Nutrient concentrations and stable isotope values for groundwater in nearshore shelf waters off Charleston, SC from June 2018 to August 2019

Website: https://www.bco-dmo.org/dataset/892997
Data Type: Other Field Results
Version: 1
Version Date: 2023-04-03

Project
» Groundwater sources of "new" N for benthic microalgal production in the South Atlantic bight (SAB BMA)
ContributorsAffiliationRole
Pinckney, James L.University of South CarolinaPrincipal Investigator, Contact
Heyl, TaylorWoods Hole Oceanographic Institution (WHOI BCO-DMO)BCO-DMO Data Manager

Abstract
Nutrient concentrations and stable isotope values for groundwater were measured on selected dates from 7 June 2018 to 10 August 2019 in nearshore shelf waters off Charleston, SC. The survey area was located in the region of 32° 42’ N, 79° 50’ W and 32° 51’ N, 79° 09’ W. Sediment core samples were analyzed by HPLC. These data were used to map nutrient concentrations and assess inputs of groundwater effects on benthic microalgae. Results may be of interest to others conducting research projects off Charleston, SC. Data were collected and interpreted by Jay Pinckney at the University of South Carolina, Columbia, SC.


Coverage

Spatial Extent: N:32.7671 E:-79.6151 S:32.7069 W:-79.6632
Temporal Extent: 2018-06-07 - 2019-08-06

Methods & Sampling

Nutrient concentrations and stable isotope values for groundwater were measured on selected dates from 7 June 2018 to 10 August 2019 in nearshore shelf waters off Charleston, SC (32° 42’ N, 79° 50’ W and 32° 51’ N, 79° 09’ W). At each of the groundwater wells in the wellfield, divers collected fluids from the wells to determine well water inorganic nutrient concentrations (nitrate + nitrite, ammonium, orthophosphate) and the δ15N of well water DON, ammonium, and nitrate (when present). Sediment core samples were analyzed by HPLC. These data were used to map nutrient concentrations and assess inputs of groundwater effects on benthic microalgae.

δ15N of Nitrate: Filtered (0.2 micrometer) samples were stored in acid-washed HDPE bottles and frozen (-20 degrees Celsius) until analysis. For any sample with more than 0.5 μM NO3-, the isotopic composition of NO3- was determined by the denitrifier method of Sigman et al. (2001) and Casciotti et al. (2002), with updates according to McIlvin & Casciotti (2011) and Weigand et al. (2016).

δ15N of Ammonium: Filtered (0.2 μm) samples will be stored on dry ice in the field and shipped immediately to the lab for δ15N of ammonium analysis. Samples with more than 3 µM NH4+ and adequate sample volume were analyzed using the hypobromite/azide method of Zhang et al. (2007).


Data Processing Description

BCO-DMO Processing Description:
- Missing data identifier ‘-9999’ replaced with blank (BCO-DMO's default missing data identifier)
- Converted Longitude values from West to East to comply with BCO-DMO standards
 


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Data Files

File
nutrient_and_stable_isotope_data-1.csv
(Comma Separated Values (.csv), 1.27 KB)
MD5:b020ec17d5e1d300642e051e4dff00bb
Primary data file for dataset 892997_Version 1.

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Related Publications

Casciotti, K. L., Sigman, D. M., Hastings, M. G., Böhlke, J. K., & Hilkert, A. (2002). Measurement of the Oxygen Isotopic Composition of Nitrate in Seawater and Freshwater Using the Denitrifier Method. Analytical Chemistry, 74(19), 4905–4912. doi:10.1021/ac020113w
Methods
Kofoid, & Campbell, A. S. (1929). A conspectus of the marine and fresh?water Ciliata belonging to the suborder Tintinnoinea, with descriptions of new species principally from the Agassiz Expedition to the eastern tropical Pacific 1904?1905. Univ. Calif. Publs Zool., 34, 1–403.
Methods
McIlvin, M. R., & Casciotti, K. L. (2011). Technical Updates to the Bacterial Method for Nitrate Isotopic Analyses. Analytical Chemistry, 83(5), 1850–1856. doi:10.1021/ac1028984
Methods
Pinckney, J. L., Zaunbrecher, S., Lang, S., Wilson, A., & Knapp, A. (2022). Seasonality of benthic microalgal community abundance in shallow shelf waters. Continental Shelf Research, 244, 104797. https://doi.org/10.1016/j.csr.2022.104797
Results
Sigman, D. M., Casciotti, K. L., Andreani, M., Barford, C., Galanter, M., & Böhlke, J. K. (2001). A Bacterial Method for the Nitrogen Isotopic Analysis of Nitrate in Seawater and Freshwater. Analytical Chemistry, 73(17), 4145–4153. doi:10.1021/ac010088e
Methods
Weigand, M. A., Foriel, J., Barnett, B., Oleynik, S., & Sigman, D. M. (2016). Updates to instrumentation and protocols for isotopic analysis of nitrate by the denitrifier method. Rapid Communications in Mass Spectrometry, 30(12), 1365–1383. doi:10.1002/rcm.7570
Methods
Zhang, L., Altabet, M. A., Wu, T., & Hadas, O. (2007). Sensitive Measurement of NH4+15N/14N (δ15NH4+) at Natural Abundance Levels in Fresh and Saltwaters. Analytical Chemistry, 79(14), 5297–5303. doi:10.1021/ac070106d
Methods

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Related Datasets

IsRelatedTo
Pinckney, J. L. (2023) Benthic microalgal photopigment concentrations from nearshore shelf waters off Charleston, SC from June 2018 to August 2021. Biological and Chemical Oceanography Data Management Office (BCO-DMO). (Version 1) Version Date 2023-04-10 doi:10.26008/1912/bco-dmo.892576.1 [view at BCO-DMO]

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Parameters

ParameterDescriptionUnits
LocationSample location identifier unitless
Cruise_numberCruise identifier unitless
LatitudeLatitude of sampling site North (South is negative) decimal degrees
LongitudeLongitude of sampling site East (West is negative) decimal degrees
DateDate of collection unitless
DepthWater depth meters (m)
d15N_bulk_sedimentsd15N for bulk sediments unitless
d15N_water_filtersd15N for particulate organic matter in the water column unitless
TDN_well_waterTotal dissolved nitrogen for groundwater micromolar
d15N_TDN_well_waterd15N for total dissolved nitrogen for groundwater unitless
DON_well_waterTotal dissolved organic nitrogen for groundwater micromolar
NH4_well_waterTotal dissolved ammonium for groundwater micromolar
NO3_NO2_well_waterTotal dissolved nitrate and nitrite for groundwater micromolar
PO4_well_waterTotal dissolved orthophosphate for groundwater micromolar


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Instruments

Dataset-specific Instrument Name
Turner Trilogy fluorometer
Generic Instrument Name
Fluorometer
Generic Instrument Description
A fluorometer or fluorimeter is a device used to measure parameters of fluorescence: its intensity and wavelength distribution of emission spectrum after excitation by a certain spectrum of light. The instrument is designed to measure the amount of stimulated electromagnetic radiation produced by pulses of electromagnetic radiation emitted into a water sample or in situ.

Dataset-specific Instrument Name
Shimadzu UV-1800 uv-vis spectrophotometer
Generic Instrument Name
UV Spectrophotometer-Shimadzu
Generic Instrument Description
The Shimadzu UV Spectrophotometer is manufactured by Shimadzu Scientific Instruments (ssi.shimadzu.com). Shimadzu manufacturers several models of spectrophotometer; refer to dataset for make/model information.

Dataset-specific Instrument Name
Thermo Finnigan DeltamV isotope ratio mass spectrometer
Generic Instrument Name
Mass Spectrometer
Generic Instrument Description
General term for instruments used to measure the mass-to-charge ratio of ions; generally used to find the composition of a sample by generating a mass spectrum representing the masses of sample components.

Dataset-specific Instrument Name
Generic Instrument Name
Self-Contained Underwater Breathing Apparatus
Generic Instrument Description
The self-contained underwater breathing apparatus or scuba diving system is the result of technological developments and innovations that began almost 300 years ago. Scuba diving is the most extensively used system for breathing underwater by recreational divers throughout the world and in various forms is also widely used to perform underwater work for military, scientific, and commercial purposes. Reference: http://oceanexplorer.noaa.gov/technology/diving/diving.html


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Project Information

Groundwater sources of "new" N for benthic microalgal production in the South Atlantic bight (SAB BMA)

Coverage: South Atlantic Bight (32 N, 79 W)


NSF Award Abstract:
Continental shelves are highly productive, with both ecological and economic importance. Benthic microalgae (BMA) are key primary producers in these location. As much as 6x the water column biomass of primary producers is compressed into a layer only a few mm thick on the sediment surface. The source(s) of fixed nitrogen (N) supporting such highly concentrated BMA biomass is currently unknown. Recent studies of sub-seafloor groundwater flow at the University of South Carolina have demonstrated that upwelling saline groundwater likely supplies high concentrations of nutrients in the ridge-swale habitats in the South Atlantic Bight (SAB). The investigators suggest that groundwater input of fixed N into surficial sediments is the primary source of N supporting BMA biomass and production in the mid-shelf region of the SAB. The purpose of this project is to determine the primary source of fixed N supporting BMA biomass in the surface sediments of the shallow shelf waters (<30 m), using the SAB as a field area. A secondary objective is to apply novel and innovative methods to directly quantify groundwater inputs of N into surficial sediments. Research results will fully document the spatio-temporal distributions of BMA and phytoplankton biomass and community structure in the mid-shelf region of the SAB and relate the observed patterns to groundwater inputs of fixed N sources as well as hydrographic and climatic conditions. This research will provide full support and tuition for 2 graduate students, summer support for undergraduate assistants, and involve upper level undergraduates as lab interns. The study team will also work with the Baruch Institute and other partners to develop an "Ocean Schoolyard" program to meet the needs of teachers, students, and community audiences. The project will also provide partial support for Girls Go for I.T., a coding summer camp designed to attract middle-school-aged girls to careers in I.T. and STEM fields.

The specific objectives of the study are to (1) quantify spatial and temporal variations in N fluxes associated with hydrodynamic exchange and upward groundwater flow (2) document spatial and temporal variations in BMA biomass and (3) measure the delta15N of fixed nitrogen sources (well water, porewater and water column ammonium and nitrate; sediments), the BMA, and phytoplankton. The sampling area will be restricted to the 10 - 30 m isobath region of the SAB off the coast of Charleston, SC. Samples will be collected at both the existing groundwater well field and other regions of the shelf. At each of the groundwater wells in the well field, SCUBA divers will collect fluids from the wells to determine well water inorganic nutrient concentrations (nitrate + nitrite, ammonium, orthophosphate, silicon) and the delta 15N of well water ammonium and nitrate (when present). In nearby sediments, samples will be collected for BMA biomass and community composition, surface porewater inorganic nutrients (nitrate + nitrite, ammonium, orthophosphate, silicon), C and N of sediments, sediment grain size analysis, and delta 15N of BMA, ammonium, nitrate (when present), and sediments. Line transects, consisting of 5 sampling locations along a 50 m transect, will be conducted in each of the 4 depth strata. At 10 m intervals along each transect, divers will collect samples the same as above for the well field. Water column samples will be collected for HPLC measurements of phytoplankton biomass and community composition, inorganic nutrient concentrations (nitrate + nitrite, ammonium, orthophosphate, silicon), seston CHN, delta 15N of phytoplankton, and the delta 15N of ammonium and nitrate. The researchers will use heat as a tracer to map the depth of hydrodynamic exchange and monitor the rate of vertical groundwater flow. Results from that analysis will also allow them to then simulate transport of a conservative tracer that can be compared to observed nutrient concentrations to BMA abundance and community composition.



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Funding

Funding SourceAward
NSF Division of Ocean Sciences (NSF OCE)

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