Tracing Atmospheric Deposition of PCDD/Fs in Lake Maggiore (Italy): Preliminary Results on Settling Material and Sediments

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/ Fs) enter the environment primarily as a result of anthropogenic activities. Many of the congeners bioaccumulate and are considered potent toxicants capable of producing a wide spectrum of adverse health effects in biota and humans such as immunotoxicity, chloracne, carcinogenicity, reproductive and developmental toxicity, disruption of the endocrine system, induction of enzymes, and anti-estrogenic effects. As a chemical class, they occur as byproducts of chemical manufacturing and incineration processes. Emissions from incineration of medical, municipal, and chemical wastes and certain facilities in central Europe provide the major source of PCDD/F to the environment. PCDD/Fs are delivered to lake systems by atmospheric emission and transport followed by deposition, direct and indirect discharges, and riverine inputs. Polychlorinated dioxins and furans (PCDD/Fs) for example are characterized by low aqueous solubilities and vapor pressures, and resistance to extensive chemical and biological transformation. Their general hydrophobic nature results in high partition coefficients to abiotic and biotic particles. PCDD/Fs exist in the atmosphere as gases and particles although most measurements are dominated by the aerosol concentrations, especially the black carbon (BC) fraction. Once delivered to the water column, the primary removal processes are adsorption to or partitioning into particles and subsequent settling and accumulation in bottom sediments. The sorptive properties are largely controlled by the organic carbon (OC) content of particles, although BC may also play a role. Thus hydrophobic organic contaminants (HOCs) will follow the path of the average clay-size particles and be focused into the more quiescent, depositional basins of the lake. Experience from the Laurentian Great Lakes shows that residence times for HOCs are about 2-4 times the fine-particle residence times of ~ 1 year. Once delivered to the bottom sediments, contaminant and particle burial is slowed by the effects of resuspension and mixing of surface sediments by aquatic organisms. Several studies have focused on the atmospheric transport, reactivity and deposition of these compounds but relatively few on their in-lake behavior. In this short paper, we provide preliminary information on the delivery and accumulation of PCDD/Fs as recorded in sediments from the Lake Maggiore (LM) (Italy). 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 preliminary air, aerosol and rain profiles. Similarity in isomer profiles in atmospheric aerosol, rain, water column settling matter and bottom sediment point to an important if not dominant contribution from atmospheric deposition to LM, especially derived from aerosol-bound PCDD/Fs. Later high resolution

CASTRO JIMENEZ Javier;  CANUTI Elisabetta;  CHRISTOPH Eugen;  EISENREICH Steven;  HANKE Georg;  MARIANI Giulio;  SKEJO Helle;  UMLAUF Gunther; 

2006-02-14

JRC32571

https://publications.jrc.ec.europa.eu/repository/handle/JRC32571,