Concentrations of selenium (Se), manganese (Mn), zinc (Zn), cadmium (Cd), lead
(Pb) and arsenic (As) were measured in the water column, sediment and biota, in conjunction
with selected physicochemical data, from representative wetland types at a mining site within
Salt Lake County, Utah, USA. The selected field sites included Oolitic Pond (lentic) and Lee
Creek (lotic), which are moderately contaminated brackish, alkaline aquatic wetlands
managed by a copper mining industry. These fishless wetlands are located in a geographic
region that poses risk to migratory shorebird populations from dietary Se. A spatial sampling
study demonstrated the extent of variation in total Se concentration within the wetlands. With
the exception of the sediment compartment, Se concentration did not differ significantly along
the 2-mile length of Lee Creek or within the Pond. The differences in sediment total Se
concentrations between the Creek East and West segments characterize lower Lee Creek as
having two segments distinguished by unique processes that influence the sediment Se
accumulation profiles. Se accumulation trends were observed temporally over 3-years (2000
to 2002) and over two seasons (spring and autumn). Total Se body burden in benthic
invertebrates was more clearly associated with sediment/detritus Se concentrations than with
surface water concentrations. Three invertebrate groups dominated the aquatic invertebrates
assemblage in the lotic and lentic benthos; primary consumers (Chironomidae, Diptera),
generalist feeders (Hemiptera) and predators (Odonata). The chironomid larvae accumulated
1.3 to 39 times the trace metal concentrations of the Hemiptera or odonate taxa, independent
of trace metal type (essential or non-essential) or wetland occupation. Organism-specific
factors, such as habitat selection and preferential feeding habits, were proposed to influence
benthic invertebrate accumulation profiles by modifying trace metal exposure. Mixed diets,
trophic omnivory and the complexity of wetland biogeochemistry limit the power of stable
nitrogen fractionation signatures to define benthic food web relationships. Wetland site-specific
processes impacted Se accumulating efficiency, with trace metal concentrations from
4 to 7 times greater within the lentic benthic system than the lotic. The fractionation of the
natural abundant stable carbon isotopes revealed the importance of sedimentary and detrital
organic carbon as dietary sources for the benthic food web. Sediment organic content was not
significantly associated with sediment, or invertebrate, Se accumulation profiles. Ecological
risk assessments based on sound understanding of metal chemistry and the interactions
between the sediment matrix and benthic organisms are necessary to provide tools for
environmental management. / Graduation date: 2005
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/29920 |
| Date | 24 May 2004 |
| Creators | Hillwalker, Wendy E. |
| Contributors | Anderson, Kim A., Jepson, Paul C. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
Page generated in 0.0015 seconds