Reconstructing 20th century lead pollution and sediment focusing in a peat land pool (Kempen, Belgium), via Pb-210 dating

Abstract

Pb-210 dating of two metal-polluted organic sediment cores obtained near a former pyrometallurgical zinc smelter in Lommel, Belgium have been used to reconstruct atmospheric lead deposition rates during the 20(th) century. Independent knowledge concerning historical pollution events and Cs-137 fall-out profiles has allowed a critical evaluation of the CRS, CIC and CF-CS models for the Pb-210 age interpretation. Resulting ages for the three models suggest that, in this case, the CIC model gives the most accurate interpretation of historical pollution events and atmospheric lead fall-out. The Pb-210 water-sediment flux was estimated at 141-1158 Bq.m(-2).yr(-1) for one site and 62-106 Bq.m(-2).yr(-1) at the other site, during the last century. The large difference illustrates that sediment focusing was important on a small spatial scale (10 m). The direction of focusing correlates with the predominant wind direction. Maximum atmospheric lead deposition rates were found to be 1.63+/-0.59 g.m(-2).yr(-1) around 1968 AD, which is 2 orders of magnitude larger than the Belgian average in 1980 AD, and 5 orders larger than Holocene atmospheric lead deposition.