磷灰石和石灰稳定化修复对污染土壤铜和镉垂直迁移的影响

Vertical Migration of Cu and Cd in Soils Immobilized by Lime and Apatite

大量改良材料被用于重金属污染土壤的稳定化修复,但是不同用量的改良材料长期田间修复后重金属总量和有效态在不同土层的垂直分布特征鲜有研究涉及。本研究采集不同剂量的磷灰石和石灰稳定化修复的0~13、13~30和30~50 cm土层污染土壤,考察铜和镉总量及有效态含量在不同土层的分布特征。结果表明:随着磷灰石和石灰用量的增加,显著降低了0~13 cm土层土壤交换性酸和交换性铝,增加了土壤全钙的含量,且磷灰石处理提高了土壤全磷和速效磷含量。0~13 cm土层土壤pH、总铜和总镉含量均随着磷灰石和石灰用量的增加而逐渐增加,但是降低了13~30和30~50 cm土层土壤总铜和总镉含量。3个土层中铜和镉有效态含量均随着磷灰石和石灰用量的增加而显著降低,其中23.2 g/kg磷灰石处理和4 g/kg石灰处理土壤有效态铜含量降低85.1%和92.0%,有效态镉降低18.8%和23.5%。相关性分析表明,土壤pH和铜镉总量是影响铜镉有效性的主要因素。可见,磷灰石和石灰的应用使铜和镉较好地固定在土壤表层,减少铜和镉向下层土壤的淋溶,降低了铜和镉的有效性。

Considerable amounts of amendments have been applied to remediate heavy metal-contaminated soils, but little information is available on the vertical migration of total and available heavy metals during long term immobilization with amendments. In this study, soils at the depths of 0-13, 13-30 and 30-50 cm were collected under the different dosages of apatite and lime, and the vertical migration of total Cu and Cd and their availability were investigated. Results showed that the applications of apatite and lime significantly decreased the exchangeable acid and aluminum in 0-13 cm soil and increased total Ca, and apatite application enhanced the contents of total and available Pin soils. With the increase of the dosages of apatite and lime, pH and total Cu and Cd contents in 0-13 cm soil increased gradually, but the total Cu and Cd contents in 13-30 and 30-50 cm soils decreased. Available Cu and Cd at three depths all decreased with increasing the dosages of apatite and lime. Available Cu decreased by 85.1% and 92.0% in 23.2 g/kg apatite and 4 g/kg lime amended soils, and available Cd decreased by 18.8% and 23.5%, respectively. Correlation analysis indicated that soil pH and total Cu and Cd were the main factors influenced the available Cu and Cd. In summary, the applications of apatite and lime can effectively immobilize Cu and Cd in the topsoil and reduce Cu and Cd availability and leaching downward.