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伊犁河流域土壤重金属环境地球化学基线研究及污染评价 总被引:7,自引:4,他引:3
采用标准化方法建立伊犁河流域黑钙土、栗钙土、灰钙土和盐碱土Cu、Zn、Pb、As、Hg环境地球化学基线模型,并计算其理论基线值.采用基线因子污染指数评价法、环境背景值评价法和重金属环境洁净度评价法对流域土壤进行对比污染评价.结果表明:①基线因子污染评价显示流域内4种典型土壤类型以As的污染最为突出,黑钙土、栗钙土、灰钙土分别有7.14%、9.76%、7.50%的样点达重度污染;其次为Pb,栗钙土有7.32%的样点达重度污染,且As和Pb的变异度最大,表明人为扰动大.②环境背景值评价显示,土壤主要污染元素为As,其次为Cu、Zn、Pb;③土壤重金属环境洁净度评价显示,Cu、Zn、Pb在4种土类中均优于二级洁净度,Hg为一级洁净度,As在灰钙土中为中度污染,黑钙土、栗钙土、盐碱土为二级或优于二级.比较3种评价体系,基线因子污染评价较为充分地体现了元素地球化学迁移特性及土壤发育过程,且可将污染评价定位到样点;而背景值污染评价因建立于区域背景值,忽视了重金属元素在土壤中自然迁移、淀积过程;重金属环境洁净度评价则以土壤环境安全度为主要评价目的. 相似文献
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风浪扰动对太湖水体重金属形态的影响 总被引:4,自引:0,他引:4
对不同风浪条件下水体中的悬浮颗粒物,采用ICP-AES测定其中Co,Cr,Cu,Ni,Pb,Zn,Al,Fe和Mn不同形态的含量.研究表明,水体中Al,Fe,Co,Cr,Pb和Ni可提取态含量随风浪扰动程度的增强其含量均有不同程度的增大. Mn,Zn和Cu在7m·s-1风浪下含量最高,11m·s-1风浪次之,2m·s-1风浪最小.7m·s-1风浪与2m·s-1风浪相比,水体中Mn, Co, Cr, Zn, Cu和Ni的B1, B2, B3态含量增加3-20倍.11m·s-1风浪与7m·s-1风浪相比,Co, Cr和Ni的B1态含量分别增加31.1%-76.8%,Mn, Zn和Cu分别减少22.1%-38.6%; Cr,Zn和Ni的B2态含量增加12.1%-50.2%, Mn减少65.6%, Co和Cu的含量相当; Co和Ni的B3态含量增加15.4%-10.3%,Cr,Mn,Zn和Cu略微减少.水体中的金属主要以Fe-Mn氧化物结合态存在,且金属的三态比例随风浪的变化不明显. Mn的生物有效性最高,Zn,Cu和Ni次之,毒性较大的Pb和Cr的生物有效性较低.Al, Fe和Pb的Fe-Mn氧化物结合态比例非常高,约有74.56%-100%. Co,Cr和Ni的有机结合态比例较高,且Co和 Ni的三态比例比较均一,Cu的B3态较低. 相似文献
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The nitrogen (N) distribution and cycling of atmosphere-plant-soil system in the typical meadow Calamagrostis angustifolia wetland (TMCW) and marsh meadow Calamagrostis angustifolia wetland (MMCW) in the Sanjiang plain were studied by a compartment model. The results showed that the N wet deposition amount was 0.757 gN/(m2·a), and total inorganic N (TIN) was the main body (0.640 gN/(m2·a)). The ammonia volatilization amounts of TMCW and MMCW soils in growing season were 0.635 and 0.687 gN/m2, and the denitrification gaseous lost amounts were 0.617 and 0.405 gN/m2, respectively. In plant subsystem, the N was mainly stored in root and litter. Soil organic N was the main N storage of the two plant-soil systems and the proportions of it were 93.98% and 92.16%, respectively. The calculation results of N turnovers among compartments of TMCW and MMCW showed that the uptake amounts of root were 23.02 and 28.18 gN/(m2·a) and the values of aboveground were 11.31 and 6.08 gN/(m2·a), the re-translocation amounts from aboveground to root were 5.96 and 2.70 gN/(m2·a), the translocation amounts from aboveground living body to litter were 5.35 and 3.38 gN/(m2·a), the translocation amounts from litter to soil were larger than 1.55 and 3.01 gN/(m2·a), the translocation amounts from root to soil were 14.90 and 13.17 gN/(m2·a), and the soil (0-15cm) N net mineralization amounts were 1.94 and 0.55 gN/(m2·a), respectively. The study of N balance indicated that the two plant-soil systems might be situated in the status of lacking N, and the status might induce the degradation of C. angustifolia wetland. 相似文献
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Specific ecogenetic features of solods in the forest-steppe zone has been studied, and the role of biotic and abiotic factors of soil formation has been estimated. Differentiation of soil horizons with respect to the physical clay fraction accounts for specific features of their moistening, which is reflected in the ratio of strongly and weakly crystallized forms of iron. Periodic changes in redox conditions results in iron segregation, and a high content of fulvic acids accounts for its eluvial migration. These processes are controlled by soil geochemical barriers. 相似文献
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The concept of sustainability transitions has become increasingly prominent in academic and policy discourses during recent decades, but the importance of the link between knowledge-producing epistemic practices and urban governance has been underappreciated in this discourse. Based on a case study of cycling in Copenhagen between 1900 and 2015, and drawing upon a governmentality-inspired analytical framework, this research demonstrates that transformative governance may be initiated by epistemic practices that render urban systems visible in other ways. Urban cycling has been reconstructed over time in Copenhagen as a traffic safety ‘problem’, a component of the experiential and liveable city, and a health-producing (and hence economically valuable) regional transport mode. The research findings emphasise that epistemic practices can provide a powerful stimulus for creating changes in urban governance. The results also provide support for initiatives to broaden the terms of academic debate on sustainability transitions. 相似文献
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Andreas Behrends Sonja Riediger Sascha Grube Burkhard Poeggeler Chandana Haldar Rüdiger Hardeland 《Journal of environmental science and health. Part. B》2013,48(6):599-606
The redox-active quinalphos main metabolite, 2-hydroxyquinoxaline, is particularly effective under excitation by light. We have studied the photocatalytic destruction of melatonin and its precursors, because the cytoprotective indoleamine has been detected in high quantities in mammalian skin. In photooxidation reactions, in which melatonin, N-acetylserotonin and serotonin are destroyed by 2-hydroxyquinoxaline, the photocatalyst is virtually not consumed. Rates of melatonin and serotonin destruction are not changed by the singlet oxygen quencher 1,4-diazabicyclo-(2,2,2)-octane, indicating that this oxygen species is not involved in the primary reactions, so that the persistence of 2-hydroxyquinoxaline has to be explained by redox cycling. This should imply formation of an organic radical, presumably the quinoxaline-2-oxyl radical, from which 2-hydroxyquinoxaline is regenerated by electron abstraction from indolic radical scavengers. Electron donation by 2-hydroxyquinoxaline is demonstrated by reduction of the 2,2′-azino-bis-(3-ethylbenzthiazolinyl-6-sulfonic acid) cation radical under ultrasound excitation. The compound 2-hydroxyquinoxaline interacts with the specific superoxide anion scavenger Tiron. Formation of oligomeric products from melatonin and serotonin is strongly inhibited by sodium dithionite. Products from photocatalytic indolamine conversion are predominantly dimers and oligomers. No kynuramines were detected in the case of serotonin oxidation, and melatonin's otherwise prevailing oxidation product N 1-acetyl-N 2-formyl-5-methoxykynuramine, another cytoprotective metabolite, is only formed in relatively small quantities. The proportion between products from melatonin is changed by 1,4-diazabicyclo-(2,2,2)-octane: singlet oxygen, also formed under the influence of excited 2-hydroxyquinoxaline, only affects secondary reactions. 相似文献