Mercury speciation and mobility in soils of industrial areas in the Baikal region, Southern Siberia, Russia

Abstract

Mercury speciation and mobility in soils as a result of the chlor-alkali and metallurgy industries in Baikal region was investigated. In the period from 1973 to 1998, chlorine and alkali at the plant were produced using metallic mercury. Within the period of plant operation, the total mercury emissions release to the environment amounted to 1327 tons. The former Angarsk metallurgic plant for the production of arsenic is another technogenic source of mercury. The plant was shut down in 1949, but the technogenic dumps with high concentrations of arsenic, mercury and another heavy metals were located in the town for more than 60 years. These plants are located on the banks of the Angara River and are significant sources of technogenic mercury for the environment of the Baikal region. Mercury speciation was studied in soils near these plants. Mercury species were extracted by sequential extraction, and included water-soluble, acid-soluble, organic, tightly bound and sulfide fractions. High mercury concentrations were found in organic (41–61%) and tightly bound (38–56%) fractions in soils near the chlor-alkali plant. For the metallurgical plant soils, mercury was mainly found in the tightly bound (40–64%) and sulfide (31–51%) fractions. Mercury concentrations in mobile water and acid-soluble fractions of soils were low (0.17–2.27 and 0.04–1.06%, respectively). Such mercury distribution in the fractions was dependent on the primary mercury species that entered the soils from the two technogenic sources. The results indicate high mercury immobilization in soil and low potential bioavailability by plants.