Arsenic And Bangladesh Water Supplies
Many water wells in Bangladesh are contaminated with arsenic. More than 70 million people are affected. In the 1970s and 80s various International Agencies joined together to dig wells to allow the population access to clean water.10 million wells were dug , but the presence of arsenic was unsuspected and untested for.
The arsenic is a fluke , the result of leaching from the Himalayan mountains and carried down over thousands of years. The amount of arsenic is 5 to 10 times the upper limits of safety.
The result is a terrible poisoning with 27 million drinking water with over 50 ppb arsenic and 50 million 10 ppb, the safe concentration. The food produced from plants watered by contaminated water may also be poisonous.The safe concentration may be 1.7 ppb.
The poisoning includes blackening of the hands and feet, nodular growths and gangrene and ulcers. Cancer can be a later development.
The Lancet describes the valiant attempts of Joseph Graziano and his colleagues from Columbia University USA to try and remedy this.
The work includes clinical care but perhaps central to the whole study is to dig new wells often close to the poisoned wells which produce clean water.
Loewenberg S 2007 Scientists tackle water contamination in Bangladesh Lancet vol 370, 471-2
Loewenberg S 2007, Profile Joseph Graziano : tackling arsenic poisoning in Bangladesh. Lancet. Vol 370 p 477
Arsenic And SE Asia
Arsenic poisoning is a real problem in Bangladesh. A recent paper in Nature 2008, vol 454 p 263 indicates that many other areas in SE Asia may be troubled by arsenic pollution of the water.
A map of contamination indicates that the Myanmar Irrawaddy Delta is may be contaminated by arsenic. Many of these countries wells are polluted, and arsenic poisoning can cause skin lesions and cancer.
The reason is that the deltas fill with relatively new sediments only 10,000 years old. These are more likely to release arsenic.
3.5 million people live in these regions.
Ledford 2009 Irrawaddy may be poisoned by arsenic Nature vol 454 pp 263
China and water
A crisis is developing beneath China’s farms and cities. With about 20% of the world’s popula-tion but only about 5-7% of global freshwater resources, China draws heavily on ground¬water. Those reserves are being depleted at an alarming rate in some regions and are badly polluted in many others.
The water crisis is not unique to China, but the problem here is orders of magnitude bigger than anywhere else:’
Groundwater is used to irrigate more than 40% of China’s farmland, and for about 70% of the drinking water in the dry northern and north¬western regions.
During the past few decades groundwater extraction has increased by about 2.5 billion cubic metres per year. Groundwater levels of the arid North China Plain have dropped as fast as 1 metre a year between 1974 and 2000, forcing people to dig hundreds of metres to access fresh water.
Water is scarce for two-thirds of China’s 660 cities. As China’s economy expands, so will its demand for water. The country will consume 750 billion cubic metres of water a year by 2030, about 90% of the total amount of usable water resources in the country.
Pollution is also putting the system under pressure. In southern and southeastern China, which have seen rapid economic development, groundwater is now laden with heavy metals and other pollutants. 90% of groundwater is polluted, 60% of it seriously so.
The government hopes that a massive system of canals and pipes, to funnel 45 billion cubic metres of water a year from China’s moist south to its arid north, will alleviate groundwater depletion once it is completed in 2050.
Climate contributed only about 10-30% of the water-table depletion in three regions of China. The majority of the depletion was down to farming practice: “There is much room for improvement in terms of more effective water management.
Arguably, the biggest improvement could come in the agriculture sector, which already uses 70% of the COW1try’S fresh water. To boost grain production, for example, China has a double-cropping system of growing wheat in winter and maize in summer. But because there is very little precipitation on the North China Plain in winter, this draws deeply on groundwater supplies. The country could import grain, and synchronize crop production with the climate by ending the cultivation of winter wheat and growing maize for more of the year.
Qiu 2010 China faces up to groundwater crisis nature vol 466 p 308
Rain And Water
Tropical rain recycling
Water must be along with oxygen amongst the most important provision to life. Useable water is essential. Water movements on earth are central to climate and life. The process is a little like the chicken and egg but if one starts with water evaporation from oceans, accumulates in the atmosphere, followed by coalescence and falling as rain or snow. Some directly into the oceans, other on land and enters the terrestrial water cycle. A very complex process.
Tropical ocean waters evaporate, the water is lifted to cloud level by convection and transported towards the poles and lost progressively as rain or snow.
Rain sometimes in hot regions never reaches the ground but evaporates again in the sky. This depends upon the ambient relative humidity
Rahn T in Nature 2007, vol 445, pp495-6.
Worden et al Nature 2007, vol 445, pp 528-531.
Sanitation And Health
Our interest in food may not to stop once the residue leaves the colon into the outside world.
In Asia, Africa and Latin America more than two and half billion people ( 40% of the worlds population) have no toilets with a proper waste removal system. In India the figure is 700 million. In Afghanistan less than 10% have access to toilets. Which is a major source of disease, as the free expression leads to contamination of drinking water and the spread of highly lethal diseases e.g. cholera with faecal contamination ( in 2006 over 230,000 reported cases ) and hepatitis from faecal and urinary contamination.
When there is a serious sanitation programme then the death rate particularly in children falls . There are cultural problems and the need or education, to use toilets and for them to be kept clean and healthy. . My wife and I have a league of the worst toilet we have seen , one in South Mexico is a slender winner.
It also must be said what a remarkable system the urban sewage system is. The pioneering London scheme in the Victorian era and the development of similar systems in the cities, town, villages has transformed life and health.
Leader Lancet 2007 Access to toilet for all Lancet vol 370, p 1590
Durrheim 2007, A clarion call for greater investment in global sanitation Lancet vo370, 1592-3
Barreta et al 2007 Effect of city-wide sanitation programme on education in rate of childhood diarrhoea in northeast Brazil : assessment by two cohort studies Lancet ; vol 370, 1622-28
Water is vital to life The American Museum of Natural History has an exhibition on Water ( Water : H2O = Life.)
The exhibition shows the difference in usage in different parts of the world. The average North American, uses between 227 and 340 litres of water per day. Yet Atlanta, Georgia, will run out of drinking water within the next four months if it doesn’t rain soon. The city is experiencing its driest year since 1931. In some parts of sub-Saharan Africa, women spend between 15 and 17 hours a week collecting water..
20 litres per day is the minimum amount of clean water required to meet basic human needs, drinking, cooking and hygiene. Some people in parched places have to survive on just 5 litres or less. One quarter of Mexico City’s residents have no access to tap water; others have only 1 hour a week.
The exhibit’s emphasis is on water conservation. It takes 3 litres of water to produce a 1-litre bottle of bottled water .
There are innovative methods to extract, conserve and purify water. More than 700 PlayPump water systems have been installed in rural South Africa and other sub-Saharan countries. Children spinning on these colourful merry-go-rounds 16 times per minute generate enough energy to pump about 1,400 litres of water per hour from boreholes 40 metres deep. Perth , Australia gets 20% of its water supply from the Indian Ocean, desalinated with wind power. Windhoek in Namibia reclaims up to 30% of its water from sewage.
Bangladeshi women have cut cholera incidence in half using sari fabric, folded eight times, to filter bacteria from water.
Following the writings of Snow and the demonstration in the late 19th century that faecal contaminated water was a factor in the spread of cholera the London Corporation built separate water mains and sewerage tunnels emptying downstream into the Thames river, a system that is still in use. The Thames and Lee rivers now supply drinking water to 8.3 million residents in th London area every day.
Systems age and the antiquated system allows hundreds of millions of litres of untreated sewage to pass directly back into the rivers . This happens in London and in the River Forth in front of my house. .
Glausiusz J (2007) The liquid of life Nature vol 450 p 353
As global warming becomes more of a day to day reality the most conspicuous effect is on the availability of water. In parallel with the drying of the terrestrial surface there is increasing requirements for water by growing populations as well as industry.
There are many instances of this but a recent example is recorded in the London Times of February 6th 200. India is enjoying increasing prosperity and with this an increasing requirement for water. After a 17 year long tribunal the southern state of Karnataka in Southern India is obliged to allow more water to flow down the River Cauvery to States downstream. The disputes over this originate in the 19th century from the time of the Raj.
The amounts of water in discussion are massive and are in excess of 500 billion cubic feet. The States downstream are desperate for water and their needs are, they feel, unmet. Lack of water makes population panic and there have been riots in response to the most recent decisions of the Tribunal. This decision is to insist that half of the 500 billion cubic feet of water is allowed to flow down stream to fed the other States.
Such arguments abut the distribution of water are happening all over the world for example the Jordan in the Middle .East.
Elsewhere there are problems attendant upon excess rain .
Water More Or Less
The world is facing a real crisis in obtaining fresh water. This topic, central to any Population Nutrition economy has been discussed at length in a recent edition of Nature
- 1 billion people lack access to fresh drinkable water.
- 2 billion lack proper sanitation.
Whilst climate change is an important factor other factors are contributing to the problem. Growing populations and increasing energy requirements. India and China are prospering and consuming more meat. It takes 15,500 litres of water to produce 1 kilogram of beef. Which is 10 times the amount of water to produce 1 kg of wheat.
Cooling electricity plants requires fresh water, the United States uses more than 500 billion litres of fresh water a day to cool its power stations. Australia is struggling to obtain sufficient water to grow wheat.
Energy usage is increasing and the use of water will double.
To produce sufficient food we will need 12,000 cubic km of water , equal to the
Many of the world’s rivers are drying. volume of Lake Superior every year.
There is a need to use what is called blue water efficiently , rivers, lakes, reservoirs and underground aqueducts but also green water that is rain water.
Green water conservation means changes in agricultural techniques to ensure that rain is effectively used. Which is not universally the case currently
Desalination is an attractive option but is very energy costly. Polyamide membranes and reverse osmosis plants are more efficient than thermal distillation plants. At the present time 40 million cubic metres of water is produced a day world wide. The average cost is 3.5 times the cost of pumping from aquifer, though this varies with the locality. . Fouling of the filters is a real problem and costly.
Editorial Nature 2008, a fresh approach to water Nature vol 452 pp 254
Schiermeier 208 Purification with a pinch of salt Nature vol 452, pp 260-61
Water under pressure a News Feature 2008 Nature vol452. pp 269-
Water is essential for life
Dirty contaminated water, which is world wide phenomenon, is a threat to life In many rural communities there is a shortage of water which may be contaminated. The prime problem is bacteria and viruses, but also toxic elements e.g. arsenic. Filtering the dirt and bacteria is the best method. There are several other methods
- Leaving a bottle full of the water in the sun to heat and sterilise the water
- The Moringa tree seeds if crush contains polypeptides which adsorb bacteria and other contaminates and these settle and yield pure water. Michael Lea has a website showing how to do this. The Moringa tree is abundant in the tropics.