酸雨对黄土磷的淋溶效应

采用室内土柱模拟淋溶试验,分析了陕西省杨凌区3种土壤在5个酸雨梯度的侵蚀作用下,土壤磷的释放和迁移规律.结果表明,酸雨会使土壤受到一定程度的酸化,而土壤的酸化程度与酸雨的pH值、土壤的类型、土壤的pH值、阳离子交换量、有机质含量有关.土壤对酸雨的缓冲能力由大到小的顺序为:腐殖质层＞母质层＞黏化层.随着酸雨累积淋溶量的增加,土壤磷的释放总量呈增加趋势,但淋失率会下降.酸雨的pH值为5时土壤磷的累积淋失量最大,土壤磷的累积淋失量和淋失率顺序为:腐殖质层＞黏化层＞母质层.酸雨对腐殖质层的磷具有最强侵蚀效应.母质层和黏化层的酸化主要发生在土壤表层,而腐殖质层酸化主要发生在土壤底层,酸雨侵蚀后腐殖质层酸化最严重.长期的酸雨侵蚀会导致土壤磷流失,造成土壤养分贫瘠化.

Leaching Effect of Acid Rain on Phosphorus of Loess Soil

A leaching experiment was conducted using soil column simulation to investigate the release andtransferring characteristics of phosphorus in three soils of Yangling Demonstration Zone,Shaanxi Provinceunder erosion effects of five acid rain gradients.The results showed that acid rain resulted in soil acidificationto some extent,which was controlled by the pH value of the acid rain,soil type,soil pH value,cation exchange capacity and organic matter content.The soils could be ranked in terms of acid rain buffering capacityin a descending order as humus layer>parent material layer>adhesive layer.With the increase of total leaching amount by acid rain,the total soil phosphorus release amount increased with a decreasing leaching rate.Soil phosphorus loss amount achieved the maximum value with acid rain that has a pH value of 5.The soilscould be then ranked in terms of either the cumulative soil phosphorus release amount or the leaching rate ina descending order as humus layer>adhesive layer>parent material layer.Acid rain showed the strongesterosion effect on phosphorus of the humus layer.The acidification in the parent material layer and the adhesive layer occurred mainly in surface,while the acidification in the humus layer mainly occurred in the lowerpart.The most severe acidification by acid rain was found in the humus layer.Long-term acid rain leachingcould lead to soil phosphorus loss and causes soil nutrient impoverishment.