Role of dissolved organic carbon in the cosorption of copper and phthalate esters onto Yellow River sediments

Although the sorption mechanism of hydrophobic organic pollutants on soils or sediments has been widely studied, the effects of coexisting heavy metals are seldom reported, especially the role of dissolved organic carbon (DOC) in sorption interactions involving heavy metals. This paper investigates the sorption interactions of phthalate esters (diethyl phthalate, DEP, and di-n-butyl phthalate, DnBP) and copper on Yellow River sediment in the presence of DOC. The results indicate that the sorption hardly varies for DEP but increases up to 20% for DnBP as the copper concentration increases in a water-sediment system with extremely low concentration of DOC. The copper-induced sorption of DnBP could be due to its complexation with copper, as well as its hydrophobicity. In a water-sediment system with the addition of 6.34 mg l(-1) of commercial humic acid (HA), the sorption of DEP is decreased by up to 37%, and that of DnBP is enhanced by up to 41%, as copper is gradually added. This finding is also consistent with the results for a river water-sediment system containing 8.1 mg l(-1) natural DOC. The copper-influenced sorption of DEP and DnBP are found to be due to the binding of copper to DOC that leads to the configuration change of DOC and thus to its enhanced sorption to sediment. By using polarograph and fluorescence spectrograph techniques, the complexation competition among coexisting phthalates, copper and DOC is examined. The resulting data confirm the significant role of DOC in sorption interactions.     

球形红细菌去除和转化铅的机理研究

通过X-射线衍射光谱分析,球形红细菌(Rhodobacter sphaeroides)H菌株对铅离子的转化产物为硫化铅.H菌株在不同浓度Pb2 中培养后,研究了该菌株生长细胞对Pb2 去除的动力学和该菌体产生半胱氮酸脱巯基酶活性的变化,用聚丙烯酰胺凝胶电泳法分析了其同工酶谱.结果表明,Pb2 浓度为25～150 mg·L-1时,去除速率常数k较大,半衰期T1/2较短,去除率较高;Pb2 浓度为75、100和150 mg·L-1时,对H菌株产生半胱氨酸脱巯基酶活力有明显的促进作用,Pb2 浓度为200 mg·L-1时,对该酶活力有抑制作用.该菌体细胞及亚细胞组分中铅含量测定结果显示,94%的Pb2 分布于细胞壁和细胞质内,仅少量存在于细胞膜上,并结合透射电镜观察和红外光谱分析,证明了该H菌株对铅离子去除和转化是在细胞质内进行的.     

SBR系统中活性污泥内源呼吸速率的研究

在SBR污水处理系统中应用呼吸速率测定仪对活性污泥的呼吸速率进行测定,探讨了污泥浓度和温度对内源呼吸速率的影响.对大量的比内源呼吸速率数据进行处理后发现,在混合液温度基本不变的基础上,内源呼吸速率与污泥浓度变化趋势一致,即比内源呼吸速率与污泥浓度无关;而温度对比内源呼吸速率的影响十分显著.这些结论为呼吸速率成为SBR工艺的控制参数提供了基础.     

土壤轻组有机质

轻组有机质主要是由不同分解程度的植物残体和一些微生物结构体组成,它的改变可以用来指示土壤肥力的变化.本文综述了轻组的分离方法、轻组的组成、种植和施肥对轻组的影响、轻组在土壤团聚体和土壤剖面中的分布以及轻组的季节性变化.     

基因芯片在环境毒理学研究中的应用进展

基因芯片可以将大量的DNA信息集成到 1cm2 左右的芯片上 ,对生命信息具有大规模平行处理的能力 ,为环境毒理学研究提供了一个理想的平台。基因芯片可以精确地完成污染物对人类基因表达影响的分析 ,并对污染物进行分类与分级 ,筛选毒物靶标和确定毒性机理。本文描述了基因芯片技术、毒理学应用研究现状及应用前景。引用文献 2 9篇。     

我国海洋自然保护区面临的主要问题及管理策略

我国海洋自然保护区的建立,在保护海洋环境、物种资源,维护海洋生态平衡等方面起了重要作用;然而海洋自然保护区建设管理工作起步较晚、基础薄弱、保护区的管理正处于摸索阶段,还存在一些问题.文章提出了目前我国海洋自然保护区在管理体制、总体布局规划、经费投入、法律法规以及科研工作方面存在的主要问题,并根据这些问题提出相应解决的管理策略.     

On-line controlling system for nitrogen and phosphorus removal of municipal wastewater in a sequencing batch reactor (SBR)

The objectives of this study were to establish an on-line controlling system for nitrogen and phosphorus removal synchronously of municipal wastewater in a sequencing batch reactor (SBR). The SBR for municipal wastewater treatment was operated in sequences: filling, anaerobic, oxic, anoxic, oxic, settling and discharge. The reactor was equipped with on-line monitoring sensors for dissolved oxygen (DO), oxidation-reduction potential (ORP) and pH. The variation of DO, ORP and pH is relevant to each phase of biological process for nitrogen and phosphorus removal in this SBR. The characteristic points of DO, ORP and pH can be used to judge and control the stages of process that include: phosphate release by the turning points of ORP and pH; nitrification by the ammonia valley of pH and ammonia elbows of DO and ORP; denitrification by the nitrate knee of ORP and nitrate apex of pH; phosphate uptake by the turning point of pH; and residual organic carbon oxidation by the carbon elbows of DO and ORP. The controlling system can operate automatically for nitrogen and phosphorus efficiently removal.     

Combined effects of cadmium and fluoranthene on germination, growth and photosynthesis of soybean seedlings

The single and combinational effects of cadmium (Cd) and fluoranthene (FLT) on germination, growth and photosynthesis of soybean seedlings were investigated. Exposure to 5, 10, or 15 mg Cd/L or 1, 5, or 10 mg FLT/L individually or in combination significantly decreased germination vigor (3 days) and final germination rate of soybean seeds, except at 1 and 5 mg FLT/L. The results of two-way ANOVA analysis and the Bliss independence model showed that at lower concentrations of FLT (1 mg/L), the interaction between Cd and FLT on germination was antagonistic, whereas the interaction was synergistic when the concentration of FLT was 5 or 10 mg/L and the concentration of Cd was 15 mg/L. Growth, expressed as dry weight, length of shoot and root, leaf area, and photosynthesis, expressed as net photosynthetic rate, intercellular CO2 concentration, chlorophyll contents and fluorescence of soybean seedlings were also reduced by exposure to 5 or 10 mg Cd/L or 1 or 5 mg FLT/L, singly or jointly. Significant antagonistic effects of exposure to 5 or 10 mg Cd/L or 1 or 5 mg FLT/L on shoot growth and photosynthesis were observed, whereas synergy and antagonism of Cd and FLT were both observed for root growth.     

杭州某退役污水处理厂退役场地污染调查与健康风险评估

通过对杭州某污水处理厂退役场地环境总体质量进行调查分析,得出场地主要超标特征污染物是锌、镍,污染区域主要分布在内堆场区域,内堆场土壤样品中重金属超标率为29%,最大超标深度为4 m,污染深度主要集中在0¹00 cm深度土层中。通过健康风险评估方法对退役场地在居住用地暴露情景下进行风险评估,评估结果表明,退役场地致癌风险较小,存在一定的非致癌风险,镍和铬是主要的非致癌风险污染物,主要的暴露途径是经口摄入暴露,基于退役场地后续开发利用规划,建议采用外运处置、客土封闭等技术对场地污染土壤进行修复。     

甲萘威在土壤中的吸附与迁移行为研究

分别采用振荡平衡法、土壤薄层层析法和土柱淋溶法研究了甲萘威在不同土壤中的吸附和淋溶特性。结果表明,甲萘威在红土、黄土、水稻土、黑土4种土壤中的吸附和淋溶性均存在差异。土壤吸附常数K d值分别为0.127、0.381、9.652、15.54,吸附能力强弱顺序为黑土>水稻土>黄土>红土。甲萘威在红土中属于易淋溶、可移动,在黄土中属于可淋溶、中等移动,在水稻土和黑土中属于难淋溶、不易移动。影响甲萘威在土壤中吸附和淋溶的主要因素是土壤有机质含量,土壤有机质含量越高,对甲萘威的吸附性越强,淋溶性越弱。