Dry and wet weather carbon exports from an urban stream impacted by anthropogenic contamination
Abstract
Declining water quality and exports of organic carbon and pathogenic microorganisms from urban streams to coastal areas have important implications for human and ecosystem health. Composition of dissolved organic matter (DOM) in urban waterways is of particular interest due to the influential role of DOM in the biological functioning of aquatic ecosystems and critical biogeochemical processes underway in coastal environments. Here we focus on characterizing changes in DOM optical properties in an urban stream in San Diego, CA, USA, which was studied during dry weather conditions and during three storm events in 2016 and 2017. Optical spectroscopic properties, including specific ultraviolet absorbance (SUVA), fluorescence index (FI), and parallel factor analysis (PARAFAC) model components, as well as concentrations of dissolved organic carbon (DOC) were used to characterize DOM sources and export. Chloride/bromide ratios reflect a distinct shift from groundwater-fed baseflow to rainwater-fed runoff and interflow. During dry weather, DOM was characterized by higher fluorescence index values, indicating that microbial sources, such as algae or bacteria, dominated the DOM pool. Changes in SUVA and FI values during the storm hydrograph indicated a shift to more terrestrially-derived and aromatic carbon sources, most likely derived from interflow through soil porewaters. On an annual basis, export of DOM of primarily microbial origin during dry weather was several times higher than the export of DOM of primarily terrestrial origin during storm events; both represent important carbon inputs to coastal waters.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMH032.0004M
- Keywords:
-
- 0478 Pollution: urban;
- regional and global;
- BIOGEOSCIENCES;
- 0481 Restoration;
- BIOGEOSCIENCES;
- 0496 Water quality;
- BIOGEOSCIENCES;
- 1879 Watershed;
- HYDROLOGY