Cleaner air reveals growing influence of climate on dissolved organic carbon trends in northern headwaters. (21st September 2021)

• Record Type: Journal Article
• Authors: de Wit, Heleen A; Stoddard, John L; Monteith, Donald T; Sample, James E; Austnes, Kari; Couture, Suzanne; Fölster, Jens; Higgins, Scott N; Houle, Daniel; Hruška, Jakub; Krám, Pavel; Kopáček, Jiří; Paterson, Andrew M; Valinia, Salar; Van Dam, Herman; Vuorenmaa, Jussi; Evans, Chris D
• Is Part Of: Environmental research letters. Volume 16:Number 10(2021)
• Publication Date: 2021-09-21
• Subjects: sulfate deposition -- carbon cycle -- precipitation -- catchment DOC export -- surface water browning -- organic matter solubility; Environmental sciences -- Periodicals; Human ecology -- Research -- Periodicals; Environmental health -- Periodicals; 333.7
• DOI: 10.1088/1748-9326/ac2526
• Languages: English
• ISSNs: 1748-9326

Abstract

Abstract: Surface water browning, the result of increasing concentrations of dissolved organic matter (DOM), has been widespread in northern ecosystems in recent decades. Here, we assess a database of 426 undisturbed headwater lakes and streams in Europe and North America for evidence of trends in DOM between 1990 and 2016. We describe contrasting changes in DOM trends in Europe (decelerating) and North America (accelerating), which are consistent with organic matter solubility responses to declines in sulfate deposition. While earlier trends (1990–2004) were almost entirely related to changes in atmospheric chemistry, climatic and chemical drivers were equally important in explaining recent DOM trends (2002–2016). We estimate that riverine DOM export from northern ecosystems increased by 27% during the study period. Increased summer precipitation strengthened upward dissolved organic carbon trends while warming apparently damped browning. Our results suggest strong but changing influences of air quality and climate on the terrestrial carbon cycle, and on the magnitude of carbon export from land to water.