Mercury in sediments of lake Päijänne, Finland (original) (raw)
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Half a Century of Mercury Contamination in Lake Vänern (Sweden)
Water, Air, and Soil Pollution
Lake Vänern is Sweden's largest freshwater reservoir. It has been significantly affected by mercury contamination during the latter half of the 20th century. The aim of this study was to analyse the spatial and vertical mercury distribution, whereas 46 sediment cores were sampled in 2001 and analysed for total mercury. Several of these cores were dated presenting sediment accumulation rates varying from 6-8 mm yr −1 outside major rivers to ∼2 mm yr −1 in the deeper areas. This was made using 137 Cs, which was verified by 210 Pb dating. Cluster analysis was used to identify five areas with similar accumulation and mercury concentration regimes. In areas far from shore, surface concentrations ranged from 0.1 to 0.5 ppm Hg, while the deeper layers in contaminated areas held concentrations up to 11 ppm Hg. In total, ∼50 tonnes of mercury accumulated in the lake's sediment between ∼1940-2001; almost 80% (or 37 tonnes) originate from before the mid 70's when the recovery period began, and at least 30 tonnes can be attributed to the former point source-a chlor-alkali industry.
Total mercury and methyl mercury contents in fish from lake Päijänne
Environmental Pollution (1970), 1978
The total mercury and methyl mercury contents of freshwater fish f?om Lake P?iijiinne, Finland, are studied. This is the second largest lake in Finland and has been quite heavily contaminated by mercury. The fish from the limnologically cleanest areas had the highest concentrations of mercury. Twelve species of'fish (1774 analyses of total mercury and 157 of methyl mercury) were analysed during a four-year period. Total mercury was measured by flameless atomic absorption and by gas-liquid chromatography. The average mercury concentrationJbr all fish was 0.65 mg/kg on a fresh weight basis, of which 98.7 % was in a methylated form. The concentration of mercury in fish differed in different parts of the lake and also depended on the weight of the fish.
Mercury Pollution Trends in Subarctic Lakes in the Northern Swedish Mountains
Ambio, 2007
Despite many years of research about mercury pollution, data concerning high-latitude regions of Europe are limited, particularly studies of long-term temporal trends. It is not clear whether the mercury load at high latitudes follows the recent decreasing trends in European mercury emissions or whether the load is still high because of continuing global emissions. In this study we use sediments from 12 lakes, located above the Arctic Circle in the Swedish mountains, to assess the past and recent mercury pollution situation, especially for the last 200 y. The mercury load increased clearly in sediment deposited from the late 19th or early 20th century to a peak between 1960 and 1990. This peak represents an enrichment of 1.4 to 4.2 times over background concentrations. This enrichment is comparable with enrichments in sediments from lower latitudes as well as other Arctic regions. Since the 1990s mercury concentration has declined in 8 of the 12 lakes, i.e., similar to emission trends in Europe.
Development of fish mercury concentrations in Finnish reservoirs from 1979 to 1994
The Science of the total environment, 1998
Mercury (Hg) concentrations in burbot (Lota lota), perch (Perca fluviatilis), northern pike (Esox lucius), roach (Rutilus rutilus), whitefish (Coregonus lavaretus) and peled (C. peled) were monitored in 18 reservoirs situated in western and northern Finland over a period of 16 years (1979-1994). The reservoirs were impounded from 1964 to 1980. The surface areas ranged between 1 and 417 km2. Data from downstream sites and reference lakes were compared to reservoir mercury data. Generally, fish Hg concentrations in reservoirs exceeded those in natural lakes. Shortly after inundation, fish mercury concentrations clearly increased and remain 15-25 years above background concentrations. The mean Hg concentrations in standardized 1 kg pike from 1989 to 1993 was 0.45 mg/kg in natural lakes and 0.58 mg/kg in reservoirs. The 1 mg/kg fish Hg level recommended by health authorities as the upper limit for human consumption was still exceeded in two reservoirs 20 years old or more. The two large...
Environmental factors influencing mercury speciation in Subarctic and Boreal lakes
The Science of the total environment, 2014
Environmental drivers of total mercury (TotHg) concentrations, methylmercury (MeHg) concentrations, and MeHg fractions (a proxy for methylation potential, expressed as %MeHg) were assessed in a synoptic study of 51 lakes in southeast (Boreal) and northeast (Subarctic) Norway. Concentrations of TotHg and MeHg ranged between 0.5-6.6 ng/L and <0.02-0.70 ng/L, respectively. The lakes span wide ranges of explanatory environmental variables, including water chemistry, catchment characteristics, climate conditions, and atmospheric deposition of Hg, sulphur and nitrogen (N). Dissolved organic matter (DOM), measured as total organic carbon (TOC), was the variable most strongly correlated with TotHg (r(2)=0.76) and MeHg (r(2)=0.64) concentrations. Lakes in the Subarctic region had significantly lower TotHg and MeHg concentrations, and %MeHg than lakes in the Boreal region (p<0.01), implying a lower aquatic food web exposure of aqueous Hg species in Subarctic Norway than in the Boreal la...
Total mercury (T-Hg) and organic mercury (mainly methylmercury, MeHg) concentrations in the most important compartments (water, sediment, macrophytes, zooplankton, mussels and fish) of the shallow and eutrophic Lake Candia (Turin, Northern Italy) were measured. The decreasing sequence of the T-Hg concentrations is as follows: cat-fish (143 µg kg -1 d.w.), zooplankton (77 µg kg -1 d.w.), Unio pictorum mancus (37.9 µg kg -1 d.w.), macrophytes (28.9 µg kg -1 d.w.). The content of mercury in mussel tissues increased with the size of the animal, but the relationship between Hg concentration and tissue weight was negative, indicating that the rate of mercury accumulation was lower than the tissue growth rate. The amount of mercury accumulated in the mussels living in the lake sediments was estimated to be 0.54 µg m -2 . The importance of mercury biomagnification is also discussed.
Journal of Environmental Sciences, 2010
The aim of this study was to characterize mercury (Hg) contamination in the coastal waters of the Southern Baltic Sea, and to investigate transformations of Hg in the initial links of the marine food chain. Concentrations of Hg in water, particulate matter, plankton and macrophytes at various stations in the coastal zone (a bay with restricted water exchange, near an industrial city, river mouths, and the open sea) were measured in 2006-2008. Hg concentrations observed in the Southern Baltic varied greatly, showing the highest average values in all environmental compartments near the river mouths. In shallow, sheltered parts of the gulf, where water exchange is restricted, Hg concentrations in the water and in macrophytes were elevated relative to those in the coastal zone of the deeper part of the bay and in the open Baltic. Distance to the river mouth, terrestrial runoff, and quantity and quality of organic matter were more important than seasonal variations in controlling Hg and Hg SPM concentrations in water samples. Mercury concentrations in the surface microlayer at the air/sea interface were over 10 times higher than those in the bulk surface water. Concentrations of Hg in macrophytes in the winter were significantly higher than those in the warm seasons (spring, summer, autumn). This was probably the combined effect of higher availability of Hg in porewaters and leaf growth inhibition.