research paper on groundwater pollution

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• Review Article
• Published: 31 January 2023

Global water resources and the role of groundwater in a resilient water future

• Bridget R. Scanlon   ORCID: orcid.org/0000-0002-1234-4199 1 ,
• Sarah Fakhreddine 1 , 2 ,
• Ashraf Rateb 1 ,
• Inge de Graaf   ORCID: orcid.org/0000-0001-7748-868X 3 ,
• Jay Famiglietti 4 ,
• Tom Gleeson 5 ,
• R. Quentin Grafton 6 ,
• Esteban Jobbagy 7 ,
• Seifu Kebede 8 ,
• Seshagiri Rao Kolusu 9 ,
• Leonard F. Konikow 10 ,
• Di Long   ORCID: orcid.org/0000-0001-9033-5039 11 ,
• Mesfin Mekonnen   ORCID: orcid.org/0000-0002-3573-9759 12 ,
• Hannes Müller Schmied 13 , 14 ,
• Abhijit Mukherjee 15 ,
• Alan MacDonald   ORCID: orcid.org/0000-0001-6636-1499 16 ,
• Robert C. Reedy 1 ,
• Mohammad Shamsudduha 17 ,
• Craig T. Simmons 18 ,
• Alex Sun 1 ,
• Richard G. Taylor 19 ,
• Karen G. Villholth 20 ,
• Charles J. Vörösmarty 21 &
• Chunmiao Zheng   ORCID: orcid.org/0000-0001-5839-1305 22  

Nature Reviews Earth & Environment volume  4 ,  pages 87–101 ( 2023 ) Cite this article

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An Author Correction to this article was published on 29 March 2023

This article has been updated

Water is a critical resource, but ensuring its availability faces challenges from climate extremes and human intervention. In this Review, we evaluate the current and historical evolution of water resources, considering surface water and groundwater as a single, interconnected resource. Total water storage trends have varied across regions over the past century. Satellite data from the Gravity Recovery and Climate Experiment (GRACE) show declining, stable and rising trends in total water storage over the past two decades in various regions globally. Groundwater monitoring provides longer-term context over the past century, showing rising water storage in northwest India, central Pakistan and the northwest United States, and declining water storage in the US High Plains and Central Valley. Climate variability causes some changes in water storage, but human intervention, particularly irrigation, is a major driver. Water-resource resilience can be increased by diversifying management strategies. These approaches include green solutions, such as forest and wetland preservation, and grey solutions, such as increasing supplies (desalination, wastewater reuse), enhancing storage in surface reservoirs and depleted aquifers, and transporting water. A diverse portfolio of these solutions, in tandem with managing groundwater and surface water as a single resource, can address human and ecosystem needs while building a resilient water system.

Net trends in total water storage data from the GRACE satellite mission range from −310 km 3 to 260 km 3 total over a 19-year record in different regions globally, caused by climate and human intervention.

Groundwater and surface water are strongly linked, with 85% of groundwater withdrawals sourced from surface water capture and reduced evapotranspiration, and the remaining 15% derived from aquifer depletion.

Climate and human interventions caused loss of ~90,000 km 2 of surface water area between 1984 and 2015, while 184,000 km 2 of new surface water area developed elsewhere, primarily through filling reservoirs.

Human intervention affects water resources directly through water use, particularly irrigation, and indirectly through land-use change, such as agricultural expansion and urbanization.

Strategies for increasing water-resource resilience include preserving and restoring forests and wetlands, and conjunctive surface water and groundwater management.

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Change history

29 march 2023.

A Correction to this paper has been published: https://doi.org/10.1038/s43017-023-00418-9

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B.R.S. conceptualized the review and coordinated input. S.F. reviewed many of the topics and developed some of the figures. A.R. analysed GRACE satellite data and M.S. reviewed this output. Q.G. provided input on water economics. E.J. reviewed impacts of land-use change. S.R.K. provided data on future precipitation changes. L.F.K. provided detailed information on surface water/groundwater interactions. M.M. provided data on water trade. C.J.V. provided input on green and grey solutions. All authors reviewed the paper and provided edits.

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Scanlon, B.R., Fakhreddine, S., Rateb, A. et al. Global water resources and the role of groundwater in a resilient water future. Nat Rev Earth Environ 4 , 87–101 (2023). https://doi.org/10.1038/s43017-022-00378-6

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‘Garbage Lasagna’: Dumps Are a Big Driver of Warming, Study Says

Decades of buried trash is releasing methane, a powerful greenhouse gas, at higher rates than previously estimated, the researchers said.

By Hiroko Tabuchi

They’re vast expanses that can be as big as towns: open landfills where household waste ends up, whether it’s vegetable scraps or old appliances.

These landfills also belch methane, a powerful, planet-warming gas, on average at almost three times the rate reported to federal regulators, according to a study published Thursday in the journal Science.

The study measured methane emissions at roughly 20 percent of 1,200 or so large, operating landfills in the United States. It adds to a growing body of evidence that landfills are a significant driver of climate change, said Riley Duren, founder of the public-private partnership Carbon Mapper, who took part in the study.

“We’ve largely been in the dark, as a society, about actual emissions from landfills,” said Mr. Duren, a former NASA engineer and scientist. “This study pinpoints the gaps.”

Methane emissions from oil and gas production , as well as from livestock, have come under increasing scrutiny in recent years. Like carbon dioxide, the main greenhouse gas that’s warming the world, methane acts like a blanket in the sky, trapping the sun’s heat.

And though methane lasts for a shorter time in the atmosphere than carbon dioxide, it is more potent. Its warming effect is more than 80 times as powerful as the same amount of carbon dioxide over a 20-year period.

The Environmental Protection Agency estimates that landfills are the third largest source of human-caused methane emissions in the United States, emitting as much greenhouse gas as 23 million gasoline cars driven for a year.

But those estimates have been largely based on computer modeling, rather than direct measurements. A big reason: It can be difficult and even dangerous for workers with methane “sniffers” to measure emissions on-site, walking up steep slopes or near active dump sites.

Organic waste like food scraps can emit copious amounts of methane when they decompose under conditions lacking oxygen, which can happen deep in landfills. Composting, on the other hand, generally doesn’t produce methane, which is why experts say it can be effective in reducing methane emissions.

For the new study, scientists gathered data from airplane flyovers using a technology called imaging spectrometers designed to measure concentrations of methane in the air. Between 2018 and 2022, they flew planes over 250 sites across 18 states, about 20 percent of the nation’s open landfills.

At more than half the landfills they surveyed, researchers detected emissions hot spots, or sizable methane plumes that sometimes lasted months or years. That suggested something had gone awry at the site, like a big leak of trapped methane from layers of long-buried, decomposing trash, the researchers said.

“You can sometimes get decades of trash that’s sitting under the landfill,” said Daniel H. Cusworth, a climate scientist at Carbon Mapper and the University of Arizona, who led the study. “We call it a garbage lasagna.”

Many landfills are fitted with specialized wells and pipes that collect the methane gas that seeps out of rotting garbage in order to either burn it off or sometimes to use it to generate electricity or heat. But those wells and pipes can leak.

The researchers said pinpointing leaks doesn’t just help scientists get a better picture of emissions, it also helps landfill operators fix leaks.

Overseas, the picture can be less clear, particularly in countries where landfills aren’t strictly regulated. Previous surveys using satellite technology have estimated that globally, landfill methane makes up nearly 20 percent of human-linked methane emissions.

“The waste sector clearly is going to be a critical part of society’s ambition to slash methane emissions,” said Mr. Duren of Carbon Mapper. “We’re not going to meet the global methane pledge targets just by slashing oil and gas emissions.”

A growing constellation of methane-detecting satellites could provide a fuller picture. Last month, another nonprofit, the Environmental Defense Fund, launched MethaneSat , a satellite dedicated to tracking methane emissions around the world.

Carbon Mapper, with partners including NASA’s Jet Propulsion Laboratory, Rocky Mountain Institute, and the University of Arizona, intends to launch the first of its own methane-tracking satellites later this year.

Hiroko Tabuchi covers the intersection of business and climate for The Times. She has been a journalist for more than 20 years in Tokyo and New York. More about Hiroko Tabuchi

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The Omnipresence of PFAS—and What We Can Do About Them

PFAS are raising a red flag among public health and environmental advocates.

Morgan Coulson

Per- and poly-fluoroalkyl substances (PFAS)—also known as “forever chemicals”—are everywhere.

Created in the 1940s, these synthetic compounds are an unseen ingredient in many items that we use in our daily lives, like cleaning products, food packaging, nonstick cookware, cosmetics, personal care items like dental floss,  water-repellent clothing, as well as stain-resistant carpets and upholstery. Since the 1970s, they have also been used in firefighting foams and by the military.  

“Food is another potential source,” says  Carsten Prasse , PhD, MSc, assistant professor in  Environmental Health and Engineering . “Unfortunately, PFAS are also present in biosolids which are used as agricultural fertilizer,” creating a pathway from contaminated soil to produce in the grocery store.  

Because of their longevity and resistance to disintegration—a characteristic born of their carbon-fluorine chemical bonds—PFAS can last thousands of years. These “attributes also make them very resistant to degradation in our treatment systems,” says Prasse.

The most common method of destroying PFAS is incineration, but some studies  indicate that this fails to eliminate all the chemicals, and instead releases the remaining pollution into the air.

In water treatment systems, the main methods for destroying PFAS are reverse osmosis, activated carbon, and ion-exchange resins—but these technologies are costly. Other methods include  supercritical water oxidation ,  plasma reactors , and most recently,  sodium hydroxide (lye) and dimethyl sulfoxide , chemicals used in soap and as a medication for bladder pain syndrome, respectively.

But when items containing PFAS inevitably reach landfills, the compounds leach into the environment. And every day, people flush PFA-laden products—like shampoo, cleaning liquids, even some toilet papers—down the drain.

“If they're not removed in our wastewater treatment plants, [PFAS] get into our rivers, streams, and groundwater, which are commonly used for drinking water production,” Prasse says. “Around 50% of our rivers and streams contain measurable PFAS concentrations.”  

According to a  2020 study published in Science by the Environmental Working Group,  an estimated 200 million Americans are served by water systems that contain PFAS. And it’s not just public systems— a  2023 study by the U.S. Geological Survey found that approximately 20% of private wells are contaminated. 

These compounds are now so ubiquitous, that  an estimated 98% of the U.S. population has detectable concentrations in their blood. That’s concerning, since studies have shown that exposure to some PFAS may be linked to harmful health effects, both in animals and humans.

“We know today that even very low concentrations can impact the reproductive system, [have] developmental effects, increase risk of certain cancers, reduce immune response, as well as increase cholesterol levels,” Prasse says. The Environmental Protection Agency  also links the compounds to thyroid disorders, obesity, and asthma.

Individuals who may have had high exposure to PFAS—in firefighting or chemical manufacturing industries, for example—should consider blood testing, Prasse says. “I think it is valuable …  because it allows them at least to talk to medical professionals, to think about follow-up examinations, to really monitor potential health effects.”

Prasse says we still know very little about the health impacts of PFAS, especially on a population level. While these compounds have been around for some time, there is insufficient research to answer many questions that have emerged over decades.

But some action is being taken. Last year, the EPA proposed  the first federal limits on forever chemicals in drinking water. And in February 2024, the agency proposed  that nine PFAS be categorized as hazardous to human health —a designation only applied to substances that are toxic or cause cancer, genetic mutation, or embryo malformation.

“The main reason for the step that the EPA is taking is that there's increasing evidence that there are toxic effects on a variety of levels,” Prasse says. “It will hopefully lead to more research to address the presence of these compounds in the environment, but also to more efforts to really elucidate the health impacts of these chemicals.”

  The proposal would classify the chemicals as "hazardous constituents" under the Resource Conservation and Recovery Act, making it easier for the agency to clean up contaminated sites—and to allocate funds to treat affected drinking water.  

But these nine compounds are only the tip of the iceberg. 

“We estimate there are more than 12,000 individual PFAS compounds, and unfortunately for most of them, we have basically no understanding about toxicity, and we don't really know a lot about their occurrence in the environment,” Prasse says. “I think the step by the EPA is really urgently needed to protect our drinking water and ultimately our health.”

  A  small study published in Environment International this month showed that cholestyramine—a cholesterol-lowering drug—could help scrub toxic forever chemicals from the blood of people who have been highly exposed. But the most efficient way to reduce contamination is preventatively, Prasse says, by regulating PFAS production and cleaning up the environment—especially waterways—and ensuring that our drinking water facilities are equipped to remove these compounds.

  “The issue at this point is really that we don't know what levels are concerning or lead to health effects, and which don't,” Prasse adds. “That's something that only the future will tell.”

Prasse and other experts recommend a variety of actions to minimize exposure to PFAS:  

• Avoid using nonstick cookware.
• Limit use of food packaging, such as grease-resistant takeout containers.
• Filter your water at the tap, with pitchers that are certified for PFAS.
• Avoid wearing water-resistant textiles.
• Seek out PFAS-free retailers’ products—including  menstrual products and large items like carpets or furniture.

Morgan Coulson is an editorial associate in the Office of External Affairs at the Johns Hopkins Bloomberg School of Public Health.

“Forever Chemicals” and Lead Exposure: Their Threat to Public Health (video)

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Today's Paper | April 04, 2024

From polar bears to groundwater, nature is riddled with `forever chemicals`

Comments on: “Spatio‑temporal evolution of groundwater quality and its health risk assessment in Punjab (India) during 2000–2020” by Praise Shukla Dericks, 10.1007/s11356-023–29200-6

• Letter to the Editor
• Published: 03 April 2024

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• Hardev Singh Virk   ORCID: orcid.org/0000-0001-6118-610X 1  

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Letter to Editor

The authors of this paper have reported their findings using spatio-temporal analysis based on groundwater quality data of 315 sites, taken from the reports of Central Groundwater Board (CGWB), Government of India. The non-carcinogenic health risk due to F¯ and nitrate contamination in groundwater has been assessed by estimating hazard quotient HQ. For this purpose, authors have collected data from secondary sources which may not be reliable. Results reported under the heading Health risk of fluoride and nitrate and Fig. 7 are contradictory to our findings (Nizam et al. 2022 ; Virk 2022 , 2023 ).

Authors report high F¯ concentration in the Malwa region of Punjab consisting of Bathinda, Mansa, Fazilka, and Sangrur districts in the year 2000. Similarly, during the year 2020, 5 sampling sites in the Bathinda district and 1 location in Mansa and Sangrur each have F¯ concentration > 4 mg/l. It can be observed in Fig. 7 that during 2020, the health hazard quotient for F¯ shows the groundwater is unsafe in districts Moga, Barnala, Bathinda, Sangrur, and Mansa. We have no objection to results of Malwa region districts.

Figure 7 of authors’ paper shows Patiala District as a safe zone for both Fluoride and Nitrate with HQ < 1. There is no discussion about these contaminants for Patiala district in authors’ paper. In our study (Nizam et al. 2022 ), we found about 98% of groundwater samples of Patiala district with fluoride concentrations > 1.5 mg/L, and about 23% of the samples contain > 4 mg/L fluoride, with HQ values > 1 in all cases. A study undertaken by Kaur et al. ( 2020 ) of 1600 school children of Patiala city shows the adverse effects of fluoride in the prevalence of dental caries in 40% cases. Patiala district has higher fluoride contamination compared with Malwa districts.

Results of our investigations (Virk 2022 , 2023 ) for Nitrate contamination in groundwater of Patiala district are also in contradiction with authors’ paper. Patiala district is found to be a ‘hot spot’ of nitrate contamination of groundwater. Authors report Patiala district in safe zone with HQ value < 1 (Fig. 7). Our study reports HQ Nitrate values of 45.59 and 106.38 for adults and children, respectively, corresponding to maximum concentration of Nitrate in groundwater of Patiala district (Virk 2022 ). Out of seven districts investigated for health hazards of nitrate in groundwater, including some from the Malwa region studied by authors, Patiala district recorded maximum contamination due to nitrate occurrence in its groundwater (Virk 2022 ).

Kaur S, Kaur A, Singh R, Avasthi A, Fatima A (2020) Prevalence of dental caries in 5- to 12-year-old school children of Patiala City. Punjab Dent J Adv Stud 08:01–04. https://doi.org/10.1055/s-0040-1703026

Article   CAS   Google Scholar  

Nizam S, Virk HS, Sen IS (2022) High levels of fluoride in groundwater from Northern parts of Indo-Gangetic plains reveals detrimental fluorosis health risks. Environmental Advances 8:100200. https://doi.org/10.1016/j.envadv.2022.100200

Virk HS (2022). Groundwater Contamination in Punjab Due to High Levels of Nitrate (NO 3 - ) and Its Health Hazards: A Preliminary Report. Research & Reviews: A Journal of Toxicology 12(3): 18–26. https://medicaljournals.stmjournals.in/index.php/RRJoT/article/view/3093

Virk HS (2023). A Study of Groundwater Contamination of Patiala District as a ‘HOT SPOT’ in Punjab. J. Water Pollution & Purification Research 10(1): 1–13. https://techjournals.stmjournals.in/index.php/JoWPPR/article/view/1410

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Virk, H.S. Comments on: “Spatio‑temporal evolution of groundwater quality and its health risk assessment in Punjab (India) during 2000–2020” by Praise Shukla Dericks, 10.1007/s11356-023–29200-6 . Environ Sci Pollut Res (2024). https://doi.org/10.1007/s11356-024-32859-0

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DOI : https://doi.org/10.1007/s11356-024-32859-0

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Rio Tinto’s Madagascar mine may face lawsuit over pollution claims

Mining company hit with accusation it contaminated waterways with harmful levels of uranium and lead

Rio Tinto is facing a likely lawsuit in an English court brought by the UK-based law firm Leigh Day on behalf of people living in villages near a mine in Madagascar.

In a letter of claim, a document that is an early step in a lawsuit, the villagers accuse Rio Tinto of contaminating the waterways and lakes that they use for domestic purposes with elevated and harmful levels of uranium and lead, which pose a serious risk to human health.

The mine, operated by Rio Tinto subsidiary QIT Madagascar Minerals (QMM), extracts ilmenite, a major source of titanium dioxide, which is mainly used as a white pigment in products such as paints, plastics and paper. It also produces monazite, a mineral that contains highly-sought-after rare-earth elements used to produce the magnets in electric vehicles and wind turbines.

Leigh Day commissioned testing of people’s blood lead levels in the area around the mine as part of its research. According to the claim, which was sent on Tuesday, the testing shows that 58 people living around the mine have elevated levels of lead, and the majority of cases exceed the threshold at which the World Health Organization (WHO) recommends clinical and environmental interventions, 5 micrograms per decilitre. The claim alleges that the most likely cause of the elevated levels is a result of QMM’s mine processes.

“Whilst Rio Tinto extracts large profits from its mining operations in Madagascar, our clients’ case is that they and other local families are being forced to consume water which is contaminated with harmful heavy metals. In bringing this case, our clients are seeking accountability and justice for the damage that has been caused to their local environment and their health,” Paul Dowling, Leigh Day’s lead partner on the case, said.

While a relatively small sample, Leigh Day’s blood lead level testing results are a significant development that may for the first time quantify the detrimental health impact their clients allege are posed by QMM. Both the pollution of surface water and lead poisoning are global problems, and the case will be watched closely not just by Rio Tinto shareholders but by global environmental justice advocates in other nations where villagers also accuse industrial giants of polluting their waterways.

“We have received the letter from Leigh Day,” said the Rio Tinto spokesperson, who declined to comment further on the allegations. The spokesperson pointed to a published report that states that the company’s recent water analysis had not detected metals, including uranium and lead, that had previously been identified as potential concerns.

Madagascar’s environmental regulator, the National Office for the Environment, or ONE, says it has periodically monitored QMM’s activities over the past decade and has tested the water after previous complaints about contamination. “In the face of these accusations, ONE requested several expert analyses … the results of which indicated no contamination of surface waters nor mining sites,” Hery Rajaomanana, ONE’s director of environmental integration and sustainable development, said in March.

Rio Tinto, which had net earnings of $12.4bn in 2022, has a troubled track record in Madagascar. Locals, civil society groups and media have accused the company of damaging the endangered forest, threatening rare endemic species, forcing villagers off their land without proper compensation, destroying fishers’ livelihoods and failing to honour its promises to employ local people. Communities have been protesting against the mine almost since its inception.

“QMM operates in a highly sensitive area from a water and broader environmental perspective,” wrote a Rio Tinto spokesperson, who declined to attach a name to the statements from the company. “We are committed to working to address any specific issues that community members raise, and to engaging in constructive dialogue on how we can mitigate impacts of our operations while generating tangible and sustainable benefits for our host communities.”

The 150-year-old metals and mining company has been embroiled in scandal for years. In 2020, Rio Tinto blew up two ancient Australian aboriginal sites to expand its iron ore mining in the region. In 2022, a review found that bullying, sexism and racism were rampant across the company . In March 2023, Rio Tinto agreed to pay a $15m penalty to the US Securities and Exchange Commission after accusations surfaced that in 2011 it paid $10.5m to a friend of the Guinean president to retain iron ore mining rights. The company is facing pressure from investors over water quality concerns at several of its mining sites, including in Madagascar and Mongolia.

“People were eating so well”

QMM started exploring for heavy mineral sands in Anôsy, Madagascar, along the south-eastern coast in 1986. The region is home to about 800,000 people, with more than 90% of rural residents living on less than $1.90 (£1.50) a day.

The area where the minerals were discovered is a unique ecosystem, a littoral forest occurring in the sandy substrates close to the Indian Ocean. Madagascar once had a continuous 1,600km band of littoral forest along its eastern coastline. Today, it is estimated that only a fraction of that forest remains intact. New species are being discovered there all the time, but many of them are already endangered by habitat destruction. Yet the region, with its famous lemurs and a concentrated diversity of plant species, remains one of the most important and fragile ecosystems in the world.

When Rio Tinto began exploring the area, the possible risks associated with a large-scale mineral sands project, including the potential for radioactive materials to be released into the surrounding environment, were not well known.

“People didn’t yet understand the ecological impact of the mine,” said Tahiry Ratsiambahotra, the founder of LuSud, an activist organisation that has become a thorn in the sides of the government and Rio Tinto. “So, parliament adopted the agreement.”

Before building the QMM mine, the company conducted a series of assessments to determine the potential social, environmental and economic impacts of the mine on the surrounding area. Baseline water testing from 2001 revealed that the surface water from lakes and rivers surrounding the mine was free from high levels of metals including lead and uranium.

To support its mining operations, QMM planned to construct a weir, or barrier, where Lake Ambavarano meets the mouth of the estuary that connects to the Indian Ocean to control water flows and water level heights. But the company was warned that the weir had the potential to permanently change the occasionally brackish lagoon system into freshwater, which would affect fish and fishers in the region. With support from the World Bank, it also built a port in Fort Dauphin to export raw materials to Rio Tinto’s processing plant in Canada.

Despite concerns by LuSud, the World Bank, and other bodies involved in early impact assessments of the mine, QMM received a legal licence to begin operations in 2005. The licence covered three mine sites to be mined sequentially under a 100-year lease from the Malagasy government.

The mine became operational in 2008. The barrier ended up entirely blocking inundations of salt water into Lake Ambavarano. Soon, nearly all the species of fish that thrived in the brackish conditions were gone. The extractive industry watchdog Publish What You Pay found in a March 2022 community survey that at least 27 fish species appear to have disappeared from the lakes since the start of the Rio Tinto mining operation.

“Before the weir, people were eating so well. They were happy. They were fishing,” said Olivier Randimbisoa, one of the lake fishers affected by the weir.

Randimbisoa has been fishing since he was 10 years old. Before the weir was built, he could choose whether he wanted to catch crab, shrimp, ocean fish or lake fish. He could make 100,000 ariary (about $22.40) each day from fishing. Now, he says he’s barely making a fraction of that.

Heavy sands

The QMM mine extracts ilmenite from mineral-rich sands by creating shallow, unlined, water-filled basins between five and 15 metres deep. By churning up the sands and passing them through a floating dredge, the mining process filters out the heavier sands, which contain ilmenite. The ilmenite is then extracted using electrostatic processing and shipped to Rio Tinto’s plant in Canada. Despite its small size, Madagascar was the fourth largest exporter of ilmenite in the world in 2022.

The mineral sands also contain radioactive elements, including uranium and thorium. The process of churning the sand allows these radioactive elements to dissolve in the mining water, which is then discharged as wastewater.

The Malagasy regulator requires an 80 metre buffer zone between a mining operation and any ecologically sensitive area to avoid contamination. In 2015, the government regulator approved QMM’s request to reduce this buffer zone from 80 metres to 50. But in 2017, Yvonne Orengo, the director of ALT-UK, a charity that works on issues in Madagascar, accused Rio Tinto of breaching the buffer zone based on a series of satellite images she captured using Google Earth.

Rio Tinto initially denied the breach in correspondence with ALT-UK. The company agreed to conduct an independent study and identified a private company called Ozius to carry it out. To ensure an independent review, Orengo enlisted the help of Dr Steven Emerman, a groundwater and mining expert, to conduct his own study. Using Ozius’s data as well as Google Earth images, Emerman calculated that, in addition to breaching the buffer zone, the company had encroached on to the lake bed by 117 metress, bringing the total breach to 167 metres, he said.

In early 2019, QMM announced that it would revise its plans and revert back to the 80-metre buffer zone. It later acknowledged that it had breached the original buffer zone.

The QMM mine relies on a “natural” system, usually referred to as passive water treatment, to treat its mining basin water. It releases the contaminated water into a series of “settling paddocks” to reduce the levels of floating particles, one indicator of water quality. When the water in the paddocks gets too high, the mine offloads the water into naturally occurring wetlands that connect to a nearby river. The idea is that the process of moving through the settling paddocks and wetlands would rid the mining basin water of its more harmful elements and allow safe water to flow into the surrounding environment.

One issue with passive water treatment systems is that they can remove contaminants, like lead and uranium, from process water and store them in the wetland sediment. A later change in wetland water chemistry, such as an increase in acidity, could remobilise those heavy metals back into dissolved form in the water column. “This is why passive water treatment systems are sometimes referred to as ‘chemical timebombs’,” said Emerman.

Rio Tinto refers to its tailings dam as a berm, or an artificial embankment, and its tailings as process water. There have been reports of berm failures at QMM since mining began, resulting in large releases of harmful mine waste. The first two were made in 2010 and 2018, and dead fish appeared in the lakes after the 2018 overflow.

In August 2020, QMM stopped regularly discharging its process water into the surrounding wetlands. The following year, Rio Tinto released a report that concluded its “natural” filtration system was not working as expected and excess levels of aluminium and cadmium were being released into the water around the mine.

Two additional berm failures occurred in early 2022, after a series of cyclones and other severe weather events battered the region. Dead fish had started appearing in the lakes again, which is what Randimbisoa, the fisher, witnessed. In response, the authorities banned fishing, which led to widespread protests from communities living around the mine.

Following the 2022 dead fish incident, QMM and the Malagasy environmental regulator analysed a series of water samples. The company says the analysis revealed no significant change to water quality in the surrounding water bodies and no link between the mine’s activities and the dead fish, but despite requests from civil society actors and the Intercept, the report has not been made available to the public.

In April 2022, ALT-UK commissioned Dr Stella Swanson, a Canada-based aquatic ecologist and radioactivity specialist, to analyse the potential causes of the fish deaths. She concluded that “the combination of acidic water and elevated aluminium in the water released from the QMM site is the most probable connection between the water releases and the fish kills observed after those releases.”

Rio Tinto and QMM dispute Swanson’s assessment, but Earl Hatley, the co-founder of the non-profit Lead Agency Inc, backs it up. A similar combination of metals and low pH in water have caused fish deaths near many other mining sites, Hatley said, including at the Tar Creek Superfund site in Oklahoma, where former lead and zinc mines caused environmental devastation, and poisoned fish and people living around the mining sites.

Blood and water

Clean water has long been a problem around the QMM mine, and in recent years, it has become the main one. About 15,000 people draw their drinking water from the lakes and waterways around the mine.

After Orengo discovered the buffer zone breach in 2017, ALT-UK asked Swanson to conduct a radioactivity study to determine the presence of radioactive material in the surrounding waterways. The study found that uranium – in concentrations up to 50 times the WHO drinking water quality guidelines for chemical toxicity – was detectable in samples from all QMM’s river water monitoring stations.

In a response, QMM denied having any impact on the high levels of uranium in the water and claimed that the elevated levels were a naturally occurring result of local geological conditions. “This is not a QMM-related impact and is an aspect of the water used by local communities before the commencement of construction or operations at QMM,” the company argued.

Emerman, the mining expert who studied the breach, conducted his own analysis using data from Rio Tinto and samples collected by local residents. He reported that the maximum downstream lead and uranium concentrations were 40 and 52 times higher, respectively, than the WHO recommended standards for drinking water. Emerman also found that lead levels were 4.9 times higher downstream of the mine and uranium levels were 24 times higher downstream. According to Emerman, these results, and their contrast with the 2001 baseline study, point to QMM as the source of contamination.

Late last year, Rio Tinto released its QMM water report 2021–2023, which included new water sampling data as well as additional information about the company’s developing water management practices. The report showed that all parameters were below the analytical limits of detection upstream and downstream of the mine’s release point during the reporting period. Emerman independently assessed the report and concluded that the new data confirmed “the detrimental impact of the QMM mine on regional water quality”, and that it failed to alter his earlier conclusions.

There were no blood lead levels testing results publicly available for the population living around the QMM mine until now. In its new claim, Leigh Day states that blood lead level testing on 58 people living around the mine, among them children, shows elevated levels of lead. Scientific studies have found that children with blood lead levels above the WHO’s threshold of 5 micrograms per decilitre are likely to suffer at least some amount of mental impairment as a result.

An expert clinical toxicologist working with Leigh Day has recommended periodic blood lead testing for all 58 of the clients who were tested. For at-risk groups such as children, women of child-bearing age, and those with a blood lead level above the WHO reference level, the expert has recommended additional interventions including clinical monitoring, more frequent blood lead testing, nutritional supplements and additional antenatal care, where appropriate. One client with particularly high blood lead levels has been advised to undergo chelation therapy, which helps remove pollutants from the bloodstream.

“Rio Tinto continues to make bold public commitments about safeguarding vital water sources and respecting the rights of those affected by its operations wherever in the world they may be,” said Dowling, of Leigh Day. “We trust the company will now stand behind those commitments and engage constructively with our clients’ claims at an early stage to ensure the communities no longer have to rely on polluted water and get the medical attention they need.”

Georges Marolahy Razafidrafara, a Mandramondramotra resident, used to work for the mine. Today, he worries about the water quality, especially because he has a daughter who is still just a toddler. “QMM always says: ‘Yeah, we take the water samples to analyse in the lab’ but we never get the results,” he said. “They always come back and say it’s drinkable, but they truck water into the mine [for their employees].”

The way Razafidrafara sees it, the local population were promised prosperity. Instead, they got poison.

This story was published in partnership with The Intercept . The reporting for this investigation was supported by a grant from Journalists for Transparency, an initiative of Transparency International.

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