Atmospheric input of POPs into Lake Maggiore (Northern Italy): PCDD/F and dioxin-like PCB profiles and fluxes in the atmosphere and aquatic system.

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 were 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. 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. PCDD/F concentrations in air of 25 WHO-TEQ fg m(-3) and DL-PCBs of 7 WHO-TEQ fg m(-3) were measured. Bulk atmospheric deposition yielded 140 and 28 WHO-TEQ pg m(-2) per week for dioxins/furans and DL-PCBs, respectively. Aquatic settling material exhibited concentrations of 11 WHO-TEQ pg g(-1) for PCDD/Fs and 2 WHO-TEQ pg g(-1) for DL-PCBs. Weekly settling material fluxes of 50 WHO-TEQ pg m(-2) and 10 WHO-TEQ pg m(-2) were obtained for PCDD/Fs and DL-PCBs, respectively. PCDD/Fs concentrations in surface sediments varied from 0.1 to 17 WHO-TEQ pg g(-1) whereas values ranged from 0.03 to 6 WHO-TEQ pg g(-1) for DL-PCBs. The concentrations obtained in the environmental compartments studied suggest a situation of low level contamination. PCDD/Fs and DL-PCBs congener 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.

Atmospheric input of POPs into Lake Maggiore (Northern Italy): PBDE concentrations and profile in air, precipitation, settling material and sediments.

Large lakes are sinks for many chemical pollutants but the role of the atmosphere in delivering PBDEs (polybrominated diphenyl ethers) is not well known. In this study we estimated inputs of PBDEs from the atmosphere to Lake Maggiore and the delivery via settling material to accumulated bottom sediments. Sampling consisted of one simultaneous week of air and bulk deposition during Spring 2005, an integrated 4-month period of collected settling material (via sediment trap), and superficial bottom sediments near the sediment trap deployment and tributary mouths of the lake. Concentration of total PBDEs (Sigma 8) in the sediments ranged between 0.06 and 27 ng g(-1), and two different patterns were observed. One pattern was dominated by BDE-47 and BDE-99 and a second by BDE-209. The latter pattern suggested input from local source(s). Total PBDEs in air were 107 pg m(-3) with a pattern dominated by BDE-47. The bulk deposition rate of total PBDEs for precipitation was measurated to be 17.6 ng m(-2) day(-1) where BDE-209 exhibited the highest concentration. For aquatic settling material the flux was 3.57 ng m(-2) day(-1) and was dominated by congeners BDE-47 and BDE-99. The bulk deposition and settling material fluxes were in the same range for the less brominated congeners, while for the hepta- and deca-brominated PBDEs the fluxes in the settling material were one order of magnitude lower. This suggests different sedimentation processes among congeners and/or the presence of local sources that influence the relative distribution in water column.

Seasonal variations of selected herbicides and related metabolites in water, sediment, seaweed and clams in the Sacca di Goro coastal lagoon (Northern Adriatic).

This study assesses the status of Sacca di Goro coastal lagoon (Northern Adriatic, Italy) with respect to watershed pollution. Because 80% of its watershed is devoted to agriculture, plant protection products and their metabolites were found in the water column, sediments (the upper 0-15 cm layer), macroalgae (Ulva rigida) and clams (Tapes philippinarum). Five seasonal sampling campaigns were performed from May 2004 to April 2005 and concentrations measured in five stations in the lagoon and six in the watershed. Relatively high concentrations of the s-triazine - terbuthylazine -, urea herbicides - diuron - and alachlor were detected through the year mainly at stations directly influenced by the Po di Volano inflow. The concentrations of products in use follow a clear seasonal pattern with spring peaks. This pattern is also visible in the sediments as well as in biota. Among metabolites, hydroxylated compounds prevailed, often with concentrations greater than those of the parent compounds. For the most part of the year, the concentrations in biota were close to detection limits, with concentration peaks in spring.

A 3D hydrodynamic fate and transport model for herbicides in Sacca di Goro coastal lagoon (Northern Adriatic).

Sacca di Goro is a shallow coastal microtidal lagoon with a surface area of 26 km2, and an average depth of about 1.5m. Fresh water pollutant loads from Po River branches and several drainage canals lead to anthropogenic eutrophication, frequent summer anoxia crises and chemical contamination. Such events not only affect the lagoon ecosystem but also cause serious economic losses, the lagoon being the second largest producer of clams in Italy. The present work aims at using a fate model coupled with COHERENS 3D hydrodynamic model to simulate and to explain the spatial distribution and temporal variations of s-triazines herbicides in the Sacca di Goro lagoon. The simulation results of spatial and temporal dynamic behaviour of atrazine, simazine and terbuthylazine have been compared with experimental data obtained during an annual monitoring programme.