Background

   Nitrogen (N), an essential element for plants, is one of the main contributor to groundwater contamination in rural areas. Nitrate (NO3-) that is the most oxidized form of N often contaminates groundwater when excess N was applied to farmland. In contrast, high concentrations of ammonium (NH4+) was detected in groundwater below vegetable fields in the downstream areas of the Huong River, Central Vietnam. The objective of the study is to determine the contamination sources and mechanisms of nitrogen contamination in groundwater by using 15N natural abundance and functional genes of microorganisms. We are developing a new method to collect NH4-N, NO3-N, and organic N in water and soil samples for δ15N analysis. Functional genes like narG, napA, and nosZ are quantified to obtain the information on nitrogen dynamics in deep soil.

Expected results

   We can propose the best fertilizer and manure managements in rural areas of Central Vietnam according to scientific data analysis using new technologies.

URL

http://www.eme.okayama-u.ac.jp/Sections/Lithosphere/index-e.html