Evaluating speciation of arsenic (As) is essential to assess its risk in paddy soils. In this study, effects of phosphate on speciation of As in six paddy soils differing in redox status were studied over a range of pH (pH 3-9) and different background calcium (Ca) levels by batch adsorption experiments and speciation modeling. Contrasting effects of phosphate on As speciation were observed in suboxic and anoxic soils. Under suboxic conditions, phosphate inhibited Fe and As reduction probably due to stabilization of Fe-(hydr)oxides, but increased soluble As(V) concentration as a result of competitive adsorption between As(V) and phosphate. In anoxic soils, phosphate stimulated Fe and As reduction and caused increases of As(III) in soil solution under both acidic and neutral/alkaline pH. The LCD (Ligand and Charge Distribution) and NOM-CD (Natural Organic Matter-Charge Distribution) model can describe effects of pH, calcium and phosphate on As speciation in these paddy soils. The results suggest that phosphatefertilization may decrease (at low pH) or increase (at neutral/alkaline pH) As mobility in paddy soils under (sub)oxic conditions, but under anoxic conditions and in phosphorus deficient soils phosphate fertilization may strongly mobilize As by promoting microbial activities.

The overuse and misuse of antibiotics could promote the emergence of antibiotic resistance genes (ARGs) and pose a potential risk to human health and the ecological environment. In this study, fifteen antibiotics and their corresponding ARGs in water, sediment and sewage treatment plant (STP) effluent were analysed to investigate their occurrence and correlation in the Yangtze River (Jiangsu section) for the first time. The concentrations of erythromycin-H₂O (EM-H₂O) (2.08–30 ng L⁻¹) and ofloxacin (OFL) (290–8400 ng kg⁻¹) were the highest in the water and sediment, respectively, and EM-H₂O and clarithromycin (CLA) posed the highest risks to aquatic organisms. The concentrations of antibiotics in STP effluent were significantly higher (p < 0.05) than those in the water. Norfloxacin (NOR) was the most predominant antibiotic, with low removal efficiency (−38%-51%), in STPs; the concentration of NOR in the STP effluent was 4–6 orders of magnitude higher than that in the water. Moreover, the concentrations of antibiotics and their corresponding ARG abundance in downstream were higher than those in upstream, suggesting that STPs with high concentration levels might be an important source of river contamination. Additionally, the concentrations of antibiotics and the abundance of ARGs might increase after the sewage treatment process. The results also showed the prevalence of sul1 and sul2 in all the sampling sites. Significant correlations (p < 0.0001) were detected between int1 and sul1 and sul2, which resulted from the contribution of int1 to the propagation of ARGs. Overall, this study demonstrated the prevalence of antibiotics and ARGs and their inconsistent correlations in the Yangtze River (Jiangsu section) and provides support for further investigation of the occurrence and spread of antibiotics and ARGs.

Human-induced temperature changes influence coastal regions, both via thermal pollution and ocean warming, which exerts profound effects on the chemistry of metals and the physiology of organisms. However, it remains unknown whether the increased temperature of discharged water or ocean warming, as a result of climate change, lead to an increase of human health risks associated with the consumption of sea foods. In this study, the influence of temperature on metal accumulation by oysters was studied in individuals collected from a coastal area affected by the thermal water discharge of the Houshi Power Plant, China. The bioaccumulation factor (BAF) and oral bioavailability (OBA) of metals in oysters was determined. Elevated temperatures led to an increase in BAF for Cu, Zn, Hg, and Cd (p < 0.05), but no change was observed for As and Pb (p > 0.05). The OBA for Cd, As, and Pb correlated positively to elevated temperatures (p < 0.05). However, for Cu and Zn, OBA was negatively correlated with increasing temperature (p < 0.05). As, Pb, and Cd in the trophically available metal (defined as a sum of heat-stable proteins, heat-denaturable proteins, and organelles) was significantly elevated at the highest temperature seawater site (site A) compared to the lowest seawater site (site B). Thus, the irregular variation of OBA for each metal may be the result of variations in the subcellular distribution of metals and the protein quality influenced by the increased temperature. Moreover, the increased temperature and increased the hazard quotient values of As and Cd (p < 0.05 for As, n = 6, p < 0.05 for Cd, n = 6), which provided an indication of the potential risks of the consumption of oysters or other seafood to future warming under climate change scenarios.

Cadmium (Cd) and its forms has recently been a focus of attention due to its toxic effects on human health and the environment. We evaluated the atmospheric deposition of Cd during three consecutive winter seasons (2009–2011) at 10 mountain-top locations in the Czech Republic along the borders with Poland, Germany, Austria and Slovakia. Cadmium concentrations of soluble and insoluble forms in both horizontal (rime) and vertical (snow) deposition were determined using sector-field ICP-MS. Across the sites, 94% of the total winter Cd deposition occurred in the soluble (environmentally available) Cd form. Mean concentrations of soluble Cd in rime were six times higher than in snow (398 vs. 66 ng L⁻¹). Vertical deposition contributed as much as 41% to the total winter Cd input. Between-site variability in Cd deposition was large, ranging between 13 and 108 μg m⁻² winter⁻¹. Overall, Cd concentrations in winter deposition did not reach the drinking water limits and did not pose a direct threat for human health. Long-term trends (1996–2017) in winter Cd deposition were evaluated at six GEOMON sites (a monitoring network of small forested catchments). Since 1996, Cd input in winter atmospheric deposition decreased by 73–93%. Simultaneously, we found declines in between-site variability in winter Cd inputs. The highest recent winter Cd inputs were found at sites located in the northeast of the country. A north-south pollution gradient, which has frequently been mentioned in the literature, was not observed, with both northwestern sites and southern sites being among those with the lowest Cd pollution. Backward trajectories of the HYSPLIT model for fresh snow samples identified Poland and Germany as major transboundary Cd pollution sources for the Czech Republic.

Bacteria involved with ecosystem N cycling in the rhizosphere of submerged macrophytes are abundant and diverse. Any declines of submerged macrophytes can have a great influence on the abundance and diversity of denitrifying bacteria and anammox bacteria. Natural decline, tardy decline, and sudden decline methods were applied to cultivated Potamogeton crispus. The abundance of anammox bacteria and nirS denitrifying bacteria in rhizosphere sediment were detected using real-time fluorescent quantitative PCR of 16S rRNA, and phylogenetic trees were constructed to analyze the diversities of these two microbes. The results indicated that the concentration of NH₄⁺ in pore water gradually increased with increasing distances from the roots, whereas, the concentration of NO₃⁻ showed a reverse trend. The abundance of anammox bacteria and nirS denitrifying bacteria in sediment of declined P. crispus populations decreased significantly over time. The abundance of these two microbes in the sudden decline group were significantly higher (P > 0.05) than the other decline treatment groups. Furthermore, the abundances of these two microbes were positively correlated, with RDA analyses finding the mole ratio of NH₄⁺/NO₃⁻ being the most important positive factor affecting microbe abundance. Phylogenetic analysis indicated that the anammox bacteria Brocadia fuigida and Scalindua wagneri, and nirS denitrifying bacteria Herbaspirillum and Pseudomonas, were the dominant species in declined P. crispus sediment. We suggest the sudden decline of submerged macrophytes would increase the abundance of anammox bacteria and denitrifying bacteria in a relatively short time.

Although association between polycyclic aromatic hydrocarbons (PAHs) exposure and mitochondrial DNA copy number (mtDNAcn) was researched by traditional linear model extensively, most of these studies analyzed independent effect of each PAHs metabolite and adjust for the confounding other metabolites concomitantly, without considering others interactions. As a complex organic pollutant, a reasonable statistical method is needed to study toxic effects of PAHs.Therefore, we aimed to conduct a novel statistical approach, Bayesian Kernel Machine Regression (BKMR), to explore the effect of PAHs exposure on mtDNAcn among coke oven workers. In this cross-sectional study, the concentrations urinary of PAHs metabolites were measured using high performance liquid chromatography mass spectrometry (HPLC-MS). The mtDNAcn was measured using real-time quantitative polymerase chain reaction (RT-PCR) in peripheral blood of 696 Chinese coke oven workers. The relationship of urinary of PAHs metabolites and mtDNAcn were evaluated by BKMR model. And the results showed a significant negative effect of PAHs metabolites on mtDNAcn when PAHs metabolites concentrations were all above 35th percentile compared to the median and the statistically significant negative single-exposure effect of 2-OHNAP and 2-OHPHE on mtDNAcn when all of the other PAHs are fixed at a particular threshold (25th, 50th, 75th percentile). The changes in log 2-OHNAP and 2-OHPHE from the 25th to the 75th percentile when other PAHs metabolites were at the 50th percentile were associated with change in mtDNAcn of −0.082 (−0.021, −0.124) and −0.048 (−0.021, −0.090) respectively. And evidence of a linear effect of urinary 2-OHNAP and 2-OHPHE were found. Finally, our findings suggested that PAHs cumulative exposures and particularly single-exposure of 2-OHNAP and 2-OHPHE might compromise mitochondrial function by decreasing mtDNAcn in Chinese coke oven workers.

Following nine years since the Fukushima Dai-ichi Nuclear Power Plant Acciden (FDNPPA), it might be the time to draw a much clearer conclusion for the impact of FDNPPA on marine biota. In this work, the evolution of the FDNPPA derived ¹³⁴Cs, ¹³⁷Cs and ¹¹⁰ᵐAg in the neon flying squids in the Northwest Pacific from 2011 to 2018 were studied. The background level of ¹³⁷Cs in neon flying squids (<0.10 Bq/kgfᵣₑₛₕ wₑᵢgₕₜ with the average of 0.017 Bq/kgfᵣₑₛₕ wₑᵢgₕₜ) before FDNPPA were estimated. The radioactive levels of ¹³⁴Cs, ¹³⁷Cs and ¹¹⁰ᵐAg in neon flying squids decreased with time. ¹³⁴Cs and ¹¹⁰ᵐAg decreased at the half-lives of 7.6 months and 5.7 months at the population level, respectively. After May 2014, ¹³⁴Cs and ¹¹⁰ᵐAg cannot be detected and ¹³⁷Cs activities returned to the background level before FDNPPA. BCFs of cesium isotopes (3.7–17.7 with the average of 10.8) and ¹¹⁰ᵐAg (∼7 × 10⁴) for neon flying squids were estimated. The amount of ¹¹⁰ᵐAg released into the Northwest Pacific (∼20-∼26 TBq) were firstly calculated using a ¹³⁴Cs/¹¹⁰ᵐAgₐcₜᵢᵥᵢₜy ᵣₐₜᵢₒ method. Radiation dose assessment demonstrated that it was far from causing radiation harm to neon flying squids in the open ocean of Northwest Pacific and humans who ingested these neon flying squids.

Excess nitrate has been reported to be associated with many adverse effects in humans and experimental animals. However, there is a paucity of information of the effects of nitrate on intestinal microbial community. In this study, the effects of nitrate on development, intestinal microbial community, and metabolites of Bufo gargarizans tadpoles were investigated. B. gargarizans were exposed to control, 5, 20 and 100 mg/L nitrate-nitrogen (NO₃–N) from eggs to Gosner stage 38. Our data showed that the body size of tadpoles significantly decreased in the 20 and 100 mg/L NO₃–N treatment group when compared to control tadpoles. Exposure to 20 and 100 mg/L NO₃–N also caused indistinct cell boundaries and nuclear pyknosis of mucosal epithelial cells in intestine of tadpoles. In addition, exposure to NO₃–N significantly altered the intestinal microbiota diversity and structure. The facultative anaerobic Proteobacteria occupy the niche of the obligately anaerobic Bacteroidetes and Fusobacteria under the pressure of NO₃–N exposure. According to the results of functional prediction, NO₃–N exposure affected the fatty acid metabolism pathway and amino acid metabolism pathway. The whole-body fatty acid components were found to be changed after exposure to 100 mg/L NO₃–N. Therefore, we concluded that exposure to 20 and 100 mg/L NO₃–N could induce deficient nutrient absorption in intestine, resulting in malnutrition of B. gargarizans tadpoles. High levels of NO₃–N could also change the intestinal microbial communities, causing dysregulation of fatty acid metabolism and amino acid metabolism in B. gargarizans tadpoles.

Plastics pollution has been recognized as a serious environmental problem. Nevertheless, new plastic uses, and applications are still increasing. Among these new applications, three-dimensional resin printers have increased their use and popularity around the world showing a vertiginous annual-sales growth. However, this technology is also the origin of residues generation from the alcohol cleaning procedure at the end of each printing. This alcohol/resin mixture can originate unintentionally very small plastic particles that usually are not correctly disposed, and as consequence, could be easily released to the environment. In this work, the nanoparticle generation from 3D printer’s cleaning procedure and their physicochemical characterization is reported. Nano-sized plastic particles are easily formed when the resin residues are dissolved in alcohol and placed under UV radiation from sunlight. These nanoparticles can agglomerate in seawater showing an average hydrodynamic diameter around 1 μm, whereas the same nanoparticles remain dispersed in ultrapure water, showing a hydrodynamic diameter of ≈300 nm. The formed nanoparticles showed an isoelectric point close to pH 2, which can facilitate their interaction with other positively charged pollutants. Thus, these unexpected plastic nanoparticles can become an environmental issue and public health risk.

Excessive nitrogen (N) losses from food production and consumption have resulted in noticeable environmental impacts, e.g., air pollution and climate change, saturation of soil N, and water eutrophication. In the present study, a rural-scale N flow model was constructed in Quzhou county, Hebei province to investigate the characteristics of the N flux, N use efficiency (NUE), and N loss and their driving factors in the food production and consumption system during 1997–2017. Our results show that the N fluxes of the crop-production subsystem (CPS), the livestock-breeding subsystem (LBS), and the household-consumption subsystem (HCS) all followed an upward trend. During 1997–2017, the N losses from the system were high (51.38%), and the CPS was a major source. When the N fertilizer application level was optimal (403–475 kg N ha⁻¹), the NUE in the CPS (NUEc) decreased sharply, resulting in a higher N cost than that observed at larger scales. For the LBS, the NUE of animal feed (NUEa) was high (46.37%); however, the waste utilization rate of the HCS was below 30%. The chemical fertilizer application level, feed input, animal-food demand, and livestock manure application level were closely related to the environmental N losses. Due to the lack of reasonable N treatment and utilization methods, the increasing N losses are expected to have a large future impact on environmental issues such as haze, soil acidification, and frequent algal blooms. Therefore, adjusting N management in the processes of food production and consumption is of great significance to the improvement of global NUE and reduction of environmental pollution.