Data Management Plan

The water chemistry data described here are from discrete water samples collected by the NOAA Coral Reef Ecosystem Program (CREP) in 2013 and 2014 to assess the seawater carbonate systems primarily at fixed climate survey sites located in coral reef habitats in Timor-Leste. Climate sites were established by CREP to establish ecological baselines for climate change by measuring multiple features of the coral reef environment (in addition to the data described herein) over time. Water chemistry data for both 2013 and 2014 is only available for a subset of the established climate survey sites (5 of the 8 sites). In 2013, water samples were collected from a few random sites in addition to the samples collected at the climate survey sites.

SCUBA divers collected two discrete water samples from each site; one at the reef and one at the surface directly above the reef. In 2013 only, surface water samples were also collected ~1 km offshore from the survey site. The samples were processed by CREP and sent to NOAA Pacific Marine Environmental Laboratory (PMEL) to be analyzed for total alkalinity (TA) and dissolved inorganic carbon (DIC). From these constituents, alongside temperature, salinity, and depth data, other parameters of the seawater carbonate system were calculated, including pH, partial pressure of carbon dioxide, and aragonite saturation state.

The water chemistry data can be accessed online via the NOAA National Centers for Environmental Information (NCEI) Ocean Archive.

Extent of water chemistry data for Timor-Leste from water samples collected in 2013 and 2014.

Lineage Statement:
NOAA Coral Reef Ecosystem Program (CREP) assembles carbonate chemistry information from discrete seawater samples analyzed for two parameters: 1) Dissolved Inorganic Carbon (DIC), which in some literature is defined as Total Carbon (CT), and 2) Total Alkalinity (TA or AT). All carbonate system collection and measurement methodologies follow the protocols accepted by the greater scientific community and outlined in Dickson et al. (2007)

Process Steps:

• At each Climate Monitoring site, 1 discrete near reef seawater sample (recovered at ~15-m depth) and 1 surface seawater sample (recovered at ~1-m depth) were collected using 5-L Niskin bottles. In 2013, a third seawater sample was collected ~1-km offshore from each site (recovered at ~1-m depth). Each time a water sample was collected, it was divided into: (1) a 500-mL glass bottle and preserved with mercuric chloride (for dissolved inorganic carbon [DIC] and total alkalinity [TA] analysis) and (2) a 250-mL HDPE plastic bottle (for salinity analysis). During both 2013 and 2014 field efforts, 1 in 4 water sample collections were replicated to ensure analytical reproducibility. Discrete water samples are collected according to the protocol established by the NOAA Pacific Marine Environmental Laboratory (PMEL). (Citation: Inorganic Carbon Sampling: Planning and Sample Collection)
• In 2013, electronic measurements of temperature and pressure were taken at the location where each water sample was collected using a Seabird SBE-39 subsurface temperature recorder. In 2014, immediately upon returning to the dive boat, a conductivity-temperature-depth instrument was used to sample through the water column above the 15-m survey site using a SBE-19plus. (Citation: Dickson et al (2007), SOP 1: Water Sampling for the parameters of the oceanic carbon dioxide system)
• NOAA Pacific Marine Environmental Laboratory (PMEL) supports NOAA Coral Reef Ecosystem Program's (CREP’s) carbonate chemistry sampling through the laboratory analysis of dissolved inorganic carbon (DIC) and total alkalinity (TA), provision of the sample bottles and transport cases, and technical consultation. The source document contains the protocols that PMEL uses to analyze water samples for DIC (SOP 2) and TA (SOP 3b). (Citation: Dickson, A.G., Sabine, C.L. and Christian, J.R. (Eds.) 2007. Guide to best practices for ocean CO2 measurements. PICES Special Publication 3, 191 pp.)
• The Total Alkalinity (TA) analysis employs a two-stage, potentiometric, open-cell titration using coulometrically analyzed HCl. (Citation: Dickson et al (2007), SOP 3b: Determination of total alkalinity in sea water using an open-cell titration)

PMEL conducts quality assurance and quality control on their analyses; the precision and accuracy of DIC analyses are on the order of ± 0.05% and TA analyses are on the order of ± 0.1% in a laboratory setting.

Data quality flags are provided by NOAA Pacific Marine Environmental Laboratory (PMEL) and included in the dataset. These flags indicate if something went wrong with the analytical equipment or with the processing of the samples. PMEL uses the World Ocean Circulation Experiment (WOCE) data quality flag system, where '2's correspond to good values, '3's to questionable data, and '4's to bad data. Most water samples collected by the NOAA Coral Reef Ecosystem Program (CREP) and analyzed by PMEL in this dataset received a '2' data quality flag and the remainder were flagged as questionable ('3').

Data can be accessed online via the NOAA National Centers for Environmental Information (NCEI) Ocean Archive.

The data resides in an MS Access database, which is maintained and regularly backed up by PIFSC ITS.