Sedimentary mercury stable isotope records of atmospheric and riverine pollution from two major European heavy metal refineries

Variations in sediment total mercury (Hg) concentrations and Hg stable isotopic compositions were investigated in the vicinity of two former non-ferrous metal (zinc) refineries in Lommel (Kempen, Belgium) and Viviez (Aveyron, France). Contaminated Kempen sediment Hg levels are up to 6.8 mg kg(-1) corresponding to a peak in atmospheric Hg deposition of similar to 1.0 mg m(-2) year(-1) for the year 1968. Atmospheric and riverine Hg contamination from the zinc refinery point sources in Belgium and France present mass dependent (delta Hg-202 of -032 to + 0.71 parts per thousand) and small mass independent Hg isotope signatures (Delta Hg-199 of -0.15 to -0.04 parts per thousand) that are significantly different from local geochemical background Hg (delta Hg-202 of -1.44 to -0.75 parts per thousand; Delta Hg-199 of -0.35 to + 0.06 parts per thousand). In addition we found that selected sphalerite (ZnS) ore concentrates carry average delta Hg-202 of -0.65 +/- 1.33 parts per thousand. (2 sigma, n = 4), similar to published Hg minerals (mainly HgS) with delta Hg-202 of -0.64 +/- 1.82 parts per thousand (2 sigma, n = 125). Congolese ZnS ores from the Kipushi deposit show significant mass independent Hg isotope fractionation with average Delta Hg-201 of -0.09 +/- 0.02 parts per thousand, and Delta Hg-199 of -0.08 +/- 0.01 parts per thousand (2 sigma; n=3), possibly suggesting a partial atmospheric origin for trace Hg within the Kipushi ore deposit Similar to Zn and Cd isotopes, high temperature non-ferrous metal refining processes appear to preferentially retain the heavy Hg isotopes in slag residues: Hg contaminated Cajarc (France) river sediment delta Hg-202 values of + 022 +/- 0.52 parts per thousand. (2 sigma, n=17), considered to present an integrated picture of post-WWII 20th century slag tailing effluents, are significantly enriched in the heavier Hg isotopes relative to Kempen core B1 atmospheric Hg deposition with delta Hg-202 of -0.07 +/- 034 parts per thousand (2 sigma, n=10), as well as relative to Hg containing sulfide minerals with delta Hg-202 of -0.64 +/- 1.82 parts per thousand (2 sigma, n=125). The distinct Hg isotope signatures of natural and anthropogenic Hg suggest that tracing the various Hg emissions into regional Belgian and French ecosystems should be feasible. The highly elevated contamination of Hg in the Kempen warrants further study of local ecosystems including human exposure. (C) 2010 Elsevier B.V. All rights reserved.