地表水环境中微(纳米)塑料污染防控面临的挑战

微(纳米)塑料因其可在水体、沉积物、土壤等环境介质中长期存在并危害生态环境,且在环境中难降解的特性已成为一种新污染物。根据国内地表水环境中微(纳米)塑料的分布、来源和生态毒性效应的相关研究发现,地表水环境中微(纳米)塑料的来源繁杂,直接来源主要包括个人护理品、工农业制备、各类垃圾不当处置等;间接来源为污水处理厂的污水排放、地表径流、原始塑料的风化降解等。微(纳米)塑料的生态毒性组成复杂,除其本身对于生物体的生化胁迫外,还易与其他污染物形成复合污染,对水生生物产生交互效应。因此,研究治理地表水环境微(纳米)塑料污染已刻不容缓,本文可为地表水环境中微(纳米)塑料污染防控和生态风险研究提供理论参考。

微塑料暴露下有/无植物人工湿地脱氮性能的对比

为揭示湿地植物对微塑料暴露湿地脱氮性能的影响,构建了2组垂直流人工湿地(黄菖蒲湿地和无植物湿地),对比了聚苯乙烯微塑料(PS MPs)短期和长期暴露下2组湿地植物和微生物生态效应及脱氮性能的差异.结果表明,2组湿地均可实现PS MPs的有效去除,去除率均超过99.8%;PS MPs短期暴露下,黄菖蒲湿地体现出更高的脱氮性能;而PS MPs的长期暴露对黄菖蒲光系统和抗氧化系统将产生不利影响,叶片光合色素质量分数下降了13.92%~26.15%;PS MPs短期及长期暴露下,黄菖蒲湿地中微生物物种丰富度和多样性更高,硝化细菌和反硝化细菌的整体丰度也高于无植物湿地.以上结果为同步去除污水中氮素和微塑料的人工湿地设计提供了参考.

钙改性玄武岩纤维对人工湿地污水处理性能的提升

为研究钙改性玄武岩纤维(Ca-MBF)及其填充方式对人工湿地污水处理性能的影响,构建中试规模的分层平铺和垂直填充Ca-MBF人工湿地,并与传统人工湿地的除污效果、酶活性空间分布、胞外聚合物含量及微生物群落结构进行对比.结果表明,Ca-MBF能提高人工湿地微生物多样性和丰富度,增加基质上层与中层硝化菌和反硝化菌丰度,促进功能属之间合作.Ca-MBF显著提高了湿地中层和下层的酶活性,使整个系统的平均酶活性升高(氨单加氧酶、亚硝酸氧化还原酶、硝酸还原酶、亚硝酸还原酶和磷酸酶).此外,Ca-MBF促进了胞外聚合物的分泌,平均增加了29.02%~52.90%.Ca-MBF能提升湿地去除污染物的能力,分层平铺的Ca-MBF湿地效果最好,其对氨氮、总氮和总磷去除率分别提高16.72%、6.95%和6.30%.这些结果为Ca-MBF人工湿地的应用提供了有价值的参考.

Wastewater treatment performance and microbial community structure in the constructed wetland under double-pressure of low temperature and Ag NPs exposure

To investigate the effects of silver nanoparticles(Ag NPs)and low temperature double-pressure on the wastewater treatment efficacy and the microbial community structure of constructed wetlands,a pilot-scale vertical flow constructed wetland was set up to treat synthetic wastewater under laboratory conditions.By measuring the effluent concentration of ammonia nitrogen(NH_(4)^(+)-N),total nitrogen(TN),total phosphorus(TP),chemical oxygen demand(COD),and the diversity,richness,and community structure of microorganisms of the upper and lower soil layers in the wetland,the nutrient removal effect of the constructed wetland and the changes in the microflora of the soil layer were studied.The results reveal that the correlation coefficients between the removal rates of TN and NH_(4)^(+)-N and the temperature are 0.463 and 0.692,respectively,indicating a significant positive correlation.From the warm to the cold season,both the diversity and richness of microorganisms in the lower soil layer of wetlands are inhibited under the double-pressure of Ag NPs and low temperature,and the abundances of the denitrogenation functional bacteria such as Candidatus nitrososphaera,Sulfuritalea,Anaeromyxobacter,Candidatus solibacter,Nitrospira,and Zoogloea are altered.Low temperature and Ag NPs exposure can thus affect the wastewater treatment performance of constructed wetlands,possibly because of the seasonal changes of the microflora.

Effects of silver nanoparticles on resistance characteristics of the wetland plant Typha orientalis in a hydroponic system

To probe the influence and the adverse-resistance characteristics of wetland plants in presence of silver nanoparticles (AgNPs), the changes in the physiological and biochemical characteristics (including the superoxide dismutase (SOD) activity, catalase (CAT) activity, peroxidase (POD) activity, soluble protein content, and chlorophyll content) of Typha orientalis exposed to different concentrations of AgNPs solutions (0, 0.1, 1, 20 and 40 mg/L) were explored. Meantime, the accumulation of silver content in these plants was revealed. The results show that under low concentrations of AgNPs, the SOD and POD activities in the leaves of Typha orientalis are strengthened to different degrees. However, high concentrations of AgNPs inhibit the activities of SOD and POD. Under the stress of different concentrations of AgNPs, the CAT activities are inhibited initially and later recovered to some extent. Under the stress of low concentrations of AgNPs, the soluble protein content in the leaves of Typha orientalis increases significantly, but decreases more significantly with increasing concentrations of AgNPs. Low concentrations of AgNPs promote chlorophyll synthesis in the leaves of Typha orientalis , but the chlorophyll content subsequently falls to pre-stress levels. In contrast, high concentrations of AgNPs cause a certain inhibition to generate chlorophyll. Meanwhile, the results show that the silver concentrations of plant tissues increase with the exposure of concentrations of AgNPs and they have a positive relationship with the exposure of concentrations of AgNPs.

Responses of soil enzyme and microbial community under co-loading of different microplastics and sulfamethoxazole

Polyamide/polyethylene(PA/PE)microplastics were injected into soil containing sulfamethoxazole(SMX)to investigate their combined effects on SMX removal,soil enzyme activity,and microbial communities.The results show that both PA and PE transiently increase SMX removal and inhibite the stimulation of microbial species diversity by SMX.The effect of PE is more significant.Meanwhile,PE combined with SMX increases the relative abundances of Actinobacteria and Pseudomonas,while PA combined with SMX decreases the relative abundances of Nocardioides and Streptomyces.In addition,PA/PE combined with SMX can increase dehydrogenase,urease,ammonia monooxygenase,and nitrate reductase activities in the soil while inhibiting the activity of laccase.Compared with PA combined with SMX,the activities of dehydrogenase,urease,ammonia monooxygenase,and laccase of PE combined with SMX increase by 9.82%,10.41%,8.07%,and 5.47%,while the activities of nitrate reductase and neutral phosphatase decrease by 1.47%and 6.78%.