Natural Salt Lakes Research Articles

Food Chain Organisms in Hypersaline, Industrial Evaporation Ponds

Evaporation ponds are becoming widely used by industry and agriculture for the disposal of brines as a result of increasingly strict regulations pertaining to off-site disposal methods. Migratory waterfowl and other wildlife can become reliant on such ponds, which can present biological hazards depending on the chemicals they receive. This study examined the algae, invertebrates, and chemistry of two large, hypersaline, industrial wastewater ponds near Phoenix, Arizona, at which waterfowl die-offs (primarily eared grebes, Podiceps nigricollis) were reported. The objectives were to determine what attracted birds to the ponds and whether the ponds were directly responsible for bird deaths. High levels of total salts and nitrate were detected in both ponds, but selenium (16 to 41 μg/L) was the only potentially toxic element that reached levels of concern in the water column. Dominant algae were diatoms, Chaetoceros sp. and Nitzschia frustrulum (Kurtz.) Grun. (up to 6.5 × 105 cells/mL), and cyanobacteria. Synechococcus Nageli 1849 (up to 8.8 × 106 cells/mL). These are normal components of hypersaline ponds and natural salt lakes. However, Chaetoceros levels were negatively correlated with salinity levels in the ponds and a species turnover is expected as ponds age. Primary aquatic fauna were Artemia franciscana (brine shrimp), a filter feeder that consumes algae, and Trichocorixa sp. (waterboatman), a carnivorous insect that presumably feeds on brine shrimp. Brine shrimp were the primary attractant of birds; they were harvested by numerous resident and migratory waterfowl. Selenium levels in brine shrimp (2 to 10 mg/kg) were above recommended levels for food chain organisms in aquatic ecosystems but were well below levels that can cause acute toxicity. Brine shrimp fed to zebra danios fish (Brachydanio refio) in a bioassay were nontoxic. As at other locations where grebe mortality events have been reported in recent years, the cause of death of birds visiting these evaporation ponds is unknown. Therefore, it is concluded that these ponds may not be directly toxic to visiting wildlife, but that evaporation ponds such as these are attractants for wildlife and may pose a long-term hazard through the accumulation of selenium in the food chain. Zero-discharge evaporation ponds may be useful as an interim solution to the brine disposal problem but do not represent a safe, permanent solution.

Brine Chemistry of Groundwater Discharge Zones in the Murray Basin, Australia

Control of rising groundwater levels in Australia's Murray Basin requires the pumping of groundwater, and natural salt lakes seem ideal areas in which to dispose of the pumped water. A thorough understanding of the interaction of chemical and physical processes in particular geologic settings should be the basis for selection and management of appropriate disposal sites. In this work we use chemical modeling to predict the equilibrium evolutionary path of evaporating brines in two operating disposal basins and two natural salt lake complexes in the Murray Basin. Evaporative brines from an engineered and a natural, salt lake, groundwater disposal basin showed close correspondence with the predicted equilibrium evaporation pathways for the relevant inlet waters. There was no evidence of re‐solution of salts during evaporation in the salt lake disposal basin. The predicted evaporite suites for these two disposal basins differ because the inlet waters are derived from different sedimentary regions of the basin. In the two natural salt lake complexes studied, the comparison of field samples with predicted evaporation of regional groundwater indicates that brine evolution is a complex process of evaporation and re‐solution of salts, and this is strongly influenced by the lithostratigraphic setting. Re‐solution is favored where thick clayey sediments overlie the regional, unconfined aquifer, and such a site is favorable for disposal of pumped groundwater.

Salt availability in Turkey and its potential use in solar ponds

Natural salt lakes with temperature gradients are briefly reviewed. Previous work on artificial solar ponds for energy production is also examined. The experience gained from more than twenty non-convecting solar ponds encourages their economic utilization in the future. In addition to the technical and physical requirements for solar pond construction, four basic requirements (sunshine, land, water and salt) are pointed out. In Turkey, these are abundantly found. Salt is the most important and expensive element, constituting about 15–20% of the initial investment of a solar pond. Salt can also be regarded as a complementary “fuel” for a solar pond, since it should be continuously replenished during the operation of the system. In this respect, salt resources in the country were studied. It is recommended that a survey over the Salt Lake be carried out to discover possible natural temperature gradients for heat generation.

Utilización de los barros en Portugal: pasado y presente

Peloid are "products formed by spontaneous or artificial mixture of natural mineral water, sea water or salt lake, with a solid component (organic or inorganic), resulting from biological or geological processes (or both) in the natural state or after preparation, are used topically for therapeutic purposes in the form of poultices or baths "(VI Conf. Int Soc Med Hydr., 1949). Thus considered, the peloid in the natural state or after preparation (ripening) have therapeutic interest for the use of its thermal effect, nonspecific, but they also will be important to consider their specific effect dependent on their physical and chemical composition (silica, Biogel existing or developed during the maturation process, and the consequent enrichment sulfurárea ion, formation of reducing or oxidizing substances, humic acids and other compounds of steroid structure, etc.).. In this specific effect is important to consider the effect scaly (silica and sulfur), buffering (colloidal silica), antiseptic (sulfur), anti-inflammatory (resolving power, chlorinated waters; action of humic acids and other steroid structure, sulphurous waters). In Portugal, and for many years, were used: a) natural peloids - of the Cucos Spa, Torres Vedras (hipertonic waters, sodium chloride, silica) and the Azores, among others in the Thermal Furnas (hipertonic water, sulphurous, and alumina silicate, some ferruginous). b) artificial peloids - made from sludge deposits collected from the bed of the Vouga river, near Aveiro, and properly cleaned and prepared for further maturation in tanks fed the sulphurous water 37-39° C for 6 months, so to acquire a very high amount of sulfurárea, a practice used for years in Vizela and Aregos spas. c) Each other and were later used in the treatment of rheumatic diseases and other musculoskeletal disorders or therapy eczematous dermatoses (eg psoriasis). d) In the early 90s of last century, everything changed: First, the closure of of Cucos spas (who are awaiting restoration), then under the law but produced and which increased the accuracy of microbiological control the use of mineral water at the spa, or by simultaneous economistic strategy, Vizela and Aregos spas stopped growing artificial maturation of peloid. In its place, began to use something they call "muds", sometimes mixed with paraffin ("muds") and are nothing more than "extemporaneous preparations" of any product purchased elsewhere abroad loamy, mixed on thermal water and put the heat to high temperature in a "pot of stainless steel" (which, as a rule, receive more pompous other names). In most cases, the application of such "products" will be completed in poultices hot (40-45° C) that most do not act other than as "moist heat" nonspecific and, as such, the Portuguese law of 2004, should not be considered "thermal techniques" but only "complementary techniques," since they can not be recognized Crenotherapy effect. Such practice, however and unfortunately, has become widespread in many of the spas in Portugal, in abusive use of the name of "muds" which, in our view, does nothing to dignify hydrotherapy. Across the thalassotherapy, Portugal has some areas with "marine mud," natural and some quality, some enriched with various types of algae that naturally mature in these deposits, such as the beach of Foz do Minho, Consolation Beach (Peniche) Praia do Meco (Caparica) and some of the Algarve coast. Unfortunately, such "marine mud" have only been exploited by people spontaneously, without any organized therapeutic environment. Is it time to produce adequate legislation for the SPA, similar to what exists for Thermal Therapy, and from there develop a correct therapeutic use of marine mud.