Hydrochemical Structural Patterns of the Lena River–Laptev Sea Mixing Zone in the Autumn Period

• Published in: Oceanology (Washington. 1965) 2020-11, Vol.60 (6), p.735-741
• Main Authors: Kostyleva, A. V., Polukhin, A. A., Stepanova, S. V.
• Format: Article
• Language: English
• Subjects: Alkalinity; Ammonium; Ammonium compounds; Chlorophyll; Chlorophyll a; Dissolved oxygen; Distribution; Earth and Environmental Science; Earth Sciences; Marine Chemistry; Mineral nutrients; Nitrogen; Nutrients; Oceanography; Parameters; Phosphates; Phosphorus; River discharge; River flow; Rivers; Runoff; Silicon; Stagnant water
• ISSN: 0001-4370; 1531-8508
• DOI: 10.1134/S0001437020060053

This study was based on data obtained during the cruise 63 of the R/V Akademik Mstislav Keldysh in September 2015. We examine the features of the hydrochemical structure of the Lena River–Laptev Sea mixing zone. The studies were carried out in the eastern part of the Laptev Sea on a quasi-meridional transect, with the length of 710 km along 130°30' E. The distribution of dissolved oxygen, pH, alkalinity, major nutrients (phosphates, silicon, nitrate, and ammonium nitrogen), and chlorophyll a was analyzed. The relationship between the main hydrochemical parameters and chlorophyll a was considered. The distribution of hydrochemical parameters is similar to the data of previous studies: significant removal of silicon by waters of the Lena River (66.6 μM) with a moderate nitrate content (3.87 μM) and low concentration of mineral phosphorus (0.08 μM) in the area of strong influence of river runoff (salinity of 3.012 PSU). The presence of a near-bottom stagnant water zone in the part of research area affected by river runoff was detected. It is shown that the influx of mineral forms of nitrogen and phosphorus into the marine region of the Lena River delta occurs mostly as a result of nutrient recycling rather than due to the continental runoff.