沉积物有机质的形成温度对苯并[a]芘吸附解吸的影响

Effect of Formation Temperature on Sorption and Desorption of Benzo[α]pyrene by Sediment Organic Matter

通过静态吸附实验,研究了不同燃烧温度形成的沉积物有机质对苯并[a]芘(BaP)的吸附解吸行为。结果表明,当燃烧温度从0℃升高到400℃时,吸附非线性指数n值从0.544降低到0.299。然而,沉积物有机质形成温度的升高增加了BaP的吸附能力和解吸滞后性。当燃烧温度升高到600℃时,样品中脂肪结构、极性结构和大部分芳香结构被燃烧掉,主要剩下矿物组分。因此,T600样品对BaP表现出高的n值、低吸附能力和吸附不可逆性。单一浓度下有机碳标化的吸附能力参数lgKoc值与芳香碳含量显著正相关(p<0.001),而与样品的H/C原子比显著负相关(p<0.001)。样品的芳香碳含量与BaP的解吸滞后指数(H)(p<0.01)和n值(p<0.000 1)均表现出很好的负相关关系。以上的结论说明,芳香碳在BaP的吸附非线性、吸附能力和解吸滞后性中起主要作用。

Sorption and desorption isotherms of benzo[α]pyrene（BaP） on sediment organic matter（SOM） prepared at different combustion temperature were studied to examine the impact of SOM structure on sorption and desorption.With the increase of combustion temperature from 0 ℃ to 400 ℃,the sorption isotherm nonlinearity index n value decreased from 0.544 to 0.299.However,the increase of formation temperature enhanced the adsorption capacity and desorption hysteresis for BaP on SOM.When the combustion temperature increased to 600 ℃,aliphatic structures,polar structures and most aromatic structures were burnt out,and the mineral materials were dominant in the sample.Higher n value,lower sorption capacity and sorption irreversibility of BaP were presented in the sample treated at 600 ℃（T600）.Positive correlations between single-point organic carbon-normalized distribution coefficient logKoc values and aromatic carbon（p 0.001） and negative correlations between log Koc values and H/C ratios（p 0.001） were observed.There was a negative relation between hysteresis index（H） value and aromatic carbon and a negative trend of n values and aromatic carbon.The above results indicated the dominance of aromatic structures in the sorption nonlinearity,sorption capacity and desorption hysteresis of BaP on SOM.