Effects of taxonomy,sediment, and water column on C:N:P stoichiometry of submerged macrophytes in Yangtze floodplain shallow lakes,China

Carbon (C), nitrogen (N) and phosphorus (P) are the three most important essential elements limiting growth of primary producers. Submerged macrophytes generally absorb nutrients from sediments by root uptake. However, the C:N:P stoichiometric signatures of plant tissue are affected by many additional factors such as taxonomy, nutrient availability, and light availability. We first revealed the relative importance of taxonomy, sediment, and water column on plant C:N:P stoichiometry using variance partitioning based on partial redundancy analyses. Results showed that taxonomy was the most important factor in determining C:N:P stoichiometry, then the water column and finally the sediment. In this study, a significant positive relationship was found between community C concentration and macrophyte community biomass, indicating that the local low C availability in macrophytes probably was the main reason why submerged macrophytes declined in Yangtze floodplain shallow lakes. Based on our study, it is suggested that submerged macrophytes in Yangtze floodplain shallow lakes are primarily limited by low light levels rather than nutrient availability.

     

活性碳纤维吸附废气中的丙烯酸和甲苯

采用动态吸附法探讨了在活性碳纤维对模拟废气中丙烯酸和甲苯的吸附过程中,各因素对活性碳纤维穿透吸附量和饱和吸附量的影响。实验结果表明,在模拟废气中丙烯酸质量分数为0.2%、双柱塞泵流量为6.1mL/h、载气流量为1.60L/min的条件下,穿透时间为10min,活性碳纤维的穿透吸附量为227.5mg/g,饱和吸附时间为40min,活性碳纤维的饱和吸附量为460.0m g/g。     

粗石英砂层厚度及倾角对核废物处置库顶盖毛细屏障效应的影响

毛细屏障作为核废物处置库顶盖的工程屏障之一,已经在国内外得到了广泛应用.采用箱体实验方法,研究了非饱和稳定流条件下粗石英砂层厚度和倾角对毛细屏障效应的影响.结果表明,随着粗石英砂层厚度的增大,水分的相对绕流量增大,毛细屏障效应增强;随着粗石英砂层倾角的增大,其表面积水减少,水的横向流动能力增强,毛细屏障效应增强.     

改性SiO2气凝胶对废水中Fe3+的吸附性能

制备了改性SiO₂气凝胶，考察了经不同类型、不同配比的改性剂改性的SiO₂气凝胶对模拟含Fe³⁺废水的吸附处理效果。实验结果表明：改性SiO₂气凝胶的最佳制备条件为三甲基氯硅烷（TMCS）作改性剂，V（TMCS）#x02236;V（正己烷）=1#x02236;5；当改性SiO₂气凝胶加入量为75g/L、吸附时间为4h、Fe³⁺质量浓度为10mg/L时，模拟含Fe³⁺废水的Fe³⁺去除率为98.32%，剩余Fe³⁺质量浓度为0.168mg/L；采用改性SiO₂气凝胶动态吸附处理流量为420mL/h、Fe³⁺质量浓度为100mg/L的模拟含Fe³⁺废水，吸附后废水中剩余Fe³⁺质量浓度仅为0.196mg/L。     

土壤中零价铁还原3-氯硝基苯的作用

利用零价铁在常温常压下对土壤中的3-氯硝基苯的还原，对反应物和产物随时间的变化及反应的各个影响因素进行了研究。实验结果表明，零价铁能够有效地将3-氯硝基苯还原为3-氯苯胺，反应过程中没有检测到脱氯产物。其反应速率随铁粉用量、反应体系含水量的增加以及反应温度的升高而升高，随土壤初始pH值的升高而降低。在土壤中3-氯硝基苯含量约为2.5×10^-6 mol/g，铁粉使用量为25 mg/g，反应体系中含水量为0.75 mL/g，pH值为6.8时，在恒温生化培养箱(25±1)℃反应5 h后，3-氯硝基苯的还原率达到92.75％。     

Insight into metal binding properties of biochar-derived DOM using EEM-PARAFAC and differential absorption spectra combined with two-dimensional correlation spectroscopy

Environmental Science and Pollution Research - A large amount of biochar-derived dissolved organic matter (BDOM) will be released into the environment with biochars application into repairing...     

Feasibility of nanoscale zerovalent iron-loaded sediment-based biochar (nZVI-SBC) for simultaneous removal of nitrate and phosphate: high selectivity toward dinitrogen and synergistic mechanism

Environmental Science and Pollution Research - In the process of water treatment, excessive nitrogen and phosphorus pollutants are of great concern. Therefore, we prepared nanoscale zerovalent iron...     

Polycyclic aromatic hydrocarbon and n-alkane pollution characteristics and structural and functional perturbations to the microbial community: a case-study of historically petroleum-contaminated soil

Characterization of the typical petroleum pollutants, polycyclic aromatic hydrocarbons (PAHs) and n-alkanes, and indigenous microbial community structure and function in historically contaminated soil at petrol stations is critical. Five soil samples were collected from a petrol station in Beijing, China. The concentrations of 16 PAHs and 31 n-alkanes were measured by gas chromatography-mass spectrometry. The total concentrations of PAHs and n-alkanes ranged from 973 ± 55 to 2667 ± 183 μg/kg and 6.40 ± 0.38 to 8.65 ± 0.59 mg/kg (dry weight), respectively, which increased with depth. According to the observed molecular indices, PAHs and n-alkanes originated mostly from petroleum-related sources. The levels of ΣPAHs and the total toxic benzo[a]pyrene equivalent (ranging from 6.41 to 72.54 μg/kg) might exert adverse biological effects. Shotgun metagenomic sequencing was employed to investigate the indigenous microbial community structure and function. The results revealed that Proteobacteria and Actinobacteria were the most abundant phyla, and Nocardioides and Microbacterium were the important genera. Based on COG and KEGG annotations, the highly abundant functional classes were identified, and these functions were involved in allowing microorganisms to adapt to the pressure from contaminants. Five petroleum hydrocarbon degradation-related genes were annotated, revealing the distribution of degrading microorganisms. This work facilitates the understanding of the composition, source, and potential ecological impacts of residual PAHs and n-alkanes in historically contaminated soil.

     

AOX contamination status and genotoxicity of AOX-bearing pharmaceutical wastewater

Adsorbable organic halogens(AOX) are a general indicator for the total amount of compounds containing organically bonded halogens. AOX concentrations and components were investigated along the wastewater treatment process in four large-scale pharmaceutical factories of China, and genotoxicity based on the SOS/umu test was also evaluated. The results showed that AOX concentrations in wastewater of four factories ranged from 4.6 to 619.4 mg/L, which were high but greatly different owing to differences in the raw materials and products. The wastewater treatment process removed 50.0%–89.9% of AOX, leaving 1.3–302.5 mg/L AOX in the effluents. Genotoxicity levels ranged between 2.1 and 68.0 μg 4-NQO/L in the raw wastewater and decreased to 1.2–41.2 μg 4-NQO/L in the effluents of the wastewater treatment plants(WWTPs). One of the main products of factory I, ciprofloxacin, was identified as the predominant contributor to its genotoxicity. However, for the other three factories, no significant relationship was observed between genotoxicity and detected AOX compounds.     

基于WebGIS的水环境模拟关键技术研究

近年来随着水环境模拟领域的发展出现了较多水环境数学模型,目前日益成熟的WebGIS技术是使模型使用变得简单化和直观化的一大途径.是在通过Flex和ArcGIS Server搭建WebGIS系统平台的基础上,利用PHP进行WebGIS和水环境模拟模型的数据交互,实现系统平台和数值模型的松散耦合.用户在浏览器端进行模型输入条件的设置,模型在远程服务器端进行运行计算,反馈的模拟结果通过RIA在WebGIS中进行多元化动态展示.该方法对一般模型具有适用性,可降低模型使用门槛,提高模拟结果展示和分析能力.