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

More documents

Recommendations

Info

4 nitric/hydrofluoric acid mixture (5 :8 volumes respectively of concentrated acids) using high-purity acids (Aristar) for 48 hours at 140-145°C . After cooling to room temperature, 4 grams of recrystallized reagent grade boric acid were added, the pH was adjusted to 4 .0 with ammonia, and the digest was then transferred quantitatively to a 125 ml separatory funnel . The heavy metals were then complexed with ammonium pyrollidine dithicarbamate (AFDC) (2 ml of 2% solution) and extracted 3-4 times with 30 ml of carbon tetrachloride . The extract was collected in a 100 ml volumetric flask, and the solvent was then removed from the extract with a Buchi Rotavapor evaporator . For this purpose the volumetric flask was attached directly to the evaporator via a special adaptor . Removal of solvent was carried out at relatively low temperature (50-55°C) to prevent loss of metals in the process . The residue in the flask was then oxidized with 5-ml of concentrated high-purity (Aristar) nitric acid, and the solution was made up to volume with triply distilled (twice in quartz) water . The heavy metals in this aqueous matrix were then analyzed for Cu and Zn by flameless atomic absorption, using a heated graphite tube atomizer, 70 HGA Perkin Elmer, and a 403 Perkin Elik , Atomic Absorption Spectrophotometer . Precision, accuracy and some operational parameters are given in Wagemann (1975) . The elements Si, Al and Ca were determined simultaneously on a multichannel ARL X-ray spectrometer (University of Manitoba, using the method of Wilson et al ., 1965) . This method consists essentially of fusing the sample with lithium tetraborate at 1100°C, then grinding the fused bead with the appropriate quantities of lanthanum oxide and boric acid and pressing the mixture into discs appropriate for analysis . Cation exchange capacity and ammonium acetate-extractible cations were determined on Mackenzie Delta channel sediments according to methods 5A1 and 3A2a from U . S . Dept . Agriculture (1967) . These sediments were also extracted with HC1 to determine acid- .labile elements . Oven-dried (110 °C) sediment (15-25 g) was shaken with 100 ml of 1N NH40Ac and 1N HC1 for 8 hrs . The solution was then filtered through Whatman GF/C filters and analyzed for Ca, Mg, Na, K, Fe and Hn by atomic absorption spectrophotometry according . t o Stainton et al . (1974) . X-ray diffraction, mineral identifications and sediment particle size determinations were done by methods given in Brunskill et al . (1973, Appendix VII) . Data Analysis Instantaneous concentrations of suspended, sediment or particulate nutrients were obtained by direct measurement or analysis . Instantaneous discharge figures were generally taken from Water Survey of Canada (Davies, 1973 ; 1974) . Summations of total monthly discharges, computed from the mean discharge for each month, yielded annual discharge. Monthly rates of transport of suspended sediment and particulate nutrients were calculated from the product of the mean concentration during the month and the total monthly discharge .
Annual rates of transport were obtained by summing monthly rates of transport . For months during which no concentration was measured, a seasonal mean concentration was generally applied . Winter mean concentrations were calculated for the period November through April and summer means for the period May to October . Considering each river individually, the instantaneous concentrations of suspendedr sediment. or particulate nutrients were regressed on instantaneous discharge ., All data was transformed to logarithms . The method for these simple linear regressions is discussed in Snedecor and Cochran (1971) . Only those analyses producing regression coefficients significant at a - 0 .10 were subsequently plotted . The linear regression analysis program of a Wang-462 was used for.' computations . t Annual rates of transport for particulate materials were divided by the watershed area above the sampling station . Simple linear regressions were then performed on the logarithms of these normalized transport rates versus the logarithm of corresponding annual discharges . The set of data pairs consisted of eleven different stations on eight rivers, with a maximum of three years data for any one station . The statistical method is discussed in Sokal and Rohlf (1969) . Multiple linear regressions were performed on mean annual rates of transport versus seven topographic and climatic variables . . Transport of suspended sediment, and particulate nitrogen, phosphorous and carbon were considered individually, using - the same eleven stations as above . Logarithmic transformations were maintained . Topographic variables included watershed area (Ad), change in elevation (LE) and length (L) of the river . Area of the watershed above the sampling station was obtained from Water Survey (Davies, 1973 ; 1974) • where possible, or by planimetry . Change in elevation represents •the difference between the highest - contour-in the watershed and' the contour on which the sampling station falls . Lengths of the rivers from the source to the station were determined with a chartometer . The Canadian National topographic map series (Scale 1 :250,- 000) was used for these three determinations . Temperature (T), precipitation (P), and forest cover (F) represented climatic and vegetation variables . Mean annual daily temperatures for each watershed were obtained from Figure 4 .18 in Burns, (1973), and mean annual precipitation .from Figure 6 .8 in Burns (1974) . In both cases a grid was drawn over each watershed to obtain a mean value for the watershed area . Using the map provided in Rowe (1972), •the vegetation zones included in the Mackenzie Valley and Yukon were'ranked in increasing order of forest cover : mountain tundra .- 1, forest and grassland = 2, and predominately forest - 3 . The grid method was again used to determine an average vegetation type for the watershed . The last variable was representative of the surface geology of each watershed . A coded system for erodibility (G) of rock was obtained from Jansen and Painter (1974) . The system assigns higher values to rock-types
Page 1 and 2: Department of the Environment Minis
Page 3 and 4: iii TABLE OF-CONTENTS Page List of
Page 5 and 6: V TABLE 8 . Page Mean annual rates
Page 7 and 8: vii LIST OF FIGURES Page Figure 1 .
Page 9 and 10: ix ABSTRACT Brunskill, G . J ., P .
Page 11 and 12: xi RESUMt Brunskill, G . J ., P . C
Page 13 and 14: 1 INTRODUCTION In regions of northe
Page 15: 3 Stream and river bottom sediments
Page 19 and 20: 7 The total mass of sediments remov
Page 21 and 22: 9 Only two clay minerals were found
Page 23 and 24: 11 increased sediment concentration
Page 25 and 26: 13 changes in albedo, and the gener
Page 27 and 28: 15 Increases in the concentrations
Page 29 and 30: 17 which is positively related to w
Page 31 and 32: 19 and velocity (Fig . 1) . For the
Page 33 and 34: 21 It will be necessary to quantify
Page 35 and 36: 23 CONCLUSIONS 1 . For selected riv
Page 37 and 38: 25 REFERENCES Abrahams, A . D . and
Page 39 and 40: 27 Corbel, J . 1964 . L erosion ter
Page 41 and 42: 29 Hughes, 0 . L ., J . J . Veillet
Page 43 and 44: 33 McRoberts, E . C . and N . R . M
Page 45 and 46: 33 Tarnocai, C . 1973 . Soils of th
Page 47 and 48: , 35 e TABLE 2a . Slopes ') and int
Page 49 and 50: 37 i TABLE 2c . Slopes (b) and inte
Page 51 and 52: i 39 b TABLE 3 . Average annual mas
Page 53 and 54: 41 v b TABLE 5 . Cation exchange ca
Page 55 and 56: N c . P TABLE 7a . Ranges of concen
Page 57 and 58: I a m r TABLE 8 . Mean annual rates
Page 59 and 60: 01 TABLE 10. Mean annual rates of t
Page 61 and 62: 49 TABLE 12 . Significance of regre
Page 63 and 64: TABLE 14 . Mean concentrations of s
Page 65 and 66: 9 Q TABLE 16 . A comparison of annu
Page 67 and 68:
TABLE 17 . cont'd River Year Date S
Page 69 and 70:
S TAME 17 . cont'd River Year Date
Page 71 and 72:
TABLE 17 . cont'd River Year Date Q
Page 73 and 74:
It • TABLE 17 . cont'd River Year
Page 75 and 76:
TABLE 17 . cant 'd River Year Date
Page 77 and 78:
2 =0.67 100,000- N E Y a 10,000- Y
Page 79 and 80:
c 11 I C- 10 - E n I, 0 10- E e 0.1
Page 81:
II (m 3 vnnr - ' v In'6 1 r r, m A
show all

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

Create successful ePaper yourself

Delete template?

Save as template?