Monitoring of Inorganic Nitrogen Levels in the Surface and Ground Water of the Red River Delta, Northern Vietnam

Nutrient (N, P, Si) transfers in the subtropical Red River system (China and Vietnam): Modelling and budget of nutrient sources and sinks

“…This is a severe restriction for an overall evaluation of the water quality status of the whole Red River system because the delta is the place where population density and human pressure on water resources are the greatest. Water quality of the small urbanized tributaries or distributaries of the Red River delta is often much altered (Kurosawa et al, 2004;Luu et al, comm. pers.).…”

Temporal and Spatial Variations of Inorganic Nitrogen Levels in Surface and Groundwater Around Hanoi, Vietnam

“…In the monitoring of October 2002 (Kurosawa et al 2004), however, the nitrate-N concentration detected in the groundwater was less than 5 mg/L and was considerably below the Vietnamese water standard for drinking use (10 mg/L) in the three communes. By contrast, the ammonium-N concentration was determined to be over 0.59 mg/L and far exceeded the Vietnamese water standard for drinking use of 0.039 mg/L.…”

“…In each commune, crop cultivation is carried out in a wide area, and many farm households also raise livestock. The general agricultural situation in the Red River Delta was outlined in a previous paper (Kurosawa et al 2004). Figure 1 reproduces the locations of the three communes, all situated within Table 1 shows the brief description of those communes: land elevation is 9 -10 m, 5 -5.5 m, and 3 -3.5 m, respectively, for Thanh Xuan, Phu Dong, and Phu Lam.…”

“…The average amounts of fertilizer-N applied to individual crop in each commune in 2002 are shown in Table 2, quoted from Kurosawa et al (2004). The winter crop in parentheses indicates the most commonly cultivated crop in the respective communes.…”

“…Surface and groundwater quality for the inorganic-N concentrations in October 2002 was monitored in three communes near Hanoi in the Red River Delta, where farmers cultivate three crops each year and applied a total of around 400 kg N/ha in the year of 2002. The 400-kg total includes 90-125 kg each for two rice crops and about 190 kg for a crop of maize (Kurosawa et al 2004). Here, commune refers to a fundamental administrative unit in Vietnam, usually consisting of 5-10 villages.…”