Espinosa E, Armienta M A
Universidad Nacional Autónoma de México, Posgrado en Ciencias del Mar y Limonología, México, D.F.
J Environ Sci Health A Tox Hazard Subst Environ Eng. 2007 Aug;42(10):1391-401. doi: 10.1080/10934520701480474.
The impact of mining wastes on both the concentration and environmental mobility of Zn, Pb and Fe was studied in a shallow river. The studied tributary of the Taxco river is located south of the historical Ag, Zn, Cu and Pb mining area of Taxco, about 150 km south of México City. Methodology included total concentration determinations and sequential extraction analyses of the operational defined fractions of sediments. Results indicated that Fe, Pb and Zn concentrations are up to 5, 100 and 390 times respectively, greater than regional background concentrations. Higher contents of Pb and Zn were observed in the rainy season versus the dry season, whereas Fe was lower in the rainy season. Zinc and lead increased downflow in the dry season, and did not show any trend during the rainy season. Speciation showed that Zn was mainly linked to the carbonatic fraction (25-39%), to the hydrous Fe/Mn oxides fraction (15-25%) and to the organic matter and sulfide fraction (14-48%); lead was mainly associated to the hydrous Fe/Mn oxides (49-59%) and residual (22-39%) fractions; finally, iron was contained mainly in the residual (65-78%) and the hydrous Fe/Mn oxides fraction (15%). Mobility decreased according to the relation: Zn > Pb > Fe. Sediments were classified as strongly polluted in zinc, strongly to very strongly polluted in Pb, and moderately to strongly polluted in iron. However, a low proportion of metals in the exchangeable fractions, indicates low bioavailability. Limestone presence played a very important role on Zn and Pb fractionation and environmental mobility. Results show the importance of including geological background in river pollution studies.
在一条浅河中研究了采矿废弃物对锌、铅和铁的浓度及环境迁移性的影响。所研究的塔斯科河支流位于历史悠久的塔斯科银、锌、铜和铅矿区以南，距墨西哥城以南约150公里。方法包括沉积物操作定义组分的总浓度测定和连续提取分析。结果表明，铁、铅和锌的浓度分别比区域背景浓度高出5倍、100倍和390倍。雨季时铅和锌的含量高于旱季，而铁在雨季时含量较低。旱季锌和铅随水流向下游增加，雨季时则没有任何趋势。形态分析表明，锌主要与碳酸盐组分（25 - 39%）、水合铁/锰氧化物组分（15 - 25%）以及有机质和硫化物组分（14 - 48%）相关联；铅主要与水合铁/锰氧化物（49 - 59%）和残渣（22 - 39%）组分相关联；最后，铁主要包含在残渣（65 - 78%）和水合铁/锰氧化物组分（15%）中。迁移性按照锌＞铅＞铁的关系降低。沉积物被分类为锌重度污染、铅重度至极重度污染、铁中度至重度污染。然而，可交换组分中金属的比例较低，表明生物可利用性较低。石灰岩的存在对锌和铅的分馏及环境迁移性起着非常重要的作用。结果表明在河流污染研究中纳入地质背景的重要性。
