Abstract:

With the use of closed-system incubations, the effect of photochemical degradation on the carbon cycle in a eutrophic, semiarid estuary (Baffin Bay, Texas) was investigated. Two series of closed-system incubation data were collected. Measurements of stable carbon isotope of dissolved organic carbon were made at the beginning and the end of each incubation whereas Chl a was determined at the start of each incubation. The Photochemical production rate of dissolved inorganic carbon was between 0.16 to 0.68 µM hr-1. It was observed that there was a daily removal of 0.3%1.5% of the standing stock of dissolved organic carbon (DOC). The photochemical degradation rate and chlorophyll a concentration were negatively correlated. The stable carbon isotope composition (δ13C-18.6‰) of degraded DOC, as determined from the DIC “Keeling” plot, indicated that the enrichment of 13C in DOC was due to the high photochemical lability. This dataset supports the publication: Wang, H., Hu, X., Wetz, M. S., Hayes, K. C., & Lu, K. (2020). Photomineralization of organic carbon in a eutrophic, semiarid estuary. Limnology and Oceanography Letters. doi:10.1002/lol2.10146

Suggested Citation:

Hongjie Wang, Xinping Hu, Michael S. Wetz, Kenneth C. Hayes, Kaijun Lu. 2020. Dataset for: Photomineralization of organic carbon in a eutrophic, semiarid estuary. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/0WHA19WV

Publications:

Wang, H., Hu, X., Wetz, M. S., Hayes, K. C., & Lu, K. (2020). Photomineralization of organic carbon in a eutrophic, semiarid estuary. Limnology and Oceanography Letters. doi:10.1002/lol2.10146

Purpose:

This study was conducted to examine the photochemical lability and its impact on organic carbon accumulation by carrying out a series of closed-system incubations in summer 2017.

Data Parameters and Units:

Incubation Month, Sampling Date (mm/dd/yy), Station, Latitude (degree North), Longitude (degree West), Samplinglayer (meter), Filtered or whole water, Salinity (PSU), Chlorophyll a (µg L-1), Dissolved inorganic carbon (µmol L-1), Dissolved inorganic carbon change (µmol L-1), Stable carbon isotope of dissolved inorganic carbon (per mille), Stable carbon isotope of dissolved organic carbon (per mille), stable carbon isotope of photochemical degraded organic carbon (per mille).

Methods:

Both surface and bottom water were collected from Baffin Bay main channel (BB3 and BB6) on August 11, 2017. The water quality measurements (temperature, salinity and Chl a) were collected at the beginning of our experiment. Both filtered (through pre-combusted Whatman GF/F filters, pore size=0.7 µm) and whole water from surface and bottom were distributed into four 1 L ground-neck quartz bottles. Microbial activities were stopped by adding 400 mL HgCl~2~ before the incubation. The quartz bottles were exposed to natural sunlight and placed in a plastic tray filled with water (~15 cm height) in Texas A&M University-Corpus Christi. DIC (concentration and δ^13^C) was collected every 3 to 4 days from August 11, 2017, to September 16, 2017. We only carried filtered water (surface and bottom) incubation from September 18, 2017, to October 25, 2017. δ^13^C~DIC~ samples were saved in 2 mL borosilicate autosampler vials. DIC samples were stored in 4 mL borosilicate vials. The δ^13^C~DOC~ samples were preserved in 40 mL Fisher brand borosilicate glass EPA vials with Teflon-lined silicone septa. DIC was measured with an infrared CO~2~ detector-based DIC analyzer (AS-C3 Apollo SciTech Inc.) in Hu’s lab at Texas A & M University-Corpus Christi. The precisions for DIC was within 2 µmol L-1. δ^13^C~DIC~ samples were measured at J. Brandes’ lab at Skidaway Institute of Oceanography, University of Georgia. The δ^13^C~DOC~ samples were analyzed by C. Osburn’s lab in North Carolina State University. The precision of the δ^13^C~DIC~ and δ^13^C~DOC~ analysis was ±0.1‰ and ±0.2‰, respectively.

Instruments:

15 mL syrings

Error Analysis:

There was no duplicate bottle for all incubations.

Individual Files: