Limiting factors and microbial organometallic transformations in anaerobic subsurface environments. Final report, 1 March 1987-30 September 1989.

摘要

Microbial communities from subsurface materials were analyzed for microbial community-particle size relationships, effects of arsenic and mercury compounds on microbial community structure, and limiting factors influencing mercury volatilization under aerobic and anaerobic conditions. The microbial communities showed strong relationships to particle size and size distribution. Major differences were found in relation to aerobic and anaerobic populations and for aerobic populations between the largest and smallest fractions. Under aerobic conditions, a significant increase in low nutrient responsive microbes occurred. After exposure to four metal compounds (phenylmercuric acetate (PMA), mercuric chloride (HgCl(sub 2)), phenylarsonic acid (PAA), and sodium arsenate (Na(sub 2)AsO(sub 4))) major changes in populations occurred. Previous exposure to these metals increased the aerobic and anaerobic populations of GS-9, indicating an adaptive response. In GS-20, previous exposure to all four compounds caused a decrease in both the aerobic and anaerobic populations. The effect was most pronounced in sediments treated with PMA or HgCl(sub 2). Limiting nutritional factors for the volatilization of mercury under aerobic and anaerobic conditions were identified in control and PMA impacted samples from GS-9 and GS-20.