摘要
为能够准确预测有机污染物在植物角质层上的吸附行为,用化学方法（脱蜡、皂化、酸解）分离得到7种苹果角质层组分,探讨了角质组分对甲萘酚的吸附特征及其与结构组成之间的关系.结果表明,苹果角质层由44.7%蜡质、34.6%角质单体、13.6%糖类、7.5%生物高聚物（cutan）组成,脱蜡、皂化脱角质单体后角质组分的极性指数（（O＋N）/C）增大,而酸解脱糖后（O＋N）/C则减小.角质层组分对甲萘酚的等温吸附曲线均呈非线性（N=0.551~0.918）,而高浓度时的等温吸附曲线则呈线性,表明植物角质与有机物的相互作用除了分配作用之外,还存在其它的特殊作用.苹果角质层（AC1）对甲萘酚的吸附系数（Koc）为442,脱蜡、脱糖后角质组分的Koc值增大,而脱角质单体后Koc值则大大减小,表明角质单体是主要的吸附介质;蜡质、角质单体、糖类组分对角质层吸附行为的影响存在交互作用.角质组分的Koc值随其（O＋N）/C变化出现＂峰值＂,意味着甲萘酚与角质组分之间的相互作用存在最佳的极性匹配.
Cuticular materials were isolated from apples by chemical methods including de-waxing, saponification and acid hydrolysis. The polarity index （（ O ＋ N）/C atomic ratio） and components （waxes, cutin monomer, polysaccharide） of all cuticular fractions were characterized by elemental analysis and the recoveries of each fractions were determined. To accurately predict the fate of organic pollutants in the plant-environment system, the sorption of 1-naphthol to apple cuticular materials was investigated using a batch equilibration technique, and correlated with the cuticle properties. The cuticle sheet in each apple consisted of waxes （44.7%） , cuticular monomer （34.6%） , polysaccharide （ 13.6% ） , and cutan （7.5%）. Cutin monomer and waxes were the dominant nonpolar components of cuticle, while polysaccharide significantly contributed to the polar components. Isotherms of 1 -naphthol to apple cuticular fractions were nonlinear （N = 0. 551 - 0. 918） over the whole tested concentration range, while isotherms at high concentrations werg practically linear. These observations suggest that the sorption mechanism was dominated by partition and supplemented by specific interactions including hydrogen bonding and π-π interaction. Polarity apparently played a regulating role in the sorption of organic contaminants. The sorption coefficient （Koc） increased rapidly with the decrease of polarity, and reached a maximal value （Koc = 861 ） at （ O ＋ N）/C = 0.27, then decreased rapidly with a further decrease of polarity, which suggests that 1-naphthol was strongly compatible with the plant cuticular fraction with medium polarity. The interactive effects of wax, cuticle monomer and polysaccharide on sorption by the cuticle were evaluated from the K∝ ratios of the different fractions. Cutin monomer was the predominant sorptive medium in apple cuticle material, followed by waxes and polysaccharide components.
出处
《环境科学学报》
CAS
CSCD
北大核心
2007年第11期1881-1886,共6页
Acta Scientiae Circumstantiae
基金
国家自然科学基金(No.20577041
40671168)
教育部"新世纪优秀人才支持计划"(No.NCET-05-0525)~~
