熟石灰对土壤Cd、Pb、As含量及水稻重金属累积的影响

Effects of Slaked Lime on Cd,Pb and As Content in Soil and Heavy Metal Accumulation in Rice

【目的】探明施用熟石灰条件下稻田土壤重金属Cd、Pb和As含量及其水稻不同器官对重金属的富集能力,为熟石灰在重金属污染治理中的应用提供参考。【方法】通过田间试验,以不添加熟石灰处理为对照(CK),研究熟石灰不同添加量处理(低量1500 kg/hm^(2)、中低量3000 kg/hm^(2)、中量4500 kg/hm^(2)、中高量6750 kg/hm^(2)和高量9750 kg/hm^(2))水稻产量及土壤性质的变化,并分析水稻不同生育期各器官Cd、Pb和As重金属的动态含量。【结果】熟石灰施用量在1500~6750 kg/hm^(2),随施用量增加土壤pH和有效磷含量不断提高,碱解氮和速效钾含量逐渐下降;熟石灰施用量≥6750 kg/hm^(2)时土壤有效态Cd和Pb含量的降低效果最为显著,同时有效态As含量最高。水稻根、茎秆、叶片及糙米对Cd、Pb和As的累积随熟石灰用量增加而逐渐降低,当熟石灰施用量≥4500 kg/hm^(2)时糙米Cd、Pb和As含量在安全利用范围。糙米中Cd、Pb和As含量与土壤有效态Cd、Pb含量呈极显著或显著正相关,与土壤有效态As含量存在显著负相关。【结论】熟石灰施用量4500~6750 kg/hm^(2)可有效降低土壤重金属有效态含量,减少水稻各器官对土壤中重金属的积累,降低稻米中重金属含量,从而实现耕地安全利用。

【Objective】The effects of slaked lime on Cd,Pb and As content in paddy soil and heavy metal enrichment capacity of different rice organs at different growth stages are discussed to provide a reference for slaked lime application in heavy metal pollution control.【Method】The rice yield,soil properties and dynamic variation of Cd,Pb and As content in different rice organs at different growth stages under six treatments(CK,1500 kg/hm^(2)slaked lime,3000 kg/hm^(2)slaked lime,4500 kg/hm^(2)slaked lime,6750 kg/hm^(2)slaked lime and 9750 kg/hm^(2)slaked lime)are analyzed by a field test.【Result】The soil pH and available P content increase continually but soil available N and rapid available K content decreases gradually with increase of slaked lime amount when slaked lime amount is 1500-6750 kg/hm^(2).The soil effective Cd and Pb content significantly reduces but soil effective As content reaches the highest when slaked lime amount is more than 6750 kg/hm^(2).The Cd,Pb and As accumulation in root system,stem,leaf and brown rice decrease gradually with increase of slaked lime amount.The Cd,Pb and As content in brown rice is within the safe utilization range when slaked lime amount is≥4500 kg/hm^(2).The Cd,Pb and As content in brown rice is positively related to soil effective Cd,and Pb content very significantly or significantly,and negatively related to soil effective As content significantly.【Conclusion】Applying 4500~6750 kg/hm^(2)of slaked lime can reduce content of effective heavy metals in soil effectively,decreases accumulation of heavy metals in different organs of rice and reduce content of heavy metals in brown rice,which can realize safe utilization of farmland effectively.