生物质炭对土壤中PAHs总量及有效性的影响研究

Effects of biochar on the total and bioavailable polycyclic aromatic hydrocarbons(PAHs)in soil

通过24周的土壤培养实验,研究了生物质炭添加量(0.1%、1.0%、2.0%)对土壤中菲和芘的化学可提取总量、挥发量及基于聚甲醛膜(POM)提取的生物有效性含量的影响。结果显示:与对照相比,添加生物质炭使土壤中菲和芘的总量分别下降了15.6%~25.0%和12.8%~30.3%,有效性分别下降了14.7%~37.3%和23.4%~49.8%;培养前6周,添加生物质炭使土壤中菲的挥发量显著减少了70.4%~72.4%,芘的挥发量减少了36.2%~48.9%,此后土壤中菲、芘挥发量趋于稳定,各处理间无显著差异(P>0.05)。研究表明,生物质炭在降低土壤中PAHs的总量及有效性含量方面具有剂量效应,但对PAHs挥发量的抑制作用的剂量效应与PAHs的种类有关。

In the present study, a 24 weeks′ soil incubation experiment was carried out to investigate the effect of corn stover biochar on the total and bioavailable phenanthrene and pyrene in soil. The biochar was applied at a rate of 0.1%~2.0%（weight percent）. The total concentration of PAHs was extracted by chemical solvent, while the bioavailable of PAHs was measured by polyoxymethylene. In addition, the volatile content of phenanthrene and pyrene during this period was also determined. At the end of the incubation, the total concentration of phenanthrene and pyrene in the amended treatments decreased by 15.6%~25.0% and 12.8%~30.3%, respectively,when compared to the control（without biochar addition）. The bioavailable concentration of phenanthrene and pyrene decreased 14.7% ~37.3% and 23.4%~49.8%, respectively. With the respect of the volatile PAHs, an obvious inhibition was observed in the first six weeks＇ incubation, with an amount ranged from 70.4% to 72.4% for phenanthrene, and 36.2% to 48.9% for pyrene, respectively. However, at the end of the incuba-tion, no significant differences（P 〉0. 05） were observed for the inhibition rate between phenanthrene and pyrene, regardless of the biochar application rate. Therefore, biochar has a dose-effect on reducing both total and bioavailable PAHs in soil, i.e., the total and bioavailable PAHs in soil could be decreased by increasing the biochar application. However, the dose-effect on the inhibition of PAHs volatilization highly depended on the species of PAHs. The results obtained in the present study were very valuable in the remediation of soils contaminated with volatilized organic compounds.