Concentrations and distributions of 18 organochlorine pesticides listed in the Stockholm Convention in surface sediments from the Liaohe River basin, China.

Organochlorine pesticides (OCPs) were analyzed in 26 surface sediment samples from the Liaohe River basin, and the distributions of and potential environmental risks posed by OCPs in the basin were evaluated. Eighteen OCPs listed in the Stockholm Convention were determined using isotope-dilution gas chromatography-high resolution mass spectrometry. This is the first study of hexachlorobenzene (HCB) in the Liaohe River basin sediments. The total OCP concentrations were 0.39-68.06 ng g(-1) dry weight. The total α-, ß-, γ-, and δ-hexachlorocyclohexane (HCH), the total dichlorodiphenyltrichloroethane (DDT - p,p'-dichlorodiphenyldichloroethane (DDD), p,p'-dichlorodiphenyldichloroethylene (DDE), o,p(')-DDT, and p,p'-DDT), and the HCB concentrations in the sediment samples were 0.1-28.48 ng g(-1) (mean 4.01 ng g(-1)), 0.08-6.52 ng g(-1) (mean 3.07 ng g(-1)), and 0.18-24.8 ng g(-1) (mean 4.38 ng g(-1)), respectively. The HCB concentrations were higher than the concentrations of the other OCPs, and the HCHs and HCB together were the dominant OCPs. ß-HCH was the most abundant HCH isomer. The concentrations of DDTs and other OCPs were relatively low, and the (DDE+DDD)/DDT ratios (>0.5) and DDD/DDE ratios (<1) indicated that no recent DDT inputs had occurred in the Liaohe River system. The main sources of HCHs were probably the historical production and agricultural use of HCH in the study area. The DDT and HCH concentrations were generally below or similar to the concentrations that have been found in other parts of the world. An ecotoxicological evaluation indicated that HCHs in surface sediments pose slight risks to human and ecological health in the Liaohe River basin.

Characterization and distribution of PAHs in surface sediments of Daliao River, China.

The concentrations of 16 priority pollutant PAHs in the samples of Daliao River were analyzed by a method based on Soxhlet extraction, solid-phase extraction clean-up and high performance liquid chromatography-programmable fluorescence/ultra violet detection. The total concentrations of PAHs in Daliao River ranged from 267.9 ng/g to 9,212 ng/g. The highest concentration of PAHs was 9,212 ng/g at the Station 24 (Anshan Railroad Bridge), and the lowest 267.9 ng/g at the Station 19 (Estuary). Compared with the total concentrations of PAHs of rivers in other parts of the world, the degree of contamination of Daliao River by PAHs was moderate to high. Specific compounds or groups of PAHs have been used as molecular markers to differentiate petrogenic and pyrogenic origin. The results showed that the main sources of PAHs in Daliao River were pyrolytic inputs such as combustion of coal, wood and petrogenic chemicals. The data was also compared by mean of two guideline values, an effects range-low (ER-L) and effects range-medium (ER-M), to assess the potential biological effects of the sediment adsorbed PAHs. It showed that the PAHs in some sites of Daliao River would exert adverse biological effects.