Water column nutrients and sedimentary denitrification in the Gulf of Maine

• Main Authors: John P. Christensen, David W. Townsend, Joseph P. Montoya
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1994
• Subjects: Wilkinson; North Atlantic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.485.8473; http://grampus.umeoce.maine.edu/dave/Christensen-et-al-1996-Cont-Shelf-Res.pdf

Abstract--Sedimentary denitrification acts to remove nitrogen from both the sediments and water column in continental shelf ecosystems, sothat in enclosed shelf areas where water residence times are long (about a year in the Gulf of Maine), significant rates of sedimentary denitrification might lower inorganic nitrogen concentrations. We examined this using a basin-wide suite of hydro-graphic and nutrient data collected in mid-summer. Total inorganic nitrogen (TIN) concentrations (nitrate + nitrite + ammonium) were highest in the aged North Atlantic continental slope waters found at depth in the Jordan Basin on the eastern side of the Gulf. Phosphate and silicate concentrations were moderately high in these waters. On the western side of the Gulf, Wilkinson Basin receives much less of the nutrient-rich slope waters. In these deep waters, TIN concen-trations were lower and phosphate and silicate concentrations higher than in the Jordan Basin. In the intermediate and deep waters, TIN/PO 4 ratios averaged 19 on the eastern side but only 15-16 on the western side of the Gulf. Partially isolated regions within the Gulf had even lower TIN/PO 4 ratios. The differences in this ratio suggested the occurrence of either a non-stoichiometric reduction in nitrogen or an enrichment in phosphate between the eastern and western sides of the Gulf. The relationship between phosphate and silicate was identical in open waters on both sides of