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Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

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At least 1,171 records · Page 65Linked to original sources
USGS2003

Natural remediation potential of arsenic-contaminated ground water

Migration of leachate from a municipal landfill in Saco, Maine has resulted in arsenic concentrations in ground water as high as 647 μg/L . Laboratory experimental data indicate the primary source of arsenic to be reductive dissolution of arsenic-enriched iron oxyhydroxides in the aquifer by organic carbon in landfill leachate. A core from an uncontaminated part of the aquifer yielded no dissolved iron or arsenic when leached with oxic ground water. Eluent ground water spiked with organic carbon in order to create reducing conditions mobilized both ferrous iron and arsenite from this core. The landfill was capped in early 1998 to eliminate the source of leachate. Cores from the contaminated portion of the aquifer were collected and leached with uncontaminated ground water in the laboratory to simulate natural remediation conditions. Data from these experiments show that significant concentrations of labile organic carbon have accumulated on aquifer solids, causing significant biological oxygen demand. In laboratory leaching experiments of the most contaminated core, the organic carbon caused complete consumption of the influent dissolved oxygen (6 mg/L) for 220 pore volumes. Arsenic leaching from contaminated cores rapidly decreased in concentration initially in response to flushing with uncontaminated ground water. Subsequent leaching produced more gradual decreases in dissolved arsenic concentrations, controlled by a combination of reductive dissolution of arsenic-enriched iron oxyhydroxides and adsorption/desorption. In leachate from the most contaminatedcore, arsenic concentrations exceeded the new United States Environmental Protection Agency drinking-water standard of 10 μg/L for more than 200 pore volumes. A geochemical model simulated the concentration of selected constituents as uncontaminated ground water eluted through contaminated aquifer solids. Concentrations of dissolved oxygen, arsenic, and iron, in leachate from one core were used to calibrate the model. This model was validated by successfully simulating constituent concentrations in leachate from cores collected from other contaminated areas of this aquifer.

Saco↗
USGS2020

Understanding nekton use of estuarine habitats in the northern Gulf of Mexico: Guidebook for natural resource managers and restoration practitioners

Without a comprehensive understanding of nekton use of key habitats across locations, natural resource managers and restoration practitioners in the northern Gulf of Mexico region lack a key tool to assist in their efforts to design, implement, and monitor effective coastal restoration and protection efforts in the decades to come. To address this need, Abt helped conduct a systematic literature review, data compilation, and meta-analysis to evaluate nekton use of estuarine habitats in the northern Gulf of Mexico.

Louisiana, Texas↗
USGS2020

Avian community responses to management of vegetation and water levels in restored wetlands at the Humacao Nature Reserve, Puerto Rico

Coastal wetlands of the Caribbean have been greatly reduced in area and quality, and information on wildlife responses to management is lacking. We applied wetland management practices (disking, control of water levels) in a site historically disturbed by Saccharum spp. (sugarcane) cultivation at the Humacao Nature Reserve, southeastern Puerto Rico, and evaluated avian community response. We conducted weekly bird surveys and nest searches on disked and non-disked plots within recently constructed impoundments. The avian community shifted from 16 upland dominated species pre-restoration, to 67 wetland-dependent species at the end of our study (2001–2002). Ordination analysis indicated avian guild use of plots varied with environmental variables. Bird species diversity was not influenced by treatment, month, or salinity levels but was influenced by water depth and vegetation cover. Bird abundance was influenced by water depth, but not by treatment, month, salinity or vegetation cover. Furthermore, water depths of 0.10–0.20 m and salinity of ≤15 ppt promoted habitat conditions suitable for a diverse wetland avian community. We located 268 nests of 8 wetland bird species and observed adults with young of various other waterbirds, including species of conservation concern such as Dendrocygna arborea (West Indian Whistling Duck) and Porzana flaviventer (Yellow-breasted Crake). Bird community responses suggest that management practices (i.e., soil disturbance and control of water levels) can improve wetland biodiversity in abandoned sugarcane fields of Puerto Rico. Moreover, these practices may benefit wetland biodiversity in other Caribbean islands with a similar history of land use and habitat degradation.

Humacao Nature Reserve↗
USGS1974

WATEQ, a computer program for calculating chemical equilibria of natural waters

The computer program, WATEQ, calculates the equilibrium distribution of inorganic aqueous species of major and important minor elements in natural waters using the chemical analysis and in situ measurements of temperature, pH, and redox potential. From this model, the states of reaction of the water with solid and gaseous phases are calculated. Thermodynamic stabilities of aqueous species, minerals, and gases have been selected from a careful consideration of all available experimental data. The program is written in PL-1 for IBM 360 computers.

Journal of Research of the U.S. Geological Survey↗
USGS1976

A simplified slope-area method for estimating flood discharges in natural channels

Discharge of a stream may be computed from the slope of the water surface, the cross-sectional area, and an estimate of channel roughness. This, the slope-area method, is widely used to compute flood peak discharges from high-water marks. Reliability of a computed discharge depends largely on the roughness coefficient, which must be estimated. This paper shows that results of comparable accuracy can be obtained from area and slope alone in natural channels; a roughness coefficient is not needed because roughness and slope are related. The estimating equation and suggestions for application of the simplified method are included.

Journal of Research of the U.S. Geological Survey↗
USGS2022

Klamath natural flow study, Upper Klamath Basin groundwater flow model

The purpose of the Upper Klamath Basin Groundwater Flow Model (UKBGFM) is to simulate groundwater conditions in the Upper Klamath Basin under historical and predevelopment conditions. The UKBGFM quantifies estimates of and changes in groundwater levels, storage, pumping, drainage flow to tile drains, evapotranspiration, and flow between the Upper Klamath Basin and neighboring basins. The quantifications of base flow to streams and seepage to and from lakes and reservoirs can be used as inputs to the RiverWare Mass Balance Model (Zagona and others, 2001), a companion model being developed as part of the Klamath Natural Flow Study (KNFS).

California, Oregon↗
USGS2023

Bridging the gap between mathematical biology and undergraduate education using applicable natural resource modeling

Mathematical biology is a wide field of study with many venues that undergraduate students can access through research. However, the topics of study for these students can be overwhelming, and many topics of study yield either only trivial results or abstract outcomes that are nonintuitive and diffcult to understand. We have used natural resource modeling, and more specifically, a partnership between academic researchers and federal scientists, as a bridge between undergraduate research and mathematical biology. Our collaboration is an interdisciplinary team that combines biology, mathematics, and statistics professors with government research scientists. As a team, we have mentored students through opportunities such as a Research Experiences for Undergraduates and other projects. In this article, we provide an overview of how we develop questions for undergraduates and outline two case studies, both of which resulted in peer reviewed journal articles. Last, we describe how we also transfer the results from these undergraduate projects to resource managers so the results may be applied to real world problems.

Letters in Biomathematics↗
USGS2025

Natural capital accounting on forested lands: An application to the Colorado River basin

This paper creates a first set of forest natural capital accounts and demonstrates how these accounts can be integrated with general equilibrium models of the economy. Focusing on the Colorado River Basin, we show that deforestation has direct implications for the forest industry and indirect impacts on the economy through water treatment costs and carbon stock. 327,000 acres of forest are projected to be lost to development by 2100, representing a loss of 1.3 million tons of carbon stored in forests. The direct economic impacts associated with forest loss are estimated to be over $30 million, with $28 million of that coming directly from the value of lost carbon.

Conference Paper↗
USGS2000

Natural remediation in the Great Lakes

Overall, the existence of stricter environmental laws during the last 30 years and a reduction in the manufacturing base in the Great Lakes has resulted in improvement in conditions in harbors, rivers, and nearshore waters. Problems remain, such as the inability to dredge certain harbors and remove sediments because of lack of disposal facilities for contaminated sediments. Because of the wide extent of of contaminated sediments in the Great Lakes, much work remains to be done to document the condition of contaminated areas and the degree to which remediation of these areas is occurring from biotic and abiotic natural processes.

Book chapter↗
USGS1999

Diversifying natural resources value measurements: The Trinity River study

An interdisciplinary team set out to establish the economic and social values of the Trinity River in northern California . This information was intended to support the Secretary of the Interior's decision on allocation of Trinity River flows . This team set out to measure the values of Trinity River flows , fishery resources , and rec reation amenities in several different ways . A survey was mailed to users of the Trinity River . This single instrument included economic measures ( willingness - to pay and costs incurred in visiting ) and social - psychological measures ( importance , satisfaction , and water allocation preferences ). A closely related survey measured several of these same values among west coast regional households . The results of these surveys were compiled , and the measured economic and social values were compared . We found that integrating economic and social value information pro vides a greater depth of understanding of the resource's value . In addition , this integration provides a more in - depth understanding through the quantitative and qualitative results that emerge.

Society and Natural Resources↗
USGS2009

Alternative natural gas contract and pricing structures and incentives of the LNG industry

Gas conversion to liquefied gas (LNG) and transport by LNG tankers is one option for meeting expanding gas consumption and for gas traded internationally. This paper examines the impact of the traditional gas contract provisions of indefinite pricing, market out price ceilings, and take‐or‐pay requirements on the profitability of LNG projects in the context of markets characterized by price and quantity uncertainty. Simulation experiments are used to examine and calibrate the effects of those provisions. The results provide guidance to operators, host countries and purchasers in structuring such contracts. The paper also assesses prospects of future expansion of world LNG capacity.

Natural Resources Forum↗