紫色土磷素流失的环境风险评估-土壤磷的“临界值”

Environmental Risk Assessment about Purple Soil Phosphorus Loss-Its Phosphorus "Change-point"

采用室内培养的方法,研究了3种类型的紫色土旱地和淹水土壤磷素流失的环境阈值。结果表明:无论是淹水土壤或旱地生境,3种紫色土Olsen-P与CaCl2-P之间都存在一个"临界值",酸性、中性和钙质紫色土磷素淋失临界点的Olsen-P含量分别为67.2、85.8和113.8 mg kg-1。淹水土壤磷素环境敏感值在酸性、中性和钙质紫色土上,Olsen-P含量分别为49.2、77.9和92.1 mg kg-1。3种紫色土在淹水还原条件下土壤磷环境敏感临界值比旱地低,淹水还原条件提高了紫色土磷向水体释放的风险。淹水土壤Olsen-P含量与田表水TP、DP浓度之间存在"临界值",酸性、中性和钙质土临界值处土壤Olsen-P含量分别为(65±1.41)mg kg-1(、96.7±2.7)mg kg-1和(105.5±1.1)mg kg-1。土壤0.01 mol L-1 CaCl2-P与田表水TP、DP之间呈极显著的线性关系。可以利用这些指标对紫色土区域土壤磷环境风险进行评价,并确定区域磷肥的最佳管理策略。

The indoor experiment was conducted on three types of purple soils.The environmental threshold of soil phosphorus loss was studied in dry and paddy fields.The results showed that,whether it was rice or dry land habitat,three kinds of purple soil Olsen-P and CaCl2-P existed between a ＂change-point＂.Three kinds of purple soil phosphorus leaching thresholds varied greatly.Acid,neutral and calcareous purple soil phosphorus leaching critical point of the Olsen-P contents were respectively 67.2,85.8,and 113.8 mg kg-1.The change-points were 49.2,77.9,and 92.1 mg kg-1 on the acid,neutral and calcareous purple soil,respectively.The change-points of three kinds of purple soil in flooded conditions were lower than in dry land,increased the risk soil phosphorus releasing to water.There was a change-point between paddy soil Olsen-P content and surface water TP,DP concentration.The change-points of acid,neutral and calcareous soil were 65 ± 1.41 mg kg-1,96.7 ± 2.7 mg kg-1,and 105.5 ± 1.1 mg kg-1 on soil Olsen-P contents,respectively.0.01 mol L-1 CaCl2-P soil extraction and the surface water TP,DP were among the most significant linear relationship.These indexes could be used on the purple soil region to evaluate environmental risk of soil phosphorus and to determine the best management strategy of regional phosphate.