Biogeochemical and physical controls on ammonium accumulation on the Chukchi shelf, western Arctic Ocean

Spatial variability of ammonium concentrations along repeat transects were examined on the Chukchi shelf during 2012-2018. Two distinct near-bottom high ammonium pools (>1 & mu;mol/kg) near 67.5 degrees N and 72.5 degrees N of the transects were identified in all years. The accumulation of ammonium in the regions is driven primarily by a combination of biogeochemical processes (e.g., dynamic bacterial remineralization of organic matter) and physical controls (e.g., strong density-contrast barrier limits upward mixing of ammonium). The ammonium pool on the shelf may became larger in the expectation of the stronger bacterial remineralization following elevate primary production, and may have potential impact on the structure and productivity of ecosystem on the Chukchi shelf.

Automated summary

The spatial variability of ammonium concentrations along repeat transects on the Chukchi shelf from 2012 to 2018 was studied. Two distinct near-bottom high ammonium pools (>1 μmol/kg) were identified at 67.5 degrees N and 72.5 degrees N in all years. The accumulation of ammonium in these regions is primarily influenced by a combination of biogeochemical processes (such as dynamic bacterial remineralization of organic matter) and physical controls (such as a strong density-contrast barrier limiting upward mixing of ammonium). The expansion of the ammonium pool on the shelf may have potential impacts on the structure and productivity of the ecosystem on the Chukchi shelf.