Local impacts of coal mines and power plants across Canada. I. Thallium in waters and sediments

Abstract

A Canada-wide survey was undertaken of sites associated with coal mines and coal-fired electrical generating stations. Several water samples were found to contain very high concentrations of thallium, iron and manganese. High thallium concentrations were found in several sites in Eastern Canada, in spite of the greater coal consumption and production in the western and central regions. The data suggest that coal type (rather than quantity) and/or regional geological contributions are responsible for the high Tl concentrations observed. Our findings, coupled with others around the world, strongly indicate that Tl is an environmental pollutant. In sediments, the observed high ratios of Tl/Hg suggest there is an enrichment of Tl by at least 25% when compared to crustal concentration ratios.

Thallium Contamination of Water in Canada

“…All samples were preserved with 0.2% ultrapure nitric acid. Detailed samplings have been reported (Cheam et al 1995(Cheam et al , 1998(Cheam et al , 2000.…”

“…It was reported that thallium concentration was higher in streams receiving wastewater and runoff from certain mines, mills, or smelters processing copper-, lead-and zinc-bearing materials than upstream or downstream concentrations. Cheam et al (2000) also found that ninety-five percent of the time, the upstream concentra-tions of thallium and other metals were smaller than downstream, discharge or cooling ponds of the coal mine and power plant operations across Canada. Gold tailings and concentrates are known to contain very high or very low concentrations of thallium.…”

“…After the rapid advance in sensitive instruments such as the ICPMS, there have been more Tl data reported in environmental studies, indicating an increased interest in this element. In our laboratory, we have developed a highly sensitive instrument, the Laser-Excited Atomic Fluorescence Spectrometry, LEAFS (Cheam et al 1992(Cheam et al , 1996a, and applied it to the study of several important Canadian environmental issues dealing with major ecosystems such as the Canadian Arctic and the Great Lakes, as well as to study the pollution from the operations of coal mines and coal power plants across the country, interstitial pore water, and various lakes and rivers across the country (Cheam et al 1993(Cheam et al , 1995(Cheam et al , 1996b(Cheam et al , 1998(Cheam et al , 2000.…”

Thallium isotope composition of the upper continental crust and rivers—An investigation of the continental sources of dissolved marine thallium

“…Based mainly on the work of Lin and Nriagu (1999) and Cheam et al (2000Cheam et al ( , 2001. Rehkämper and Nielsen (2004) estimated that pristine rivers have a global mean dissolved Tl content of 7 Ϯ 3 ng/kg.…”

The Oxidative Precipitation of Thallium at Alkaline pH for Treatment of Mining Influenced Water

“…Surfaceand ground-water may be impacted by Tl leaching from naturally occurring mineralized zones; stream concentrations above 2 lg/L have been observed in areas of sulfidic deposits (Xiao et al 2003). A survey of coal mine and power plant sites in Canada reported Tl concentrations \2 lg/L (Cheam et al 2000). However, the discharge from an ash lagoon at a coal power plant in Nova Scotia contained up to 24 lg/L of Tl.…”