Atmospheric Input of POPs into Lake Maggiore (Northern Italy): PCDD/Fs and Dioxin-like PCBs Profiles and Fluxes in the Atmosphere and Aquatic System

Abstract

The delivery and accumulation of PCDD/Fs and dioxin-like PCBs (DL-PCBs) as recorded in sediments from the Lake Maggiore (LM) in Northern Italy and the influence of the atmosphere in contaminating this subalpine ecosystem was studied. PCDD/Fs (17 congeners) and DL-PCBs (12 congeners) concentrations, congener profiles and fluxes in air, bulk deposition, aquatic settling material and surface sediments are presented in this work. Our strategy was to obtain surface sediment from areas near riverine inputs and in the depositional basins, settling material in sediment traps at one site and air, aerosol and bulk deposition profiles. Concentrations in air of 24.5 WHO-TEQ fg m-3 PCDD/Fs and 6.8 WHO-TEQ fg m-3 DL-PCBs were obtained. Bulk deposition of 136.6 and 28.5 WHO-TEQ pg m-2 for dioxins/furans and DL-PCBs respectively, resulted during one sampled week. Aquatic settling material had a concentration of 11.4 WHO-TEQ pg g-1 for PCDD/Fs and a concentration of 2.3 WHO-TEQ pg g-1 for DL-PCBs. PCDD/Fs concentrations in surface sediments varied from 0.13 to 16.9 WHO-TEQ pg g-1whereas values ranged from 0.03 to 4.7 WHO-TEQ pg g-1 for DL-PCBs. The concentrations obtained in the environmental compartments studied suggest a situation of low level contamination. Similarity in PCDD/Fs and DL-PCBs congeners profiles in atmospheric air, bulk deposition, aquatic settling matter and surface sediment point to an important if not dominant contribution from atmospheric deposition to Lake Maggiore, especially derived from wet deposition of aerosol-bound PCDD/Fs and DL-PCBs. Flux estimates support this hypothesis.