磷肥和稻草对土壤重金属形态、微生物活性和植物有效性的影响

Effects of Phosphate Fertilizer and Rice Straw on Soil Heavy Metal Fraction,Microbial Activity and Phytoavailability

采用原位化学固定法,通过向土壤中添加修复剂磷肥和稻草,研究其对土壤中重金属形态、植物有效性和土壤微生物活性的影响.结果表明:添加磷肥和稻草可改变土壤中重金属Cu、Cd、Zn和Pb的形态分布,使土壤中重金属高植物有效性的酸提取态比例降低;其中以磷肥+稻草组下降最多,酸提取态Cu比例从对照的50.4%降至8.7%,酸提取态Cd从56.2%降至29.5%,酸提取态Zn从32.9%降至25.1%,酸提取态Pb从21.1%降至检测限以下.磷肥、稻草及磷肥+稻草修复土壤后,4种重金属在油菜(Brassica napus L.)中的含量显著降低,且油菜干生物量由对照的0.46 g分别增至0.97、1.53和2.28 g.同时土壤中微生物活力得到提高,土壤微生物生物量碳由对照的19.16 mgkg最高增至966.71 mgkg,而代谢呼吸率由对照的21.95 mg(kg.h)最大升至158.63 mg(kg.h).证明磷肥和稻草可降低重金属对油菜和土壤微生物的毒性胁迫,改善污染土壤质量,促进植物和土壤微生物的生长.

The effects of phosphate fertilizer and rice straw on heavy metal chemical fractions,phytoavailability and soil microbial activity were investigated based on in-situ chemical fixation.The results showed that application of phosphate fertilizer andor straw to soil changed the chemical fractions of Cu,Cd,Zn and Pb,and decreased the proportion of acid-extractable fraction.Addition of the mixture of phosphate fertilizer and rice straw resulted in the greatest decline in proportion to acid-extractable fraction.The percentage of Cu acid-extractable fraction decreased from 50.4% in the control to 8.7%,Cd decreased from 56.2% to 29.5%,Zn decreased from 32.9% to 25.1% and Pb decreased from 21.1% to below the detection limit of AAS.Compared to the control,concentrations of Cu,Cd,Zn and Pb in Brassica napus decreased significantly after application of phosphate fertilizer,rice straw andor the mixture of phosphate fertilizer and rice straw,and their dry mass increased from 0.46 g in the control to 0.97,1.53 and 2.28 g,respectively.Additions of phosphate fertilizer,rice straw andor the mixture of both materials also improved soil microbial activity.Microbial biomass C increased from 19.16 mgkg in the control to 966.71 mgkg,and the respiration rate of microbes increased from 21.95 mg（kg·h） to 158.63 mg（kg·h）.The results indicated that the addition of phosphate fertilizer and straw to soil could reduce the toxicity of heavy metals to B.napus L and soil microorganisms,improve soil quality and accelerate the growth of plants and microbes.It could be used for heavy metal immobilization in soil.