石灰质复合调理剂对中碱性镉污染稻田的修复效果

Composite Calcareous Conditioners Remediate the Alkaline Paddy Soil Contaminated by Cadmium

为探究石灰质材料(生石灰和石灰石粉)与枯饼肥、海泡石复配对中碱性镉污染稻田的修复效果,通过田间小区试验,研究了石灰质复合材料与枯饼肥、海泡石的不同组配方式对土壤pH值、有效态镉含量及糙米镉含量的影响,并进行效益分析。结果表明:石灰质复合调理剂主要是通过提升土壤酸碱度,降低土壤有效态镉含量,从而降低水稻对镉的吸收积累。石灰质2复合材料(生石灰∶石灰石粉=1∶2)3600 kg/hm合理搭配枯饼肥、海泡石的复合调理剂,可显著提高土壤pH值0.47~0.67个单位,显著降低土壤有效态镉含量34.71%~44.94%,显著降低糙米镉含量39.60%~53.47%,且其作用效果随调理剂用量的增加而提高。复合调理剂还具有显著的增产效果,增产幅度达1.75%~10.59%,其增产效果主要受枯饼肥用量的影响。成本效益分析结果表明,降镉1%新增成本随糙米降镉率呈先下降后上升的趋势,但糙米降镉率与修复成本呈报酬递减规律。综合考虑糙米降镉效果和成本,生石灰(1200 kg/hm^(2))+石灰石粉(2400 kg/hm^(2))+海泡石(1500 kg/hm^(2))可推荐为最佳复合调理剂。

Calcareous materials(quicklime and limestone powder)were mixed with seed meal and sepiolite at different ratios to prepare composite calcareous conditioners,which were then used to remediate the alkaline paddy soil contaminated by cadmium.Field plot experiments were conducted to study the effects of the composite calcareous conditioners on soil pH,available cadmium content in soil,and cadmium content in brown rice.Furthermore,the cost and benefit of cadmium reduction were analyzed.The results showed that composite calcareous conditioners reduced the content of available cadmium in soil by increasing soil pH,thus reducing the absorption and accumulation of cadmium in rice.The calcareous materials(quicklime:limestone powder=1∶2)applied at 36002 kg/hm with seed meal and sepiolite increased the soil pH by 0.47-0.67,reduced the soil available cadmium by 34.71%-44.94%,and decreased the cadmium content in brown rice by 39.60%-53.47%.Moreover,the effects enhanced with the increase in the application rate.Furthermore,the composite calcareous conditioners increased the rice yield by 1.75%-10.59%,and the yield-increasing effect was affected by the amount of seed meal.The results of cost-benefit analysis showed that the cost for 1%reduction of cadmium in brown rice first decreased and then increased with the increase of the cadmium reduction rate in brown rice.The benefit decreased as the cadmium reduction rate in brown rice and the remediation cost increased.Considering the effect and cost of cadmium reduction in brown rice,the optimal formula of the composite calcareous conditioner was recommended as quicklime(1200 kg/hm^(2))+limestone powder(2400 kg/hm^(2))+sepiolite(1500 kg/hm^(2)).