Ge Ying, Murray Patricia, Sauvé Sébastien, Hendershot William
Department of Natural Resource Sciences, McGill University, Ste-Anne-de-Bellevue, Québec, Canada.
Environ Toxicol Chem. 2002 May;21(5):954-61.
Bioavailability of Cd, Cu, Ni, Pb, and Zn in a metal-enriched railway yard in Montréal, Québec, Canada was assessed using metal speciation, plant uptake, and microbial assays. Metal speciation of extracted soil solutions was estimated using the Windmere Humic Aqueous Model. In soil solutions, free Cd, Ni, and Zn ions represented as much as 80%, 72%, and 62%, respectively, of the total dissolved metals. Copper and Pb were strongly bound by dissolved organic matter, and metal-fulvic acid complexes represented as much as 99% of the total dissolved metals. Three field-collected plant species (dandelion, bladder campion, and chicory) varied in their tendency to accumulate metals in either their leaves or roots. Chicory grown in the greenhouse had significantly higher metal bioconcentration factors than wild chicory. Although the site studied is considered to be contaminated, no metal pool, such as free ions or dissolved or total soil metals, consistently predicted metal uptake by potted chicory. Regression analysis revealed that soil total metal concentrations could adequately predict tissue accumulations of Cd, Ni, Pb, and Zn in bladder campion but only Cd and Zn in dandelion. Data from microbial assays also showed that the soil respiration was not affected by the metal contamination, but that nitrification was inhibited for the most contaminated soils. These results indicate that the metal bioavailability in the railway yard is low, but they also suggest that nitrogen cycling may be affected.
利用金属形态分析、植物吸收和微生物分析方法，对加拿大魁北克省蒙特利尔一个金属富集的铁路调车场中镉、铜、镍、铅和锌的生物有效性进行了评估。采用温德米尔腐殖酸水模型估算了提取的土壤溶液中的金属形态。在土壤溶液中，游离镉、镍和锌离子分别占总溶解金属的80%、72%和62%。铜和铅与溶解有机物强烈结合，金属-富里酸络合物占总溶解金属的99%。三种野外采集的植物物种（蒲公英、膀胱蝇子草和菊苣）在叶片或根部积累金属的倾向各不相同。温室中种植的菊苣的金属生物富集系数显著高于野生菊苣。尽管所研究的场地被认为受到了污染，但没有一种金属库，如游离离子、溶解态或土壤总金属，能够持续预测盆栽菊苣对金属的吸收。回归分析表明，土壤总金属浓度能够充分预测膀胱蝇子草中镉、镍、铅和锌的组织积累，但只能预测蒲公英中镉和锌的积累。微生物分析数据还表明，土壤呼吸不受金属污染的影响，但对于污染最严重的土壤，硝化作用受到抑制。这些结果表明，铁路调车场中的金属生物有效性较低，但也表明氮循环可能受到影响。
