Distribution characteristics and risk assessment of polyhalogenated carbazoles in sea water of the Yellow Sea

Polyhalogenated carbazoles (PHCZs), a novel type of organic pollutants with dioxin-like toxicity, have gained increasing attention in the past several years. In this study detection and distribution of five PHCZ compounds found in the Yellow Sea region are studied. The range of Sigma PHCZ in the detection area is 0.062-0.322 ng/L (median: 0.112 ng/L), with 3,6-dichlorocarbazole and 3,6-dibromocarbazole content being the greatest, ranging from 0.035-0.269 ng/L and 0.010-0.682 ng/L, respectively, followed by 3-CCZ (0.010-0.020 ng/L). The relative toxicity of PHCZs is evaluated by the toxicity equivalent (TEQ), in which a range of 0-0.19 pgTEQ/L (median: 0.006 pgTEQ/L) is determined. According to the results, PHCZs are widely distributed in Yellow Sea water with relatively lower toxicity, and the impact of natural factors, as well as their potential sources, are discussed in order to provide basic scientific data for the investigation of PHCZs in seawater.