Quantity and Quality of DOC within Agricultural Watersheds Using Absorbance and Fluorescence Spectroscopy.

Quantity and quality of DOC within agricultural watersheds using absorbance and fluorescence spectroscopy

Lili Lei

Abstract: An increasing trend of dissolved organic carbon (DOC) concentration has been reported in inland surface waters over large areas of the Northern Hemisphere and will continue to rise. The main source of DOC in aquatic ecosystems comes from degradation from soil organic carbon and leaching of DOC in terrestrial landscapes. Land use relating source and quantity of organic matter input into soil has been reported as the greatest influence factor on composition and concentration of DOC in soil solution. However, a lack of information on the lateral transport of DOC from different terrestrial sources to aquatic ecosystems. We conducted a study on fine-scale temporal and spatial characteristics of DOC in soil solution down to 40cm from forest, crop and pasture landscape and in adjacent head water stream. We found that optical properties of DOC in soil solution from different landscapes was significantly different and this difference leaded to different DOC concentration and composition in adjacent headwater stream. This is very helpful in optimizing management practices of different landscapes in terms of carbon management and essential to understand DOC transformations from soil solution across different landscapes.