Subscribe free to our newsletters via your
. Earth Science News .

Over-pumping sucks arsenic into Hanoi's water
by Staff Writers
Paris (AFP) Sept 11, 2013

Arsenic has infiltrated an aquifer that provides water for the Vietnamese capital Hanoi, scientists said Wednesday, warning that the phenomenon could also occur elsewhere.

Massive over-pumping of the aquifer caused the problem, but the threat is advancing slowly and Hanoi has ample time to deal with it, they said.

The experts said the phenomenon was a threat in other locations where naturally occurring arsenic lies dangerously close to over-exploited groundwater.

"This is the first time we've been able to show that a previously clean aquifer has been contaminated," said Alexander van Geen, a professor of geochemistry at the Lamont-Doherty Earth Observatory at Columbia University in New York.

"The amount of water being pumped really dominates the system. Arsenic is moving," he said.

The research, published in the journal Nature, entailed extensive tests around the village of Van Phuc, located on the Red River 10 kilometres (six miles) southeast of Hanoi.

Hydrologists sought to explain why local levels of arsenic, drawn from private wells around 40 metres (130 feet) deep, were so high.

On the western side of the village, the wells typically had less than 10 microgrammes of arsenic per litre (1.8 pints) of water, well under the World Health Organisation (WHO) threshold, they found.

But on the eastern side, arsenic concentrations were between 10 and 50 times higher.

The probe noted that there were two adjacent aquifers at Van Phuc.

One, lying in relatively recent sediment deposited around 5,000 years ago during the early Holocene era, has high levels of arsenic.

It lies uphill from a safe aquifer, whose sediment is far older, laid down more than 12,000 years ago during the Pleistocene era.

Massive pumping of the safe aquifer to feed the Vietnamese capital's surging demands have caused its levels to drop.

As a result, water is flowing into it from the contaminated aquifer and the nearby Red River.

Using dating techniques based on levels of helium and hydrogen isotopes in samples, the team found that over the last 40 to 60 years, water from the contaminated aquifer has advanced by around 2,000 metres (a mile) into other areas.

But its invasion of the safe aquifer is between 16 and 20 times slower.

The delay may be explained by the local hydrology: a chemical reaction between the intruding water and the aquifer's sediment could be curbing the advance.

So far, arsenic contamination has advanced by around 120 metres (370 feet) into the safe aquifer.

"It is not moving as fast as we had feared it might," Van Geen said.

There is no health risk for water users in Hanoi because the water is filtered, and the city may have years, or even decades, to fix the problem, the scientists said.

A bigger risk, though is for people who draw water directly from tainted wells.

Co-author Pham Thi Kim Trang of Hanoi University's Centre for Environmental Technology and Sustainable Development said efforts were under way to drill deeper wells for people at Van Phuc and install a filtering station.

However, "if people in the city keep drawing more water, the arsenic problem will become more serious," she said in a press release, noting that the expansion of the expansion of the city suburbs was prompting many people to connect to private wells with untreated water.

Between 2000 and 2010, Hanoi's water use nearly doubled, from around half a million to nearly one million cubic metres (19.4 million to 31.7 million cubic feet) of water per day, according to the team's estimates.

Pollution from naturally occurring arsenic is a known problem in many parts of the world, but it especially affects southern and Southeast Asia, where vast amounts of sediment containing arsenic have eroded off the Tibetan plateau over millions of years.

By some estimates, around 100 million people, most of them in Bangladesh, are chronically exposed to levels of arsenic that can cause heart, liver and kidney disease as well as cancer.

"Our results (in Van Phuc) are directly relevant to Bangladesh because the underlying geology and geochemistry of the problem are very similar," Van Geen told AFP in an email.

Michael Berg of Swiss Federal Institute of Aquatic Science and Technology said that the safe aquifer was part of a vast, integrated system of aquifers that covered thousands of square kilometres in the Hanoi region.

As a result, the detected contamination was only a small part of the whole system, Berg said in a phone interview.

But, he cautioned, the problem of arsenic intrusion from over-pumping was probably occurring in many other parts of the region, he said.


Related Links
Our Polluted World and Cleaning It Up

Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks DiggDigg RedditReddit GoogleGoogle

Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News

Bacteria supplemented their diet to clean up after Deep Water Horizon oil spill
Florence, Italy (SPX) Sep 09, 2013
Bacteria living in the Gulf of Mexico beaches were able to 'eat up' the contamination from the Deep Water Horizon oil spill by supplementing their diet with nitrogen. Professor Joel Kostka will tell geochemists gathered in Florence for the conference that detailed genetic analysis showed some of the bacteria thrived on a diet of oil because they were able to fix nitrogen from the air. The ... read more

New technique to assess cost issues from major flood damage

Australia reiterates tough asylum boat policy

Niger asks for foreign help for flood victims

Olympics: Tokyo 2020 is a bid in the shadow of Fukushima

Chinese-built Bolivian satellite tested in space simulator

Indiana Jones meets George Jetson

New computational approaches speed up the exploration of the universe

Advancing graphene for post-silicon computer logic

Report reveals missed opportunities to save water and energy

Massive pumping of groundwater for cities said raising arsenic risks

Rising reuse of wastewater in forecast but world lacks data

Scientist say just a few Asian carp may be big trouble for Great Lakes

New study points finger at climate in mammoth's demise

Penn Study Finds Earlier Peak for Spain's Glaciers

East Antarctic Ice Sheet could be more vulnerable to climate change than previously thought

On warming Antarctic Peninsula, moss and microbes reveal unprecedented ecological change

Indonesian farmers take legal action against president over haze

Overgrazing turning parts of Mongolian Steppe into desert

Certification of aquaculture critical to sustainable seafood production

A genetic treasure hunting in sorghum may benefit crop improvement

Tropical Storm Gabrielle batters Bermuda: forecasters

New model of Earth's interior reveals clues to hotspot volcanoes

Humberto becomes season's first east Atlantic hurricane

Scientists confirm existence of largest single volcano on earth

Nigerian troops kill 10 insurgents after air strike: army

West pressed hard for end to Congo war

Guinea-Bissau rules out amnesty for coup leaders

Sudan bombs S. Sudan buffer zone position, kills 2: Juba

Researchers discover rare fossil ape cranium in China

Wide range of differences, mostly unseen, among humans

Long-disappeared rivers may have helped human migrations out of Africa

New data reveals that the average height of European males has grown by 11cm in just over a century

The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement