长江流域城市水污染治理成效的系统评估与解析

如何实现人类社会经济的可持续发展是本世纪的重大挑战之一。近几十年来,中国经济实力大幅提升,国际影响力显著增强。然而,经济社会高速发展可能会给生态环境造成诸多不利影响,其中之一就是人类活动污水排放总量的快速增长。长江经济带作为中国高质量发展的重点区域,科学评估和揭示沿江城市群污水治理成效及影响因素至关重要。本研究核算了2007-2017年间长江流域主要污染物的浓度变化趋势,利用数据驱动型技术对影响污染物通量变化的关键因子及其贡献开展了系统解耦和量化分析,揭示了污染物排放强度的时空异质性,解析了沿江城镇污水系统发展对污染物通量削减的作用效果。研究发现,长江流域水污染治理成效总体向好,长江经济带国内生产总值和沿江人类活动污水排放强度之间的强耦合在2013年之后呈现脱钩趋势,这主要得益于城镇排水和污水厂基础设施建设的快速发展。研究提出,长江流域城镇污水治理如何实现以水载资源再生利用为导引的“绿色零碳模式”转变,对于全面改善长江流域的水环境质量具有关键作用,同时也能为区域生态环境保护与经济高质量发展提供有益启示和借鉴。

Removal of pharmaceutical in a biogenic/chemical manganese oxide system driven by manganese-oxidizing bacteria with humic acids as sole carbon source

Bioaugmented sand filtration has attracted considerable attention because it can effectively remove contaminants in drinking water without additional chemical reagent addition.In this study,a synthesized chemical manganese dioxide (MnO_(2)) -coated quartz sand(MnQS) and biogenic manganese oxide (BioMnOx) composite system was proposed to simultaneously remove typical pharmaceutical contaminants and Mn_(2)+.We demonstrated a manganese-oxidizing bacterium,Pseudomonas sp.QJX-1,could oxidize Mn_(2)+to generate BioMnOxusing humic acids (HA) as sole carbon source.The coaction of MnQS,QJX-1,and the generated BioMnOxin simultaneously removing caffeine and Mn_(2)+in the presence of HA was evaluated.We found a synergistic effect between them.MnQS and BioMnOxtogether significantly increased the caffeine removal efficiency from 32.8%(MnQS alone) and 21.5%(BioMnOxalone) to 61.2%.Meanwhile,Mn_(2)+leaked from MnQS was rapidly oxidized by QJX-1 to regenerate reactive BioMnOx,which was beneficial for continuous contaminant removal and system stability.Different degradation intermediates of caffeine oxidized by MnQS and BioMnOxwere detected by LC-QTOF-MS analysis,which implied that caffeine was oxidized by a different pathway.Overall,this work promotes the potential application of bioaugmented sand filtration in pharmaceutical removal in the presence of natural organic matter in drinking water.

Defect-enhanced photocatalytic removal of dimethylarsinic acid over mixed-phase mesoporous TiO2

Much attention has been paid to the pollutant dimethylarsenic acid(DMA),because of its high toxicity even at very low doses.Although TiO2 photocatalytic oxidation(PCO)is one of the few effective methods for treating DMA-containing water,the efficient decomposition of DMA and simultaneous removal of toxic arsenic species remains a significant but challenging task.Here,defective mesoporous TiO2 with mixed-phase structure was synthesized and used as both photocatalyst and adsorbent for DMA removal.Due to the reduced band-gap and enhanced separation of photogenerated charge carriers,the oxygen-deficient TiO2 nanostructures exhibited 4.2 times higher PCO efficiency than commercial TiO2(P25).More importantly,the high surface area of the mesoporous TiO2 provided sufficient active sites for in-situ adsorption and reaction,resulting in the efficient removal of as-formed As(V).Combining the experimental and characterization results,the different roles of reactive species during PCO reactions were clarified.In the presence of hole(h+)as the dominant oxidation species,DMA was demethylated and transformed into MMA.Thereafter,MMA was subsequently reduced to As(Ⅲ)by photo-generated electrons.Superoxide radicals(O2·-)played a significant role in oxidizing As(Ⅲ)into As(Ⅴ),which was finally adsorptively removed by the mesoporous TiO2.

Mixing regime shapes the community assembly process,microbial interaction and proliferation of cyanobacterial species Planktothrix in a stratified lake

Lake mixing influences aquatic chemical properties and microbial community composition,and thus,we hypothesized that it would alter microbial community assembly and interac-tion.To clarify this issue,we explored the community assembly processes and cooccurrence networks in four seasons at two depths(epilimnion and hypolimnion)in a mesotrophic and stratified lake(Chenghai Lake),which formed stratification in the summer and turnover in the winter.During the stratification period,the epilimnion and hypolimnion went through contrary assembly processes but converged to similar assembly patterns in the mixing pe-riod.In a highly homogeneous selection environment,species with low niche breadth were filtered,resulting in decreased species richness.Water mixing in the winter homogenized the environment,resulting in a simpler microbial cooccurrence network.Interestingly,we observed a high abundance of the cyanobacterial genus Planktothrix in the winter,proba-bly due to nutrient redistribution and Planktothrix adaptivity to the winter environment in which mixing played important roles.Our study provides deeper fundamental insights into how environmental factors influence microbial community structure through community assembly processes.

Microbial responses to the use of NaClO in sediment treatment

Chlorine is often used in algal removal and deodorization of landscape waters,and occasionally used as an emergency treatment of heavily polluted sediments.However,the ecological impact of this practice has not been fully studied and recognized.In this study,NaClO at 0.1 mmol/g based on dry weight sediment was evenly mixed into the polluted sediment,and then the sediment was incubated for 150 days to evaluate its microbial effect.Results showed that NaClO addition enhanced the release of TOC,TN,Cr and Cu from the sediment.The microbial richness in the examined sediment decreased continuously,and the Chao1 index declined from 4241 to 2731,in 150 days.The microbial community composition was also changed.The abundance of Proteobacteria and Bacteroidetes increased to 54.8%and 4.2%within 7 days compared to the control,and linear discriminant analysis(LDA)showed gram-negative bacteria and aerobic bacteria enriched after chlorination.The functional prediction with PICRUSt2 showed the functions of the microbial community underwent major adjustments,and the metabolic-related functions such as carbon metabolism,including pyruvate and methane metabolisms were significantly inhibited;besides,15 out of 22 analyzed key enzymes involved in C cycling and 6 out of 12 key enzymes or genes involved in N cycling were strongly impacted,and the enzymes and genes involved in carbon degradation and denitrification showed remarkable downregulation.It can be concluded that chlorination posed a seriously adverse effect on microbial community structure and function.This study deepens the understanding of the ecological effects of applying chlorine for environmental remediation.