Through his work at the Nicholas School of the Environment, Vengosh and his research team have demonstrated the widespread prevalence of uranium in India’s groundwater.
-By Namrata Jha
A recent study led by Duke University researchers found widespread uranium contamination in groundwater from aquifers in several states in India. The study authors note that although the main source of the uranium is natural, human activities are contributing to the problem through groundwater table decline and nitrate pollution.
Our Duke in India team followed up with one of the lead researchers, Avner Vengosh, to learn more about the findings. Vengosh is a professor of earth and ocean sciences at the Nicholas School of the Environment.
Q: Can you tell us why the groundwater table is declining? And what causes nitrate pollution?
A: Groundwater level decline is caused by the over-pumping of groundwater all over India, especially in northwestern India, where pumping rates exceed precipitation. This can happen when surface water is not available anymore because of overuse and climate change, and more groundwater is extracted for mostly agriculture from underground aquifer reservoirs in areas where there is not enough rainfall to balance the over-pumping.
Nitrate is a known water pollutant. Excess nitrate from wastewater in urban areas and fertilizers in rural and agricultural areas can cause contamination of shallow groundwater. Nitrate can make uranium more soluble, or mobile in water.
Over-pumping and pollution combined present chronic challenges for India.
Q: What policies could be implemented to address groundwater contamination?
A: Some possible solutions include changing how irrigation systems work, such as using micro (or drip) irrigation to reduce the water used for agriculture and the over-pumping of groundwater. In addition, if we could treat domestic wastewater for reuse, we would generate alternative water sources for the agriculture sector and would also reduce groundwater exploration and pollution.
Q: Do the higher levels of uranium in water also have an effect on crops? If so, how can this be measured?
A: We do not know the exact mechanism of accumulation of uranium in plants or the possible effects of human health. This has not been investigated in India as far as we know.
Q: Do any remediation technologies and preventive management practices exists to treat uranium contamination? What possible challenges do we face to implement these?
A: The technologies for treating uranium contamination are well established, such as reverse osmosis, which is a commonly used method for water purification.
The first step is to recognize the problem, then to map those “hot spots” where potentially large numbers of people could be affected and target those areas for remediation and management. While uranium contamination was known in some areas, our study has revealed that this is a large scale problem all over India and thus recognizing the scope of the problem is the key for monitoring, mapping and identifying the groundwater that should not be used as drinking water.
Q: What are your future plans after these research findings have been finalized and published?
A: We are now working on the next scientific paper where we will evaluate other important contamination issues we have revealed in groundwater and drinking water in Rajasthan and Gujarat, two neighboring states in northwestern India.
Q: How does Duke’s approach of research-oriented teaching assist you in your efforts?
A: Our research involves graduate students – my PhD student Rachel Coyte leads the research. Through teaching water quality in my classes in the Nicholas School of the Environment, we present new data from the project to undergraduate and graduate students and receive feedback and evaluation on our research. This combination of research and teaching is a unique aspect of Duke University’s approach to learning.