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At least 325 records · Page 18Linked to original sources
USGS2016

Effects of salinity and flooding on post-hurricane regeneration potential in coastal wetland vegetation

PREMISE OF THE STUDY: The nature of regeneration dynamics after hurricane flooding and salinity intrusion may play an important role in shaping coastal vegetation patterns. METHODS: The regeneration potentials of coastal species, types and gradients (wetland types from seaward to landward) were studied on the Delmarva Peninsula after Hurricane Sandy using seed bank assays to examine responses to various water regimes (unflooded and flooded to 8 cm) and salinity levels (0, 1, and 5 ppt). Seed bank responses to treatments were compared using a generalized linear models approach. Species relationships to treatment and geographical variables were explored using nonmetric multidimensional scaling. KEY RESULTS: Flooding and salinity treatments affected species richness even at low salinity levels (1 and 5 ppt). Maritime forest was especially intolerant of salinity intrusion so that species richness was much higher in unflooded and low salinity conditions, despite the proximity of maritime forest to saltmarsh along the coastal gradient. Other vegetation types were also affected, with potential regeneration of these species affected in various ways by flooding and salinity, suggesting relationships to post-hurricane environment and geographic position. CONCLUSIONS: Seed germination and subsequent seedling growth in coastal wetlands may in some cases be affected by salinity intrusion events even at low salinity levels (1 and 5 ppt). These results indicate that the potential is great for hurricanes to shift vegetation type in sensitive wetland types (e.g., maritime forest) if post-hurricane environments do not support the regeneration of extent vegetation.

Delmarva Peninsula↗
USGS1983

Land resource information needs of county government : a case study in Larimer County, Colorado

My two colleagues on the study team, Rex Burns of the Larimer County Planning Department, and Glenn McCarty of the Fort Collins office of the Soil Conservation Service, contributed substantially to this report; many of their written words have found their way directly into the text. Jill O'Gara later replaced Rex Burns as the Larimer County coordinator in the study's final stages. John Rold, Colorado State Geologist, assisted in coordinating our efforts at the beginning of this study. Lou Campbell, State Cartographer, gave valuable advice and assistance throughout the effort. Wallace Hansen and James Blakey of the USGS Geologic and Water Resources Divisions, respectively, read the final manuscript and helped in many other ways. Joanna Trolinger served as research assistant and manuscript typist. Many others in the USGS, SCS, and other organizations helped in supplying information and advice. Tom Bates, then Chairman of the USGS Central Region Earth Science Applications Task Force, was the originator of the study, leader of the USGS participation effort, and guiding inspiration throughout. The study was carried out in association with the Program on Environment and Behavior, Institute of Behavioral Science, University of Colorado, Boulder.

Open-File Report↗
USGS2016

Using an interlaboratory study to revise methods for conducting 10-d to 42-d water or sediment toxicity tests with Hyalella azteca

Studies have been conducted to refine US Environmental Protection Agency, ASTM International, and Environment Canada standard methods for conducting 42-d reproduction tests with Hyalella azteca in water or in sediment. Modifications to the H. azteca method include better-defined ionic composition requirements for exposure water (i.e., >15 mg/L of chloride and >0.02 mg/L of bromide) and improved survival, growth, and reproduction with alternate diets provided as increased rations over time in water-only or whole-sediment toxicity tests. A total of 24 laboratories volunteered to participate in the present interlaboratory study evaluating the performance of H. azteca in 42-d studies in control sand or control sediment using the refined methods. Improved growth and reproduction of H. azteca was observed with 2 alternate diets of 1) ramped diatoms ( Thalassiosira weissflogii ) + ramped Tetramin or 2) yeast–cerophyll–trout chow (YCT) + ramped Tetramin, especially when compared with results from the traditional diet of 1.8 mg YCT/d. Laboratories were able to meet proposed test acceptability criteria and in most cases had lower variation in growth or reproduction compared with previous interlaboratory studies using the traditional YCT diet. Laboratory success in conducting 42-d H. azteca exposures benefited from adherence to several key requirements of the detailed testing, culturing, and handling methods. Results from the present interlaboratory study are being used to help revise standard methods for conducting 10-d to 42-d water or sediment toxicity exposures with H. azteca .

Environmental Toxicology and Chemistry↗
USGS2005

Optimization of an acoustic telemetry array for detecting transmitter-implanted fish

The development of miniature acoustic transmitters and economical, robust automated receivers has enabled researchers to study the movement patterns and survival of teleosts in estuarine and ocean environments, including many species and age-classes that were previously considered too small for implantation. During 2001-2003, we optimized a receiver mooring system to minimize gear and data loss in areas where current action or wave action and acoustic noise are high. In addition, we conducted extensive tests to determine (1) the performance of a transmitter and receiver (Vemco, Ltd.) that are widely used, particularly in North America and Europe and (2) the optimal placement of receivers for recording the passage of fish past a point in a linear-flow environment. Our results suggest that in most locations the mooring system performs well with little loss of data; however, boat traffic remains a concern due to entanglement with the mooring system. We also found that the reception efficiency of the receivers depends largely on the method and location of deployment. In many cases, we observed a range of 0-100% reception efficiency (the percentage of known transmissions that are detected while the receiver is within range of the transmitter) when using a conventional method of mooring. The efficiency was improved by removal of the mounting bar and obstructions from the mooring line.

Idaho, Oregon, Washington↗
USGS2008

The Global Flows of Metals and Minerals

This paper provides a preliminary review of the trends in worldwide metals and industrial minerals production and consumption based on newly developed global metals and minerals Material Flow Accounts (MFA). The MFA developed encompass data on extraction and consumption for 25 metal and mineral commodities, on a country-by-country and year-by-year basis, for the period 1970 to 2004. The data-base, jointly developed by the authors, resides with the U.S. Geological Survey (USGS) as individual commodity Excel workbooks and within a Filemaker data management system for use in analysis. Numerous national MFA have been developed to provide information on the industrial metabolism of individual countries. These MFA include material flows associated with the four commodity categories of goods that are inputs to a country's economy, agriculture, forestry, metals and minerals, and nonrenewable organic material. In some cases, the material flows associated with the creation and maintenance of the built infrastructure (such as houses, buildings, roads, airports, dams, and so forth) were also examined. The creation of global metals and industrial minerals flows is viewed as a first step in the creation of comprehensive global MFA documenting the historical and current flows of all of the four categories of physical goods that support world economies. Metals and minerals represent a major category of nonrenewable resources that humans extract from and return to the natural ecosystem. As human populations and economies have increased, metals and industrial minerals use has increased concomitantly. This dramatic growth in metals and minerals use has serious implications for both the availability of future resources and the health of the environment, which is affected by the outputs associated with their use. This paper provides an overview of a number of the trends observed by examining the database and suggests areas for future study.

Open-File Report↗
USGS2019

Complexities, context, and new information about the Elwha River

Recently, Hand et al. (2018) discussed the socio- ecological complexities surround-ing natural resource policy, science, and management in the Columbia River Basin, using a case study of dam removal on the Elwha River in Washington State (WebFigure 1a). We feel compelled to provide additional historical context and correct some of the information provided by Hand et al. about the Elwha. The his-toric removals of the two Elwha River dams – a long- anticipated project that was decades in the making – have been touted by some as an environmental success story following the project’s completion in 2014. As with any complex endeavor, critical analyses and lessons learned continue to emerge, and will likely benefit future projects.

Washington↗
USGS2022

Modeling the dynamics of lahars that originate as landslides on the west side of Mount Rainier, Washington

Large lahars pose substantial threats to people and property downstream from Mount Rainier volcano in Washington State. Geologic evidence indicates that these threats exist even during the absence of volcanic activity and that the threats are highest in the densely populated Puyallup and Nisqually River valleys on the west side of the volcano. However, the precise character of these threats can be difficult to anticipate. To help predict depths and rates of possible lahar inundation in the area, this report presents the results of simulations of hypothetical future lahars that originate high on the west side of Mount Rainier and travel downstream into the Puyallup and Nisqually River valleys. Many of the results portrayed as still images in the figures of this report are also available as animated files that can be accessed at the web address provided in the figure captions. We simulated eight scenarios, including worst-case scenarios in which the simulated lahars are similar in size and mobility to the approximately 260 million cubic meter (Mm 3 ; 340 million cubic yard) Electron Mudflow lahar that descended from Mount Rainier and inundated the Puyallup River valley about 500 years ago. The other six scenarios place the worst-case scenarios in perspective by simulating lahars that originate from the same source areas but have smaller volumes or lesser mobilities. We perform our simulations using an open-source software package that we developed called D-Claw. The numerical model composing the kernel of D-Claw solves a system of five hyperbolic partial differential equations that describe the depth-averaged dynamics of static or flowing grain-fluid mixtures interacting with three-dimensional topography. In D-Claw, the volume fraction occupied by solid grains is a dependent variable that can freely evolve, enabling simulation of landslide liquefaction and of lahar interaction with static bodies of water. The latter feature facilitates a seamless simulation of a lahar in the Nisqually River valley entering Alder Lake reservoir. In the event of an approximately 260 Mm 3 high-mobility lahar originating on the west side of Mount Rainier, our results point to two areas of pronounced hazard. One area, comprising the densely populated lowlands of Orting, Washington, and environs, could be inundated by lahars originating from either the Sunset Amphitheater or Tahoma Glacier headwall areas. In the worst-case scenario we consider for the Orting lowlands, which involves a 260 Mm 3 high-mobility lahar originating from a landslide in the Sunset Amphitheater, a flow front approximately 4 meters deep and traveling about 4 meters per second reaches the Orting lowlands about 1 hour after the onset of slope failure. After passing through the Orting lowlands, the simulated lahar slows down and comes to rest in the valleys surrounding Sumner and Puyallup. A second area of pronounced hazard is the stretch of the Nisqually River valley beginning in Mount Rainier National Park and extending downstream to Alder Lake reservoir and Alder Dam. This area would be substantially affected in the worst-case scenario that involves a 260 Mm 3 high-mobility lahar originating from the Tahoma Glacier headwall area—the locality identified by a previous study as the sector of Mount Rainier most prone to large-scale gravitational collapse. The simulated lahar passes through the area of Ashford, Washington, within about 20 minutes of the onset of slope failure and reaches the head of Alder Lake within about 50 minutes. The lahar ultimately displaces enough reservoir water to cause overtopping of the 100 meter (330 foot) tall Alder Dam, but consequences of such dam overtopping are not addressed in this report.

Washington↗
USGS2008

MGS-TES thermal inertia study of the Arsia Mons Caldera

Temperatures of the Arsia Mons caldera floor and two nearby control areas were obtained by the Mars Global Surveyor (MGS) Thermal Emission Spectrometer (TES). These observations revealed that the Arsia Mons caldera floor exhibits thermal behavior different from the surrounding Tharsis region when compared with thermal models. Our technique compares modeled and observed data to determine best fit values of thermal inertia, layer depth, and albedo. Best fit modeled values are accurate in the two control regions, but those in the Arsia Mons' caldera are consistently either up to 15 K warmer than afternoon observations, or have albedo values that are more than two standard deviations higher than the observed mean. Models of both homogeneous and layered (such as dust over bedrock) cases were compared, with layered-cases indicating a surface layer at least thick enough to insulate itself from diurnal effects of an underlying substrate material. Because best fit models of the caldera floor poorly match observations, it is likely that the caldera floor experiences some physical process not incorporated into our thermal model. Even on Mars, Arsia Mons is an extreme environment where CO2 condenses upon the caldera floor every night, diurnal temperatures range each day by a factor of nearly 2, and annual average atmospheric pressure is only around one millibar. Here, we explore several possibilities that may explain the poor modeled fits to caldera floor and conclude that temperature dependent thermal conductivity may cause thermal inertia to vary diurnally, and this effect may be exaggerated by presence of water-ice clouds, which occur frequently above Arsia Mons.

Journal of Geophysical Research E: Planets↗
USGS2016

Unmanned aircraft systems in wildlife research: Current and future applications of a transformative technology

Unmanned aircraft systems (UAS) – also called unmanned aerial vehicles (UAVs) or drones – are an emerging tool that may provide a safer, more cost-effective, and quieter alternative to traditional research methods. We review examples where UAS have been used to document wildlife abundance, behavior, and habitat, and illustrate the strengths and weaknesses of this technology with two case studies. We summarize research on behavioral responses of wildlife to UAS, and discuss the need to understand how recreational and commercial applications of this technology could disturb certain species. Currently, the widespread implementation of UAS by scientists is limited by flight range, regulatory frameworks, and a lack of validation. UAS are most effective when used to examine smaller areas close to their launch sites, whereas manned aircraft are recommended for surveying greater distances. The growing demand for UAS in research and industry is driving rapid regulatory and technological progress, which in turn will make them more accessible and effective as analytical tools.

Frontiers in Ecology and the Environment↗
USGS2019

Social–ecological mismatches create conservation challenges in introduced species management

Introduced species can have important effects on the component species and processes of native ecosystems. However, effective introduced species management can be complicated by technical and social challenges. We identify “social–ecological mismatches” (that is, differences between the scales and functioning of interacting social and ecological systems) as one such challenge. We present three case studies in which mismatches between the organization and functioning of key social and ecological systems have contributed to controversies and debates surrounding introduced species management and policy. We identify three common issues: social systems and cultures may adapt to a new species’ arrival at a different rate than ecosystems; ecological impacts can arise at one spatial scale while social impacts occur at another; and the effects of introduced species can spread widely, whereas management actions are constrained by organizational and/or political boundaries. We propose strategies for collaborative knowledge building and adaptive management that may help address these challenges.

Frontiers in Ecology and the Environment↗
USGS2007

Paleoecology and ecosystem restoration: Case studies from Chesapeake Bay and the Florida Everglades

Climate extremes that cause droughts, floods, or large temperature fluctuations can complicate ecosystem restoration efforts focused on local and regional human disturbance. Restoration targets are often based primarily on monitoring data and modeling simulations, which provide information on species' short-term response to disturbance and environmental variables. Consequently, the targets may be unsustainable under the spectrum of natural variability inherent in the system or under future climate change. Increasingly, ecologists and restoration planners recognize the value of the long temporal perspective provided by paleoecological data. Advances in paleoclimatology, including better climate proxy methods and temporal resolution, contribute to our understanding of ecosystem response to anthropogenic and climatic forcing at all time scales. We highlight paleoecological research in the Chesapeake Bay and the Florida Everglades and summarize the resulting contributions to restoration planning. Integration of paleoecological, historic, monitoring, and modeling efforts will lead to the development of sustainable, adaptive management strategies for ecosystem restoration.

Delaware, Florida, Maryland, New York, Pennsylvani↗
USGS2012

Lead and strontium isotopes and related trace elements as genetic tracers in the Upper Cenozoic rhyolite-basalt association of the Yellowstone Plateau volcanic field

Supported by various field geologic and petrologic data, the contents of Pb, U, Th, Rb, and Sr and the isotopic compositions of Pb and Sr for upper Cenozoic volcanic rocks of the Yellowstone Plateau volcanic field are consistent with the hypothesis of derivation of the basaltic and rhyolitic magmas by partial melting of distinct source regions in the upper mantle and lower crust, respectively. All the basalt samples analyzed but one have systematically lower values of 207 Pb/ 204 Pb and 87 Sr/ 86 Sr than the rhyolites. The values of 206 Pb/ 204 Pb are smaller, and 87 Sr/ 86 Sr are mostly larger than known values in oceanic basalts. In all but one case, the values of 207 Pb/ 204 Pb are higher than expected from an extrapolation of known values in oceanic basalts to less radiogenic values of 206 Pb/ 204 Pb. Because there are no xenoliths, phenocrysts are only moderate to sparse in abundance, REE patterns are low and flat at the radiogenic end of lead isotopic compositions, several values of Rb/Sr are low, and 80% of the basalt samples form a well-developed secondary isochron separate from the rhyolites, we favor an interpretation for basalt genesis wherein isotopic signatures of most mafic magmas were attained in a continental ‘keel’ of mantlelike character about 2.6 b.y. old or somewhat older attached to the crust, and these signatures were unaltered by magma passage through the crust. At the very least, the current data continue to cast serious doubt as to the inevitability of crustal contamination for basaltic magma intruding the continental environment and postulate that much can be learned about the mantle under continents through the study of continental basalts. One basalt unit with an unusually low value of 207 Pb/ 204 Pb and an 87 Ar/ 86 Ar less than 0.704 may represent subcontinental ‘keel’-derived magma that rose unaltered to the surface. Our data also are not consistent with formation of this rhyolite-basalt association primarily by such processes as crystal fractionation, separation of immiscible silicate liquids from a common parental magma, or fractional melting of a homogeneous source. Rather as a conceptual model, we envision large mafic intrusions to have been injected into the lower crust resulting in rhyolite generation through partial anatexis of the adjacent wall rocks which probably had a 206 Pb/ 204 Pb < 17 and 87 Sr/ 86 Sr > 0.709; a model that has much in common with that proposed by Holmes (1931). All the other hypotheses listed have the necessary added complication that either the basalt or the rhyolite or both become contaminated after the two magma types separated, have problems accounting for the lack of igneous rocks of intermediate compositions or production of such large volumes of rhyolitic material (∼5000 km 3 ), and fail to explain why rhyolitic magma is not a more common occurrence in the ocean basin. We appeal to bouyancy of rhyolites to generate a barrier for basalt magma migration and account for the great preponderance of rhyolite relative to basalt at the surface. Furthermore, the complex isotopic picture in the rhyolites indicates that many of these magmas interacted with the upper crustal geologic units that they traversed. The interactions involved diverse processes, probably including reacton with hydrothermal fluids or hydrothermally altered rocks at high levels as well as by contamination with Phanerozoic sedimentary and Precambrian crystalline rocks at deeper levels. At the very least, we feel our study adds a cautionary note to the currently increasingly popular hypothesis that differentiation of basalt or gabbro magmas to rhyolite or granite (as distinct from tonalite or dacite) is a common occurrence and is therefore an important continential building process. Models for formation of rhyolite and granite predominantly by reworking of crust (anatexis) must still be considered. The primitive Archean mantle of the region was characterized by higher Rb/Sr, U/Pb, and Th/U values than are typical of modern suboceanic mantle. The mantle residuum within the continental subcrustal lithosperic ‘keel’ that resulted from the Archean crustal differentiation event probably was depleted in Rb/Sr and U/Pb, and the crust was correspondingly enriched in these ratios. The crust probably was further differentiated by an Archean high-grade metamorphism, during or after the primary event, into a granulitic lower crust depleted in U/Pb and Rb/Sr and a lower-grade upper crust enriched in these ratios.

Journal of Geophysical Research Solid Earth↗
USGS2010

A methodology for ecosystem-scale modeling of selenium

The main route of exposure for selenium (Se) is dietary, yet regulations lack biologically based protocols for evaluations of risk. We propose here an ecosystem-scale model that conceptualizes and quantifies the variables that determinehow Se is processed from water through diet to predators. This approach uses biogeochemical and physiological factors from laboratory and field studies and considers loading, speciation, transformation to particulate material, bioavailability, bioaccumulation in invertebrates, and trophic transfer to predators. Validation of the model is through data sets from 29 historic and recent field case studies of Se-exposed sites. The model links Se concentrations across media (water, particulate, tissue of different food web species). It can be used to forecast toxicity under different management or regulatory proposals or as a methodology for translating a fish-tissue (or other predator tissue) Se concentration guideline to a dissolved Se concentration. The model illustrates some critical aspects of implementing a tissue criterion: 1) the choice of fish species determines the food web through which Se should be modeled, 2) the choice of food web is critical because the particulate material to prey kinetics of bioaccumulation differs widely among invertebrates, 3) the characterization of the type and phase of particulate material is important to quantifying Se exposure to prey through the base of the food web, and 4) the metric describing partitioning between particulate material and dissolved Se concentrations allows determination of a site-specific dissolved Se concentration that would be responsible for that fish body burden in the specific environment. The linked approach illustrates that environmentally safe dissolved Se concentrations will differ among ecosystems depending on the ecological pathways and biogeochemical conditions in that system. Uncertainties and model sensitivities can be directly illustrated by varying exposure scenarios based on site-specific knowledge. The model can also be used to facilitate site-specific regulation and to present generic comparisons to illustrate limitations imposed by ecosystem setting and inhabitants. Used optimally, the model provides a tool for framing a site-specific ecological problem or occurrence of Se exposure, quantify exposure within that ecosystem, and narrow uncertainties abouthowto protect it by understanding the specifics of the underlying system ecology, biogeochemistry, and hydrology.

Integrated Environmental Assessment and Management↗
USGS2023

Nearshore ecosystems in the Gulf of Alaska

Nearshore ecosystem monitoring in western Prince William Sound, Kenai Fjords National Park, Kachemak Bay, and Katmai National Park and Preserve has been conducted as a single Nearshore Component of the Gulf Watch Alaska program over the past five years (2017-2021). This program builds on the previous five years and continues, in many cases, decades of preceding research and monitoring. During the 2017-2021 period of Gulf Watch Alaska, we successfully collected data on more than 200 nearshore metrics across all regions. These metrics were explicitly selected because of their value as trophically-connected features that offer insights into causes of changes through bottom-up and top-down forces within the nearshore food web. During these past 5 years, this study design has been applied to documenting and understanding several perturbations, including the Pacific Marine Heatwave and loss of sea stars due to sea star wasting. Continued monitoring will allow for a better understanding of change in nearshore ecosystems across the Gulf of Alaska and the status of spill injured resources, including greater perspective on oil spill effects and recovery relative to other types of perturbations. This information will be critical for anticipating and responding to ongoing and future changes in the region, as well as providing data for understanding global-scale variation in marine environments.

Alaska↗
USGS2013

Estimating irrigation water demand using an improved method and optimizing reservoir operation for water supply and hydropower generation: a case study of the Xinfengjiang reservoir in southern China

The ever-increasing demand for water due to growth of population and socioeconomic development in the past several decades has posed a worldwide threat to water supply security and to the environmental health of rivers. This study aims to derive reservoir operating rules through establishing a multi-objective optimization model for the Xinfengjiang (XFJ) reservoir in the East River Basin in southern China to minimize water supply deficit and maximize hydropower generation. Additionally, to enhance the estimation of irrigation water demand from the downstream agricultural area of the XFJ reservoir, a conventional method for calculating crop water demand is improved using hydrological model simulation results. Although the optimal reservoir operating rules are derived for the XFJ reservoir with three priority scenarios (water supply only, hydropower generation only, and equal priority), the river environmental health is set as the basic demand no matter which scenario is adopted. The results show that the new rules derived under the three scenarios can improve the reservoir operation for both water supply and hydropower generation when comparing to the historical performance. Moreover, these alternative reservoir operating policies provide the flexibility for the reservoir authority to choose the most appropriate one. Although changing the current operating rules may influence its hydropower-oriented functions, the new rules can be significant to cope with the increasingly prominent water shortage and degradation in the aquatic environment. Overall, our results and methods (improved estimation of irrigation water demand and formulation of the reservoir optimization model) can be useful for local watershed managers and valuable for other researchers worldwide.

Xinfengjiang Reservoir↗
USGS1998

Water-quality assessment of the Central Arizona Basins, Arizona and northern Mexico – Environmental setting and overview of water quality

The Central Arizona Basins study area in central and southern Arizona and northern Mexico is one of 60 study units that are part of the U.S. Geological Survey's National Water-Quality Assessment program. The purpose of this report is to describe the physical, chemical, and environmental characteristics that may affect water quality in the Central Arizona Basins study area and present an overview of water quality. Covering 34,700 square miles, the study area is characterized by generally north to northwestward-trending mountain ranges separated by broad, gently sloping alluvial valleys. Most of the perennial rivers and streams are in the northern part of the study area. Rivers and streams in the south are predominantly intermittent or ephemeral and flow in response to precipitation such as summer thunderstorms. Effluent-dependent streams do provide perennial flow in some reaches. The major aquifers in the study area are in the basin-fill deposits that may be as much as 12,000 feet thick. The 1990 population in the study area was about 3.45 million, and about 61 percent of the total was in Maricopa County (Phoenix and surrounding cities). Extensive population growth over the past decade has resulted in a twofold increase in urban land areas and increased municipal water use; however, agriculture remains the major water use. Seventy-three percent of all water with drawn in the study area during 1990 was used for agricultural purposes. The largest rivers in the study area-the Gila, Salt, and Verde-are perennial near their headwaters but become intermittent downstream because of impoundments and artificial diversions. As a result, the Central Arizona Basins study area is unique compared to less arid basins because the mean surface-water outflow is only 528 cubic feet per second from a total drainage area of 49,650 square miles. Peak flows in the northern part of the study area are the result of snowmelt runoff; whereas, summer thunderstorms account for the peak flows in the southern part. Ground water is the primary water supply in most of Arizona and the only source of drinking water used by communities in the southern half of the study area. Years of overpumping have caused water tables in basin fill to drop below once-perennial streams leaving streambeds dry, water too deep to pump economically, pumping of poorer quality water with depth, and earth fissures resulting from subsidence after dewatering of sediments. Natural processes-such as leaching of trace elements and major ions from geologic formations-and human activities-such as mining, agriculture, and urban development-have major effects on the quality of surface-water and ground-water resources in the Central Arizona Basins study area. Surface-water quality standards in Arizona are based on the designated use of the water such as full or partial body contact, fish consumption, aquatic and wildlife uses, and agriculture. Maintaining the biological integrity (health) of surface waters in Arizona is an important part of ensuring that these waters are suitable for designated uses. Important water-quality issues for surface water that are somewhat unique to Arizona include: (1) streamflows and riparian environments sustained by effluent from municipal wastewater-treatment plants that contains high concentrations of nutrients, potentially toxic trace elements and organic compounds, and fecal bacteria; (2) industrial, mining, agricultural, and municipal sources of contamination from Mexico; and (3) unpredictable high flows from major summer thunder storms causing stream-channel changes; high suspended-sediment concentrations and loads; sewage overflows; and breaching, erosion, and washout of landfills and mining operations. The quality of water in aquifers that are protected for drinking- water use is subject to standards that are in most cases equal to or more stringent than the primary drinking-water regulations of the U.S. Environmental Protection Agency. The general che

Arizona↗
USGS2011

Sediment dynamics and the burial and exhumation of bedrock reefs along an emergent coastline as elucidated by repetitive sonar surveys: Northern Monterey Bay, CA

Two high-resolution bathymetric and acoustic backscatter sonar surveys were conducted along the energetic emergent inner shelf of northern Monterey Bay, CA, USA, in the fall of 2005 and the spring of 2006 to determine the impact of winter storm waves, beach erosion, and river floods on biologically-important siliclastic bedrock reef habitats. The surveys extended from water depths of 4 m to 22 m and covered an area of 3.14 km2, 45.8% of which was bedrock, gravel, and coarse-grained sand and 54.2% was fine-grained sand. Our analyses of the bathymetric and acoustic backscatter data demonstrates that during the 6 months between surveys, 11.4% of the study area was buried by fine-grained sand while erosion resulted in the exposure of bedrock or coarse-grained sand over 26.5% of the study area. The probability of burial decreased with increasing water depth and rugosity; the probability of exhumation increased with increasing wave-induced near-bed shear stress, seabed slope and rugosity. Much of the detected change was at the boundary between bedrock and unconsolidated sediment due to sedimentation and erosion burying or exhuming bedrock, respectively. In a number of cases, however, the change in seabed character was apparently due to changes in sediment grain size when scour exposed what appeared to be an underlying coarser-grained lag or the burial of coarser-grained sand and gravel by fine-grained sand. These findings suggest that, in some places, (a) burial and exhumation of nearshore bedrock reefs along rocky, energetic inner shelves occurs over seasonal timescales and appears related to intrinsic factors such as seabed morphology and extrinsic factors such as wave forces, and (b) single acoustic surveys typically employed for geologic characterization and/or habitat mapping may not adequately characterize the geomorphologic and sedimentologic nature of these types of environments that typify most of the Pacific Ocean and up to 50% of the world's coastlines.

Monterey Bay↗
USGS2019

Pesticides and pollinators: A socioecological synthesis

The relationship between pesticides and pollinators , while attracting no shortage of attention from scientists, regulators, and the public, has proven resistant to scientific synthesis and fractious in matters of policy and public opinion. This is in part because the issue has been approached in a compartmentalized and intradisciplinary way, such that evaluations of organismal pesticide effects remain largely disjoint from their upstream drivers and downstream consequences. Here, we present a socioecological framework designed to synthesize the pesticide-pollinator system and inform future scholarship and action. Our framework consists of three interlocking domains-pesticide use, pesticide exposure, and pesticide effects–each consisting of causally linked patterns, processes, and states. We elaborate each of these domains and their linkages, reviewing relevant literature and providing empirical case studies. We then propose guidelines for future pesticide-pollinator scholarship and action agenda aimed at strengthening knowledge in neglected domains and integrating knowledge across domains to provide decision support for stakeholders and policymakers. Specifically, we emphasize (1) stakeholder engagement, (2) mechanistic study of pesticide exposure, (3) understanding the propagation of pesticide effects across levels of organization, and (4) full-cost accounting of the externalities of pesticide use and regulation. Addressing these items will require transdisciplinary collaborations within and beyond the scientific community, including the expertise of farmers, agrochemical developers, and policymakers in an extended peer community.

Science of the Total Environment↗