Four soils, phaeozem (PM), saline-alkali soil (SA), meadow albic bleached soil (MA) and dark brown forest soil (DB) from Northeast China were used to examine the sorption and desorption characteristics of Cd and pH in...Four soils, phaeozem (PM), saline-alkali soil (SA), meadow albic bleached soil (MA) and dark brown forest soil (DB) from Northeast China were used to examine the sorption and desorption characteristics of Cd and pH influence on it. According to sorption experiment without pH control, the order of amount of absorbed Cd by soils was: SA>PM>DB>MA. The results from non-linear fitting method showed that Langmuir and Freundrich models were more adaptable than Temkin model in describing the sorption data. The maximum sorption amounts from Langmuir model were: PM>SA>MA>DB. Exponential equation for PM and SA and quadratic equation for MA and DB were suitable to fit the desorption data. The order of average desorption percentage was: MA>DB>PM>SA. The amounts of sorption by PM, DB and MA reached the maximum in pH 9.0, while sorption by SA was linearly increased in the experimental range of pH 3.3-11.4. In uniform pH, however, Cd sorption by SA was the minimum among four soils, which indicated that the more amounts of Cd absorbed by SA in isotherm sorption were ascribed to the higher soil pH. The higher sorption of Cd in PM resulted from the higher percentage of organic matter and clay components.展开更多
A pot experiment was conducted in artificially Cd-contaminated （5 mg Cd kg 1） soils to investigate the feasibility of using lime （3 g kg-1） or phosphate （80 mg P kg-1） to mitigate uptake of Cd by vegetables. Fiv...A pot experiment was conducted in artificially Cd-contaminated （5 mg Cd kg 1） soils to investigate the feasibility of using lime （3 g kg-1） or phosphate （80 mg P kg-1） to mitigate uptake of Cd by vegetables. Five common vegetables in South China, including lettuce （Lactuca sativa L. var. ramosa Hort.）, Chinese cabbage [Brassica rapa L. subsp. Chinensis （L.） var. parachinensis （L. H. Bailey） Hanect], Chinese broccoli （Brassica oleracea L. vat. albiflora Kuntze）, white amaranth （Amaranthus tricolor L.） and purslane （Amaranthus viridis L.）, were grown in the soils and harvested after 60 d. The results showed that liming significantly reduced Cd uptake by most vegetables by 40%-50% （or a maximum of 70%）, mainly due to immobilization of soil Cd. Increased availability of Ca in the soil might also contribute to the Cd uptake reduction as a result of absorption competition between Ca and Cd. Liming caused biomass reduction in white amaranth and purslane, but did not influence growth of the other vegetables. Phosphate decreased Cd uptake by vegetables by 12% 23%. Compared with lime, phosphate decreased, to a smaller extent, the bioavailability of Cd in most cases. Phosphate markedly promoted growth of vegetables. Changes in soil chemistry by adding lime or phosphate did not markedly influence nutrient uptake of vegetables except that lime increased Ca content and phosphate increased P content in shoots of the vegetables. The results suggested that a proper application of lime could be effective in reducing Cd uptake of vegetables, and phosphate could promote growth of the vegetables as well as alleviate the toxicity of Cd.展开更多
基金Under the auspices of the K ey Projectof K now ledge Innovation Program of C hinese A cadem y of Sciences (N o.K ZC X 1-SW -19)
文摘Four soils, phaeozem (PM), saline-alkali soil (SA), meadow albic bleached soil (MA) and dark brown forest soil (DB) from Northeast China were used to examine the sorption and desorption characteristics of Cd and pH influence on it. According to sorption experiment without pH control, the order of amount of absorbed Cd by soils was: SA>PM>DB>MA. The results from non-linear fitting method showed that Langmuir and Freundrich models were more adaptable than Temkin model in describing the sorption data. The maximum sorption amounts from Langmuir model were: PM>SA>MA>DB. Exponential equation for PM and SA and quadratic equation for MA and DB were suitable to fit the desorption data. The order of average desorption percentage was: MA>DB>PM>SA. The amounts of sorption by PM, DB and MA reached the maximum in pH 9.0, while sorption by SA was linearly increased in the experimental range of pH 3.3-11.4. In uniform pH, however, Cd sorption by SA was the minimum among four soils, which indicated that the more amounts of Cd absorbed by SA in isotherm sorption were ascribed to the higher soil pH. The higher sorption of Cd in PM resulted from the higher percentage of organic matter and clay components.
基金Supported by the National Natural Science Foundation of China (Nos. 30870442 and 30630015)the National Basic Research Program(973 Program) of China (No. 2009CB421101)+2 种基金the National High Technology Research and Development Program (863 Program) of China (No. 2007AA061001)the Guangdong Provincial Natural Science Foundation of China (No. 9151001002000001)the key lab(No. 2009DP173224) of Vegetation Restoration and Management of Degraded Ecosystems,Chinese Academy of Sciences for providing the experimental site
文摘A pot experiment was conducted in artificially Cd-contaminated （5 mg Cd kg 1） soils to investigate the feasibility of using lime （3 g kg-1） or phosphate （80 mg P kg-1） to mitigate uptake of Cd by vegetables. Five common vegetables in South China, including lettuce （Lactuca sativa L. var. ramosa Hort.）, Chinese cabbage [Brassica rapa L. subsp. Chinensis （L.） var. parachinensis （L. H. Bailey） Hanect], Chinese broccoli （Brassica oleracea L. vat. albiflora Kuntze）, white amaranth （Amaranthus tricolor L.） and purslane （Amaranthus viridis L.）, were grown in the soils and harvested after 60 d. The results showed that liming significantly reduced Cd uptake by most vegetables by 40%-50% （or a maximum of 70%）, mainly due to immobilization of soil Cd. Increased availability of Ca in the soil might also contribute to the Cd uptake reduction as a result of absorption competition between Ca and Cd. Liming caused biomass reduction in white amaranth and purslane, but did not influence growth of the other vegetables. Phosphate decreased Cd uptake by vegetables by 12% 23%. Compared with lime, phosphate decreased, to a smaller extent, the bioavailability of Cd in most cases. Phosphate markedly promoted growth of vegetables. Changes in soil chemistry by adding lime or phosphate did not markedly influence nutrient uptake of vegetables except that lime increased Ca content and phosphate increased P content in shoots of the vegetables. The results suggested that a proper application of lime could be effective in reducing Cd uptake of vegetables, and phosphate could promote growth of the vegetables as well as alleviate the toxicity of Cd.
