Baseline geochemical data for stream sediment and surface water

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Jenis Berkas: PDF/Adobe Acrobat - Versi HTMLspectrophotometry following the method of O'Leary and Meier (1996). ... Co, Cr, Cu, Fe, Ga, Ge, La, Mg, Mn, Mo, Na, Nb, Ni, P, Pb, Pd, Pt, Sb, Sc, Sn, Sr, Th, Ti, V, W,. Y, Zn, and Zr. This method is designated ES in Table 2 and in the data ... This is particularly true for the major elements Al, Ca, Fe, K, Mg, ...

INTRODUCTION
During a 3-week period in the summer of 1996, the U.S. Geological Survey conducted a reconnaissance baseline geochemical study in central Idaho. Areas covered include Panther Creek, the Middle Fork of the Salmon River from Boundary Creek to the mouth, and the Main
Salmon River from North Fork to Corn Creek (Fig. 1). Stream sediment samples were collected
at all sample sites. Filtered and unfiltered stream water samples were collected at most sample
sites. The purpose of the baseline study was to establish a “geochemical snapshot” of the area,
as a datum for monitoring future change in the geochemical landscape, whether natural or human-induced. Events that could change the geochemical landscape include, but are not limited to, mining, flood, landslide, wildfire, or resource extraction activities. In the summer of 2000, there were numerous large wildfires in central Idaho. In particular, the Clear Creek (206,000 acres; 83,370 hectares), Little Pistol (74,000 acres; 29,950 hectares), and Shellrock (64,000 acres; 25,900 hectares) fires swept across much of the area that was sampled. Thus, these data represent a pre-fire baseline geochemical dataset. A 2001 post-fire study is planned and will involve re-sampling of the pre-fire baseline sites, to allow for pre- and post-fire comparison. Sampling was conducted from July 8-28, 1996. Weather during this period was warm and precipitation sparse. Only one rain event occurred during the sampling period—a brief rain storm on the evening of July 16, with about ¼” (0.64 cm) of total precipitation. River levels were lower than normal for this time of year because of lower-than-normal precipitation during
the previous winter and spring. The study area lies within the Salmon River Mountains, and much of the area— particularly along the Middle Fork of the Salmon River—lies within the Frank Church-River of No Return Wilderness (Fig. 1). Topographic relief is high. Peaks at the heads of drainages commonly have elevations above 9000 ft (2740 m), while river-level elevations are typically several thousand feet lower, ranging from around 5700 ft (1740 m) at Boundary Creek on the Middle Fork of the Salmon River, to less than 3000 ft (914 m) at Corn Creek on the Main
Salmon River. Terrain ranges from rugged, steep peaks, ridges, and cirques at higher elevations,
through tree-covered mountains and meadows at intermediate elevations, to steep, narrow, heavily vegetated canyons at lower elevations. Climatic conditions vary from warm summer days with frequent thunderstorms to cold winter days with heavy snowfall accumulations. Access to the Panther Creek basin is by U.S. Forest Service gravel roads 030 from North Fork, Idaho, and 055, which runs along Panther Creek. Access to the Main Salmon River from North Fork to Corn Creek is by U.S. Highway 93 and U.S. Forest Service gravel road 030, which runs along the Main Salmon, ending at Corn Creek, and by raft or jet boat. Access to the Middle Fork of the Salmon River is exclusively by oar-powered raft or pack trail.