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USGS1991

An analytical model for in situ extraction of organic vapors

This paper introduces a simple convective-flow model that can be used as a screening tool and for conducting sensitivity analyses for in situ vapor extraction of organic compounds from porous media. An assumption basic to this model was that the total mass of volatile organic chemicals (VOC) exists in three forms: as vapors, in the soil solution, and adsorbed to soil particles. The equilibrium partitioning between the vapor-liquid phase was described by Henry's law constants (K(H)) and between the liquid-soil phase by soil adsorption constants (K(d)) derived from soil organic carbon-water partition coefficients (K(oc)). The model was used to assess the extractability of 36 VOCs from a hypothetical site. Most of the VOCs appeared to be removable from soil by this technology, although modeling results suggested that rates for the alcohols and ketones may be very slow. In general, rates for weakly adsorbed compounds (K(oc) < 100 mL/g) were significantly higher when K(H) was greater than 10-4 atm??m3??mol-1. When K(oc) was greater than about 100 mL/g, the rates of extraction were sensitive to the amount of organic carbon present in the soil. The air permeability of the soil material (k) was a critical factor. In situ extraction needs careful evaluation when k is less than 10 millidarcies to determine its applicability. An increase in the vacuum applied to an extraction well accelerated removal rates but the diameter of the well had little effect. However, an increase in the length of the well screen open to the contaminated zone significantly affected removal rates, especially in low-permeability materials.This paper introduces a simple convective-flow model that can be used as a screening tool and for conducting sensitivity analyses for in situ vapor extraction of organic compounds from porous media. An assumption basic to this model was that the total mass of volatile organic chemicals (VOC) exists in three forms: as vapors, in the soil solution, and adsorbed to soil particles. The equilibrium partitioning between the vapor-liquid phase was described by Henry's law constants (KH) and between the liquid-soil phase by soil adsorption constants (Kd) derived from soil organic carbon-water partition coefficients (Koc). The model was used to assess the extractability of 36 VOCs from a hypothetical site. Most of the VOCs appeared to be removable from soil by this technology, although modeling results suggested that rates for the alcohols and ketones may be very slow. In general, rates for weakly adsorbed compounds (Koc < 100 mL/g) were significantly higher when KH was greater than 10-4atm-m3-mol-1. When Koc was greater than about 100 mL/g, the rates of extraction were sensitive to the amount of organic carbon present in the soil. The air permeability of the soil material (k) was a critical factor. In situ extraction needs careful evaluation when k is less than 10 millidarcies to determine its applicability. An increase in the vacuum applied to an extraction well accelerated removal rates but the diameter of the well had little effect. However, an increase in the length of the well screen open to the contaminated zone significantly affected removal rates, especially in low-permeability materials.

Journal of Hazardous Materials↗

USGS2008

Thermal history of the unsaturated zone at Yucca Mountain, Nevada, USA

Secondary calcite, silica and minor amounts of fluorite deposited in fractures and cavities record the chemistry, temperatures, and timing of past fluid movement in the unsaturated zone at Yucca Mountain, Nevada, the proposed site of a high-level radioactive waste repository. The distribution and geochemistry of these deposits are consistent with low-temperature precipitation from meteoric waters that infiltrated at the surface and percolated down through the unsaturated zone. However, the discovery of fluid inclusions in calcite with homogenization temperatures (Th) up to ???80 ??C was construed by some scientists as strong evidence for hydrothermal deposition. This paper reports the results of investigations to test the hypothesis of hydrothermal deposition and to determine the temperature and timing of secondary mineral deposition. Mineral precipitation temperatures in the unsaturated zone are estimated from calcite- and fluorite-hosted fluid inclusions and calcite ??18O values, and depositional timing is constrained by the 207Pb/235U ages of chalcedony or opal in the deposits. Fluid inclusion Th from 50 samples of calcite and four samples of fluorite range from ???35 to ???90 ??C. Calcite ??18O values range from ???0 to ???22??? (SMOW) but most fall between 12 and 20???. The highest Th and the lowest ??18O values are found in the older calcite. Calcite Th and ??18O values indicate that most calcite precipitated from water with ??18O values between -13 and -7???, similar to modern meteoric waters. Twenty-two 207Pb/235U ages of chalcedony or opal that generally postdate elevated depositional temperatures range from ???9.5 to 1.9 Ma. New and published 207Pb/235U and 230Th/Uages coupled with the Th values and estimates of temperature from calcite ??18O values indicate that maximum unsaturated zone temperatures probably predate ???10 Ma and that the unsaturated zone had cooled to near-present-day temperatures (24-26 ??C at a depth of 250 m) by 2-4 Ma. The evidence of elevated temperatures persisting in ash flow tuffs adjacent to parent calderas for as much as ???8 Ma is a new finding, but consistent with thermal modeling. Simulations using the HEAT code demonstrate that prolonged cooling of the unsaturated zone is consistent with magmatic heat inputs and deep-seated (sub-water table) hydrothermal activity generated by the large magma body ???8 km to the north that produced the 15-11 Ma ash flows and ash falls that make up Yucca Mountain. The evidence discussed in this and preceding papers strongly supports unsaturated zone deposition of the secondary minerals from descending meteoric waters. Although depositional temperatures reflect conductive (and possibly vapor-phase convective) heating of the unsaturated zone related to regional magmatic sources until perhaps 6 Ma, depositional conditions similar to the present-day unsaturated zone have prevailed for at least the past 2-4 Ma.

Applied Geochemistry↗

USGS2015

Modeling and management of pit lake water chemistry 1: Theory

Pit lakes are permanent hydrologic/landscape features that can result from open pit mining for metals, coal, uranium, diamonds, oil sands, and aggregates. Risks associated with pit lakes include local and regional impacts to water quality and related impacts to aquatic and terrestrial ecosystems. Stakeholders rely on predictive models of water chemistry to prepare for and manage these risks. This paper is the first of a two part series on the modeling and management of pit lakes. Herein, we review approaches that have been used to quantify wall-rock runoff geochemistry, wall-rock leachate geochemistry, pit lake water balance, pit lake limnology (i.e. extent of vertical mixing), and pit lake water quality, and conclude with guidance on the application of models within the mine life cycle. The purpose of this paper is to better prepare stakeholders, including future modelers, mine managers, consultants, permitting agencies, land management agencies, regulators, research scientists, academics, and other interested parties, for the challenges of predicting and managing future pit lakes in un-mined areas.

Applied Geochemistry↗

USGS2014

Acceptability of residential development in a regional landscape: Potential effects on wildlife occupancy patterns

The conversion of natural lands to developed uses may pose the single greatest human threat to global terrestrial biodiversity. Continued human growth and development over the next century will further exacerbate these effects of habitat loss and fragmentation. Natural resource managers are tasked with managing wildlife as a public trust, yet often have little say in land use decisions. Generally speaking, decision makers could benefit from an understanding of what different regulations mean in terms of wildlife distribution. In a previous paper ( Bettigole et al., 2013 ), we surveyed town residents throughout Vermont to measure how respondents feel about a range of development levels within their town boundaries. We estimated the “social carrying capacity for development” – or SK d – for 251 towns in Vermont. SK d provides an estimate of the level of developed land cover classes that town residents deem “acceptable” within their town boundaries. In this paper, we design a framework for linking the town-specific SK d estimates with the wildlife distribution patterns for three wide-ranging mammalian species: American black bear ( Ursus americanus ), fisher ( Martes pennanti ), and bobcat ( Lynx rufus ). We simulated landscape conditions at SK d for each town in Vermont, and then used existing occupancy models for the three target species to spatially map and compare occupancy rates in the baseline year 2000 with occupancy rates at SK d . With nearly 90% of Vermont towns willing to increase developed landcover classes within town boundaries compared to baseline levels, significant state-wide changes in occupancy rates were predicted for all three focal species. Average occupancy rates declined by −15.9% and −3.1% for black bear and bobcats, respectively. Average occupancy rates for fisher increased by 9.0%. This study provides a method for linking development standards within a town with wildlife occurrence. Across towns, the methodology spatially identifies areas that may be at risk of future development, as well as identifying areas where wildlife distribution patterns may face future change as a result of increased human population growth and development.

Biological Conservation↗

USGS2019

Amphibian conservation in the Anthropocene

Research is necessary to identify patterns in nature, to understand how a system functions, and to make predictions about the future state of an ecosystem. Applied research in conservation biology can identify effective strategies to maintain biodiversity, though many papers end with the conclusion that more research is needed. However, more research does not necessarily lead to solutions. We use the ongoing global decline of amphibians as a salient example to highlight limitations in current conservation research, and to focus on finding solutions which are directly relevant for conservation. While research has been conducted since declines were first detected in the 1990s, outside a few specific examples, little progress in conservation has been achieved. We suggest that the case of amphibian declines is relevant to conservation science in general, as the current paradigm for conservation is that management is planned after research is completed; research and management are not effectively (and not directly) connected. This disconnect illustrates the knowledge-action divide which has been identified as a serious deficiency in conservation. Accordingly, we use this introductory paper to the Special Issue (Amphibian conservation in the Anthropocene: Progress and challenges) to describe amphibians as a conservation dilemma, and to make the case for a different, more pragmatic, and more solutions-focused view of conservation research.

Kansas, Oklahoma↗

USGS2005

Geochemistry of sulfate minerals in high- and low-temperature environments: A tribute to Robert O. Rye

This special issue is a tribute to Robert O. Rye, known as "Bob" to most, in light of his highly productive and ongoing career. Almost all of the papers in this issue are derived from topical sessions on sulfate minerals in hydrothermal and low-temperature environments. The sessions, held at the 2000 Geological Society of America meeting in Reno, NV, and sponsored jointly by the Mineralogical Society of America, the Society of Economic Geologists and the Geochemical Society, included 29 oral and 9 poster presentations. The sessions complemented a short course on the crystallography, geochemistry and environmental significance of sulfate minerals, sponsored by the Mineralogical Society of America and the Geochemical Society, which immediately preceded the meeting (Alpers et al., 2000). The 23 papers in this special issue typify the breadth of Bob Rye’s research in this important area of geochemistry.

Chemical Geology↗

USGS2026

The Sedimentary Geochemistry and Paleoenvironments Project Phase 2 data release: An open data resource for the study of Earth's environmental history

Geochemical data from sedimentary rocks are the primary source of information regarding Earth's surface evolution through time, including its air and water envelopes and interactions with life and deep Earth processes. The Sedimentary Geochemistry and Paleoenvironments Project (SGP) is a scientific consortium centered around open data and community-driven development of cyberinfrastructure tools and resources for sedimentary geochemistry and Earth history. Here we describe the SGP Phase 2 data release, which focused on incorporating Paleoproterozoic and Mesoproterozoic (2500–1000 million years ago) data and better accommodating carbonate data. This data release was built through the involvement of >200 researchers worldwide in academia, government, and industry, and provides the largest available public data resource for our user community in the academic fields of geochemistry, sedimentology, tectonics, paleontology, Earth history, and paleoclimate, as well as the petroleum and minerals industries. The dataset now encompasses 126,006 samples and 4,132,371 geochemical analyses. In addition to direct entry by SGP Team Members, we have ingested and incorporated datasets from the Geoscience Australia OZCHEM database, the Alberta Geological Survey, and the Deep-Time Marine Sedimentary Element Database (DM-SED) compilation. This paper details sampling in the Phase 2 dataset with respect to age, geography, lithology, and other geological characteristics, documents access via our search website and API, discusses possible issues and/or biases in the dataset that could impact analyses, describes plans for governance and stewardship of data from Indigenous lands, and serves as the citable reference paper for the data release.

Chemical Geology↗

USGS2012

Review and update of the applications of organic petrology: Part 2, geological and multidisciplinary applications

The present paper is focused on organic petrology applied to unconventional and multidisciplinary investigations and is the second part of a two part review that describes the geological applications and uses of this branch of earth sciences. Therefore, this paper reviews the use of organic petrology in investigations of: (i) ore genesis when organic matter occurs associated with mineralization; (ii) the behavior of organic matter in coal fires (self-heating and self-combustion); (iii) environmental and anthropogenic impacts associated with the management and industrial utilization of coal; (iv) archeology and the nature and geographical provenance of objects of organic nature such as jet, amber, other artifacts and coal from archeological sites; and (v) forensic science connected with criminal behavior or disasters. This second part of the review outlines the most recent research and applications of organic petrology in those fields.

International Journal of Coal Geology↗

USGS2014

The geochemistry of deep-sea coral skeletons: a review of vital effects and applications for palaeoceanography

Deep-sea corals were discovered over a century ago, but it is only over recent years that focused efforts have been made to explore the history of the oceans using the geochemistry of their skeletal remains. They offer a promising archive of past oceanic environments given their global distribution, layered growth patterns, longevity and preservation as well as our ability to date them using radiometric techniques. This paper provides an overview of the current state-of-the-art in terms of geochemical approaches to using deep-sea coral skeletons to explore the history of the ocean. Deep-sea coral skeletons have a wide array of morphologies (e.g. solitary cup corals, branching colonial corals) and materials (calcite, aragonite and proteins). As such their biomineralization strategies are diverse, leading to complex geochemistry within coral skeletons. Notwithstanding these complications, progress has been made on developing methods for reconstructing the oceanographic environment in the past using trace elements and isotopic methods. Promising approaches within certain coral groups include clumped isotopes and Mg/Li for temperature reconstructions, boron isotopes and radiocarbon for carbon cycling, εNd, and radiocarbon for circulation studies and δ 15 N, P/Ca and Ba/Ca for nutrient tracer studies. Likewise there is now a range of techniques for dating deep-sea corals skeletons (e.g. U-series, radiocarbon), and determining their growth rates (e.g. radiocarbon and 210 Pb). Dating studies on historic coral populations in the Atlantic, Southern Ocean and Pacific point to climate and environmental changes being dominant controls on coral populations over millennial and orbital timescales. This paper provides a review of a range of successes and promising approaches. It also highlights areas in which further research would likely provide new insights into biomineralization, palaeoceanography and distribution of past coral populations.

Deep-Sea Research Part II: Topical Studies in Ocea↗

USGS2024

Understanding gaps in early detection of and rapid response to invasive species in the United States: A literature review and bibliometric analysis

While concepts regarding invasive species establishment patterns and eradication possibilities have long been a topic of invasion biology, the specific terminology referring to early detection of and rapid response to (EDRR) invasive species emerged in scientific literature during the early 2000s. Since then, the EDRR approach has expanded to include a suite of detection, planning, and management tools. By conducting a systematic literature review, we attempt to characterize the field of EDRR in the United States and its territories as reflected by publication records. Specifically, we assessed publication data such as the number of publications per year, the most common journals where papers were published, and the relationship between author’s keywords for studies focusing on aquatic and terrestrial habitats. For publications that used invasive species occurrence or abundance data (whether collected for the purposes of the respective publication or acquired from another data source), we manually vetted additional information such as focal taxa, data collection years and locations, sources of other data used, and whether data or code were deposited in open access formats. We also conducted network analyses for the author institutions that coauthored papers together most frequently and for the references most cited by EDRR publications. Overall, we found that silos existed in terms of which author institutions worked together, which existing literature was cited, and which topics were frequently explored. We also found evidence of substantial gaps in data access and use. For example, although a wide variety of data sources for invasive species occurrences are available, these sources were seldom cited by published literature, and newly collected data was not often deposited into invasive species databases or other open-source data repositories. Considering the continued advocation for a centralized national EDRR information system, our study suggests that facilitating access to data, decision support tools, and other informational resources represents a key opportunity for improving EDRR capabilities.

Ecological Informatics↗

USGS2015

Markov decision processes in natural resources management: observability and uncertainty

The breadth and complexity of stochastic decision processes in natural resources presents a challenge to analysts who need to understand and use these approaches. The objective of this paper is to describe a class of decision processes that are germane to natural resources conservation and management, namely Markov decision processes, and to discuss applications and computing algorithms under different conditions of observability and uncertainty. A number of important similarities are developed in the framing and evaluation of different decision processes, which can be useful in their applications in natural resources management. The challenges attendant to partial observability are highlighted, and possible approaches for dealing with it are discussed.

Ecological Modelling↗

USGS2012

Reducing uncertainty about objective functions in adaptive management

This paper extends the uncertainty framework of adaptive management to include uncertainty about the objectives to be used in guiding decisions. Adaptive decision making typically assumes explicit and agreed-upon objectives for management, but allows for uncertainty as to the structure of the decision process that generates change through time. Yet it is not unusual for there to be uncertainty (or disagreement) about objectives, with different stakeholders expressing different views not only about resource responses to management but also about the appropriate management objectives. In this paper I extend the treatment of uncertainty in adaptive management, and describe a stochastic structure for the joint occurrence of uncertainty about objectives as well as models, and show how adaptive decision making and the assessment of post-decision monitoring data can be used to reduce uncertainties of both kinds. Different degrees of association between model and objective uncertainty lead to different patterns of learning about objectives.

Ecological Modelling↗

USGS2024

Advancing knowledge pluralism and cultural benefits in ecosystem services theory and application

Improved consideration of the cultural benefits of ecosystem services (ES) requires attention to knowledge pluralism in addition to value pluralism. Theorists have increasingly argued that meaningful inclusion of cultural benefits of ES requires attention to plural values, beyond the individual, instrumental values associated with ecosystems. However, there has been little engagement around the role of knowledge pluralism as a foundational enabling factor for meaningful consideration of plural values. This paper contributes to a conceptual toolkit for implementation of knowledge pluralism in ES theory and application by (re)conceptualizing ES-knowledge as a knowledge system. This can support personal and collective reflexivity around the role of worldviews embedded in our institutions, and illuminate what is at stake when assumptions about human-nature relationship and well-being remain hidden. Further, by locating benefits-knowledge as a core element of the ES-knowledge-system, we can imagine a greater range of possible cultural-benefits-knowledge-forms and improve our ability to comprehend and convey the plural values of cultural benefits of ES, as they arise across cultural contexts.

Ecosystem Services↗

USGS2024

Opportunities for improved consideration of cultural benefits in environmental decision-making

Many cultural benefits of ecosystem services (ES) are difficult to capture in standard ES assessments. Scholars and practitioners often respond to this gap by seeking to develop new scientific methods to capture and integrate the plural values associated with diverse cultural benefits categories. This increasing emphasis on value pluralism represents an essential step toward recognitional justice within ES theory and practice. However, current approaches continue to rest on the assumption that ES-knowledge is only made available to decision-makers through scientific documentation. As a result, scholars and decision-makers fail to account for the role of knowledge pluralism as a core element of recognitional justice, and a key enabling factor for meaningful consideration of the plural values linked to cultural benefits of ES. In this paper, we contribute to a pluralist theory of cultural-benefits-knowledge, and ES-knowledge more broadly. Using a critical interpretive synthesis of environmental management literature, we conceptualize a wider range of knowledge forms that convey cultural benefits, based on the knowledge-as-practice concept in addition to the knowledge-as-product concept more familiar to Western actors. As part of the synthesis, we explore when and how diverse forms of cultural-benefits-knowledge intersect with decision-making processes, and the value aspects and categories of cultural benefits most frequently conveyed by each form of knowledge. Our synthesizing argument offers a critique of the concept of “ES-knowledge-use,” proposing a shift in focus toward “learning opportunities” that exist across phases of decision-making. We demonstrate that attention to a greater diversity of knowledge forms (knowledge pluralism), and a fuller spectrum of opportunities to integrate them (learning opportunities) can support more meaningful consideration of the plural values associated with cultural benefits of ES (value pluralism). In combination, attention to knowledge pluralism and value pluralism can help bring the ES approach into alignment with environmental justice through the recognition and legitimization of multiple identities, well-beings, and human-nature relationships, as reflected in meaningful consideration of the diverse cultural benefits of ES.

Ecosystem Services↗

USGS2005

Field occurrences of liquefaction-induced features: A primer for engineering geologic analysis of paleoseismic shaking

Discussed in this paper are the factors that control the typical manifestations of liquefaction that are found in continental field settings. The factors are given mainly in terms of the local geologic field situation and the geotechnical properties there. A meaningful interpretation of liquefaction-based data for quantitative analysis of paleoseismic shaking requires understanding of both geologic and geotechnical roles in the mode of ground failure at a specific site. Recommendations are made for the size of the field area that must be searched for liquefaction effects, in order to develop adequate data for engineering geologic/geotechnical analyses of paleoseismicity. The areal extent must be based on an appreciation that the tectonic situation can cause seismically induced liquefaction effects to form in some locales, but not in others nearby, even for a strong earthquake in the region. Our guidelines for the conduct of the field search and preliminary analysis of the data relate to three issues for which liquefaction features are especially useful in answering: Has there been strong Holocene/latest Pleistocene shaking in the region? Where was the tectonic source? And what was the strength of shaking? Understanding of the various factors that control the manifestations of liquefaction effects, which we present in this paper, is essential for developing credible answers to these questions. ?? 2004 Elsvier B.V. All rights reserved.

Engineering Geology↗

USGS2008

Using the Model Coupling Toolkit to couple earth system models

Continued advances in computational resources are providing the opportunity to operate more sophisticated numerical models. Additionally, there is an increasing demand for multidisciplinary studies that include interactions between different physical processes. Therefore there is a strong desire to develop coupled modeling systems that utilize existing models and allow efficient data exchange and model control. The basic system would entail model "1" running on "M" processors and model "2" running on "N" processors, with efficient exchange of model fields at predetermined synchronization intervals. Here we demonstrate two coupled systems: the coupling of the ocean circulation model Regional Ocean Modeling System (ROMS) to the surface wave model Simulating WAves Nearshore (SWAN), and the coupling of ROMS to the atmospheric model Coupled Ocean Atmosphere Prediction System (COAMPS). Both coupled systems use the Model Coupling Toolkit (MCT) as a mechanism for operation control and inter-model distributed memory transfer of model variables. In this paper we describe requirements and other options for model coupling, explain the MCT library, ROMS, SWAN and COAMPS models, methods for grid decomposition and sparse matrix interpolation, and provide an example from each coupled system. Methods presented in this paper are clearly applicable for coupling of other types of models. ?? 2008 Elsevier Ltd. All rights reserved.

Environmental Modelling and Software↗

USGS2016

Modelling with stakeholders - Next generation

This paper updates and builds on ‘Modelling with Stakeholders’ Voinov and Bousquet, 2010 which demonstrated the importance of, and demand for, stakeholder participation in resource and environmental modelling. This position paper returns to the concepts of that publication and reviews the progress made since 2010. A new development is the wide introduction and acceptance of social media and web applications, which dramatically changes the context and scale of stakeholder interactions and participation. Technology advances make it easier to incorporate information in interactive formats via visualization and games to augment participatory experiences. Citizens as stakeholders are increasingly demanding to be engaged in planning decisions that affect them and their communities, at scales from local to global. How people interact with and access models and data is rapidly evolving. In turn, this requires changes in how models are built, packaged, and disseminated: citizens are less in awe of experts and external authorities, and they are increasingly aware of their own capabilities to provide inputs to planning processes, including models. The continued acceleration of environmental degradation and natural resource depletion accompanies these societal changes, even as there is a growing acceptance of the need to transition to alternative, possibly very different, life styles. Substantive transitions cannot occur without significant changes in human behaviour and perceptions. The important and diverse roles that models can play in guiding human behaviour, and in disseminating and increasing societal knowledge, are a feature of stakeholder processes today.

Environmental Modelling and Software↗

USGS2019

Effective modeling for Integrated Water Resource Management: A guide to contextual practices by phases and steps and future opportunities

The effectiveness of Integrated Water Resource Management (IWRM) modeling hinges on the quality of practices employed through the process, starting from early problem definition all the way through to using the model in a way that serves its intended purpose. The adoption and implementation of effective modeling practices need to be guided by a practical understanding of the variety of decisions that modelers make, and the information considered in making these choices. There is still limited documented knowledge on the modeling workflow , and the role of contextual factors in determining this workflow and which practices to employ. This paper attempts to contribute to this knowledge gap by providing systematic guidance of the modeling practices through the phases (Planning, Development, Application, and Perpetuation) and steps that comprise the modeling process, positing questions that should be addressed. Practice-focused guidance helps explain the detailed process of conducting IWRM modeling, including the role of contextual factors in shaping practices. We draw on findings from literature and the authors’ collective experience to articulate what and how contextual factors play out in employing those practices. In order to accelerate our learning about how to improve IWRM modeling, the paper concludes with five key areas for future practice-related research: knowledge sharing, overcoming data limitations, informed stakeholder involvement, social equity and uncertainty management.

Environmental Modelling & Software↗