Thallium in the marine environment: First ecotoxicological assessments in the Guadalquivir estuary and its potential adverse effect on the Doñana European natural reserve after the Aznalcóllar mining spill (SW Spain)

Abstract

Thallium (Tl) is an extremely toxic but little-studied element in the marine environment and practically no information has been reported on the levels of Tl in marine organisms. After the Aznalcóllar mining spill (April 1998), high levels of metals were put into the environment. This acidcontaminated medium was responsible for the initial pollution effects measured in the Guadiamar River, which is an affluent of the Guadalquivir River and very close to the biggest natural reserve in Europe (Doñana). Four different species were used in the monitoring from April to September 1998 and a sediment field bioassay to check bioacumulation was performed. We present the first ecotoxicological evaluation of the mining spill in the Guadalquivir River, with reference to Tl, a little-known metal. Also, Pb and Cd data were compared to Tl during field sediment testing. Results show low levels of this metal in all of the organisms studied and they do not show any increase in the level of this metal, ranging from 40 to 90 ng g -1 , 80 to 210 ng g -1 , 15 to 98 ng g -1 and 75 to 125 whole body dry weight for Scrobicularia plana, Liza ramada (muscle), Crassostrea angulata and Uca tangeri, respectively. These are the first field data of Tl concentration measured using estuarine organisms. Field sediment toxicity test results

Multivariate statistical analysis of heavy metals in soils of a Pb–Zn mining area, India

“…Thallium is a rare but ubiquitous trace element with average concentrations of 0.49 ppm in continental crust and 0.013 ppm in oceanic crust (Delvalls et al 1999;Peter and Viraraghavan 2005). Mean concentrations of thallium in the earth's crust are of the order of 0.1-1.7 mg/kg, mainly present in sulfide ores of zinc, copper, lead, and also in coal (Smith and Carson 1977).…”

Speciation and Determination of Tellurium in Water, Soil, Sediment and other Environmental Samples

“…Tl + is stable and has properties similar to potassium; Tl 3+ , which resembles aluminum, has strong oxidizing properties and is slowly converted to a monovalent state (Delvalls et al 1999). Table 15.3 presents data on the occurrence of thallium in the environment.…”

“…Thallium salts were extensively used to treat syphilis (since 1883), and to reduce night sweats in tuberculosis patients (Delvalls et al 1999). Application of thallium salts as poisons for rodents and later, as insecticides began in 1920 and for the following 45 yr it was the principal use for this element (Nriagu 1998).…”

Removal of Trace Thallium from Industrial Wastewater by Fe0-Electrocoagulation

“…Tl(III) usually exists in water such as lake water or marsh water, which is rich in colloids and organic matter [12]. Yet, under normal circumstances, Tl(III) is converted to a monovalent state as it possesses a strong oxidizing tendency [13]. So, in most natural environments, thallous compounds are the dominant species [14].…”