Markus Andrews

Perfluorinated and polyfluorinated alkyl substances (PFAS) have been found in more than 2,800 US communities.Credit: Alexander Safonov/Shutterstock

The US Environmental Protection Agency (EPA) has proposed the first limitations on a set of pervasive and dangerous ‘forever chemicals’ in US drinking water. The chemicals, known for their strong carbon–fluorine bonds, are difficult to destroy and have become widely dispersed in the environment. Scientists and engineers are busy developing ways to extract the chemicals more efficiently from water and soil and break them down, but water utility companies warn that meeting the EPA’s new standards will be expensive in the short term — possibly prohibitively so for small water-treatment facilities.“This is a huge deal, in terms of protecting public health, but also in terms of what it’s going to take to accomplish,” says Michelle Crimi, an environmental engineer at Clarkson University in Potsdam, New York.
Tainted water: the scientists tracing thousands of fluorinated chemicals in our environment
Proposed on 14 March, the regulation targets perfluorinated and polyfluorinated alkyl substances (PFAS), a class of thousands of nearly indestructible compounds used in everything from non-stick cookware and waterproof clothes to industrial materials and cosmetics. Once called miracle chemicals for their hallmark durability, PFAS accumulate in the environment and in people; even minute amounts increase the risk of cancer, as well as the risk of developmental and other health problems1, research shows.The EPA suggested a voluntary limit for PFAS in drinking water in 2016, but this is the first time it has advanced a mandatory requirement. The core of the proposal would restrict two of the most dangerous PFAS compounds, PFOA and PFOS, to four parts per trillion. That is the lowest level that is detectable using current laboratory tests, although the agency has determined that there are risks associated with much lower concentrations. Another four chemicals would be regulated as a mixture.Similar movements to rein in PFAS are afoot internationally. At the extreme end of the spectrum, the European Union is considering legislation that would ban the production of PFAS altogether.Health costsAchieving the EPA’s proposed regulation won’t be cheap. PFAS contamination has been found in around 2,800 communities in the United States, according to the Environmental Working Group, an advocacy organization based in Washington DC, and research by the group suggests that it probably affects the water supplies of at least 200 million people2. And although the use of PFOA and PFOS has mostly been phased out in the United States, the group has identified around 30,000 industrial facilities that could be using countless other compounds in the PFAS family.
How to destroy ‘forever chemicals’: cheap method breaks down PFAS
Numerous states have already set limits on PFAS in drinking water, and water providers have demonstrated that existing technologies such as carbon filtration can reduce PFAS amounts to undetectable levels. But installing such technologies nationally could be costly, with the financial burden falling disproportionately on smaller water-treatment systems. For facilities large and small, adding PFAS filtration will have to be weighed against other priorities, such as replacing lead pipes, says Chris Moody, a regulatory analyst with the American Water Works Association (AWWA), which is based in Denver, Colorado, and represents more than 4,300 utility companies that provide some 80% of the US drinking-water supply.By one measure, the EPA estimates that implementing its proposal nationally would cost around US$772 million annually, but a study commissioned by the AWWA using similar assumptions suggests that the price tag could be around $2.9 billion a year. The EPA says that more than $9 billion is already available through a US infrastructure law enacted in late 2021, but Moody stresses that this is just a start: the AWWA-estimated cost over 20 years is $58 billion.If history is any indicator, however, costs will probably come down over time, says Melanie Benesh, vice-president of government affairs at the Environmental Working Group. “With regulation often comes market innovation,” she adds.Innovative solutionsScientists and engineers started investigating technologies years ago, when the risks posed by PFAS became clear. Research has focused on methods to more efficiently remove PFAS from drinking water, clean up groundwater contamination or destroy the chemical compounds.The upshot is that a variety of promising technologies are now available, from carbon filtration and ion-exchange systems that can separate PFAS from drinking water to electrochemical and gasification methods to break down PFAS, says Patrick McNamara, an engineer at Marquette University in Milwaukee, Wisconsin. But scaling them up to be practical could be challenging, he adds.For her part, Crimi is working with the US Department of Defense to test a technology that could be used to clean up plumes of PFAS contamination in groundwater before they leach into drinking-water supplies. Starting as early as this year at Peterson Space Force Base in Colorado Springs, groundwater will be collected inside a horizontal well and funnelled through a reactor developed by Crimi’s team that uses ultrasound waves to break the carbon–fluorine bonds in PFAS3.“We know it’s effective in the lab,” she says, but there are always things to learn when scaling up to field operations.The EPA is accepting comments on the proposal until mid-April. More

The United Nation 2023 Water Conference offers a critical opportunity to catalyse actions and innovations that bring increased water security to vulnerable communities across the globe. Researchers have an important role in supporting the delivery of needed on-the-ground impact, but their work must be informed by the priorities and necessities of Global South implementors.Too many of the images on our news feeds show the destructive power of water as droughts and floods ravage communities across the globe. The super-charging of the hydrological cycle from increased atmospheric greenhouse gas levels is adding stresses to water resource systems that are already challenged by over-exploitation, degradation and rising demand (Fig.1). Societies everywhere aspire to ‘water security’1, in which our management of water resources meets the diversity of human health, livelihoods, nature, and production needs, while reducing water risks to acceptable and manageable levels. The urgency of overcoming the gap between aspiration and the reality of water insecurity for billions of people was recognized by heads of government and heads of state who took part in the High-Level Roundtable on Water Security convened at the Conference of the Parties (COP) 27 in Sharm El-Sheikh, Egypt, in November 2022. They called for increased global cooperation, ramping up of investment, and higher political priority for water. Governments, for the first time, agreed explicitly at COP27 2 on the critical role of water systems in climate action. More

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Competing interests
J.H.M. worked as an advisor to the Asian Development Bank and World Bank on water and climate change issues. He is currently working with a coalition of national party, private sector, and NGO groups on a set of cases and recommendations to articulate water resilience as an operational economic concept, which is funded by the Kingdom of the Netherlands, GIZ, and the Kingdom of Spain. More

Ammonia (NH3) is a small and uncharged molecule typically used as a fertilizer, refrigerant, a fuel, and it is generated in wastewater processes1. Since ammonia is a fuel with a high energy density, it is possible to take this advantage by converting ammonia to nitrogen and electrical energy via the ammonia oxidation reaction (AOR). This reaction requires a catalyst to decrease the energy barrier that prevents the molecule from reacting and transforming into nitrogen. The AOR has been taken to the International Space Station (ISS) using an autonomous potentiostat system with electrode arrays, fluid pumps, and liquid reservoirs, and an autonomous potentiostat.The anodic electrochemical oxidation of ammonia was done on platinum nanocubes2 catalyst on screen-printed carbon electrodes (SPE). The cited literature suggests that under standard conditions, the products of the AOR on monocrystalline platinum (i.e., Pt{100}) is molecular nitrogen at an applied bias of 0.65 V vs. NHE. Nevertheless, other oxides of nitrogen may form at more positive potentials3,4. The gas molecules produced by the electro-oxidation of ammonia can detach from the catalyst interface due to the buoyancy effects that are exerted when in the presence of gravity. Below you may find an AOR mechanism developed by Gericher-Mauerer mechanism5.$$NH_{3(aq)} to NH_{3ads}$$
(1)
$$NH_{3ads} + OH^ – to NH_{2ads} + H_2O + e^ -$$
(2)
$$NH_{2ads} + OH^ – to NH_{ads} + H_2O + e^ -$$
(3)
$$NH_{xads} + NH_{y;ads} to N_2H_{x + y;ads}$$
(4)
$$N_2H_{x + y;ads} + left( {x + y} right)OH^ – to N_2 + left( {{{{mathrm{x}}}} + {{{mathrm{y}}}}} right)H_2O + left( {x + y} right)e^ -$$
(5)
$$NH_{ads} + OH^ – to N_{ads} + H_2O + e^ -$$
(6)
Under microgravity conditions the AOR has shown to have a lower current density because of the lack of buoyancy which allows the gaseous molecules to remain/stay near or at the electrode catalyst interface6,7,8. The lack of buoyancy for mass transfer convection affects the efficiency of the AOR at the platinum surface6. In a parabolic flight where a direct ammonia alkaline fuel cell (DAAFC) was used, the performance decreases up to 27% when using platinum nanocubes supported on Vulcan (Pt-V)8. This catalyst was selected for the ISS AOR study since it is robust and provides the means to achieve reproducibility in our experiments. In addition, it showed the highest AOR current densities9.The purpose of the Ammonia Electrooxidation Lab at the ISS (AELISS)10 project was to develop an autonomous electrochemical systems for studies at the ISS and to validate the previous results under parabolic flights6,7,8 and elucidate the factors affecting the ammonia oxidation reaction during long-term μG conditions at the ISS. There is an interest on electrochemical processes in space for Environmental Control and Life Support System11,12.For the AELISS experiment an autonomous potentiostat needed to be developed for the ISS, a plug-and-play device. Autonomous potentiostats have been developed for wearable technologies13 and smartphones14. For the ISS, a 2-U Nanorack (Nanode)15 (4” x 4” x 8”) was connected to the ISS station equipment rack through a USB-b port. Inside the Nanode the AELISS was placed, which consisted of an autonomous potentiostat, two screen-printed electrode (SPE) Channel Flow-Cells (Metrohm DropSens), two Dolomite Microfluidics peristaltic micropumps, two liquid plastic containers, and a USB flash data storage drive. The autonomous potentiostat, designed and produced by NuVant Systems Inc., controlled all the AELISS components. The AELISS was launched to the ISS on a cargo resupply mission CRS-14/NG-14, in the vehicle Antares, at 9:38 p.m. EDT on October 1, 2020. The data acquisition followed is shown in Fig. 1.Fig. 1Ammonia Electrooxidation Lab at the ISS electrochemical experimental cycles summary.Full size imageThe aim of this research work is to create an autonomous electrochemical device able to improve the time and reproduction of multiple cyclic voltammetry and chronoamperometry experiments at the International Space Station. This will provide a better insight into the selected platinum nanocube catalyst performance for the ammonia oxidation reaction (AOR) and compare results with those generated on Earth gravity. More

Study populationA total of 39 volunteers participated in the study, including 24 women (60%), 14 men (37%), and 1 non-binary (3%), with an average age of 40.7 years (standard deviation (SD) = 10.2 years, range = 26–76 years). Educational level was university or more among 35 (90%) and a high school among 4 (10%). Average consumption of unfiltered tap, bottled, and filtered tap water were, respectively 0.6 (SD = 0.5, range = 0.1–1.5), 0.5 (SD = 0.4, range = 0.3–1.5), and 0.4 (SD = 0.5, range = 0.1–1.5) L/day, based on a self-reported water consumption questionnaire.PFAS, bisphenol A, and nonylphenol in tap waterIn total, 35 PFAS were analyzed in tap water, of which only perfluoroalkyl acids (PFAA; 7 carboxylates and 3 sulfonates) were above the quantification limits, mainly with a carbon chain length shorter than eight (≤C8); while C10, C11 and C12 carboxylates were only detected in one or two samples. Total PFAS detection rate for the first sampling was 79%, and 69% for the second sampling (Table 1). The most frequently detected ( >50%) compounds during the first sampling were perfluoropentanoate (PFPeA) (64%; median = 3.3 ng/L), perfluorobutane sulfonate (PFBS) (64%; median = 9.2 ng/L), perfluoroheptanoate (PFHpA) (52%; median = 3.0 ng/L), perfluorohexanoate (PFHxA) (31%; median = 13.0 ng/L) and PFOS (52%; median = 12.5 ng/L), while the other PFAS showed detection frequencies lower than 12% (Table 1, Fig. 1). Similarly, the most prevalent compounds during the second sampling were PFPeA (62%; median = 4.0 ng/L) and PFBS (45%; median = 6.8 ng/L), whereas PFOS and PFHpA were present in 4.8% and 24% samples, respectively (Table 1, Fig. 1). The PFAS composition profile in the first sampling was dominated by PFBS (25.9%), PFOS (22.1%), PFPeA (17.6%), PFHxA (16.2%) relative to the total PFAS concentrations (Fig. 2). In the second sampling, high contributions to total PFAS concentrations were observed for PFPeA (45.7%), and PFBS (39.2%) (Fig. 2). To our knowledge, this was the first study analyzing ether-PFAS (e.g., GenX, and ADONA) in drinking water of the Barcelona region, showing non-detected levels.Table 1 Number (%) of samples above the limit of quantification (≥LOQ), and concentrations (ng/L) of target compounds in unfiltered tap water samples collected in 42 locations in Barcelona, Spain, in repeated sampling campaigns (August–October 2020, and May 2021).Full size tableFig. 1: PFAS concentrations (ng/L) in tap water.Unfiltered tap water samples were collected in 42 locations in Barcelona, Spain, in repeated sampling campaigns (August–October 2020, and May 2021). The line within the box marks the median, the boundaries of the box indicate the 25th to the 75th percentiles, and the dots denote observations (samples) corresponding to PFAS concentrations.Full size imageFig. 2: Average percentage contributions of individual PFAS concentrations relative to total PFAS concentrations detected in drinking water samples.First sampling (N = 42; S1 DW), second sampling (N = 42; S2 DW), and urine samples of the first sampling (N = 39; S1 Urine).Full size imageCompared to previous studies conducted in Barcelona, replacement PFAS (PFPeA, PFHxA, PFBS) and PFHpA were the most predominant compounds detected in the tap water samples, with observed increasing concentrations over the last 10 years (Supplementary Table 1)16,17.This dominance of PFAS with fewer than eight carbons ( More

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.This is a summary of: Shumilova, O. et al. Impact of the Russia–Ukraine armed conflict on water resources and water infrastructure. Nat. Sustain. https://doi.org/10.1038/s41893-023-01068-x (2023). More