Mapping chemical footprints in European streams
Many pesticides, industrial chemicals, and pharmaceuticals, as well as their degradation products, end up in streams and rivers after use.
A team of environmental chemists at the UFZ has therefore taken a closer look at 610 chemicals with known occurrence patterns or problematic effects and analyzed whether and in what concentrations they occur in European watercourses—from large rivers such as the Elbe, Danube, and Rhine to the Ebro and Tagus on the Iberian Peninsula to smaller streams in agricultural regions of Germany.
After analyzing 445 samples from 22 rivers, the researchers detected 504 of the 610 chemicals. They found 229 pesticides and biocides and 175 pharmaceutical chemicals, as well as surfactants, plastic and rubber additives, per- and polyfuoroalkyl substances (PFAS), and corrosion inhibitors.
They detected up to 50 chemical substances in 40% of the samples and 51–100 chemicals in a further 41%. In four samples, they were even able to detect more than 200 organic micropollutants. They detected the most substances—241 chemicals—in a water sample taken from the Danube.
In the samples, the environmental chemists most frequently found N-acetyl-4-aminoantpyrine, which is a degradation product of the analgesic metamizole. Little is known about the effects of this substance on freshwater ecosystems.
"For many of these metabolites, it is unclear how harmful they are to the environment. We still lack the necessary knowledge," says UFZ environmental chemist Saskia Finckh, co-lead author of the study. However, the negative effects of other substances detected in the waters have already been researched
One of the most common of these substances is the anticonvulsant carbamazepine, which is not readily biodegradable in bodies of water. It also impairs the reproductive capacity of invertebrates and delays the development of fish. Carbamazepine is, therefore, already on the watch list of the Federal Environment Agency (UBA) and is one of 23 other proposed priority substances to be added to the EU Water Framework Directive.
The effect of some other substances also frequently detected in the samples is also known. For example, the UFZ researchers frequently found the insecticides diazinon and fipronil, both of which are extremely harmful to aquatic invertebrates. In total, the chronic risk thresholds for invertebrates were exceeded for more than 70 chemicals detected in the waters. This means that prolonged or repeated exposure can lead to developmental disorders, among other things.
Many of the individual organic micropollutants are a problem for water bodies in their own right. However, there is an additional one to worry about. "The range of chemicals that are discharged into water bodies is a big problem. We still know far too little about the additive effects of these substances when they mix with each other", explains Dr. Eric Carmona, UFZ environmental chemist and co-lead author.
In order to be able to assess the impact of these mixing effects on the organisms living in the watercourses, the researchers applied the concept of the chemical footprint, which quantifies the potential of chemical mixtures to affect water quality—specifically, what chance of survival in aquatic organisms such as fish, crustaceans, and algae have at a particular site. The chemical footprint is calculated by relating the concentration of a chemical at a site to the expected effect.
The values for the chemicals detected are then summed. For each of these groups of organisms, there is a scientific limit value. Exceedances of this value may support the disappearance of vulnerable species from the ecosystem. The scientific limit values were exceeded in 74% of the samples tested. The risk is particularly high for crustaceans; at 15% of the sites surveyed, it is even acute, which means that the animals have little chance of survival at these sites.
The UFZ researchers conclude that despite many improvement measures, there are still too many chemicals in European waters. At many sites, the limit values are exceeded.
"Our data also show that it is not just individual substances but rather the large number of substances that contribute to this problem," says Finckh. It is, therefore, necessary to include even more chemicals in chemical water monitoring for the implementation of the EU Water Framework Directive because these have not yet been evaluated in an environmental context. More measurement data are also needed.
"It is often completely unclear what effects chemicals have on organisms in the water and in what concentrations," says Carmona. In these cases, model-based values have been used; however, these lead to greater uncertainty than the effect values measured. "Above all, we should be focusing more on their mixtures when assessing chemicals," says Finckh.
The findings are published in the journal Environment International.
More information: Saskia Finckh et al, Mapping chemical footprints of organic micropollutants in European streams, Environment International (2023). DOI: 10.1016/j.envint.2023.108371
The critical need to address chemical contamination in drinking water
A Special Issue of the Journal of Exposure Science & Environmental Epidemiology co-edited by Yale School of Public Health Associate Professor Dr. Nicole Deziel, PhD, presents the latest research on exposure, health, and justice issues surrounding chemical contamination in drinking water. This Special Issue includes 17 articles authored by experts from around the globe and across multiple disciplines including environmental engineering, hydrology, exposure science, epidemiology, toxicology, and climate science. Many of the papers emerged from an international symposium organized by Dr. Deziel and Associate Research Professor Dr. Cristina Villanueva, PhD, a drinking water expert with ISGlobal, and co-editor of the Special Issue. The symposium was held in Barcelona and virtually in September 2022 while Dr. Deziel was in residence on sabbatical. Dr. Deziel discussed the focus of the Special Issue in a recent online interview.
What are the specific concerns regarding human exposure to chemical contaminants in drinking water?
Populations worldwide are exposed to a myriad of chemicals via drinking water, yet only a handful of chemicals have been thoroughly evaluated with regard to human exposures and health. Furthermore, there are only federal drinking water standards for approximately 100 different chemicals. Some of the existing standards have not been updated for quite some time and there is concern that exposures to chemicals at concentrations below current standards could still be associated with an increased risk of health effects, such as birth defects and cancers. In addition, there are many emerging chemicals in drinking water (e.g., microplastics, 1,4-dioxane) that are unregulated. Lastly, we must consider the issue of water scarcity and climate change. As the world’s temperature rises, we are already seeing available public water supplies starting to dry up, resulting in an increase in desalination efforts in some areas and the use of treated wastewater in others to meet demand. Overall, we have limited knowledge of how climate events will affect the quality of drinking water, and the need for more research is discussed in the Special Issue.
We need coordinated efforts to generate new health data for emerging contaminants.
How is science responding to these concerns?
This Special Issue showcases some of the innovative new research and technologies scientists have come up with to improve chemical surveillance in drinking water and better evaluate the possible health effects attributable to contamination. This includes better methods for monitoring and evaluating water supplies, improved biological assays, and novel methods for detecting harmful particulates in drinking water. We expect that these new studies will help inform regulations, encourage development of new methods and tools for assessing exposure to drinking water contaminants, and identify important issues pertaining to equity and environmental justice.
What are some of the challenges and opportunities in conducting research in this important area of public health?
Many chemicals are generally “invisible” in that they do not alter the color or odor of drinking water, and many of the associated effects are not observable for decades, making our ability to identify links between exposure and disease challenging. In addition, current tools and techniques for evaluating drinking water related exposures are limited and lag behind what is available for other environmental contaminants such as air pollution. So, there is definitely a need for additional and better data. Also, despite water contaminants often occurring in mixtures, most of the existing evaluations and related policies and regulations focus on individual chemicals without consideration of potential interactions between chemicals.
There is also an equity issue. Approximately 15% of Americans rely on domestic (private) wells for home drinking water. These are not covered by federal regulation, and the responsibility for testing or treating the well water falls on the property owner. Because private wells are not subject to regular monitoring or testing, water quality data in more rural areas are limited. Public drinking supplies also present risks. One study featured in this Special Issue found that 2.6 million people in the U.S. are relying on water systems where average fluoride concentrations exceed World Health Organization guidance limits. A separate study found that manganese in drinking water frequently exceeds U.S. guidelines, so there is lots to be concerned about, especially in regard to how these concentrations may impact vulnerable populations such as children.
As for the opportunities that lie before us, this Special Issue provides a framework for what needs to be done to address this critical public health concern. We need coordinated efforts to generate new health data for emerging contaminants. We need to strengthen drinking water standards and treatment technologies. We need to collect and disseminate more drinking water quality data, and we need to upgrade our drinking water infrastructure
Featured in this article
Nicole Deziel, PhD, MHS
Associate Professor of Epidemiology (Environmental Health Sciences); Co-Director, Yale Center for Perinatal, Pediatric and Environmental Epidemiology (CPPEE)
Combined advanced oxidation dye-wastewater treatment plant: design and development with data-driven predictive performance modeling
npj Clean Water 7, Article number: 15 (2024)
Abstract
The recalcitrant nature of the industrial dyes poses a significant challenge to existing treatment technologies due to the stringent environmental regulations. This combined with the inefficiency of a single treatment method has led to the implementation of the combination of primary, secondary, and tertiary treatment processes, which fails during complex secondary aeration processes due to variable pH loads of industrial effluent wastewater. This article presents a modified design methodology of a pilot-scale micro-pre-treatment unit using a solar-triggered advanced oxidation process reactor that both effectively controls the influent variability at the source and mitigates textile effluents for making the discharge reusable for different industrial purposes. The proposed modified combination technique of controlled serial processes inclusive of primary, secondary, and tertiary treatment steps with ZnO/ZnO-GO NanoMat-based advanced oxidation process demonstrates complete remediation of industrial grade effluent with effective reuse of the discharge. Further, a reliable prediction model for estimating water quality parameter using machine learning models are proposed. Multi-linear regression and Artificial Neural network modeling provide simple, accurate, and robust prediction capabilities, which are evaluated for the efficiency of the processes. The generated prediction models capture the output parameters within an acceptable level of accuracy and allow compliance with the discharge Inland Water Discharge Standards (IWDS).
How aromatic dissolved organic matter affects organic micropollutant adsorption
Activated carbon is employed for the adsorption of organic micropollutants (OMPs) from water, typically present in concentrations ranging from ng L−1 to μg L−1. However, the efficacy of OMP removal deteriorates considerably due to competitive adsorption from background dissolved organic matter (DOM), present at substantially higher concentrations in mg L−1. Interpreting the characteristics of competitive DOM is crucial in predicting OMP adsorption efficiencies across diverse natural waters.
In a study published in Environmental Science and Ecotechnology, a multi-national team describes the intricate influence of aromaticity and polarity in low MW DOM competition, from a fraction level to a compound level. They achieved this by employing direct sample injection liquid chromatography coupled with ultrahigh-resolution Fourier-transform ion cyclotron resonance mass spectrometry.
Anion exchange resin pre-treatment eliminated 93% of UV254-active DOM, predominantly aromatic and polar DOM, and only minimally alleviated DOM competition. Molecular characterization revealed that nonpolar molecular formulas (constituting 26% PAC-adsorbable DOM) with medium aromaticity contributed more to the DOM competitiveness.
Isomer-level analysis indicated that the competitiveness of highly aromatic LMW DOM compounds was strongly counterbalanced by the increased polarity. These findings suggest that aromatic DOM (as measured by UV254) was not essentially competitive against OMPs in adsorption.
The study illustrates the counterbalancing effect of aromaticity and polarity in understanding the competitive adsorption of DOM and highlights the limitations of relying solely on aromaticity or UV254-based methods as the sole interpretive metric.
More information: Qi Wang et al, How aromatic dissolved organic matter differs in competitiveness against organic micropollutant adsorption, Environmental Science and Ecotechnology (2024). DOI: 10.1016/j.ese.2024.100392
Provided by Eurasia Academic Publishing GroupA demonstration of substituent effects in anti-aromatic compounds
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