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This paper presents a high-level overview of site characterization, risk analysis and monitoring priorities for underground energy-related product storage or sequestration facilities. The siting of an underground storage or sequestration facility depends on several important factors beginning with the area of review. Collection of all existing and available records and data from within the rock volume, including potential vulnerabilities such as prior containment issues, proximity to infrastructure and/or population centres, must be evaluated. Baselining of natural processes before storage or sequestration operations begin provides the basis for assessing the effects of storage or sequestration on the surroundings. These initial investigations include geological, geophysical and geochemical analyses of the suitability of the geological host rock and environs for storage or sequestration. A risk analysis identifies and evaluates threats and hazards, the potential impact should they develop into unwanted circumstances or events and the consequences to the facility should any of them occur. This forms the basis for framing effective mitigation measures. A comprehensive monitoring programme that may include downhole well surveillance, observation wells, geochemical sampling and well testing ensures that the facility operates as designed and that unforeseen issues, such as product migration or loss of integrity, can be identified and mitigated. In addition to these technical issues, human factors and public perception of a project are a critical part of the site characterization, construction and operational phases of a project. Despite differences between underground storage and sequestration, the characterization, risk analysis and monitoring approaches that were developed for underground natural gas storage or for carbon dioxide sequestration could be used for underground storage or sequestration of any type of energy-related product. Recommendations from this work include: (1) develop an industry-standard evaluation protocol (workflow) for the evaluation of salt beds, saline aquifers, depleted hydrocarbon reservoirs, underground mines and cased wellbores for potential underground storage or sequestration development beyond those in use today; and (2) develop an industry-wide collaborative process whereby incident and near-miss data related to underground storage or sequestration operations can be reported, documented and shared for use in refining risk analysis modelling.

Geological structures in the subsurface have been used for the storage of energy and waste products for over a century. Depleted oil and gas fields, saline aquifers or engineered caverns in salt or crystalline rocks are used worldwide to store energy fluids intended to provide demand buffers and sustained energy supply. The transition of our energy system into a clean, renewable-based system will most likely require an expansion of these subsurface storage activities, to host a wide variety of energy products (e.g. natural gas, hydrogen, heat or waste energy products, like CO 2 ) to balance the inherent intermittence of the renewable energy supply. Ensuring the safety and effectiveness of these subsurface storage operations is therefore crucial to achieve the sought-after renewable energy transition while ensuring energy security.

HighlightsIn-channel sediment and TP storage were quantified along 13.5 km of a stream.TP and sediment masses were 1 and 3 times greater than their respective annual watershed load.Colluvial material at streambank toe represented the dominant storage pool.Sinuous stream reaches exhibited significantly greater storage versus channelized reaches.Abstract. In-channel storage of both fine sediment and sediment-bound phosphorus has been recognized as potentially large contributors to respective watershed loads, yet they are rarely quantified in the field. In this field-based study, we quantified and characterized in-channel fine sediment and total phosphorus (TP) storage within a third-order stream. We hypothesized storage to be significant within the context of watershed-scale sediment and TP loads and that storage trends are influenced by channel characteristics and hydraulics. In May 2015, the volume of stored in-channel sediment was estimated within a 13.5 km stretch of Walnut Creek, an alluvial stream draining an agriculturally dominated watershed in Jasper County, Iowa, USA. Storage volume was estimated in-field through a series of 240 transects which were stratified across reaches of the varying channel and hydraulic conditions (e.g., sinuosity, stream power). Overall storage volume was broken down into feature classes (e.g., point bars) based on in-channel depositional processes. Following in-field quantification, feature class sediment samples were collected and analyzed for physical properties (e.g., bulk density) and TP concentration. Physical and chemical analyses, coupled with in-field volume estimation, allowed for watershed-scale masses of in-channel sediment and TP to be calculated and then placed within the context of respective annual loads. Sediment and TP were estimated to be stored at ~2.7 Mg m-1 and 0.7 kg m-1, respectively. Sinuous reaches exhibited significantly greater sediment storage volume (p < 0.001) and depth (p < 0.001) versus straight reaches. Reach sinuosity exhibited a significant positive correlation (p = 0.03) with storage mass and represented the most effective storage predictor. The majority of storage mass (72%) was represented by colluvial material accumulations at the streambank toe. Loose bed sediment was the second greatest contributor to storage mass (18%), with the remaining feature classes (e.g., bars) representing a combined ~10%. Sediment storage mass was ~3.25 times greater than the watershed suspended sediment load for 2015. The TP mass was found to be nearly equal to the respective watershed load for 2015. In-channel sediment and TP storage masses within Walnut Creek were found to be significant in comparison to respective annual loads, and thus storage is expected to play a significant role in respective watershed routing, loading, and the overall budgets of these parameters. Though challenging, quantification of in-channel fine sediment and TP storage is necessary to relate source contributions (e.g., streambank erosion) to watershed loads and is critical to account for interannual sediment and TP export. Keywords: Channel evolution, Channel morphology, Iowa, Sinuosity, Stream power, Water quality, Watershed export.

Carbon capture and sequestration (CCS) is widely recognized as an important component of technological approaches to directly address carbon dioxide (CO 2 ) emissions. The geological sequestration aspect of CCS requires careful site selection and assessment of processes when planning a CCS project, including coupled fluid flow–thermal–geochemical–geomechanical phenomena. In this paper, we present a high-level overview of carbon capture utilization and sequestration (CCUS): the geological sequestration aspect, global projects/facilities, regulatory framework and financial incentives for CCUS. We review the current research areas in geomechanics (including pore pressure–stress coupling, fault reactivation and caprock integrity) associated with geological CO 2 sequestration and discuss the role of rock physics in monitoring, verification and accounting activities. Finally, we suggest research needs that are critical to facilitating the deployment of CCS and improving geomechanical assessments of CO 2 sequestration sites.

Storage of energy-related products in the geological subsurface provides reserve capacity, resilience, and security to the energy supply chain. Sequestration of energy-related products ensures long-term isolation from the environment and, for CO 2 , a reduction in atmospheric emissions. Both porous-rock media and engineered caverns can provide the large storage volumes needed for energy security and supply-chain resilience today and in the future. Methods for site characterization and modelling, monitoring, and inventory verification have been developed and deployed to identify and mitigate geological threats and hazards such as induced seismicity and loss of containment. Broader considerations such as life-cycle analysis, environment, social and governance (ESG) impact and effective engagement with stakeholders can reduce project uncertainty and cost while promoting sustainability during the ongoing energy transition toward net-zero or low-carbon economies.

After fertilization, remodeling of the oocyte and sperm genomes is essential to convert these highly differentiated non-dividing transcriptionally quiescent cells into early cleavage-stage transcriptionally active totipotent blastomeres. This developmental transition is accompanied by cell cycle adaptation such as lengthening or shortening of the gap phases G1 and G2. However, regulation of these cell cycle changes is poorly understood, especially in mammals. Checkpoint kinase 1 (CHK1) is a protein kinase that regulates cell cycle progression in somatic cells. Here, we show that CHK1 regulates cell cycle progression in early mouse embryos by restraining CDK1 kinase activity due to CDC25A phosphatase degradation. CHK1 kinase also ensures the long G2 phase needed for genome activation and reprogramming gene expression in 2-cell stage mouse embryos. Last,Chk1depletion leads to DNA damage and chromosome segregation errors that result in aneuploidy and infertility.

MicroRNAs (miRNAs) are small, noncoding RNAs that regulate gene expression after transcription. miRNAs are present in transcriptionally quiescent full-grown oocytes and preimplantation embryos that display a low level of transcription prior to embryonic genome activation. The role of miRNAs, if any, in preimplantation development is not known. The temporal pattern of expression of miRNAs during bovine preimplantation development was determined by small RNA-sequencing using eggs and preimplantation embryos (1-cell, 2-cell, 4-cell, 8-cell, 16-cell, morula, and blastocyst). Embryos cultured in the presence of α-amanitin, which permitted the distinguishing of maternal miRNAs from embryonic miRNAs, indicated that embryonic miRNA expression was first detected at the two-cell stage but dramatically increased during the morula and blastocyst stages. Targeting DGCR8 by a small-interfering RNA/morpholino approach revealed a role for miRNAs in the morula-to-blastocyst transition. Knockdown of DGCR8 not only inhibited expression of embryonically expressed miRNAs but also inhibited the morula-to-blastocyst transition. In addition, RNA-sequencing identified an increased relative abundance of messenger RNAs potentially targeted by embryonic miRNAs in DGCR8-knockdown embryos when compared with controls. Results from these experiments implicate an essential role for miRNAs in bovine preimplantation embryo development.

Introduction: The edge of the pre-Noachian Borealis impact basin, thought to be the cause of the planetary dichotomy boundary [1-2], crosses the northern Valles Marineris troughs [1-3]. Intense deformation is exposed in the deepest parts of the Ophir and Hebes Chasmata, the northernmost troughs. Structural geology and mineralogical analyses motivate the tentative identification of brittle and brittle-ductile shear zones and hydrothermal activity in the Valles Marineris basement. Implications for the Borealis basin and the proto-Valles Marineris crust are examined. Structural analysis: Crustal right-lateral shear zones are identified in the pre-Noachian basement of Ophir and Hebes Chasmata (Figure 1). In Ophir Chasma, S-C-C' structures, indicate deformation in the brittle-ductile domain. In Hebes Chasma, megabreccia indicates brittle deformation. From scaling relationships [4-5], the shear zones are inferred to be at least hundreds of kilometers long. They do not extend to the surface nor even up into the interior layered deposits (ILD), and are therefore interpreted to affect the Valles Marineris basement only, which at this depth, is interpreted to be of pre-Noachian age. Mineralogy: A new method of non-linear spectral unmixing derived from the LinMin algorithm [6] is implemented and applied to three pre-Noachian basement exposures in a CRISM cube in Ophir Chasma. After gas absorption removal, two groups of minerals are robustly detected (Figure 2): primary minerals of mafic rocks (olivine, hypersthene, augite, anorthite, albite), and sulfates, most of them likely of hydrothermal origin (copiapite, jarosite, szomolnokite). Anhydrite (ROI3) is not diagnostic of any particular environment. Kieserite is interpreted as transported by wind from the neighboring ILDs. S-C-C' structures constrain the granulometry of the sheared rock which, under the assumption that all the primary minerals are detected, would be olivine-gabbronorite (ROI1) or troctolite (ROI2-3). Combined structural and mineralogical analyses point to hydrothermal alteration of a mafic intrusive basement, or contamination of this basement by hydrothermal activity in the ILDs. Relationships with the Borealis basin: The general trend of the shear zones follows the edge of the Borealis as inferred from gravity and topography [4], also of pre-Noachian age, suggesting that they may have initiated as basin ring faults and were reactivated as crustal shears. North of Valles Marineris, the radial component of the remanent magnetic field at the surface [7] shows elongated anomalies that follow the trend of the shear zones and more generally, the expected curved edge of the Borealis basin. The existence of a magnetic field (or dynamo) was coeval with formation of the planetary dichotomy boundary [8]. Two anomalies also correspond to Noachian or pre-Noachian crustal ridges in Ophir Planum, of igneous [9] or tectonic [10] origin. Mapping reveals that the ridges are fractured parallel to the magnetic anomalies, and that their topography guided a hydrologic system (Figure 3). Moreover, these fractures are parallel to a dyke swarm exposed in eastern Candor Chasma [11]. Therefore, the ridges have a volcanotectonic origin within an active hydrologic context. Figure 1. Ophir shear zone (OSZ) and Hebes shear zone (HSZ): (a) location map showing trace of the Borealis impact basin with ±5° uncertainty (dashed area) [5]; (b) zoom on S-C-C' structures in the OSZ, and illustration of shear orientations; (c) zoom on fault megabreccia in the HSZ. HiRISE images ESP_017754_1755 and ESP_040211_1790. Figure 2. Results of nonlinear spectral unmixing applied to basement exposures in Ophir Chasma: (a) CRISM cube location (frt00018b55_07_if165l_trr3); (b) the cube (bands R: 233, G: 78, B: 13); (c) mineral relative abundances, after aerosol contribution removal; (d) best fit plots and HiRISE images of the basement exposures: ESP_051999_1755, ESP_039525_1755, ESP_039525_1755. Figure 3. Features related to hydrothermal activity possibly resulting from the Borealis impact and suggested to explain magnetic banding north of Coprates Chasma. Dykes are located thanks to HiRISE images. The rose diagram was established from 26 representative dykes observed on the eastern Candor Chasma wall; the indicated strike refers to the mean resultant dyke orientation. Magnetic anomalies are from [7]. Topographic contours (spacing 500 m) are from HRSC (ESA/DLR/Freie Univ. Berlin). Circumferential magnetic anomalies are observed at some terrestrial impact craters (e.g.[12]) as well as the Chicxulub impact basin [13] and are due to crystallization of magnetic minerals in an impact-related hydrothermal system [14]. We suggest, therefore, that the magnetic anomalies measured above the Valles Marineris plateau similarly result from hydrothermal activity in response to the Borealis impact, and follow basin ring structures. This hydrothermal activity might be the surface counterpart of deep hydrothermal activity in the basement detected using spectral unmixing [15]. Conclusions: Analysis of northeastern Valles Marineris supports the interpretation of a pre-Noachian Borealis impact basin that would have underlain the later northern troughs of Valles Marineris in the presence of an active dynamo. Large shear zones in the Valles Marineris basement would be reactivated ring faults. Borealis basin formation may have triggered a huge hydrothermal system, identified along these structures and also producing magnetic minerals that generated the observed magnetic anomalies. Primary deposits of base and rare metals likely formed as well. Other evidence of hydrothermal activity at the edge of the Borealis basin would confirm these interpretations. References: [1] Andrews-Hanna J. et al. (2008) Nature, 453, 1212–1215. [2] Marinova M. M. et al. (2008) Nature, 453, 1216–1219. [3] Andrews-Hanna J. (2012) J. Geophys. Res., 117, E03006. [4] Schultz R. A. and Fossen H. (2002) J. Struct. Geol. 24, 1389–1411. [5] Fossen H. (2010) Structural Geology, Cambridge Univ. Press. [6] Schmidt F. et al. (2014) Icarus, 237, 61–74. [7] Langlais B. et al. (2019) J. Geophys Res., 109, E02008. [8] Mittelholz et al. (2020) Sci. Adv., eaba0513. [9] Tanaka K. L. et al. (2014) USGS Sci. Inv. Map 3292. [10] Viviano-Beck et al. (2017) Icarus, 284, 43–58. [11] Mège D. and Gurgurewicz J. (2017) 48th LPSC, Abstract #1087. [12] Hawke P. J. et al. (2006) Explor. Geophys., 37, 191–196. [13] Abramov O. and Kring D. A. Meteor. Planet. Sci., 42, 93–112. [14] Osinski G. R. et al. (2011) Meteor. Planet. Sci., 36, 731–745. [15] Gurgurewicz J. et al., submitted to Commun. Earth Environ.

Recent events resulting from the Covid-19 pandemic precipitated a triage-like environment wherein experienced faculty were forced to convert courses rapidly to online venues. This unexpected circum...

It remains poorly understood how histone modifications regulate changes in gene expression during preimplantation development. Using a bovine model, we profiled changes in two activating (H3K4me3 and H3K27ac) and two repressive (H3K9me3 and H3K27me3) marks in oocytes, 2-, 4- and 8-cell embryos (that developed in the presence or absence of the transcription inhibitor a-amanitin), morula, blastocysts, inner cell mass cells and trophectoderm. In oocytes, we find that broad bivalent domains of H3K4me3 and H3K27me3 mark developmental genes, and that prior to genome activation, H3K9me3 and H3K27me3 co-occupy gene bodies. During genome activation, chromatin accessibility is established before canonical H3K4me3 and H3K27ac, and although embryonic transcription is required for this active remodeling, it is dispensable for maintenance of pre-established histone marks. Finally, blastocyst lineages are defined by differential Polycomb repression and transcription factor activity. Overall, these results further support the use of bovine as a more appropriate model system than the mouse to study genome activation and cell lineage specification during human preimplantation development.

Stream bank erosion in agricultural landscapes is a major pathway for non-point source sediment and phosphorus loading of receiving waters. Previous studies have shown direct and indirect effects of land use on stream bank erosion, and identified high erosion rates within riparian pastures. One potential impact of agricultural land-use on stream bank erosion is the alteration of stream stage characteristics, including an increase in frequency of high-stage events over short periods of time (forming flash hydrographs). The objective of this study was to assess the relationship between the number of high stream stages and corresponding stream bank soil erosion. The study was conducted in six grazed pasture stream reaches within the Rathbun Lake Watershed, a reservoir on the Chariton River located within the Southern Iowa Drift Plain. The erosion pin method was utilized to measure the change in stream bank erosion in response to differences in the number of high stream-stage events, which were monitored by pressure transducers. The measured seasonal bank erosion rates were correlated with the different stream stages data to assess their impact on stream bank erosion. Based on the different model assumptions, there were generally strong linear relationships between high stage and bank erosion. Approximately 75% of the variability in stream bank erosion rates was directly linked to the number of high stages/erosive stream flow depths. Conservation practices that reduce these erosion rates will be those that increase soil-water infiltration, reduce the frequency of high stream flow events and increase bank stability through perennial vegetation cover or reducing disturbance within the riparian zone.

SummaryA core-based fracture prediction method is used to illustrate a value-of-information (VOI) decision-analysis protocol to inform completion decisions in tight gas sandstones. The ratio of late host-rock cement to available pore volume (PV), or degradation index, uses petrographic observations of cement distributions in core (including sidewall cores) to predict whether nearby but unsampled fractures (widths > 0.5 to 1 mm) are sealed (nonconductive) or open (conductive). Measurements from four sandstone plays suggest that the index correctly predicts open vs. sealed fractures with an accuracy in excess of 80%. The value added is calculated using Bayesian inference in which the accuracy of the index serves as the likelihood of the prior distribution of open fractures to assess the posterior probability that data represent a useful predictor of producibility. VOI of the prediction method is more than three times the cost to acquire the data. VOI is most sensitive to play-specific geologic and cost parameters including cost to drill, expected revenue from a successful well, cost of completion, cost of acquiring data for the index, and fracture probability distributions. The approach provides a way to value acquiring fracture data and points to a need for zone-specific production data in tight gas sandstones.

Volunteer cleanup operations collect large datasets on anthropogenic litter that are seldom analyzed. Here we assess the influence of land use in both near-stream and watershed scale source domains on anthropogenic litter concentration (standing stock, kg km−1) in riparian zones of Iowa, USA. We utilized riparian litter concentration data on four classes of anthropogenic litter (metal, recyclable, garbage, and tires) from volunteer cleanup operations. Anthropogenic litter data were tested for correlation with near-stream and watershed scale land uses (developed, road density, agricultural, and open lands). Road density (road length/area) and developed land use (% area) were significantly correlated to anthropogenic litter, but agricultural (% area) and open lands (% area) were not. Metal objects correlated to near-stream road density (r = 0.79, p = 0.02), while garbage and recyclable materials correlated to watershed scale road density (r = 0.69, p = 0.06 and r = 0.71, p = 0.05 respectively). These differences in the important spatial scales of land use may be related to differences in transport characteristics of anthropogenic litter. Larger, denser metal objects may be transported more slowly through the watershed/channelized system and thus, dependent on more proximal sources, whereas smaller, less dense garbage and recyclable material are likely transported more rapidly, resulting in concentrations that depend more on watershed scale supply. We developed a linear regression model that used near-stream road density and the total amount of observed litter to predict an average anthropogenic litter density of 188 kg km−1 and a standing stock of 946 t in all Iowa streams (>4th Strahler order). The techniques employed in this study can be applied to other professional and volunteer litter datasets to develop prevention and cleanup efforts, inform investigations of process, and assess management actions.

Summary Oil and gas production from unconventional reservoirs, which are usually stratified with layers having different mechanical properties, generally requires the aid of hydraulic–fracturing technology. Predicting hydraulic–fracture–height growth is one of the critical factors in designing successful hydraulic–fracturing treatments. It has been well–documented that the in–situ–stress contrast between adjacent layers and interface properties are the dominating factors in fracture–height containment, whereas the modulus contrast between adjacent layers is generally considered to be of secondary importance in the direct control of fracture–height containment. However, the arrest of fluid–driven fractures at soft layers is often observed in outcrops and hydraulic–fracture–diagnostic field tests. The objective of this study is to investigate fracture–height containment resulting from the modulus contrast between adjacent layers. To illustrate the effect of modulus contrast on fracture–height containment, this study proposes a new approach that uses the effective modulus of a layered reservoir. We use 2D finite–element models to evaluate the effective modulus of a layered reservoir, considering the effects of modulus values, fracture–tip location, height percentage of each rock layer, layer location, the number of layers, and the mechanical anisotropy. Then, the effect of modulus contrast on fracture–height growth is investigated with an analysis of the stress–intensity factor, taking into account the change of the effective modulus as the fracture tip propagates from the stiff layer to the soft layer. This study shows that the detail of layering does not affect the effective modulus and the only important parameters are fracture–tip locations, modulus values, and the height percentage of each rock layer. In addition, this study empirically derives two approximations of effective moduli depending on fracture–tip locations: the modified height–weighted mean and the modified height–weighted harmonic average. Results from combining linear–elastic fracture mechanics with the effective–modulus approximations show that height growth will be inhibited by the soft layer because of a reduced stress–intensity factor. The effective moduli can be applied to other hydraulic–fracture models to take into account the layering effect. This study also shows that soft layers inhibit hydraulic–fracture–height growth in layered reservoirs. As a result, hydraulic–fracture–height containment within a stratified rock stack can be better evaluated by comparing the modulus contrast between adjacent layers.

The objective of this study was to develop a conceptual framework to study soil aggregate dynamics through the integration of aggregation, disruption, stabilization and destabilization processes of soil constituent units. We used aggregate‐size distribution and water stability of macroaggregates to evaluate changes in soil aggregates in two ecosystems where one is the ‘reference’ state and the other is the ‘new’ state. The framework was validated with data from (a) a non‐buffered annual row crop (ARC) system, (b) a no‐till (NT) system and (c) a bare fallow (BF) system. The dynamics of soil aggregates in the ARC were dominated by the disruption of aggregates (the aggregation–disruption index (ADI) was −0.08), in NT they were dominated by the aggregation process (ADI = 0.03) and in BF dominated by the disruption of aggregates (ADI = −0.20). Three pathways were observed: (a) expression of the aggregation process, which is essential in reestablishing soil structure and functionality, (b) expression of the disruption process, which is critical in the destruction of soil structure and (c) prevalence of mixed behaviour, where the dominant process depended on the relative rate of aggregation and disruption. The proposed framework and study of the carbon associated with aggregates could pave the way for the development of a methodology for the quantitative study of soil organic carbon (SOC) dynamics, carbon inputs (outputs), soil carbon fractions, and edaphic and biotic conditions that regulate SOC dynamics. HIGHLIGHTS: Soil aggregate dynamics were assessed within multiple management systems. A new methodology is proposed for the quantitative study of soil aggregate dynamics. Provided an understanding of aggregation, disruption, stabilization and destabilization in aggregate dynamics. Aggregate dynamic pathways of value in land management can minimize deterioration of the environment.