卡拉麦里南部工业区梭梭和琵琶柴重金属空间分布及污染评价

对五彩湾工业区周边21个采样点的梭梭(Hadoxylon)和琵琶柴(Reaummuria soongorica)的Zn、Cu、Cr、Pb、As、Hg 6种重金属元素含量测定,运用统计学方法和地统计插值法分析其茎叶和根部重金属含量变化情况和空间分布特征,并综合评价其污染程度和潜在生态危害性。结果表明:梭梭和琵琶柴植株Hg含量的最大值和均值都超出新疆土壤背景值0.017 mg/kg,除梭梭根部的均值0.060 mg/kg未超出国家土壤背景值0.065 mg/kg,在二者其他部位的最大值和均值都已超出;琵琶柴整株中Cr最大值72.62 mg/kg和Zn最大值97.61 mg/kg均超出新疆土壤背景值49.3 mg/kg和国家土壤背景值61 mg/kg,Pb元素未被检出。插值精度方面,Hg、As的RMSE较小,分别为0.263和0.443,预测模型中Hg的R~2为0.72,Cu的R~2为0.67,能较好地估计预测样点的重金属含量,Zn的R~2为0.31,精度较低;插值结果,琵琶柴中的Zn、Cr、As、Hg含量较高的区域均在工业园区内部及周围,受人为扰动程度较大。梭梭和琵琶柴中Hg元素分别为中度污染和重度污染;Hg元素为中等潜在危害程度高于其他4种元素。

Heavy metal spatial distribution and contamination assessment of Hadoxylon and Reaummuria soongorica in an industrial area south of Kalamali

Hadoxylon and Reaummuria soongorica, two species of desert vegetation that occur near Juggar coal, were studied. Six kinds of heavy metals were detected in them, including Zn, Cu, Cr, Pb, As, and Hg. Conventional statistics and geostatistical analysis methods were used to determine the spatial distribution characteristics of heavy metals. The heavy metals in plants were assessed by the Nemerow integrated index to understand the current pollution status and potential ecological risk. The results suggested that maximum Hg (0.224 mg/kg), mean Hg (0.069 mg/kg) in stems and leaves, and mean Hg (0.215 mg/kg) in roots of Hadoxylon were all higher than the national baseline value in soil (0.065 mg/kg). Its maximum (0.92 mg/kg) and mean (0.066 mg/kg) in stems and leaves, and maximum (0.637 mg/kg) and mean (0.072 mg/kg) in roots of Reaummuria soongorica indicated similar results. In the whole body of Reaummuria soongorica, maximum Cr (72.62 mg/kg) and that of Zn (97.61 mg/kg) were higher than the soil baseline in Xinjiang (49.3 mg/kg) and nationally (61 mg/kg). Pb was not found. Interpolated precision was better for Hg and Cu, but worse for Zn. Spatial analysis of Reaummuria soongorica revealed that Zn, Cr, As, and Hg exhibited large artificial disturbances. Hg moderately contaminated Hadoxylon and mildly contaminated Reaummuria soongorica. Zn in stems and leaves of Reaummuria soongorica was a potential risk, whereas the others were in the safe range. It is worth mentioning that Hg was at a moderately hazardous level, higher than the other four elements. Over time, research into metal pollution in plants will be intensified.