Ammonium (NH4 +) concentration profiles in piston-core sediments of the Carolina Rise and Blake Ridge generally have linear concentration profiles within the sulfate reduction zone (Borowski, 1998). Deep Sea Drilling Project (DSDP) Site 533, located on the Blake Ridge, also displayed a linear ammonium concentration profile through the sulfate reduction zone and the profile linearity continues into the upper methanogenic zone to a depth of ~200 meters below seafloor (mbsf), where the first methane gas hydrates probably occur (Jenden and Gieskes, 1983; Kvenvolden and Barnard, 1983). Sediments from the Ocean Drilling Program (ODP) Leg 164 deep holes (Sites 994, 995, and 997) also exhibit linear ammonium profiles above the top of the gas hydrate zone (~200 mbsf) (Paull, Matsumoto, Wallace, et al., 1996).
Borowski, W.S., C.K. Paull. 2000. Nitrogen isotopic composition of pore water ammonium, Blake Ridge, Site 997, ODP Leg 164. In: C.K. Paull, R. Matsumoto, P.J. Wallace, and W.P. Dillon, Proceedings ODP, Scientific Results, 164: College Station, TX (Ocean Drilling Program), 171-172. DOI: 10.2973/odp.proc.sr.164.213.2000
Proceedings ODP, Scientific Results, 164