Formation of water disinfection byproduct 2,6-dichloro-1,4-benzoquinone from chlorination of green algae

摘要

We report that green algae in lakes and rivers can serve as precursors of halobenzoquinone(HBQ) disinfection byproducts(DBPs) produced during chlorination. Chlorination of a common green alga, Chlorella vulgaris, produced 2,6-dichloro-1,4-benzoquinone(2,6-DCBQ), the most prevalent HBQ DBP in disinfected water. Under varying p H conditions(p H 6.0–9.0), 2,6-DCBQ formation ranged from 0.3 to 2.1 μg/mg C with maximum formation at p H 8.0. To evaluate the contribution of organic components of C. vulgaris to 2,6-DCBQ formation, we separated the organics into two fractions, the protein-rich fraction of intracellular organic matter(IOM) and the polysaccharide-laden fraction of extracellular organic matter(EOM). Chlorination of IOM and EOM produced 1.4 μg/mg C and 0.7 μg/mg C of 2,6-DCBQ, respectively. The IOM generated a two-fold higher 2,6-DCBQ formation potential than the EOM fraction, suggesting that proteins are potent 2,6-DCBQ precursors. This was confirmed by the chlorination of proteins extracted from C. vulgaris: the amount of 2,6-DCBQ produced is linearly correlated with the concentration of total algal protein(R2= 0.98). These results support that proteins are the primary precursors of 2,6-DCBQ in algae, and control of green algal bloom outbreaks in source waters is important for management of HBQ DBPs.