Stable Isotopes of Sulphur and Oxygen in Forested Catchments: Insight from New Techniques into Sulphur Cycling and Dissolved Organic Matter Alteration
MetadataShow full item record
Dissolved organic matter (DOM) is present in all forested catchments and can be important in binding metals, absorbing UV, and the transport of nutrients (C, N, S, P). DOM is extremely heterogeneous in time and space, making it difficult to characterize. New techniques have been developed to determine δ34S and δ18O in DOM. These techniques have been applied to samples from Harp and Plastic Lake catchments (45º23'N, 79º 08'W, 45º11'N, 78º 50'W) in order to obtain information about sources and sinks of DOM within forested catchments on the Canadian Shield. In conjunction with sulphate and DOC concentrations, this new data provides valuable insight into sulphur cycling and DOM alteration within these catchments. Data generated for δ34S-DOM and δ18O-DOM appears to be the first data reported in the literature for DOM. The inorganic (δ34S-SO42-) and organic S (δ34S-DOM) differs by environment in both catchments. The range of δ34S-SO42- is between 3. 3‰ and 10. 3‰, and the range of δ34S-DOM is from 3. 4‰ to 8. 7‰. Sulphate in the Harp Lake catchment in most samples is subject to some sort of cycling within the watershed, since δ34S-SO42- differs from precipitation. In the Harp Lake catchment, upland δ34S-SO42- is influenced by historical precipitation. The δ34S-DOM is derived from leaching and microbial activity of DOM from organic horizons in the soil. The δ34S-SO42- and δ34S-DOM of wetland streams is extremely variable, controlled by hydrology. The δ34S-SO42- provides information on oxidation-reduction dynamics in the wetland, and δ34S-DOM provides information about sources of DOS in the wetland. The δ34S-SO42- and δ34S-DOM are possibly related in Harp Lake. Mineralization of DOS as evidenced by δ34S-DOM and DOS concentrations could be a small input of SO42- into Harp Lake. It is possible δ18O-DOM could be an indicator of DOM alteration. The range of δ18O-DOM is between 8. 2‰ and 14. 4‰. The δ18O-DOM in the Harp Lake catchment is highly correlated with relative molecular weight, which has been shown to decrease with increasing alteration. Wetland streams show the largest range in δ18O-DOM, while uplands, groundwater, and Harp Lake are the least varied. The highest δ18O-DOM values are from sources of DOM such as leaf leachates (representative of forest floor litter) and wetlands. The most depleted samples are from groundwater and Harp Lake which typically contain highly altered DOM. The δ34S-DOM and δ18O-DOM can provide valuable information on sources of DOM and DOM alteration within the catchment. The δ18O-DOM could also allow the separation of autochthonous and allochthonous DOM in lakes.
Cite this work
Stefan Humphries (2003). Stable Isotopes of Sulphur and Oxygen in Forested Catchments: Insight from New Techniques into Sulphur Cycling and Dissolved Organic Matter Alteration. UWSpace. http://hdl.handle.net/10012/1270
Showing items related by title, author, creator and subject.
Iravani, Amir (University of Waterloo, 2011-09-02)The reduction of sulphur in transportation fuel has gained significant importance as the regulatory agencies worldwide react to air quality concerns and the impact of sulphur oxides on the environment. The overall objective ...
Lim, Lucas (University of Waterloo, 2016-12-14)In recent years we have seen an enormous increase in electronic device capabilities as users demand new and improved features in a smaller form factor. As a result, the power demands of these electronics are increasing at ...
Ruthart, Ryan (University of Waterloo, 2013-03-13)The Marathon PGM-Cu deposit is hosted by the Coldwell alkaline complex, which consists predominantly of gabbro and syenite and was emplaced at 1108 Ma as part of the Mid-Continent Rift System. Mineralization at the Marathon ...