Carbon cycling hysteresis in permeable carbonate sands over a diel cycle: Implications for ocean acidification
Dissolved inorganic carbon, dissolved oxygen, H + , and alkalinity fluxes from permeable carbonate sediments at Heron Island (Great Barrier Reef) were measured over one diel cycle using benthic chambers designed to induce advective pore‐water exchange. A complex hysteretic pattern between carbonate...
| Published in: | Limnology and Oceanography |
|---|---|
| Main Authors: | , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Wiley
2012
|
| Subjects: | |
| Online Access: | http://dx.doi.org/10.4319/lo.2013.58.1.0131 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.4319%2Flo.2013.58.1.0131 https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.2013.58.1.0131 |
| Summary: | Dissolved inorganic carbon, dissolved oxygen, H + , and alkalinity fluxes from permeable carbonate sediments at Heron Island (Great Barrier Reef) were measured over one diel cycle using benthic chambers designed to induce advective pore‐water exchange. A complex hysteretic pattern between carbonate precipitation and dissolution in sands and the aragonite saturation state (Ω Ar ) of the overlying chamber water was observed throughout the incubations. During the day, precipitation followed a hysteretic pattern based on the incidence of photosynthetically active radiation with lower precipitation rates in the morning than in the afternoon. The observed diel hysteresis seems to reflect a complex interaction between photosynthesis and respiration rather than Ω Ar of the overlying water as the main driver of carbonate precipitation and dissolution within these permeable sediments. Changes in flux rates over a diel cycle demonstrate the importance of taking into account the short‐term variability of benthic metabolism when calculating net daily flux rates. Based on one diel cycle, the sediments were a net daily source of alkalinity to the water column (5.13 to 8.84 mmol m −2 d −1 , depending on advection rates), and advection had a net stimulatory effect on carbonate dissolution. The enhanced alkalinity release associated with benthic metabolism and pore‐water advection may partially buffer shallow coral reef ecosystems against ocean acidification on a local scale. |
|---|