Production of Hydroxylamine in the Epilimnion of a Dam Lake

Abstract

　In the euphotic layer of a dam lake (reservoir), we discovered a phenomenon that hydroxylamine (NH₂OH) accumulates at a high concentration at the same time as the increase in Chl-a, which is an indicator of phytoplankton biomass. Therefore, to investigate the presence or absence of NH₂OH production by phytoplankton, we conducted a culture experiment using a single sterile strain of cyanobacteria isolated from the dam lake. Our results confirmed that NH₂OH increased with the increase in Chl-a, and the ability of cyanobacteria to produce NH₂OH was clarified. This result suggests that NH₂OH detected in the euphotic layer during the dominance of cyanobacteria in summer is produced by the cyanobacteria.