Algal-derived organic matter as precursors of disinfection by-products and mutagens upon chlorination |
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Authors: | Lui Y S Qiu J W Zhang Y L Wong M H Liang Y |
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Affiliation: | Croucher Institute for Environmental Sciences and Department of Biology, Hong Kong Baptist University, Kowloon Tong, Hong Kong, PR China |
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Abstract: | Algal-derived organic materials (including algal cells, hydrophilic and hydrophobic proteins) from Chlamydomonas sp. (a common green alga in local reservoirs), were chlorinated in the laboratory (20 °C, pH 7, Cl2/DOC ratio of 20 mg Cl2 mg−1). Levels of disinfection by-products and mutagenicity (via Salmonella T100 mutation assay, -S9) over 2 h of chlorination time were determined. The hydrophilic proteins were more effective precursors of chloroform (35.9 μmol L−1 at 120 min), 35 times greater than that from the hydrophobic proteins; whereas the hydrophobic proteins were more potent precursors of direct-acting mutagens (maximum level of 50.1 rev μL−1 at 30 s) than the hydrophilic proteins (maximum level of 3.38 rev μL−1 at 60 min). The mutagenicity of the chlorinated solutions generally reached a peak level shortly after chlorination and then declined afterwards, a pattern different from that of chloroform generation. The results indicate that algal hydrophilic proteins, containing low aromaticity and difficult to be removed via coagulation/flocculation, are important chloroform precursors. It is also suggested that hydrophobic organic intermediates with low molecular weight formed during chlorination may serve as the direct-acting mutagens. |
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Keywords: | Chlamydomonas sp Chlorination intermediate by-products Algal hydrophilic protein Algal hydrophobic protein Mutagenic potency |
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