The suitability of constructed wetland （CW） in were developed. The first experiment focused on zinc and treating acid mine drainage （AMD） was investigated. Two experiments nutrients removals. Four units of horizon...The suitability of constructed wetland （CW） in were developed. The first experiment focused on zinc and treating acid mine drainage （AMD） was investigated. Two experiments nutrients removals. Four units of horizontal subsurface flow CWs were used, two cells planted with Phragmites mauritianus, one cell with Typha domingensis and one cell unplanted （control cell）. Artificial high concentrated AMD was used. It was mixed with domestic wastewater from the anaerobic waste stabilization pond （WSP） to ensure nutrient supply to the plants in the CW cells. The second experiment tested the tolerance of locally available macrophytes to the harsh acidic environment, while providing required condition for treatment of AMD. To accomplish this, another set of four CW cells planted with different types of macrophytes, namely Typha domingensis, Phragmites mauritianus, Vetiver grass and Papyrus, were used thereby subjecting them to varying acid concentration ofpH of 3.5, 3.0, 2.9 and 2.7. The study demonstrated adequate zinc removal from AMD which is related to sulphide precipitation. A CW cell planted with Typha domingensis showed higher zinc removal （80%-84%） compared to other cells. Different macrophytes showed different nutrient removal efficiency, but overall, for the type of wetland plants studied, phosphorous removal increased with decreasing pH while nitrogen removal behaved quite opposite. On the other hand, Typha domingensis, Phragmites mauritianus and Papyrus were observed to tolerate high acidity as low pH as 2.7 and therefore are suitable macrophytes for AMD treatment with CW.展开更多
Seismicity in northern Arizona is concentrated in a northwest-southeast trending belt that stretches from the Utah border south to the edge of the Colorado Plateau. Located within this NASB （Northern Arizona Seismic ...Seismicity in northern Arizona is concentrated in a northwest-southeast trending belt that stretches from the Utah border south to the edge of the Colorado Plateau. Located within this NASB （Northern Arizona Seismic Belt） is the San Francisco volcanic field, classified by the United States Geological Survey as potentially active. The last volcanic event in the field was located at Sunset Crater and occurred less than 1,000 years ago. Eruption intervals in the volcanic field are of the same order of length of time. Seismic monitoring of the volcanic field area has improved greatly since 1985 with the establishment of new network seismic stations. This has allowed for a lowered threshold of detection of seismic events and improved location capabilities. As an example of the result of this improved ability to locate smaller tremors, two swarms have been identified in the field, the 2009 Halloween swarm near Sunset Crater volcano and the 2011 swarm near Flagstaff, the largest urban community in northern Arizona.展开更多
文摘The suitability of constructed wetland （CW） in were developed. The first experiment focused on zinc and treating acid mine drainage （AMD） was investigated. Two experiments nutrients removals. Four units of horizontal subsurface flow CWs were used, two cells planted with Phragmites mauritianus, one cell with Typha domingensis and one cell unplanted （control cell）. Artificial high concentrated AMD was used. It was mixed with domestic wastewater from the anaerobic waste stabilization pond （WSP） to ensure nutrient supply to the plants in the CW cells. The second experiment tested the tolerance of locally available macrophytes to the harsh acidic environment, while providing required condition for treatment of AMD. To accomplish this, another set of four CW cells planted with different types of macrophytes, namely Typha domingensis, Phragmites mauritianus, Vetiver grass and Papyrus, were used thereby subjecting them to varying acid concentration ofpH of 3.5, 3.0, 2.9 and 2.7. The study demonstrated adequate zinc removal from AMD which is related to sulphide precipitation. A CW cell planted with Typha domingensis showed higher zinc removal （80%-84%） compared to other cells. Different macrophytes showed different nutrient removal efficiency, but overall, for the type of wetland plants studied, phosphorous removal increased with decreasing pH while nitrogen removal behaved quite opposite. On the other hand, Typha domingensis, Phragmites mauritianus and Papyrus were observed to tolerate high acidity as low pH as 2.7 and therefore are suitable macrophytes for AMD treatment with CW.
文摘Seismicity in northern Arizona is concentrated in a northwest-southeast trending belt that stretches from the Utah border south to the edge of the Colorado Plateau. Located within this NASB （Northern Arizona Seismic Belt） is the San Francisco volcanic field, classified by the United States Geological Survey as potentially active. The last volcanic event in the field was located at Sunset Crater and occurred less than 1,000 years ago. Eruption intervals in the volcanic field are of the same order of length of time. Seismic monitoring of the volcanic field area has improved greatly since 1985 with the establishment of new network seismic stations. This has allowed for a lowered threshold of detection of seismic events and improved location capabilities. As an example of the result of this improved ability to locate smaller tremors, two swarms have been identified in the field, the 2009 Halloween swarm near Sunset Crater volcano and the 2011 swarm near Flagstaff, the largest urban community in northern Arizona.
