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901.
Olson PE Flechter JS Philp PR 《Environmental science and pollution research international》2001,8(4):243-249
The natural attenuation of polyaromatic hydrocarbons (PAHs) in the vadose zone of a naturally revegetated former industrial sludge basin (0.45 ha) was examined. This was accomplished by comparing the concentration of 16 PAH contaminants present in sludge collected below the root zone of plants with contaminants present at 3 shallower depths within the root zone. Chemical analysis of 240 samples from 60 cores showed the average concentration of total and individual PAHs in the 0-30 cm, 30-60 cm, and bottom of the root zone strata were approximately 10, 20, and 50%, respectively, of the 16, 800 ppm average total PAH concentration in deep non-rooted sludge. Statistically significant differences in average PAH concentrations were observed between each strata studied and the non-rooted sludge except for the concentrations of acenaphthene and chrysene present at the bottom of the root zone in comparison to sludge values. The rooting depth of the vegetation growing in the basin was dependent on both vegetation type and plant age. Average rooting depths for trees, forbs (herbaceous non-grasses), and grasses were 90, 60, and 50 cm, respectively. The deepest root systems observed (100-120 cm) were associated with the oldest (12-14 year-old) mulberry trees. Examination of root systems and PAH concentrations at numerous locations and depths within the basin indicated that plant roots and their microbially active rhizospheres fostered PAH disappearance; including water insoluble, low volatility compounds, i.e. benzo(a)pyrene and benzo(ghi)perylene. The reduced concentration of PAHs in the upper strata of this revegetated former sludge basin indicated that natural attenuation had occurred. This observation supports the concept that through appropriate planting and management practices (phytoremediation) it will be possible to accelerate, maximize, and sustain natural processes, whereby even the most recalcitrant PAH contaminants (i.e. benzo(a)pyrene) can be remediated over time. 相似文献
902.
中国农村生活污水处理技术应用现状及研究方向 总被引:9,自引:0,他引:9
农村生活污水未经处理就直接排放,是造成农村水环境污染的原因之一,也是造成湖泊富营养化的重要因素,因此,归纳了目前国内一些先进的、适合于农村生活污水处理的技术,并对其研究方向进行了探讨和分析。 相似文献
903.
生态系统服务价值评估研究进展及其在环境保护中的意义 总被引:2,自引:0,他引:2
介绍了生态系统服务功能价值的国内外研究进展。对研究趋势进行了分析,并对开展生态价值评价在环境保护中的意义进行了分析。 相似文献
904.
环境生物技术的研究现状及发展前景 总被引:5,自引:0,他引:5
环境生物技术(Environmental Biotechnology)简称EBT,是近20年来才定义的新型边缘学科。环境生物技术主要由生物技术、工程学、环境学和生态学组成。一般认为生物工程即生物技术,是指综合应用生物学、化学和工程学等手段,直接或间接地利用生物体本身,生物体某些组分或某些特殊机能,生产有用物质的一门综合性科学体系。它的产生和发展涉及多种学科,既反映了基础科学研究的最新成果,也体现了工程科学开拓出来的新技术和新工艺。 相似文献
905.
906.
Reddy CM Drenzek NJ Eglinton TI Heraty LJ Sturchio NC Shiner VJ 《Environmental science and pollution research international》2002,9(3):183-186
INTENTION, GOAL, SCOPE, BACKGROUND: Identifying different sources and following reaction pathways of chlorinated organic contaminants in the environment can be challenging, especially when only their concentrations are available. Compound-specific stable chlorine measurements of some contaminants have recently been shown to provide additional information and an increased understanding of their biogeochemistry. These studies, however, have been generally limited to volatile molecules. OBJECTIVE: Here, the stable chlorine isotope ratios of the semi-volatile pesticide, 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) were investigated. Specifically, the intramolecular stable chlorine isotopic compositions of DDT and the kinetic isotope effect (KIE) for the abiotic dehydrochlorination of DDT to 2,2-bis(p-chlorophenyl)-1,1-dichloroethene (DDE) were determined. METHODS: Selective chemical oxidation of DDT to dichlorobenzophenone (DCBP) and analysis of each compound was used to calculate the stable chlorine isotope ratios of the alkyl and aromatic chlorines in DDT. To determine the KIE for dehydrochlorination, DDT was reacted in a basic solution to yield DDE at 52 degrees C, 60 degrees C, and 72 degrees C for 3, 5, and 5 days, respectively. RESULTS AND DISCUSSION: Significant intramolecular stable chlorine isotopic differences were observed in one sample of DDT where the alkyl and aromatic delta 37Cl values were -5.76 +/- 0.45 and -2.21 +/- 0.24%@1000, respectively. Dehydrochlorination of DDT to DDE in basic solutions at 52, 60, and 70 degrees C resulted in a substantial intramolecular KIE where the alkyl chlorines of DDE shifted by approximately 3%@1000 relative to the alkyl chlorines in DDT. However, no temperature dependence was observed. The KIE, calculated by an iterative program, was 1.009. CONCLUSIONS: Intramolecular differences in the stable chlorine isotope ratios were observed in DDT and this is the first such finding. Dehydrochlorination of DDT yields a measurable and distinct intramolecular stable chlorine KIE. RECOMMENDATION AND OUTLOOK: The results of this study demonstrate the existence of significant intramolecular differences in chlorinated organic compounds. Many other chlorinated semi-volatile and volatile organic contaminants are synthesized from multiple sources of chlorine, and we recommend that similar studies be performed on many such molecules in order to attain a clear understanding of their intramolecular chlorine isotopic differences. The existence of a measurable KIE for the dehydrochlorination of DDT to DDE shows the potential strength of using isotopic measurements to investigate the biogeochemistry of these important compounds. For example, the isotopically depleted aqueous chloride produced by dehydrochlorination of DDT to DDE may be a useful tracer of these reactions in freshwater environments. 相似文献
907.
喀斯特石漠化及其景观生态学研究展望 总被引:4,自引:0,他引:4
喀斯特石漠化是广泛分布于我国西南喀斯特地区的一种生态灾害,近30年来其扩展速度明显加快,严重制约了我国西南地区的经济发展和生态质量的提高。首先从概念、成因及防治等方面探讨了目前喀斯特石漠化的研究现状,并指出石漠化研究中的不足,主要表现为研究内容较片面,缺乏定量研究,标准不统一和缺乏景观水平上的研究。景观生态学有其特有的理论优势和方法体系,若利用景观生态学的理论和研究方法来研究石漠化,可以解决目前石漠化研究中的某些相关问题。最后,在此基础上,从景观生态学的角度出发,展望了喀斯特石漠化未来研究的4个方向,即景观格局变化、景观异质性及其分区、石漠化过程空间动态模拟和生物多样性. 相似文献
908.
目前,城市生活垃圾已成为我国当前一段时期较为突出的环境问题之一。近年来城市生活垃圾产生量持续大幅度上升,加上历史欠帐较多,目前的生活垃圾处理现状已不能适应城市发展对垃圾处理的需要。本文通过对乌兰察布市目前城市生活垃圾处理现状及其存在的问题进行分析的基础上,并根据乌兰察布市城市生活垃圾的特点及其变化趋势,基于可持续发展的环保战略要求提出了一些相应的对策措施。 相似文献
909.
以1996-2006年监测数据为基本依据,采用综合污染指数及spearm an秩相关系数法对苏州市城区河道外城河的水质变化趋势及污染特征进行分析评价。结果表明,河流总体水质呈现好转趋势,外城河水系污染属有机污染类型,主要污染因子为氨氮、石油类、生化需氧量、挥发性酚和高锰酸盐指数,水质严重污染因子已经由石油类转变为NH3-N。对外城河水质转好原因进行分析,由此提出了完善城市基础设施建设、加强河道疏浚、进行引水冲污等污染防治的对策措施。 相似文献
910.