The relationship between dissolved organic carbon quality and land use in three rivers flowing into the Kesennuma Bay.

Abstract

To elucidate the factors controlling dissolved organic carbon (DOC) dynamics in river systems, we investigated DOC concentrations and fluorescence emission-excitation matrix characteristics in three rivers draining into the Kesennuma and Moune Bays from 2012 to 2014. DOC concentrations and the relative fluorescence intensity of fulvic-acid-like substances (F) increased with agricultural areas. The relative fluorescence intensity of protein-like substances (P) and the ratio of P to F had a significant correlation with urban areas. In Moune river where small salt marsh were created after the Great East Japan Earthquake and following tsunami at the estuary, DOC concentrations and values of F and P increased significantly. These results indicate that anthropogenic landuse (agriculture and urban areas) and newly-created salt marsh can control DOC concentrations and fluorescence characteristics in the river basins.