滇西某油用牡丹种植区镉铅污染及钝化修复效果评估

Assessment on Cd and Pb Pollution and Remediation by Chemical Stabilization in Oil Peony Planting Land in West Yunnan Province

油用牡丹是一种新型的木本食用油料植物,其在重金属污染耕地上的生产安全性鲜有报导。本文对云南西部某矿区周边油用牡丹种植区的土壤和植物镉(Cd)、铅(Pb)污染状况进行调查,并结合田间小区试验探讨中重度污染耕地化学钝化修复的可行性。结果表明,油用牡丹种植区的土壤和植物可食部分存在严重的Cd、Pb污染,土壤全量Cd、Pb较风险筛选值(GB 15618—2018)的超标率分别为100%和82.8%;油用牡丹籽粒中Cd和Pb含量超标率高达100%和82.1%(GB 2762—2017),中药材牡丹皮中Cd超标率也高达77.1%以上。钝化修复显著提高了中重度污染耕地上油用牡丹根系生物量和根长,但对其成活率和株高无显著影响。生石灰和海泡石复合钝化剂施用显著降低了土壤CaCl2提取态Cd、Pb含量,降幅在56%和59%以上,且随着钝化剂用量的增加钝化效果显著增强。虽然钝化修复显著降低了重度污染土壤上牡丹皮Cd含量,但牡丹皮Cd含量仍存在较高的超标风险。为保证中重度污染耕地的油用牡丹生产安全性,应提高钝化剂施用量以持续降低污染土壤中重金属有效性,并加强土壤和农产品Cd、Pb的协同监测。

Oil peony(Paeoniasuffruticosa Andr.)is the new woody edible oil plant in China,but the safe production of oil peony growing in heavy metal polluted soil is still unclear.In this study,a survey of cadmium(Cd)and lead(Pb)pollution in oil peony planting land around a mining area in west of Yunnan Province was conducted,and the field experiments were also carried out to study the feasibility of chemical stabilization remediation for safe production of oil peony in moderately and severely polluted soils.The survey results showed that Cd and Pb pollution were very serious in the soils and plant edible parts of oil peony planting land,and there were 100%and 82.8%soil samples with Cd and Pb concentrations exceeding the risk screening value(GB 15618—2018),respectively.Due to the serious soil pollution,Cd and Pb concentrations in oil peony seeds and Cd concentration in peony barks sampled from the polluted soils all had high exceeding rates.In the moderately and severely polluted soils,chemical stabilization remediation had no significant effects on the survival rate and plant height of oil peony,but increased the root biomass and root length of oil peony.The combined application of lime and sepiolite decreased soil CaCl2 extracted Cd and Pb concentrations by 55.8%and 59.2%,respectively,and the efficiency of stabilization increased with the dosage of stabilizing agents.No significant differences was found in Pb concentrations in peony bark,but soil remediation decreased Cd concentration in peony bark significantly.However,Cd concentration in peony bark was still high in the severely polluted soils after remediation.Thus,more stabilizing agent should be applied to ensure the safe production of oil peony in moderately and severely polluted soils,and the cooperative monitoring of Cd and Pb in soil and agricultural products should be enhanced.