Plastic polymers such as polyvinyl chloride (PVC) may contain chemical additives, such as lead (Pb), that are leachable in aqueous solution. The fragmentation into microplastics (MPs) of plastics such as PVC may facilitate desorption of chemical additives and increase exposure of aquatic animals. In this study, the role of chemical additives in the aqueous toxicity of PVC, high-density polyethylene (HDPE) and polyethylene terephthalate (PET) MPs were investigated in early-life stage zebrafish (Danio rerio) by assessment of changes in expression of biomarkers. Exposure of zebrafish larvae to PVC for 24 h increased expression of metallothionein 2 (mt2), a metal-binding protein, but no changes in expression of biomarkers of estrogenic (vtg1) or organic (cyp1a) contaminants were observed. HDPE and PET caused no changes in expression of any biomarkers. A filtered leachate of the PVC also caused a significant increase in expression of mt2 and indicated that a desorbed metal additive likely elicited the response in zebrafish. Metal release was confirmed by acid-washing the MPs which mitigated the response in mt2. Metal analysis showed Pb leached from PVC into water during exposures; at 500 mg PVC L⁻¹ in water, 84.3 ± 8.7 μg Pb L⁻¹ was measured after 24 h. Exposure to a Pb-salt at this concentration caused a comparable mt2 increase in zebrafish as observed in exposures to PVC. These data indicated that PVC MPs elicited a response in zebrafish but the effect was indirect and mediated through desorption of Pb from PVC into the exposure water. Data also indicated that PVC MPs may act as longer-term environmental reservoirs of Pb for exposure of aquatic animals; the Pb leached from PVC in 24 h in freshwater equated to 2.52% of total Pb in MPs leachable by the acid-wash. Studies of MPs should consider the potential role of chemical additives in toxicity observed.

For further understanding leaching characteristics of heavy metals in tailings and better immobilization on heavy metals against acid rain, batch experiments were conducted. The leaching results of Cu(II), Zn(II), Cd(II) and Mn(II) can be well fit by second-order kinetics equation, and Pb(II) can be well fit by two-constant equation. The leaching intensity of heavy metals in tailings was ranged as: Mn(II)> Cu(II)> Cd(II)> Zn(II)> Pb(II). Triethylenetetramine functioned montmorillonite (TETA-Mt) was successfully synthesized and can obtain simultaneous immobilization effect compared with Mt and TETA, and immobilization rates on Cu(II), Cd(II), Mn(II) and Zn(II) can reach above 90%, the immobilization rate on Pb(II) can reach more than 75%. The mechanisms for efficient immobilization of heavy metals on TETA-Mt included buffering and adsorption abilities. The mechanism for TETA-Mt adsorption of heavy metals included physical absorption, chelation and chemical sedimentation. The results showed that TETA-Mt can be applied to effective immobilization of heavy metals in tailings and efficient remediation of acid mine drainage (AMD) in acid rain area.

The lag effect in the polar organic chemical integrative sampler (POCIS) equipped with a polyethersulfone (PES) membrane (POCIS-PES) is a potential limitation for its application in water environments. In this study, a POCIS with a poly(tetrafluoroethylene) (PTFE) membrane (POCIS-PTFE) was investigated for circumventing membrane sorption in order to provide more reliable concentration measurements of organic contaminants. Sampler characteristics such as sampling rates (RS) and sampler-water partition coefficients (KSW) were similar for POCIS-PES and POCIS-PTFE, indicating that partitioning into Oasis HLB as the receiving phase dominates the overall partitioning from the aqueous phase to the POCIS. Membrane sorption was quantified in both laboratory and field experiments. Although POCIS-PTFE showed minor membrane sorption, the PTFE membranes were not robust enough to prevent changes in the sorption of the pollutants to the inner Oasis HLB sorbent due to biofouling. This was reflected in significant ionization effects in the electrospray ionization (ESI) source during the LC-MS/MS analysis. Despite clear differences in the ionization effects, the two POCISs types provided similar time-weighted average (CTWA) concentrations after a two-week passive sampling campaign in surface water and the outflow of a wastewater treatment plant. This study contributes to a more detailed understanding of POCIS application by providing a quantitative evaluation of membrane sorption and its associated effects in the laboratory and field.

The incorporation of crop straw with fertilization is beneficial for soil carbon sequestration and cropland fertility improvement. Yet, relatively little is known about how fertilization regulates the emissions of the greenhouse gas nitrous oxide (N₂O) in response to straw incorporation, particularly in soils subjected to long-term fertilization regimes. Herein, the arable soil subjected to a 31-year history of five inorganic or organic fertilizer regimes (unfertilized; chemical fertilizer application, NPK; 200% NPK application, 2 × NPK; manure application, M; NPK plus manure application, NPKM) was incubated with and without rice straw to evaluate how historical fertilization influences the impact of straw addition on N₂O emissions. The results showed that compared to the unfertilized treatment, historical fertilization strongly increased N₂O emissions by 0.48- to 34-fold, resulting from increased contents of hot water-extracted organic carbon (HWEOC), NO₃⁻, and available phosphorus (Olsen-P). Straw addition had little impact on N₂O emission from the unfertilized and NPK treatments, primarily due to Olsen-P limitation. In contrast, straw addition increased N₂O emissions by 102–316% from the 2 × NPK, M, and NPKM treatments as compared to the corresponding straw-unamended treatments. These results indicated that N₂O emissions in response to straw addition were largely regulated by historical fertilization. The N₂O emissions were closely associated with the depletion of NO₃⁻ and decoupled from change in NH₄⁺ content, suggesting that NO₃⁻ was the main substrate for N₂O production upon straw addition. The stoichiometric ratios of HWEOC to mineral N and mineral N to Olsen-P were key factors affecting N₂O emissions, underscoring the importance of resource stoichiometry in regulating N₂O emissions. In conclusion, historical fertilization largely regulated the impacts of crop straw incorporation on N₂O emissions via shifts in NO₃⁻ depletion and the stoichiometry of HWEOC, mineral N, and Olsen-P.

Dichlorvos is a common crop insecticide widely used by people which causes extensive and serious environmental pollution. However, it has been shown that organophosphorus poisoning causes energy metabolism and neural disorders. The overall purpose of this study was to investigate the damage to brain tissue and the changes in AMPK signaling pathway-related gene expression after dichlorvos poisoning in chickens. White-feathered broiler chickens, as the research subjects of this experiment, were divided into three groups: control group, low-dose group (77.5% dichlorvos at 1.13 mg/kg dose) and high-dose group (77.5% dichlorvos at 10.2 mg/kg dose). Clinical symptoms were observed after modeling, and an integrative analysis was conducted using HE staining microscopy, immune-histochemical microscopy, electron microscopy and PCR arrays. The results showed that the high-dose group had more obvious dyspnea, salivation, convulsion and other neurological phenomena. Pathological sections showed that nuclear disintegration of neurons was most obvious in the low-dose group, and apoptosis of brain cells was most obvious in the high-dose group, and the mitochondrial structure was destroyed in the two poisoned group, i.e. low-dose group and high-dose group. PCR arrays showed that AMPK signaling pathway was inhibited and the expressions of genes involved in energy metabolism (ACACA and PRKAA1) were significantly changed. Furthermore, genes associated with protein synthesis (EIF4EBP1) were significantly upregulated. FASN and HMGCR expressions were significantly increased. There were significant changes in the expressions of cell cycle-related genes (STK11, TP53 and FOXO3). Organophosphate poisoning can cause a lot of nuclear disintegration of brain neurons, increases cell apoptosis, disrupts the energy metabolism of mitochondrial structure, and inhibits the AMPK signaling pathway. These results provide a certain idea and basis for studying the mechanism of AMPK signaling after organophosphorus poisoning and provide a research basis for the prevention and treatment of organophosphorus poisoning.

Facing serious air pollution problems, the Chinese government has taken numerous measures to prevent and control air pollution. Understanding the sources of pollutants is crucial to the prevention of air pollution. Using numerical simulation method, this study analysed the contributions of the total local emissions and local emissions from different sectors (such as industrial, traffic, resident, agricultural, and power plant emissions) to PM₂.₅ concentration, backward trajectory, and potential source regions in Tangshan, a typical heavy industrial city in north China. The impact of multi-scale meteorological conditions on source apportionment was investigated. From October 2016 to March 2017, total local emissions accounted for 46.0% of the near-surface PM₂.₅ concentration. In terms of emissions from different sectors, local industrial emissions which accounted for 23.1% of the near-surface PM₂.₅ concentration in Tangshan, were the most important pollutant source. Agricultural emissions were the second most important source, accounting for 10.3% of the near-surface PM₂.₅ concentration. The contributions of emissions from power plants, traffic, residential sources were 2.0%, 3.0%, and 7.2%, respectively. The contributions of total local emissions and emissions from different sectors depended on multi-scale meteorological conditions, and static weather significantly enhanced the contribution of regional transport to the near-surface PM₂.₅ concentration. Eight cluster backward trajectories were identified for Tangshan. The PM₂.₅ concentration for the 8 cluster trajectories significantly differed. The near-surface PM₂.₅ in urban Tangshan (receptor point) was mainly from the local emissions, and another important potential source region was Tianjin. The results of the source apportionment suggested the importance of joint prevention and control of air pollution in some areas where cities or industrial regions are densely distributed.

Australian tropical freshwaters can experience extreme seasonal variability in rainfall and run off, particularly due to pulse events such as storms and cyclones. This study investigated how seasonal variability in dissolved organic matter (DOM) quality impacted the chronic toxicity of copper to a tropical green alga (Chlorella sp.) in the presence of two concentrations of DOM (low: ∼2 mg C/L; high: ∼10 mg C/L) collected from three tropical waters. Copper speciation and lability were explored using diffusive gradients in thin-films (DGT) and modelled maximum dynamic concentrations (cᵈʸⁿₘₐₓ) using data derived from the Windermere Humic Aqueous Model (WHAM VII). Relationships between copper lability and copper toxicity were assessed as potential tools for predicting toxicity. Copper toxicity varied significantly with DOM concentration, source and season. Copper toxicity decreased with increasing concentrations of DOM, with 50% growth inhibition effect concentrations (EC₅₀) increasing from 1.9 μg Cu/L in synthetic test waters with no added DOM (0.34 mg C/L) up to 63 μg Cu/L at DOM concentrations of 9.9 mg C/L. Copper toxicity varied by up to 2-fold between the three DOM sources and EC₅₀ values were generally lower in the presence of wet season DOM compared to dry season DOM. Linear relationships between DGT-labile copper and dissolved copper were significantly different between DOM source, but not concentration or season. Modelled cᵈʸⁿₘₐₓ consistently under-predicted labile copper in high DOM treatments compared to DGT measurements but performed better in low DOM treatments, indicating that this method is DOM-concentration dependent. Neither speciation method was a good surrogate for copper toxicity in the presence of different sources of natural DOM. Our findings show that DOM source and season, not just DOM concentration, affect copper toxicity to freshwater biota. Therefore, DOM quality should be considered as a toxicity-modifying factor for future derivation of bioavailability-based site-specific water quality guideline values.

Environmental colloids play crucial roles in the transport of environmental pollutants in porous media by acting as pollutant carriers. In this work, the dispersion stability and correlated transport of kaolinite colloid were investigated as a function of solution pH, solution ionic strength, and concentration of humic acid (HA), the roles of kaolinite colloid in driving Eu(III) transport were discussed. The results showed that the dispersion of kaolinite colloid was favorable at alkaline and extremely acidic pH values, the trend of aggregation with varying pH was critically reversed at pH ∼3.2 due to the transformation of surface electrical properties. Cations with higher valence and mineral affinity showed a more significant contribution in inducing colloid aggregation, which was generally in accordance with the Schulze-Hardy rule and Hofmeister series. HA greatly increased the colloid stability by altering the surface electrostatic potential and steric effect. The Derjguin-Landau-Verwey-Overbeek (DLVO) model suggested that the electrostatic force between colloidal particles controlled the aggregation and destabilizing trend of colloid, and the theoretically calculated critical coagulation concentration was consistent with that determined from kinetic aggregation experiments. The roles of kaolinite colloid in driving Eu(III) transport varied under different conditions, and the transport behavior was highly correlated with the dispersion stability trend of colloid. These results can provide an enhanced understanding of the environmental fate of kaolinite colloid as well as commensal pollutants.

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.

Shortly after an atmospheric release, the interception of radionuclides by crop canopies represents the main uptake pathway leading to food chain contamination. The food chain models currently used in European emergency decision support systems require a large number of input parameters, which inevitably leads to high model complexity. In this study, we have established a new relationship for wet deposited radionuclides to simplify the current modelling approaches. This relationship is based on the hypothesis that the stage of plant development is the key factor governing the interception of radionuclides by crops having horizontally oriented leaves (planophile crops). The interception fraction (f) and the leaf area index normalized (fLAI) and mass normalized (fB) interception fractions were assessed for spinach (Spinacia oleracea) and radish (Raphanus sativus) at different stages of plant development and for different contamination treatments and plant densities. A database of 191 f values for Cs-137 and Th-229 was built and complemented with existing literature covering various radionuclides and crops with similar canopy structure. The overall f increased with the plant growth, while the reverse was observed for fB. The fLAI significantly decreased by doubling the contaminated rainfall deposited. Fitting a multiple linear regression to predict the f value as a function of the standing biomass (B), and the radionuclide form (anion and cation) led to a better estimation of the interception (R² = 81%) than the ECOSYS-87 model (R² = 35%). Hence, the simplified modelling approach here proposed seems to be a suitable risk assessment tool as fewer parameters will minimize the model complexity and facilitate the decision-making procedures in case of emergencies, when countermeasures need to be identified and implemented promptly.