Abstract:

To reveal the spatial distribution laws of nitrate nitrogen ($NO_{3}^{-}$-N) concentration in the upstream of Miyun reservoir and its main influencing factors, we collected water samples throughout the whole watershed in the upstream of Miyun reservoir, and investigated the data on human activities such as population, land use types and fertilizer application, determined the concentration of $NO_{3}^{-}$-N by a flow injection analyzer. The results showed that: the concentration of $NO_{3}^{-}$-N in Chaohe River in the eastern upstream of Miyun reservoir was higher than that in the Baihe River in the western upstream; the spatial distribution pattern of $NO_{3}^{-}$-N concentration was closely related with human activities; the concentration of $NO_{3}^{-}$-N tended to rise in the way of livestock farms, settlements and farmland, while it tended to decrease in the way of dams, canyons and forests; so, the rank of $NO_{3}^{-}$-N concentration in the stream passing through different land uses was: livestock farm> settlements>farmland>dams>canyons>forests. The concentration of $NO_{3}^{-}$-N was positively correlated with population density, proportion of cultivated land, and fertilizer nitrogen application.

Key words: Nitrate Nitrogen, Spatial Distribution, Upstream, Miyun Reservior Watershed, Population Density, Proportion of Cultivated Land