Occurrence of Persistent Organochlorine Pollutants in Sediments from Lake Piediluco, Italy

Abstract

In surficial sediments of Lake Piediluco, a small, riverine, regulated and heavily modified water body in the Central Italian Apennines, contamination by persistent organochlorine pollutants (POPs) was assessed. During spring and autumn, six representative points were investigated. Reflecting a substantial zonation of pollution within this aquatic ecosystem, concentrations were found to vary from site to site. OCPs, particularly DDT and its metabolites DDE and DDD, were detected at varying frequencies and concentrations from 0.301 to 8.185 ng/g d.w., whilst total PCBs (Σ50 congeners) were from 0.570 to 10.206 ng/g d.w. Although both PCB congener-specific and homolog patterns suggest a prevalent presence of Aroclors 1254 and 1260, a more limited likely contribution of 1248 technical mixture is not to be excluded. In the western area of the lake, affected daily by continuous basin water remixing for hydroelectricity production, major seasonal differences in OCP concentrations were found. Conversely, the eastern area was typified by low seasonal fluctuation and small variation among sites. Regardless of either collection site or seasonality, polychlorinated-p-dioxin and furan (PCDD/Fs) contamination were below 8.3 pg WHO-TEQ/g. In contrast to the present study, POP pollution from PCBs, PCDD/Fs and some DDT-derived pollutants has not been investigated so far. Nevertheless, the concentrations are typical of low-polluted or pristine area lakes and are consistently lower than those of other Italian lakes of greater size and depth (e.g., Como, Garda and Maggiore). The physical and chemical properties of investigated analytes are more consistent with probable diffuse point source contamination originating from the catchment area, rather than from atmospheric depositions by regional or long-range transports. Finally, according to the international sediment quality guidelines (SQGs), Piediluco sediments pose a low risk to sediment-dwelling organisms and, more generally, to the wildlife of such aquatic ecosystems.