title: Reconstructing long-term trends in municipal sewage discharge into a small lake in northern Manitoba, Canada.
abstract: Ross Lake lies within the City of Flin Flon (Manitoba, Canada), a mining community originally formed by the Hudson Bay Mining and Smelting Company (now Hudbay Minerals Inc.) in 1927. At the time of this investigation, a continuous effluent stream from Hudbay Minerals (approximately 80 years) and a discontinuous and unknown amount of raw and minimally treated municipal sewage (>20 years, likely ending in 1951) was discharged into the north basin of the lake. Maximum concentrations of fecal sterols, such as coprostanol and terrestrial phytosterols, such as: β-sitosterol, campesterol, stigmastanol were measured in vertical sections of sediment cores, collected from Ross Lake, in the 15-16-cm section, which likely corresponds to the 1930s. Concentrations of coprostanol increased from <1 μg g(-1) in older sediments, to 252.3 μg g(-1) organic carbon at the peak. Observed changes in concentrations of sterols, in combination with radiometric dating and changes to sediment physicochemical characteristics, support the conclusion that sediments of a depth of less than 17.5-cm depth were deposited during the post-industrial era from approximately 1930 onwards. Ratios of coprostanol to cholesterol>1, peaking at 3.6 are consistent with anecdotal information that municipal sewage was discharged into Ross Lake during the early years of urbanization, prior to changes in treatment of sewage and discharge practices that began in 1951. Finally, historical concentrations of terrestrial phytosterols followed trends similar to those of coprostanol and cholesterol and may possibly be the result of an increase in the flux of terrestrial organic matter into Ross Lake as the result of regional deforestation due to logging and fire.
authors.affiliation: Toxicology Graduate Program, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B3, Canada.
authors.forename: T J
authors.initials: TJ
authors.lastname: Tse
authors.affiliation: Toxicology Center, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B3, Canada.
authors.forename: G
authors.initials: G
authors.lastname: Codling
authors.affiliation: Toxicology Center, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B3, Canada; School of Environment and Sustainability, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C3, Canada.
authors.forename: P D
authors.initials: PD
authors.lastname: Jones
authors.affiliation: Saskatchewan Structural Sciences Centre, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C9, Canada.
authors.forename: K
authors.initials: K
authors.lastname: Thoms
authors.affiliation: Toxicology Center, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B3, Canada.
authors.forename: K
authors.initials: K
authors.lastname: Liber
authors.affiliation: Toxicology Center, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B3, Canada; Department of Veterinary Biomedical Sciences, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B4, Canada.
authors.forename: J P
authors.initials: JP
authors.lastname: Giesy
authors.affiliation: Global Institute for Water Security, University of Saskatchewan, Saskatoon, Saskatchewan S7N 3H5, Canada.
authors.forename: H
authors.initials: H
authors.lastname: Wheater
authors.affiliation: Toxicology Center, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B3, Canada. Electronic address: lorne.doig@usask.ca.
authors.forename: L E
authors.initials: LE
authors.lastname: Doig
mesh_terms: D002784:Cholesterol / Q000031:analogs & derivatives / Q000032:analysis / Q000266:history; D004784:Environmental Monitoring; D005243:Feces / Q000737:chemistry; D019015:Geologic Sediments / Q000737:chemistry; D049673:History, 20th Century; D049674:History, 21st Century; D060106:Lakes / Q000737:chemistry*; D008350:Manitoba; D010840:Phytosterols / Q000032:analysis / Q000266:history; D012722:Sewage / Q000737:chemistry*; D012855:Sitosterols / Q000032:analysis / Q000266:history; D014865:Waste Disposal, Fluid / Q000266:history; D014873:Water Pollutants / Q000032:analysis* / Q000266:history; D018508:Water Purification / Q000266:history
chemical_list: D010840:Phytosterols; D012722:Sewage; D012855:Sitosterols; D014873:Water Pollutants; C021273:campesterol; C025473:gamma-sitosterol; D002784:Cholesterol; C021255:stigmastanol
keywords: Coprostanol; Fecal sterols; Municipal sewage; Phytosterols; Sediment