Evaluation of the ecotoxicity of sediments from Yangtze river estuary and contribution of priority PAHs to ah receptor--mediated activities.

Li Liu,Tilman Floehr,Ling Chen,Kathrin Eichbaum,Hongxia Xiao,Ying Shao,Lili Zhang,Yan Yan,Henner Hollert,Lingling Wu,Aditya B Pant

doi:10.1371/journal.pone.0104748

Abstract

In this study, in vitro bioassays were performed to assess the ecotoxicological potential of sediments from Yangtze River estuary. The cytotoxicity and aryl hydrocarbon receptor (AhR)-mediated toxicity of sediment extracts with rainbow trout (Oncorhynchus mykiss) liver cells were determined by neutral red retention and 7-ethoxyresorufin-O-deethylase assays. The cytotoxicity and AhR-mediated activity of sediments from the Yangtze River estuary ranged from low level to moderate level compared with the ecotoxicity of sediments from other river systems. However, Yangtze River releases approximately 14 times greater water discharge compared with Rhine, a major river in Europe. Thus, the absolute pollution mass transfer of Yangtze River may be detrimental to the environmental quality of estuary and East China Sea. Effect-directed analysis was applied to identify substances causing high dioxin-like activities. To identify unknown substances contributing to dioxin-like potencies of whole extracts, we fractionated crude extracts by open column chromatography. Non-polar paraffinic components (F1), weakly and moderately polar components (F2), and highly polar substances (F3) were separated from each crude extract of sediments. F2 showed the highest dioxin-like activities. Based on the results of mass balance calculation of chemical toxic equivalent concentrations (TEQs), our conclusion is that priority polycyclic aromatic hydrocarbons indicated a low portion of bio-TEQs ranging from 1% to 10% of crude extracts. Further studies should be conducted to identify unknown pollutants.

Highlights

Marine ecosystem contamination has been greatly affected by human activities
3.1 Cytotoxicity of crude extracts and multilayer fractions The results of the Neutral red retention (NR) assay on the crude extracts are shown in
According to a sediment classification system of sediments found in Germany [33], the threshold values of NR biotest system are as follows: NR50.80 mg/mL, non-toxic; 80$NR50$31 mg/mL, moderately toxic; and NR50,31 mg/mL, strongly toxic

Summary

Introduction

Marine ecosystem contamination has been greatly affected by human activities. As a coastal transitional system, an estuary serves as a recipient of environmental contaminants derived from land and rivers as well as the atmosphere. Sediments in estuaries are the main sinks of numerous potential chemical and biological pollutants. These sediments may be considered as a secondary source of water pollution or be absorbed by benthic organisms via bioaccumulation. Sediments as contaminants in rivers and estuaries may pose a potential threat to aquatic organisms and human health. Fish cell lines have been successfully used as a biological alternative of animal tests to assess the toxic effects of sediment extracts [4,5]. RTL-W1 is commonly used to determine the acute cytotoxicity and CYP1A-based EROD activity of sediment extracts [2,7]

Objectives

Methods

Results

Conclusion