Characterizing Dissolved Organic Matter from Cattle Slurry in Kushiro River Water Using EEM-PARAFAC

Abstract

We applied excitation emission matrix-parallel factor analysis (EEM-PARAFAC) technique to ascertain the fluorophore group indicating fecal pollution from the complex nature of dissolved organic matter (DOM) in surface water of Kushiro River Basin. Covariation between relative concentrations of identified fluorophore groups and specific steroid profiles were analyzed to produce an alternate classical steroid indicator of fecal pollution by the identified fluorophore group. The fluorophore, showing fluorescent characteristics similar to those of the indole ring structure of tryptophan, was found from cattle slurry. The maximum fluorescence intensities (F_max) of the fluorophore showed seasonal and spatial distribution similar to that of coprostanol (5β), which is known as indicator of fecal pollution. The fluorophore was widely detected in surface water of Kushiro River Basin collected from autumn through the following spring, after application of cattle slurry to pastureland. In this case, F_max of the fluorophore showed good correlation with 5β, while during fall through spring, it is useful similar to 5β. Composition of 5β in fecal sterols is specific to the type of domestic animal. Correlation between 5β and F_max of the fluorophore holds only in a basin that has the DOM sources of breeding beef and dairy cattle such as Kushiro River Basin.