Abstract:

This study contains chemical composition data of Mississippi Sound surface seawater and groundwater samples collected along the coastline, from 2017-07-28 to 2019-11-13. Samples were collected of groundwater tracers as well as nutrients and trace elements along the coastline of the Mississippi Sound at five stations over three years (2017-2019). Surface water grab samples and groundwater PushPoint samples were collected along the coastline.

Suggested Citation:

Shiller, Alan M., Amy Moody, and Melissa Gilbert. 2023. Chemical composition data of Mississippi Sound surface seawater and groundwater samples collected along the coastline, from 2017-07-28 to 2019-11-13. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/9yxdwch4

Purpose:

Sampling was started to determine if submarine groundwater discharge played a role in localized fish kills along the coastline, and was expanded to understand the impact of the Bonnet Carré Spillway, local rivers, and submarine groundwater discharge on nutrient dynamics and oxygen depletion along the coast.

Data Parameters and Units:

Site, Type, Sample ID, Radium ID, Date [mm/dd/yyyy], Time [hh:mm], Latitude [decimal degrees], Longitude [decimal degrees], Temperature [C], Salinity [ppt], Oxygen Surface [µmol/L], Oxygen Saturation [%], Oxygen Bottom [µmol/L], Oxygen Bottom Saturation [%], Depth [m], CH4 [nmol/L], NO3 + NO2 [µmol/L], NH4+ [µmol/L], PO4 [µmol/L], SiO3 [µmol/L], DON [µmol/L], DOP [µmol/L], Ba [nmol/L], Cs [nmol/L], Mo [nmol/L], Ra228 [dpm/100L], Ra226 [dpm/100L], Ra224 [dpm/100L], Ra223 [dpm/100L], 222Rn [dpm/L], δ18O(water) [‰ VSMOW], δD(water) [‰ VSMOW]

Methods:

Nutrients like phosphate, ammonia and silicates were analyzed using a Seal AA3 Autoanalyzer. Methane was analyzed using laser cavity ring-down spectroscopy (CRDS) in an equilibrated headspace Further details are provided Roberts and Shiller, 2015. Dissolved radium (223 Ra and 234Ra) analysis was performed by first adsorbing radium onto MnO2 coated fibers, and then passing the decay products of radium which do not adsorb onto MnO2 through a scintillation detector. A delayed coincidence circuit is used to distinguish between the decay products of 223 Ra and 234Ra. Further details are provided in Moore and Arnold, 1996. Dissolved Ba was determined according to Joung and Shiller, 2013 which used a high resolution inductively coupled plasma mass spectrometer (HR-ICP-MS, ThermoFisher Element 2) using an isotope dilution method. ICP-MS was also used to analyze samples for molybdenum and cesium (Shim et al., 2012). Radon was determined with the use of RAD7 Radon detector manufactured by Durridge Inc.

Instruments:

YSI EXO 2 Multiparameter Sonde RAD7 and RAD H2O/ RAD H2O methods SEAL AA3 Autoanalyzer Element XR, High resolution inductively coupled plasma-mass spectrometer, ThermoFisher Cavity ring-down spectrometer, Picarro L2120i, Picarro G2301 Radium Delayed Coincidence Counter (RaDeCC) system for short-lived radium isotopes Gamma counter, well-type, germanium for long-lived radium isotopes

Provenance and Historical References:

Durridge Company Inc., 2020. RAD H2O. https://durridge.com/documentation/RAD_H2O_Manual.pdf. Durridge Company Inc., 2022. RAD7. https://durridge.com/documentation/RAD7%20Manual.pdf. Joung, D.J, Shiller, A.M., 2013. Trace element distributions in the water column near the Deepwater Horizon well blowout. Environ. Sci. Technol. 47(5): 2161-2168. https://doi.org/10.1021/es303167p. Joung, DongJoo and Alan M. Shiller. 2014. Dissolved barium behavior in Louisiana Shelf waters affected by the Mississippi/Atchafalaya River mixing zone. Geochimica et Cosmochimica Acta. 141:303-313. https://doi.org/10.1016/j.gca.2014.06.021. Moore, W. S., 1996. Large groundwater inputs to coastal waters revealed by 226Ra enrichments. Nature 380, 612–614. https://doi.org/10.1038/380612a0. Moore, W.S. and Arnold, R., 1996. Measurement of 223Ra and 224Ra in coastal waters using a delayed coincidence counter. J. Geophys. Res. 101, 1321–1329. https://doi.org/10.1029/95JC03139. Moore, Willard S. and Ralph Arnold. 1996. Measurement of 223Ra and 224Ra in coastal waters using a delayed coincidence counter. Journal of Geophysical Research Oceans: 101.C1: 1321-1329. https://doi.org/10.1029/95JC03139. Roberts, Hannah M. and Alan M. Shiller. 2015. Determination of dissolved methane in natural waters using headspace analysis with cavity ring-down spectroscopy. Analytica Chimica Acta. 856: 68-73. https://doi.org/10.1016/j.aca.2014.10.058. Shim, Moo-Joon, Peter W. Swarzenski, and Alan M. Shiller. 2012. Dissolved and colloidal trace elements in the Mississippi River delta outflow after Hurricanes Katrina and Rita. Continental Shelf Research. 42: 1-9. https://doi.org/10.1016/j.csr.2012.03.007.

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