ABSTRACT

A safe use of herbicide in the environment can be assessed by it’s adsorption – desorption behavior in soil. In the present work laboratory studies were performed to examine adsorption-desorption behavior of penoxsulam herbicide on six soils having widely different properties. Adsorption kinetics of penoxsulam was best accounted by pseudo-first order model. Among acidic soils, soil having the lowest pH (5.36) showed highest partition coefficient (k_d) whereas, in case of alkaline soils, soil of relatively less alkaline pH (7.88) and higher silt and organic content had higher k_d value. The k_d of penoxulam showed a highly significant and negative correlation with soil pH (r = −0.987, significant at p ≤ 0.01). Adsorption-desorption data fitted well to Freundlich isotherm model. Percent desorption of penoxsulam showed a highly significant and positive correlation with soil pH (r = 0.973, significant at p ≤ 0.01). Step-wise multiple regression analysis revealed that k_d, Freundlich adsorption-desorption isotherm constants and hysteresis of penoxulam in soils could be successfully predicted by soil properties. The fourier transformed infrared spectral comparisons showed that adsorption of penoxsulam on soil occurred through H-bonding of several polar moieties with soil constituents besides a likely complex reaction of triazole group with some transition metals present on soil exchange complex.

摘要

除草剂在环境中的安全使用可以通过其在土壤中的吸附-解吸行为来评估。在目前的工作中，进行了实验室研究，以检查五氧磷磺酰胺除草剂在六种性质迥异的土壤上的吸附-解吸行为。伪一阶模型最好地解释了戊氧舒兰的吸附动力学。在酸性土壤中，pH最低（5.36）的土壤分配系数（k _d）最高，而在碱性土壤中，碱性pH值相对较低（7.88）且粉沙和有机物含量较高的土壤的k _d值较高。第k _d戊唑仑的含量与土壤pH值呈极显着负相关（r = -0.987，p≤0.01时呈显着性）。吸附-解吸数据非常适合Freundlich等温线模型。戊氧舒兰的解吸百分率与土壤pH呈高度显着正相关（r = 0.973，在p≤0.01时显着）。逐步多元回归分析表明，土壤性质可以成功地预测土壤中百草枯的k _d，弗氏吸附-解吸等温常数和滞后。傅立叶变换红外光谱比较表明，除三唑基与土壤交换复合物上存在的某些过渡金属可能发生复杂反应外，还通过一些极性基团与土壤成分的H键键合吸附了五氧化二硫。