To complement information of heavy metals＇ distribution, chemical speciation, activity and environmental risks in agricultural soils surrounding tailings, a total of 16 samples obtained from the 4 # railings site of ...To complement information of heavy metals＇ distribution, chemical speciation, activity and environmental risks in agricultural soils surrounding tailings, a total of 16 samples obtained from the 4 # railings site of Dexing copper mine of China were investigated. The total concentrations of heavy metals Zn, Fe, Cu, Pb, Cd, Cr, Hg, As, Mn, Ag, Co, and Ni were determined by inductively coupled plasma-atomic emission spectrometry. Chemical speciations of Cu, Cd, and Zn were investigated with the procedures recommended by Tessier（1979）. Two different assessment approaches （GB 15618- 1995 and risk assessment code, RAC ） were employed to estimate heavy metals＇ environmental risks. Results indicated that heavy metals, especially Cu and Cd were in high levels of accumulation in these samples. Chemical speciation analysis results revealed that Cu was mainly in organic matter bound fraction （ORG） and residual fraction （ RES）, and Cd was predominantly in exchangeable fraction （EXC）, while Zn appeared mainly with the RES fraction. Environmental risk analysis results showed that Cd was in ＂heavy＂ pollution level （ classification m ） in almost all samples, which may exert ＂high＂ or ＂very high＂ environmental risks. Whereas, for Cu, one fourth samples showed ＂heavy＂ pollution level, but were located in ＂low＂ or ＂medium＂ environmental risk ranks. For Zn, many samples were grouped in ＂light＂ pollution level （ classification II ）, but were related to ＂ medium＂ and ＂ high＂ environmental risk ranks. These results indicated heavy pollution and high environmental risk of Cd in soils surrounding the 4# tailings site, which should be paid more attention to. Meanwhile, for Cu and Zn, the contrary results obtained by different environmental risk assessment approaches, may suggest that a more scientific, adequate environmental risk assessment criterion should consider both total content and chemical speciation activity of heavy metals.展开更多
Municipal solid waste incineration(MSWI)fly ash poses severe environmental risks because of the high potential of fly ash for heavy metal leaching.In this study,the leaching of fly ash by acetic acid was investigated....Municipal solid waste incineration(MSWI)fly ash poses severe environmental risks because of the high potential of fly ash for heavy metal leaching.In this study,the leaching of fly ash by acetic acid was investigated.Key parameters,including time,acetic acid concentration,and fly ash type,were examined for their influence on calcium and heavy metal leaching.The physical and chemical changes in fly ash before and after leaching were analysed via the X-ray fluorescence(XRF),X-ray diffraction(XRD),and heavy metal leaching methods.The results showed that acetic acid effectively leached metals from different types of fly ash,as determined by the risk assessment code(RAC)and risk index(RI),and leaching with 0.25 mol/L acetic acid resulted in the lowest environmental hazard for fly ash.Moreover,adjusting the pH to below 11 during acid treatment,followed by washing with water,substantially reduced heavy metal leaching and increased the potential for safe resource recovery.A life cycle assessment(LCA)using the CML-2001 method revealed that the marine aquatic ecotoxicity potential had the largest environmental impact,accounting for 39.56%of the total index.These findings suggest that acetic acid leaching followed by water washing,improves the potential for repurposing of fly ash as a construction material.展开更多
基金National Natural Science Foundation of China (No. 41073060)Shanghai Leading Academic Discipline Project,China (No.B604)the State Environmental Protection Engineering Center for Pollution Treatment and Control in Textile Industry,China
文摘To complement information of heavy metals＇ distribution, chemical speciation, activity and environmental risks in agricultural soils surrounding tailings, a total of 16 samples obtained from the 4 # railings site of Dexing copper mine of China were investigated. The total concentrations of heavy metals Zn, Fe, Cu, Pb, Cd, Cr, Hg, As, Mn, Ag, Co, and Ni were determined by inductively coupled plasma-atomic emission spectrometry. Chemical speciations of Cu, Cd, and Zn were investigated with the procedures recommended by Tessier（1979）. Two different assessment approaches （GB 15618- 1995 and risk assessment code, RAC ） were employed to estimate heavy metals＇ environmental risks. Results indicated that heavy metals, especially Cu and Cd were in high levels of accumulation in these samples. Chemical speciation analysis results revealed that Cu was mainly in organic matter bound fraction （ORG） and residual fraction （ RES）, and Cd was predominantly in exchangeable fraction （EXC）, while Zn appeared mainly with the RES fraction. Environmental risk analysis results showed that Cd was in ＂heavy＂ pollution level （ classification m ） in almost all samples, which may exert ＂high＂ or ＂very high＂ environmental risks. Whereas, for Cu, one fourth samples showed ＂heavy＂ pollution level, but were located in ＂low＂ or ＂medium＂ environmental risk ranks. For Zn, many samples were grouped in ＂light＂ pollution level （ classification II ）, but were related to ＂ medium＂ and ＂ high＂ environmental risk ranks. These results indicated heavy pollution and high environmental risk of Cd in soils surrounding the 4# tailings site, which should be paid more attention to. Meanwhile, for Cu and Zn, the contrary results obtained by different environmental risk assessment approaches, may suggest that a more scientific, adequate environmental risk assessment criterion should consider both total content and chemical speciation activity of heavy metals.
基金supported by the“Innovation Yongjiang 2035”Key R&D Program of Ningbo(No.2024Z248)the“Pioneer”and“Leading Goose”R&D Program of Zhejiang(No.2022C03056)the Baima Lake Laboratory Joint Funds of Zhejiang Provincial Natural Science Foundation of China(No.BMHZ24E020004).
文摘Municipal solid waste incineration(MSWI)fly ash poses severe environmental risks because of the high potential of fly ash for heavy metal leaching.In this study,the leaching of fly ash by acetic acid was investigated.Key parameters,including time,acetic acid concentration,and fly ash type,were examined for their influence on calcium and heavy metal leaching.The physical and chemical changes in fly ash before and after leaching were analysed via the X-ray fluorescence(XRF),X-ray diffraction(XRD),and heavy metal leaching methods.The results showed that acetic acid effectively leached metals from different types of fly ash,as determined by the risk assessment code(RAC)and risk index(RI),and leaching with 0.25 mol/L acetic acid resulted in the lowest environmental hazard for fly ash.Moreover,adjusting the pH to below 11 during acid treatment,followed by washing with water,substantially reduced heavy metal leaching and increased the potential for safe resource recovery.A life cycle assessment(LCA)using the CML-2001 method revealed that the marine aquatic ecotoxicity potential had the largest environmental impact,accounting for 39.56%of the total index.These findings suggest that acetic acid leaching followed by water washing,improves the potential for repurposing of fly ash as a construction material.
