The chemistry, mineralogy, and rates of transport of sediments in the ...
The chemistry, mineralogy, and rates of transport of sediments in the ...
The chemistry, mineralogy, and rates of transport of sediments in the ...
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
3<br />
Stream <strong>and</strong> river bottom <strong>sediments</strong> were sampled by h<strong>and</strong> <strong>and</strong> with Lane<br />
buckets, Ekman <strong>and</strong> Ponar dredges . . Shore, <strong>and</strong> bank <strong>sediments</strong> were sampled<br />
with a shovel . Water velocity was measured with Gurley flow meters, <strong>and</strong><br />
steel tapes were used to measure stream cross-section area . Discharge <strong>and</strong><br />
suspended sediment concentrations were also taken from <strong>the</strong> data <strong>of</strong> Davies<br />
(1973 ; 1974) .-<br />
Oxygen-dem<strong>and</strong> <strong>of</strong> Harris bank <strong>sediments</strong> was estimated <strong>in</strong> <strong>the</strong> field <strong>and</strong><br />
laboratory . Harris River bank <strong>sediments</strong>, identical to those <strong>sediments</strong> used<br />
<strong>in</strong> <strong>the</strong> experiments <strong>of</strong> Rosenberg <strong>and</strong> Snow (1975), were added to 300 ml glass<br />
stoppered 02 bottles to yield suspended sediment concentrations <strong>of</strong> 2 to 300 mg/L<br />
<strong>of</strong> Harris River water . <strong>The</strong>se stoppered bottles, with sediment-free controls,<br />
were suspended <strong>in</strong> <strong>the</strong> stream current for 1-4 hours . Oxygen was measured by<br />
<strong>the</strong> W<strong>in</strong>kler method (APHA, 1965) at <strong>the</strong> beg<strong>in</strong>n<strong>in</strong>g <strong>and</strong> <strong>the</strong> end <strong>of</strong> <strong>the</strong> period to<br />
estimate changes <strong>in</strong> 02 concentrations caused by <strong>sediments</strong> . Similar experiments<br />
were done <strong>in</strong> <strong>the</strong> Freshwater Institute laboratory by add<strong>in</strong>g Harris River<br />
bank <strong>sediments</strong> to oxygenated water <strong>in</strong> glass stoppered bottles to yield sediment<br />
concentrations <strong>of</strong> 100-18,500 mg/L . <strong>The</strong>se bottles were wrapped <strong>in</strong> t<strong>in</strong>foil<br />
<strong>and</strong> agitated on an automatic shaker for 16-60 hours . Oxygen was measured as<br />
above .<br />
SampleAnalyses<br />
-Suspended sediment samples were usually filtered on ignited, preweighed<br />
Whatman GF/C 45 mm filters at field camps <strong>in</strong> Ft . Simpson <strong>and</strong> Inuvik, usually<br />
on <strong>the</strong> day <strong>of</strong> sampl<strong>in</strong>g, but sometimes_ as late as one week after sampl<strong>in</strong>g .<br />
Alternately, large volume (20 L . carboy) samples were centrifuged <strong>in</strong> Yellowknife<br />
on a Sorval RC2B centrifuge with a cont<strong>in</strong>uous-flow unit . A comparison<br />
<strong>of</strong> <strong>the</strong> precision <strong>of</strong> <strong>the</strong>se methods is given <strong>in</strong> Campbell <strong>and</strong> Elliott (1975)<br />
which <strong>in</strong>dicates that filtration <strong>of</strong> 1-2 L . <strong>of</strong> sample gives reasonable (±5%)<br />
results, even <strong>in</strong> very low suspended sediment (2-5 mg/L) waters . For analytical<br />
reasons, it was necessary to have large (10 g) samples <strong>of</strong> suspended <strong>sediments</strong>,<br />
which required <strong>the</strong> use <strong>of</strong> <strong>the</strong> cont<strong>in</strong>uous-flow centrifuge . <strong>The</strong> precision <strong>of</strong><br />
suspended sediment determ<strong>in</strong>ation by centrifugation was 15-20% for low suspended<br />
sediment waters (Campbell <strong>and</strong> Elliott, 1975) . <strong>The</strong> sediment collected by<br />
centrifugation was dried at 110°C <strong>in</strong> <strong>the</strong> centrifuge tube, weighed, removed<br />
from <strong>the</strong> tube, ground with mortar <strong>and</strong> pestle, <strong>and</strong> shipped to Freshwater<br />
Institute laboratories for m<strong>in</strong>eralogical <strong>and</strong> chemical analyses . Sediment<br />
on filters was dried, weighed, <strong>and</strong> stored <strong>in</strong> a freezer until analysis . Particulate<br />
phosphorus (PP) was analyzed <strong>in</strong> <strong>the</strong> Yellowknife laboratory from filter<br />
samples accord<strong>in</strong>g to Sta<strong>in</strong>ton et aZ . (1974) . Particulate carbon (PC) <strong>and</strong><br />
particulate nitrogen (PN) were determ<strong>in</strong>ed from filters or subsamples <strong>of</strong><br />
centrifuged sediment on a CHN elemental analyzer accord<strong>in</strong>g to Sta<strong>in</strong>ton et OZ .<br />
(1974) <strong>and</strong> Hauser (1973) .<br />
For <strong>the</strong> analysis <strong>of</strong> copper <strong>and</strong> z<strong>in</strong>c, <strong>sediments</strong> were dried for 1 hour at<br />
100°C, .cooled to room temperature <strong>in</strong> a desiccator, <strong>and</strong> a quantity <strong>in</strong> <strong>the</strong> range<br />
<strong>of</strong> 0 .1-0 .2 grams was weighed accurately <strong>in</strong>to <strong>the</strong> teflon <strong>in</strong>sert <strong>of</strong> an acid<br />
digestion bomb (Parr 4745) . <strong>The</strong> sediment was digested <strong>in</strong> <strong>the</strong> bomb with a