Category Archives: Environment

Arts, Books, Environment, Nature

Book Review: Buzz

NATURE

Buzz

Bees are brilliant and a much-needed species. And it’s thanks to wasps from which they evolved.

DO you know what Aristotle, George Washington, Leo Tolstoy, Sherlock Holmes and Scarlett Johansson have in common?

If you didn’t you might be surprised to hear that they were (or are) all beekeepers.

This lively, engaging book shows the human fascination with bees has deep roots. Stone Age art, from Africa to Europe and further afield to Australia, depicts honey-hunting expeditions. People kept bees before they tamed horses. The Hittites imposed fines on anyone caught stealing from hives. The Greeks had honey taxes.

Bees have long been central to our eating habits. “It’s often said,” Hanson remarks, “that every third bite of food in the human diet relies upon bees.”

He includes a table of 150 crops which either need or benefit from pollination by bees. They range from apricots to tomatoes and turnips.

Mead, brewed from honey, is one of mankind’s oldest tipples. People have been drinking it for at least 9,000 years. The ancient Chinese downed a version laced with rice and hawthorn berries; the Celts preferred theirs flavoured with hazelnuts.

The Mayans of Central America went one better and produced hallucinogenic varieties, spiked with narcotic roots.

Bee products have also proved invaluable in traditional healing. Of 1,000 prescriptions in a 12th-century volume entitled The Book Of Medicines, more than 350 made use of them. Honey was thought to be a remedy for everything from hiccups to a low sperm count. Beeswax could be used to treat loose teeth, aching testicles and sword wounds.

It’s little wonder that bees figure prominently in various mythologies. In some Greek myths, the god Zeus was raised by wild bees who fed him on nectar and honey. In cultures across the world, the buzzing of bees was interpreted as the voices of departed souls.

Bees are certainly remarkable creatures. They evolved from wasps. The first unequivocal bees appear in the fossil record about 70 million years ago. There are now around 20,000 different species around the globe.

Their antennae tune into chemicals which signal everything from potential meals to potential mates. Their wings can flap more than 200 times a second. One species of bumblebee can hover at elevations higher than the peak of Everest.

Bees, of course, evolved in tandem with the flowers on which they feed and which in turn depend on them to spread their pollen. In one sense, the colours of flowers reflect the nature of bees’ eyesight.

The prevalence of blues and golds in flowers is no chance matter. These shades fall right in the middle of a bee’s visual spectrum. On remote islands where there are few, if any bees, flowers are drab and colourless.

The development of scented flowers is also interwoven with bees’ ability to sense them. As Hanson puts it, “The fact that bees prefer odours we find worthy of poetry, counts as one of nature’s happier accidents.”

Plants need to attract bees to help them pollinate. They have devised any number of cunning strategies to do so. Some include caffeine in their nectar to get bees addicted to visiting them.

There are varieties of orchids which mimic the body shapes and scents of female bees to lure lustful male bees towards them.

The behaviour was recorded in the 19th century but prudish naturalists, including Charles Darwin, were puzzled. They thought the bees were attacking the orchids. They didn’t realise that they were actually trying to have sex with them.

 

BEES are now big business, particularly in the U.S. For a price, honeybees are sent by truck around the country, so farmers can improve bee-dependent crops. More than 10 million bees can be on a single truck.

Much publicity has been given in recent years to the alarming decline in bee numbers – so-called Colony Collapse Disorder (CCD). Hanson acknowledges the concerns, but he is ultimately optimistic about the future. He is also a charmingly enthusiastic bee fanatic and his book is delightful to read.

– Buzz by Thor Hanson is published by Icon for £16.99

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Education, Environment, Science

Questions of Science: Against the grain

SAND PARTICLE DEPOSITION

Sand particles on a beach or dunes seem to reach a certain grain size and then reduce no further. After millions of years, shouldn’t most sand have become dust?

THE GRAINS that we see in desert sand dunes have been deposited mainly by wind action. These will generally have originated in other parts of the desert where there are bare rock surfaces that are constantly being weathered by exposure to the sun, wind and water – the last of which is a surprisingly powerful weathering agent in deserts.

The result is a build-up of fragments of various sizes: boulders, pebbles, sand grains and dust. The last two, being smaller, can be removed by the wind and transported hundreds of kilometres, either in suspension high in the atmosphere, or by saltation – the process of bouncing along the ground.

The maximum grain size that can be transported by the wind is proportional to the wind speed – faster winds will move larger particles. This means that the large particles are deposited when and where the wind speed drops, which is often in low or flat terrain. So sand grains of around a certain size can accumulate in great masses in lowland basins, while the smaller fragments can be carried further; dust from the Sahara Desert quite frequently falls on the UK, for example. The result is that dunes are made up of grains mainly of the same size.

Similar principles apply on beaches, although the movement of particles is also affected by a variety of additional processes such as wave action, tides, offshore currents and long-shore drift – sand creep caused by waves approaching the beach obliquely. How effective each mechanism is at moving particles depends on its energy, so each will deposit particles in a different location. For example, wave action can sought beach material so that shingle will accumulate as a ridge high up the beach, while sand will only be exposed at low tide. Or long-shore drift may carry sand to one end of a beach, leaving shingle at the other.

Of course, all these fragments – boulders pebbles and sand – may gradually be broken down into finer particles, so that we might suppose all of the world’s rocks should by now have been reduced to a mass of dust blanketing the continents. But this does not happen because deposits of sand and dust gradually get compressed and cemented together to form new rock – the sandstones and mudstones. Nor does the planet run out of sand and dust, because bare rock surfaces are constantly exposed to weathering processes, and there will always be new rock exposed as a result of tectonic movement.

National Geographic

IF the sand in a coastal system is too fine relative to the energy of the waves then it will stay in suspension in the water and will not be deposited. So for a beach of dust to exist, the environment would have to be profoundly calm, and the dust-like sand would have to be kept wet in order to prevent the wind from claiming it. Most beaches are not like this.

Dunes are deposits of wind-blown sand, and for the sand to be deposited the size of the grains must exceed the carrying capacity of the wind. Sand dunes are innately dry places and there is no way that dust-sized particles could hope to stay put in these areas, however weak the wind may be.

Desert dunes exist in gigantic systems, whereas beach dunes form only a narrow band running along the back of some sea beaches, and are created by gusts from the sea that transport sand up from the beach. Yet both systems result from the same key processes of wind-borne matter being deposited when the wind becomes too weak to keep it aloft. Of course, even the tiniest sand grains will be deposited somewhere, but they will be highly dispersed and will not form dunes.

. You may also like  Skimming pebbles on water. But how does it happen?

 

. Appendage:

Sand

 

Science in motion

Science-in-motion: a series of short articles following topics in science.

. Newtonian gravity

Isaac Newton’s law of universal gravitation, published in 1687, was the first clear mathematical description of how bodies such as planets and stars attract each other under their mutual gravitational pull.

Newton’s inspiration for the theory came from watching an apple falling from a tree. A falling apple accelerates towards the ground, so Newton reasoned from his laws of motion that there must be a force, which he called gravity, acting on the apple. This force might have a huge range and could also be responsible for the orbit of the Moon around the Earth, if the Moon had just the right speed to remain in orbit despite constantly ‘falling’ towards the Earth.

He went on to show that the gravitational force between two massive objects is directly proportional to the product of their masses and weakens with the square of the distance between them. But troubling, the theory didn’t explain why the force was transmitted across empty space. This problem is resolved in Einstein’s general relativity theory.

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Britain, Environment, Government, Science

Reintroducing beavers could help fight flooding and pollution

ENVIRONMENTAL SCIENCE

Beavers were common inhabitants of the UK’s waterways for centuries.

A reintroduction of beavers to Britain could help clean up rivers, prevent flooding and minimise soil loss, an expert has claimed.

Professor Richard Brazier, a researcher at the University of Exeter, said unpublished preliminary results from a trial area in Devon showed muddy water entering an area where the creatures were living was three times cleaner when it left.

And he said farmers and agriculturalists should be grateful to the buck-toothed beasts cleaning up pollution caused by carbon and nitrogen from fertilisers being released into the environment.

Prof Brazier said: “We see quite a lot of soil erosion from agricultural land round here (near Okehampton).

“Our trial has shown that the beavers are able to dam our streams in a way that keeps soil in the headwaters of our catchment so it doesn’t clog up rivers downstream and pollute our drinking and bathing waters.

“Farmers should be happy that beavers are solving some of the problems that intensive farming creates.

“If we bring beavers back it’s just one tool we need to solve Britain’s crisis of soil loss and diffuse agricultural pollution of waterways, but it’s a useful tool.”

Prof Brazier’s claims were disputed by the National Farmers’ Union (NFU), which warned that the reintroduction of beavers to Scotland had led to fields and forests becoming damaged.

A spokesperson for the NFU said: “The knowledge of the impacts beavers have had to farmland, riverbanks and flood defences in Scotland is concerning. We await the (formal) results of the Devon trial and will analyse the outcomes then”.

Bavarian beavers thought to have escaped or been released into the wild in the Forfar area of Scotland about fifteen years ago have been blamed for damage to trees and water ditches.

Beavers were common inhabitants of the UK’s waterways for centuries, until hunting for their valuable pelts led to their eventual extinction.

Prof Brazier, an expert in Earth Surface Processes, insisted the animals could even play a useful role in preventing flooding – an increasingly common problem across parts of England.

He further added: “The public is currently paying people to build leaky dams to keep storm waters in the uplands.

“The beavers can do it free of charge and even build their own homes. They are busy as beavers. It’s a no-brainer.”

His claims were in part supported by Devon Wildlife Trust’s, who said that wildlife habitat in two areas in the north of the county had improved since the introduction of two beavers in 2011, with frogs and herons seeing particular benefits.

“We shouldn’t be surprised – beavers were part of our landscape and so many creatures evolved alongside them,” he said.

However, Professor Jane Rickson, a soil specialist from Cranfield University, Bedfordshire, joined the NFU in sounding a note of caution.

She agreed that in some places in the UK there was evidence of worrying soil loss, and said new policies were urgently needed.

Beavers may in fact reduce the river channel and remove vegetation, exposing banks to greater erosion and increasing, rather than decreasing, the risk of flooding, she warned.

And she said beaver dams should be “leaky” to avoid build-ups of large volumes of water.

An Environment Agency spokesman said: “Natural and hard flood defences both have an important role in keeping communities’ safe – though introducing beavers does not form part of our approach.”

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