Both surface and satellite observations have shown a decrease in NOₓ emissions in East Asian countries in recent years. In order to reflect the recent NOx emission reduction and to investigate its impact on surface O₃ concentrations in Asian megacities, we adjusted two bottom-up regional emission inventories of which base years are 2006 (E2006) and 2010 (E2010), respectively. We applied direct and relative emission adjustments to both E2006 and E2010 to constrain NOx emissions using OMI NO₂ vertical column densities. Except for the relative emission adjustment with E2006, modeling results with adjusted emissions exhibit that NOx emissions over East Asian megacities (Beijing, Shanghai, Seoul, and Tokyo) in the bottom-up inventories are generally overestimated. When the direct emission adjustment is applied to E2006, model biases in the Seoul Metropolitan Area (SMA), South Korea are reduced from 24 ppb to 2 ppb for NOx (=NO+NO₂) and from −9 ppb to 0 ppb for O₃. In addition, NO₂ model biases in Beijing and Shanghai in China are reduced from 8 ppb to 18 ppb–0 ppb and 1 ppb, respectively. Daily maximum 8-h average O₃ model biases over the same places are decreased by 8 ppb and 14 ppb. Further analyses suggest that the reduction in domestic South Korean NOₓ emissions plays a significant role in increasing O₃ concentrations in SMA. We conclude that the current strong drive to reduce NOₓ emissions as part of the strategy to lower particulate matter concentrations in South Korea can account for increased O₃ concentrations in recent years and suggest that more aggressive NOₓ emissions will be necessary soon.

Nonylphenol (NP) is a chemical raw material and intermediate which is mainly used in the production of surfactants, lubricating oil additives and pesticide emulsifiers. NP is reported to be toxic on the immune system, nervous system and reproductive system due to its binding to estrogen receptors. However, the toxicity of NP on mammalian oocyte quality remains unclear. In present study, we explored the effects of NP exposure on mouse oocyte maturation. Our results showed that 4 weeks of NP exposure increased the number of atresia follicles and decreased oocyte developmental competence. Transcriptomic analysis indicated that NP exposure altered the expression of more than 800 genes in oocytes, including multiple biological pathways. Subcellular structure examination indicated that NP exposure disrupted meiotic spindle organization and caused chromosome misalignment. Moreover, aberrant mitochondrial distribution and decreased membrane potential were also observed, indicating that NP exposure caused mitochondria dysfunction. Further analysis showed that NP exposure resulted in the accumulation of reactive oxygen species (ROS), which causes oxidative stress; and the NP-exposed oocytes showed positive Annexin-V signal, indicating the occurrence of early apoptosis. In summary, our results indicated that NP exposure reduced oocyte quality by affecting cytoskeletal dynamics and mitochondrial function, which further induced oxidative stress and apoptosis in mice.

Human activities such as agriculture, aquaculture, and industry can lead to the pollution of coastal waters by trace organic contaminants (TrOCs), and the TrOCs can pose a threat to marine ecosystems. Therefore, it is essential to investigate the occurrence, distribution, and ecological risk of the TrOCs in coastal waters. Previous studies adopting conventional analytical methods have focused on a limited number of targets. Herein, a comprehensive and systematic determination was undertaken to target 484 TrOCs in the waters around the Liaodong Peninsula, China. Eighty-six TrOCs were detected at concentrations of up to 350 ng L⁻¹, and 25 TrOCs were detected at a frequency of >50%. Pesticides were the predominant pollutants, occurring at high concentrations with large detection frequencies. Ecological risks were assessed for single pollutants and mixtures based on the risk quotient and concentration addition modeling, respectively. The detected pesticides posed relatively high risk to aquatic organisms, while pharmaceuticals, consumer products, and other pollutants posed little or no risk. TrOC mixtures posed extremely high risk to aquatic organisms, which represented a significant threat to the marine environment and local communities. The results described here provide useful information that can inform China’s “Action Plan for Prevention and Control of Water Pollution”.

Daphnids, including the water flea Daphnia magna, can be exploited for wastewater treatment purposes, given that they are filter feeder organisms that are able to remove suspended particles from water. The presence of pollutants, such as microplastics and chemicals, might be considered stressors and modify the behaviour and survival of D. magna individuals. The impact of the cumulative pollutants that regulate the fate of living organisms has yet to be fully determined. Here we present the effect of double and triple combinations of stressors on the behaviour of D. magna. The impact of water temperature, ammonium and polystyrene microplastics on the filtration capacity and survival of D. magna is studied. Water temperatures of 15 °C, 20 °C and 25 °C, microplastic-to-food ratios of 25% and 75%, and ammonium concentrations of 10 and 30 mg N–NH₄⁺ L⁻¹ are tested after making dual and triple combinations of the parameters. A synergistic effect between water temperature and ammonium is normally observed but not in the case of the lower values of ammonium concentration and temperature. The combination of three stressors (water temperature, microplastics and ammonium) is also found to be synergistic, producing the greatest impact on D. magna filtration capacity and reducing their survival. In comparison with the effect of the two stressor conditions, the combination of the three stressors caused a reduction of between 13.1% and 91.7% in the t₅₀% time (the time required for a 50% reduction in the D. magna filtration capacity) and a reduction of between 4.8% and 54.5% in TD50 (the time for 50% mortality).

The biodegradable S,S-ethylenediaminedisuccinic acid (EDDS) is a promising chelant for chelant-assisted phytoextraction of trace metals in polluted soil. The interactions between EDDS and trace metals/major elements in the soil affect the metal bioavailability and their subsequent phytoextraction efficiency. This study aimed to investigate the macroscopic and molecular-level interactions of EDDS with Cu in the rhizosphere and non-rhizosphere of a Cu-polluted agricultural soil. A multi-interlayer rhizobox planted with ryegrass was used to simulate the transport of EDDS and Cu from the non-rhizosphere to rhizosphere soils. The results showed that EDDS (5 mM kg⁻¹) significantly dissociated Cu (285–690 fold), Fe (by 3.47–60.2 fold), and Al (2.43–5.31 fold) from the soil in comparison with a control group. A combination of micro-X-ray fluorescence, X-ray absorption near-edge structure spectroscopy, and sequential extraction analysis revealed that EDDS primarily chelated the adsorbed fraction of Cu by facilitating the dissolution of goethite. Moreover, as facilitated by ryegrass transpiration, CuEDDS was moved from the non-rhizosphere to rhizosphere and accumulated in ryegrass. In situ processes of Cu extraction and transport by EDDS in the rhizosphere were further elucidated with chemical speciation analysis and geochemical modeling methods.

Aerobic performance in fish is linked to individual and population fitness and can be impacted by anthropogenic contaminants. Exposure to some engineered nanomaterials, including silver nanoparticles (nAg), reduces rates of oxygen consumption in some fish species, but the underlying mechanisms remain unclear. In addition, their effects on swim performance have not been studied. Our aim was to quantify the impact of exposure to functionalized nAg on aerobic scope and swim performance in rainbow trout (Oncorhychus mykiss) and to characterize the contribution of changing rates of protein synthesis to these physiological endpoints. Fish were exposed for 48 h to 5 nm polyvinylpyrolidone-functionalized nAg (nAgPVP; 100 μg L⁻¹) or 0.22 μg L⁻¹ Ag⁺ (as AgNO₃), which was the measured quantity of Ag released from the nAgPVP over that time period. Aerobic scope, critical swimming speed (Ucᵣᵢₜ), and fractional rates of protein synthesis (Kₛ), were then assessed, along with indicators of osmoregulation and cardiotoxicity. Neither nAgPVP, nor Ag⁺ exposure significantly altered aerobic scope, its component parts, or swim performance. Kₛ was similarly unaffected in 8 tissue types, though it tended to be lower in liver of nAgPVP treated fish. The treatments tended to decrease gill Na⁺/K⁺-ATPase activity, but effects were not significant. The latter results suggest that a longer or more concentrated nAgPVP exposure may induce significant effects. Although this same formulation of nAgPVP is bioactive in other fish, it had no effects on rainbow trout under the conditions tested. Such findings on common model animals like trout may thus misrepresent the safety of nAg to more sensitive species.

Heavy metal contamination is a serious environmental problem commonly monitored in various organisms. Small wild rodents are ideal biological monitors to show the extent of environmental pollution. The aim of this study was to evaluate the adverse effects of marble and stone quarries on the Levant vole, Microtus guentheri, inhabiting some polluted sites. In this context, Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was used to analyze distribution of thirteen heavy metals (Fe, Al, Zn, Cu, Cr, Mn, Ni, B, Pb, As, Co, Cd, and Hg) in the organs (skins, bones, muscles, livers and kidneys) of the biological specimens, and the comet assay revealed DNA damage in blood lymphocytes for the first time. This study was conducted at close to the marble and stone quarries at Korkuteli, Antalya-Turkey during spring, summer, autumn (2017) and winter (2018) seasons. In spring and summer, genetic damage in blood lymphocytes from all polluted sites (sites 1–5) was significantly higher than that of controls, while in autumn it was higher in samples from three sites (sites 3–5). In terms of heavy metal distribution in organs, we found depositions of Fe, Al, Zn, Ni, Mn, Cr, Co, As and Pb primarily in the skin with its derivatives, Cu and Cd deposits in the kidney, Cu, Cd and B deposits in the liver, and As and Pb depositions in the bones. The study shows that certain organs (especially skin with its derivatives) and blood lymphocytes of Levant vole can be used as ideal indicators of heavy metal pollution. Our results suggest that the Korkuteli area could already be under the threat of heavy metal pollution.

Two farmed freshwater fish species Nile tilapia (Oreochromis niloticus) and jade perch (Scortum barcoo) were cultured with food waste-based diets and compared with commercial formulated control diet for a period of six months. Sixteen priority polycyclic aromatic hydrocarbons (PAHs) in the diets and cultured fish meat were tested by gas chromatography–mass spectrometry. No significant differences of ∑PAHs were observed between Nile tilapia and jade perch fed with food waste-based diets and control diet (p > 0.05). However, there were significantly higher concentration of ∑PAHs in market fish compared with the same species of fish fed by food waste-based diets (p < 0.05). Thus, the food waste-based diets have a potential to lower the PAH concentrations in farmed fish when compared with market fish. Based on the PAH concentrations, a human health risk assessment was made. The results indicated there were no non-cancer and very low cancer risks of consuming fish cultured with food waste-based diets at the 95th centile (Nile tilapia: hazard index (HI adult) = 0.343 × 10−3, HI children = 0.614 × 10−3 and cancer risk value = 0.943 × 10−6; jade perch: HI adult = 0.456 × 10−3, HI children = 0.814 × 10−3 and cancer risk value = 0.291 × 10−6). In general, the fish fed with food waste-based diets were unlikely to cause adverse health effects, based on the concentrations of PAHs. There is great potential for using food waste-based diets as an alternative to commercial feeds for cultivating freshwater fish.

Urbanization is conducive to promoting social development and improving living standards. However, the changing land use attributed to urbanization has placed both the environment and humans at risk. Based on the long-term monitoring and the land use change during 2010–2017, we investigated the exposure of fluoride (F) and arsenic (As) in groundwater. We analyzed the temporal and spatial variation of F and As from different land use changes. The study assessed health risk for children by calculating carcinogenic risk and non-carcinogenic risk. Furthermore, we mapped the distribution pattern of F and As using GIS. For the 768 water samples collected from 2010 to 2017, F concentrations ranged between 0.10 and 5.70 mg L⁻¹ (M = 0.68 ± 0.02 mg L⁻¹), As concentrations ranged between 0.50 and 71.50 μg L⁻¹ (M = 4.28 ± 0.28 μg L⁻¹). A concerning result showed that 6.77% of F concentrations larger than 1.5 mg L⁻¹ and 11.46% of As concentrations larger than 10 μg L⁻¹ based on the recommendation by WHO, respectively. Results proved that land use change caused by human activity increased groundwater pollution and placed human health at risk. High F and As risk were found in southern Taiyuan City. In particular, the groundwater of industrial land suffered from more severe pollution, especially at the frontier of urban and suburban areas in the southern part of Taiyuan City. Land use change attributed to industrial land resulted in major increases in the F and As concentrations in groundwater across 2010–2017. Both carcinogenic risk and non-carcinogenic risk in 2016–2017 were higher than that in 2010–2015. Rational land use planning, strict groundwater protection policies and the regular monitoring of pollution levels are necessary in order to prevent the adverse health of residents.

Nitrogen pollution of groundwater has created problems worldwide. Riparian zones form a connection hub for terrestrial and aquatic ecosystems. As a potential source of ammonium in groundwater, aquitards have an important effect on the environment of riparian zones. The spatial distribution and factors influencing the ammonium content in the riparian zone aquitard of a small watershed were analyzed through three geological boreholes with increasing distances from the river: boreholes A > B > C. The results show that the distribution of ammonium was closely related to the lithology of sediments. Under the influence of the river and floods, the average content of ion exchange form of ammonium of sediments in borehole A (stable sedimentary environment) was 94.31 mg kg⁻¹, accounting for 21.2% of the transferable ammonium. The average proportions of ion exchange form of ammonium in the transferable ammonium of boreholes B and C (unstable sedimentary environment) were 19.1% and 17.4%, respectively. The carbonate and iron-manganese oxide forms of ammonium content of sediments in three boreholes were 0.96–15.28 mg kg⁻¹ and 2.3–54.4 mg kg⁻¹, respectively; this was mainly affected by the pH and Eh of the sedimentary environment. Organic sulfide, the form of transferable ammonium of sediments mainly exists in organic matter. The ammonium content in pore water generally increased with depth and was mainly derived from the mineralization of humic-like organic matter in borehole A. The ammonium in pore water in boreholes B and C mixed with ammonium from the mineralization of organic matter and the desorption of ion exchange form ammonium within sediments. The ammonium content in the pore water (up to 5.34 mg L⁻¹) was much higher than the limit for drinking water of 0.5 mg L⁻¹ in China. Therefore, the aquitard has a high risk of releasing ammonium and poses a certain threat to the quality of groundwater.