Atmospheric Deposition Chemistry Research Articles

Bulk and wet atmospheric deposition chemistry at pallanza (N. Italy)

The chemistry of wet only and bulk depositions collected weekly at Pallanza from May, 1984 to December, 1986 is compared and discussed in relation to the composition of dust fall. The comparison shows a very good agreement between pH values (volume weighted mean values of 4.35 and 4.36, respectively, for wet only and bulk samples) and differences between 6 and 12% for ammonium, sulphate, nitrate, and Na. For Ca, Mg, and K the difference range is 30 to 50%. The amount of precipitation over Pallanza (mean value 1951–1985,1709 mm), together with the solute concentrations in atmospheric deposition, mean that there is high bulk deposition of acidifing substances. The values found during the study period were 76, 93, 143, and 81 meq m2 yr−1 for H+, ammonium, sulphate, and nitrate, respectively.

Causes of Acidification of Four Streams on Laurel Hill in Southwestern Pennsylvania

AbstractAtmospheric deposition, soils developed from bedrock, a natural bog, gas wells, and a ski area were all investigated as possible sources of water quality degradation for four streams on Laurel Hill in southwestern Pennsylvania where fish kills have been reported since 1960. An intensive study of the chemistry of atmospheric deposition, soil leachate, and stream water and fish populations was conducted on these basins during 1980–1981 with emphasis on dormant season periods with runoff from snowmelt and rain. Although bedrock geology was found to control the natural buffering capacity of these streams, only acid precipitation could be linked to sharp drops in pH and increases in total Al concentrations observed during stormflows in the poorly buffered streams. Three poorly buffered streams exhibited drops to pH 4.4 to 4.5 and increases in total Al concentrations up to 1.5 mg/L during observed peak flows. Mineral soil leachate from the three major soil series on the basins during this time exhibited a low pH of 4.3 and mean total Al concentrations of 3.6 mg/L, indicating stream response during storms was closely linked to chemistry of soil leachate. Poorly buffered streams did not support reproducing populations of trout (Salmonidae sp.) or other fishes. In contrast, one well‐buffered stream (20 mg/L CaCO3) exhibited drops to pH 5.5 during peak flow and supported reproducing trout and sculpin (Cottus bairdi) populations. The acidification of the four streams studied was attributed to atmospheric deposition.

Acid Rain Model: Hydrologic Module

The acid rain model has been developed to simulate lake-watershed acidification processes. It provides a quantitative linkage between atmospheric deposition and lake water chemistry. The continuous simulation model is comprised of several modules including watershed hydrology, stream and lake hydraulics, canopy, snow, soil, stream and lake chemistry. The hydrology module simulates the processes of interception, throughfall, evapotranspiration, freezing and thawing of soil, and snow accumulation and melting. The model segregates the watershed horizontally into subcatchments and vertically into soil layers. Flows are routed through a layered soil profile to the streams and ultimately to the lake. Incoming precipitation and deep groundwater flow. Application of the model to Panther and Woods Lake basins in the Adirondack mountains of New York indicates the importance of flowpaths in determining lake water acidity.