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At least 901 records · Page 50Linked to original sources
USGS2007

Preliminary Surficial Geology of the Dove Spring Off-Highway Vehicle Open Area, Mojave Desert, California

Introduction As part of a U.S. Geological Survey (USGS) monitoring plan to evaluate the environmental impact of off-highway vehicle (OHV) use on Bureau of Land Management (BLM) land in California, this report presents results of geologic studies in the Dove Spring OHV Open Area. This study produced baseline data, which when combined with historic and current patterns of land use, forms the basis for vegetation and wildlife monitoring designed to address the following questions: 1. Is the density and length of OHV routes increasing? 2. Are there cumulative effects of past and current OHV use associated with changes in the environmental integrity of soils, plants, and wildlife? 3. Is the spread of invasive species associated with levels of OHV use? 4. Is there a threshold of OHV impact that might be translated to management action by the BLM? The monitoring studies will be used to collect baseline environmental information to determine levels of environmental impact of OHV use. This approach will use a low-impact area as a proxy for pre-impact conditions (substituting space for time) to determine thresholds of OHV impacts beyond which environmental integrity is affected. Indicators of environmental integrity will emphasize factors that are fundamental to ecosystem structure and function and likely to be sensitive to OHV impacts. Surficial geology is studied because material properties such as texture and chemistry strongly control soil moisture and nutrient availability and therefore affect plant growth and distribution. An understanding of surficial geology can be used to predict and extrapolate soil properties and improve understanding of vegetation assemblages and their distribution. In the present study, vegetation associations may be examined as a function of surficial geology as well as other environmental variables such as slope, aspect, NRCS (National Resources Conservation Service) soil classification, elevation, and land-use history. Ground measurements of vegetation, biological soil crusts, compaction, and other information may be correlated with land use to identify possible ecological thresholds in OHV use that require monitoring. Surficial geology is relevant for several other studies of OHV impact, such as soil compaction, dust emissions, and acceleration of erosion. Compaction, reduced infiltration, and accelerated erosion have been documented in Dove Spring Canyon because of OHV use (Snyder and others, 1976) and elsewhere in the Mojave Desert (e.g., Webb, 1983; Langdon, 2000). A surficial geologic map enables the use of geomorphic process models, which when combined with measured soil properties, such as texture, nutrient chemistry, and bulk density, allows spatial extrapolation of the properties. Maps can be produced that predict compaction susceptibility, moisture conditions, dust emissions, flood hazards, and erodibility, among other applications.

Open-File Report↗
USGS2023

Compost, plants and endophytes versus metal contamination: Choice of a restoration strategy steers the microbiome in polymetallic mine waste

Finding solutions for the remediation and restoration of abandoned mining areas is of great environmental importance as they pose a risk to ecosystem health. In this study, our aim was to determine how remediation strategies with (i) compost amendment, (ii) planting a metal-tolerant grass Bouteloua curtipendula , and (iii) its inoculation with beneficial endophytes influenced the microbiome of metal-contaminated tailings originating from the abandoned Blue Nose Mine, SE Arizona, near Patagonia (USA). We conducted an indoor microcosm experiment followed by a metataxonomic analysis of the mine tailings, compost, and root samples. Our results showed that each remediation strategy promoted a distinct pattern of microbial community structure in the mine tailings, which correlated with changes in their chemical properties. The combination of compost amendment and endophyte inoculation led to the highest prokaryotic diversity and total nitrogen and organic carbon, but also induced shifts in microbial community structure that significantly correlated with an enhanced potential for mobilization of Cu and Sb. Our findings show that soil health metrics (total nitrogen, organic carbon and pH) improved, and microbial community changed, due to organic matter input and endophyte inoculation, which enhanced metal leaching from the mine waste and potentially increased environmental risks posed by Cu and Sb. We further emphasize that because the initial choice of remediation strategy can significantly impact trace element mobility via modulation of both soil chemistry and microbial communities, site specific, bench-scale preliminary tests, as reported here, can help determine the potential risk of a chosen strategy.

Environmental Microbiome↗
USGS2025

Factors structuring macrofaunal communities of hydrocarbon seeps along the Cascadia margin

Cold seeps, fueled by hydrocarbon-based chemosynthesis, support unique benthic communities that can vary across small spatial scales influenced by local geochemistry. We examined the community structure and function of macrofauna in cold seeps along the Cascadia margin on the edge of gas hydrate stability—a dynamic environment that may fluctuate as seafloor temperatures change. These communities were assessed in relation to their sediment environment to provide baseline data for these previously uninvestigated seeps and decipher the most significant variables structuring them. Specific environmental drivers investigated include sediment organic carbon, total nitrogen, C:N ratios, stable isotopes (δ 13 C and δ 15 N), redox potential, grain size, and porefluid chemistry. Macrofaunal community composition varied across locations separating into twelve distinct clusters. Several co-located cores clustered separately, indicating high heterogeneity in these communities at small spatial scales. Significant drivers of macrofauna communities included clay and sand content, C:N, δ 15 N values, organic carbon content, and depth. Functional trait composition was influenced by similar drivers, including depth, δ 15 N values, C:N, and sand content. Our results indicate similar environmental variables structure macrofaunal community composition and function across small- and large-scale gradients, contributing to our understanding of heterogeneity in local and regional factors that shape seep macrofaunal communities. This is the first investigation of macrofauna at these recently discovered seeps and provides baseline data on the hydrate stability zone for future comparisons, advancing our knowledge of broad-scale trends in seep macrofauna ecology.

California, Oregon, Washington↗
USGS2011

Spring runoff water-chemistry data from the Standard Mine and Elk Creek, Gunnison County, Colorado, 2010

Water samples were collected approximately every two weeks during the spring of 2010 from the Level 1 portal of the Standard Mine and from two locations on Elk Creek. The objective of the sampling was to: (1) better define the expected range and timing of variations in pH and metal concentrations in Level 1 discharge and Elk Creek during spring runoff; and (2) further evaluate possible mechanisms controlling water quality during spring runoff. Samples were analyzed for major ions, selected trace elements, and stable isotopes of oxygen and hydrogen (oxygen-18 and deuterium). The Level 1 portal sample and one of the Elk Creek samples (EC-CELK1) were collected from the same locations as samples taken in the spring of 2007, allowing comparison between the two different years. Available meteorological and hydrologic data suggest that 2010 was an average water year and 2007 was below average. Field pH and dissolved metal concentrations in Level 1 discharge had the following ranges: pH, 2.90 to 6.23; zinc, 11.2 to 26.5 mg/L; cadmium, 0.084 to 0.158 mg/L; manganese, 3.23 to 10.2 mg/L; lead, 0.0794 to 1.71 mg/L; and copper, 0.0674 to 1.14 mg/L. These ranges were generally similar to those observed in 2007. Metal concentrations near the mouth of Elk Creek (EC-CELK1) were substantially lower than in 2007. Possible explanations include remedial efforts at the Standard Mine site implemented after 2007 and greater dilution due to higher Elk Creek flows in 2010. Temporal patterns in pH and metal concentrations in Level 1 discharge were similar to those observed in 2007, with pH, zinc, cadmium, and manganese concentrations generally decreasing, and lead and copper generally increasing during the snowmelt runoff period. Zinc and cadmium concentrations were inversely correlated with flow and thus apparently dilution-controlled. Lead and copper concentrations were inversely correlated with pH and thus apparently pH-controlled. Zinc, cadmium, and manganese concentrations near the mouth of Elk Creek did not display the pronounced increase observed during high flow in 2007, again perhaps due to remedial activities at the mine site or greater dilution in 2010. Zinc and cadmium loads near the mouth of Elk Creek were generally greater than those at the Level 1 portal for the six sample days in 2010. Whereas metal loads in September 2007 suggested that Level 1 portal discharge was the primary source of metals to the creek, metal loads computed for this study suggest that this may not have been the case in the spring of 2010. d18O values are well correlated with flow, becoming lighter (more negative) during snowmelt in both Level 1 discharge and Elk Creek. Seasonal variations in the chemistry of Level 1 discharge, along with portal flow tracking very closely with creek flow, are consistent with geochemical and environmental tracer data from 2007 that indicate short residence times (<1 year) for groundwater discharging from the Standard Mine.

Colorado↗
USGS1994

Assessment of concentrations of trace elements in ground water and soil at the Small-Arms Firing Range, Shaw Air Force Base, South Carolina

Ground-water samples were collected from four shallow water-table aquifer observation wells beneath the Small-Arms Firing Range study area at Shaw Air Force Base. Water-chemistry analyses indicated that total lead concentrations in shallow ground water beneath the study area do not exceed the U.S. Environmental Protection Agency maximum contaminant level established for lead in drinking water (0.05 milligrams per liter). All other trace element total concentrations in ground water beneath the study area were at or below the detection limit of the analytical methodology.

South Carolina↗
USGS1999

Inhibition of hydroxyl radical reaction with aromatics by dissolved natural organic matter

Reaction of aromatic compounds with hydroxyl radical is inhibited by dissolved natural organic matter (NOM). The degree of inhibition is significantly greater than that expected based on a simple model in which aromatic compound molecules bound to NOM are considered to be unreactive. In this study, hydroxyl radical was produced at steady-state concentrations using Fenton chemistry (H2O2 + Fe2+ ??? Fe3+ + HO- + HO??). Suwannee River fulvic acid and humic acid were used as NOM. The most likely mechanism for the observed inhibition is that hydroxyl radical formation occurs in microenvironmental sites remote from the aromatic compounds. In addition to changes in kinetics, pyrene hydroxyl radical reaction also exhibited a mechanistic change in the presence of fulvic acid. The mechanism changed from a reaction that was apparently firstorder in pyrene to one that was apparently secondorder in pyrene, indicating that pyrene self-reaction may have become the dominant mechanism in the presence of fulvic acid. Dissolved NOM causes significant changes in the rate and mechanism of hydroxyl radical degradation of aromatic compounds. Consequently, literature rate constants measured in pure water will not be useful for predicting the degradation of pollutants in environmental systems. The kinetic and mechanistic information in this study will be useful for developing improved degradation methods involving Fenton chemistry.Reaction of aromatic compounds with hydroxyl radical is inhibited by dissolved natural organic matter (NOM). The degree of inhibition is significantly greater than that expected based on a simple model in which aromatic compounds molecules bounds to NOM are considered to be unreactive. In this study, hydroxyl radical was produced at steady-state concentrations using Fenton chemistry (H2O2 + Fe2+ ??? Fe3+ + HO- + HO??). Suwannee River fulvic acid and humic acid were used as NOM. The most likely mechanisms for the observed inhibition is that hydroxyl radical formation occurs in microenvironmental sites remote from the aromatic compounds. In addition to changes in kinetics, pyrene hydroxyl radical reaction also exhibited a mechanistic change in the presence of fulvic acid. The mechanism changed from a reaction that was apparently first-order in pyrene to one that was apparently second-order in pyrene, indicating that pyrene self-reaction may have become the dominant mechanism in the presence of fulvic acid. Dissolved NOM causes significant changes in the rate and mechanism of hydroxyl radical degradation of aromatic compounds. Consequently, literature rate constants measured in pure water will not be useful for predicting the degradation of pollutants in environmental systems. The kinetic and mechanistic information in this study will be useful for developing improved degradation methods involving Fenton chemistry.

Environmental Science & Technology↗
USGS2022

Surface-water-quality data to support implementation of revised freshwater aluminum water-quality criteria in Massachusetts, 2018–19

The U.S. Geological Survey, in cooperation with the Massachusetts Department of Environmental Protection, performed a study to inform the development of the department’s guidelines for the collection and use of water-chemistry data to support calculation of site-dependent aluminum criteria values. The U.S. Geological Survey collected and analyzed discrete water-quality samples at four wastewater-treatment facilities and seven water-treatment facilities in eastern and central Massachusetts from April 2018 through May 2019. For each of the 11 facilities considered, water-quality samples were collected from treatment-plant effluent and receiving-water bodies. Samples were collected for laboratory analysis of major ions (calcium and magnesium ions are used to calculate total hardness), dissolved organic carbon (DOC), total organic carbon (TOC), and total recoverable aluminum. Field parameters for pH, temperature, and specific conductance were measured in situ concurrently with sample collection. Water-quality conditions differed among monitoring stations. The highest pH values were observed for stations on the Assabet River that receive effluent discharges from wastewater-treatment facilities (the Westborough, Marlborough, Hudson, and Maynard wastewater-treatment facilities). High DOC concentrations (greater than 10 mg/L) were measured in water bodies associated with large areas of riparian wetlands—Lily Pond (Cohasset) and Third Herring Brook (Hanover), and low DOC concentrations (less than 2.5 mg/L) were measured at three water bodies in central Massachusetts—Hocomonco Pond (Westborough), Wyman Pond (Fitchburg), and Monoosnoc Brook (Leominster). Wyman Pond (Fitchburg), Monoosnoc Brook (Leominster), and Lily Pond (Cohasset) also had low pH values and low total hardness concentrations. The monthly discrete pH, DOC, and total hardness data for selected stations on receiving-water bodies were used in the U.S. Environmental Protection Agency Aluminum Criteria Calculator Version 2.0 to estimate site-dependent total recoverable aluminum concentrations that—if not exceeded—would be expected to protect fish, invertebrates, and other aquatic life from adverse effects associated with acute and chronic aluminum exposures. The U.S. Environmental Protection Agency Calculator output provides values for the acute criterion, defined as the criterion maximum concentration (CMC), an estimate of the highest aluminum concentration in surface water to which an aquatic community can be exposed briefly without resulting in an unacceptable effect. This output also provides values for the chronic criterion, defined as the criterion continuous concentration (CCC), an estimate of the highest concentration of aluminum in surface water to which an aquatic community can be exposed indefinitely without resulting in an unacceptable effect. To determine aluminum criteria values typically evaluated for use as protective water-quality criteria, the monthly instantaneous CMC and CCC values were used to calculate the minimum, 5th percentile, and 10th percentile CMC and CCC values for selected monitoring stations. The monthly instantaneous aluminum CMC and CCC values generated using the EPA Calculator varied among stations. Aluminum CMC and CCC values were highest for four ambient (upstream) stations on the Assabet River associated with wastewater-treatment facilities (Westborough, Marlboro, Hudson, and Maynard). Aluminum CMC and CCC values were lower for stations associated with water-treatment facilities, and lowest for selected ambient stations on Lily Pond, Monoosnoc Brook, and Wyman Pond associated with water-treatment facilities in Cohasset, Leominster, and Fitchburg, respectively. For many stations, the highest CMC and CCC instantaneous aluminum criteria values generated using the U.S. Environmental Protection Agency Calculator were for months during the growing season for algae and aquatic macrophytes (April or May through September or October) and the lowest values were for months during the nongrowing season (October or November through March or April), indicating the importance of collecting water-quality data during the nongrowing season. Aluminum CMC and CCC values generated by the U.S. Environmental Protection Agency Calculator are sensitive to variations in the input parameters (pH, DOC, and total hardness). Aluminum solubility is particularly affected by pH. To characterize diel and seasonal variations in pH, multiparameter water-quality monitors recording continuous (15-minute interval) water temperature and pH were installed in the receiving-water body for one station near each facility upstream from the effluent discharge (in rivers) or at a station outside the immediate effect of effluent discharge (in ponds). Continuous water temperature and pH data were collected from April or May 2018 through November or December 2018. Continuous pH data indicated that the pond stations and Assabet River stations had large diel variations in pH during the growing season. Continuous pH data were used together with discrete DOC and total hardness data to evaluate the potential effect of diel variations in pH on calculated site-dependent aluminum criteria values. For the 11 stations, diel variations in pH were determined to correspond to differences in the 10th percentile of CMC values by a median of 160 μg/L, ranging from 0 to 610 μg/L, and differences in the 10th percentile of CCC values by a median of 40 μg/L, ranging from 15 to 210 μg/L. The low monthly instantaneous CMC and CCC values that have the greatest effect on the minimum, 5th percentile, and 10th percentile aluminum values tend to result during the nongrowing season (October or November through March or April) when the range of diel variations in pH is small, thus minimizing the effect of diel variations in pH on the lowest CMC and CCC values. Historical water-quality data on organic carbon in Massachusetts streams were investigated using data retrieved from the USGS National Water Information System database. An assessment of the availability of historical pH, DOC, and hardness data indicated that more data were available for TOC than for DOC. A linear regression equation was developed for the relation between DOC and TOC concentrations to inform the potential use of available data to evaluate water-quality conditions at additional sites across Massachusetts where only pH, hardness, and TOC data are available. DOC and TOC concentrations were well correlated in the 223 samples in which both constituents were analyzed, and the equation had a coefficient of determination ( R 2 ) equal to 0.93.

Massachusetts↗
USGS2024

Environmental change drivers reduce sapling layer diversity in sugar maple-beech forests of aastern North America

A century of beech bark disease (BBD) in North America has transformed hardwood forests by reducing the canopy biomass of American beech ( Fagus grandifolia ), even as beech has come to dominate the sapling layer of many forests. We do not understand the extent to which environmental change drivers such as climate, acidic atmospheric deposition (and its legacy of acidified soils), and invasive disease (BBD) may have contributed to this transformation. We investigated how BBD effects and tree community composition varied along a well-documented soil acidity gradient in the northeastern United States. We surveyed overstory and sapling layer tree species composition, BBD effects, and soil chemistry on 30 watersheds in forests co-dominated by beech and sugar maple ( Acer saccharum ). We analyzed potential drivers of community composition, BBD, and beech sapling density using linear models and non-metric multidimensional scaling. Predictors accounted for soil chemistry, climate, overstory beech (importance value, IV), mortality, and BBD defect. Overall overstory species composition varied most along the acidity gradient, while beech and BBD severity varied along their own distinct environmental gradient. Species composition of the overstory and sapling layers diverged significantly, with the latter dominated by beech. Beech sapling density was positively related to the proportion of standing dead overstory beech and soil exchangeable aluminum, but was unrelated to the overall proportion of overstory beech or their BBD severity. The dominance of sapling layers by beech may have resulted from a gradual accumulation of canopy-opening events precipitated by BBD and sugar maple decline, the latter driven by stressors such as acidification and climate change.

New York↗
USGS2011

Effects of acid deposition on ecosystems: Advances in the state of the science

Chapter 2 focused on the environmental results of the ARP, presenting data from national monitoring networks on SO2 and NOx emissions, air quality, atmospheric deposition, surface water chemistry, and visibility. This chapter expands on this information by examining the most recent research into how ecosystems respond to acid deposition, especially the processes that control the recovery of ecosystems as acid deposition decreases. In Chapter 2, two general trends were discussed regarding the current recovery status of affected ecosystems: (1) these ecosystems are trending generally towards recovery, but improvements in ecosystem condition shown by surface water chemistry monitoring data thus far have been less than the improvements in deposition; and (2) ecosystem impacts and trends vary widely by geographic region, but the evidence of improvement is strongest and most evident in the Northeast. These trends are not uniform across the United States, however, and in some regions (e.g., central Appalachian Mountain region), trends in improved water quality are generally not evident. Despite the strong link in many areas between reduced emissions and reduced acidity of atmospheric deposition, the link is less clear between reduced acidity and recovery of the biological communities that live in aquatic and terrestrial ecosystems that have experienced deleterious effects from acid deposition. The recovery of these communities is proceeding at a slower pace than, for example, the improvements in stream and lake ANC would indicate. The goal of this chapter is to synthesize the science in a weightof-evidence manner to provide policy makers with tangible evidence and likely causative factors regarding ecosystem status and recovery patterns to date. This chapter serves as an update to the 2005 NAPAP RTC (NSTC, 2005), with an emphasis on scientific studies and monitoring since 2003, which was the last year for consideration of research results in the 2005 report. Several issues pertinent to ecosystem response to emission controls and acid deposition are receiving increasing attention in the scientific literature and will be discussed in this chapter, including the (1) observed delay in ecosystem recovery in the eastern United States, even with decreases in emissions and deposition over the past 30 years; (2) emerging ecosystem impacts of nitrogen deposition in the western United States; (3) the application of critical deposition loads as a tool for scientists to better inform air quality policies; (4) the role of changes in climate and the carbon cycle as factors that affect the response of ecosystems to acid deposition; and (5) the interaction of multiple pollutants in ecosystems. Throughout this chapter, the value of long-term environmental monitoring data in informing air quality policy will be highlighted, including the limitations of assessing the current status of some ecosystem indicators for which continuous, long-term data are lacking.

Report↗
USGS2015

Characterization of water-quality and bed-sediment conditions in Currituck Sound, North Carolina, prior to the Mid-Currituck Bridge construction, 2011–15

The North Carolina Turnpike Authority, a division of the North Carolina Department of Transportation, is planning to make transportation improvements in the Currituck Sound area by constructing a two-lane bridge from U.S. Highway 158 just south of Coinjock, North Carolina, to State Highway 12 on the Outer Banks just south of Corolla, North Carolina. The results of the Final Environmental Impact Study associated with the bridge and existing roadway improvements indicated potential water-quality and habitat impacts to Currituck Sound related to stormwater runoff, altered light levels, introduction of piles as hard substrate, and localized turbidity and siltation during construction. The primary objective of this initial study phase was to establish baseline water-quality conditions and bed-sediment chemistry of Currituck Sound in the vicinity of the planned alignment of the Mid-Currituck Bridge. These data will be used to evaluate the impacts associated with the bridge construction and bridge deck stormwater runoff. Between 2011 and 2015, discrete water-quality samples were collected monthly and after selected storm events from five locations in Currituck Sound. The sampling locations were distributed along the proposed alignment of the Mid-Currituck Bridge. Water samples were analyzed for physical parameters and water-quality constituents associated with bridge deck stormwater runoff and important in identifying impaired waters designated as &ldquo;SC&rdquo; (saltwater-aquatic life propagation/ protection and secondary recreation) under North Carolina&rsquo;s water-quality classifications. Bed-sediment chemistry was also measured three times during the study at the five sampling locations. Continuous water-level and wind speed and direction data in Currituck Sound were also collected by the U.S. Geological Survey during the study period. For the water samples, measured concentrations were greater than water-quality thresholds on 52 occasions. In addition, there were 190 occurrences of censored results having a reporting level higher than specific thresholds. All 52 occurrences of concentrations greater than water-quality thresholds were confined to seven different physical properties or constituents, namely pH (25), turbidity (8), total recoverable chromium (6), total recoverable copper (6), dissolved copper (3), total recoverable mercury (2), and total recoverable nickel (2). Concentrations of 17 other constituents were never measured to be greater than their established water-quality thresholds during the study. The focus of the water-quality characterization was on concentrations of constituents identified as parameters of concern in a 2011 collaborative U.S. Geological Survey/North Carolina Department of Transportation study that characterized bridge deck stormwater runoff across North Carolina. The occurrence and distribution of parameters of concern identified in the 2011 study, including pH, nutrients, total recoverable and dissolved metals, and polycyclic aromatic hydrocarbons, and some additional pertinent physical properties (dissolved oxygen, specific conductance, and turbidity), were analyzed in water and bed-sediment samples. Statistical differences were identified between monthly and storm samples for the following physical properties and constituents: pH, dissolved oxygen, specific conductance, turbidity, Escherichia coli bacteria, total recoverable aluminum, and total recoverable iron. Seasonality was observed in pH, specific conductance, dissolved oxygen, turbidity, total phosphorus, and total nitrogen, and total recoverable aluminum, arsenic, iron, lead, and manganese during the study period. The volume and residence time of the water in Currituck Sound are such that the water chemistry is relatively uniform spatially, but variable temporally. One of the most variable constituents in bed sediments was the fraction of fines, those sediments less than 63 micrometers in diameter. Because most, if not all, of the measured constituents were presumably associated with this fraction, bulk-sediment concentrations are determined largely by the amount of fines present. Only four constituents were greater than bed-sediment thresholds: tin (5 samples), barium (4 samples), aluminum (2 samples), and diethyl phthalate (1 sample). The occurrences of concentrations being greater than referenced thresholds could be underestimated for diethyl phthalate, because the reporting level exceeded the threshold in nine samples. Thirty-five constituents had sampled concentrations that were never greater than quality thresholds, although 21 of these constituents (154 instances) had at least one sample with a reporting level that was greater than the corresponding threshold. Finally, 33 constituents had no quality thresholds. This study and previous studies of bed-sediment quality in Currituck Sound, although few, indicate that sedimentation in Currituck Sound near the proposed alignment of the MidCurrituck Bridge is characterized overall by low and transient input, frequent wind-driven resuspension, and little long-term deposition of fines. To the extent that it might alter water depths along the alignment, bridge construction might also alter the deposition and resuspension rates of fine sediments in Currituck Sound in the vicinity of the bridge. The characterization of water-quality and bed-sediment chemistry in Currituck Sound along the proposed alignment of the Mid-Currituck Bridge summarized herein provides a baseline for determining the effect of bridge construction and bridge deck runoff on environmental conditions in Currituck Sound.

North Carolina↗
USGS2024

Paleosols in loess deposits

Paleosols , in loess or other deposits, are soils of the past. Three types can be recognized, buried, exhumed (once buried, but now at the surface), and relict (not buried, but formed under a different environment in the past). In loess deposits, paleosols have stratigraphic significance as they represent times of minimal or no loess accumulation. In many parts of the world, loess-derived paleosols mark interglacial periods, but in other regions, loess accumulation and soil formation are competing processes that occur together during both glacial and interglacial periods. Identification of paleosols within loess sequences can be accomplished by recognition of soil morphological properties (A and B horizons), zones of pedogenic clay accumulation, zones of carbonate loss (humid regions) or carbonate gain (arid regions), distinct phosphorus depth functions, and magnetic properties. Once recognized, paleosols can serve not only as valuable stratigraphic markers, but can help in reconstructing past environmental conditions, particularly climate and vegetation. Such goals can be accomplished by determination of degree of chemical weathering in paleosols from chemistry and mineralogy, carbon isotopic composition of paleosol organic matter, phytoliths, and magnetic properties.

Book chapter↗
USGS2011

Understanding processes affecting mineral deposits in humid environments

Recent interdisciplinary studies by the U.S. Geological Survey have resulted in substantial progress toward understanding the influence that climate and hydrology have on the geochemical signatures of mineral deposits and the resulting mine wastes in the eastern United States. Specific areas of focus include the release, transport, and fate of acid, metals, and associated elements from inactive mines in temperate coastal areas and of metals from unmined mineral deposits in tropical to subtropical areas; the influence of climate, geology, and hydrology on remediation options for abandoned mines; and the application of radiogenic isotopes to uniquely apportion source contributions that distinguish natural from mining sources and extent of metal transport. The environmental effects of abandoned mines and unmined mineral deposits result from a complex interaction of a variety of chemical and physical factors. These include the geology of the mineral deposit, the hydrologic setting of the mineral deposit and associated mine wastes, the chemistry of waters interacting with the deposit and associated waste material, the engineering of a mine as it relates to the reactivity of mine wastes, and climate, which affects such factors as temperature and the amounts of precipitation and evapotranspiration; these factors, in turn, influence the environmental behavior of mineral deposits. The role of climate is becoming increasingly important in environmental investigations of mineral deposits because of the growing concerns about climate change.

Fact Sheet↗
USGS2014

Dendrochemical patterns of calcium, zinc, and potassium related to internal factors detected by energy dispersive X-ray fluorescence (EDXRF)

Energy dispersive X-ray fluorescence (EDXRF) provides highly sensitive and precise spatial resolution of cation content in individual annual growth rings in trees. The sensitivity and precision have prompted successful applications to forensic dendrochemistry and the timing of environmental releases of contaminants. These applications have highlighted the need to distinguish dendrochemical effects of internal processes from environmental contamination. Calcium, potassium, and zinc are three marker cations that illustrate the influence of these processes. We found changes in cation chemistry in tree rings potentially due to biomineralization, development of cracks or checks, heartwood/sapwood differentiation, intra-annual processes, and compartmentalization of infection. Distinguishing internal from external processes that affect dendrochemistry will enhance the value of EDXRF for both physiological and forensic investigations.

Chemosphere↗
USGS1999

Environmental characteristics and water quality of hydrologic benchmark network stations in the Eastern United States, 1963-95

The information in this report was compiled to aid in the application and interpretation of historical water-quality data collected as part of the U.S. Geological Survey Hydrologic Benchmark Network program, which was established in 1963 to provide long-term measurements of streamflow and water quality in areas that are minimally affected by human activities. This report describes the environmental characteristics and water quality at 16 benchmark basins in the Eastern United States. In most of the basins, stream-water chemistry seems to be controlled by the interaction of acidic precipitation with the underlying soils and bedrock. Land use had a minimal effect on stream-water chemistry at most of the gaging stations.

Circular↗
USGS2004

Geochemical characterization of ground-water flow in the Santa Fe Group aquifer system, Middle Rio Grande Basin, New Mexico

Chemical and isotopic data were obtained from ground water and surface water throughout the Middle Rio Grande Basin (MRGB), New Mexico, and supplemented with selected data from the U.S. Geological Survey (USGS) National Water Information System (NWIS) and City of Albuquerque water-quality database in an effort to refine the conceptual model of ground-water flow in the basin. The ground-water data collected as part of this study include major- and minor-element chemistry (30 elements), oxygen-18 and deuterium content of water, carbon-13 content and carbon-14 activity of dissolved inorganic carbon, sulfur-34 content of dissolved sulfate, tritium, and dissolved atmospheric gases including nitrogen, argon, helium, chlorofluorocarbons, and sulfur hexafluoride from 288 wells and springs in parts of the Santa Fe Group aquifer system. The surface-water data collected as part of this study include monthly measurements of major- and minor-element chemistry (30 elements), oxygen-18 and deuterium content of water, chlorofluorocarbons, and tritium content at 14 locations throughout the basin. Additional data include stable isotope analyses of precipitation and of ground water from City of Albuquerque production wells collected and archived from the early 1980?s, and other data on the chemical and isotopic composition of air, unsaturated zone air, plants, and carbonate minerals from throughout the basin. The data were used to identify 12 sources of water to the basin, map spatial and vertical extents of ground-water flow, map water chemistry in relation to hydrogeologic, stratigraphic, and structural properties of the basin, determine radiocarbon ages of ground water, and reconstruct paleo-environmental conditions in the basin over the past 30,000 years. The data indicate that concentrations of most elements and isotopes generally parallel the predominant north to south direction of ground-water flow. The radiocarbon ages of dissolved inorganic carbon in ground water range from modern (post-1950) to more than 30,000 years before present, and appear to be particularly well defined in the predominantly siliciclastic aquifer system. Major sources of water to the basin include (1) recharge from mountains along the north, east and southwest margins (median age 5,000-9,000 years); (2) seepage from the Rio Grande and Rio Puerco (median age 4,000-8,000 years), and from Abo and Tijeras Arroyos (median age 3,000-9,000 years); (3) inflow of saline water along the southwestern basin margin (median age 20,000 years); and (4) inflow along the northern basin margin that probably represents recharge from the Jemez Mountains during the last glacial period (median age 20,000 years). Water recharged from the Jemez Mountains during the last glacial period occurs at the water table in the central part of the basin and beneath younger recharge along the Rio Grande and the northern mountain front. In some parts of the basin, boundaries between hydrochemical zones appear to be near major faults that may affect ground-water flow. However, in other parts of the basin, such as along the east side of Albuquerque near the Sandia Fault zone, ground-water flow appears to be unaffected by major faults. Upward leakage of saline water occurs along some faults and can be a source of salinity and elevated arsenic concentrations in some ground water. A trough in the modern and predevelopment water table west of Albuquerque is centered along a zone of predominantly late Pleistocene age water through the center of the basin and is flanked and overlain along the trough boundary by water that infiltrated from the Rio Puerco on the west and the Rio Grande to the east. It is suggested that the groundwater trough is a relatively recent transient feature of the Santa Fe Group aquifer system. At Albuquerque, a distinct north-south boundary in deuterium content of ground water marks the division between recharge from the eastern mountain front and that from the Rio Grande.

New Mexico↗
USGS2009

The Effects of Urbanization and Other Environmental Gradients on Algal Assemblages in Nine Metropolitan Areas across the United States

The U.S. Geological Survey conducted studies from 2000 to 2004 to determine the effects of urbanization on stream ecosystems in nine major metropolitan study areas across the United States. Biological, chemical, and physical components of streams were assessed at 28 to 30 sites in each study area. Benthic algae were sampled to compare the degree to which algal assemblages correlated to urbanization, as characterized by an urban intensity index (UII), relative to other environmental gradients that function at either the watershed or reach scales. Ordination site scores were derived from principal components analyses of the environmental data to define environmental gradients at two spatial scales: (1) watershed-scale gradients that summarized (a) landscape modifications and (b) socioeconomic factors, and (2) reach-scale gradients that characterized (a) physical habitat and (b) water chemistry. Algal response was initially quantified by site scores derived from nonmetric multi-dimensional scaling ordinations of the algal assemblage data. The site scores were then correlated with a set of algal metrics of structure and function to help select specific indicators that would best represent changes in the algal assemblages and would infer ecological condition. The selected metrics were correlated to the UII and other environmental gradients. The results indicated that diatom-taxa in the assemblages were distinctly different across the nine study areas, likely due to physiographic differences across the country, but nevertheless, some algal metrics were applicable to all areas. Overall, the study results indicated that although the UII represented various landscape changes associated with urbanization across the country, the algal response was more strongly related to more specific factors generally associated with water quality measured within the stream reach.

Scientific Investigations Report↗
USGS2016

Response of fish assemblages to declining acidic deposition in Adirondack Mountain lakes, 1984–2012

Adverse effects of acidic deposition on the chemistry and fish communities were evident in Adirondack Mountain lakes during the 1980s and 1990s. Fish assemblages and water chemistry in 43 Adirondack Long-Term Monitoring (ALTM) lakes were sampled by the Adirondack Lakes Survey Corporation and the New York State Department of Environmental Conservation during three periods (1984–87, 1994–2005, and 2008–12) to document regional impacts and potential biological recovery associated with the 1990 amendments to the 1963 Clean Air Act (CAA). We assessed standardized data from 43 lakes sampled during the three periods to quantify the response of fish-community richness, total fish abundance, and brook trout ( Salvelinus fontinalis) abundance to declining acidity that resulted from changes in U.S. air-quality management between 1984 and 2012. During the 28-year period, mean acid neutralizing capacity (ANC) increased significantly from 3 to 30 μeq/L and mean inorganic monomeric Al concentrations decreased significantly from 2.22 to 0.66 μmol/L, yet mean species richness, all species or total catch per net night (CPNN), and brook trout CPNN did not change significantly in the 43 lakes. Regression analyses indicate that fishery metrics were not directly related to the degree of chemical recovery and that brook trout CPNN may actually have declined with increasing ANC. While the richness of fish communities increased with increasing ANC as anticipated in several Adirondack lakes, observed improvements in water quality associated with the CAA have generally failed to produce detectable shifts in fish assemblages within a large number of ALTM lakes. Additional time may simply be needed for biological recovery to progress, or else more proactive efforts may be necessary to restore natural fish assemblages in Adirondack lakes in which water chemistry is steadily recovering from acidification.

New York↗