Complexation of Copper Algicide and Cellular Organic Matter: Implications for Its Fate in Algae-Laden Surface Waters

Copper-basedalgicides have been widely used to suppresscyanobacterialbiomass. Constrained by the heterogeneous characteristics of cellularorganic matter (COM) in aquatic ecosystems, little information onthe Cu(II) binding of different COM subfractions has been obtained.In this study, the original COM solution was divided into four fractions,the hydrophobic (HPO), transphilic (TPI), charged hydrophilic (CHPI),and neutral hydrophilic (NHPI) fractions, via resin-mediated fractionation.A comprehensive methodology that integrates two-dimensional correlationspectroscopy (2DCoS), hetero-2DCoS, and moving-window 2DCoS analysiswas used to identify the binding sites and binding sequence of COMsubfractions in response to Cu(II) perturbation. The most sensitivegroups in the HPO, TPI, CHPI, and NHPI fractions were aryl & upsilon;(C-H), aliphatic & delta;(C-H), amide II & upsilon;(C-N), and polysaccharide & nu;(C-O), respectively. Each subfraction could interact with Cu(II) throughdiverse functional moieties, and carboxylic, aliphatic, aryl, andphenolic groups were the basic units of COM chromophores. The functionalgroups could coordinate with Cu(II) when it was present at both traceand high concentrations, but the abundance of functional groups variedsignificantly among COM subfractions and even chromophores. Thesefindings enhance our understanding of the molecular characteristicsof Cu(II) complexes and the environmental fates of metal-organiccomplexes in aquatic systems. Our findingshave implications for the prevention, control,and remediation of copper-based algicide in algae-laden surface waters.