Chefetz Benny
Department of Soil and Water Sciences, Faculty of Agricultural, Food and Environmental Quality Sciences, Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100, Israel.
Environ Toxicol Chem. 2003 Oct;22(10):2492-8. doi: 10.1897/02-461.
Several studies have shown selective preservation of plant cuticular materials in soils. However, very little is known about their function as sorbents for the hydrophobic organic contaminants (HOCs) in the soil. In this study, we investigated the sorption and desorption of phenanthrene and atrazine by cuticular fractions of pepper (bulk, dewaxed, nonsaponifiable, and nonhydrolyzable) to better understand the sorptive activity of cuticular matter in soils. The bulk and dewaxed cuticles exhibited carbon-normalized distribution coefficients (Koc) for phenanthrene and atrazine in the range of that reported for soil humic substances, although both samples were rich in aliphatic structures. No hysteresis was observed in the desorption isotherms of either solute. The nonhydrolyzable residue exhibited a very high Koc value for atrazine, whereas the nonsaponifiable sample be exhibited the lowest Koc value for both sorbates. Based on solubility parameter data, it is suggested that the nonsponifiable sample be considered an intermediate between the physical and chemical mixture of pectin and cutan/lignin-like fractions, whereas the dewaxed cuticle is a chemical blending of cutin and pectin. The n-hexane-normalized sorption data suggest that the pepper cuticle can interact specifically with atrazine. This study leads to the conclusion that the contribution of aliphatic-rich plant biopolymers to the sorption of HOCs can be significant because of their preservation and accumulation in soils.
多项研究表明，植物角质层物质在土壤中能够被选择性保存。然而，对于它们作为土壤中疏水性有机污染物（HOCs）吸附剂的功能，我们却知之甚少。在本研究中，我们研究了菲和阿特拉津在辣椒角质层组分（整体、脱蜡、不皂化和不可水解）上的吸附和解吸情况，以便更好地了解土壤中角质层物质的吸附活性。整体和脱蜡角质层对菲和阿特拉津的碳归一化分配系数（Koc）处于土壤腐殖质报道的范围内，尽管这两个样品都富含脂肪族结构。两种溶质的解吸等温线均未观察到滞后现象。不可水解残渣对阿特拉津表现出非常高的Koc值，而不皂化样品对两种吸附质均表现出最低的Koc值。基于溶解度参数数据，表明不皂化样品可被视为果胶与角质/木质素样组分物理和化学混合物之间的中间体，而脱蜡角质层是角质和果胶的化学混合物。正己烷归一化吸附数据表明，辣椒角质层可与阿特拉津发生特异性相互作用。本研究得出结论，富含脂肪族的植物生物聚合物因其在土壤中的保存和积累，对HOCs吸附的贡献可能很大。
