稳定化处理对底泥利用后土壤Cd形态及空心菜Cd含量的影响

采用大田试验,研究了石灰+钙镁磷肥、海泡石+磷酸二氢钙、单独使用钙镁磷肥3种不同的稳定剂组合对底泥土地利用后造成污染的农田土壤中Cd的稳定化处理效果以及对空心菜吸收Cd的影响。结果表明,3种稳定剂组合均能有效改变土壤中Cd的形态分布,弱酸提取态含量最大减少率54.43%,可还原态含量最大增加率81.90%,可氧化态含量最大增加率107.43%,残渣态含量最大增加率74.15%,稳定化效果明显。稳定化处理组的空心菜Cd含量显著低于对照组,减少率为38.61%~85.69%,且达到无公害蔬菜安全要求。不同污染水平下,稳定剂对空心菜中Cd浓度减少率的影响程度均为石灰+钙镁磷肥>钙镁磷肥>海泡石+磷酸二氢钙,与对土壤Cd弱酸提取态含量减少的影响一致。总体上讲,稳定剂可以有效修复轻微污染底泥利用带来的土壤Cd污染,确保种植空心菜的安全性。

Effects of Chemical Stabilization on Soil Cd Fractions and Water Spinach Cd Contents After Amendment with Dredged River Sediments

In situ stabilization is a low-cost, simple-operation and fast-effectiveness technique for remediating heavy metals-contaminated soils. In this study, a field trial was carried out to investigate the stabilization effects of three different amendment treatments(lime + calcium magnesium phosphate fertilizer, sepiolite+calcium dihydrogen phosphate, and calcium magnesium phosphate fertilizer alone) on soil Cd forms and bioavailability. The effectiveness of the treatments was evaluated by soil Cd fractions and Cd contents in water spinach. Results showed that amendments changed Cd fractions in treated soil. Compared with the control, the maximum reduction of acid extractable Cd fraction was 54.43%, while the increase percentages were as high as 81.90% for reducible fraction, 107.43% for oxidizable fraction, and 74.15% for residual fraction. Water spinach Cd contents were 38.61% to 85.69% lower in the stabilization treatments than in control, meeting the safety requirements for non-pollution vegetables. For all Cd levels, the reducing effect of stabilizers on water spinach Cd content was lime+calcium magnesium phosphate fertilizer > calcium magnesium phosphate fertilizer > sepiolite+calcium dihydrogen phosphate, which was consistent with acid extractable Cd in soil. In conclusion, soil amendments could effectively control the Cd pollution caused by sediment applications, ensuring the food safety of water spinach produce.