Digital Commons Network^™

Techniques For Enumerating Protozoa In Saturated Subsurface Sediments, Amoret L. Bunn

Doctoral Dissertations

Three techniques were investigated for the enumeration of small (2-5 $\mu$m in diameter) flagellates and amoebae in sediments collected within and outside of a wastewater contaminated ground water plume at the U.S. Geological Survey Toxic Substances Hydrology Research site, located on Cape Cod, MA. An epifluorescent direct count technique was developed to enumerate DAPI stained protozoa on polycarbonate membrane filters. These estimates were compared to the those from the Darbyshire liquid media MPN and Singh solid media MPN techniques. In Fall 1991, sediment samples were collected to investigated the variability of the hold time of cores, total and encysted protozoan …

Isotope Geochemistry And Paleobiology Of The Devils Lake Basin, North Dakota, Robert Mulvihill Lent

Doctoral Dissertations

Devils Lake is located in one of the largest closed basins in the northern prairies. Water and sediment samples were collected to characterize present and past hydrologic and climatic conditions in the basin.

Precipitation in North Dakota exhibits a wide range of stable isotopic compositions. Precipitation samples clustered along two segments of the meteoric water line, illustrating the strong seasonal component of precipitation. Low deuterium excess in summer precipitation was indicative of higher relative humidity of the air masses originating over the Gulf of Mexico. High deuterium excess in winter precipitation is similar to the values found at Canadian stations …