LEADER 00000nam  2200421   4500 
001    AAI3412979 
005    20110926104350.5 
008    110926s2010    ||||||||||||||||| ||eng d 
020    9781124126449 
035    (UMI)AAI3412979 
040    UMI|cUMI 
100 1  Yang, Qiang 
245 10 Arsenic in fractured bedrock aquifers in greater Augusta, 
       Maine, USA 
300    157 p 
500    Source: Dissertation Abstracts International, Volume: 71-
       09, Section: B, page: 5350 
500    Adviser: Yan Zheng 
502    Thesis (Ph.D.)--City University of New York, 2010 
520    Thirty one percent of private well water samples (n=790) 
       collected in 2006 from fractured meta-sedimentary bedrock 
       aquifers in greater Augusta, Maine were found to contain >
       10 mug/L of arsenic. An additional 331 samples were 
       obtained in 2007 from 4 towns representing low to high 
       arsenic occurrence. The spatial pattern of groundwater 
       arsenic distribution resembled the bedrock map. Arsenic 
       exceedance rate was highest in the Silurian pelite and 
       sandstone/limestone (∼40%), and differed significantly
       from those in the Silurian-Ordovician sandstone (24%), the
       Devonian granite (15%) and the Ordovician-Cambrian 
       volcanic rocks (9%). This was confirmed in the 4 cluster 
       areas with a greater sampling density. Thus, bedrock 
       geology is associated with arsenic occurrence in fractured
       bedrock aquifers of the study area at scales of 100-101 km
520    The elevated arsenic concentrations were associated with 
       high pH, fluoride, molybdenum, and low dissolved oxygen, 
       nitrate, chloride. A logistic regression model showed that
       bedrock geology, soil arsenic content, pH, dissolved 
       oxygen, nitrate and sulfate played important roles on 
       groundwater arsenic concentrations. Water geochemistry 
       suggested a complex mobilization mechanism of oxidation of
       arsenic-rich sulfide, adsorption on iron minerals, pH-
       dependent desorption of arsenic from iron minerals with 
       calcite dissolution along the groundwater flow path 
520    Geophysical logging and water sampling from bore hole and 
       specific fractures in two wells in Manchester, Maine found
       that dissolved arsenic concentrations increased when the 
       bore hole water was replaced by the water with high 
       dissolved arsenic coming primarily from high yielding 
       fractures near the bottom of bore hole in response to 
       pumping. Iron particulate precipitates were common and 
       found to be enriched in arsenic. Laboratory experiment 
       suggested that in the bore hole arsenic was mainly settled
       with iron enriched particles, probably amorphous ferric 
       oxyhydroxides, with possibly minor adsorption on the iron 
520    The association of arsenic distributions in groundwater, 
       soil and stream sediment from national data sets examined 
       by logistic regression models suggested that soil and 
       stream sediment arsenic distributions had significant 
       effects on groundwater arsenic occurrence at the national 
       scale. Stronger correlations were found in Florida, New 
       England and Nevada at regional scales and in greater 
       Augusta, Maine at the local scale with higher sampling 
590    School code: 0046 
650  4 Environmental Geology 
650  4 Environmental Sciences 
650  4 Geochemistry 
690    0407 
690    0768 
690    0996 
710 2  City University of New York.|bEarth & Environmental 
773 0  |tDissertation Abstracts International|g71-09B 
856 40 |uhttp://pqdd.sinica.edu.tw/twdaoapp/servlet/