Dissecting the spatial scales of mercury accumulation in Ontario lake sediment.
Total mercury concentration was analyzed in 171 lakes from pre-industrial (>30 cm depth; Hg(pre-industrial)) and present-day sediments (0.5-1 cm; Hg(present-day)). Numerous hot or cold spots of sediment mercury enrichment (Hg EF; Hg(pre-industrial)/Hg(present-day)) were evident as determined by local tests of autocorrelation, although in most cases, the maximum correlation among sites was not the nearest neighbor, indicating a strong influence of watershed characteristics. Hg EF was correlated with the area of open water (ha) (r = 0.91, p = 0.035), mine tailings (r = 0.94, p = 0.019), and organic deposits in surficial geology of the watershed (r = -0.91, p = 0.034). Through use of local rather than global regression coefficients, R(2) increased from 0.20 (p = 0.005) to 0.60 (p = 0.013). A broad spatial pattern (>500 km) observed only in Hg(pre-industrial) was best explained by mean annual precipitation (shared variance = 3.5%), while finer spatial patterns only observed in Hg(present-day) and Hg EF were best explained by pH (average shared variance = 10.8%).
Mills
R Brad
RB
University of Ottawa, Department of Biology, Chemical and Environmental Toxicology, Ontario, Canada. brad.mills613@gmail.com
Paterson
Andrew M
AM
Lean
David R S
DR
Smol
John P
JP
Mierle
Greg
G
Blais
Jules M
JM
D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D060106:Lakes / Q000032:analysis*; D008628:Mercury / Q000032:analysis*; D009864:Ontario; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014877:Water Pollution, Chemical / Q000032:analysis
D014874:Water Pollutants, Chemical; D008628:Mercury