Contribution of humic substances to the dissolved nitrogen pool in the Greenland Sea

LARA, RUBÉN JOSÉ; HUBBERTEN, ULA

MARINE CHEMISTRY

Elsevier

Lugar: Amsterdam; Año: 1993 p. 327 - 336

0304-4203

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:612.0pt 792.0pt; margin:72.0pt 90.0pt 72.0pt 90.0pt; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> The concentration and distribution of dissolved nitrogenous compounds was studied in the Greenland Sea in June 1991. Dissolved organic (DON) and inorganic nitrogen (DIN) were determined in seawater of different origin and depth. Dissolved organic matter was isolated on XAD-2 resin and fractionated into its non-humic hydrophitic (HI), and so-called humic components (hydrophobic acid, HbA, and hydrophobic neutral, HbN). From all fractions the DON content was subsequently determined. Total DON concentrations were about 5 µmol N L-1 in the surface and 3 µmol N L-1 below depths of 150-200 m. DIN varied between 1.5 and 16 µmol N L-1. There was a highly significant inverse correlation (r = -0.75) between DON and DIN suggesting a close coupiing in the uptake and release of the different forms of nitrogen. The mean DON concentration in the XAD-fractions were for Hl = 2.3 µmol N L-1, for HbA = 0.8 µmol N L-1 and for HbN = 1.0 µmol N L-1.The average percentage contributions were, respectively, 56%, 19% and 25%. This means that about 56% of the total DON does not belong to the ´humic fraction´. The HbN fraction was evenly distributed in the water column, without any obvious relationship with water masses, depth, or nutrient status In contrast, the HbA fraction showed a significant correlation with total DON.