Cd accumulation in paddy soils and its subsequent transfer to the food chain are widespread environmental issues, which has been extensively investigated in China. However, most studies focused on regional scales and these results may not be applicable to present the Cd contamination status in soil-rice ecosystems at a national scale. Therefore, based on collected data from China’s rice cultivation dominated regions, this study provides the Cd pollution level of paddy soils and rice grains in China. Results indicates that the Yangtze River basin, especially Hunan, required more attention due to the elevated Cd concentrations in soil-rice ecosystems. Moreover, this review summarizes the significant natural and anthropogenic sources, transport and accumulation mechanism as well as the influencing factors of Cd in soil-rice ecosystems. The wide occurrence of Cd contamination in paddy soils derived primarily from mining activities, intensive application of phosphates fertilizers and e-waste. Physicochemical characteristics of soil, soil microorganisms, temperature as well as the physiological features of rice plants all contribute to Cd accumulation in rice grains, which can be controlled to mitigate Cd accumulation in rice grains. This review will provide a scientific reference for Cd pollution control and management with respect to paddy field ecosystems in China and other countries.

Bats are poorly understood as a reservoir of multidrug-resistant strains; therefore, the aim of this study was to determine molecular characterization of multidrug-resistant Enterococcus strains isolated from bat species from Poland. A multi-stage analysis based on targeted isolation of drug-resistant strains (selective media with tetracycline, chloramphenicol, gentamicin, streptomycin, and vancomycin), determination of the phenotypic profile of drug-susceptibility using the disc diffusion method, and amplification of DNA fragments surrounding rare restriction sites (ADSRRS-fingerprinting) was used for the isolation and differentiation of strains. The applied strategy finally allowed identification of E. faecalis resistant to at least one antimicrobial in 47.2% of the single-animal group and in 46.9% of the pooled samples of bat’s guano. Out of the 36 distinct isolates, 69% met the criteria of multi-drug resistance, with a dominant combination of resistance to tetracycline, erythromycin, and rifampicin. Simultaneously, 41.6% of the strains were high-level aminoglycoside resistant (HLAR). In most strains, phenotypic resistance was reflected in the presence of at least one gene encoding resistance to a given drug. Moreover, our research results show that some genes were detected simultaneously in the same strain statistically significantly more frequently. This may confirm that the spread of some genes (tetM and ermB or aph (3′)-IIIa as well as gelE and aac (6′)-Ie-aph (2″)-Ia or ant (6)-Ia) is associated with their common occurrence on the same mobile genetic element.To our knowledge, this is the first analysis of multidrug-resistance among E. faecalis isolated from bats. Our research demonstrates that the One Health concept is not associated exclusively with food-producing animals and humans, but other species of wildlife animals should be covered by monitoring programs as well.We confirmed for the first time that bats are an important reservoir of multi-resistant E. faecalis strains and could have a great impact on environmental resistance.

Due to rapid urbanization in China, lead (Pb) continues to accumulate in urban topsoil, resulting in soil degradation and increased public exposure. Mapping Pb concentrations in urban topsoil is therefore vital for the evaluation and control of this exposure risk. This study developed spatial models to map Pb concentrations in urban topsoil using proximal and remote sensing data. Proximal sensing reflectance spectra (350–2500 nm) of soils were pre-processed and used to calculate the principal components as landscape factors to represent the soil properties. Other landscape factors, including vegetation and land-use factors, were extracted from time-sequential Landsat images. Two hybrid statistical approaches, regression kriging (RK) and geographically weighted regression (GWR), were adopted to establish prediction models using the landscape factors. The results indicated that the use of landscape factors derived from combined remote and proximal sensing data improved the prediction of Pb concentrations compared with useing these data individually. GWR obtained better results than RK for predicting soil Pb concentration. Thus, joint proximal and remote sensing provides timely, easily accessible, and suitable data for extracting landscape factors.

Co-selection of antibiotic resistance genes (ARGs) by heavy metals might facilitate the spread of ARGs in the environments. Cadmium contamination is ubiquitous, while, it remains unknown the extent to which cadmium (Cd²⁺) impact plasmid-mediated transfer of ARGs in aquatic bacterial communities. In the present study, we found that Cd²⁺ amendment at sub-inhibitory concentration significantly increased conjugation frequency of RP4 plasmid from Pseudomonas putida KT2442 to a fresh water microbial community by liquid mating method. Cd²⁺ treatment (1–100 mg/L) significantly increased the cell membrane permeability and antioxidant activities of conjugation mixtures. Amendments of 10 and 100 mg/L Cd²⁺ significantly enhanced the mRNA expression levels of mating pair formation gene (trbBp) and the DNA transfer and replication gene (trfAp) due to the repression of regulatory genes (korA, korB and trbA). Phylogenetic analysis of transconjugants indicated that Proteobacteria was the dominant recipients and high concentration of Cd²⁺ treatment resulted in expanded recipient taxa. This study suggested that sub-inhibitory Cd²⁺ contamination would facilitate plasmid conjugation and contributed to the maintenance and spread of plasmid associated ARGs, and highlighted the urgent need for effective remediation of Cd²⁺ in aquatic environments.

Quantitative identification of the main sources of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in soils around multiple types of key areas is of great significance for blocking pollution sources. However, there is a lack of more comprehensive relevant research. In this study, Beijing was taken as the research area and four main sources were identified using the positive matrix factorization (PMF) method. The concentration of Pb, PAHs, Cr, and Hg in soils was significantly affected by the presence of landuse type, road traffic, natural factor, and industrial production, respectively, and the farmland, distance to main road, Proterozoic Changcheng-Jixian parent material and cinnamon soil type, and the gross industrial production make greater contributions to these four factors respectively than other variables. Moreover, the uncertainty of the PMF indicates that this four-factor PMF solution is stable and appropriate. These results provide support for the comprehensive control of soil environmental risks.

A three-dimensional hydrodynamic-antibiotic model is developed to investigate the transport and dilution of sulfamethoxazole (SMX) in the Upper Gulf of Thailand (UGoT). The simulation produced a spatially averaged annual mean SMX concentration of 0.58 μgm−3, which varied slightly between seasons assuming a temporally constant river SMX loading observed in August. In contrast, the horizontal distribution of SMX concentrations strongly varied with season because of the changing residual currents. In addition, SMX is diluted to concentrations lower than 10% of those in river waters a short distance offshore of the estuaries. To better understand this behavior, we examined the relationship between salinity and SMX concentrations in the UGoT. The annual budget demonstrates that 98% of SMX in the UGoT is removed by natural decomposition. As the concentrations of fluvial pollutants in the UGoT depend on their river loading and decomposition rates, functions were derived to predict pollutant concentrations and flushing times based on the river input flux and half-life.

Despite the ubiquitousness of microplastics, knowledge on the exposure of freshwater fish to microplastics is still limited. Moreover, no standard methods are available for analyzing microplastics, and the quality of methods used for the quantification of ingested microplastics in fish should be improved. In this study, we studied microplastic ingestion of common wild freshwater fish species, perch (Perca fluviatilis) and vendace (Coregonus albula). Further, our aim was to develop and validate imaging Fourier-transform infrared spectroscopic method for the quantification of ingested microplastics. For this purpose, enzymatically digested samples were measured with focal plane array (FPA) based infrared microscope. Data was analyzed with siMPle software, which provides counts, mass estimations, sizes, and materials for the measured particles. Method validation was conducted with ten procedural blanks and recovery tests, resulting in 75% and 77% recovery rates for pretreatment and infrared imaging, respectively. Pretreatment caused contamination principally by small <100 μm microplastics. The results showed that 17% of perch and 25% of vendace had ingested plastic. Most of the fish contained little or no plastics, while some individuals contained high numbers of small particles or alternatively few large particles. Perch from one sampling site out of five had ingested microplastics, but vendace from all sampling sites had ingested microplastics. The microplastics found from fish were mostly small: 81% had particle size between 20 and 100 μm, and most of them were polyethylene, polypropylene, and polyethylene terephthalate. In conclusion, the implemented method revealed low numbers of ingested microplastics on average but needs further development for routine monitoring of small microplastics.

Despite representing an extremely relevant portion (20–40%) of worldwide coastal litter, cigarette butts are still an underestimate environmental issue of limited scientific interest. Public authorities of different countries promote active removal of cigarette butts, but the issue remains problematic in terms of aesthetic, environmental and health-related impacts. There are few studies on the environmental side-effects of smoked cigarette butt litter despite being a worldwide issue. In this work, two ecotoxicological bioassay batteries were adopted to evaluate the environmental consequences of cigarette butt water-soluble ingredient release in both marine water and freshwater. Marine assays were generally more affected compared to freshwater. Interesting outcomes were observed with crustacean tests, showing a lower effect of smoked cigarette butt leachate when tested at maximum concentration. This finding were supported by heartbeat measures of Daphnia magna, which were accelerated at 100% of smoked cigarette butt leachate.

High ammonia (NH₃) emissions from fertilized soil in China have led to various concerns regarding environmental safety and public health. In response to China's blue skies protection campaign, effective NH₃ reduction measures need to consider both mitigation efficiency and food security. In this context, we conducted a meta-analysis (including 2980 observations from 447 studies) to select effective measures based on absolute (AV) and yield-scaled (YSAV) NH₃ volatilization reduction potential, with the aim of establishing a comprehensive NH₃ mitigation framework covering various crop production sectors, and offering a range of potential solutions. The results showed that manipulating crop density, using an intermittent irrigation regime for paddy field rice, applying N as split applications or partially substituting inorganic fertilizer N with organic N sources could achieve reductions in AV and YSAV reduction of 10–20 %; adopting drip irrigation regimes, adding water surface barrier films to paddy fields, or using double inhibitor (urease and nitrification), slow-release or biofertilizers could achieve 20–40 % mitigation; plastic film mulching, applying fertilizer by irrigation or using controlled-release fertilizers could yield 40–60 % reduction; use of a urease inhibitor, fully substituting fertilizer N with organic N, or applying fertilizer by deep placement could decrease AV and YSAV by over 60 %. In addition, use of soil amendments, applying suitable inorganic N sources, or adopting crop rotation, intercropping or a rice-fish production model all had significant benefits to control AV. The adoption of any particular strategy should consider local accessibility and affordability, direct intervention by local/government authorities and demonstration to encourage the uptake of technologies and practices, particularly in NH₃ pollution hotspot areas. Together, this could ensure food security and environmental sustainability.

Particulate pollution is closely related to public health. PM₁ (particles with an aerodynamic size not larger than 1 μm) is much more harmful than particles with larger sizes because it goes deeper into the body and hence arouses social concern. However, the sparse and unevenly distributed ground-based observations limit the understanding of spatio-temporal distributions of PM₁ in China. In this study, hourly PM₁ concentrations in central and eastern China were retrieved based on a random forest model using hourly aerosol optical depth (AOD) from Himawari-8, meteorological and geographic information as inputs. Here the spatiotemporal autocorrelation of PM₁ was also considered in the model. Experimental results indicate that although the performance of the proposed model shows diurnal, seasonal and spatial variations, it is relatively better than others, with a determination coefficient (R²) of 0.83 calculated based on the 10-fold cross validation method. Geographical map implies that PM₁ pollution level in Beijing-Tianjin-Hebei is much higher than in other regions, with the mean value of ∼55 μg/m³. Based on the exposure analysis, we found about 75% of the population lives in an environment with PM₁ higher than 35 μg/m³ in the whole study area. The retrieval dataset in this study is of great significance for further exploring the impact of PM₁ on public health.