Abstract:

This dataset contains nitrogen concentrations and isotopic compositions of Baffin Bay and its tributaries. Sampling in Baffin Bay, Texas was conducted from 2020-11-01 to 2022-06-30 and surface water of six Baffin Bay sites were collected monthly. The surface water samples of tributaries that drain into Baffin Bay sub-watersheds were collected six times before (dry period) and after (wet period) the rain events that occurred in spring 2021, fall 2021, and spring 2022. Surface water was collected at 20 cm below the air-water interface using high density polyethylene (HPDE) bottles.

Suggested Citation:

Wetz, Michael S., J. David Felix, Yixi Qiu, and Dominic Burch. 2024. Nitrogen concentrations and isotopic compositions of Baffin Bay, Texas and its tributaries obtained from 2020-11-01 to 2022-06-30. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/3jzxecp8

Purpose:

The goal of data collection was to identify “hot spots” of nutrient enrichment and identify potential surficial nutrient sources to both Baffin Bay and its feeder creeks. Results contribute to our understanding of priority nutrient sources/source locations in support of watershed restoration efforts.

Data Parameters and Units:

Date, time, long (longitude), lat (latitude), pH, NH4 (µM), NO2, NO2+NO3, NO3, TDN-NH4, DON, δ15N-NH4, δ15N-NO3, δ18O-NO3, δ15N-DON, δ15N-DIN, Cl (uM), SO4 um, Precipitation (inches), Lightning (no. of lightning strikes).

Methods:

A colorimetric method was used to measure the NO3-/NO2- concentrations of watershed sample (Tsikas, 2007). The cadmium reduction method was used to reduce NO3 to NO2 after NO2 was measured. NO3‑ was measured by subtracting NO2 from the NO3-/NO2- concentration. A Dionex Aquion Ion Chromatography 4000i, equipped with an AS-AP autosampler and AS4A separation column was used to measure the NO3-/NO2-, Cl- and SO42 concentrations of airshed samples. The o-phthalaldehyde (OPA) fluorometric method (Holmes et al., 1999) was used to ammonium concentrations of watershed and airshed samples. Furthermore, DON, DIN and TDN were all determined. Dissolved free amino acids (DFAA) which are expected to be 1.2 to 12.5% of the total DON pool (Sipler and Bronk, 2015) were represented by glycine. N-acetyl amino polysaccharides (N-AAPs), which are important to the semi-labile DON pool (Aluwihare et al., 2005) were represented by N-acetyl-D-glucosamine. Using the denitrifier bacteria method at the University of California, Davis Stable Isotope Facility (Sigman et al., 2001), the isotopic composition of NO3-/NO2- (δ15N-NO3-/NO2- and δ18O-NO3-/NO2-) was measured. Data correction was done after measurements of δ15N-NO3- and δ18O-NO3- in Internationally recognized standards (USGS32, USGS34, USGS35, IAEA-N3). In addition, δ15N-NH4+ and δ15N-TDN were also determined.

Error Analysis:

Blank cells result in either no data collected or data not available.

Provenance and Historical References:

Aluwihare, LI, Repeta DJ, Pantoja S, Johnson CG. 2005. Two chemically distinct pools of organic nitrogen accumulate in the ocean. 308(5724):1007-10. https://doi.org/10.1126/science.1108925 Felix, J. David, EM Elliott, TJ Gish, LL McConnell, and SL Shaw. 2013. Characterizing the isotopic composition of atmospheric ammonia emission sources using passive samplers and a combined oxidation-bacterial denitrifier approach. Rapid Commun. Mass Spectrom., 27: 2239-2246. https://doi.org/10.1002/rcm.6679 Holmes, Robert M, Alain Aminot, Roger Kérouel, Bethanie A Hooker, and Bruce J Peterson. 1999. A simple and precise method for measuring ammonium in marine and freshwater ecosystems. Canadian Journal of Fisheries and Aquatic Sciences. 56(10): 1801-1808. https://doi.org/10.1139/f99-128 Sigman, DM, KL Casciotti, M. Andreani, C. Barford, M. Galanter, JK Böhlke. 2001. A bacterial method for the nitrogen isotopic analysis of nitrate in seawater and freshwater. Anal Chem. 73(17):4145-53. https://doi.org/10.1021/ac010088e Sipler, Rachel & Bronk, Deborah. (2014). Dynamics of Dissolved Organic Nitrogen. 10.1016/B978-0-12-405940-5.00004-2. Tsikas, Dimitrios. 2007. Analysis of nitrite and nitrate in biological fluids by assays based on the Griess reaction: Appraisal of the Griess reaction in the l-arginine/nitric oxide area of research. Journal of Chromatography B, 851(1-2): 51-70. https://doi.org/10.1016/j.jchromb.2006.07.054.

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