TY - JOUR
T1 - Evidence of intense suboxia and anoxia in a tropical bay of the Gulf of California
AU - Sánchez, Alberto
AU - Rodríguez-Figueroa, Griselda
AU - Shumilin, Evgueni
AU - Ortiz-Hernández, Ma Concepción
N1 - Publisher Copyright:
© 2018 Elsevier Ltd
PY - 2018/9/15
Y1 - 2018/9/15
N2 - 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 δ15N of sinking particulate organic matter and sediments suggest that oxygen solubility is controlled by oceanographic forcing in the tropical equatorial region. To determine the intensification of the OMZ within its upper border, δ15N analysis of the organic matter in superficial sediments of La Paz Bay was carried out. In the present work, 115 samples of superficial 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 denitrification of the water column that it was reflected in the sedimentary δ15N. The δ15N of the organic matter is 1.5‰ greater in the bay than in the mouth of the Gulf of California, indicating greater denitrification 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.
AB - 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 δ15N of sinking particulate organic matter and sediments suggest that oxygen solubility is controlled by oceanographic forcing in the tropical equatorial region. To determine the intensification of the OMZ within its upper border, δ15N analysis of the organic matter in superficial sediments of La Paz Bay was carried out. In the present work, 115 samples of superficial 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 denitrification of the water column that it was reflected in the sedimentary δ15N. The δ15N of the organic matter is 1.5‰ greater in the bay than in the mouth of the Gulf of California, indicating greater denitrification 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.
KW - Denitrification
KW - Gulf of California
KW - Oxygen minimum zone
KW - Stable isotopes of nitrogen
UR - http://www.scopus.com/inward/record.url?scp=85053525031&partnerID=8YFLogxK
U2 - 10.1016/j.csr.2018.09.006
DO - 10.1016/j.csr.2018.09.006
M3 - Artículo
SN - 0278-4343
VL - 168
SP - 21
EP - 27
JO - Continental Shelf Research
JF - Continental Shelf Research
ER -