Microplastics (<5 mm) are ubiquitous contaminants of growing concern. These have been found in multiple environmental compartments, including remote sites where anthropogenic activity is null. Once ...released, microplastics interact with multiple chemicals in the environment, many of which are classified as organic contaminants or heavy metals. Some contaminants have an affinity for microplastics, attributed to certain sorption mechanisms, and thus become vectors of hazardous chemicals. Here, we focused on the sorption behavior of degradable and non-degradable microplastics, including field and laboratory experiments. We reviewed the sorption mechanisms, namely hydrophobic interactions, electrostatic interactions, pore-filling, Van der Waals forces, hydrogen bonding, and π-π interactions, and the factors strengthening or weakening these mechanisms. Then, we analyzed the literature investigating the sorption behavior of a wide range of chemicals contaminants on microplastics, and the current knowledge regarding the occurrence of organic contaminants and heavy metals on microplastics extracted from the environment. The future perspectives and research priorities were discussed. It is apparent that degradable microplastics, such as polylactic acid or polybutylene succinate, have a greater affinity for hydrophobic contaminants than conventional synthetic non-degradable microplastics according to recent studies. However, studies assessing degradable microplastics are scarce and much research is required to further prove this point. We stated several knowledge gaps in this new line of research and suggest the future studies to follow an integrative approach, allowing to comprehend the multiple factors involved, such as ecotoxicity, bioaccumulation, and fate of the chemical contaminants.
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•Microplastics (MPs) serve as vectors of chemical contaminants.•The sorption capacity of MPs depends on mechanisms and factors.•The sorption capacity of degradable MPs is similar or higher than nondegradable MPs.•Future research must focus on elucidating the full potential of degradable MPs.
We present a simulation of the global present-day composition of the troposphere which includes the chemistry of halogens (Cl, Br, I). Building on previous work within the GEOS-Chem model we include ...emissions of inorganic iodine from the oceans, anthropogenic and biogenic sources of halogenated gases, gas phase chemistry, and a parameterised approach to heterogeneous halogen chemistry. Consistent with Schmidt et al. (2016) we do not include sea-salt debromination. Observations of halogen radicals (BrO, IO) are sparse but the model has some skill in reproducing these. Modelled IO shows both high and low biases when compared to different datasets, but BrO concentrations appear to be modelled low. Comparisons to the very sparse observations dataset of reactive Cl species suggest the model represents a lower limit of the impacts of these species, likely due to underestimates in emissions and therefore burdens. Inclusion of Cl, Br, and I results in a general improvement in simulation of ozone (O3) concentrations, except in polar regions where the model now underestimates O3 concentrations. Halogen chemistry reduces the global tropospheric O3 burden by 18.6 %, with the O3 lifetime reducing from 26 to 22 days. Global mean OH concentrations of 1.28 × 106 molecules cm−3 are 8.2 % lower than in a simulation without halogens, leading to an increase in the CH4 lifetime (10.8 %) due to OH oxidation from 7.47 to 8.28 years. Oxidation of CH4 by Cl is small (∼ 2 %) but Cl oxidation of other VOCs (ethane, acetone, and propane) can be significant (∼ 15–27 %). Oxidation of VOCs by Br is smaller, representing 3.9 % of the loss of acetaldehyde and 0.9 % of the loss of formaldehyde.
One of the most important ecosystems in the Amazon rainforest is the Mauritia flexuosa swamp or “aguajal”. However, deforestation of its dominant species, the Mauritia flexuosa palm, also known as ...“aguaje”, is a common issue, and conservation is poorly monitored because of the difficult access to these swamps. The contribution of this paper is twofold: the presentation of a dataset called MauFlex, and the proposal of a segmentation and measurement method for areas covered in Mauritia flexuosa palms using high-resolution aerial images acquired by UAVs. The method performs a semantic segmentation of Mauritia flexuosa using an end-to-end trainable Convolutional Neural Network (CNN) based on the Deeplab v3+ architecture. Images were acquired under different environment and light conditions using three different RGB cameras. The MauFlex dataset was created from these images and it consists of 25,248 image patches of 512 × 512 pixels and their respective ground truth masks. The results over the test set achieved an accuracy of 98.143%, specificity of 96.599%, and sensitivity of 95.556%. It is shown that our method is able not only to detect full-grown isolated Mauritia flexuosa palms, but also young palms or palms partially covered by other types of vegetation.
Identifying novel viruses or assessing viral variation by NGS requires high sequencing coverage. More than 90% of total RNA is ribosomal (rRNA), making variant calling, virus discovery or ...transcriptomic profiling difficult. Current methods to increase informative reads suffer from drawbacks, either they cannot be used for some viruses, are optimized for a single species, or introduce bias. We describe a two-part approach combining reverse-transcription to create RNA/DNA hybrids which are then degraded with RNaseH/DNase sequentially that works for three medically relevant mosquito genera; Aedes, Anopheles, and Culex. We demonstrate depletion of rRNA from different samples, including whole mosquitoes and midgut contents from FTA cards. We describe novel insect-specific virus genomes from field collected mosquitoes. The protocol requires only common laboratory reagents and small oligonucleotides specific to rRNA. This approach can be adapted for other organisms, aiding virus diversity analyses, virus discovery and transcriptomics in both laboratory and field samples.
•rRNA can make up most of the RNA in metagenomic sequencing from mosquitoes.•Short DNA probes bind rRNA and create DNA/RNA hybrids after reverse transcription.•RNase H and DNase treatment will selectively degrade rRNA and subsequent cDNA.•This method increases NGS reads to viruses, bacteria, and mosquito transcripts.
Boreal fires have increased during the last years and are projected to become more intense and frequent as a consequence of climate change. Wildfires produce a wide range of effects on the Arctic ...climate and ecosystem, and understanding these effects is crucial for predicting the future evolution of the Arctic region. This study focuses on the impact of the long-range transport of biomass-burning aerosol into the atmosphere and the corresponding radiative perturbation in the shortwave frequency range. As a case study, we investigate an intense biomass-burning (BB) event which took place in summer 2017 in Canada and subsequent northeastward transport of gases and particles in the plume leading to exceptionally high values (0.86) of Aerosol Optical Depth (AOD) at 500 nm measured in northwestern Greenland on 21 August 2017. This work characterizes the BB plume measured at the Thule High Arctic Atmospheric Observatory (THAAO; 76.53∘N, 68.74∘W) in August 2017 by assessing the associated shortwave aerosol direct radiative impact over the THAAO and extending this evaluation over the broader region (60∘N–80∘N, 110∘W–0∘E). The radiative transfer simulations with MODTRAN6.0 estimated an aerosol heating rate of up to 0.5 K/day in the upper aerosol layer (8–12 km). The direct aerosol radiative effect (ARE) vertical profile shows a maximum negative value of −45.4 Wm−2 for a 78∘ solar zenith angle above THAAO at 3 km altitude. A cumulative surface ARE of −127.5 TW is estimated to have occurred on 21 August 2017 over a portion (∼3.1×106 km2) of the considered domain (60∘N–80∘N, 110∘W–0∘E). ARE regional mean daily values over the same portion of the domain vary between −65 and −25 Wm−2. Although this is a limited temporal event, this effect can have significant influence on the Arctic radiative budget, especially in the anticipated scenario of increasing wildfires.
Plastic pollution is one of the major challenges in the Anthropocene. A plastic waste sub-product, microplastics (<5 mm), has been regarded as contaminants of concern for its detrimental effects and ...widespread in the environment. Most studies assessing microplastics focused on marine environments, while terrestrial and soil systems have been overlooked. In this review, we analyzed the current knowledge regarding microplastic pollution in natural soil or agricultural ecosystems. We focused on reviewing the procedural steps for microplastic extraction and identification in detail. The heterogeneity of the methods applied, lack of standardized procedures and incompatible parameters reported, make the results incomparable among most studies. Several microplastic concentration units are needed to make studies comparable. Correctly determining and reporting microplastic morphotypes are key to understanding the sources of contamination. Minimal considerations and recommendations were stated for extraction, digestion, filtration, and polymer identification procedures. Baseline contamination prevention measures were identified as mandatory along the entire sampling, handling and identification procedures. Lastly, knowledge gaps were identified and discussed for further research.
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•MPs abundance in soil depend on the source, site characteristic and methods used.•Reporting the MP types and chemical classification is mandatory.•Heterogeneity of methods used in literature make results incomparable.•Novel methods need to overcome important frontiers and challenges.•Minimal standards along the extraction and identification procedure are suggested.
Safety studies are essential in drug development. This study evaluates the safety of Amphotericin A21 (AmB‐A21), a derivative of amphotericin B with antifungal therapeutic potential. We performed a ...chronic toxicity study, a targeted organ study and a dermal irritation test. To evaluate chronic toxicity, 18 male adult rats were treated orally with AmB‐21 (2 mg/kg) for 26 weeks. The effects on body‐weight and animal health were measured, and haematological, clinical chemistry and histopathological tests were conducted on various organs. In the target organ toxicity study, male adult rats received a daily oral dose of AmB‐21 (2 mg/kg) for 6 and 17 weeks; testicle histology and testosterone levels were then evaluated. For the dermal irritation study, AmB‐21 (200 and 1000 mg/kg) was placed on the skin of adult male rabbits; macroscopic and microscopic studies, as well as haematological and clinical chemistry tests were then conducted. The chronic toxicity study revealed that AmB‐21 caused testicle damage, and the testicle‐targeted study showed structural alterations and changes in testosterone levels at 17 weeks. However, these alterations were no longer observed 8 weeks after discontinuation of treatment, and the testes showed very similar characteristics to those in the control group. The dermal irritation study showed skin thickening and reddening in rabbits treated with 2000 mg of AmB‐A21 after 14 days of exposure. This same group also showed changes in liver enzymes, renal parameters and platelet levels. Based on our results, we consider AmB‐21 to be a potential candidate for safe, long‐term antifungal treatment given its reduced side effects.
A bibliometric analysis of proton exchange membrane fuel cells (PEMFCs) content from a total of 15.020 research publications was conducted between 2008 and 2018, the papers being detailed in the ...online version of SCI-Expanded, Thomson Reuters Web of Science. Data processing tools such as Hitscite, CiteSpace, ArcGIS and Ucinet 6 were used to process the information. The parameters analyzed in the analysis were: type of document; the language of publication; volume and characteristics of publication output; publication by journals; performance of countries and research institutions; research trends and visibility. The study showed that "Fuel'', "Cell", "Membrane “and "Proton" were found in most of the titles of the documents, while "Performance", "Pemfc”, "Pem Fuel Cell" and "Fuel Cell" were the keywords most commonly used in documents. The analysis found that PEMFC studies have tended to be growing and that leading peer-reviewed journals have produced numerous publications on the subject. The investigation revealed that the country with the most significant production in the field is USA with a contribution of 3009; 20% of the total publications. Followed by China 2480; 16.5%, South Korea 1273; 8.5% and Germany 1121; 7.5%, showing to the main world powers as the most significant contributors to the research.
Top-down observational constraints on emissions flux estimates from satellite observations of chemical composition are subject to biases and errors stemming from transport, chemistry and prior ...emissions estimates. In this context, we developed an ensemble data assimilation system to optimize the initial conditions for carbon monoxide (CO) and aerosols, while also quantifying the respective emission fluxes with a distinct attribution of anthropogenic and wildfire sources. We present the separate assimilation of CO profile v9 retrievals from the Measurements of Pollution in the Troposphere (MOPITT) instrument and Aerosol Optical Depth (AOD), collection 6.1, from the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments. This assimilation system is built on the Data Assimilation Research Testbed (DART) and includes a meteorological ensemble to assimilate weather observations within the online Community Atmosphere Model with Chemistry (CAM-chem). Inversions indicate an underestimation of CO emissions in CAMS-GLOB-ANT_v5.1 in China for 2015 and an overestimation of CO emissions in the Fire INventory from NCAR (FINN) version 2.2, especially in the tropics. These emissions increments are consistent between the MODIS AOD and the MOPITT CO-based inversions. Additional simulations and comparison with in situ observations from the NASA Atmospheric Tomography Mission (ATom) show that biases in hydroxyl radical (OH) chemistry dominate the CO errors.
New plastic formations in the Anthropocene De-la-Torre, Gabriel Enrique; Dioses-Salinas, Diana Carolina; Pizarro-Ortega, Carlos Ivan ...
The Science of the total environment,
02/2021, Letnik:
754
Journal Article
Recenzirano
Odprti dostop
Plastic pollution is one of the major challenges in the Anthropocene. Upon reaching the marine environment, plastic debris is subject to anthropogenic and environmental conditions that result in ...novel items that vary in composition, physical and chemical characteristics. Here, we reviewed and discussed the potential fate and threat to the environment of four recently described plastic formations: Plastiglomerates, pyroplastics, plasticrusts, and anthropoquinas. The threats identified were mostly related to the release of toxic chemicals and plastic ingestion. Transportation of alien invasive species or microbial pathogens and fragmentation of larger plastics into microplastics (<5 mm), potentially reaching marine trophic webs, are suspected as potential impacts based on the characteristics of these plastic formations. Some plastic forms may persist in the environment and voyage across the ocean, while others are denser and less likely to enter the plastic cycle or interact with biota. In the latter case, plastics are expected to become buried in the sediment and incorporate into the geological record. It is necessary to establish sampling protocols or standards that are specific to each plastic formation and start reporting the occurrence of these new plastic categories as such to avoid underestimating plastic pollution in marine environments. It is suggested that monitoring plans include these categories and identify potential sources. Further research must focus on investigating whether the suspected impacts are a matter of concern. In this sense, we have suggested research questions to address the knowledge gaps and have a better understanding of the impacts and distribution of the new plastic forms.
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•New plastic-associated contaminants have been recently reported in literature.•The fate and effects depend on the characteristics of each new contaminant.•Plastic pollution monitoring guidelines must include the new terminology.•Further research is needed regarding the suspected impacts of these contaminants.
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