基于籽粒Cd消减率与边际效率评价Cd污染稻田的修复效果

Remediation effect of Cd polluted paddy soil evaluated by grain Cd reduction rate and marginal efficiency

高效、低成本钝化材料的研发及盆栽与田间试验结果的一致性仍然是目前重金属污染土壤原位钝化修复的技术难点。该文以镉(Cd)污染的湖南红壤与浙江水稻土为对象,以2种不同Cd敏感性水稻(Cd低吸收品种JH212、Cd高富集品种XS09)为试材,通过盆栽与田间对比试验,基于水稻籽粒Cd消减率、修复边际效率及土壤中Cd有效态含量的变化等对不同钝化剂的修复效果进行了测定。结果表明:不同钝化剂对2种不同Cd敏感性水稻籽粒Cd的吸收、转运均有显著(P<0.05)降低作用。盆栽试验条件下,与对照相比,不同钝化剂处理后湖南红壤中水稻籽粒Cd浓度最大降低65.3%,浙江水稻土中籽粒Cd浓度最大降低61.4%;在田间试验条件下,不同钝化剂处理的红壤中水稻籽粒Cd浓度最大降低61.8%,水稻土中籽粒Cd浓度最大降低60.1%。就2种不同的Cd敏感性水稻品种而言,不同钝化剂对Cd高富集品种XS09的钝化效果要优于Cd低吸收品种JH212。总体而言,不同钝化剂对2种不同Cd敏感性水稻籽粒Cd消减率为41.6%~65.3%,对XS09的籽粒Cd消减率略高于JH212,在酸性红壤的钝化效果高于水稻土;不同钝化剂对水稻籽粒Cd消减效果依次为黏土矿物钝化剂AT>腐殖质钝化剂WG≈岩基钝化剂FS。不同钝化剂对Cd污染红壤与水稻土的修复边际效率为9.10%~15.4%,最高为AT处理,其次为WG与FS处理;综合籽粒Cd消减率与修复边际效率2个指标进行考虑,不同钝化剂对Cd污染土壤的修复效果顺序为AT>WG>FS。

Cadmium(Cd)pollution in paddy soil is becoming an increasingly serious issue in China.A nationwide survey in China revealed that Cd is the most frequently detected heavy metal in soil and7%of the investigated site soil is contaminated by Cd.Cadmium is accumulated in plants more readily than most other metals,and can be translocated into the edible parts(cereal grains)and causes health risk through the food chain.Numerous efforts have been paid for remediation of heavy metal polluted soil in China in past decades.In present,development of high efficiency and low cost remediation materials and keeping the consistency of pot and field experiments results are still the technical difficulties for in-situ remediation of heavy metal polluted soils.In this study,two rice cultivars characterized with Cd-sensitive cultivar(JH212)and Cd-enrichment cultivar(XS09)were used,and the red earth from Hunan province and paddy soil from Zhejiang province polluted by Cd were also collected for pot experiment,while the field validation experiment were simultaneously conducted to investigate the remediation efficiency of different amendments(including:amendment from rock foundation FS,clay mineral AT and humus WG)on Cd polluted soils,the remediation efficiency was evaluated by rice grain Cd reduction rate(%),the DTPA-extracted fraction of Cd in soil and remediation marginal cost.The results indicated that the Cd uptake and translocation by the rice cultivars were significantly(P<0.05)reduced by the soil amendment applications.For the pot experiment,compared with control(CK),the maximum Cd reduction rate of rice grain for the tested rice cultivars reached65.3%and61.4%for red earth from Hunan province and paddy soil from Zhejiang province,respectively.In field condition,the maximum Cd reduction rate of rice grain for the tested rice cultivars reached61.8%and60.1%,respectively for the above two type of polluted soils.In terms of the Cd-sensitive rice cultivars,higher remediation efficiency was generally observed for Cd-enrichment cultivar(XS09)than that for Cd-sensitive cultivar(JH212)for both soil types and culture condition(i.e.pot experiment and field validation experiment).In general,the rice grain Cd reduction rate reached41.6%-65.3%for the two rice cultivars compared with the control after amendments,and the rice grain Cd reduction rate for Cd-enrichment cultivar(XS09)were generally higher than that for Cd-sensitive cultivar(JH212),and the rice grain Cd reduction efficiency for red earth were generally higher(P<0.05)than that for paddy soil among the treatments.The remediation efficiency followed the order of AT>WG≈FS based on rice grain Cd reduction efficiency.The remediation marginal efficiency(RME)(defined as rice grain Cd reduction rate based on1500yuan cost per hectare)for the tested soils ranged from9.10%to15.4%.The highest RME was observed with AT,followed with WG and FS treatment.By considering the rice grain Cd reduction rate and remediation marginal efficiency,the remediation effect of Cd polluted soil for different amendments ordered as AT>WG>FS.