Biotic and Abiotic Controls on Dinitrogen Production in Coastal Sediments

Abstract

Nitrogen (N) is an essential nutrient that limits marine primary productivity and biogeochemical processes across a range of spatial and temporal scales (Canfield et al., 2010;Vitousek & Howarth, 1991). Historically, microbial N fixation has been the primary N source that converts dinitrogen gas (N 2 ) to biologically available forms, while denitrification has traditionally been recognized as the most important pathway through which fixed N is converted back to atmosphere (Devol, 2015). In response to 20 century increases N fertilizer inputs and fossil fuel combustion, however, studies suggest that ∼20% of N inputs to the modern ocean now occurs via terrestrial nutrient runoff and atmospheric deposition (Canfield et al., 2010;Seitzinger, 2008). The fate of such inputs is controversial, given that microbial processes in shelf sediments may consume a significant fraction of anthropogenic N inputs before they enter the open ocean. Substantial uncertainty surrounds how much N is lost to N 2 in marine sediments (

Global variations and controlling factors of anammox rates

“…Soil anammox is a complex biochemical process that is conducted by anammox bacteria (Kartal et al, 2011; Zhu et al, 2019). Higher abundance of anammox bacteria generally induced a greater anammox rate (Sun et al, 2021). Gu et al (2017) showed that the anammox rates rose from 0.34 to 1.04 nmol N 2 g −1 h −1 as the abundance of anammox bacteria increased from 1.39 × 10 5 to 3.58 × 10 6 copies g −1 soil.…”

“…The rate of anammox was enhanced by 129.4% with the concentrations of nitrite increasing by 107.7% (Meyer et al, 2005). Higher levels of ammonium can increase the abundance and activities of anammox bacteria, and ergo expedite the anammox rates (Bai, Xi, et al, 2015; Sun et al, 2021). The magnitude of anammox bacteria was grown from 4.86 × 10 6 to 6.11 × 10 6 copies g −1 soil, while the concentrations of ammonium increased from 10.0 to 20.5 mg kg −1 (Nie et al, 2018).…”