Dissolved organic carbon, nitrogen and phosphorus in the N-E Atlantic and the N-W Mediterranean with particular reference to non-refractory fractions and degradation

Abstract

Dissolved organic carbon (DOC), dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP) measured in deep profiles in the N-E Atlantic and in the N-W Mediterranean in the period 1984-2002 are described. After accurate validation, they show close agreement with those previously published. Classic profiles were obtained, with concentrations decreasing in deep waters. In the Mediterranean and in the Atlantic comparable concentrations were found in the 1500-2000 m waters, 44-46 μmol l −1 DOC, 2.6-2.8 μmol l −1 DON and 0.02-0.03 μmol l −1 DOP. In the surface layers, DOC concentrations were higher, but DON and DOP concentrations lower, in the Mediterranean than in the Atlantic, leading to higher element ratios in the Mediterranean. In autumn, values were, respectively, DOC:DON 17 vs. 14, DOC:DOP 950 vs. 500 and DON:DOP 55 vs. 35. The data suggest an increase in DOC and DON in the North Atlantic Central Water over 15 years, which may be linked to the North Atlantic climatic oscillations.

Spatial and temporal variations in dissolved and particulate organic nitrogen in the equatorial Pacific: biological and physical influences

“…Research has indicated that phytoplankton and zooplankton play a role in affecting DON and PON variations in the euphotic zone (Davis and Benner, 2005;Aminot and Kerouel, 2004;Bronk, 2002). Many studies have shown that phytoplankton and zooplankton biomass are affected by physical and biogeochemical conditions such as upwelling intensity, nutrient concentration and nutricline (Wang et al, 2005a(Wang et al, , 2006aLe Borgne et al, 1999, suggesting implications for the DON and PON variability.…”

“…There have been reports of DON concentration in other parts of the ocean, showing a narrow range (4 to 7 mmol m −3 ) in a majority of the surface open ocean (Bronk, 2002;Aminot and Kerouel, 2004;Davis and Benner, 2005;Kahler and Koeve, 2001;Wong et al, 2002;Church et al, 2002). As Bronk (2002) summarized, the averaged DON concentration in the surface open ocean is 5.8 mmol m −3 with a standard deviation of 2 mmol m −3 .…”

“…There are a few studies showing relatively high DON concentrations (e.g., surface DON>7 mmol m −3 ) (Bronk, 2002;Vidal et al, 1999). In the field, DON concentration is often obtained by subtracting TIN and PON from total nitrogen (TN) of unfiltered water samples (Libby and Wheeler, 1997;Raimbault et al, 1999), or by the difference between TN and TIN in filtered water samples (Aminot and Kerouel, 2004;Davis and Benner, 2005; Vidal et al, 1999). Therefore, in some published studies, the in situ DON pool may represent a small portion of other materials such as living matter and small detritus.…”

Distribution of cold-water corals in the Whittard Canyon, NE Atlantic Ocean

“…A steep pycnocline separates the ENACW from Mediterranean Outflow Water (MOW). The MOW extends down to about 1200 m, mixing with the underlying Labrador Sea Water marked by a salinity minimum at around 1800 m. There is some influence of Norwegian Sea Water at around 2000 m. Below this depth North Atlantic Deep Water (NADW) derived from Greenland appears, and is heavily influenced by the pervading Atlantic Antarctic Bottom Water at greater depths (Matthias and Godfrey, 2003;Aminot and Kerouel, 2004;De Mol et al, 2011).…”

“…Water masses in the North Eastern Atlantic have been described by Vangrieshem (1985) and Arhan et al (1994). Aminot and Kerouel (2004) summarised the water masses as North Atlantic Surface Water (max 100 m depth) overlying Eastern North Atlantic Central Water (ENACW) ( o700 m). A steep pycnocline separates the ENACW from Mediterranean Outflow Water (MOW).…”