The influences of different soil organic fractions on the sorption and bioavailability of phenanthrene
土壤中不同有机质对菲的吸附行为及生物可利用性的影响

In order to know influences of different soil organic fractions on sorption characteristics and bioavailability to persistent organic pollutants (POPs), mineral-bound humic acid (MHA) and mineral-bound humin (MHU) were separated from the topsoil of Heilongjiang Province. Sorption characteristics of MHA, MHU and whole soil to phenanthrene were studied by sorption kinetics and isotherms. Influences of soil organic fractions on bioavailability were measured by changing aging time of phenanthrene and quantity of adsorbents. The results showed both distribution coefficients K and nonlinearities were MHU>whole soil>MHA. During short aging period (60 d) and degradation time (24 h), MHA with lower distribution coefficients K restrained biodegradation of phenanthrene. The degradation rates of phenanthrene, adsorbed by MHA, MHU and whole soil, were 46.99%, 64.40% and 59.33% respectively, after 60 d aged and 6 h degraded. With increased the amount of sorbent, the biodegradations of phenanthrene absorbed by MHA were significantly decreased. Phenanthrene, aged 7 d and degraded 24 h, was degraded by 78.80% and 13.90%, respectively, after increased MHA by 1 and 3 times. However, similar results were not observed by changing MHU. With prolonged the aging time, the biodegradations of phenanthrene adsorbed by MHU decreased gradually. These findings suggest that MHA plays an important role in the biodegradation of POPs adsorbed by the soil in a short aging period and biodegradation time.