viernes, 6 de diciembre de 2013

Ancient Water Irrigates Saharan Oasis

La agricultura de oasis sahariano
Image: European Space Agency
By Rachel Feltman
Outside Al Jawf, Libya, a verdant oasis blooms in the middle of a desert. 
Farmers irrigate their Saharan fields, which receive only 2.5 millimeters of rain a year, with so-called fossil water from a massive aquifer beneath a large swath of northeastern Africa. 
The Nubian Sandstone Aquifer System is a remnant of wetter eras going back 20,000 years, when heavy rains fell that ultimately penetrated more than three kilometers into the earth.
Why are the agricultural plots perfectly round? The oasis relies on center-pivot irrigation, in which a single, rotating beam of sprinklers delivers water to crops planted around a central point. 
The size of the plots—up to one kilometer in diameter—helps them stand out in this image from Japan's Advanced Land Observing Satellite.
scientificamerican.com


This article was originally published with the title What is It?.

domingo, 13 de octubre de 2013

Global Food Security: The Critical Role of Water, Sanitation, and Hygiene (WASH)

Photo: Women's Environment & Development Organization (WEDO)
Photo: Women’s Environment & Development Organization (WEDO)

  • Women cannot contribute to the agricultural sector when they devote six hours each day to collect water.
  • Unsafe WASH decreases income-generating opportunities, further diminishing households’ abilities to purchase nutritious foods.
  • Food safety through safe WASH practices can reduce fecal food contamination by approximately 96 percent.
Global health experts are recognizing that food security challenges cannot be met until safe drinking water, sanitation, and hygiene (WASH) are available in the world’s poorest communities. The World Health Organization defines food security as “when all people at all times have access to sufficient, safe, nutritious food to maintain a healthy and active life.”[1] The three main aspects of food security are: food availability, food access, and food use.[2]

Food Availability

Because women make up 43 percent of the agriculture workforce in the developing world,[3] they are disproportionately affected by lack of access to safe drinking water and sanitation. In almost two-thirds of households surveyed in 2010 from 45 developing countries, women were the primary collectors of water,[4]spending up to six hours each day on this task.[5] Women cannot contribute to the agricultural sector when they are devoting so much time to collecting water and caring for family members who are sick from contaminated water and lack of sanitation.
Wastewater containing untreated human feces is often used by farmers because of its high nutrient composition. Sometimes it is used because it is the only reliable supply of water. While using wastewater provides higher financial returns on crops,[6] the higher returns also bring a higher risk of exposure to microbial contaminants. The use of untreated wastewater increases the risk of infection for both farm workers[7] and those who consume the crops.[8] Open defecation and poor waste disposal can also contaminate food crops.

Food Access

Lack of basic water and sanitation services perpetuates cycles of gender inequality and poverty, reducing household resources and opportunities to access and afford nutritious foods. One study[9] found that when the poorest households in Sudan spend their income on water, that money is often taken from their food budget.
Even when food is available, households cannot afford to purchase it when much of their income is spent securing water for their families. And when women spend much of their time collecting water or caring for family members made sick by contaminated water, they lose opportunities to participate in income-generating activities, further decreasing households’ abilities to purchase nutritious foods.

Food Use

Without access to safe drinking water, proper sanitation, and proper hygiene, food is easily contaminated through exposure to unsafe drinking water, pathogens on hands and from flies, and unclean surfaces. This can cause diarrhea, environmental enteropathy and other intestinal diseases and eventually undernutrition. It is a vicious cycle: intestinal diseases contribute to undernutrition through decreased nutrient absorption,[10]while undernutrition reduces the body’s ability to fight off further infections.[11]
Infants in the developing world who are given other liquids or foods with breast milk or are not breastfed are at higher risk for diarrhea due to exposure to contaminated water or lack of sanitation.[12] A study in Bangladesh found that proper disposal of child feces in an isolated space resulted in a 35 percent reduction in intestinal parasite infection.[13] Handwashing with soap, a basic hygiene practice, has been shown to reduce the risk of diarrheal disease by 42 to 47 percent,[14] and handwashing practiced at critical times such as before preparing a meal or feeding a child, along with using safe drinking water to wash utensils and prepare food, reduced food contamination by approximately 96 percent for babies in Bangladesh.[15] Food safety in the home, at school lunch programs, and in the workplace through the use of safe drinking water and handwashing practices consequently is imperative for food security and disease prevention.


[2] Ibid.
[3] FAO, 2011. The role of women in agriculture. ESA Working Paper No. 11-02.
[4] WHO/UNICEF Joint Monitoring Programme for Water Supply and Sanitation, 2010. Progress on Sanitation and Drinking-Water, 2010 Update.
[8] Drechsel, P., et al., 2009. Wastewater irrigation and health.
[9] Cairncross, S. & Kinnear, J., 1992. Elasticity of demand for water in Khartoum, SudanSocial Science & Medicine 34(2):183-189.
[11] Guerrant, R., et al., 2008. Malnutrition as an enteric infectious disease with long-term effects on child developmentNutrition Reviews 66(9):487-505.
[13] Roy, E., et al., 2011. Patterns and risk factors for helminthiases in rural children aged under 2 in BangladeshThe South African Journal of Child Health 5(3):78.
[14] Curtis, V. & Cairncross, S., 2003. Effect of washing hands with soap on diarrhoea risk in the community: a systematic reviewLancet Infectious Diseases 3(5):275-281.
[15] Islam, M., et al., 2013. Hygiene intervention reduces contamination of weaning food in Bangladesh.Tropical Medicine and International Health 18(3):250-258.


sábado, 20 de abril de 2013

Eco-friendly Super Foam Makes Contaminated Water Fit To Drink


Absorbance properties of "super foam" being tested in an NC State forest biomaterials labSuper Foam being tested
It began as an experiment to create an absorbent material for the next generation of diapers,  but potential uses may be much more far-reaching.
Using by-products of the lumber industry and pulverized crustacean shells, Dr. Joel Pawlak and his research team in the Department of Forest Biomaterials at NC State University came up with an eco-friendly super absorbent foam that has the potential to revolutionize efforts to purify drinking water in developing countries and disaster-stricken areas.

Watch the video – Source: Reuters 
by CNR Communications
cnr.ncsu.edu

Map Shows Vast Regions of Ocean Are Warmer



Changes in Sea-Surface Temperature Since 1900
By Mark Fischetti  

Most people equate global warming with the atmosphere, but detailed mapping shows that many regions of the world’s oceans are heating up, too. 
Data compiled and plotted by Marinexplore in Sunnyvale, Calif., show that sea-surface temperatures across the Atlantic, Pacific and Indian oceans are up by about 1 degree Celsius and as much as 2 degrees C in certain spots (see map below).
The warming is not uniform, and parts of the Southern Ocean around Antarctica have actually cooled. 
Temperature changes are more mixed in the Arctic Ocean, up as much as 2 degrees C in some spots and down by 2 degrees C in others.
Roberto De Almeida, an ocean data engineer at Marinexplore, also notes that the Atlantic and Pacific oceans are heating up as deep as 700 meters and beyond. 
For graphics on that trend, see “Deep Heat Threatens Marine Life” in the April issue ofScientific American.
scientificamerican.com