Heavy Metals in Soils as Indicator of Sanitary State of Territories: Monitoring of the South of Astrakhan Region

Abstract

The results: 1) long-term monitoring of Hg concentrations and amounts of metals Zc(MnCrVNiCoCuAgZnPbSnMo) in the soils of the area of deployment of the Astrakhan gas complex (AGC; stages: 1991-1997-2007-2012 years); 2) estimates of the dynamics of Hg in soils of villages in the Volga Delta in the period 1995-2009, Since in the Astrakhan region such significant assessment has been undertaken (detail and coverage areas). At the distance of 50 km from AGC on the stages of the control 1997-2007-2012 the tendency for the deterioration of the hygienic condition of the land was discovered. In a separate ghosting the contents of Hg in the soil was up to 285 mg/kg and was approaching a "target" safe levels (300 mg/kg) adopted in Western Europe. The content of Hg in soils to 2007 has increased 6 to 8 times on the leeward of the North-West territories, distant 15 km from AGC. The study established the effect of concentration of Hg in summer in the surface horizon of soils. When handling Hg-containing (70-100 µg/kg) commercial sulfur, a significant role in the deterioration of the hygienic state of the sanitary protection zone belongs to their Eolian distribution of particles from the places of storage, loading and transportation of raw materials. The total number of metals at values Zc(MnCrVNiCoCuAgZnPbSnMo) as the nearest (sanitary protection – up to 5 km) far (5-50 km) and background sites has risen steadily. By 2012, a number of places in the AGC-30 km control zone had already recorded hygienically dangerous levels of total accumulation of metals (up to Zc =34). The spatial variability of this state is largely controlled by the dispersion of emissions by the prevailing East and South-East winds. In the settlements of the Volga Delta, gasification of boiler houses ensured the dispersion of Hg in soils (>90% of its previously accumulated amount). Concentrations decreased to almost background values (20-60 µg/kg). Further quality control of the hygienic state of the territories needs to be repeated sampling of soil and involvement of medical statistics on the incidence of residents of the region.