15 Jun 2026

Environmental Fate of Monosodium Methanearsonate (MSMA)—Part 1: Conceptual Model

Abstract: Monosodium methanearsonate (MSMA), the sodium salt of monomethylarsonic acid (MMA), is used as a selective, broad‐spectrum contact herbicide to control weeds in cotton and a variety of turf. In water, MSMA dissociates into ions of sodium (Na+) and of MMA−, which is the herbicide's active component. Certain soil microorganisms can methylate MMA to dimethylarsinic acid (DMA) other microorganisms can demethylate MMA to inorganic arsenic (iAs). To predict the groundwater concentration of iAs that may result from MSMA application, the processes affecting the environmental behavior of MSMA must be quantified and modeled. There is an extensive body of literature regarding the environmental behavior of MSMA. There is a consensus among scientists that the fate of MMA in soil is controlled by microbial activity and sorption to solid surfaces and that iAs sorption is even more extensive than that of MMA. The sorption and transformation of MMA and its metabolites are affected by several factors including aeration condition, temperature, pH, and the availability of nutrients. The precise nature and extent of each of these processes vary depending on site‐specific conditions; however, such variability is constrained in typical MSMA use areas that are highly managed. Monomethylarsonic acid is strongly sorbed on mineral surfaces and becomes sequestered into the soil matrix. Over time, a greater portion of MMA and iAs becomes immobile and unavailable to soil microorganisms and to leaching. This review synthesizes the results of studies that are relevant for the behavior of MSMA used as a herbicide to reliably predict the fate of MSMA in its use conditions.

15 Jun 2026

Natural vs. Genetically Engineered Microbiomes: Understanding Public Attitudes for Indoor Applications and Pathways for Future Engagement

Abstract: This study examines public preferences for natural microbiomes and support for genetically engineered (GE) microbiomes in the built environment, focusing on the demographic, sociographic, and attitudinal factors that influence these preferences. Using data from a nationally representative survey of 1,000 U.S. adults, we employed hierarchical regression analyses to assess the relative contribution of these variables. While demographic and sociographic factors explained limited variance, topic-specific attitudes, including positive perceptions of microbiome engineering’s potential to improve quality of life, were the most significant predictors of support. Conversely, age, distrust in science, and perceived knowledge negatively influenced support for GE microbiomes, reflecting skepticism among some audiences. The findings highlight the potential of the Responsible Research and Innovation (RRI) framework to align the development of microbiome engineering with societal values and to address diverse public perspectives. This research provides actionable insights for policymakers, researchers, and communicators seeking to navigate the complexities of public engagement with emerging biotechnologies.

12 Jun 2026

Automated Snow Cover Detection on Mountain Glaciers Using Spaceborne Imagery and Machine Learning

Abstract: Tracking the extent of seasonal snow on glaciers over time is critical for assessing glacier vulnerability and the response of glacierized watersheds to climate change. We present an automated snow detection workflow for mountain glaciers using supervised machine-learning-based image classifiers and Landsat 8 and 9, Sentinel-2, and PlanetScope satellite imagery. We develop the image classifiers by testing numerous machine learning algorithms with training and validation data. The workflow produces daily to twice monthly time series of several glacier mass balance and snowmelt indicators from 2013 to present. Workflow performance is assessed by comparing automatically classified images and snow lines to manual interpretations at each glacier site. The image classifiers exhibit over-all accuracies of 92 %–98 %, κ scores of 84 %–96 %, and F scores of 93 %–98 % for all image products. The median difference between automatically and manually delineated median snow line altitudes is −31 m across all image products. The Sentinel-2 classifier produces the most accurate glacier mass balance and snowmelt indicators and distinguishes snow from ice and firn the most reliably. Although they are less accurate, the Landsat- and PlanetScope-derived estimates greatly enhance the temporal coverage of observations. The transient accumulation area ratio produces the least noisy time series, making it the most reliable indicator for characterizing seasonal snow trends. The temporally detailed accumulation area ratio time series reveal the timing of minimum snow cover conditions varies by up to a month between Arctic and midlatitude sites, underscoring the potential for bias when estimating glacier minimum snow cover conditions from a single late-summer image. Widespread application of our automated snow detection workflow has the potential to improve regional assessments of glacier mass balance, land ice representations within Earth system models, water resources, and the impacts of climate change on snow cover across broad spatial scales.

12 Jun 2026

Spatiotemporal Patterns of Accumulation and Surface Roughness in Interior Greenland with a GNSS-IR Network

Abstract: The dry-snow zone is the largest region of the Greenland Ice Sheet, yet temporally and spatially dense observations of surface accumulation and surface roughness in this area are lacking. We use the global navigation satellite system interferometric reflectometry (GNSS-IR) technique with a novel, low-cost GNSS network of 12 stations in the vicinity of the ice sheet summit to reveal temporal and spatial patterns of accumulation of the upper snow layer. We show that individual measurements are highly precise, while the aggregate of hundreds of daily measurements across a large spatial footprint can detect millimeter-level surface changes and is biased by −2.7 ± 3.0 cm com-pared to a unique validation data set that covers a similar spatial extent to the instrument sensing footprint. Using the validation data set, we find that the reflectometry technique is most sensitive to the surrounding 4–20 m of the surface, with the GNSS antenna at a height of 1–2 m above ground level. Along with an exceptionally high accumulation rate at the beginning of the study, we also detect an across-slope dependence in accumulation rates at yearly timescales. For the first time, we also validate GNSS-IR sensitivity to meter-scale surface heterogeneities such as sastrugi, and we construct a time series of surface roughness evolution that suggests a seasonal pattern of heightened wintertime roughness features in this region. These surface accumulation and rough-ness measurements provide a novel data set for these critical variables and show a statistically significant relationship with occurrences of both high winds and precipitation events but only moderate correlations, suggesting that other processes may also contribute to accumulation and enhanced surface roughness in the interior region of Greenland.

12 Jun 2026

EcoHydraulic Modeling to Inform Sustainable Sediment Management: A Priori Modeling of Reservoir Sediment Release to Estimate Geomorphic and Ecological Response

Abstract: With decreasing storage capacity and increasing operational costs in reservoir management, sediment release is considered a potential alternative to traditional dredging. However, passing sediment through reservoirs may have unexpected effects on downstream river morphology and ecosystem resources. This study uses numerical modeling and a conceptual ecological model to assess the relative effects of sediment load, stream flow magnitude, and grain size distribution in downstream river morphology and aquatic habitat in a case study system of the Big Blue and Kansas Rivers downstream of Tuttle Creek Reservoir, Manhattan, Kansas. The effects of sediment grain size, clearwater flushing rate, and backwater effects from the Kansas River were all found to be relevant in affecting sediment transport and deposition patterns. High-volume water/sediment releases were found to be most effective at emulating historical conditions. Additionally, sediment release was found to increase desirable physical habitat areas that have been lost in the channel. Clearwater flushing further increased the distribution of sediment to support physical habitat creation. These findings can inform sediment release management decisions regarding the timing, duration, and magnitude of sediment releases, particularly in relation to flows at the downstream confluence and for target ecosystem function goals.

12 Jun 2026

Adsorption of the Microbial Exopolysaccharide from Rhizobium Tropici (ATCC 49,672) on Birnessite Facilitates Mn Reduction and Dissolution: Structural Interactions and Morphological Transformation

Abstract: The study addresses the broader question of how microbial exopolysaccharides (EPS) can modulate the reactivity and stability of manganese (Mn) oxides in environmental systems. The objective of this study is to investigate the adsorption process of EPS from Rhizobium tropici on birnessite (MnO2) and mechanisms of induced Mn reduction and dissolution and its further transformation. EPS adsorption isotherms and kinetics on birnessite and the induced dissolution of birnessite were analyzed. Adsorption kinetics could best be described with the Parabolic Diffusion Model while EPS adsorption isotherm was best fitted with the Freundlich model. Adsorbed EPS facilitated Mn reduction and dissolution, releasing Mn²⁺ into the solution. This was also confirmed by fourier transform infrared spectroscopy (FTIR) results with the Mn-O vibrations, O–H groups and C = O carbonyl stretching. The pre-presence of EPS hindered the formation and growth of crystalline structure of birnessite and further hindered its transformation into more stable β-MnO2. The presence of Mn oxide significantly aggregated EPS, forming large aggregates. This study reveals the importance of EPS in influencing both the adsorption behavior and the redox state of Mn, providing significant insights into the interactions of EPS with birnessite in environmental systems.

11 Jun 2026

Simulation of Dredged Material Placement in the San Francisco Bay Using a Multi-Dimensional Hydrodynamics and Sediment Transport Model

Abstract: The US Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory, has developed an Adaptive Hydraulics (AdH) 2D, hydrodynamic and sediment transport model for San Francisco Bay. This model supports the US Army Corps of Engineers, San Francisco District, in informing navigation and sediment management decisions as part of the Regional Dredged Material Management Plan (RDMMP), which evaluates dredging methods and placement alternatives over a 20-year planning horizon. There is a need to assess the long-term fate of dredged material placed at in-bay sites to better understand associated benefits and potential impacts. This report documents the development, calibration, and validation of the AdH 2D model for conditions in 2022. The model was applied to simulate the multimonth dispersion and transport of dredged material from four sites. Model results demonstrate that sediment transport patterns are influenced by seasonal hydrodynamic forcing and grain-size composition, with coarser material forming stable deposits that persist over time. The findings of this study inform sediment management strategies under the San Francisco Bay RDMMP and support efforts to reduce navigation risks and enhance beneficial use opportunities. The study recommends field data collection to improve sediment characterization at placement sites and strengthen predictive modeling and planning efforts.

11 Jun 2026

Proceedings from the Great Lakes Engineering With Nature® Natural and Nature-Based Features Playbook Workshop

Abstract: Communities in the Great Lakes are experiencing increased frequency in coastal flooding and erosion, causing property damage, putting lives at risk, and disrupting local economies. To address these challenges, two workshops were conducted (18 February 2025 [virtual] and 26–27 February 2025 [in person]) to collect knowledge, insights, and feedback from community members, policymakers, and Tribal Nations representatives to inform the development of the Engineering With Nature® Great Lakes Playbook. This report documents the workshop outcomes. The playbook is being designed to advance coastal resilience efforts in the region by identifying natural and nature-based features and multiple lines of resilience strategies that address unique natural hazard-related challenges of the Great Lakes. During the workshops, sustainable, resilient, adaptable, and cost-effective solutions were explored and construction and implementation feasibility were discussed along with regulatory and community challenges that are applicable to coastal risks and opportunities around the Great Lakes. By providing location-appropriate examples and clear guidance on how these nature-based and engineered solutions can be implemented, the playbook will enhance understanding of their potential performance in the region and build confidence among federal, state, and local agencies and Tribal Nations in planning, designing, and implementing these sustainable, adaptable, and cost-effective solutions.

11 Jun 2026

Geofencing for Standardized Navigation Lock Cycle Time Analysis

Abstract: The purpose of this US Army Engineer Research and Development Center (ERDC) technical note (TN) is to describe the motivation for, and development of, a set of geospatial boundaries (geofences) at standard intervals around navigation lock structures owned or operated by the US Army Corps of Engineers (USACE). These geofences will be used for automated time-stamp generation in conjunction with Automatic Identification System (AIS) broadcasts from vessels.

11 Jun 2026

The Bird Islands Ecosystem Design Using Boussinesq Modeling—Barren Island, Mid-Chesapeake Bay

Purpose: The US Army Corps of Engineers (USACE) Baltimore District is currently engaged in an ecosystem restoration within the Chesapeake Bay, Maryland. Specifically, two islands, Barren Island and James Island, are to undergo restoration using dredged materials and creation of berms and breakwaters to offer a level of protection to the island from wave and surge during storm events. This report focuses on the design of bird habitat development on the Tarbay side of the detached breakwaters in the Barren Island design. During the ongoing Preconstruction, Engineering, and Design (PED) phase of the project, it was determined that terraced islands would be created on the leeside of the detached breakwater system for bird habitat development. Coastal storm inundation and wave loading from Coastal Storm Modeling System (CSTORM-MS) coupled surge and wave modeling system were quantified in a previous effort. These results are used as input to local high-fidelity phase-resolved wave modeling to quantify the hydrodynamics on the island. The terraced structure will include berms. Berm and breakwater stone stability was quantified using Ahrens (1989) reef equations. This report discusses potential erosion and additional structure configurations. Additional offshore reef-type breakwaters were considered to protect the bird islands from waves propagating from the east to the west toward the Tarbay side of the island.