Microplastics (MPs) are emerging as global environmental pollutants, significantly influencing the safety of city rivers. This study investigated six sampling sites in the Qinhuai River of Nanjing, which explored the distribution and characteristics of MPs and the microbial structure in 2023. The studied river contained various levels of MPs with average concentrations of 667.68 items/L, whose abundance firstly decreased midstream and then increased downstream. The MPs abundance upstream was higher in surface water column, microplastics midstream and downstream accumulated more in deep water column. Black and blue are prevalent in the color distribution, while the polymers of PC, PP and PS changed with increasing depth, with a proportion of 74 % ∼ 97 % in the dominant shapes of granules. Furthermore, the water with higher MPs may stimulate the growth of MPs-related bacteria in sediments, including the genus of Pseudoxanthomonas and Dechloromonas. Our research will provide constructive support for enhancing urban river management strategies.

Organochlorine compounds (OCs) such as chlorobenzenes (CB) are persistent organic pollutants that are ubiquitous in soils at organochlorine pesticides (OCP) production sites. Long-term contamination with OCs might alter the soil microbial structure and further affect soil functions. However, the effects of OCs regarding the shaping of microbial community structures in the soils of OCs-contaminated sites remain obscure, especially in the vertical soil profile where pollutants are highly concealed. Hence this paper explored the status and causes of OCs pollution (CB, hexachlorocyclohexane (HCH), and dichlorodiphenyltrichloroethane (DDT)) in an obsolete site, and its combined effects with soil properties (pH, available phosphorus (AP), dissolved organic carbon (DOC), etc) on microbial community structure. The mean total concentration of OCs in the subsoils was up to 996 times higher than that in the topsoils, with CB constituting over 90% of OCs in the subsoil. Historical causes, anthropogenic effects, soil texture, and the nature of OCs contributed to the differences in the spatial distribution of OCs. Redundancy analysis revealed that both the soil properties and OCs were important factors in shaping microbial composition and diversity. Variation partitioning analysis further indicated that soil properties had a greater impact on microbial community structure than OCs. Significant differences in microbial composition between topsoils and subsoils were observed through linear discriminant analysis effect size (LEfSe) analysis, primarily driven by different pollutant conditions. Additionally, co-occurrence network analysis indicated that heavily contaminated subsoils exhibited closer and more intricate bacterial community interactions compared to lightly contaminated topsoils. This work reveals the impact of environmental factors in co-shaping the structure of soil microbial communities. These findings advance our understanding of the intricate interplay among organochlorine pollutants, soil properties, and microbial communities, and provides valuable insights into devising effective management strategies in OCs-contaminated soils.

Soil microplastic pollution is ubiquitous, but the vertical distribution characteristics of microplastics in different land use types are unclear. In this study, the microplastic abundance, particle size, shape, color, and polymer type in 0-20 cm, 20-40 cm, and 40-60 cm soil layers of seven land use types (woodland, grassland, maize, wheat, cotton, polytunnel, and greenhouse) were systematically investigated in Shouguang City, a typical agricultural city in China. The results showed that the average microplastic abundance from top to deep for the three soil layers of Shouguang City were 1948.1 ± 992.5, 1349.4 ± 654, and 670.1 ± 341.6 items kg-1. In the top soil layer (0-20 cm), the abundance of microplastics in facility soils was significantly higher than in other land use types. In agricultural soils, microplastics were predominantly small size (<0.5 mm), films and fragments, PE and PP. The average microplastic abundance in deep soils (40-60 cm) of the seven land use types was 349.1 ± 62.8 (woodland), 284.9 ± 113.9 (grassland), 657.1 ± 127.1 (maize), 537.8 ± 137.4 (wheat), 851.4 ± 204.2 (cotton), 878.5 ± 295.7 (polytunnel), 1132.2 ± 304.5 (greenhouse) items kg-1, respectively, accounting for 11 % to 19 % in all three soil layers. The percentage of small size and pellet microplastics increased in deep soils (40-60 cm). Correlation analysis showed that soil environmental factors (pH, EC, total phosphorus, total nitrogen, and organic carbon) influenced to different extents the distribution, fragmentation, and transport of microplastics. The results of this study contribute to a better understanding of contamination and vertical distribution of soil microplastics in agricultural and non-agricultural soils, as well as provide important data for the development of preventive and management policies.

Although terrestrial isopods (Oniscidea) are primarily soil- and surface-dwelling invertebrates, they can also be found on tree trunks and walls. This study evaluated distribution patterns of terrestrial isopods on a brick wall during the first hours of night in autumn. Four species of terrestrial isopods were recorded with Armadillidiumversicolor being the dominant one. Terrestrial isopods were distributed from ground level up to a height of 2 m, but preferred a 70-80 cm height band. The highest number of active individuals was observed 3 h after astronomical dusk. Potential predators of terrestrial isopods were abundant during the same time and at the same height.

In late September 2019, the longest and most extensive ozone (O3) pollution process occurred at Pearl River Delta. Base on the observational data, surface-level O3, vertical distribution characteristics boundary layer O3 as well as its effect on surface-level O3 are thoroughly analyzed. The O3 lidar results showed similar vertical O3 profiles both in pollution episodes and clean periods, from which a high O3 concentration layer between 300 and 500 m and a sub-high O3 concentration layer between 1300 and 1700 m (near the top of the mixing layer) can be found. Besides, the downward O3 transport paths from the high/sub-high O3 concentration layers could be observed along with the boundary layer evolution: At nighttime, large amounts of O3 were effectively stored into the residual layer (RL). Due to the upward development of Mixing layer (ML) in early morning, atmospheric vertical mixing carried the O3 inside the RL down to the surface, which led to a rapid increase in the surface-level O3. The sub-high O3 layer began the downward mixing at noon, and became well-mixed after the boundary layer was fully developed in the afternoon, by which the near surface O3 pollution deteriorated again. Further analysis of the heavy O3 pollution episodes show that, the high O3 concentration inside the RL contributed 54% ± 6% of the surface-level O3 at 9:00 LT and the average contribution of O3 in the sub-high concentration layer to the surface-level O3 at 14:00 LT was 26% ± 9%. Based on the quantitative analysis of the observational data, this paper focus to reveal the importance of the contribution of O3 inside the RL and near the top of the ML to the surface O3.

To determine the reasons for the variation in the vertical distribution of nitrogen in sediment interstitial waters between different stratified reservoirs, the characteristics of overlying water-interstitial water in Xiangxi Bay, Yangtze River mainstream, and Xiaowan Reservoir were monitored. The vertical distribution of nitrogen in sediment interstitial waters in these different stratified waters were then analyzed, and the reasons for the variation in this distribution were assessed. The results showed:① the ρ(TN) in the sediment interstitial waters of the Yangtze River mainstream and Xiangxi Bay gradually increased with depth, while that of Xiaowan Reservoir reached its maximum at 12 cm and the bottom layer presented a \"C\" distribution. The ρ(NH4+) in the sediment interstitial waters of the Yangtze River mainstream and Xiangxi Bay exhibited an increasing trend with depth, while that of Xiaowan Reservoir was slightly higher in the bottom layer than in the surface layer, although the change with depth was not significant. Overall, the ρ(NH4+) in the sediment interstitial waters of the Yangtze River mainstream and Xiangxi Bay was higher than that of Xiaowan Reservoir, and the concentration ranges were as follows:0.512-8.289 mg·L-1, 0.968-9.307 mg·L-1, and 0.950-1.450 mg·L-1. The vertical distribution of the ρ(NO3-) in the sediment interstitial waters of all three waterbodies were opposite to that of ρ(NH4+). Moreover, the ρ(NO3-) in the sediment interstitial waters of Xiangxi Bay and the Yangtze River mainstream was higher than that of Xiaowan Reservoir. The concentration ranges were as follows:0.143-0.674 mg·L-1, 0.107-0.647 mg·L-1, and 0.050-0.051 mg·L-1. ② There were also significant differences in the vertical distribution of physical and chemical indices in the three water bodies. There was no significant change in the vertical distribution of the water temperature in the Yangtze River mainstream and the N2 value was <5×10-5 s-2; hence, the water was well mixed, and the vertical range of the dissolved oxygen content was 6.180-6.318 mg·L-1. The water temperature in the upper and middle reaches of Xiangxi Bay decreased vertically, while the water temperature in the lower reach presented a ladder-like distribution and the N2 values were all>5×10-5 s-2; thus, the water was in a stable stratified state and the dissolved oxygen content presented a \"C\" distribution. There was obvious stratification at the depths of 5-15 m and 54-70 m in Xiaowan Reservoir. The dissolved oxygen content decreased significantly at higher water temperature gradients, and there was no significant change along the water depth below 80 m. ③ The main reasons for the variation in the vertical distribution of nitrogen in the sediment interstitial waters of the three waterbodies were the differences in the overlying water hydrodynamics, dissolved oxygen distribution, and sediment environment. The ρ(NH4+) and ρ(NO3-) were higher in Xiangxi Bay, which may have increased the denitrification rate and subsequently have helped to remove nitrogen and reduce the nitrogen load in these waters.

Totally 126 samples of windowsill dust were collected from different floors along elevated road in Changzhou. The concentrations of Cu, Zn, Pb, Cd, Ni and Cr were determined, and the vertical distribution and chemical speciation were analyzed. The enrichment factor, bioaccessiblity, potential ecological risk and health risk were evaluated. The results showed that the average contents of Cu, Zn, Pb, Cd, Ni and Cu were 181.95, 709.99, 211.24, 2.76, 101.59 and 257.55 mg·kg-1 respectively, which were all higher than the background value. The enrichment factor of Cd was 33.05, with enrichment degree of strongly enriched. The enrichment degrees of Cu, Pb and Zn were all significantly enriched. These four heavy metals may come not only from transportation source, but also from natural source and regional industrial polluted gas. The enrichment factors of Ni and Cr were low, which may result from natural source. With the elevation of house height, the concentration of Cd increased, the concentrations of Pb and Zn increased first and then decreased, while Cu showed no significant differences. Zn, Cd, Cu and Pb mainly existed in the active form, while Ni and Cr mainly existed in the residual form. The bioaccessiblity of Zn and Cd was high, while that of other heavy metals was low. The modified potential ecology risk evaluation results showed that the risk of Cd was extremely high, and contributed mainly to the potential risk index of multi-element. The Cd from the windowsill of high height showed higher potential ecological risk. The carcinogenic risk of Cr to children was higher than the threshold value, while the carcinogenic risk and non-carcinogenic risk of other metals to children and adults were all below the safety thresholds.

Vertical profiles of environmental radionuclides (210Pb, 137Cs, 238U, 232Th, 226Ra and 40K) in a sediment core (Y1) of the Yellow River Estuary wetland were investigated to assess whether environmental evolutions in the coastal wetland could be recorded by the distributions of radionuclides. Based on 210Pb and 137Cs dating, the average sedimentation rate of core Y1 was estimated to be 1.0 cm y-1. Vertical distributions of natural radionuclides (238U, 232Th, 226Ra and 40K) changed dramatically, reflecting great changes in sediment input. Concentrations of 238U, 232Th, 226Ra and 40K all had significant positive relationships with organic matter and clay content, but their distributions were determined by different factors. Factor analysis showed that 238U was determined by the river sediment input while 226Ra was mainly affected by the seawater erosion. Environmental changes such as river channel migrations and sediment discharge variations could always cause changes in the concentrations of radionuclides. High concentrations of 238U and 226Ra were consistent with high accretion rate. Frequent seawater intrusion decreased the concentration of 226Ra significantly. The value of 238U/226Ra tended to be higher when the sedimentation rate was low and tide intrusion was frequent. In summary, environmental evolutions in the estuary coastal wetland could be recorded by the vertical profiles of natural radionuclides.