Variation of wet deposition chemistry in Sequoia National Park, California

Sequoia National Park has monitored wet deposition chemistry in conjunction with the National Atmospheric Deposition Program and National Trends Network (NADP/NTN), on a weekly basis since July, 1980. Annual deposition of H, NO₃ and SO₄ (0.045, 3.6, and 3.9 kg ha⁻¹ a⁻¹, respectively) is relatively low compared to that measured in the eastern United States, or in the urban Los Angeles and San Francisco areas. Weekly ion concentrations are highly variable. Maximum concentrations of 324,162, and 156 μeq ol⁻¹ of H, NO₃ and SO₄ have been recorded for one low volume summer storm (1.4 mm). Summer concentrations of NO₃ and SO₄ average two and five times higher, respectively, than concentrations reported for remote areas in the world. There is considerable variability in the ionic concentration of low volume samples, and much less variability in moderate and high volume samples.