Zagury Gerald J, Neculita Carmen-Mihaela, Bastien Christian, Deschênes Louise
Department of Civil, Geological and Mining Engineering, Ecole Polytechnique de Montréal, P.O. Box 6079, Station Centre-ville, Montreal, Quebec H3C 3A7, Canada.
Environ Toxicol Chem. 2006 Apr;25(4):1138-47. doi: 10.1897/05-302r.1.
Mercury (Hg) fractionation, speciation, bioavailability, and ecotoxicity were investigated in three highly contaminated soils from chlor-alkali plants. Single extractions and a validated four-step sequential extraction scheme were used. Total, volatile, and methyl-Hg concentrations were determined. Mercury was then separated in fractions defined as water-soluble (F1), exchangeable (F2), organic (F3), and residual (F4). Germination and growth inhibition of barley (Hordeum vulgare) and mortality of earthworms (Eisenia andrei) were assessed, and tissue-Hg concentrations of exposed organisms were determined. Results revealed highly (295 +/- 18-11,500 +/- 500 microg Hg/g) contaminated soils, but extracted fractions indicated relatively low mobility of Hg. Nevertheless, the water-soluble and the CaCl2-extractable fractions represented significant Hg concentrations (299 +/- 18 microg/g in soil 3, 67.4 +/- 2.3 microg/g in soil 1, and 9.5 +/- 0.3 microg/g in soil 2), and volatile Hg ranged between 14 and 98% of total Hg. Overall, Hg concentrations reached 6,560 +/- 240 microg/g in roots, 4,200 +/- 1,070 microg/g in aerial plants, and 1,410 +/- 120 microg/g in E. andrei. Earthworm mortality was 100% after exposure to the soil with the highest concentration of mobile Hg. In the latter soil, earthworm fragmentation and chlorotic plants were observed. Bioconcentration factors (BCFs) were higher in barley compared to earthworms, but BCFs yielded misleading values after exposure to the extremely contaminated soil. This study shows that Hg accumulated primarily in the roots, but results also indicate uptake of gaseous Hg by the aerial plants of barley. Tissue-Hg concentrations of both exposed organisms were correlated with water-soluble and CaCl2-extractable Hg, and growth inhibition was in agreement with Hg fractionation.
对来自氯碱厂的三种高度污染土壤中的汞（Hg）分级、形态、生物有效性和生态毒性进行了研究。采用了单次萃取和经过验证的四步连续萃取方案。测定了总汞、挥发性汞和甲基汞的浓度。然后将汞分离为水溶性（F1）、可交换性（F2）、有机态（F3）和残留态（F4）等组分。评估了大麦（Hordeum vulgare）的发芽和生长抑制情况以及蚯蚓（Eisenia andrei）的死亡率，并测定了暴露生物体内的组织汞浓度。结果显示土壤受到高度污染（295±18 - 11,500±500微克汞/克），但萃取得到的组分表明汞的迁移性相对较低。然而，水溶性和氯化钙可萃取组分中的汞浓度较高（土壤3中为299±18微克/克，土壤1中为67.4±2.3微克/克，土壤2中为9.5±0.3微克/克），挥发性汞占总汞的14%至98%。总体而言，大麦根系中的汞浓度达到6,560±240微克/克，地上部分为4,200±1,070微克/克，蚯蚓体内为1,410±120微克/克。暴露于移动汞浓度最高的土壤后，蚯蚓死亡率为100%。在该土壤中，观察到蚯蚓解体和植物黄化现象。大麦的生物富集系数（BCFs）高于蚯蚓，但暴露于极端污染土壤后，生物富集系数产生了误导性数值。本研究表明汞主要积累在根系中，但结果也表明大麦地上部分可吸收气态汞。两种暴露生物的组织汞浓度与水溶性和氯化钙可萃取汞相关，生长抑制情况与汞分级结果一致。
