Quaternary ammonium compounds (QACs) used as cationic surfactants have been ubiquitously detected in water, sediment, sludge, etc. QACs residue can be examined highly at several hundreds or even thousands of mg/kg (dry weight, dw) in sludge particularly. Because of their high surface activity and moderate-high toxicity, QACs can cause toxic effects on fish, aglae, bacteria, daphnids, etc. at relatively low concentrations. Furthermore, QACs significantly influence the bioavailability and mobility of the other coexisting pollutants in environment. The environmental problems of QACs have attracted a great attention in devoloped countries, however, little literature is available in China. Therefore, this paper reviews the pollution source, analytical methods, pollution status, fates and toxic effects of QACs in environment. The currently existing problems and trends are also discussed. We hope that this review will provide valuable reference for the enviromental researches on QACs in China.

Contents
1 Introduction
2 Sources of QACs in environment
3 Analytical methods
3.1 Sample extraction and purification
3.2 Sample analysis
4 Pollution status and fates of QACs in environment
4.1 QACs in water
4.2 QACs in sewage sludge and sediment
4.3 QACs in soil and agricultural crops
4.4 Fates of QACs in environment
5 Toxicity of QACs
6 Conclusion and outlook