Exploratory Analysis of the Winter Chemistry of Five Lakes on the North Slope of Alaska1

Abstract: Lakes are important water resources on the North Slope of Alaska. Freshwater is required for oilfield production as well as exploration, which occurs largely on ice roads and pads. Since most North Slope lakes are shallow, the quantity and quality of the water under ice at the end of winter are important environmental management issues. Currently, water‐use permits are a function of the presence of overwintering fish populations, and their sensitivity to low oxygen concentrations. Sampling of five North Slope lakes during the winter of 2004‐2005 shed some light on the winter chemistry of four lakes that were used as water supplies and one undisturbed lake. Field analysis was conducted for oxygen, conductivity, pH, and temperature throughout the lake depth, as well as ice thickness and water depth. Water samples were retrieved from the lakes and analyzed for Na, Ca, K, Mg, Fe, dissolved‐organic carbon, and alkalinity in the laboratory. Lake properties, rather than pumping, were the best predictors of oxygen depletion, with the highest dissolved‐oxygen levels maintained in the lake with the lowest concentration of constituents. Volume weighted mean dissolved‐oxygen concentrations ranged from 4 to 94% of saturation in March. Dissolved oxygen and specific conductance data suggested that the lakes began to refresh in May.     

Growth of Uronema marinum in chemically defined medium

A strain of the marine hymenostome ciliate Uronema marinum was isolated in axenic culture. This strain, designated PW2, was cultivated in a chemically defined medium containing 17 amino acids, 4 nucleotides, 5 fatty acids, stigmasterol, 8 growth factors and an artificial sea water. Increased populations were observed when either phosphatidylinositol or Tween 80 were included in the medium. The vitamins thiamine, riboflavin, pyridoxal, nicotinamide, folic acid and pantothenate were required by U. marinum PW2. No requirement could be demonstrated for exogenous thioctic acid or biotin, although growth was diminished in their absence. The amino acid and nucleotide requirements were found to be higher than the levels reported for other ciliates. This strain was found to be euryhaline, with maximum growth observed in media of specific gravity 1.007, corresponding to approximately 25% sea water. Although no requirement could be demonstrated for Fe, Zn, Mn or Cu, high levels of these metals were observed to be toxic. Growth was observed over a pH range of 6.6 to 8.3, with an optimum observed near 7.3.     

Adapting to climate change: the role of organisational personalities in natural resource management

Regional Environmental Change - Preparing for climate change represents a significant challenge to environmental managers and is influenced by their ability to access and use the latest...     

Chemical and Physical Controls on the Oxygen Regime of Ice‐Covered Arctic Lakes and Reservoirs1

Abstract: We examined the chemical, morphological, and anthropogenic controls on winter‐oxygen biogeochemistry in ice‐covered lakes and reservoirs on the North Slope of Alaska. We measured dissolved oxygen (DO), solute concentrations, water depth, and ice thickness at three natural thaw lakes and four reservoirs (flooded gravel mines) for two winters. In all seven study sites, DO concentration and pH decreased with depth, and temporally through the winter (November to April). DO concentration was four to six times greater in the deeper reservoirs (8‐13 mg/l) compared with shallow natural lakes (ca. 2 mg/l). Lakes and reservoirs with high dissolved organic carbon (DOC) concentration were susceptible to large decreases in oxygen over the winter. DO concentration differed markedly between years, but was not attributed to changes in water‐use or winter water‐chemistry. Alternatively, we suggest that dissolved oxygen concentration was lower during freeze‐up, possibly associated with higher lake‐productivity during the summer. Our results suggest that current water‐use practices on the North Slope of Alaska caused little to no change in DO concentration over the winter. In particular, considering the high pumping activity and shallow depth, lakes with low DOC concentration (≤6 mg/l) showed strong resilience to change in chemistry over the winter. We suggest that both lake and reservoir depth, and DOC concentration are key factors influencing oxygen consumption in ice‐covered arctic lakes and reservoirs.     

Use of Synthetic Aperture Radar for Selecting Alaskan Lakes for Winter Water Use1

Abstract: Water resources are limited in many areas of the North Slope, Alaska, particularly during winter. Water is used by the oil industry for ice road construction and maintenance, drilling and facility operations, and potable water supplies. The coastal plain between Teshekpuk Lake, in the National Petroleum Reserve‐Alaska (NPR‐A) and the Colville River has numerous shallow lakes, but further south in the northern foothills of the Brooks Range, and east to the Canning River, lakes are fewer. While many oil and gas lease sales have been conducted, or are proposed, access to the leases may be limited because of the lack of available water for ice road construction. Ice roads are the main means by which exploration is conducted in the Arctic, putting a stress on freshwater bodies that do not freeze to the lakebed in winter. Lakes that do not freeze to the lakebed also serve as overwintering habitat for fish. The purpose of this paper is to report on the potential distribution of water bodies that may provide overwinter water in selected areas from Teshekpuk Lake to the Canning River. The project used synthetic aperture radar (SAR) imagery to search for the presence of water in lakes in March 2006. In the Kuparuk and Canning SAR images, 52 and 61% of lakes were frozen to their beds by March 2006, accounting for 49 and 57% of the lake area in these study regions. Conversely, only 2% of the lakes in the Teshekpuk region were frozen to the bottom by March 2006. Unfrozen water was more available because of deeper and more numerous lakes in the Teshekpuk Lake region (west) than in the Canning River area (east). While only specific SAR tiles were analyzed herein, the method will be a useful tool for land managers who seek to evaluate the potential for ice road construction across the Arctic.     

Climate adaptation of food value chains: the implications of varying consumer acceptance

Despite there being considerable research and knowledge surrounding the risks of climate change on agricultural productivity, fewer studies have examined risks from a whole-of-chain perspective (i.e. from producer to consumer) and the perceptions of consumers about the climate adaptation strategies of food businesses. This paper presents the findings of a survey of 1532 Australian consumers and how they might respond to a food company’s climate adaptation strategy. Three respondent archetypes, ‘Eco-warriors’ (n = 557), ‘Undecideds’ (n = 600) and ‘Abdicators’ (n = 375), were identified based on their perceptions of risks associated with climate change and their attitudes towards climate adaptation. Further analysis was carried out to understand how each group of respondents would respond to adaptation strategies employed by food companies. Based on the findings of this study, two main challenges are presented for food value chains: (1) translating consumer needs and preferences to niche opportunities arising from adaptation and (2) understanding how best to communicate adaptation benefits based on varying attitudes and information needs. By addressing these challenges, synergies between adaptation goals and competitive strategies in food value chains may be achieved.     

A Tool for Modeling the Winter Oxygen Depletion Rate in Arctic Lakes1

Abstract: Many arctic lakes freeze completely in winter. The few that retain unfrozen water for the entire winter period serve as overwintering fish habitat. In addition to serving as fish habitat, water in arctic lakes is needed for industrial and domestic use. Permits for water extraction seek to maximize water use without impacting dissolved oxygen (DO) levels and endangering fish habitat. The relationship between lake volume, winter DO budget, and extraction of water through pumping has historically not been well understood. A management model that could estimate end‐of‐winter DO would improve our understanding of the potential impacts of different management strategies. Using under‐ice DO measurements (November to April) taken from two natural lakes and one flooded gravel mine on the North Slope of Alaska, a physically based model was developed to predict end‐of‐winter DO concentration, water‐column DO profiles, and winter oxygen depletion rate in arctic lakes during periods of ice cover. Comparisons between the measured and model‐predicted oxygen profiles in the three study lakes suggest that the depth‐based DO modeling tool presented herein can be used to adequately predict the amount of DO available in arctic lakes throughout winter.     

Urban heat island intensity and evaluation of outdoor thermal comfort in Chennai,India

Environment, Development and Sustainability - The variation in the atmospheric conditions of urban areas to the fringe areas is termed as urban heat island and is attributed predominantly to the...