In developing countries, many urban rivers are suffering from heavy contamination by untreated sewage, which implies great microbial risks. However, information regarding the bacterial pathogen diversity and distribution in urban rivers is highly limited. In this study, 41 water samples of fifteen rivers and eight samples from two sewage treatment plants in Changzhou City of Yangtze River Delta were sampled. Next-generation sequencing and a self-built reference pathogen database were used to investigate the diversity of enteric and environmental pathogens. The results indicated that the studied urban rivers were harboring diverse potential pathogen species, which primarily included enteric pathogens in Arcobacter and Bacteroides, and environmental pathogens in Acinetobacter, Aeromonas and Pseudomonas. Quantification of twelve pathogens/indicators of interest by qPCR showed that Escherichia coli, Enterococcus faecalis, Campylobacter jejuni, Arcobacter cryaerophilus, Acinetobacter johnsonii, Acinetobacter lwoffii and Aeromonas spp. were abundant, with median values ranging from 3.30 to 5.85 log10 copies/100 mL, while Salmonella, Legionella pheumophila, Mycobacterium avium, Pseudomonas aeruginosa and Staphylococcus aureus were infrequently quantified. The pollution of nutrients and human intestinal microorganisms indicated by specific markers were found to be prevalent but with different levels in the rivers. The correlation analyses revealed that the diversity (p < 0.01) and concentrations (p < 0.05) of the enteric pathogens highly correlated to the human fecal marker abundances, which indicated that the enteric pathogens in the urban rivers were likely to have originated from domestic sewage. The environmental pathogens, which are different from the enteric ones, showed various distribution patterns, and some of them were more abundant in the rivers of rich nutrient. Our findings provide a comprehensive understanding of the bacterial pathogen distribution and influencing factors in urban rivers that are impacted by domestic sewage, thereby establishing the foundation for urban water management.

The bioavailability of a pollutant is usually evaluated based on its freely dissolved concentration (Cfree), which can be measured by negligible-depletion equilibrium extraction that is commonly suffered from long equilibration time. Herein, metal-organic framework (MOF) composites (Fe3O4@MIL-101), consists of a magnetic Fe3O4 core and a MIL-101 (Cr) MOF shell, is developed as sorbents for negligible-depletion magnetic solid-phase extraction (nd-MSPE) of freely dissolved polyaromatic hydrocarbons (PAHs) in environmental waters. The freely dissolved PAHs in 1000 mL water samples are extracted with 1.5 mg MOF composites, and desorbed with 0.9 mL of acetonitrile under sonication for 5 min. The MOF composites exclude the extraction of dissolved organic matter (DOM) and DOM-associated PAHs by size exclusion. Additionally, the combined interactions (hydrophobic, π-π and π-complexation) between PAHs and composites markedly reduced the extraction equilibration time to < 60 min for all the studied PAHs with logKOW up to 5.74. Moreover, the porous coordination polymers property of the MOFs makes the proposed nd-MSPE based on the partitioning of PAHs and thus excludes the competitive adsorption of coexisting substances. The developed nd-MSPE approach provides low detection limits (0.08–0.82 ng L−1), wide linear range (1–1000 ng L−1) and high precision (relative standard deviations (RSDs) (3.3–4.8%) in determining Cfree of PAHs. The measured Cfree of PAHs in environmental waters are in good agreement with that of verified method. Given the large diversity in structure and pore size of MOFs, various magnetic MOFs can be fabricated for task-specific nd-MSPE of analytes, presenting a prospective strategy for high-efficiency measuring Cfree of contaminants in environments.

Vermicomposting is a green technology used in the recycling of sewage sludge using the joint action of earthworms and microorganisms. Although tetracycline is present in abundance in sewage sludge, little attention has been given to its influence on vermicomposts. This study investigated the effects of different tetracycline concentrations (0, 100, 500 and 1000 mg/kg) on the decomposition of organic matter, microbial community and antibiotic resistance genes (ARGs) during vermicomposting of spiked sludge. The results showed that 100 mg/kg tetracycline could stimulate earthworms’ growth, accompanied by the highest humification and decomposition rates of organic matter in the sludge. The abundance of active microbial cells and diversity decreased with the increase in tetracycline concentrations. The member of Bacteroidetes dominated in the tetracycline spiked treatments, especially in the higher concentration treatments. Compared to its counterparts, the addition of tetracycline significantly increased the abundances of ARGs (tetC, tetM, tetX, tetG and tetW) and Class 1 integron (int-1) by 4.7–186.9 folds and 4.25 folds, respectively. The genera of Bacillus and Mycobacterium were the possible bacterial pathogen hosts of ARGs enriched in tetracycline added group. This study suggests that higher concentration of tetracycline residual can modify microbial communities and increase the dissemination risk of ARGs for final sludge vermicompost.

Soot nanoparticles (SNPs) produced from incomplete combustion have strong impacts on aquatic environments as they eventually reach surface water, where their environmental fate and transport are largely controlled by aggregation. This study investigated the aggregation kinetics of SNPs in the presence of macromolecules including fulvic acid (FA), humic acid (HA), alginate polysaccharide, and bovine serum albumin (BSA, protein) under various environmentally relevant solution conditions. Our results showed that increasing salt concentrations induced SNP aggregation by suppressing electrostatic repulsion and that CaCl2 exhibited stronger effect than NaCl in charge neutralization, which is in agreement with the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. The aggregation rates of SNPs were variously reduced by macromolecules, and such stabilization effect was the greatest by BSA, followed by HA, alginate, and FA. Steric repulsion resulting from macromolecules adsorbed on SNP surfaces was mainly responsible for enhancing SNP stability. Such steric repulsion appeared to be affected by macromolecular structure, as BSA having a more compact globular structure on SNP surfaces imparted long-range steric repulsive forces and retarded the SNP aggregation rate by 10–100 times. In addition, alginate was shown to enhance SNP aggregation by ∼10 times at high CaCl2 concentrations due to alginate gel formation via calcium bridging. The results may bear strong significance for the fate and transport of SNPs in both natural and controlled environmental systems.

Alternative transportation fuels (ATFs) can reduce air pollution. However, the influence of conventional fuels—diesel and gasoline, and particularly ATFs on photochemical air pollution is not well-characterized, limiting assessments of ATFs and air quality. This is mainly due to frequent use of lumped chemical mechanisms by related atmospheric modeling. Here we hypothesized that applying a chemical mechanism that is specifically developed according to both emission fractions and photochemical ozone creation potential of volatile organic compounds (VOCs) is key to gaining reliable insights into the impact of transportation fuels on photochemistry. We used a heterogeneous chemical mechanism with 927 reactions and relatively detailed emission inventories to specifically meet the requirements for reliable simulation of the effect of exhaust emissions from vehicles fueled by selected model fuels—diesel, gasoline, and mixtures of 15% gasoline with 85% ethanol (E85) or 85% methanol (M85)—on photochemistry. These dispersion-box model simulations revealed a strong influence of atmospheric background balance between VOCs and nitrogen oxides (NOX = [NO] + [NO2]) on the impact of exhaust emissions on photochemistry, with higher tendency toward ozone (O3) formation or destruction for more VOC-limited or NOX-limited conditions, respectively. Accordingly, higher [NOX]/[VOC] exhaust emission, such as from diesel and M85, resulted in lower O3, not only locally but also downwind of the emission. This offers a new perspective and measure for transportation fuel assessment. Rapid conversion of O3 to hydroxyl and hydroperoxyl radicals downwind of the exhaust emission indicates the importance of simulating the impact of road transportation on photochemistry at high spatial and temporal resolution. Peroxyacetyl nitrate formation was more sensitive to VOC emission under VOC-limited conditions than to NOX emission under NOX-limited conditions. Secondary formaldehyde dominated over primary emitted formaldehyde several minutes after emission. These findings should be verified using a 3D modeling study under varying meteorological conditions.

Soil is a fundamental carrier to support for human living and development and has been polluted seriously by heavy metals. This fact highlights the urgency to realize soil heavy metal pollution prevention through soil heavy metals contamination status assessment and root cause analysis. The previous research tends to focus status assessment and source identification without consideration of economic aspect. This study realized the systematic analysis from status assessment, sources identification and economic-environmental cost-benefits analysis in the Yangtze River basin. Through the spatial difference comparison among the provinces of upper, middle and lower in the Yangtze River basin, it revealed that anthropogenic influence is the main reason caused the current Cd contamination in Yangtze River basin. An interesting finding is that the human caused Cd concentration contribution amount is nearly the same between upstream and downstream which is all about 0.1 mg/kg, while they have quite different economic scale. It indicated that due to the difference of the scale and structure of local economy, and the level of cleaner production and pollution treatment, some regions could own high economic-benefits and low environmental cost, which it is opposite in other regions. The geographic location and natural resources is the root cause to form the environmental cost-economic benefits difference among regions. The convenient traffic promoted downstream to develop large amount and high quality of economy. The natural mineral resources promoted midstream to develop resources based economy. The poor condition of traffic and natural resources has restricted the development of Qinghai province, and made it has the highest Cd pollution intensity. The results would provide effective economic management measures for better soil quality and sustainable development goals achievement.

In the present study, we evaluate our previously developed non-destructive soil algal toxicity method using species from a different class of algae; Class Trebouxiophyceae (Chlorella vulgaris and Chlorella sorokiniana), and directly measure the photosynthetic activity of these species adsorbed onto the soil as a new toxicity endpoint. This study shows that non-destructive soil algal toxicity method is applicable to non-specific test species, including those of Class Trebouxiophyceae as well as Class Chlorophyceae (Chlorococcum infusionum and Chlamydomonas reinhardtii). Furthermore, by performing photosynthesis image analysis, we verify that it is possible to measure the photosynthetic activity of soil algae Chlorella vulgaris adsorbed onto soils without the need to extract algal cells from the soil. We propose that the non-destructive soil algal toxicity method represents a novel technique for 1) evaluating pollutants in soil using non-specific algae and 2) conveniently and rapidly assessing the photosynthetic activity of soil algae Chlorella vulgaris adsorbed onto soil as a new toxicity endpoint.

The influence of titanium dioxide nanoparticles (nTiO₂) on the transport and deposition of polystyrene microplastics (MPs) in saturated quartz sand was investigated in NaCl solutions with ionic strengths from 0.1 to 10 mM at two pH conditions (pH 5 and 7). Three different-sized polystyrene (PS) MPs (diameter of 0.2, 1, and 2 μm) were concerned in present study. We found that for all three different-sized MPs in NaCl solutions (0.1, 1 and 10 mM) at both pH 5 and 7, lower breakthrough curves and higher retained profiles of MPs with nTiO₂ copresent in suspensions relative to those without nTiO₂ were obtained, demonstrating that the copresence of nTiO₂ in MPs suspensions decreased MPs transport and increased their deposition in quartz sand under all examined conditions. The mechanisms contributing to the increased MPs deposition with nTiO₂ in suspensions at two pH conditions were different. The formation of MPs-nTiO₂ heteroaggregates and additional deposition sites provided by previously deposited nTiO₂ were found to drive to the increased MPs deposition with nTiO₂ in suspensions at pH 5, while the formation of MPs-nTiO₂ aggregates, additional deposition sites and increased surface roughness induced by the pre-deposited nTiO₂ on quartz sand surfaces were responsible for the enhanced MPs deposition at pH 7. The results give insights to predict the fate and transport of different-sized MPs in porous media in the copresence of engineered nanoparticles.

In recent years, the concentration of fine particulate matter has decreased gradually in the Pearl River Delta (PRD) region, but the ozone (O₃) concentration remains high and has become the primary air pollutant. In this study, using a three-dimensional numerical model [nested air quality prediction modeling system (NAQPMS)] coupled with an on-line source apportionment module, the contribution of different source regions and source categories to the O₃ concentration in the PRD region was quantified. A comparison with observation data confirmed that the NAQPMS adequately reproduced surface O₃ concentrations in different seasons. Compared with biogenic emissions, anthropogenic precursors play a dominant role in O₃ production. In Guangzhou city, among different source categories, mobile emission is the largest contributor (accounting for approximately 40%), followed by industry emissions (20%–24%). Regional control measures for solvent use and mobile emissions are effective for reducing O₃ concentration. In the PRD region, self-contribution is more significant in daytime (∼40%) than in nighttime (∼10%) on average. Among the source regions outside PRD, the northern part of Guangdong province, Jiangxi province, and Fujian province are important contributors. Within the PRD region, the self-contribution of each city increases by 12%–32% during O₃ episodes (>80 ppbv) compared with the annual mean contribution. The contribution of the entire PRD region and the entire Guangdong province is 46%–63% and 63%–74% in PRD cities during O₃ episodes. These results indicate that regional collaboration on emission control within PRD or Guangdong province is effective for reducing O₃ episodes in the PRD region. In addition, because long-range transport from regions outside Guangdong province played an important role in the O₃ concentration in the PRD region, long-term emission control measures throughout China in subsequent years should be propitious to further reduce the annual O₃ level and improve air quality in the PRD region.

Antibiotics as emerging pharmaceutical pollutants have seriously not only threatened human life and animal health security, but also caused environmental pollution. It has drawn enormous attention and research interests in the study of antibiotics removal from aqueous environments. Graphene, an interesting one-atom-thick, 2D single-layer carbon sheet with sp² hybridized carbon atoms, has become an important agent for removal of antibiotic, owing to its unique physiochemical properties. Recently, a variety of graphene-based nanomaterials (GNMs) are reported to efficiently remove antibiotics from aqueous solutions by different technologies. In this review, we summarize different structure and properties of GNMs for the removal of antibiotics by adsorption. Meanwhile, advanced oxidation processes (AOPs), such as photocatalysis, Fenton process, ozonation, sulfate radical and combined AOPs by the aid of GNMs are summarized. Finally, the opportunities and challenges on the future scope of GNMs for removal of antibiotics from aqueous environments are proposed.