Canadian Shield, lakes

Bodaly RA, Rudd JWM, Fudge RJP, Kelly CA. 1993. Mercury concentrations in fish related to size of remote Canadian shield lakes. Can J Fish Aquat Sci 50 980-987. 

Auclair, J. C. 1995. Implications of increased UV-B induced photoreduction Iron(II) enrichment stimulated picocyanobacterial growth and the microbial food web in clear-water acidic Canadian Shield lakes. Canadian Journal of Fisheries and Aquatic Sciences 52 1782—1788. Auclair, J. C., P. Brassard, and P. Couture. 1985. Total dissolved phosphorus Effects of two molecular weight fractions on phosphorus cycling in natural phytoplankton communities. Water Research 19 1447—1453. 

Servos, M.R., Muir, D.C.G. (1989a) Effect of dissolved organic matter from Canadian shield lakes on the bioavailability of 1,3,6,8-tetrachlorodibenzo-p-dioxin to the amphipod Crangonyx laurentianus. Environ. Toxicol. Chem. 8, 141-150. 

E.J. Fee, R.E. Hecky, S.E.M. Kasian, D.R. Cruikshank (1996). Effects of lake size, water clarity, and climatic variability on mixing depths in Canadian shield lakes. Limnol. Oceanogr., 41, 912-920. 

A. Perez-Fuentetaja, D.J. Dillon, N.D. Yan, D.J. McQueen (1999). Significance of dissolved organic carbon in the prediction of themocline depth in small Canadian shield lakes. Aquat. Ecol, 33,127-133. 

S.S. Dixit, W. Keller, A.S. Dixit, J.P. Smol (2001). Diatom-inferred dissolved organic carbon reconstructions provide assessments of past UV-B penetration in Canadian Shield lakes. Can. J. Fish. Aquat. Sci., 58, 543-550. 

Recently, distribution coefficients Kd for " "Tc in Canadian Shield lake sediments were determined under oxic and anoxic conditions in a laboratory study. Untreated Winnipeg River water was used. For the oxic treatment, sediment and water were shaken for 24 h, spiked with 932 Bq of shaken for another 48 h. The... 

Edwards, T. W. D. J. H. McAndrews, 1989. Paleohydrology of a Canadian Shield lake inferred from Oin sediment cellulose. Can. J. Earth Sci. 26 1850-1859. 

Vast undulating till plains occur in North America, between the Canadian shield area and the loess belt. This area is either covered with thick tills or with deglaciation sediments, lacustrine sediments in particular. The lake areas are level as such but the till landscape has a typical hummocky relief. The main characteristic of hummocky tills (40% of the total area) is the predominance of very local drainage patterns (mainly in depressions). Tills and loess have in common that they are internally uniform and that they all date back to deglaciation periods. 

The regional-based survey pattern of the GSC-determined Hg concentrations (ppb) in stream sediments across Canada is shown in Fig.1. Of particular interest are (i) the high Hg concentration cluster near the central north-eastern border of the Yukon Territory (Survey Zone 3), (ii) the somewhat elevated background levels in the southern portions of the Canadian Shield along the Great Lakes, (iii) the scattered pattern of similar values throughout British Columbia, Labrador and... 

Figure 19. Plot of Li isotopic composition vs. inverse Li concentration for lakes and basinal/oilfield brines. Lakes open circle = major global lakes (Chan and Edmond 1988 Falkner et al. 1997) semi-open circle = western U.S. closed basin lakes (Tomascak et al. 2003). Oilfield brines inverted triangle = Williston basin, Saskatchewan (Bottomley et al. 2003) diamond = Israeli oilfields (Chan et al. 2002d). Mine waters (Canadian Shield basinal brines) square = Yellowknife, NWT (Bottomley et al. 1999) triangle = Sudbury, Ontario, area (Bottomley et al. 2003) star = Thompson, Manitoba, area (Bottomley et al. 2003). Average composition of seawater is included for reference.

Carignan, R., P. D Arcy, and S. Lamontagne. 2000. Comparative impacts of fire and forest harvesting on water quality in Boreal Shield lakes. Canadian Journal of Fisheries and Aquatic Sciences 57 (Suppl. 2) 105-117. 

Generally, the problems with acid water occur mostly in areas with granitic or similarly resistive bedrock, and with sparse soil cover derived from the same parent material. Calcium concentration levels in surface waters are generally low, typically less than 2 mg/1. This explains why the problem so far has mainly surfaced in Scandinavia, and in areas of similar geological formations on the Canadian shield and in the Adirondack Mountains. Some acidification of lakes and water courses has also occurred in England and Scotland (32,33), and in the Erzgebirge between the German Democratic Republic and Czechoslovakia (34,35). 

Investigations on the transfer of l e04 from surface water to organic-rich bottom sediments in the freshwater Perch Lake, located on the Canadian Shield, revealed very low transfer rates of only 1.4 to. 1.3 % of radioactivity per day. The same range of transfer rates was found for - I and [32]. 

In Canada, nearly 45% of the land area is considered sensitive to acid deposition. Lakes and watersheds located on the Canadian Shield are considered the most vulnerable, due to the low buffering capacity of the typically shallow soils that overlay the Shield bedrock. A large portion of eastern Canada, including much of Ontario and Quebec as well as parts of the Atlantic Provinces are underlain by silicate bedrock these areas also receive the highest levels of acid deposition in the country. 

The Nechalacho deposit (Thor Lake) is located at the Southern Margin of the Archaean Slave Province of the Canadian Shield. It is centered within the Blachford Igneous Complex, which consists of rocks of an early suite of gabbro, quartz syenite and granite, and a later suite of granite, with a core of syenite (Thor Lake syenite). The early suite is relatively aluminous, whereas the rocks of the later suite... 

Canadian Shield, North America Pine Cone Lake, Ontario present day 13.64 14.75 33.87 Wampler and Kulp (1964)... 

Sediments from Lake Superior in the Canadian Shield ... 

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