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471.
硫酸盐还原菌对碱性和酸性农田土壤中重金属的钝化效果及其作用机制 总被引:2,自引:1,他引:1
通过土壤培养实验考察了硫酸盐还原菌(SRB)包括希瓦氏菌、梭状芽胞杆菌和两者混合菌对碱性和酸性农田土中有效态重金属(Cd、Pb、Cu和Zn)的钝化效果及其作用机制.结果表明,在相同接菌量下,希瓦氏菌处理组对碱性土中有效态重金属的钝化效果优于梭状芽胞杆菌和两者混合菌的处理组;而不同种类的SRB对酸性土中有效态重金属的钝化效果无显著差异.培养第20 d后土壤中有效态重金属的钝化率不再显著变化.SRB处理对碱性土中有效态重金属的钝化率可达80%以上,而对酸性土中有效态重金属的钝化率低于40%.在碱性土中,SRB能够有效还原SO42-,并且提高土壤pH值,使S2-可与重金属紧密结合,显著提高有效态重金属钝化率.尽管SRB使酸性土壤pH值升高,但土壤仍然呈酸性使SO42-还原受到抑制,不利于有效态重金属的钝化.总体来看,SRB适用于碱性和酸性土壤的重金属污染治理,但与酸性土壤相比,SRB对碱性土壤中有效态重金属的钝化效果更好. 相似文献
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B. Yang W.S. Shu Z.H. Ye R.L. Qiu G.X. Cui 《Environmental pollution (Barking, Essex : 1987)》2010,158(2):551-408
It is observed that ramie (Boehmeria nivea), an economic fiber crop, can establish and colonize metal-contaminated sites in China. Metal tolerance and accumulation by ramie originating from 13 metal-contaminated and 4 “clean” sites in China were compared under field and hydroponic conditions. All selected populations and germplasms displayed good growth performance under diverse metal-contaminated habitats; while growth responses, metal accumulation and tolerance were similar among the 8 populations and 2 germplasms when exposed to solutions containing elevated As, Cd, Pb, or Zn in the laboratory. These revealed that ramie possesses a certain degree of constitutional metal tolerance. To our knowledge, this is the first report of constitutional metal tolerance possessed by a fiber crop. Ramie can be considered as a good candidate for both fiber production and phytoremediation of sites contaminated by multi-metals, as it accumulates relative low metal concentrations, but possesses both high biomass and high economic value. 相似文献
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R. S. Maharia R. K. Dutta R. Acharya A. V. R. Reddy 《Journal of environmental science and health. Part. B》2013,48(2):174-181
Heavy metal distribution in medicinal plants is gaining importance not only as an alternative medicine, but also for possible concern due to effects of metal toxicity. The present study has been focused on emphasizing the heavy metal status and bioaccumulation factors of V, Mn, Fe, Co, Cu, Zn, Se (essential metals) and Cr, Ni, Cd, As and Pb (potentially toxic metals) in medicinal plants grown under two different environmental conditions e.g., near to Khetri copper mine and those in fertile soils of Haridwar, both in India, using Instrumental Neutron Activation Analysis (relative method) and Atomic Absorption Spectrometry. The copper levels in the medicinal plants from Khetri were found to be 3-4 folds higher (31.6–76.5 mg kg?1) than those from Haridwar samples (7.40–15.3 mg kg?1), which is correlated with very high copper levels (763 mg kg?1) in Khetri soil. Among various heavy metals, Cr (2.60–5.92 mg kg?1), Cd (1.47–2.97 mg kg?1) and Pb (3.97–6.63 mg kg?1) are also higher in concentration in the medicinal plants from Khetri. The essential metals like Mn (36.4–69.3 mg kg?1), Fe (192–601 mg kg?1), Zn (24.9–49.9 mg kg?1) and Se (0.13–0.91 mg kg?1) and potentially toxic metals like Ni (3.09–9.01 mg kg?1) and As (0.41–2.09 mg kg?1) did not show much variations in concentration in the medicinal plants from both Khetri and Haridwar. The medicinal plants from Khetri, e.g., Ocimum sanctum, Cassia fistula, Withania somnifera and Azadirachta Indica were found rich in Ca and Mg contents while Aloe barbadensis showed moderately high Ca and Mg. Higher levels of Ca-Mg were found to correlate with Zn (except Azadirachta Indica). The bioaccumulation factors (BAFS) of the heavy metals were estimated to understand the soil-to-plant transfer pattern of the heavy metals. Significantly lower BAF values of Cu and Cr were found in the medicinal plants from Khetri, indicating majority fraction of these metals are precipitated and were immobilized species unsuitable for plant uptake. Overall, Withania somnifera (Ashwagandha) showed very high metal bioaccumulation. 相似文献
478.
The adsorption of some heavy metals onto the walls of harvested, washed, and dried non-living biomass cells of different Pseudomonas strains was studied at optimum experimental conditions using a simplified single component system. The Langmuir adsorption model was found to be a suitable approach to describe the system via multi-step processes. Isotherms measured at 30.0°C and pH 5.5 with [M]total = 10-100 mM for tight, reversible Cr6+(aq), Ni2+(aq), Cu2+(aq) and Cd2+(aq) binding by the cell walls of the investigated biomass fit the Langmuir model and give the pH-independent stoichiometric site capacities νi and equilibrium constants Ki for metal binding at specific biomass sites i = A, B, C, and D. Tight binding sites A, B, and D of the non-living biomass are occupied by CrVI, sites A and C by NiII, sites A and D by CdII, and only site B by CuII. It is concluded that νi is a stoichiometric parameter that is independent of the magnitude of Ki for binding site i and that the studied heavy metals selectively and tightly bind at different biomass sites. 相似文献
479.
市场转型对中国环境治理结构的影响——国家污染物减排指标的分配机制研究 总被引:1,自引:0,他引:1
朱旭峰 《中国人口.资源与环境》2008,18(6)
国家统计局数据显示,2006年我国节能减排任务均远未实现国家"十一五"规划开局之年的目标,特别是主要污染物排放总量不降反升.本文在分析了中国环境治理体系和国家"十一五"规划主要污染物减排指标分配机制的基础上,研究了市场转型对中国环境治理结构的影响.中国的市场转型可以抽象为以"分权让利"、"市场化"和"工业化"为主要特征的结构演进过程.文中提出,中国市场转型过程对环境治理结构造成了重大影响,而环境治理的各项措施反过来也应与市场转型相适应.当前中国主要污染物减排指标没有实现达标的重要原因是国家污染物减排指标的分配机制无法适应我国市场转型的要求.为此,本文提出一系列国家主要污染物减排指标分配机制的政策建议. 相似文献
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Michael A. Smith Ingvar L. Larsen Audeen W. Fentiman 《Journal of environmental radioactivity》2008,99(10):1611
Vertical distributions of 60Co are determined in soil cores obtained from a 10-ha grassland, where anaerobically digested sludge was applied by surface spraying from 1986 to 1995 on the U.S. Department of Energy's Oak Ridge Reservation. These results, along with historical application records, are used to estimate vertical-migration rates and perform a mass balance. The presence of 60Co results solely from the sludge-application process. Soil, vegetation, and surface-water samples were collected. Eleven soil cores were sectioned into 3-cm increments and analyzed by gamma-ray spectrometry. No 60Co was detected in the vegetation or water samples. The downward migration rate of 60Co in the upper 15 cm of soil ranged from 0.50 to 0.73 cm/yr. About 98%, 0.020 ± 0.011 Bq/cm2, of 60Co remained in the upper 15 cm of soil, which compared favorably with the expected 60Co activity based on historical records of 0.019 ± 0.010 Bq/cm2. 相似文献