Abstracts of the

IX International Conference on Salt Lake Research

September 26 – 30, 2005; Perth Australia

Hosted by

Curtin University of Technology, Bentley, Western Australia

&

The International Society for Salt Lake Research (http://www.issslr.org)

Jacob John, Conference Secretariat (j.john@curtin.edu.au)

FREEZE DESALINATION USING CLATHRATE HYDRATES

Aral H.¹, Norgate T.

¹CSIRO Minerals, Bayview Ave., Clayton, VIC 3169, Australia

Freeze desalination is an alternative process to reverse osmosis and evaporation for desalinating water. The process is based on the fact that dissolved salts are naturally excluded during the formation of ice crystals. The non-frozen saline component is removed at the appropriate time in the freezing process, and the frozen (fresh) water is washed to remove any remaining salts adhering to the ice crystals. The ice is then melted to produce fresh water.

The desalination of seawater to date has been limited to high cost processes such as distillation and reverse osmosis (RO). Only the countries that are able to pay a high price, mainly the Middle East and tourist destination Pacific islands, have made use of these technologies to a large extent. Desalination processes using RO technology produce potable water in Southern California at (year 2000) prices ranging from US$1.06 to US$1.59 per m³. Multiple effect distillations are more expensive than RO desalination and they require a cheap source of energy, as in Arab Peninsula countries. Furthermore, distillation-based desalination methods require large water production capacities to lower the costs. This makes it unsuitable for mineral processing plant applications and small inland town usage in Australia.

Freeze desalination inherently uses the least amount of energy. About 100 cal/g energy is needed to convert water at 20°C to ice. In conventional distillation processes the energy required to keep the water boiling is about 620 cal/g, therefore, freezing uses only 1/6 as much energy as boiling. In freeze desalination heat could be recovered to melt the ice.

There are several processes for desalinating the seawater by freezing. Some of these ideas have been investigated through various stages of development. The indirect process is the simplest, where freezing is accomplished by circulating a cold refrigerant through a heat exchanger that removes heat from the seawater through conduction. The ice is formed on the heat exchanger surface and then must be removed, washed and melted with incoming (feed) water.

There are a number of direct freezing processes where the heat from the cold seawater is removed by direct contact of the refrigerant with the seawater. Among them clathrate desalination is the most important as it has the lowest energy requirement. This was achieved by pumping the clathrate to ocean depth of 600m through a concentric-coaxial pipeline where the temperature of the water at that depth (5 to 10^oC) is suitable for clathrate hydrate formation. At this depth clathrate combines with the water to form slurry of clathrate ice crystals and brine. This slurry is sucked back to the surface through the outer pipeline, filtered to obtain clathrate ice, which is then washed with small amount of fresh water and melted to obtain potable water. The clathrate molecule is regenerated for reuse. The method therefore did not require any refrigeration energy input. The cost of potable water made in this way was estimated as US$0.50 to 0.70 per kilolitre.

At CSIRO Minerals, as the first part of a preliminary evaluation of freeze desalination processes, an estimate was made of the electrical power cost for operating a typical indirect freeze desalination plant in inland Australia.

In this paper the work done in the freeze desalination area in CSIRO will be described. The importance of the clathrate hydrate type freeze desalination will be emphasized based on the literature data.

SEASONAL DYNAMICS OF ZOOPLANKTON IN A SHALLOW EUTROPHIC, MAN-MADE HYPOSALINE LAKE IN DELHI (INDIA): ROLE OF ENVIRONMENTAL FACTORS

Arora J.¹, Mehra N.K.¹

¹Limnology Unit, Department of Zoology, University of Delhi, Delhi 110 007, India.

Physicochemical and biological characteristics of Old Fort Lake were studied in monthly surveys during two consecutive years (January 2000 – December 2001). The principal objective was to elucidate the influence of different environmental variables on the seasonal succession of zooplankton assemblages using Canonical Correspondence Analysis (CCA).

This small (1.6 ha), shallow, eutrophic and recreational water body is located in Delhi, which lies in the subtropical semi-arid zone of northern India. Originally, it was a wide moat surrounding the Old Fort, which was constructed by the Mughal emperor Sher Shah Suri during 1538 to 1545 A.D. In ancient times, the lake was connected to river Yamuna, however, presently the lake represents a closed hydrological basin. Rainwater is the major source of water. In addition, groundwater drawn through tube wells is used for replenishing the lake regularly.

This alkaline, hyposaline (TDS: 3.0 – 10.3 gL^-1) and hard water lake contains very high ionic concentration, especially nitrates. Based on overall ionic composition, this lake can be categorized as chloride-sulphate alkaline earth waters with the anion sequence dominated by SO₄^2- > Cl^- > HCO₃^-, and the cations by Mg⁺⁺ > Ca⁺⁺. The Principal Component Analysis (PCA) indicates that the annual cycle of evaporation and precipitation largely regulates the overall seasonal variability in physicochemical profile. However, the ground water largely influences its water quality.

A total of 52 species of zooplankton were recorded. The rotifers dominated the community structure both qualitatively as well as quantitatively. The genus Brachionus comprised a significant component of zooplankton community with B. plicatilis as the most dominant species. B. quadridentatus, B. angularis, Lecane grandis, L. thalera, L. punctata, Mesocyclops sp. and Alona rectangula were the common taxa. The significant environmental variables selected by CCA that explain maximum variability in the zooplankton species data were NH₃-N followed by percent saturation of DO, COD, SS, BOD, NO₂-N, rainfall, silicates and PO₄-P.

AVIAN HABITAT USE IN SALINITY GRADIENT IMPOUNDMENTS

Barnum D.A.¹, Anderson T.¹

¹U.S. Geological Survey, La Quinta, CA USA

Avian use of salinity gradient environments such as agricultural/industrial evaporation ponds (Tanner et al. 1999), artificial salt ponds (Anderson 1970, Britton and Johnson 1987, Carmona and Danemann 1998, Masero and Perez-Hurtado 2001, Takekawa et al. 2001), natural salt flats (Velasquez and Hockey 1992, Collazo et al. 1995), and estuaries (Ysebaert et al. 2000) has been documented at numerous sites around the world. Generally, it is found that waterbird abundance is seasonally high due to use by migrating birds. During migration, birds usually require refueling stops which makes prey availability an important factor in determining their distribution, both on a landscape scale and within a particular habitat (Myers et al. 1987, Haig et al. 1998). Many studies have found salinity gradient habitats, particularly ones with hypersaline areas, provide a stable, abundant prey base that can be utilized by birds year around (Britton and Johnson 1987, Tanner et al. 1999, Masero 2003). For any particular habitat to be suitable to birds the prey must also be accessible. Different bird species have different water depths in which foraging is ideal (Burger 1984, Takekawa et al. 2001). For these reasons, an area providing many different aquatic habitats comprised of a variety of salinities and water depths has the potential to meet the needs of the greatest number and diversity of waterbirds. This concept of a mosaic of habitats has developed quite recently and there are several studies which have assisted in the evolution and understanding of this management technique. In a recent study by Takekawa et al. (2001) bird use of hypersaline salt ponds was compared to that of the other bayland wetlands. For the period from 1982-1999 the overall abundance and diversity of birds on the mosaic of bayland habitats was greater than found on the salt pond habitat, however, the density of birds on the salt ponds was greater than on the remaining baylands (Takekawa et al. 2001). The greater diversity of birds using the non salt pond wetlands is supported by the ecological theory of increased biological diversity with increased spatial/structural heterogeneity (Krebs 1991). Meanwhile, the greater density of birds found in the hypersaline salt ponds was attributed to shorebirds attracted to the combined factors of shallow water habitat (< 10 cm) in which to forage and the temporally more consistent prey availability (Takekawa et al. 2001). Studies of bird use of agricultural wastewater ponds in Central California indicated some dramatic relationships between salinity, invertebrate productivity and bird numbers (Barnum unpubl data). The implications of managing mosiacs of fresh and salt gradient wetlands for ecosystem restoration are explored.

SCIENCE OF THE SALTON SEA. RESTORATION OF AN IMPORTANT INLAND SALINE LAKE IN THE SOUTHWESTERN UNITED STATES.

Barnum D.A.¹, Hurlbert S.H.²

¹U.S. Geological Survey, La Quinta, CA USA. ²Department of Biology, San Diego State University, San Diego, CA USA

The Salton Sea is the latest waterbody to be formed by Colorado River floodwaters within the geographic area known as the Salton Trough. All of the previous water bodies evaporated to dryness because of an evaporation rate of 5.6 feet per year and rainfall of less than 3 inches per year. Unlike the pervious water bodies of the same location, the Salton Sea has not evaporated to dryness because it has a permanent water source. Most of the water reaching the Salton Sea is agricultural drainwater flowing down the New, Alamo and Whitewater Rivers. Waters reaching the Salton Sea have essentially been in equilibrium with evaporation (approximately 1.34 million acre feet) for more than a decade. The result is California’s largest inland water body with a length of approximately 35 miles, a maximum width of 15 miles and a maximum depth of 51 feet (average of about 30 feet). The current Salton Sea Restoration Project was initiated in January 1998 and is the first effort to have a major focus on the bird and fish life of the Salton Sea. The Salton Sea has become increasingly important as habitat for migratory birds of the Pacific Flyway and adjacent areas because of wetland and other habitat losses. California leads the nation with a loss of 91 percent of interior wetland acreage from pre-settlement until the mid-1980’s. In total, approximately 95 percent of the historic interior wetland acreage has been lost or severely impacted. Less than 0.4 percent of the surface area of California is currently comprised of wetlands. Those losses and other habitat losses within the western United States and Mexico have resulted in the Salton Sea becoming an important “mitigation waterbody” for sustaining migratory birds of the Pacific Flyway and it is a critical habitat linking distant wetlands of Pacific and Central Flyways to wintering habitats in Mexico and Central and South America.

The high rate of evaporation of surface waters results in a continual increase in the salinity of the waters of the Salton Sea. The current salinity level of approximately 46 parts per thousand (ppt) is about 25 percent more saline than ocean water (35ppt). Because most of the water reaching the Salton Sea is agriculture and municipal drainwater there is a high loading of nutrients that make the lake hypereutrophic.

The current equilibrium between inflows to the Salton Sea and evaporation has resulted in a low annual rate of increases in salinity (less than 0.5 percent per year). Arresting salinity as a means for sustaining the fishery of the Salton Sea is a major focus for the Salton Sea Restoration Project. Other issues associated with the manner in which water transfers may occur including selenium, air quality issues associated with the amount of the current Salton Sea that will become dry, loss of migratory bird habitat as the lake level recedes, and loss of recreational and economic development are additional major focal points of this project. The USGS Salton Sea Science Office has initiated integrated efforts to evaluate nutrient dynamics/modeling, contaminant risk assessments for migratory birds and human health, evaluations of various restoration alternatives, avian population dynamics, contaminant burden profiles in birds and fish, air quality related studies including sediment characterization of the Salton Sea lake bed and emissions data analysis, larval fish abundance and distribution data analysis, salinity tolerance limits for fish, pileworm population abundance and distribution, and wetland habitat restoration. Results of these comprehensive studies have been published in peer-reviewed scientific journals in several dozen individual articles. Proceedings of a symposium held in 2000 were published in Hydrobiologia. A more recent symposium on science of the Salton Sea was held in late March 2005 and the edited proceedings will similarly be published in Hydrobiologia. Results from these peer-reviewed studies have been incorporated in the development of a science-based alternative for restoration of the Salton Sea. Restoration alternatives are under development by the State of California with a legislated deadline of December 2006. The Science Office remains involved in the conduct of original science and serves as the overall science program coordinator. As the program moves forward into an adaptive management phase, feedback from scientific investigations and integrated monitoring activities will interact with programmatic decisions for restoration planning.

ACID SALINE LAKES IN AUSTRALIA: CLUES TO PAST ENVIRONMENTS AND LIFE AT MERIDIANI PLANUM, MARS?

Benison K.C.¹, Bowen B.B.¹, Mormile M.R.², Oboh-Ikenobe F.E.³

¹Department of Geology, Central Michigan University, Mt. Pleasant, Michigan, U.S.A. ²Department of Biology, University of Missouri, Rolla, Missouri, U.S.A. ³Department of Geological Sciences and Engineering, University of Missouri, Rolla, Missouri, U.S.A.

The many space missions dedicated to exploring Mars, including the recent Mars Exploration Rovers (MER) mission, have accumulated intriguing images of Mars’ surface and chemical analyses of Mars’ atmosphere, sediments, and rocks. Of particular interest are the bedded sedimentary rocks of the Burns Formation at Meridiani Planum. Compositional analyses of these Martian rocks strongly suggests that they were deposited by acid saline surface waters and ground waters (Kargel, 2004; Squyres et al., 2004a, 2004b). For example, the rocks contain jarosite, a mineral formed only by acid waters on earth, as well as hematite and sulfate minerals. This mineral suite is rare on earth, but is a criterion for the recognition of acid saline deposition in terrestrial settings (Benison and Goldstein, 2002).

Sedimentary structures seen in the MER images of the Meridiani Planum sedimentary rocks include bedding, cross-bedding, ripple marks, mudcracks, and displacive evaporite crystals. This group of features are suggestive of ephemeral shallow saline lake waters and groundwaters. These sedimentary structures are all common in terrestrial ephemeral saline lakes.

The striking similarities in composition and sedimentary structures make acid saline lakes the best terrestrial analog for the sedimentary rocks of Mars. Acid saline lakes in southern Western Australia and northwestern Victoria seem to be some of the few natural types of these unusual environments and, therefore, may be the best modern terrestrial analog for past environments on Mars.

The best way to search for signs of past life on Mars may be to first inventory, and then understand, organisms in terrestrial analog environments. Only then will planetary paleontologists know what kinds of fossils to look for in Martian rocks.

Preliminary biological investigations of the Australian acid saline settings suggest that algae and bacteria may be the dominant life forms there. These may be the closest living things to possible past life on Mars.

BROADSCALE ANALYSIS OF PLAYA FILLING IN THE YARRA YARRA DRAINAGE SYSTEM, WESTERN AUSTRALIA.

Boggs G.S.¹, Boggs D.A.²

¹GIS and Remote Sensing Group. Building 18, Charles Darwin University, Casuarina, Northern Territory, Australia, 0909. ²School of Earth and Geographical Sciences. The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009.

Rainfall disparity across the Yarra Yarra catchment produces variable spatial and temporal patterns in playa filling frequency and hydroperiod. The distribution and permanence of water in the playas has numerous geomorphological, hydrochemical and ecological implications including creating variability of habitat for a range of aquatic organisms and migratory waterbirds. AVHRR satellite data from May 2002 to May 2005 were used to map broadscale events in playa filling frequency and hydroperiod. These patterns were analysed in relation to catchment and rainfall characteristics to produce a simple filling model.

THE ROLE OF ZOOPLANKTON IN THE ECOLOGICAL SUCCESSION OF PLANKTON AND BENTHIC ALGAE ACROSS A SALINITY GRADIENT IN THE SHARK BAY SOLAR SALT PONDS.

Bruce L.C.¹, Imberger J.¹

¹Centre for Water Research, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia.

The relatively low biodiversity and simple hydrodynamics make solar salt ponds ideal sites for ecological studies. We have studied the ecological gradient of the primary ponds at the Shark Bay Resources solar salt ponds, Western Australia using a coupled hydrodynamic ecological numerical model, DYRESM/CAEDYM. Seven ponds representative of the primary system were simulated with salinity ranging from 45 to 155 ppt. Six species were simulated, three phytoplankton, two microbial mat plankton, and one zooplankton as well as dissolved inorganic and particulate organic nitrogen, phosphorus and carbon. By extracting the various carbon fluxes from the model we determined the role that the introduced zooplankton, Artemia parthenogenetica play in grazing the particulate organic carbon from the water column in the high salinity ponds. We also examined the nutrient fluxes and stoichiometric ratios of the various organic components for each pond to determine the role that A. parthenogenetica play in the nutrient dynamics of the salt pond system.

A COMPARISON OF THE CYST SHELL MORPHOLOGY OF TWO PARARTEMIA SPECIES (CRUSTACEA: ANOSTRACA) FROM WESTERN AUSTRALIA

Campagna V.S., John J.

Department of Environmental Biology, Curtin University of Technology, GPO Box U1987, Bentley, Western Australia, 6845.