Based on the snowpit samples collected at the accumulation zone of Glacier No.1 at the headwaters of Urumqi River in the Tianshan Mountains from November 2004 to October 2005, nitrate (NO^-₃) concentration in snowpacks is analyzed. Seasonality is displayed for the mean NO^-₃ concentrations in snowpacks, and the concentrations are higher in the dry season (from November to March) and lower in the wet season (from April to October). At the upper section of snowpacks, the spring-formed NO^-₃ concentration peaks  are  diluted significantly in the summer, according to the elution effect; for the whole snowpacks, the NO^-₃ concentration peaks relocate downward. In the vertical profile of snowpack, a transition layer appears at a distance of 70~80 cm to superimposed ice layer; the elution effect above the transition layer is much stronger than that below, and the concentration above the layer is higher than that below. With 20%~60% loss of content during the strong elution period in the postdepositional process, the environmental information is recorded in the ice.