Adsorption and degradation of four acidic herbicides in soils from southern Spain.
Adsorption and degradation of four acidic herbicides in soils from southern Spain.
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DOI：
10.1002/ps.1545
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发表时间：
2008-07
影响因子：
4.1
通讯作者：
J. Villaverde;M. Kah;Colin D. Brown
中科院分区：
文献类型：
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作者：
J. Villaverde;M. Kah;Colin D. Brown
农药在土壤中的降解和吸附是决定农药使用是否会对环境质量产生影响的关键过程。农药在土壤中的降解通常会导致毒性降低，但有些农药的分解产物比母体化合物的毒性更大。对土壤颗粒的吸附确保除草剂保留在其生物活性表达的地方，也决定了从作用部位转移的潜力。降解和吸附是复杂的过程，在理解它们方面的缺陷仍然限制了预测可电离农药的命运和行为的能力。本文报道了四种酸性农药在西班牙南部五种土壤中的吸附和降解行为。结果用于研究土壤和农药性质对吸附和降解的影响以及两者之间的潜在联系。结果测定了4种酸性农药在西班牙小有机质（OM）含量（0.3 ~ 1.0%）和不同粘土含量（3 ~ 66%）土壤中的吸附和降解情况。总体上，麦草畏<甲磺隆-甲基< 2,4- d <氟嘧磺隆-甲基钠的吸附量依次增大。有机质和粘土含量都是决定除草剂吸附程度的重要因素，但不同土壤之间粘土含量的相对差异远大于有机质含量的相对差异，因此粘土含量是决定这些土壤对除草剂吸附程度的主要属性。pH与除甲磺隆-甲基外的所有化合物的吸附均呈负相关。降解率与粘土和OM含量呈极显著正相关（P < 0.01），与pH呈极显著负相关（P < 0.01）。除甲磺隆-甲基外，其降解仅与土壤生物活性显著相关（P < 0.05）。结论有机质和粘土含量都是决定除草剂吸附程度的重要因素，但不同土壤间粘土含量的相对差异远大于有机质含量的相对差异，因此粘土含量是决定该类土壤除草剂吸附程度的主要指标。pH与除甲磺隆-甲基外的所有化合物的吸附均呈负相关。这四种酸性农药的对比表明，土壤中的化学降解比吸附更难预测。大多数测量的变量是相互关联的，即使是来自同一化学类别和具有相似结构的化合物，也观察到不同的行为。
BACKGROUND Pesticide degradation and adsorption in soils are key processes determining whether pesticide use will have any impact on environmental quality. Pesticide degradation in soil generally results in a reduction in toxicity, but some pesticides have breakdown products that are more toxic than the parent compound. Adsorption to soil particles ensures that herbicide is retained in the place where its biological activity is expressed and also determines potential for transportation away from the site of action. Degradation and adsorption are complex processes, and shortcomings in understanding them still restrict the ability to predict the fate and behaviour of ionisable pesticides. This paper reports the sorption and degradation behaviour of four acidic pesticides in five soils from southern Spain. Results are used to investigate the influence of soil and pesticide properties on adsorption and degradation as well as the potential link between the two processes. RESULTS Adsorption and degradation of four acidic pesticides were measured in four soils from Spain characterised by small organic matter (OM) contents (0.3-1.0%) and varying clay contents (3-66%). In general, sorption increased in the order dicamba < metsulfuron-methyl < 2,4-D < flupyrsulfuron-methyl-sodium. Both OM and clay content were found to be important in determining adsorption, but relative differences in clay content between soils were much larger than those in OM content, and therefore clay content was the main property determining the extent of herbicide adsorption for these soils. pH was negatively correlated with adsorption for all compounds apart from metsulfuron-methyl. A clear positive correlation was observed for degradation rate with clay and OM content (P < 0.01), and a negative correlation was observed with pH (P < 0.01). The exception was metsulfuron-methyl, for which degradation was found to be significantly correlated only with soil bioactivity (P < 0.05). CONCLUSIONS Both OM and clay content were found to be important in determining adsorption, but relative differences in clay content between soils were much larger than those in OM content, and therefore clay content was the main property determining the extent of herbicide adsorption for soils of this type. pH was negatively correlated with adsorption for all compounds apart from metsulfuron-methyl. The contrasting behaviour shown for these four acidic pesticides indicates that chemical degradation in soil is more difficult to predict than adsorption. Most of the variables measured were interrelated, and different behaviours were observed even for compounds from the same chemical class and with similar structures.