Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • BCO-DMO Processing Description
• Data Files
• Related Publications
• Parameters
• Instruments
• Project Information
• Funding

Fish carbonate samples were collected from Eleuthera, The Bahamas, in 2009, 2010, 2011, and 2014, and Lizard Island, Great Barrier Reef, QLD, Australia in 2016. For more information regarding sample collection and processing, see the associated references (Salter et al., 2017; Salter et al., 2019; Salter et al., 2018; Salter et al., 2014; Salter et al., 2012).

Wild fish were collected from the local nearshore environments and housed in aquaria supplied with seawater filtered to 1 micrometer (µm) and maintained close to local ambient conditions (temperature = 24 to 32 degrees Celsius (°C); salinity = 35 to 37; pH (NBS) = 8.09 to 8.18). Food was withheld from fish during the sampling periods, and for 48 hours prior to allow the gastrointestinal tract to be completely emptied of dietary items and faeces. Excreted carbonates were collected at 24-hour intervals using a plastic Pasteur pipette and were immediately rinsed for a few minutes with distilled water before being immersed in sodium hypochlorite (<5 % w/v) for at least 6 hours to remove organic matter. Samples were then rinsed several times with distilled water before being transferred to 0.45 µm filters and dried at 50 °C. Samples collected in The Bahamas and Australia were primarily obtained from fish that had only ever consumed a mixed diet prior to their collection. However, several individuals of three species sampled in The Bahamas in 2011 (Lutjanus apodus, Albula vulpes, and Sphoeroides testudineus) were provided a diet of sardines (Sardinella aurita; Cap'n Salty, Raffield Fisheries Inc., Port St. Joe, FL; sourced from the Gulf of Mexico) for at least two weeks prior to carbonates being collected as normal (i.e., fish at fasting state).

- Imported original file "End members metadata.xlsx" into the BCO-DMO system.
- Flagged "N/A" and "Not measured" as missing data identifiers (missing data are blank/empty in the final CSV file).
- Made south latitude values negative.
- Made west longitude values negative.
- Changed format of dates from %m/%d/%Y to %Y-%m-%d.
- Renamed fields to comply with BCO-DMO naming conventions.
- Saved the final file as "960257_v1_end_members_metadata.csv".

NSF Award Abstract:
OCE-PRF Towards Quantifying Calcium Carbonate Sediment Dissolution During Marine Diagenesis The goal of the project is to investigate dissolution of calcium carbonate (CaCO3) in sediments below the seafloor and determine its importance to the chemistry of seawater. This project uses sediment samples and chemical data collected from different parts of the ocean during the past five decades by scientific ocean drilling programs. Sediment dissolution of carbonate can lessen the impact of ocean acidification, the process that causes the pH of the ocean to decrease due to the uptake of carbon dioxide (CO2) from the atmosphere. Ocean acidification threatens the survival of marine organisms, such as oysters, clams, and coral reefs, which could alter marine food chains and food supply to humans. By improving understanding of carbonate dissolution in the ocean, results from this project will enable better predictions of the effects of ocean acidification on marine organisms. This will advance the progress of science and contribute to the knowledge that can inform public policy. In addition, understanding carbonate sediment dissolution serves other important purposes. For example, dissolution can create small spaces between sediments that may get filled with groundwater once sediments convert to rocks over millions of years. Thus, understanding the occurrence and spatial distribution of spaces within rocks may help determine the volume and movement of groundwater in subsurface aquifers. This project provides support for a postdoctoral research fellow and research training opportunities for students through the Summer Student Fellowship and Woods Hole-wide Partnership Education Programs at the Woods Hole Oceanographic Institution.

Carbonate mineral dissolution is an integral part of the alkalinity and carbon cycles in the ocean and is expected to play an increasingly significant role in mediating changes in ocean chemistry as atmospheric CO2 continues to rise. The goal of this project is to provide thermodynamic constraints necessary for quantifying carbonate sediment dissolution in marine diagenetic environments. Specifically, the CaCO3 saturation state of pore fluids will be calculated in 365 globally distributed sites from previous scientific ocean drilling expeditions using a specially developed Pitzer ion activity model which is particularly useful for calculating activity coefficients in high ionic strength solutions such as those that characterize most diagenetic environments. These calculations will be substantiated with geochemical and textural analyses of sediment samples from four representative sites to identify the specific diagenetic processes (e.g., dissolution, precipitation, and recrystallization) and document the conditions responsible for their occurrence and prevalence. The immediate advantage of calculating the saturation state of pore fluids is that such data can be used to estimate carbonate sediment dissolution below the seafloor and quantify its contribution to the alkalinity and carbon cycles, which will lead to more accurate predictions of the consequences of ocean acidification. Another benefit of the global saturation state dataset is that it will improve our understanding of authigenic carbonate precipitation and its link to the carbon cycle over Earth history, which has been proposed as a significant sink for carbon. Furthermore, by complementing the thermodynamic calculations with textural and geochemical analyses, this project will parse out various diagenetic processes and identify the sedimentological and geochemical conditions responsible for their occurrence. Such knowledge is crucial for evaluating the impact of diagenesis on the carbonate-hosted paleoenvironmental proxies. Collectively, this project will pave the way towards a mechanistic understanding of carbonate diagenesis. This will provide important constraints on the oceanic alkalinity cycle, carbon burial rates, and geochemical proxies, which ultimately help us better understand the future of our ocean system in the context of climate change.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.