我国3种自然土壤中稀有金属的化学形态分布特征研究

以我国3种典型土壤黑土、潮土和红壤为研究对象,在相对清洁未扰动自然土壤区域采集了土壤的剖面样品,分析了土壤中的稀有金属银(Ag)、铋(Bi)、铟(In)、锡(Sn)的含量水平,利用元素富集率(ER)的垂向分布探讨了外源污染对金属含量的影响,并采用连续逐级提取法研究了土壤中稀有金属的化学形态分布特征,用金属可交换态和碳酸...

Chemical Speciation of Rare Metals in Three Natural Soils of China

Soil profile samples of isohumosol, primosol, and ferrosol were obtained in relatively clean areas of China. Concentrations and chemical speciation of rare metals e.g., Ag (Silver), Bi (Bismuth), In (Indium) and Sn (Tin)] were determined, in which sequential extraction was used to fraction metals. Vertical distributions of elemental enrichment ratios (ERs) were used to study the anthropogenic influence. The mobility of metals was characterized by the sum of exchangeable form and carbonate-bound form. Average concentrations of Ag, Bi, In and Sn in the A horizon were (0.14 +/- 0.01), (0.49 +/- 0.09), (0.050 +/- 0.01), and (2.8 +/- 0.9) mg x kg(-1), respectively. The ERs were close to 1. Average distributions of metal speciation were: Ag, residual (65.8%) > H202-extractable organically bound (H2O2-Org) (25.9%) > Amorphous metal oxide-bound (am-MeOx) (4.2%) > Metal-organic complex-bound (Me-Org) approximately Crystalline Fe oxide-bound (cr-FeOx) (2.0%); Bi, residual (29.2%) > H2O2-Org (27.1%) > cr-FeOx (22.7%) > am-MeOx (18.8%) > Me-Org (1.0%) > carbonate-bound (0.9%) > easily reducible metal oxide-bound (re-MeOx) (0.3%); In, residual (67.8%) > cr-FeOx (17.0%) > am-MeOx (6.8%) > H2O2-Org (6.0%) > carbonate-bound (1.4%) > Me-Org (1.0%); Sn, residual (58.1%) > am-MeOx (23.0%) > cr-FeOx (15.6%) > H2O2-Org (1.8%) > Me-Org (1.1%) > exchangeable approximately carbonate-bound (0.2%). the results indicated that the exogenous elements enrichment was deficiency to minimal, and the concentrations of the rare metals were close to background values of soil in studied areas. Rare metals were stable in soils. The mobility of metals was in the order In > Bi > Sn > Ag.