Historical changes in polycyclic aromatic hydrocarbons (PAHs) input in Lake Baiyangdian related to regional socio-economic development.

The accumulation of polycyclic aromatic hydrocarbons (PAHs) over a period of almost 180 years was studied in a sediment core collected from Lake Baiyangdian in northern China. Total PAHs concentration varied from 97.2 to 2402 ng g(-1) dry weight. We found the highest total PAH concentration in 1940s and 1990s, and a decreasing trend from 1990 until present. The warfare and increasing economic activity had the largest impact on the PAH vertical distribution. The implemented measures for pollution control in catchment since 1990 might reduce point source input of PAH in some degree in recently. The historical record of PAHs is different from the developed countries and areas due to difference in socio-economic development condition. PAHs in the core are dominantly pyrogenic in source, i.e., they are mainly from the incomplete combustion of wood and coal. PAHs from terrigenous organic matter input decreased obviously from the 1950s due to rainfall reduction during this period.