Distribution, risk and bioavailability of metals in sediments of Lake Yamdrok Basin on the Tibetan Plateau, China

Total contents of metals in soil and sediments on the Tibetan Plateau of China have been widely analyzed, but existing information is insufficient to effectively evaluate metal ecological risk because of a lack of metal bioavailability data. In this study, distribution, potential risk, mobility and bioavailability of metals in sediments of Lake Yamdrok Basin in Tibet of China were explored by combined use of total digestion, sequential extraction and the diffusive gradient in thin-films (DGT). Average concentrations of Cr, Ni, Cu, Zn, As, Cd and Pb in surface sediments were 31.25, 30.31, 22.00, 45.04, 31.32, 0.13 and 13.39 mg/kg, respectively. Higher levels of metals were found near the inflowing rivers. Residual form was dominant in Cr, Ni, Zn, Cd and Pb, and reducible form was dominant in As and Cd. Metals in surface sediments showed a low enrichment degree overall, but Cd and As had higher ecological risk levels than the other metals. Furthermore, there was a larger average proportion of exchangeable form of As (20.4%) and Cd (9.0%) than the other metals (1.7%-3.3%), implying their higher mobility and release risk. Average DGT-labile concentrations of Cr, Ni, Cu, Zn, As, Cd and Pb were 0.5, 4.5, 0.7, 25.1, 60.0, 0.22 and 1.0 µg/L, respectively. The DGT-labile As was significantly correlated with extractable As forms (p< 0.01), suggesting that extractable As in sediments acts as a “mobile pool” for bioavailable As. These results suggest potential risks of As and Cd, especially As, deserve further attention in Lake Yamdrok Basin.     

污染场地土壤气被动采样技术研究进展

在VOCs（挥发性有机物）污染场地调查中,土壤气采样的重要性日益受到重视.常规的土壤气采样主要依赖吸附管和采样罐等主动采样方法,但主动采样有很多缺点.作为一种新兴的采样技术,被动采样具有成本低、操作简单、更能代表长时间人体暴露、可用于低渗透性地层等优点,已经成为污染场地调查领域的研究热点.对被动采样的理论基础、采样器类型、吸附剂类型、采样误差的来源进行了介绍,对土壤气被动采样中存在的技术难题以及前沿研究方向进行了讨论,并对该技术在我国场地调查领域的应用前景进行了展望和建议.结果表明:在被动采样中准确控制采样器的采样速率（uptake rate）是保证其定量能力的关键,当控制采样速率低于土壤气中VOCs的补给速率时,可以实现良好的定量效果.影响采样速率的主要因素包括待测VOCs的性质、吸附剂种类、采样器结构以及各类环境因素,挥发性强的VOCs较难被捕集且容易发生逃逸.不同被动采样器用于不同种类VOCs采样时的采样速率可以相差6个数量级,从最低的0.005 5 mL/min到最高的125 mL/min.因此,建议在实际采样中应选用结构合理的采样器,控制采样速率不宜过大,以降低饥饿效应的产生;应选用与待测物匹配的吸附剂,对待测物兼具良好的保留能力和脱附能力;应加强环境因素（温度、湿度、土壤性质）对采样速率影响机制及场地校准方法的研究;应该结合研究和实践经验制定符合我国国情的土壤气被动采样技术指南.      

雄安新区土壤重金属地球化学监测关键问题探讨

为构建雄安新区土壤环境质量监控网,系统获取雄安新区建设前后土壤重金属地球化学数据,长期监测新区建设过程中土壤重金属的变化趋势,在分析雄安新区土地质量地球化学调查监测数据和土壤重金属元素地球化学空间变异特征的基础上,采用统计学方法估算构建新区土壤地球化学监测网所需要的采样密度、采样数量和采样周期等参数,为后续新区土壤重金属地球化学长期监测工作提供参考.结果表明,调查区重金属As、 Cd、 Cu、 Hg和Pb元素变异系数36%,属于高度变异元素; Cd、 Cu和Pb元素块金系数均75%,其高度富集是在较高自然背景上出现了人为源的叠加.在置信水平P为95%和90%时,对样本平均值允许误差Δ分别为5%、 10%和15%的条件下,同时对新区土壤中8种重金属As、 Cd、 Cr、 Cu、 Hg、 Ni、 Pb和Zn进行土壤环境质量监测,最少合理采样数分别为1 077个、 270个、 120个和767个、 192个、 86个.土壤各重金属元素可监测最小变化量(MDC)介于0.0025～2.54 mg·kg~(-1)之间.在不同的重金属年变化速率下土壤重金属监测所需要的重访间隔时间不同,在目前调查区重金属年变化速率条件下,调查区土壤监测所需要的重访间隔时间在2 a左右.     

某工业场地砷污染的加密布点优化与精度对比分析

场地污染调查是开展场地风险评估和修复的基础,随着我国颁布建设用地土壤风险管控标准等文件,提出风险筛选值和管制值的分级管控体系,我国土壤污染调查工作对于精确掌握污染物浓度梯度及空间分布有了更高的要求,因而如何构建高效采样布点方法变得尤为重要.本研究以南京市某砷工业污染场地为例,开展了优化布点方法与调查精度的研究.首先,在初查数据的基础上,运用指示克里格的方法预测土壤污染概率,参考城市土壤背景值开展阈值设定,提取加密布点区域,之后结合场地历史生产资料与自然信息布设加密点位,最终将插值预测污染结果与非加密、均匀加密、真实情况结果进行对比,验证方法精度.结果表明：本方法符合国际中基于设计抽样以达到场地调查简单、经济、客观的理念,适用于数据存在明显空间相关性的场地;该方法获得的污染区域面积占比为8.32%,与8.57%的现实情况较为接近,但普通法得到的污染面积比相对未加密情况不升反降,可能的原因是在非污染区域增设点位会造成阈值边缘区域在模拟时往清洁区域偏移,污染区域被误判为清洁,反而造成结果偏差;在目前我国环境管理对超阈范围重点关注的背景下,该方法既能够节约布点成本,又精确化预测场地污染超标范围,为后续的场地修复和治理工作提供帮助.     

烟气二氧化硫分析仪采样计量泵的研制与应用

采样误差是抽样式污染源气体分析仪最大的误差来源之一。采样的气体浓度越高 ,越需要高精度的气体采样计量泵。文章介绍的计量泵精度可达 0 .1 1 %。应用该计量泵可以基本消除气体分析仪采样方面的计量误差     

Statistical Analysis of Spatial Pattern: A Comparison of Grid and Hierarchical Sampling Approaches

Previous studies have combined random-site hierarchical sampling designs with analysis of variance techniques, and grid sampling with spatial autocorrelation analysis. We illustrate that analysis techniques and sampling designs are interchangeable using densities of an infaunal bivalve from a study in Poverty Bay, New Zealand. Hierarchical designs allow the estimation of variances associated with each level, but high-level factors are imprecisely estimated, and they are inefficient for describing spatial pattern. Grid designs are efficient for describing spatial pattern, and are amenable to conventional analysis. Our example deals with a continuous spatial habitat, but our conclusions also apply in disjunct or patchy habitats. The influence of errors in positioning is also assessed. The advantages of systematic sampling are reviewed, and more efficient hierarchical approaches are identified. The distinction between biological and statisticalsignificance in all analyses is emphasised.     

Microsoft Word for Windows在环境质量报告书中的应用

叙述了ＭｉｃｒｏｓｏｆｔＷｏｒｄｆｏｒＷｉｎｄｏｗｓ软件在编写环境质量报告书中的应用内容。     

大辽河入海口水质在线自动监测系统取样工程的建设与维护

介绍一个以自吸喷射泵为取样泵的水质自动监测系统取样工程建设方案及其日常维护措施。适用于河口和四季分明水域建设水质自动监测站需要,更可在其他类型水域建站时借鉴使用。     

生化需氧量测试方法稀释比的改良

由污水常规监测及实验室内质控样的分析结果,进行比较分析,获取经验常数,确立BOD_5与CODcr存在线性关系,可由CODcr计算BOD_5的近似值,引用经验公式,直接确定取样体积,对BOD_5常规测试方法进行了改良,以达到降低工作强度,提高监测人员工作效率的目的。