Cropland productivity has been significantly impacted by soil acidification resulted from nitrogen （N） fertilization, especially as a result of excess ammoniacal N input. With decades＇ intensive agricultural cultiv...Cropland productivity has been significantly impacted by soil acidification resulted from nitrogen （N） fertilization, especially as a result of excess ammoniacal N input. With decades＇ intensive agricultural cultivation and heavy chemical N input in the Huang-Huai-Hai Plain, the impact extent of induced proton input on soil pH in the long term was not yet clear. In this study, acidification rates of different soil layers in the soil profile （0-120 cm） were calculated by pH buffer capacity （pHBC） and net input of protons due to chemical N incorporation. Topsoil （0-20 cm） pH changes of a long-term fertilization field （from 1989） were determined to validate the predicted values. The results showed that the acid and alkali buffer capacities varied significantly in the soil profile, averaged 692 and 39.8 mmolc kg-1 pH-1, respectively. A significant （P〈0.05） correlation was found between pHRC and the content of calcium carbonate. Based on the commonly used application rate of urea （500 kg N ha-1 yr-1）, the induced proton input in this region was predicted to be 16.1 kmol ha-1 yr-1, and nitrification and plant uptake of nitrate were the most important mechanisms for proton producing and consuming, respectively. The acidification rate of topsoil （0-20 cm） was estimated to be 0.01 unit pH yr-1 at the assumed N fertilization level. From 1989 to 2009, topsoil pH （0-20 cm） of the long-term fertilization field decreased from 8.65 to 8.50 for the PK （phosphorus, 150 kg P205 ha-1 yr-1; potassium, 300 kg K20 ha-1 yr-1; without N fertilization）, and 8.30 for NPK （nitrogen, 300 kg N ha-1 yr-1; phosphorus, 150 kg P2Os ha-1 yr-1; potassium, 300 kg K20 ha -1 yr-1）, respectively. Therefore, the apparent soil acidification rate induced by N fertilization equaled to 0.01 unit pH yr-1, which can be a reference to the estimated result, considering the effect of atmospheric N deposition, crop biomass, field management and plant uptake of other nutrients and cations. As protons could be consumed by some field practices, such as stubble return and coupled water and nutrient management, soil pH would maintain relatively stable if proper management practices can be adopted in this region.展开更多
Ternary In-rich AlxIn1-x N films were successfully grown on Si （111） and （0001） sapphire substrates by radio-frequency magnetron sputtering on a relatively Al-rich AlxIn1-x N layer after AlN buffer. X-ray diffract...Ternary In-rich AlxIn1-x N films were successfully grown on Si （111） and （0001） sapphire substrates by radio-frequency magnetron sputtering on a relatively Al-rich AlxIn1-x N layer after AlN buffer. X-ray diffraction （XRD） patterns of the films indicate highly c axis-oriented wurtzite structure and the indium content of about 0.76 has been evaluated according to the Vegard＇s law. An Al-rich AlxIn1-xN transition layer was formed between the ultimate In-rich AlxIn1-x N film and the AlN buffer, which served as a further buffer to alleviate mismatch. X-ray photoelectron spectroscopy （XPS） depth profiling analyses confirm the alternative of indium and aluminum composition and the unavoidable oxygen impurities from surface to bulk. Owing to high indium content, obvious E2u and InN-like Al （LO） phonon model accompanying with slight A1N-like A1 （LO） phonon model are observed. Hall effect measurements demonstrate n-type electrical conductivity in these alloys with carrier concentrations n=1019 cm-3. The strain in In-rich AlxIn1-x N films can be significantly reduced by introducing an Al-rich interlayer, facilitating the improvement of film quality for diverse device applications.展开更多
Aim To compare lipophilicity measuring scale stemmed from immobilized artificial membrane chromatography and n octanol/buffer systems. Methods A test set consisted of 27 structurally diverse compounds. The lipophilici...Aim To compare lipophilicity measuring scale stemmed from immobilized artificial membrane chromatography and n octanol/buffer systems. Methods A test set consisted of 27 structurally diverse compounds. The lipophilicity of these were evaluated by both immobilized artificial memberane chromatography (IAMC) and n octanol/buffer systems, which were expressed as lg k IAM and lg D O/W,7 4 , respectively. Results With regard to each individual group, good correlation coefficient ( r 2) over 0 81 was obtained (0 82 for acid, 0 88 for neutral, 0 81 for base and 0 92 for ampholyte, respectively). However, a smaller r 2 (0 62) was acquired for all compounds studied than that of each individual group. Conclusion IAMC and n octanol/buffer systems were shown to be different in lipophilicity.展开更多
基金financially supported by the National Basic Research Program of China (2011CB100506)the China Agriculture Research System-Wheat (CARS-03-02A)+1 种基金the Knowledge Innovation Program of the Chinese Academy of Sciences (KSCX2-EW-N-08)Research Fund of State Key Laboratory of Soil and Sustainable Agriculture, Nanjing Institute of Soil Science, Chinese Academy of Sciences (Y412201401)
文摘Cropland productivity has been significantly impacted by soil acidification resulted from nitrogen （N） fertilization, especially as a result of excess ammoniacal N input. With decades＇ intensive agricultural cultivation and heavy chemical N input in the Huang-Huai-Hai Plain, the impact extent of induced proton input on soil pH in the long term was not yet clear. In this study, acidification rates of different soil layers in the soil profile （0-120 cm） were calculated by pH buffer capacity （pHBC） and net input of protons due to chemical N incorporation. Topsoil （0-20 cm） pH changes of a long-term fertilization field （from 1989） were determined to validate the predicted values. The results showed that the acid and alkali buffer capacities varied significantly in the soil profile, averaged 692 and 39.8 mmolc kg-1 pH-1, respectively. A significant （P〈0.05） correlation was found between pHRC and the content of calcium carbonate. Based on the commonly used application rate of urea （500 kg N ha-1 yr-1）, the induced proton input in this region was predicted to be 16.1 kmol ha-1 yr-1, and nitrification and plant uptake of nitrate were the most important mechanisms for proton producing and consuming, respectively. The acidification rate of topsoil （0-20 cm） was estimated to be 0.01 unit pH yr-1 at the assumed N fertilization level. From 1989 to 2009, topsoil pH （0-20 cm） of the long-term fertilization field decreased from 8.65 to 8.50 for the PK （phosphorus, 150 kg P205 ha-1 yr-1; potassium, 300 kg K20 ha-1 yr-1; without N fertilization）, and 8.30 for NPK （nitrogen, 300 kg N ha-1 yr-1; phosphorus, 150 kg P2Os ha-1 yr-1; potassium, 300 kg K20 ha -1 yr-1）, respectively. Therefore, the apparent soil acidification rate induced by N fertilization equaled to 0.01 unit pH yr-1, which can be a reference to the estimated result, considering the effect of atmospheric N deposition, crop biomass, field management and plant uptake of other nutrients and cations. As protons could be consumed by some field practices, such as stubble return and coupled water and nutrient management, soil pH would maintain relatively stable if proper management practices can be adopted in this region.
基金Supported by the 863 High-Technology Research and Development Program of China(No.2009AA03Z442)the National Natural Science Foundation of China(No.61077074)the Science and Technology Department of Jilin Province(No.20090422)
文摘Ternary In-rich AlxIn1-x N films were successfully grown on Si （111） and （0001） sapphire substrates by radio-frequency magnetron sputtering on a relatively Al-rich AlxIn1-x N layer after AlN buffer. X-ray diffraction （XRD） patterns of the films indicate highly c axis-oriented wurtzite structure and the indium content of about 0.76 has been evaluated according to the Vegard＇s law. An Al-rich AlxIn1-xN transition layer was formed between the ultimate In-rich AlxIn1-x N film and the AlN buffer, which served as a further buffer to alleviate mismatch. X-ray photoelectron spectroscopy （XPS） depth profiling analyses confirm the alternative of indium and aluminum composition and the unavoidable oxygen impurities from surface to bulk. Owing to high indium content, obvious E2u and InN-like Al （LO） phonon model accompanying with slight A1N-like A1 （LO） phonon model are observed. Hall effect measurements demonstrate n-type electrical conductivity in these alloys with carrier concentrations n=1019 cm-3. The strain in In-rich AlxIn1-x N films can be significantly reduced by introducing an Al-rich interlayer, facilitating the improvement of film quality for diverse device applications.
文摘Aim To compare lipophilicity measuring scale stemmed from immobilized artificial membrane chromatography and n octanol/buffer systems. Methods A test set consisted of 27 structurally diverse compounds. The lipophilicity of these were evaluated by both immobilized artificial memberane chromatography (IAMC) and n octanol/buffer systems, which were expressed as lg k IAM and lg D O/W,7 4 , respectively. Results With regard to each individual group, good correlation coefficient ( r 2) over 0 81 was obtained (0 82 for acid, 0 88 for neutral, 0 81 for base and 0 92 for ampholyte, respectively). However, a smaller r 2 (0 62) was acquired for all compounds studied than that of each individual group. Conclusion IAMC and n octanol/buffer systems were shown to be different in lipophilicity.
