The chemistry, mineralogy, and rates of transport of sediments in the ...

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stream current, and 02 was measured before-and after incubation . Nearly
all bottles (including the control bottles) increased in 02 concentration,
which indicated that algal photosynthesis produced more 02 than the sediment
consumed .
Cation Exchange Capacity andExchangeable Cations of Mackenzie Valley
Sediments
Estimates of cation exchange capacities are given for selected sediment
samples in Table 5 . Most of the flowing water suspended and bottom
sediments are rather low in cation exchange capacity, compared to Temperate
Zone prairie soils . This is likely the result of the lack of the more
reactive clay minerals (e .g .- the montmorillonite group) in these sediments .
Chlorite and illite were the clay minerals commonly found in these samples
(see Campbell et al ., 1975, for sediment mineralogy of these localities) .
Sediments of lakes usually had higher cation exchange capacities than did
flowing water sediments . Lakes in the Mackenzie Delta that frequently
received suspended sediments from flooding Mackenzie River waters had lower
exchange capacities than did Delta lakes which rarely receive Mackenzie
River floodwaters . Shell (- Long) Lake, near Inuvik, is not in the Delta,
does not receive turbid Mackenzie waters, and has the highest exchange
capacity among our samples .
Acid and basic extracts of a Mackenzie Delta East Channel sediment
sample indicated that Ca, Mg,-Na, and Fe are the major reactive ions in
the sediment (Table 6) . The large yield of Ca and Mg in the acid extract
is likely due to the dissolution of calcite and dolomite in these sediments
(see below) . The relatively high yield .of Fe in the acid extract is likely
due to the dissolution of amorphous hydrated iron oxides and hydroxides,
since our X-ray diffraction methods revealed no reactive crystalline iron
minerals .
Mineralogy of Lake andRiver
Sediments
Nearly all samples of bottom sediments, shore and bank sediments
and suspended sediments contained quartz and a Ca-rich plagioclase, and
several samples from the Beaufort Sea contained orthoclase (Campbell et at .,
1975 ; Brunskill et al ., 1973, vol . 2, App . IX, Table VI) . These .detrital
minerals were found in all size fractions, and appeared as both fresh,
sharply angled fragments and as highly abraded and rounded grains . Dolomite
and calcite were very commonly found in bottom sediments and in
suspension in river waters (see Table 8, PCo/PCZ., Campbell et al . 1975,
and Brunskill et al . 1973 .) . These carbonate minerals in river systems
are likely all detrital in origin, since ion activity products computed
from dissolved ion concentration data (Campbell et al ., 1975) indicate
undersaturation with respect to common carbonate (calcite, dolomite)
minerals, and there are abundant sources of carbonate rocks in most of
these watersheds . Most Mackenzie Delta lake bottom sediments have inorganic
compositions similar to Mackenzie River sediments, but have much higher
concentrations of organic matter (5-30% weight loss on ignition in lake
sediments, see Campbell et al . (1975) for tabulated data) .