TY - JOUR
T1 - High-resolution nitrogen gas profiles in sediment porewaters using a new membrane probe for membrane-inlet mass spectrometry
AU - Hartnett, Hilairy E.
AU - Seitzinger, Sybil P.
N1 - Funding Information:
We would like to thank A. Laursen for assistance with the MIMS system. C. Reimers kindly provided the opportunity to collect sediment samples and T. Komada assisted in sample collection. HEH received funding from the Institute of Marine and Coastal Sciences.
PY - 2003/10
Y1 - 2003/10
N2 - A probe inlet for membrane-inlet mass spectrometry (MIMS) was developed to measure dissolved nitrogen and argon gas in sediment porewaters. This technique represents a significant improvement in the measurement of dissolved gas ratios in sediment cores and in small volume samples (<5 ml). The probe is stable, inexpensive and has relatively fast equilibration times (∼ 4-5 min) for dissolved N2/Ar ratio analyses. The membrane probe is mounted at the end of a stainless steel capillary (0.75 mm OD) connected directly to the inlet system of a quadrupole mass spectrometer. The membrane is ∼ 1 mm x 0.5 mm resulting in profiles that have a depth resolution of < 2 mm. Nitrogen/argon ratios measured with the probe inlet have a precision of < 0.2%. Porewater N2/Ar ratios measured in cores collected from Raritan Bay, NJ, indicated that N2 was in equilibrium with the atmosphere in overlying waters and that nitrogen was up to 8% supersaturated by a depth of 1 cm. The increase in N2 is consistent with nitrogen production from denitrification of ∼ 2 mmol N2 m-2 day-1. High-resolution nitrate profiles also provide evidence for denitrification, with nitrate being depleted at the same depth horizon where N2 gas concentrations are increasing.
AB - A probe inlet for membrane-inlet mass spectrometry (MIMS) was developed to measure dissolved nitrogen and argon gas in sediment porewaters. This technique represents a significant improvement in the measurement of dissolved gas ratios in sediment cores and in small volume samples (<5 ml). The probe is stable, inexpensive and has relatively fast equilibration times (∼ 4-5 min) for dissolved N2/Ar ratio analyses. The membrane probe is mounted at the end of a stainless steel capillary (0.75 mm OD) connected directly to the inlet system of a quadrupole mass spectrometer. The membrane is ∼ 1 mm x 0.5 mm resulting in profiles that have a depth resolution of < 2 mm. Nitrogen/argon ratios measured with the probe inlet have a precision of < 0.2%. Porewater N2/Ar ratios measured in cores collected from Raritan Bay, NJ, indicated that N2 was in equilibrium with the atmosphere in overlying waters and that nitrogen was up to 8% supersaturated by a depth of 1 cm. The increase in N2 is consistent with nitrogen production from denitrification of ∼ 2 mmol N2 m-2 day-1. High-resolution nitrate profiles also provide evidence for denitrification, with nitrate being depleted at the same depth horizon where N2 gas concentrations are increasing.
KW - Denitrification
KW - High-resolution nitrogen gas profile
KW - Membrane-inlet mass spectrometry
KW - Sediment porewater
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U2 - 10.1016/S0304-4203(03)00093-8
DO - 10.1016/S0304-4203(03)00093-8
M3 - Article
AN - SCOPUS:0345447482
VL - 83
SP - 23
EP - 30
JO - Marine Chemistry
JF - Marine Chemistry
SN - 0304-4203
IS - 1-2
ER -