The present study is conducted in the scenario of the tannery waste hazards in Kasur district of Pakistan where the tannery industry is considered as major cause of groundwater quality deterioration, Area focused in t...The present study is conducted in the scenario of the tannery waste hazards in Kasur district of Pakistan where the tannery industry is considered as major cause of groundwater quality deterioration, Area focused in this research constitutes the surroundings of the effluent carrying drains near tannery units. This study includes soil explorations, groundwater monitoring and wastewater analysis in the research area so as to find out the contamination extent of chromium in subsurface. Initial groundwater monitoring exhibited chromium concentrations as high as 90 mg/L in the tannery area. Even groundwater sampling from monitoring wells installed in the adjacent areas of effluent carrying drains, showed concentrations up to 10.4 mg/L. Wastewater analysis of all the drains in the research area has evidenced potential risk of contaminant seepage into soil and groundwater as level of chromium in wastewater samples has reported to be immensely high and varies from 68 mg/L to 2,152 mg/L. However the 30 soil samples collected from two soil bores did not show any significant results as the maximum values obtained for hexavalent chromium for leaching and retained in soil are 0.02 mg/L and 8.1 mg/kg, respectively. These low concentrations of soil samples suggest that the soil contamination may not be a main environmental issue in the areas adjacent to the effluent carrying drains, The research concludes as possibility of direct interference of the tannery wastewater with groundwater through damaged structures and sewers.展开更多
Due to improper tannery wastewater management in district Kasur Pakistan, groundwater has been reported to be highly contaminated. It was aimed to find out the extent up to which subsurface has contaminated due to chr...Due to improper tannery wastewater management in district Kasur Pakistan, groundwater has been reported to be highly contaminated. It was aimed to find out the extent up to which subsurface has contaminated due to chromium in areas adjacent to the tannery units. Eight （8） soil bores were conducted up to the depth of 30.5 meters and soil samples were tested for total and hexavalent chromium concentrations retained in soil by aqua regia digestion at the every depth of 1.5 meters. Afterwards monitoring wells were installed in these eight （8） bores so as to monitor chromium concentrations in the groundwater on monthly basis. The main source of contamination was considered to be the four （4） drains carrying tanneries effluent therefore samples were collected from these drains so as to observe seasonal variation in chromium concentration.展开更多
To evaluate the metal chromium (Cr) contamination of soil at a chromium-containing slag site by ferrochromium production, the contaminated sites, under slag heap, in the vicinity of slag heap and arable soils near the...To evaluate the metal chromium (Cr) contamination of soil at a chromium-containing slag site by ferrochromium production, the contaminated sites, under slag heap, in the vicinity of slag heap and arable soils near the outlet of sewer channel, and unpolluted site 5 km away from one ferroalloy plant in Hunan Province, China, were selected. The concentrations of total Cr and water soluble Cr in bulk soil samples and profile depth samples were determined. The results show that the soils in the vicinity of slag heap have the highest total Cr content followed by the soils under the slag heap and near the outlet of sewer channel of the factory. The mean concentrations of total Cr in the top soils at above three contaminated locations exceed the critical level of Secondary Environmental Quality Standard for Soil in China by 3.5, 5.4 and 1.8 times. In most Cr polluted soils, total Cr has a relative accumulation in soil depth of 40-60 cm, but this trend is not found in unpolluted soils. The average concentrations of water soluble Cr (Ⅵ) in top soils under slag heap and in the vicinity of slag heap are 176.9 times and 52.7 times higher than that in the uncontaminated soils, respectively. However, water soluble Cr (Ⅵ) contents in soils near sewer channel are all low and the values are close to that in the uncontaminated soils. Although water soluble Cr (Ⅵ) content in soil profiles decreases with soil depths, it in soils under slag heap maintains a high level even at a depth of 100-150 cm. The results imply that the transportation of Cr (Ⅵ) can result in a potential risk of groundwater system in this area.展开更多
Cr(Ⅵ)-amended soil was inoculated with Cr(Ⅵ)-reducing strain,Bacillus sp.XW-4 and incubated at 28 ℃in an incubator. Cr(Ⅵ)reduction,available Cr and Cr fractionin soils were studied.The results show that addition o...Cr(Ⅵ)-amended soil was inoculated with Cr(Ⅵ)-reducing strain,Bacillus sp.XW-4 and incubated at 28 ℃in an incubator. Cr(Ⅵ)reduction,available Cr and Cr fractionin soils were studied.The results show that addition of Bacillus sp.XW-4 can promote Cr(Ⅵ)reduction,but inoculation of this strain has a negative effect on the decrease of available Cr content in soil.In controls (without this strain)amended with 100 and 200 mg/kg of Cr(Ⅵ),Cr(Ⅵ)contents decrease to about 41 and 92 mg/kg respectively after incubation of 4 d,while in soil inoculated with XW-4,Cr(Ⅵ)contents decrease to about 18 and 60 mg/kg,respectively.The content of available Cr in soils with inoculation of XW-4 is higher than that in controls.Chromium is partitioned into water soluble Cr,exchangeable Cr,precipitated Cr,Cr bound to organics and residual Cr.The highest content of Cr is observed in residual form and water soluble Cr is not detected for all treatments after 42 d,but the soils inoculated with Bacillus sp.XW-4 contain higher content of exchangeable Cr and lower content of precipitated Cr than the soil without the inoculum.Inoculation of Bacillus sp.XW-4 can increase chromium activity in soils.展开更多
Kinetic studies of the extraction of chromium（Ⅵ）[Cr（Ⅵ）] from the hydrochloric acid solution with tri-n-octylamine（N235） have been made by a Lewis cell. The influences of various kinetic parameters, such as sti...Kinetic studies of the extraction of chromium（Ⅵ）[Cr（Ⅵ）] from the hydrochloric acid solution with tri-n-octylamine（N235） have been made by a Lewis cell. The influences of various kinetic parameters, such as stirring rate, interfacial area, temperature, N235 and initial Cr（Ⅵ） concentrations were evaluated. The rate equations for the extraction of Cr（Ⅵ） by N235 were obtained on the basis of the slope analysis data. The results indicated that the reaction rate of Cr（Ⅵ） increased with increasing of the stirring rate and interfacial area until that a "plateau" was observed with increasing stirring rate. The activation energies of Cr（Ⅵ） extraction by N235 dissolved in diluents were calculated. Kinetics analysis proved that the mass transfer was controlled mainly by diffusion and the chemical reaction between Cr（Ⅵ） anions and N235 could be achieved at the liquid-liquid interface. On the basis of the relation between ln[Cr（Ⅵ）] and ln R0 or ln[N235] and ln R0, the rate equations can be obtained. This research provides a proof-in-concept analysis for kinetic mechanism.展开更多
The adsorption of Cu(Ⅱ)and Cr(Ⅵ)on diaspore was studied with the help of X-ray diffraction analysis,BET measurement,zeta potential measurement and atomic adsorption spectrometry.The adsorption equilibrium almost rea...The adsorption of Cu(Ⅱ)and Cr(Ⅵ)on diaspore was studied with the help of X-ray diffraction analysis,BET measurement,zeta potential measurement and atomic adsorption spectrometry.The adsorption equilibrium almost reaches within 60 min.The adsorption isotherms of Cu(Ⅱ)and Cr(Ⅵ)could be well described by the Langmuir equation.The adsorption capacities of Cu(Ⅱ)and Cr(Ⅵ)are 1.944 and 1.292 mg/g,respectively.The adsorption percentage of Cr(Ⅱ)increases with the increment of solution pH,but the adsorption percentage of Cr(Ⅵ)decreases.This could be explained by zeta potential theoretical and electrostatic attraction between metal ions and diaspore surface.展开更多
文摘The present study is conducted in the scenario of the tannery waste hazards in Kasur district of Pakistan where the tannery industry is considered as major cause of groundwater quality deterioration, Area focused in this research constitutes the surroundings of the effluent carrying drains near tannery units. This study includes soil explorations, groundwater monitoring and wastewater analysis in the research area so as to find out the contamination extent of chromium in subsurface. Initial groundwater monitoring exhibited chromium concentrations as high as 90 mg/L in the tannery area. Even groundwater sampling from monitoring wells installed in the adjacent areas of effluent carrying drains, showed concentrations up to 10.4 mg/L. Wastewater analysis of all the drains in the research area has evidenced potential risk of contaminant seepage into soil and groundwater as level of chromium in wastewater samples has reported to be immensely high and varies from 68 mg/L to 2,152 mg/L. However the 30 soil samples collected from two soil bores did not show any significant results as the maximum values obtained for hexavalent chromium for leaching and retained in soil are 0.02 mg/L and 8.1 mg/kg, respectively. These low concentrations of soil samples suggest that the soil contamination may not be a main environmental issue in the areas adjacent to the effluent carrying drains, The research concludes as possibility of direct interference of the tannery wastewater with groundwater through damaged structures and sewers.
文摘Due to improper tannery wastewater management in district Kasur Pakistan, groundwater has been reported to be highly contaminated. It was aimed to find out the extent up to which subsurface has contaminated due to chromium in areas adjacent to the tannery units. Eight （8） soil bores were conducted up to the depth of 30.5 meters and soil samples were tested for total and hexavalent chromium concentrations retained in soil by aqua regia digestion at the every depth of 1.5 meters. Afterwards monitoring wells were installed in these eight （8） bores so as to monitor chromium concentrations in the groundwater on monthly basis. The main source of contamination was considered to be the four （4） drains carrying tanneries effluent therefore samples were collected from these drains so as to observe seasonal variation in chromium concentration.
基金Project(k0802144-31) supported by the Program of Science and Technology of Changsha, ChinaProjects(2006AA062374, 2007AA021304) supported by the National Hi-tech Research and Development Program of China
文摘To evaluate the metal chromium (Cr) contamination of soil at a chromium-containing slag site by ferrochromium production, the contaminated sites, under slag heap, in the vicinity of slag heap and arable soils near the outlet of sewer channel, and unpolluted site 5 km away from one ferroalloy plant in Hunan Province, China, were selected. The concentrations of total Cr and water soluble Cr in bulk soil samples and profile depth samples were determined. The results show that the soils in the vicinity of slag heap have the highest total Cr content followed by the soils under the slag heap and near the outlet of sewer channel of the factory. The mean concentrations of total Cr in the top soils at above three contaminated locations exceed the critical level of Secondary Environmental Quality Standard for Soil in China by 3.5, 5.4 and 1.8 times. In most Cr polluted soils, total Cr has a relative accumulation in soil depth of 40-60 cm, but this trend is not found in unpolluted soils. The average concentrations of water soluble Cr (Ⅵ) in top soils under slag heap and in the vicinity of slag heap are 176.9 times and 52.7 times higher than that in the uncontaminated soils, respectively. However, water soluble Cr (Ⅵ) contents in soils near sewer channel are all low and the values are close to that in the uncontaminated soils. Although water soluble Cr (Ⅵ) content in soil profiles decreases with soil depths, it in soils under slag heap maintains a high level even at a depth of 100-150 cm. The results imply that the transportation of Cr (Ⅵ) can result in a potential risk of groundwater system in this area.
文摘为定量分析土壤不同粒级中Cr(Ⅵ)的健康风险,将铬污染土壤筛分为粗砂(500~1000μm)、中砂(250~500μm)、细砂(100~250μm)、粗粉砂(50~100μm)、粉砂及以下(0~50μm),利用激光粒度分析仪、积累因子法(accumulation factors,AF)及基于生理的提取实验(physiologically based extraction test,PBET)研究不同粒级质量分布、Cr(Ⅵ)分布特性及Cr(Ⅵ)生物可给性,并采用美国环境保护局(United States Environmental Protection Agency,US EPA)推荐的暴露模型评价Cr(Ⅵ)通过经口摄入途径引起的健康风险。结果表明,土壤不同粒级组分间Cr(Ⅵ)积累因子分布与Cr(Ⅵ)含量分布规律一致,碱性土壤中Cr(Ⅵ)倾向于在粗颗粒内积累;考虑生物可给性的情况下,Cr(Ⅵ)产生的健康风险下降43.65%~99.19%;细砂组分对Cr(Ⅵ)经口摄入的健康风险贡献最大,为48%~78%,说明粒级质量占比和生物可给性越高,其对健康风险的贡献越大。本研究量化了粒级质量分布对健康风险贡献的大小,这有利于识别影响健康风险的主要粒级组分,提高铬污染土壤健康风险评估的可靠性。
基金Project(20050532009)supported by the Doctoral Foundation of Ministry of Education of ChinaProject supported by Program for Changjiang Scholars and Innovative Research Team in University
文摘Cr(Ⅵ)-amended soil was inoculated with Cr(Ⅵ)-reducing strain,Bacillus sp.XW-4 and incubated at 28 ℃in an incubator. Cr(Ⅵ)reduction,available Cr and Cr fractionin soils were studied.The results show that addition of Bacillus sp.XW-4 can promote Cr(Ⅵ)reduction,but inoculation of this strain has a negative effect on the decrease of available Cr content in soil.In controls (without this strain)amended with 100 and 200 mg/kg of Cr(Ⅵ),Cr(Ⅵ)contents decrease to about 41 and 92 mg/kg respectively after incubation of 4 d,while in soil inoculated with XW-4,Cr(Ⅵ)contents decrease to about 18 and 60 mg/kg,respectively.The content of available Cr in soils with inoculation of XW-4 is higher than that in controls.Chromium is partitioned into water soluble Cr,exchangeable Cr,precipitated Cr,Cr bound to organics and residual Cr.The highest content of Cr is observed in residual form and water soluble Cr is not detected for all treatments after 42 d,but the soils inoculated with Bacillus sp.XW-4 contain higher content of exchangeable Cr and lower content of precipitated Cr than the soil without the inoculum.Inoculation of Bacillus sp.XW-4 can increase chromium activity in soils.
基金Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.18KJD610001)Doctor of Philosophy(PhD)Start-up Foundation of Changzhou Vocational Institute of Engineering(No.11130900117002)+1 种基金Jiangsu Students’Platform for Innovation and Entrepreneurship Training Program,China(No.201813102026H)Qing-Lan Project of Jiangsu Province,China(No.2018-12)
文摘Kinetic studies of the extraction of chromium（Ⅵ）[Cr（Ⅵ）] from the hydrochloric acid solution with tri-n-octylamine（N235） have been made by a Lewis cell. The influences of various kinetic parameters, such as stirring rate, interfacial area, temperature, N235 and initial Cr（Ⅵ） concentrations were evaluated. The rate equations for the extraction of Cr（Ⅵ） by N235 were obtained on the basis of the slope analysis data. The results indicated that the reaction rate of Cr（Ⅵ） increased with increasing of the stirring rate and interfacial area until that a "plateau" was observed with increasing stirring rate. The activation energies of Cr（Ⅵ） extraction by N235 dissolved in diluents were calculated. Kinetics analysis proved that the mass transfer was controlled mainly by diffusion and the chemical reaction between Cr（Ⅵ） anions and N235 could be achieved at the liquid-liquid interface. On the basis of the relation between ln[Cr（Ⅵ）] and ln R0 or ln[N235] and ln R0, the rate equations can be obtained. This research provides a proof-in-concept analysis for kinetic mechanism.
基金Project(2005CB623701)supported by the Major State Basic Research Development Program of China
文摘The adsorption of Cu(Ⅱ)and Cr(Ⅵ)on diaspore was studied with the help of X-ray diffraction analysis,BET measurement,zeta potential measurement and atomic adsorption spectrometry.The adsorption equilibrium almost reaches within 60 min.The adsorption isotherms of Cu(Ⅱ)and Cr(Ⅵ)could be well described by the Langmuir equation.The adsorption capacities of Cu(Ⅱ)and Cr(Ⅵ)are 1.944 and 1.292 mg/g,respectively.The adsorption percentage of Cr(Ⅱ)increases with the increment of solution pH,but the adsorption percentage of Cr(Ⅵ)decreases.This could be explained by zeta potential theoretical and electrostatic attraction between metal ions and diaspore surface.
