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291.
印染污泥中重金属形态分析及生物有效性   总被引:7,自引:2,他引:5  
选取上海某印染厂的印染废水处理后的活性污泥样品,通过盆栽土培试验,用黑麦草对印染污泥进行修复,运用Tessier A连续提取法研究修复后黑麦草根际和非根际印染污泥中铅、铜、镍、锌、镉5种重金属形态的变化,以及重金属的生物有效性与植物中有效态含量之间的关系。结果表明,栽培后根际与非根际环境中各重金属元素具有典型的形态分布特征:铅主要以离子交换态和残渣态存在;铜主要以碳酸盐结合态和残渣态存在;镍由紧结合态(铁锰氧化物结合态+有机结合态)向离子交换态转移;锌的有机结合态和碳酸盐结合态有所增加;镉主要以离子交换态和铁锰氧化物结合态为主,说明镉元素较活泼,具有潜在的环境影响能力,应该给予更多的关注。印染污泥中重金属的生物有效性与重金属元素的性质有关,铜、锌的生物有效性较高,其次是铅,最低是镍、镉。  相似文献   
292.
南海湖沉积物中Hg的形态分布特征   总被引:2,自引:0,他引:2  
以包头市南海湖为研究对象,采用连续化学提取法,系统开展了沉积物中Hg的形态分布研究。结果表明,表层沉积物中Hg含量的水平分布总体呈现湖心区低,西南和东北部湖区高的趋势。腐殖酸结合态为表层沉积物中Hg的主导形态,次为交换态和水溶态。表层沉积物中生物有效态Hg的含量甚高,占总汞的76%~94%,对整个生态系统具有潜在危害性。沉积柱芯中总Hg表现为表层富集并随深度增加而降低的变化趋势。B、F站位柱状沉积物中腐殖酸结合态Hg随深度有规律的递减,H站位20 cm以上Hg的主导形态为腐殖酸结合态,残渣态次之;20~30 cm的主导形态则为残渣态及可交换态。  相似文献   
293.
Vanadium is a trace element, which may be biologically beneficial and possibly essential but certainly harmful to human beings and some living organisms if excessive. After over 40 years of development, the mining industry has caused serious environmental problems in the Panzhihua mining area. Vanadium is significantly accu-mulated in the soil of the Panzhihua area. Human activities have intensified the pollution and release of vanadium and caused serious damages to the ecological system there. In the past few years, the authors have made investiga-tions into and assessments on the geochemical distribution, chemical speciation, adsorption characteristics and transfer behavior of vanadium in the topsoil in the Panzhihua mining area. The results showed that: (1) the difference in the contents of vanadium in soil between premonsoon and monsoon is insignificant; (2) the adsorption isotherms of vanadium on soil in the Panzhihua mining area ate well described by the Langmuir type; (3) the transfer ability of vanadium in soil is interrelated to soil properties; and (4) the chemical speciation of vanadium shows an order of insoluble residue > oxidizable=reducible > soluble component. According to the above results, some countermea-sures to control pollution of vanadium in soil should be put forward.  相似文献   
294.
我国燃煤汞沉降的数值模拟   总被引:3,自引:1,他引:2       下载免费PDF全文
利用CMAQ-Hg(Community Multi-scale Air Quality-Mercury)模式模拟了我国燃煤排放的大气汞在我国区域的沉降分布状况,其中气象模式为MM5.模式中包括了三种价态汞(气态元素汞(GEM)、气态活性汞(RGM)和颗粒汞(PHg))的气相、液相、非均相化学反应过程以及输送、干湿沉降等物理过程.中国燃煤排放的大气汞中RGM所占比例较高,约为58.4%~66.8%,这导致我国汞沉降量较大.模拟结果表明,在我国的西南地区、华东地区以及京津塘地区燃煤汞的沉降较高,在这些区域的沉降通量高达2~6μg m-2mon-1.燃煤大气汞排放形态对汞的沉降有重要影响,减少燃煤汞排放中RGM的比例能够显著降低我国区域汞的沉降通量.  相似文献   
295.
Mercury speciation was determined in rainwater from 76 storms in southeastern North Carolina between September 1, 2003 and September 30, 2005. Volume-weighted average concentrations of total Hg (THg), total dissolved Hg (TDHg), particulate Hg (Hgpart) and dissolved monomethyl Hg (MMHg) were 45.5 pM, 34.8 pM, 12.0 pM and 1.1 pM respectively. TDHg accounted for 77% of THg in precipitation which is similar to Cu but significantly higher than Cr or Fe. Concentrations of the various Hg species were very similar during summer and winter indicating that there was not a dominant seasonal influence on Hg speciation in rainwater at this location. THg, TDHg, and MMHg concentrations were also not significantly impacted by storm origin suggesting that they are relatively well mixed regionally and that air mass back trajectory is not the dominant factor controlling their concentration at this location. Concentrations of TDHg and Hgpart were inversely correlated in rainwater samples subjected to irradiation with simulated sunlight, suggesting the distribution between dissolved and particulate Hg may be controlled by photochemical transformations. Unlike TDHg and Hgpart, no significant changes in MMHg were observed upon photolysis of rainwater indicating that its distribution is not significantly driven by sunlight-mediated reactions, in contrast to what has been observed in surface waters. Results presented in this study indicate that the speciation of Hg in rainwater is dynamic and is driven by a complex combination of natural and anthropogenic processes as well as interactions with sunlight.  相似文献   
296.
黄河包头段不同粒级沉积物中重金属形态分布特征   总被引:3,自引:0,他引:3  
以黄河包头段为研究对象,探讨了该河段不同粒级沉积物中重金属的形态分布特征,并估算了各粒级沉积物对各形态重金属的贡献率。结果表明,铁锰氧化物结合态是黄河干流各粒级沉积物中Cu、Pb和Zn非稳定态的主导形态;总体上,黄河干支流沉积物中3种重金属各形态含量均随粒级增大而减小,表现明显的粒度效应;重金属形态分布的粒度效应是沉积...  相似文献   
297.
Total concentrations of chemical elements in soils may not be enough to understand the mobility and bioavailability of the elements. It is important to characterise the degree of association of chemical elements in different physical and chemical phases of soil. Another geochemical characterisation methodology is to apply sequential selective chemical extraction techniques. A seven-step sequential extraction procedure was used to investigate the mobility and retention behaviour of Al, Fe, Mn, Cu, Zn, Pb, Cr, Co, Ni, Mo, Cd, Bi, Sn, W, Ag, As and U in specific physical–chemical and mineral phases in mine tailings and soils in the surroundings of the abandoned Ervedosa mine. The soil geochemical data show anomalies associated with mineralised veins or influenced by mining. Beyond the tailings, the highest recorded concentrations for most elements are in soils situated in mineralised areas or under the influence of tailings. The application of principal components analysis allowed recognition of (a) element associations according to their geochemical behaviour and (b) distinction between samples representing local geochemical background and samples representing contamination. Some metal cations (Mn, Cd, Cu, Zn, Co, Cr, Ni) showed important enrichment in the most mobilisable and bioavailable (i.e., water-soluble and exchangeable) fractions due likely to the acidic conditions in the area. In contrast, oxy-anions such as Mo and As showed lower mobility because of adsorption to Fe oxy-hydroxides. The residual fraction comprised largest proportions of Sn and Al and to a lesser extent Zn, Pb, Ni, Cr, Bi, W, and Ag, which are also present at low concentrations in the bioavailable fractions. The elements in secondary mineral phases (mainly Fe, Mn, Cu, Zn, Cd, Pb, W, Bi, Mo, Cr, Ni, Co, As and U) as well as in organic matter and sulphides are temporarily withheld, suggesting that they may be released to the environment by changes in physico-chemical conditions.  相似文献   
298.
A specific method for the determination of bromine and iodine species in drinking water was developed by using high performance liquid chromatography‐ICP‐MS. An ICS‐A23 ion chromatography column was chosen for the separation of species, with the mobile phase being 0.03 mol l?1 ammonium carbonate at a flow rate of 0.8 ml min?1. The detection limits for BrO3?, Br?, IO3? and I? were 0.032, 0.063, 0.008 and 0.012 μg l?1, respectively. Spectroscopic interferences were only observed in blank samples and mainly resulted from the argon‐potassium polyatomic ion (40Ar39K+). However, this interference was negligible because of the elution and complete separation from that of iodinate under optimised conditions. The method developed was successfully applied to twenty‐two samples of drinking water obtained from a supermarket. Results indicated that 36.4% of the samples had BrO3? concentrations exceeding the Chinese national limit for drinking water of 10 μg l?1.  相似文献   
299.
地下水地球化学模拟   总被引:3,自引:1,他引:3  
曾溅辉 《地质论评》1993,39(6):490-496
地下水地球化学模拟是评价地下水水质,模拟水-岩相互作用,查明地下水-岩石相互作用下污染物迁移形式和变化特点,以及预测地下水化学演变的有效方法。本文概述了地下水地球化学模拟的基本理论,讨论了地下水地球化学模拟中的组分存在形式的计算,质量平衡反应模型及反应路径模拟的研究内容和方法,并指出了其存在的问题及发展方向。  相似文献   
300.
Sixty-two soil samples collected from different functional zones of Guiyang were analyzed for total concentrations and sequential extraction of Cr, Cu, Pb, Zn and Cd by ICP spectrometry. The average total concentrations ofCr, Cu, Pb, Zn and Cd in the soils of Guiyang were 92.9, 51.6, 44.1,139.3 and 0.28 mg/kg, respectively. The soils have been polluted by Cr, Cu, Pb, Zn and Cd to some extent in comparison with the background values of Guiyang. Significant differences were recognized in the concentrations of Cr, Cu, Pb, Zn and Cd in different functional zones. As for the sequential extraction, Cr, Cu and Zn were present mainly in the residual fraction, and Pb was present mainly in the oxidizable fraction. The reducible fraction of Cd accounts for 47.5%, and the residual fraction is lowest. The mobility and bioavailability of heavy metals follow the order of Cd〉Pb〉Cu〉Cr〉Zn.  相似文献   
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