APPORTIONMENT OF SULFUR-OXIDES AT CANYONLANDS DURING THE WINTER OF 1990 .3. SOURCE APPORTIONMENT OF SOX AND SULFATE AND THE CONVERSION OF SO2 TO SULFATE IN THE GREEN-RIVER BASIN

During January-March of 1990 a study was conducted to determine the so urces of sulfur oxide emissions present in the Canyonlands area in Uta h. Samples were collected at the Island-in-the-Sky visitors center in Canyonlands National Park and at several sites circling the park to ch aracterize the chemical composition of air masses influencing the rece ptor sites from various geographical regions. The results of the sampl ing program and the identified chemical fingerprints of the sources th at can impact the Canyonlands receptor site have been given in the fir st two papers in a series of three papers. In this paper are presented the results of chemical mass balance source apportionment of the SOx present at Canyonlands, Green River, Bullfrog Marina and Edge of the C edars, Utah, using the chemical composition and source fingerprint dat a given in the preceding papers. The results indicate that the presenc e of sulfur oxides at the Canyonlands area is a regional problem not d ominated by a single source. The contributions to SOx at Canyonlands d uring the 21 days included in the source apportionment analyses includ ed sources to the southwest (37%), south and southeast (20%), north an d northeast (19%), and northwest (23%). At the Edge of the Cedars Stat e Park to the southeast of Canyonlands, sources from the southeast con tributed 51% of the observed SOx. At Bullfrog Marina in the Lake Powel l National Recreation Area, southwest of Canyonlands, sources to the s outhwest were responsible for 81% of the SOx present. At Green River, to the north of Canyonlands, the contribution of sources to the north and northeast were reduced (10%) because the major transport path of s ources from these directions was the movement of emission from northwe stern Colorado down the Colorado River drainage and south of Green Riv er. The apportionment of sulfate at Canyonlands has been estimated fro m a combination of the chemical mass balance SOx source apportionment results, the measured concentrations of SO2 and particulate sulfate, a nd meteorological data. This analysis indicates that, while the main s ource of SOx at Canyonlands is from emissions to the southwest, the ma in source of sulfate is from SOx emissions originating from the southe ast of Canyonlands.