Kahru Anne, Ivask Angela, Kasemets Kaja, Põllumaa Lee, Kurvet Imbi, François Matthieu, Dubourguier Henri-Charles
National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, Tallinn 12618, Estonia.
Environ Toxicol Chem. 2005 Nov;24(11):2973-82. doi: 10.1897/05-002r1.1.
The combined chemical and ecotoxicological hazard evaluation study was conducted on 60 smelter-influenced soils containing 1 to 13, 50 to 653, and 100 to 1,198 mg/kg of Cd, Pb, and Zn, respectively. For these soils (liquid-to-soil ratio = 10), water extractability of Zn, Cd, and Pb was less than 0.19% (median values). Acetic acid (0.11 M) extracted 23, 9.7, and 0.7% of Cd, Zn, and Pb, respectively. Although heavy metal concentrations in the studied soils were high, the toxic effects of water extracts were observed only in few samples and in few biotests (algae Selenastrum capricornutum and metal detector assay). For most of the aquatic test organisms (e.g., crustaceans, photobacteria), the bioavailable concentrations of metals in soil-water extracts were either subtoxic, or the adverse effects were compensated by soil nutrients, etc. However, analysis of the soils with recombinant Cd sensor Bacillus subtilis (pTOO24) showed that about 65% of these apparently subtoxic samples contained bioavailable Cd when analyzed in the suspension assay (detection limit 1.5 mg Cd/kg soil), indicating the desorption of Cd induced by direct contact of bacteria with soil particles. The median bioavailable fraction of Cd (1%) was 23-fold lower than the fraction extracted by acetic acid. The Pb-Cd sensor Staphylococcus aureus (pT0024) detected bioavailable Pb only in the suspensions of five of the most lead-polluted soils (>417 mg Pb/kg): the median bioavailability of Pb was 0.42%. Consequently, the hazard assessment relying on total metal levels in soils should be revised by critical comparison with data obtained from bioassays. Development and use of biosensors (excellent tools for mechanistic studies and signaling hazard already at subtoxic level) should be encouraged.
对60份受冶炼厂影响的土壤进行了化学和生态毒理学联合危害评估研究，这些土壤中镉、铅和锌的含量分别为1至13毫克/千克、50至653毫克/千克和100至1198毫克/千克。对于这些土壤（液土比 = 10），锌、镉和铅的水提取率低于0.19%（中位数）。0.11 M的乙酸分别提取了23%、9.7%和0.7%的镉、锌和铅。尽管所研究土壤中的重金属浓度很高，但仅在少数样品和少数生物测试（藻类羊角月牙藻和金属探测器测定）中观察到水提取物的毒性作用。对于大多数水生测试生物（如甲壳类动物、发光细菌），土壤 - 水提取物中金属的生物可利用浓度要么低于毒性水平，要么不利影响被土壤养分等抵消。然而，用重组镉传感器枯草芽孢杆菌（pTOO24）对土壤进行分析表明，在悬浮试验（检测限为1.5毫克镉/千克土壤）中分析时，约65%这些明显低于毒性水平的样品含有生物可利用的镉，这表明细菌与土壤颗粒直接接触会导致镉的解吸。镉的生物可利用中位数分数（1%）比乙酸提取的分数低23倍。铅 - 镉传感器金黄色葡萄球菌（pT0024）仅在五种铅污染最严重的土壤（>417毫克铅/千克）的悬浮液中检测到生物可利用的铅：铅 的生物可利用中位数为0.42%。因此，依靠土壤中总金属含量的危害评估应通过与生物测定获得的数据进行关键比较来修订。应鼓励开发和使用生物传感器（用于机理研究和在低于毒性水平时发出危害信号的优秀工具）。
