The Changes of Nitrate/Nitrite Concentrations and Nitrate/Nitrite Reductase Activity Changes in Soil for the Development a HONO(nitrous acid) Model

다국어 초록 (Multilingual Abstract)

The aim of this study is to determine the activity of enzymes by soil microorganisms and to develop a HONO production model according to the change in nitrogen concentration in the soil. Most plants absorb nitrogen in the form of nitrate (NO₃⁻) after ammonium (NH₄⁺) is converted into NO₃⁻ by nitrifying bacteria. The NO₃⁻ is reduced to nitrite (NO₂⁻) by nitrate reductase, which is also reduced to NH₄⁺ by nitrite reductase. It is important for the development of HONO model to measure the concentration of a nitrogen source in the soil. Soil samples were collected from Jeollanam-do area. Quantitative analysis of NH₄⁺ was performed using the indophenol method. For quantitative analysis of NO₂⁻ and NO₃⁻, HPLC analysis at 214 nm (Sphereclone Sax column) was performed. The LOD and LOQ of NO₂⁻ and NO₃⁻ were lower than 0.1 ppm and 0.2 ppm, respectively. The concentration decreased with increasing soil depth. Soil samples from soybean fields had a reduced NO₃⁻ concentration from 111.60 ppm to 46.20 ppm. We plan to complete the HONO emission model by measuring the change in the nitrogen concentration and the activity of related enzymes in Korean soil and estimating the reaction rate constant.