磷石膏改良石灰土对不同品种牧草吸收Cd的影响及风险评价

Effect of Phosphogypsum-improved Lime Soil on Cd Uptake of Different Forages and Its Risk Evaluation

通过对贵州省中部喀斯特山区种植牧草的耕地进行调查并采集土壤进行盆栽试验,探讨磷石膏施用改良石灰土对牧草生长的影响及其Cd污染风险进行评价。结果表明:在土壤Cd含量高出农用地筛选值的耕地上种植的6种牧草中,菊苣Cd含量及生物富集系数均显著地高于高羊茅、燕麦、黑麦草、紫花苜蓿、白三叶;禾本科牧草Cd含量显著地比豆科牧草高,但二者之间Cd的生物富集系数未出现明显的差异,且6种牧草Cd含量均未超过《饲料卫生标准》中植物性饲料原料的限值。石灰土施用磷石膏后6种牧草的地上生物量提高了8.31%~22.09%,但牧草植株Cd的含量增加了15.96%~193.54%,虽然菊苣Cd含量的增加量较小,但Cd含量水平达到警戒及污染风险等级。利用磷石膏改良石灰土种植牧草时,可以优先选择低镉累积的紫花苜蓿、白三叶,其次是黑麦草,从而减少牧草植株Cd的污染风险。

By investigating the cultivated land planting forage in the Karst mountainous area of central Guizhou and collecting soil for pot experiment,the effect of phosphogypsum-application to improve lime soil on the growth of forage grass and the risk of Cd pollution were evaluated.The results showed that six species of forage grass were planted on the cultivated land,whose soil Cd content was higher than the screening value of agricultural land,the Cd content and bioconcentration coefficient of chicory plants were significantly higher than those of tall fescue,oats,ryegrass,alfalfa,and white clover.The Cd content of gramineae grass was significantly higher than that of legumes grass,but there was no significant difference in the bioconcentration coefficient of Cd between the two.And the Cd content of the six forage grass grown on high cadmium soil did not exceed the Limits for plant-based feed ingredients.After applying phosphogypsum to the lime soil,the aboveground biomass of six forage grass were increased by 8.31%~22.09%,but the Cd content of these were increased by 15.96%~193.54%.Although the increase of the Cd content of chicory plants was small,the Cd content level was reached the alert and pollution risk level.In words,when using phosphogypsum to improve calcareous soil for growing forage grass,alfalfa and white clover with low cadmium accumulation were preferentially choose,followed by ryegrass,thereby reducing the risk of Cd contamination for forage grass.