Application of a new combined fractionation technique (CFT) to detect fluorophores in size-fractionated hydrophobic acid of DOM as indicators of urban pollution

For pollution monitoring, we developed a new combined fractionation technique (CFT) to characterize dissolved organic matter (DOM) in natural water by combining resin adsorption (RA) and ultrafiltration (UF) with 3D-fluorescence measurement. We tested the new technique on 4 polluted and 4 unpolluted samples. The 3D-fluorescence characteristics of size sub-components in the hydrophobic acid (HPOA) fraction could distinguish unpolluted from polluted DOM. The unpolluted HPOA fraction was composed of a single dominant size component—peak A (fulvic-like, around Ex240/Em410nm) material with relatively large molecular weight (MW) (>10kDa). In comparison, the HPOA in polluted DOM contained another predominant size component with lower MW (