The bottom ash and fly ash from the co-combustion of wood residues and peat at a bubbling fluidised bed boiler（296 MW） contained only quartz（SiO_2）, microcline（KAl Si_3O_8） and albite（NaAlSi_3O_8）. Thus, X-ray...The bottom ash and fly ash from the co-combustion of wood residues and peat at a bubbling fluidised bed boiler（296 MW） contained only quartz（SiO_2）, microcline（KAl Si_3O_8） and albite（NaAlSi_3O_8）. Thus, X-ray powder diffraction（XRD） was not useful for clarifying the difference in the release of associated heavy metals from ash matrices. In order to assess the release of heavy metals from ashes under changing environmental conditions, they were sequentially extracted and fractionated by the BCR-procedure into acid soluble/exchangeable（CH_3COOH）, reducible（NH_2OH-HCl） and oxidizable（H_2O_2/CH_3COONH_4） phases. The CH_3 COOH extractable fraction in conjunction with the total heavy metals concentrations were used to calculate the risk assessment code values for heavy metals leaching from the ash matrix. The leaching studies indicate that the heavy metals in the bottom ash and fly ash are bound to different fractions with different strengths. From the environmental and utilization perspectives, heavy metals in ashes posed different levels of environmental contamination risk. Only As in the bottom ash posed a very high risk. High risk metals were Cd in the bottom ash as well as As, Cd and Se in the fly ash.展开更多
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
Sale-leaseback is paid special focus on for its great application in China in recent years.By giving a detailed analysis,an analysis of the features of sale-leaseback and a study of the risks of it are given in this p...Sale-leaseback is paid special focus on for its great application in China in recent years.By giving a detailed analysis,an analysis of the features of sale-leaseback and a study of the risks of it are given in this paper.Then a quantitative analysis of commercial real estate sale-leaseback is carried out.The scientific theoretical analysis is provided in this paper for risk assessment in commercial real estate sale-leaseback mode in China.An effective approach is put forward for sale-leaseback project evaluation and prevention of risk.A useful means is given to supervise commerciai real estate sale-leaseback mode for relevant departments and a certain contribution is made to a further sound development of commercial real estate sale-leaseback mode.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
Fertilizers are widely applied in agricultural practice to improve crop yield and quality.However, they can also alter the behavior of soil pollutants.A field experiment was conducted on a chernozem in Heilongjiang Pr...Fertilizers are widely applied in agricultural practice to improve crop yield and quality.However, they can also alter the behavior of soil pollutants.A field experiment was conducted on a chernozem in Heilongjiang Province, China.Various proportions of inorganic nitrogen(N), phosphorus(P), and organic(manure) fertilizers were applied.Soil samples were collected four times over 2 years, and the total concentrations and speciation of chromium(Cr) and cadmium(Cd) were analyzed.Inorganic fertilizer addition had little effect on the total concentration of Cr and Cd, while organic fertilizer addition reduced the total concentrations of both Cr and Cd.Inorganic fertilizers increased the concentration of Cr in the exchangeable form, but decreased that of the residual form(P < 0.05).Addition of inorganic or organic fertilizer alone decreased concentrations of exchangeable Cd(P < 0.05), but the combination of inorganic and organic fertilizers had the opposite effect.High concentration of total Cd exceeding the upper limits of the Environmental Quality Standard for Soils proposed by the Ministry of Environmental Protection of China could result in an environmental risk, and fertilizer application could lower that risk.Results of risk assessment code calculated as the percentage of the sum of metal concentrations in the exchangeable and carbonate-associated form in total metal concentration showed that Cr and Cd risks were lowered when organic fertilizer was applied alone or in combination with inorganic fertilizers.Our study highlighted that organic fertilizer should be applied alone or in combination with inorganic fertilizers to lower the environmental risks of Cr and Cd pollution in the chernozem.展开更多
文摘The bottom ash and fly ash from the co-combustion of wood residues and peat at a bubbling fluidised bed boiler（296 MW） contained only quartz（SiO_2）, microcline（KAl Si_3O_8） and albite（NaAlSi_3O_8）. Thus, X-ray powder diffraction（XRD） was not useful for clarifying the difference in the release of associated heavy metals from ash matrices. In order to assess the release of heavy metals from ashes under changing environmental conditions, they were sequentially extracted and fractionated by the BCR-procedure into acid soluble/exchangeable（CH_3COOH）, reducible（NH_2OH-HCl） and oxidizable（H_2O_2/CH_3COONH_4） phases. The CH_3 COOH extractable fraction in conjunction with the total heavy metals concentrations were used to calculate the risk assessment code values for heavy metals leaching from the ash matrix. The leaching studies indicate that the heavy metals in the bottom ash and fly ash are bound to different fractions with different strengths. From the environmental and utilization perspectives, heavy metals in ashes posed different levels of environmental contamination risk. Only As in the bottom ash posed a very high risk. High risk metals were Cd in the bottom ash as well as As, Cd and Se in the fly ash.
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.
文摘Sale-leaseback is paid special focus on for its great application in China in recent years.By giving a detailed analysis,an analysis of the features of sale-leaseback and a study of the risks of it are given in this paper.Then a quantitative analysis of commercial real estate sale-leaseback is carried out.The scientific theoretical analysis is provided in this paper for risk assessment in commercial real estate sale-leaseback mode in China.An effective approach is put forward for sale-leaseback project evaluation and prevention of risk.A useful means is given to supervise commerciai real estate sale-leaseback mode for relevant departments and a certain contribution is made to a further sound development of commercial real estate sale-leaseback mode.
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.
基金the National Key Technology R&D Program of China(Nos.2012BAD15B05 and 2013BAD16B01)
文摘Fertilizers are widely applied in agricultural practice to improve crop yield and quality.However, they can also alter the behavior of soil pollutants.A field experiment was conducted on a chernozem in Heilongjiang Province, China.Various proportions of inorganic nitrogen(N), phosphorus(P), and organic(manure) fertilizers were applied.Soil samples were collected four times over 2 years, and the total concentrations and speciation of chromium(Cr) and cadmium(Cd) were analyzed.Inorganic fertilizer addition had little effect on the total concentration of Cr and Cd, while organic fertilizer addition reduced the total concentrations of both Cr and Cd.Inorganic fertilizers increased the concentration of Cr in the exchangeable form, but decreased that of the residual form(P < 0.05).Addition of inorganic or organic fertilizer alone decreased concentrations of exchangeable Cd(P < 0.05), but the combination of inorganic and organic fertilizers had the opposite effect.High concentration of total Cd exceeding the upper limits of the Environmental Quality Standard for Soils proposed by the Ministry of Environmental Protection of China could result in an environmental risk, and fertilizer application could lower that risk.Results of risk assessment code calculated as the percentage of the sum of metal concentrations in the exchangeable and carbonate-associated form in total metal concentration showed that Cr and Cd risks were lowered when organic fertilizer was applied alone or in combination with inorganic fertilizers.Our study highlighted that organic fertilizer should be applied alone or in combination with inorganic fertilizers to lower the environmental risks of Cr and Cd pollution in the chernozem.
