Nitrogen Concentration of River Water
Copyright The National Institute for Agro-Environmental Sciences
The National Institute for Agro-Environmental Sciences (NIAES) of Japan announced on August 18, 2009, that it had developed a broad-based model to extensively estimate changes in nitrogen circulation due to the production, trading and consumption of food, and the influence on water quality. Nitrogen flows into national land area externally from use of fertilizer, food trading and seafood capture, etc. After circulating from crops to farm animals and humans, nitrogen flows out into groundwater and rivers.
According to the model, due to increases in population and per capita food demand in Japan, nitrogen inflow increased until the late 1980s. Since the 1990s, a decrease in use of nitrogen fertilizers has suppressed the nitrogen outflow. Estimation of nitrogen in groundwater and rivers by region indicated high levels of nitrogen near big cities and in areas with abundant livestock farming.
On the other hand, the model also showed that most nitrogen inflow into national land area comes from fertilizers, and is still on the increase in China and Southeast Asian countries such as Thailand and Vietnam. Nitrogen concentrations in China are extremely high in the downstream areas of the Yellow River and the Yangzi River where intensive agriculture is conducted.
This estimating model has made it possible to find out what elements, related to production and consumption of food, cause water contamination in individual regions. It can also predict impacts on the environment due to changes in food demand in response to future demographic trends and the cultivation of feed and energy crops.
National Institute for Agro-Environmental Sciences official website