晋南铬渣堆场主要植物重金属富集特征

为筛选适合山西当地气候与土壤条件的重金属耐性植物,于山西某铬渣堆场采集草本植物及表层土壤(0~20cm)样品,从中选取6种主要植物品种,测定植物地上部分、根部及土壤中4种重金属(Cu、Zn、Pb和Cr)含量,分析6种植物对重金属的富集特征。结果表明:铬渣堆场土壤Cr污染严重,平均质量浓度为2207mg/kg,是山西省土壤背景值(58mg/kg)的38.1倍,是《土壤环境质量农用地土壤污染风险管控标准(试行)》(GB 15618-2018)规定风险筛选值(250mg/kg)的8.8倍。选取的6种植物中,狼尾草(Pennisetum alopecuroides(L.)Spreng.)、羊草(Leymus chinensis(Trin.)Tzvel.)和狗牙根(Cynodon dactylon(L.)Pers.)等植物体内Cr含量相对较高,表现出较强的Cr吸收能力。根据植物对重金属的吸收机制,羊草、狼尾草和狗牙根属于根部囤积性植物;狗尾草(Setaria viridis(L.)Beauv.)、虎尾草(Chloris virgate Sw.)和牛筋草(Eleusine indica(L.)Gaertn.)属于Cr规避型植物。

Heavy metal enrichment characteristics of dominant plants naturally growing on chromium residue dump site in southern Shanxi

In order to select heavy metal tolerant plants that suitable for climate and soil conditions of Shanxi Province,some herbages and surface soil(0-20 cm)samples were collected from a chromium residue dump site.Among the herbage samples,6 dominant species were chosen and the heavy metal contents(Cu,Zn,Pb and Cr)in the above-ground and underground parts of plants and soil were determined,and the enrichment characteristics of heavy metals in six plants were analyzed.The results showed that Cr was the most serious contamination in the soil around the chromium residue dump site,with an average content of 2 207 mg/kg,which was 38.1 times of the background value of Shanxi soil(58 mg/kg)and 8.8 times of the risk screening values(250 mg/kg)of"Soil environmental quality risk control standard for soil contamination of agricultural land"(GB 15618-2018).Among the six main plants collected,Pennisetum alopecuroides(L.)Spreng.,Leymus chinensis(Trin.)Tzvel.,and Cynodon dactylon(L.)Pers.had relatively high Cr content,showing a strong absorption capacity.According to the uptake mechanism of heavy metals by plants,Pennisetum alopecuroides(L.)Spreng.,Leymus chinensis(Trin.)Tzvel.and Cynodon dactylon(L.)Pers.belonged to root compartment plants,while Setaria viridis(L.)Beauv.,Chloris virgate Sw.and Eleusine indica(L.)Gaertn.belonged to Cr excluders plants.