School of Agriculture, Food and Wine, University of Adelaide, South Australia, 5005 Adelaide, Australia.
Chemosphere. 2011 Sep;84(11):1556-62. doi: 10.1016/j.chemosphere.2011.05.053. Epub 2011 Jun 23.
Land application of biosolids is common practice in many countries, however, there are some potential risks associated with the presence of contaminants within the biosolids. This laboratory study examined the degradation of four commonly found organic compounds, 4-nonylphenol, 4-t-octylphenol, bisphenol A, and triclosan, in soil following the addition of two biosolids over 32 weeks. The pattern of degradation was assessed to determine if it followed a standard first-order decay model or if a biphasic model with a degrading and a recalcitrant fraction better described the data. The time taken for the initial concentrations to decrease by 50% (DT50), based on a first-order model, was 12-25 d for 4-nonylphenol, 10-14 d for 4-t-octylphenol, 18-102 d for bisphenol A, and 73-301 d for triclosan. For 4-nonylphenol, bisphenol A and triclosan, the biphasic model fitted the degradation data better than the first-order model, indicating the presence of a degrading fraction and a non-degrading recalcitrant fraction. The recalcitrant fraction for these three compounds at the completion of the 32 week experiment was 17-21%, 24-42%, and 30-51% of the initial concentrations, respectively. For 4-t-octylphenol, the first-order model was sufficient in explaining the degradation data, indicating that no recalcitrant fraction was present. This study showed that biphasic degradation occurred for some organic compounds in biosolids amended soil and that the use of standard first-order degradation models may underestimate the persistence of some organic compounds following land application of biosolids.
土地应用生物固体是许多国家的常见做法，然而，生物固体中存在污染物会带来一些潜在风险。本实验室研究考察了在添加两种生物固体后 32 周内，土壤中四种常见有机化合物（壬基酚、对叔辛基酚、双酚 A 和三氯生）的降解情况。评估降解模式，以确定其是否遵循标准的一级衰减模型，或者是否存在一个降解和难降解分数的两相模型可以更好地描述数据。基于一级模型，初始浓度降低 50%所需的时间（DT50）分别为壬基酚 12-25 天、对叔辛基酚 10-14 天、双酚 A 18-102 天和三氯生 73-301 天。对于壬基酚、双酚 A 和三氯生，两相模型比一级模型更能拟合降解数据，表明存在一个降解分数和一个非降解的难降解分数。在 32 周实验结束时，这三种化合物的难降解分数分别为初始浓度的 17-21%、24-42%和 30-51%。对于对叔辛基酚，一级模型足以解释降解数据，表明不存在难降解分数。本研究表明，在添加生物固体的土壤中，一些有机化合物发生了两相降解，而使用标准的一级降解模型可能会低估生物固体土地应用后一些有机化合物的持久性。
