Occurrence and Distribution of Chlorobenzenes in the Tonghui River of Beijing, China

Eleven chlorobenzenes (CBs) in surface water and sediments of Tonghui River, a main urban drainage river of Beijing in China, were determined in October 2003, January 2004, and April 2006. CBs were widely detected and the [summation operator]CB concentrations in water ranged from 89.9 to 6638.0 ng/L, with average values of 1902.8 ng/L in 2003, 2084.0 ng/L in 2004, and 1281.2 ng/L in 2006, respectively. The [summation operator]CB concentrations in surficial sediments varied from 18.2 to 1827.7 ng/g dry weight (dw), with average values of 897.4 ng/g dw in 2003, 653.4 ng/g dw in 2004, and 562.6 ng/g dw in 2006, respectively. Nonparametric statistical analysis (Mann-Whitney U test) showed that there were no statistically significant changes in [summation operator]CB concentrations in either surface water or sediments over the period 2003-2006. The distribution pattern of CBs in the Tonghui River indicates that further effort is warranted in reducing local sources of contaminants. Additionally, the [summation operator]CB levels in sediment samples were found to be dependent on total organic carbon contents.