灌溉在保障农业正常生产的同时,也对土壤理化性质产生重要影响。本研究以宁夏引黄灌区为例,通过与未进行灌溉、耕作等人为活动影响的自然土壤进行对比分析,研究了引用含有泥沙的黄河水灌溉、耕作对土壤基本理化属性和土壤有机碳组分变...灌溉在保障农业正常生产的同时,也对土壤理化性质产生重要影响。本研究以宁夏引黄灌区为例,通过与未进行灌溉、耕作等人为活动影响的自然土壤进行对比分析,研究了引用含有泥沙的黄河水灌溉、耕作对土壤基本理化属性和土壤有机碳组分变化的影响。结果表明:与自然土壤相比,引黄灌溉后,土壤总有机碳、重组有机碳和轻组有机碳增加显著,分别增加了272%、222%和318%(P<0.01)。重组有机碳是引黄灌区土壤碳库的主要组分,占总有机碳65%以上,灌区土壤碳库稳定性较高;引黄灌溉耕作后,全氮和全磷含量分别由0.27和0.85 g·kg^(-1)增加到0.77和1.68 g kg^(-1)(P<0.05);土壤容重降低,通气保水能力增强,pH下降,土壤盐化趋势减弱,土壤肥力水平提高。引黄灌溉是改善该区土壤性状和提高土地生产力的有效措施。展开更多
Five diagnostic experiments with a 3D baroclinic hydrodynamic and sediment transport model ECOMSED in couple with the third generation wave model SWAN and the Grant-Madsen bottom boundary layer model driven by the mon...Five diagnostic experiments with a 3D baroclinic hydrodynamic and sediment transport model ECOMSED in couple with the third generation wave model SWAN and the Grant-Madsen bottom boundary layer model driven by the monthly sediment load of the Yellow River, were conducted to separately diagnose effects of different hydrodynamic factors on transport of suspended sediment discharged from the Yellow River in the Bohai Sea. Both transport and spatio-temporal distribution of suspended sediment concentration in the Bohai Sea were numerially simulated. It could be from the Yellow River cannot be delivered in concluded that suspended sediment discharged long distance under the condition of tidal current. Almost all of sediments from the Yellow River are deposited outside the delta under the condition of wind-driven current, and only very small of them are transported faraway. On the basis of wind forcing, sediments from the Yellow River are mainly transported north-northwestward, and others which are first delivered to the Laizhou Bay are continuously moved northward. An obvious 3D structure characteristic of sediment transport is produced in the wind-driven and tide-induced residual circulation condition. Transport patterns at all layers are generally consistent with circulation structure, but there is apparent deviation between the depth-averaged sediment flux and the circulation structure. The phase of temporal variation of sediment concentration is consistent with that of the bottom shear stress, both of which are proved to have a ten-day cycle in wave and current condition.展开更多
文摘灌溉在保障农业正常生产的同时,也对土壤理化性质产生重要影响。本研究以宁夏引黄灌区为例,通过与未进行灌溉、耕作等人为活动影响的自然土壤进行对比分析,研究了引用含有泥沙的黄河水灌溉、耕作对土壤基本理化属性和土壤有机碳组分变化的影响。结果表明:与自然土壤相比,引黄灌溉后,土壤总有机碳、重组有机碳和轻组有机碳增加显著,分别增加了272%、222%和318%(P<0.01)。重组有机碳是引黄灌区土壤碳库的主要组分,占总有机碳65%以上,灌区土壤碳库稳定性较高;引黄灌溉耕作后,全氮和全磷含量分别由0.27和0.85 g·kg^(-1)增加到0.77和1.68 g kg^(-1)(P<0.05);土壤容重降低,通气保水能力增强,pH下降,土壤盐化趋势减弱,土壤肥力水平提高。引黄灌溉是改善该区土壤性状和提高土地生产力的有效措施。
基金National Natural Science Foundation of China, No.40771030 No.40571020
文摘Five diagnostic experiments with a 3D baroclinic hydrodynamic and sediment transport model ECOMSED in couple with the third generation wave model SWAN and the Grant-Madsen bottom boundary layer model driven by the monthly sediment load of the Yellow River, were conducted to separately diagnose effects of different hydrodynamic factors on transport of suspended sediment discharged from the Yellow River in the Bohai Sea. Both transport and spatio-temporal distribution of suspended sediment concentration in the Bohai Sea were numerially simulated. It could be from the Yellow River cannot be delivered in concluded that suspended sediment discharged long distance under the condition of tidal current. Almost all of sediments from the Yellow River are deposited outside the delta under the condition of wind-driven current, and only very small of them are transported faraway. On the basis of wind forcing, sediments from the Yellow River are mainly transported north-northwestward, and others which are first delivered to the Laizhou Bay are continuously moved northward. An obvious 3D structure characteristic of sediment transport is produced in the wind-driven and tide-induced residual circulation condition. Transport patterns at all layers are generally consistent with circulation structure, but there is apparent deviation between the depth-averaged sediment flux and the circulation structure. The phase of temporal variation of sediment concentration is consistent with that of the bottom shear stress, both of which are proved to have a ten-day cycle in wave and current condition.
