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At least 307 records · Page 17Linked to original sources
USGS2010

Accumulation of current-use and organochlorine pesticides in crab embyros from northern California, USA

Invertebrates have long been used as resident sentinels for assessing ecosystem health and productivity. The shore crabs, Hemigrapsus oregonensis and Pachygrapsus crassipes, are abundant in estuaries and beaches throughout northern California, USA and have been used as indicators of habitat conditions in several salt marshes. The overall objectives of the present study were to conduct a lab-based study to test the accumulation of current-use pesticides, validate the analytical method and to analyze field-collected crabs for a suite of 74 current-use and legacy pesticides. A simple laboratory uptake study was designed to determine if embryos could bioconcentrate the herbicide molinate over a 7-d period. At the end of the experiment, embryos were removed from the crabs and analyzed by gas chromatography/mass spectrometry. Although relatively hydrophilic (log K(OW) of 2.9), molinate did accumulate with an estimated bioconcentration factor (log BCF) of approximately 2.5. Following method validation, embryos were collected from two different Northern California salt marshes and analyzed. In field-collected embryos 18 current-use and eight organochlorine pesticides were detected including synthetic pyrethroids and organophosphate insecticides, as well as DDT and its degradates. Lipid-normalized concentrations of the pesticides detected in the field-collected crab embryos ranged from 0.1 to 4 ppm. Pesticide concentrations and profiles in crab embryos were site specific and could be correlated to differences in land-use practices. These preliminary results indicate that embryos are an effective sink for organic contaminants in the environment and have the potential to be good indicators of ecosystem health, especially when contaminant body burden analyses are paired with reproductive impairment assays.

California↗
USGS1998

Considerations in As analysis and speciation

This article summarizes recent experiences in arsenic (As) quantification, preservation, and speciation developed during AWWA Research Foundation (AWWARF) and Water Industry Technical Action Fund (WITAF) projects. The goal of this article is to alert analysts and decision-makers to potential problems in As analysis and speciation, because there appear to be several unresolved problems with routine analytical approaches. In true split drinking water samples As was quantified by three accepted analytical methods in three laboratories. The techniques used were graphite furnace atomic absorption spectrometry (GFAAS), inductively coupled plasma mass spectrometry (ICP-MS), and hydride generation inductively coupled plasma-emission spectrometry (HG-ICP-AES). Experimental findings are organized into sections on As analysis, particulate As in water supplies, and examination of As speciation methods.

Journal of the American Water Works Association↗
USGS2011

Spatial patch occupancy patterns of the Lower Keys marsh rabbit

Reliable estimates of presence or absence of a species can provide substantial information on management questions related to distribution and habitat use but should incorporate the probability of detection to reduce bias. We surveyed for the endangered Lower Keys marsh rabbit ( Sylvilagus palustris hefneri ) in habitat patches on 5 Florida Key islands, USA, to estimate occupancy and detection probabilities. We derived detection probabilities using spatial replication of plots and evaluated hypotheses that patch location (coastal or interior) and patch size influence occupancy and detection. Results demonstrate that detection probability, given rabbits were present, was <0.5 and suggest that naïve estimates (i.e., estimates without consideration of imperfect detection) of patch occupancy are negatively biased. We found that patch size and location influenced probability of occupancy but not detection. Our findings will be used by Refuge managers to evaluate population trends of Lower Keys marsh rabbits from historical data and to guide management decisions for species recovery. The sampling and analytical methods we used may be useful for researchers and managers of other endangered lagomorphs and cryptic or fossorial animals occupying diverse habitats.

Florida↗
USGS2018

Evaluating response distances to develop buffer zones for staging terns

Buffer zones, calculated by flight‐initiation distance (FID), are often used to reduce anthropogenic disturbances to wildlife, but FID can vary significantly across life‐history stages. We examined the behavioral effect of potential natural (gulls and shorebirds) and anthropogenic (pedestrians) disturbance sources to staging roseate ( Sterna dougallii ) and common tern ( S. hirundo ) flocks from July to September in 2014 and 2015 at Cape Cod, Massachusetts, USA. We estimated the proportion of the flock exhibiting different responses to potential disturbance sources as a function of distance, flock size, percent roseate terns, and local disturbance rates, using Bayesian zero‐and‐one inflated beta regression. The proportion of tern flocks responding to the presence of shorebirds by flying was low (0.01 ± 0.001 [SE]) and did not vary by distance or other covariates, whereas the proportion flying in response to gulls increased as distance decreased, with smaller flocks, and with flocks with a larger proportion of roseate terns being more sensitive to gull presence. Prolonged flight response rapidly increased in probability from 0.0 to as much as 1.0 as distance from pedestrians to the flock decreased from 100 m and was much more likely with smaller flocks. Pedestrian activity levels also had an effect on flock responses; those engaged in active behaviors such as jogging were more likely to cause flushing than those engaged in passive behaviors. Terns seemed to view pedestrians as more of a threat than shorebirds and gulls, even though gulls are frequent kleptoparasites of terns. Pedestrians >120 m from a tern flock generally elicited the same probability of flight response as shorebirds and gulls. We recommend managers maintain anthropogenic disturbance levels at or below the intensity of those from natural sources at sites where recreation and wildlife values are both important. Because staging tern flocks may use a variety of areas within a site, we recommend instituting a 100‐m buffer around areas potentially used by staging flocks at Cape Cod, where we studied every location roseate terns are known to use in large numbers. For other sites used by mixed‐species tern flocks, we recommend the use of our field and analytical methods to develop appropriate buffer distances that will keep pedestrians far enough away to reduce the likelihood of flight and other non‐locomotive anti‐predator behaviors. These buffer zones will also benefit other species sensitive to human activity.

Journal of Wildlife Management↗
USGS2022

Regional walrus abundance estimate in the United States Chukchi Sea in autumn

Human activities (e.g., shipping, tourism, oil, gas development) have increased in the Chukchi Sea because of declining sea ice. The declining sea ice itself and these activities may affect Pacific walrus ( Odobenus rosmarus divergens ) abundance; however, previous walrus abundance estimates have been notably imprecise. When sea ice is absent from the eastern Chukchi Sea, walruses in waters of the United States usually rest together onshore at a single Alaska coastal haulout, where they can be surveyed more easily than when they rest on dispersed offshore ice floes. We estimated the number of walruses on land (herd size) at this haulout from 13 unoccupied aircraft system (UAS) surveys flown within a 10-day period in each of 2018 and 2019. We estimated population size of walruses using the haulout over the course of the surveys by combining herd size data with data from satellite-linked transmitters that indicated whether tagged walruses were in or out of water during each survey. Our estimates of the population size of walruses using the haulout during each year's survey period were similar to each other and more precise than historical walrus abundance estimates: posterior means (95% credibility intervals) were 166,000 (133,000–201,000) for 2018 and 189,000 (135,000–251,000) for 2019. Auxiliary observations support using these estimates to represent the size of the population using the eastern Chukchi Sea in autumn during the surveyed years. Our study site was the only substantial Chukchi Sea coastal haulout in the United States during the survey periods and study-specific tracking data (consistent with known distribution and movement patterns) indicated tagged walruses remained in eastern Chukchi waters during the survey periods. In addition, the imagery, telemetry, and analytical methods developed for this study advance the prospect for precise range-wide walrus population size estimates.

Alaska↗
USGS2022

Accounting for spatial heterogeneity in visual obstruction in line-transect distance sampling of gopher tortoises

Line-transect distance sampling (LTDS) surveys are commonly used to estimate abundance of animals or objects. In terrestrial LTDS surveys of gopher tortoise ( Gopherus polyphemus ) burrows, the presence of ground-level vegetation substantially decreases detection of burrows of all sizes, but no field or analytical methods exist to control for spatially heterogeneous vegetation obstruction as a source of variation in detection. We propose the addition of a simple measurement of ground-level vegetation that serves as a covariate for the detection function. We present a Bayesian hierarchical model in which covariates burrow width and nearby vegetation height help to account for detection bias and improve precision of estimated density. We investigate the performance of this covariate by simulation and by using real LTDS data collected before and after application of prescribed fire. We collected data in 2018 at the Jones Center at Ichauway in Newton, Georgia, USA. Across all simulations, our model including both covariates produced the most accurate density point estimates of any of the models tested. For our case study, our Bayesian model with vegetation covariates tended to produce similar estimates of density before and after burns. Our study indicates that any level of spatial variation in vegetation obstruction decreases detection of burrows and may lead to underestimation in population size (≤68%) and proportion of individuals with small burrow sizes (≤32%) when not considered during analysis. Our work is extensible to other terrestrial sampling efforts where systematic measurement of a spatially distributed obstructing feature is feasible during the LTDS survey.

Georgia↗
USGS2018

Precision and relative effectiveness of a purse seine for sampling age-0 river herring in lakes

Stock assessments for anadromous river herring, collectively Alewife Alosa pseudoharengus and Blueback Herring A. aestivalis , lack adequate demographic information, particularly with respect to early life stages. Although sampling adult river herring is increasingly common throughout their range, currently no standardized, field‐based, analytical methods exist for estimating juvenile abundance in freshwater lakes. The objective of this research was to evaluate the relative effectiveness and sampling precision of a purse seine for estimating densities of age‐0 river herring in freshwater lakes. We used a purse seine to sample age‐0 river herring in June–September 2015 and June–July 2016 in 16 coastal freshwater lakes in the northeastern USA. Sampling effort varied from two seine hauls to more than 50 seine hauls per lake. Catch rates were highest in June and July, and sampling precision was maximized in July. Sampling at night (versus day) in open water (versus littoral areas) was most effective for capturing newly hatched larvae and juveniles up to ca. 100 mm TL. Bootstrap simulation results indicated that sampling precision of CPUE estimates increased with sampling effort, and there was a clear threshold beyond which increased effort resulted in negligible increases in precision. The effort required to produce precise CPUE estimates, as determined by the CV, was dependent on lake size; river herring densities could be estimated with up to 10 purse‐seine hauls (one‐two nights) in a small lake (<50 ha) and 15–20 hauls (two‐three nights) in a large lake (>50 ha). Fish collection techniques using a purse seine as described in this paper are likely to be effective for estimating recruit abundance of river herring in freshwater lakes across their range.

North American Journal of Fisheries Management↗
USGS2003

Oxygen isotopes in nitrate: New reference materials for 18O:17O:16O measurements and observations on nitrate-water equilibration

Despite a rapidly growing literature on analytical methods and field applications of O isotope-ratio measurements of NO 3 − in environmental studies, there is evidence that the reported data may not be comparable because reference materials with widely varying δ 18 O values have not been readily available. To address this problem, we prepared large quantities of two nitrate salts with contrasting O isotopic compositions for distribution as reference materials for O isotope-ratio measurements: USGS34 (KNO 3 ) with low δ 18 O and USGS35 (NaNO 3 ) with high δ 18 O and ‘mass-independent’ δ 17 O. The procedure used to produce USGS34 involved equilibration of HNO 3 with 18 O-depleted meteoric water. Nitric acid equilibration is proposed as a simple method for producing laboratory NO 3 − reference materials with a range of δ 18 O values and normal (mass-dependent) 18 O: 17 O: 16 O variation. Preliminary data indicate that the equilibrium O isotope-fractionation factor ( α ) between [NO 3 − ] and H 2 O decreases with increasing temperature from 1.0215 at 22°C to 1.0131 at 100°C. USGS35 was purified from the nitrate ore deposits of the Atacama Desert in Chile and has a high 17 O: 18 O ratio owing to its atmospheric origin. These new reference materials, combined with previously distributed NO 3 − isotopic reference materials IAEA-N3 (=IAEA-NO-3) and USGS32, can be used to calibrate local laboratory reference materials for determining offset values, scale factors, and mass-independent effects on N and O isotope-ratio measurements in a wide variety of environmental NO 3 − samples. Preliminary analyses yield the following results (normalized with respect to VSMOW and SLAP, with reproducibilities of ±0.2–0.3‰, 1 σ ): IAEA-N3 has δ 18 O = +25.6‰ and δ 17 O = +13.2‰; USGS32 has δ 18 O = +25.7‰; USGS34 has δ 18 O = −27.9‰ and δ 17 O = −14.8‰; and USGS35 has δ 18 O = +57.5‰ and δ 17 O = +51.5‰.

Rapid Communications in Mass Spectrometry↗
USGS2002

Oxygen isotope corrections for online δ34S analysis

Elemental analyzers have been successfully coupled to stable-isotope-ratio mass spectrometers for online measurements of the δ34S isotopic composition of plants, animals and soils. We found that the online technology for automated δ34S isotopic determinations did not yield reproducible oxygen isotopic compositions in the SO2 produced, and as a result calculated δ34S values were often 1–3‰ too high versus their correct values, particularly for plant and animal samples with high C/S ratio. Here we provide empirical and analytical methods for correcting the S isotope values for oxygen isotope variations, and further detail a new SO2-SiO2 buffering method that minimizes detrimental oxygen isotope variations in SO2.

Rapid Communications in Mass Spectrometry↗
USGS2011

Isotopic tracing of perchlorate in the environment

Isotopic measurements can be used for tracing the sources and behavior of environmental contaminants. Perchlorate (ClO 4 − ) has been detected widely in groundwater, soils, fertilizers, plants, milk, and human urine since 1997, when improved analytical methods for analyzing ClO 4 − concentration became available for routine use. Perchlorate ingestion poses a risk to human health because of its interference with thyroidal hormone production. Consequently, methods for isotopic analysis of ClO 4 − have been developed and applied to assist evaluation of the origin and migration of this common contaminant. Isotopic data are now available for stable isotopes of oxygen and chlorine, as well as 36 Cl isotopic abundances, in ClO 4 − samples from a variety of natural and synthetic sources. These isotopic data provide a basis for distinguishing sources of ClO 4 − found in the environment, and for understanding the origin of natural ClO 4 − . In addition, the isotope effects of microbial ClO 4 − reduction have been measured in laboratory and field experiments, providing a tool for assessing ClO 4 − attenuation in the environment. Isotopic data have been used successfully in some areas for identifying major sources of ClO 4 − contamination in drinking water supplies. Questions about the origin and global biogeochemical cycle of natural ClO 4 − remain to be addressed; such work would benefit from the development of methods for preparation and isotopic analysis of ClO 4 − in samples with low concentrations and complex matrices.

Book chapter↗
USGS1998

Sources and age of aquatic humus

As aquatic scientists have recognized the diversity of processes controlled by or dependent upon aquatic humus, it has become important to learn more about the genesis, chemical properties, and concentration of humic substances in aquatic ecosystems. There are three classes of aquatic humus (fulvic acids, humic acids, and humin), all of which share the characteristics of being heterogeneous biomolecules which are yellow to brown or black in color, high to moderate molecular weight, and biologically recalcitrant. Fulvic acids are organic acids which are soluble at any pH; humic acids are soluble above pH 2; and humin is insoluble under the full range of pH. Aquatic humus occurs in both dissolved and solid phases, with molecular weights ranging from about 500 D for dissolved fulvic acid to greater than 100,000 D for humic acids in sediments. Although the heterogeneity of these humic fractions makes rigorous chemical studies challenging, there are sufficient analytical methods at hand to make progress toward understanding the sources, formation pathways, and fate of aquatic humus.

Book chapter↗
USGS1994

Cyanide and migratory birds at gold mines in Nevada, USA

Since the mid-1980s, cyanide in heap leach solutions and mill tailings ponds at gold mines in Nevada has killed a large but incompletely documented number of wildlife (>9,500 individuals, primarily migratory birds). This field investigation documents the availability of cyanide at a variety of ‘typical’ Nevada gold mines during 1990 and 1991, describes wildlife reactions to cyanide solutions, and discusses procedures for eliminating wildlife loss from cyanide poisoning. Substantial progress has been made to reduce wildlife loss. About half of the mill tailings ponds (some up to 150 ha) in Nevada have been chemically treated to reduce cyanide concentrations (the number needing treatment is uncertain) and many of the smaller heap leach solution ponds and channels are now covered with netting to exclude birds and most mammals. The discovery of a cyanide gradient in mill tailings ponds (concentration usually 2–3 times higher at the inflow point than at reclaim point) provides new insight into wildlife responses (mortality) observed in different portions of the ponds. Finding dead birds on the tops of ore heaps and associated with solution puddling is a new problem, but management procedures for eliminating this source of mortality are available. A safe threshold concentration of cyanide to eliminate wildlife loss could not be determined from the field data and initial laboratory studies. New analytical methods may be required to assess further the wildlife hazard of cyanide in mining solutions.

Nevada↗
USGS1977

Survey of trace elements in coals and coal-related materials by neutron activation analysis

Utilizing primarily instrumental neutron activation analysis (INAA) and other analytical methods as many as 61 elements were quantitatively surveyed in 170 U.S. whole coals, 70 washed coals, and 40 bench samples. Data on areal and vertical distributions in various regions were obtained along with extensive information on the mode of occurrence of various elements in the coal matrix itself. ?? 1977 Akade??miai Kiado??.

Journal of Radioanalytical Chemistry↗
USGS2012

Near-field tsunami edge waves and complex earthquake rupture

The effect of distributed coseismic slip on progressive, near-field edge waves is examined for continental shelf tsunamis. Detailed observations of edge waves are difficult to separate from the other tsunami phases that are observed on tide gauge records. In this study, analytic methods are used to compute tsunami edge waves distributed over a finite number of modes and for uniformly sloping bathymetry. Coseismic displacements from static elastic theory are introduced as initial conditions in calculating the evolution of progressive edge-waves. Both simple crack representations (constant stress drop) and stochastic slip models (heterogeneous stress drop) are tested on a fault with geometry similar to that of the M w = 8.8 2010 Chile earthquake. Crack-like ruptures that are beneath or that span the shoreline result in similar longshore patterns of maximum edge-wave amplitude. Ruptures located farther offshore result in reduced edge-wave excitation, consistent with previous studies. Introduction of stress-drop heterogeneity by way of stochastic slip models results in significantly more variability in longshore edge-wave patterns compared to crack-like ruptures for the same offshore source position. In some cases, regions of high slip that are spatially distinct will yield sub-events, in terms of tsunami generation. Constructive interference of both non-trapped and trapped waves can yield significantly larger tsunamis than those that produced by simple earthquake characterizations.

Pure and Applied Geophysics↗
USGS2007

Development and certification of the new SRM 695 trace elements in multi-nutrient fertilizer

During the past seven years, several states within the US have enacted regulations that limit the amounts of selected non-nutritive elements in fertilizers. Internationally, several countries, including Japan, China, and Australia, and the European Union also limit the amount of selected elements in fertilizers. The elements of interest include As, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, Se, and Zn. Fertilizer manufacturers and state regulatory authorities, faced with meeting and verifying these limits, need to develop analytical methods for determination of the elements of concern and to validate results obtained using these methods. Until now, there were no certified reference materials available with certified mass fraction values for all elements of interest in a blended, multi-nutrient fertilizer matrix. A new standard reference material (SRM) 695 trace elements in multi-nutrient fertilizer, has been developed to help meet these needs. SRM 695 has recently been issued with certified mass fraction values for seventeen elements, reference values for an additional five elements, and information values for two elements. The certificate of analysis includes an addendum listing percentage recovery for eight of these elements, determined using an acid-extraction inductively-coupled plasma optical-emission spectrometry (ICP-OES) method recently developed and tested by members of the Association of American Plant Food Control Officials. ?? Springer-Verlag 2007.

Conference Paper↗
USGS2023

Broadening benefits and anticipating tradeoffs with a proposed ecosystem service analysis framework for the US Army Corps of Engineers

Would-be adopters of ecosystem service analysis frameworks might ask, ‘Do such frameworks improve ecosystem service provision or social benefits sufficiently to compensate for any extra effort?’ Here we explore that question by retrospectively applying an ecosystem goods and services (EGS) analysis framework to a large river restoration case study conducted by the US Army Corps of Engineers (USACE) and comparing potential time costs and outcomes of traditional versus EGS-informed planning. USACE analytic methods can have a large influence on which river and wetland restoration projects are implemented in the United States because they affect which projects or project elements are eligible for federal cost-share funding. A new framework is designed for the USACE and is primarily distinguished from current procedures by adding explicit steps to document and compare tradeoffs and complementarity among all affected EGS, rather than the subset that falls within project purposes. Further, it applies economic concepts to transform ecological performance indicators into social benefit indicators, even if changes cannot be valued. We conclude that, for large multi-partner restoration projects like our case study, using the framework provides novel information on social outcomes that could be used to enhance project design, without substantially increasing scoping costs. The primary benefits of using the framework in the case study appeared to stem from early comprehensive identification of stakeholder interests that might have prevented project delays late in the process, and improving the communication of social benefits and how tradeoffs among EGS benefits were weighed during planning.

Missouri↗
USGS2022

A golden era for volcanic gas geochemistry?

The exsolution, rise, expansion, and separation of volatiles from magma provides the driving force behind both effusive and explosive volcanic eruptions. The field of volcanic gas geochemistry therefore plays a key role in understanding volcanism. In this article, we summarize the most important findings of the past few decades and how these shape today’s understanding of volcanic degassing. We argue that the recent advent of automated, continuous geochemical monitoring at volcanoes now allows us to track activity from unrest to eruption, thus providing valuable insights into the behavior of volatiles throughout the entire sequence. In the next 10 years, the research community stands to benefit from the expansion of geochemical monitoring networks to many more active volcanoes. This, along with technical advances in instrumentation, and in particular the increasing role that unoccupied aircraft systems (UAS) and satellite-based observations are likely to play in collecting volcanic gas measurements, will provide a rich dataset for testing hypotheses and developing diagnostic tools for eruption forecasts. The use of consistent, well-documented analytical methods and ensuring free, public access to the collected data with few restrictions will be most beneficial to the advancement of volcanic gas science.

Bulletin of Volcanology↗
USGS2016

Monitoring for the management of disease risk in animal translocation programmes

Monitoring is best viewed as a component of some larger programme focused on science or conservation. The value of monitoring is determined by the extent to which it informs the parent process. Animal translocation programmes are typically designed to augment or establish viable animal populations without changing the local community in any detrimental way. Such programmes seek to minimize disease risk to local wild animals, to translocated animals, and in some cases to humans. Disease monitoring can inform translocation decisions by (1) providing information for state-dependent decisions, (2) assessing progress towards programme objectives, and (3) permitting learning in order to make better decisions in the future. Here we discuss specific decisions that can be informed by both pre-release and post-release disease monitoring programmes. We specify state variables and vital rates needed to inform these decisions. We then discuss monitoring data and analytic methods that can be used to estimate these state variables and vital rates. Our discussion is necessarily general, but hopefully provides a basis for tailoring disease monitoring approaches to specific translocation programmes.

EcoHealth↗