THE STANFORD DAILY
Wednesday, April 15, 2009
By: Julia Brownell
Faculty and students from the Environmental Earth Systems Sciences (EESS) program have found the source of arsenic that has been poisoning groundwater in South Asian river deltas.
The project, conducted south of the Cambodian capital, Phnom Penh, was orchestrated by EESS Prof. Scott Fendorf and his team of graduate students, in conjunction with Research Development International (RDI) Cambodia.
The health effects of ingesting arsenic range from mild callusing and darkening of the skin to lesions on the skin and lungs, leading to melanoma and lung cancer.
The humanitarian aspect of this research on arsenic is very important to Fendorf and his team; Fendorf said that he believes that the humanitarian spirit permeates the EESS department.
“Definitely, EESS research has a human element to it…It was one of the founding ideas,” he said. “Once you see the gravity of the situation in South Asia in my case…you start migrating to those types of issues.”
Due to intense civil war in Cambodia over the past 30 years, the citizens have only started to dig wells to the aquifer for drinking water over the past decade. Therefore, they have fewer symptoms of poisoning because of their limited exposure.
“It takes often two decades before effects start manifesting themselves,” Fendorf said.
Most health effects are more visible in the Ganges-Brahmaputra river delta in India and Bangladesh, where thousands die of cancers related to the toxin.
“It’s really, really bad,” Fendorf said. “Bangladesh and parts of India are really getting hit hard with the health effects now, and Cambodia is on its way.”
To get to the bottom of the mystery, the team dug wells in a section of the Mekong delta to study the distribution of the dissolved arsenic.
“We were able to figure out how the water flows, and follow the chemistry of [the arsenic] as it moves down,” Fendorf said.
The wells allowed the team to study the exchange of water between the river and the wetlands surrounding it. The wetlands are flooded by the Mekong River each year, which deposits sediment containing insoluble arsenic from the Himalayas. Once deposited, the arsenic is used as fuel by anaerobic bacteria, which turn it into a soluble form that flows with water from the wetlands down into the citizens’ drinking water. The aquifer then feeds back into the river.
“We think it’s about a 300-year travel time [in the strongest spots],” Fendorf said. “It’s a steady state; you have arsenic in the sediment and arsenic in the water. It’s been happening for thousands of years, and it’ll just keep doing that.”
Fendorf stressed that the project was not one without hope of solution. He recently returned from a conference in Cambodia about how to proceed using the new findings. The conference stressed how scientists can help inform policy-makers and the public.
In addition, Fendorf mentioned specific measures being considered to remedy the problem for the citizens of the delta who have no other source of water and are running out of time against the health risks.
“You can filter the water,” he said, “but you have a number of risk factors—how do you prevent filter failure and how do you work if a filter does fail?”
Due to limited options of other water sources, Fendorf said another option may have to be “rainwater harvesting.”
Cambodia’s civil war included genocide against citizens outside the government who were educated or held positions of power. Fendorf stressed that RDI Cambodia made sure the project worked cooperatively with the community in Phnom Penh to help educate them and provide work opportunities.
“That was RDI’s mantra–immerse themselves in the local community and not just bring in Westerners to do the work,” Fendorf said. “Helping to bring back an educated class is really important.”
Though on the right track, Fendorf qualified that this research is by no means an end or solution to the puzzle.
“It was an important step…[the research] is having and will continue to have a positive social influence,” he said. But, “We’re actually still working over there…It’s an ongoing process.”
Wednesday, April 15, 2009
By: Julia Brownell
Faculty and students from the Environmental Earth Systems Sciences (EESS) program have found the source of arsenic that has been poisoning groundwater in South Asian river deltas.
The project, conducted south of the Cambodian capital, Phnom Penh, was orchestrated by EESS Prof. Scott Fendorf and his team of graduate students, in conjunction with Research Development International (RDI) Cambodia.
The health effects of ingesting arsenic range from mild callusing and darkening of the skin to lesions on the skin and lungs, leading to melanoma and lung cancer.
The humanitarian aspect of this research on arsenic is very important to Fendorf and his team; Fendorf said that he believes that the humanitarian spirit permeates the EESS department.
“Definitely, EESS research has a human element to it…It was one of the founding ideas,” he said. “Once you see the gravity of the situation in South Asia in my case…you start migrating to those types of issues.”
Due to intense civil war in Cambodia over the past 30 years, the citizens have only started to dig wells to the aquifer for drinking water over the past decade. Therefore, they have fewer symptoms of poisoning because of their limited exposure.
“It takes often two decades before effects start manifesting themselves,” Fendorf said.
Most health effects are more visible in the Ganges-Brahmaputra river delta in India and Bangladesh, where thousands die of cancers related to the toxin.
“It’s really, really bad,” Fendorf said. “Bangladesh and parts of India are really getting hit hard with the health effects now, and Cambodia is on its way.”
To get to the bottom of the mystery, the team dug wells in a section of the Mekong delta to study the distribution of the dissolved arsenic.
“We were able to figure out how the water flows, and follow the chemistry of [the arsenic] as it moves down,” Fendorf said.
The wells allowed the team to study the exchange of water between the river and the wetlands surrounding it. The wetlands are flooded by the Mekong River each year, which deposits sediment containing insoluble arsenic from the Himalayas. Once deposited, the arsenic is used as fuel by anaerobic bacteria, which turn it into a soluble form that flows with water from the wetlands down into the citizens’ drinking water. The aquifer then feeds back into the river.
“We think it’s about a 300-year travel time [in the strongest spots],” Fendorf said. “It’s a steady state; you have arsenic in the sediment and arsenic in the water. It’s been happening for thousands of years, and it’ll just keep doing that.”
Fendorf stressed that the project was not one without hope of solution. He recently returned from a conference in Cambodia about how to proceed using the new findings. The conference stressed how scientists can help inform policy-makers and the public.
In addition, Fendorf mentioned specific measures being considered to remedy the problem for the citizens of the delta who have no other source of water and are running out of time against the health risks.
“You can filter the water,” he said, “but you have a number of risk factors—how do you prevent filter failure and how do you work if a filter does fail?”
Due to limited options of other water sources, Fendorf said another option may have to be “rainwater harvesting.”
Cambodia’s civil war included genocide against citizens outside the government who were educated or held positions of power. Fendorf stressed that RDI Cambodia made sure the project worked cooperatively with the community in Phnom Penh to help educate them and provide work opportunities.
“That was RDI’s mantra–immerse themselves in the local community and not just bring in Westerners to do the work,” Fendorf said. “Helping to bring back an educated class is really important.”
Though on the right track, Fendorf qualified that this research is by no means an end or solution to the puzzle.
“It was an important step…[the research] is having and will continue to have a positive social influence,” he said. But, “We’re actually still working over there…It’s an ongoing process.”
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