Ahumada Inés, Escudero Paula, Carrasco M Adriana, Castillo Gabriela, Ascar Loreto, Fuentes Edwar
Facultad de Cs. Quimicas y Farmaceuticas. Universidad de Chile, Casilla 233, Santiago, Chile.
J Environ Monit. 2004 Apr;6(4):327-34. doi: 10.1039/b313272b. Epub 2004 Feb 16.
In Chile, the increasing number of plants for the treatment of wastewater has brought about an increase in the generation of sludge. One way of sludge disposal is its application on land; this, however involves some problems, some of them being heavy metal accumulation and the increase in organic matter and other components from sewage sludge which may change the distribution and mobility of heavy metals. The purpose of the present study was to determine the effect of sewage sludge application on the distribution of Cr, Ni, Cu, Zn and Pb in agricultural soils in Chile. Three different soils, two Mollisols and one Alfisol, were sampled from an agricultural area in Central Chile. The soils were treated with sewage sludge at the rates of 0 and 30 ton ha(-1), and were incubated at 25 degrees C for 45 days. Before and after incubation, the soils were sequentially extracted to obtain labile (exchangeable and sodium acetate-soluble), potentially labile (soluble in moderately reducing conditions, K4P2O7-soluble and soluble in reducing conditions) and inert (soluble in strong acid oxidizing conditions) fractions. A two-level factored design was used to assess the effect of sludge application rate, incubation time and their interaction on the mobility of the elements under study. Among the metals determined in the sludge, zinc has the highest concentration. However, with the exception of Ni, the total content of metals was lower than the recommended limit values in sewage sludge as stated by Chilean regulations. Although 23% of zinc in sludge was in more mobile forms, the residual fraction of all metals was the predominant form in soils and sludge. The content of zinc only was significantly increased in two of the soils by sewage sludge application. On the other hand, with the exception of copper, the metals were redistributed in the first four fractions of amended soils. The effect of sludge application rate, incubation time and their interaction depended on the metal or soil type. In most cases an increase in more mobile forms of metals in soils was observed as the final effect.
在智利，用于处理废水的工厂数量不断增加，导致污泥产量上升。污泥处置的一种方式是将其施用于土地；然而，这会引发一些问题，其中包括重金属积累以及污水污泥中有机物和其他成分的增加，这可能会改变重金属的分布和迁移性。本研究的目的是确定施用污水污泥对智利农业土壤中铬、镍、铜、锌和铅分布的影响。从智利中部的一个农业区采集了三种不同的土壤，两种软土和一种淋溶土。土壤分别以0和30吨/公顷的速率施用污水污泥，并在25℃下培养45天。培养前后，对土壤进行连续提取，以获得不稳定（可交换和乙酸钠可溶）、潜在不稳定（在适度还原条件下可溶、焦磷酸钾可溶和在还原条件下可溶）和惰性（在强酸氧化条件下可溶）部分。采用二级析因设计来评估污泥施用量、培养时间及其相互作用对所研究元素迁移性的影响。在所测定的污泥中的金属中，锌的浓度最高。然而，除镍外，金属的总含量低于智利法规规定的污水污泥推荐限值。尽管污泥中23%的锌以更易迁移的形式存在，但所有金属的残留部分在土壤和污泥中都是主要形式。仅在两种土壤中，施用污水污泥后锌的含量显著增加。另一方面，除铜外，金属在改良土壤的前四个部分中重新分布。污泥施用量、培养时间及其相互作用的影响取决于金属或土壤类型。在大多数情况下，最终观察到土壤中更易迁移形式的金属有所增加。
