Historical records of the deposition fluxes of polycyclic aromatic hydrocarbons (PAH) in 10 remote high altitude lakes distributed throughout Europe have been studied. Cores from each site were dated radiometrically, and the results were used for the reconstruction of the pollutant changes between 1830 and present. In general, both PAH pyrolytic fluxes and concentrations (Σ = 23 compounds) increased from uniform background levels (5−30 μg m-2 yr-1, 20−100 ng g-1 dw, respectively) at the turn of the century to maximum values in 1960−1980. After these peak values a slight decrease to present day levels has been observed in some lakes, though they are still 3−20 times greater than the preindustrial period. Distinctive features in the downcore PAH profiles and concentrations between sites allowed for differentiation between five regions in Europe:  peripheral areas (Norway and the Iberian Peninsula), Pyrenees and western Alps, central Alps, Tatra Mountains, and the Arctic. Atmospheric PAH inventories were estimated from the vertical integration of sedimentary inventories using 210Pb to correct for postdepositional transport processes. This approach consistently reduces variability among lakes from the same region. The results obtained define the lakes in the Tatra mountains and that on Spitsbergen Island as those of highest and lowest atmospheric PAH input. The other lakes exhibit lower differences although their atmospheric inventory values group consistently with the above-mentioned regions.

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Hexachlorocyclohexanes (HCHs; alpha- and gamma-isomers), endosulfans (alpha- and beta-isomers and the sulfate residue), hexachlorobenzene (HCB), dichlorodiphenyltrichloroethane (DDTs), and polychlorobiphenyls (PCBs) were measured in waters from three European remote mountain lakes situated in the Alps, Pyrenees, and Caledonian mountains. Sampling encompassed both ice-free and ice-covered periods at different water column depths. High HCH concentrations were found in all lakes, those in the Alps and Pyrenees (990-2,900 pg/L) being among the highest recorded in continental waters. Endosulfans and endosulfan sulfate (120-1,150 pg/L) were the second major group of organochlorine contaminants, showing a remarkable stability upon atmospheric long-range transport. The concentrations of HCB, DDTs, and PCB (4-8, 0.6-16, and 26-110 pg/L, respectively) were low in comparison with other continental waters. Hexachlorocyclohexanes, endosulfans, and HCB were essentially found in the dissolved phase. Phase partitioning of the more hydrophobic compounds exhibited a dependence on temperature and water-suspended particles. Comparison between different sampling seasons and water depths indicated a remarkable concentration uniformity within lake, but major interlake differences. Normalization to turnover rates showed higher interlake similarity. Preferential accumulation of the less volatile compounds in the Alp lake and significant increase of baseline contributions of organochlorine compounds and residues in the Caledonian lake are also evidenced from these turnover rates.

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Abstract:Urban flooding is an increasing problem in developing countries, thus understanding flood dynamics is necessary to establish guidelines on urban development and flood management. This paper studied the lower reaches of the Andalien River basin, situated on the coast of the Greater Concepcion Metropolitan Area (CMA), the second most urbanized area in Chile. This basin experienced a record 21 flood events in the last 50 years. Patterns in the evolution of urban growth were evaluated using a historical analysis ) that specifically focused on how these patterns interact with zones that are prone to flooding over different return periods. Our model applied to the CMA, but is sufficiently transversal to be applied in similar areas. It was determined that the built-up area increased by 1457 ha and had an urban form vulnerable to future flooding due to its location on landforms exposed to flood risk, with altitudes of <8 m and slopes of <0.5 • . The bankfull channel of the Andalien River lost 18.4% of its area. Upstream, management of the river decreased smaller floods for a return period of two, five, and 10 years; however, for a return period of 500 years, risk remained at high levels. These findings help to rethink and improve urban planning and the response of Chilean cities in relation to flood hazard.