土壤中多环芳烃的SPMD辅助解吸行为研究

为了开发一种表征土壤中憎水性有机污染物解吸及生物有效性的新方法,建立了半透膜被动采样装置（SPMD）研究土壤中有机污染物解吸行为的方法,利用SPMD分析了多环芳烃菲、芘和苯并［a］芘在3种不同性质土壤中的辅助解吸行为.结果表明,SPMD是一种很好地表征土壤中憎水性有机污染物解吸及生物有效性的手段. SPMD辅助解吸多环芳烃的效率与土壤有机质及多环芳烃性质有关.随着土壤有机质含量的降低,土壤中菲和芘的SPMD解吸率逐渐升高,对于10 mg/kg染毒水平,当土壤有机质含量由18.68%降低到0.3%时,2种化合物的解吸率分别由56.45%和48.28%上升到接近100%;但是对于苯并［a］芘,粘土表现出明显的滞留能力,在有机质含量（0.3%）很低、粘土含量（39.05%）较高的3号土壤中,苯并［a］芘的解吸率仅有66.97%.不同多环芳烃SPMD辅助解吸率差别很大,随着土壤有机质含量的降低,以及污染物浓度的提高,菲和芘的解吸差异逐渐缩小,而苯并［a］芘与上述2种多环芳烃的差异很大,主要是由于苯并［a］芘具有高度亲脂性,并且分子较大,造成其容易滞留在粘土的微孔及有机质的致密结构中.

Desorption of Polycyclic Aromatic Hydrocarbons in Soils Assisted by SPMD

In order to develop a new method to study the desorption and bioavailability of hydrophobic organic chemicals(HOCs) in soils,a method using semi-permeable membrane device(SPMD) to study desorption of HOCs in soils has been set up,and assisted desorption of polycyclic aromatic hydrocarbons(PAHs),phenanthrene(PHE),pyrene(PYE),and benzo[a]pyrene(B[a]PYE)in three different kinds of soils was studied using SPMD.The results show that SPMD is a good measurement to study the desorption and bioavailability of HOCs in soils.SPMD assisted desorption of PAHs is highly dependent on the properties of the soils and the chemicals.PHE and PYE desorption percentages increase with the reduction of the content of soil organic matter(SOM),so that the desorption of the two chemicals increases from 56.45% and 48.28% to almost 100 % when SOM content was reduced from 18.68% to 0.3 %.However,clay has a significant holding effect on(B[a] PYE),and PYE desorption is only 66.97% in Soil 3 with SOM of 0.3 % and clay content of 39.05 %.There is a great variety in the desorption among the different PAHs. With the reduction of SOM content and the elevation of contamination concentration,the difference between PHE and PYE decreases gradually,while B[a]PYE exhibits a significant difference from them.This could be attributed to the high lipophilicity and large molecular size of B[a]PYE,which make the molecule of BPYE to be more easier to be held in the nanopores of clay and the dense region of SOM.