The co-contamination of arsenic (As) and cadmium (Cd) in soils is a common problem. Selenium (Se) can reduce the uptake of As and Cd in plants, and in practice, the alternate wetting and drying is a common culture mode in rice production. However, it is unknown whether Se can efficiently reduce As and Cd concentrations in crops suffering from a high-level contamination of As and Cd under different soil water conditions. In this study, we assessed the efficiency and risks of selenite [Se(IV)], in a pot experiment, to reduce the uptake of As and Cd in a rice plant (YangDao No 6) growing in a heavily contaminated soil by As and Cd (pH 7.28) under different soil water conditions. The results showed that Se(IV) failed to control the grain total As and Cd concentrations within their individual limited standard (0.2 mg kg⁻¹) despite that Se(IV) significantly reduced the grain total As and Cd concentrations. The soil drying treatment alone could reduce the accumulation of arsenite [As(III)] in the grains, but additional Se(IV) stimulated the accumulation of As(III) in the grains under soil drying conditions. In addition, the addition of Se(IV) enhanced the As and Cd concentrations in the shoots and/or roots of rice plants under certain conditions. The above results all suggested that the utilization of Se(IV) in a high contaminated soil by As and Cd cannot well control the total concentrations of As and Cd in plants. In this study, the available concentrations of As and Cd in the rhizosphere soil, the rhizosphere soil pH, the formation of root iron/manganese plaques and the concentrations of essential elements in the grains were monitored, and the related mechanisms on the changes of these parameters were also discussed. This study will give a guideline for the safe production of rice plants in a heavily co-contaminated soil by As and Cd.

The occurrence and composition profiles of 13 triester organophosphate flame retardants and their three diester metabolites in river water, wastewater, and tap water in China were studied. Most target organophosphate esters (OPEs) were found in water samples, with average concentrations of 787 ng/L for triethyl phosphate (TEP) and 0.1 ng/L for tripropyl phosphate (TPP) in wastewater, 1.48 × 10³ ng/L for TEP and 0.12 ng/L for tripentyl phosphate (TPeP) in river water, and 15.5 ng/L for tris(2-chloroethyl) phosphate (TCEP) and 0.08 ng/L for tritolyl phosphate (TMPP) in tap water. TEP was the most abundant compound among the detected OPEs in all water types. The exposure of zebrafish embryos showed negligible effects of TEP, triphenyl phosphate (TPHP), and diphenyl phosphate (DPHP), while mixed solutions that mimic river water and wastewater composition disturbed the development of embryos and led to the altered transcription of genes relating to the hypothalamic-pituitary-thyroid (HPT) axis. In addition, the binding affinity between OPEs and a thyroid hormone receptor (TRβ) protein was further investigated by molecular docking modeling, which helped to estimate the effects of OPEs on TRβ. This research provides experimental and theoretical evidence for the ecotoxicological effects of OPEs in aquatic environments.

Microplastics are widespread across the global oceans, yet the potential risks of the ubiquitous environmental contaminant to marine organisms has been less known. Accumulation of microplastics and associated contaminants in marine fish, may pose adverse impacts to human health via seafood consumption. This study evaluated microplastic contamination in 24 fish species collected from Beibu Gulf, one of the world’s largest fishing grounds in South China Sea. Microplastics were detected in 12 fish species at an abundance of 0.027–1.000 items individual⁻¹ and found in fish stomach, intestines and gills with the count percentage of 57.7%, 34.6% and 7.7%, respectively. Transparent fibers were observed as the predominant microplastics, which might be ingested accidently by fish or transferred through other animals at lower trophic levels. Majority of microplastics were identified as polyester (44%) and nylon (38%), whereas polypropylene (6%), polyethylene (6%), and acrylics (6%) were also found. Relatively, higher microplastic abundances were found in demersal fish compared to the pelagic species. Overall, the abundance of microplastics was documented as relatively low in the commercial fish collected from the open water of Beibu Gulf, South China Sea.

The presence of polystyrene (PS) waste increases constantly. Styrofoam, the most popular form of PS, is one of the major plastic pollutants in the environment. An efficient and environmentally friendly method of PS recycling is still needed. The biodegradation of PS by insects has been presented by researchers as a promising alternative to chemical, mechanical and thermal methods. The main aim of this study was to assess the survival, growth, and development of yellow mealworms (the larvae of Tenebrio molitor) fed with PS to determine if the insects are able to use PS as a source of mass and energy. The Dynamic Energy Budget (DEB) model was used to analyze the effects of food type on the growth trajectory and metabolism of tested organisms. We investigated five possible modes of influence of PS diet on DEB model parameters including a decrease of food availability, an increase in somatic maintenance power, an increase in costs for structure, allocation of energy, and a decrease in somatic maintenance power. Our results show that changes in the development of larvae fed with PS are mainly caused by a decrease in reserves density and reaction of the organism to the insufficient food supply. The inability or difficulty in completing the life cycle of T. molitor larvae fed with PS raises doubts about the use of mealworms as an effective technology for utilizing polystyrene.

Light absorbing carbonaceous aerosols (LACA) consisting of black carbon (BC) and brown carbon (BrC) have received considerable attention because of their climate and health implications, but their sources, characteristics and fates remain unclear in Southeast Asia (SEA). In this study, we investigated spatio-temporal characteristics of LACA, their radiative properties and potential sources in Singapore under different weather conditions. Hourly BC concentrations, measured from May 2017 to March 2018, ranged from 0.31 μg/m³ to 14.37 μg/m³ with the mean value being 2.44 ± 1.51 μg/m³. High mass concentrations of BC were observed during the south-west monsoon (SWM, 2.60 ± 1.56 μg/m³) while relatively low mass concentrations were recorded during the north-east monsoon (NEM, 1.68 ± 0.96 μg/m³). There was a shift in the Absorption Ångström exponent (AAE) from 1.1 to 1.4 when the origin of LACA changed from fossil fuel (FF) to biomass burning (BB) combustion. This shift is attributed to the presence of secondary BrC in LACA, derived from transboundary BB emissions during the SWM. Lower AAE values were observed when local traffic emissions were dominant during the NEM. This explanation is supported by measurements of water-soluble organic carbon (WSOC) in LACA and the corresponding AAE values determined at 365 nm using a UV–vis spectrophotometer. The AAE values, indicative of the presence of brown carbon (BrC), showed that photochemically aged LACA contribute to an enhancement in the light absorption of aerosols. In addition, spatio-temporal characteristics of BC in the intra-urban environment of Singapore were investigated across diverse outdoor and indoor microenvironments. High variability of BC was evident across these microenvironments. Several air pollution hotspots with elevated BC concentrations were identified. Overall, the results stress a need to control anthropogenic emissions of BC and BrC in order to mitigate near-term climate change impacts and provide health benefits.

Global urbanization and plastic pollution has increased the availability and variety of substrates for sessile organisms, and are intensively used by invasive species for settlement. Despite extensive literature describing the strong association between artificial structures and invasive species, little effort has been directed towards identifying the larval traits that favor this selection. Larval selection and settlement are crucial as larvae actively search and interpret environmental cues to identify suitable habitats to settle. The aim of this research was to investigate if invertebrate larvae have a preference for a particular anthropogenic substrate, and how pre-settlement behaviors vary when encountering different substrates. We used two invasive bryozoan species, Bugula flabellata and Bugula neritina, which are commonly found in urbanized areas around the world. Energy expenditure during planktonic and benthonic stages, pre-settlement swimming/exploring behaviors, settlement and larval selectivity were quantified under laboratory conditions on different substrates (concrete, wood, polystyrene, polyvinyl chloride, polyethylene terephthalate and polycarbonate). The energy expenditure measured was higher in planktonic larvae than in early settled larvae. Larvae of both species swam less and explored more when exposed to plastic surfaces, suggesting a preference for this substrate and resulting in lower energy expenditures associated with searching for habitat. Larvae actively chose to settle on plastics rather than on wood or concrete substrates. The results suggest that for Bugula larvae, the likelihood of colonizing plastic surfaces is higher than other materials commonly found in urbanized coastal areas. The more quickly they adhere to artificial substrates the lower the energy expenditure, contributing to higher fitness in these individuals. The strong preference of invertebrate larvae for plastics can potentially extend the distribution range of many invasive marine species as they are able to travel long distances attached to floating debris. This phenomenon will likely exacerbate the introduction of exotic species into novel habitats.

To improve catalytic performance and stability of Ag nanoparticles (Ag NPs), a facile ultrasonication-assisted chemical reduction method was developed to fabricate reduced graphene oxide (rGO) aerogels loaded with 1–3 nm Ag NPs under the normal temperature and pressure. The ultrasonication facilitated the dispersion of Ag(I) in the form of silver ammonia and anchored onto GO nanosheets. Ag(I) and GO were simultaneously reduced to Ag(0) immobilizing onto 3D rGO hydrogels within the heterogeneous liquid phase, and ultimately formed 3D rGO-Ag NPs aerogels. The 3D rGO-Ag NPs aerogels displayed superb catalytic performance for the reduction of nitrobenzene (NB), 1,3-dinitrobenzene (DNB) and 4-nitrophenol (NP) into aniline, 1,3-diaminobenzene and 4-aminophenol, respectively. The individual reduction rate Kobs for NB, DNB and NP were 0.168 h−1, 0.109 h−1 and 0.092 h−1, which were much higher than those of other Ag NPs-based materials. Moreover, the immobilization of 1–3 nm Ag NPs in 3D rGO-Ag NPs was stable during the whole reduction reaction without aggregation and leaching. The high stability of Ag NPs in 3D rGO-Ag NPs and superb performance on catalytic reduction of nitroaromatic compounds (NACs) could be concluded into ultrasonication influence in the preparation procedure and synergistic effect of Ag NPs and 3D rGO in the catalytic reduction process. The simple ultrasonication-assisted chemical reduction approach provided a scaled-up application prospect in catalytic reduction of NACs by metal nanoparticle catalysts.

Nutrient effluents from urban and agricultural inputs have resulted in high concentrations of nitrate in freshwater ecosystems. Exposure to nitrate can be particularly threatening to aquatic organisms, but a quantitative synthesis of the overall effects on amphibians, amphipods and fish is currently unavailable. Moreover, in disturbed ecosystems, organisms are unlikely to face a single stressor in isolation, and interactions among environmental stressors can enhance the negative effects of nitrate on organisms. Here, the effects of elevated nitrate on activity level, deformity rates, hatching success, growth and survival of three taxonomic groups of aquatically respiring organisms are documented. Effect sizes were extracted from 68 studies and analysed using meta-analytical techniques. The influence of nitrate on life-stages was also assessed. A factorial meta-analysis was conducted to examine the effect of nitrate and its interaction with other ecological stressors on organismal survival. Overall, the impacts of nitrate are biased towards amphibians (46 studies) and fish (13 studies), and less is known about amphipods (five studies). We found that exposure to nitrate translates to a 79% decrease in activity, a 29% decrease in growth, and reduces survival by 62%. Nitrate exposure also increases developmental deformities but does not affect hatching success. Nitrate exposure was found to influence all life-stages except embryos. Differences in the sensitivity of nitrate among taxonomic groups tended to be negligible. The factorial meta-analysis (14 amphibians and two amphipod studies) showed that nitrate in combination with other stressors affects survival in a non-additive manner. Our results indicate that nitrate can have strong effects on aquatic organisms and can interact with other environmental stressors which compound the negative effects on survival. Overall, the impacts of nitrate and additional stressors are complex requiring a holistic approach to better conserve freshwater biodiversity in the face of ongoing global change.

Urbanisation is increasing globally at a rapid pace. Consequently, wild species face novel environmental stressors associated with urban sprawl, such as artificial light at night and noise. These stressors have pervasive effects on the behaviour and physiology of many species. Most studies have singled out the impact of just one of these stressors, while in the real world they are likely to co-occur both temporally and spatially, and we thus lack a clear understanding of the combined effect of anthropogenic stressors on wild species. Here, we experimentally exposed captive male great tits (Parus major) to artificial light at night and 24 h noise in a fully factorial experiment. We then measured the effect of both these stressors on their own and their combination on the amount and timing of activity patterns. We found that both light and noise affected activity patterns when presented alone, but in opposite ways: light increased activity, particularly at night, while noise reduced it, particularly during the day. When the two stressors were combined, we found a synergistic effect on the total activity and the nighttime activity, but an antagonistic effect on daytime activity. The significant interaction between noise and light treatment also differed among forest and city birds. Indeed, we detected a significant interactive effect on light and noise on daytime, nighttime, dusktime and offset of activity of urban birds, but not of forest birds. These results suggest that both artificial light at night and anthropogenic noise can drive changes in activity patterns, but that the specific impacts depend on the habitat of origin. Furthermore, our results demonstrate that co-occurring exposure to noise and light can lead to a stronger impact at night than predicted from the additive effects and thus that multisensory pollution may be a considerable threat for wildlife.

Soil application of Zn fertilizer is an effective approach to improve yield and Zn accumulation in wheat grain. However, it remains unclear whether repeated Zn application can result in high accumulation of heavy metals (HMs) in soils and grains and thus represents a potential risk for human consumption. This study aimed to evaluate the health risk assessment of HMs in a wheat production system which had continuously received 8 years of Zn application at varying rates (0, 2.3, 5.7, 11.4, 22.7, 34.1 kg Zn ha⁻¹). The results showed that Zn application significantly increased the soil total Zn concentration without affecting concentrations of As, Pb, Cd, Cu and Cr. Across Zn rates, Zn application increased grain concentrations of Zn, Pb and Cd by 75%, 51% and 14%, respectively, and reduced grain As concentration by 14%. The human health risk assessment revealed that the threshold hazard quotients for the individual HM were below 1, independent of Zn rates. The hazard index (HI) values at Zn rates of 11.4, 22.7 and 34.1 kg Zn ha⁻¹ were significantly greater than that at null Zn treatment. Furthermore, exposures to As, Cu and Zn accounted for 97% of HI at all Zn rates. Analysis of the threshold cancer risk with Pb and As showed that ingestion of wheat grain even from highest Zn application rate wouldn’t bring the lifetime carcinogenic risk. In contrast, long-term Zn application significantly reduced the carcinogenic risk of As by 9.7–26.5%. In conclusion, repeated soil applications of Zn at optimal rate (5.7 kg Zn ha⁻¹) didn’t cause health risk for Zn, Cu, Cd, Pb, Cr, and As, while improving productivity and grain Zn concentration of wheat to meet human recruitment. Our study highlights the importance of appropriate Zn fertilizer management in improving grain quality while reducing HMs risks from human consumption.