Land-sea carbon and nutrient fluxes and coastal ocean CO 2 exchange and acidification: Past, present, and future

Fred T. Mackenzie*, Andreas J. Andersson, Rolf S. Arvidson, Michael W. Guidry, Abraham Lerman

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Epochs of changing atmospheric CO 2 and seawater CO 2 -carbonic acid system chemistry and acidification have occurred during the Phanerozoic at various time scales. On the longer geologic time scale, as sea level rose and fell and continental free board decreased and increased, respectively, the riverine fluxes of Ca, Mg, DIC, and total alkalinity to the coastal ocean varied and helped regulate the C chemistry of seawater, but nevertheless there were major epochs of ocean acidification (OA). On the shorter glacial-interglacial time scale from the Last Glacial Maximum (LGM) to late preindustrial time, riverine fluxes of DIC, total alkalinity, and N and P nutrients increased and along with rising sea level, atmospheric PCO 2 and temperature led, among other changes, to a slightly deceasing pH of coastal and open ocean waters, and to increasing net ecosystem calcification and decreasing net heterotrophy in coastal ocean waters. From late preindustrial time to the present and projected into the 21st century, human activities, such as fossil fuel and land-use emissions of CO 2 to the atmosphere, increasing application of N and P nutrient subsidies and combustion N to the landscape, and sewage discharges of C, N, P have led, and will continue to lead, to significant modifications of coastal ocean waters. The changes include a rapid decline in pH and carbonate saturation state (modern problem of ocean acidification), a shift toward dissolution of carbonate substrates exceeding production, potentially leading to the " demise" of the coral reefs, reversal of the direction of the sea-to-air flux of CO 2 and enhanced biological production and burial of organic C, a small sink of anthropogenic CO 2 , accompanied by a continuous trend toward increasing autotrophy in coastal waters.

Original languageEnglish (US)
JournalApplied Geochemistry
Volume26
Issue numberSUPPL.
DOIs
StatePublished - Jun 1 2011

ASJC Scopus subject areas

  • Environmental Chemistry
  • Pollution
  • Geochemistry and Petrology

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