杭州市居民区土壤磷的积累和释放潜力

土壤磷的积累会增加磷的流失潜力,影响环境质量.本文对杭州市49个居民区土壤的研究表明,大部分居民区土壤磷积累明显,平均总磷含量约为农业土壤的2倍.86%的居民区土壤的水可溶性磷含量超过10 mg/kg;59%的土壤磷饱和度超过25%(环境敏感临界指标).杭州市居民区土壤磷主要以HCl-P为主,占总磷的50%～60%.居民区土壤磷的积累和潜在释放能力随居民区年龄的增加而增加.模拟试验表明,当土壤pH下降至5.0(低磷土壤)或6.5(高磷土壤)时,土壤磷的释放迅速增加.当土壤总磷量超过1.2 g/kg时,可使土壤磷的饱和度超过25%,对环境产生潜在的负影响.

Accumulation and release potential of soil phosphorus in residential areas of Hangzhou city, China

Accumulation of phosphorus in soils increases the potential of P run off from the soils and thus affects environmental quality. In this study forty-nine soil samples from different residential areas in Hangzhou city, Zhejiang province were collected for analyzing forms and saturation degree of P, and investigating the accumulation and release potential of P in the soils. The Hedley fractionation scheme was used to divide soil P into water-soluble, NaHCO_3-soluble, NaOH-soluble, HCl-soluble and residual P. The results showed that soils of the residential areas in the city had been enriched with P to a great extent, mean total soil P in the residential areas was twice of that in agricultural land. About 86% of the residential soils had water soluble P higher than 10 mg/kg, and 59% of the soils had P saturation degree greater than 25%, an environmentally sensitive threshold. The soil P was mainly composed of HCl-P which accounted for 50%-60% of the total P. Most of the P (80%) in the soils could be extracted by water, NaHCO_3, NaOH and HCl. The accumulation and release potential of P in the soils increased with age increasing of the residential areas. It is suggested that soil may impose a significant negative influence on environment when its total P content exceeds 1.2 g/kg.