An extensive soil investigation was conducted in different domains of Changchun to disclose the fractionations of Pb, Cu, Cd, Zn and Ni in urban soils. Meanwhile correlation analysis and multiple stepwise regressions ...An extensive soil investigation was conducted in different domains of Changchun to disclose the fractionations of Pb, Cu, Cd, Zn and Ni in urban soils. Meanwhile correlation analysis and multiple stepwise regressions were used to define relationships between soil properties and metal fractions and the chief factors influencing the fractionation of heavy metals in the soils. The results showed that Pb, Ni and Cu were mainly associated with the residual and organic forms; most of Cd was concentrated in the residual and exchangeable fractions. Zn in residual and carbonate fraction was the highest. The activities of the heavy metals probably declined in the following order: Cd, Zn, Pb, Cu and Ni. The chemical fractions of heavy metals in different domains in Changchun City were of significantly spatial heterogeneity. Soil properties had different influences on the chemical fractions of heavy metals to some extent and the main factors influencing Cd, Zn, Pb, Cu and Ni fractionation and transformation were apparently different.展开更多
Alpine tundra ecosystems have specific vegetation and environmental conditions that may affect soil phosphorus （P） composition and phosphatase activities. However, these effects are poody understood. This study used...Alpine tundra ecosystems have specific vegetation and environmental conditions that may affect soil phosphorus （P） composition and phosphatase activities. However, these effects are poody understood. This study used NaOH-EDTA extraction and solution ^31P nuclear magnetic resonance （NMR） spectroscopy to determine soil P composition and phosphatase activities, including acid phosphomonoesterase （AcP）, phosphodiesterase （PD） and inorganic pyrophosphatase （IPP）, in the alpine tundra of the Changbai Mountains at seven different altitudinal gradients （i.e., 2000 m, 2100 m, 2200 m, 2300 m, 2400 m, 2500 m, and 2600 m）. The results show that total P （TP）, organic P （OP）, OP/TP, NaOH-EDTA extracted P and AcP, PD, and IPP activities over the altitude range of 2500-2600 m are significantly lower than those below 2400 m. The dominant extracted form of P is OP （73%0-83%） with a large proportion of monoesters （65%0-72%）, whereas inorganic P is present in lower proportions （17%-27%）. The activity of AcP is significantly positively correlated with the contents of soil OP, total carbon （TC）, total nitrogen （TN）, and TP （P 〈 0.05）, indicating that the AcP is a more sensitive index for responding P nutrient storage than PD and IPP. Soil properties, P composition, and phosphatase activities decrease with increased altitude and soil pH. Our results indicate that the distribution of soil P composition and phosphatase activities along altitude and AcP may play an important role in P hydrolysis as well as have the potential to be an indicator of soil quality.展开更多
文摘An extensive soil investigation was conducted in different domains of Changchun to disclose the fractionations of Pb, Cu, Cd, Zn and Ni in urban soils. Meanwhile correlation analysis and multiple stepwise regressions were used to define relationships between soil properties and metal fractions and the chief factors influencing the fractionation of heavy metals in the soils. The results showed that Pb, Ni and Cu were mainly associated with the residual and organic forms; most of Cd was concentrated in the residual and exchangeable fractions. Zn in residual and carbonate fraction was the highest. The activities of the heavy metals probably declined in the following order: Cd, Zn, Pb, Cu and Ni. The chemical fractions of heavy metals in different domains in Changchun City were of significantly spatial heterogeneity. Soil properties had different influences on the chemical fractions of heavy metals to some extent and the main factors influencing Cd, Zn, Pb, Cu and Ni fractionation and transformation were apparently different.
基金National Natural Science Foundation of China(No.41171241)
文摘Alpine tundra ecosystems have specific vegetation and environmental conditions that may affect soil phosphorus （P） composition and phosphatase activities. However, these effects are poody understood. This study used NaOH-EDTA extraction and solution ^31P nuclear magnetic resonance （NMR） spectroscopy to determine soil P composition and phosphatase activities, including acid phosphomonoesterase （AcP）, phosphodiesterase （PD） and inorganic pyrophosphatase （IPP）, in the alpine tundra of the Changbai Mountains at seven different altitudinal gradients （i.e., 2000 m, 2100 m, 2200 m, 2300 m, 2400 m, 2500 m, and 2600 m）. The results show that total P （TP）, organic P （OP）, OP/TP, NaOH-EDTA extracted P and AcP, PD, and IPP activities over the altitude range of 2500-2600 m are significantly lower than those below 2400 m. The dominant extracted form of P is OP （73%0-83%） with a large proportion of monoesters （65%0-72%）, whereas inorganic P is present in lower proportions （17%-27%）. The activity of AcP is significantly positively correlated with the contents of soil OP, total carbon （TC）, total nitrogen （TN）, and TP （P 〈 0.05）, indicating that the AcP is a more sensitive index for responding P nutrient storage than PD and IPP. Soil properties, P composition, and phosphatase activities decrease with increased altitude and soil pH. Our results indicate that the distribution of soil P composition and phosphatase activities along altitude and AcP may play an important role in P hydrolysis as well as have the potential to be an indicator of soil quality.
