Mercury sediment record

Engstrom DR, Polhnan CD, Fitzgerald WF, Balcom PH. 2003. Evaluation of recent trends in atmospheric mercury deposition in south florida from lake-sediment records. Tallahassee (FL) Florida Department of Environmental Protection, 27 pp. 

Roulet M, Lucotte M, Canuel R, Farella N, CorrreeUes M, Guimaraes J-R, Mergler D, Amorim M. 2000. Increase in mercury contamination recorded in lacustrine sediments following deforestation in the central Amazon. Chem Geol 165 243-266. 

Mercury Fluxes and Sediment Records. Our calculations of lakewide Hg fluxes from more than 80 dated sediment cores from seven small headwater lakes reveal a regionally consistent increase in Hg inputs from preindustrial times to the present the modern Hg flux to each of these lakes is about 3.7 times that of the early 1800s. Such increases are typical of that reported in other investigations of lake sediments from remote or rural sites in eastern North America (3, 6, 7,10, 23). Most researchers have concluded that the increase is anthropogenic and that the Hg must be transported through the atmosphere and deposited on the lake and its terrestrial catchment. 

Thomas (1972) reported a sediment record of recent mercury contamination in Lake Ontario. The following year a similar resnlt was reported from the more rural Lake Windermere (Aston et al, 1973), and a sedimentary record of Pb contamination was reported from Lake Washington (Crecelius Piper, 1973). In the years that followed, similar results were found elsewhere, and for many trace elements in addition to Hg and Pb (Kemp Thomas, 1976 Bertine Mendeck, 1978 Norton Hess, 1980 Rippey et al., 1982 Davis et al., 1983 Ochsenbein et al., 1983 Norton 1986 Verta et al., 1989 Norton et al., 1992 Engstrom et al., 1994). These studies have consistently shown enhanced accumulation of Cd, Cu, Pb, Zn and Hg. Generally, increases in Ni, Co and V have not been found, except where there are major local sources (e.g., Cornett et al., 1989). 

In the profiles of the core from the industrial area, mercury displays the highest accumulation. Mercury in this area, close to the industrial district, has probably derived from a large chloralkali plant which has employed mercury cathodes since the fifties. Whereas, at present, very severe measures are taken to prevent mercury spills into the Lagoon, in the past, polluted waters and solid materials were discharged almost untreated. In the most superficial strata a marked decrease in the accumulations is, in fact, recorded. Lead and Cd accumulations are lower here by a factor of 5-10. The presence of cadmium in the sediments of the Lagoon has been referred to sphalerite (ZnS) processing on the basis of a strict concomitant... 

A second risk zone corresponds to Monzon (17,042 inhabitants), a highly industrialized city in the middle Cinca River. Its industrial activity has caused the historical release of organic and inorganic compounds to the river coming from chlor-alkali industry, from production and utilization of solvents and organochlo-rine pesticides, and from the use of brominated flame retardants in the production processes. Very high concentrations of mercury have been recorded for sediment and fish samples in the downstream of Monzon [2-4]. 

Kiorboe, T., F. Mohlenberg, and H.U. Riisgard. 1983. Mercury levels in fish, invertebrates and sediment in a recently recorded polluted area (Nissum Broad, western Limljord, Denmark). Mar. Pollut. Bull. 14 21-24. 

While atmospheric concentrations of mercury are low ( 1-2 ng m ), the total mass of mercury stored in the atmosphere is quite large. Fitzgerald [13] estimated the mass of mercury in the atmosphere to be 5000 metric tons. Current research using core samples from sediment, peat bog and glacial ice as a record of metal deposition indicate that mean amounts of total mercury in the atmosphere have been increasing over the past 100 years with some research indicating a recent... 

Mercury levels in the Danube sediment samples were rather low. In approximately 50% of the samples, Hg concentrations were under detection limits, while in the others they were below 1 mg kg". Maximum concenfration of this toxic metal was 1.15 mg kg". Only in the canal sediment samples were mercury concenfrations exceeding 1 mg kg" recorded, the maximum level being up to 3.5 mg kg" . 

Sediment samples taken only along the right and left riverbank revealed the consequences of pollution with mercury, oil and derivatives. Maximum concentrations were as follows mercury - 0.28 mg kg", mineral oil - 371.7 mg kg" and PAHs -454.2 (xg kg". The presence of DCE and PCBs was not recorded in sediment samples. 

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