DOI: 10.5061/dryad.5hqbzkhft
title: Bulk sediment geochemistry for seagrass meadows in three California estuaries

description: Seagrass meadows are a significant global carbon sink. Most of the carbon
 sequestered in these ecosystems is found as sedimentary organic carbon,
 which can vary spatially across seagrass meadows and can be derived from a
 variety of sources. Here, we investigate intra- and inter-meadow spatial
 variability in sediment organic carbon storage and quantify potential
 organic matter sources in three Zostera marina seagrass meadows spanning
 three estuaries across California (USA). Seagrass sediment organic carbon
 storage varies as much intra-meadow as it varies across regions. At the
 intra-meadow scale, we find significant correlations between organic
 carbon content and mud content (fraction of sediment grains
 &lt;63 μm, %), C/N ratios, and δ13C values in surface
 sediments across two meadows. At the regional scale greater organic carbon
 storage in the presence of seagrass compared to adjacent unvegetated
 sediments. Additionally, we find that mud content is the best predictor of
 sediment organic carbon content at the regional scale, indicating an
 enhanced role for mineral interaction in organic carbon preservation, but
 not consistently at the localized meadow scale. Approximately one-fourth
 of the organic carbon preserved in seagrass sediments is derived from
 seagrass. This research provides insights into the variability of organic
 carbon storage in seagrass meadows in California at multiple spatial
 scales. We demonstrate the need to account for small-scale variation of
 organic carbon storage in seagrass meadows to better estimate the capacity
 for these ecosystems to serve as effective long-term carbon sinks.
description: # Bulk sediment geochemistry for seagrass meadows in three California
 estuaries Dataset DOI: [10.5061/dryad.5hqbzkhft](10.5061/dryad.5hqbzkhft)
 ## Description of the data and file structure Sediment samples were
 collected between 2017 and 2019 as per the methods outlined in the
 published
 article: [https://doi.org/10.1029/2024JG008526.](https://doi.org/10.1029/2024JG008526) Sediment geochemistry provided in this data set was rinsed with distilled water, dried in an oven at 60-70 degrees Celsius, and homogenized before elemental and isotopic analysis and loss on ignition. This dataset includes geochemical data from a study of carbon storage in seagrass meadows from three California estuaries. #### File: 25_6_seagrass_geochem.xlsx **Parameters** All sediment samples are bulk rinsed samples. They have not been acidified to remove carbonates. Note: No data in row/column contains blank boxes. #### Variables **"sediment" Sheet Description:** Sheet with name "sediment" = sediment geochemical data  * core = core number and site location CG, Cypress Grove; BH, Bodega Harbor; NBB, Newport Back Bay  * sample_ID = core number, depth position (surface, intermediate, deep), and location site CG, Cypress Grove; BH, Bodega Harbor; NBB, Newport Back Bay  * site = CG, Cypress Grove; BH, Bodega Harbor; NBB, Newport Back Bay  - depth = depth bin, either S=surface, I=intermediate, D=deep * depth_bin = 2, 1,0, or 20 cm depth interval - V_UV = vegetation status, whether the sample is vegetated (V) or unvegetated (UV) * site_VUV = vegetation status and site - latitude = coordinate of sediment sample in degrees North * longitude = coordinate of sediment sample in degrees West - d13C = the raw total carbon isotope composition of the sediment sample * adjusted_d13C = adjusted organic carbon isotope value - DBD_gcm3 = dry bulk density of sediment sample * adjusted_Cmgcm3 = calculated organic carbon content in sediment sample in grams/centimeter^3 - raw_Corg = the raw percent (%) total carbon in sediment sample * adjusted_Corg = calculated percent (%) organic carbon in sediment sample - d15N = the raw total nitrogen isotope composition of the sediment sample * Cmol = mols of organic carbon  - Ntot = the raw percent (%) nitrogen in sediment sample * Nmol= mols of nitrogen - CNmol = the molar carbon to nitrogen ratio in sediment samples  * NCmol= the molar nitrogen to carbon ratio in sediment samples - TOM = the total organic matter (as a percent, %) in the sediment sample measured via loss on ignition * mud = the percent (%) mud in sediment samples measured via wet sieving through a 63 micron filter **"biomass" Sheet Description:** Sheet with name "biomass" = biomass geochemical data  * data_type = where data is sourced from, and the type of biomass - d13C = average carbon isotope composition in per mille * c13min = minimum carbon isotope composition in per mille - c13max = maximum carbon isotope composition in per mille * c13std = standard deviation of carbon isotope composition in per mille - CN = average molar carbon to nitrogen ratio * cnmin = minimum molar carbon to nitrogen ratio - cnmax = maximum molar carbon to nitrogen ratio * cnstd = standard deviation of the molar carbon to nitrogen ratio - n = number of samples ## Code/software Files are saved as .xlsx spreadsheets, which can be opened in Excel or other freely available software such as Google Sheets or LibreOffice.