Adsorption and desorption process of cadmium in red soil (Ferrisols) as well as the influence by media' s pH were investigated in detail with and without citric acid and EDTA. Experimental results clearly showed t...Adsorption and desorption process of cadmium in red soil (Ferrisols) as well as the influence by media' s pH were investigated in detail with and without citric acid and EDTA. Experimental results clearly showed that Cd adsorption in red soil was affected significantly by the coexisted organic chemicals. In the presence of citric acid and EDTA, Cd adsorption in red soil increased with pH in acid media but decreased in high pH one. Further studies placed stress on the adsorbed Cd in red soil which was found to be existed mainly as exchangeable one at pH < 5.5, and desorption rate by 0.10 mol/L NaNO3 gave a peak-shaped curve due to the difference of specifically and nonspecifically adsorbed Cd with pH's change.展开更多
The effects of lanthanum on rice growth, phosphorus uptake and phosphorus chemical fractions in rice were studied with split root solution culture. Results show that low concentration of La (0.05～1.5 mg·L -1...The effects of lanthanum on rice growth, phosphorus uptake and phosphorus chemical fractions in rice were studied with split root solution culture. Results show that low concentration of La (0.05～1.5 mg·L -1 ) significantly increases rice yield while high La concentration (9～30 mg·L -1 ) markedly decreases rice yield. When La concentration is 0.05～0.75 mg·L -1 , La increases stem and root dry weight, but the difference is not statistically significant. La significantly increases EDTA P and inorganic P content in the stem and root. More than 80% of the increase of phosphors content in roots attributing to increase of EDTA P and inorganic P. Low La concentration (0.05～0.75 mg·L -1 ) increases nucleic P content in root, but high La concentration (30 mg·L -1 ) decreases nucleic P and ester P content in root. The residue P content increases in the root and stem. Also the relationship between the chemical fractions of phosphorus and its uptake by rice was discussed.展开更多
Three-year summertime surface atmospheric N_2O concentrations were observed for the first time on the Fildes Peninsula, maritime Antarctica, and the relationships among the N2O concentration, total atmospheric O3 amou...Three-year summertime surface atmospheric N_2O concentrations were observed for the first time on the Fildes Peninsula, maritime Antarctica, and the relationships among the N2O concentration, total atmospheric O3 amount, and sunspot number were analyzed. Solar activity had an important effect on surface N2O concentration and total O3 amount, and increases of sunspot number were followed by decreases in the N2O concentration and total O3 amount. A corresponding relationship exists between the N2O concentration and total atmospheric O3, and ozone destruction was preceded by N2O reduction. We propose that the extended solar activity in the Antarctic summer reduces the stratospheric N2O by converting it into NOx, increases the diffusion of N2O from the troposphere to the stratosphere, decreases the surface atmospheric N2O, and depletes O3 via the chemical reaction between O3 and NOx. Our observation results are consistent with the theory of solar activity regarding the formation of the Antarctic O3 hole.展开更多
The effects of lanthanum on the protective enzymes of rape ( Brassica juncea ) were studied in hydroponics experiment. Results show that when treated with 0.3 mg·kg -1 La, the content of chlorophyll and th...The effects of lanthanum on the protective enzymes of rape ( Brassica juncea ) were studied in hydroponics experiment. Results show that when treated with 0.3 mg·kg -1 La, the content of chlorophyll and the activities of peroxidase(POD), catalase(CAT), superoxide dismutase(SOD) and polyphenoloxidase(PPO) in rape increase, but the content of malondialdehyde(MDA) in rape decreases. However, the treatments do not change the content of soluble protein in rape significantly.展开更多
Split-root solution culture was used to study the promoting effect of lanthanum on rice (Oryza sativa) growth and its physiological mechanisms. Results sho w that low concentration (0.05～1.5 mg·L -1) increases...Split-root solution culture was used to study the promoting effect of lanthanum on rice (Oryza sativa) growth and its physiological mechanisms. Results sho w that low concentration (0.05～1.5 mg·L -1) increases rice yield an d grain numbers. High concentration depresses grain formation (9～30 mg·L -1 ) and root elongation (1.5～30 mg·L -1). No significant influence on str aw dry weight was found over the whole concentration range except the 0.05 mg·L -1 treatment. With the increase of La concentration from 0.05 to 0.75 mg· L -1, catalase (CAT) activity in the first fully expandeing leaves and root s decreases. When La concentration is greater than 0.75 mg·L -1 or less than 9 mg·L -1, it significantly decreases superoxide dismutase activity ( SOD) in the leaves and roots. No significant effects were found on chlorophyll, protein and malondialdehyde (MDA) content. Possible mechanisms of La′s promotin g effect on rice growth and reduction effect of ·O- 2 were discussed.展开更多
基金the National Natural Science Foundation of China (No 29877027)the Postdoctoral Science Foundation of China
文摘Adsorption and desorption process of cadmium in red soil (Ferrisols) as well as the influence by media' s pH were investigated in detail with and without citric acid and EDTA. Experimental results clearly showed that Cd adsorption in red soil was affected significantly by the coexisted organic chemicals. In the presence of citric acid and EDTA, Cd adsorption in red soil increased with pH in acid media but decreased in high pH one. Further studies placed stress on the adsorbed Cd in red soil which was found to be existed mainly as exchangeable one at pH < 5.5, and desorption rate by 0.10 mol/L NaNO3 gave a peak-shaped curve due to the difference of specifically and nonspecifically adsorbed Cd with pH's change.
文摘The effects of lanthanum on rice growth, phosphorus uptake and phosphorus chemical fractions in rice were studied with split root solution culture. Results show that low concentration of La (0.05～1.5 mg·L -1 ) significantly increases rice yield while high La concentration (9～30 mg·L -1 ) markedly decreases rice yield. When La concentration is 0.05～0.75 mg·L -1 , La increases stem and root dry weight, but the difference is not statistically significant. La significantly increases EDTA P and inorganic P content in the stem and root. More than 80% of the increase of phosphors content in roots attributing to increase of EDTA P and inorganic P. Low La concentration (0.05～0.75 mg·L -1 ) increases nucleic P content in root, but high La concentration (30 mg·L -1 ) decreases nucleic P and ester P content in root. The residue P content increases in the root and stem. Also the relationship between the chemical fractions of phosphorus and its uptake by rice was discussed.
基金supported by the Key Project of National Natural Science Foundation(Grant No.40231002)the Youth Foundation of the University of Science and Technology of China(Grant NO.KA0727).
文摘Three-year summertime surface atmospheric N_2O concentrations were observed for the first time on the Fildes Peninsula, maritime Antarctica, and the relationships among the N2O concentration, total atmospheric O3 amount, and sunspot number were analyzed. Solar activity had an important effect on surface N2O concentration and total O3 amount, and increases of sunspot number were followed by decreases in the N2O concentration and total O3 amount. A corresponding relationship exists between the N2O concentration and total atmospheric O3, and ozone destruction was preceded by N2O reduction. We propose that the extended solar activity in the Antarctic summer reduces the stratospheric N2O by converting it into NOx, increases the diffusion of N2O from the troposphere to the stratosphere, decreases the surface atmospheric N2O, and depletes O3 via the chemical reaction between O3 and NOx. Our observation results are consistent with the theory of solar activity regarding the formation of the Antarctic O3 hole.
文摘The effects of lanthanum on the protective enzymes of rape ( Brassica juncea ) were studied in hydroponics experiment. Results show that when treated with 0.3 mg·kg -1 La, the content of chlorophyll and the activities of peroxidase(POD), catalase(CAT), superoxide dismutase(SOD) and polyphenoloxidase(PPO) in rape increase, but the content of malondialdehyde(MDA) in rape decreases. However, the treatments do not change the content of soluble protein in rape significantly.
文摘Split-root solution culture was used to study the promoting effect of lanthanum on rice (Oryza sativa) growth and its physiological mechanisms. Results sho w that low concentration (0.05～1.5 mg·L -1) increases rice yield an d grain numbers. High concentration depresses grain formation (9～30 mg·L -1 ) and root elongation (1.5～30 mg·L -1). No significant influence on str aw dry weight was found over the whole concentration range except the 0.05 mg·L -1 treatment. With the increase of La concentration from 0.05 to 0.75 mg· L -1, catalase (CAT) activity in the first fully expandeing leaves and root s decreases. When La concentration is greater than 0.75 mg·L -1 or less than 9 mg·L -1, it significantly decreases superoxide dismutase activity ( SOD) in the leaves and roots. No significant effects were found on chlorophyll, protein and malondialdehyde (MDA) content. Possible mechanisms of La′s promotin g effect on rice growth and reduction effect of ·O- 2 were discussed.
