Long-term trends in dissolved organic matter from fluvial systems across biomes
Abstract
Dissolved organic carbon (DOC) concentrations have increased in many streams and rivers draining temperate watersheds in Europe and North America. Less is known however about changes in other biomes and if changes in dissolved organic nitrogen (DON) track those of DOC. Here we present long-term DOC and DON trends from multiple streams across biomes ranging from the tropics to northern boreal forests and arctic. For each individual stream within a given site, we obtained sen slopes for DOC and DON time series and related these slopes to stream physico-chemical parameters, stream physical properties, climatic descriptors, and stream chemistry to determine global and regional drivers. Sen slopes varied in direction and magnitude across sites and streams, from -0.25 mg/L/year to 0.25 mg/L/year for DOC and -0.005 mg/L/year to 0.013 mg/L/year for DON. Changes in DOC concentrations were greater than DON across all sites. Some sites displayed consistent positive or negative responses across streams, while other sites displayed variable responses. We did not identify any consistent global driver of DOC or DON trends but found that drivers differed among biomes. Drivers identified included PO4, Si, Cl, and Mg concentrations, specific conductance, pH, and elevation. Results suggest that there is no consistent pattern of change in DOC or DON concentrations at the global scale, but that site-specific and regional patterns exist in the occurrence and magnitude of DOC trends. Because increasing or decreasing trends in DOM can have major implications for stream metabolism, food webs, and drinking water quality, understanding the extent of global changes in DOC and DON concentrations is an important topic for further investigation.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.H42A..06R
- Keywords:
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- 1804 Catchment;
- HYDROLOGY;
- 1806 Chemistry of fresh water;
- HYDROLOGY;
- 1848 Monitoring networks;
- HYDROLOGY;
- 1895 Instruments and techniques: monitoring;
- HYDROLOGY