To assess organochlorine compound (OC) contamination, its possible sources, and adverse health impacts on giant pandas, we collected soil, bamboo, and panda fecal samples from the habitat and research center of the Qinling panda (Ailuropoda melanoleuca qinlingensis)—the rarest recognized panda subspecies. The polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) concentrations were comparatively low which suggests that moderate sources of OC pollution currently. OC levels were lower in samples from nature reserve than in those collected from pandas held in captivity, and OC levels within the reserve increased between functional areas in the order: core, buffer and experimental. The distribution patterns, and correlation analyses, combined with congener distributions suggested PCBs and OCPs originated from similar sources, were dispersed by similar processes, being transported through atmosphere and characterized by historical residues. Backward trajectory analyses results, and detected DRINs (aldrin, dieldrin, endrin and isodrin) both suggest long-range atmospheric transport of pollution source. PCBs pose potential cancer risk, and PCB 126 was the most notable toxicant as assessed be the high carcinogenic risk index. We provide data for health risk assessment that can guide the identification of priority congeners, and recommend a long-term monitoring plan. This study proposes an approach to ecotoxicological threats whereby giant pandas may be used as sentinel species for other threatened or endangered mammals. By highlighting the risks of long-distance transmission of pollutants, the study emphasizes the importance of transboundary cooperation to safeguard biodiversity.

Urban green infrastructure is closely linked to the alleviation of pollution from atmospheric particulate matter. Although particle deposition has been shown to depend on leaf characteristics, the findings from earlier studies are sometimes ambiguous due to the lack of controlling variables. In this study, we investigated the impact of leaf morphological characteristics on PM₂.₅ dry deposition velocity by employing a control-variable approach. We focused on four indices: trichome density, petiole length, aspect ratio (width-to-length ratio), and fractal deviation. For each index, tree species were chosen from the same family or genus to minimize the influence of other factors and make a group of treatments for an individual index. The dry deposition velocities of PM₂.₅ were determined through application of an indirect method. The results revealed that the presence of leaf trichomes had a positive effect on PM₂.₅ dry deposition velocity, and a higher trichome density also led to a greater particle deposition velocity. Lower leaf aspect ratio, shorter petioles, and higher leaf fractal deviation were associated with greater PM₂.₅ dry deposition velocity. The control-variable approach allows to investigate the correlation between deposition velocity and a certain leaf characteristic independently while minimizing the effects of others. Thus, our study can clarify how a single leaf characteristic affects particle deposition velocity, and expound its potential mechanism more scientifically than the published studies. Our research points out the importance of controlling variables, and also provides ideas for future researches on related factors to be found. Meanwhile the results would help provide insight into design improvements or adaptive management for the alleviation of air pollution.

This paper presents the results of experimental research into the component composition of gases and ash residue from the combustion of a set of high-potential coal-water slurries containing petrochemicals. We have established that the use of slurry fuels provides a decrease in the CO₂, CH₄, SO₂, and NOₓ concentrations as compared to those from coal combustion. The content of carbon monoxide and hydrogen in the gas environment from the combustion of slurries is higher due to the intense water evaporation. It is shown that adding biomass allows a further 5–33% reduction in the emissions of nitrogen and sulfur oxides as compared to the coal-water slurry and the composition with added waste turbine oil and a 23–68% decrease as compared to coal (per unit mass of the fuel burnt). The mechanisms and stages of CO₂, SO₂, and NOₓ formation are explained with a view to controlling gaseous anthropogenic emissions and ash buildup. The values of the relative environmental performance indicator are calculated for slurry fuels. It is shown to exceed the same indicator of bituminous coal by 28–56%.

Vehicular emissions contribute significantly to air pollution, and the number of vehicles in use is continuing to rise. Policymakers thus need to formulate vehicular emission reduction policies to improve urban air-quality. This study used different vehicle control scenarios to predict the associated potential of mitigating carbon monoxide (CO), volatile organic compounds (VOCs), nitrogen oxide (NOₓ), particulate matter with an aerodynamic diameter less than 2.5 μm (PM₂.₅), and particulate matter with an aerodynamic diameter less than 10 μm (PM₁₀) in Xi’an China, in 2020 and 2025. One business-as-usual scenario and six control scenarios were established, and vehicular emission inventory was developed according to each scenario. The results revealed that eliminating high-emission vehicles and optimizing after-treatment devices would effectively reduce vehicular emissions. In addition, increasing the number of alternative fuel vehicles, restraining vehicle use, and restraining the growth of the vehicle population would all have certain effects on CO and VOCs emissions, but the effects would not be significant for NOx, PM₂.₅, and PM₁₀. The results also indicated that if all control measures were stringently applied together, emissions of CO, VOCs, NOₓ, PM₂.₅, and PM₁₀ would be reduced by 51.66%, 51.58%, 30.19%,71.12%, and 71.81% in 2020, and 53.55%, 51.44%, 19.09%, 54.88%, and 55.51%, in 2025, respectively.

This study used a regional climate-chemistry transport model, WRF-Chem v3.9.1, to evaluate the impact of South Asian biomass burning on black carbon (BC) over the Tibetan Plateau (TP) and its climatic effects for an entire year. The simulation, which was validated by comparing surface meteorological parameters and BC concentration against in-situ observations over South Asia and the TP, provided a perspective on the seasonal variations and regional spatial patterns of BC concentration. Using a sensitivity simulation where BC emissions from biomass burning were removed from South Asia, this study found South Asian biomass burning emissions contributed up to 90% of BC mass over the TP during the pre-monsoon season, specifically emissions from western India for the simulated year. The emissions led to reduced surface radiative forcing, causing the temperature to decrease accordingly. However, column cloud water was increased. This study suggested that the biomass burning emissions from South Asia have significant impact on atmospheric BC over the TP, especially during the pre-monsoon season. Therefore, reducing biomass burning emissions from South Asia is potentially important for alleviating the effects of BC on climatic and environmental conditions over the TP and surrounding regions.

Numerous pieces of evidence documented the importance of gut microbiota in regulating human health and evaluating the toxicity of environmental pollutants, which are closely related to the host health in various aspects, including nutrition, energy translation, metabolism, pathogen resistance, and immune function. A variety of environmental factors can disrupt gut microbiota and their functions, and inevitably cause immune diseases, obesity and diabetes. However, deciphering the inner mechanisms involved in the functional interaction of gut microbes with host health is still needed extensive investigations. This review focused on the essential roles of intestinal microbes in host-related diseases and highlighted the development and applications of germ-free (GF) animal models, mainly zebrafish. Moreover, the generation, immunity characters, advantages and challenges of GF zebrafish models were also summarized. Importantly, the composition and isolation of zebrafish gut bacteria for further application and toxicity evaluation of aquatic environmental pollutants were also discussed. In conclusion, GF zebrafish play irreplaceable roles in understanding the potential functions and responses of customized microbiota towards human and environmental health implications.

While the influence of climate change on the fate of persistent organic pollutants (POPs) is becoming a topic of global concern, it has yet to be demonstrated how POPs and their transformation products in soil respond to a changing climate at the local scale. We conducted a year-long field experiment with spiked soils to investigate the impact of climate on the dissipation of γ-hexachlorocyclohexane (γ-HCH) and p,p’-dichlorodiphenyltrichloroethane (p,p’-DDT) as well as the formation of their products. Four sites along an elevational gradient on the eastern Tibetan Plateau were selected to represent four scenarios ranging from a dry and cold to a warm and humid climate. Based on the measured concentrations of the two pesticides and their transformation products, we calculated the dissipation rates of γ-HCH and p,p’-DDT in soil using two biphasic kinetic models, and the formation rates of transformation products using a mid-point rectangular approximation method. The spiked γ-HCH generally showed the expected decrease in dissipation from soils with increasing altitudes, and therefore decreasing temperature and precipitation, whereas dissipation of p,p’-DDT was influenced more by photolysis and sequestration in soil. The formation rates of the primary products of γ-HCH (i.e. γ-HCH→PeCCH and γ-HCH→TeCCH) and p,p’-DDT (i.e. p,p’-DDT→p,p’-DDE and p,p’-DDT→p,p’-DDD) indicate that a warmer and wetter climate favors dechloroelimination (anaerobic biodegradation) over dehydrochlorination (aerobic biodegradation). The significantly longer dissipation half-lives of γ-HCH at the coldest site suggests that the fate of POPs in frozen regions (e.g. polar regions) needs more attention. Overall, the fate of more volatile chemicals (e.g. γ-HCH) might be more responsive to the climate change.

In recent decades China has experienced high-level PM₂.₅ pollution and then visible air quality improvement. To understand the air quality change from the perspective of aerosol optical depth (AOD), we adopted two statistical methods of Empirical Orthogonal Functions (EOF) and Non-negative Matrix Factorization (NMF) to AOD retrieved by MODIS over China and surrounding areas. Results showed that EOF and NMF identified the important factors influencing AOD over China from different angles: natural dusts controlled the seasonal variation with contribution of 42.4%, and anthropogenic emissions have larger contribution to AOD magnitude. To better observe the interannual variation of different sources, we removed seasonal cycles from original data and conducted EOF analysis on AOD monthly anomalies. Results showed that aerosols from anthropogenic sources had the greatest contribution (27%) to AOD anomaly variation and took an obvious downward trend, and natural dust was the second largest contributor with contribution of 17%. In the areas surrounding China, the eastward aerosol transport due to prevailing westerlies in spring significantly influenced the AOD variation over West Pacific with the largest contribution of 21%, whereas the aerosol transport from BTH region in winter had relative greater impact on the AOD magnitude. After removing seasonal cycles, biomass burning in South Asia became the most important influencing factor on AOD anomalies with contribution of 10%, as its interannual variability was largely affected by El Niño. Aerosol transport from BTH was the second largest contributor with contribution of 8% and showed a decreasing trend. This study showed that the downward trend of AOD over China since 2011 was dominated by aerosols from anthropogenic sources, which in a way confirmed the effectiveness of air pollution control policies.

Restoring woody vegetation to riparian zones helps to protect waterways from excessive sediment and nutrient inputs. However, the associated leaf litter can be a major source of dissolved organic matter (DOM) leached into surface waters. DOM can lead to the formation of disinfection by-products (DBPs) during drinking water treatment. This study investigated the DBPs formed during chlorination of DOM leached from leaf litter and assessed the potential toxicity of DBPs generated. We compared the leachate of two native Australian riparian trees, Casuarina cunninghamiana and Eucalyptus tereticornis, and a reservoir water source from a catchment dominated by Eucalyptus species. Leachates were diluted to dissolved organic carbon concentrations equivalent to the reservoir (~9 mg L⁻¹). E. tereticornis leachates produced more trihalomethanes (THMs), haloacetic acids (HAAs), and haloketones after chlorination, while C. cunninghamiana produced more chloral hydrate and haloacetonitriles. Leachate from both species produced less THMs and more HAAs per mole of carbon than reservoir water. This may be because reservoir water had more aromatic, humic characteristics while leaf leachates had relatively more protein-like components. Using in vitro bioassays to test the mixture effects of all chemicals, chlorinated E. tereticornis leachate induced oxidative stress in HepG2 liver cells and bacterial toxicity more frequently and at lower concentrations than C. cunninghamiana and reservoir water. Overall, this study has shown that the DOM leached from litter of these species has the potential to generate DBPs and each species has a unique DBP profile with differing bioassay responses. E. tereticornis may pose a relatively greater risk to drinking water than C. cunninghamiana as it showed greater toxicity in bioassays. This implies tree species should be considered when planning riparian zones to ensure the benefits of vegetation to waterways are not offset by unintended increased DBP production and associated toxicity following chlorination at downstream drinking water intakes.

East Asian oceans are possibly affected by a high nitrogen (N) burden because of the intense anthropogenic emissions in this region. Based on high-resolution regional chemical transport modeling with horizontal grid scales of 36 and 12 km, we investigated the N burden into East Asian oceans via atmospheric deposition in 2010. We found a high N burden of 2–9 kg N ha⁻¹ yr⁻¹ over the Yellow Sea, East China Sea (ECS), and Sea of Japan. Emissions over East Asia were dominated by ammonia (NH₃) over land and nitrogen oxides (NOₓ) over oceans, and N deposition was dominated by reduced N over most land and open ocean, whereas it was dominated by oxidized N over marginal seas and desert areas. The verified numerical modeling identified that the following processes were quantitatively important over East Asian oceans: the dry deposition of nitric acid (HNO₃), NH₃, and coarse-mode (aerodynamic diameter greater than 2.5 μm) NO₃⁻, and wet deposition of fine-mode (aerodynamic diameter less than 2.5 μm) NO₃⁻ and NH₄⁺. The relative importance of the dry deposition of coarse-mode NO₃⁻ was higher over open ocean. The estimated N deposition to the whole ECS was 390 Gg N yr⁻¹; this is comparable to the discharge from the Yangtze River to the ECS, indicating the significant contribution of atmospheric deposition. Based on the high-resolution modeling over the ECS, a tendency of high deposition in the western ECS and low deposition in the eastern ECS was found, and a variety of deposition processes were estimated. The dry deposition of coarse-mode NO₃⁻ and wet deposition of fine-mode NH₄⁺ were the main factors, and the wet deposition of fine-mode NO₃⁻ over the northeastern ECS and wet deposition of coarse-mode NO₃⁻ over the southeastern ECS were also found to be significant processes determining N deposition over the ECS.