Villagers follow the geology to safer water in Bangladesh

Water researchers have found a way to fight the "king of poisons" that accounts for 20 deaths in Bangladesh.

Arsenic has a long, poisonous history as used in aristocratic poisoning, but it is also a common element in the world. In groundwater, too much arsenic is still a killer, but nowhere more than in Bangladesh. The south Asia country is more than 10 million shallow, which means that it exceeds the World Health Organization's (WHO) arsenic guidelines of 10 micrograms per liter.

"Groundwater is popular because it is free from bacterial pathogens," explained Alexander van Geen of Columbia University, Lamont-Doherty Earth Observatory. Groundwater, which filters out most harmful bacteria. The same process adds minerals to groundwater-including a lot of arsenic in some shallow wells of Bangladesh.

In 2000, van Geen and his team surveyed 6,000 wells, and then recruited a health study cohort of 12,000 people. Then in 2013, they conducted a larger survey of 50,000 wells serving 350,000 people. They found that government was much less than 150 meters deep. However, they were more widely distributed than others, but they were distributed by political parties and were not accessible to the public. This interpretation has been made by the economist Mushfiq Mobarak at Yale University, van Geen explained.

"Millions of people rely on water supplies that are contaminated with naturally occurring arsenic," says Sarah Ruth, a director of the National Science Foundation's Dynamics of Coupled Natural and Human Systems Program, which funded the research. "Consumption of arsenic-contaminated water, or the rice crops irrigated with it, can have severe health effects, including a variety of cancers and increased child mortality."

The hijacking of the deeper government may not get good water, however. People in the study area are now better understood, van Geen said. As a result, they have been taking care of themselves, often encountering low arsenic water well before 150 meter depth. A new survey of the water in the study area recently documented in the WHO guideline. Only 25 percent of wells were safe in 2000, compared to 70 percent in 2018.

"This is good news," said van Geen of this year's survey of water. "This is for a population of 12,000 living within a 25 square kilometer area that we've been tracking since 2000. Urine arsenic data confirms that villagers are not just telling us what they know what we'd like to hear." Most of the decline is attributable to households reinstalling wells to a greater depth at their own cost.

"Some villages have figured out others," said van Geen. His team is trying to convey this information to the villages through water tests, so people can see the difference for themselves. "Geology and geochemistry causes the problem, but it's also the solution."

Van Geen will be presenting his latest water survey results at the meeting of The Geological Society of America in Indianapolis, Indiana, on Tuesday, Nov. 6

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More information:
How Earth Processes Can Poison Millions But also Provide A Solution: The Case of Well-Water Arsenic In South Asia, Presentation time: 10:50 AM at: gsa.confex.com/gsa/2018AM/webp … ram / Paper319704.html