[Spatial and Temporal Distribution Characteristics of Ozone Concentration and Health Benefit Assessment in the Beijing-Tianjin-Hebei Region from 2015 to 2020].

To evaluate the spatial and temporal distribution characteristics of ambient ozone (O3) in the Beijing-Tianjin-Hebei (BTH) Region, the land use regression (LUR) model and random forest (RF) model were used to simulate the ambient O3 concentration from 2015 to 2020. Meanwhile, all-cause, cardiovascular, and respiratory mortalities as well as economic losses attributed to O3 were also estimated. The results showed that upward trends with fluctuation were observed for ambient O3 concentration, mortalities, and economic losses attributable to O3 exposure in the BTH Region from 2015 to 2020. The areas with high O3 concentration and great changes were concentrated in the central and southwestern regions, whereas the concentration in the northern region was low, and the change degree was small. The spatial distribution of the mortalities was also consistent with the spatial distribution of O3 concentration. From 2015 to 2020, the economic losses regarding all-cause mortality and cardiovascular mortality increased in 13 cities of the BTH Region, whereas the economic losses of respiratory mortality decreased in 4 cities in the BTH Region. The results indicated that the priority areas for O3 control were not uniform. Specifically, Beijing, Tianjin, Hengshui, and Xingtai were vital areas for O3 pollution control in the BTH Region. Differentiated control measures should be adopted based on the characteristics of these target areas to decline O3 concentration and reduce health impacts and economic losses associated with O3 exposure.

Assessment of toxic mechanisms and mode of action to three different levels of species for 14 antibiotics based on interspecies correlation, excess toxicity, and QSAR.

Antibiotics have received much attention owing to their ecotoxicity toward nontarget aquatic creatures. However, the mode of action (MOA) of toxicity against nontarget organisms is unclear in some aquatic organisms. In this study, the comparison of toxicities through interspecies correlations, excess toxicity calculated from toxicity ratio, and quantitative structure-activity relationship (QSAR) was carried out to investigate the MOAs for 14 antibiotics among Daphnia magna, Vibrio fischeri, and Pseudokirchneriella subcapitata. The results showed that interspecies toxicity correlations were very poor between any two of the three species for the 14 antibiotics. The toxicity ratio revealed that most antibiotics exhibited excess toxicity to algae and Daphnia magna but not to V. fischeri, demonstrating that some antibiotics share the same MOA, but some antibiotics share different MOAs among the three different levels of species. P. subcapitata was the most sensitive species, and V. fischeri was the least sensitive species. This is because of the differences in the biouptake and interactions of antibiotics with the target receptors between the three different trophic levels of the species. Molecular docking simulations suggested that the toxicity of antibiotics depends highly on their interactions with target receptors through hydrogen bonds, electrostatic or polar interactions, π bond interactions, and van der Waals forces. QSAR models demonstrated that hydrogen bonding and electrophilicity/nucleophilicity play key roles in the interaction of antibiotics with different receptors in the three species. The toxic mechanisms of antibiotics are attributed to the interactions between electrophilic antibiotics and biological nucleophiles, and hydrogen-bond interactions. These results are valuable for understanding the toxic mechanisms and MOA of the three different levels of species.

[Distribution and Potential Ecological Risk Assessment of Heavy Metals in Sediments of Lake Qinghai].

Lake Qinghai is the largest closed saltwater lake in China. In recent years, because of the rapid development of industry, agriculture, and tourism, the lake has been increasingly affected by human activities, which has attracted the attention of many scholars. In order to understand the distribution of heavy metals in the surface sediments of Lake Qinghai, the contents of Zn, Cu, Pb, Co, Ni, As, Cd, and Cr were investigated, the metal fractions were extracted, and the sources, as well as potential ecological risks, were analyzed. The results showed that:① the ω(As) (13.21 mg·kg-1) and ω(Cd) (0.21 mg·kg-1) in the surface sediments of Lake Qinghai were 1.13 and 1.53 times higher than the environmental background values, respectively, and the other heavy metal contents were all lower than the environmental background values. There were similar spatial distribution characteristics of analyzed metals except for As, with higher values measured in the northwestern area of the lake and the 151 Terminal. ② Except for Cd, the analyzed heavy metals mainly existed in the form of the residual state; by contrast, Cd mainly existed in the form of the bioavailable state, which has high potential toxicity to aquatic organisms. ③ Combined with the results of the correlation and principal component analysis, the metals including Zn, Cu, Pb, Co, Ni, Cd, and Cr were thought to mainly come from the natural environment, whereas the source of As was related to human activities, such as agricultural production. ④ According to potential risk analyses, the average of the metal potential ecological risk factors was 76.57, which indicated a slight ecological hazard level. However, it should be noted that the potential ecological hazard level and release risk of Cd at each site were higher than those of the other metals, especially in the regions nearing the estuary of Heima River, Lake Gahai, and the sand island, which showed higher levels of enrichment and potential release risk. Therefore, further attention should be paid to the potential impacts of Cd in sediments of these regions on the water environment and ecosystem.