芘在土壤中的长期吸附和解吸行为

研究了芘在6种不同性质土壤中长期吸附解吸及不可逆吸附行为.实验结果表明:长期实验中芘在土壤中的吸附和解吸都存在快过程和慢过程2个阶段.不同吸附平衡时间下,有机质含量高于1%时,不同土壤的吸附平衡常数随有机质含量的增加而增加;有机质含量低于1%时,黏粒含量对土壤的吸附能力有着重要影响;平衡时间由2d增加到180d后,6种土壤的Kd值增加了35.1%～557.9%,其中土壤有机质对Kd值有不同程度的影响,而黏粒对Ka值影响最大,平衡时间对部分土壤Kd值影响不容忽视.长期解吸过程中,6种土壤慢解吸部分占总解吸量的12.05%～41.00%,有机质含量越高,慢解吸对解吸过程的贡献越大.不考虑老化的影响,有机质含量对不可逆吸附容量的贡献明显高于黏粒的贡献,与有机质对慢解吸过程的影响有一致性.

Long-Term Sorption/Desorption Behavior of Pyrene in Soils

Long-term sorption/desorption behavior of pyrene in six types of soils are investigated. The results show that long-term sorption and desorption entail two phases, including initially rapid process followed by a slow sorption/desorption. When soil organic matter (SOM) content was below 1%, the constant of sorption Kd of dissimilar soils increased with SOM content under different equilibrium time. While clay content played an important role in sorption capacity of the soils as SOM content was below 1%. In long-term sorption experiment, the Kd values of the six soils increased from 35.1% to 557.9%, respectively, with the sorption equilibrium time increased from 2 d to 180 d. Clay influenced significantly on Kd, while the effect of SOM was different, which suggested that the effect of sorption time on Kd of some soils could not be ignored. In long-term desorption experiment, the slow desorption percentages of pyrene from the six soils were in the range of 12.05% - 41.00%, with the tendency that the attribution of slow desorption fraction to desorption process increased with SOM. Ignoring the influence of aging on the sorption/desorption, it indicates that the attribution of SOM to the capacity of irreversible sorption compartment is distinctly higher than that of clay, which is consistent to the attribution of SOM to slow desorption process.