In this issue

	ECOS Issue 45

Cloud seeding: its effects may linger A fresh analysis of more than 30 years of Australian rain-making experiments suggests that cloud seeding may have been much more effective than previously believed. Download Article

Seeking out the source of radium in groundwater One of the potential problems in mining uranium is that highly radioactive radium can be leached out of tailings dams. However, you cannot necessarily blame a nearby uranium mine if you find water containing high levels of radium. Download Article

Sensitive plant invades the north
Giant sensitive plant, Mimosa pigra, has been advertised by a seed-marketing company in Hawaii as 'an interesting conversation piece', due to the ability of its leaves to close when touched, and later re-open. Residents of the Northern Territory, however, are not so readily amused by such antics. For them, M. pigra is more of a menace than a pest.
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When you feel taxed: a new stress test Too much stress in the long term may lead to serious health problems. Although nobody has done a comprehensive study on the cost of stress-related diseases in Australia, the few researchers who have been studying stress estimate that it costs about 2 per cent of the Australian Gross National Product - $4,000 million a year. Download Article

Concrete: more cure, less rot The symbols of contemporary urban life, skyscrapers and pavement, dominate modern cities. But we often forget that their main ingredient, concrete, has been around a long time. In ancient Rome, all of the roads and many public buildings, such as the Pantheon, employed concrete in their construction. Download Article

Leak from the Pacific warming the west?
That gourmet's delight, the western rock lobster of Western Australia, probably owes its existence to an ocean current that has no parallel anywhere in the world. The Leeuwin Current is the world's 'odd man out', oceanographically speaking. This narrow ribbon of warm water flows rapidly southwards along the coast of Western Australia accelerating into the prevailing winds. Then it curls into the Great Australian Bight.
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Industrial wastes with potential
On the Swan coastal plain, WA, four refineries generate about eleven million tonnes of bauxite residue each year - twice the weight of the alumina produced in the refining process. The residue consists of two fractions, sand and finer red mud. The sand component quickly lets the highly alkaline caustic pass through it. However the fine red mud holds a lot of chemically combined and dissolved caustic, and is more difficult to 'clean'.
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Boosting casuarinas around the world
The tree the casuarina is so-called because its filamentous branches resemble the plumage of the cassowary. The tree is hardy, adaptable, and vigorous, and has colonised coastal dunes, swamp and salt-water habitats, and arid soils around the globe. Its success lies in the unusual symbiosis the tree has with the filamentous Frankia bacteria. Selecting the right Frankia strain is critical to the success of plantations overseas.
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Desalinating a million litres a day Brackish bore water, transformed into clean potable water by contact with special ion-exchange resins, should begin contributing a million litres to Perth's daily water supply. Sirotherm is an ion-exchange technique; resin beads remove the salt ions from Download Article

Bird's eye view of goose nests The wetlands of the Top End harbour a rich variety of water birds, especially ducks and geese. One of the most numerous and distinctive is the magpie, or semipalmated, goose - so called because of its pied markings and the very small webs of its feet. Download Article

Coal, cleaner than clean
Washing coal with water separates out the shaley low-grade material, and this is the job of the many coal washery plants scattered around the country. Upgraded in this way, more than 60 million tonnes of coking coal are exported each year. But even such prime clean coal carries a burden of incombustible mineral matter. Recent research has sought a way around this obstacle.
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Improvements in the baghouse Passing a smoky stream of exhaust gas through a filter appears a simple way of controlling pollution. It works in a similar way to the household vacuum cleaner, where the dirty air-stream is forced through a fabric bag to filter out the dust. Download Article

Putting frost on the map Frost, like other aspects of weather, is a difficult phenomenon to pin down. While the weather bureau can issue frost warnings for a region whenever overnight temperatures are likely to fall near zero, when frost strikes it is likely to be very selective in its targets. Download Article