为研究不同橡胶集料取代率对风积沙混凝土力学性能的影响规律,设计、制作10组不同配合比的混凝土试件,通过对各试件进行基本力学性能试验、扫描电子显微镜(scanning electron microscope,SEM)和能量色散谱(energy dispersive spectrosco...为研究不同橡胶集料取代率对风积沙混凝土力学性能的影响规律,设计、制作10组不同配合比的混凝土试件,通过对各试件进行基本力学性能试验、扫描电子显微镜(scanning electron microscope,SEM)和能量色散谱(energy dispersive spectroscopy,EDS)测试,对比分析了橡胶集料和风积沙对混凝土力学性能的作用机理,并研究了橡胶集料风积沙混凝土和橡胶集料混凝土两种试件水泥石砂浆界面过渡区的微观结构。研究结果表明:橡胶集料风积沙混凝土和橡胶集料混凝土试件的抗压、抗折、劈裂抗拉强度均随着橡胶集料取代率的增加而降低;折压比随橡胶集料取代率的增加而增加;橡胶的掺入使混凝土的界面过渡区更为薄弱,试件内部呈现出较多微小孔隙,导致混凝土强度的降低。展开更多
In order to evaluate ecological risk of agrochemicals in agricultural environment, single and joint toxic effects of an important herbicide and a typical heavy metal on root elongation of crops were investigated. Seed...In order to evaluate ecological risk of agrochemicals in agricultural environment, single and joint toxic effects of an important herbicide and a typical heavy metal on root elongation of crops were investigated. Seeds of the three crops including wheat （Triticum aestivum）, Chinese cabbage （Brassica pekimensis） and soybean （Glycine max） as the main crops in northeast China were exposed to acetochior as a herbicide and lead （Pb） as a heavy metal using the pot-culture method, and meadow brown soil as one of the main soils distributed in northeast China was applied in the investigation. The results indicated that the interactive effects of the two pollutants on root elongation of the three crops were very complicated although they had markedly significant （P〈0.01） linear interrelationships based on the regression analyses. When the concentration of added Pb^2＋ reached 200 mg/kg, acetochlor and Pb had an antagonistic effect on the inhibition of root elongation of the three crops. However, acetochlor and Pb had significantly （P〈0.05） synergic effects on the inhibition of root elongation when concentration of added Pb^2＋ was up to 1000 mg/kg. At the low concentration of added Pb, joint toxicity of acetochlor and Pb was more dependent on the concentration of Pb. Among the three crops, wheat was the most sensitive to the toxicity of Pb and Chinese cabbage was the most sensitive to the toxicity of acetochlor.展开更多
A pot experiment was conducted to examine the influence of phosphate levels on the phytoavailability and speciation distribution of cadmium （Cd）, lead （Pb） in soil. Spring wheat （Triticum aestivum L.） was select...A pot experiment was conducted to examine the influence of phosphate levels on the phytoavailability and speciation distribution of cadmium （Cd）, lead （Pb） in soil. Spring wheat （Triticum aestivum L.） was selected as the tested plant. There were 5 phosphate fertilizer（Ca（H2PO4）2） levels including 0, 50, 100, 200, and 400 mg P2O5/kg soil, marked by P0, P1, P2, P3, and P4, respectively. CdCl2·2.5H2o and Pb（NO3）2 were added to soil as the following levels： Cd ＋ Pb = 25＋0, 0＋1000, and 25＋1000 mg/kg, marked by T1, T2, and T3, respectively. The results showed that the P fertilizer promoted the dry weight of wheat in all treatments and alleviated the contamination induced by Cd and Pb. With increasing levels of the additional P fertilizer, Cd concentration in different parts （root, haulm, chaffand grain） of wheat decreased at the P1 level at first and then increased. The soluble plus exchangeable （SE） fraction of Cd in soil decreased at the P1 level and then increased from P2 to P4 levels. The moderate P fertilizer reduced the phytoavailability of Cd. The application of P could obviously restrain the uptake of Pb by wheat and there were significantly negative correlations between the levels of P and the uptake of Pb. Phosphorus supply resulted in a decrease in the SE fraction of Pb and there was a significantly negative correlation between the levels of P and the SE fraction of Pb in soil. All the levels of the P fertilizer in this experiment could reduce the phytoavailability of Pb. Thus, it is feasible to apply the P fertilizer （Ca（H2PO4）2） to Pb contaminated soils. However, the levels of P application should be restricted in case that redundant P may increase the phytoavailability of Cd.展开更多
文摘为研究不同橡胶集料取代率对风积沙混凝土力学性能的影响规律,设计、制作10组不同配合比的混凝土试件,通过对各试件进行基本力学性能试验、扫描电子显微镜(scanning electron microscope,SEM)和能量色散谱(energy dispersive spectroscopy,EDS)测试,对比分析了橡胶集料和风积沙对混凝土力学性能的作用机理,并研究了橡胶集料风积沙混凝土和橡胶集料混凝土两种试件水泥石砂浆界面过渡区的微观结构。研究结果表明:橡胶集料风积沙混凝土和橡胶集料混凝土试件的抗压、抗折、劈裂抗拉强度均随着橡胶集料取代率的增加而降低;折压比随橡胶集料取代率的增加而增加;橡胶的掺入使混凝土的界面过渡区更为薄弱,试件内部呈现出较多微小孔隙,导致混凝土强度的降低。
基金Project supported by the National Science Fund for Distinguished Young Scholar of China(No.20225722)the National Natural Science Founda-tion of China(No.20337010)the National Basic Research Program (973)of China(No.2004CB418503).
文摘In order to evaluate ecological risk of agrochemicals in agricultural environment, single and joint toxic effects of an important herbicide and a typical heavy metal on root elongation of crops were investigated. Seeds of the three crops including wheat （Triticum aestivum）, Chinese cabbage （Brassica pekimensis） and soybean （Glycine max） as the main crops in northeast China were exposed to acetochior as a herbicide and lead （Pb） as a heavy metal using the pot-culture method, and meadow brown soil as one of the main soils distributed in northeast China was applied in the investigation. The results indicated that the interactive effects of the two pollutants on root elongation of the three crops were very complicated although they had markedly significant （P〈0.01） linear interrelationships based on the regression analyses. When the concentration of added Pb^2＋ reached 200 mg/kg, acetochlor and Pb had an antagonistic effect on the inhibition of root elongation of the three crops. However, acetochlor and Pb had significantly （P〈0.05） synergic effects on the inhibition of root elongation when concentration of added Pb^2＋ was up to 1000 mg/kg. At the low concentration of added Pb, joint toxicity of acetochlor and Pb was more dependent on the concentration of Pb. Among the three crops, wheat was the most sensitive to the toxicity of Pb and Chinese cabbage was the most sensitive to the toxicity of acetochlor.
基金The National Basic Research Program (973) of China (No. 2004CB418506)the National Natural Science Foundation of China(No. 20477029)
文摘A pot experiment was conducted to examine the influence of phosphate levels on the phytoavailability and speciation distribution of cadmium （Cd）, lead （Pb） in soil. Spring wheat （Triticum aestivum L.） was selected as the tested plant. There were 5 phosphate fertilizer（Ca（H2PO4）2） levels including 0, 50, 100, 200, and 400 mg P2O5/kg soil, marked by P0, P1, P2, P3, and P4, respectively. CdCl2·2.5H2o and Pb（NO3）2 were added to soil as the following levels： Cd ＋ Pb = 25＋0, 0＋1000, and 25＋1000 mg/kg, marked by T1, T2, and T3, respectively. The results showed that the P fertilizer promoted the dry weight of wheat in all treatments and alleviated the contamination induced by Cd and Pb. With increasing levels of the additional P fertilizer, Cd concentration in different parts （root, haulm, chaffand grain） of wheat decreased at the P1 level at first and then increased. The soluble plus exchangeable （SE） fraction of Cd in soil decreased at the P1 level and then increased from P2 to P4 levels. The moderate P fertilizer reduced the phytoavailability of Cd. The application of P could obviously restrain the uptake of Pb by wheat and there were significantly negative correlations between the levels of P and the uptake of Pb. Phosphorus supply resulted in a decrease in the SE fraction of Pb and there was a significantly negative correlation between the levels of P and the SE fraction of Pb in soil. All the levels of the P fertilizer in this experiment could reduce the phytoavailability of Pb. Thus, it is feasible to apply the P fertilizer （Ca（H2PO4）2） to Pb contaminated soils. However, the levels of P application should be restricted in case that redundant P may increase the phytoavailability of Cd.
