Study On The Formation Of Halogenated Disinfection By-products In Aquaculture Waters

Although the potentially toxic halogenated disinfection byproducts?X-DBPs?have been reported to form from reactions between disinfectants,halide ion and dissolved organic matter?DOM?,their formation in disinfected aquaculture water has been rarely studied.This research studied the formation of brominated disinfection by-products?Br-DBPs?and iodinated DBPs?I-DBPs?in disinfected aquaculture waters by chlorination/iodination.Inductively coupled plasma mass spectrometry?ICP-MS?and ion chromatography?IC?were employed to measure the total organic halogen?TOX?content of X-DBPs.Fourier transform ion cyclotron resonance mass spectrometry?FT-ICR MS?was applied to characterize the composition and distribution of these X-DBPs.After 5 days of disinfection of raw aquiculture seawater samples with sodium dichloroisocyanurate?NaDDC?,trichloroisocyanuric acid?TCCA?and chlorine dioxide?ClO₂?,181,179 and 37 Br-DBPs were detected by FT-ICR MS,and the corresponding TOBr content were 5.01,4.45 and 1.67?M,respectively.Sunlight irradiation was found to reduce the formation of Br-DBPs in chlorinated aquaculture seawater with TCCA and NaDDC,possibly due to the photodegradation of the important intermediate HBrO/HCl O and the newly formed Br-DBPs.On the contrary,Br-DBPs formed in chlorinated aquaculture seawater by ClO₂ increased under sunlight irradiation.The number of Br-DBPs formed during chlorination agreed well with the total organic bromine?TOBr?content,indicating that there had a good correlation between TOBr contents and Br-DBPs numbers.Most Br-DBPs were highly unsaturated and phenolic compounds,and generated through electrophilic substitution.After 24 h of disinfecting artificial aquiculture freshwater with povidone-iodine?PVP-I?and quaternary-N complex iodine?R4N-I?,333 and 290 I-DBPs were determined by FT-ICR MS,and the corresponding TOI content were 0.81 and 0.62?M,respectively.Most I-DBPs were phenolic and highly unsaturated compounds,and generated through electrophilic substitution reactions.Futhermore,a method was established for the identification and qualification of 9 polar aromatic Br-DBPs and I-DBPs by using ultra-performance liquid chromatography ionization-triple quadrupole mass spectrometry,and their concentrations in disinfected aquaculture water were analyzed.These aromatic compounds might be highly lipophilic and could potentially accumulate in marine organisms.Our findings call for further focus on the investigation of Br-DBPs and I-DBPs produced in disinfected aquaculture water.