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۱Does soil organic matter chemistry affect sorption of nonionic pesticides?
نویسنده(ها):
اطلاعات انتشار: اولین همایش ملی اصلاح الگوی مصرف با محوریت منابع طبیعی، کشاورزی و دامپزشکی، سال
تعداد صفحات: ۹
The influence of organic matter chemistry on the sorption of diuron to soils collected from a small field was investigated. Organic carbon–normalized sorption coefficients (KOC), determined by batch sorption, varied between 405 and 598 Lkg–1 amongst 10 A11 horizons, and between 547 and 975 Lkg–1 amongst 10 matching A12 horizons. In all cases KOC was greater for the A12 horizon than the corresponding A11 horizon by 27–81%. Organic matter chemistry of the A11 and A12 horizons was determined using solid–state 13C nuclear magnetic resonance (NMR) spectroscopy. KOC was positively correlated with aryl C (r2 = 0.61, significance level 0.001) and negatively correlated with O–alkyl C (r2 = 0.88, significance level <0.001) as a single factor and combination of both we also propose A index (r2 = 0.65, significance level 0.001). Little changes in soil mineralogy across a very small field led to diminish organic matter and clay minerals interactions, allowing the effect of organic matter chemistry on KOC to be seen clearly.<\div>

۲Differentiation between the role of organic matter–mineral interactions and organic matter chemistry on the sorption of polycyclic aromatic hydrocarbons
نویسنده(ها):
اطلاعات انتشار: اولین همایش ملی اصلاح الگوی مصرف با محوریت منابع طبیعی، کشاورزی و دامپزشکی، سال
تعداد صفحات: ۵
Even though it is well documented that the amount of soil organic matter is the most important determinant of the sorption affinity of soils for non–ionic compounds, it is also clear that organic carbon–normalized sorption coefficients (KOC) vary considerably between soils. KOC variability can be affected by two factors, variations in the chemistry of organic matter between soils and interactions between organic matter and soil minerals,
especially clay minerals. Here, we quantify both of these effects for phenanthrene. The effect of organic matter– mineral interactions was gauged
by comparing KOC for HF–treated soils, which have had their clay minerals removed, with KOC for the corresponding whole soils. The average ratio of KOC of the HF–treated soils to KOC of the whole soils was 2.3, indicating a substantial depression of KOC due to the presence of minerals in the whole soils. The effect of organic matter chemistry was gauged by correlating KOC against distributions of C types determined using solid–state 13C NMR spectroscopy. KOC was positively correlated with aryl C and negatively correlated with O–alkyl C, for HF–treated soils but not for whole soil. We suggest that the lack of a clear effect of organic matter chemistry on whole soil KOC for phenanthrene is due to an over–riding influence of organic matter–mineral interactions in this case. This hypothesis is supported by a correlation between the increase in KOC on HF–treatment and the soil clay content.<\div>

۳The role of lipids on the Sorption of non–ionic pesticides in soil environment
نویسنده(ها):
اطلاعات انتشار: اولین همایش ملی اصلاح الگوی مصرف با محوریت منابع طبیعی، کشاورزی و دامپزشکی، سال
تعداد صفحات: ۶
Removal of soil lipids using accelerated solvent extraction (ASE) increased the sorption affinity of the remaining organic matter for both diuron and phenanthrene, by an average of 31% and 29%, respectively. Extractable lipids accounted for 3–13% of organic C. The organic carbon–normalized
sorption coefficients (KOC) for diuron and phenanthrene were consistently higher for the lipid–extracted soils than for the whole soils (average of 31% for diuron and 29% for phenanthrene), indicating that lipids compete for or block sorption sites on the organic matter. Sorption experiments on one pair of HF–treated soils indicated that the blocking effects of minerals and lipids are independent, since lipid extraction and HF–treatment combined increased KOC by more than either treatment alone.<\div>
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