Search Results

Interactions among flow, geomorphic processes, and riparian vegetation can strongly influence both channel form and vegetation communities. To investigate such interactions, we took advantage of a series of dam-managed flood releases that were designed in part to maintain a native riparian woodland system on a sand-bed, dryland river, the Bill...

In August and September 2010, the U.S. Geological Survey, in cooperation with Natural Resources Canada, Geological Survey of Canada, conducted bathymetric and geophysical surveys in the Beaufort Sea and eastern Arctic Ocean aboard the U.S. Coast Guard Cutter Healy. The principal objective of this mission to the high Arctic was...

Environmental conditions shape community composition. Arctic thermal springs provide an opportunity to study how environmental gradients can impose strong selective pressures on microbial communities and provide a continuum of niche opportunities. We use microscopic and molecular methods to conduct a survey of microbial community composition at Troll Springs on Svalbard,...

Nonindigenous apple snails, Pomacea maculata (formerly Pomacea insularum), are currently spreading rapidly through the southeastern United States. This mollusk serves as an intermediate host of the rat lungworm parasite (Angiostrongylus cantonensis), which can cause eosinophilic meningitis in humans who consume infected mollusks. A PCR-based detection assay was used to test...

There will be winners and losers as climate change alters the habitats of polar organisms. For an Adélie penguin (Pygoscelis adeliae) colony on Beaufort Island (Beaufort), part of a cluster of colonies in the southern Ross Sea, we report a recent population increase in response to increased nesting habitat as...

Improved understanding of the complex dynamics associated with spatially and temporally variable runoff response is needed to better understand the hydrology component of interdisciplinary problems. The objective of this study was to quantitatively characterize the environmental controls on runoff generation for the range of different streamflow-generation mechanisms illustrated in the...

The current estimate of the soil organic carbon (SOC) pool in the northern permafrost region of 1672 Petagrams (Pg) C is much larger than previously reported and needs to be incorporated in global soil carbon (C) inventories. The Northern Circumpolar Soil Carbon Database (NCSCD), extended to include the range 0–300 cm,...

Any estimate of ‘age’ of a groundwater sample based on environmental tracers requires some form of geochemical model to interpret the tracer chemistry (chapter 3) and is, therefore, referred to in this chapter as a tracer model age. the tracer model age of a groundwater sample can be useful for...

Land managers are grappling with massive changes in vegetation structure, particularly in protected areas formerly subjected to fire and grazing. The objective of this review was to compare notes on the historical and current management of ecosystems around the world (especially in wet to dry grasslands in the Americas, Australia,...

The radioactive isotope of carbon, radiocarbon (14C), was first produced artificially in 1940 by Martin Kamen and Sam Ruben, who bombarded graphite in a cyclotron at the Radiation Laboratory at Berkeley, CA, in an attempt to produce a radioactive isotope of carbon that could be used as a tracer in...

This book investigates applications of selected chemical and isotopic substances that can be used to recognize and interpret age information pertaining to ‘old’ groundwater (defined as water that was recharged on a timescale from approximately 1000 to more than 1 000 000 a). However, as discussed below, only estimates of...

This chapter discusses some of the fundamental concepts, data needs and approaches that aid in developing a general understanding of a groundwater system. Principles of the hydrological cycle are reviewed; the processes of recharge and discharge in aquifer systems; types of geological, hydrological and hydraulic data needed to describe the...

The U.S. Geological Survey created a comprehensive geopressure-gradient model of the regional pressure system spanning the onshore and offshore Gulf of Mexico basin, USA. This model was used to generate ten maps that included (1) five contour maps characterizing the depth to the surface defined by the first occurrence of...

Phast4Windows is a Windows® program for developing and running groundwater-flow and reactive-transport models with the PHAST simulator. This graphical user interface allows definition of grid-independent spatial distributions of model properties—the porous media properties, the initial head and chemistry conditions, boundary conditions, and locations of wells, rivers, drains, and accounting zones—and...

Characterization of ore and waste-rock material using automated quantitative micro-mineralogical techniques (e.g., QEMSCAN® and MLA) has the potential to complement traditional acid-base accounting and humidity cell techniques when predicting acid generation and metal release. These characterization techniques, which most commonly are used for metallurgical, mineral-processing, and geometallurgical applications, can be...

In 1994, the U.S. Geological Survey (USGS), in cooperation with the U.S. Navy, deployed three sets of moorings in Sinclair Inlet, which is a relatively small embayment on the western side of Puget Sound (fig. 1). This inlet is home to the Puget Sound Naval Shipyard. One purpose of the...

Elemental sulfur, as a transient intermediate compound, by-product, or catalyst, plays significant roles in thermochemical sulfate reduction (TSR) reactions. However, the mechanisms of the reactions in S-H2O-hydrocarbons systems are not clear. To improve our understanding of reaction mechanisms, we conducted a series of experiments between 200 and 340 °C for...

Management and restoration of the Mississippi River deltaic plain (southern United States) and associated wetlands require a quantitative understanding of sediment delivery during large flood events, past and present. Here, we investigate the sedimentary fingerprint of the 2011 Mississippi River flood across the Louisiana coast (Atchafalaya Delta, Terrebonne, Barataria, and...

Ecological theory predicts that the diffuse risk cues generated by wide-ranging, active predators should induce prey behavioural responses but not major, population- or community-level consequences. We evaluated the non-consumptive effects (NCEs) of an active predator, the grey wolf (Canis lupus), by simultaneously tracking wolves and the behaviour, body fat, and...

Coal fires occur in nature spontaneously, contribute to increases in greenhouse gases, and emit atmospheric toxicants. Increasing interest in quantifying coal fire emissions has resulted in the adaptation and development of specialized approaches and adoption of numerical modeling techniques. Overview of these methods for direct estimation of diffuse gas emissions...

We have developed a novel, in vivo superinfection fitness assay to examine superinfection dynamics and the role of virulence in superinfection fitness. This assay involves controlled, sequential infections of a natural, vertebrate host, Oncorhynchus mykiss (rainbow trout), with variants of a co-evolved viral pathogen, infectious hematopoietic necrosis virus (IHNV). Intervals...

Colonization of vacant habitats is an important process for supporting the long-term persistence of populations and species. We used a before–after experimental design to follow the process of colonization by steelhead Oncorhynchus mykiss (anadromous Rainbow Trout) at six monitoring sites in a natal stream, Beaver Creek, after the modification or...

In this study we report uranium analysis for human semen samples. Uranium quantification was performed by inductively coupled plasma mass spectrometry. No additives, such as chymotrypsin or bovine serum albumin, were used for semen liquefaction, as they showed significant uranium content. For method validation we spiked 2 g aliquots of pooled...

Coastal recreation and water quality are major contributors to human well-being in coastal regions. They can also interact, creating opportunities for ecosystem based management, ecological restoration, and water quality improvement that can positively affect people and the environment. Yet the effect of environmental quality on human behavior is often poorly...