• Automatic detection of sensor calibration errors in mining industry

      Pothina, Rambabu; Ganguli, Rajive; Ghosh, Tathagata; Lawlor, Orion; Barry, Ronald (2017-12)
      Sensor errors cost the mining industry millions of dollars in losses each year. Unlike gross errors, "calibration errors" are subtle, develop over time, and are difficult to identify. Economic losses start accumulating even when errors are small. Therefore, the aim of this research was to develop methods to identify calibration errors well before they become obvious. The goal in this research was to detect errors at a bias as low as 2% in magnitude. The innovative strategy developed relied on relationships between a variety of sensors to detect when a given sensor started to stray. Sensors in a carbon stripping circuit at a gold processing facility (Pogo Mine) in Alaska were chosen for the study. The results from the initial application of classical statistical methods like correlation, aggregation and principal component analysis (PCA), and the signal processing methods (FFT), to find bias (±10%) in "feed" sensor data from a semi-autogenous (SAG) grinding mill operation (Fort Knox mine, Alaska) were not promising due to the non-linear and non-stationary nature of the process characteristics. Therefore, those techniques were replaced with some innovative data mining techniques when the focus shifted to Pogo Mine, where the task was to detect calibration errors in strip vessel temperature sensors in the carbon stripping circuit. The new techniques used data from two strip vessel temperature sensors (S1 and S2), four heat exchanger related temperature sensors (H1 through H4), barren flow sensor (BARNFL) and a glycol flow sensor (GLYFL). These eight sensors were deemed to be part of the same process. To detect when the calibration of one of the strip vessel temperature sensors, S1, started to stray, tests were designed to detect changes in relationship between the eight temperature sensors. Data was filtered ("threshold") based on process characteristics prior to being used in tests. The tests combined basic concepts such as moving windows of time, ratios (ratio of one sensor data to data from a set of sensors), tracking of maximum values, etc. Error was triggered when certain rules were violated. A 2% error was randomly introduced into one of the two strip vessel temperature data streams to simulate calibration errors. Some tests were less effective than others at detecting the simulated errors. The tests that used GLYFL and BARNFL were not very effective. On the other hand, the tests that used total "Heat" of all the heat exchanger sensors were very effective. When the tests were administered together ("Combined test"), they have a high success rate (95%) in terms of True alarms, i.e., tests detecting bias after it is introduced. In those True alarms, for 75% of the cases, the introduction of the error was detected within 39.5 days. A -2% random error was detected with a similar success rate.
    • Axisymmetric numerical heat transfer analysis of natural gas hydrates reservoir

      Subbaihaannadurai, Vijayagandeeban; Das, Debendra K.; Patil, Shirish L.; Goering, Douglas J. (2004-12)
      Gas hydrates are crystalline substances, occurring in nature under high pressure and low temperature. Numerical studies were conducted on dissociation of gas hydrate to recover natural gas. The model is a cylindrical geometry with a wellbore at the center through which hot water is injected. Through this thermal stimulation technique frozen hydrate reservoir is melted and natural gas is released. The computational fluid dynamics software FLUENT was adopted to generate the model. The initial model was solely comprised of a hydrate layer. This model was refined by adding the overburden and the underburden to the hydrate and exploring the thermal regime of the entire composite medium. Unsteady state results showing the dissociation front propagation with respect to time were calculated. In the first part, the hydrate medium is dissociated by the conduction phenomenon only. In the second part, due to the porous nature of the hydrate medium, both conduction and convection phenomena are considered. This thesis presents the following results obtained from simulations using Fluent. They are: temperature rise within the reservoir with time, temperature profiles in the radial direction, and steady and transient state solutions of the dissociation of gas hydrate with the liquid fraction in the reservoir. Comparison of our results with a finite difference model and a finite element model is also included. Volumes of gas released with respect to time and thermal efficiency ratios are also determined.
    • Baseline geochemical studies for resource evaluation of D-2 Lands - geophysical and geochemical investigations at the Red Dog and Drenchwater Creek mineral occurrences

      Metz, P.A., Robinson, M.S., and Lueck, L. (University of Alaska Mineral Industry Research Laboratory, 1979)
      Major zinc, lead and barite mineralization has been discovered at Red Dog and Drenchwater Creeks in the DeLong Mountains of north-western Alaska. The host rocks for the mineral occurrences are carbonates, cherts, shales, and dacitic volcanic rocks of the Mississippian Lisburne Group. The host rocks are deformed in a narrow belt of imbricate thrust sheets that extend from the Canadian border to the Chukchi Sea. The rocks strike generally east-west and dip to the south. The sulfide minerals occur as stratiform mineralization parallel to bedding planes, as breccia fillings and vein replacements, and as disseminations in the various host rocks. The primary ore minerals are sphalerite, pyrite, pyrrhotite, and galena. Barite occurs as massive beds up to 90 meters (300 feet) thick at Red Dog Creek and as nodules, veinlets, and disseminations at Drenchwater Creek. Close spaced soil sampling, mercury vapor sampling, and magnetic and radiometric surveys were conducted over the areas of exposed sulfide mineralization to test the response of these techniques to these types of deposits in northern Alaska. There is potential for additional deposits of this type in the Lisburne Group of the entire northern Brooks Range. These techniques provide a rapid low cost method for the discovery and preliminary evaluation of these types of mineral occurrences in northern Alaska.
    • Behavior Of Granular Materials Under Cyclic And Repeated Loading

      Minassian, George H.; Raad, Lutfi (2003)
      Granular layers are essential contributors to the structural integrity of the pavement system, their premature deformation radically decrease support of the asphalt concrete surface layer, thus leading to the early deterioration of the overall pavement structure. This research was conducted to better understand the behavior of granular materials when subjected to the complex nature of traffic loading. Long-term triaxial tests were conducted on typical Alaskan base course material using both repeated as well as cyclic loading to also account for the shear reversal effects induced by wheel load. Results show that the shear reversal component of the traffic loads, which have been ignored so far, induces considerable damage to the granular layers. Models were presented to predict the different soil moduli while also accounting the effect of strain hardening or densification due to the repetitive nature of the loads applied. Moreover, a simple yet powerful model was presented to predict accumulated permanent strains as function of the stress state, number of load repetitions and the strength level applied. The results obtained in this study also show a clear indication of the existence of given stress level limit beyond which incremental collapse of the system takes place. Furthermore, regions of instability of granular layers subjected to dynamic loading have been defined using a simple response parameter and monotonic shear strength of the soil. An effort was made to explain the instability zones identified in this research by the shakedown theory.* *This dissertation is a compound document (contains both a paper copy and a CD as part of the dissertation). The CD requires the following system requirements: Microsoft Office.
    • Beneficiation of rare earth minerals from Bokan Mountain: Dotson Ridge ore

      Narantsetseg, Purevbaatar; Наранцэцэг, Пүрэвбаатар; Ganguli, Rajive; Ghosh, Tathagata; Akdogan, Guven (2014-12)
      The purpose of this research work was to study the beneficiation of rare earth ore of the Bokan Mountain -- Dotson Ridge deposit, located near Ketchikan, Alaska. Rare earth element (REE) composite ore samples from the Bokan Mountain -- Dotson Ridge deposit were tested using gravity concentration, magnetic separation, flotation, and leaching techniques to separate the REE. The composite ore sample was a product of a preliminary x-ray sorting process. Qualitative electron microprobe analysis of the ore showed that most of the REE minerals in the ore were silicate minerals. Since the electron microprobe analysis samples were coated with carbon during sample preparation, the carbon element was inactivated for analysis. Because of this, carbonate compounds of minerals' particles could not be detected. 95% of the REE mineral particles appear to be smaller than about 10 μm in size (about 100 μm² in area). For the gravity concentration, light rare earth elements (LREE) and heavy rare earth elements' (HREE) individual elemental recovery values were in the ranges of 49.6-52.8% and 46.3-48.8%, respectively, at 25% of mass yield. In order to separate a larger amount of the REE, a wet high intensity magnetic separation (WHIMS) test was carried out on tailings of the gravity concentration tests. The HREE individual elemental recovery values ranged from 56.3-63.1% at 37% mass yield, while LREE individual elemental recovery values were in the 57.9% - 59.1% range. For the combined gravity and magnetic separation processes, the net individual elemental recovery values of the LREE and the HREE were in the range of 79.6-80.5% and 76.5-80.9%, respectively. The combined mass yield of the gravity and magnetic separation processes was 3%. Direct leaching tests conducted on the composite ground ore feed yielded high individual elemental recovery values of 90-92% of the LREE. The HREE individual elemental recovery values ranged from 56.5-87.3%. In the leaching, 20% HCl was used in the 1st and 2nd stages with a duration of 2 hrs in each stage at 90°C. The solid percentage of the leach slurry was 20% w/w. The composite ground ore sample was tested in conventional flotation using a 2.0 L capacity Denver cell. In the flotation, 0.05 kg/tonne of Cytec Aero 6493 collector, 0.05 kg/tonne of Cytec Aero Froth 88, and 0.1 kg/tonne of sodium metasilicate as a depressant were used. Pulp pH was set around 9. Results showed individual elemental recovery values in the range of 44.6-50.4% or the LREE. The HREE individual elemental recovery values ranged from 27.9-44.5%. The mass yield of the flotation was 23%. The flotation recoveries reported here are significantly lower than what was achieved previously. For the Leach after flotation process, leaching was conducted on the first concentrate of flotation. Individual elemental recovery values of the LREE and HREE were 94.7-96.5% and 61.1-90.5%, respectively. The concentrate was leached using 20% HCl in both the 1st and 2nd stages, with a duration of 2 hrs in each stage at 90°C. Flotation/Leach process net recoveries of LREE by individual elemental values ranged from 42.2-48.5%. HREE net recoveries by individual elemental values ranged from 17.1-41.4%.
    • BERG2 Micro-Computer Estimation of Freeze and Thaw Depths and Thaw Consolidation

      Braley, W. Alan; Connor, Billy (1989-06)
      The BERG2 microcomputer program uses a methodology similar to the Modified Berggren method (Aldrich and Paynter, 1953) to estimate the freeze and thaw depths in layered soil systems. The program also provides an estimate of the thaw consolidation in ice rich soils. BERG2 differs from the original Modified Berggren method since it uses the actual frozen and unfrozen material thermal properties instead of average alues. This approach improves the accuracy of the prediction. BERG2 provides an improved user interface over the original BERG program (Braley, 1984). It also requires less input as a result of the ability to compute many of climatic parameters from the more common data. As a result the user required input is significantly reduced. This manual provides the user information concerning the use of BERG2, its strengths and its limitations. It also provides a discussion of the equations used in development of the program for those who wish a better understanding of the analysis process.
    • Best practices and metrics for virtual reality user interfaces

      Byam, Jay; Chappell, Glenn; Lawlor, Orion; Metzgar, Jonathan (2019-12)
      Virtual Reality (VR) technology has become increasingly effective and accessible within the past decade [15]. With this increase in the technology’s prevalence and cultural significance, certain interaction techniques and design choices have emerged as the most widely used and recommended. This research effort employs a VR experiment in which multiple selection methods, interface placements, and navigation techniques are compared side-by-side, and performance metrics and preference data are collected. Both best practice and to-be-avoided methods are examined, and the performance and preference data is analyzed. Determinations made based on the data gathered are partly in-line with expectations according to best practices, partly inconclusive, and partly contrary to the expected performance and preference results. Results suggest that virtual laser pointers and tapping are equally recommendable selection methods for most VR experiences, hand-mounted menus produce the best results overall, and despite performance advantages, joystick navigation should be avoided in VR due to user comfort concerns.
    • Better understanding of production decline in shale gas wells

      Harongjit, Kananek; Ahmadi, Mohabbat; Patil, Shirish; Dandekar, Abhijit (2014-08)
      Production data from the Eagle Ford shale (an analog to the Alaska Shublik shale) was collected from two neighboring counties and analyzed to correlate well performance with completion parameters including length of horizontal wellbore and number of hydraulic fracturing stages. Thirty-eight dry gas wells with production history range of 18-43 months were analyzed using 6 different decline curve analysis (DCA) models including Arps' exponential, harmonic and hyperbolic, power law exponential (PLE), logistic growth analysis (LGA) and Duong's models. In the matching process, 2/3 of history was used to tune the DCA models and their forecasts were compared to the remaining 1/3 of real history. The matching results were analyzed based on production history length and flow regime to have better understanding of limitations and capabilities of each DCA model. Reservoir simulation models, constructed using range of realistic data and actual completion practices of 4 select wells, were employed to assess reasonable values of remaining reserve and remaining well life that were used as benchmarks for comparison with DCA results. The results showed that there was no strong correlation between well performance (average first year production rate) and the horizontal leg or the number of fracturing stages. This was an indication of extremely heterogeneous medium. In most cases, the accuracy of the DCA models increased when longer production history was used to tune the model parameters. LGA seems to be the most accurate DCA model since it gave the highest matching accuracy 71% of the total wells when using longest history length of 31 months. As the flow regime is concerned, LGA model also performed very well matched in 57% of the wells exhibiting only transient flow and 63% for the wells showing transient flow during early production time followed by boundary-dominated flow during late production. Moreover, the remaining reserve and well life of the select wells predicted by LGA fell into reasonably close range of the estimates from the reservoir simulations.
    • Bibliography of Arctic Water Resources

      Hartman, Charles W.; Carlson, Robert F. (University of Alaska, Institute of Water Resources, 1970-11)
      In July, 1969, the Institute of Water Resources began a study of Alaska's Arctic water resources in response to the impending resource development of Arctic regions. The intent of the study was to provide a literature review of existing information, a model study of the water system in an Arctic region, and a limited field program. It became quite apparent early in the study that a great amount of literature pertaining to the Arctic water cycle was available and would need extensive organization to be useful. It also became apparent that if the literature were organized, the list would be useful to investigators other than ourselves. The result is this Bibliography of Arctic Water Resources.
    • Bibliography of Published Reports and Articles Related to Hydrological Research on the Sagavanirktok River

      Youcha, Emily; Toniolo, Horacio (2017-08)
      Researchers from the Water and Environmental Research Center (WERC), University of Alaska Fairbanks (UAF), are conducting a study of sediment transport conditions along the Sagavanirktok River. This document, as part of the study, provides a compilation of published literature related to the Sagavanirktok River (or adjacent watersheds with similar characteristics) including previous or ongoing hydrological and sedimentological research in the Sagavanirktok River basin. The literature referenced includes research on climate change, hydrology, sedimentology, permafrost and soils, meteorology, field data, satellite or aerial imagery, geophysics, modeling, water quality, and geochemistry in the Sagavanirktok River basin.
    • Bio-based Renewable Additives for Anti-icing Applications (Phase I)

      Nazari, Mehdi Honarvar; Havens, Eden Adele; Shi, Xianming; Muthumani, Anburaj (Center for Environmentally Sustainable Transportation in Cold Climates, 2016-09-04)
      The performance and impacts of several bio-based anti-icers along with a traditional chloride-based anti-icer (salt brine) were evaluated. A statistical design of experiments (uniform design) was employed for developing anti-icing liquids consisting of cost-competitive chemicals such as bio-based compounds (e.g., sugar beet extract and dandelion extract), rock salt, sodium metasilicate, and sodium formate. The following experimentally obtained parameters were examined as a function of the formulation design: ice-melting capacity and ice penetration at 25°F (−3.9°C) and 15°F (−9.4°C), compressive strength of Portland cement mortar samples after 10 freezethaw/deicer cycles, corrosion rate of C1010 carbon steel after 24-hour immersion, and impact on asphalt binder’s stiffness. One viable formula (“best performer”) was tested for freezing point depression phase diagram (ASTM D1177-88) and the friction coefficient of asphalt pavement treated by this anti-icing formulation (vs. 23 wt.% NaCl) at a certain temperature near 25°F or 30°F after being applied at 30 gallons per lane mile (1 hour after simulated trafficking and plowing). Laboratory data shed light on the selection and formulation of innovative bio-based snow and ice control chemicals that can significantly reduce the costs of winter maintenance operations. This exploratory investigation contributes to more systematic study of optimizing “greener” anti-icers using renewable resources.
    • Bio-Based Renewable Additives for Anti-Icing Applications (Phase II)

      Nazari, Mehdi Honarvar; Oh, Taekil; Ewing, Alexander Charlemagne; Okon, Deborah Ave; Avalos, Brandon; Alnuaimi, Eisa; Havens, Eden Adele; Shi, Xianming (Center for Environmentally Sustainable Transportation in Cold Climates, 2019-01-24)
      The performance and impacts of several agro-based anti-icers along with a traditional chloride-based anti-icer (salt brine) were evaluated. A statistical design of experiments (central composite design) was employed for developing anti-icing liquids consisting of cost-competitive chemicals such as agro-based compounds (e.g., Concord grape extract and glycerin), sodium chloride, sodium metasilicate, and sodium formate. The following experimentally obtained parameters were examined as a function of the formulation design: ice-melting capacity at 25°F (−3.9°C), splitting strength of Portland cement mortar samples after 10 freeze-thaw/deicer cycles, corrosion rate of C1010 carbon steel after 24-hour immersion, and impact on asphalt binder stiffness and m-value. One viable formula (“best performer”) was tested for thermal properties by measuring its differential scanning calorimetry (DSC) thermograms, the friction coefficient of asphalt pavement treated by this anti-icing formulation (vs. 23 wt.% NaCl and beet juice blend) at 25°F after being applied at 30 gallons per lane mile (1 hour after simulated trafficking and plowing), and other properties (pH, oxygen demand in COD). Laboratory data shed light on the selection and formulation of innovative agro-based snow- and ice-control chemicals that can significantly reduce the costs of winter maintenance operations.
    • Bio-Processes of the Oxidation Ditch When Subjected to a Sub-Arctic Climate

      Ranganathan, K. R.; Murphy, R. Sage (University of Alaska, Institute of Water Resources, 1972-05)
      Alaska's far northern area is sparsely populated primarily because of a severe climate which varies from northern temperate to Arctic. Construction and power costs are high. Skilled operating personnel are scarce and expensive, if available. Receiving streams are said to be delicate, particularily in the winter, when little possibility for reaeration exists due to a total ice cover. The oxidation ditch modification of the extended aeration activated sludge process appears to be well suited for the treatment of wastes in this environment. Past operating data on a plant of this type located in Interior Alaska (near Fairbanks) indicated it may be well suited to treat small volumes of domestic waste economically, with low sludge production, and minimal sensitivity to low temperatures.
    • A Bio-Wicking System to Mitigate Capillary Water in Base Course

      Lin, Chuang; Zhang, Xiong (Center for Environmentally Sustainable Transportation in Cold Climates, 2016-11)
      Water within pavement layers is the major cause of pavement deteriorations. High water content results in significant reduction in soil’s resilient behavior and increase in permanent deformation. Conventional drainage systems can only drain gravity water but not capillary water. Both preliminary lab and field tests have proven the drainage efficiency of a newly developed H2Ri geotextile with wicking fabrics. This bio-wicking system aims at resolving the potential issues that the original design may encounter: (1) H2Ri ultraviolet degradation, (2) H2Ri mechanical failure, (3) loss of drainage function under high suction, and (4) clogging and salt concentration. Both elemental level and full-scale test results indicated that the bio-wicking system is more effective in draining capillary water within the base courses compared with original design, in which the geotextile is directly exposed to the open air. However, a good drainage condition is required for the bio-wicking system to maintain its drainage efficiency. Accumulation of excess water will result in water re-entering the road embankment. Moreover, grass root and geotextile share the same working mechanism in transporting water. In the proposed bio-wicking system, the relatively smaller channels in the grass roots further ensures water moving from H2Ri geotextile, transporting through the stems of grass, and eventually evapo-transpiring into the air at the leaf-air interfaces. In sum, the bio-wicking system seemed to successfully address the concerns in the preliminary design and is a more efficient system to dehydrate the road embankment under unsaturated conditions.
    • A Bio-Wicking System to Prevent Frost Heave in Alaskan Pavements: Phase II Implementation

      Galinmoghadan, Javad; Zhang, Xiong; Lin, Chang (2019-11)
      Water within pavement layers is the major cause of pavement deterioration. High water content results in significant reduction in soil’s resilient behavior and an increase in permanent deformation. Especially in cold regions, frost heave and thaw weakening cause extensive damage to roads and airfields. Conventional drainage systems can only drain gravity water not capillary water. Both preliminary lab and field tests have proven the drainage efficiency of a newly developed H2Ri geotextile with wicking fabrics. In this report, continuous research was conducted to verify the effectiveness of the wicking fabric in mitigating frost boil issues in Alaskan pavemnets. Two test sections were selected at two low volume roads on the campus of the University of Alaska Fairbanks. Soil moisture and temperature sensors were installed within the road embankments. The monitored data was used to analyze the soil migrations and evaluate the drainage performance of the wicking fabric. Preliminary monitoring results showed that the wicking fabric was effective in mitigating the frost boil problem.
    • The Biochemical Bases of Psychrophily in Microorganisms: A Review

      Miller, Ann P. (University of Alaska, Institute of Water Resources, 1967)
    • The Biodegradation of Organic Substrates Under Arctic and Subarctic Conditions

      Murray, Ann P.; Murphy, R. Sage (University of Alaska, Institute of Water Resources, 1972-03)
      The objective of this research was to obtain data on the metabolic reaction rates of the microorganisms indigenous to the cold environments of the arctic and sub-arctic in order to evaluate the natural abilities of the freshwater streams and lakes of Alaska to assimilate the wastes discharged into them. Microorganisms capable of growth even at subzero temperatures have long been known; however, most have consistently fared better at higher temperatures, usually above 20° C. Much of the work done with the biological oxidation of wastes at low temperatures has been with organisms of this type : mesophilic organisms which are able to survive at low temperatures but which are metabolically much more active in the temperature range from 20 to 45° C. Such organisms might be labeled "cold-tolerant," but they are probably biochemically quite different from the truly "cold-loving," or psychrophilic, microorganisms which are able not only to survive but also to thrive at temperatures below 20° C and which, in fact, find temperatures much higher than 25° C intolerable.
    • Biodegradation Of Petroleum And Alternative Fuel Hydrocarbons In Moderate To Cold Climate

      Horel, Agota Anna (2009)
      Microbial degradation of hydrocarbon fuels contaminating soil in the Arctic and subarctic environment is a relatively slow process. Nevertheless, due to transportation and logistical limitations in rural Alaska, biodegradation might be the best and cheapest contaminant removal option. The aim of this thesis was to investigate the environmental effects on biodegradation by naturally occurring microorganisms for some innovative hydrocarbon fuels and to determine the overall fate of hydrocarbons in soil, including degradation by fungi and bacteria, volatilization, and transport in the soil. Three major types of fuels were investigated in small scale microcosms and larger soil columns: conventional diesel as a control substance, synthetic diesel (arctic grade Syntroleum) and different types of fish oil based biodiesel. The environmental conditions investigated included different soil types (sand and gravel), different temperatures (constant 6�C, 20�C, and fluctuating between 6 and 20�C), moisture levels (from 2% to 12% GWC), fuel concentrations (from 500 to 20,000 mg fuel/kg soil) and nutrient dosages (0 or 300 mg N/kg soil). Microbial response times and growth phases were also investigated for different inoculum types. Conditions of 20�C, 300 mg N/kg soil, sand, ?4000 mg of fuel/kg soil and ?4% GWC were favorable for bioremediation, with a short lag phase lasting from one day to less than a week, and pronounced peaks of daily CO 2 production between week 2 and 3. At suboptimal conditions, all phases were extended and slow, however at low temperatures steady metabolization continued over a longer time. The relative importance of fungal and bacterial remediation varied between fuel types. Diesel fuel degradation was mainly due to bacterial activities while fish biodiesel degradation occurred largely by mycoremediation. For Syntroleum both bacterial and fungal remediation played key roles. Volatilization contributed up to 13% to overall contaminant removal. In soil columns, degradation was slower than in microcosms, due to an uneven concentration profile of contaminants, nutrients and oxygen with depth. In general, biodegradation showed promising results for soil remediation and the alternate fuel types were more biodegradable compared with conventional diesel fuel.
    • Biogeochemistry of deep lakes in the central Alaskan Range: Completion report

      LaPerriere, Jacqueline; Casper, Lawrence (University of Alaska, Institute of Water Resources, 1976-02)
      Casper, one of the investigators, was a guest of the National Park Service as a weekend camper at the Wonder Lake Campground within Mount McKinley National Park. On the next visit to this campground for the same purpose, Mr. Casper took along several pieces of equipment for making simple limnological measurements. On this trip, he was accompanied by Frederick Payne, a graduate student from Michigan State University, who was in Alaska working with aquatic plant community structure. Following this visit to the lake, a research project proposal was drawn up for the purpose of obtaining funds in order to study several limnological aspects of this lake and others related to it. The relative high importance of vascular aquatic plant production in the Arctic had been noticed by John Hobbie (1973). In an intensive study of a deep subarctic lake, Harding Lake, being conducted by the Institute of Water Resources, University of Alaska, the relative high importance of rooted aquatic plants had also been noted. Thus, a question arose as to whether or not the primary production of vascular aquatic plants is higher than that of phytoplankton in subarctic lakes as is the case in arctic lakes which usually have higher biomass concentrations of algae than subarctic lakes (Hobbie, 1973). The stated objectives of this project were: 1) To conduct a biogeochemical reconnaissance of selected deep subarctic lakes in the central Alaska Range. 2) To develop hypotheses concerning the regional limnology. 3) To collect biological specimens to extend knowledge of taxonomic distributions, especially of aquatic plants and phytoplankton. 4) To estimate the seasonal nutrient budget for these lakes.