Knowledge about how the COVID-19 pandemic can affect aquatic wildlife is still extremely limited, and no effect of SARS-CoV-2 or its structural constituents on invertebrate models has been reported so far. Thus, we investigated the presence of the 2019-new coronavirus in different urban wastewater samples and, later, evaluated the behavioral and biochemical effects of the exposure of Culex quinquefasciatus larvae to two SARS-CoV-2 spike protein peptides (PSPD-2002 and PSPD-2003) synthesized in our laboratory. Initially, our results show the contamination of wastewater by the new coronavirus, via RT-qPCR on the viral N1 gene. On the other hand, our study shows that short-term exposure (48 h) to a low concentration (40 μg/L) of the synthesized peptides induced changes in the locomotor and the olfactory-driven behavior of the C. quinquefascitus larvae, which were associated with increased production of ROS and AChE activity (cholinesterase effect). To our knowledge, this is the first study that reports the indirect effects of the COVID-19 pandemic on the larval phase of a freshwater invertebrate species. The results raise concerns at the ecological level where the observed biological effects may lead to drastic consequences.

Forest and agricultural land use affects the concentration and composition of dissolved organic carbon (DOC) in streams and rivers. To elucidate the impacts of forest and agricultural land use on stream DOC during storm events, we investigated DOC concentration ([DOC]), optical properties of dissolved organic matter (DOM), and Δ¹⁴C-DOC in both forest- and agriculture-dominated headwater streams in South Korea in the summer of 2012. One forested and five agricultural streams were investigated. During storms, the peak [DOC] of forest stream increased to 5.8 mg L⁻¹, approximately two times larger than that of the most agricultural stream (3.2 mg L⁻¹), demonstrating the weaker storm responses of the [DOC] of agricultural streams to hydrological change. Five PARAFAC components were identified, including three terrestrial humic-like substances (C1, C2, C3), one microbial humic substance (C4), and one microbial protein-like substances (C5). The mean (C4+C5)/(C1+C2+C3) of all storm events at the most agricultural stream was 1.5 times larger than that of the most forested stream, suggesting that more protein-like DOM is exported from agricultural watersheds. Whereas a forest stream was primarily composed of terrestrially derived and ¹⁴C-enriched modern DOC, the ¹⁴C-age of the most agricultural stream was up to ∼1000 years old. The results suggest that agricultural practices could decrease the old organic carbon pools from soils. However, how quickly the aged DOC can be degraded to CO₂ in streams is unknown, warranting future investigation on lability of the aged DOC and their effects on CO₂ evasion from rivers and estuaries downstream.

The Yellow River is the second largest river in China. Carbon transport by the Yellow River has significant influence on riverine carbon cycles in Asia. During the wet season, the riverine carbon was mainly found in dissolved form, i.e., dissolved organic carbon (DOC), along the entire course of the river. The distinct spatial variations of DOC concentration were observed at different reaches of the mainstream (p < 0.01), while the highest mean DOC concentration was generally observed at midstream (4.13 ± 0.91 mg/L). Carbon stable isotope analysis δ¹³C and C: N ratio of DOC, evidenced the sources of DOC in headwater and upstream were primarily the terrestrial plants (94% and 61%), but it was changed to soil organic matter (SOM) in mid- and downstream (36% and 37%), and the contribution of sewage to DOC were also increased to 17% and 18%. In the whole mainstream of the Yellow River, water temperature (WT) had a significant impact on DOC concentration, and it could explain 67% of the DOC variance. However, in a large catchment, the driving mechanisms on the DOC variations in headwaters will not necessarily be those controlling DOC trends in downstream. The study firstly quantified, in headwater and upstream, the natural factors explained as much as 65% and 73% of the DOC variations, respectively. In mid- and downstream areas, DOC was significantly influenced by the amount of wastewater discharged by the industry and the use of chemical fertilizers (p < 0.05). These findings may facilitate a better assessment of global riverine carbon cycling and may help to reveal the importance of the balance between development and environmental sustainability with the changing DOC transport features in the Yellow River due to human disturbances.

With the ever-increasing demand for lithium (Li) for portable energy storage devices, there is a global concern associated with environmental contamination of Li, via the production, use, and disposal of Li-containing products, including mobile phones and mood-stabilizing drugs. While geogenic Li is sparingly soluble, Li added to soil is one of the most mobile cations in soil, which can leach to groundwater and reach surface water through runoff. Lithium is readily taken up by plants and has relatively high plant accumulation coefficient, albeit the underlying mechanisms have not been well described. Therefore, soil contamination with Li could reach the food chain due to its mobility in surface- and ground-waters and uptake into plants. High environmental Li levels adversely affect the health of humans, animals, and plants. Lithium toxicity can be considerably managed through various remediation approaches such as immobilization using clay-like amendments and/or chelate-enhanced phytoremediation. This review integrates fundamental aspects of Li distribution and behaviour in terrestrial and aquatic environments in an effort to efficiently remediate Li-contaminated ecosystems. As research to date has not provided a clear picture of how the increased production and disposal of Li-based products adversely impact human and ecosystem health, there is an urgent need for further studies on this field.

The versatile use of various synthetic polymers, including plastics, generates a large volume of non-degradable waste, which is eventually responsible for forming microplastics (MPs) in aquatic environments. The present study describes the significant spatial and seasonal variation on the abundance of MPs and their physiochemical nature along the Mandovi-Zuari estuarine system of Goa, west coast of India. During the wet season (September), the average abundance of MPs was found relatively higher in water (0.107 particles/m³) and sediment (7314 particles/kg) than those found in the dry season (April) (0.099 particles/m³ in water and 4873 particles/kg in sediment). During the wet season, heavy rain and excessive riverine freshwater influx carry more terrestrial plastic debris in the estuarine system which causes higher averages MPs density in surface water and sediment. <300 μm sized particles and black colored MPs were predominant equally in water and sediment during both seasons. MPs of different shapes like fragments, fibres, films and beads accounted for most collected samples. The Micro-Fourier Transform Infrared Spectroscopy (μ-FTIR) based compositional analysis identified approximately 33 types of polymers, of which polyacrylamide (PAM), polyacetylene, polyamide (PA), polyvinyl pyrrolidone (PVP), polyvinyl chloride (PVC), and polyimide (PI) were abundant. Fragmentation of larger plastic particles due to mismanaged treated and untreated STPs and washing machine effluents are the primary sources of these MPs in the estuarine system. Moreover, these estuaries also receive a variety of domestic, industrial and other wastes from local cities, ports, and fishing jetties. Thus the present study enlightens the current distribution of MPs and their sources in the Mandovi-Zuari estuarine system and thus provides very useful information to the stakeholder and concerned departments for initiating the mitigation measures.

Microplastics can have several negative consequences on a variety of organisms, and their prevalence in marine ecosystems has become a major concern. Researchers have recently focused their attention on the world's largest gulf, the Gulf of Mexico (GoM), to determine and assess the impact of microplastic pollution on various environmental compartments (i.e., water, sediment, and biota). This paper critically reviews the analytical methodologies as well as summarizes the distribution, accumulation, sources, and composition of microplastics in a handful of studies (n = 14) conducted in the Gulf of Mexico (GoM) covering countries like the USA (n = 10) and Mexico (n = 4). Current quality control measures with respect to sampling and microplastic extraction are summarized. Of 14 studies reviewed, 47% primarily focused on examining sediments for microplastics, with biota and water comprising 35% and 18%, respectively. The abundance ranged from 31.7 to 1392 items m⁻² and 60–1940 items kg⁻¹ in sediment, 12–381 particles L⁻¹ in water, and 1.31–4.7 particles per fish in biota. Irregular shaped fragments were the most abundant, followed by fiber, film, foam, hard, and beads etc. Different polymer types of microplastics have been found, including polyethylene, polypropylene, polystyrene, polyamide, nylon, and rayon etc. According to published research, 46 out of 100 fish thriving in this region are susceptible to microplastic ingestion. Although microplastic concentration in the GoM is among the highest found worldwide, the determination of microplastic contamination is still a growing field of research and methodological discrepancies largely limit the realization of establishing a baseline information on the microplastic abundance of the GoM. In this respect, considerable efforts must be dedicated towards evaluating their distribution and exposure levels; thereby, major challenges and future research directions are briefly discussed.

In this study, we reported the occurrence of eight organophosphorus pesticides (OPPs) in the East China Sea. Forty samples were collected and analysed with a high volume solid phase extraction method (Hi-throat/Hi-volume SPE) in the early summer of 2020. All the target OPPs were detected in the surface water at one or more stations in the East China Sea, and the concentrations of ΣOPPs were in the range 0.0775–3.09 ng/L (mean: 0.862 ± 0.624 ng/L). Terbufos sulfone and fenthion were the main pollutants in this area, probably resulting from pesticide use in China and other countries. The off-shore input from coastal regions was suggested to be a major source of OPP pollution in the East China Sea, and the movement of ocean currents played an important role in their transportation because around 0.86 t OPPs passed through the Tsushima Strait from the East China Sea each month. An ecological risk assessment showed that these OPPs presented a high risk to species in the East China Sea, whereas they posed no health risk to humans under both the median and high exposure scenario.

The co-occurrence of mcr-like and carbapenemase-encoding genes have been reported mainly in humans and animals, whereas, in the environment, studies are gradually increasing due to the One Health approach. In this study, we investigated antimicrobial resistance genes (ARGs) in water and sand samples from marine environments in Brazil. Total DNA from 56 samples (33 sands and 23 waters) was obtained and 27 different ARGs were detected, highlighting the presence of mcr-9, blaKPC and cfr genes. Additionally, the microbiological analysis revealed that sand samples of all analyzed beaches were not recommended for primary use, whereas water samples from most beaches were classified as unsuitable for bathing. The presence of clinically relevant ARGs in urban beaches suggests the presence of antimicrobial-resistant bacteria. Furthermore, to the best of our knowledge, this is the first report of mcr-9 and cfr genes in the environment from Brazil and recreational areas worldwide.

Microplastic (MPL) contamination in the marine environment is extensively studied yet little is known about the extent of MPL abundance in seagrass beds. The aim of this study was to evaluate MPL accumulation in coastal seagrass (Zostera marina) beds in the Baltic Sea, Estonia.Surface water was sampled by pumping using 40 μm plankton net, and sediments by trowel. MPL was extracted with NaCl, identified by microscopy and ATR-FTIR on selected samples.Surface water in the seagrass beds had 0.04–1.2 (median 0.14) MPL/L, similar to other areas of the Baltic Sea. Sediments had 0–1817 (median 208) MPL/kg (dwt), much higher than previously recorded from adjacent unvegetated and offshore sediments, thereby suggesting a strong ability of the sediments in seagrass beds to retain MPL. Of identified MPL, blue fibres were dominant in both the sampled media. Sediment characterization showed a correlation between MPL counts with poorly sorted sediments.

In aquatic environments, assessment of microplastic concentrations is increasing worldwide but environments from developing countries remain under-evaluated. Due to disparities of facilities, financial resources and human resources between countries, protocols of sampling, analysis and observations used in developed countries cannot be fully adapted in developing ones, and required specific adaptations. In Viet Nam, an adapted methodology was developed and commonly adopted by local researchers to implement a microplastic monitoring in sediments and surface waters of 21 environments (rivers, lakes, bays, beaches) of eight cities or provinces. Microplastic concentrations in surface waters varied from 0.35 to 2522 items m-3, with the lowest concentrations recorded in the bays and the highest in the rivers. Fibers dominated over fragments in most environments (from 47% to 97%). The microplastic concentrations were related to the anthropogenic pressure on the environment, pointing out the necessity in a near future to identify the local sources of microplastics.