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USGS2012

Varve calibrated records of carbonate and organic carbon accumulation over the last 2000 years in the Black Sea

Sedimentologic and geochemical studies of box and gravity cores recovered from the Black Sea during the first leg of a multileg international Black Sea expedition in 1988 allow reconstruction of the basinwide Holocene environmental history of the Black Sea. In the deeper parts of the basin, box cores typically recovered a flocculent surface layer (“fluff”), laminated coccolith marls of Unit I (25–45 cm thick), and the upper 5–10 cm of finely laminated, dark‐colored sapropels of Unit II. Fine‐grained, homogeneous mud turbidites are interbedded with Units I and II over much of the basin, but the stratigraphie position of these turbidites differs, from site to site. The deposition of individual turbidites up to 15 cm thick does not appear to have significantly disturbed underlying laminae. Sediment trap deployments in the Black Sea suggest that light and dark laminae couplets represent annual increments of sedimentation (i.e., varves); we have therefore constructed a varve chronology for the sequence in order to correlate and date distinctive sedimentation and paleoenvironmental events. Distinctive groups of laminae in Unit I can be correlated across the entire deeper basin (a distance of more than 1000 km). This implies a remarkable homogeneity in production, accumulation, and preservation of biogenic material over much of the Black Sea during deposition of Unit I. The change from deposition of finely laminated, organic carbon‐rich sapropels (Unit II) to laminated, more calcareous, coccolith‐rich marls (Unit I) is thought to represent the crossing of a salinity threshold for Emiliania huxleyi. The varve chronology sets this change at about 1.63 ka (1633±100 yr B.P.), but the record of magnetic secular variation measured in several cores produces an age estimate of about 2.0 ka for the base of Unit I, or about 1.2 times the varve age. The average of six calibrated accelerator mass spectrometry radiocarbon ages for the base of Unit I is 2.7 ka, or about 1.7 times the varve age. Following the initial change to coccolith‐dominated sedimentation, deposition of sapropel resumed for at least one significant period, 1.56–1.25 ka. Since 1.25 ka, cycles of carbonate deposition with quasi‐decadal periodicities have produced characteristic darker and lighter assemblages of laminae. These cycles may have been climatically driven. Geochemical analyses coupled with the varve ages adopted herein indicate that accumulation rates of carbonate are nearly an order of magnitude higher in Unit I (averaging 35–45 g m −2 yr −1 ) than in sapropelic Unit II. which contains primarily detrital carbonate. The accumulation of lithogenic components in parts of Unit I is only 1.5 times the rate in Unit II. Deepwater organic carbon accumulation rates are somewhat higher in Unit I (3.5–4.5 g m −2 yr −1 ) than in the upper part of Unit II. Organic carbon accumulation rates in Unit I are somewhat antithetic to those of carbonate, and on the basis of this and additional constraints placed by pyrolysis and carbon isotopic analyses of organic material, it appears that terrestrial organic matter is an important component (perhaps >25%) of total organic carbon burial in the basin. Unit I in the western part of the Black Sea has a higher terrestrial organic component and higher accumulation rates of terrigenous clastic material than Unit I in the eastern part. This difference between eastern and western Black Sea is to be expected because of the major rivers that empty into the western Black Sea from eastern Europe, Ukraine, and Russia. Shallow slope sites, but still within euxinic bottom waters, have lower organic carbon accumulation rates and lower pyrolysis hydrogen indices than deepwater basinal sites, suggesting selective resuspension and oxidation of organic matter at basin margins and focusing of organic matter deposition toward the basin center. A comparison of the Black Sea data with those from several open ocean sites with similar water depths showed no significant difference between organic carbon accumulation rates under oxic and anoxic conditions. For a given bulk accumulation rate the organic carbon accumulation rates, normalized to primary productivity, are about the same in both settings.

Global Biogeochemical Cycles↗

USGS2021

Modeling structural mechanics of oyster reef self-organization including environmental constraints and community interactions

Self-organization is a process of establishing and reinforcing local structures through feedbacks between internal population dynamics and external factors. In reef-building systems, substrate is collectively engineered by individuals that also occupy it and compete for space. Reefs are constrained spatially by the physical environment, and by mortality, which reduces production but exposes substrate for recruits. Reef self-organization therefore depends on efficient balancing of production and occupancy of substrate. To examine this, we develop a three-dimensional individual-based model (IBM) of oyster reef mechanics. Shell substrate is grown by individuals as valves, accumulates at the reef level, and degrades following mortality. Single restoration events and subsequent dynamics are simulated for a case study in South Carolina (USA). Variability in model processes is included on recruitment, spatial environmental constraints, and predation, over multiple independent runs and five predator community scenarios. The main goal for this study is to summarize trends in dynamics that are robust across this uncertainty, and from these generate new hypotheses and predictions for future studies. Simulation results demonstrate three phases following restoration: initial transient dynamics with considerable shell loss, followed by growth and saturation of the live population, and then saturation of settlement habitat several years later. Over half of simulations recoup initial shell losses as populations grow, while others continue in decline. The balance between population density, substrate supporting the reef, and exposed surfaces for settlement is mediated by overall population size and size structure, presence of predators, and relative amounts of live individuals and intact dead shells. The efficiency of settlement substrate production improves through time as population size structure becomes more complex, and the population of dead valves accumulates.

Ecological Modelling↗

USGS1998

Walden Pond, Massachusetts: Environmental setting and current investigations

Introduction Walden Pond, in Concord, Massachusetts, is famous among lakes because of its unique social history. Walden was the setting for American naturalist Henry David Thoreau's well-known essay 'Walden; or, Life in the Woods,' first published in 1854. Thoreau lived and wrote at Walden Pond from July 1845 to September 1847. In 'Walden,' Thoreau combined highly admired writing on Transcendental philosophy with pioneering observations of aquatic ecology and physical aspects of limnology, the study of lakes. Because Thoreau also defended so effectively the value of living close to nature in the Walden woods, the pond is considered by many to be the birthplace of the American conservation movement. Visitors come from all over the world to the pond, which has been designated a National Historic Landmark, and its fame has resulted in a major fund drive to preserve the surrounding woods. Walden Pond has no surfacewater inflow or outflow, and much of its ground-water contributing area likely is preserved within the Walden Pond Reservation area (fig. 1). Only 15 miles from Boston, the pond is unusually clear and pristine for an urban-area lake. However, point sources of nutrients near the pond, and a large annual visitor attendance, concentrated during the summer when the swimming beach (fig. 2) is open, may contribute a nutrient load sufficient to change the pond environment. The occurrence of nuisance algal species, a recent beach closing, and an awareness of water-quality problems suffered by other ponds in the region raise concerns about the risk of ecological change at Walden Pond. Despite the role of Walden Pond as a cultural and environmental icon, little is known about the pond's ecological features, such as its internal nutrient cycling or the structure of its food web, nor have consistent measurements been made to determine whether these features are changing or are stable. Production rates of aquatic plants in lakes and ponds naturally undergo a slow increase as plant nutrients, organic matter, and soil are leached and eroded from the surrounding watershed. This process is known as eutrophication. The term 'cultural eutrophication' refers to an accelerated form of the natural process in which extra soil and nutrients are derived from people's use of fertilizer, rerouting of surface drainage, and disposal of domestic and industrial waste. Cultural eutrophication can lead to excessive growth of aquatic plants, pond filling by decayed plants and eroded soils, reduced water clarity, and depletion of dissolved oxygen in deep water with subsequent loss of cold-water fish habitat. In order to document the longterm ecological health of Walden Pond, the U.S. Geological Survey (USGS), working in cooperation with the Massachusetts Department of Environmental Management (MDEM), is investigating factors that could contribute to cultural eutrophication of Walden. Through measurements of mass balance of nutrients and oxygen in the pond's deep water, the investigation will establish a baseline data set on Walden's trophic state, which is a measure of the pond's ability to support plant growth. The baseline data will be used to detect trends and give early warning of trophic changes or trophic response to pond remediation projects. This Fact Sheet provides background information on the environmental setting, limnological features, and cultural eutrophication of Walden Pond, and describes the joint USGS/MDEM study.

Massachusetts↗

USGS1997

The USGS World Energy Program

The world has recently experienced rapid change to market-driven economies and increasing reliance on petroleum supplies from areas of political instability. The interplay of unprecedented growth of the global population, increasing worldwide energy demand, and political instability in two major petroleum exporting regions (the former Soviet Union and the Middle East) requires that the United States maintains a current, reliable, objective assessment of the world's energy resources. The need is compounded by the environmental implications of rapid increases in coal use in the Far East and international pressure on consumption of fossil fuels.

Fact Sheet↗

USGS1990

Recent geophysical and geological research in Antarctica related to the assessment of petroleum resources and potential environmental hazards to their development

During the 6-year negotiation of and adoption of the Convention on the Regulation of Antarctic Mineral Resources Activities on June 2, 1988, various countries have increased their attention to the possibility of exploitation of Antarctica's petroleum resources, which are covered by this treaty. However, there are no known petroleum resources in Antarctica, and scientific information is lacking to adequately assess any undiscovered resources or the possible environmental hazards to their development. Scientific research carried out in Antarctica since the International Geophysical Year (1957-1958) has provided a great deal of information on the geological framework of this ice-covered continent and its margin and has found general indications of the types of hazards that must be considered. Antarctica covers a vast area, and likely supergiant oil fields of the type to be exploited would be tiny (e.g., a few tens of kilometers across) in comparison. Any petroleum resources located in Antarctica will be found by applying the knowledge, techniques, and experience gained developing oil fields in other parts of the world and would, therefore, be other examples of general cases; in contrast, the Antarctic environment and its associated hazards must be considered unique.

Book chapter↗

USGS2015

Geomorphic change in the Limitrophe reach of the Colorado River in response to the 2014 delta pulse flow, United States and Mexico

A pulse of water was released from Morelos Dam into the dry streambed of the Colorado River in its former delta on March 23, 2014. Although small in relation to delta floods of a century ago, this was the first flow to reach the sea in nearly two decades. The pulse flow was significant in that it resulted from an international agreement, Minute 319, which allowed Colorado River water to be used for environmental restoration. Here we present a historical perspective of channel change and the results of geomorphic and sediment transport monitoring during the pulse flow between Yuma, Arizona and San Luis Rio Colorado, Sonora. This reach is known as the Limitrophe, because the river channel is the legal border between the United States and Mexico. Peak discharge of the pulse flow was 120 m3/s at Morelos Dam, but decreased to 71 m3/s at the southern border because of infiltration losses to the dry streambed. In contrast, flood flows in the 1980s and 1990s peaked above 600 m3/s at the southern border, and high flows above 200 m3/s were common. The sustained high flows in the 1980s caused widening and reworking of the river channel downstream through the delta. In the Limitrophe, flooding in 1993 from the Gila River basin dissected the 1980s flood surfaces, and smaller floods in the late 1990s incised the modern “active” channel within these higher surfaces. Field observations show that most geomorphic change during the pulse flow was confined to this pre-pulse, active channel. Relatively little bank erosion was evident, particularly in upstream reaches where vegetation is most dense, but new sandbars formed in areas of flow expansion. Farther downstream, localized bed scour and deposition ranged from 10s of centimeters to more than a meter, and fluvial dunes aggraded the bed in several locations. Measurable suspended-sediment transport occurred throughout the Limitrophe. Sediment concentrations peaked during the rising limb, and suspended sand concentrations suggest deposition in the lower 7 km of the Limitrophe as the channel gradient decreases by an order of magnitude. The pulse flow was small compared to historic floods, and flood magnitudes greater than the 2014 pulse flow are therefore necessary to significantly rework stable geomorphic surfaces or induce channel widening.

Arizona and California↗

USGS2022

Science mission requirements for a globally ranging, riserless drilling vessel for U.S. Scientific Ocean Drilling

Through the collection and analysis of shallow and deep subseafloor sediments, rocks, fluids, and life, scientific ocean drilling has enriched our understanding of the complex Earth system. Among other achievements, scientific ocean drilling has documented the history of Earth’s climate, the waxing and waning of polar ice sheets, the past changes in ocean and atmospheric circulation, the existence and function of microbial life in the subseafloor, the compositional variations in Earth’s crust and underlying mantle, and the physical and chemical processes acting at subduction zones, including those associated with tsunamigenic earthquakes. Over the decades, more than 12,000 articles that depend on analyses of scientific ocean drilling samples and geophysical data have been published, many detailing breakthrough contributions to global knowledge about the Earth system. Approximately 45% of these publications were led by U.S.-affiliated authors (International Ocean Discovery Program Publication Services, 2021). Since the mid-1980s, the workhorse of this multidisciplinary, international research effort has been the riserless D/V JOIDES Resolution, operated by Texas A&M University with funding from the U.S. National Science Foundation (NSF). D/V JOIDES Resolution has conducted the vast majority of scientific ocean drilling expeditions and collected most of the scientific cores over that period, including 82% of the expeditions and 93% of the cores in the last decade alone, despite being one of three platforms that is operated within the International Ocean Discovery Program. However, D/V JOIDES Resolution is approaching the end of its useful life. With a strong commitment to continue scientific ocean drilling beyond the end of the current phase, the community developed a document outlining the research frontiers that should be pursued. Exploring Earth by Scientific Ocean Drilling: 2050 Science Framework (Koppers and Coggon, 2020) describes seven scientific strategic objectives that focus on understanding interconnections within the Earth system and five flagship initiatives that integrate these objectives into long-term research efforts that address issues facing society. Additional elements in the 2050 Science Framework, including STEM education, workforce development, technology development, and innovative applications of data analytics, will advance the goals of scientific ocean drilling. Addressing the 2050 Science Framework also requires building partnerships with allied U.S. and international science programs and strengthening existing ones. To implement a significant portion of the 2050 Science Framework, the U.S. scientific community seeks to lease or acquire a newly built, globally ranging, state-of-the art, riserless drilling vessel. The many and varied technical and human resources requirements for successful accomplishment of scientific and educational goals summarized in this document and described in detail in the 2050 Science Framework require broad community input and careful consideration. Following receipt of NSF’s formal Request for Assistance to the United States Science Support Program (USSSP), the U.S. scientific ocean drilling community conducted a one-year exercise to identify its national scientific needs and priorities in order to determine the Science Mission Requirements (SMRs) presented here. This community effort included: (1) a U.S. community-wide survey to identify the specific operational and technical capabilities critical to addressing science in the 2050 Science Framework; (2) a series of online workshops focusing on critical capabilities identified by the survey; and (3) a large in-person workshop to synthesize the results of the survey and the virtual workshops (Appendix 1). The approach was designed to reach as many participants as possible. Overall, 278 survey responses were received from U.S. community members, representing 104 unique institutions from 39 states and the District of Columbia, and 137 unique individuals participated in the workshops (Appendix 2). The results of this effort comprise two classes of SMRs: Foundational Science Mission Requirements and Primary Science Mission Requirements. Foundational SMRs define minimum criteria for a new riserless drilling vessel that can address significant portions of the 2050 Science Framework. Primary SMRs build upon the Foundational SMRs and will create more robust science opportunities and data collection capabilities, will increase progress in addressing the 2050 Science Framework objectives, and will provide more real-time ship-to-shore interaction to improve science productivity, engagement, and outreach. Modern safety and environmental standards, including meeting standards to access protected waters such as exclusive economic zones, extended continental shelves, or high latitudes, while being cognizant of the vessel’s environmental footprint. Safe and efficient operations in global locations and in water depths from 70 m to 6000+ m, with total drill string length of at least 7000 m. High-quality core and data collection from a range of key subseafloor environments. Advanced heave compensation, dynamic positioning, and drill pipe stability. Modern mud and cement/casing systems. Critical onboard measurements for safety, operational decision-making, documentation of ephemeral properties, mission-specific science, and long-term science goals that extend beyond a single expedition. Designated and appropriate space for sample and data preservation. Highly skilled onboard personnel, including technical staff for curation and core handling; support for safety, time-sensitive, and critical shipboard measurements; computer support; equipment and instrument repair; application support; and data assurance. Primary Science Mission Requirements include: Flexible shipboard space for laboratories and on deck to ensure safe, successful implementation of diverse science objectives and operations. Minimizing contamination of recovered samples. Over-the-side capabilities for science-supporting technology (e.g., remotely operated vehicles, water- column sampling, sediment-water interface sampling). Downhole logging and measurements. Expanded borehole observatory capabilities. Reliable and consistent ship-to-shore communications. NSF’s investment in a new globally ranging, riserless drilling vessel will have a powerful economic multiplier effect, including the infusion of additional science support funds in the United States for training and research, the development of new technologies and tools, and the associated scientific and technical workforce development. The skills and knowledge gained through scientific ocean drilling are translatable to careers in fields such as sustainable energy development (e.g., geothermal and offshore wind), carbon sequestration, data management and cyberinfrastructure, biotechnology, communications, science education, policy, hazard mitigation, and environmental management. The United States is a leader in a well-established and internationally collaborative scientific ocean drilling community. A modern, globally ranging, riserless drilling vessel will allow the United States to expand its leadership position, address broad scientific questions that current capabilities preclude, and cultivate equitable international, multidisciplinary collaborations that will ensure scientific ocean drilling’s future success.

Report↗

USGS2018

Relating cyanobacteria and physicochemical water-quality properties in Willow Creek Lake, Nebraska, 2012–14

Cyanobacteria (also referred to as blue-green algae) are naturally present members of phytoplankton assemblages that may detract from beneficial uses of water because some strains produce cyanotoxins that pose health hazards to people and animals. Cyanobacteria populations observed in Willow Creek Lake during 2012 through 2014 were compared to external nutrient loading from the Willow Creek drainage basin and several other physicochemical properties within the lake, including internal nutrient loading. This report is part of a cooperative study between the U.S. Geological Survey, the Lower Elkhorn Natural Resources District, the Nebraska Department of Environmental Quality, the Nebraska Game and Parks Commission, the Nebraska Department of Natural Resources, the Nebraska Environmental Trust, and the University of Nebraska–Lincoln. Cyanobacteria concentrations were quantified using weekly microcystin sampling, intermittent algal taxonomy, and hourly in-situ phycocyanin measurements. External and internal nutrient loads, lake water physical characteristics, and local meteorological conditions were evaluated as potential causes of cyanobacterial blooms. A water balance approach that estimated Willow Creek Lake inflow and outflow volumes identified Willow Creek as the major inflow and groundwater flux as the major outflow for the lake. Nutrient concentrations from several water sources were quantified and combined with flow volumes to compute nutrient loads during the study period. Surface flows contributed most external nutrients to the lake, whereas lake nutrients were exported during groundwater losses. The main stem of Willow Creek accounted for most nitrate loads to the lake, whereas total Kjeldahl nitrogen, total phosphorus, and phosphate loads to the lake were more evenly distributed between Willow Creek and the North Tributary, a smaller drainage. Sediment core incubations determined internal phosphorus loading was a negligible component of the overall nutrient load to the lake. Cyanobacterial responses were compared to nutrient loads and other external factors that could potentially affect algal growth. A series of univariate comparisons were made by plotting those factors against phycocyanin using biweekly summaries of each and a multivariate model that incorporated seasonality and cumulative nitrate loading. Although the multivariate model only incorporated cumulative nitrate, both nitrogen and phosphorus are likely contributing to cyanobacterial population growth, and management efforts may benefit from the recognition of differences in nutrient loading characteristics between the monitored basins.

Nebraska↗

USGS2026

The Zooplankton International Geospatial (ZIG) dataset: A global repository of spatiotemporal freshwater zooplankton community composition data from lakes and reservoirs to support ecological research

Zooplankton transfer substantial energy in aquatic food webs and are used as indicators of environmental change. Syntheses of zooplankton community dynamics globally require datasets that span a wide range of environmental gradients; however, these datasets are limited due to methodological differences across programs, taxonomic inconsistencies, and a lack of standardized metadata. To reconcile these challenges, we created the Zooplankton International Geospatial (ZIG) dataset, which includes original zooplankton, water physical and chemical variables, and lake morphometric data from 311 inland lakes and reservoirs. ZIG includes waterbodies ranging in size from 0.005 to 82,100 km 2 and spanning broad latitudinal (−47.26 to 64.90) and longitudinal ranges (−165.04 to 176.53). Temporal coverage for individual waterbodies ranges between 1 and 60 yr with sampling frequency ranging from annually to weekly. With its extensive coverage and content, we consider ZIG to be a cornerstone for future investigations of global scale lake biodiversity change.

Limnology & Oceanography - Letters↗

USGS2010

Western Mineral and Environmental Resources Science Center--providing comprehensive earth science for complex societal issues

Minerals in the environment and products manufactured from mineral materials are all around us and we use and come into contact with them every day. They impact our way of life and the health of all that lives. Minerals are critical to the Nation's economy and knowing where future mineral resources will come from is important for sustaining the Nation's economy and national security. The U.S. Geological Survey (USGS) Mineral Resources Program (MRP) provides scientific information for objective resource assessments and unbiased research results on mineral resource potential, production and consumption statistics, as well as environmental consequences of mining. The MRP conducts this research to provide information needed for land planners and decisionmakers about where mineral commodities are known and suspected in the earth's crust and about the environmental consequences of extracting those commodities. As part of the MRP scientists of the Western Mineral and Environmental Resources Science Center (WMERSC or 'Center' herein) coordinate the development of national, geologic, geochemical, geophysical, and mineral-resource databases and the migration of existing databases to standard models and formats that are available to both internal and external users. The unique expertise developed by Center scientists over many decades in response to mineral-resource-related issues is now in great demand to support applications such as public health research and remediation of environmental hazards that result from mining and mining-related activities. Western Mineral and Environmental Resources Science Center Results of WMERSC research provide timely and unbiased analyses of minerals and inorganic materials to (1) improve stewardship of public lands and resources; (2) support national and international economic and security policies; (3) sustain prosperity and improve our quality of life; and (4) protect and improve public health, safety, and environmental quality. The MRP supports approximately 40 USGS research specialists who utilize cooperative agreements with universities, industry, and other governmental agencies to support their collaborative research and information exchange. Scientists of the WMERSC study how and where non-fuel mineral resources form and are concentrated in the earth's crust, where mineral resources might be found in the future, and how mineral materials interact with the environment to affect human and ecosystem health. Natural systems (ecosystems) are complex - our understanding of how ecosystems operate requires collecting and synthesizing large amounts of geologic, geochemical, biologic, hydrologic, and meteorological information. Scientists in the Center strive to understand the interplay of various processes and how they affect the structure, composition, and health of ecosystems. Such understanding, which is then summarized in publicly available reports, is used to address and solve a wide variety of issues that are important to society and the economy. WMERSC scientists have extensive national and international experience in these scientific specialties and capabilities - they have collaborated with many Federal, State, and local agencies; with various private sector organizations; as well as with foreign countries and organizations. Nearly every scientific and societal challenge requires a different combination of scientific skills and capabilities. With their breadth of scientific specialties and capabilities, the scientists of the WMERSC can provide scientifically sound approaches to a wide range of societal challenges and issues. The following sections describe examples of important issues that have been addressed by scientists in the Center, the methods employed, and the relevant conclusions. New directions are inevitable as societal needs change over time. Scientists of the WMERSC have a diverse set of skills and capabilities and are proficient in the collection and integration of

Circular↗

USGS2020

Gene transcript profiling in desert bighorn sheep

Respiratory disease is a key factor affecting the conservation and recovery of bighorn sheep ( Ovis canadensis ) populations. Innovative, minimally invasive tools such as gene transcription–based diagnostics have the potential to improve our understanding of the broad range of factors that can affect the health of wild sheep. Evaluation of transcript levels for genes representative of multiple internal systems enables measurement of physiological responses of individuals as well as populations to environmental stressors such as pathogens, nutritional deficiency, or contaminants. We developed real‐time polymerase chain reaction assays for 14 genes of interest representing systems including inflammation, cell signaling, detoxification, antiviral, antibacterial, or general stress. Initial results from desert bighorn sheep ( O. c. nelsoni ) sampled from the River, Muddy, and Bare mountains as well as from the Pintwater Range, in southern Nevada, USA, indicated unique transcript profiles associated with each population. This initial study provides the framework from which controlled variable or longitudinal studies can be made, thus augmenting the potential to inform management actions in the future.

Nevada↗

USGS2001

Transboundary movement of airborne pollutants — A methodology for integrating spaceborne images and ground based data

The availability of relevant and accurate environmental information is essential for environmental policy-makers. Recent improvements in satellite remote sensing technologies, groundbased monitors, and data access have resulted in the ability to observe and assess major atmospheric and ecological events around the world on a timely basis Each of these monitoring technologies reveals different and useful information, yet rarely are the resulting data sets used together in an integrated manner. The U.S. Environmental Protection Agency (EPA) and the United Nations Environment Programme (UNEP) Global Resource Information Database (GRID) office in Sioux Falls identified an environmental issue of global interest as a test case for applying an integrated approach: the transboundary movement of atmospheric pollutants. Transboundary movement of atmospheric pollutants has ramifications for human and environmental health, as well as economic impacts. As a result, it is the focus of many bilateral, regional, and international policy efforts. A central question with atmospheric pollutant transport is how to monitor pollutant movement and how to merge different monitoring datasets into useful information. Highly visible regional plumes of dust, smoke, and urban haze can be seen with satellite sensors, while ground-based monitoring of air pollutants such as fine particulates, SO2 , and toxics occurs at the local level. Integration of these two kinds of measurements allows the user to remotely observe large environmental effects in many areas of the world, while obtaining more detailed information from ground-based monitors. Hence, the combination of satellite-based sensor data and ground-based monitoring data promotes greater understanding of the movement of pollutants than either data set alone. Combined data sets are important for use by both scientists and international policy-makers. A standard methodology did not exist to guide and encourage integrated use of satellite images and ground-based data to monitor and understand major pollution events, such as air pollution. Thus, a small team was assembled to develop a methodology for the integration of satellite images and ground-based data. First, we conducted a literature and project review covering past and current integrated remote and ground-based data projects, a literature search of published work, and a search of data sets and technologies that could be used in a combined form. Second, based on this search and documentation, a general methodology was developed for using integrated spaceborne and ground-based data sets, intended as a guide for general scientists and policy-makers. Third, we found an existing project that was willing to be a pilot for testing the methodology: a U.S. EPANOAA project that was using aerial and ground-based sampling to learn more about the airborne sources of mercury deposition in the Florida Everglades. This document presents the results of the literature and project review, the complete methodology, and the outcome of the Florida Everglades pilot project.

Report↗

USGS2017

Direct and indirect controls on organic matter decomposition in four coastal wetland communities along a landscape salinity gradient

Coastal wetlands store more carbon than most ecosystems globally. As sea level rises, changes in flooding and salinity will potentially impact ecological functions, such as organic matter decomposition, that influence carbon storage. However, little is known about the mechanisms that control organic matter loss in coastal wetlands at the landscape scale. As sea level rises, how will the shift from fresh to salt-tolerant plant communities impact organic matter decomposition? Do long-term, plant-mediated, effects of sea-level rise differ from direct effects of elevated salinity and flooding? We identified internal and external factors that regulated indirect and direct pathways of sea-level rise impacts, respectively, along a landscape-scale salinity gradient that incorporated changes in wetland type (fresh, oligohaline, mesohaline and polyhaline marshes). We found that indirect and direct impacts of sea-level rise had opposing effects on organic matter decomposition. Salinity had an indirect effect on litter decomposition that was mediated through litter quality. Despite significant variation in environmental conditions along the landscape gradient, the best predictors of above- and below-ground litter decomposition were internal drivers, initial litter nitrogen content and initial litter lignin content respectively. Litter decay constants were greatest in the oligohaline marsh and declined with increasing salinity, and the fraction of litter remaining (asymptote) was greatest in the mesohaline marsh. In contrast, direct effects of salinity and flooding were positive. External drivers, salinity and flooding, stimulated cellulytic activity, which was highest in the polyhaline marsh. Synthesis . Our results indicate that as sea level rises, initial direct effects of salinity will stimulate decay of labile carbon, but over time as plant communities shift from fresh to polyhaline marsh, litter decay will decline, yielding greater potential for long-term carbon storage. These findings highlight the importance of quantifying carbon loss at multiple temporal scales, not only in coastal wetlands but also in other ecosystems where plant-mediated responses to climate change will have significant impacts on carbon cycling.

Journal of Ecology↗

USGS2011

Construction of shipping channels in the Detroit River: History and environmental consequences

The Detroit River is one of the most biologically diverse areas in the Great Lakes basin. It has been an important international shipping route since the 1820s and is one of the busiest navigation centers in the United States. Historically, it supported one of the most profitable Lake Whitefish (Coregonus clupeaformis) commercial fisheries in the Great Lakes. Since 1874, the lower Detroit River has been systematically and extensively modified, by construction of deepwater channels, to facilitate commercial shipping. Large-scale dredging, disposal of dredge spoils, and construction of water-level compensating works has greatly altered channel morphology and flow dynamics of the river, disrupting ecological function and fishery productivity of the river and influencing Great Lakes water levels. From 1874 to 1968, major construction projects created 96.5 kilometers (60 miles) of shipping channels, removed over 46,200,000 m 3 of material, covered 4,050 hectares (40.5 square kilometers) of river bottom with dredge spoils, and built 85 hectares of above-waterline compensating works at a total cost of US$283 million. Interest by industries and government agencies to develop the river further for shipping is high and increasing. Historically, as environmental protection agencies were created, construction impacts on natural resources were increasingly addressed during the planning process and, in some cases, assessments of these impacts greatly altered or halted proposed construction projects. Careful planning of future shipping-channel construction and maintenance projects, including a thorough analysis of the expected environmental impacts, could greatly reduce financial costs and ecological damages as compared to past shipping-channel construction projects.

Michigan↗

USGS2007

Proceedings for a workshop on deposit modeling, mineral resource assessment, and their role in sustainable development

The world's use of nonfuel mineral resources continues to increase to support a growing population and increasing standards of living. The ability to meet this increasing demand is affected especially by concerns about possible environmental degradation associated with minerals production and by competing land uses. What information does the world need to support global minerals development in a sustainable way? Informed planning and decisions concerning sustainability and future mineral resource supply require a long–term perspective and an integrated approach to resource, land use, economic, and environmental management worldwide. Such perspective and approach require unbiased information on the global distribution of identified and especially undiscovered resources, the economic and political factors influencing their development, and the potential environmental consequences of their exploitation. The U.S. Geological Survey and the former Deposit Modeling Program of the International Union of Geological Sciences (IUGS) of the United Nations Educational, Scientific and Cultural Organization (UNESCO) sponsored a workshop on "Deposit Modeling, Mineral Resource Assessment, and Their Role in Sustainable Development" at the 31st International Geological Congress (IGC) in Rio de Janeiro, Brazil, on August 18–19, 2000. The purpose of the workshop was to review the state-of-the-art in mineral deposit modeling and resource assessment and to examine the role of global assessments of nonfuel mineral resources in sustainable development. The workshop addressed questions such as the following: Which of the available mineral deposit models and assessment methods are best suited for predicting the locations, deposit types, and amounts of undiscovered nonfuel mineral resources remaining in the world? What is the availability of global geologic, mineral deposit, and mineral exploration information? How can mineral resource assessments be used to address economic and environmental issues? Presentations included overviews of assessment methods applied in previous national and other small-scale assessments of large regions and of the resulting assessment products and their uses. Twenty-seven people from Canada, China, Finland, Germany, Japan, Peru, Slovenia, South Africa, United States, and Venezuela participated in the 2-day post-Congress workshop. The attendees represented academia, government, environmental organizations, and the mining industry.

Circular↗

USGS2013

Foraging area fidelity for Kemp's ridleys in the Gulf of Mexico

For many marine species, locations of key foraging areas are not well defined. We used satellite telemetry and switching state-space modeling (SSM) to identify distinct foraging areas used by Kemp's ridley turtles ( Lepidochelys kempii ) tagged after nesting during 1998–2011 at Padre Island National Seashore, Texas, USA (PAIS; N = 22), and Rancho Nuevo, Tamaulipas, Mexico (RN; N = 9). Overall, turtles traveled a mean distance of 793.1 km (±347.8 SD) to foraging sites, where 24 of 31 turtles showed foraging area fidelity (FAF) over time (N = 22 in USA, N = 2 in Mexico). Multiple turtles foraged along their migratory route, prior to arrival at their "final" foraging sites. We identified new foraging "hotspots" where adult female Kemp's ridley turtles spent 44% of their time during tracking (i.e., 2641/6009 tracking days in foraging mode). Nearshore Gulf of Mexico waters served as foraging habitat for all turtles tracked in this study; final foraging sites were located in water <68 m deep and a mean distance of 33.2 km (±25.3 SD) from the nearest mainland coast. Distance to release site, distance to mainland shore, annual mean sea surface temperature, bathymetry, and net primary production were significant predictors of sites where turtles spent large numbers of days in foraging mode. Spatial similarity of particular foraging sites selected by different turtles over the 13-year tracking period indicates that these areas represent critical foraging habitat, particularly in waters off Louisiana. Furthermore, the wide distribution of foraging sites indicates that a foraging corridor exists for Kemp's ridleys in the Gulf. Our results highlight the need for further study of environmental and bathymetric components of foraging sites and prey resources contained therein, as well as international cooperation to protect essential at-sea foraging habitats for this imperiled species.

Ecology and Evolution↗

USGS2022

Workshops report for mesophotic and deep benthic community fish, mobile invertebrates, sessile invertebrates and infauna

Two workshops with subject matter experts in the appropriate fields, were held in November and December 2021 to elicit guidance and feedback from the broader mesophotic and deep benthic scientific community. These workshops focused on best practices/approaches and identifying data gaps relative to habitat assessment and evaluation goals of the Mesophotic and Deep Benthic Community (MDBC) restoration portfolio. The first workshop was a combined effort of the Habitat Assessment and Evaluation (HAE) Project Team and the Deepwater Horizon (DWH) Program. Industrial Economics, Inc. (IEc) provided extensive workshop planning, organizing, execution, and facilitation support during all stages of the workshop. Based on a questionnaire sent to scientists in August, 2021, the workshop focused on fish and mobile invertebrate habitat associations, abundance trends, community metrics, and food web functionality. Topical presentations and discussions focused not only on demersal fish and mobile invertebrates that are directly associated with mesophotic and deep benthic habitats, but also considered water column species and communities that benefit from these habitats more broadly. The second workshop, intended to complement the first workshop, focused on identifying best practices and critical information gaps for key community metrics, larval dispersal modeling, connectivity, effects and variability of environmental parameters, and recovery trajectories of corals, infauna, and other sessile invertebrates. Through literature review, internal HAE scientists considered these topics to be critical for restoration success. Products from the literature review included topical summaries (see Appendix B) that summarized the current state-of-the-science and provided the framework for the workshop. Information generated from the workshops will assist the MDBC HAE Project, and more broadly the DWH Program, identify data gaps and develop a suite of best practices for restoration activities.

DWH MDBC Summary Report↗

USGS2003

Maps showing geology, oil and gas fields, and geologic provinces of the Arctic

Introduction This CD-ROM was compiled according to the methodology developed by the U.S. Geological Survey's World Energy Project . The geologic map of the Arctic was compiled and synthesized from the Circumpolar Geological Map of the Arctic, by Okulitch A.V., Lopatin B.G., and Jackson H.R., scale 1:6,000,000, published by the Geological Survey of Canada in 1989 (see References ). Specific details of the data sources are given in the metadata files on this CD-ROM. Map units were kept as close as possible to original map (more than 100 unique values). These Arctic maps were compiled using Environmental Systems Research Institute Inc. (ESRI) ARC/INFO software. Political boundaries and cartographic representations on this map are shown (with permission) from ESRI's ArcWorld 1:3M digital coverage. They have no political significance and are displayed as general reference only. Portions of this database covering the coastline, rivers and country boundaries contain proprietary property of ESRI. (© 1992 and 1996, Environmental Systems Research Institute Inc. All rights reserved. The bathymetric data were derived from the International Bathymetric Chart of the Arctic Ocean (IBCAO) which was downloaded from the NOAA web site. Oil and gas centerpoints were derived from Probe 4.0 database - proprietary property of Petroleum Information/Dwights LLC d/b/a/IHS Energy Group. Specific details of the data sources and map compilation are given in the metadata files on this CD-ROM.

Open-File Report↗