Geochemical characteristics of rare earth elements in windowsill dust in Baotou, China: influence of the smelting industry on levels and composition.

Smelting is one of the main sources of rare earth elements (REEs) in large scale smelting regions that have been neglected before. To provide experimental evidence on the influence of smelting processes on REEs in windowsill dust, this study investigated the concentration, chemical fractions, and spatial distribution of 14 REEs in windowsill dust and assessed the possible influence of smelting processes on the geochemical behavior of these REEs. A total of 46 windowsill dust samples were collected from different locations in Baotou, a typical industrial city for large-scale smelting. The fractions of REEs were analyzed by Tessier sequential extraction analysis. The enrichment factor (EF) was adopted to assess the contribution of anthropogenic emissions of REEs. The loess-normalized REE patterns of windowsill dust are similar to those of the iron ore of the Bayan Obo mine, but differ from those of the local soil. The concentrations of La, Ce, Pr, Nd, and ∑REEs in the residual fraction and total digestion decrease gradually with the increase in distance from the smelter in the downwind direction. These results suggested that the accumulation and fractionation of REEs in windowsill dust are considerably influenced by smelting. The emission of smelting is the main source of REEs for windowsill dust in Baotou.