Ammonium and sulfate gradients have been measured in sediment at more than 80 marine sites where sediment accumulation rates were determined using conventional dating methods. Dissolved ammonium and sulfate gradients are directly related to organic carbon burial and sedimentation rates. Low gradients correspond to deep ocean regions where sediment accumulation rates are millimetres per 1000 years and sediment organic carbon concentrations are <0.1%. The highest gradients are found in coastal sites under salmon aquaculture cages where sediment accumulation rates are centimetres per year and organic carbon concentrations are >5%. Since the pore water gradients are a function of present day redox reactions, the method provides an estimate of recent sediment accumulation rates, which can range from 0.1 to 1000 cm ka (super -1) . It is unique in that it provides a method of determining accumulation rates where conventional dating methods cannot be used because of post-depositional mixing. After a mixing event, the pore water profiles re-adjust to reflect present-day redox conditions, since the dissolved ions are free to diffuse through the interstitial pore water. The method can be applied at most locations where sediment cores can be recovered. Sediment sub-samples must be removed from the cores when they are collected in order to minimize errors due to sample storage. Limitations to the method are discussed.

West: -64.1500 East: -62.0900 North: 45.1600 South: 44.2500

West: NaN East: NaN North: NaN South: NaN

Expedition: 119

Provider: SEDIS Publication Catalogue

Data set link: http://sedis.iodp.org/pub-catalogue/index.php?id=2000-020961 (c.f. for more detailed metadata)

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