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	Issue 4

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Salt problems in Perth’s hills
The Darling Range is very important to Western Australia. Its forests are the source of the renowned hardwood jarrah, and the bauxite in its soil supplies a large alumina-refining industry. Parts of the Range are farmed, and its streams provide irrigation water for the plains below. Its scenery, climate, and proximity to Perth make it a valuable recreation area. Most important of all, it supplies 90% of Perth's water.
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Sawmill wastes: cleaner disposal, new uses
When a tree is converted into sawn or dressed timber, only between half and one-third of it usually gets used — that is if you exclude the leaves, bark, and root system. Each year Australian sawmilling and wood-processing operations yield wood residue equivalent to about 5½. million cubic metres of sawn timber. Bark should be added to this figure, but nobody really knows how much of that we produce.
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Food and water — enough for the many?
How many people can Australia support? There's no simple answer, of course; it depends on the country's ability to keep supplying the things people need and on how fast people consume these things: However, the question is clearly an important one. In Canberra, a group of biologists and physicists from CSIRO recently looked at possible limits to the amounts of food Australia could produce and water it could supply. Then they related these to population limits.
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Monitoring ultraviolet radiation Ultraviolet rays from the sun cause skin cancer and sunburn. However, only a very small proportion of the harmful radiation penetrates to the ground. Ozone in the upper atmosphere forms a very effective shield. Download Article

Flotsam and jetsam on Westernport Bay
People don't usually like their beaches being fouled by oil, or littered with bits of wood and other trash that washes out from urban storm-water drains. No doubt holiday-makers using the beaches of Westernport Bay are no exception. Yet to some extent such pollution probably must be the price that will have to be paid for the proposed Westernport industrial complex.
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What makes a brown haze? Take any big city. On a sunny still morning, the chances are that an unsavoury-looking brown haze will be hovering over it. Although city dwellers know the haze well by sight, much remains to be found out about just what it is and where it comes from. Download Article

Fruit pigeons need their rainforest Most of the pigeons that we usually see in Australia are rather drab, but in the rainforest it's different. Australia has 23 pigeon species, and no less than nine of these occur almost exclusively in our diminishing rainforests. Download Article

Jets, haze, and the stratosphere Twenty kilometres high in the sky sounds a long way up — commercial jet airliners only cruise half as high. So it seems astonishing that tiny particles less than a millionth of a metre across so far up in the stratosphere may affect us. Yet very possibly they may. Download Article

What to do about liquid trade wastes? One of the problems created by the growth of our industrial cities is finding ways of disposing of ever-greater amounts of waste. More people with their rising standard of living create more garbage, and industry produces more solid and liquid wastes. Download Article

Australian birds — migrants or nomads? Text books often say that few Australian birds regularly migrate from one place to another — they are merely nomads, finding feed where they can get it. Download Article