GEOMICROBIOLOGICAL STUDIES OF SALINE LAKES ON THE TIBETAN PLATEAU, NW CHINA: LINKING GEOLOGICAL AND MICROBIAL PROCESSES
Lakes constitute an important part of the global ecosystem as habitats in these environments play an important role in biogeochemical cycles of life-essential elements. The cycles of carbon, nitrogen and sulfur in these ecosystems are intimately linked to global phenomena such as climate change. Microorganisms are at the base of the food chain in these environments and drive the cycling of carbon and nitrogen in water columns and the sediments. Despite many studies on microbial ecology of lake ecosystems, significant gaps exist in our knowledge of how microbial and geological processes interact with each other. In this dissertation, I have studied the ecology and biogeochemistry of lakes on the Tibetan Plateau, NW China. The Tibetan lakes are pristine and stable with multiple environmental gradients (among which are salinity, pH, and ammonia concentration). These characteristics allow an assessment of mutual interactions of microorganisms and geochemical conditions in these lakes. Two lakes were chosen for this project: Lake Chaka and Qinghai Lake. These two lakes have contrasting salinity and pH: slightly saline (12 g/L) and alkaline (9.3) for Qinghai Lake and hypersaline (325 g/L) but neutral pH (7.4) for Chaka Lake. We have taken an integrated approach combining geochemistry, molecular phylogeny (both DNA and RNA based, both 16S rRNA and amoA gene), quantitative PCR (total Bacteria, Archaea, total crenarchaeota, AOA, and AOB), and cultivation and isolation. Both lake water and sediments have been analyzed. The results are divided into four chapters and they are summarized below. In addition, I also studied microbial communities and functions in sediments from South China Sea, a potential site for gas hydrate deposits. This work was done as extra add-on to the microbial ecology studies in Titeban lakes.
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:geomicrobiology tibetan plateau saline lakes
Date of Publication:01/01/2007