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One Water, Many Solutions

On a summer morning, a storm dropped buckets of rain on the desert outside Tucson, Ariz. Water ran over the dry soil. Most of the water subsequently evaporated, but some parched plants drank their fill. What was left over sank into the ground, percolating into the aquifer below.

A few kilometers down the road, Tucson Water pumped groundwater from the same aquifer to a nearby reservoir, then through its treatment system. A Tucson ratepayer turned on her tap and used a few liters of water to give her dog a bath. The soiled water flowed into Tucson’s wastewater system and once again was treated. A portion of that recycled wastewater was released into the Santa Cruz River, where parkgoers enjoyed watching it flow through the city.

In Tucson, as in the rest of the world, every human interaction with water is connected to a broader water system.

But water practitioners haven’t always treated their work with the same interconnected approach. Instead, many cities and regions divide their water into three silos: drinking water, wastewater, and stormwater, each managed separately.

That approach is not meeting the needs of many communities. And a different approach, called One Water, is beginning to take its place.

One Water treats drinking water, wastewater, and stormwater as a single, interconnected entity and attempts to manage it holistically, bringing together water utilities, community members, business and industry leaders, researchers, politicians, engineers, and advocacy groups.

Recycled water flows into the Santa Cruz River in Arizona as part of the Santa Cruz River Heritage Project. Credit: Tucson Water

In a One Water approach, the Tucson ratepayer, water utility, and parkgoer are equal stakeholders, and water practitioners attempt to create a water system that works well for each of them.

“Partnerships and collaboration are at its core,” said Scott Berry, director of policy and government affairs at the US Water Alliance, a nonprofit membership organization dedicated to advancing a “One Water future for all.”

A holistic, inclusive approach is not without obstacles, though. Different stakeholders bring different priorities and practices and may have cultural, historical regulatory, and organizational barriers that keep them from collaborating effectively.

To navigate such challenges, water stakeholders from varied sectors across the United States come together at an annual conference (soon to be held every 18 months), the One Water Summit, hosted by the US Water Alliance. About 70% of attendees come as part of a delegation, a peer group, typically organized by region, whose members want to work together on U.S. water issues.

These delegations are the lifeblood of the summit and uniquely mirror the One Water approach: They’re meant to be highly collaborative, allowing stakeholders with very different priorities to come together and work toward a common cause. Though the framework is hindered by funding constraints and a lack of engagement from some sectors, delegations have provided a valuable opportunity for sharing knowledge and bringing One Water projects to fruition.

Siloed Systems

In the water sector, siloed systems are the norm. The inertia they engender can be hard to break when trying to build collaborative networks.

In some cases, siloed approaches contribute to unaligned regulations, which can limit a collaboration’s success, explained Caity Peterson, a research fellow at the Public Policy Institute of California’s Water Policy Center.

For example, someone working on a wastewater problem must navigate both environmental and health regulations. A One Water program might involve potable reuse, or recycling wastewater into drinking water by purifying it, filtering it, and diverting it to groundwater or reservoir supplies. Such a project needs to ensure that the recycled water complies with environmental regulations that govern water quality for irrigation and other nonpotable uses. But once that water is destined for a drinking water supply, it must also comply with health regulations. “A little bit of streamlining” of those regulations can bolster collaboration, Peterson said.

Siloed jurisdictions can present another challenge for water practitioners. Though the flow of water respects no political or system boundary, water managers do work within such jurisdictions, said Sarin Pokhrel, a water resource engineer for the Environment and Protected Areas Ministry of Alberta, Canada. (Some local governments within Alberta, such as Edmonton, where Pokhrel is based, use a One Water approach.)

British Columbia, where Pokhrel previously worked, is home to an array of jurisdictions: Municipalities govern water via local bylaws, Indigenous communities manage their own water, and districts follow broader regional plans. Unifying plans under a single framework that all levels of water management can follow is very challenging, he said.

The US Water Alliance added the delegation structure to its annual conference in 2016 as a way for water practitioners to overcome these barriers and move toward One Water ideals. Berry, who leads delegation work at the US Water Alliance, said he thinks of the delegation system as an opportunity for stakeholders to “road test” collaborations.

“It’s a way to test the waters of collaboration away from the normal sphere of influence.”

“It’s this idea of getting a bunch of folks together who may not work together often, or who may even be at odds with one another,” he said. “It’s a way to test the waters of collaboration away from the normal sphere of influence.”

Organizers of the One Water Summit encourage delegations, which can be assembled by anyone with the interest, ability, and time to recruit fellow delegates, to attend. Delegation members can register at a discounted rate, and the summit provides opt-in programming specifically for delegates. Around one thousand people and 20–40 delegations attend each year. Membership in any one delegation has ranged from fewer than 10 to almost 50 people, Berry said.

The first half day of each summit is dedicated to “peer exchanges,” where delegations present their work to each other. These presentations range from showcasing a particular success to workshopping a problem that the delegation is facing, Berry said.

At the 2023 Tucson summit, for example, the Tap into Resilience delegation hosted a peer exchange to brainstorm how to scale up distributed water infrastructure, a type of ultralocal water system meant to be more affordable than conventional water systems. The Climate Action delegation shared strategies for utilities to use capital investments to make progress on their climate plans. And the New Jersey delegates hosted a discussion about how delegations can build relationships with state governments to advance One Water.

At an end-of-summit plenary, delegations are invited to announce “commitments to action” for the coming year.

“The entire plenary, you’re surrounded by all this amazing work that’s going to be happening in all these different places,” Berry said. “You get a sense that you’re not alone and that there are opportunities for collaboration.”

Commitments to action range from informal directives to full proposals. Delegations at the 2023 summit committed to developing new One Water plans for their cities, improving community engagement around water issues, sharing what they’d learned with local leaders and policymakers, and constructing new green stormwater and water treatment facilities. Delegations that return to the subsequent summit are encouraged to share how they’ve progressed on their commitments.

One Water, Many Networks

Water practitioners report a strengthening of the depth and breadth of their collaborations as a result of participating in a delegation.

“I felt like I really got to know people in a different way, not just as colleagues but as friends,” said Rebekah Jones, communications director for the Iowa Soybean Association’s Iowa Agriculture Water Alliance, who attended the 2023 One Water Summit as part of the delegation from Iowa. Jones deepened her relationships with colleagues at the city of Cedar Rapids and Des Moines Water Works and especially enjoyed meeting members of a delegation from Hawaii, who shared how critical water is to Hawaiian culture and livelihoods.

Jennifer Walker of the Texas delegation, director of the Texas Coast and Water Program at the National Wildlife Federation, said she feels the same after attending multiple summits. When a delegation convenes away from their home community, “everybody has a little bit more time to focus on the content, spend some time together, and build relationships,” she said.

“We can come together in ways that would be almost impossible at home.”

Because Texas is such a large state, the delegation venue is crucial for getting Texas stakeholders, including nonprofits, utilities, engineers, consultants, elected officials, and community members in the same room.

The delegations are building relationships among people who don’t work together day-to-day, said Michelle Stockness, executive director of the Freshwater Society, a nonprofit based in Saint Paul, Minn. Stockness attended the 2023 summit as a member of the Minnesota delegation. “We’re building those relationships so that we can talk about hard things a little more easily.”

“We can come together in ways that would be almost impossible at home,” said Candice Rupprecht, a water conservation program manager for the city of Tucson and a member of the Tucson delegation, in a 2019 presentation.

Strengthened relationships have sparked meaningful progress on One Water projects across the country.

At the Tucson, Ariz., One Water Summit in 2023, the Minnesota delegation shared concerns about water quality and distribution. Credit: Michelle Stockness

At the 2023 conference, the Iowa delegation held an educational session for other summit attendees about urban and rural collaboration via an exercise about a fictional town called Farmersville and its picturesque Crystal River. Attendees attempted to fix a water quality problem in Farmersville—a suddenly odorous and murky Crystal River—while playing a role that was different from their real-life job. For example, a water researcher could act as mayor, and a utility staff member could role-play a farmer.

In the scenario, the urban community blamed rural farmers for soil erosion and nutrient pollution, whereas farmers accused the city of industrial pollution and ineffective waste management. Workshop attendees had to navigate these concerns as they developed a plan to improve water quality.

“It got people thinking out of the box about what it’s like to be in someone else’s shoes,” Jones said.

In New Jersey, water practitioners had already formed a coalition of community members, nonprofit organizations, government entities, and utilities when the delegation from the state began attending the summit in 2016. Participating as a delegation supplemented the group’s holistic effort, said Paula Figueroa, director of the Jersey Water Works Collaborative and a former New Jersey delegate. For the New Jersey delegation, the summit is an important source of energy to balance the sometimes draining, difficult work of advancing a One Water approach, she said.

After the 2022 summit, Figueroa noticed that two leaders, one a New Jersey utility staff member and the other an employee of the Jersey Water Works Collaborative, began to collaborate, inviting each other to more events and sharing the other’s work. The new relationship increased the visibility of a shared, primary project: replacing lead service lines across the state.

The summit offers delegations opportunities for interstate cooperation as well. Following conversations between the Pittsburgh and Milwaukee delegations at the 2022 and 2023 summits, delegates from Pennsylvania and Wisconsin held a dedicated learning exchange in Milwaukee the following year.

Some water issues in Pittsburgh would have taken 2 or 3 years each to solve, but as a result of knowledge gained in the Wisconsin exchange, “we were able to complete five or six problems in 2 or 3 years,” said Jamil Bey, founder of the UrbanKind Institute and a longtime member of the Pittsburgh delegation. “That learning exchange model is really powerful.”

The event in Milwaukee helped inform a new approach to addressing stormwater reclamation in Pittsburgh, for instance, said Kelly Henderson, who was part of the Pittsburgh cohort that attended the learning exchange.

One of the locations the group visited was Green Tech Station, a former brownfield site that the Northwest Side Community Development Corporation, a nonprofit in Milwaukee, had transformed into a stormwater reclamation facility. Green Tech Station can capture more than 380,000 liters of stormwater each time it rains—water that is then used to irrigate trees on the site. The facility also includes a prairie ecosystem with native plants, a pavilion to host educational programming, and a collection of artwork.

Shown here is Green Tech Station in Milwaukee, a former brownfield site that was restored as a water reclamation system. In April 2024, members of the Pittsburgh delegation visited Green Tech Station as part of a learning exchange. Credit: Northwest Side Community Development Corporation

Henderson, executive director of Grounded Strategies, a nonprofit focused on community-driven vacant lot reclamation, found Green Tech Station so inspiring that she decided to create something similar in Pittsburgh. Grounded Strategies, along with partners from the Department of City Planning in Pittsburgh and the Pittsburgh Water and Sewer Authority and elsewhere, recently received a $55,000 grant to start the project. As they plan the site, they’ll be in close contact with the group that constructed Green Tech Station, Henderson said.

Delegations can also facilitate cooperation between stakeholders with different immediate interests.

In 2017, for instance, the Tucson delegation committed to a lofty goal: returning perennial water flow to the Santa Cruz River. At the time, the stretch of the river in downtown Tucson flowed only during rainstorms.

Rupprecht, the Tucson Water conservation manager and four-time Tucson delegation member, said delegation members were key to advocating for Arizona’s Drought Contingency Plan, a change in state law that increased recycled water recharge credits. Under the Drought Contingency Plan, Tucson Water can receive credits for 95% of the water released into the Santa Cruz River, then use those credits in the future to secure additional water supply.

Within a year, Tucson Water’s Santa Cruz River Heritage Project had released enough recycled water to the river that it flowed anew for the first time in almost 80 years. The new stretch of perennial river restored plants, revitalized a ciénaga (wetland) ecosystem, and provided new habitat for wildlife such as herons, native toads, coyotes, and dragonflies.

Inclusivity Obstacles

Though many delegations have made tangible progress toward One Water goals, barriers still exist to achieving full cross-sector engagement.

“With something like One Water…if you don’t do a good job of building those relationships and building those ties between sectors, then there’s a risk it could be just some pleasant marketing but not really delivering the outcomes that it’s supposed to deliver,” Peterson said.

One major barrier is money. Attending the summit comes at a financial cost that can be too high for underfunded organizations.“It’s all about money,” said Pokhrel, the Alberta engineer. “Do we have enough budget? Do we have enough resources to fulfill this?”

“Most of the most vulnerable people who are having water issues, they don’t have the resources to participate.”

“Most of the most vulnerable people who are having water issues, they don’t have the resources to participate,” Bey said. “There’s a minimum threshold for organizational capacity that you have to have to connect you to these types of conversations.”

The US Water Alliance tries to help delegates from underfunded organizations attend the summit with a tiered registration fee system. “If you’re a small nonprofit, you’re going to pay less than a private company or a large urban utility,” Berry said. “The people who are more resourced, who can afford to pay more, do pay more, and that helps us subsidize the cost for the folks who are less well resourced.”

A little funding can go a long way to help include historically marginalized voices. With help from a grant from the US Water Alliance, for instance, in 2023 the Minnesota delegation was able to invite representatives from the Indigenous-led nonprofit Honor the Earth, as well as community members from the Environmental Justice Coordinating Council (EJCC). Members of EJCC had previously attended the 2022 One Water Summit in Milwaukee, where they had committed to working on issues of environmental health in Minnesota, particularly the impact of per- and polyfluoroalkyl substances (PFAS) on drinking water.

“Providing funding for community and tribal members was really important to get the people we wanted to be there and have that diverse representation.”

“Providing funding for community and tribal members was really important to get the people we wanted to be there and have that diverse representation of multiple perspectives,” Stockness said.

Delegates from Honor the Earth and EJCC could not be reached for comment in time for publication.

Berry and some past delegates said they feel that the agriculture industry is underrepresented at the summits, too. Agriculture is a huge element of the water system, responsible for about 70% of freshwater use worldwide. The proportion of agriculture practitioners at the summit is “still not as big as it could be, or should be,” said Sean McMahon, a sustainable agriculture consultant who has been involved in coordinating the Iowa delegation for five summits.

City utilities make up the majority of membership in the US Water Alliance, and urban organizations dominate the summit—a dynamic that may make the rural agriculture community feel ostracized, Peterson said. If members of the agriculture community are not engaging in a collaboration, that might mean the benefit of participating is not clear to them.

As in the fictional Farmersville, agriculture communities and urban water suppliers may not always see eye to eye. Farmers may be frustrated with what they see as overly restrictive regulations in an already difficult economic environment, whereas urban utilities prioritize delivering clean drinking water to their ratepayers.

The agriculture sector often gets cast as a villain and may feel that it must defend itself against other water practitioners who aren’t familiar with the hardships of farm operations, Peterson said. Making clear to farmers the mutual benefits of a One Water approach could improve collaboration. For instance, many sustainable agriculture practices both benefit farm finances and improve downstream water quality.

McMahon recommended that delegation leaders reach out to agriculture associations to find champions of improving water quality and water use efficiency. “If you’re framing your proposal like, ‘Come help us talk about these complicated issues from your perspective,’ it’s like a wide-open door to have really powerful conversations,” said Jones.

“The water is the bridge.”

Clare Lindahl, chief executive officer of the Soil and Water Conservation Society, a member of the Soil and Water Conservation delegation, and a board member of the US Water Alliance, said her delegation has had success building relationships across the urban and rural divide by emphasizing the value of water to all stakeholders. “The water is the bridge,” she said.

When a highly diverse group of stakeholders makes it to the summit, collaboration can lead to what Figueroa called a “healthy push and pull”: Everyone sitting around the table may have different expectations, goals, and work practices. Delegations have found that defining common goals and outlining clear responsibilities are the best way around that.

For example, the New Jersey group has centered its conversations around four shared goals: having effective and financially sustainable water systems; empowering stakeholders and ensuring that they are well-informed; building successful, beneficial green infrastructure; and creating smart combined sewer overflow control systems.

“That’s our North Star, and that has helped us,” Figueroa said.

“It’s hard to break down silos if your objectives aren’t clear,” Peterson said. Being “really candid and clear about who’s involved, what the roles are, and what the responsibilities are for the beginning, middle, and end of the project” can help, she said.

Berry said he has high hopes for the future of delegations. He imagines an eventual Colorado River delegation that would include stakeholders from throughout the Colorado River Basin. Other dreams include a Great Lakes delegation and a Mississippi River delegation. “There’s so much ground to cover,” he said.

“It’s both a resources and money question, and it’s a relationship question,” Berry said.

—Grace van Deelen (@GVD__), Staff Writer

Citation: van Deelen, G. (2025), Delegations drive One Water dialogues, Eos, 106, https://doi.org/10.1029/2025EO250155. Published on 24 April 2025. Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Editors’ Highlights are summaries of recent papers by AGU’s journal editors. Source: AGU Advances

The massive 2022 eruption of the Hunga Tonga-Hunga Ha‘apai volcano was one of the most powerful explosions ever recorded. It blasted ash and gas high into the sky, reaching heights over 50 kilometers (above most clouds and weather), and sent waves rippling through Earth’s atmosphere. These waves traveled all the way to the upper atmosphere—the netherworld where satellites orbit—causing unexpected disruptions in this region.

Using data from satellites and computer models, Li et al. [2025] investigate why these waves spread so far. They focus on two possible causes: Lamb waves (pressure waves that “hug” Earth’s surface) and secondary gravity waves (new waves created when initial eruption waves break apart higher up). The authors find that secondary gravity waves, with their faster speeds and larger magnitudes, matched the satellite observations best. This means they were the key driver of the upper atmosphere’s dramatic changes.

These findings matter because they reveal how geological events on Earth’s surface, like volcanoes, can “talk” to the edge of space. Understanding this link helps improve satellite safety and weather predictions in space, which is critical as humans rely more on satellites for communication, navigation, and climate monitoring.

The numerical simulations reveal that secondary gravity waves could be responsible for the large scale thermospheric disturbances captured by GRACE-FO satellite associated with the extraordinary eruption of the Tonga volcano on 15 January 2022. Credit: Li et al. [2025], Supporting Information Movie S1

Citation: Li, R., Lei, J., Zhang, S.-R., Liu, F., Chen, X., Luan, X., & Meng, X. (2025). Were gravity waves or lamb waves responsible for the large-scale thermospheric response to the Tonga eruption? AGU Advances, 6, e2024AV001470. https://doi.org/10.1029/2024AV001470

— Binzheng Zhang, Editor, AGU Advances

Text © 2024. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

SummaryFault Zone Head Waves (FZHW) are a key diagnostic tool to identify bimaterial interfaces along fault zones. We detect and analyze FZHW recorded in the waveforms from the local MONGAN (MONitoring of the GANos Fault) seismic network along the Ganos section of the North Anatolian Fault Zone, northwestern Türkiye, between October 2017 and July 2019. MONGAN covers the Ganos fault with different inter-station distances ranging from 25 m to ∼4 km. To detect FZHW, an automatic detector is used as a preliminary analysis method followed by manual revision and particle-motion analyses to distinguish between FZHW and direct P waves. FZHWs are predominantly detected at the southern side of the fault. The observed FZHWs have a moveout (∆t) with respect to the direct P arrivals, increasing with distance traveled along the fault and indicating a deep bimaterial interface down to the bottom of the seismogenic crust. The average velocity contrast is estimated to be 5.9% across the fault. Near fault-recordings indicate that the Ganos Fault is offset by ∼250 m with respect to the surface trace obtained from literature. To a lesser extent, FZHW are also observed in the northern stations from the fault, indicating a shallow wedge-shaped low-velocity portion constituted by highly fractured material to either side along the southwestern section of the Ganos Fault between the fast Eocene block to the north and the slow Miocene block to the south. The seismic velocity contrast and geological complexity have important implications for the rupture evolution during future earthquakes on the Ganos fault in that they would progress predominantly westward, away from Istanbul and Tekirdağ. Furthermore, an asymmetric aftershock distribution skewed to the northern block can be expected, with subsequent implications for site-dependent risk there. Our results allow to revise focal mechanism solutions by separating FZHW from direct-P wave for previous Sea of Marmara earthquakes.

SummaryBorehole breakout (BO) has increasingly been utilised to estimate in-situ stress magnitudes given the importance of the stress field in subsurface activities and the limitations of conventional stress measurement techniques. In this study, a new backpropagation neural network model is developed to estimate both maximum and minimum horizontal stress magnitudes from multi-scale BO data. A total of 150 experimental data points from pre-stressed true-triaxial laboratory tests and 44 field data from a mine site in Australia and the literature are collected and employed for model development and validation. Compared to previous studies, the collected dataset is significantly enhanced in both quantity and quality. To address discrepancies in stress magnitudes between experimental and field data, the three principal stresses are normalised by borehole wall strength (BWS). Overall, the model achieves mean absolute percentage errors of below 8% for the maximum horizontal stress and below 20% for the minimum horizontal stress, significantly outperforming the previous model developed for this purpose. Furthermore, these error rates fall within the typical error range (10-20%) of conventional stress measurement techniques, indicating the model's sufficient accuracy for practical applications. Moreover, the effectiveness and generalisability of the model are verified using 166 additional BOs from two mine sites, which are independent of those used in model development. Continuous and detailed stress profiles are established based on these BOs, covering greater depth intervals than the stress measurements from the overcoring method. The results of this study demonstrate that the proposed model can provide reliable and accurate stress estimation, utilising input parameters that can be readily obtained from borehole geophysical logs.

SummaryThe behavior of uniaxial single domain magnetite particles in rock and paleomagnetic experiments was first described in the 1940s by Néel and Stoner and Wohlfarth. Since this time, micromagnetism has allowed us to gain a better understanding of magnetic particles in the single vortex or multi-domain states. By contrast, when describing the behavior of assemblages of single domain particles, simplifying assumptions made in the 1940s are still used today. In particular, most rock and paleomagnetic simulations involve magnetite with a uniaxial anisotropy. These assumptions are not necessary in the modern day, as data on other magnetic minerals has been collected, and modern computers are powerful enough to easily calculate the behavior of multiaxial particles. We present a new software package called the Single Domain Comprehensive Calculator (SDCC). This package can simulate a large number of thermally activated rock and paleomagnetic experiments with distributions of single domain particles. These include acquisition of viscous remanence, thermal demagnetization experiments, hysteresis loops, and paleointensity protocols. The package provides a simple Python scripting interface for users to define custom experiments and run models on a laptop computer. Preliminary simulations run with the SDCC demonstrate that magnetocrystalline anisotropy can have a significant effect on the thermoviscous behavior of single domain particles, despite normally being ignored in models. This highlights a need for further investigation into the behavior of single domain particles.

SummaryIn this study, a modified two-dimensional gravimetric inversion algorithm is presented that is based on the reversible-jump Markov chain Monte Carlo (RJMCMC) method with the Talwani equation. To ensure the validity of the Talwani equation and accurate gravity anomaly calculations, the Shamos-Hoey algorithm is incorporated as an additional acceptance condition to prevent intersections in the model polygon. This improves upon the method proposed by Luo by iteratively refining a polygon model based on gravity anomalies while maintaining physical validity. Additionally, we suggest a revision of the prior density function to better test the proposal models. This method estimates the shape and location of subsurface intrusions, providing valuable insights into subsurface geological structures. This positions the algorithm as a valuable tool for geophysical research.

SummaryNear-field large-amplitude seismograms are essential for the rapid inversion of earthquake source parameters using waveform inversion methods such as the Cut And Paste (CAP) method for disaster assessment. High-rate Global Navigation Satellite System (GNSS) relative positioning (RP) provides precise, rapid, and real-time measurement of near-field large-amplitude displacements. However, RP records motion with respect to a reference station, and the reference station's movements become part of the relative displacement waveforms. Therefore, seismic source parameter estimates may be inaccurate if the reference station's motion is not taken into consideration, and doing so affects some basic assumptions made in the CAP method. To overcome this problem, we develop an expanded differential CAP inversion approach specifically for high-rate GNSS RP (CAP-RP) that accounts for the motion of the reference station. Two methods are proposed to implement CAP-RP: an expanded differential CAP (D-CAP) and an iterative post-processing CAP (P-CAP). We assess the performance of CAP-RP with different datasets, using the July 2019 Mw 6.4 earthquake in California as a case study. Both CAP-RP techniques produce accurate source parameters in synthetic data inversion tests, indicating the feasibility of the strategy. However, P-CAP is more time-efficient than D-CAP, making it the better option. Generally, results from high-rate GNSS RP, broadband seismographs, and their inverted combinations exhibit consistency in observational data inversion testing. Our results also demonstrate that more accurate source parameters can be obtained by combining sensitive far-field broadband seismograph data with large amplitude near-field GNSS RP waveforms.

SummarySpectral induced polarization (SIP) has been suggested as a non-invasive and cost-effective tool to detect and monitor aromatic rich organic matter such as biochar. In our study, we show that SIP can track biochar concentration up to 10% (wt.) in a soil with a clay content of 20%. Assessment of changes in the concentration of biochar was conducted according to double Pelton parameters and the maximal phase determined at 11.7 Hz, a frequency at which a polarization peak is observed in the presence of biochar. All SIP-derived parameters were correlated with the biochar content, with the exception of the relaxation time of the polarization peak occurring at 11.7 Hz, which was related to soil water saturation in previous investigations. Among studied parameters, the phase value that we measured at 11.7 Hz may therefore consist in a simple and reliable methodology to evaluate the biochar content on SIP in our experiment. Several steps are still necessary before a widespread field application notably by considering how modifications in the chemistry of biochar with time can interact with biochar concentration and water saturation to modify polarization processes shaping SIP curves. Beyond the scope of tracking changes in the content of highly aromatic OM – such as biochar - in soils, this study suggests that the degree of aromaticity of OM can play a key role in the SIP response paving the way for wider use of SIP in soil science.

The East Asian summer monsoon (EASM) plays a crucial role in shaping the regional climate and ecosystem. It is a key driver of seasonal precipitation patterns that sustain agricultural productivity and water resources in East Asia. Additionally, the EASM facilitates heat and moisture transport, modulating the regional energy balance and influencing large-scale atmospheric circulation.

Chinese scientists have discovered that fragile swamp forests in the Pearl River Delta (PRD) region suddenly collapsed approximately 2,100 years ago (2.1 ka)—with human activity as the cause.

Publication date: Available online 15 April 2025

Source: Advances in Space Research

Author(s): Peichen Wang, Xunliang Yan, Wenjiang Nan, Xinguo Li

Publication date: Available online 15 April 2025

Source: Advances in Space Research

Author(s): Kadierye Maolan, Yusufujiang Rusuli, WuHaiZhi, Yimuran Kuluwan

Rising temperatures could tip the scale in an underground battle that has raged for millennia. In the soils of Earth's wetlands, microbes are fighting to both produce and consume the powerful greenhouse gas methane. But if Earth gets too hot, a key way wetlands clamp down on methane could be at risk, according to a Smithsonian study published in Science Advances.

Over the past two decades, satellite-based planetary observations have recorded rapid mass loss of Patagonian glaciers, contributing approximately 0.07 mm per year to global sea-level rise. A study published in Nature Communications links this mass loss to a poleward shift of subtropical high-pressure systems. This large-scale atmospheric circulation change brings more warm air to Patagonia, thereby accelerating glacier melt.

South Africa is slowly lifting out of the water—by up to 2 millimeters per year depending on the region. It had been assumed up to now that this phenomenon was due to mantle flow in Earth's crust. However, a study carried out by the University of Bonn now provides another explanation: Droughts and the associated water loss are the main reason for this land uplift. The results have now been published in the Journal of Geophysical Research: Solid Earth.

Multiple climate "tipping points" are likely to be triggered if global policies stay on their current course, new research shows. Scientists assessed the risk of "tipping" in 16 different parts of the Earth system—ranging from the collapse of major ice sheets to the dieback of tropical coral reefs and vast forests.

Around 10,000 years ago, as the last Ice Age drew to a close, the drifting of the continent of North America, and spreading in the Atlantic Ocean, may have temporarily sped up—with a little help from melting glaciers, according to a new study from scientists at the University of Colorado Boulder.

Drought-fueled wildfires in Southern California, a devastating hurricane in the southern Appalachian Mountains, and catastrophic floods in New England are among the most recent disasters to bring the increasingly astronomical costs of climate change into focus.

Earth’s oceans are full of plastic. Though the state-sized garbage patches formed by ocean currents are the most visible, just an estimated 1% of ocean plastic lurks on the surface. The other 99% hides elsewhere in the ocean and may be found in the deep sea, mixed in with seafloor sediment. These particles are often in the form of microplastics: fragments of plastic goods degraded to less than 1 millimeter in length.

Scientists know these deep-sea plastics don’t get there by simply sinking from the surface since their distribution doesn’t match the locations of surface garbage patches. Results of laboratory experiments and seafloor sampling campaigns led scientists to suspect these plastic particles instead reach the deep ocean via turbidity currents, gravity-driven cascades of sediment-rich water that flows from rivers over the continental shelf and down to the seafloor. But no one had observed the process until now.

A new study published in Environmental Science and Technology presents the first direct evidence of an underwater microplastics “avalanche,” a turbidity current that transported plastic pollution to the bottom of a deep ocean canyon. The findings raise concerns about how microplastics may be affecting marine organisms because the same turbidity currents foster biodiversity hot spots in the same locations.

“The fact that we captured this in action proves the theory, but it also highlights the threats that microplastics pose.”

“Turbidity currents are an important process that transports sediments and nutrients to the deep sea. The question was: Do they also transport plastics?” said Florian Pohl, a sedimentologist at the University of Bayreuth in Germany who was not involved in the research. Pohl was the lead author on a 2020 study that predicted the existence of these microplastics “avalanches” using laboratory experiments.

“The fact that we captured this in action proves the theory, but it also highlights the threats that microplastics pose,” said Ian Kane, a coauthor of the new study and a sedimentologist at the University of Manchester. “This study is further evidence of the impact that we’re having on the oceans.”

Measuring Microplastics

To observe turbidity currents in action, the research team headed to Whittard Canyon, an undersea canyon in the Celtic Sea nearly 4 kilometers (2.5 miles) deep. They installed sensors in the canyon that could measure turbidity current velocity and detect sediment concentration.

The team also installed a sediment trap just above the seafloor to collect material transported by the turbidity current and drilled cores of seafloor and subseafloor sediment at seven sites at varying depths in the canyon.

Between June 2019 and August 2020, the sensors detected six turbidity currents, the first of which filled the sediment trap. An analysis of flow velocity and sediment grain size showed that the turbidity flow even carried large plastic litter, including segments of plastic fishing line. All sediment trap samples and seafloor sediment cores contained microplastic particles.

The sediment trap, which collected sediment from the first observed turbidity flow, yielded 82 microplastic items per 50 grams of dried sediment. Credit: Peng Chen

Samples of sediment from the cores revealed that the relative proportion of microplastic fragments (tiny plastic “chunks”) to microplastic fibers (from synthetic textiles) increased deeper into the canyon, indicating that fragments and fibers travel differently in turbidity currents. Pohl said he’d like to take a closer look at the fragment and fiber properties (such as the type of plastic they’re made of) to determine why.

Kane was struck by the high concentrations of microplastics found in the sediment, especially because Whittard Canyon is so far from shore—300 kilometers (186 miles). “It’s quite alarming that this material is making its way so far out into ocean basins,” he said.

The microplastics “avalanches” observed in Whittard Canyon likely also happen elsewhere in Earth’s oceans. More than 5,000 similar canyons worldwide could be important conveyors of pollution to the deep sea, the authors wrote. Some of these canyons are fed directly by rivers on land. Seasonal flash floods in Sicily, for instance, have carried large amounts of plastic litter to submarine canyons.

If Whittard Canyon is receiving a lot of plastic, it’s likely that other canyons, especially those more closely linked to rivers on land, are receiving even more, Kane said.

Plastic in the Ecosystem

The new study is a “great first step” in understanding how microplastics reach the deep ocean, Pohl said. “It’s a big piece of the puzzle to understand that these flows do indeed transport microplastics. But now there are follow-up questions, like how much [plastic] do they actually transport? And how does this relate to the overall budget of ocean floor plastics?”

The same turbidity currents that flush microplastics also bring oxygen and nutrients to the deep sea, forming biodiversity hot spots in the same locations where plastic pollution accumulates. That plastic pollution often contains toxic ingredients that are hazardous to marine organisms.

“Magnification through the trophic web is a real danger.”

Filter feeders ingest toxic plastic particles, which accumulate up the marine food chain. “Magnification through the [food] web is a real danger,” Kane said.

Much of the plastic in the ocean enters via waste management systems. Better filtration at wastewater treatment plants could be one important way to reduce the flow of microplastic fibers into the ocean, Kane said, adding that fishing and shipping are also major sources of microplastics to target for mitigation. But microplastic pollution is ubiquitous in the environment, and reducing its presence in the ocean is “a big challenge,” Pohl said.

—Grace van Deelen (@gvd.bsky.social), Staff Writer

Citation: van Deelen, G. (2025), Avalanches of microplastics carry pollution into the deep sea, Eos, 106, https://doi.org/10.1029/2025EO250153. Published on 23 April 2025. Text © 2025. AGU. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Editors’ Highlights are summaries of recent papers by AGU’s journal editors. Source: Geophysical Research Letters Sampling red snow on the Tasman Glacier in the Southern Alps following the 2019-2020 Australian bushfire/dust storm (Photo: J. Hunt 11/02/2020). Credit: Winton et al. [2024], Figure 1d

New research reveals the source of the red dust that blanketed the New Zealand Southern Alps in the summer of 2019-2020 following the severe Australian bushfires. While much attention was paid to ash from the extreme 2019-2020 Australian fires, a surprising discovery is that transport of dust generated from dust storms was also a major contributor to the composition of the atmosphere at the time.

Winton et al. [2024] analyze snow samples from the Fox, Franz Josef, and Tasman glaciers and geochemically fingerprint its origin as southeast Australia where desert dust storms transported massive amounts of red dust across the Tasman Sea. These dust storms were fueled by the same high winds that also drove the bushfires and transported an estimated 4,500 tons of red mineral dust to the snow and ice in the Southern Alps. While the dust storm event lasted only a short time, it could have long-term effects on glacier melting.

Citation: Winton, V. H. L., Charlier, B. L. A., Jolly, B. H., Purdie, H., Anderson, B., Hunt, J. E., et al. (2024). New Zealand Southern Alps blanketed by red Australian dust during 2019/2020 severe bushfire and dust event. Geophysical Research Letters, 51, e2024GL112782. https://doi.org/10.1029/2024GL112782  

—Bin Zhao, Associate Editor, Geophysical Research Letters

Text © 2024. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.