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TerryM

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Re: Decline in insect populations
« Reply #200 on: November 24, 2019, 01:40:56 PM »
^^
But - But you're trampling the garden of those invested in the GreenWashing Industry.


If conferences couldn't be flown to, indulgences couldn't be paid for, and harvestable woodlots couldn't be planted to atone for others ecological sins, how would the captains to these industries support themselves.


Without Greenwashing keeping them supplied with Cuban Cigars and Gulfstream Jets think of the mischief they'd get into!
Green BAU is obviously the only way we can make progress, without being crushed by our burgeoning burden of guilt.
Terry

vox_mundi

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Re: Decline in insect populations
« Reply #201 on: January 06, 2020, 05:35:35 PM »
Researchers United on International Road Map to Insect Recovery
https://www.theguardian.com/environment/2020/jan/06/urgent-new-roadmap-to-recovery-could-reverse-insect-apocalypse-aoe
https://phys.org/news/2020-01-international-road-insect-recovery.html



International scientists formulate a roadmap for insect conservation and recovery, Nature Ecology & Evolution (2020)
https://www.nature.com/articles/s41559-019-1079-8
« Last Edit: January 07, 2020, 01:36:33 AM by vox_mundi »
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dnem

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Re: Decline in insect populations
« Reply #202 on: January 07, 2020, 12:52:02 PM »
The roadmap to insect recovery is essentially the same roadmap to avoiding environmental calamity overall.

blumenkraft

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Re: Decline in insect populations
« Reply #203 on: January 14, 2020, 11:58:01 AM »
Munich study confirms severe decline in insect populations in Germany, especially in grasslands by 67%

Link >> https://www.nature.com/articles/s41586-019-1684-3
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kassy

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Re: Decline in insect populations
« Reply #204 on: January 14, 2020, 02:28:41 PM »
In 30 forest sites with annual inventories, biomass and species number—but not abundance—decreased by 41% and 36%, respectively.

So over a third of the species are lost while abundance remains the same.
I wonder if they have a breakdown of species in the article.
Are we losing certain types of specialists over others?
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blumenkraft

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Re: Decline in insect populations
« Reply #205 on: January 14, 2020, 02:43:41 PM »
I take it they only measured biomass in regards to decline.

Quote
... Here we analyse data from more than 1 million individual arthropods (about 2,700 species), from standardized inventories taken between 2008 and 2017 at 150 grassland and 140 forest sites in 3 regions of Germany. ...

Quote
... Our results show that there are widespread declines in arthropod biomass, ...
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kassy

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Re: Decline in insect populations
« Reply #206 on: January 14, 2020, 03:04:28 PM »
No they split it in three categories but sadly it is paywalled.

The difference between the forests and grasslands is interesting and i would like to see tables with a breakdown for both.
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blumenkraft

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Re: Decline in insect populations
« Reply #207 on: January 14, 2020, 03:58:26 PM »
Kassy, there is a link to the dataset. I don't see a breakdown into categories.

>> https://www.bexis.uni-jena.de/PublicData/PublicDataSet.aspx?DatasetId=25786
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nanning

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Re: Decline in insect populations
« Reply #208 on: January 14, 2020, 06:27:05 PM »
We have here in Friesland ditches around our fields.
In my youth I loved to pole leap over ditches and I loved the beautiful biotope of life in those waters.

These days, in general all ditches are cleared. The whole biotope removed. Well, I mean the growing biotope from last years digging out.
There's hardly any life left. The fields are mono culture ryegrass, spread with biocides every year, that run-off into the ditches.

What this means in my understanding, is that because of this there are hardly any flying insects left.
I feel strongly about this.

Am I correct in assuming that most flying insects have their larvae stage under water (in a functioning biotope)?
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Ktb

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Re: Decline in insect populations
« Reply #209 on: January 15, 2020, 12:49:50 PM »
In 30 forest sites with annual inventories, biomass and species number—but not abundance—decreased by 41% and 36%, respectively.

So over a third of the species are lost while abundance remains the same.
I wonder if they have a breakdown of species in the article.

I take it they only measured biomass in regards to decline.

"We showed that arthropods declined markedly not only in biomass but also in abundance and the number of species, and that this affected taxa of most trophic levels in both grasslands and forests." - Siebold et al 2019.

No they split it in three categories but sadly it is paywalled.

The difference between the forests and grasslands is interesting and i would like to see tables with a breakdown for both.

I have access to the paper. What would you both like to see?
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blumenkraft

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Re: Decline in insect populations
« Reply #210 on: January 15, 2020, 12:51:43 PM »
Upload screenshots? ;)
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Ktb

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Re: Decline in insect populations
« Reply #211 on: January 15, 2020, 12:58:39 PM »
Quote
Much of the debate surrounding the human-induced biodiversity crisis has focused on vertebrates3, but population declines and extinctions may be even more substantial in small organisms such as terrestrial arthropods4. Recent studies have reported declines in the biomass of flying insects2, and in the diversity of insect pollinators5,6, butterflies and moths1,7,8,9,10, hemipterans11,12 and beetles7,13,14. Owing to the associated negative effects on food webs15, ecosystem functioning and ecosystem services16, this insect loss has spurred an intense public debate. However, time-series data relating to arthropods are limited, and studies have so far focused on a small range of taxa11,13,14, a few types of land use and habitat12—or even on single sites1,17. In addition, many studies lack species information2 or high temporal resolution2,12. It therefore remains unclear whether reported declines in arthropods are a general phenomenon that is driven by similar mechanisms across land-use types, taxa and functional groups.

The reported declines are suspected to be caused mainly by human land use2. Locally, farming practices can affect arthropods directly by application of insecticides18,19, mowing20 or soil disturbance, or indirectly via changes in plant communities through the application of herbicides or fertilizer21. Forestry practices can also affect local arthropod communities via changes in tree species composition or forest structure22. In addition, local arthropod populations can be affected by land use in the surrounding landscape; for example, through the drift and transport of pesticides and nitrogen by air or water23,24, through the effects of habitat loss on meta-communities (source–sink dynamics25) or by hampering dispersal.

To disentangle the local and landscape-level effects of land use on temporal trends in arthropod communities of grasslands and forests, we used data from the ‘Biodiversity Exploratories’ research programme that pertain to more than 1 million individual arthropods (2,675 species) (Extended Data Table 1). Arthropods were collected annually at 150 grassland sites by standardized sweep-net sampling in June and August from 2008 to 2017, and at 30 forest sites with flight-interception traps over the whole growing period from 2008 to 2016. An additional 110 forest sites were sampled in 2008, 2011 and 2014 to test for trends across a larger number of sites. Both the grassland and the forest sites cover gradients in local land-use intensity. Land-use intensity was quantified in the form of compound indices that are based on grazing, mowing and fertilization intensity in grasslands26, and on recent biomass removal, the proportion of non-natural tree species and deadwood origin in forests27. To analyse landscape-level effects, we quantified the cover of arable fields, grassland and forest in circles, with a radius between 250 m and 2 km, around each sampling site. We modelled temporal trends in arthropod biomass (estimated from body size; Methods), abundance and the number of species separately for grasslands and forests, and tested for the effects of local and landscape-scale land-use intensity on these trends, accounting for weather conditions. Analyses were conducted for all species together, and for different dispersal and trophic guilds.

The total number of arthropod species across all sites (gamma diversity) was substantially lower in later than in earlier years in both forests and grasslands (Fig. 1). Gamma diversity, biomass, abundance and number of species fluctuated over time but revealed an overall decrease with strongest declines from 2008 to 2010, especially in grasslands (Fig. 1). Year-to-year fluctuations in arthropod biomass, abundance and number of species were partially explained by weather conditions (Extended Data Fig. 1, Supplementary Table 1-1, Supplementary Information section 2). Accounting for weather, fitted trends from our models showed declines in biomass of 67% for grasslands and 41% for forests, declines in species numbers of 34% for grasslands and 36% for forests, and declines in abundance of 78% for grasslands, with no significant change in abundances for forests (−17%) (Fig. 1, Supplementary Table 3-1). In grasslands, declines occurred consistently across all trophic guilds (herbivores, myceto-detritivores, omnivores and carnivores), although the trend for carnivores was not significant (Supplementary Table 1-1). In forests, the patterns were more complex: herbivores showed an increase in abundance and species number, whereas all other trophic guilds declined. Temporal trends of arthropods on the basis of data recorded in 3-year intervals from all 140 forest sites were similar to the trends based on the 30 sites with annual data (Supplementary Table 1-1). Sensitivity analyses that removed or reshuffled years showed that the decline was influenced by, but not solely dependent on, high numbers of arthropods in 2008. Fluctuations in numbers (including the numbers from 2008) appear to match trends that have been observed in other studies2, which suggests that the recent decline is part of a longer-term trend that had begun by at least the early 1990s (Extended Data Fig. 2, Supplementary Information section 3). Further sensitivity analyses showed consistent declines when data from individual sampling dates were not aggregated per year, and also showed that declines concerned all three regions that we analysed (Supplementary Tables 3-2, 3-3, Supplementary Fig. 3-1).

Fig. 1: Temporal trends in arthropod communities.
figure1
a–d, Gamma diversity (total number of species across all grassland or forest sites) (a), biomass (b), abundance (c) and number of species (d) of arthropods were recorded in 30 forest and 150 grassland sites across Germany. Gamma diversity shows mean incidence-based, bias-corrected diversity estimates (Chao’s BSS, that is, the higher value of the minimum doubled reference sample size and the maximum reference sample size among years29) for q = 0 and 95% confidence intervals derived from bootstrapping (n = 200). Non-overlapping confidence intervals indicate significant difference30. Box plots show raw data per site and year (n = 1,406 (grassland) or 266 (forest) independent samples). Solid lines indicate significant temporal trends (P < 0.05) based on linear mixed models that included weather conditions, and local and landscape-level land-use intensity as covariates. Shaded areas represent confidence intervals. Boxes represent data within the 25th and 75th percentile, black lines show medians, and whiskers show 1.5× the interquartile range. Data points beyond that range (outliers) are not shown for graphical reasons. Plots for biomass and species number have separate y axes for grassland and forest.

Full size image
Linking changes in biomass, abundance and the number of species to one another enables further inferences regarding the mechanisms that drive arthropod declines. In grasslands, both abundant and less-abundant species declined in abundance (Fig. 2), but loss in the number of species occurred mostly among less-frequent species (Fig. 1, Extended Data Fig. 3, Supplementary Information section 4). This suggests that the decline in the number of species in grasslands was attributable mainly to a loss of individuals among rare species. In forests, species that were initially less abundant decreased in abundance, whereas some of the most abundant species—including invasive species and potential pest species—increased in abundance (Fig. 2, Supplementary Table 5-1). The loss of species was, however, irrespective of their frequency (Fig. 1, Extended Data Fig. 3, Supplementary Information section 4). This suggests that the decline of arthropods in forests is driven by mechanisms that negatively affect the abundances of many species, which leads to an overall decline in biomass and the number of species but favours some species that are able to compensate declines in abundance.

Fig. 2: Changes in the dominance of species.
figure2
Rank abundance curves of arthropod communities for the first two (2008–2009) and final two (2016–2017 for grasslands and 2015–2016 for forests) years of the study, from 150 grassland and 30 forest sites. The insets show enlarged curves for the 30 most-abundant species. Data from the first two and final two study years were pooled (abundances are the total number of individuals of a species observed over two years). Declines in abundance are highlighted by yellow shading, and increases in abundance are shaded in green. The y axes are log-scaled, but show untransformed values.

Full size image
The magnitudes of declines in biomass, abundance and the number of species in arthropod communities were independent of local land-use intensity (Supplementary Table 1-1) as well as changes in plant communities (Supplementary Information section 6) at all sites. However, in forests declines in the number of species were weaker at sites with high natural or anthropogenic tree mortality, possibly owing to increased heterogeneity in local habitats (Extended Data Fig. 4). Landscape composition had no effect on arthropod trends in forests (note that forest sites covered only limited gradients of the landscape variables, Extended Data Fig. 5), but it mediated declines in the number of species in grasslands: the magnitude of the declines increased with increasing cover of arable fields, and marginally increased with cover of grasslands in the surrounding landscape (Fig. 3, Supplementary Table 1-1). This suggests that major drivers of arthropod decline in grasslands are associated with agricultural land use at the landscape scale.

Fig. 3: Landscape effects on arthropod decline in grasslands.
figure3
a, Temporal changes in biomass, abundance and the number of species for all arthropod species. b, c, Temporal change in biomass of species with high (b) or low (c) dispersal ability, conditional on the cover of arable fields in the surrounding landscape (1-km radius). The decline in biomass increased significantly with the cover of arable fields for weak dispersers, but not for strong dispersers. Slopes were derived from models that included weather conditions and local land-use intensity as covariates. The y axes are log-scaled, but show untransformed values.

Full size image
The interaction between a species and the landscape around its habitat depends on its dispersal ability, which ultimately determines its occurrence and persistence28. In grasslands, taxa of high and low dispersal ability (Methods) both declined, but an increasing cover of arable fields—although not of grasslands—in the surroundings amplified declines in the biomass of weak dispersers more strongly than it did declines of strong dispersers (Fig. 3, Supplementary Table 7-1). Weak dispersers may experience higher mortality during dispersal, and thus have a lower chance of (re)colonization of a particular site when arable field cover is high. In forests, strong dispersers declined in biomass, abundance and the number of species, whereas weak dispersers increased in abundance and biomass—but less strongly when grassland cover in the landscape was high (Supplementary Table 7-1). This suggests that the drivers behind arthropod declines in forests also act at landscape-level spatial scales.

We showed that arthropods declined markedly not only in biomass but also in abundance and the number of species, and that this affected taxa of most trophic levels in both grasslands and forests. Declines in gamma diversity suggest that species might disappear across regions. Our results also indicate that the major drivers of arthropod decline in both habitat types act at landscape-level spatial scales, but that declines may be moderated by increases in heterogeneity of local habitats in forests. Although the drivers of arthropod decline in forests remain unclear, in grasslands these drivers are associated with the proportion of agricultural land in the landscape. However, we cannot ascertain whether the observed declines are driven by the legacy effects of historical land-use intensification or by recent agricultural intensification at the landscape level; for example, by the decrease of fallow land and field margins rich in plant species, the increased use of pesticides or use of more potent insecticides (Supplementary Information section 3). Time-series data relating to changes in the use of agrochemicals or the presence of fine-scale arthropod habitats would be necessary to answer this question. Furthermore, the extents to which changes in climate have reinforced the observed trends in arthropod biomass, abundance and number of species is unclear (Supplementary Information section 2). Our results show that widespread arthropod declines have occurred in recent years. Although declines were less pronounced during the second half of our study period, there is no indication that negative trends have been reversed by measures that have been implemented in recent years. This calls for a paradigm shift in land-use policy at national and international levels to counteract species decline in open and forested habitats by implementing measures that are coordinated across landscapes and regions. Such strategies should aim to improve habitat quality for arthropods and to mitigate the negative effects of land-use practices not only at a local scale (within isolated patches embedded in an inhospitable agricultural matrix) but also across large and continuous areas.
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kassy

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Re: Decline in insect populations
« Reply #212 on: January 15, 2020, 02:46:11 PM »
Thanks blumenkraft.
Too bad the actual dataset did not extract (path too long).


And big thanks Ktb! I would like the post twice if that was not counterproductive.  :)

This was mostly what i was wondering about:

In grasslands, declines occurred consistently across all trophic guilds (herbivores, myceto-detritivores, omnivores and carnivores), although the trend for carnivores was not significant (Supplementary Table 1-1). In forests, the patterns were more complex: herbivores showed an increase in abundance and species number, whereas all other trophic guilds declined.
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wdmn

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Re: Decline in insect populations
« Reply #213 on: January 25, 2020, 06:18:31 AM »
Mayfly numbers drop by half since 2012, threatening food chain

https://www.nationalgeographic.com/animals/2020/01/mayfly-insect-populations-in-decline

EVERY SUMMER, MAYFLIES burst forth from lakes and rivers, taking to the skies of North America. These insects, which are particularly abundant in the northern Mississippi River Basin and Great Lakes, live in the water as nymphs before transforming into flying adults. They synchronize their emergence to form huge swarms of up to 80 billion individuals—so massive that, in waterside towns, they are sometimes scooped up with snowplows.

These insect explosions provide food for a wide variety of animals, from perch and other commercially important freshwater fish to birds and bats. But new research shows that mayflies are in decline. Since 2012, mayfly populations have declined by more than 50 percent throughout the northern Mississippi and Lake Erie, likely due to pollution and algal blooms, according to a study published today in Proceedings of the National Academy of Sciences.

...

The study revealed that between 2015 to 2019, populations of burrowing mayflies in the genus Hexagenia declined by an incredible 84 percent in western Lake Erie. In the nearby northern Mississippi River Basin, from 2012 to 2019, they declined by 52 percent.

These dropping populations are significant because the insects are an important link in the food chain, serving as prey for a variety of predators. They also transfer tons of nutrients from the water to the land, a valuable ecological service.


edit: thanks for the heads up kassy
« Last Edit: January 25, 2020, 02:26:41 PM by wdmn »

kassy

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Re: Decline in insect populations
« Reply #214 on: January 25, 2020, 10:23:40 AM »
Those are some horrible numbers.  :(

Please edit the link down to this format since all the rest is tracking crap:
https://www.nationalgeographic.com/animals/2020/01/mayfly-insect-populations-in-decline
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TerryM

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Re: Decline in insect populations
« Reply #215 on: January 25, 2020, 12:08:24 PM »
We had a cottage at Lake Erie in the 50's. The screens had to be cleaned twice a season to clear out the dead mayflies. I was alarmed when I went back to the cottage in the early 2,000's and couldn't find a single one, alive or dead.


A friend of mine who makes movies in the North Bay region assures me that they're alive and well in the north. She apparently spends half her day cleaning lenses and shooting around the swarms. :)
The local loss of mayflies is a huge loss of available protein. I hope the predators have been able to follow their prey.


Last summer I spotted a single monarch butterfly at Port Dover. I hope they've found a new flyway.
Terry

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Re: Decline in insect populations
« Reply #216 on: January 25, 2020, 01:24:52 PM »
TerryM:
Are you sure it wasn’t a Viceroy? I almost got fooled by one in my grade school insect collection.
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Re: Decline in insect populations
« Reply #217 on: January 25, 2020, 03:18:36 PM »
^^
AHA!
Now we know why there's been a decline!

;) ;D
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TerryM

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Re: Decline in insect populations
« Reply #218 on: January 25, 2020, 05:19:07 PM »
TerryM:
Are you sure it wasn’t a Viceroy? I almost got fooled by one in my grade school insect collection.


I'd never heard of the "Viceroy", and can't tell the difference from the photos.


In the 50's we had millions of monarchs in the milkweed field just down from our property. I'd clap my hands loudly and they'd darken the sky, the caterpillars were everywhere.


This appeared to be a monarch that was totally exhausted. It alit on my towel to rest which gave me a chance to look it over before it took off. Parts of its wings were missing as if it had been caught out in a bad storm, I doubt that it lasted the day.


It's the only thing I've seen that looked like a monarch since I've been back, but a friend with a farm closer to the lake told me he'd sited plenty last spring.


Perhaps a return?
Terry

kassy

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Re: Decline in insect populations
« Reply #219 on: January 25, 2020, 06:35:08 PM »
This happened in Mexico:

In Mexico, 53 local police officers are being questioned over the disappearance of environmental activist Homero Gómez.

Mr Gómez, who manages a butterfly sanctuary in the central town of Ocampo, was last seen on 13 January.

...

Mr Gómez is a tireless campaigner for the conservation of the monarch butterfly and the pine and fir forests where it hibernates.

...

The sanctuary Mr Gómez manages near Ocampo opened in November as part of a strategy to stop illegal logging in the area, which is a key habitat for the monarch butterfly.

https://www.bbc.com/news/world-latin-america-51205114

RIP Mr Gómez.

Ofc the next target is the trees...
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nanning

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Re: Decline in insect populations
« Reply #220 on: January 26, 2020, 07:16:55 AM »
^^
"Ofc the next target is the trees... "

In my view, loggers really don't see trees, which are lifeforms. They see only a job, resources, wood and dollar$.
Pressing buttons to let high tech do the difficult destruction for them. Without high tech humans can't fell a tree.

If there's opposition, no problem, the loggers'll start an old fashioned violent conquering. I ask myself, what's the difference with neo-colonialism? In the end it's all about resources and conquering, and grown-up's social hierarchy.

Loggers are another symptom of civilisation.
They use technology they don't understand and that they can't create themselves. That goes for almost all technology. Users don't understand it and can't create it themselves. Pressing or swiping or switching magic buttons.
e.g. Computertech is magic to >90% of humans.
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Re: Decline in insect populations
« Reply #222 on: February 01, 2020, 04:35:17 PM »
Quote
When rearing the moths, developers incorporated what they call a self-limiting gene that makes female offspring die shortly after hatching.
Typically, tetracycline, an antibiotic used to suppress the gene, is included in the moths' diet so that female moths can be produced as well.
"However, when you want to release populations of males, you do not include tetracycline," Shelton said. "So all the female larvae that are feeding on the artificial diet will die. And then you'll just have thousands and thousands of males which you can release in the field."

They could maybe find some spot with tetracyclin pollution...

Paper is paywalled.

A review on pollution situation and treatment methods of tetracycline in groundwater

ABSTRACT
Tetracycline antibiotics (TCs) are widely used all over the world in recent decades. TCs are a family used as broadspectrum antibiotics and animal veterinary drugs. Among the TCs, tetracycline (TC) is the most use. Due to the rapid development of antibiotics industry, the dosage standards of TC are not yet clearly defined in most countries and regions. TC is hard to degrade in living organisms and can even be converted to more toxic substances. The overuse and wanton discharge of TC, also caused serious pollution of groundwater. This article attempts to summarize the latest knowledge on the nature, sources, pollution status, the impact on water environment toxicity of TC respectively. Meanwhile, there are many technologies to remove TC. This paper mainly included 12 kinds of degradation methods, including photodegradation, microbial removal, adsorption, electrochemical and sludge digestion. This review will provide a reference for the study of the basic properties and removal methods of TC.
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kassy

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Re: Decline in insect populations
« Reply #223 on: February 03, 2020, 12:48:22 PM »
In a follow up to #219:

A second activist campaigning for the conservation of monarch butterflies and the woods in which they hibernate has been found dead in Mexico.

Raúl Hernández worked as a tour guide at a butterfly sanctuary in Michoacán state.

His body, which bore signs of beatings and a head injury, was found two days after the funeral of Homero Gómez.

Mr Gómez managed a monarch butterfly sanctuary in the same state and had received threats, his family said.

more on:
https://www.bbc.com/news/world-latin-america-51356265
Þetta minnismerki er til vitnis um að við vitum hvað er að gerast og hvað þarf að gera. Aðeins þú veist hvort við gerðum eitthvað.

Ktb

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Re: Decline in insect populations
« Reply #224 on: February 07, 2020, 07:15:57 AM »
Ktb's note -- don't feel like adding the graphics at this time. Exhausted. May return at a later date to upload the graphs/images.

Paper is paywalled.

A review on pollution situation and treatment methods of tetracycline in groundwater

Introduction
In recent years, the use of drugs has increased yearly, and the situation of drug abuse has become more serious, which caused the drug remained in the environment. Meanwhile, the residual drug in the environment was relatively stable and difficult to handle by conventional methods. Among the numerous drugs which existed in the environment, antibiotics were widely used in the world.

In the past few decades, the use of drugs was growing rapidly. Tetracycline antibiotics (TCs) were the most common antibiotics all over the world. TCs are a family of broad-spectrum antibiotics produced or semi-synthesized by actinomycetes and they are effective against to Gram-positive and Gram-negative bacteria as well as against a variety of bacterial infections. TCs are a class of tetrahydrobenzene derivatives with a dibasic tetraphenyl base structure. TCs mainly contain TC, oxytetracycline and chlortetracycline. The overall structure of oxytetracycline was found by Woodward et al. (1947) by chemical degradation and infrared spectroscopy.[1] Chlortetracycline is isolated from the culture medium of Streptomyces spp. TC is obtained by getting rid of the chlorine atom of the chlortetracycline.[2] TC plays an important role in TCs, it’s also the largest proportion of in TCs. TC also has many advantages, such as, low prices, high quality. TC has also many advantages such as low production prices and could be synthesized with great purity. However, TC is difficult to be absorbed by animal metabolism, most of which is in the form of maternal compounds discharged into the environment by the excrement. It can be residual in the water for a long-term.[3] The amount of TC in most countries of the world has no clear rules. The uncontrolled usage of TC and its arbitrary released into the environment pose a certain threat to the ecological environment. TC affects the development of teeth, bones and also has certain hepatotoxicity. The researcher found that high levels of fecal waste might bring huge pollution problems once they came into groundwater.[4] TC excreted by human and animal enters the water environment. It could cause water pollution, after infiltration, leaching, and other processes. The contents of TC in surface water and groundwater were more than 100.00 ng/L in the wet season in Hanjiang plain.[4]

Research of TC pollution to groundwater and its treatment technology are great significance to human health. TC was detected at a concentration of 184.2 ng/L in shallow groundwater in china.[5] Although TC is not easy to cause acute toxicity in normal circumstances, long-term exposure to TC in water environment may be the potential for chronic toxicity to non-target organisms.[3] In order to solve the residual TC, researchers used variety methods to deal with TCs in groundwater.[6] Most removal methods of TC could not directly remove groundwater pollution. Generally, TC is removed indirectly by wastewater, and the methods also applied to drinking water. There were various methods of TC removal in water environment, and their degradation efficiency was different. This article described the commonly used TC removal methods included, photodegradation, microbial degradation, phytodegradation, adsorption processes and electrochemical processes.[7] The new methods of TC degradation include sludge digestion technology, membrane processes, advanced oxidation processes, hydrolysis process, ultrasonic degradation, low-temperature plasma technology and soil infiltration system.[8] This article indicated the status, amount, source, toxicity, and removal methods of TC in groundwater. It would provide a reference for the property and treatment of TC in groundwater.

Physicochemical properties of TC
TC is mainly synthetized as an odorless yellow crystalline powder. TC is slightly soluble in water, lower in alcohols (methanol, ethanol, etc.), and insoluble in organic solvents.[9] TC is dissolved in dilute acid and dilute alkali. TC antibiotic is stable in the air, but it is easy to absorb moisture. The case of sunlight can change the color of TC. The efficacy of TC will be significantly reduced or even produce toxicity. TCs have similar physicochemical properties, such as the similar chemical structure and molecular weight. The differences among TCs are the groups of R1 and R3, which are shown on Table 1. The main physical and chemical properties of TCs are shown in Fig. 1. TC mainly consists with four carbocycles, which contains dimethylamino group (N(CH3)2), acylamino group (CONH2), phenolic hydroxyl group (C-OH), a ketone group (C = O) and an enol group conjugate double bond system at the same time. TC is a kind of quaternary weak acid, there are four kinds of forms in aqueous solution. When the pH is less than 3.3, the dimethylamino group in the TC molecular structure is protonated, mainly in the presence of cation TCH3+. When the pH value is 3.3–7.7, the TC molecules in the phenolic ketone group lost protons, with zwitterions TCH2±. When the pH value is more than 7.7, the TC molecules is in the form of anion TCH2− or the divalent anion TC2-.[12,13] The different forms of TC according to pH are shown in Fig. 2.

Table 1. The molecular weight and molecular formula of tetracycline antibiotics.

CSVDisplay Table
Figure 1. The structural formula of tetracycline.


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Figure 2. The presence of TC in different pH conditions.


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The source and pollution conditions of TC
The amount of TC was not clearly defined in the initial. Therefore, the abuse of TC has emerged in the world. China’s total antibiotic production reached 21000 tons in 2009, accounts for about half the world’s consumption.[14,15] Because of the broad spectrum of antibacterial and stable naphthalene ball structure, TC was difficult to degrade.[16] A small fraction of TC came into the body to produce inactive products through metabolic reactions such as cleavage and glucuronidation.[17] The antibiotic metabolites that excreted from the body were still biologically active, and they could form a matrix in the environment and even produce more degraded substances than pre-degraded.[18,19] About 69–86% of the TC antibiotics were excreted through the urine and feces of the human body and animals, then they were released into the environment in an active form.[18] TC has a high degree of hydrophilicity and low volatility, with significant persistence in water environment. The inappropriate use of TC poses a threat to human health and ecological security. TC carried in the feces contacts the soil and further enters the surface water. In the long run, TC in surface water penetrates into groundwater. At present, the control of the groundwater environment is still not perfect. TC entering the groundwater is difficult to detect. It is difficult to identify the pollutants and sources when groundwater is contaminated. Therefore, it is imperative to study the source of TC and its pollution in groundwater.[20]

The source, the use, and the pollution situation of TC
The source of TC contamination is mainly from human and veterinary drugs. The main source of TC contamination is shown in Fig. 3. As for human drugs, TC enters into human body through the way of injection and oral consumption. However, due to the lack of restraint mechanisms, antibiotics were used without abstinence. The antibiotics were discharged randomly, and made the adverse effect. There are three main sources of antibiotic pollution. The first source is the unused expired antibiotic used from the medical institution. Secondly, medical institutions have left antibiotics in discarded medical devices. Thirdly, the excrement of patient’s also carries raw antibiotics and metabolized antibiotics.[21] These unused antibiotics discharge into the environment through the urban sewage system. On the one hand, the antibiotics in treated wastewaters infiltrate in soils and surface waters, and enters into the groundwater indirectly. On the other hand, they enter the urban sewage treatment system. The existing sewage treatment technology can not completely remove the antibiotics. The biochemical treatment of wastewater in the microbial growth has a strong inhibitory effect, so the antibiotics are difficult to degradation.[22,23] Once the antibiotic into the surface water, they will cause pollution of the water environment.

Figure 3. The migration of antibiotics in water environment.


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As for veterinary drugs, TC is often used as feed additives into animal. The use of antibiotics in animal husbandry and aquaculture are the two main sources of veterinary antibiotics. These antibiotics will also be into the water environment in the form of the animal excretion. According to the statistics, most of livestock and aquaculture exist in rural areas. Sewage treatment system is lacked in rural areas, so the fecal matter goes directly into surface water. TC issued from veterinary drugs does not reach directly groundwater. On the one hand, wastewaters containing TC are discharged in surface waters. Then, TC migrates to hyporheic zone and finally reaches groundwater. On the other hand, wastewaters can be discharged on soils and then they penetrate in the non-saturated zone. In consequence, TC infiltrates through the vadose zone before to reach groundwater.

In 1950s, the US Food and Drug Administration (UFA) formally approved the application of TC antibiotics to animal feed additives at first.[16] Because of the broad-spectrum and low prices, TCs has been widely promoted in the animal husbandry.[24,25] Statistically, the European Union annual production of antibiotics is about 5,000 tons, accounting for 46–50% of the total antibiotics.[9] Britain produces 438 tons of antibiotics each year, the production of TCs is 228 tons, accounting for 52% of the total antibiotics.[9] As for China, the production of TCs is about 97,000 tons, accounting for 46% of the total antibiotics.[9]

Antibiotics have created enormous economic benefits in human health and the development of animal husbandry.[26] TCs are widely used in veterinary drugs and treated for gastrointestinal tract, respiratory tract, skin infections, and sepsis and other diseases.[27,28] Taking TC veterinary drugs as an example, the total amount of TC antibiotics around the world is shown in Fig. 4. In recent years, people have found some new uses of TC antibiotics, especially non-antibacterial effects.[29] TC treatment of type Ⅲ prostatitis infected by Nanobacteria.[30] Injection of TC hydrochloride as a hardening agent, adjuvant treatment of malignant pleural effusion, treatment of liver and kidney cysts and other diseases.[31] TC and minocycline can be used as anti-osteoporosis drug.[32] Dr. Maria Amy (a medical researcher in New York State University) reports that Periostat (doxycycline monohydrate) is effective in the treatment of chronic gingivitis.[33]

Figure 4. The total amounts (tons) of TCs used for veterinary purposes around the world.


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The water pollution by antibiotics is a combination of point source and surface source emissions.[34] Because antibiotics are hydrophilic and low volatility, their main migration in the environment is through water and food transfer.[35,36] For instance, in China, most of groundwater pollution problems exist in the livestock and poultry breeding and aquaculture of rural China. There are several common problems, for example, the selection of farm site is not standardized, animal feces, and sewage discharge is not up to standard pollution prevention and control. The average content of residual TC in pigs is 9.09 mg/kg.[37] The Ministry of Agriculture of the People’s Republic of China indicated that China’s annual livestock and poultry manure production is about 3.80 billion tons in 2016, however, the comprehensive utilization rate is less than 60%.[38] High levels of fecal waste might bring huge pollution problems once they come into the groundwater. These problems are superimposed on causing serious damage to TC antibiotics in surface water and groundwater of rural areas.[39]

At present, most countries and regions of the groundwater TC antibiotic pollution have not been systematically detected. And the literature of detection is very little. The researchers in Beijing Normal University, (2015) had a test to part of the surface water sampling in China.[40] They found that antibiotic content is amazing. The detection results of 19 kinds of sulfonamides, fluoroquinolones, TC, and macrolide in the Jianghan Plain in the surface water and groundwater in the dry season and the wet season shows that, the maximum concentrations of chlortetracycline in surface water and groundwater are 122.30 and 86.60 ng/L, respectively.[41] The contents of TC, ofloxacin, norfloxacin, and erythromycin in surface water and groundwater are more than 100.00, 135.10, 134.20, and 381.50ng/L, respectively.[41]

Toxicity
Effects of TC on aquatic animals in water environment
TC is difficult to cause acute toxicity, however, the long-term exposure to antibiotic in the environment may be the potential for chronic toxicity to non-target organisms. The widely use of TCs has caused the effect of micro-organisms in the terrestrial environment and plant growth.[42] The bacteria in natural environments can transmit antibiotic-resistant genes, which has the potentially threatens in ecosystem and human health.[43] on the other hand, the antibiotic resistance gene is found in the environment and it was characterized as a new type of contaminant. Zhu et al. (2017) published an essay in Science.[44] This article described the antibiotics as a pollutant during the water and soil microbial migration process. In order to resist antibiotics and other pollutants “threat”, the microbes had to occur gene mutation or gene lateral transfer. They gradually produce “resistance” to take the initiative to respond to a changing environment.[45] Therefore, the global antibiotic resistance problem has reached an urgent point.

Wollen-berger et al. (2000) conducted acute and chronic toxicity tests on freshwater crustacean large fleas in fisheries according to the standard protocol (ISO, 1989b) of the flea acute toxicity test.[46] This experiment used 9 kinds of antibiotics including TC antibiotics. The results showed that TC NOEC50 (No observed effect concentrations) was 340 mg/L (the highest effective concentration for parent animals and propagation was considered as NOEC). In acute toxicity experiments, the antibiotics had a mass concentration that affected the reproductive performance of large fleas, several times lower than the acute toxicity concentration. In the chronic toxicity test, the EC50 (concentration for 50% of maximal effect) of TC was 44.80 mg/L and the EC50 of oxytetracycline was 46.20 mg/L.[46]

Ferreira et al. (2007) conducted a toxicity test on the use of microalgae Tetraselmis chuii and the crustacean Artemia parthenogenetica.[47] TC can cause toxic effects on aquatic organisms. The results showed that IC50 (half maximal inhibitory concentration) of TC at 24 and 48h were 870.47 mg/L (95% confidence interval: 778.83–983.66 mg/L) and 805.99 mg/L (95% confidence interval: 650.71–1129.00 mg/L), respectively. And the NOEC and lowest observed effect concentration values were 637  and 828 mg/L, respectively.[47]

The research results above are mostly based on acute toxicity experiments, and they cannot fully feedback TC antibiotics toxicity. In recent years, due to the impact of experimental costs and ethics, the researchers use alternative research methods for acute toxicity test. Researchers try to reduce the use of larger animals such as fish and shellfish.[48] This is a method of innovation in TC antibiotics for aquatic animals. Sanderson et al. (2003) used quantitative structural relationships and compared the lowest predicted concentration to the highest detection concentration with obtain the ecotoxicity data of the contaminants.[49] The risk factor of a series of antibiotics (the ratio of the detected concentration of the predicted toxicity) can be obtained in this way. For example, the risk factor of TC was 6.88 × 10−6, and the risk coefficient of oxytetracycline was 2.13 × 10−5. The European Commission has proposed using the risk factor to evaluate the potential environmental risk of a drug by responding to the ratio of predicted environmental concentration to predict no-effect concentration. When the ratio is bigger than 1, it indicates a high risk.
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Ktb

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Re: Decline in insect populations
« Reply #225 on: February 07, 2020, 07:16:50 AM »
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Another alternative research method is called as vitro testing,[50] which found that the enzyme activity as a sub-lethal toxicity test indicators could also provide ecological toxicity estimates.[51,52] Babin et al. (2005) tested the toxicity of TC antibiotics (mainly for oxytetracycline and TC) to fish, using fish RTG-2 and RTL-W1 cell lines for test tube toxicity testing.[10] This operation replaces the direct toxicity test. The activity of EROD (ethoxyresorufin-O-deethylase) and β-galactosidase activity were used as toxic endpoints, and the oxytetracycline and TC solutions were used in order. The test showed that TC and oxytetracycline inhibited the activity of EROD and β-galactosidase. The EC50 of EROD in TC was 167.63mg/L, and the EC50 of β-galactosidase in TC reached 84.59 mg/L.[10] So the toxicity of oxytetracycline was slightly lower than that of TC.

Effects of TC on plants in water environment
Holling-Sorenson et al. (2000)[11] and Holten et al. (1999)[53] used toxicological tests on Microcystis aeruginosa, Chlorella algae using TC antibiotics in different fisheries. The contents of TC in M. aeruginosa was higher than in green algae. Holling-Sorenson showed that TC drugs were toxic or medium toxic chemicals in aquatic algae.[11] In addition, Jiang et al. (2010) also studied the toxic effects of TC on the photosynthesis and antioxidant enzyme activities of M. aeruginosa.[54] Authors thought that TC could hinder the photosynthesis of M. aeruginosa.[54] At the same time, the inhibitory effect increases with the increase of TC concentration. TC will destroy the antioxidant enzymes and inhibit the growth of algae eventually.

Effects of TCs on microbes in water environment
Dijek et al. (1976) studied the effects of 21 antibiotics including TC on 36 typical microbes in water.[55] The results showed that only 7 kinds of microorganisms were sensitive to antibiotics, and the other 29 species had natural resistance to common antibiotics. Back-haus et al. (1999) studied the five commonly used antibiotics using the long-term bioluminescence inhibition test of Vibrio spp.[56] The results showed that the above antibiotics were highly toxic, most of the EC50 are less than 1 mg/L. Tetracycline hydrochloride was the most potent in all 20 tested antibiotics. The EC90 (concentration for 90% of maximal effect), EC50 and EC10 (concentration for 10% of maximal effect) of TC hydrochloride were 0.0738 ng/L, 0.025 mg/L, 0.0046 mg/L, respectively.[57]

Degradation methods of TC
Photodegradation
Photodegradation refers that a molecule absorbs energy of lights into an excited state and causes various reactions. TC directly absorbs photons and leads to the light reaction which called direct photodegradation. Adding the light-absorbing substance, the light reaction is called indirect photodegradation.[58] Verma et al. (2007) studied the degradation of TC in sterilized water and found that the half-life of TC was 2 days under light conditions while 18 days under dark conditions.[59] This study had confirmed by other researchers, Garcia-Rodriguez et al. (2013) studied found that TC in water could be removed by photodegradation.[60] The molecular structure of TC determines whether the antibiotic can undergo photodegradation. TC molecules contain amido group (CONH2) whose carbon-nitrogen bond (C-N) is easily fracture into substances which called amino under the photodegradation reaction.[18] The efficiency of direct photodegradation of TC is low. Some researches had proved that under natural light and ultraviolet light the degradation ratio of TC after 1h were 27.2% and 73.2%, respectively.[61] Photosensitizer, as a light energy carrier, can change the light stability of compounds, thereby accelerating the photolysis. Strong photosensitizer can accelerate the photodegradation of TC by capturing free radicals in the TC reaction system that photosensitizer could catch ·O2−, H+ and ·OH. In nature environment, indirect photodegradation is the main way of the degradation of TC. There are widely photosensitizers in nature, such as humus, vitamin B2, NO2−, Fe3 +, Fe2 +, NaCl and TiO2. The mechanisms of photosensitizer how to accelerating the photodegradation of TC are similar, for example, TiO2 can rapidly improve the photodegradation rate of TC. Only under the ultraviolet light, visible light and long wave ultraviolet light irradiation, it is almost undetectable that degradation of TC. However, TC degraded 50% at 10min with TiO2(0.5g/L).[62] Under the sunlight and mercury lamp, the removal ratio of TC could achieve 80% after 30 min with TiO2 and ZnO at the same time.[63] TCs mainly adsorb on the surface of TiO2 and occur photocatalytic oxidation which conform the first-order reaction kinetic equation. This adsorption process plays a controlling role in the overall photodegradation.[64] In nature, the photodegradation of TC is greatly influenced by pH. At different pH conditions, the molecular structure of TC has dissociable functional groups that morphology is different. The negative ions are unstable so that they could easily absorb photons and occur photodegradation. With the increase of pH, the photodegradation of TC is enhanced and the alkaline conditions are more favorable for the photodegradation of TC.[65] Oxygen-free radicals are another important factor, which could affect the photodegradation of TC. TCs generate riboflavin (Rf) and superoxide radical anion (·O2−) by transfer of ground-state electron, stimulate the triplet (3Rf*), and then transfer the energy to the dissolved oxygen, at the same time produce singlet molecular oxygen, thereby promote TC degradation.[66] Besides, the photodegradation of TC is also affected by light intensity, light time, initial concentration and ionic strength.[67] Though photodegradation reaction is quick and efficient, making a large area of ultraviolet light and other light source is difficult and adding photosensitizers may have side effects. Therefore, the production and control of light sources, suitable photosensitizers and multi-component combinations to cope with wastewater are the focus in the future research.

Microbial degradation
Microbes can change the structure and physico-chemical properties of TC, which is degradation of TC from macromolecules into small molecule compounds until it converts to H2O and CO2.[68] In the degradation of TC, drug-resistant bacterium plays an important role that can directly destroy and modify the TC and make it inactivated. Several typical bacteria are shown in Table 2. There are about three kinds of degradation mechanisms of TC as follows.[72] First, hydrolysis, drug-resistant bacterium cause that TC lose their activities by enzymes eliminating chemical bong which are easily to hydrolyze and sensitive, such as the amide bond. Acetylation, acetylation is a common mechanism for bacteria to inactivate TC. Drug-resistant bacterium causes TC to lose target-binding ability and makes them inactivated by covalent modification of active groups of TC such as hydroxyl or amide groups of TC. Third, the redox is a vital mechanism for degradation of TC. TC can be oxidized by resistant enzyme, which called TetX. Related studies have shown that the addition of exogenous microorganisms into pig manure can improve the degradation of TC.[73] Microbial degradation, which is highly effective, is difficult to screening of microbial strain and control of combination conditions of compounds. At present, microbial degradation is widely used in the composting and wastewater treatment process.[74]

Table 2. Degradation of tetracycline by several typical plants.

CSVDisplay Table
Phytodegradation
Plants can degrade TC through direct absorption, exudate of root, and microbial transformation of root system.[75] There are typical plants shown in Table 3. Phytodegradation may be the most viable method to fundamentally remediate the wastewater contaminated by TC. The most common ways of phytodegradation are filter bed of aquatic plant and wetland remediation system.[83] Eichhornia crassipes could remove TC in water, and it can remove 80% TC when the concentration of TC was less than 2.5mg/L. However, the removal of TC in water by aquatic vegetables effects by season. In summer, the TC removal efficiency of cress filtration system was significantly higher than that of spinach filtration system, and the TC removal rates were 71.83 and 33.28%, respectively. While in winter, there was no significant difference in TC removal rates between them.[71] There are many advantages of aquatic plant filter bed, such as it could remove TC without chemical reagents and secondary pollution, low costs, and efficient. However, aquatic plant filter bed needs the large area and may produce stink. Therefore, this technology is more suitable for degradation of TC in wastewater in oxidation ponds around large scale farms and towns.[84] When using the constructed wetland to remove TC, the removal efficiency of TC by different wetland plants is different, and the accumulation of TC was different in different parts of wetland plants.[85] In addition, the matrix property of artificial wetland and its relationship with other structural elements should be considered.[86] Though there are several common matrix, such as slag, cinder, clay, and zeolite, the selection of artificial wetland matrices for TC removal is still to be studied in the future.

Table 3. Degradation of tetracycline by several typical fungus.

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Table 4. Degradation of tetracycline by membrane processes.

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Table 5. Degradation of tetracycline by adsorption processes.

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Table 6. Degradation of tetracycline by advanced oxidation processes.

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Table 7. Degradation of tetracycline by electrochemical process.

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Sludge digestion technology
Li et al. (2013)[96] studied the removal of trace amounts of TC in activated sludge reactors and found that the vast majority of TC was removed by sludge adsorption with negligible biodegradability.[87] Lapara et al. (2011) found that the vast majority of TC is present in the sludge sedimentary facies, so there were still amount of TC in the wastewater which was treated.[88] Therefore, the sludge digestion process had a potential prospective to remove TC. According to the recent research on sludge digestion technology, TC removal efficiency is more significant under anaerobic conditions than that under aerobic conditions, the high temperature anaerobic system is better than the medium temperature anaerobic system, and the removal rate increases with the increasing temperature; in the same digestion system, the efficiency of removing TC increases with the higher sludge age.[89] How to adjust the influential factors, such as oxygen consumption, temperature and sludge age, to achieve a better removal result is worth to study in the future. Moreover, sludge bulking, single component, and low removing rate of TC are all problems of sludge digestion technology to solve in the future.

Membrane processes
Membrane technology is a new type of separation enrichment technology, which is the use of membrane for the selective permeability of mixture components, to achieve the separation and purification. The nanofiltration membrane (NF) and reverse osmosis (RO) technology are the most promising methods removing TC. Nevertheless, RO, ultrafiltration, and nanofiltration techniques could remove to a lot of organic matter naturally occurring in the water matrix and the concentration of dissolved salts.[90] A electrocatalytic filtration membrane with high degradation efficiency about 96.50% after 6 h and low cost was fabricated by coating nano antimony-doped tin dioxide (Sb-SnO2) on a porous coal-based carbon membrane through sol-gel method.[91] Rejection of the examined TC is acceptably high for the selected RO and the tight NF membranes, in most cases, more than 98.50%.[92] H4SiW12O40 (SiW12)/cellulose acetate (CA) composite nanofibrous membrane was prepared by electrospinning in which CA was employed as the support of SiW12. Under ultraviolet irradiation, the as-prepared composite membrane exhibited enhanced photocatalytic activity in the decomposition of TC compared with pure and provided more contact area between SiW12 and the pollutant in TC photodegradation process. The optimal mass ratio of SiW12 to cellulose acetate (CA) was 1:4, and the corresponding degradation ratio for TC was 63.80%.[93] TC can be degraded by anaerobic/aerobic MBBR (A/O – MBBR) process bout 41.79%, but with increasing concentration of TC in the water, the system of TC removal ratio is declining, and fell more and more bigger.[94]

Adsorption processes
Adsorption is a process that contaminants shift from liquid to a solid surface. Granular activated carbon adsorbent is the most popular, however, expense of activated carbon is the major disadvantage at present.[95] In the investigation of the adsorption process of TC on anaerobic granular sludge during anaerobic digestion of animal wastewater, the effects of initial pH, humic acid concentration, and temperature on the removal of TC by anaerobic granular sludge from aqueous solution were investigated using the batch adsorption technique in 100mL flasks with 75 mL of work volume. The results showed that the highest removal ratio was 93% at pH 3 and the removal ratio at the neutral pH range (pH 6–8) was about 91.50%.[96] Adsorption characteristics of TC onto alumina were investigated according to series of adsorption experiments. The adsorption mechanism was dissected at molecular level by molecular dynamics simulation. Analysis of radial distribution function showed that TC could be adsorbed effectively by alumina mainly through non-bond interaction. The results illustrated that the absorption was influenced by alumina dosage, temperature, and oscillating frequency. The optional temperature was 25℃. The removal ratio of TC increased from 53.73 to 86.44%, which the alumina dosage was from 0.10 g/L to 2.00 g/L. The removal ratio of TC increased by 28.78%,which oscillation frequency was from 90 to 200 r/min.[97] Adsorption of TC onto activated carbon prepared from lign in by H3PO4 impregnated was studied.[98] The maximum adsorption capacity of TC calculated by the Langmuir isotherm model was 475.48 mg/g. The unsaturated polyester resin can be used as an effective and low-cost adsorbent to remove TC from aqueous solution.[99] In order to increase the adsorption of TC from aqueous solution, Fe-incorporated SBA15 (Fe-SBA15) with different contents of Fe (III) was synthesized. The results showed that Fe-SBA15 had better adsorption capacity of TC than that of SBA15.[100] The adsorption of TC onto silica particles was studied. The results showed that the enthalpy and entropy of adsorption were approximately – 16  and – 25 J/mol, respectively.[101]

Advanced oxidation processes
Advanced oxidation processes based on the oxidation of free radicals reaction technology. The technology for processing hard biodegradable organic matter in water and wastewater have the characteristics of high efficiency and no secondary pollution. The oxidation degradation effects of TC residues in pharmaceutical wastewater with H2O2, HClO4, and NaClO were studied. The degradation ratios of TC by H2O2, HClO4, and NaClO were 80, 88, and 100%, respectively.[102] Degradation of TC with Fenton reagent showed that the optimum reaction conditions were as follows: H2O2/Fe2+ of 10:1, pH 3.0 and H2O2 dosage of 1.58 mmol/L. Under these conditions, using a two-beam UV-Vis spectrophotometer to quantify TC at 360nm, finding that 0.10 mmol/L of TC degraded by 88.47% within 60 min of reaction.[103] In the experiment of ozone oxidation to remove TC from wastewater, the best process conditions are normal temperature, initial pH is 9.0 wastewater ozone dosing quantity is 400 mg/min, ozone oxidation time is 2h. Under this condition, the TC removal ratio is remarkable, TC concentration from 672 mg/L to below 50 mg/L.[104] The removal performance of the TC in water by using potassium ferrate was investigated. It was found that TC can be removed by ferrate efficiently and quickly, and the optimal pH value range for TC degradation is 9–10. The removal efficiency of TC and reaction ratio were increased with lager dosage of ferrate. During the first 60s, TC occurred the major degradation, over the next 10–20 min, TC occurred further degradation. At Fe (VI):TC molar ratios of 1:1 and 1:5, approximately 100% of the TC were removed after 60 s. Though conversion of TC is quick, TC only occurred a small reduction. It implicated that most of TC transformed into intermediate products without complete mineralization.[105]

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Re: Decline in insect populations
« Reply #226 on: February 07, 2020, 07:17:14 AM »
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Electrochemical process
Nowadays, in the environmental field, the removal of TC by electrochemical technologies has received considerable attention.[15] By means of anodic oxidation, highly ordered TiO2 nanotube array electrodes were prepared in the electrolytes, respectively with HF acid solution and NH4F glycerol solution. Scanning electron microscope (SEM) results show that TiO2 nanotube arrays are of uniform morphology. The length of TiO2 nanotube arrays prepared in organic electrolyte is 3 μm, while the length prepared in aqueous solution is 300 nm. At the bias potential of 4 V, the photocurrents are 1.37 and 0.83 mA/cm2, respectively. By using the electrode of 3μm, the removal efficiency of 50 mg/L TC reaches about 93% within 180 min.[106] Carbon base membrane coated with nano Sbdoped SnO2(Sb-SnO2) was fabricated through sol-gel and heat-treatment process. The removal ratio of carbon membrane for TC increased significantly after coating with Sb-SnO2 under the condition of 2.5 V DC field. The TC removal ratio was still as high as 92.30% even the operation time was up to 12 h. This indicated that there would be promising application prospects for electrocatalytic membrane in the field of treating antibiotic wastewater in the near future.[107] The SnO2/quartz column particle electrode was prepared by dipping-calcination method. The optimum calcination temperature and calcination time to prepare SnO2/quartz column particle electrode were 550°C and 5h. When the cell voltage was 15 V and the dosage of particle electrode was 32g, they performed a pretty good electrocatalytic property in TC degradation. 88.60% TC was degraded in 2h and it was 25.30% higher than that in two-dimensional system.[108] With a facile photochemical method, degradation of TC hydrochloride (TC-HCl) Ag2O/g-C3N4 p-n heterojunctions were successfully fabricated through enhanced visible-light photosynthetic activity of Ag2O/g-C3N4 p-n heterojunctions synthesized via a photochemical route. Under visible light irradiation, this method regards as a photocatalyst in the degradation of antibiotic TC-HCl.[109] Electrochemical processes seemed to be fit for treating high concentrations of antibiotics from manufacturing wastewaters. By using electrochemical technology, the removal of TC was advanced, but the applicability of this process was limited for large scale. The high operating cost caused the high-energy consumption. It is still the principal disadvantage, which limits the application of the electrochemical process.[110]

Hydrolysis process
Hydrolysis is the main way to degrade TC in the water environment.[111] The hydrolysis of TC is strongly influenced by pH and temperature. TC degradation ratio increased with the increasing of pH and temperature. Ionic strength does not affect the hydrolysis of TC.[112] The functions of biological treatment systems may be limited by high concentrations of TC in wastewater. Yi et al. (2016) established a pretreatment method for TC production wastewater by using an enhanced hydrolysis process under the optimization of temperature and pH conditions.[113] This research showed that the TC hydrolysis rate was accelerated by 2.22–2.74-fold with an increase of 10°C. When the pH value was increased from 3 to 11 at 85°C, the hydrolysis half-life of TC was shortened by 3.23-fold. The half-life of TC at pH 7 and pH 11 could be shortened from 5.5 to 0.93 h and from 3.7 to 0.59 h, by elevating the temperature from 65 to 85°C. Kang et al. (2012) measured the first order hydrolysis rate constants of TC at pH 5, 7, and 9 using batch tests. The value was highest at pH 7 for TC, indicating short environmental half-lives of TC. For TC, half-lives were approximately 7–10 days at pH 7. It also was found that the degradation ratio of TC was much faster when the solution was passed through a silica column or silica sand was present in a batch solution. This indicates that the silica surface may serve as a catalyst for hydrolysis and that the actual environment half-lives of TC could be shorter than those estimated from laboratory hydrolysis rate constants.[114] Hydrolysis time is longer and the effect is limited. It can be used as an auxiliary means of degradation of TC.

Others
Ultrasonic degradation
As new technology of water treatment, ultrasonic degradation has received wide attention in the removal of TC.[115] Ultrasonic degradation technology can generate instantaneous high temperature and instantaneous high pressure by using ultrasonic activation to activate the nucleate and break chemical bonds of pollutants in liquids. At the same time, vapors produce HO to oxidize organic pollutants in liquids at high temperature and high pressure. Then, those pollutants would become molecules and ions, which are easier to deal with. Researchers found that the average ratio of removal of TC by ultrasonic degradation technology was 63.89%.[116] Ultrasonic degradation technology has a wide range of application, but it needs more moderate degradation conditions, and higher cost and energy consumption, which have restricted the development of ultrasonic degradation technology.[117]

Low-temperature plasma technology
Low-temperature plasma technology is the use of a large number of ions generated by the active particle of ultraviolet light, ozone and electronic radiation as the conditions for the occurrence, thereby accelerating the degradation of pollutants in chemical reactions and to achieve the removal effect of the technology.[118] Under natural conditions, half-life of TC is 7.5 h.[119] However, TC removed by low-temperature plasma technology in a short time. Previous report deemed that the removal ratios of TC under the conditions that synergism of electron radiation, ozone and ultraviolet light which could accelerate the degradation of TC were higher than that under the individual conditions.[69,70,76–82,120,121] Low-temperature plasma technology is a simple and convenient operation, without adding chemical agents and other advantages, but its reaction condition, reaction rate and quantity are difficult to control, disinfection by-products produced in the process of reaction is also a problem to be solved.

Enzyme degradation
Li et al. (2016) chose the crude enzyme of lignin peroxidase (Lip) from Phanerochaete chrysosporium as the research object.[54] The results indicated that the limitation of carbon, nitrogen and low concertation of Mn2+ were important factors for enzyme production. Lip had a strong ability of TC degradation with initial concentrations of 10 , 25, 50, and 100 mg/L, the degradation rate being 62, 80, 82, and 90%, respectively. However, this method is limited by the industrial production of enzyme.

Conclusion and future directions in pollution control technology of TC
This review examines the contamination and control of TC in groundwater. Firstly, it elaborated on the livestock and poultry farming industry in rural areas where TC is the primary source of surface water. Secondly, the survey found that TC was commonly used in medicine and veterinary medicine. Thirdly, effects of toxicity of TC in groundwater and its biology were studied. Finally, the application conditions, mechanism, advantages, and disadvantages of various TC control technologies were summarized.

The above review shows that TC poses a threat to aquatic organisms, aquatic animals, plants, and microbes in groundwater. Therefore, this paper presents a variety of methods such as photodegradation, microbial degradation, phytodegradation, sludge digestion technology, membrane processes, adsorption processes, advanced oxidation processes, electrochemical process, and hydrolysis process to deal with the environmental risks brought by ex situ groundwater. Nevertheless, these methods could also be used to treat drinking waters issued from groundwater. There is no doubt that in situ treatment of groundwater is one of the most important is our future research direction. These methods have their shortcomings, and the treatment technology is not enough to fully remove TC currently. Therefore, the application and improvement of various detection techniques and treatment methods should continue to be strengthened. Combined with pollution situation of TC in groundwater, there are further research directions following aspects:

(1) Photocatalysts for the efficient removal of TC should be studied. As demonstrated by Hong et al. (2016) who applied photodegradation, it was possible to use entirely new Nb2O5/g–C3N4(niobium pentoxide/graphitic-like carbon nitride) heterojunctions made by a simple one-step heating strategy for removing TC, which would bring about potential application in removing of TC pollutant and solar energy conversion. It was found that the new heterojunction showed the highest photocatalytic efficiency for TC–HCl degradation and excellent photocatalytic recyclability.[122] Then, a new nano-photocatalyst of TC was born as recently exemplified by Omorogie et al. (2017), which enhanced its surface area/pore structure and photoactivity by decreasing the electron-hole pair recombination.[123] Moreover, the development of multiresponsive catalytic materials was a wonderful subject for forwarding to the understanding on catalysis and removing mechanism, which had already being studied by Tu et al. (2017).[124] They developed a series of different forms of Bi4Ti3O12 catalyst, including nanorods, flake assembled microspheres, hollow microspheres and cubic nested assembly. This catalyst had general photoreactivity for various contaminants and antibiotics such as bisphenol A, rhodamine B, chlortetracycline and tetracycline hydrochloride.[124]

(2) Biodegradable repair which is based on enzymatic degradation is a relatively recent field of research and a promising technology to remove TC from groundwater. Taheran et al. (2017) have been done a supernacular exploring who used enzymatic degradation with laccase to remove pharmaceutical compounds from aqueous media. In this study, laccase was immobilized on a homemade polyacrylonitrile-biochar composite nanofiber membrane and then biocatalyst was used to remove antibiotics from the water.[125] Conventional biological processes can still pose threat to groundwater. So the hybrid process combined with biological or physical technology will remove efficiently. Advancing biological technologies and Membrane Bio–Reactor hybrid systems are considered as one promising technology for removing TC. On the other hand, it is important to discuss the harm of microbial oxidative degradation products of TC. It is very promising to elucidate the degradation of degradation products in environment and their role in the formation of microbial communities. It’s necessary to analyze the ecological risk-assessment to reduce the risks we would cause.

(3) Standard removal process can remove most TC. It’s possible to focus on the treatment of trace TC. The minority pays attention to remove trace TC, Yang et al. (2017) have studied that the fate of trace organic contaminants.[126] The results of this report showed the pervasive presence of 17 trace organic contaminants (TrOCs) in sewage sludge and highlighted the importance of evaluating TrOC removal through mass balance calculations. This calculation took into account the distribution and biodegradation between aqueous and solid phase. In addition, the substrate concentration required for advanced oxidation technology is generally higher than the actual concentration of antibiotic in water. Therefore, it is necessary to study the advanced oxidation method combined with traditional technology to avoid secondary pollution.

(4) The production of antibiotic resistance genes (ARGs) has been considered as a rising contaminant which would be a pivotal danger to groundwater in worldwide. In order to further understand the migration and transformation of TC in environment, at the same time, improving the control of TC prediction model in groundwater, it is benefit to take different ways to deal with its diverse forms. Some heavy metals, fungicides, and TC have a co-selection effect on bacterial microbes, so the degradation of TC by resistant bacterial microorganisms in groundwater will also be the focus of future research. Zhou et al. (2017) thought that it was significant to control ARG spread in the agriculture sector within the globe.[127]
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blumenkraft

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Re: Decline in insect populations
« Reply #227 on: February 07, 2020, 07:18:10 AM »
Thanks so much, Ktb!.
"damn .. one apocalypse getting in the way of another .." - be cause

kassy

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Re: Decline in insect populations
« Reply #228 on: February 07, 2020, 01:45:14 PM »
Thanks indeed! If you do add pictures i think figures 3 and 4 are the most interesting.



Climate change: Loss of bumblebees driven by 'climate chaos


"Climate chaos" has caused widespread losses of bumblebees across continents, according to scientists.

A new analysis shows the likelihood of a bee being found in any given place in Europe and North America has declined by a third since the 1970s.

Climbing temperatures will increasingly cause declines, which are already more severe than previously thought, said researchers.

...

Dr Tim Newbold of University College London (UCL) said there had been some previous research showing that bumblebee distributions are moving northwards in Europe and North America, "as you'd expect with climate change".

He added: "But this was the first time that we have been able to really tie local extinctions and colonisations of bumble bees to climate change, showing a really clear fingerprint of climate change in the declines that we've seen."

...

In the new study, researchers looked at more than half a million records of 66 bumblebee species from 1901 to 1974 and from 2000 to 2014.

They found bumblebee populations declined rapidly between 2000-2014: the likelihood of a site being occupied by bumblebees dropped by an average of over 30% compared with 1901-1974.

'Alarming' losses
Bees have been hardest hit in southern regions such as Spain and Mexico due to more frequent extreme warm years. And, while populations have expanded into cooler northern regions, this has not been enough to compensate for the losses.

https://www.bbc.com/news/science-environment-51375600
 
Þetta minnismerki er til vitnis um að við vitum hvað er að gerast og hvað þarf að gera. Aðeins þú veist hvort við gerðum eitthvað.

vox_mundi

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Re: Decline in insect populations
« Reply #229 on: February 13, 2020, 12:01:35 AM »
Car ‘Splatometer’ Tests Reveal Huge Decline In Number of Insects
https://www.theguardian.com/environment/2020/feb/12/car-splatometer-tests-reveal-huge-decline-number-insects

Research shows abundance at sites in Europe has plunged by up to 80% in two decades

Two scientific studies of the number of insects splattered by cars have revealed a huge decline in abundance at European sites in two decades.

The research adds to growing evidence of what some scientists have called an “insect apocalypse”, which is threatening a collapse in the natural world that sustains humans and all life on Earth. A third study shows plummeting numbers of aquatic insects in streams.

The survey of insects hitting car windscreens in rural Denmark used data collected every summer from 1997 to 2017 and found an 80% decline in abundance. It also found a parallel decline in the number of swallows and martins, birds that live on insects.

The second survey, in the UK county of Kent in 2019, examined splats in a grid placed over car registration plates, known as a “splatometer”. This revealed 50% fewer impacts than in 2004. The research included vintage cars up to 70 years old to see if their less aerodynamic shape meant they killed more bugs, but it found that modern cars actually hit slightly more insects.

Parallel declines in abundance of insects and insectivorous birds in Denmark over 22 years
https://onlinelibrary.wiley.com/doi/full/10.1002/ece3.5236

Kent Wildlife Trust’s Bugs Matter survey
https://www.kentwildlifetrust.org.uk/bugs-matter
https://www.kentwildlifetrust.org.uk/sites/default/files/2020-02/Bugs_Matter_report_website_version.pdf

Complex and nonlinear climate‐driven changes in freshwater insect communities over 42 years
https://conbio.onlinelibrary.wiley.com/doi/abs/10.1111/cobi.13477
“There are three classes of people: those who see. Those who see when they are shown. Those who do not see.” ― Leonardo da Vinci

Insensible before the wave so soon released by callous fate. Affected most, they understand the least, and understanding, when it comes, invariably arrives too late