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近地表土壤水分条件对农田化学物质输出过程和地表水质有很大影响。以黄土区缓坡耕地为研究对象,利用地下供水和前期降雨措施改变坡面近地表土壤水分条件,通过室内模拟降雨试验研究坡面水土流失和土壤溶质(NO3-、PO43-、K+和B r-)的迁移特征。结果表明地下供水对土壤溶质迁移影响最大,水土流失量和溶质地表流失量显著高于其它处理。前期降雨处理地表径流量和泥沙量大于对照处理,而径流和泥沙溶质平均浓度相对较低。NO3-和B r-坡面迁移的主要载体是地表径流,PO43-主要随侵蚀泥沙迁移,K+两者兼有。地下供水坡地出现明显的土壤侵蚀后,地表径流中PO43-和K+的浓度急剧增加。土壤初始含水量较高的地下供水和前期降雨坡地是土壤侵蚀和吸附态溶质流失的敏感区,对应的等效径流迁移深度也较大。
Near-surface soil moisture conditions have a significant impact on the chemical processes of farmland output and surface water quality. Taking the gentle slope farmland in the loess area as the research object, the near surface soil moisture conditions on the slope surface were changed by underground water supply and pre-rainfall measures. The soil erosion and soil solutes (NO3-, PO43-, K + and B r- ) Migration characteristics. The results showed that subsurface water supply had the greatest impact on soil solute transport, and soil erosion and solute loss were significantly higher than those of other treatments. Pre-rainfall treatment surface runoff and sediment yield is greater than the control treatment, and runoff and sediment average concentration is relatively low. The main carrier of NO3- and B r- slope migration is surface runoff, PO43- mainly migrates with erosion sediment, K + both. After obvious soil erosion occurred on the subsurface water supply slope, the concentration of PO43- and K + in surface runoff increased sharply. The underground water supply and pre-rainfall slope with higher initial water content are the sensitive areas for soil erosion and solute loss, and the corresponding equivalent runoff migration depth is also larger.