Research project: Development of cost-effective methods for minimising risk from heavy metal pollution in industrial cities: A case study of mercury pollution in Pavlodar (TOXICMANAGEMENT)

Currently Active:: Yes

A project funded by the EU INCO Programme

Project Overview

Plume of mercury contaminated groundwater — Plume of mercury

Field work carried out in summer 2001 involved a detailed survey of the topsoils at and around the former chlor-alkali workshop, an extensive survey of the groundwater quality beneath the plant and in the surrounding region, and an investigation of the sediment and water quality in nearby Lake Balkyldak. Fish from the lake were also sampled to assess human health and ecological risks. A geographic information system was created and was used for the design of the second year sampling programmes and to investigate the spatial distribution of the contamination.

Activities in the second year involved further soil sampling on site at depths of up to 4 metres, an investigation of the sediment and water quality of the River Irtysh, and sampling of fish from the river and its oxbow lakes. Thirty-seven new observation boreholes were drilled to establish the exact location of the contaminant plume in groundwater. Computer modelling of the speed and direction of movement of the plume was carried out for a period of 30 years. Detailed risk analysis and assessment was performed using pre-existing data as well as the data gathered in the 2001 and 2002 sampling campaigns.

The results show that although mercury concentrations in groundwater are high on the site itself and within the narrow band of the plume, the contamination does not appear to have spread more than about 2.5 km from site. Field observations and computer modelling results indicate that the contaminant plume appears to be moving in a north-westerly direction from the site and towards Lake Balkyldak, and that the risk of significant mercury pollution of the Irtysh under the given hydrogeological conditions is very low. Mercury levels in groundwater in the general region are low and concentrations measured in Pavlodarskoye village, located ca. 4 km from the site on the River Irtysh, were not elevated above background, indicating that other routes of exposure such as the consumption of contaminated fish from the lake are far more important.

The soils at the former electrolysis workshop and near other buildings associated with chlor-alkali production were found to be very heavily polluted. The pastureland between the plant and Lake Balkyldak is contaminated to a lesser degree. Contaminated surface waters and the uncovered openly accessible waste lagoons pose a risk to grazing cattle and trespassing humans. Fish from the lake were found to be unfit for human consumption.

Actions for managing the risks have been proposed and steps have been taken by the factory management to put these into practice. Recommendations made include the isolation of secondary sources of soil and groundwater contamination. Measures taken to isolate the main source on site appear to be sufficient to prevent further mercury from entering the groundwater, but an engineered cover is required to prevent infiltration of precipitation, capillary rise and mercury vapour emissions. A ban on fishing should be enforced for Lake Balkyldak.