Mercury pollution of riverine sediments in a typical irrigation area in the Beijing-Tianjin-Hebei region.

The Beijing-Tianjin-Hebei region is China's cultural and political center. Rapid social and economic development has led to serious water pollution in this region. A comprehensive investigation of mercury (Hg) pollution in riverine sediments was carried out in a typical irrigation area in this region. The results show that the total Hg levels in the surface sediments of the Duliujian River Network (DRN) ranged from 0.169 to 1.391 mg kg-1, with an average of 0.528 mg kg-1. The Hg levels at most of the sample points were higher than the background. The Hg fractions were categorized as exchangeable (B1), reducible (B2), oxidizable (B3), and residual (B4). The Hg was mainly present in the B4 fraction (0.439 mg kg-1, on average). The order of the average percentage of different fractions of Hg was B4 > B3 > B2 > B1. A risk assessment using total Hg showed that the potential ecological risk in each section of the DRN ranged from 80.4 to 662 (average = 263). A risk assessment using Hg speciation showed that the average risk for B1 was 3.28%. Because the potential ecological risk is very high, more attention should be given to this risk in the management of the river. This research also provides theoretical support for the study of Hg in the developed area of the agricultural irrigation canal. The information obtained in this study could be used to develop effective management strategies to control Hg pollution in the DRN.