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The effects of aging on the sorption/desorption behavior of organic chemicals in soils and relation to bioavailability.

机译：老化对土壤中有机化学物质的吸附/解吸行为及其生物利用度的影响。

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摘要

Observations on the behavior of pesticides in field-weathered soils have demonstrated that increased soil-chemical contact time (aging) may lead to increased persistence of contaminants in the environment. Aged chemicals can act as long-term sources of groundwater contamination, and aging may reduce the effectiveness of soil remediation technologies such as soil washing, pump and treat, and in-situ bioremediation. Environmental fate characterization based on laboratory studies of freshly added chemicals fail to consider the effects of aging and hence may underestimate the persistence of organic compounds in the environment. For example, although the soil fumigant ethylene dibromide (EDB) is readily biodegradable, relatively water soluble, and volatile, EDB residues have been found in field soils 20 years after its last known application. However, the causes of increased persistence due to aging are not well understood. One possible cause of increased persistence is a reduction in the bioavailability of contaminants to degrading microorganisms. This decrease in bioavailability is likely due to changes in the physical/chemical disposition of the contaminants due to aging. For example, an increase in sorption to soils due to aging can limit the extent of biodegradation of organic contaminants. Also, desorption from soils, which may decrease with aging, is thought to be the limiting factor controlling the rate of degradation of organic contaminants by degrading microorganisms.; This study describes three experiments designed to test the role of aging and its effect on the sorption/desorption dynamics and bioavailability of chemicals in soils. One experiment examined the sorption/desorption behavior of chlorobenzene on four soils (soil organic carbon content from 0.4–7.8%) after soil-chemical contact times (aging) of 24 hours and 14 months. Another experiment examined the sorption/desorption behavior of four compounds (EDB, chlorobenzene, 2,4-D, and atrazine) on one soil type after aging times of 24 hours, 1 month, and 14 months. Lastly, the sorption/desorption behavior and bioavailability of biphenyl to Pseudomonas putida P106 was studied after aging times of 24 hours and 8 months.; Increases in sorption due to aging were found for some chemicals (2,4-D, EDB) but not others (chlorobenzene). Large differences in sorption/desorption behavior for similar compounds (EDB and chlorobenzene) were observed, indicating that generalizations about compound behavior in soils are inappropriate. Desorption profiles were consistent in that aged chemicals showed a much larger desorption resistant fraction after long aging periods and this was true for all soil types. Desorption rates were unaffected by aging time. Biodegradation of biphenyl decreased with increased aging time and the desorption resistant fraction (observed in the desorption profiles) appeared to be inaccessible to microbes.
机译：对农药在田间风化土壤中的行为的观察表明，增加的土壤化学接触时间（老化）可能导致环境中污染物的持久性增加。老化的化学物质可能会长期作为地下水污染的来源，而老化可能会降低土壤修复技术的有效性，例如土壤清洗，泵送和处理以及原位生物修复。根据对新鲜添加的化学物质进行实验室研究得出的环境归宿特征未能考虑到老化的影响，因此可能低估了有机化合物在环境中的持久性。例如，尽管土壤熏蒸剂二溴乙烷（EDB）易于生物降解，相对水溶性和挥发性，但在上次已知应用后20年，在田间土壤中发现了EDB残留物。但是，由于老化而导致持久性增加的原因尚不清楚。持久性增加的一种可能原因是污染物降解微生物的生物利用度降低。生物利用度的这种下降可能是由于老化导致污染物的物理/化学分布发生变化。例如，由于老化导致对土壤的吸附增加会限制有机污染物的生物降解程度。另外，土壤中的解吸可能会随着年龄的增长而减少，这被认为是控制微生物降解有机污染物降解速率的限制因素。这项研究描述了三个实验，旨在测试衰老的作用及其对土壤中化学物质的吸附/解吸动力学和生物利用度的影响。一个实验检查了24小时14个月的土壤-化学接触时间（老化）后，氯苯在四种土壤上的吸附/解吸行为（土壤有机碳含量为0.4-7.8％）。另一个实验检查了24小时，1个月和14个月的老化时间后，四种化合物（EDB，氯苯，2,4-D和at去津）在一种土壤类型上的吸附/解吸行为。最后，研究了老化24小时8个月后联苯对恶臭假单胞菌P106的吸附/解吸行为和生物利用度。对于某些化学品（2,4-D，EDB），发现由于老化而导致的吸附增加，而其他化学品（氯苯）则没有。观察到相似化合物（EDB和氯苯）的吸附/解吸行为存在很大差异，这表明关于土壤中化合物行为的一般化是不合适的。解吸曲线是一致的，因为老化的化学品在长时间老化后显示出更大的抗解吸分数，这对于所有土壤类型都是如此。解吸速率不受老化时间的影响。联苯的生物降解作用随着老化时间的增加而降低，并且抗解吸分数（在解吸曲线中观察到）似乎无法被微生物吸收。

著录项

  • 作者

    Sharer, Michael Steven.;

  • 作者单位

    Michigan State University.;

  • 授予单位 Michigan State University.;
  • 学科 Environmental Sciences.; Agriculture Soil Science.
  • 学位 Ph.D.
  • 年度 1998
  • 页码 105 p.
  • 总页数 105
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 环境科学基础理论;土壤学;
  • 关键词

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