Aging reduces the bioavailability of even a weakly sorbed pesticide (carbaryl) in soil
Aging reduces the bioavailability of even a weakly sorbed pesticide (carbaryl) in soil
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DOI：
10.1897/03-569
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发表时间：
2004-09-01
影响因子：
4.1
通讯作者：
Alston, AM
中科院分区：
文献类型：
--
作者：
Ahmad, R;Kookana, RS;Alston, AM
我们研究了位于巴基斯坦Mamoon Kanjan的一个储存设施中具有长期农药污染历史的土壤中西威因（1-萘基甲基氨基甲酸酯）的生物利用度和生物降解。西威因的吸附性较弱，一般认为在土壤中容易降解。提取研究表明，土壤中49%的总西威因（88.0 mg kg(-1)）不能水提取，也不能生物利用，这一点通过接种可降解西威因的混合细菌培养物得到证实。在污染土壤中接种西威因降解培养基表明，细菌只能降解农药的有效部分（即水可提取的部分）。当土壤在球磨机中粉碎以促进残留物的释放时，另外19%的西维因变成了生物可利用性。相当大比例的残留物（约33%）仍然不可用。农药与土壤（即老化）之间的长（约12年）接触时间，可能会被固存到土壤纳米孔和有机质基质中，这表明农药无法被微生物降解。土壤中高浓度（88.0 mg kg(-1)）有利于其持续存在和固存。本研究的结果表明，即使是一种弱吸附和容易降解的农药，西威因，也会随着时间的推移而有效地隔离在土壤中，使微生物部分无法进入，并影响该化合物的生物利用度。
We investigated bioavailability and biodegradation of carbaryl (1-naphthyl methylcarbamate) in a soil with a long history of pesticide contamination from a storage facility located at Mamoon Kanjan, Pakistan. Carbaryl is weakly sorbed and generally considered to be easily degradable in soil. Extraction studies revealed that 49% of the total carbaryl in soil (88.0 mg kg(-1)) was not water-extractable and also not bioavailable, as demonstrated by inoculation of the contaminated soil with a carbaryl-degrading, mixed bacterial culture. Inoculation of the contaminated soil with the carbaryl-degrading culture showed that the bacteria were capable of degrading only the available (i.e., water-extractable) fraction of the pesticide. When the soil was pulverized in a ball mill to enhance the release of residue, an additional 19% of the carbaryl became bioavailable. A significant proportion of residue (approximate to33%) remained unavailable. The long (>12 years) contact time between the pesticide and soil (i.e., aging), allowing possible sequestration into,soil nanopores and the organic matter matrices, is suggested to have rendered the pesticide unavailable for microbial degradation. High concentration (88.0 mg kg(-1)) in soil facilitated its persistence and sequestration. Results from the present study demonstrate that even a weakly sorbed and easily degradable pesticide, carbaryl, is effectively sequestrated in soil with time, rendering it partly inaccessible to microorganisms and affecting the bioavailability of the compound.