Abstract:

This dataset contains ammonium photoproduction in porewater samples obtained from 6 locations in Baffin Bay, Texas from 2020-10-31 to 2022-05-26. A solar simulator (Model: Atlas SUNTEST CPS+) was used to irradiate samples at different time intervals (0,3,12,24,72 hours).

Suggested Citation:

Abdulla, Hussain. 2024. Ammonium photoproduction in porewater samples obtained in Baffin Bay from 2020-10-31 to 2022-05-26. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/e9kjrn2r

Purpose:

This experiment was done to estimate the ammonium photoproduction rate from photooxidation of porewater dissolved organic nitrogen.

Data Parameters and Units:

Latitude, longitude, time (hours), Supplemental Information, Ammonium (umole/L).

Methods:

A solar simulator (Model: Atlas SUNTEST CPS+) was used to irradiate samples at different time intervals (up to 72 hrs) and the samples were further analyzed accordingly with the irradiation wavelength set at 300-400 nm which transfers the following heat fluxes (kJ/m2): 702 in 3 hours, 2808 in 12 hours, 5616 in 24 hours, and 16848 in 72 hours. The solar simulator lamps were kept on for the entire experimental period during the irradiation of the samples. Five subsamples (60-65mL each) in five quartz flasks underwent irradiation at 3, 12, 24, 72 hours along with a dark control. A dark control was aluminum wrapped and exposed to irradiation in 72 hours to monitor heat effect. The irradiated waters were then preserved for the following experiments: ammonium concentration, UV-Vis measurement, and structural elucidation by Mass Spectrometry. Ammonium (NH4+) concentrations were determined using the Ortho-phthalaldehyde (OPA) method (Holmes et al., 1999) and measurements were conducted with the fluorescence detector in High-Performance Liquid Chromatography (HPLC) Ultimate 3000 model. OPA working solution (WS) is made up of 200mL borate buffer + 1mL sodium sulfite + 10mL OPA as the ratio is Borate : Na2SO3 : OPA = 200:1:10. Borate buffer solution: 8g of sodium tetraborate in 200 mL H2O makes up 200 mL of borate buffer for the WS. Sodium sulfite solution: 0.08g of Na2SO3 in 10 mL of H2O makes up 10 mL of sodium sulfite solution, then take only 1 mL for the WS. OPA fluorescence solution: 0.4g of OPA in 10mL of ethanol makes up 10 mL of OPA fluorescence solution for the WS. The WS was stored in the dark for at least 1 day prior to reaction with samples. For the determination of ammonium (NH4+) concentration, 0.25 mL of a sample was mixed with 1mL of the WS then incubated in the dark for at least 2 hours prior to the detection by HPLC - fluorescence detector. The NH4+ concentration must be measured between 2-8 hours of incubation time. Ammonium chloride (NH4Cl) solutions were used as the calibration standard from 0.1 – 400 µM.

Provenance and Historical References:

Robert M Holmes, 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

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