Abstract:

【Objective】 Huimin County in Shandong Province is a typical intensive vegetable planting area in North China Plain. The concentration of nitrate in shallow ground water in this county was analyzed and potential source of nitrate was tracked.【Method】 Multi-point collection of samples of soil, fertilizer and underground water in the vegetable planting area was made; then stable isotope technology was used to track the potential source of nitrite in groundwater. 【Result】 The result showed that the concentration of nitrate ranged from 25.3 to 279.6 mg?L-, with an average of 121.6 mg?L-1 which was about 600 times as much as that in deep well water in field. The highest concentration of nitrate in ground water was in cucumber patch, followed by celery-chili patch, chili patch, celery-cucumber patch and celery-tomato patch. In the study areas, the concentration range of δ15 N in the soil was from 1.96‰ to 7.38‰ and the concentration of chemical fertilizer (such as urea and compound fertilizer) and dung (such as farmyard manure and stable manure) ranged from 0.2‰ to 0.6‰ and from 7.3‰ to 16.87‰, respectively. The δ15 N value of ground water sample ranged from -0.01‰ to 15.91‰ with an average of 6.75‰ ±3.15‰. The value of δ15 N in ground water was not accordingly increased with the decrease of concentration of NO3-N. The results also showed that the denitrification of ground water was relatively weak in the study areas.【Conclusion】 The nitrite contamination of shallow ground water in vegetable greenhouses is extremely serious, and it is seriously influenced by humanity. The main source of nitrate is soil organic nitrogen, and the minor source is animal dung.

Key words: intensification')">intensification, Huimin County, Shandong Province, ground water, nitrate, δ15N