Temporal and spatial trends in contaminant levels in herring gull eggs from the Great Lakes, 1974--1993
- Canadian Wildlife Service, Burlington, Ontario (Canada)
The levels of 14 organochlorine contaminants in herring gull (Larus argentatus) eggs were measured at up to 13 Great Lakes colonies during the period of 1974--1993. Linear regression was applied to all transformed contaminant values at each site to establish statistical patterns. Long term analysis (1974--1993) consisted of finding an appropriate change point model, comparing its efficacy with a single line model and choosing the most appropriate. Fifty-eight percent of the analyses required a change point in the model, the most common change points were 1987 and 1991. Of the 169 total analyses, 63% showed a significant decrease, 6% showed a significant increase and 31% showed no significant pattern over time, i.e. slope did not differ from zero. Increasing contaminant concentrations for at least one compound were found in Lakes Huron, Michigan, Ontario and Superior. In a second temporal analysis, recent trends for SUM PCB and DDE were assessed by single line regression over three time periods: 1983--1993, 1989--1993 and 1990--1993. In 89% of the analyses (n = 78), levels showed no statistical change, 5% showed a decrease and 6% showed a significant increase. Rising levels were round in Lake Huron and Superior; decreasing levels were found in the Niagara and Detroit Rivers and Lake Erie. Spatial analysis on data from the last five years indicated that oxychlordane, dieldrin and heptachlor epoxide had their greatest concentrations at Lake Michigan sites; DDE and SUM PCBs were greatest at Saginaw Bay, Lake Huron and mirex was most elevated in Lake Ontario.
- OSTI ID:
- 201231
- Report Number(s):
- CONF-9511137-; ISBN 1-880611-03-1; TRN: IM9613%%208
- Resource Relation:
- Conference: 2. Society of Environmental Toxicology and Chemistry (SETAC) world conference, Vancouver (Canada), 5-9 Nov 1995; Other Information: PBD: 1995; Related Information: Is Part Of Second SETAC world congress (16. annual meeting): Abstract book. Global environmental protection: Science, politics, and common sense; PB: 378 p.
- Country of Publication:
- United States
- Language:
- English
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