Jules M. Blais

Accumulation of persistent organochlorine compounds in mountains of western Canada

Persistent, semi-volatile organochlorine compounds, including toxic industrial pollutants and agricultural pesticides, are found everywhere on Earth, including in pristine polar and near-polar locations. Higher than expected occurrences of these compounds in remote regions are the result of long-range transport in the atmosphere, precipitation and ‘cold condensation’ — the progressive volatilization in relatively warm locations and subsequent condensation in cooler environments, which leads to enhanced concentrations at high latitudes. The upper reaches of high mountains are similar to high-latitude regions in that they too are characterized by relatively low average temperatures, but the accumulation of organochlorine compounds as a function of altitude has not yet been documented. Here we repororganochlorine deposition in snow from mountain ranges in western Canada that show a 10- to 100-fold increase between 770 and 3,100 m altitude. In the case of less-volatile compounds, the observed increase by a factor of 10 is simply due to a 10-fold increase in snowfall over the altitude range of the sampling sites. In the case of the more-volatile organochlorines, cold-condensation effects further enhance the concentration of these compounds with increasing altitude. These findings demonstrate that temperate-zone mountain regions, which tend to receive high levels of precipitation while being close to pollutant sources, are particularly susceptible to the accumulation of semivolatile organochlorine compounds.

Relations between lake morphometry and the presence of laminated lake sediments: a re-examination of Larsen and Macdonald (1993)

Abstract In this paper we conduct an empirical test of a published equation which relates lake surface area and maximum lake depth to the presence or absence of laminated lake sediments. A 297 lake dataset from New York State and six regions in Canada, representing a number of biogeoclimatic zones, is employed. The results suggest that deeper lakes are more likely to contain laminated lake sediments than are shallower lakes. The percentage of lakes incorrectly predicted to contain laminated sediments (false positives) and that incorrectly predicted to contain massive sediments (false negatives), was much higher than that found in the study in which the original equation was developed. Its low predictive ability suggests, therefore, that in addition to lake morphometry, many other factors affect the formation and preservation of laminated sediments.

Concentrations of organochlorine pesticides and polychlorinated biphenyls in amphipods (Gammarus lacustris) along an elevation gradient in mountain lakes of western Canada

Populations of the amphipod Gammarus lacustris were examined for their concentrations of organochlorine pesticides and polychlorinated biphenyls (PCBs) from seven lakes spanning a 1,300-m elevation gradient in Alberta, Canada. The concentrations of several of the semivolatile organochlorine compounds ([SVOCs], vapor pressure > 0.03 Pa at 20 degrees C) increased at higher altitudes. This pattern was generally not observed among the less volatile organochlorines ([LVOCs]. vapor pressure < 0.03 Pa at 20 degrees C). These same SVOC compounds have been previously shown to increase at high latitudes as a result of their long-range transport and preferential deposition in cold climates. We also show that populations of G. lacustris at high elevations have slower growth rates and store more lipids than populations at lower elevations. To resolve the colinearity of independent variables, we used multiple regression to identify patterns of contaminant concentrations in this data set. Multiple regressions showed that the effect of elevation, lipid content, and temperature on contaminant concentrations was no longer significant once the growth rate of Gammarus was included as an independent variable. This study shows that enrichment of SVOCs occurs in Gammarus at high altitudes in Alberta, Canada, and that growth rate (biodilution) appears to be the primary influence. Because Gammarus is an important trophic link in aquatic foodwebs in these environments, enhanced concentrations of toxicants in prey may increase their biomagnification in top predators of high-altitude lakes.

Regional Contamination in Lakes from the Noril'sk Region in Siberia, Russia

Sediment and water chemistry data were collected from ten lakes within a 110 km radius of Norilsk in Siberia, the largest smelting complex in the world. Metals showing the most pronounced increase in enrichment near the smelters were Cu, Ni, Co, Ba and Zn. Cu and Ni appear to be as or more enriched in lake sediments around Norilsk compared with levels previously reported for other locations. Although SO4 concentrations were highly elevated in the areas closest to the smelting complex, lake water pH remained elevated due to high concentrations of base cations in the waters. Sediment mercury enrichment was high in sediments near the smelting complex, but not more so than in other parts of the Arctic, suggesting that Hg either is not a major smelting product at Norilsk, or that Hg is transported greater distances than other metals due to its longer atmospheric residence time.

A paleolimnological assessment of the effects of logging on two lakes in northwestern Ontario, Canada

Most of the recent srudies that have examined the effects of forest harvesting on aquatic ecosystems have focussed on stream environments. It has been shown that these disturbances may alter water quantiry through a disruption of hydrological regimes (HARTMAN & ScRJVENER 1990, MILLER et al. 1997), and water qualiry through elevated inputs of nutrients and suspended solids, and changes to mixing regimes (NICOLSON 1975, PATRIC 1980, KRAusE 1982, FELLER & KIMMINS 1984, LYNCH & CüRBETT 1990, KEENAN & K!MMINS 1993). Considerably fewer studies have examined the ecological effects of timber management on lakes (see reviews in KEENAN & KlMMINS 1993, MILLER et al. 1997).