Evidence of intense suboxia and anoxia in a tropical bay of the Gulf of California
Periodo de realización: 2018/06/01 al 2018/01/01
Tipo: Artículo científico
Lugar(es) de estudio: Golfo de California, Baja California Sur, México
Resumen: "The expansion of the upper boundary of the oxygen minimum zone (OMZ) has been associated with the low
solubility of oxygen in the surface ocean due to global warming in tropical regions. However, sedimentary
records of d15N of sinking particulate organic matter and sediments suggest that oxygen solubility is controlled
by oceanographic forcing in the tropical equatorial region. To determine the intensi?cation of the OMZ within its
upper border, d15N analysis of the organic matter in super?cial sediments of La Paz Bay was carried out. In the
present work, 115 samples of super?cial sediment were collected in the interval of 2–407 m depth in La Paz Bay.
The surface sediments were analysed for the nitrogen isotopic composition of their organic matter. Hypoxia
conditions (< 60 µM) at 100 m to depth suggest an intense denitri?cation of the water column that it was
re?ected in the sedimentary d15N. The d15N of the organic matter is 1.5‰ greater in the bay than in the mouth of
the Gulf of California, indicating greater denitri?cation towards the interior of the bay with respect to the gulf
mouth. The intense suboxia/anoxia conditions have been maintained due to a well-mixed water column that
promotes exported productivity in La Paz Bay."