Effect of landscape control on the spatiotemporal variability of riverine chromophoric dissolved organic matter

Abstract

An increase in the release of sewage discharge and stream ecosystem degradation is contributing to increased chromophoric dissolved organic matter (CDOM) in the Yinma River Watershed, which is a polluted watershed of the Songhua River. This study involves the spatiotemporal characterization of CDOM, CDOM-DOC relationships, and the influence of environmental factors (e.g., natural geographical and anthropogenic activities). Riverine waters showed higher aCDOM (335) and DOC concentrations in the spring and autumn than in the summer, and positive correlations were found between the aCDOM (335) and DOC concentrations in the summer (r = 0.90, 2-tailed, p<0.01) and autumn (r = 0.58, 2-tailed, p<0.01). Storms in May 2016 affected DOC flux from terrestrial ecosystems into the stream, and the CDOM-DOC relationship in the spring. Environmental factors such as water quality, precipitation, soil, gradient, land-use, and GDP could have affected the optical properties of CDOM (DOC). Gradient was correlated with the optical properties (2-tailed, p<0.05) of CDOM. Types of land-use, pollutant discharge from point sources, and GDP (r = 0.58, 2-tailed, p<0.05) affected the composition and creation of CDOM (DOC). The correlations among CDOM absorption parameters, gradient, and GDP were driven by samples that were related to regional terrestrial and anthropogenic pollutants. High loading of complex CDOM (DOC) inputs from anthropogenic activities combine with natural influences and constitute a challenge for CDOM (DOC)-derived pollution treatment, and treatment of pollution in the watershed.