Mean annual precipitation chemistry at west point newyork

Weekly composite samples of precipitation (wet-only deposition) have been collected at West Point since June 1979 as one of the NADP monitoring stations. The site initially occupied (NY51) was terminated in October 1984 for logistical reasons, while a second station (NY99), about one km away, was initiated in September 1983. Here we discuss a few aspects of mean annual precipitation chemistry from West Point (NY99) for the period from 198499. Chemical data from weekly samples have been aggregated by NADP as amount-weighted concentrations for various periods. Values compiled in Table 7.1 are calendar year amount-weighted means. Note that since the primary data are from weekly composites (samples collected on Tuesdays), annual means can represent periods a few days less than or greater than 365 days. Mean annual precipitation amount for this sixteen-year period was 128 cm yr-1.

The most abundant anions for the period 198499, in rank order (|Eq l-1), were: SO42- (44), NO3-(24) and Cl- (12). The most abundant cations in rank order (|Eq l-1) were: H+ (49), NH4+ (12) and Na+ (8). There appear to have been systematic decreases in mean annual [SO42-], [NO3-] and [H+ ] over this period, indicating that total annual

Table 7.1.

National Atmospheric Deposition Program data from NY99, West Point, NY0

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