Record Details
An examination of the form and variability of manganese oxide in Columbia River suspended material
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | An examination of the form and variability of manganese oxide in Columbia River suspended material |
| Names |
Covert, Paul Allister
(creator) Prahl, Fredrick G. (advisor) |
| Date Issued | 2001-05-07 (iso8601) |
| Note | Graduation date: 2002 |
| Abstract | Suspended particulate matter (SPM) in the Columbia River is a mixture of particles of several origins having varying physical and biogeochemical properties. The relative abundances of these freshwater particles changes with season and apparently also with tide. Prior investigation has quantified seasonal variation of organic material in both the Columbia and Willamette rivers. In this investigation, seasonal variability in the abundace of manganese in the mineral fraction (Mn/Al) is confirmed in both rivers. Mn/Al hovers around 0.01 (crustal average = 0.011, Whetten et al., 1969) during the winter and early spring, rising in the spring and summer to 0.04 and 0.06 in the Columbia and Willamette Rivers, respectively. Results from particle settling experiments and electron microprobe photos of SPM indicate that seasonal Mn/Al variability is a result of addition of Mn-oxides to SPM in the summer months, and that these oxides exist as discrete, slow settling particles. A short-term (12 hour) variability of Mn/Al, as well as Chl a/POC, is observed at mid-depth in the Columbia River. Owen Tube particle settling experiments revealed that with respect to geochemical properties, SPM could be divided into two settling classes: slow (<0.11 cm/s) and fast (>0.11 cm/s). Particles in the slow settling class were typically enriched in Mn and Chl a , while fast settling particles were more characteristic of detrital material. One consequence of this geochemical separation is that it leads to differential particle settling and resuspension in the tidal freshwater portions of the river, resulting in the observed 12-hour variability of SPM character. Such variability could have further reaching consequences with regard to chemical transport and dispersal. |
| Genre | Thesis |
| Topic | Manganese oxide -- Columbia River |
| Identifier | http://hdl.handle.net/1957/10684 |
