As the population of the Mother Lode area grows, it is increasingly important to consider these effects during planning and development of land and groundwater resources. Oxidation of arsenian pyrite to goethite, jarosite, and copiapite causes temporary attenuation of arsenic during summer, when these secondary minerals accumulate subsequent rapid dissemination of arsenic into the aqueous environment is caused by annual winter storms. Arsenic concentration, speciation, and distribution in the Sierra Nevada foothills depend on many factors, including the lithologic sources of arsenic, climatic influences on weathering of host minerals, and geochemical characteristics of waters with which source and secondary minerals react. The total mass of arsenic in the pit lake increases coinciding with early winter rains that erode, partially dissolve, and transport arsenic-bearing salts into the pit lake. Redistribution of the arsenic occurs during summer stratification, with highest concentrations at middle depths. Jewish Voices of the California Gold Rush examines the life of California’s Jewish community through letters, diaries, memoirs, court and news reports, and photographs, as well as institutional, synagogue, and organizational records. Aqueous arsenic concentrations in the 80 m deep pit lake are up to 1000 ?g/L. California’s Jewish immigrants become founders of their own social, cultural, and religious institutions. QVC regularly celebrates this historic discovery on January 24 each year since 1988. Dewatering during excavation of the Harvard open-pit mine produced a hydrologic cone of depression that has been recovering toward the pre-mining groundwater configuration since mining ended in 1994. California Gold Rush celebrates the 174th anniversary of the gold discovery at Sutter's Mill on January 24, 1848. Reservoir waters immediately above the cores contain up to 3.5 ?g/L arsenic lake waters away from the submerged tailings typically contain less than 1 ?g/L arsenic. The pH values in sediment porewaters range from 3.7 in buried gypsum-bearing sands and tailings to 7 in the overlying lake sediments. Fine quartz tailings also contain up to 3.5 ppm mercury related to the ore processing. Overlying surface muds have less arsenic in the solid fraction but higher concentrations in porewaters (up to 500 ?g/L) than the sands. Submerged mill tailings obtained by gravity core at Don Pedro Reservoir contain arsenic up to 300 ppm in coarse sand layers. Arsenic is sorbed as a bidentate complex on goethite, and substitutes for sulfate in jarosite. Arsenic is concentrated up to 1300 ppm in fine-grained, friable iron-rich weathering products of the arsenian pyrite (goethite, jarosite, copiapite), which develop as efflorescences and crusts on weathering outcrops. ![]() ![]() Arsenic in outcrops and waste rock occurs in arsenian pyrite containing an average of 2 wt% arsenic. These environments are characterized by distinct modes of rock-water interaction that influence the local transport and fate of arsenic. This study describes arsenic concentration and speciation in three hydrogeologic settings in the southern Mother Lode Gold District: mineralized outcrops and mine waste rock (overburden) mill tailings submerged in a water reservoir and lake waters in this monomictic reservoir and in a monomictic lake developing within a recent open-pit mine. Gold mining activity in the Sierra Nevada foothills, both recently and during the California Gold Rush, has exposed arsenic-rich pyritic rocks to weathering and erosion.
0 Comments
Leave a Reply. |
AuthorSteve ArchivesCategories |