RELATIONSHIPS AMONG ATMOSPHERIC DEPOSITION, THROUGHFALL, AND SOIL PROPERTIES IN OAK FOREST ECOSYSTEMS

Relationships among pollutant (H+, SO42-, NO3-) deposition, throughfal l ionic fluxes, and soil properties were examined at six oak forest si tes in the southern Great Lakes region. At each site, precipitation, t hroughfall, acid soil samples were collected and chemically analyzed. Sulfate and NO3- deposition increased from southern Michigan to northe rn Ohio in both precipitation and throughfall. Throughfall H+ fluxes a lso increased between these two areas. Throughfall fluxes of H+, SO42- , NO3-, and Ca2+ were significantly related to wet pollutant depositio n. Throughfall Ca2+ and Mg2+ fluxes also tended to reflect soil cation abundance, but H+ consumption in the canopy was a major contributor t o cation fluxes at certain sites. After accounting for differences in inherent soil properties, additional variation in both surface and sub surface soil properties was statistically related to atmospheric depos ition. While topographic position and impeded drainage also may be imp licated, elevated extractable SO42-, decreased potential to adsorb SO4 2-, and lower nutrient cation saturation in the solum of the most poll uted site were consistent with pollutant deposition impacts. Results s uggest that certain oak ecosystems in the southern Great Lakes region have experienced alteration in throughfall chemistry and soil properti es as a result of elevated pollutant deposition.