Iroquois Falls Research Articles

MULTIPULSE – high resolution and high power in one TDEM system

An airborne time domain electromagnetic (TEM) system with high resolution and great depth of exploration is desired for geological mapping as well as for mineral exploration. The MULTIPULSE technology enables an airborne TEM system to transmit a high power pulse (a half-sine, for instance) and one or multiple low power pulse(s) (trapezoid or square) within a half-cycle. The high power pulse ensures good depth of exploration and the low power pulse allows a fast transmitter current turn off and earlier off-time measurement thus providing higher frequency signals, which allows higher near-surface resolution and better sensitivity to weak conductors. The power spectrum of the MULTIPULSE waveform comprising a half-sine and a trapezoid pulse clearly shows increased power in the higher frequency range (> ~2.3 kHz) compared to that of a single half-sine waveform. The addition of the low power trapezoid pulse extends the range of the sensitivity 10-fold towards the weak conductors, expanding the geological conductivity range of a system and increasing the scope of its applications. The MULTIPULSE technology can be applied to standard single-pulse airborne TEM systems on both helicopter and fixed-wing. We field tested the HELITEM MULTIPULSE system over a wire-loop in Iroquois Falls, demonstrating the different sensitivity of the high and low power pulses to the overburden and the wire-loop. We also tested both HELITEM and GEOTEM MULTIPULSE systems over a layered oil sand geologic setting in Fort McMurray, Alberta, Canada. The results show comparable shallow geologic resolution of the MULTIPULSE to that of the RESOLVE system while maintaining superior depth of exploration, confirming the increased geological conductivity range of a system employing MULTIPULSE compared to the standard single-pulse systems.

Effect of Climatic Fluctuations on Post-Fire Regeneration of Two Jack Pine and Red Pine Populations during the Twentieth Century

The age structure of two mixed red pine (Pinus resinosa Ait.) and jack pine (Pinus banksiana Lamb.) forests located at Lac Duparquet, northwestern Québec, were correlated with mean annual temperature and total precipitation recorded at Iroquois Falls for the period between 1913 and 1986. The age structures of both pine species showed a common pattern of regeneration characterized by low regeneration before 1930, an important regeneration peak starting around the 1930s, a dip in the age structure around 1950, a second, though less important, regeneration peak in the 1960s, and an important drop, especially for red pine, after 1970. In general, high regeneration rates were positively correlated with precipitation and negatively with temperature, suggesting that pine recruitment is negatively affected by low snow cover and/or drought. The absence of correlation with temperature suggests that the red pine northern limit may be controlled more by a change in the fire regime than by increasing temperature.

Observations on the Nesting of the Northern Hawk Owl, <em>Surnia ulula</em>, near Timmins and Iroquois Falls, Northeastern Ontario, in 2001

Three breeding pairs of Northern Hawk Owls were observed in northeastern Ontario in the vicinity of Timmins and Iroquois Falls in 2001, and two nests and a brood were recorded. The young from one nest fledged prematurely (likely due to a storm) and the another nest probably failed. Four other territorial pairs were observed. Notes on nest sites, feeding and nest attendance were taken.

Variations in Periodicities of the Ring Width of Black Ash (Fraxinus nigra Marsh.) in Relation to Flooding and Ecological Site Factors at Lake Duparquet in Northwestern Québec

Variations in periodicities of the radial growth response of black ash (Fraxinus nigra Marsh.) exposed to yearly spring flooding were studied in relation to hydrological fluctuations and site ecological factors at Lake Duparquet in northwestern Québec. Eight mean standardized 1880-1988 ring-width chronologies were constructed from trees growing on the floodplain, for five specific stand geomorphological landforms and three classes of elevation from the lake level. These dendrochronological series were submitted to spectral analysis based on the multi-frequential periodogram statistic. Monthly mean water discharge records of the Harricana River, and monthly mean temperature and total precipitation series collected at the Iroquois Falls weather station, all over the 1915-1990 period, were analyzed similarly. About 3.5-, 3.75-, and 7.5-year periodicities were detected in all the dendrochronological series; the 3.75- and 7.5-year components are harmonics of a 15-year periodicity that a majority of the series presented. All the ring-width chronologies, with the exceptions of the high elevation class and the stand near a bog, showed a strong biennial periodic component. A predominant 6.25-year periodicity was detected in the water discharge of the Harricana River and, to a lesser extent, in the ring-width chronologies of mid and high elevations. After an about 11-year periodicity was detected in several tree-ring and climatic series, peaks in the corresponding sine waves fitted to the tree-ring series were found to correspond to maxima in sunspot activity. Effects of geomorphological landform and elevation from the lake on the fluctuations from year to year of the radial growth of black ash were assessed by a two-way analysis of variance of the finite Fourier transform of ring-width chronologies from 46 sites, using landform and elevation as factors and sites as replicates. Significant landform effects were observed at short to longer periodicities, while an elevation environmental gradient was finely delimited. The low to high concordance levels observed in the periodicities of tree-ring series from different stands were related to ecological factors.

Cluster analysis: An application in forest management planning

The basic principle of cluster analysis is illustrated with a simple example. The method is used to aggregate stands into clusters, each of which is relatively homogeneous and geographically compact but distinct from the remainder. Such aggregation is required to convert the output from a harvest scheduling model to a form suitable as input for a one-year, operational planning model. An application of the method, based on data from the Iroquois Falls Management Unit in northern Ontario, is given.

Analyses of a Forest Drainage Experiment in Northern Ontario. II: An Economic Analysis

Results of an economic analysis of a forest drainage experiment established near Iroquois Falls, Ontario, indicate that, from 1929 to 1969, the annual rate of return due to drainage of the better site increased from −2.7 to 3.4%. For the entire drainage area the annual rate of return increased from 2.0 to 2.2% and will increase for several years.Further analysis based on current drainage cost and projected future stumpage prices indicates that future rates of return from drainage of similar sites will be about 6%. Because of technological advances in forest drainage and savings realized in logging and transportation costs as a result of drainage, the expected future rate of return from the best drainable site could easily increase to about 10%.Whether such rates of return are sufficient to induce investment in drainage depends on other investment possibilities and on social, environmental, and political considerations regarding the various alternatives.

Effect of SO2 Removal on the Biodegradability of Arbiso Spent Sulphite Liquor

Abstract The spent sulphite liquor derived from Abitibi Paper Company, Iroquois Falls Mills Arbiso process contained about 11.3% dissolved solid, 0.52% (W/V) residual SO2 and had a low pH of 4.3. The COD of the liquor was about 109,000 ppm and BOD5 26,000 ppm. The objective of the study was to investigate the technical feasibility of utilizing biodegradation to reduce the BOD5 of the spent liquor to acceptable levels. Upon first analysis, it appeared that the liquor would be amenable to biological degradation because of the presence of wood sugars. However, biological oxidation was retarded due to the presence of SO2. The maximum SO2 concentration tolerated by the microbes was about 0.32% (W/V). Boiling and lime treatment were found to be effective in reducing the SO2. Other major factors affecting biological activity were initial pH adjustment and nutrient addition. Nutrients required and optimal operating conditions are discussed. Under optimal conditions, a batch biological system was capable of removing 60% BOD5, in 11 days and 80% BOD5 in 16 days.

GLACIAL FEATURES OF THE HEARST‐COCHRANE MAP‐SHEET AREA: An Aerial Photograph Reconnaissance

A number of glacial landform features which are interpretable from aerial photographs are described for the area covered by the Hearst‐Cochrane 8 miles to 1 inch map sheet. These include both the drumlinoidal patterns created by moving ice sheets, and various glacio‐fluvial and outwash landforms associated with the recession of continental glaciers. Sequence of late‐Wisconsin events is postulated as a working hypothesis.In the subsequent discussion of the distribution and nature of these landforms a sequence of late‐Wisconsin events is postulated as a working hypothesis.The hypothetical series of events worked out mainly on the basis of the evidence provided by the aerial photograph interpretation, may be briefly enumerated as follows:‐ A late‐Wisconsin glacial advance from the northeast ‐ the Labradorean In the subsequent discussion of the distribution and nature of these landforms a The hypothetical series of events worked out mainly on the basis of the evidence glacier ‐ presumed to be correlated to the Mankato ice advance. Recession of the Mankato (?) ice‐sheet, along with the formation of a proglacial lake and a possible marine invasion. A second glacial advance from the northwest covering all but the southern sections of the map‐area and the complete o r partial destruction of mariy of the eskers and other landforms of the Mankato (?) advance. Recession of the second glacier and the creation of Lake Ojibway as well as the large eskers, with their associated esker deltas, of the northeastern area of the map. Continued recession of this ice sheet no doubt allowed the complete drainage of Lake Ojibway and possibly the beginnings of marine inundation in the James Bay area. A readvance took place (Antevs'‐ Cochrane readvance) from the region to the north of the area of the Hearst‐Cochrane map‐sheet. This readvance took a asymmetric lobate form, and in part moved southward as far as approximately the latitude of Iroquois Falls where it formed kame deposits. This readvance also left a thin mantle of silty till covering the glacio‐flwial and lacustrine deposits associated with the recession of the second (northwestern) glaciation.