土壤环境重金属污染风险的综合评价模型

综合考虑了土壤环境中重金属的总量富集污染及各重金属在土壤中不同赋存形态的生物有效性差异,将风险评估指数(RAC)嵌入地累积指数模型,建立了土壤环境重金属污染风险的综合评价模型。应用所建模型评价某典型污灌区土壤中各重金属污染的风险程度,通过分析评价结果以及和同类模型评价结果的对比,所建模型更全面、真实地表征了该区域土壤重金属污染的风险水平,为我国土壤资源管理和优先控制因子的选取提供了新思路。     

密云水库上游某铁矿区土壤重金属含量及形态研究

应用富集因子法(EF)和风险评估编码方法(RAC)对北京市密云水库上游某铁矿矿区及其周边土壤中重金属的分布状况和潜在生态风险进行了研究.结果表明,各重金属元素含量除As外,其余均明显高于北京市土壤重金属背景值,矿区的选冶活动已经对下游的水体和土壤环境造成一定的影响.富集因子法评价表明Cd、Pb、Cr富集较为严重,达到显著污染水平.形态分析表明,残渣态是重金属元素的主要存在形态, Cd元素可交换态所占比例(2.88%~21.15%)最高,RAC评价结果显示Cd基本处于中等风险水平,Pb为无风险,风险等级由强至弱的顺序为:Cd>Mn>Zn>Cu>Co>Cr>Pb.     

分光光度法测定空气中氢氧化钠气溶胶

针对常用的滴定法测定空气中氢氧化钠气深胶的不足，研究了用分光光度法对其测定．实验证明，此法具有许多优点，并能得到满意的结果     

The spatial scale of organic chemicals in multimedia fate modeling. Recent developments and significance for chemical assessment

In the last years, the spatial range (SR) or characteristic travel distance (CTD) of organic chemicals has found increasing scientific interest as an indicator of the long-range transport (LRT) potential and, in combination with persistence, as a kind of 'hazard' indicator on the exposure level. This development coincides with European debates about more effective and more preventive approaches to the chemicals assessment, and about an international, legally-binding instrument for the phase out of persistent organic pollutants (POPs). Persistence and LRT potential are important issues in these debates. Here, the development of the concept of assessing the spatial scale from early ideas in the 1970s and 1980s to recent studies in the field of multimedia fate and transport modeling is summarized. Different approaches to the modeling of environmental transport (advective and dispersive) and different methods for quantifying the SR or CTD are compared. Relationships between SR or CTD and different persistence measures are analyzed. Comparison of these relationships shows that conclusions for chemical assessment should be based on an evaluation of different persistence and spatial scale measures. The use of SR or CTD and persistence as hazard indicators in the chemicals assessment is illustrated.     

Intergovernmental relationships after disaster: state and local government learning during flood recovery in Colorado

ABSTRACT

When communities experience disaster, emergency response and recovery are led internally, based on local-level policy decisions and priorities. Decisions about how or whether to rebuild are made by local governments. Higher governmental authorities such as states and provinces may institute their own disaster recovery processes and policies in addition to or in competition with local governments. Greater intergovernmental engagement could increase resources and knowledge, which would yield higher levels of learning and result in superior disaster recovery policy outcomes. The role of higher authorities, then, can have important implications for policy processes and outcomes. The learning literature includes a dearth of studies that analyze the relationships between state and local governments during disaster recovery. We move the learning literature forward by analyzing intergovernmental relationships during disaster recovery. We find that learning within local governments is associated with higher levels of resource flows from state agencies as well as more collaborative intergovernmental relationships. We also find that state governments can improve processes for disaster recovery assistance and bring together disaster-affected local governments to promote learning during the recovery process. While this study focused on relationships constrained by U.S. federal dynamics, the lessons are useful to other multilevel governance systems.     

湖泊水动力模型外部输入条件不确定性和敏感性分析

以我国典型的大型浅水湖泊太湖为研究区域,采用国内外常用的环境流体动力学模型(EFDC),结合拉丁超立方取样(LHS)方法,研究湖泊水动力模型中4个重要的外部输入条件,即3个边界输入条件(出入湖流量、风速、风向)和1个初始输入条件(初始水位),对模型水动力模拟结果(水位、水龄以及流场)的影响与贡献.结果表明,初始水位的设定对模拟全湖水位和水龄产生决定性影响,不确定性的贡献率分别达到85.73%和66.125%,对垂向平均流速影响的贡献率只有3%;风速对表面流速模拟结果影响较大,贡献率达到58.70%,而对水位和水龄的贡献率分别为5.25%和3.00%.在垂向上,各层流速受外部输入条件不确定性的影响规律相似,贡献率排序为风速(55%~60%)>风向(10%~15%)>初始水位≈出入湖流量(1%~5%).因此在模拟大型浅水湖泊水动力过程时,可以根据不同的输出目标能够有针对性地提高外部输入条件的准确度,为提高模型精确度提供有效信息.     

太湖不同营养水平湖区表层沉积物的砷分布特征及其生态风险

以太湖不同营养水平湖区为研究对象,采用改进的砷(As)形态连续提取法对表层沉积物中As的化学形态进行分析研究,探讨了沉积物中总砷(TAs)和As形态的分布特征及其与沉积物中营养盐和总有机碳(TOC)的相关性,并利用潜在生态风险评价(Eir)和风险指数编码法(RAC)评估了各湖区沉积物中As的生态风险水平.结果表明,各湖区表层沉积物中TAs的平均含量约为14.23~16.59 mg·kg~(-1),其中,竺山湾的TAs平均含量相对最高.As形态表现出明显的空间分布特征,其中,北部富营养湖区(竺山湾、梅梁湾、贡湖湾)中的有效态As(非专性吸附态和专性吸附态)与潜在有效态As(无定形氧化铁结合态、晶体形氧化铁结合态、有机结合态)的含量与百分比均高于中营养水平的南太湖,而北部湖区的残渣态As含量则低于南太湖.Pearson相关分析结果显示,除晶体形氧化铁结合态As和残渣态As外,沉积物总氮(TN)、总磷(TP)和TOC与其他As形态均存在显著的正相关关系.潜在生态风险评价结果表明,各湖区沉积物TAs均处于低风险;而RAC评价结果表明,各湖区沉积物的有效态As基本处于中等风险水平,且北部湖区的RAC指数均明显高于南太湖.     

Dovehicular emissions dominate the source of C6-C8aromatics in the megacity Shanghai of eastern China?

The characteristic ratios of volatile organic compounds (VOCs) to i-pentane, the indicator of vehicular emissions, were employed to apportion the vehicular and non-vehicular contributions to reactive species in urban Shanghai. Two kinds of tunnel experiments, one tunnelwith more than 90% light duty gasoline vehicles and the otherwithmore than 60% light duty diesel vehicles, were carried out to study the characteristic ratios of vehicle-related emissions from December 2009 to January 2010. Based on the experiments, the characteristic ratios of C6-C8 aromatics to i-pentane of vehicular emissions were 0.53 ± 0.08 (benzene), 0.70 ± 0.12 (toluene), 0.41 ± 0.09 (m,p-xylenes), 0.16 ± 0.04 (o-xylene), 0.023 ± 0.011 (styrene), and 0.15 ± 0.02 (ethylbenzene), respectively. The source apportionment results showed that around 23.3% of C6-C8 aromatics in urban Shanghai were from vehicular emissions, which meant that the non-vehicular emissions had more importance. These findings suggested that emission control of non-vehicular sources, i.e. industrial emissions, should also receive attention in addition to the control of vehicle-related emissions in Shanghai. The chemical removal of VOCs during the transport from emissions to the receptor site had a large impact on the apportionment results. Generally, the overestimation of vehicular contributions would occur when the VOC reaction rate constant with OH radicals (k_OH) was larger than that of the vehicular indicator, while for species with smaller kOH than the vehicular indicator, the vehicular contribution would be underestimated by the method of characteristic ratios.     

A review on current status of municipal solid waste management in India

Municipal solid waste management is a major environmental issue in India. Due to rapid increase in urbanization, industrialization and population, the generation rate of municipal solid waste in Indian cities and towns is also increased. Mismanagement of municipal solid waste can cause adverse environmental impacts, public health risk and other socio-economic problem. This paper presents an overview of current status of solid waste management in India which can help the competent authorities responsible for municipal solid waste management and researchers to prepare more efficient plans.     

Occurrence and distribution of micro- and mesoplastics in the high-latitude nature reserve,northern China

• The first study on micro(meso)plastics (MMPs) in the Liaohe River Reserve is reported. • Diverse MMP were detected in surface water and sediment at all 32 sites. • The abundance of MMPs decreased in the course of the river. • The MMPs abundance in water is significant association with the county population. Microplastics pollution has received growing attention worldwide in recent years. However, data on microplastics in the freshwater environment are still limited, especially in high-latitude nature reserves in Northern China. The first study on microplastic pollution in the Liaohe River Reserve in Northern China is reported here, and mesoplastics were also incorporated. Surface water and sediment samples were collected from 32 sites along the nature reserve. The abundance, type, shape, color, and size of micro- and mesoplastics were measured using density extraction, optical microscopy, and FTIR spectroscopy. The data showed that diverse micro- and mesoplastics were found widespread in the 32 sites, and the average abundance of these plastics was 0.11±0.04 10⁻² items/L in surface water and 62.29±54.30 items/kg in sediment. Moreover, 70% and 66% were smaller than 2000 μm in surface water and sediment, respectively. Fiber accounted for 91.86% in surface water and 43.48% in sediment, indicating that the major source of micro- and mesoplastics in the Liaohe River Reserve may be domestic sewage and aquaculture. A total of 16 and 27 polymers were identified in surface water and sediment, respectively, and mostly consisted of rayon, polyester, polystyrene, and poly(ethylene terephthalate). Moreover, both the risk index and the pollution load index demonstrated a low risk of micro- and mesoplastics in surface water and sediment in the Liaohe River Reserve.