This study was directed towards the development of rigorous, systematic, computer-assisted statistical procedures for the interpretation of quantitative and qualitative data commonly encountered in practical exploration-oriented surveys. A suite of data analysis tools were developed to evaluate the quality of geochemical data sets, to investigate the value and utilization of categorical field data, and to recognize and rank anomalous samples. Data obtained from regional stream sediment surveys as undertaken by the British Columbia Ministry of Energy, Mines and Petroleum Resources in southern British Columbia were examined as a case history. A procedure based on a statistical analysis of field-site duplicates was developed to evaluate the quality of regional geochemical silt data. The technique determines: (1) whether differences in metal concentrations between sample sites reflect a real trend related to geological and geochemical features and not merely a consequence of sampling and analytical error, and (2) absolute precision estimates at any particular accumulation across a metal's concentration range. Results for metals Zn, Cu, Ni, Co, Fe and Mn indicated that combined variability due to local and procedural error averaged less than 5% of the total error and that precision estimates at the 95th percentile concentration value averaged less than 6.0%. Results presented indicate duplicates are more in accord with splits of individual samples (analytical duplicates) rather than separate field-site duplicates. This type of systematic approach provides a basis for interpreting geochemical trends within the survey area, while simultaneously allowing evaluation of the method of sampling and laboratory analysis. A procedure utilizing Duncan's Multiple Range Test examined the relationships between metal concentrations and class-interval and categorical observations of the drainage catchment, sample site and sediment sample. Results show that, many field observations can be systematically related to metal content of drainage sediments. Some elements are more susceptible than others to environmental factors and some factors influence few or many elements. For example, in sediments derived from granites there are significant relationships between bank type and concentration of 8 elements (Zn, Cu, Ni, Pb, Co, Fe, Mn and Hg). In contrast, the texture of these sediments, using estimates of fines contents as an index, did not significantly affect the concentration of any of the elements studied. In general, results indicate that groups of environmental factors acting collectively are more important than any single factor in determining background metal contents of drainage sediments. A procedure utilizing both a graphical and multiple regression approach was developed to identify and characterize anomalous samples. The procedure determines multivariate models based on background metal values which are used to describe very general geochemical relations of no interest for prospecting purposes. These models are then applied to sample subsets selected on the basis of factor/s known to strongly influence geochemical results. Individual samples are characterized after comparisons with relevant determined threshold levels and background multielemenmodels. One hundred and fifteen anomalous samples for zinc from seven provenance groups draining 1259 sample sites were identified and characterized by this procedure. Forty three of these samples had zinc concentrations greater than its calculated provenance threshold, while 72 of these anomalous samples were identified solely because their individual metal associations were significantly different than their provenance multivariate background model. The method provides a means to reduce the effects of background variations while simultaneously identifying and characterizing anomalous samples. The data analysis tools described here allow extraction of useful information from regional geochemical data, and as a result provide and effective means of defining problems of geological interest that warrant further investigation. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

No description available.

Thesis (M.S. in environmental engineering)--Washington State University, December 2009. / Title from PDF title page (viewed on Jan. 14, 2010). "Department of Civil and Environmental Engineering." Includes bibliographical references (p. 41-42).

Thesis (M.S.)--Ball State University, 2009. / Title from PDF t.p. (viewed on Feb. 08, 2010). Includes bibliographical references (p. 37-38).

Fluvial sediments, as a product of erosion, are associated with a wide range of environmental issues. In particular, sediment quality and its origin represent one of the focuses of contemporary water management. This study examines the characteristics and provenance of fine bed sediments in a humid sub-tropical macro scale catchment – the East River basin in South China. Sampling was carried out in the dry seasons of 2007 – 2008, following the protocol of USGS OFR 94-458. Sample density was one per 200 km2. The particle size, grain roundness, geochemistry, mineral magnetic parameters, clay mineralogy, along with C and N, were determined for the <2-mm and <63-μm size fractions. A geochemical baseline, along with its spatial distribution, was developed for the East River by using a statistical approach. The geochemistry was generally consistent with upper crustal abundance of China and with world average suspended matter concentrations. Some analytes, such as arsenic and sulphur, were elevated and were found to associate with anthropogenic activities, whilst rare earth elements (REEs) were affiliated with the igneous geology in the study basin. These associations were also detected from exploratory factor analysis, as well as the longitudinal profiles developed for the main stem of the river. Sediment source apportionment was carried out by utilizing the fingerprinting procedure on three geologic groups. Results indicate that provenance of sediments in the East River was more or less uniform among the different geologies, but the accuracy of the apportionment has been compromised by the relatively high within-group variance of the source categories. Results suggested that source apportionment was only viable by utilizing the <63-μm fraction, and grain size correction factor shall not be employed on samples with a high granulometric variance. REE represents a robust signature to indicate provenance from igneous lithology, in particular, granites. / published_or_final_version / Geography / Doctoral / Doctor of Philosophy

No description available.

This project was designed to assess the ability of natural sediment microbial communities and single species microbial populations to preferentially utilize inorganic forms of nitrogen (ammonium, NH4-N, and nitrate, NO3-N, specifically). The first chapter addressed two primary questions: 1) Do sediment microbial communities preferentially assimilate NH4-N or NO3-N?; and, 2) Does preferential uptake of nitrogen change with increased NH4-N or NO3-N availability? The second chapter furthered these analyses by assessing shifts in microbial nitrogen assimilation in response to sustained nitrogen enrichments. Primary questions addressed were: 1) Are microbial communities able to adapt to nitrogen enrichment and preferentially utilize a more available source?; and, 2) Are initial microbial responses to nitrogen enrichment different from sustained responses? Questions were addressed with in vitro laboratory experiments quantifying microbial activity. Overall, microbial community activity changed in response to the form of nitrogen available, enrichment type, and duration of exposure. Data demonstrate sediment microbial communities in the Midwestern US may prefer NO3-N over other forms of nitrogen. However, microbial communities became saturated with NO3-N with increases in concentrations >0.75 mg NO3-N/L. Microbial communities were able to adapt to higher nitrogen concentration and increase rates of assimilation for both NH4-N and NO3-N. Thus, microbial communities are robust in response to nitrogen increases in and ecosystem, even in high nitrogen environments like the Midwestern US. / Preferential uptake of available nitrogen forms -- Adaptive uptake in microbial communities. / Department of Biology

Thesis (M.S. - Renewable Natural Resources)--University of Arizona, 1986. / Includes bibliographical references (leaves 79-83).

Thesis (M.S.)--University of Tennessee, Knoxville, 2008. / Title from title page screen (viewed on Mar. 11, 2009). Thesis advisor: John S. Schwartz. Vita. Includes bibliographical references.

Thesis (M.A.)--University of Missouri-Columbia, 2008. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on September 12, 2008) Vita. Includes bibliographical references.