Thesis (Ph.D.)--York University, 2005. Graduate Programme in Geography. / Typescript. Includes bibliographical references. Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR19797

Thesis (M.S.)--Ohio University, June, 2008. / Title from PDF t.p. Includes bibliographical references.

Critical zone science seeks to develop mechanistic theories that describe critical zone structure, function, and long-term evolution. One postulate is that hydrogeochemical controls on critical zone evolution can be inferred from solute discharges measured down-gradient of reactive flow paths. These flow paths have variable lengths, interfacial compositions, and residence times, and their mixing is reflected in concentration-discharge (C-Q) relations. Motivation for this special section originates from a U.S. Critical Zone Observatories workshop that was held at the University of New Hampshire, 20-22 July 2015. The workshop focused on resolving mechanistic CZ controls over surface water chemical dynamics across the full range of lithogenic (e.g., nonhydrolyzing and hydrolyzing cations and oxyanions) and bioactive solutes (e.g., organic and inorganic forms of C, N, P, and S), including dissolved and colloidal species that may cooccur for a given element. Papers submitted to this special section on concentration-discharge relations in the critical zone include those from authors who attended the workshop, as well as others who responded to the open solicitation. Submissions were invited that utilized information pertaining to internal, integrated catchment function (relations between hydrology, biogeochemistry, and landscape structure) to help illuminate controls on observed C-Q relations.

No description available.

Thesis (M.S.)--University of Wyoming, 2008. / Title from PDF title page (viewed on August 6, 2009). Includes bibliographical references (p. 50-54).

Nutrient loading to aquatic and marine ecosystems is a topic of interest, especially as the human population continues to grow and land use changes. Here, I examined the seasonal variability and relative amounts of different forms of nitrogen (N) and phosphorous (P) from four sites at Röbäcksdalen (Umeå, Västerbotten), an area influenced by both agriculture and partial urbanization. In addition, I studied how nutrient concentration varied with discharge during snowmelt. Overall, the results show that the seasonality of nutrient concentration did not differ drastically from what is expected in more pristine boreal catchments. However, the concentrations of dissolved inorganic N (DIN) and phosphate (PO4) were elevated. Land use activities in Röbäcksdalen also appear to be influencing inorganic N inputs to streams to a greater degree than inputs of inorganic P. Comparisons with more pristine boreal streams also reveal a fundamental change in the composition of the stream N pool, with greater dominance of DIN within the catchment. This pattern is likely due to inputs of nutrients in excess of biotic demand. Lastly, the results of the concentration-discharge analysis from Röbäcksdalen indicate that hydrological forcing rather than soil processes control the supply of nutrients to these streams during snowmelt. With concentrations being high, this also indicates that a considerable increase in the flux of nutrients from the area is expected with increased discharge.

In this study an effort was made to determine by analysis the principal minerals that are dissolved in the water of the Little Wichita River.

In boreal landscapes, large quantities of dissolved organic carbon (DOC) accumulated in soils are flushed into rivers and streams during snowmelt. These inputs supply energy to aquatic microbes, affect pH, and can promote the transportation of metals to streams and rivers. However, during the spring flood, changes in stream DOC are influenced by the structure of the catchment (e.g., forest vs. wetland cover), where different solutes are stored in soils, and snowmelt hydrology. While these mechanisms have been studied extensively in ‘pristine’ boreal landscapes, the influence of agricultural and urban land use on DOC flushing during snowmelt is poorly understood in this region. To understand these influences, I measured DOC, along with pH, conductivity, and discharge, during snowmelt at three boreal streams draining agricultural and urban lands.  I analyzed chemical patterns using discharge-concentration curves that reveal whether solutes are stable (chemostatic) or change (chemodynamic) during floods. Similar to observations made in forested catchments elsewhere, DOC was chemodynamic at all sites, increasing with discharge; however, two sites did show dilution at the very highest flows. pH declined with discharge at one site, but did not change at the other two. Electrical conductivity declined (was diluted) with increasing discharge for all sites, coinciding with previous studies. These results indicate that the majority of these chemical patterns in boreal streams influenced by agriculture and urban land use are chemodynamic, either increasing or decreasing in concentration with discharge during snowmelt. However more studies are needed to further clarify if patterns human-modified catchments are consistent with models based on boreal forested catchments.

Thesis (M.S.)--Ohio University, August, 2006. / Title from PDF t.p. Includes bibliographical references.

Thesis (M.Sc. Earth and Ocean Sciences and Chemistry)--University of Waikato, 2009. / Title from PDF cover (viewed October 2, 2009). Includes bibliographical references (p. 161-170)