Organic micropollutants in lakes: a sedimentological approach

Many very persistent and lipophilic compounds, considered to be of concern for chronic toxicity and bioaccumulation, are generally present in surface waters at very low and variable concentrations. Sediments represent a concentrated pool for these compounds and consequently they are often analyzed instead of water. Some theoretical models have been proposed recently (Håkanson, 1980; Galassi and Migliavacca, 1986; Provini et al., 1987) in order to estimate the concentration of these pollutants in water and their potential risk for aquatic biota and human health. In this work sediments from three subalpine lakes located in Northern Italy, very close to each other but with different anthropogenic loads, were collected at several stations for determination of the classes of organic micropollutants of urban, industrial, and agricultural origin. Results show that urban and industrial pollution are predominant in this area. Two classes of micropollutants seem to be most related to anthropogenic activities: PAH and trichloroalkylphosphates. The first reaches lake sediments through atmospheric deposition and point sources; the second, present only in two lakes, is more likely to be due to industrial effluents. The advantages and limitations of the sedimentological approach for risk assessment in the aquatic environment are discussed.