Green River Research Articles

Juvenile Pacific salmonid habitat use in two Puget Sound lowland rivers

AbstractObjectiveLarge rivers are complex, productive environments that support numerous species. However, humans have extensively modified these ecosystems, contributing to the decline of Pacific salmonid Oncorhynchus spp. populations. Salmon recovery efforts rely upon an understanding of salmonid habitat needs at different life stages, but data on juvenile salmonid habitat use within large rivers are rare due to the challenges of sampling in large rivers. To help fill this information need, we used a cataraft‐mounted electrofisher to evaluate juvenile salmonid use of natural (bar, backwater, side channel, and unarmored bank) and human‐modified (riprap‐armored bank and biorevetment bank [armored banks with added wood]) channel edge habitats in the Snoqualmie and Green rivers within the Puget Sound region of Washington State.MethodsWe electrofished over 1000 25‐m transects across seven spring rearing seasons (2016–2022) and measured transect water depths and widths of low‐velocity habitat (≤0.45 m/s).ResultBars, backwaters, and side channels were shallower and had wider low‐velocity habitat than armored banks. River flow also influenced water depth and low‐velocity width, but the relationship varied depending on the habitat type. Subyearling Chinook Salmon O. tshawytscha and subyearling Coho Salmon O. kisutch occurred more frequently and were more abundant along natural edge habitats than along armored banks, while their use of biorevetment banks was intermediate between their use of natural edge habitats and armored banks. In contrast, yearling Coho Salmon and trout occurred more frequently and were more abundant along armored, biorevetment, and unarmored banks than along bars and backwaters, but they also used side channels extensively. Habitat use shifted throughout the spring, but specific shifts varied by species or life history stage.ConclusionThese results emphasize the importance of conserving natural edge habitats, removing bank armoring, and reconnecting or restoring side channels. Additionally, our results highlight that a diversity of habitat types and conditions is necessary to support multiple species and life history stages.

A volatile sulfur sink aids in reconciling the sulfur isotope mass balance of closed basin lakes

Sedimentary rocks from the early Eocene Green River Formation comprise the largest known lacustrine oil shale deposits, contain remarkably well-preserved fossils, and provide a unique record of climate evolution across the Early Eocene Climate Optimum, a period of high atmospheric CO2. The depositional environment of these intermountain lakes spanned from relatively fresh and fluvially influenced to expanded and stratified saline closed basin lakes under the influence of the Laramide orogeny and alternating humid and arid climatic conditions. As the surface area of the lakes expanded, alkalinity and salinity increased, with depositional cycles that linked to evaporative cycles and marked by an increasing abundance of organic matter-rich shales (TOC > 10 wt%). Simultaneously, an intriguing 20 ‰ positive shift in the sulfur isotope composition of sulfide minerals and organic sulfur is observed. Given that this trend cannot be simply explained by a change in the source of sulfate delivered to the basin, the evolution of biogeochemical sulfur cycling and the balance of fluxes in response to basin evolution remain unresolved. Here, we combine the sulfur isotope compositions of pyrite, organic sulfur, and carbonate-associated sulfate and molecular proxies of euxinia in samples from the Uinta basin's depocenter. We find that organic matter-rich sediments reflect deposition in a stratified water column with enhanced burial of pyrite and sulfurized organic matter, while organic-lean facies present evidence of, at least transiently, euxinic conditions reaching the photic zone during arid conditions presumably because of evaporation. As the lake became both saline-stratified and euxinic, we observe that δ34S values of all measured sulfur-bearing sedimentary proxies increase and evolve along a 1:1 line, a trend independent of facies that we interpret as reflecting a sulfate-limited system despite saline conditions. The isotopic mass balance of sulfur fluxes implies the existence of a sink of sulfur depleted in 34S that is spatially decoupled from burial in the depocenter. Modeling sulfur biogeochemical processes in a saline stratified lake system allows us to estimate that at least 50 % of the sulfur entering the lake could have been lost from the upper part of the euxinic water column where the fractionation factor imparted by microbial sulfate reduction is expressed. We propose that the overall isotopic enrichment of the system was caused by H2S degassing during arid climate intervals, presumably enhanced by transient water column mixing events. Further, episodic intrusion of euxinic bottom waters into the upper part of the water column might have triggered mass fish and plankton mortality, consequently facilitating the formation of these exceptionally fossiliferous and organic matter-rich rocks. Our study finds that volatile outgassing may be an underappreciated mechanism for the sulfur mass balance of stratified lacustrine systems.

Ecological network resilience evaluation and ecological strategic space identification based on complex network theory: A case study of Nanjing city

Constructing a resilient ecological network (EN) and identifying critical strategic nodes and corridors within the EN, stands as a pivotal approach toward achieving a harmonious equilibrium between regional development and ecological conservation. It is imperative to expand the perspective to encompass the holistic resilience of the EN, thus identifying and safeguarding ecologically strategic nodes and corridors that play pivotal roles throughout the entire network. Therefore, this study takes Nanjing City as a case study and establishes a comprehensive EN resilience assessment framework based on resilience theory and complex network theory, grounded in a foundation of multidimensional indicators. Building upon this, the research develops the ‘regional network simulation - ecological spatial analysis - strategic spatial identification’ investigative framework. The results show that a core EN structure centered around green spaces, rivers, lakes, and similar features has taken shape, encompassing a total of 39 ecological nodes and 69 ecological corridors. Examining from six perspectives, connectivity, integration, complexity, centrality, efficiency, and substitutability, and their integrated assessment, this study analyzed the impact of single and sequential failures in different EN component spaces on the overall resilience of the EN. The study aimed to identify the component space that significantly contributes to the network's resilience. As a result, the strategic space of the EN was divided into three levels. The ecological source areas 1, 2, 7, and 34, along with ecological corridors 1–34, 1–4, 4–11, 19–34, 18–19, and 27–39, emerge as the primary strategic spaces within the study region. Previous research primarily emphasized the individual characteristics of ecological spaces. However, this study adopts a systemic perspective rooted in resilience theory and complex network theory to meticulously explore the pivotal impact of specific ecological spaces on the overall resilience of the ecological system network. Moreover, it amalgamates considerations of both the significance and scale of ecological spaces, conducting a comprehensive assessment of their combined influence on the overall EN resilience. This approach not only aids in identifying and preserving strategic ecological nodes and corridors but also contributes to evaluating, planning, and restoring regional EN resilience. This progression plays a crucial role in establishing an equilibrium between regional advancement and ecological conservation.

SMART ENVIRONMENT: ANALYSIS OF WATER MANAGEMENT POLICY IN MAKASSAR


 
 
 
 Abstract
 This article aims to analyze the Makassar government's policies on clean water management in Makassar, one of Indonesia's major cities. Utilizing the concept of a smart environment as an analytical framework, this study investigates whether Makassar's clean water management aligns with the principles of a smart environment. The escalating construction of apartments and hotels has notable consequences for water resources in Makassar. Simultaneously, the city experiences rapid population growth each year, indirectly affecting clean water consumption. This qualitative study employs descriptive analysis, aiming to elucidate and depict the current events concerning the research object. Secondary data forms the basis of this study. Research findings indicate that Makassar's clean water management does not conform to the smart environment concept. This discrepancy can be attributed to inconsistent clean water distribution aggravated by the city's swiftly growing population. Furthermore, the implementation of smart environment principles in managing clean water resources, such as the development of Public Green Open Spaces, waste management, river revitalization, and slum settlement management, remains suboptimal. These aspects significantly impact the establishment of a smart environment, particularly concerning the universal provision of clean water for Makassar's residents.
 Keywords: Makassar City, smart environment, policy, water management
 
 
 

High-resolution X-ray fluorescence-based provenance mapping of Eocene fluvial distributary fans that fed ancient Gosiute Lake, Wyoming, USA

The Green River Formation of Wyoming, USA, is host to the world’s largest known lacustrine sodium carbonate deposits, which accumulated in a closed basin during the early Eocene greenhouse. Alkaline brines are hypothesized to have been delivered to ancient Gosiute Lake by the Aspen paleoriver that flowed from the Colorado Mineral Belt. To precisely trace fluvial provenance in the resulting deposits, we conducted X-ray fluorescence analyses and petrographic studies across a suite of well-dated sandstone marker beds of the Wilkins Peak Member of the Green River Formation. Principal component analysis reveals strong correlation among elemental abundances, grain composition, and sedimentary lithofacies. To isolate a detrital signal, elements least affected by authigenic minerals, weathering, and other processes were included in a principal component analysis, the results of which are consistent with petrographic sandstone modes and detrital zircon chronofacies of the basin. Sandstone marker beds formed during eccentricity-paced lacustrine lowstands and record the migration of fluvial distributary channel networks from multiple catchments around a migrating depocenter, including two major paleorivers. The depositional topography of these convergent fluvial fans would have inversely defined bathymetric lows during subsequent phases of lacustrine inundation, locations where trona could accumulate below a thermocline. Provenance mapping verifies fluvial connectivity to the Aspen paleoriver and to sources of alkalinity in the Colorado Mineral Belt across Wilkins Peak Member deposition, and shows that the greatest volumes of sediment were delivered from the Aspen paleoriver during deposition of marker beds A, B, D, and I, each of which were deposited coincident with prominent “hyperthermal” isotopic excursions documented in oceanic cores.

ROLE OF ELECTROMAGNETIC FIELDS IN DEVELOPMENT OF OIL AND GAS GENERATION PROCESSES IN UNCONVENTIONAL RESERVOIR ROCKS

The specifics of the Bazhenov Formation sediments, which are fundamentally different from traditional Green River oil shales, is that the processes of organic matter (kerogen) transformation into hydrocarbons have not yet been completed in them. The achieved paleotemperatures allowed the studied sediments to enter the main phase of oil formation during the regional catagenetic transformation of kerogen, but they failed to realize their oil-maternal potential to the full extent. At present, there are several unsolved problems for these rocks, related both to the genesis of oil and to the search for commercial hydrocarbon deposits in them and the development of technologies for their further development. The processes of «proto-oil» formation in the Bazhenov Formation sediments are still poorly understood. In fact, these processes are a system of equations with many unknowns, the correct solution of which is still impossible at the current stage of study. In our opinion, an important role in the development of oil formation processes in the Earth’s subsurface is played by magnetic fields formed under the action of a number of reasons (in particular, during the development of numerous tectonic disturbances). Our laboratory experiments by gas chromatography showed that in bitumoids of the studied samples there is a progressive shift of the «naphthenic hump» associated with internal transformations in the magnetic field. As a result of these studies, a decrease in the naphthenic fraction of hydrocarbons in samples heated in a magnetic field was recorded compared to samples without exposure to a magnetic field. Significant differences were found in paired samples of most geochemical characteristics - n-C23/24, n-C25/26, n-C26/27, n-C29/30, OEP, CPI, naphthene sum. Taking into account the influence of electromagnetic fields on the development of oil and gas generation processes allows us to create a completely new technology of «maturation» of hydrocarbon compounds (proto-oil) directly in the oil-maternal sediments and the formation of «artificial/technogenic» oil deposits.

Using Data-Driven Prediction of Downstream 1D River Flow to Overcome the Challenges of Hydrologic River Modeling

Methods for downstream river flow prediction can be categorized into physics-based and empirical approaches. Although based on well-studied physical relationships, physics-based models rely on numerous hydrologic variables characteristic of the specific river system that can be costly to acquire. Moreover, simulation is often computationally intensive. Conversely, empirical models require less information about the system being modeled and can capture a system’s interactions based on a smaller set of observed data. This article introduces two empirical methods to predict downstream hydraulic variables based on observed stream data: a linear programming (LP) model, and a convolutional neural network (CNN). We apply both empirical models within the Colorado River system to a site located on the Green River, downstream of the Yampa River confluence and Flaming Gorge Dam, and compare it to the physics-based model Streamflow Synthesis and Reservoir Regulation (SSARR) currently used by federal agencies. Results show that both proposed models significantly outperform the SSARR model. Moreover, the CNN model outperforms the LP model for hourly predictions whereas both perform similarly for daily predictions. Although less accurate than the CNN model at finer temporal resolution, the LP model is ideal for linear water scheduling tools.

Formation of magnesium‐clay in a lacustrine microbialite‐bearing carbonate deposit, Eocene Green River Formation, Sanpete County, Utah

AbstractAuthigenic magnesium‐clays have been observed and documented in the Green River Formation, specifically as ooidal stevensite grains. Magnesian clays are a valuable proxy for reconstructing shallow‐water, saline–alkaline lake palaeoenvironments due to their responses to chemical changes. Magnesium‐rich clay minerals are relatively common components in modern and ancient lake systems. A rare interaction of lacustrine magnesian clays, microbialites, carbonates and volcanoclastic deposits of the Eocene Green River Formation crop out in Sanpete Valley, Utah, USA. The characterization of this interaction, Mg‐rich clay and carbonate minerals genesis, the environmental controls on Mg‐rich clay minerals distribution and accumulation is still poorly understood. This study has identified various species of Mg‐clay minerals (stevensite, mixed‐layer kerolite–stevensite and sepiolite), along with calcite and dolomite, found in four Mg‐clay‐bearing lithofacies: (i) Mg‐clay stromatolites; (ii) Mg‐clay arenites; (iii) Mg‐claystone; and (iv) intraclastic Mg‐clay hybrid arenites and conglomerates. Magnesium‐clay bearing rocks from the Sanpete Valley area were deposited in a south‐western, shallow embayment of Eocene Lake Uinta along the margin of the Sevier fold and thrust belt. Sanpete Valley's Mg‐clay‐bearing section shows syngenetic mineralogical paragenesis with neoformation of magnesian clays accompanied by calcite and silica. Regional chronostratigraphic correlation of Sanpete Valley's Mg‐clay‐bearing section with the Uinta Basin was made by zircon U–Pb dating (laser ablation–inductively coupled plasma–mass spectrometry) of two tuff beds. Stevensite and kerolite are precipitated under very specific conditions. This study presents a depositional model, considering evidence from the authigenic mineralogy, facies, fossil evidence and basin context. All of these findings allow a comprehensive analysis of the lithostratigraphic and chemostratigraphic evolution of this isolated bay system, as well as texture classification. This study provides analogue for detailed correlation and comparison to other basins containing similar Mg‐clay and microbialite‐bearing deposits.

Semi-closed hydrous pyrolysis of type I source rock using formation water: Implications for biomarker behaviour under supercritical conditions

Hydrous pyrolysis is a useful artificial method to simulate hydrocarbon generation process and investigate the geochemical behaviour of biomarkers with the presence of water, which has great importance for conventional and unconventional oil-gas exploration. Formation water is ubiquitous saline water in oilfields, whereas not commonly utilized in hydrous pyrolysis. To determine the influence of formation water on the expulsion/retention behaviour of commonly utilized oil-source correlation indictors (Pr/Ph, Pr/n-C17, Ph/n-C18, and gammacerane index, C22/C21, C24/C23 and C26/C25 tricyclic terpane ratios, C31R/C30hopane, C31(22S/22S + 22R) hopane, moretane/hopane and Ts/Ts + Tm), two series of semi-closed hydrous pyrolysis experiments were conducted in 300–550 °C for the typical type I Green River Shale source rocks using distilled water and formation water. Such comparative study can also improve the understanding of whether supercritical fluids affect the biomarker behaviour because the temperature for major hydrocarbon generation in hydrous pyrolysis approaches the critical temperature for distilled water. The studied oil-source correlation indictors of immiscible oils generated in both experiments using distilled water and formation water exhibit similar patterns with the increase of thermal maturity levels. Both retained and expelled immiscible oils generated in the experiments using formation water and distilled water are situated in similar area of empirical genetic diagrams (e.g. Pr/n-C17vs Ph/n-C18, C31R/C30 hopanes vs C26/C25 tricyclic terpanes, and ternary plot of C27–C28–C29 regular steranes), suggesting that the presence of formation water/supercritical water does not significantly compromise the utility of these diagrams for oil-source correlation. Outcomes of this study also demonstrate that semi-closed hydrous pyrolysis is a useful artificial method for characterizing biomarker compositions of oils generated by type I source rocks and understanding geochemical behaviour of biomarkers under supercritical conditions.

Laboratory and field evaluation of a new light‐emitting‐diode‐lit quatrefoil light trap for sampling fish early life stages

AbstractObjectiveCreate and test the effectiveness of a new light‐emitting‐diode (LED) light trap for sampling early life stages of fishes in relation to a chemical light stick (CL) lit light trap.MethodsLaboratory experiments compared light intensity of the LED and CL light sources and LED‐ and CL‐lit light trap capture and retention probabilities of Razorback Sucker Xyrauchen texanus and Fathead Minnow Pimephales promelas. Field experiments compared LED‐ and CL‐lit light trap captures of all fishes and Razorback Sucker larvae in both paired and unpaired analysis.ResultThe LED light source had a greater and more stable light intensity over time than the CL light source, and LED‐lit traps had similar capture and retention probabilities in laboratory experiments. However, in field experiments LED‐lit traps captured more fish and Razorback Sucker than CL‐lit traps.ConclusionLED‐lit light traps are as or more effective at sampling early life stages of fishes compared to CL‐lit light traps. Biologists should consider adopting this innovative design to increase sampling effectiveness while eliminating light stick waste.

Illustrating land cover change associated with erosion management of the Little Blue River, Kansas, USA

AbstractErosion is a concern due to environmental degradation, loss of valuable cropland, increased sediment loads in aquatic systems, and reduced reservoir capacity. To manage erosion, riparian forest buffers and bendway weirs were installed in the Little Blue River, Kansas, during years 2002–2010. To illustrate land cover changes associated with management for upland and streambank erosion, indicated through terrestrial land gains, particularly of permanent tree cover relative to short‐lived crop cover, we digitized 1 m orthoimagery. For the pretreatment interval of 1991–2002, we digitized streambank edges to approximate change in river area. Due to river dynamics, for the 2002 and 2014 interval before and after treatment, we used land ownership parcels as fixed locations to assess changes in land area and land classes for 24 treated and 24 untreated parcels, each parcel group totaling 1575 ha. We appraised two extents of the unified streambank for both years and all land in parcels rather than isolating the river from the surrounding watershed. During 1991 to 2002, treated land parcels lost terrestrial land, whereas untreated land parcels gained land. During 2002–2014, treated land had greater river and crop cover, and less tree cover than untreated land. For the entire extent, with similar trends for the unified streambank extent, by 2014, treated parcels gained 27.3 ha of terrestrial land compared to 4.6 ha gained by untreated parcels. Gains occurred in tree cover and losses in river water and sediments cover. In treated parcels crop cover decreased, whereas in untreated parcels crop cover increased. Streamflows decreased over time, likely contributing to streambank stability. Despite lack of documented cost‐share agreements, in untreated parcels, landowners managed land by increasing tree cover to protect soil from erosion. All measurements were consistent with erosion followed by management for erosion through terrestrial land gains of tree cover.

Exploring non-linear and synergistic effects of green spaces on active travel using crowdsourced data and interpretable machine learning

The relationship between green spaces and active travel has been extensively studied. However, the majority of previous studies relied on small datasets concerning active travel and inadequately explored non-linear and/or synergistic effects. This study uses multi-source data and interpretable machine learning techniques to identify the non-linear and synergistic effects of green spaces in Chengdu (China) on two types of active travel: cycling and running. Crowdsourced data from Strava collected in December 2021 is used to measure city-wide active travel levels. Meanwhile, green spaces are evaluated from two viewpoints: overhead view and eye level, with the latter assessed using Baidu Street View imagery. The findings demonstrate that green spaces can account for up to 20% of the variance in active travel. Generally, the effect of the area of green spaces on active travel is positive. When the area of green spaces reaches a certain threshold, its effect becomes marginal and even negative. The green view index displays complex effects on cycling. Furthermore, this study identifies synergistic effects among predictors (e.g., green view index & river line length).

Core-scale numerical simulation and comparison of breakdown of shale and resulting fractures using sc-CO2 and water as injectants

Supercritical carbon dioxide (sc-CO2) is an alternative to water for stimulation of low permeability systems such as shale gas and geothermal resources. Previously core-scale experimental studies have compared the behavior of CO2 to water injection for sample breakdown. Due to differences in experimental setup and core sample preparation, inconsistent or even apparently contradictory conclusions have resulted. To reconcile this contradiction, a phase-field numerical model is applied to understand hydraulic fracturing experiments using Green River shale found in the literature. The finite element numerical model incorporates a rate-dependent phase-field fracture model developed separately to describe fracture initiation and growth. We investigate the impact of various material and fluid properties on the resulting fractures. Most importantly, we study the effect of fluid properties and boundary conditions on the breakdown pressure, including the direction of the resulting fracture plane. Model results predict that (1) sc-CO2 injection in the laboratory may result in greater breakdown pressure than that of water under no-flow boundary conditions because lower viscosity sc-CO2 may result in pressure build up at the core boundary that opposes fracture initiation and (2) lower viscosity sc-CO2 also produces fast-propagating fractures that are less influenced by the bedding plane on their resulting fracture topology. Our model offers a straightforward explanation and reconciliation of existing experimental observations, as well as a means to extrapolate to new conditions. Exploration of field-scale conditions suggests less pronounced or no elevation in breakdown pressure when sc-CO2 is injected because the pressure build up effect at the system boundary is significantly less or absent at field length scales.

Watershed-scale provenance heterogeneity within Eocene nonmarine basin fill: Southern Greater Green River Basin, western USA

Weathering, erosion, and sediment transport in modern landscapes may be investigated via direct observation of attributes such as elevation, relief, bedrock lithology, climate, drainage organization, watershed extent, and others. Studies of ancient landscape evolution lack this synoptic perspective, however, and instead must rely more heavily on downstream records of fluvial deposits. Provenance analysis based on detrital grain ages has greatly enhanced the utility of such records but has often focused broadly on regional to continental scales. This approach may overlook important details of localized watersheds, which could lead to significant misinterpretation of past sediment dispersal patterns. The present study, therefore, explores the impact of geographic and stratigraphic sampling density on detrital zircon provenance, based on a high-density investigation of U-Pb ages (N = 23, n = 4905) obtained from a narrow chronostratigraphic range (∼2 m.y.) within a relatively small (∼25,000 km2) area of an Eocene nonmarine sedimentary basin. Based on multi-dimensional scaling and DZmix modeling, these strata comprise seven distinct, approximately isochronous detrital zircon (DZ) chronofacies, defined as “. . . a group of sedimentary rocks that contains a specified suite of detrital zircon age populations” (Lawton et al., 2010). Four of these DZ chronofacies reflect long-distance transport from extrabasinal source areas. DZ chronofacies CO-1 and CO-2 are interpreted to derive from a primary sediment source in central Colorado (USA), corroborating previously proposed long-distance sediment transport via the Aspen paleoriver. DZ chronofacies ID-1 and ID-2 are interpreted to have been delivered to the basin from central Idaho by the Idaho paleoriver. In contrast, DZ chronofacies UT-1 and UT-2 are interpreted to reflect local drainage from the Uinta Uplift south of the basin, and DZ chronofacies WY-1 is interpreted to have been sourced from the Rawlins, Granite, and Sierra Madre uplifts to the north and east via the Toya Puki paleoriver. Lateral transitions between different DZ chronofacies in some cases occur over distances as little as 5 km, implying that depositional systems carrying sand from disparate watersheds directly competed to fill available basin accommodation. The results of this study reveal a high degree of complexity of Eocene rivers that converged on the Greater Green River Basin, indicating that their deposits contain a rich record of fine-scale landscape evolution across much of the Laramide foreland and Cordilleran orogen. These results illustrate the need for adequate sample density when assessing basin-scale provenance and offer a cautionary consideration for researchers using sandstone (and incorporated authigenic cement) in other nonmarine basins as the basis for paleoaltimetry or detrital thermochronology studies.

A new damselfy from the Lower Eocene Green River Formation (Odonata, Dysagrionidae)

The Eocene Green River Formation in the USA is well known as a Konservat-Lagerstätte, and has yielded an enormous number of beautifully preserved fossil insects from the Parachute Creek Member of Lake Uinta in Colorado and Utah, USA (Grande, 1984) where insects dominate the fauna. In Fossil Lake deposits, fish dominate the fauna with insects a minor component. This formation spans a 5-myr-long period between ca. 53.5 and 48.5 Ma (Smith et al., 2003) in three distinct basins containing lacustrine sediments. Many of these fossils are in an exquisite state of preservation, occasionally even with soft tissues and colour patterns preserved (e.g., Bechly et al., 2020). As this entomofauna is one of the most diverse for the Early Eocene, increasing its knowledge is crucial for the understanding of the evolution of the insects at that time. This is especially the case for the Odonata, a clade that remains poorly known for the Paleocene and early Eocene (Nel & Jouault, 2022). Bechly et al. (2020) provided a first revision of the damselflies from the Green River Formation, but continuing excavation produces new specimens. The specimen described herein was recently discovered while excavating fossil fish in the Fossil Lake deposits of the Green River Formation in southwest Wyoming. This new species of Zygoptera from the Fossil Lake deposits further demonstrates its impressive diversity of Odonata.

Scanning electron microscopic evaluation of broad ion beam milling effects to sedimentary organic matter: Sputter-induced artifacts or naturally occurring porosity?

Research examining organic-matter hosted porosity has significantly increased during the last decade due to greater focus on understanding hydrocarbon migration and storage in source-rock reservoirs, and technological advances in scanning electron microscopy (SEM) capabilities. The examination of nanometer-scale organic-matter hosted porosity by SEM requires the preparation of exceptionally flat geologic samples beyond the abilities of traditional mechanical polishing, which can deform or otherwise obscure organic surfaces. To meet this demand, broad ion beam (BIB) milling was introduced as a sample preparation technique for SEM petrographic analysis of geologic samples. As with any sample preparation technique, there can be unintended consequences. In this study, we examined the development of nanometer-scale sputter-induced voids caused by BIB milling of thermoset plastic binder material [poly(methyl methacrylate), PMMA] used for the mounting of geologic samples, and artifact sputter-induced voids in the organic matter of Green River Formation and Kimmeridge Clay Formation source rocks. Development of artifact sputter-induced voids was evaluated in relation to variations in the slope of the sample examination surface (0.0–4.9% slope), effectively varying the angle of ion incidence. The results indicate that only minor variations in the angle of ion incidence can generate sputter-induced voids in both PMMA (10.0–386.2 nm diameter sputter-induced voids) and sample sedimentary organic matter (solid bitumen; 12.2–103.6 nm diameter sputter-induced voids). Overall, average artifact pore diameters increased with increasing ion incidence angle within PMMA. Although sputter-induced voids within solid bitumen in the Green River Formation sample were only found in limited extent, the size of these void artifacts falls within the same size range as naturally occurring meso-macroporosity. That is, the pore-like artifacts could easily be misconstrued as naturally developed organic porosity, which is a major concern for SEM-based porosity evaluation methods. This study describes the factors that contribute to the creation of artifact sputter-induced voids, their distinguishing characteristics, and best practices for avoiding the creation of ion-induced artifacts.

Simulations of winter ozone in the Upper Green River basin, Wyoming, using WRF-Chem

Abstract. In the Upper Green River basin (UGRB) of Wyoming and the Uintah Basin of Utah, strong wintertime ozone (O3) formation episodes leading to O3 mixing ratios occasionally exceeding 70 parts per billion (ppb) have been observed over the last 2 decades. Wintertime O3 events in the UGRB were first observed in 2005 and since then have continued to be observed intermittently when meteorological conditions are favorable, despite significant efforts to reduce emissions from oil and natural gas extraction and production. While O3 formation has been successfully simulated using observed volatile organic compound (VOC) and nitrogen oxide (NOx) mixing ratios, successful simulation of these wintertime episodes using emission inventories in a 3-D photochemical model has remained elusive. An accurate 3-D photochemical model driven by an emission inventory is critical to understanding the spatial extent of high-O3 events and which emission sources have the most impact on O3 formation. In the winter of 2016/17 (December 2016–March 2017) several high-O3 events were observed with 1 h mixing ratios exceeding 70 ppb. This study uses the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) to simulate one of the high-O3 events observed in the UGRB during March 2017. The WRF-Chem simulations were carried out using the 2014 edition of the Environmental Protection Agency National Emissions Inventory (EPA NEI2014v2), which, unlike previous versions, includes estimates of emissions from non-point oil and gas production sources. Simulations were carried out with two different chemical mechanisms: the Model for Ozone and Related Chemical Tracers (MOZART) and the Regional Atmospheric Chemistry Mechanism (RACM), and the results were compared with data from seven weather and air quality monitoring stations in the UGRB operated by the Wyoming Department of Environmental Quality (WYDEQ). The simulated meteorology compared favorably to observations with regard to temperature inversions, surface temperature, and wind speeds. Notably, because of snow cover present in the basin, the photolysis surface albedo had to be modified to predict O3 in excess of 70 ppb, although the models were relatively insensitive to the exact photolysis albedo if it was over 0.65. O3 precursors, i.e., NOx and VOCs, are predicted similarly in simulations with both chemical mechanisms, but simulated VOC mixing ratios are a factor of 6 or more lower than the observations, while NOx is also underpredicted but to a lesser degree. Sensitivity simulations revealed that increasing NOx and VOC emissions to match observations produced slightly more O3 compared to baseline simulations, but an additional sensitivity simulation with doubled NOx emissions resulted in a considerable increase in O3 formation. These results suggest that O3 formation in the basin is most sensitive to NOx emissions.

The First Discovery of a Fish Fossil (Phareodus sp.) from Paleogene Fluvial Deposits in Western Washington State, USA

The 2023 discovery of a fish fossil from lower Eocene strata of the Chuckanut Formation provides new insights into the paleoenvironment and paleoecology of one of the region’s most prolific fossil deposits. The detrital clastic fluvial and floodplain deposits of the Chuckanut Formation are not favorable for the preservation of fish, but the high quality of preservation of this specimen is evidence that some Chuckanut Formation sediments provide suitable depositional conditions for the preservation of skeletal remains. This information improves our understanding of the range of depositional environments within the Chuckanut Formation, and provides clues for searching for additional specimens. The discovery of this fossil has larger significance; the skeletal remains of fish are scarce in fluvial and floodplain deposits. Despite its incompleteness, dorsal fin and caudal fin ray anatomy suggest that the specimens represent the extinct genus Phareodus, an open-water carnivore that has previously only been reported in North America from the Green River and Bridger Formations in Wyoming and Utah, USA.

First recognition of the extinct eudicot genus Palibinia in North America: Leaves and fruits of Palibinia comptonifolia (R.W.Br.) comb. nov. from the Eocene of Utah and Colorado, USA

AbstractNewly investigated leafy twigs bearing axillary fruits from the Eocene Parachute Creek Member of the Green River Formation in eastern Utah, USA, have provided more information on the species previously attributed to the Proteaceae as Banksia comptonifolia R.W.Br. The leaves are simple, estipulate with short petioles, and elongate laminae with prominent angular nonglandular teeth. The laminae have a thick midvein and pinnate craspedodromous secondaries, and are distinctive in the presence of a thick, often coalified, marginal rim. Vegetative and reproductive buds occur in the axils of the leaves. These features indicate that the species belongs to Palibinia Korovin—an extinct Eudicot genus previously known only from the Paleogene of Asia and Europe. Small pedicellate ovoid fruits 1.5–2.2 mm wide are borne in fascicles of three and are seen to be capsules with four apical valves. Despite the specific epithet referring to similarity of the foliage to that of Comptonia (Myricaceae), the fasciculate inflorescence organization with axillary flowers is quite distinct from the catkins characteristic of that family. Assignment to Banksia or other Proteaceae with complex inflorescences and follicular fruits is also problematic. Additionally, MacGinitie′s transfer of the species to Vauquelinia of the Rosaceae is contradicted by the lack of stipule scars on the twig and by differences in leaf venation and floral morphology. We transfer the species to Palibinia comptonifolia (R.W.Br.) comb. nov., but its familial affinity within the Pentapetalae remains uncertain. This new occurrence augments records from the Paleogene of Turkmenistan, Kazakhstan, China, England, and Germany.

Zn, Cu, Ni, Cd, and Pb in the foot tissue of freshwater pearl mussels from Green Belt rivers of Fennoscandia

Margaritifera margaritifera is a critically threatened species in Europe. Metal pollution may be one of the reasons for its decline, but the influence of this factor remains insufficiently studied. Zn, Cu, Ni, Cd, and Pb were determined in the foot tissue of the freshwater pearl mussel Margaritifera margaritifera (bivalvia, margaritiferidae) from Green Belt rivers of Fennoscandia [the Murmansk region (Kola Peninsula) and Karelia (northern part)] and the accumulation of the metals was shown to be variable; however, their levels in the molluscs, being quite long-lived aquatic organisms, do not exceed the established standards of the Russian Federation. The recorded levels of the metals in the foot tissue of the Margaritifera margaritifera can be considered indicators of the background levels of geologic and anthropogenic metal concentrations in the environment influencing the distribution and development of this protected species in the lake-river systems of the Green Belt of Fennoscandia.