基于模拟-优化模型的某场地污染地下水抽水方案设计

针对抽出-处理技术修复污染地下水时抽水方案不合理导致修复成本高、修复效果差的问题,以我国北方某化工企业搬迁场地局部区域苯污染地下水为对象,通过GMS软件联合MGO(modular groundwater optimizer)程序对抽水方案进行模拟优化.结果表明:研究区地下水中检出ρ(苯)最大值为700 μg/L,修复目标为100 μg/L;自然降解条件下需1 740 d才能达到修复目标,降解缓慢.经过技术比选,选择抽出-处理技术快速修复该污染地下水.通过模拟-优化模型对抽出-处理技术中的抽水方案进行优化设计,结果显示,当抽水时间小于600 d时,出现水头疏干,无法进行抽出处理修复;当抽水时间在600～700 d范围内时,设计的抽水时间越长,达到修复目标所需的总抽水量越小,修复成本越低;当设计抽水时间超过700 d时,修复成本增加,1 500 d的抽水方案较700 d总抽水量增加了2.38×106 m3.综合修复时间及修复成本分析,虽然抽水时间为700 d时抽水量最小,但相对于抽水时间为600 d的优化方案,其抽水量仅减少1.4%,经济性较差,因此推荐抽水时间采用600 d.      

厨余垃圾水热处理的腐殖化特性研究

以模拟厨余垃圾为对象,考察了水热过程中反应温度、反应时间及无机弱酸对腐殖质形成与转化的影响,总结了腐殖质的生成机理,并通过红外光谱分析进行了验证.实验表明,水热处理后厨余垃圾腐殖化程度明显增高,在205℃、50 min工况下厨余垃圾的腐殖质含量达到39.52%,腐殖化率(胡敏酸与富里酸比值)达到1.31,腐熟度很高.在一定范围内,反应时间和温度升高能提升水热腐殖化强度.加0.01%的硫酸水热处理过后的腐殖质含量比未加酸要略高,而腐殖化率增加更为明显,表明氢离子对水热过程的腐殖质的形成及腐殖化率的提高有一定的促进作用.结合红外光谱分析推测,腐殖质的形成主要来自于一些糖类降解产物的缩合反应,以及这些小分子降解产物同难降解有机物如木质素的聚合反应.     

滇池流域宝象河水库沉积物中多环芳烃的垂直分布特征及来源解析

采用GC-MS检测了滇池宝象河水库沉积物中16种美国环保署(US EPA)优先控制的多环芳烃(PAHs)的含量,并对其垂直分布特征及来源进行分析,以此了解宝象河水库近年来PAHs的变化.结果表明,水库沉积物中16种PAHs均有检出,其含量范围为162.26~762.24ng·g~(-1),平均值为423.30 ng·g~(-1).自底层50 cm至表层,沉积物中PAHs含量呈上升趋势.从多环芳烃环数来看,沉积物中的PAHs以2~3环为主,其含量为128.34~518.81 ng·g~(-1),平均值为279.88 ng·g~(-1),占PAHs总量的42.2%~84.1%,平均值为67.6%.FLA/(FLA+PYR)、Ba A/(Ba A+CHR)和Icd P/(Icd P+Bghi P)3组比值及PAHs各组分的分析结果表明,燃烧过程是沉积物中PAHs的主要来源,主要为煤炭、生物质的燃烧.PAHs含量与总有机碳(TOC)之间有显著正相关关系,TOC影响宝象河水库沉积物中PAHs的分布.     

Fate of diuron and linuron in a field lysimeter experiment

The environmental fate of herbicides can be studied at different levels: in the lab with disturbed or undisturbed soil columns or in the field with suction cup lysimeters or soil enclosure lysimeters. A field lysimeter experiment with 10 soil enclosures was performed to evaluate the mass balance in different environmental compartments of the phenylurea herbicides diuron [3-(3,4-diclorophenyl)-1,1-dimethyl-urea] and linuron [3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea]. After application on the agricultural soil, the herbicides were searched for in soil, pore water, and air samples. Soil and water samples were collected at different depths of the soil profile and analyzed to determine residual concentrations of both the parent compounds and of their main transformation products, to verify their persistence and their leaching capacity. Air volatilization was calculated using the theoretical profile shape method. The herbicides were detected only in the surface layer (0-10 cm) of soil. In this layer, diuron was reduced to 50% of its initial concentration at the end of the experiment, while linuron was still 70% present after 245 d. The main metabolites detected were DCPMU [3-(3,4-dichlorophenyl)-1-methylurea] and DCA (3,4-dichloroaniline). In soil pore water, diuron and linuron were detected at depths of 20 and 40 cm, although in very low concentrations. Therefore the leaching of these herbicides was quite low in this experiment. Moreover, volatilization losses were inconsequential. The calculated total mass balance showed a high persistence of linuron and diuron in the soil, a low mobility in soil pore water (less than 0.5% in leachate water), and a negligible volatilization effect. The application of the Pesticide Leaching Model (PELMO) showed similar low mobility of the chemicals in soil and water, but overestimated their volatilization and their degradation to the metabolite DCPMU. In conclusion, the use of soil enclosure lysimeters proved to be a good experimental design for studying mobility and transport processes of herbicides in field conditions.     

宁夏水环境现状及水污染防治

宁夏是全国水资源严重短缺的省区之一,水资源人均占有量只有190立方米,是全国平均值的1/11.近年来,水污染进一步加剧了水资源的短缺,呈现出资源型缺水与水质型缺水共存的局面.     

试论生物安全“入典”之立法选择与规范表达

环境法典编纂背景下,生物安全是否纳入环境法典成为亟待解决的现实问题。就生物安全的概念而言,国际法采用狭义概念,国内法采用广义概念,单从任一概念与环境法的关系判断,生物安全“入典”貌似成了伪命题。但生物安全概念的国际法与国内法差异中蕴含着生物多样性保护和维持生态系统可持续发展的概念内涵,在生物安全与环境法典之间建立起沟通的桥梁。目前,生物安全具体领域专门立法的缺失以及环境法典体系化的需求,决定了生物安全必须纳入环境法典。生物安全与环境保护之间的关联性以及现有的国内、国际立法,为生物安全纳入环境法典提供了可能。当下国内法规定的广义的生物安全概念决定了其无法全部纳入环境法典,只能筛选旨在保护生物多样性与生态平衡,属于环境法传统核心领域的生物安全事项,以嵌入的方式纳入自然生态保护编。环境法典无法涵盖的生物安全事项,宜设置引致条款指向单行法的规定。     

Sub-chronic exposure to fluoxetine in juvenile oysters (<Emphasis Type="Italic">Crassostrea gigas</Emphasis>): uptake and biological effects

The bioconcentration potential of fluoxetine (FLX) and its biological effects were investigated in juvenile Pacific oyster exposed for 28 days to environmentally relevant concentrations of FLX (1 ng L^?1, 100 ng L^?1 and up to 10 μg L^?1). FLX bioaccumulated in oyster flesh resulting in 28-day bioconcentration factors greater than 2,000 and 10,000 by referring to wet and dry weights, respectively. Nevertheless, FLX did not induce oyster mortality, delayed gametogenesis, or lead to adverse histopathological alterations. At the two highest concentrations, despite non-optimal trophic conditions, FLX stimulated shell growth but only in a transient manner, suggesting a role of serotonin in the regulation of feeding and metabolism in bivalves. Those high concentrations seemed to drive bell-shaped responses of catalase and glutathione S-transferase activities throughout the exposure period, which may indicate the activation of antioxidant enzyme synthesis and then an enhanced catabolic rate or direct inhibition of those enzymes. However, no clear oxidative stress was detected because no strong differences in thiobarbituric acid-reactive substance (TBARS) content (i.e. lipid peroxidation) were observed between oyster groups, suggesting that cellular defence mechanisms were effective. These results demonstrate the importance of considering additional biomarkers of oxidative stress to obtain a comprehensive overview of the FLX-induced changes in marine bivalves exposed under realistic conditions. Considering the battery of biomarkers used, FLX appears to induce little or no effects on oyster physiology even at a concentration of 10 μg L^?1. These results do not confirm the lowest observed effect concentration (LOEC) values reported by some authors in other mollusc species.     

中国保护水生生物的甲基汞水质标准制订初探

甲基汞是具较强生物有效性和毒性的有机汞形态,其具有高生物累积性和生物放大效应,能对水生态系统中高营养级生物产生极高的危害,对脊椎动物造成神经毒性、内分泌干扰和生殖毒性等。我国不同环境介质(水、沉积物和生物体组织)中均检测到了甲基汞的存在。传统的水质基准仅依据水环境中水生生物急慢性毒性数据推导得到,未考虑污染物的生物有效性和生物累积性,采用该水质基准可能会对水生态系统造成欠保护。组织浓度是累积性物质生物有效性的直接体现,使用基于组织浓度的毒性数据推导水质基准进而确定水质标准,科学性更强,能更加合理、可靠地保护水生态系统。综述了甲基汞暴露最新毒性研究,在此基础上,采用物种敏感度分布法计算了甲基汞基于组织浓度的基准值为23.15 μg/kg,确定了其保护水生生物的水质基准值为0.12 ng/L,由此推导了其适合我国水环境的水生生物水质标准值为0.35 ng/L。研究结果可为甲基汞水质基准向水质标准的转化及生物累积性物质的水环境质量管理提供思路和支持。     

刍议我国污染场地修复现状与对策

随着城市化和产业转移进程的加快,我国城镇工业企业搬迁或遗留的污染场地数量与日俱增,亟须开展污染场地治理与修复工作,以保障人居环境安全、国民健康和社会稳定。本文综述了我国污染场地的产生及风险,污染场地管理、修复技术及工程实践进展,污染场地管理和修复的主要问题,场地污染防治与修复政策、技术和融资机制需求,旨在为我国污染场地修复产业化发展提供一定的参考。