Factors controlling sorption of prosulfuron by variable-charge soils and model sorbents
Factors controlling sorption of prosulfuron by variable-charge soils and model sorbents
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DOI：
10.2134/jeq2004.1354
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发表时间：
2004-07-01
影响因子：
2.4
通讯作者：
Lee, LS
中科院分区：
文献类型：
--
作者：
Hyun, S;Lee, LS
丙磺隆[1-（4-甲氧基-6-甲基三嗪-2-基）-3-[2-（3，3，3-三氟丙基）苯磺酰基]-脲）是一种相对较新的磺酰脲除草剂，为弱酸性（pK（a）3.76），因此将经历pH依赖性的形态和吸附。了解丙磺隆在土壤中的吸附对于预测其环境归宿非常重要。通过测定氟嘧磺隆在5种模型吸附剂（无定形二氧化硅、Cl-氧化铝、CaSWy 1蒙脱石、商品腐殖酸和阴离子交换树脂）和10种可变电荷土壤上的吸附，研究了氟嘧磺隆在CaCl 2和Ca（H2 PO 4）2溶液中的吸附随pH和离子强度的变化规律。阴离子交换的氟磺隆占高达82%的总吸附在pH值范围从3至7。阴离子交换对丙磺隆吸附的相对重要性与阴离子和阳离子交换容量的比值呈正相关。腐殖酸和可变电荷土壤的有机碳（OC）归一化的吸附（K-OC）与pH值之间的比较显示出类似的趋势，吸附随pH值的增加而减少。然而，K-OC值估计可变电荷土壤在较低的pH值范围内，阴离子交换有最大的贡献吸附几乎是一个对数单位大于估计从腐殖酸清楚地例证了阴离子交换的影响。腐殖酸和可变电荷土壤的K-oc-pH曲线的相似性可能是由于以下事实：（i）阳离子交换容量随着OC含量的增加而增加，从而有效阴离子交换容量降低;（ii）疏水和亲水吸附机制的相对贡献相当恒定。鉴于亲水性和疏水性吸附的氟磺隆减少与pH值的增加，此外，肥料和石灰的修正案可能会提高最近应用的酸性农药的场外浸出的潜力。
Prosulfuron [1-(4-methoxy-6-methyltriazin-2-yl)-3-[2-(3,3,3-trifluoropropyl) phenylsulfonyl]-urea), a relatively new sulfonylurea herbicide, is a weak acid (pK(a) 3.76), and therefore, will undergo pH-dependent speciation and sorption. Understanding prosulfaron sorption in soils is important for predicting its environmental fate. Soil and solution factors controlling sorption were investigated by measuring prosulfuron sorption on five model sorbents (amorphous silica, cl-alumina, CaSWy1 montmorillonite, commercial humic acid, and anion exchange resin) and 10 variable-charge soils from CaCl2 and Ca(H2PO4)(2) solutions as a function of pH and ionic strength. Anion exchange of prosulfuron accounted for up to 82% of overall sorption in the pH range from 3 to 7. The relative importance of anion exchange to prosulfaron sorption was positively correlated to the ratio of anion and cation exchange capacities. Comparison between organic carbon (OC)-normalized sorption (K-oc) versus pH for humic acid and variable-charge soils show similar trends with sorption decreasing with increasing pH. However, K-oc values estimated from variable-charge soils in the lower pH range where anion exchange has the greatest contribution to sorption was almost one log unit greater than that estimated from humic acid clearly exemplifying the impact of anion exchange. Similarity in K-oc-pH curves for humic acid and variable-charge soils may result from the fact that (i) cation exchange capacity increases with increasing OC content, thus effective anion exchange capacity is reduced; and (ii) the relative contribution of hydrophobic and hydrophilic sorption mechanisms was fairly constant. Given that both hydrophilic and hydrophobic sorption of prosulfuron decrease with increasing pH, addition of fertilizer and lime amendments may enhance the potential for off-site leaching of recently applied acidic pesticides.