Emissions of major reactive nitrogen compounds, including nitric oxide (NO), nitrogen dioxide (NO₂) and ammonia (NH₃), from heavy-duty diesel vehicles (HDDVs) place substantial pressure on air quality for many large cities in China. To control nitrogen oxide (NOX) emissions from HDDVs, selective catalytic reduction (SCR) systems have been widely used since the China IV standards. To investigate the impacts of aftertreatment technologies and driving conditions on real-world emissions of reactive nitrogen compounds, a portable emissions measurement system was employed to test eighteen heavy-duty diesel trucks in China. The results showed that the China IV and China V HDDVs with appropriate SCR functionality could reduce NOX emissions by 36% and 53%, respectively, compared to the China III results, although their real-world emissions were still higher than the corresponding emission limits for regulatory engine tests. For these HDDVs, five samples were tested with NH₃ emissions, ranging from 1.67 ppm to 51.49 ppm. The NH₃ emission rates tended to significantly increase under high-speed driving conditions. The results indicate that the current SCR technology may have certain risks in exceeding the future China VI NH₃ limit. However, five China IV/V HDDVs were found to have SCR temperature sensors that were intentionally tampered with, resulting in comparable or even higher NOX emissions and zero NH₃ emissions. Increased NO₂ emissions due to the adoption of diesel oxidation catalysts and diesel particulate filters were also found from our experiments. This study highlights the importance of enhancing in-use compliance requirements and eliminating aftertreatment tampering for China IV and China V HDDVs.

Anthropogenic activities have significantly changed the stoichiometry and concentrations of nutrients in coastal waters. Silicon (Si) has become a potential limiting nutrient due to disproportionate nitrogen, phosphorus, and silicate inputs into these areas. The disrupted nutrient ratios can cause changes to metal sensitivity and accumulation in marine diatoms, an important group of eukaryotic phytoplankton that requires silicon for growth. In this study, we examined the effects of Si availability on the metal sensitivity in the diatom P. tricornutum. We found that Si starvation dramatically compromised its cadmium, copper, and lead tolerances. Interestingly, multiple lines of evidence indicated that Si-enriched cells had higher metal adsorption and influx rates than Si-starved cells. Yet Si-enriched cells also had a greater ability to respond to and counteract metal toxicity via elevated expression of membrane and vacuolar metal transporters and greater antioxidant activities which scavenge reactive oxygen species created by metal stress.

Summertime ozone (O₃) concentrations over China continue to increase although the governmental Clear Air Actions have been carried out since 2013. The worst O₃ pollution is confronted over North China Plain. Ozone polluted days (with observed regionally-averaged maximum daily 8-h average (MDA8) O₃ concentrations exceeding 80 ppbv) in May–July in North China increased from 35 days in year 2014 to 56 days in year 2018, and persistent O₃ pollution episodes that lasted for 5 days or longer (OPEs5) contributed 14.3% and 66.1% to those O₃ polluted days in 2014 and 2018, respectively. Model simulations suggest that O₃ transport from central eastern China (including Shandong, Henan, Jiangsu and Anhui Provinces) contributes 36% of the enhanced O₃ concentrations in North China during OPEs5 relative to the seasonal mean. We find that emission control of volatile organic compounds in central eastern China is most effective to alleviate intensity of OPEs5 in North China.

The present study proposes a maize sprouts hydroponic growth model to evaluate the As, Cd, Cr and Pb translocation from multinutrient fertilizer and to do speciation of As and Cr in this fertilizer and As in parts of plant in order to predict their phytoavailability. X-ray absorption near edge structure (XANES) was employed to speciate As and Cr directly on fertilizer solid sample. Arsenate (Asⱽ) and a solid solution of FeCrO₃ were the major species identified in the samples. The sprouts were hydroponically cultivated in water, fertilizer slurry and fertilizer extract media. Concentrations of As, Cd and Pb measured on leaves of maize sprouts ranged from 0.061 to 0.31 mg kg⁻¹, whereas Cr was not translocated to the aerial parts of sprouts. High performance liquid chromatographic with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) analysis was used to determine As speciation in maize sprouts, as well as in the fertilizer extracts and slurries. Arsenate was the only species identified in the initial fertilizer extract and this information is in agreement with the XANES results. However, the reduction of arsenate to arsenite was observed in extracts and slurries collected after sprout growth, probably due to the action of exudates secreted by plant roots. Arsenite was the predominant species identified in sprouts, the high phosphate concentration in the medium may have contributed to reduce arsenate phytoavailability.

Microbiota in urban green spaces underpin ecosystem services that are essential to environmental health and human wellbeing. However, the factors shaping the microbial communities in urban green spaces, especially those associated with turf grass phyllosphere, remain poorly understood. The lack of this knowledge greatly limits our ability to assess ecological, social and recreational benefits of urban green spaces in the context of global urbanization. In this study, we used amplicon sequencing to characterize soil and grass phyllosphere bacterial communities in 40 urban green spaces and three minimally disturbed national parks in Victoria, Australia. The results indicated that urbanization might have shown different impacts on soil and grass phyllosphere microbial communities. The bacterial diversity in soil but not in grass phyllosphere was significantly higher in urban green spaces than in national parks. Principal coordinate analysis revealed significant differences in the overall patterns of bacterial community composition between urban green spaces and national parks for both soil and grass phyllosphere. Industrial development, as represented by the number of industries in the region, was identified as a key driver shaping the bacterial community profiles in urban green spaces. Variation partitioning analysis suggested that industrial factors together with their interaction with other factors explained 20% and 28% of the variances in soil and grass phyllosphere bacterial communities, respectively. The findings highlight the importance of industrial development in driving the spatial patterns of urban microbiomes, and have important implication for the management of microbiomes in urban green spaces.

Common solvents are frequently used as carriers to dissolve chemicals with a hydrophobic property that is extensively applied in the industrial and biomedical fields. In this study, we aimed to systematically study the sub-chronic effect of ten common solvents at low concentration exposure in adult zebrafish and perform neurobehavioral assessments for mechanistic exploration. After exposed to ten common solvents, including methanol, ethanol (EtOH), dimethyl sulfoxide (DMSO), isopropanol, acetone, polyethylene glycol-400 (PEG-400), glycerol, butanol, pentane, and tetrahydrofuran for continuous 10 day at 0.1% concentration level, adult zebrafish were subjected to perform a serial of behavioral tests, such as novel tank, mirror biting, predator avoidance, social interaction and shoaling. Later, 20 behavioral endpoints obtained from these five tests were transformed into a scoring matrix. Principal component analysis (PCA) and hierarchy clustering were performed to evaluate and compare the zebrafish behavior profiling. By using this phenomic approach, we were able to systematically evaluate the toxicity of the common solvents in zebrafish at a neurobehavioral level for the first time and found each common solvent-induced unique behavioral alteration to produce fingerprint-like patterns in hierarchy clustering and heatmap analysis. Among all tested common solvents, acetone and PEG-400 displayed better biocompatibility and less toxicity since they triggered less behavioral and biochemical alterations while methanol and DMSO caused severe behavior alterations in zebrafish after chronic exposure of these solvents. We conclude the behavioral phenomic approach conducted in this study providing a powerful tool to a systematical exploration of the common solvent toxicity at the whole organism level.

Occupational exposure to hexavalent chromium (Cr(VI)) can cause cytotoxicity and carcinogenicity. In this study, we established a liver injury model in rats via intraperitoneal injection of potassium dichromate (0, 2, 4, and 6 mg/kg body weight) for 35 d to investigate the mechanism of Cr(VI)-induced liver injury. We found that Cr(VI) induced hepatic histopathological lesions, oxidative stress, and apoptosis and reduced the expression of mitochondrial-related regulatory factors such as adenosine 5′-monophosphate-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) in a dose-dependent manner. Furthermore, Cr(VI) promoted mitochondrial division and inhibited fusion, leading to increased expression of caspase-3 and production of mitochondrial reactive oxygen species. Our study demonstrates that long-term exposure to Cr(VI) induces mitochondrial dynamics disorder by inhibiting AMPK/PGC-1α signaling pathway in rat liver.

The investigation of microplastics (MPs) in freshwater has received increased attention within the last decade. To date, sampling is mainly conducted at the surface of both rivers and lakes and only a few studies assessed the vertical distribution of MPs in the water column of freshwater bodies. To contribute to the understanding of MP pollution in the water column of freshwater lakes, this study evaluated the vertical profile of MPs in Lake Tollense considering particles between 63 and 5000 μm in size. Sampling was conducted on three occasions at three depths (surface, 7 m and 10 m) along a transect including eight sampling stations. The retrieved samples were digested with hydrogen peroxide and sodium hypochlorite and investigated via Nile Red staining and fluorescence microscopy. Subsequently, a sub-sample of stained particles was verified by μRaman-spectroscopy. The vertical distribution of MPs in Lake Tollense differed considerably between particle shapes (irregular particles (IPs) and fibers). Fibers did not show a noticeable pattern with depth and ranged between 22 fibers m⁻³ at 0 m to 19 fibers m⁻³ at 10 m. In contrast, IPs were distinctly less abundant in sub-surface samples with concentrations between 50 IPs m⁻³ at 0 m to 29 IPs m⁻³ at 10 m. Concerning IPs, buoyant polymers (mainly PE and PP) and concerning fibers PET and PP dominated the polymeric composition. Besides particle inherent properties, wind-induced mixing is likely affecting the intensity of vertical concentration gradients. This study highlights the need for depth-integrated sampling approaches in order to achieve representative data without over- or underestimating the overall abundances.