Coastal N-2 Fixation Rates Coincide Spatially With Nitrogen Loss in the Humboldt Upwelling System off Peru

Kittu, Leila R.1; Paul, Allanah J.1; Fernandez-Mendez, Mar1,2; Hopwood, Mark J.1,3; Riebesell, Ulf1

2023-02-01

10.1029/2022GB007578

GLOBAL BIOGEOCHEMICAL CYCLES   影响因子和分区

0886-6236

1944-9224

Marine nitrogen (N-2) fixation supports significant primary productivity in the global ocean. However, in one of the most productive regions of the world ocean, the northern Humboldt Upwelling System (HUS), the magnitude and spatial distribution of this process remain poorly characterized. This study presents a spatially resolved data set of N-2 fixation rates across six coastal transects of the northern HUS off Peru (8 degrees S-16 degrees S) during austral summer. N-2 fixation rates were detected throughout the waters column including within the Oxygen Minimum Zone (OMZ) between 12 degrees S and 16 degrees S. N(2 )fixation rates were highest where the subsurface OMZ (O-2 < 20 mu mol L (-1)) was most intense and estimated nitrogen (N) loss was highest. There, rates were measured throughout the water column. Hence, the vertical and spatial distribution of rates indicates a colocation of N-2 fixation with N loss in the coastal productive waters of the northern HUS. Despite high phosphate and total dissolvable iron (TdFe) concentrations throughout the study area, N-2 fixation was still generally low (1.19 +/- 3.81 nmol L (-1) d (-1)) and its distribution could not be directly explained by these two factors. Our results suggest that the distribution was likely influenced by a complex interplay of environmental factors including phytoplankton biomass and organic matter availability, and potentially iron, or other trace metal (co)-limitation of both N-2 fixation and primary production. In general, our results support previous conclusions that N(2 )fixation in the northern HUS plays a minor role as a source of new N and to replenish the regional N loss.

nitrogen fixation marine nitrogen cycling Eastern Tropical South Pacific

SCI

英语

其他

German Federal Ministry of Education and Research (BMBF) through the cooperative research projects Humboldt Tipping["01LC1823B","FKZ03F0"]

Environmental Sciences & Ecology ; Geology ; Meteorology & Atmospheric Sciences

Environmental Sciences ; Geosciences, Multidisciplinary ; Meteorology & Atmospheric Sciences

WOS:000935659400001

AMER GEOPHYSICAL UNION

GEOSCIENCES

Web of Science

1.GEOMAR Helmholtz Ctr Ocean Res Kiel, Marine Biogeochem, Kiel, Germany
2.Helmholtz Ctr Polar & Marine Res, Alfred Wegner Inst, Bremerhaven, Germany
3.Southern Univ Sci & Technol, Shenzhen, Peoples R China

Kittu, Leila R.,Paul, Allanah J.,Fernandez-Mendez, Mar,et al. Coastal N-2 Fixation Rates Coincide Spatially With Nitrogen Loss in the Humboldt Upwelling System off Peru[J]. GLOBAL BIOGEOCHEMICAL CYCLES,2023,37(2).

Kittu, Leila R.,Paul, Allanah J.,Fernandez-Mendez, Mar,Hopwood, Mark J.,&Riebesell, Ulf.(2023).Coastal N-2 Fixation Rates Coincide Spatially With Nitrogen Loss in the Humboldt Upwelling System off Peru.GLOBAL BIOGEOCHEMICAL CYCLES,37(2).

Kittu, Leila R.,et al."Coastal N-2 Fixation Rates Coincide Spatially With Nitrogen Loss in the Humboldt Upwelling System off Peru".GLOBAL BIOGEOCHEMICAL CYCLES 37.2(2023).