Salt Lakes In Australia Research Articles

Mineralogy and Physico-Chemical Data of Two Newly Discovered Halloysite in China and Their Contrasts with Some Typical Minerals

We report in this article the systematical acquisition of physico-chemical parameters for two newly discovered halloysite (Hal) minerals from Shiyan and Tongling in China. As the comparative reference, the data from Hal in Linfen, Chenxi, and the salt lake in Australia (samples were abbreviated as Hal-AU, Hal-SY, Hal-LF, Hal-CX and Hal-TL, respectively) were also investigated using X-ray diffraction (XRD), scanning electronic microscopy (SEM), transmission electron microscopy (TEM), Fourier transformation infrared spectroscopy (FTIR), differential scanning calorimetry-thermogravimetry (DSC-TG), X-ray fluorescence, surface zeta potential measurements and N2 adsorption-desorption isotherms. The newly found minerals were probably formed in hydrothermal leaching and sedimentary circumstances. The Hal-SY contains 7 Å-halloysite and dickite, while Hal-TL contains 10 Å-halloysite with some alunite (similar with Hal-CX). Other impurities found in the samples include quartz, gibbsite, iron oxide and anatase. All of them showed tubular morphology with diameter in the range of 30–90 nm and a length of 300–2500 nm, while the Hal-SY has the largest inner diameter to about 150 nm. Specific surface areas varied from 26.0~59.0 m2·g−1. In addition, maximum CEC (cation exchange capacity) of the newly found Hal was about 40 cmol/kg, while that of Hal-AU was relatively low (8 cmol/kg) due to the sedimentary nature of Salt Lake circumstances. The surface charge was predominantly negative over most of the relevant pH range (>2.0). It can be concluded that the different morphology and impurity content of halloysite will greatly affect the surface area, pore volume, and cationic exchange capacity (CEC) of the minerals.

Tolerance of extreme salinity in two stem-succulent halophytes (Tecticornia species).

Communities of Tecticornia on the margins of ephemeral salt lakes in Australia often exhibit species zonation, such as at Hannan Lake (Western Australia) where Tecticornia indica subsp. bidens (Nees) K.A.Sheph. and Paul G.Wilson occupies the less saline dune habitat on lake margins and Tecticornia pergranulata (J.M.Black) K.A.Sheph. and Paul G.Wilson subsp. pergranulata occupies both the dunes and the more saline and moist lake playa. Here we tested the hypothesis that these two species differ in tolerance to extreme salinity. Plants were grown in drained sand cultures with treatments of 10-2000mM NaCl for 85 days. Both species were highly salt tolerant, maintaining growth at treatments of up to 2000mM NaCl, although the death of two replicates of T. indica at 2000mM NaCl suggests this salinity is close to the species tolerance limit. Both Tecticornia species maintained a favourable gradient in tissue water potential via osmotic adjustment as external salinity increased, also with reduced tissue water content at very high external salinity. Regulated accumulation of Na+ and Cl-, maintenance of net K+ to Na+ selectivity, high tissue concentrations of glycinebetaine and presumed cellular solute compartmentation, would have contributed to salt tolerance. The growth rate of T. pergranulata was 11-29% higher than T. indica suggesting, in addition to these moderate differences in salinity tolerance, other factors are likely to contribute to species zonation at salt lakes. The higher water use efficiency of the C4 T. indica compared with the C3 T. pergranulata may provide an advantage in the drier dune habitat on salt lake margins. An additional experiment confirmed the hypothesis that survival of T. pergranulata seedlings is enhanced by the duration of reduced salinity after germination, as would occur following significant rainfall, as older seedlings maintained higher growth rates during subsequent increases in salinity.

Salinity and waterlogging tolerances in three stem-succulent halophytes (Tecticornia species) from the margins of ephemeral salt lakes

Background and aims Tecticornia species are stem-succulent, perennial halophytes (sub-family Salicornioideae; Chenopodiaceae) that inhabit saline areas including the margins of ephemeral salt lakes in Australia. Based on zonation observed at salt lakes, species were hypothesised to differ in tolerances to salinity and/or waterlogging.

A study of the salt lakes and salt springs of Eyre Peninsula, South Australia

An 18-month-study of 40 saline wetlands, ranging from 6 to 336 g l−1, on the west and southern coasts of Eyre Peninsula yielded 88 species of invertebrates, some aquatic plants and a fish. The invertebrates are taxonomically diverse and include 38 crustaceans, 28 insects, 12 molluscs and significantly an aquatic spider, a nemertean, two polychaetes, two sea anemones, a sponge and a bryzoan. Most were tolerant of wide fluctuations in salinity, there being 51 halobionts, 21 halophils and only 16 salt-tolerant freshwater species. Many invertebrates are restricted to the thalassic springs where marine molluscs dominated. Athalassic wetlands were dominated by crustaceans and were of two basic types—coastal and continental. There is evidence of the former evolving biologically into the later, and for some lakes to be still in transition. There is also evidence of increasing salinity in recent decades and already two lakes exhibit severe secondary salinity. Like other salt lakes in Australia the fauna is regionally distinctive.

The biology of the saline lakes of central and eastern inland of Australia: a review with special reference to their biogeographical affinities

In 1984 when Bill Williams highlighted the regionalization of salt lakes in Australia, little was known about lakes in the remote inland. It was thought the invertebrate fauna of such lakes was depauperate due to their being poor evolutionary loci associated with extreme episodicity. However, work in the last two decades, has shown the fauna of many inland lakes is relatively rich. Part of the reason for restricted faunas in the larger lakes is habitat homeogeneity. Nevertheless there is little diversification at the species level, indicating restrictions on speciation. There are also limits on diversity imposed by the harsh environment, as indicated by the lack of forms unable to survive severe desiccation, e.g. higher crustaceans. Lakes in central and the eastern inland are dominated by characteristic lower crustaceans such as Parartemia minuta, Daphniopsis queenslandensis, Moina baylyi, Trigonocypris globulosa and a new mytilocyprid ostracod, as well as some forms widespread in Australia and in salt lakes on other continents. This invertebrate fauna is just as distinct as those of other salt lake districts in southern Australia, further reinforcing the concept of regionalization in Australia. The fish fauna of central and eastern salt lakes is also largely specific, but the waterbirds are not as they have responded to the episodicity by nomadism and habitat flexibility.

Salt Lakes in Australia: Present Problems and Prognosis for the Future

Australia is a land of salt lakes and despite low human population density, many lakes are adversely impacted by a range of factors. Secondary salinisation is the most pernicious force degrading lakes, especially in south-west Western Australia where up to 30% of the landscape is predicted to be affected. Mining also impinges on many salt lakes in this state, mainly through the dewatering of saline groundwater. Exploitation of groundwater for irrigation caused some lakes in Victoria, Australia, to dry, especially the significant Red Rock Complex. Global climate change will result in new water balances in endorheic lakes, with most having less water, particularly the seasonal lakes of southern Australia. This has already happened in Lake Corangamite, Victoria, but the prime reason is diversion of inflowing floodwater. Consequently, the lake has retreated and become salinised compromising its status as a Ramsar site. Various other lakes suffer from enhanced sedimentation, have introduced biota or their catchments are being disturbed to their detriment. Enlightened management should be able to maintain some important lakes in an acceptable condition, but, for most others, the future is bleak.

Distinctive aspects of the zooplankton of large lakes in Australasia, Antarctica and South America

Not only has the degree of species-level cosmopolitanism amongst zooplanktonic organisms been considerably overestimated, but differences between the different classical biogeographic regions (established from terrestrial studies) occur at supra-specific levels as high as family or even suborder. The Centropagidae, and particularly the genus Boeckella, are found in New Zealand, most of Australia, southern and high altitude regions of South America, and around the periphery of Antarctica. The biogeography and ecology of this family is discussed in detail. Most predaceous families of Cladocera are entirely absent from the Australian and Neotropical regions. The genus Daphniopsis occurs in salt lakes in Australia and South America and in freshwater lakes in Antarctica. In southern Australia numerous species of ostracod have colonized the limnetic region of salt lakes, and the largest of these prey on species of Calamoecia, Daphniopsis and small ostracods. Chaoboridae are absent from New Zealand as, too, are obligate planktivorous fish. The Chilean flamingo, Phoenicopterus chilensis, and Wilson's phalarope, Phalaropus tricolor, are significant predators on Boeckella poopoensis in salt lakes on the Andean Altiplano and elsewhere in South America.

Daphniopsis pusilla, a cladoceran of Australian salt lakes: Recognition and ecological data for palaeolimmologists

The cladoceran fauna of salt lakes in Australia is tabulated. Only Moina and Daphniopsis spp. are important elements, and D. pusilla appears to be the most important species. Important diagnostic characters for the ephippia of D. pusilla are described (ephippia are the most commonly preserved cladoceran remains). Some ecological features concerning this species are also given. The most important is that adults occur between salinities of 3 and 60%, although salinities may greatly exceed 60% in localities from where the species has been recorded.

The composition of aquatic communities in saline wetlands in Western Australia

Macrophytes, plankton samples, salinity and depth data were collected from wetlands in October 1981. Species diversity and distributions are recorded and relationships drawn between macrophytes and plankton occurrence. An examination of the data of Geddes et al. (1981) enables comparisons of species composition in a similar range of Western Australian lakes in 1978 at a different stage in the seasonal cycle. Comparison with the biota of salt lakes in Australia's eastern states and elsewhere lead to biogeographical speculations for the macrophytes and for some of the planktonic species.

On the ecology of Haloniscus searlei (Isopoda, Oniscoidea), an inhabitant of Australian salt lakes

The taxonomy, geographical distribution, salinity tolerance, bathymetric distribution, tolerance to desication and osmotic regulation of Haloniscus searlei Chilton (1920), an aquatic oniscoid isopod living in salt lakes in Australia, are considered.