太湖东部不同类型湖区疏浚后沉积物重金属污染及潜在生态风险评价

为揭示太湖东部疏浚湖区沉积物中重金属分布特征及其潜在生态风险,于2012年在东太湖与胥口湾共设置5个点位采集沉积物样品,测试了底泥部分理化性质及重金属元素含量(As、Cd、Cr、Cu、Hg、Ni、Pb、Zn),并运用潜在生态风险指数法综合评价了疏浚湖区沉积物的重金属污染现状和潜在风险程度.结果表明,太湖东部不同类型湖区间沉积物的营养盐及重金属含量分布存在差异,总体上胥口湾草型湖区的重金属含量相对东太湖养殖湖区较高,营养盐含量则相对较低;在垂直剖面上,沉积物营养盐和重金属均表现出表层富集的特征.太湖东部湖区各疏浚点位的营养盐和重金属含量均低于未疏浚点位,表明底泥生态疏浚能有效去除沉积物中的营养物质和重金属污染物,但疏浚效果随时间逐渐减弱.各重金属元素及营养盐之间均呈显著正相关关系,表明这些污染物具有较好的同源性.潜在生态风险指数RI的评价结果表明,各点位沉积物的重金属潜在危害程度依次为X1>D1>D3>X2>D2,其中未疏浚点位胥口湾X1的潜在生态风险高于东太湖D1,且X1、D1均属于中等生态风险,而疏浚点位D2、D3、X2属于轻微生态风险,底泥疏浚有效降低了沉积物中的重金属潜在生态风险.     

城市河流栖息地评价方法与应用

维持河流生物完整性必须要有良好的栖息地条件.城市河流栖息地评价是城市河流治理和管理的前提和基础.城市河流栖息地评价基准与城市河流栖息地特征密切关联.基于可拓学物元概念和其发散性特征,以及前人的研究,建立了包含水质、形态结构、水动力和水生生物4个类别要素的适应于城市河流健康修复实践的栖息地质量评价指标体系,同时,结合层次分析法建立了多级可拓物元评价模型,并在评价过程中引入可拓学诊断方法以确定影响栖息地质量的关键因子.将以上方法应用于镇江市古运河,结合古运河修复目标和现状条件建立了相应的指标评价标准.经过1a多时间的野外调查,在古运河上选择6个500m长特征河段,分别对其栖息地、要素质量进行比较评价.结果表明,古运河整体栖息地及水质、水动力和水生生物质量均较差;诊断分析表明,水动力和水质为影响栖息地质量的主要因素,水质污染指数、透明度、流量满足率和纵向连续性为影响古运河栖息地质量的主要因子,并根据评价结果对古运河栖息地修复提出了建议.     

pH值和硬度对两种氯酚类化合物对大型溞急性毒性的影响

以大型溞为研究对象,系统研究了pH值和硬度对2,4,6-三氯酚(2,4,6-TCP)和五氯酚(PCP)对大型溞急性毒性的影响.结果表明,pH值的影响非常显著.在实验pH值范围内(6~10),随pH值升高,两种氯酚对大型溞的急性毒性迅速降低,对不同pH值下两种氯酚在水中的形态分布与其毒性的相关性分析显示,pH值对毒性的影响机制与氯酚在水中的存在形态有密切关系,氯酚类物质的毒性主要由其分子态贡献,而pH值的升高促使分子态向离子态转化从而使其毒性降低.与pH值相比,硬度虽然对两种氯酚对大型溞急性毒性有一定的影响,但影响不显著.因此,在制定该类污染物的基准和标准时水体硬度的影响可以不作为关键因素考虑.     

基于群决策和层次分析法的长江中游地区农村污水处理技术评价及优选

长江流域农村污水治理是实现长江大保护的重要环节,但现有处理技术存在工艺多样、难以选择和缺少评价等问题.因此,调研收集了长江中游地区农村污水处理工程案例资料,分析了不同收集方式和排放标准下各处理技术的应用情况,构建了农村污水处理技术评价指标体系,并基于群决策和层次分析法对各处理技术进行了分类评价.结果表明,长江中游地区农村污水的收集方式以单村或小规模联村收集为主,处理规模主要集中在200 m³·d^-1以下,处理技术以厌氧+生态工艺应用最多(28.05%),一体化设备的应用也较为广泛(22.47%).评价指标体系准则层中技术性能权重最大(0.503 9),其次分别为经济效益(0.247 4)、运行管理(0.155 9)和环境影响(0.092 8),指标层中TP去除率、吨水运行成本、氨氮去除率和维护管理难易的权重较高.评价和优选结果表明,强化生态及厌氧+生态处理技术适于在长江中游农村地区推广和应用.研究结果可为长江中游地区农村污水处理技术的评估选择提供科学依据和参考.     

地质高背景区外源污染叠加条件下大白菜对Cd、Pb、Zn累积途径探究

黔西北是喀斯特重金属地质高背景区,受历史上土法炼锌影响,区域内大气降尘重金属含量高,土壤污染严重.为探究叶菜类蔬菜重金属的累积途径,以大白菜为供试作物,选择Cd、 Pb和Zn含量一致的地质高背景土壤和锌冶炼污染土壤,在锌粉厂污染区和无污染对照区进行盆栽试验,研究露天、覆膜和大棚栽培条件下大白菜重金属含量、富集系数(BCF)和转运系数(TF).结果表明,污染区和对照区大白菜ω(Cd)范围分别在0.10～1.01 mg·kg^-1和0.10～0.91 mg·kg^-1,ω(Pb)为0.31～0.62 mg·kg^-1和0.23～0.37 mg·kg^-1,ω(Zn)为7.50～32.74 mg·kg^-1和4.88～21.79 mg·kg^-1,总体上污染区重金属含量偏高,在地质高背景土壤上种植的大白菜,Cd和Pb基本达到国家食品安全标准限值的要求.受大气沉降的影响,污染区大白菜Pb和Zn含量显著高于对照区,Cd差异不明显.污染土壤弱酸溶态Cd、 Pb和Zn占比分别为48...     

Bioaccumulation,subcellular, and molecular localization and damage to physiology and ultrastructure in Nymphoides peltata (Gmel.) O. Kuntze exposed to yttrium

Bioaccumulation, subcellular distribution, and acute toxicity of yttrium (Y) were evaluated in Nymphoides peltata. The effects of Y concentrations of 1–5 mg L^?1 applied for 4 days were assessed by measuring changes in photosynthetic pigments, nutrient contents, enzymatic and non-enzymatic antioxidants, and ultrastructure. The accumulation of Y in subcellular fractions decreased in the order of cell wall > organelle > soluble fraction. Much more Y was located in cellulose and pectin than in other biomacromolecules. The content of some mineral elements (Mg, Ca, Fe, Mn, and Mo) increased in N. peltata, but there was an opposite effect for P and K. Meanwhile, ascorbate, and catalase activity decreased significantly for all Y concentrations. In contrast, peroxidase activity was induced, while initial rises in superoxide dismutase activity and glutathione content were followed by subsequent declines. Morphological symptoms of senescence, such as chlorosis and damage to chloroplasts and mitochondria, were observed even at the lowest Y concentration. Pigment content decreased as the Y concentration rose and the calculated EC₅₀ and MPC of Y for N. peltata were 2 and 0.2 mg L^?1 after 4 days of exposure, respectively. The results showed that exogenous Y was highly available in water and that its high concentration in water bodies might produce harmful effects on aquatic organisms. N. peltata is proposed as a biomonitor for the assessment of metal pollution in aquatic ecosystems.     

上海春季大气PM_1分布特征

利用2015年春季(3月—5月)上海地区9个大气成分站在线观测获得的地面PM_1质量浓度数据,研究该地区PM_1浓度时空分布特征。结果表明,上海地区各站PM_1污染浓度水平总体较高,整个上海地区的PM_1小时平均浓度为26.3μg?m~(-3),最大值为126.4μg?m~(-3),最小值为2.4μg?m~(-3);各站PM_1浓度的日变化分布表现为峰值类型和峰值时间不一;各站PM_1三个主要粒径段的质量浓度比值均有一定的差异,其中东滩PM_1比例最大,宝山最小;上海春季PM_1的浓度逆周末效应,可能是由于春季气象条件周期性影响。     

模拟地下水环境微生物降解甲苯的研究

采集某加油站附近的土样，进行富集、培养、分离纯化，获得一系列降解甲苯的菌株，选择了出降解率最高的菌株进行诱变，再筛选出降解特效菌株，并模拟地下水环境进行驯化。菌株在12d内对甲苯的降解率达到93．5％。利用渗流槽模拟扩大降解实验，第11天甲苯的降解率达87．3％，第15天达到95．2％，证明该菌株是一种能够有效降解地下水中甲苯的菌株。     

Three-dimensional eutrophication model and application to Taihu Lake, China

Taihu Lake, the largest freshwater shallow lake in eastern China, has suffered from severe eutrophication over the past two decades. This research developed a three-dimensional eutrophication model to investigate the eutrophication dynamics. The model fully coupled the biological processes and hydrodynamics, and also took into account the effects of sediment release and the external loads from the tributaries. After sensitivity analyses, the key parameters were defined and then calibrated by the field observation data. The calibrated model was applied to study the seasonal primary productions and its regional differences. The comparisons between model results and field data in year 2000 indicated that the model is able to simulate the eutrophication dynamics in Taihu Lake with a reasonable accuracy. From the simulation experiments, it was found that the meteorological forcing have significant influences on the temporal variations of the eutrophication dynamics. The wind-induced circulation and sediment distribution play an important role in the spatial distribution of the algae blooms.