The Occurrence of Thiobacillus ferrooxidans and Arsenic in Subarctic Streams Affected by Gold-Mine Drainage

Thirty-five streams in gold-mining regions between Rampart, Alaska, and Dawson City, Yukon Territory, were sampled to determine dissolved arsenic concentrations, and numbers of the acidophilic iron- and sulfur-oxidizing bacterium Thiobacillus ferrooidans. The pH of the streams varied from 6.3 to 8.6 and the streams were nearly saturated with dissolved oxygen. T. ferrooxidans was found in eight of nine streams affected by gold-mine drainage and in only one of 26 streams not affected by gold-mine drainage. Some of the streams affected by gold-mine drainage near Fairbanks, Alaska, occasionally contained levels of dissolved arsenic above 50 parts per billion. The recognition that T. ferrooxidans is associated with gold-mine material and that the heavy metal arsenic exists in streams affected by gold-mine wastes is important for understanding the environmental affects of mining activity on subarctic streams.Key words: arsenic, gold mines, heavy metals, pyrite, Thiobacillus ferrooxidansMots clés: arsenic, mines d'or, métaux lourds, pyrite, Thiobacillus ferrooxidan

Microbial ecology of Thiobacillus ferrooxidans

FINAL TECHNICAL REPORT TO U.S. DEPARTMENT OF THE INTERIOR Geological Survey Washington. D.C.The contents of this report were developed in part under a grant from the Department of the Interior, U.S. Geological Survey. Grant number 14-08-0001-61313

Effects of Catalyst Pretreatment on Carbon Nanotube Synthesis from Methane Using Thin Stainless-Steel Foil as Catalyst by Chemical Vapor Deposition Method

Synthesis of carbon nanotubes (CNTs) was carried out using methane as a carbon source via the chemical vapor deposition (CVD) method. A thin stainless-steel foil was used as catalyst for CNT growth. Our results revealed that pretreatment step of the stainless-steel foil as a catalyst plays an important role in CNT formation. In our experiments, a catalyst pretreatment temperature of 850 °C or 950 °C was found to facilitate the creation of Fe- and Cr-rich particles are active sites on the foil surface, leading to CNT formation. It is noted that the size of metallic particles after pretreatment is closely related to the diameter of the synthesized CNTs. It is interesting that a shorter catalyst pretreatment brings the growth of semiconducting typed CNTs while a longer pretreatment creates metallic CNTs. This finding might lead to a process for improving the quality of CNTs grown on steel foil as catalyst