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USGS2021

Evaluation of Indoor PM2.5 concentrations in a Native American community: A pilot study

Background Indoor air pollution is associated with adverse health effects; however, few studies exist studying indoor air pollution on the Navajo Nation in the southwest U.S., a community with high rates of respiratory disease. Methods Indoor PM 2.5 concentration was evaluated in 26 homes on the Navajo Nation using real-time PM 2.5 monitors. Household risk factors and daily activities were evaluated with three metrics of indoor PM 2.5 : time-weighted average (TWA), 90th percentile of concentration, and daily minutes exceeding 100 μg/m 3 . A questionnaire and recall sheet were used to record baseline household characteristics and daily activities. Results The median TWA, 90th percentile, and daily minutes exceeding 100 μg/m 3 were 7.9 μg/m 3 , 14.0 μg/m 3 , and 17 min, respectively. TWAs tended to be higher in autumn and in houses that used fuel the previous day. Other characteristics associated with elevated PM exposure in all metrics included overcrowded houses, nonmobile houses, and houses with current smokers, pets, and longer cooking time. Conclusions Some residents of the Navajo Nation have higher risk of exposure to indoor air pollution by Environmental Protection Agency (EPA) standards. Efforts to identify the causes and associations with adverse health effects are needed to ensure that exposure to risks and possible health impacts are mitigated.

Journal of Exposure Science and Environmental Epid↗

USGS2010

Significance of dredging on sediment denitrification in Meiliang Bay, China: A year long simulation study

An experiment for studying the effects of sediment dredging on denitrification in sediments was carried out through a one-year incubation of undredged (control) and dredged cores in laboratory. Dredging the upper 30 cm of sediment can significantly affect physico-chemical characteristics of sediments. Less degradation of organic matter in the dredged sediments was found during the experiment. Denitrification rates in the sediments were estimated by the acetylene blockage technique, and ranged from 21.6 to 102.7 nmol N2/(g dry weight (dw) x hr) for the undredged sediment and from 6.9 to 26.9 nmol N2/(g dw x hr) for dredged sediments. The denitrification rates in the undredged sediments were markedly higher (p < 0.05) than those in the dredged sediments throughout the incubation, with the exception of February 2006. The importance of various environmental factors on denitrification was assessed, which indicated that denitrification was regulated by temperature. Nitrate was probably the key factor limiting denitrification in both undredged and dredged sediments. Organic carbon played some role in determining the denitrification rates in the dredged sediments, but not in the undredged sediments. Sediment dredging influenced the mineralization of organic matter and denitrification in the sediment; and therefore changed the pattern of inherent cycling of nitrogen.

Journal of Environmental Sciences↗

USGS2021

Until It's a regulation it's not my fight: Complexities of a voluntary nonlead hunting ammunition program

Wildlife and human health are at risk of lead exposure from spent hunting ammunition. Lead exposure persists for bald eagles due to bullet fragments in game animal gut piles and unretrieved carcasses, and is also a human health risk when wild game is procured using lead ammunition. Programs encouraging the voluntary use of nonlead ammunition have become a popular approach mitigating these effects. This study explored attitudes and experiences of United States Fish and Wildlife Service (USFWS) staff implementing an outreach program encouraging deer hunters to voluntary use nonlead ammunition on 54 National Wildlife Refuges (NWRs) in the Upper Midwest, U.S. to understand factors affecting program implementation. We conducted 29 semi-structured interviews of USFWS staff along with 60 responses from an open-ended survey question. Twelve themes emerged from the data and were grouped into three broad categories: (1) challenges of dealing with complex issues, (2) importance of messengers and messages, and (3) resistance from staff. Challenges of dealing with complex issues included administrative restraint and uncertainty, scope and scale of program, human health not an agency responsibility, contextual political influences, and public-private collaborations. Importance of messengers and messages included the importance of experience, and salience of human health risk. Finally, resistance from staff included skepticism of the science and motives behind the program, competing priorities for refuge staff, differing perceptions of regulatory and voluntary approaches, cost and availability of nonlead ammunition, and disregard by some about lead ammunition and human health risks. Staff identified numerous challenges implementing the program, many of which were external factors beyond the control of the participants. Understanding the factors affecting program implementation may help guide future efforts encouraging the voluntary use of nonlead ammunition.

Illinois, Iowa, Indiana, Michigan, Minnesota, Miss↗

USGS2009

High-resolution sclerochronological analysis of the bivalve mollusk Saxidomus gigantea from Alaska and British Columbia: techniques for revealing environmental archives and archaeological seasonality

The butter clam, Saxidomus gigantea, is one of the most commonly recovered bivalves from archaeological shell middens on the Pacific Coast of North America. This study presents the results of the sclerochronology of modern specimens of S. gigantea, collected monthly from Pender Island (British Columbia), and additional modern specimens from the Dundas Islands (BC) and Mink and Little Takli Islands (Alaska). The methods presented can be used as a template to interpret local environmental conditions and increase the precision of seasonality estimates in shellfish using sclerochronology and oxygen isotope analysis. This method can also identify, with a high degree of accuracy, the date of shell collection to the nearest fortnightly cycle, the time of day the shell was collected and the approximate tidal elevation (i.e., approx. water depth and distance from the shoreline) from which the shell was collected. Life-history traits of S. gigantea were analyzed to understand the timing of growth line formation, the duration of the growing season, the growth rate, and the reliability of annual increments. We also examine the influence of the tidal regime and freshwater mixing in estuarine locations and how these variables can affect both incremental structures and oxygen isotope values. The results of the sclerochronological analysis show that there is a latitudinal trend in shell growth that needs to be considered when using shells for seasonality studies. Oxygen isotope analysis reveals clear annual cycles with the most positive values corresponding to the annual winter growth lines, and the most negative values corresponding to high temperatures during the summer. Intra-annual increment widths demonstrate clear seasonal oscillations with broadest increments in summer and very narrow increments or no growth during the winter months. This study provides new insights into the biology, geochemistry and seasonal growth of S. gigantea, which are crucial for paleoclimate reconstructions and interpreting seasonality patterns of past human collection.

Alaska;British Columbia↗

USGS2023

Contribution of arsenic and uranium in private wells and community water systems to urinary biomarkers in US adults: The Strong Heart Study and the Multi-Ethnic Study of Atherosclerosis

Background Chronic exposure to inorganic arsenic (As) and uranium (U) in the United States (US) occurs from unregulated private wells and federally regulated community water systems (CWSs). The contribution of water to total exposure is assumed to be low when water As and U concentrations are low. Objective We examined the contribution of water As and U to urinary biomarkers in the Strong Heart Family Study (SHFS), a prospective study of American Indian communities, and the Multi-Ethnic Study of Atherosclerosis (MESA), a prospective study of racially/ethnically diverse urban U.S. communities. Methods We assigned residential zip code-level estimates in CWSs (µg/L) and private wells (90th percentile probability of As >10 µg/L) to up to 1485 and 6722 participants with dietary information and urinary biomarkers in the SHFS (2001–2003) and MESA (2000–2002; 2010–2011), respectively. Urine As was estimated as the sum of inorganic and methylated species, and urine U was total uranium. We used linear mixed-effects models to account for participant clustering and removed the effect of dietary sources via regression adjustment. Results The median (interquartile range) urine As was 5.32 (3.29, 8.53) and 6.32 (3.34, 12.48) µg/L for SHFS and MESA, respectively, and urine U was 0.037 (0.014, 0.071) and 0.007 (0.003, 0.018) µg/L. In a meta-analysis across both studies, urine As was 11% (95% CI: 3, 20%) higher and urine U was 35% (5, 73%) higher per twofold higher CWS As and U, respectively. In the SHFS, zip-code level factors such as private well and CWS As contributed 46% of variation in urine As, while in MESA, zip-code level factors, e.g., CWS As and U, contribute 30 and 49% of variation in urine As and U, respectively. Impact statement We found that water from unregulated private wells and regulated CWSs is a major contributor to urinary As and U (an estimated measure of internal dose) in both rural, American Indian populations and urban, racially/ethnically diverse populations nationwide, even at levels below the current regulatory standard. Our findings indicate that additional drinking water interventions, regulations, and policies can have a major impact on reducing total exposures to As and U, which are linked to adverse health effects even at low levels.

Journal of Exposure Science and Environmental Epid↗

USGS2008

Decadal-scale changes of nitrate in ground water of the United States, 1988-2004

This study evaluated decadal-scale changes of nitrate concentrations in groundwater samples collected by the USGS National Water-Quality Assessment Program from 495 wells in 24 well networks across the USA in predominantly agricultural areas. Each well network was sampled once during 1988-1995 and resampled once during 2000-2004. Statistical tests of decadal-scale changes of nitrate concentrations in water from all 495 wells combined indicate there is a significant increase in nitrate concentrations in the data set as a whole. Eight out of the 24 well networks, or about 33%, had significant changes of nitrate concentrations. Of the eight well networks with significant decadal-scale changes of nitrate, all except one, the Willamette Valley of Oregon, had increasing nitrate concentrations. Median nitrate concentrations of three of those eight well networks increased above the USEPA maximum contaminant level of 10 mg L-1. Nitrate in water from wells with reduced conditions had significantly smaller decadal-scale changes in nitrate concentrations than oxidized and mixed waters. A subset of wells had data on ground water recharge date; nitrate concentrations increased in response to the increase of N fertilizer use since about 1950. Determining ground water recharge dates is an important component of a ground water trends investigation because recharge dates provide a link between changes in ground water quality and changes in land-use practices. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

Journal of Environmental Quality↗

USGS2018

Evaluating spatial and temporal variability in growth and mortality for recreational fisheries with limited catch data

Understanding the spatial and temporal variability in life-history traits among populations is essential for the management of recreational fisheries. However, valuable freshwater recreational fish species often suffer from a lack of catch information. In this study, we demonstrated the use of an approach to estimate the spatial and temporal variability in growth and mortality in the absence of catch data and apply the method to riverine smallmouth bass ( Micropterus dolomieu ) populations in Pennsylvania, USA. Our approach included a growth analysis and a length-based analysis that estimates mortality. Using a hierarchical Bayesian approach, we examined spatial variability in growth and mortality by assuming parameters vary spatially but remain constant over time and temporal variability by assuming parameters vary spatially and temporally. The estimated growth and mortality of smallmouth bass showed substantial variability over time and across rivers. We explored the relationships of the estimated growth and mortality with spring water temperature and spring flow. Growth rate was likely to be positively correlated with these two factors, while young mortality was likely to be positively correlated with spring flow. The spatially and temporally varying growth and mortality suggest that smallmouth bass populations across rivers may respond differently to management plans and disturbance such as environmental contamination and land-use change. The analytical approach can be extended to other freshwater recreational species that also lack of catch data. The approach could also be useful in developing population assessments with erroneous catch data or be used as a model sensitivity scenario to verify traditional models even when catch data are available.

Pennsylvania↗

USGS2018

Development of a species status assessment process for decisions under the U.S. Endangered Species Act

Decisions under the U.S. Endangered Species Act (ESA) require scientific input on the risk that the species will become extinct. A series of critiques on the role of science in ESA decisions have called for improved consistency and transparency in species risk assessments and clear distinctions between science input and policy application. To address the critiques and document the emerging practice of the U.S. Fish and Wildlife Service (USFWS), we outline an assessment process based on principles and practices of risk and decision analyses that results in a scientific report on species status. The species status assessment (SSA) process has three successive stages: 1) document the life history and ecological relationships of the species in question to provide the foundation for the assessment, 2) describe and hypothesize causes for the current condition of the species, and 3) forecast the species' future condition. The future condition refers to the ability of a species to sustain populations in the wild under plausible future scenarios. The scenarios help explore the species' response to future environmental stressors and to assess the potential for conservation to intervene to improve its status. The SSA process incorporates modeling and scenario planning for prediction of extinction risk and applies the conservation biology principles of representation, resiliency, and redundancy to evaluate the current and future condition. The SSA results in a scientific report distinct from policy application, which contributes to streamlined, transparent, and consistent decision-making and allows for greater technical participation by experts outside of the USFWS, for example, by state natural resource agencies. We present two case studies based on assessments of the eastern massasauga rattlesnake Sistrurus catenatus and the Sonoran Desert tortoise Gopherus morafkai to illustrate the process. The SSA builds upon the past threat-focused assessment by including systematic and explicit analyses of a species' future response to stressors and conservation, and as a result, we believe it provides an improved scientific analysis for ESA decisions.

Journal of Fish and Wildlife Management↗

USGS2025

Reconciling scale using the Resist-Accept-Direct (RAD) Framework to improve management of woody encroachment in grasslands

Implementing strategies to navigate large-scale ecological transitions in grasslands is one of this century's greatest conservation challenges. In the US Great Plains, managing areas impacted by woody transitions have been reactive, short-lived, costly, and ineffective. Along with current technological innovation in rangeland monitoring, the promise of early warning science is to provide managers with sufficient time to be better prepared for novel signals of ecological change. Combining the science of early warning signals and frameworks such as the Resist – Accept – Direct (RAD) can provide land managers with guidelines to identify proactive strategies when facing ecological change. Using this approach, we found that opportunities to resist woody transitions decreased from 84 % to 60 % between 1990 and 2020 over the entire biome but remained highest in the northern and western Great Plains, which contributes to large scale conservation targets. These are key areas to prioritize resist opportunities. In contrast, 11 % of the biome exhibited early warning transition signals across all hierarchical scales by 2020, a fourfold increase since 1990. Lastly by 2020, 30 % of the biome exhibited early warning signals across multiple but not all scales. Here, efforts may be more effective when management is directed to conserve fragmented grassland legacies within a woody-dominated matrix and avoid large-scale monocultures of problematic encroaching woody species. Our multi-scale study indicates that 1) anchoring to the last remaining grassland core areas with no early warning of transitions and 2) strategically investing in these intact grasslands may provide the best results for grassland conservation.

Great Plains↗

USGS2015

Synergistic and singular effects of river discharge and lunar illumination on dam passage of upstream migrant yellow-phase American eels

Monitoring of dam passage can be useful for management and conservation assessments of American eel, particularly if passage counts can be examined over multiple years. During a 7-year study (2007–2013) of upstream migration of American eels within the lower Shenandoah River (Potomac River drainage), we counted and measured American eels at the Millville Dam eel pass, where annual study periods were determined by the timing of the eel pass installation during spring or summer and removal during fall. Daily American eel counts were analysed with negative binomial regression models, with and without a year (YR) effect, and with the following time-varying environmental covariates: river discharge of the Shenandoah River at Millville (RDM) and of the Potomac River at Point of Rocks, lunar illumination (LI), water temperature, and cloud cover. A total of 17 161 yellow-phase American eels used the pass during the seven annual periods, and length measurements were obtained from 9213 individuals (mean = 294 mm TL, s.e. = 0.49, range 183–594 mm). Data on passage counts of American eels supported an additive-effects model (YR + LI + RDM) where parameter estimates were positive for river discharge (β = 7.3, s.e. = 0.01) and negative for LI (β = −1.9, s.e. = 0.34). Interestingly, RDM and LI acted synergistically and singularly as correlates of upstream migration of American eels, but the highest daily counts and multiple-day passage events were associated with increased RDM. Annual installation of the eel pass during late spring or summer prevented an early spring assessment, a period with higher RDM relative to those values obtained during sampling periods. Because increases in river discharge are climatically controlled events, upstream migration events of American eels within the Potomac River drainage are likely linked to the influence of climate variability on flow regime.

Potomac River drainage, Shenandoah River↗

USGS2008

Chronic and episodic acidification of Adirondack streams from acid rain in 2003-2005

Limited information is available on streams in the Adirondack region of New York, although streams are more prone to acidification than the more studied Adirondack lakes. A stream assessment was therefore undertaken in the Oswegatchie and Black River drainages; an area of 4585 km2 in the western part of the Adirondack region. Acidification was evaluated with the newly developed base-cation surplus (BCS) and the conventional acid-neutralizing capacity by Gran titration (ANCG). During the survey when stream water was most acidic (March 2004), 105 of 188 streams (56%) were acidified based on the criterion of BCS < 0 ??eq L-1, whereas 29% were acidified based on an ANCG value < 0 ??eq L-1. During the survey when stream water was least acidic (August 2003), 15 of 129 streams (12%) were acidified based on the criterion of BCS < 0 ??eq L-1, whereas 5% were acidified based on ANCG value < 0 ??eq L -1. The contribution of acidic deposition to stream acidification was greater than that of strongly acidic organic acids in each of the surveys by factors ranging from approximately 2 to 5, but was greatest during spring snowmelt and least during elevated base flow in August. During snowmelt, the percentage attributable to acidic deposition was 81%, whereas during the October 2003 survey, when dissolved organic carbon (DOC) concentrations were highest, this percentage was 66%. The total length of stream reaches estimated to be prone to acidification was 718 km out of a total of 1237 km of stream reaches that were assessed. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

Journal of Environmental Quality↗

USGS2014

Simulating soil-water movement through loess-veneered landscapes using nonconsilient saturated hydraulic conductivity measurements

Soil Survey Geographic Database (SSURGO) data are available for the entire United States, so are incorporated in many regional and national models of hydrology and environmental management. However, SSURGO does not provide an understanding of spatial variability and only includes saturated hydraulic conductivity ( K sat ) values estimated from particle size analysis (PSA). This study showed model sensitivity to the substitution of SSURGO data with locally described soil properties or alternate methods of measuring K sat . Incorporation of these different soil data sets significantly changed the results of hydrologic modeling as a consequence of the amount of space available to store soil water and how this soil water is moved downslope. Locally described soil profiles indicated a difference in K sat when measured in the field vs. being estimated from PSA. This, in turn, caused a difference in which soil layers were incorporated in the hydrologic simulations using TOPMODEL, ultimately affecting how soil water storage was simulated. Simulations of free-flowing soil water, the amount of water traveling through pores too large to retain water against gravity, were compared with field observations of water in wells at five slope positions along a catena. Comparison of the simulated data with the observed data showed that the ability to model the range of conditions observed in the field varied as a function of three soil data sets (SSURGO and local field descriptions using PSA-derived K sat or field-measured K sat ) and that comparison of absolute values of soil water storage are not valid if different characterizations of soil properties are used.

Soil Science Society of America Journal↗

USGS2013

Influence of dissolved organic matter character on mercury incorporation by planktonic organisms: an experimental study using oligotrophic water from Patagonian lakes

Ligands present in dissolved organic matter (DOM) form complexes with inorganic divalent mercury (Hg 2+ ) affecting its bioavailability in pelagic food webs. This investigation addresses the influence of a natural gradient of DOM present in Patagonian lakes on the bioaccumulation of Hg 2+ (the prevailing mercury species in the water column of these lakes) by the algae Cryptomonas erosa and the zooplankters Brachionus calyciflorus and Boeckella antiqua. Hg 2+ accumulation was studied through laboratory experiments using natural water of four oligotrophic Patagonian lakes amended with 197 Hg 2+ . The bioavailability of Hg 2+ was affected by the concentration and character of DOM. The entrance of Hg 2+ into pelagic food webs occurs mostly through passive and active accumulation. The incorporation of Hg 2+ by Cryptomonas, up to 27% of the Hg 2+ amended, was found to be rapid and dominated by passive adsorption, and was greatest when low molecular weight compounds with protein-like or small phenolic signatures prevailed in the DOM. Conversely, high molecular weight compounds with a humic or fulvic signature kept Hg 2+ in the dissolved phase, resulting in the lowest Hg 2+ accumulation in this algae. In Brachionus and Boeckella the direct incorporation of Hg from the aqueous phase was up to 3% of the Hg 2+ amended. The dietary incorporation of Hg 2+ by Boeckella exceeded the direct absorption of this metal in natural water, and was remarkably similar to the Hg 2+ adsorbed in their prey. Overall, DOM concentration and character affected the adsorption of Hg 2+ by algae through competitive binding, while the incorporation of Hg 2+ into the zooplankton was dominated by trophic or dietary transfer.

Patagonia↗

USGS2024

Atlas of microscopic images of biochar using reflected light microscopy in biochar characterization

Derived through the thermochemical conversion of biomass, biochar is a carbon-rich substance recognized for its significance in environmental applications and sustainable agriculture. As interest in its utilization continues to rise, it becomes crucial to comprehend how the source material and pyrolysis parameters influence the properties of biochar and, consequently, to research the suitability of various analytical methods for characterizing it. Despite the current utilization of numerous physical and chemical methods, the untapped potential of reflected light microscopy warrants further exploration. While a few recent studies suggest a correlation between certain microscopic characteristics and selected physical and chemical properties of biochar, the data are limited and difficult to compare. This is primarily due to variations in the types of original biomass used and lack of information about pyrolysis conditions. Moreover, because only a limited number of photographs taken under a reflected light microscope are publicly available to-date, it is difficult to evaluate morphological differences between various biochars and other organic materials such as inertinites from coal, charcoal, etc. To address limited availability of publicly available data, this “Atlas of Microscopic Images of Biochar” presents a collection of more than 300 images contributed by researchers from Poland, the United States, Canada, Australia, Brazil, and Denmark. These photomicrographs capture optical characteristics of a diverse array of biochar, demonstrating its unique morphological and structural features. This visual documentation can serve as a valuable resource for researchers, industry professionals, educators, and enthusiasts interested in investigating the complexities of biochar forms.

Indiana Journal of Earth Sciences↗

USGS2009

A lacustrine record from Lop Nur, Xinjiang, China: Implications for paleoclimate change during Late Pleistocene

Climate variability during the Late Pleistocene is studied from the proxies in core CK-2 drilled from the Luobei Depression (91??03???E, 40??47???N), Lop Nur in the eastern Tarim Basin, Xinjiang, China. Geophysical and geochemical properties, including magnetic susceptibility, granularity, chroma, carbonate content, loss on ignition and trace elements, have been determined to reconstruct the environmental evolution of the area during 32-9 ka BP. The chronology is established by uranium-thorium disequilibrium dating techniques. Our data suggest four paleoclimate stages, indicating glacial variations between cold-humid and warm-arid environments. A period of extreme humidity occurred during 31,900-19,200 yr BP is attributed the last glacial maximum (LGM). The period was followed by a warm-arid episode during 19,200-13,500 yr BP. Then a cold-humid interval during 13,500-12,700 yr BP may correspond to another cooling phases at high latitudes of the Northern Hemisphere. The last stage from 12,700 to 9000 yr BP has a trend that the climate turned warm and arid. The Lop Nur region is characterized by particularly humid stadials and arid interstadials. The climate variability in Lop Nur was constrained by global climate change because it is correlated with Dansgaard-Oeschger and Heinrich events, which were observed at the northern high latitudes. The synchroneity of the palaeoclimatic events suggested that cold air activity at the northern high latitudes was the most important factor that influenced the climate evolution in the Lop Nur region. A probable mechanism that involves the migration of westerly winds is proposed to interpret this synchroneity. ?? 2008 Elsevier Ltd.

Journal of Asian Earth Sciences↗

USGS2010

Effect of diet on fecal and urinary estrogenic activity

The United States Environmental Protection Agency has identified estrogens from animal feeding operations as a major environmental concern, but few data are available to quantify the excretion of estrogenic compounds by dairy cattle. The objectives of this study were to quantify variation in estrogenic activity in feces and urine due to increased dietary inclusion of phytoestrogens. Ten Holstein heifers were assigned to 2 groups balanced for age and days pregnant; groups were randomly assigned to treatment sequence in a 2-period crossover design. Dietary treatments consisted of grass hay or red clover hay, and necessary supplements. Total collection allowed for sampling of feed refusals, feces, and urine during the last 4 d of each period. Feces and urine samples were pooled by heifer and period, and base extracts were analyzed for estrogenic activity (estrogen equivalents) using the yeast estrogen screen bioassay. Feces and urine samples collected from 5 heifers were extracted and analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) to quantify excretion of 7 phytoestrogenic compounds. Excretion of 17-β estradiolequivalents in urine was higher and tended to be higher in feces for heifers fed red clover hay (84.4 and 120.2 mg/d for feces and urine, respectively) compared with those fed grasshay (57.4 and 35.6 mg/d). Analysis by LC-MS/MS indicated greater fecal excretion of equol, genistein, daidzein, coumestrol, and formononetin by heifers fed red clover hay (1634, 29.9, 96.3, 27.8, and 163 mg/d, respectively) than heifers fed grass hay (340, 3.0, 46.2, 8.8, and 18.3 mg/d, respectively). Diet had no effect on fecal biochanin A or 2-carbethoxy-5, 7-dihydroxy-4’-methoxyisoflavone. Four phytoestrogens were detected in urine (2-carbethoxy-5, 7-dihydroxy-4’-methoxyisoflavone, daidzein, equol, and formononetin) and their excretion was not affected by diet. Identifying sources of variation in estrogenic activity of manure will aid in the development of practices to reduce environmental estrogen accumulation.

Journal of Dairy Science↗

USGS2004

EXAFS study of mercury(II) sorption to Fe- and Al-(hydr)oxides - II. Effects of chloride and sulfate

Common complexing ligands such as chloride and sulfate can significantly impact the sorption of Hg(II) to particle surfaces in aqueous environmental systems. To examine the effects of these ligands on Hg(II) sorption to mineral sorbents, macroscopic Hg(II) uptake measurements were conducted at pH 6 and [Hg]i=0.5 mM on goethite (??-FeOOH), ??-alumina (??-Al2O3), and bayerite (??-Al(OH)3) in the presence of chloride or sulfate, and the sorption products were characterized by extended X-ray absorption fine structure (EXAFS) spectroscopy. The presence of chloride resulted in reduced uptake of Hg(II) on all three substrates over the Cl- concentration ([Cl-]) range 10-5 to 10-2 M, lowering Hg surface coverages on goethite, ??-alumina, and bayerite from 0.42 to 0.07 ??mol/m2, 0.06 to 0.006 ??mol/m2, and 0.55 to 0.39 ??mol/m2 ([Cl -]=10-5 to 10-3 M only), respectively. This reduction in Hg(II) uptake is primarily a result of the formation of stable, nonsorbing aqueous HgCl2 complexes in solution, limiting the amount of free Hg(II) available to sorb. At higher [Cl-] beam reduction of Hg(II) to Hg(I) was observed, resulting in the possible formation of aqueous Hg2Cl2 species and the precipitation of calomel, Hg 2Cl2(s). The presence of sulfate caused enhanced Hg(II) uptake over the sulfate concentration ([SO42-]) range 10-5 to 0.9 M, increasing Hg surface coverages on goethite, ??-alumina, and bayerite from 0.39 to 0.45 ??mol/m2, 0.11 to 0.38 ??mol/m2, and 0.36 to 3.33 ??mol/m2, respectively. This effect is likely due to the direct sorption or accumulation of sulfate ions at the substrate interface, effectively reducing the positive surface charge that electrostatically inhibits Hg(II) sorption. Spectroscopic evidence for ternary surface complexation was observed in isolated cases, specifically in the Hg-goethite-sulfate system at high [SO42-] and in the Hg-goethite-chloride system. ?? 2003 Elsevier Inc. All rights reserved.

Journal of Colloid and Interface Science↗

USGS2021

Evaluation of remote mapping techniques for earthquake-triggered landslide inventories in an urban subarctic environment: A case study of the 2018 Anchorage, Alaska Earthquake

Earthquake-induced landslide inventories can be generated using field observations but doing so can be challenging if the affected landscape is large or inaccessible after an earthquake. Remote sensing data can be used to help overcome these limitations. The effectiveness of remotely sensed data to produce landslide inventories, however, is dependent on a variety of factors, such as the extent of coverage, timing, and data quality, as well as environmental factors such as atmospheric interference (e.g., clouds, water vapor) or snow and vegetation cover. With these challenges in mind, we use a combination of field observations and remote sensing data from multispectral, light detection and ranging (lidar), and synthetic aperture radar (SAR) sensors to produce a ground failure inventory for the urban areas affected by the 2018 magnitude (M w ) 7.1 Anchorage, Alaska earthquake. The earthquake occurred during late November at high latitude (∼61°N), and the lack of sunlight, persistent cloud cover, and snow cover that occurred after the earthquake made remote mapping challenging for this event. Despite these challenges, 43 landslides were manually mapped and classified using a combination of the datasets mentioned previously. Using this manually compiled inventory, we investigate the individual performance and reliability of three remote sensing techniques in this environment not typically hospitable to remotely sensed mapping. We found that differencing pre- and post-event normalized difference vegetation index maps and lidar worked best for identifying soil slumps and rapid soil flows, but not as well for small soil slides, soil block slides and rock falls. The SAR-based methods did not work well for identifying any landslide types because of high noise levels likely related to snow. Some landslides, especially those that resulted in minor surface displacement, were identifiable only from the field observations. This work highlights the importance of the rapid collection of field observations and provides guidance for future mappers on which techniques, or combination of techniques, will be most effective at remotely mapping landslides in a subarctic and urban environment.

Alaska↗