Results for “Nature Methods” — Page 86

USGS2026

Rapid earthquake magnitude classification via P-wave strains from borehole strainmeters and Distributed Acoustic Sensing

Distributed Acoustic Sensing (DAS) offers a promising approach for earthquake early warning (EEW) in settings where seismic networks are costly to maintain. By repurposing fiber-optic cables as dense strainmeter arrays, DAS enables real-time earthquake detection wherever those fibers are accessible. However, poor azimuthal coverage and challenges in estimating magnitude from strain measurements remain key hurdles in applying for earthquake monitoring. Here, we develop a machine learning method to distinguish large (M≥5.4) earthquakes from smaller ones within the first 4 seconds of a strain waveform after a P-wave arrival without determining location. Using ensemble decision tree models trained on borehole strainmeter data (3.5≤M≤7.1) and tested on onshore DAS waveforms (including the 2024 M7 Offshore Cape Mendocino earthquake), we find that low-frequency (0.2–0.5 Hz) continuous wavelet transform coefficients are the strongest predictors of magnitude, in addition to strain amplitude. Both DAS and borehole strainmeters effectively capture long-period strain signals, making these findings valuable for EEW systems. Our method shows high precision compared to the real-time EEW system, ShakeAlert®, supporting the position that DAS is a viable technology for earthquake monitoring and magnitude classification.

California↗

USGS1992

Evaluation of the depth-integration method of measuring water discharge in large rivers

The depth-integration method of measuring water discharge makes a continuous measurement of the water velocity from the water surface to the bottom at 20 to 40 locations or verticals across a river. It is especially practical for large rivers where river traffic makes it impractical to use boats attached to taglines strung across the river or to use current meters suspended from bridges. This method has the additional advantage over the standard two- and eight-tenths method in that a discharge-weighted suspended-sediment sample can be collected at the same time. When this method is used in large rivers such as the Missouri, Mississippi and Ohio, a microwave navigation system is used to determine the ship's position at each vertical sampling location across the river, and to make accurate velocity corrections to compensate for shift drift. An essential feature is a hydraulic winch that can lower and raise the current meter at a constant transit velocity so that the velocities at all depths are measured for equal lengths of time. Field calibration measurements show that: (1) the mean velocity measured on the upcast (bottom to surface) is within 1% of the standard mean velocity determined by 9–11 point measurements; (2) if the transit velocity is less than 25% of the mean velocity, then average error in the mean velocity is 4% or less. The major source of bias error is a result of mounting the current meter above a sounding weight and sometimes above a suspended-sediment sampling bottle, which prevents measurement of the velocity all the way to the bottom. The measured mean velocity is slightly larger than the true mean velocity. This bias error in the discharge is largest in shallow water (approximately 8% for the Missouri River at Hermann, MO, where the mean depth was 4.3 m) and smallest in deeper water (approximately 3% for the Mississippi River at Vickbsurg, MS, where the mean depth was 14.5 m). The major source of random error in the discharge is the natural variability of river velocities, which we assumed to be independent and random at each vertical. The standard error of the estimated mean velocity, at an individual vertical sampling location, may be as large as 9%, for large sand-bed alluvial rivers. The computed discharge, however, is a weighted mean of these random velocities. Consequently the standard error of computed discharge is divided by the square root of the number of verticals, producing typical values between 1 and 2%. The discharges measured by the depth-integrated method agreed within ±5% of those measured simultaneously by the standard two- and eight-tenths, six-tenth and moving boat methods.

Journal of Hydrology↗

USGS2003

Comparison of artificial maturation of lignite in hydrous and nonhydrous conditions

The objectives of the study are to compare product compositions and yields generated from lignite artificially matured by open nonhydrous pyrolysis, closed nonhydrous pyrolysis, and hydrous pyrolysis. The pyrolysis products were fractionated into CO2, H2O, CH4, C2-C5, C8-C14, C14+ saturates, C14+ aromatics and NSOs (resins+asphaltenes). All three methods generated high and similar quantities of water during pyrolysis that ranged between 14.6 and 15.2 wt.% of the original lignite. As a result of this high water content generated by the lignite, the experiments with no added water are referred to as nonhydrous rather than anhydrous. Rock-Eval pyrolysis and elemental analyses were conducted on the recovered lignite after solvent extraction to determine their residual hydrocarbon generation potential and to plot their position in a van Krevelen diagram, respectively. Residual lignite from the closed nonhydrous and hydrous experiments showed relationships between vitrinite reflectance (%Ro) values and atomic H/C ratios that occurred within the fields observed for natural maturation of coal. Although no significant differences in the atomic H/C ratios were observed between closed nonhydrous and hydrous pyrolysis, the vitrinite reflectance values were on the average 0.2% Ro lower in the residual lignite from the nonhydrous experiments. The remaining hydrocarbon generation potential as determined by Rock-Eval pyrolysis of the residual lignite showed that the nonhydrous residuals had on the average 16 mg more hydrocarbon potential per gram of original lignite than the hydrous residuals. This suggests there is a better release of the pyrolysis products from the lignite network in the hydrous experiments once generation occurs. For gas generation, at maximum yields, open nonhydrous pyrolysis generates the most hydrocarbon gas (21.0 mg/g original lignite), which is 20% more than closed nonhydrous pyrolysis and 29% more than hydrous pyrolysis. Closed nonhydrous pyrolysis generates on the average 14% more gas than hydrous pyrolysis, but the proportionality of the generated hydrocarbon gases is essentially the same for both pyrolysis methods. At maximum yields, CO2 generation is greatest in hydrous pyrolysis (99.5 mg/g original lignite), with yields being 37 percent higher than closed nonhydrous pyrolysis and 26% higher than open nonhydrous pyrolysis. The maximum yields of C14+ products are highest and similar for open nonhydrous pyrolysis and hydrous pyrolysis (125.6 and 125.9 mg/g lignite, respectively), and are more than 70% higher than closed nonhydrous pyrolysis. This difference in the maximum yields of C14+ products can be explained by differences in the proportionality between either cracking reactions that result in liquid product and char formation or trapping of generated products within the coal network (cross-linking reactions). Maximum yields of C14+ aliphatics from hydrous experiments may not have been attained, but the maximums that were observed and their GC traces are similar for the three pyrolysis systems.

Organic Geochemistry↗

USGS2026

Developing a low-cost drone-based method for deploying and retrieving autonomous recording units in inaccessible areas

Autonomous Recording Units (ARUs) are increasingly used in research to support passive acoustic monitoring, but deployment in remote or inaccessible locations remains logistically challenging. Traditional manual placement is labor-intensive, time-consuming, potentially hazardous, and often limited to habitat edges, creating sampling biases and restricting spatial coverage. To address placement limitations in wetland systems, we developed and field-tested a low-cost, lightweight floating platform paired with a drone-based deployment and retrieval system. The drone-deployable ARU platform, constructed from inexpensive, off-the-shelf materials (~US $21 per unit), weighed ~560 g and was mounted with an ARU (AudioMoth) at ~1.2 m above water. The platform was designed for stability, portability, and compliance with Federal Aviation Administration Part 107 regulations. Field trials were conducted across 50 operations in various types of historical rice-field impoundments along the South Carolina coast, which provide critical habitat for secretive marsh birds such as rails (e.g ., Rallus, Laterallus , and Porzana ) and bitterns (e.g ., Botaurus and Ixobrychus ). All 50 deployments and retrievals were successful, demonstrating the robustness of the method under diverse hydrologic and vegetative conditions. Deployment times were significantly shorter than retrieval times (median 6 vs. 9 min), with retrieval requiring greater precision for hook engagement. Operation times scaled predictably with distance: deployment increased by 0.93 min/100 m (R 2 = 0.94) and retrieval by 1.17 min/100 m (R 2 = 0.95). No platform damage or displacement was observed, as emergent vegetation was likely providing natural anchoring. Our approach offers an affordable and effective solution for expanding ARU coverage in large, inaccessible wetlands, reducing sampling bias and enhancing biodiversity monitoring. With continued advances in drone payload capacity, battery endurance, and beyond-visual-line-of-sight flight regulations, our workflow could be adapted for deploying multi-sensor platforms (e.g., ARUs, eDNA samplers, water and air quality sensors, plant sample collectors, insect traps, and trail cameras) to support integrated biodiversity monitoring in challenging landscapes worldwide.

South Carollina↗

USGS2002

Sorption of N2 and EGME vapors on some soils, clays, and mineral oxides and determination of sample surface areas by use of sorption data

Vapor sorption isotherms of ethylene glycol monoethyl ether (EGME) at room temperature and isotherms of N2 gas at liquid nitrogen temperature were determined for various soils and minerals. The N2 monolayer capacities [Qm (N2)] were calculated from the BET equation and used to determine the surface areas. To examine whether EGME is an appropriate adsorbate for determination of surface areas, the apparent EGME monolayer capacities [Qm (EGME)ap] were also obtained by use of the BET equation. For sand, aluminum oxide, kaolinite, hematite, and synthetic hydrous iron oxide, which are relatively free of organic impurity and expanding/solvating minerals, the Qm (EGME)ap values are in good conformity with the corresponding Qm (N2) values and would give surface areas consistent with BET (N2) values. For other samples (Woodburn soil, a natural hydrous iron oxide, illite, and montmorillonite), the Qm (EGME)ap values overestimate the Qm (N2) values from a moderate to a large extent, depending on the sample. A high-organic-content peat shows a very small BET (N2) surface area; the EGME/ peat isotherm is linear and does not yield a calculation of the surface area. Large discrepancies between results of the two methods for some samples are attributed to the high solubility of polar EGME in soil organic matter and/ or to the cation solvation of EGME with solvating clays. The agreement for other samples is illustrative of the consistency of the BET method when different adsorbates are used, so long as they do not exhibit bulk penetration and/or cation solvation.

Environmental Science & Technology↗

USGS2026

Salt marsh establishment controlled by sediment availability, landscape position, and anthropogenic history

Anthropogenic actions have directly and indirectly modulated salt marsh extent globally. For example, direct actions such as draining and filling of marshes for agriculture were common before the early 20th century, while development on barrier islands has indirectly reduced the capacity of back-barrier marshes to evolve in response to coastal processes. Similarly, restoration efforts span a spectrum between direct actions such as hydrologic reconnection and sediment placement to indirect actions such as shoreline protection and facilitation of upland migration. With a combination of remote sensing and synoptic in-situ observations, we demonstrate that the vegetative establishment of two disparate salt marsh complexes are strongly linked to their access to external sediment supply, position in the coastal landscape, and anthropogenic history. A marsh complex fringing Delaware Bay, in a former agricultural reclamation area, was directly modified through re-introduction of tidal forcing; vegetative establishment occurred rapidly (3% y −1 increase in vegetative cover) due to a high flood-ebb suspended sediment differential (+32 mg l −1 ), indicating sediment import. The other marsh complex, behind a sand spit fronting the Atlantic Ocean, vegetated indirectly in response to updrift beach nourishment which provided a sheltered environment for expansion. The lower suspended sediment differential (+1.3 mg l −1 ) led to a slower vegetation establishment rate (1.7% y −1 ). The directly modified and restored complex responded more rapidly than the indirectly modified and restored complex due to sediment availability. Direct restoration may be more rapid than indirect methods, and reversing anthropogenic impacts is possible on relatively short timescales, if sufficient external sediment supply exists. Siting of restoration projects can therefore leverage external forcing to accelerate recovery and enhance resilience. In light of ongoing coastal transgression, these examples also demonstrate a potential difference in return-on-restoration-investment between back-barrier marshes undergoing coastal squeeze and estuarine fringing marshes that are naturally transgressing across the coastal landscape.

New Jersey↗

USGS2025

Genetic analysis of Missouri’s Topeka Shiners with implications for the propagation of understudied small-bodied freshwater fishes

Objective Best practices for conservation hatcheries to conserve genetic diversity and minimize adaptation to captivity have been established for decades, but how to apply them is not clear in every circumstance. As a growing number of aquatic species are propagated in captive settings, addressing the fit of these practices to each system will help managers operate optimally while conserving hatchery resources. Small-bodied freshwater fish present a unique set of traits compared with species that are typically considered for propagation (i.e., salmonids), including a patchy distribution within a watercourse. We examine the propagation and reintroduction program that supports the Topeka Shiner Miniellus topeka , an endangered minnow in the Midwestern USA. Methods We genotyped shiners from groups with different histories (two reintroduced, three captive, and two remnant populations) at 11 microsatellite loci and compared genetic diversity, genetic structure, effective population size, and evidence of population bottlenecks. We also looked at the breeding structure by genetically assigning hatchery-reared young ( n = 148) to candidate parents. Results We documented high levels of genetic structure among the two natural populations in our study. We also noted lower diversity and evidence of bottlenecks in hatchery-reared groups. However, hatcheries may support sufficient (>50) effective population sizes with minimal space. Conclusions Hatcheries may avoid bottlenecks in other small-bodied freshwater fish by collecting wild fish from a broad area and frequently incorporating them into the captive population. Within the hatchery, we emphasize the need to reduce generational overlap by stocking all production fish and/or subdividing the captive populations.

Missouri↗

USGS2013

Fate of process solution cyanide and nitrate at three Nevada gold mines inferred from stable carbon and nitrogen isotope measurements

Stable isotope methods have been used to identify the mechanisms responsible for cyanide consumption at three heap-leach operations that process Carlin-type gold ores in Nevada, U.S.A. The reagent cyanide had δ 15 N values ranging from -5 to -2‰ and δ 13C values from -60 to -35‰. The wide δ 13 C range reflects the use by different suppliers of isotopically distinct natural-gas feedstocks and indicates that isotopes may be useful in environmental studies where there is a need to trace cyanide sources. In heap-leach circuits displaying from 5 to 98% consumption of cyanide, barren-solution and pregnant-solution cyanide were isotopically indistinguishable. The similarity is inconsistent with cyanide loss predominantly by HCN offgassing (a process that in laboratory experiments caused substantial isotopic changes), but it is consistent with cyanide retention within the heaps as solids, a process that caused minimal isotopic changes in laboratory simulations, or with cyanide oxidation, which also appears to cause minimal changes. In many pregnant solutions cyanide was carried entirely as metal complexes, which is consistent with ferrocyanides having precipitated or cyano-complexes having been adsorbed within the heaps. It is inferred that gaseous cyanide emissions from operations of this type are less important than has generally been thought and that the dissolution or desorption kinetics of solid species is an important control on cyanide elution when the spent heaps undergo rinsing. Nitrate, nitrite and ammonium had δ 15 N values of 1-16‰. The data reflect isotopic fractionation during ammonia offgassing or denitrification of nitrate–particularly in reclaim ponds–but do not indicate the extent to which nitrate is derived from cyanide or from explosive residues.

Nevada↗

USGS1994

Analysis of larval trematode communities

We can compare natural communities with null models of communities to indicate how they differ from random assemblages of species (i.e., how much structure is present). However, because null models draw on observed values of species' prevalences, whatever structure already exists in natural communities affects the composition of a null model and weakens its comparative power. To address this, we developed formulae to estimate "pre—interactive" species prevalences permitting a more sensitive quantification of community structure. Nonetheless, if a null model deviates from the community that we base it on, it is difficult to separate the effects of heterogeneity in recruitment from competition. We have developed a method to test for each independently. Applying our analytical techniques to a well—studied guild of larval trematodes in the salt marsh snail Cerithidea californica revealed that competitive interactions among species were the most significant structuring force. Interestingly, spatial heterogeneity acted to significantly intensify species co—occurrences. This differs from previous studies, which argued that the isolating effects of spatial heterogeneity, not competition, structure these communities by reducing co—occurrences.

Ecology↗

USGS2024

U.S. Geological Survey climate science plan—Future research directions

Executive Summary Climate is the primary driver of environmental change and is a key consideration in defining science priorities conducted across all mission areas in the U.S. Geological Survey (USGS). Recognizing the importance of climate change to its future research agenda, the USGS’s Climate Science Steering Committee requested the development of a Climate Science Plan to identify future research directions. Subject matter experts from across the Bureau formed the USGS Climate Science Plan Writing Team, which convened in September 2022 to identify and outline the major climate science topics of future concern and develop an integrated approach to conducting climate science in support of the USGS and U.S. Department of the Interior missions. The resulting USGS Climate Science Plan identifies three major priorities under which USGS climate science proceeds: (1) characterize climate change and associated impacts, (2) assess climate change risks and develop approaches to mitigate climate change, and (3) provide climate science tools and support. The Climate Science Plan identifies 12 specific goals to achieve the outcomes of the three priorities. Conduct long-term, broad-scale, and multidisciplinary measurements and monitoring and research activities to define, quantify, and predict the impacts of climate change on natural and human systems; Provide leadership to standardize measuring, monitoring, reporting, and verifying greenhouse gas emissions, lateral carbon fluxes, and carbon sinks across lands managed by the U.S. Department of the Interior (DOI); Provide science capacity, training, tools, and infrastructure to Tribal partners; support Tribal-led science initiatives; Conduct climate change research in partnership with the broader climate science community; Develop improved data synthesis methods through collaborative and open science across mission areas and between the USGS and agency partners; Translate climate change impacts into risk assessments in support of risk management strategies; Develop new and improved risk assessments, models, and approaches for mitigating climate change, adapting to its impacts, and reducing uncertainties; design early warning systems for risk mitigation; Investigate climate change mitigation strategies and create decision science support tools to inform climate change mitigation and adaptation; Provide a framework that facilitates knowledge co-production needed to inform policy decisions; Provide access to USGS data and information through novel integration and visualization approaches; Build capacity within USGS and DOI through development of scientific training curricula; and Coordinate science and capacity building efforts broadly across the Federal Government. To achieve these goals, the USGS Climate Science Plan also outlines climate science guidelines—key elements for conducting climate-based research—as well as emerging opportunities to support successful climate science. The USGS Climate Science Plan provided in this circular will guide future research priorities and science-support investments, as well as continued development of the climate workforce for decades to come, ensuring that the USGS continues to serve as one of the Nation’s leading climate science agencies.

Circular↗

USGS2007

Regional geochemical results from the reanalysis of NURE stream sediment samples -- Eagle 3 degree quadrangle, east-central Alaska

This report presents reconnaissance geochemical data for a cooperative study in the Fortymile Mining District, east-central Alaska, initiated in 1997. This study has been funded by the U.S. Geological Survey (USGS) Mineral Resources Program. Cooperative funds were provided from various State of Alaska sources through the Alaska Department of Natural Resources. Results presented here represent the initial reconnaissance phase for this multidisciplinary cooperative study. In this phase, 239 sediment samples from the Eagle 3° Quadrangle of east-central Alaska, which had been collected and analyzed for the U.S. Department of Energy's National Uranium Resource Evaluation program (NURE) of the 1970's (Hoffman and Buttleman, 1996; Smith, 1997), are reanalyzed by newer analytical methods that are more sensitive, accurate, and precise (Arbogast, 1996; Taggart, 2002). The main objectives for the reanalysis of these samples were to establish lower limits of determination for some elements and to confirm the NURE data as a reliable predictive reconnaissance tool for future studies in Alaska's Eagle 3° Quadrangle. This study has wide implications for using the archived NURE samples and data throughout Alaska for future studies.

Alaska↗

USGS2013

Economic resilience through "One-Water" management

Disruption of water availability leads to food scarcity and loss of economic opportunity. Development of effective water-resource policies and management strategies could provide resiliance to local economies in the face of water disruptions such as drought, flood, and climate change. To accomplish this, a detailed understanding of human water use and natural water resource availability is needed. A hydrologic model is a computer software system that simulates the movement and use of water in a geographic area. It takes into account all components of the water cycle--“One Water”--and helps estimate water budgets for groundwater, surface water, and landscape features. The U.S. Geological Survey MODFLOW One-Water Integrated Hydrologic Model (MODFLOWOWHM) software and scientific methods can provide water managers and political leaders with hydrologic information they need to help ensure water security and economic resilience.

Open-File Report↗

USGS1970

Chromite deposits of the north-central Zambales Range, Luzon, Philippines

Peridotite and gabbro form an intrusive complex which is exposed over an area about 35 km wide and 150 km long in the center of the Zambales Range of western Luzon. The Zambales Complex is remarkable for its total known resources, mined and still remaining, of about 15 million metric tons of chromite ore. Twenty percent of Free World production was obtained from this area between 1950 and the end of 1964; in 1960 production reached a high of 606,103 metric tons of refractory-grade ore, mostly from the Coto mine near Masinloc, and 128,426 metric tons of metallurgical ore from the Acoje mine. The United States imports 80 to 90 percent of its refractory-grade chromite from the Philippines, and its basic refractory technology has been designed upon the chemical and physical characteristics of Coto high-alumina chromite ore. Continuation of this pattern will depend upon discovery of additional ore reserves to replace those depleted by mining. The Zambales Ultramafic Complex is of the alpine type in which lenticular or podiform deposits of chromite lie in peridotite or dunite, mostly near Contacts with gabbroic rocks. Layered structures, foliation, and lineation commonly are well developed and transect boundaries between major rock units, including chromite deposits, at any angle. Accordingly, these structures cannot be used as guides in exploration and mining as they are used in stratiform complexes such as the Bushveld, where chromite layers extend for many miles. Probably 90 percent of the known deposits in the Zambales Complex are located in two belts in its northern part. One zone containing high-aluminua refractory-grade deposits extends northeast from the Coto mine and Chromite Reservation No. I along a peridotite contact with olivine gabbro, and another of high-chromium metallurgical grade chromite extends south through the Zambales and Acoje properties, and swings westward around the south side of Mount Lanai along a peridotite contact with norite. The textures of ores, association of chromite with dunite as gangue and as halos, and the transecting nature of the layering, foliation, and lineation in relation to chromite, are similar in all deposits regardless of composition of the chromite mineral itself. Textures in chromite ores, and structural relationships between chromite deposits and country rocks, show that layering and related foliation and lineation were formed or modified by flowage. Gabbro is believed to form the upper part of the Complex in general. Geophysical methods have been rather unsuccessful in finding chromite in the Zambales Complex. Gravity surveys, in order to be successful, must correct for all features influencing gravity except for the chromite itself. Too often the uncertainties in position of rock units and in knowledge of rock densities or position of hidden geologic features (dikes, zones of alteration) preclude the possibility of making adequate corrections. Magnetic surveys have failed to reveal any magnetic patterns attributable to the presence of chromite. Exploration for chromite should be guided by the knowledge that chromite occurs only in certain geologic environments. Thus because nearly all known chromite deposits in the Zambales Complex lie in peridotite near the gabbro contact, search for chromite should be concentrated there. Likewise it is evident from structural evidence presented here that there is little relation between layering and distribution of either major rock units or chromite deposits. Thus one is not justified in using the layered structure to predict either the position or attitude of major rock unit contacts, or presence or position of chromite deposits. In such a productive complex it is geologically certain that unknown deposits still remain undiscovered. The most promising areas for exploration are near known groups of large deposits like Acoje and Chromite Reservation No. 1. Underground drilling has been very successful in finding buried tabular

Open-File Report↗

USGS1999

U.S. Geological Survey Toxic Substances Hydrology Program: Proceedings of the technical meeting, Charleston, South Carolina, March 8-12, 1999: Volume 1 (Part A)

This report contains papers presented at the seventh Technical Meeting of the U.S. Geological Survey (USGS), Toxic Substances Hydrology (Toxics) Program. The meeting was held March 8-12, 1999, in Charleston, South Carolina. Toxics Program Technical Meetings are held periodically to provide a forum for presentation and discussion of results of recent research activities. The objectives of these meetings are to: Present recent research results to essential stakeholders, Encourage synthesis and integrated interpretations among scientists with different expertise who are working on a contamination issue, and Promote exchange of ideas among scientists working on different projects and issues within the Toxics Program. The Proceedings is published in three volumes. Volume 1 contains papers that report on results of research on contamination from hard-rock mining. Results include research on contamination from hard rock mining in arid southwest alluvial basins, research on hard rock mining in mountainous terrain, and progress from the USGS Abandoned Mine Lands Initiative. This Initiative is designed to develop a watershed-based approach to characterize and remediate contamination from abandoned mine lands and transfer technologies to Federal land management agencies and stakeholders. Volume 2 contains papers on contamination of hydrologic systems and related ecosystems. The papers discuss research on the response of estuarine ecosystems to contamination from human activities. They include research on San Francisco Bay; mercury contamination of aquatic ecosystems; and investigation of the occurrence, distribution, and fate of agricultural chemicals in the Mississippi River Basin. This volume also contains results on development and reconnaissance testing of new methods to detect emerging contaminants in environmental samples. Volume 3 contains papers on subsurface contamination from point sources. The papers discuss research on: hydrocarbons and fuel oxygenates at gasoline release sites; ground-water contamination by crude oil; complex contaminant mixtures from treated wastewater discharges; waste disposal and subsurface transport of contaminants in arid environments; ground water and surface water affected by municipal landfill leachate; natural attenuation of chlorinated solvents; and characterizing flow and transport in fractured rock aquifers. In all, the more than 175 papers contained in this proceedings reflect the contributions of more than 350 scientists who are co-authors. These scientists are from across the USGS, as well as from universities, other Federal and State agencies, and industry.

Water-Resources Investigations Report↗

USGS1999

U.S. Geological Survey Toxic Substances Hydrology Program: Proceedings of the technical meeting, Charleston, South Carolina, March 8-12, 1999: Volume 2 (Part B)

This report contains papers presented at the seventh Technical Meeting of the U.S. Geological Survey (USGS), Toxic Substances Hydrology (Toxics) Program. The meeting was held March 8-12, 1999, in Charleston, South Carolina. Toxics Program Technical Meetings are held periodically to provide a forum for presentation and discussion of results of recent research activities. The objectives of these meetings are to: Present recent research results to essential stakeholders, Encourage synthesis and integrated interpretations among scientists with different expertise who are working on a contamination issue, and Promote exchange of ideas among scientists working on different projects and issues within the Toxics Program. The Proceedings is published in three volumes. Volume 1 contains papers that report on results of research on contamination from hard-rock mining. Results include research on contamination from hard rock mining in arid southwest alluvial basins, research on hard rock mining in mountainous terrain, and progress from the USGS Abandoned Mine Lands Initiative. This Initiative is designed to develop a watershed-based approach to characterize and remediate contamination from abandoned mine lands and transfer technologies to Federal land management agencies and stakeholders. Volume 2 contains papers on contamination of hydrologic systems and related ecosystems. The papers discuss research on the response of estuarine ecosystems to contamination from human activities. They include research on San Francisco Bay; mercury contamination of aquatic ecosystems; and investigation of the occurrence, distribution, and fate of agricultural chemicals in the Mississippi River Basin. This volume also contains results on development and reconnaissance testing of new methods to detect emerging contaminants in environmental samples. Volume 3 contains papers on subsurface contamination from point sources. The papers discuss research on: hydrocarbons and fuel oxygenates at gasoline release sites; ground-water contamination by crude oil; complex contaminant mixtures from treated wastewater discharges; waste disposal and subsurface transport of contaminants in arid environments; ground water and surface water affected by municipal landfill leachate; natural attenuation of chlorinated solvents; and characterizing flow and transport in fractured rock aquifers. In all, the more than 175 papers contained in this proceedings reflect the contributions of more than 350 scientists who are co-authors. These scientists are from across the USGS, as well as from universities, other Federal and State agencies, and industry.

Water-Resources Investigations Report↗

USGS1999

U.S. Geological Survey Toxic Substances Hydrology Program: Proceedings of the technical meeting, Charleston, South Carolina, March 8-12, 1999: Volume 3 (Part C)

This report contains papers presented at the seventh Technical Meeting of the U.S. Geological Survey (USGS), Toxic Substances Hydrology (Toxics) Program. The meeting was held March 8-12, 1999, in Charleston, South Carolina. Toxics Program Technical Meetings are held periodically to provide a forum for presentation and discussion of results of recent research activities. The objectives of these meetings are to: Present recent research results to essential stakeholders, Encourage synthesis and integrated interpretations among scientists with different expertise who are working on a contamination issue, and Promote exchange of ideas among scientists working on different projects and issues within the Toxics Program. The Proceedings is published in three volumes. Volume 1 contains papers that report on results of research on contamination from hard-rock mining. Results include research on contamination from hard rock mining in arid southwest alluvial basins, research on hard rock mining in mountainous terrain, and progress from the USGS Abandoned Mine Lands Initiative. This Initiative is designed to develop a watershed-based approach to characterize and remediate contamination from abandoned mine lands and transfer technologies to Federal land management agencies and stakeholders. Volume 2 contains papers on contamination of hydrologic systems and related ecosystems. The papers discuss research on the response of estuarine ecosystems to contamination from human activities. They include research on San Francisco Bay; mercury contamination of aquatic ecosystems; and investigation of the occurrence, distribution, and fate of agricultural chemicals in the Mississippi River Basin. This volume also contains results on development and reconnaissance testing of new methods to detect emerging contaminants in environmental samples. Volume 3 contains papers on subsurface contamination from point sources. The papers discuss research on: hydrocarbons and fuel oxygenates at gasoline release sites; ground-water contamination by crude oil; complex contaminant mixtures from treated wastewater discharges; waste disposal and subsurface transport of contaminants in arid environments; ground water and surface water affected by municipal landfill leachate; natural attenuation of chlorinated solvents; and characterizing flow and transport in fractured rock aquifers. In all, the more than 175 papers contained in this proceedings reflect the contributions of more than 350 scientists who are co-authors. These scientists are from across the USGS, as well as from universities, other Federal and State agencies, and industry.

Water-Resources Investigations Report↗

USGS2021

Accelerating ecological sciences from above: Spatial contrastive learning for remote sensing

The rise of neural networks has opened the door for automatic analysis of remote sensing data. A challenge to using this machinery for computational sustainability is the necessity of massive labeled data sets, which can be cost-prohibitive for many non-profit organizations. The primary motivation for this work is one such problem; the efficient management of invasive species -- invading flora and fauna that are estimated to cause damages in the billions of dollars annually. As an ongoing collaboration with the New York Natural Heritage Program, we consider the use of unsupervised deep learning techniques for dimensionality reduction of remote sensing images, which can reduce sample complexity for downstream tasks and decreases the need for large labeled data sets. We consider spatially augmenting contrastive learning by training neural networks to correctly classify two nearby patches of a landscape as such. We demonstrate that this approach improves upon previous methods and naive classification for a large-scale data set of remote sensing images derived from invasive species observations obtained over 30 years. Additionally, we simulate deployment in the field via active learning and evaluate this method on another important challenge in computational sustainability -- landcover classification -- and again find that it outperforms previous baselines.

Proceedings of the AAAI Conference on Artificial I↗

USGS2009

Ground-Water Quality Data in the Upper Santa Ana Watershed Study Unit, November 2006-March 2007: Results from the California GAMA Program

Ground-water quality in the approximately 1,000-square-mile Upper Santa Ana Watershed study unit (USAW) was investigated from November 2006 through March 2007 as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The GAMA Priority Basin project was developed in response to the Groundwater Quality Monitoring Act of 2001, and is being conducted by the U.S. Geological Survey (USGS) in cooperation with the California State Water Resources Control Board (SWRCB). The Upper Santa Ana Watershed study was designed to provide a spatially unbiased assessment of raw ground-water quality within USAW, as well as a statistically consistent basis for comparing water quality throughout California. Samples were collected from 99 wells in Riverside and San Bernardino Counties. Ninety of the wells were selected using a spatially distributed, randomized grid-based method to provide statistical representation of the study unit (grid wells). Nine wells were selected to provide additional understanding of specific water-quality issues identified within the basin (understanding wells). The ground-water samples were analyzed for a large number of organic constituents (volatile organic compounds [VOCs], pesticides and pesticide degradates, pharmaceutical compounds, and potential wastewater-indicator compounds), constituents of special interest (perchlorate, N-nitrosodimethylamine [NDMA], 1,4-dioxane, and 1,2,3-trichloropropane [1,2,3-TCP]), naturally occurring inorganic constituents (nutrients, major and minor ions, and trace elements), radioactive constituents, and microbial indicators. Naturally occurring isotopes (tritium, carbon-14, and stable isotopes of hydrogen and oxygen in water) and dissolved noble gases also were measured to help identify sources and ages of the sampled ground water. Dissolved gases, and isotopes of nitrogen gas and of dissolved nitrate also were measured in order to investigate the sources and occurrence of nitrate in the study unit. In total, nearly 400 constituents and water-quality indicators were investigated for this study. This study did not attempt to evaluate the quality of water delivered to consumers; after withdrawal from the ground, water typically is treated, disinfected, and (or) blended with other waters to maintain acceptable water quality. Regulatory thresholds apply to treated water that is served to the consumer, not to raw ground water. However, to provide some context for the results, concentrations of constituents measured in the raw ground water were compared with regulatory and non-regulatory health-based thresholds established by the U.S. Environmental Protection Agency (USEPA) and the California Department of Public Health (CDPH) and thresholds established for aesthetic concerns (secondary maximum contaminant levels, SMCL-CA) by CDPH. Volatile organic compounds (VOCs) were detected in more than 80 percent of USAW grid wells. Most VOCs detected were at concentrations far less than thresholds established for drinking water to protect human health; however, six wells had VOC concentrations above health-based thresholds. Twenty-four of the 85 VOCs investigated were detected in the study unit;11 were detected in more than 10 percent of the wells. The VOCs detected above health-based thresholds in at least one well were dibromochloropropane (DBCP), tetrachloroethene (PCE), trichloroethene (TCE), carbon tetrachloride, and 1,1-dichoroethene. Pesticide compounds were detected in more than 75 percent of the grid wells. However, of the 134 different pesticide compounds investigated, 13 were detected at concentrations greater than their respective long-term method detection limits, and only 7 compounds (all herbicides or herbicide degradates) were detected in more than 10 percent of the wells. No pesticide compound was detected above its health-based threshold, although thresholds exist for fewer than half of the pesticide compounds investigat

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