Vertical and Lateral Redistribution of POPs in Soils Developed along a Hydrological Gradient

摘要

Study of die dispersion of persistent organic pollutants (POPs) throughout trie environment is necessitated by tbeirtoncological properties and propensity to accumulate in biota. In this study, we use data from the analysis of three ~(210)Pb dated soil profiles collected along a 30-m hydrological gradient to demonstrate postdepositional mobility of polycholrinated dibenzo-p-dioxins and polychlorinated dibenzofiirans (PCDD/Fs) and potychlorinated biphenyls (PCBs). We found that (i) humus originating from litter exposed to surface fallout during die 1960- 1970s contains the highest concentrations of PCDD/Fs and PCBs in the O-horizon of die sods; (ii) accumulation rates of PCDD/Fs and PCBs in the O-horuon(~5.0)and~210μg m~(-2)yr~(-1)) constituted onb/9.1%and 3.5%, respectively, of die measured annual input, demonstrating that a minor fraction of the deposited material is retained within Che O-horizon; (iii) POP; inventories in die upper 0.5-0.9 m of die mineral soil constituted a considerable part (40-70%) of the total pool stored in die soil, implyingsignificant vertical transk>catienofatmospberk derived POPs; and (iv) increasing downslope inventories of POPs suggest a lateral downward transport of POPs from. The findings challenge me commonly accepted view that POPs fallout is effectrnly retained widun O-horisoss.