Abstract:

We sampled 3 plots (0.25m x 0.25m) at each of four sites along a salinity gradient downstream of the Davis Pond Diversion in the Barataria estuarine system in June 2014. Net soil greenhouse gas (CO2, CH4, N2O) fluxes were quantified for each plot. Live and dead above-ground and below-ground biomass was quantified from each plot except at BT4 where areal extent and average height of Avicennia germinans stand was assessed and stem and pneumatophore density determined. Biogeochemical process rates (greenhouse gas production, nitrification potential, denitrification enzyme activity (DEA), iron reduction, phosphorus sorption) and microbial community abundances were determined and soil properties were characterized for surface (0-5cm) and subsurface (10-15cm) soils at each plot. Additionally, porewater salinity and dissolved inorganic nutrient concentrations were measured.

Suggested Citation:

Roberts, Brian. 2016. Spatial patterns in soil biogeochemical process rates along a Louisiana wetland salinity gradient in the Barataria Bay estuarine system, June 2014. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7TB14VJ

Purpose:

This dataset was developed as part of a research project investigating the effects of the Deepwater Horizon oil spill on salt marsh biogeochemistry. This component of the CWC research effort focused on examining temporal and spatial patterns in salt marsh soil N cycling rates and whether these rates demonstrated impacts from the Deepwater Horizon oil spill 4 years post-spill.

Data Parameters and Units:

ID--sample identifier including site, plot, and depth Site--site identifier Latitude (decimal degrees) Longitude (decimal degrees) Plot--indicates which plot sample was collected from Depth--indicates whether the sample is from the surface (S = 0-5 cm) or at depth (D = 10-15 cm) above canopy air temp (°C)--air temperature taken above plant canopy (reported for plot 1, depth S but applies to site) below canopy air temp (°C)--air temperature taken within plant canopy (reported for plot 1, depth S but applies to site) barometric pressure (mm Hg)--barometric pressure at the site (reported for plot 1, depth S but applies to site) Vegetation--indicates which vegetation species were present in the plot (1-10, with key below = rows 29-38 of columns J&K) Live above-ground biomass (g m-2)--total above ground live plant biomass in the plot (could not be assessed for A. germinans) Live stem density (/m2)--density of live stems within the plot Dead above-ground biomass (g m-2)--total above ground dead stems within the plot (could not be assessed for A. germinans) Dead stem density (/m2)--density of dead stems within the plot pneumatophore density (/m2)--density of pneumatophores within the A. germinans plots below-ground biomass: 0-10cm (g m-2)--total plant biomass in top 10cm of the soil below-ground biomass: 10-20cm (g m-2)--total plant biomass within the 10-20cm deep layer of the soil below-ground biomass: 20-30cm (g m-2)--total plant biomass within the 20-30cm deep layer of the soil water temperature (°C)--temperature of the baywater adjacent to the site salinity (psu)-salinity of the baywater adjacent to the site Pore Water Salinity (psu)--salinity of porewater from the plot NO3 + NO2 (micromol L-1)--nitrate + nitrite concentration of porewater from the plot Overlying water (cm)--depth of overlying water at the plot when samples were collected Soil T (°C)--soil temperature at the plot soil redox (Eh)--soil redox potential in the surface soil of the plot pH--pH of a 5 cm depth interval (0-5 cm for S and 10-15cm for D) of the plot Bulk Density (g cm-3)-bulk density of a 5 cm depth interval (0-5 cm for S and 10-15cm for D) of the plot Water Content (%)--gravimetric water content of a 5 cm depth interval (0-5 cm for S and 10-15cm for D) of the plot OM (%)--organic matter content of a 5 cm depth interval (0-5 cm for S and 10-15cm for D) of the plot organic C (%)--organic carbon content of a 5 cm depth interval (0-5 cm for S and 10-15cm for D) of the plot total N (%)--total nitrogen content of a 5 cm depth interval (0-5 cm for S and 10-15cm for D) of the plot total P (micrograms per gram dry weight of soil)--total phosphorus content of a 5 cm depth interval (0-5 cm for S and 10-15cm for D) of the plot NO3-N (micromol N gdw-1)--extractable nitrate concentration of a 5 cm depth interval (0-5 cm for S and 10-15cm for D) of the plot NH4-N (micromol N gdw-1)--extractable ammonium concentration of a 5 cm depth interval (0-5 cm for S and 10-15cm for D) of the plot PO4 (Bicarbonate) (micromol P gdw-1)--bicarbonate extractable phosphate concentration of a 5 cm depth interval (0-5 cm for S and 10-15cm for D) of the plot Fe (micromol Fe gdw-1)--total extractable iron concentration of a 5 cm depth interval (0-5 cm for S and 10-15cm for D) of the plot Al (micromol Al gdw-1)--total extractable aluminum concentration of a 5 cm depth interval (0-5 cm for S and 10-15cm for D) of the plot POX (micromol P gdw-1)--oxalate extractable phosphorus concentration of a 5 cm depth interval (0-5 cm for S and 10-15cm for D) of the plot Reduced Iron (micromol Fe2+ gdw-1)--reduced iron concentration of a 5 cm depth interval (0-5 cm for S and 10-15cm for D) of the plot CO2 (micromol m-2 h-1)--net CO2 flux from soil (in situ field fluxes) CH4 (micromol m-2 h-1)--net CH4 flux from soil (in situ field fluxes) N2O (micromol m-2 h-1)--net N2O fluxe from soil (in situ field fluxes) CO2 production (nmol gdw-1 d-1)--CO2 production rate (soil slurry measurement) of a 5 cm depth interval (0-5 cm for S and 10-15cm for D) of the plot CH4 production (nmol gdw-1 d-1)--CH4 production rate (soil slurry measurement) of a 5 cm depth interval (0-5 cm for S and 10-15cm for D) of the plot N2O production (nmol gdw-1 d-1)--N2O production rate (soil slurry measurement) of a 5 cm depth interval (0-5 cm for S and 10-15cm for D) of the plot potential denitrification (DEA) (nmol N2O gdw-1 h-1)--rate of potential denitrification generated from DEA slurries of a 5 cm depth interval (0-5 cm for S and 10-15cm for D) of the plot Iron reduction (mg Fe2+ gdw-1 d-1)--rate of microbial iron reduction of a 5 cm depth interval (0-5 cm for S and 10-15cm for D) of the plot Nitrification (nmol NO3-N gdw-1 d-1)--rate of potential nitrification of a 5 cm depth interval (0-5 cm for S and 10-15cm for D) of the plot Phosphorus sorption (PSI) (mg P kg dry soil-1)--phosphorus sorption index (PSI) of a 5 cm depth interval (0-5 cm for S and 10-15cm for D) of the plot

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