In order to explicit the environmental activity of heavy metals affected by different organic acids in soil,a batch incubation experiment was explored to investigate the influence of high relative molecular mass organ...In order to explicit the environmental activity of heavy metals affected by different organic acids in soil,a batch incubation experiment was explored to investigate the influence of high relative molecular mass organic acid(HMWOA)(humic acid and fulvic acid)and low relative molecular mass organic acid(LMWOA)(threonic acid and oxalic acid)on the release or immobilization of Pb,Cu and Cd in soils.Results showed that LMWOA,especially threonic acid,had a good performance in the release of Pb,Cu and Cd from soils,and decrease in the fractions of HOAc-extractable,reducible and oxidable Pb,Cu and Cd.Conversely,HMWOA,especially humic acid,decreased the release of Pb,Cu and Cd,while it increased the fractions of HOAc-extractable,reducible and oxidable Pb,Cu and Cd,indicating that HMWOA can immobilize heavy metals.The release of Pb,Cu and Cd caused by LMWOA was attributed to the dissociation of soil organic matter and amorphous iron oxides since the total organic carbon and the water-soluble iron increased.The immobilization of Pb,Cu and Cd by HMWOA was attributed to the adsorption onto HMWOA followed by amorphous iron since HMWOA resulted in a significant decrease of zeta potential and an increase of amorphous iron oxide.It can be concluded that LMWOA has a potential application in soil washing remediation,while HMWOA can be used in the immobilization remediation for heavy metals contaminated soils.展开更多
The release of heavy metals from the combustion of hazardous wastes is an environmental issue of in-creasing concern.The species transformation characteristics of toxic heavy metals and their distribution are consid-e...The release of heavy metals from the combustion of hazardous wastes is an environmental issue of in-creasing concern.The species transformation characteristics of toxic heavy metals and their distribution are consid-ered to be a complex problem of mechanism.The behavior of hazardous dyestuff residue is investigated in a tubular furnace under the general condition of hazardous waste pyrolysis and gasfication.Data interpretation has been aided by parallel theoretical study based on a thermodynamic equilibrium model based on the principle of Gibbs free en-ergy minimization.The results show that Ni,Zn,Mn,and Cr are more enriched in dyestuff residue incineration than other heavy metals(Hg,As,and Se)subjected to volatilization.The thermodynamic model calculation is used for explaining the experiment data at 800℃ and analyzing species transformation of heavy metals.These results of species transformation are used to predict the distribution and emission characteristics of trace elements.Although most trace element predictions are validated by the measurements,cautions are in order due to the complexity of incineration systems.展开更多
Due to the elevated ecological awareness nowadays the consumption of products of organic agriculture is increasing. Organic farming means excluding the use of synthetic inputs, such as synthetic fertilizers and pestic...Due to the elevated ecological awareness nowadays the consumption of products of organic agriculture is increasing. Organic farming means excluding the use of synthetic inputs, such as synthetic fertilizers and pesticides or genetically modified organisms, but there are only a few regulations regarding heavy metal concentrations in soils. Thus a not negligible uptake of metals from the soil where the apple trees are grown may occur. Furthermore inorganic copper compounds being traditional fertilizers for apple trees are not considered as synthetic fertilizers, thus they are still used in organic apple farming for soil or foliar application. Thus also apples produced by organic agriculture may contain toxic elements, such as cadmium, chromium, copper, and lead. The concentrations of these elements were determined in whole apples, as well as in the flesh and peel in order to estimate the possible risk for human health. Prior to analysis using ICP-AES samples underwent a microwave assisted digestion. The LODs obtained are below the recommended maximum levels in vegetables/fruits by WHO. In all samples no Cu, Cr, and Pb could be detected. Only Ca was found in the peel of about a third of samples investigated in concentrations between LOD and LOQ （1-3 μg/g）.展开更多
基金the financial supports from the National Natural Science Foundation of China(No.U20A20267)the National Key R&D Program of China(Nos.2020YFC1808002,2021YFC1809203)。
文摘In order to explicit the environmental activity of heavy metals affected by different organic acids in soil,a batch incubation experiment was explored to investigate the influence of high relative molecular mass organic acid(HMWOA)(humic acid and fulvic acid)and low relative molecular mass organic acid(LMWOA)(threonic acid and oxalic acid)on the release or immobilization of Pb,Cu and Cd in soils.Results showed that LMWOA,especially threonic acid,had a good performance in the release of Pb,Cu and Cd from soils,and decrease in the fractions of HOAc-extractable,reducible and oxidable Pb,Cu and Cd.Conversely,HMWOA,especially humic acid,decreased the release of Pb,Cu and Cd,while it increased the fractions of HOAc-extractable,reducible and oxidable Pb,Cu and Cd,indicating that HMWOA can immobilize heavy metals.The release of Pb,Cu and Cd caused by LMWOA was attributed to the dissociation of soil organic matter and amorphous iron oxides since the total organic carbon and the water-soluble iron increased.The immobilization of Pb,Cu and Cd by HMWOA was attributed to the adsorption onto HMWOA followed by amorphous iron since HMWOA resulted in a significant decrease of zeta potential and an increase of amorphous iron oxide.It can be concluded that LMWOA has a potential application in soil washing remediation,while HMWOA can be used in the immobilization remediation for heavy metals contaminated soils.
基金Supported by the National Natural Science Foundation of China (No.50276055)the Superintendent's Fund of Guangzhou Institute of Energy Conversion,Chinese Academy of Sciences (No.0607ba1001).
文摘The release of heavy metals from the combustion of hazardous wastes is an environmental issue of in-creasing concern.The species transformation characteristics of toxic heavy metals and their distribution are consid-ered to be a complex problem of mechanism.The behavior of hazardous dyestuff residue is investigated in a tubular furnace under the general condition of hazardous waste pyrolysis and gasfication.Data interpretation has been aided by parallel theoretical study based on a thermodynamic equilibrium model based on the principle of Gibbs free en-ergy minimization.The results show that Ni,Zn,Mn,and Cr are more enriched in dyestuff residue incineration than other heavy metals(Hg,As,and Se)subjected to volatilization.The thermodynamic model calculation is used for explaining the experiment data at 800℃ and analyzing species transformation of heavy metals.These results of species transformation are used to predict the distribution and emission characteristics of trace elements.Although most trace element predictions are validated by the measurements,cautions are in order due to the complexity of incineration systems.
文摘Due to the elevated ecological awareness nowadays the consumption of products of organic agriculture is increasing. Organic farming means excluding the use of synthetic inputs, such as synthetic fertilizers and pesticides or genetically modified organisms, but there are only a few regulations regarding heavy metal concentrations in soils. Thus a not negligible uptake of metals from the soil where the apple trees are grown may occur. Furthermore inorganic copper compounds being traditional fertilizers for apple trees are not considered as synthetic fertilizers, thus they are still used in organic apple farming for soil or foliar application. Thus also apples produced by organic agriculture may contain toxic elements, such as cadmium, chromium, copper, and lead. The concentrations of these elements were determined in whole apples, as well as in the flesh and peel in order to estimate the possible risk for human health. Prior to analysis using ICP-AES samples underwent a microwave assisted digestion. The LODs obtained are below the recommended maximum levels in vegetables/fruits by WHO. In all samples no Cu, Cr, and Pb could be detected. Only Ca was found in the peel of about a third of samples investigated in concentrations between LOD and LOQ （1-3 μg/g）.
