Bynoe Harbour Habitat Mapping Survey 2016: Total oxygen uptake and total carbon dioxide release from core incubation experiments

Maintenance and Update Frequency: asNeeded | Statement: Bottom sediments were collected using a Smith McIntyre grab. Two 5 cm diameter cores of surface sediments were extracted from the grabs by hand-pushing 5 cm diameter core barrels into the sediments. The cores were overlain with 0.153 L of filtered (2 um) and uv-treated seawater and then were incubated in the dark for ~4-6 hours at ~25oC after a ~3 hour pre-incubation period. Dissolved oxygen levels were measured at ~30 minute intervals using the Presens technology. Samples for dissolved inorganic carbon (DIC) analysis were taken at the start and finish of each incubation. Blank cores comprising filtered and uv-treated seawater only accompanied all incubations. DIC concentrations were determined using a DIC analyser and infrared-based CO2 detector (Geoscience Australia). CO2 production and O2 consumption rates were calculated by concentration differences (T=1 - T=0) over the course of the incubation. Accuracy of O2 measurements was ± 0.1 mg L-1. The %RSDs of the precisions and accuracies of the dissolved inorganic carbon analyses were both 0.6. The O2 consumption and CO2 production rates of the 3 blank samples run in duplicate at the start and end of the field campaign, and midway, were -3.5 ± 2.2 and -1.5 ± 6.5 mmol m-2 d-1 respectively. Nutrient fluxes (NOx, DIN, NO2, N2, SiO4 and PO4) were undertaken at two stations on duplicate cores during the first leg of the voyage. Dissolved nutrients were determined by Segmented Flow Analysis - SEAL AA3 (method: Ryle V.D., Mueller H.R. and Gentien P.(1981). Automated Analysis of Nutrients in Tropical Seawaters, AIMS Oceanography Series Tech. Bulletin No.3, AIMS.OS.81.2) at the Townsville Laboratories of the Australian Institute of Marine Sciences. Dissolved N2 gas concentrations were determined using Membrane Inlet Mass spectrometry (MIMS) at the Ecochemistry Laboratory (University of Canberra) following methods and calculation protocols described in Kana et al. (1994 & 1998) and using the solubility constants of Weiss (1970). Kana, T. M., C. Darkangelo, M. D. Hunt, J. B. Oldham, G. E. Bennett & J. C. Cornwell, 1994. Membrane inlet mass spectrometer for rapid high-precision determination of N2, O2 and Ar in environmental water samples. Analytical Chemistry 66/23: 4166-4170. Kana, T.M., Sullivan, M.B., Cornwell J.C. and Groszkowski, K. 1998. Denitrification in estuarine sediments determined by membrane inlet mass spectrometry. Limnology and Oceanography 43: 334