酸雨对含磷物质钝化修复的农田土壤磷流失的影响

为探讨酸雨对经不同含磷物质钝化修复的镉污染农田土壤磷流失和磷有效性的影响,本研究选用磷酸二氢钙(MCP)、磷酸二氢铵(MAP)和磷酸二氢钾(MKP)3种典型含磷物质对镉污染农田土壤进行室内钝化试验,在室温下培养3个月。采用两种类型硫酸型酸雨(SSAR)和混合型酸雨(SMAR)]、3种酸度(pH=3.0、4.0、5.6)的模拟酸雨(SAR)对钝化修复后土壤进行浸泡处理,并测定酸雨浸出液的总水溶性磷(TDP)和土壤的有效磷(AP)。结果表明:在各种酸雨条件下,MAP和MKP处理的土壤磷浸出率均显著高于对照组(CK),它们的磷浸出率分别达32.63%～38.57%和41.48%～49.29%,而MCP处理的磷浸出率与CK相比无显著差异。土壤磷浸出率随酸雨pH值的升高而降低,且SSAR处理的磷浸出率高于SMAR处理。3种含磷物质的添加均显著增加了土壤有效磷的含量,但在SAR处理后,土壤有效磷含量显著下降,且呈现MCPMAPMKP的规律。此外,SSAR处理的有效磷含量低于SMAR处理。因此,从土壤磷流失与磷有效性的角度考虑,MCP比MAP和MKP更适合于酸雨区镉污染农田土壤的钝化修复。

Effects of simulated acid rain on the leachability of phosphorus in agricultural soils amended with phosphorous compounds

This study evaluated the effects of simulated acid rain(SAR) on the leachability and availability of phosphorus(P) in cadmium (Cd) -contaminated agricultural soils amended with P compounds. Cd-contaminated soils were treated with calcium dihydrogen phosphate (MCP), ammonium dihydrogen phosphate(MAP), and potassium dihydrogen phosphate(MKP), and incubated for 3 months. These treatments were followed by two types of SARsulfuric acid rain(SSAR) and mixed acid rain(SMAR)] with three levels of acidity(pH=3.0, 4.0, and 5.6). The total water-soluble P(TDP) of the leachate and available P(AP) in the soils were determined. The results showed that the leachability of P in MAP- and MKP-stabilized soils was significantly higher than that in controls(CK), being 32.63%~38.57% and 41.48%~49.29%, respectively. However, there was no significant difference in P leachability between the MCP-stabilized soils and the CK. Leachability of P decreased with increasing SAR pH. Additionally, the leachability of P in the SSAR treatments was higher than that in the SMAR treatments. The application of the three P compounds significantly increased AP concentration in soils. However, the AP concentration in the three stabilized soils significantly decreased after SAR soaking, in the order of MCP > MAP > MKP. Additionally, the AP concentration in the SSAR treatment was lower than that in the SMAR treatment. Therefore, MCP is more suitable for passivation in Cdcontaminated agricultural soils in acid rain areas than MAP and MKP, according to the leaching risk and availability of P in soils.