Groundwater/surface-water interactions in the Tunk, Bonaparte, Antoine, and Tonasket Creek Subbasins, Okanogan River Basin, North-Central Washington, 2008

USGS Publications Warehouse

Sumioka, S.S.; Dinicola, R.S.

2009-01-01

An investigation into groundwater/surface-water interactions in four tributary subbasins of the Okanogan River determined that streamflows and shallow groundwater levels beneath the streams varied seasonally and by location. Streamflows measured in June 2008 indicated net losses of streamflow along 10 of 17 reaches, and hydraulic gradients measured between streams and shallow groundwater indicated potential recharge of surface water to groundwater at 11 of 21 measurement sites. In September 2008, net losses of streamflow were indicated along 9 of 17 reaches, and potential recharge of surface water to groundwater was indicated at 18 of 21 measurement sites. The greatest losses of streamflow occurred near the confluences with the Okanogan River, likely due to the presence of thick layers of unconsolidated deposits in the flood plain of the Okanogan River. Based on available geologic information compiled from drillers' logs, a surficial geologic map, and streamflow records, the extensive and thick deposits of unconsolidated material in the Tunk and Bonaparte Creek subbasins are factors in sustaining the almost perennial streamflow in those creeks. The less extensive and generally thinner unconsolidated deposits in the Tonasket and Antoine subbasins are contributing factors to the occasional extended periods of zero flow (a dry stream channel) in those creeks. Even though groundwater withdrawals would affect streamflows, relatively low precipitation in the area, along with limited groundwater storage capacity and the presence of permeable, unconsolidated deposits underlying the stream channels, would likely lead to loss of surface water to the groundwater system without any withdrawals.

Simulating the effects of ground-water withdrawals on streamflow in a precipitation-runoff model

USGS Publications Warehouse

Zarriello, Philip J.; Barlow, P.M.; Duda, P.B.

2004-01-01

Precipitation-runoff models are used to assess the effects of water use and management alternatives on streamflow. Often, ground-water withdrawals are a major water-use component that affect streamflow, but the ability of surface-water models to simulate ground-water withdrawals is limited. As part of a Hydrologic Simulation Program-FORTRAN (HSPF) precipitation-runoff model developed to analyze the effect of ground-water and surface-water withdrawals on streamflow in the Ipswich River in northeastern Massachusetts, an analytical technique (STRMDEPL) was developed for calculating the effects of pumped wells on streamflow. STRMDEPL is a FORTRAN program based on two analytical solutions that solve equations for ground-water flow to a well completed in a semi-infinite, homogeneous, and isotropic aquifer in direct hydraulic connection to a fully penetrating stream. One analytical method calculates unimpeded flow at the stream-aquifer boundary and the other method calculates the resistance to flow caused by semipervious streambed and streambank material. The principle of superposition is used with these analytical equations to calculate time-varying streamflow depletions due to daily pumping. The HSPF model can readily incorporate streamflow depletions caused by a well or surface-water withdrawal, or by multiple wells or surface-water withdrawals, or both, as a combined time-varying outflow demand from affected channel reaches. These demands are stored as a time series in the Watershed Data Management (WDM) file. This time-series data is read into the model as an external source used to specify flow from the first outflow gate in the reach where these withdrawals are located. Although the STRMDEPL program can be run independently of the HSPF model, an extension was developed to run this program within GenScn, a scenario generator and graphical user interface developed for use with the HSPF model. This extension requires that actual pumping rates for each well be stored in a unique WDM dataset identified by an attribute that associates each well with the model reach from which water is withdrawn. Other attributes identify the type and characteristics of the data. The interface allows users to easily add new pumping wells, delete exiting pumping wells, or change properties of the simulated aquifer or well. Development of this application enhanced the ability of the HSPF model to simulate complex water-use conditions in the Ipswich River Basin. The STRMDEPL program and the GenScn extension provide a valuable tool for water managers to evaluate the effects of pumped wells on streamflow and to test alternative water-use scenarios. Copyright ASCE 2004.

Removal of surface lipids improves the functionality of commercial zein in viscoelastic zein-starch dough for gluten-free breadmaking

USDA-ARS?s Scientific Manuscript database

Maize prolamin (zein), together with starch, hydroxypropyl methylcellulose, sugar, salt, yeast and water can form wheat-like cohesive, extensible, viscoelastic dough when mixed above room temperature (e.g. 40 °C). This dough is capable of holding gas. However, it is excessively extensible, and when ...

Determining Which Dispersants Will Be Effective In Future Deepwater Oil Spills

EPA Science Inventory

Deepwater spills result in oil distributed from deep in the water column to the water surface. The objective of this study was to test eight of the available dispersants (including Corexit 9500A, which was used extensively on the 2010 Deepwater Horizon Spill) on South Louisiana C...

Application of chitosan-incorporated LDPE film to sliced fresh red meats for shelf life extension.

PubMed

Park, Su-il; Marsh, Kenneth S; Dawson, Paul

2010-07-01

Chitosan lactate was impregnated as an antimicrobial additive into low density polyethylene (LDPE) with different concentrations. The antimicrobial effectiveness was tested with three pathogenic bacteria, specifically Listeria monocytogenes, Escherichia coli and Salmonella enteritidis. Also, these chitosan incorporated films were applied on red meat surfaces to determine the effectiveness of chitosan on color shelf life extension and microbial growth inhibition. Chitosan was exposed to 0.1% peptone water containing the three pathogens in separate tests and inhibited microbial growth a higher levels with increasing concentration of chitosan in the film matrix. Oxygen permeability was not affected by the incorporation of chitosan, while the water vapor permeability increased with the addition of chitosan. Film elongation decreased with the addition of chitosan. When chitosan incorporated films were applied on fresh red meat, microorganisms on the meat surface were not inhibited but significant extension of red color shelf life were observed in refrigerated, sliced red meats. Copyright 2010 Elsevier Ltd. All rights reserved.

Effects of ocean acidification, warming and melting of sea ice on aragonite saturation of the Canada Basin surface water

NASA Astrophysics Data System (ADS)

Yamamoto-Kawai, M.; McLaughlin, F. A.; Carmack, E. C.

2011-02-01

In 2008, surface waters in the Canada Basin of the Arctic Ocean were found to be undersaturated with respect to aragonite. This is associated with recent extensive melting of sea ice in this region, as well as elevated sea surface temperature and atmospheric CO2 concentrations. We have estimated the relative contribution of each of these controlling factors to the calcium carbonate saturation state (Ω) from observations of dissolved inorganic carbon, total alkalinity and oxygen isotope ratio. Results indicate that the increase in atmospheric CO2 has lowered surface Ω by ˜0.3 in the Canada Basin since the preindustrial period. Recent melting of sea ice has further lowered mean Ω by 0.4, and of this, half was due to dilution of surface water and half was due to the change in air-sea disequilibrium state. Surface water warming has generally counteracted the mean decrease in Ω by 0.1.

The Extract of Roots of Sophora flavescens Enhances the Recovery of Motor Function by Axonal Growth in Mice with a Spinal Cord Injury.

PubMed

Tanabe, Norio; Kuboyama, Tomoharu; Kazuma, Kohei; Konno, Katsuhiro; Tohda, Chihiro

2015-01-01

Although axonal extension to reconstruct spinal tracts should be effective for restoring function after spinal cord injury (SCI), chondroitin sulfate proteoglycan (CSPG) levels increase at spinal cord lesion sites, and inhibit axonal regrowth. In this study, we found that the water extract of roots of Sophora flavescens extended the axons of mouse cortical neurons, even on a CSPG-coated surface. Consecutive oral administrations of S. flavescens extract to SCI mice for 31 days increased the density of 5-HT-positive axons at the lesion site and improved the motor function. Further, the active constituents in the S. flavescens extract were identified. The water and alkaloid fractions of the S. flavescens extract each exhibited axonal extension activity in vitro. LC/MS analysis revealed that these fractions mainly contain matrine and/or oxymatrine, which are well-known major compounds in S. flavescens. Matrine and oxymatrine promoted axonal extension on the CSPG-coated surface. This study is the first to demonstrate that S. flavescens extract, matrine, and oxymatrine enhance axonal growth in vitro, even on a CSPG-coated surface, and that S. flavescens extract improves motor function and increases axonal density in SCI mice.

Implementation of MAR within the Rio Grande Basin of Central New Mexico, USA

NASA Astrophysics Data System (ADS)

Marley, Robert; Blandford, T. Neil; Ewing, Amy; Webb, Larry; Yuhas, Katherine

2014-05-01

The U.S. Bureau of Reclamation has identified the Rio Grande basin within Central New Mexico as one of several regions where water supplies are over-allocated and future conflicts over the inadequate resource are highly likely. Local water providers have consistently identified managed aquifer recharge (MAR) as an important tool to provide conjunctive management of surface-water, groundwater, and reclaimed water sources in order to extend the useful life of existing water sources. However, MAR projects have been slow to take root partly due to rigorous demonstration requirements, groundwater quality protection concerns, and ongoing water right uncertainties. At first glance the several thousand meters of unconsolidated basin-fill sediments hosting the regional aquifer appear to provide an ideal environment for the subsurface storage of surplus water. However, the basin has a complex structural and depositional history that impacts the siting and overall effectiveness of MAR systems. Several recharge projects are now in various stages of implementation and are overcoming site specific challenges including source water and ambient groundwater compatibility, low-permeability sediments and compartmentalization of the aquifer by extensive faulting, well clogging, and overall water quality management. This presentation will highlight ongoing efforts of these water providers to develop full-scale recharge facilities. The performance of natural in-channel infiltration, engineered infiltration galleries, and direct injection systems designed to introduce from 500 to 5,000 mega-liters per annum to target intervals present from 150 to 600 meters below ground surface will be described. Source waters for recharge operations include inter-basin transferred surface water and highly treated reclaimed water sources requiring from minor to extensive treatment pre-recharge and post-recovery. Operational complexities have raised concerns related to long-term operation and maintenance and overall economic sustainability of these projects. Further, potential reduction in surface water return flows as a result of recharge operations and impacts to other water users during recovery of the stored water must be considered. Proposed rules for long-term storage, estimating water losses, and eventual water recovery as they relate to water rights administration within stream-connected aquifer systems will also be outlined during the presentation.

Field tracer investigation of unsaturated zone flow paths and mechanisms in agricultural soils of northwestern Mississippi, USA

USGS Publications Warehouse

Perkins, K.S.; Nimmo, J.R.; Rose, C.E.; Coupe, R.H.

2011-01-01

In many farmed areas, intensive application of agricultural chemicals and withdrawal of groundwater for irrigation have led to water quality and supply issues. Unsaturated-zone processes, including preferential flow, play a major role in these effects but are not well understood. In the Bogue Phalia basin, an intensely agricultural area in the Delta region of northwestern Mississippi, the fine-textured soils often exhibit surface ponding and runoff after irrigation and rainfall as well as extensive surface cracking during prolonged dry periods. Fields are typically land-formed to promote surface flow into drainage ditches and streams that feed into larger river ecosystems. Downward flow of water below the root zone is considered minimal; regional groundwater models predict only 5% or less of precipitation recharges the heavily used alluvial aquifer. In this study transport mechanisms within and below the root zone of a fallow soybean field were assessed by performing a 2-m ring infiltration test with tracers and subsurface monitoring instruments. Seven months after tracer application, 48 continuous cores were collected for tracer extraction to define the extent of water movement and quantify preferential flow using a mass-balance approach. Vertical water movement was rapid below the pond indicating the importance of vertical preferential flow paths in the shallow unsaturated zone, especially to depths where agricultural disturbance occurs. Lateral flow of water at shallow depths was extensive and spatially non-uniform, reaching up to 10. m from the pond within 2. months. Within 1. month, the wetting front reached a textural boundary at 4-5. m between the fine-textured soil and sandy alluvium, now a potential capillary barrier which, prior to extensive irrigation withdrawals, was below the water table. Within 10. weeks, tracer was detectable at the water table which is presently about 12. m below land surface. Results indicate that 43% of percolation may be through preferential flow paths and that any water breaking through the capillary barrier (as potential recharge) likely does so in fingers which are difficult to detect with coring methods. In other areas where water levels have declined and soils have similar properties, the potential for transport of agricultural chemicals to the aquifer may be greater than previously assumed. ?? 2010 .

Health risks from large-scale water pollution: trends in Central Asia.

PubMed

Törnqvist, Rebecka; Jarsjö, Jerker; Karimov, Bakhtiyor

2011-02-01

Limited data on the pollution status of spatially extensive water systems constrain health-risk assessments at basin-scales. Using a recipient measurement approach in a terminal water body, we show that agricultural and industrial pollutants in groundwater-surface water systems of the Aral Sea Drainage Basin (covering the main part of Central Asia) yield cumulative health hazards above guideline values in downstream surface waters, due to high concentrations of copper, arsenic, nitrite, and to certain extent dichlorodiphenyltrichloroethane (DDT). Considering these high-impact contaminants, we furthermore perform trend analyses of their upstream spatial-temporal distribution, investigating dominant large-scale spreading mechanisms. The ratio between parent DDT and its degradation products showed that discharges into or depositions onto surface waters are likely to be recent or ongoing. In river water, copper concentrations peak during the spring season, after thawing and snow melt. High spatial variability of arsenic concentrations in river water could reflect its local presence in the top soil of nearby agricultural fields. Overall, groundwaters were associated with much higher health risks than surface waters. Health risks can therefore increase considerably, if the downstream population must switch to groundwater-based drinking water supplies during surface water shortage. Arid regions are generally vulnerable to this problem due to ongoing irrigation expansion and climate changes. Copyright © 2010 Elsevier Ltd. All rights reserved.

Temperature-dependent daily variability of precipitable water in special sensor microwave/imager observations

NASA Technical Reports Server (NTRS)

Gutowski, William J.; Lindemulder, Elizabeth A.; Jovaag, Kari

1995-01-01

We use retrievals of atmospheric precipitable water from satellite microwave observations and analyses of near-surface temperature to examine the relationship between these two fields on daily and longer time scales. The retrieval technique producing the data used here is most effective over the open ocean, so the analysis focuses on the southern hemisphere's extratropics, which have an extensive ocean surface. For both the total and the eddy precipitable water fields, there is a close correspondence between local variations in the precipitable water and near-surface temperature. The correspondence appears particularly strong for synoptic and planetary scale transient eddies. More specifically, the results support a typical modeling assumption that transient eddy moisture fields are proportional to transient eddy temperature fields under the assumption f constant relative humidity.

Site of water vapor absorption in the desert cockroach, Arenivaga investigata.

PubMed Central

O'Donnell, M J

1977-01-01

The desert cockroach, Arenivaga investigata, can gain weight by absorption of water-vapor from unsaturated atmospheres above 82.5% relative humidity. Blocking the anus or the dorsal surface with wax does not prevent water vapor uptake, but interference with movements of the mouthparts or blocking the mouth with wax-prevents such uptake. Weight gains are associated with the protrusion from the mouth of two bladder-like extensions of the hypopharynx. During absorption these structures are warmer than the surrounding mouthparts, their surface temperature increasing with relative humidity. This suggests that the surfaces of the bladder-like structures function at least as sites for condensation of water vapor, but the precise location of its transfer into the hemolymph has not yet been identified. Images PMID:266217

Energy-switching potential energy surface for the water molecule revisited: A highly accurate singled-sheeted form.

PubMed

Galvão, B R L; Rodrigues, S P J; Varandas, A J C

2008-07-28

A global ab initio potential energy surface is proposed for the water molecule by energy-switching/merging a highly accurate isotope-dependent local potential function reported by Polyansky et al. [Science 299, 539 (2003)] with a global form of the many-body expansion type suitably adapted to account explicitly for the dynamical correlation and parametrized from extensive accurate multireference configuration interaction energies extrapolated to the complete basis set limit. The new function mimics also the complicated Sigma/Pi crossing that arises at linear geometries of the water molecule.

Occurrence, distribution and risks of antibiotics in urban surface water in Beijing, China.

PubMed

Li, Wenhui; Gao, Lihong; Shi, Yali; Liu, Jiemin; Cai, Yaqi

2015-09-01

The occurrence and distribution of 22 antibiotics, including eight fluoroquinolones, nine sulfonamides and five macrolides, were investigated in the urban surface waters in Beijing, China. A total of 360 surface water samples were collected from the main rivers and lakes in the urban area of Beijing monthly from July 2013 to June 2014 (except the frozen period). Laboratory analyses revealed that antibiotics were widely used and extensively distributed in the surface water of Beijing, and sulfonamides and fluoroquinolones were the predominant antibiotics with the average concentrations of 136 and 132 ng L(-1), respectively. A significant difference of antibiotic concentrations from different sampling sites was observed, and the southern and eastern regions of Beijing showed higher concentrations of antibiotics. Seasonal variation of the antibiotics in the urban surface water was also studied, and the highest level of antibiotics was found in November, which may be due to the low temperature and flow of the rivers during the period of cold weather. Risk assessment showed that several antibiotics might pose high ecological risks to aquatic organisms (algae and plants) in surface water, and more attention should be paid to the risk of antibiotics to the aquatic environment in Beijing.

Altered Landscapes and Groundwater Sustainability — Exploring Impacts with Induced Polarization, DC Resistivity, and Thermal Tracing

NASA Astrophysics Data System (ADS)

Eddy-Miller, C.; Caldwell, R.; Wheeler, J.; McCarthy, P.; Binley, A. M.; Constantz, J. E.; Stonestrom, D. A.

2009-12-01

Anthropogenically impacted landscapes constitute rising proportions of the Earth’s surface that are characterized by generally elevated nutrient and sediment loadings concurrent with increased consumptive water withdrawals. In recent years a growing number of hydraulically engineered riparian habitat restoration projects have attempted to ameliorate negative impacts of land use on groundwater-surface water systems resulting, e.g., from agricultural practices and urban development. Often the nature of groundwater-surface water interactions in pre- and minimally altered systems is poorly known, making it difficult to assess the impacts of land use and restoration projects on groundwater sustainability. Traditional assessments of surface water parameters (flow, temperature, dissolved oxygen, biotic composition, etc.) can be complemented by hydraulic and thermal measurements to better understand the important role played by groundwater-surface water interactions. Hydraulic and thermal measurements are usually limited to point samples, however, making non-invasive and spatially extensive geophysical characterizations an attractive additional tool. Groundwater-surface water interactions along the Smith River, a tributary to the Missouri River in Montana, and Fish Creek and Flat Creek, tributaries to the Snake River in Wyoming, are being examined using a combination of hydraulic measurements, thermal tracing, and electrical-property imaging. Ninety-two direct-current (DC) resistivity and induced polarization cross sections were obtained at stream transects covering a wide variety of hydrogeologic settings ranging from shallow bedrock to thick alluvial sequences, nature of groundwater-surface water interactions (always gaining, always losing, or seasonally varying) and anthropogenic impacts (minimal low-intensity agriculture to major landscape engineering, including channel reconstruction). DC resistivity and induced polarization delineated mutually distinct features related to hydraulic architecture. For example, induced polarization imaging resolved channel-edge muck deposits that are presumed to be sites of low hydraulic conductivity, chemical reduction, and metal accumulation. DC resistivity delineated bedrock-alluvium contacts and showed potential for tracking changes in salinization. While electrical properties cannot substitute for hydraulic and thermal data, the addition of relatively rapidly acquired, spatially extensive resistivity and induced polarization imaging offers synergistic opportunities for interpretive hydrologic investigations.

Global modeling of withdrawal, allocation and consumptive use of surface water and groundwater resources

NASA Astrophysics Data System (ADS)

Wada, Y.; Wisser, D.; Bierkens, M. F. P.

2013-02-01

To sustain growing food demand and increasing standard of living, global water withdrawal and consumptive water use have been increasing rapidly. To analyze the human perturbation on water resources consistently over a large scale, a number of macro-scale hydrological models (MHMs) have been developed over the recent decades. However, few models consider the feedback between water availability and water demand, and even fewer models explicitly incorporate water allocation from surface water and groundwater resources. Here, we integrate a global water demand model into a global water balance model, and simulate water withdrawal and consumptive water use over the period 1979-2010, considering water allocation from surface water and groundwater resources and explicitly taking into account feedbacks between supply and demand, using two re-analysis products: ERA-Interim and MERRA. We implement an irrigation water scheme, which works dynamically with daily surface and soil water balance, and include a newly available extensive reservoir data set. Simulated surface water and groundwater withdrawal show generally good agreement with available reported national and sub-national statistics. The results show a consistent increase in both surface water and groundwater use worldwide, but groundwater use has been increasing more rapidly than surface water use since the 1990s. Human impacts on terrestrial water storage (TWS) signals are evident, altering the seasonal and inter-annual variability. The alteration is particularly large over the heavily regulated basins such as the Colorado and the Columbia, and over the major irrigated basins such as the Mississippi, the Indus, and the Ganges. Including human water use generally improves the correlation of simulated TWS anomalies with those of the GRACE observations.

29 CFR Appendix C to Subpart Cc of... - Operator Certification: Written Examination: Technical Knowledge Criteria

Code of Federal Regulations, 2011 CFR

2011-07-01

.... (iv) Boom cages. (v) Proximity to electric power lines, radii, and microwave structures. (5) The...-in-place and tilt-up. (vi) Demolition operations. (vii) Operations on water. (viii) Magnet operations... extensions. (vi) Lifting loads from beneath the surface of the water. (vii) Using various approved...

29 CFR Appendix C to Subpart Cc of... - Operator Certification: Written Examination: Technical Knowledge Criteria

Code of Federal Regulations, 2014 CFR

2014-07-01

.... (iv) Boom cages. (v) Proximity to electric power lines, radii, and microwave structures. (5) The...-in-place and tilt-up. (vi) Demolition operations. (vii) Operations on water. (viii) Magnet operations... extensions. (vi) Lifting loads from beneath the surface of the water. (vii) Using various approved...

Nutrient Pumping/Advection by Propagating Rossby Waves in the Kuroshio Extension

DTIC Science & Technology

2010-01-01

sea-elevation changes or SLA variance levels are a maximum as eddies and meanders cross a mean route. This boundary in terms of Chl- a levels (lower...and elevated Chl- a levels ) is south of the KE jet. Kuroshio Extension meanders and rings carry different water types across a mean Kuroshio Extension...Fig. 5A). The ring or eddy currents may also redistribute the surface Chl- a levels , drawing out plumes of locally increased Chl-a from regions of

Modeling interactions of agriculture and groundwater nitrate contaminants: application of The STICS-Eau-Dyssée coupled models over the Seine River Basin

NASA Astrophysics Data System (ADS)

Tavakoly, A. A.; Habets, F.; Saleh, F.; Yang, Z. L.

2017-12-01

Human activities such as the cultivation of N-fixing crops, burning of fossil fuels, discharging of industrial and domestic effluents, and extensive usage of fertilizers have recently accelerated the nitrogen loading to watersheds worldwide. Increasing nitrate concentration in surface water and groundwater is a major concern in watersheds with extensive agricultural activities. Nutrient enrichment is one of the major environmental problems in the French coastal zone. To understand and predict interactions between agriculture, surface water and groundwater nitrate contaminants, this study presents a modeling framework that couples the agronomic STICS model with Eau-Dyssée, a distributed hydrologic modeling system to simulate groundwater-surface water interaction. The coupled system is implemented on the Seine River Basin with an area of 88,000 km2 to compute daily nitrate contaminants. Representing a sophisticated hydrosystem with several aquifers and including the megalopolis of Paris, the Seine River Basin is well-known as one of the most productive agricultural areas in France. The STICS-EauDyssée framework is evaluated for a long-term simulation covering 39 years (1971-2010). Model results show that the simulated nitrate highly depends on the inflow produced by surface and subsurface waters. Daily simulation shows that the model captures the seasonal variation of observations and that the overall long-term simulation of nitrate contaminant is satisfactory at the regional scale.

Water rights of the head reach farmers in view of a water supply scenario at the extension area of the Babai Irrigation Project, Nepal

NASA Astrophysics Data System (ADS)

Adhikari, B.; Verhoeven, R.; Troch, P.

The farmer managed irrigation systems (FMIS) represent those systems which are constructed and operated solely by the farmers applying their indigenous technology. The FMIS generally outperform the modern irrigation systems constructed and operated by the government agencies with regard to the water delivery effectiveness, agricultural productivity etc., and the presence of a sound organization responsible to run the FMIS, often referred to as the ‘social capital’, is the key to this success. This paper studies another important aspect residing in the FMIS: potentials to expand the irrigation area by means of their proper rehabilitation and modernization. Taking the case study of the Babai Irrigation Project in Nepal, it is demonstrated that the flow, which in the past was used to irrigate the 5400 ha area covered by three FMIS, can provide irrigation to an additional 8100 ha in the summer, 4180 ha vegetables in the winter and 1100 ha maize in the spring season after the FMIS rehabilitation. The “priority water rights” of the FMIS part have been evaluated based on relevant crop water requirement calculations and is found to be equal to 85.4 million m 3 per year. Consequently, the dry season irrigation strategy at the extension area could be worked out based on the remaining flow. By storing the surplus discharge of the monsoon and autumn in local ponds, and by consuming them in dry period combined with nominal partial irrigation practice, wheat and mustard can be cultivated over about 4000 ha of the extension area. Furthermore, storage and surface irrigation both contribute to the groundwater recharge. The conjunctive use of ground, surface and harvested water might be the mainstream in the future for a sustainable irrigation water management in the region.

Improvements in lake water budget computations using Landsat data

NASA Technical Reports Server (NTRS)

Gervin, J. C.; Shih, S. F.

1979-01-01

A supervised multispectral classification was performed on Landsat data for Lake Okeechobee's extensive littoral zone to provide two types of information. First, the acreage of a given plant species as measured by satellite was combined with a more accurate transpiration rate to give a better estimate of evapotranspiration from the littoral zone. Second, the surface area coupled by plant communities was used to develop a better estimate of the water surface as a function of lake stage. Based on this information, more detailed representations of evapotranspiration and total water surface (and hence total lake volume) were provided to the water balance budget model for lake volume predictions. The model results based on information derived from satellite demonstrated a 94 percent reduction in cumulative lake stage error and a 70 percent reduction in the maximum deviation of the lake stage.

Humidity-dependent compression-induced glass transition of the air–water interfacial Langmuir films of poly(D,L-lactic acid- ran-glycolic acid) (PLGA)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Hyun Chang; Lee, Hoyoung; Jung, Hyunjung

2015-08-26

Constant rate compression isotherms of the air–water interfacial Langmuir films of poly(D,L-lactic acid- ran-glycolic acid) (PLGA)show a distinct feature of an exponential increase in surface pressure in the high surface polymer concentration regime. We have previously demonstrated that this abrupt increase in surface pressure is linked to the glass transition of the polymer film, but the detailed mechanism of this process is not understood. In order to obtain a molecular-level understanding of this behavior, we performed extensive characterizations of the surface mechanical, structural and rheological properties of Langmuir PLGA films at the air–water interface, using combined experimental techniques including themore » Langmuir film balance, X-ray reflectivity and double-wall-ring interfacial rheometry methods.« less

Effects of including surface depressions in the application of the Precipitation-Runoff Modeling System in the Upper Flint River Basin, Georgia

USGS Publications Warehouse

Viger, Roland J.; Hay, Lauren E.; Jones, John W.; Buell, Gary R.

2010-01-01

This report documents an extension of the Precipitation Runoff Modeling System that accounts for the effect of a large number of water-holding depressions in the land surface on the hydrologic response of a basin. Several techniques for developing the inputs needed by this extension also are presented. These techniques include the delineation of the surface depressions, the generation of volume estimates for the surface depressions, and the derivation of model parameters required to describe these surface depressions. This extension is valuable for applications in basins where surface depressions are too small or numerous to conveniently model as discrete spatial units, but where the aggregated storage capacity of these units is large enough to have a substantial effect on streamflow. In addition, this report documents several new model concepts that were evaluated in conjunction with the depression storage functionality, including: ?hydrologically effective? imperviousness, rates of hydraulic conductivity, and daily streamflow routing. All of these techniques are demonstrated as part of an application in the Upper Flint River Basin, Georgia. Simulated solar radiation, potential evapotranspiration, and water balances match observations well, with small errors for the first two simulated data in June and August because of differences in temperatures from the calibration and evaluation periods for those months. Daily runoff simulations show increasing accuracy with streamflow and a good fit overall. Including surface depression storage in the model has the effect of decreasing daily streamflow for all but the lowest flow values. The report discusses the choices and resultant effects involved in delineating and parameterizing these features. The remaining enhancements to the model and its application provide a more realistic description of basin geography and hydrology that serve to constrain the calibration process to more physically realistic parameter values.

Effective use of surface-water management to control saltwater intrusion

NASA Astrophysics Data System (ADS)

Hughes, J. D.; White, J.

2012-12-01

The Biscayne aquifer in southeast Florida is susceptible to saltwater intrusion and inundation from rising sea-level as a result of high groundwater withdrawal rates and low topographic relief. Groundwater levels in the Biscayne aquifer are managed by an extensive canal system that is designed to control flooding, supply recharge to municipal well fields, and control saltwater intrusion. We present results from an integrated surface-water/groundwater model of a portion of the Biscayne aquifer to evaluate the ability of the existing managed surface-water control network to control saltwater intrusion. Surface-water stage and flow are simulated using a hydrodynamic model that solves the diffusive-wave approximation of the depth-integrated shallow surface-water equations. Variable-density groundwater flow and fluid density are solved using the Oberbeck--Boussinesq approximation of the three-dimensional variable-density groundwater flow equation and a sharp interface approximation, respectively. The surface-water and variable-density groundwater domains are implicitly coupled during each Picard iteration. The Biscayne aquifer is discretized into a multi-layer model having a 500-m square horizontal grid spacing. All primary and secondary surface-water features in the active model domain are discretized into segments using the 500-m square horizontal grid. A 15-year period of time is simulated and the model includes 66 operable surface-water control structures, 127 municipal production wells, and spatially-distributed daily internal and external hydrologic stresses. Numerical results indicate that the existing surface-water system can be effectively used in many locations to control saltwater intrusion in the Biscayne aquifer resulting from increases in groundwater withdrawals or sea-level rise expected to occur over the next 25 years. In other locations, numerical results indicate surface-water control structures and/or operations may need to be modified to control saltwater intrusion.

Engineering report single-shell tank farms interim measures to limit infiltration through the vadose zone

DOE Office of Scientific and Technical Information (OSTI.GOV)

HAASS, C.C.

1999-10-14

Identifies, evaluates and recommends interim measures for reducing or eliminating water sources and preferential pathways within the vadose zone of the single-shell tank farms. Features studied: surface water infiltration and leaking water lines that provide recharge moisture, and wells that could provide pathways for contaminant migration. An extensive data base, maps, recommended mitigations, and rough order of magnitude costs are included.

Soil physical changes associated with forest harvesting operations on a organic soil

Treesearch

Johnny M. Grace; R.W. Skaggs; D.K. Cassel

2006-01-01

The influence of forest operations on forest soil and water continues to be an issue of concern in forest management. Research has focused on evaluating forest operation effects on numerous soil and water quality indicators. However, poorly drained forested watersheds with organic soil surface horizons have not been extensively investigated. A study was initiated in...

The Extract of Roots of Sophora flavescens Enhances the Recovery of Motor Function by Axonal Growth in Mice with a Spinal Cord Injury

PubMed Central

Tanabe, Norio; Kuboyama, Tomoharu; Kazuma, Kohei; Konno, Katsuhiro; Tohda, Chihiro

2016-01-01

Although axonal extension to reconstruct spinal tracts should be effective for restoring function after spinal cord injury (SCI), chondroitin sulfate proteoglycan (CSPG) levels increase at spinal cord lesion sites, and inhibit axonal regrowth. In this study, we found that the water extract of roots of Sophora flavescens extended the axons of mouse cortical neurons, even on a CSPG-coated surface. Consecutive oral administrations of S. flavescens extract to SCI mice for 31 days increased the density of 5-HT-positive axons at the lesion site and improved the motor function. Further, the active constituents in the S. flavescens extract were identified. The water and alkaloid fractions of the S. flavescens extract each exhibited axonal extension activity in vitro. LC/MS analysis revealed that these fractions mainly contain matrine and/or oxymatrine, which are well-known major compounds in S. flavescens. Matrine and oxymatrine promoted axonal extension on the CSPG-coated surface. This study is the first to demonstrate that S. flavescens extract, matrine, and oxymatrine enhance axonal growth in vitro, even on a CSPG-coated surface, and that S. flavescens extract improves motor function and increases axonal density in SCI mice. PMID:26834638

Selected hydrologic data for the field demonstration of three permeable reactive barriers near Fry Canyon, Utah, 1996-2000

USGS Publications Warehouse

Wilkowske, Chris D.; Rowland, Ryan C.; Naftz, David L.

2001-01-01

Three permeable reactive barriers (PRBs) were installed near Fry Canyon, Utah, in August 1997 to demonstrate the use of PRBs to control the migration of uranium in ground water. Reactive material included (1) bone-char phosphate, (2) zero-valent iron pellets, and (3) amorphous ferric oxyhydroxide coated gravel. An extensive monitoring network was installed in and around each PRB for collection of water samples, analysis of selected water-quality parameters, and monitoring of water levels. Water temperature, specific conductance, pH, Eh (oxidation-reduction potential), and dissolved oxygen were measured continuously within three different barrier materials, and in two monitoring wells. Water temperature and water level below land surface were electronically recorded every hour with pressure transducers. Data were collected from ground-water monitoring wells installed in and around the PRBs during 1996-98 and from surface-water sites in Fry Creek.

A Quantitative Socio-hydrological Characterization of Water Security in Large-Scale Irrigation Systems

NASA Astrophysics Data System (ADS)

Siddiqi, A.; Muhammad, A.; Wescoat, J. L., Jr.

2017-12-01

Large-scale, legacy canal systems, such as the irrigation infrastructure in the Indus Basin in Punjab, Pakistan, have been primarily conceived, constructed, and operated with a techno-centric approach. The emerging socio-hydrological approaches provide a new lens for studying such systems to potentially identify fresh insights for addressing contemporary challenges of water security. In this work, using the partial definition of water security as "the reliable availability of an acceptable quantity and quality of water", supply reliability is construed as a partial measure of water security in irrigation systems. A set of metrics are used to quantitatively study reliability of surface supply in the canal systems of Punjab, Pakistan using an extensive dataset of 10-daily surface water deliveries over a decade (2007-2016) and of high frequency (10-minute) flow measurements over one year. The reliability quantification is based on comparison of actual deliveries and entitlements, which are a combination of hydrological and social constructs. The socio-hydrological lens highlights critical issues of how flows are measured, monitored, perceived, and experienced from the perspective of operators (government officials) and users (famers). The analysis reveals varying levels of reliability (and by extension security) of supply when data is examined across multiple temporal and spatial scales. The results shed new light on evolution of water security (as partially measured by supply reliability) for surface irrigation in the Punjab province of Pakistan and demonstrate that "information security" (defined as reliable availability of sufficiently detailed data) is vital for enabling water security. It is found that forecasting and management (that are social processes) lead to differences between entitlements and actual deliveries, and there is significant potential to positively affect supply reliability through interventions in the social realm.

Hydrophobic/Hydrophilic Cooperative Janus System for Enhancement of Fog Collection.

PubMed

Cao, Moyuan; Xiao, Jiasheng; Yu, Cunming; Li, Kan; Jiang, Lei

2015-09-09

Harvesting micro-droplets from fog is a promising method for solving global freshwater crisis. Different types of fog collectors have been extensively reported during the last decade. The improvement of fog collection can be attributed to the immediate transportation of harvested water, the effective regeneration of the fog gathering surface, etc. Through learning from the nature's strategy for water preservation, the hydrophobic/hydrophilic cooperative Janus system that achieved reinforced fog collection ability is reported here. Directional delivery of the surface water, decreased re-evaporation rate of the harvested water, and thinner boundary layer of the collecting surface contribute to the enhancement of collection efficiency. Further designed cylinder Janus collector can facilely achieve a continuous process of efficient collection, directional transportation, and spontaneous preservation of fog water. This Janus fog harvesting system should improve the understanding of micro-droplet collection system and offer ideas to solve water resource crisis. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DMSO Induces Dehydration near Lipid Membrane Surfaces

PubMed Central

Cheng, Chi-Yuan; Song, Jinsuk; Pas, Jolien; Meijer, Lenny H.H.; Han, Songi

2015-01-01

Dimethyl sulfoxide (DMSO) has been broadly used in biology as a cosolvent, a cryoprotectant, and an enhancer of membrane permeability, leading to the general assumption that DMSO-induced structural changes in cell membranes and their hydration water play important functional roles. Although the effects of DMSO on the membrane structure and the headgroup dehydration have been extensively studied, the mechanism by which DMSO invokes its effect on lipid membranes and the direct role of water in this process are unresolved. By directly probing the translational water diffusivity near unconfined lipid vesicle surfaces, the lipid headgroup mobility, and the repeat distances in multilamellar vesicles, we found that DMSO exclusively weakens the surface water network near the lipid membrane at a bulk DMSO mole fraction (XDMSO) of <0.1, regardless of the lipid composition and the lipid phase. Specifically, DMSO was found to effectively destabilize the hydration water structure at the lipid membrane surface at XDMSO <0.1, lower the energetic barrier to dehydrate this surface water, whose displacement otherwise requires a higher activation energy, consequently yielding compressed interbilayer distances in multilamellar vesicles at equilibrium with unaltered bilayer thicknesses. At XDMSO >0.1, DMSO enters the lipid interface and restricts the lipid headgroup motion. We postulate that DMSO acts as an efficient cryoprotectant even at low concentrations by exclusively disrupting the water network near the lipid membrane surface, weakening the cohesion between water and adhesion of water to the lipid headgroups, and so mitigating the stress induced by the volume change of water during freeze-thaw. PMID:26200868

Impact of Water Recovery from Wastes on the Lunar Surface Mission Water Balance

NASA Technical Reports Server (NTRS)

Fisher, John W.; Hogan, John Andrew; Wignarajah, Kanapathipi; Pace, Gregory S.

2010-01-01

Future extended lunar surface missions will require extensive recovery of resources to reduce mission costs and enable self-sufficiency. Water is of particular importance due to its potential use for human consumption and hygiene, general cleaning, clothes washing, radiation shielding, cooling for extravehicular activity suits, and oxygen and hydrogen production. Various water sources are inherently present or are generated in lunar surface missions, and subject to recovery. They include: initial water stores, water contained in food, human and other solid wastes, wastewaters and associated brines, ISRU water, and scavenging from residual propellant in landers. This paper presents the results of an analysis of the contribution of water recovery from life support wastes on the overall water balance for lunar surface missions. Water in human wastes, metabolic activity and survival needs are well characterized and dependable figures are available. A detailed life support waste model was developed that summarizes the composition of life support wastes and their water content. Waste processing technologies were reviewed for their potential to recover that water. The recoverable water in waste is a significant contribution to the overall water balance. The value of this contribution is discussed in the context of the other major sources and loses of water. Combined with other analyses these results provide guidance for research and technology development and down-selection.

Global modeling of withdrawal, allocation and consumptive use of surface water and groundwater resources

NASA Astrophysics Data System (ADS)

Wada, Y.; Wisser, D.; Bierkens, M. F. P.

2014-01-01

To sustain growing food demand and increasing standard of living, global water withdrawal and consumptive water use have been increasing rapidly. To analyze the human perturbation on water resources consistently over large scales, a number of macro-scale hydrological models (MHMs) have been developed in recent decades. However, few models consider the interaction between terrestrial water fluxes, and human activities and associated water use, and even fewer models distinguish water use from surface water and groundwater resources. Here, we couple a global water demand model with a global hydrological model and dynamically simulate daily water withdrawal and consumptive water use over the period 1979-2010, using two re-analysis products: ERA-Interim and MERRA. We explicitly take into account the mutual feedback between supply and demand, and implement a newly developed water allocation scheme to distinguish surface water and groundwater use. Moreover, we include a new irrigation scheme, which works dynamically with a daily surface and soil water balance, and incorporate the newly available extensive Global Reservoir and Dams data set (GRanD). Simulated surface water and groundwater withdrawals generally show good agreement with reported national and subnational statistics. The results show a consistent increase in both surface water and groundwater use worldwide, with a more rapid increase in groundwater use since the 1990s. Human impacts on terrestrial water storage (TWS) signals are evident, altering the seasonal and interannual variability. This alteration is particularly large over heavily regulated basins such as the Colorado and the Columbia, and over the major irrigated basins such as the Mississippi, the Indus, and the Ganges. Including human water use and associated reservoir operations generally improves the correlation of simulated TWS anomalies with those of the GRACE observations.

Global Modeling of Withdrawal, Allocation and Consumptive Use of Surface Water and Groundwater Resources

NASA Astrophysics Data System (ADS)

Wada, Y.; Wisser, D.; Bierkens, M. F.

2014-12-01

To sustain growing food demand and increasing standard of living, global water withdrawal and consumptive water use have been increasing rapidly. To analyze the human perturbation on water resources consistently over large scales, a number of macro-scale hydrological models (MHMs) have been developed in recent decades. However, few models consider the interaction between terrestrial water fluxes, and human activities and associated water use, and even fewer models distinguish water use from surface water and groundwater resources. Here, we couple a global water demand model with a global hydrological model and dynamically simulate daily water withdrawal and consumptive water use over the period 1979-2010, using two re-analysis products: ERA-Interim and MERRA. We explicitly take into account the mutual feedback between supply and demand, and implement a newly developed water allocation scheme to distinguish surface water and groundwater use. Moreover, we include a new irrigation scheme, which works dynamically with a daily surface and soil water balance, and incorporate the newly available extensive global reservoir data set (GRanD). Simulated surface water and groundwater withdrawals generally show good agreement with reported national and sub-national statistics. The results show a consistent increase in both surface water and groundwater use worldwide, with a more rapid increase in groundwater use since the 1990s. Human impacts on terrestrial water storage (TWS) signals are evident, altering the seasonal and inter-annual variability. This alteration is particularly large over heavily regulated basins such as the Colorado and the Columbia, and over the major irrigated basins such as the Mississippi, the Indus, and the Ganges. Including human water use and associated reservoir operations generally improves the correlation of simulated TWS anomalies with those of the GRACE observations.

Assessing the suitability of stream water for five different uses and its aquatic environment.

PubMed

Fulazzaky, Mohamad Ali

2013-01-01

Surface water is one of the essential resources for supporting sustainable development. The suitability of such water for a given use depends both on the available quantity and tolerable quality. Temporary status for a surface water quality has been identified extensively. Still the suitability of the water for different purposes needs to be verified. This study proposes a water quality evaluation system to assess the aptitude of the Selangor River water for aquatic biota, drinking water production, leisure and aquatic sport, irrigation use, livestock watering, and aquaculture use. Aptitude of the water has been classified in many parts of the river segment as unsuitable for aquatic biota, drinking water production, leisure and aquatic sport as well as aquaculture use. The water quality aptitude classes of the stream water for nine locations along the river are evaluated to contribute to decision support system. The suitability of the water for five different uses and its aquatic ecosystem are verified.

47 CFR 1.1311 - Environmental information to be included in the environmental assessment (EA).

Code of Federal Regulations, 2010 CFR

2010-10-01

... facilities on any district, site, building, structure or object listed, or eligible for listing, in the... land utilized (e.g., deforestation, water diversion, wetland fill, or other extensive change of surface...

Surface ultrastructure of the gill filaments and the secondary lamellae of the catfish, Rita rita, and the carp, Cirrhinus mrigala.

PubMed

Kumari, Usha; Mittal, Swati; Mittal, Ajay Kumar

2012-04-01

Surface ultrastructures of gill filaments and secondary lamellae of Rita rita and Cirrhinus mrigala, inhabiting different ecological habitat, were investigated to unravel adaptive modifications. R. rita is a sluggish, bottom dwelling carnivorous catfish, which inhabits regions of river with accumulations of dirty water. It retains its viability for long time if taken out of water. C. mrigala is an active bottom dwelling Indian major carp, which lives in relatively clean water and dies shortly after taken out of water. In R. rita, gill septa between gill filaments are reduced. Microridges on epithelial cells covering gill filaments are often continuous and arranged concentrically. Secondary lamellae are extensive. The epithelium appears corrugated, show irregular elevations and shallow depressions, and microridges on epithelial cells appear fragmented. In C. mrigala, in contrast, the gill septa are extensive. Microridges on epithelial cells covering gill filaments are fragmented. Secondary lamellae are less extensive. The epithelium appears smooth and microridges on epithelial cells are relatively inconspicuous. These differences have been considered adaptive modification in relation to habit and ecological niches inhabited by two fish species. Presence of mucous goblet cells on gill filaments is discussed in relation to their functions including precipitation of the sediments and preventing clogging of gill filaments. Infrequent mucous goblet cells in the epithelium of secondary lamellae in two fish species are considered an adaptation, minimizing thickness of the epithelium to reduce barrier between blood and water for favoring gasses exchange with increased efficiency. Copyright © 2011 Wiley-Liss, Inc.

Effects of Vaporized Decontamination Systems on Selected Building Interior Materials: Chlorine Dioxide

DTIC Science & Technology

2009-02-01

Chemical Biological Center (ECBC) to take advantage of ECBC’s extensive expertise and specialized research facilities for the decontamination of surfaces...Agency (EPA) established an Interagency Agreement with the U.S. Army Edgewood Chemical Biological Center (ECBC) to take advantage of ECBC’s extensive...Detector (Waters Corporation, Milford, MA). Conductivity suppression was carried out using an ERIS 1000HP Autosuppressor ( Alltech Corporation, Deerfield

The water dimer II: Theoretical investigations

NASA Astrophysics Data System (ADS)

Mukhopadhyay, Anamika; Xantheas, Sotiris S.; Saykally, Richard J.

2018-05-01

As the archetype of aqueous hydrogen bonding, the water dimer has been extensively studied by both theory and experiment for nearly seven decades. In this article, we present a detailed chronological review of the theoretical advances made using electronic structure methods to address the structure, hydrogen bonding and vibrational spectroscopy of the water dimer, as well as the role of its potential energy surface in the development of classical force fields to describe intermolecular interactions in clusters and the condensed phases of water.

The Water Dimer II: Theoretical Investigations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mukhopadhyay, Anamika; Xantheas, Sotiris S.; Saykally, Richard J.

As the archetype of aqueous hydrogen bonding, the water dimer has been extensively studied by both theory and experiment for nearly seven decades. Here in this article, we present a detailed chronological review of the theoretical advances made using electronic structure methods to address the structure, hydrogen bonding and vibrational spectroscopy of the water dimer, as well as the role of its potential energy surface in the development of classical force fields to describe intermolecular interaction in clusters and the condensed phases of water.

The Water Dimer II: Theoretical Investigations

DOE PAGES

Mukhopadhyay, Anamika; Xantheas, Sotiris S.; Saykally, Richard J.

2018-03-29

As the archetype of aqueous hydrogen bonding, the water dimer has been extensively studied by both theory and experiment for nearly seven decades. Here in this article, we present a detailed chronological review of the theoretical advances made using electronic structure methods to address the structure, hydrogen bonding and vibrational spectroscopy of the water dimer, as well as the role of its potential energy surface in the development of classical force fields to describe intermolecular interaction in clusters and the condensed phases of water.

Role of gravity in the formation of bacterial colonies with a hydrophobic surface layer

NASA Astrophysics Data System (ADS)

Puzyr, A. P.; Tirranen, L. K.; Krylova, T. Y.; Borodina, E. V.

A simple technique for determining hydrophobic-hydrophilic properties of bacterial colonies surface, which involves putting a drop of liquid with known properties (e.g. water, oil) on their surface, has been described. This technique allows quick estimate of wettability of bacterial colony surface, i.e. its hydrophobic-hydrophilic properties. The behaviour of water drops on colonies of bacteria Bacillus five strains (of different types) has been studied. It was revealed that 1) orientation in the Earth gravity field during bacterial growth can define the form of colonies with hydrophobic surface; 2) the form and size of the colony are dependent on the extention ability, most probably, of the hydrophobic layer; 3) the Earth gravity field (gravity) serves as a 'pump' providing and keeping water within the colony. We suppose that at growing colonies on agar media the inflow of water-soluble nutrient materials takes place both due to diffusion processes and directed water current produced by the gravity. The revealed effect probably should be taken into consideration while constructing the models of colonies growing on dense nutrient media. The easily determined hydrophobic properties of colonies surface can become a systematic feature after collecting more extensive data on the surface hydrophobic-hydrophilic properties of microorganism colonies of other types and species.

Chemical quality of ground water in the central Sacramento Valley, California

USGS Publications Warehouse

Fogelman, Ronald P.

1978-01-01

The study area includes about 1,200 square miles in the central Sacramento Valley adjacent to the Sacramento River from Knights Landing to Los Molinos, Calif. With recent agricultural development in the area, additional land has been brought under irrigation from land which had been used primarily for dry farming and grazing. This report documents the chemical character of the ground water prior to water-level declines resulting from extensive pumping for irrigation or to changes caused by extensive use of imported surface water. Chemical analyses of samples from 209 wells show that most of the area is underlain by ground water of a quality suitable for most agricultural and domestic purposes. Most of the water sampled in the area has dissolved-solids concentrations ranging from 100 to 700 milligrams per liter. The general water types for the area are a calcium magnesium bicarbonate or magnesium calcium bicarbonate and there are negligible amounts of toxic trace elements. (Woodard-USGS)

Aquifer susceptibility to perchlorate contamination in a highly urbanized environment

USGS Publications Warehouse

Woolfenden, Linda R.; Trefly, Michael G.

2007-01-01

Perchlorate contamination from anthropogenic sources has been released into the Rialto-Colton, California, USA, groundwater flow system since the 1940s during its production, distribution, storage, and use. Preliminary analysis of lithological, geophysical, and water-chemistry data provided new understanding of the pathways of perchlorate migration that aid in assessing the susceptibility of drinking-water supplies to contamination within the Rialto-Colton basin. Vertical migration of perchlorate into the main water-producing aquifers is restricted by an areally extensive old soil surface; however, perchlorate data indicate contamination below this soil surface. Possible pathways for the downward migration of the contaminated water include wellbore flow and discontinuities in the old soil surface. Horizontal migration of perchlorate is influenced by lithology and faults within the basin. The basin fill is a heterogeneous mixture of boulders, gravel, sand, silt, and clay, and internal faults may restrict perchlorate migration in some areas.

Capturing field-scale variability in crop performance across a regional-scale climosequence

NASA Astrophysics Data System (ADS)

Brooks, E. S.; Poggio, M.; Anderson, T. R.; Gasch, C.; Yourek, M. A.; Ward, N. K.; Magney, T. S.; Brown, D. J.; Huggins, D. R.

2014-12-01

With the increasing availability of variable rate technology for applying fertilizers and other agrichemicals in dryland agricultural production systems there is a growing need to better capture and understand the processes driving field scale variability in crop yield and soil water. This need for a better understanding of field scale variability has led to the recent designation of the R. J. Cook Agronomy Farm (CAF) (Pullman, WA, USA) as a United States Department of Agriculture Long-Term Agro-Ecosystem Research (LTAR) site. Field scale variability at the CAF is closely monitored using extensive environmental sensor networks and intensive hand sampling. As investigating land-soil-water dynamics at CAF is essential for improving precision agriculture, transferring this knowledge across the regional-scale climosequence is challenging. In this study we describe the hydropedologic functioning of the CAF in relation to five extensively instrumented field sites located within 50 km in the same climatic region. The formation of restrictive argillic soil horizons in the wetter, cooler eastern edge of the region results in the development of extensive perched water tables, surface saturation, and surface runoff, whereas excess water is not an issue in the warmer, drier, western edge of the region. Similarly, crop and tillage management varies across the region as well. We discuss the implications of these regional differences on field scale management decisions and demonstrate how we are using proximal soil sensing and remote sensing imagery to better understand and capture field scale variability at a particular field site.

Length-extension resonator as a force sensor for high-resolution frequency-modulation atomic force microscopy in air.

PubMed

Beyer, Hannes; Wagner, Tino; Stemmer, Andreas

2016-01-01

Frequency-modulation atomic force microscopy has turned into a well-established method to obtain atomic resolution on flat surfaces, but is often limited to ultra-high vacuum conditions and cryogenic temperatures. Measurements under ambient conditions are influenced by variations of the dew point and thin water layers present on practically every surface, complicating stable imaging with high resolution. We demonstrate high-resolution imaging in air using a length-extension resonator operating at small amplitudes. An additional slow feedback compensates for changes in the free resonance frequency, allowing stable imaging over a long period of time with changing environmental conditions.

Divergent surface and total soil moisture projections under global warming

USGS Publications Warehouse

Berg, Alexis; Sheffield, Justin; Milly, Paul C.D.

2017-01-01

Land aridity has been projected to increase with global warming. Such projections are mostly based on off-line aridity and drought metrics applied to climate model outputs but also are supported by climate-model projections of decreased surface soil moisture. Here we comprehensively analyze soil moisture projections from the Coupled Model Intercomparison Project phase 5, including surface, total, and layer-by-layer soil moisture. We identify a robust vertical gradient of projected mean soil moisture changes, with more negative changes near the surface. Some regions of the northern middle to high latitudes exhibit negative annual surface changes but positive total changes. We interpret this behavior in the context of seasonal changes in the surface water budget. This vertical pattern implies that the extensive drying predicted by off-line drought metrics, while consistent with the projected decline in surface soil moisture, will tend to overestimate (negatively) changes in total soil water availability.

Characterizing groundwater/surface-water interactions in the interior of Jianghan Plain, central China

NASA Astrophysics Data System (ADS)

Du, Yao; Ma, Teng; Deng, Yamin; Shen, Shuai; Lu, Zongjie

2018-06-01

Quantifying groundwater/surface-water interactions is essential for managing water resources and revealing contaminant fate. There has been little concern on the exchange between streams and aquifers through an extensive aquitard thus far. In this study, hydrogeologic calculation and tritium modeling were jointly applied to characterize such interactions through an extensive aquitard in the interior of Jianghan Plain, an alluvial plain of Yangtze River, China. One groundwater simulation suggested that the lateral distance of influence from the river was about 1,000 m; vertical flow in the aquitard followed by lateral flow in the aquifer contributed significantly more ( 90%) to the aquifer head change near the river than lateral bank storage in the aquitard followed by infiltration. The hydrogeologic calculation produced vertical fluxes of the order 0.01 m/day both near and farther from the river, suggesting that similar shorter-lived (half-monthly) vertical fluxes occur between the river and aquitard near the river, and between the surface end members and aquitard farther from the river. Tritium simulation based on the OTIS model produced an average groundwater residence time of about 15 years near the river and a resulting vertical flux of the order 0.001 m/day. Another tritium simulation based on a dispersion model produced a vertical flux of the order 0.0001 m/day away from the river, coupled with an average residence time of around 90 years. These results suggest an order of magnitude difference for the longer-lived (decadal) vertical fluxes between surface waters and the aquifer near and away from the river.

Characterizing groundwater/surface-water interactions in the interior of Jianghan Plain, central China

NASA Astrophysics Data System (ADS)

Du, Yao; Ma, Teng; Deng, Yamin; Shen, Shuai; Lu, Zongjie

2018-01-01

Quantifying groundwater/surface-water interactions is essential for managing water resources and revealing contaminant fate. There has been little concern on the exchange between streams and aquifers through an extensive aquitard thus far. In this study, hydrogeologic calculation and tritium modeling were jointly applied to characterize such interactions through an extensive aquitard in the interior of Jianghan Plain, an alluvial plain of Yangtze River, China. One groundwater simulation suggested that the lateral distance of influence from the river was about 1,000 m; vertical flow in the aquitard followed by lateral flow in the aquifer contributed significantly more ( 90%) to the aquifer head change near the river than lateral bank storage in the aquitard followed by infiltration. The hydrogeologic calculation produced vertical fluxes of the order 0.01 m/day both near and farther from the river, suggesting that similar shorter-lived (half-monthly) vertical fluxes occur between the river and aquitard near the river, and between the surface end members and aquitard farther from the river. Tritium simulation based on the OTIS model produced an average groundwater residence time of about 15 years near the river and a resulting vertical flux of the order 0.001 m/day. Another tritium simulation based on a dispersion model produced a vertical flux of the order 0.0001 m/day away from the river, coupled with an average residence time of around 90 years. These results suggest an order of magnitude difference for the longer-lived (decadal) vertical fluxes between surface waters and the aquifer near and away from the river.

Fabricating Superhydrophobic and Superoleophobic Surfaces with Multiscale Roughness Using Airbrush and Electrospray

NASA Astrophysics Data System (ADS)

AL-Milaji, Karam N.

Examples of superhydrophobic surfaces found in nature such as self-cleaning property of lotus leaf and walking on water ability of water strider have led to an extensive investigation in this area over the past few decades. When a water droplet rests on a textured surface, it may either form a liquid-solid-vapor composite interface by which the liquid droplet partially sits on air pockets or it may wet the surface in which the water replaces the trapped air depending on the surface roughness and the surface chemistry. Super water repellent surfaces have numerous applications in our daily life such as drag reduction, anti-icing, anti-fogging, energy conservation, noise reduction, and self-cleaning. In fact, the same concept could be applied in designing and producing surfaces that repel organic contaminations (e.g. low surface tension liquids). However, superoleophobic surfaces are more challenging to fabricate than superhydrophobic surfaces since the combination of multiscale roughness with re-entrant or overhang structure and surface chemistry must be provided. In this study, simple, cost-effective and potentially scalable techniques, i.e., airbrush and electrospray, were employed for the sake of making superhydrophobic and superoleophobic coatings with random and patterned multiscale surface roughness. Different types of silicon dioxide were utilized in this work to in order to study and to characterize the effect of surface morphology and surface roughness on surface wettability. The experimental findings indicated that super liquid repellent surfaces with high apparent contact angles and extremely low sliding angles were successfully fabricated by combining re-entrant structure, multiscale surface roughness, and low surface energy obtained from chemically treating the fabricated surfaces. In addition to that, the experimental observations regarding producing textured surfaces in mask-assisted electrospray were further validated by simulating the actual working conditions and geometries using COMSOL Multiphysics.

Assessment of the impact of traditional septic tank soakaway systems on water quality in Ireland.

PubMed

Keegan, Mary; Kilroy, Kate; Nolan, Daniel; Dubber, Donata; Johnston, Paul M; Misstear, Bruce D R; O'Flaherty, Vincent; Barrett, Maria; Gill, Laurence W

2014-01-01

One of the key threats to groundwater and surface water quality in Ireland is the impact of poorly designed, constructed or maintained on-site wastewater treatment systems. An extensive study was carried out to quantify the impact of existing sites on water quality. Six existing sites, consisting of a traditional septic tank and soakaway system, located in various ranges of subsoil permeabilities were identified and monitored to determine how well they function under varying subsoil and weather conditions. The preliminary results of the chemical and microbiological pollutant attenuation in the subsoil of the systems have been assessed and treatment performance evaluated, as well as impact on local surface water and groundwater quality. The source of any faecal contamination detected in groundwater, nearby surface water and effluent samples was confirmed by microbial source tracking. From this, it can be seen that the transport and treatment of percolate vary greatly depending on the permeability and composition of the subsoil.

Nutrient interleaving below the mixed layer of the Kuroshio Extension Front

NASA Astrophysics Data System (ADS)

Nagai, Takeyoshi; Clayton, Sophie

2017-08-01

Nitrate interleaving structures were observed below the mixed layer during a cruise to the Kuroshio Extension in October 2009. In this paper, we investigate the formation mechanisms for these vertical nitrate anomalies, which may be an important source of nitrate to the oligotrphoc surface waters south of the Kuroshio Extension Front. We found that nitrate concentrations below the main stream of the Kuroshio Extension were elevated compared to the ambient water of the same density ( σ 𝜃 = 23.5-25). This appears to be analogous to the "nutrient stream" below the mixed layer, associated with the Gulf Stream. Strong turbulence was observed above the vertical nitrate anomaly, and we found that this can drive a large vertical turbulent nitrate flux >O (1 mmol N m-2 day-1). A realistic, high-resolution (2 km) numerical simulation reproduces the observed Kuroshio nutrient stream and nitrate interleaving structures, with similar lateral and vertical scales. The model results suggest that the nitrate interleaving structures are first generated at the western side of the meander crest on the south side of the Kuroshio Extension, where the southern tip of the mixed layer front is under frontogenesis. Lagrangian analyses reveal that the vertical shear of geostrophic and subinertial ageostrophic flow below the mixed layer tilts the existing along-isopycnal nitrate gradient of the Kuroshio nutrient stream to form nitrate interleaving structures. This study suggests that the multi-scale combination of (i) the lateral stirring of the Kuroshio nutrient stream by developed mixed layer fronts during fall to winter, (ii) the associated tilting of along-isopycnal nitrate gradient of the nutrient stream by subinertial shear, which forms vertical interleaving structures, and (iii) the strong turbulent diffusion above them, may provide a route to supply nutrients to oligotrophic surface waters on the south side of the Kuroshio Extension.

Improving National Water Modeling: An Intercomparison of two High-Resolution, Continental Scale Models, CONUS-ParFlow and the National Water Model

NASA Astrophysics Data System (ADS)

Tijerina, D.; Gochis, D.; Condon, L. E.; Maxwell, R. M.

2017-12-01

Development of integrated hydrology modeling systems that couple atmospheric, land surface, and subsurface flow is growing trend in hydrologic modeling. Using an integrated modeling framework, subsurface hydrologic processes, such as lateral flow and soil moisture redistribution, are represented in a single cohesive framework with surface processes like overland flow and evapotranspiration. There is a need for these more intricate models in comprehensive hydrologic forecasting and water management over large spatial areas, specifically the Continental US (CONUS). Currently, two high-resolution, coupled hydrologic modeling applications have been developed for this domain: CONUS-ParFlow built using the integrated hydrologic model ParFlow and the National Water Model that uses the NCAR Weather Research and Forecasting hydrological extension package (WRF-Hydro). Both ParFlow and WRF-Hydro include land surface models, overland flow, and take advantage of parallelization and high-performance computing (HPC) capabilities; however, they have different approaches to overland subsurface flow and groundwater-surface water interactions. Accurately representing large domains remains a challenge considering the difficult task of representing complex hydrologic processes, computational expense, and extensive data needs; both models have accomplished this, but have differences in approach and continue to be difficult to validate. A further exploration of effective methodology to accurately represent large-scale hydrology with integrated models is needed to advance this growing field. Here we compare the outputs of CONUS-ParFlow and the National Water Model to each other and with observations to study the performance of hyper-resolution models over large domains. Models were compared over a range of scales for major watersheds within the CONUS with a specific focus on the Mississippi, Ohio, and Colorado River basins. We use a novel set of approaches and analysis for this comparison to better understand differences in process and bias. This intercomparison is a step toward better understanding how much water we have and interactions between surface and subsurface. Our goal is to advance our understanding and simulation of the hydrologic system and ultimately improve hydrologic forecasts.

ALMA Thermal Mapping of Ceres – Search for Subsurface Water Ice

NASA Astrophysics Data System (ADS)

Moullet, Arielle; Li, Jian-Yang; Titus, Timothy N.; Sykes, Mark V.; Hsieh, Henry H.

2018-06-01

Spectroscopic observations of the surface of Ceres by Dawn have demonstrated that hydrated minerals are ubiquitous, but only few smaller sites are enriched with water ice. This is somewhat surprising as Ceres is believed to host a large amount a water in its interior.The possibility of inhomogeneous subsurface water distribution can be investigated by tracing thermal inertia distribution. To that effect, we mapped the temperature of Ceres using 1.3mm maps of the whole surface obtained with the Atacama Large Millimeter Array (ALMA) over three different epochs during one Ceres’ year. Assessing the thermal conditions at the depths probed by sub millimeter observations (a few cm below the surface, within the annual thermal skin depth) is critical to constrain the effective thermal inertia, and hence the status of subsurface water ice. We will present preliminary results in terms of temperature features and the corresponding thermal inertia derived based on comparisons from the KRC thermal model which has been extensively used for Mars. Initial analysis is consistent with the presence of near-surface high thermal inertia layer, presumably water ice, in the north polar region.This work is supported by the NASA Solar System Observations Program NNX15AE02G.

Surface microstructures of daisy florets (Asteraceae) and characterization of their anisotropic wetting.

PubMed

Koch, Kerstin; Bennemann, Michael; Bohn, Holger F; Albach, Dirk C; Barthlott, Wilhelm

2013-09-01

The surface microstructures on ray florets of 62 species were characterized and compared with modern phylogenetic data of species affiliation in Asteraceae to determine sculptural patterns and their occurrence in the tribes of Asteraceae. Their wettability was studied to identify structural-induced droplet adhesion, which can be used for the development of artificial surfaces for water harvesting and passive surface water transport. The wettability was characterized by contact angle (CA) and tilt angle measurements, performed on fresh ray florets and their epoxy resin replica. The CAs on ray florets varied between 104° and 156°, but water droplets did not roll off when surface was tilted at 90°. Elongated cell structures and cuticle folding orientated in the same direction as the cell elongation caused capillary forces, leading to anisotropic wetting, with extension of water droplets along the length axis of epidermis cells. The strongest elongation of the droplets was also supported by a parallel, cell-overlapping cuticle striation. In artificial surfaces made of epoxy replica of ray florets, this effect was enhanced. The distribution of the identified four structural types exhibits a strong phylogenetic signal and allows the inference of an evolutionary trend in the modification of floret epidermal cells.

Origin of 1/f noise in hydration dynamics on lipid membrane surfaces

PubMed Central

Yamamoto, Eiji; Akimoto, Takuma; Yasui, Masato; Yasuoka, Kenji

2015-01-01

Water molecules on lipid membrane surfaces are known to contribute to membrane stability by connecting lipid molecules and acting as a water bridge. Although water structures and diffusivities near the membrane surfaces have been extensively studied, hydration dynamics on the surfaces has remained an open question. Here we investigate residence time statistics of water molecules on the surface of lipid membranes using all-atom molecular dynamics simulations. We show that hydration dynamics on the lipid membranes exhibits 1/f noise. Constructing a dichotomous process for the hydration dynamics, we find that residence times in each state follow a power-law with exponential cutoff and that the process can be regarded as a correlated renewal process where interoccurrence times are correlated. The results imply that the origin of the 1/f noise in hydration dynamics on the membrane surfaces is a combination of a power-law distribution with cutoff of interoccurrence times of switching events and a long-term correlation between the interoccurrence times. These results suggest that the 1/f noise attributed to the correlated renewal process may contribute to the stability of the hydration layers and lipid membranes. PMID:25743377

ESTIMATING AND PROJECTING IMPERVIOUS COVER IN THE SOUTHEASTERN UNITED STATES

EPA Science Inventory

Urban/suburban land use is the most rapidly growing land use class. Along with increased development inevitably comes increased impervious surface--areas preventing infiltration of water into the underlying soil. The extensive hydrological alteration of watersheds associated wi...

Urban water-quality modelling: implementing an extension to Multi-Hydro platform for real case studies

NASA Astrophysics Data System (ADS)

Hong, Yi; Giangola-Murzyn, Agathe; Bonhomme, Celine; Chebbo, Ghassan; Schertzer, Daniel

2015-04-01

During the last few years, the physically based and fully distributed numerical platform Multi-Hydro (MH) has been developed to simulate hydrological behaviours in urban/peri-urban areas (El-Tabach et al. , 2009 ; Gires et al., 2013 ; Giangola-Murzyn et al., 2014). This hydro-dynamical platform is open-access and has a modular structure, which is designed to be easily scalable and transportable, in order to simulate the dynamics and complex interactions of the water cycle processes in urban or peri-urban environment (surface hydrology, urban groundwater infrastructures and infiltration). Each hydrological module relies on existing and widely validated open source models, such as TREX model (Velleux, 2005) for the surface module, SWMM model (Rossman, 2010) for the drainage module and VS2DT model (Lappala et al., 1987) for the soil module. In our recent studies, an extension of MH has been set up by connecting the already available water-quality computational components among different modules, to introduce a pollutant transport modelling into the hydro-dynamical platform. As for the surface module in two-dimensions, the concentration of particles in flow is expressed by sediment advection equation, the settling of suspended particles is calculated with a simplified settling velocity formula, while the pollutant wash-off from a given land-use is represented as a mass rate of particle removal from the bottom boundary over time, based on transport capacity, which is computed by a modified form of Universal Soil Loss Equation (USLE). Considering that the USLE is originally conceived to predict soil losses caused by runoff in agriculture areas, several adaptations were needed to use it for urban areas, such as the alterations of USLE parameters according to different criterions, the definition of the appropriate initial dust thickness corresponding to various land-uses, etc. Concerning the drainage module, water quality routing within pipes assumes that the conduit behaves as a continuously stirred tank reactor. This extension of Multi-Hydro was tested on two peri-urban catchments located near Paris, the Villecresnes (France, 0.7 km²) and the Le Perreux-sur-Marne (France, 0.2 km²). As the Villecresnes had been analyzed within several European projects (FP7 SMARTeST, KIC-Climate BlueGreenDream, Interreg RainGain), the robustness of the new extension of MH was firstly tested on this basin by comparing the water quantity simulation outcomes with the results already obtained in previous works. Benefiting from the large datasets that are collected in the framework of the ANR (French National Agency for Research) Trafipollu project, the water quality modelling performance of the extension was then illustrated on the catchment of Le Perreux-sur-Marne.

The Martian paleoclimate and enhanced atmospheric carbon dioxide

NASA Technical Reports Server (NTRS)

Cess, R. D.; Owen, T.; Ramanathan, V.

1980-01-01

Current evidence indicates that the Martian surface is abundant with water presently in the form of ice, while the atmosphere was at one time more massive with a past surface pressure of as much as 1 atm of CO2. In an attempt to understand the Martian paleoclimate, a past CO2-H2O greenhouse was modeled and global temperatures which are consistent with an earlier presence of liquid surface water are found in agreement with the extensive evidence for past fluvial erosion. An important aspect of the CO2-H2O greenhouse model is the detailed inclusion of CO2 hot bands. For a surface pressure of 1 atm of CO2, the present greenhouse model predicts a global mean surface temperature of 294 K, but if the hot bands are excluded, a surface temperature of only 250 K is achieved.

The need for accurate long-term measurements of water vapor in the upper troposphere and lower stratosphere with global coverage.

PubMed

Müller, Rolf; Kunz, Anne; Hurst, Dale F; Rolf, Christian; Krämer, Martina; Riese, Martin

2016-02-01

Water vapor is the most important greenhouse gas in the atmosphere although changes in carbon dioxide constitute the "control knob" for surface temperatures. While the latter fact is well recognized, resulting in extensive space-borne and ground-based measurement programs for carbon dioxide as detailed in the studies by Keeling et al. (1996), Kuze et al. (2009), and Liu et al. (2014), the need for an accurate characterization of the long-term changes in upper tropospheric and lower stratospheric (UTLS) water vapor has not yet resulted in sufficiently extensive long-term international measurement programs (although first steps have been taken). Here, we argue for the implementation of a long-term balloon-borne measurement program for UTLS water vapor covering the entire globe that will likely have to be sustained for hundreds of years.

Tunable Oleo-Furan Surfactants by Acylation of Renewable Furans

DOE PAGES

Park, Dae Sung; Joseph, Kristeen E.; Koehle, Maura; ...

2016-10-19

One important advance in fluid surface control was the amphiphilic surfactant composed of coupled molecular structures (i.e., hydrophilic and hydrophobic) to reduce surface tension between two distinct fluid phases. However, implementation of simple surfactants has been hindered by the broad range of applications in water containing alkaline earth metals (i.e., hard water). This disrupts surfactant function and requires extensive use of undesirable and expensive chelating additives. We show that sugar-derived furans can be linked with triglyceride-derived fatty acid chains via Friedel–Crafts acylation within single layer (SPP) zeolite catalysts. Finally, these alkylfuran surfactants independently suppress the effects of hard water whilemore » simultaneously permitting broad tunability of size, structure, and function, which can be optimized for superior capability for forming micelles and solubilizing in water.« less

Tunable Oleo-Furan Surfactants by Acylation of Renewable Furans

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Dae Sung; Joseph, Kristeen E.; Koehle, Maura

2016-11-23

An important advance in fluid surface control was the amphiphilic surfactant comprised of coupled molecular structures (i.e. hydrophilic and hydrophobic) to reduce surface tension between two distinct fluid phases. However, implementation of simple surfactants has been hindered by the broad range of applications in water containing alkaline earth metals (i.e. hard water), which disrupt surfactant function and require extensive use of undesirable and expensive chelating additives. Here we show that sugar-derived furans can be linked with triglyceride-derived fatty acid chains via Friedel-Crafts acylation within single layer (SPP) zeolite catalysts. These alkylfuran surfactants independently suppress the effects of hard water whilemore » simultaneously permitting broad tunability of size, structure, and function, which can be optimized for superior capability for forming micelles and solubilizing in water.« less

Occurrence of the herbicide glyphosate and its metabolite AMPA in surface waters in Switzerland determined with on-line solid phase extraction LC-MS/MS.

PubMed

Poiger, Thomas; Buerge, Ignaz J; Bächli, Astrid; Müller, Markus D; Balmer, Marianne E

2017-01-01

Glyphosate is currently one of the most important herbicides worldwide. Its unique properties provide for a wide range of uses in agriculture but also in non-agricultural areas. At the same time, its zwitterionic nature prevents the inclusion in multi-residue analytical methods for environmental monitoring. Consequently, despite its extensive use, data on occurrence of glyphosate in the aquatic environment is still scarce. Based on existing methods, we developed a simplified procedure for the determination of glyphosate and its main metabolite aminomethylphosphonic acid (AMPA) in water samples using derivatization with fluorenylmethyl chloroformate FMOC-Cl, combined with on-line solid phase extraction and liquid chromatography-tandem mass spectrometry (LC-MS/MS) detection. This method was extensively tested on over 1000 samples of surface water, groundwater, and treated wastewater and proved to be simple, sensitive, and reliable. Limits of quantification of 0.005 μg/L were routinely achieved. Glyphosate and AMPA were detected in the vast majority of stream water samples in the area of Zurich, Switzerland, with median concentrations of 0.11 and 0.20 μg/L and 95th percentile concentrations of 2.1 and 2.6 μg/L, respectively. Stream water data and data from treated wastewater indicated that non-agricultural uses may significantly contribute to the overall loads of glyphosate and AMPA in surface waters. In the investigated groundwater samples, selected specifically because they had shown presence of other herbicides in previous monitoring programs, glyphosate and AMPA were generally not detected, except for two monitoring sites in Karst aquifers, indicating that these compounds show much less tendency for leaching.

Aufeis accumulations in stream bottoms in arctic and subarctic environments as a possible indicator of geologic structure: Chapter F in Recent U.S. Geological Survey studies in the Tintina Gold Province, Alaska, United States, and Yukon, Canada--results of a 5-year project

USGS Publications Warehouse

Wanty, Richard B.; Wang, Bronwen; Vohden, Jim; Day, Warren C.; Gough, Larry P.; Gough, Larry P.; Day, Warren C.

2007-01-01

The thickest (>3 meters) and most extensive aufeis (100’s of meters to kilometers along valleys) coincided with locations of laterally extensive (>5 kilometers) mapped high-angle brittle fault zones, suggesting that the fault zones are hydraulically conductive. Additional evidence of water flow is provided by observed changes in stream-water chemistry in reaches in which aufeis forms, despite a lack of surface tributaries. Minor or no aufeis was observed in many other drainage valleys where no laterally extensive structures have been mapped, implying that aufeis formation results from more than a topographic effect or discharge from bank storage. Thus, the presence of thick, laterally extensive aufeis in highgradient streams may be a useful aid to geologic structural mapping in arctic and subarctic climates.

Spatiotemporal distribution and risk assessment of organotins in the surface water of the Three Gorges Reservoir Region, China.

PubMed

Gao, Jun-Min; Wu, Lei; Chen, You-Peng; Zhou, Bin; Guo, Jin-Song; Zhang, Ke; Ouyang, Wen-Juan

2017-03-01

The water quality security of the Three Gorges Reservoir during different operating periods has been a subject of recent concern. This study is the first to report the spatiotemporal variability of organotins (OTs) in surface water under dynamic water level conditions in the Three Gorges Reservoir Region (TGRR). TGRR surface water was collected during three monitoring campaigns to analyze butyltins (BTs) and phenyltins (PTs) using a gas chromatography-mass spectrometry system. Our results showed that TGRR surface water was polluted by BTs and PTs, with mono-OTs being the dominant species. A wide range of BTs and PTs concentrations was observed across the study area, but tributyltin (TBT) displayed extensive spatial distribution, and the highest concentrations consistently occurred in the downstream region of the TGRR study area, with a maximum of 393.35 ng Sn/L in Zigui (S27). The total OTs contamination level decreased over time. The diphenyltin concentration exhibited significant seasonal variation, while other OTs showed seasonal changes only during two monitoring campaigns, with the exception of dibutyltin. An ecological risk assessment indicated that both TBT and triphenyltin posed risks to aquatic organisms in TGRR surface water. We urgently recommend continuous monitoring and further measures to prevent and control OTs pollution in the TGRR. Copyright © 2016 Elsevier Ltd. All rights reserved.

Physically Accurate Soil Freeze-Thaw Processes in a Global Land Surface Scheme

NASA Astrophysics Data System (ADS)

Cuntz, Matthias; Haverd, Vanessa

2018-01-01

The model Soil-Litter-Iso (SLI) calculates coupled heat and water transport in soil. It was recently implemented into the Australian land surface model CABLE, which is the land component of the Australian Community Climate and Earth System Simulator (ACCESS). Here we extended SLI to include accurate freeze-thaw processes in the soil and snow. SLI provides thence an implicit solution of the energy and water balances of soil and snow as a standalone model and within CABLE. The enhanced SLI was tested extensively against theoretical formulations, laboratory experiments, field data, and satellite retrievals. The model performed well for all experiments at wide-ranging temporal and spatial scales. SLI melts snow faster at the end of the cold season compared to observations though because there is no subgrid variability within SLI given by the implicit, coupled solution of energy and water. Combined CABLE-SLI shows very realistic dynamics and extent of permafrost on the Northern hemisphere. It illustrated, however, also the limits of possible comparisons between large-scale land surface models and local permafrost observations. CABLE-SLI exhibits the same patterns of snow depth and snow water equivalent on the Northern hemisphere compared to satellite-derived observations but quantitative comparisons depend largely on the given meteorological input fields. Further extension of CABLE-SLI with depth-dependence of soil carbon will allow realistic projections of the development of permafrost and frozen carbon stocks in a changing climate.

Development of a classical force field for the oxidized Si surface: application to hydrophilic wafer bonding.

PubMed

Cole, Daniel J; Payne, Mike C; Csányi, Gábor; Spearing, S Mark; Colombi Ciacchi, Lucio

2007-11-28

We have developed a classical two- and three-body interaction potential to simulate the hydroxylated, natively oxidized Si surface in contact with water solutions, based on the combination and extension of the Stillinger-Weber potential and of a potential originally developed to simulate SiO(2) polymorphs. The potential parameters are chosen to reproduce the structure, charge distribution, tensile surface stress, and interactions with single water molecules of a natively oxidized Si surface model previously obtained by means of accurate density functional theory simulations. We have applied the potential to the case of hydrophilic silicon wafer bonding at room temperature, revealing maximum room temperature work of adhesion values for natively oxidized and amorphous silica surfaces of 97 and 90 mJm(2), respectively, at a water adsorption coverage of approximately 1 ML. The difference arises from the stronger interaction of the natively oxidized surface with liquid water, resulting in a higher heat of immersion (203 vs 166 mJm(2)), and may be explained in terms of the more pronounced water structuring close to the surface in alternating layers of larger and smaller densities with respect to the liquid bulk. The computed force-displacement bonding curves may be a useful input for cohesive zone models where both the topographic details of the surfaces and the dependence of the attractive force on the initial surface separation and wetting can be taken into account.

Expanded Target-Chemical Analysis Reveals Extensive Mixed-Organic-Contaminant Exposure in U.S. Streams

EPA Science Inventory

Surface-water from 38 streams nation-wide was assessed using 14 target-organic methods (719 compounds). Designedbioactive anthropogenic contaminants (biocides, pharmaceuticals) comprised 57% of 406 organics detected at least once. The 10 most-frequently detected anthropogenic-org...

APPLICATION OF SEMIPERMEABLE MEMBRANE DEVICES TO INDOOR AIR SAMPLING

EPA Science Inventory

Semipermeable membrane devices (SPMDs) are a relatively new passive sampling technique for nonpolar organic compounds that have been extensively used for surface water sampling. A small body of literature indicates that SPMDs are also useful for air sampling. Because SPMDs ha...

Use of experimentally determined Henry's Law and salting-out constants for ethanol in seawater for determination of the saturation state of ethanol in coastal waters.

PubMed

Willey, Joan D; Powell, Jacqueline P; Avery, G Brooks; Kieber, Robert J; Mead, Ralph N

2017-09-01

The Henry's law constant for ethanol in seawater was experimentally determined to be 221 ± 4 M/atm at 22 °C compared with 247 ± 6 M/atm in pure water. The salting out coefficient for ethanol was 0.13 M -1 . In seawater ln(K H ) = -(12.8 ± 0.7) + (5310 ± 197)/T where K H is in M atm -1 and temperature is in K. This plus the salting out coefficient allow calculation of K H for any estuarine or sea water between 1 and 35 °C. High concentrations of dissolved organic carbon do not affect K H values in fresh or seawater. Nearshore surface waters were usually undersaturated with respect to gas phase ethanol except when air concentrations decreased, whereas surface seawater 40 km from shore was supersaturated. The percent saturation in surface waters is driven primarily by changes in air concentrations because these change quickly (hours) and more extensively than surface water. This study allows calculation of ethanol saturation states from air and surface water concentrations which is a necessary step to define the role of surface oceans in the global biogeochemical cycling of ethanol both now and in the future as use of ethanol biofuel continues to grow. Copyright © 2017 Elsevier Ltd. All rights reserved.

Interfacial thermodynamics of water and six other liquid solvents.

PubMed

Pascal, Tod A; Goddard, William A

2014-06-05

We examine the thermodynamics of the liquid-vapor interface by direct calculation of the surface entropy, enthalpy, and free energy from extensive molecular dynamics simulations using the two-phase thermodynamics (2PT) method. Results for water, acetonitrile, cyclohexane, dimethyl sulfoxide, hexanol, N-methyl acetamide, and toluene are presented. We validate our approach by predicting the interfacial surface tensions (IFT--excess surface free energy per unit area) in excellent agreement with the mechanical calculations using Kirkwood-Buff theory. Additionally, we evaluate the temperature dependence of the IFT of water as described by the TIP4P/2005, SPC/Ew, TIP3P, and mW classical water models. We find that the TIP4P/2005 and SPC/Ew water models do a reasonable job of describing the interfacial thermodynamics; however, the TIP3P and mW are quite poor. We find that the underprediction of the experimental IFT at 298 K by these water models results from understructured surface molecules whose binding energies are too weak. Finally, we performed depth profiles of the interfacial thermodynamics which revealed long tails that extend far into what would be considered bulk from standard Gibbs theory. In fact, we find a nonmonotonic interfacial free energy profile for water, a unique feature that could have important consequences for the absorption of ions and other small molecules.

Air-water CO2 and CH4 fluxes along a river-reservoir continuum: Case study in the Pengxi River, a tributary of the Yangtze River in the Three Gorges Reservoir, China.

PubMed

Huang, Yang; Yasarer, Lindsey M W; Li, Zhe; Sturm, Belinda S M; Zhang, Zengyu; Guo, Jinsong; Shen, Yu

2017-05-01

Water surface greenhouse gas (GHG) emissions in freshwater reservoirs are closely related to limnological processes in the water column. Affected by both reservoir operation and seasonal changes, variations in the hydro-morphological conditions in the river-reservoir continuum will create distinctive patterns in water surface GHG emissions. A one-year field survey was carried out in the Pengxi River-reservoir continuum, a part of the Three Gorges Reservoir (TGR) immediately after the TGR reached its maximum water level. The annual average water surface CO 2 and CH 4 emissions at the riverine background sampling sites were 6.23 ± 0.93 and 0.025 ± 0.006 mmol h -1  m -2 , respectively. The CO 2 emissions were higher than those in the downstream reservoirs. The development of phytoplankton controlled the downstream decrease in water surface CO 2 emissions. The presence of thermal stratification in the permanent backwater area supported extensive phytoplankton blooms, resulting in a carbon sink during several months of the year. The CH 4 emissions were mainly impacted by water temperature and dissolved organic carbon. The greatest water surface CH 4 emission was detected in the fluctuating backwater area, likely due to a shallower water column and abundant organic matter. The Pengxi River backwater area did not show significant increase in water surface GHG emissions reported in tropical reservoirs. In evaluating the net GHG emissions by the impoundment of TGR, the net change in the carbon budget and the contribution of nitrogen and phosphorus should be taken into consideration in this eutrophic river-reservoir continuum.

The nature of the air-cleaved mica surface

NASA Astrophysics Data System (ADS)

Christenson, Hugo K.; Thomson, Neil H.

2016-06-01

The accepted image of muscovite mica is that of an inert and atomically smooth surface, easily prepared by cleavage in an ambient atmosphere. Consequently, mica is extensively used a model substrate in many fundamental studies of surface phenomena and as a substrate for AFM imaging of biomolecules. In this review we present evidence from the literature that the above picture is not quite correct. The mica used in experimental work is almost invariably cleaved in laboratory air, where a reaction between the mica surface, atmospheric CO2 and water occurs immediately after cleavage. The evidence suggests very strongly that as a result the mica surface becomes covered by up to one formula unit of K2CO3 per nm2, which is mobile under humid conditions, and crystallises under drier conditions. The properties of mica in air or water vapour cannot be fully understood without reference to the surface K2CO3, and many studies of the structure of adsorbed water on mica surfaces may need to be revisited. With this new insight, however, the air-cleaved mica should provide exciting opportunities to study phenomena such as two-dimensional ion diffusion, electrolyte effects on surface conductivity, and two-dimensional crystal nucleation.

Quantification of surface water volume changes in the Mackenzie Delta using satellite multi-mission data

NASA Astrophysics Data System (ADS)

Normandin, Cassandra; Frappart, Frédéric; Lubac, Bertrand; Bélanger, Simon; Marieu, Vincent; Blarel, Fabien; Robinet, Arthur; Guiastrennec-Faugas, Léa

2018-02-01

Quantification of surface water storage in extensive floodplains and their dynamics are crucial for a better understanding of global hydrological and biogeochemical cycles. In this study, we present estimates of both surface water extent and storage combining multi-mission remotely sensed observations and their temporal evolution over more than 15 years in the Mackenzie Delta. The Mackenzie Delta is located in the northwest of Canada and is the second largest delta in the Arctic Ocean. The delta is frozen from October to May and the recurrent ice break-up provokes an increase in the river's flows. Thus, this phenomenon causes intensive floods along the delta every year, with dramatic environmental impacts. In this study, the dynamics of surface water extent and volume are analysed from 2000 to 2015 by combining multi-satellite information from MODIS multispectral images at 500 m spatial resolution and river stages derived from ERS-2 (1995-2003), ENVISAT (2002-2010) and SARAL (since 2013) altimetry data. The surface water extent (permanent water and flooded area) peaked in June with an area of 9600 km2 (±200 km2) on average, representing approximately 70 % of the delta's total surface. Altimetry-based water levels exhibit annual amplitudes ranging from 4 m in the downstream part to more than 10 m in the upstream part of the Mackenzie Delta. A high overall correlation between the satellite-derived and in situ water heights (R > 0.84) is found for the three altimetry missions. Finally, using altimetry-based water levels and MODIS-derived surface water extents, maps of interpolated water heights over the surface water extents are produced. Results indicate a high variability of the water height magnitude that can reach 10 m compared to the lowest water height in the upstream part of the delta during the flood peak in June. Furthermore, the total surface water volume is estimated and shows an annual variation of approximately 8.5 km3 during the whole study period, with a maximum of 14.4 km3 observed in 2006. The good agreement between the total surface water volume retrievals and in situ river discharges (R = 0.66) allows for validation of this innovative multi-mission approach and highlights the high potential to study the surface water extent dynamics.

Louisiana ground-water map no. 1: potentiometric surface, 1985, and water-level changes, 1983-85, of the Chicot aquifer in southwestern Louisiana

USGS Publications Warehouse

Fendick, Robert B.; Nyman, Dale J.

1987-01-01

The Chicot aquifer is the principle source of groundwater in southwestern Louisiana and is the most extensively pumped (nearly 1 billion gallons per day) aquifer in the State. Withdrawals from the Chicot aquifer are used primarily for irrigation. Two maps show the generalized potentiometric surfaces of the upper sand unit ('200-ft ' sand in the Lake Charles area) and the ' 500-ft ' sand of the Chicot aquifer. General water level altitudes and flow directions may be inferred from these maps which were prepared in cooperation with the Louisiana Department of Transportation and Development, Office of Public Works. Previous studies of groundwater hydrology in southwestern Louisiana are included in selected references. (Lantz-PTT)

Study on the number density of nanobubbles at varying concentration of ethanol in ethanol-water solution

NASA Astrophysics Data System (ADS)

Rajib, Md. Mahadi; Farzeen, Parisa; Ali, Mohammad

2017-12-01

In recent years, nanobubble technology has drawn great attention due to its extensive incorporation to substantial aspects of science and technology such as water treatment, drug delivery enhancement to cells, solvent and nutritional supplements manufacturing and many others. Bulk nanobubbles may be present in most aqueous solutions, possibly being constantly created by cosmic radiation and agitation and surface nanobubbles are present at most surfaces [1,2]. But, for utilizing these nanobubbles in a definitive way it's important to know whether an added amount of solution making substance has constructive or adverse effect on the nanobubble. In this work, the change of number density of nanobubbles in ethanol-water solution was studied by varying the ethanol concentration.

From Vegetated Ditches to Rice Fields: Thinking Outside the Box for Pesticide Mitigation

USDA-ARS?s Scientific Manuscript database

Innovative mitigation strategies are necessary to address pesticide contamination of surface waters. Since 1998, extensive research has been conducted on the ability of vegetated agricultural drainage ditches to reduce pesticide transport to aquatic receiving systems. Recently, new research has pr...

EFFECT OF SIMAZINE ON MALE REPRODUCTIVE DEVELOPMENT IN THE RAT

EPA Science Inventory

The chlorotriazine herbicides, such as atrazine, are used extensively in the United States each year. Chlorotriazine metabolites, as well as the parent compounds, have been detected in surface and ground water in areas of major usage. Previously, we found that atrazine delayed ...

Green Roofs: Federal Energy Management Program (FEMP) Federal Technology Alert

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scholz-Barth, K.; Tanner, S.

In a ''green roof,'' a layer of vegetation (e.g., a roof garden) covers the surface of a roof to provide shade, cooler indoor and outdoor temperatures, and effective storm-water management to reduce runoff. The main components are waterproofing, soil, and plants. There are two basic kinds: intensive and extensive. An intensive green roof often features large shrubs and trees, and it can be expensive to install and maintain. An extensive green roof features shallow soil and low-growing, horizontally spreading plants that can thrive in the alpine conditions of many rooftops. These plants do not require a lot of water ormore » soil, and they can tolerate a significant amount of exposure to the sun and wind. This Federal Technology Alert focuses on the benefits, design, and implementation of extensive green roofs and includes criteria for their use on federal facilities.« less

Regional hydrology and simulation of deep ground-water flow in the Southeastern Coastal Plain aquifer system in Mississippi, Alabama, Georgia, and South Carolina

USGS Publications Warehouse

Barker, R.A.; Pernik, Maribeth

1994-01-01

The Southeastern Coastal Plain aquifer system is a coastward-sloping, wedge-shaped sand and gravel reservoir exposed in outcrop to a humid climate and drained by an extensive surface-water network. Ground-water pumpage has increased to about 765 cubic feet per second since 1900, causing water-level declines of more than 150 feet in places, while base flow to major streams has decreased about 350 cubic feet per second. The water-level declines and adjustments in recharge and discharge are not expected to seriously restrict future ground-water development.

Experimental and theoretical evidence for bilayer-by-bilayer surface melting of crystalline ice

PubMed Central

Sánchez, M. Alejandra; Kling, Tanja; Ishiyama, Tatsuya; van Zadel, Marc-Jan; Mezger, Markus; Jochum, Mara N.; Cyran, Jenée D.; Smit, Wilbert J.; Bakker, Huib J.; Shultz, Mary Jane; Morita, Akihiro; Donadio, Davide; Nagata, Yuki; Bonn, Mischa; Backus, Ellen H. G.

2017-01-01

On the surface of water ice, a quasi-liquid layer (QLL) has been extensively reported at temperatures below its bulk melting point at 273 K. Approaching the bulk melting temperature from below, the thickness of the QLL is known to increase. To elucidate the precise temperature variation of the QLL, and its nature, we investigate the surface melting of hexagonal ice by combining noncontact, surface-specific vibrational sum frequency generation (SFG) spectroscopy and spectra calculated from molecular dynamics simulations. Using SFG, we probe the outermost water layers of distinct single crystalline ice faces at different temperatures. For the basal face, a stepwise, sudden weakening of the hydrogen-bonded structure of the outermost water layers occurs at 257 K. The spectral calculations from the molecular dynamics simulations reproduce the experimental findings; this allows us to interpret our experimental findings in terms of a stepwise change from one to two molten bilayers at the transition temperature. PMID:27956637

Molecular dynamics simulation of potentiometric sensor response: the effect of biomolecules, surface morphology and surface charge.

PubMed

Lowe, B M; Skylaris, C-K; Green, N G; Shibuta, Y; Sakata, T

2018-05-10

The silica-water interface is critical to many modern technologies in chemical engineering and biosensing. One technology used commonly in biosensors, the potentiometric sensor, operates by measuring the changes in electric potential due to changes in the interfacial electric field. Predictive modelling of this response caused by surface binding of biomolecules remains highly challenging. In this work, through the most extensive molecular dynamics simulation of the silica-water interfacial potential and electric field to date, we report a novel prediction and explanation of the effects of nano-morphology on sensor response. Amorphous silica demonstrated a larger potentiometric response than an equivalent crystalline silica model due to increased sodium adsorption, in agreement with experiments showing improved sensor response with nano-texturing. We provide proof-of-concept that molecular dynamics can be used as a complementary tool for potentiometric biosensor response prediction. Effects that are conventionally neglected, such as surface morphology, water polarisation, biomolecule dynamics and finite-size effects, are explicitly modelled.

The Water Content of Martian Recurring Slope Lineae: Insights from THEMIS Thermal Infrared Data

NASA Astrophysics Data System (ADS)

Edwards, C. S.; Piqueux, S.

2016-12-01

Observations of Recurring Slope Lineae (RSL) have been interpreted as present-day, seasonally variable liquid water flows; however, orbital spectroscopy has not confirmed the presence of liquid H2O, only hydrated salts. Thermal Emission Imaging System (THEMIS) temperature data and a numerical heat transfer model definitively constrain the amount of water associated with RSL.We examine a well characterized RSL-site in Valles Marineris on the walls of Garni crater, with extensive daytime and nighttime THEMIS coverage. In addition to having been characterized in detail with HiRISE data, this area is suitable for thermal analysis as it displays: 1) limited bedrock outcrops at the origination of the RSL, avoiding anisothermal behaviors with slope materials; 2) high density of RSL terrain versus dry slope material (typically 40% and up to 88% of a THEMIS pixel) maximizing RSL-bearing signal; 3) an extensive areal region, encompassing multiple THEMIS pixels; 4) seasonal THEMIS coverage. Surface temperature differences between RSL-bearing and dry RSL-free terrains are consistent with no water associated with RSL and, based on measurement uncertainties, limit the water content of RSL to at most 0.5-3 wt%. In addition, distinct high thermal inertia regolith signatures expected with evaporitic salt deposits from cyclical briny water flows are not observed, indicating low water salinity (if any), and/or low enough volumes to prevent their formation. Alternatively, the observed salts may be pre-existing in soils at low abundances (i.e. near or below detection limits) and largely immobile. These RSL-rich surfaces experience 100K diurnal temperature oscillations, possible freeze/thaw cycles and/or complete evaporation on timescales that challenge their habitability potential. The unique surface temperature measurements provided by THEMIS are consistent with a dry RSL hypothesis, or at least significantly limit the water content of martian RSL.

Revealing Surface Waters on an Antifreeze Protein by Fusion Protein Crystallography Combined with Molecular Dynamic Simulations.

PubMed

Sun, Tianjun; Gauthier, Sherry Y; Campbell, Robert L; Davies, Peter L

2015-10-08

Antifreeze proteins (AFPs) adsorb to ice through an extensive, flat, relatively hydrophobic surface. It has been suggested that this ice-binding site (IBS) organizes surface waters into an ice-like clathrate arrangement that matches and fuses to the quasi-liquid layer on the ice surface. On cooling, these waters join the ice lattice and freeze the AFP to its ligand. Evidence for the generality of this binding mechanism is limited because AFPs tend to crystallize with their IBS as a preferred protein-protein contact surface, which displaces some bound waters. Type III AFP is a 7 kDa globular protein with an IBS made up two adjacent surfaces. In the crystal structure of the most active isoform (QAE1), the part of the IBS that docks to the primary prism plane of ice is partially exposed to solvent and has clathrate waters present that match this plane of ice. The adjacent IBS, which matches the pyramidal plane of ice, is involved in protein-protein crystal contacts with few surface waters. Here we have changed the protein-protein contacts in the ice-binding region by crystallizing a fusion of QAE1 to maltose-binding protein. In this 1.9 Å structure, the IBS that fits the pyramidal plane of ice is exposed to solvent. By combining crystallography data with MD simulations, the surface waters on both sides of the IBS were revealed and match well with the target ice planes. The waters on the pyramidal plane IBS were loosely constrained, which might explain why other isoforms of type III AFP that lack the prism plane IBS are less active than QAE1. The AFP fusion crystallization method can potentially be used to force the exposure to solvent of the IBS on other AFPs to reveal the locations of key surface waters.

Influence of the Yukon River on the Bering Sea

NASA Technical Reports Server (NTRS)

Dean, K.; Mcroy, C. P.

1987-01-01

The distribution of near-surface, turbid water, discharged by the Yukon River, was studied based on analysis of satellite imagery. The interannual analyses indicates that the net flow of near-surface, turbid water is northward of the delta across the entrance to Norton Sound. Only turbid water to the east enters Norton Sound and consists of 25% of the total area. Approximately 10% of the water circulates into the sound along the southern coast and is lost to view in the vicinity of Unalakleet. Suspended sediments transported by this southern circulation are primarily deposited along the southern coast. Three distinct zones within the turbid water were identified based on relative brightness levels. These zones appear to be primarily related to differences in suspended-sediment concentrations and position of the sediments in the water column. The extent of turbid water varies seasonally. It is most extensive June through October even though discharge of the Yukon River decreases substantially after July.

Chemical quality of ground water in the eastern Sacramento Valley, California

USGS Publications Warehouse

Fogelman, Ronald P.

1979-01-01

The study area is about 1,300 square miles in the eastern Sacramento Valley, Calif., extending from the latitude of Roseville on the south to thelatitude of Chico on the north. Considering the increased agricultural development of the area, this report documents the chemical character of the ground water prior to water-level declines that could result from extensive pumping for irrigation or to changes caused by extensive use of imported surface water. Chemical analyses of samples from 222 wells show that most of the area is underlain by ground water of a quality suitable for most agricultural and domestic purposes. Ninety-five percent of the water sampled has dissolved-solids concentrations of less than 700 milligrams per liter. The general water type for the area is a calcium and magnesium bicarbonate water and there are negligible amounts of toxic trace elements. The potential for water-quality problems exists in the area south of Yuba City along the west bank of the Feather River. There, concentrations of chloride, sulfate, and dissolved solids are higher than in other parts of the area, and they could limit future agricultural activities if chloride- and sulfate-sensitive crops are grown. (Woodard-USGS)

Water-based oligochitosan and nanowhisker chitosan as potential food preservatives for shelf-life extension of minced pork.

PubMed

Chantarasataporn, Patomporn; Tepkasikul, Preenapha; Kingcha, Yutthana; Yoksan, Rangrong; Pichyangkura, Rath; Visessanguan, Wonnop; Chirachanchai, Suwabun

2014-09-15

Water-based chitosans in the forms of oligochitosan (OligoCS) and nanowhisker chitosan (CSWK) are proposed as a novel food preservative based on a minced pork model study. The high surface area with a positive charge over the neutral pH range (pH 5-8) of OligoCS and CSWK lead to an inhibition against Gram-positive (Staphylococcus aureus, Listeria monocytogenes, and Bacillus cereus) and Gram-negative microbes (Salmonella enteritidis and Escherichia coli O157:H7). In the minced pork model, OligoCS effectively performs a food preservative for shelf-life extension as clarified from the retardation of microbial growth, biogenic amine formation and lipid oxidation during the storage. OligoCS maintains almost all myosin heavy chain protein degradation as observed in the electrophoresis. The present work points out that water-based chitosan with its unique morphology not only significantly inhibits antimicrobial activity but also maintains the meat quality with an extension of shelf-life, and thus has the potential to be used as a food preservative. Copyright © 2014 Elsevier Ltd. All rights reserved.

Water resources and hydrology of Mars

NASA Technical Reports Server (NTRS)

Baker, V. R.; Gulick, V. C.; Kargel, J. S.; Strom, R. G.

1991-01-01

The surface of Mars has been extensively modified by a large variety of water erosional and depositional processes. Although liquid water is presently unstable on the planet's surface, in its cold, hyperarid climate, there is abundant geomorphological evidence of past fluvial valley development multiple episodes of catastrophic flooding, periglacial landforms, ice-related permafrost, lake deposits, eroded impact craters and possible glacial landforms throughout much of Mars' geological history. The amount of water required to form such features is estimated to be equivalent to a planet-wide layer approximately 50 meters deep. Some of this water undoubtedly was removed from the planet by atmospheric escape processes, but much probably remains in the subsurface of Mars. Jakosky summarized the present partitioning of water on Mars, expressed as an average global depth, as follows: in the polar caps, 30 meters; in the megaregolith, 500 to 1000 meters; structurally bound in clays, 10 meters; and in high latitude regolith, a few meters. However, most of this water is probably in the form of ice, except in anomalous areas of possible near surface liquid water, and in regions where hydrothermal systems are still active. The best locations for prospecting are those areas where water or ice is sufficiently concentrated at shallow enough depths to make it feasible to pump out or mine.

Ceres Evolution: From Thermodynamic Modeling and Now Dawn Observation

NASA Astrophysics Data System (ADS)

McCord, T. B.; Combe, J. P.; Castillo, J. C.; Raymond, C. A.; De Sanctis, M. C.; Jaumann, R.; Ammannito, E.; Russell, C. T.

2015-12-01

Thermodynamic modeling indicated that Ceres has experienced planetary processes, including extensive melting of its ~25% water and differentiation, (McCord and Sotin, JGR, 2005; Castillo and McCord, Icarus, 2009). Early telescopic studies showed Ceres' surface to be spectrally similar to carboneous-chondrite-like material, i.e., aqueously altered silicates darkened by carbon, with a water-OH-related absorption near 3.06 µm. Later observations improved the spectra and suggested more specific interpretations: Structural water in clay minerals, phyllosilicates, perhaps ammoniated, iron-rich clays, carbonates, brucite, all implying extensive aqueous alteration, perhaps in the presence of CO2. Telescopic observations and thermodynamic models predicted Dawn would find a very different body compared to Vesta (e.g. McCord et al., SSR, 2011), as current Dawn observations are confirming. Ceres' original water ice should have melted early in its evolution, with the resulting differentiation and mineralization strongly affecting Ceres' composition, size and shape over time. The ocean should have become very salty and perhaps may still be liquid in places. The surface composition from telescopes seems to reflect this complex history. The mineralization with repeated mixing of the crust with the early liquid interior and with in-fall from space would create a complex surface that will present an interpretation challenge for Dawn. The Dawn spacecraft is currently collecting observations of Ceres' landforms, elemental and mineralogical/molecular composition and gravity field from orbit. Early results suggest a heavily cratered but distorted and lumpy body with features and composition consistent with internal activity, perhaps recent or current, associated with water and perhaps other volatiles. We will present and interpret the latest Dawn Ceres findings and how they affect our earlier understanding of Ceres evolution from modeling and telescope observations.

Generation of Hot Water from Hot-Dry for Heavy-Oil Recovery in Northern Alberta, Canada

NASA Astrophysics Data System (ADS)

Pathak, V.; Babadagli, T.; Majorowicz, J. A.; Unsworth, M. J.

2011-12-01

The focus of prior applications of hot-dry-rock (HDR) technology was mostly aimed at generating electricity. In northern Alberta, the thermal gradient is low and, therefore, this technology is not suitable for electricity generation. On the other hand, the cost of steam and hot water, and environmental impacts, are becoming critical issues in heavy-oil and bitumen recovery in Alberta. Surface generation of steam or hot-water accounts for six percent of Canada's natural gas consumption and about 50 million tons of CO2 emission. Lowered cost and environmental impacts are critical in the widespread use of steam (for in-situ recovery) and hot-water (for surface extraction of bitumen) in this region. This paper provides an extensive analysis of hot-water generation to be used in heavy-oil/bitumen recovery. We tested different modeling approaches used to determine the amount of energy produced during HDR by history matching to example field data. The most suitable numerical and analytical models were used to apply the data obtained from different regions containing heavy-oil/bitumen deposits in northern Alberta. The heat generation capacity of different regions was determined and the use of this energy (in the form of hot-water) for surface extraction processes was evaluated. Original temperature gradients were applied as well as realistic basement formation characteristics through an extensive hydro thermal analysis in the region including an experimental well drilled to the depth of 2,500m. Existing natural fractures and possible hydraulic fracturing scenarios were evaluated from the heat generation capacity and the economics points of view. The main problem was modeling difficulties, especially determination and representation of fracture network characteristics. A sensitivity analysis was performed for the selected high temperature gradient regions in Alberta. In this practice, the characteristics of hydraulic fractures, injection rate, depth, the distance between injection and production wells and formation thickness were used as variables and an optimization study was carried out based on these variables. The results showed that the hot water (50 C at surface) needed in Fort McMurray for extraction could be obtained at lower costs than the generation of it using natural gas.

Dynamics of Wetting of Ultra Hydrophobic Surfaces

NASA Astrophysics Data System (ADS)

Mohammad Karim, Alireza; Kim, Jeong-Hyun; Rothstein, Jonathan; Kavehpour, Pirouz; Mechanical and Industrial Engineering, University of Massachusetts, Amherst Collaboration

2013-11-01

Controlling the surface wettability of hydrophobic and super hydrophobic surfaces has extensive industrial applications ranging from coating, painting and printing technology and waterproof clothing to efficiency increase in power and water plants. This requires enhancing the knowledge about the dynamics of wetting on these hydrophobic surfaces. We have done experimental investigation on the dynamics of wetting on hydrophobic surfaces by looking deeply in to the dependency of the dynamic contact angles both advancing and receding on the velocity of the three-phase boundary (Solid/Liquid/Gas interface) using the Wilhelmy plate method with different ultra-hydrophobic surfaces. Several fluids with different surface tension and viscosity are used to study the effect of physical properties of liquids on the governing laws.

First-principles study of Cs/Rb co-doped FAPbI3 stability and degradation in the presence of water and oxygen

NASA Astrophysics Data System (ADS)

Guo, Yao; Li, Chengbo; Xue, Yuanbin; Geng, Cuihuan; Tian, Dayong

2018-02-01

The poor stability of organometallic halide perovskite in humid environments is one of the biggest challenges for its commercialization in light harvesting and electroluminescent displays. Understanding the atomic detail of the perovskite/water (oxygen) interface is a critical way to explore the practicability of perovskite. In this work, we report a density functional study of water and oxygen adsorption on the Cs/Rb incorporated FAPbI3 (001) surface. The role played by water and oxygen molecules has been extensively studied in the initial degradation processes, where the strong interactions between adsorbates and perovskite surfaces are confirmed. Our results show that the dopant-terminated surface was relatively more stable than PbI2-termination one. The effects of doping on the optoelectronic properties were slight at low concentrations. The calculations showed that the molecule tend to adsorb on the I-top site of the Cs-terminated surface and the Pb-top site of the PbI2 (Cs)-terminated surface. The vdW contribution on the bonding between bare surface and molecule can be observed. The degradation-induced optical absorption decrease in the visible region could be found. Water and oxygen molecule destroy the perovskite surface structures and subsequently reduce its conversion efficiency. These findings contribute molecular-level insight into the initial stage of perovskite degradation, which should be helpful to inspire new interfacial modifications to improve the stability of corresponding perovskite materials under wet conditions.

Genes and Structural Proteins of the Phage Syn5 of the Marine Cyanobacteria Synechococcus

DTIC Science & Technology

2005-09-01

typhimurium phage P22, a podoviridae, was shown to possess extensive genomic similarity to coliphage lambda, a siphoviridae (Botstein and Herskowitz...are found among cyanobacteria in the surface waters during the winter. Temperature influences the number of infectious particles produced during lytic...grids and stained with 1% uranyl acetate for 15 minutes, washed three times in double-distilled water , stained in 1% lead citrate for 4 minutes, and

Synthesis of tin-containing polyimide films

NASA Technical Reports Server (NTRS)

Ezzell, S. A.; Taylor, L. T.

1984-01-01

A series of tin-containing polyimide films derived from either 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride or pyromellitic dianhydride and 4,4'-oxydianiline have been synthesized and their electrical properties examined. Highest quality materials (i.e., homogeneous, smooth surface, flexible) with the best electrical properties were doped with either SnCl2.2H2O or (n-Bu)2SnCl2. In all cases, extensive reactivity of the tin dopant with water, air or polyamic acid during imidization is observed. Lowered electrical surface resistivities appear to be correlatable with the presence of surface tin oxide on the film surface.

Linking atmospheric synoptic transport, cloud phase, surface energy fluxes, and sea-ice growth: observations of midwinter SHEBA conditions

NASA Astrophysics Data System (ADS)

Persson, P. Ola G.; Shupe, Matthew D.; Perovich, Don; Solomon, Amy

2017-08-01

Observations from the Surface Heat Budget of the Arctic Ocean (SHEBA) project are used to describe a sequence of events linking midwinter long-range advection of atmospheric heat and moisture into the Arctic Basin, formation of supercooled liquid water clouds, enhancement of net surface energy fluxes through increased downwelling longwave radiation, and reduction in near-surface conductive heat flux loss due to a warming of the surface, thereby leading to a reduction in sea-ice bottom growth. The analyses provide details of two events during Jan. 1-12, 1998, one entering the Arctic through Fram Strait and the other from northeast Siberia; winter statistics extend the results. Both deep, precipitating frontal clouds and post-frontal stratocumulus clouds impact the surface radiation and energy budget. Cloud liquid water, occurring preferentially in stratocumulus clouds extending into the base of the inversion, provides the strongest impact on surface radiation and hence modulates the surface forcing, as found previously. The observations suggest a minimum water vapor threshold, likely case dependent, for producing liquid water clouds. Through responses to the radiative forcing and surface warming, this cloud liquid water also modulates the turbulent and conductive heat fluxes, and produces a thermal wave penetrating into the sea ice. About 20-33 % of the observed variations of bottom ice growth can be directly linked to variations in surface conductive heat flux, with retarded ice growth occurring several days after these moisture plumes reduce the surface conductive heat flux. This sequence of events modulate pack-ice wintertime environmental conditions and total ice growth, and has implications for the annual sea-ice evolution, especially for the current conditions of extensive thinner ice.

Summary of hydrologic data collected during 1974 in Dade County, Florida

USGS Publications Warehouse

Hull, J.E.

1975-01-01

This report is ninth in a series documenting the annual hydrologic conditions in Dade County, Florida. The hydrologic conditions in Dade County for the 1974 water year (October 1, 1973 to September 30, 1974) except for rainfall are summarized in tables, graphs, and maps. The locations of ground-water data-collection stations are shown in figure 1, rainfall and surface-water stations in figure 2, and water quality sampling stations in figure 43. As shown, the network of stations is extensive. The long-term records (1940 to 1974) furnish background information vital in the analysis of effects of water-management practices.

Estimating variations in global surface water storage

NASA Astrophysics Data System (ADS)

Lettenmaier, D. P.

2016-12-01

Arguably, the most dramatic advances attributable to remote sensing in the hydrologic sciences have involved the extension of knowledge about processes and state variables from the scale of field experiments to regions, continents, and the entire Earth. However, despite the availability of information about total terrestrial water storage over large areas provided by the Gravity Recovery and Climate Experiment (GRACE) mission, we still have remarkably little knowledge of the magnitude of freshwater stored at and near the land surface, and its temporal scales of variation. This is especially true with respect to freshwater storage in natural lakes and manmade reservoirs. Estimates of the amount of water that could be stored in artificial reservoirs are in the neighborhood of 15% of the mean annual runoff from the continents or around 7-8000 km3. However, while global reservoir storage was increasing through about 1980 due to filling of new reservoirs constructed in the second half of the 20th century, it is not even known whether aggregate usable reservoir storage is increasing or decreasing, due to sedimentation effects. With the advent of satellite altimeters (mostly intended to measure ocean surface topography and or the surface elevation of glaciers and ice sheets), along with improved methods for estimating space-time variations in the extent of surface waters, new opportunities have arisen to piece together estimates of storage variations of fractions approaching one-half of the global surface water storage, for periods approaching two decades in some cases. Although this ability is nascent, it offers encouragement that, with the launch of the planned Surface Water and Ocean Topography (SWOT) satellite mission in 2020, which has as a specific objective the measurement of surface water variations, climate-scale understanding of this source of variability in Earth's surface water balance may be at hand. I discuss specific examples of the technology and resulting data sets, including successes and failures.

Potentiometric Surface of the Upper and Lower Aquifers of the North Coast Limestone Aquifer System and Hydrologic Conditions in the Arecibo-Manati Area, Puerto Rico, November 27-December 1, 2006

USGS Publications Warehouse

Rodriguez, Jose M.; Gómez-Gómez, Fernando

2008-01-01

A ground-water level synoptic survey of the limestone aquifer in the Arecibo to Manati area, Puerto Rico, was conducted from November 27 through December 1, 2006 by the U.S. Geological Survey in cooperation with the Puerto Rico Department of Natural and Environmental Resources. The purpose of the study was to define the spatial distribution of the potentiometric surface of the upper and lower aquifers of the North Coast limestone aquifer system. A potentiometric surface is defined as an areal representation of the levels to which water would rise in tightly cased wells open to an aquifer (Fetter, 1988). These potentiometric surface maps can be used by water-resources planners to understand the general direction of ground-water flow and to evaluate ground-water conditions for water supply and resource protection. The study was conducted during a period of rising ground-water levels resulting from above-normal rainfall during October and November 2006 when rainfall amount was about 30 percent above normal. The study area encompassed 125 square miles and was bounded to the north by the Atlantic Ocean, to the south by the southern extension of the limestone units, to the west by the Rio Grande de Arecibo, and to the east by the Rio Grande de Manati (pls. 1 and 2; inset).

Sorption of pathogens during sub-surface drip irrigation with wastewater

NASA Astrophysics Data System (ADS)

Levi, Laillach; Gillerman Gillerman, Leonid; Kalavrouziotis, Ioannis; Oron, Gideon

2017-04-01

Water scarcity continues to be one of the major threats to human survival in many regions worldwide, such as Africa, the Mediterranean Basin, the State of California in the US. Due to a mixture of factors such as population growth, reduction in water resources availability and higher demand for high quality waters in these regions these countries face water shortage issues that stem from overuse, extensive extraction of groundwater, and frequent drought events. In addition, there are increases in environmental and health awareness that have led to intensive efforts in the treatment and reuse of nonconventional water sources, mainly wastewater and greywater. One approach to water shortages issues is to use wastewater as means to close the gap between supply and demand. However, the need to treat wastewater and to disinfect it forces additional economic burden on the users, primarily for agricultural irrigation. A possible solution might be to use the soil as a sorbent for the contained pathogens. Under sub-surface drip irrigation, not allowing the wastewater to reach the soil surface, the pathogens will remain in the soil. It was as well shown in field experiments that the opening size of roots will not allow pathogens to penetrate into the plants. Additional advantages such as water saving, protection of the pipe systems and others are also important. Field experiments in commercial fields just emphasize the main advantages of sub-surface drip irrigation.

Nuflood, Version 1.x

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tasseff, Byron

2016-07-29

NUFLOOD Version 1.x is a surface-water hydrodynamic package designed for the simulation of overland flow of fluids. It consists of various routines to address a wide range of applications (e.g., rainfall-runoff, tsunami, storm surge) and real time, interactive visualization tools. NUFLOOD has been designed for general-purpose computers and workstations containing multi-core processors and/or graphics processing units. The software is easy to use and extensible, constructed in mind for instructors, students, and practicing engineers. NUFLOOD is intended to assist the water resource community in planning against water-related natural disasters.

SURFACE WATER FLOW IN LANDSCAPE MODELS: 1. EVERGLADES CASE STUDY. (R824766)

EPA Science Inventory

Many landscape models require extensive computational effort using a large array of grid cells that represent the landscape. The number of spatial cells may be in the thousands and millions, while the ecological component run in each of the cells to account for landscape dynamics...

VITELLOGENIN GENE EXPRESSION IN MALE FATHEAD MINNOWS EXPOSED TO DI(2-ETHYLHEXYL)PHTHALATE

EPA Science Inventory

Di(2-ethylhexyl) phthalate (DEHP) is a plasticizer used extensively in the plastics industry. DEHP has been shown to be ubiquitous in the environment and has been detected in ground and surface waters, sediment sludge and at several Superfund sites. Previous studies using rats ...

Potential of Prolamins from Maize and Sorghum to Form Gluten-like Structures in Wheat-free Bread

USDA-ARS?s Scientific Manuscript database

Prolamins from maize (zeins) are known to form viscoelastic, extensible, cohesive dough when mixed together with starch and water above their glass transition temperature (Tg, approximately 28 °C). By adding hydroxypropyl methylcellulose (HPMC, a surface-active hydrocolloid) to this formulation, lea...

Extensive Liquid Meltwater Storage in Firn Within the Greenland Ice Sheet

NASA Technical Reports Server (NTRS)

Forster, Richard R.; Box, Jason E.; vandenBroeke, Michael R.; Miege, Clement; Burgess, Evan W.; vanAngelen, Jan H.; Lenaerts, Jan T. M.; Koenig, Lora S.; Paden, John; Lewis, Cameron;

On the hydration of subnanometric antifouling organosilane adlayers: a molecular dynamics simulation.

PubMed

Sheikh, Sonia; Blaszykowski, Christophe; Nolan, Robert; Thompson, Damien; Thompson, Michael

2015-01-01

The connection between antifouling and surface hydration is a fascinating but daunting question to answer. Herein, we use molecular dynamics (MD) computer simulations to gain further insight into the role of surface functionalities in the molecular-level structuration of water (surface kosmotropicity)--within and atop subnanometric organosilane adlayers that were shown in previous experimental work to display varied antifouling behavior. Our simulations support the hypothesized intimate link between surface hydration and antifouling, in particular the importance of both internal and interfacial hydrophilicity and kosmotropicity. The antifouling mechanism is also discussed in terms of surface dehydration energy and water dynamicity (lability and mobility), notably the crucial requirement for clustered water molecules to remain tightly bound for extensive periods of time--i.e. exhibit slow exchange dynamics. A substrate effect on surface hydration, which would also participate in endowing antifouling adlayers with hydrogel-like characteristics, is also proposed. In contrast, the role of adlayer flexibility, if any, is assigned a secondary role in these ultrathin structures made of short building blocks. The conclusions from this work are well in line with those previously drawn in the literature. Copyright © 2014 Elsevier Inc. All rights reserved.

Application of Time-Domain Electromagnetic Method in Investigating Saltwater Intrusion of Santiago Island (Cape Verde)

NASA Astrophysics Data System (ADS)

Gonçalves, Rui; Farzamian, Mohammad; Monteiro Santos, Fernando A.; Represas, Patrícia; Mota Gomes, A.; Lobo de Pina, A. F.; Almeida, Eugénio P.

2017-11-01

Santiago Island, the biggest and most populated island of the Cape Verde Republic, is characterised by limited surface waters and strong dependence on groundwater sources as the primary source of natural water supply for extensive agricultural activity and human use. However, as a consequence of the scarce precipitation and high evaporation as well as the intense overexploitation of the groundwater resources, the freshwater management is also in a delicate balance with saltwater at coastal areas. The time-domain electromagnetic (TDEM) method is used to locate the extent of saltwater intrusion in four important agricultural regions in Santiago Island; São Domingos, Santa Cruz, São Miguel, and Tarrafal. The application of this method in Santiago Island proves it to be a successful tool in imaging the fresh/saltwater interface location. Depths to the saline zones and extensions of saline water are mapped along eight TDEM profiles.

The spectroscopic chemical and photophysical properties of Martian soils and their analogs

NASA Technical Reports Server (NTRS)

Coyne, Lelia M.

1987-01-01

The program of research outlined should advance significantly the understanding of the spectral signal of montmorillonites in general and the variations produced in it by structural and surface ferric and ferrous iron and interlayer water as a function of several environmental conditions that are different between Earth and Mars. In addition, an extensive data base was collected providing spectral characterization of several features (iron, both surface and structural, OH-groups, both structural and from adsorbed water and O(-) centers) that are known, or thought to be, influential in directing the surface activity of these important materials. With this data base with which to assess the results of the Viking labeled release simulation studies, it should be possible to gain important insights into the mechanisms of surface reactivity for this important chemical reaction. The results to be gained from these studies will provide a significant body of ground base truth from which to assess: the presence of smectite clays on Mars; the mineralogical form in which the Martian iron is bound; establish upper limits on the present surface water content of Martian soils; perhaps provide insights on the Martian surface radiation history; and to make strong predictions about the nature of surface chemistry on Mars, if iron-bearing clays are a significant component of the surface mineralogical assemblage.

Electromyographic signal and force comparisons during maximal voluntary isometric contraction in water and on dry land.

PubMed

Pinto, Stephanie Santana; Liedtke, Giane Veiga; Alberton, Cristine Lima; da Silva, Eduardo Marczwski; Cadore, Eduardo Lusa; Kruel, Luiz Fernando Martins

2010-11-01

This study was designed to compare surface electromyographic (sEMG) signal and force production during maximal voluntary isometric contractions (MVCs) in water and on dry land. The reproducibility of sEMG and isometric force measurements between water and dry land environments was also assessed. Nine women performed MVC for elbow flexion and extension, hip flexion, and extension against identical fixed resistance in both environments. The sEMG signal from biceps brachii, triceps brachii, rectus femoris, and biceps femoris was recorded with waterproof adhesives placed over each electrode. The sEMG and force production showed no significant difference between water and dry land, except for HEX (p = 0.035). In addition, intraclass correlation coefficient values were significant and ranged from moderate to high (0.66-0.96) for sEMG and force production between environments. These results showed that the environment did not influence the sEMG and force in MVC.

Variability of Changjiang Diluted Water revealed by a 45-year long-term ocean hindcast and Self-Organizing Maps analysis

NASA Astrophysics Data System (ADS)

Zeng, Xiangming; He, Ruoying; Zong, Haibo

2017-08-01

Based on long-term realistic ocean circulation hindcast for in the Bohai, Yellow, and East China Seas, 45 years (1961-2005) of sea surface salinity data were analyzed using Self-Organizing Maps (SOM) to have a better understanding of the Changjiang Diluted Water (CDW) variation. Three spatial patterns were revealed by the SOM: normal, transition, and extension. The normal pattern mainly occurs from December to May while the CDW hugs China's east coast closely and flows southward. The extension pattern is dominant from June to October when the CDW extends northwestward toward Jeju Island in an omega shape. The transition pattern prevails for the rest of the year. Pattern-averaged temperature, circulation, and chlorophyll-a concentration show significant differences. CDW area and its eastern most extension were explored as a function of the Changjiang runoff and regional upwelling index. We found that Changjiang runoff and upwelling index can be reasonable predictors for the overall CDW area, while ambient circulation determines the distribution and structure of the CDW, and thus the CDW eastern most extension.

Modeling the Surface Water-Groundwater Interaction in Arid and Semi-Arid Regions Impacted by Agricultural Activities

NASA Astrophysics Data System (ADS)

Tian, Y.; Wu, B.; Zheng, Y.

2013-12-01

In many semi-arid and arid regions, interaction between surface water and groundwater plays an important role in the eco-hydrological system. The interaction is often complicated by agricultural activities such as surface water diversion, groundwater pumping, and irrigation. In existing surface water-groundwater integrated models, simulation of the interaction is often simplified, which could introduce significant simulation uncertainty under certain circumstance. In this study, GSFLOW, a USGS model coupling PRMS and MODFLOW, was improved to better characterize the surface water-groundwater interaction. The practices of water diversion from rivers, groundwater pumping and irrigation are explicitly simulated. In addition, the original kinematic wave routing method was replaced by a dynamic wave routing method. The improved model was then applied in Zhangye Basin (the midstream part of Heihe River Baisn), China, where the famous 'Silk Road' came through. It is a typical semi-arid region of the western China, with extensive agriculture in its oasis. The model was established and calibrated using the data in 2000-2008. A series of numerical experiments were conducted to evaluate the effect of those improvements. It has been demonstrated that with the improvements, the observed streamflow and groundwater level were better reproduced by the model. The improvements have a significant impact on the simulation of multiple fluxes associated with the interaction, such as groundwater discharge, riverbed seepage, infiltration, etc. Human activities were proved to be key elements of the water cycle in the study area. The study results have important implications to the water resources modeling and management in semi-arid and arid basins.

Spacebased Observation of Water Balance Over Global Oceans

NASA Astrophysics Data System (ADS)

Liu, W.; Xie, X.

2008-12-01

We demonstrated that ocean surface fresh water flux less the water discharge into the ocean from river and ice melt balances the mass loss in the ocean both in magnitude and in the phase of annual variation. The surface water flux was computed from the divergence of the water transport integrated over the depth of the atmosphere. The atmospheric water transport is estimated from the precipitable water measured by Special Sensor Microwave Imager, the surface wind vector by QuikSCAT, and the NOAA cloud drift wind through a statistical model. The transport has been extensively validated using global radiosonde and data and operational numerical weather prediction results. Its divergence has been shown to agree with the difference between evaporation estimated from the Advanced Microwave Scanning Radiometer data and the precipitation measured by Tropical Rain Measuring Mission over the global tropical and subtropical oceans both in magnitude and geographical distribution for temporal scales ranging from intraseasonal to interannual. The water loss rate in the ocean is estimated by two methods, one is from Gravity Recovery and Climate Experiment and the other is by subtracting the climatological steric change from the sea level change measured by radar altimeter on Jason. Only climatological river discharge and ice melt from in situ measurements are available and the lack of temporal variation may contribute to discrepancies in the balance. We have successfully used the spacebased surface fluxes to estimate to climatological mean heat transport in the Atlantic ocean and is attempting to estimate the meridional fresh water (or salt) transport from the surface flux. The approximate closure of the water balance gives a powerful indirect validation of the spacebased products.

Near-field Oblique Remote Sensing of Stream Water-surface Elevation, Slope, and Surface Velocity

NASA Astrophysics Data System (ADS)

Minear, J. T.; Kinzel, P. J.; Nelson, J. M.; McDonald, R.; Wright, S. A.

2014-12-01

A major challenge for estimating discharges during flood events or in steep channels is the difficulty and hazard inherent in obtaining in-stream measurements. One possible solution is to use near-field remote sensing to obtain simultaneous water-surface elevations, slope, and surface velocities. In this test case, we utilized Terrestrial Laser Scanning (TLS) to remotely measure water-surface elevations and slope in combination with surface velocities estimated from particle image velocimetry (PIV) obtained by video-camera and/or infrared camera. We tested this method at several sites in New Mexico and Colorado using independent validation data consisting of in-channel measurements from survey-grade GPS and Acoustic Doppler Current Profiler (ADCP) instruments. Preliminary results indicate that for relatively turbid or steep streams, TLS collects tens of thousands of water-surface elevations and slopes in minutes, much faster than conventional means and at relatively high precision, at least as good as continuous survey-grade GPS measurements. Estimated surface velocities from this technique are within 15% of measured velocity magnitudes and within 10 degrees from the measured velocity direction (using extrapolation from the shallowest bin of the ADCP measurements). Accurately aligning the PIV results into Cartesian coordinates appears to be one of the main sources of error, primarily due to the sensitivity at these shallow oblique look angles and the low numbers of stationary objects for rectification. Combining remotely-sensed water-surface elevations, slope, and surface velocities produces simultaneous velocity measurements from a large number of locations in the channel and is more spatially extensive than traditional velocity measurements. These factors make this technique useful for improving estimates of flow measurements during flood flows and in steep channels while also decreasing the difficulty and hazard associated with making measurements in these conditions.

Ocean-Atmosphere Interaction Over Agulhas Extension Meanders

NASA Technical Reports Server (NTRS)

Liu, W. Timothy; Xie, Xiaosu; Niiler, Pearn P.

2007-01-01

Many years of high-resolution measurements by a number of space-based sensors and from Lagrangian drifters became available recently and are used to examine the persistent atmospheric imprints of the semi-permanent meanders of the Agulhas Extension Current (AEC), where strong surface current and temperature gradients are found. The sea surface temperature (SST) measured by the Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) and the chlorophyll concentration measured by the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) support the identification of the meanders and related ocean circulation by the drifters. The collocation of high and low magnitudes of equivalent neutral wind (ENW) measured by Quick Scatterometer (QuikSCAT), which is uniquely related to surface stress by definition, illustrates not only the stability dependence of turbulent mixing but also the unique stress measuring capability of the scatterometer. The observed rotation of ENW in opposition to the rotation of the surface current clearly demonstrates that the scatterometer measures stress rather than winds. The clear differences between the distributions of wind and stress and the possible inadequacy of turbulent parameterization affirm the need of surface stress vector measurements, which were not available before the scatterometers. The opposite sign of the stress vorticity to current vorticity implies that the atmosphere spins down the current rotation through momentum transport. Coincident high SST and ENW over the southern extension of the meander enhance evaporation and latent heat flux, which cools the ocean. The atmosphere is found to provide negative feedback to ocean current and temperature gradients. Distribution of ENW convergence implies ascending motion on the downwind side of local SST maxima and descending air on the upwind side and acceleration of surface wind stress over warm water (deceleration over cool water); the convection may escalate the contrast of ENW over warm and cool water set up by the dependence of turbulent mixing on stability; this relation exerts a positive feedback to the ENW-SST relation. The temperature sounding measured by the Atmospheric Infrared Sounder(AIRS) is consistent with the spatial coherence between the cloud-top temperature provided by the International Satellite Cloud Climatology Project (ISCCP) and SST. Thus ocean mesoscale SST anomalies associated with the persistent meanders may have a long-term effect well above the midlatitude atmospheric boundary layer, an observation not addressed in the past.

Rough surface adhesion in the presence of capillary condensation

DOE PAGES

DelRio, Frank W.; Dunn, Martin L.; Phinney, Leslie M.; ...

2007-04-17

Capillary condensation of water can have a significant effect on rough surface adhesion. Here, to explore this phenomenon between micromachined surfaces, the authors perform microcantilever experiments as a function of surface roughness and relative humidity (RH). Below a threshold RH, the adhesion is mainly due to van der Waals forces across extensive noncontacting areas. Above the threshold RH, the adhesion jumps due to capillary condensation and increases towards the upper limit of Γ=144mJ/m 2. Lastly, a detailed model based on the measured surface topography qualitatively agrees with the experimental data only when the topographic correlations between the upper and lowermore » surfaces are considered.« less

The Impact of Post-Pretreatment Conditioning on Enzyme Accessibility and Water Interactions in Alkali Pretreated Rice Straw

NASA Astrophysics Data System (ADS)

Karuna, Nardrapee

Rice straw, a high-abundance lignocellulosic residue from rice production has tremendous potential as a feedstock for biofuel production in California. In this study, the impact of post-alkali pretreatment conditioning schemes on enzyme saccharification efficiency was examined, particularly focusing on understanding resulting biomass compositional impacts on water interactions with the biomass and enzyme accessibility to the cellulose fraction. Rice straw was pretreated with sodium hydroxide and subsequently washed by two different conditions: 1) by extensive washing with distilled water to reduce the pH to the optimum for cellulases which is pH 5--6, and 2) immediate pH adjustment to pH 5--6 with hydrochloric acid before extensive washing with distilled water. The two post-pretreatment conditions gave significant differences in ash, acid-insoluble lignin, glucan and xylan compositions. Alkali pretreatment improved cellulase digestibility of rice straw, and water washing improved enzymatic digestibility more than neutralization. Hydrolysis reactions with a purified Trichoderma reesei Cel7A, a reducing-end specific cellulase, demonstrated that the differences in saccharification are likely due to differences in the accessibility of the cellulose fraction to the cellulolytic enzymes. Further analyses were conducted to study the mobility of the water associated with the rice straw samples by measuring T2 relaxation times of the water protons by 1H-Nuclear Magnetic Resonance (NMR) relaxometry. Results showed significant changes in water association with the rice straw due to the pretreatment and due to the two different post-pretreatment conditions. Pretreatment increased the amount of water at the surface of the rice straw samples as indicated by increased amplitude of the shortest T2 time peaks in the relaxation spectra. Moreover, the amount of water in the first T2 pool in the water washed sample was significantly greater than in the neutralized sample. These results suggest that the specific surface area of rice straw accessible to water protons was increased by the alkali pretreatment, likely due to solubilization of alkali-soluble components of the cell walls. Post-pretreatment processes resulted in differences in the specific surface area likely due to re-precipitation of alkali solubilized components during neutralization. The T2 relaxation times of the surface water pool in washed and raw rice straw were not significantly different, at 4.4 and 4.5 ms, respectively, but both T2 times were significantly shorter than that of the neutralized and then washed sample, at 5.5 ms. The expectation was that the T2 times of the surface water peaks would reflect differences in surface composition of the rice straw samples. Further analysis of surface composition is necessary to further interpret the shortest T2 times observed in the samples. The T2 spectra of the rice straw samples contained longer T2 time peaks that were interpreted as differences in porosity of the rice straw due to the treatments. Pretreatment caused physical changes to rice straw that impacted water organization (3 peaks to 4 peaks), but the amount of water in the peaks were greater in the washed rice straw than the neutralized rice straw suggesting that water-washed rice straw had more of the larger pores than the neutralized and then washed rice straw. One possible explanation is that the neutralization caused precipitation of alkali solubilized components that filled the volumes of the pores.

Factors Affecting Source-Water Quality after Disturbance of Forests by Wildfire

NASA Astrophysics Data System (ADS)

Murphy, S. F.; Martin, D. A.; McCleskey, R. B.; Writer, J. H.

2015-12-01

Forests yield high-quality water supplies to communities throughout the world, in part because forest cover reduces flooding and the consequent transport of suspended and dissolved constituents to surface water. Disturbance by wildfire reduces or eliminates forest cover, leaving watersheds susceptible to increased surface runoff during storms and reduced ability to retain contaminants. We assessed water-quality response to hydrologic events for three years after a wildfire in the Fourmile Creek Watershed, near Boulder, Colorado, and found that hydrologic and geochemical responses downstream of a burned area were primarily driven by small, brief convective storms that had relatively high, but not unusual, rainfall intensity. Total suspended sediment, dissolved organic carbon, nitrate, and manganese concentrations were 10-156 times higher downstream of a burned area compared to upstream, and water quality was sufficiently impaired to pose water-treatment concerns. The response in both concentration and yield of water-quality constituents differed depending on source availability and dominant watershed processes controlling the constituent. For example, while all constituent concentrations were highest during storm events, annual sediment yields downstream of the burned area were controlled by storm events and subsequent mobilization, whereas dissolved organic carbon yields were more dependent on spring runoff from upstream areas. The watershed response was affected by a legacy of historical disturbance: the watershed had been recovering from extensive disturbance by mining, railroad and road development, logging, and fires in the late 19th and early 20th centuries, and we observed extensive erosion of mine waste in response to these summer storms. Therefore, both storm characteristics and historical disturbance in a burned watershed must be considered when evaluating the role of wildfire on water quality.

Adsorption at air-water and oil-water interfaces and self-assembly in aqueous solution of ethoxylated polysorbate nonionic surfactants.

PubMed

Penfold, Jeffrey; Thomas, Robert K; Li, Peixun X; Petkov, Jordan T; Tucker, Ian; Webster, John R P; Terry, Ann E

2015-03-17

The Tween nonionic surfactants are ethoxylated sorbitan esters, which have 20 ethylene oxide groups attached to the sorbitan headgroup and a single alkyl chain, lauryl, palmityl, stearyl, or oleyl. They are an important class of surfactants that are extensively used in emulsion and foam stabilization and in applications associated with foods, cosmetics and pharmaceuticals. A range of ethoxylated polysorbate surfactants, with differing degrees of ethoxylation from 3 to 50 ethylene oxide groups, have been synthesized and characterized by neutron reflection, small-angle neutron scattering, and surface tension. In conjunction with different alkyl chain groups, this provides the opportunity to modify their surface properties, their self-assembly in solution, and their interaction with macromolecules, such as proteins. Adsorption at the air-water and oil-water interfaces and solution self-assembly of the range of ethoxylated polysorbate surfactants synthesized are presented and discussed.

Potentiometric Surface of the Aquia Aquifer in Southern Maryland, September 2007

USGS Publications Warehouse

Curtin, Stephen E.; Andreasen, David C.; Staley, Andrew W.

2009-01-01

This report presents a map showing the potentiometric surface of the Aquia aquifer in the Aquia Formation of Paleocene age in Southern Maryland during September 2007. The map is based on water-level measurements in 85 wells. The highest measured water level was 50 feet above sea level near the northern boundary and outcrop area of the aquifer in the central part of Anne Arundel County, and was below sea level just south of this area and in the remainder of the study area. The hydraulic gradient increased southeastward toward an extensive cone of depression around well fields at Lexington Park and Solomons Island. A water level measured west of the Cheasapeake Beach area has declined to 57 feet below sea level due to increased withdrawals. The lowest water level measured was 162 feet below sea level at the center of a cone of depression at Lexington Park.

Recurring slope lineae in equatorial regions of Mars

USGS Publications Warehouse

McEwen, Alfred S.; Dundas, Colin M.; Mattson, Sarah S.; Toigo, Anthony D.; Ojha, Lujendra; Wray, James J.; Chojnacki, Matthew; Byrne, Shane; Murchie, Scott L.; Thomas, Nicolas

2014-01-01

The presence of liquid water is a requirement of habitability on a planet. Possible indicators of liquid surface water on Mars include intermittent flow-like features observed on sloping terrains. These recurring slope lineae are narrow, dark markings on steep slopes that appear and incrementally lengthen during warm seasons on low-albedo surfaces. The lineae fade in cooler seasons and recur over multiple Mars years. Recurring slope lineae were initially reported to appear and lengthen at mid-latitudes in the late southern spring and summer and are more common on equator-facing slopes where and when the peak surface temperatures are higher. Here we report extensive activity of recurring slope lineae in equatorial regions of Mars, particularly in the deep canyons of Valles Marineris, from analysis of data acquired by the Mars Reconnaissance Orbiter. We observe the lineae to be most active in seasons when the slopes often face the sun. Expected peak temperatures suggest that activity may not depend solely on temperature. Although the origin of the recurring slope lineae remains an open question, our observations are consistent with intermittent flow of briny water. Such an origin suggests surprisingly abundant liquid water in some near-surface equatorial regions of Mars.

Bayesian evidence for the prevalence of waterworlds

NASA Astrophysics Data System (ADS)

Simpson, Fergus

2017-07-01

Should we expect most habitable planets to share the Earth's marbled appearance? For a planetary surface to boast extensive areas of both land and water, a delicate balance must be struck between the volume of water it retains and the capacity of its perturbations. These two quantities may show substantial variability across the full spectrum of water-bearing worlds. This would suggest that, barring strong feedback effects, most surfaces are heavily dominated by either water or land. Why is the Earth so finely poised? To address this question, we construct a simple model for the selection bias that would arise within an ensemble of surface conditions. Based on the Earth's ocean coverage of 71 per cent, we find substantial evidence (Bayes factor K ≃ 6) supporting the hypothesis that anthropic selection effects are at work. Furthermore, due to the Earth's proximity to the waterworld limit, this model predicts that most habitable planets are dominated by oceans spanning over 90 per cent of their surface area (95 per cent credible interval). This scenario, in which the Earth has a much greater land area than most habitable planets, is consistent with results from numerical simulations and could help explain the apparently low-mass transition in the mass-radius relation.

Effective micro-spray cooling for light-emitting diode with graphene nanoporous layers

NASA Astrophysics Data System (ADS)

Keong Lay, Kok; Yew Cheong, Brian Mun; Li Tong, Wei; Tan, Ming Kwang; Hung, Yew Mun

2017-04-01

A graphene nanoplatelet (GNP) coating is utilized as a functionalized surface in enhancing the evaporation rate of micro-spray cooling for light-emitting diodes (LEDs). In micro-spray cooling, water is atomized into micro-sized droplets to reduce the surface energy and to increase the surface area for evaporation. The GNP coating facilitates the effective filmwise evaporation through the attribute of fast water permeation. The oxygenated functional groups of GNPs provide the driving force that initiates the intercalation of water molecules through the carbon nanostructure. The water molecules slip through the frictionless passages between the hydrophobic carbon walls, resulting an effective filmwise evaporation. The enhancement of evaporation leads to an enormous temperature reduction of 61.3 °C. The performance of the LED is greatly enhanced: a maximum increase in illuminance of 25% and an extension of power rating from 9 W to 12 W can be achieved. With the application of GNP coating, the high-temperature region is eliminated while maintaining the LED surface temperature for optimal operation. This study paves the way for employing the effective hybrid spray-evaporation-nanostructure technique in the development of a compact, low-power-consumption cooling system.

Effects of the Extended Water Retention Curve on Coupled Heat and Water Transport in the Vadose Zone

NASA Astrophysics Data System (ADS)

Yang, Z.; Mohanty, B.

2017-12-01

Understanding and simulating coupled heat and water transfer appropriately in the shallow subsurface is of vital significance for accurate prediction of soil evaporation that would improve the coupling between land surface and atmosphere. The theory of Philip and de Vries (1957) and its extensions (de Vries, 1958; Milly, 1982), although physically incomplete, are still adopted successfully to describe the coupled heat and water movement in field soils. However, the adsorptive water retention, which was ignored in Philip and de Vries theory and its extensions for characterizing soil hydraulic parameters, was shown to be non-negligible for soil moisture and evaporation flux calculation in dry field soils based on a recent synthetic analysis (Mohanty and Yang, 2013). In this study, we attempt to comprehensively investigate the effects of full range water retention curve on coupled heat and water transport simulation with a focus on soil moisture content, temperature and soil evaporative flux, based on two synthetic (sand and loam) and two field sites (Riverside, California and Audubon, Arizona) analysis. The results of synthetic sand and loam numerical modeling showed that when neglecting the adsorptive water retention, the resulting simulated soil water content would be larger, and the evaporative flux would be lower, respectively, compared to that obtained by the full range water retention curve mode. The simulated temperature did not show significant difference with or without accounting for adsorptive water retention. The evaporation underestimation when neglecting the adsorptive water retention is mainly caused by isothermal hydraulic conductivity underprediction. These synthetic findings were further corroborated by the Audubon, Arizona field site experimental results. The results from Riverside, California field experimental site showed that the soil surface can reach very dry status, although the soil profile below the drying front is not dry, which also to some extent justifies the necessity of employing full range water retention function in such generally not quite dry scenarios.

A comparative study of surface energies and water adsorption on Ce-bastnäsite, La-bastnäsite, and calcite via density functional theory and water adsorption calorimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goverapet Srinivasan, Sriram; Shivaramaiah, Radha; Kent, Paul R. C.

Bastnäsite, a fluoro-carbonate mineral, is the single largest mineral source of light rare earth elements (REE), La, Ce and Nd. Enhancing the efficiency of separation of the mineral from gangue through froth flotation is the first step towards meeting an ever increasing demand for REE. To design and evaluate collector molecules that selectively bind to bastnäsite, a fundamental understanding of the structure and surface properties of bastnäsite is essential. In our earlier work (J Phys Chem C, 2016, 120, 16767), we carried out an extensive study of the structure, surface stability and water adsorption energies of La-bastnäsite. Here in thismore » work, we make a comparative study of the surface properties of Ce-bastnäsite, La-bastnäsite, and calcite using a combination of density functional theory (DFT) and water adsorption calorimetry. Spin polarized DFT+U calculations show that the exchange interaction between the electrons in Ce 4f orbitals is negligible and that these orbitals do not participate in bonding with the oxygen atom of the adsorbed water molecule. In agreement with calorimetry, DFT calculations predict larger surface energies and stronger water adsorption energies on Ce-bastnäsite than on La-bastnäsite. The order of stabilities for stoichiometric surfaces is as follows: [100] > [101] > [102] > [0001] > [112] > [104] and the most favorable adsorption sites for water molecules are the same as for La-bastnäsite. In agreement with water adsorption calorimetry, at low coverage water molecules are strongly stabilized via coordination to the surface Ce3+ ions, whereas at higher coverage they are adsorbed less strongly via hydrogen bonding interaction with the surface anions. Lastly, due to similar water adsorption energies on bastnäsite [101] and calcite [104] surfaces, the design of collector molecules that selectively bind to bastnäsite over calcite must exploit the structural differences in the predominantly exposed facets of these minerals.« less

A comparative study of surface energies and water adsorption on Ce-bastnäsite, La-bastnäsite, and calcite via density functional theory and water adsorption calorimetry

DOE PAGES

Goverapet Srinivasan, Sriram; Shivaramaiah, Radha; Kent, Paul R. C.; ...

2017-02-24

Bastnäsite, a fluoro-carbonate mineral, is the single largest mineral source of light rare earth elements (REE), La, Ce and Nd. Enhancing the efficiency of separation of the mineral from gangue through froth flotation is the first step towards meeting an ever increasing demand for REE. To design and evaluate collector molecules that selectively bind to bastnäsite, a fundamental understanding of the structure and surface properties of bastnäsite is essential. In our earlier work (J Phys Chem C, 2016, 120, 16767), we carried out an extensive study of the structure, surface stability and water adsorption energies of La-bastnäsite. Here in thismore » work, we make a comparative study of the surface properties of Ce-bastnäsite, La-bastnäsite, and calcite using a combination of density functional theory (DFT) and water adsorption calorimetry. Spin polarized DFT+U calculations show that the exchange interaction between the electrons in Ce 4f orbitals is negligible and that these orbitals do not participate in bonding with the oxygen atom of the adsorbed water molecule. In agreement with calorimetry, DFT calculations predict larger surface energies and stronger water adsorption energies on Ce-bastnäsite than on La-bastnäsite. The order of stabilities for stoichiometric surfaces is as follows: [100] > [101] > [102] > [0001] > [112] > [104] and the most favorable adsorption sites for water molecules are the same as for La-bastnäsite. In agreement with water adsorption calorimetry, at low coverage water molecules are strongly stabilized via coordination to the surface Ce3+ ions, whereas at higher coverage they are adsorbed less strongly via hydrogen bonding interaction with the surface anions. Lastly, due to similar water adsorption energies on bastnäsite [101] and calcite [104] surfaces, the design of collector molecules that selectively bind to bastnäsite over calcite must exploit the structural differences in the predominantly exposed facets of these minerals.« less

A comparative study of surface energies and water adsorption on Ce-bastnäsite, La-bastnäsite, and calcite via density functional theory and water adsorption calorimetry.

PubMed

Goverapet Srinivasan, Sriram; Shivaramaiah, Radha; Kent, Paul R C; Stack, Andrew G; Riman, Richard; Anderko, Andre; Navrotsky, Alexandra; Bryantsev, Vyacheslav S

2017-03-15

Bastnäsite, a fluoro-carbonate mineral, is the single largest mineral source of light rare earth elements (REE), La, Ce and Nd. Enhancing the efficiency of separation of the mineral from gangue through froth flotation is the first step towards meeting an ever increasing demand for REE. To design and evaluate collector molecules that selectively bind to bastnäsite, a fundamental understanding of the structure and surface properties of bastnäsite is essential. In our earlier work (J. Phys. Chem. C, 2016, 120, 16767), we carried out an extensive study of the structure, surface stability and water adsorption energies of La-bastnäsite. In this work, we make a comparative study of the surface properties of Ce-bastnäsite, La-bastnäsite, and calcite using a combination of density functional theory (DFT) and water adsorption calorimetry. Spin polarized DFT+U calculations show that the exchange interaction between the electrons in Ce 4f orbitals is negligible and that these orbitals do not participate in bonding with the oxygen atom of the adsorbed water molecule. In agreement with calorimetry, DFT calculations predict larger surface energies and stronger water adsorption energies on Ce-bastnäsite than on La-bastnäsite. The order of stabilities for stoichiometric surfaces is as follows: [101[combining macron]0] > [101[combining macron]1] > [101[combining macron]2] > [0001] > [112[combining macron]2] > [101[combining macron]4] and the most favorable adsorption sites for water molecules are the same as for La-bastnäsite. In agreement with water adsorption calorimetry, at low coverage water molecules are strongly stabilized via coordination to the surface Ce 3+ ions, whereas at higher coverage they are adsorbed less strongly via hydrogen bonding interaction with the surface anions. Due to similar water adsorption energies on bastnäsite [101[combining macron]1] and calcite [101[combining macron]4] surfaces, the design of collector molecules that selectively bind to bastnäsite over calcite must exploit the structural differences in the predominantly exposed facets of these minerals.

Coastal flood inundation monitoring with Satellite C-band and L-band Synthetic Aperture Radar data

USGS Publications Warehouse

Ramsey, Elijah W.; Rangoonwala, Amina; Bannister, Terri

2013-01-01

Satellite Synthetic Aperture Radar (SAR) was evaluated as a method to operationally monitor the occurrence and distribution of storm- and tidal-related flooding of spatially extensive coastal marshes within the north-central Gulf of Mexico. Maps representing the occurrence of marsh surface inundation were created from available Advanced Land Observation Satellite (ALOS) Phased Array type L-Band SAR (PALSAR) (L-band) (21 scenes with HH polarizations in Wide Beam [100 m]) data and Environmental Satellite (ENVISAT) Advanced SAR (ASAR) (C-band) data (24 scenes with VV and HH polarizations in Wide Swath [150 m]) during 2006-2009 covering 500 km of the Louisiana coastal zone. Mapping was primarily based on a decrease in backscatter between reference and target scenes, and as an extension of previous studies, the flood inundation mapping performance was assessed by the degree of correspondence between inundation mapping and inland water levels. Both PALSAR- and ASAR-based mapping at times were based on suboptimal reference scenes; however, ASAR performance seemed more sensitive to reference-scene quality and other types of scene variability. Related to water depth, PALSAR and ASAR mapping accuracies tended to be lower when water depths were shallow and increased as water levels decreased below or increased above the ground surface, but this pattern was more pronounced with ASAR. Overall, PALSAR-based inundation accuracies averaged 84% (n = 160), while ASAR-based mapping accuracies averaged 62% (n = 245).

Seasonal Phytoplankton Dynamics in the Eastern Tropical Atlantic

NASA Technical Reports Server (NTRS)

Monger, Bruce; McClain, Charles; Murtugudde, Ragu

1997-01-01

The coastal zone color scanner (CZCS) that operated aboard the Nimbus 7 satellite provided extensive coverage of phytoplankton pigment concentrations in the surface waters of the eastern tropical Atlantic (ETA) from March 1979 to February 1980 and coincided with four major research cruises to this region. Total primary production within the ETA (5 deg N-10 deg S, 25 deg W-10 deg E) was determined from CZCS pigment estimates and an empirical algorithm derived from concurrent in situ data taken along 4 deg W that relates near-surface chlorophyll concentration and integrated primary production. We estimated an average annual production for the ETA of 2.3 Gt C/yr with an associated 3.5-fold seasonal variation in the magnitude of this production. We describe the principal physical mechanisms controlling seasonal phytoplankton dynamics within the ETA and propose that in addition to seasonal change in the thermocline depth, one must also consider changes in the depth of the equatorial under current. An extensive validation effort indicates that the standard CZCS global products are a conservative estimate of pigment concentrations in ETA surface waters. Significant underestimates by the CZCS global products were observed in June and July which we attributed, in part, to aerosol correction errors and, more importantly, to errors caused by a significant reduction in the concentration of near-surface dissolved organic matter that resulted from strong equatorial upwelling.

Pinning and gas oversaturation imply stable single surface nanobubbles.

PubMed

Lohse, Detlef; Zhang, Xuehua

2015-03-01

Surface nanobubbles are experimentally known to survive for days at hydrophobic surfaces immersed in gas-oversaturated water. This is different from bulk nanobubbles, which are pressed out by the Laplace pressure against any gas oversaturation and dissolve in submilliseconds, as derived by Epstein and Plesset [J. Chem. Phys. 18, 1505 (1950)]. Pinning of the contact line has been speculated to be the reason for the stability of the surface nanobubbles. Building on an exact result by Popov [Phys. Rev. E 71, 036313 (2005)] on coffee stain evaporation, here we confirm this speculation by an exact calculation for single surface nanobubbles. It is based only on (i) the diffusion equation, (ii) Laplace pressure, and (iii) Henry's equation, i.e., fluid dynamical equations which are all known to be valid down to the nanometer scale. The crucial parameter is the gas oversaturation ζ of the liquid. At the stable equilibrium, the gas overpressures due to this oversaturation and the Laplace pressure balance. The theory predicts how the contact angle of the pinned bubble depends on ζ and the surface nanobubble's footprint lateral extension L. It also predicts an upper lateral extension threshold for stable surface nanobubbles to exist.

Laccase-Catalyzed Surface Modification of Thermo-Mechanical Pulp (TMP) for the Production of Wood Fiber Insulation Boards Using Industrial Process Water

PubMed Central

Schubert, Mark; Ruedin, Pascal; Civardi, Chiara; Richter, Michael; Hach, André; Christen, Herbert

2015-01-01

Low-density wood fiber insulation boards are traditionally manufactured in a wet process using a closed water circuit (process water). The water of these industrial processes contains natural phenolic extractives, aside from small amounts of admixtures (e.g., binders and paraffin). The suitability of two fungal laccases and one bacterial laccase was determined by biochemical characterization considering stability and substrate spectra. In a series of laboratory scale experiments, the selected commercial laccase from Myceliophtora thermophila was used to catalyze the surface modification of thermo-mechanical pulp (TMP) using process water. The laccase catalyzed the covalent binding of the phenolic compounds of the process water onto the wood fiber surface and led to change of the surface chemistry directly via crosslinking of lignin moieties. Although a complete substitution of the binder was not accomplished by laccase, the combined use of laccase and latex significantly improved the mechanical strength properties of wood fiber boards. The enzymatically-treated TMP showed better interactions with the synthetic binder, as shown by FTIR-analysis. Moreover, the enzyme is extensively stable in the process water and the approach requires no fresh water as well as no cost-intensive mediator. By applying a second-order polynomial model in combination with the genetic algorithm (GA), the required amount of laccase and synthetic latex could be optimized enabling the reduction of the binder by 40%. PMID:26046652

Effect of the submergence, the bed form geometry, and the speed of the surface water flow on the mitigation of pesticides in agricultural ditches

NASA Astrophysics Data System (ADS)

Boutron, Olivier; Margoum, Christelle; Chovelon, Jean-Marc; Guillemain, CéLine; Gouy, VéRonique

2011-08-01

Pesticides, which have been extensively used in agriculture, have become a major environmental issue, especially regarding surface and groundwater contamination. Of particular importance are vegetated farm drainage ditches, which can play an important role in the mitigation of pesticide contamination by adsorption onto ditch bed substrates. This role is, however, poorly understood, especially regarding the influence of hydrodynamic parameters, which make it difficult to promote best management practice of these systems. We have assessed the influence of three of these parameters (speed of the surface water flow, submergence, and geometrical characteristics of the bed forms) on the transfer and adsorption of selected pesticides (isoproturon, diuron, tebuconazole, and azoxystrobin) into the bed substrate by performing experiments with a tilted experimental flume, using hemp fibers as a standard of natural organic substrates that are found at the bottom of agricultural ditches. Results show the transfer of pesticides from surface water flow into bed substrate is favored, both regarding the amounts transferred into the bed substrate and the kinetics of the transfer, when the surface water speed and the submergence increase and when the bed forms are made of rectangular shapes. Extrapolation of flume data over a distance of several hundred meters suggests that an interesting possibility for improving the mitigation of pesticides in ditches would be to increase the submergence and to favor bed forms that tend to enhance perturbations and subsequent infiltration of the surface water flow.

Integrated assessment of groundwater - surface water exchange in the hillslope - riparian interface of a montane catchment

NASA Astrophysics Data System (ADS)

Scheliga, Bernhard; Tetzlaff, Doerthe; Nuetzmann, Gunnar; Soulsby, Chris

2016-04-01

Groundwater-surface water dynamics play an important role in runoff generation and the hydrologic connectivity between hillslopes and streams. Here, we present findings from a suite of integrated, empirical approaches to increase our understanding of groundwater-surface water interlinkages in a 3.2 km ^ 2 experimental catchment in the Scottish Highlands. The montane catchment is mainly underlain by granite and has extensive (70%) cover of glacial drift deposits which are up to 40 m deep and form the main aquifer in the catchment. Flat valley bottom areas fringe the stream channel and are characterised by peaty soils (0.5-4 m deep) which cover about 10% of the catchment and receive drainage from upslope areas. The transition between the hillslopes and riparian zone forms a critical interface for groundwater-surface water interactions that controls both the dynamics of riparian saturation and stream flow generation. We nested observations using wells to assess the groundwater - surface water transition, LiDAR surveys to explore the influence of micro-topography on shallow groundwater efflux and riparian wells to examine the magnitude and flux rates of deeper groundwater sources. We also used electrical resistivity surveys to assess the architecture and storage properties of drift aquifers. Finally, we used isotopic tracers to differentiate recharge sources and associated residence times as well as quantifying how groundwater dynamics affect stream flow. These new data have provided a novel conceptual framework for local groundwater - surface water exchange that is informing the development of new deterministic models for the site.

Coupling biophysical processes and water rights to simulate spatially distributed water use in an intensively managed hydrologic system

NASA Astrophysics Data System (ADS)

Han, Bangshuai; Benner, Shawn G.; Bolte, John P.; Vache, Kellie B.; Flores, Alejandro N.

2017-07-01

Humans have significantly altered the redistribution of water in intensively managed hydrologic systems, shifting the spatiotemporal patterns of surface water. Evaluating water availability requires integration of hydrologic processes and associated human influences. In this study, we summarize the development and evaluation of an extensible hydrologic model that explicitly integrates water rights to spatially distribute irrigation waters in a semi-arid agricultural region in the western US, using the Envision integrated modeling platform. The model captures both human and biophysical systems, particularly the diversion of water from the Boise River, which is the main water source that supports irrigated agriculture in this region. In agricultural areas, water demand is estimated as a function of crop type and local environmental conditions. Surface water to meet crop demand is diverted from the stream reaches, constrained by the amount of water available in the stream, the water-rights-appropriated amount, and the priority dates associated with particular places of use. Results, measured by flow rates at gaged stream and canal locations within the study area, suggest that the impacts of irrigation activities on the magnitude and timing of flows through this intensively managed system are well captured. The multi-year averaged diverted water from the Boise River matches observations well, reflecting the appropriation of water according to the water rights database. Because of the spatially explicit implementation of surface water diversion, the model can help diagnose places and times where water resources are likely insufficient to meet agricultural water demands, and inform future water management decisions.

Water availability and land subsidence in the Central Valley, California, USA

NASA Astrophysics Data System (ADS)

Faunt, Claudia C.; Sneed, Michelle; Traum, Jon; Brandt, Justin T.

2016-05-01

The Central Valley in California (USA) covers about 52,000 km2 and is one of the most productive agricultural regions in the world. This agriculture relies heavily on surface-water diversions and groundwater pumpage to meet irrigation water demand. Because the valley is semi-arid and surface-water availability varies substantially, agriculture relies heavily on local groundwater. In the southern two thirds of the valley, the San Joaquin Valley, historic and recent groundwater pumpage has caused significant and extensive drawdowns, aquifer-system compaction and subsidence. During recent drought periods (2007-2009 and 2012-present), groundwater pumping has increased owing to a combination of decreased surface-water availability and land-use changes. Declining groundwater levels, approaching or surpassing historical low levels, have caused accelerated and renewed compaction and subsidence that likely is mostly permanent. The subsidence has caused operational, maintenance, and construction-design problems for water-delivery and flood-control canals in the San Joaquin Valley. Planning for the effects of continued subsidence in the area is important for water agencies. As land use, managed aquifer recharge, and surface-water availability continue to vary, long-term groundwater-level and subsidence monitoring and modelling are critical to understanding the dynamics of historical and continued groundwater use resulting in additional water-level and groundwater storage declines, and associated subsidence. Modeling tools such as the Central Valley Hydrologic Model, can be used in the evaluation of management strategies to mitigate adverse impacts due to subsidence while also optimizing water availability. This knowledge will be critical for successful implementation of recent legislation aimed toward sustainable groundwater use.

Water availability and land subsidence in the Central Valley, California, USA

USGS Publications Warehouse

Faunt, Claudia; Sneed, Michelle; Traum, Jonathan A.; Brandt, Justin

2016-01-01

The Central Valley in California (USA) covers about 52,000 km2 and is one of the most productive agricultural regions in the world. This agriculture relies heavily on surface-water diversions and groundwater pumpage to meet irrigation water demand. Because the valley is semi-arid and surface-water availability varies substantially, agriculture relies heavily on local groundwater. In the southern two thirds of the valley, the San Joaquin Valley, historic and recent groundwater pumpage has caused significant and extensive drawdowns, aquifer-system compaction and subsidence. During recent drought periods (2007–2009 and 2012-present), groundwater pumping has increased owing to a combination of decreased surface-water availability and land-use changes. Declining groundwater levels, approaching or surpassing historical low levels, have caused accelerated and renewed compaction and subsidence that likely is mostly permanent. The subsidence has caused operational, maintenance, and construction-design problems for water-delivery and flood-control canals in the San Joaquin Valley. Planning for the effects of continued subsidence in the area is important for water agencies. As land use, managed aquifer recharge, and surface-water availability continue to vary, long-term groundwater-level and subsidence monitoring and modelling are critical to understanding the dynamics of historical and continued groundwater use resulting in additional water-level and groundwater storage declines, and associated subsidence. Modeling tools such as the Central Valley Hydrologic Model, can be used in the evaluation of management strategies to mitigate adverse impacts due to subsidence while also optimizing water availability. This knowledge will be critical for successful implementation of recent legislation aimed toward sustainable groundwater use.

Drought, Land-Use Change, and Water Availability in California's Central Valley

NASA Astrophysics Data System (ADS)

Faunt, C. C.; Sneed, M.; Traum, J.

2015-12-01

The Central Valley is a broad alluvial-filled structural trough that covers about 52,000 square kilometers and is one of the most productive agricultural regions in the world. Because the valley is semi-arid and the availability of surface water varies substantially from year to year, season to season, and from north to south, agriculture developed a reliance on groundwater for irrigation. During recent drought periods (2007-09 and 2012-present), groundwater pumping has increased due to a combination of factors including drought and land-use changes. In response, groundwater levels have declined to levels approaching or below historical low levels. In the San Joaquin Valley, the southern two thirds of the Central Valley, the extensive groundwater pumpage has caused aquifer system compaction, resulting in land subsidence and permanent loss of groundwater storage capacity. The magnitude and rate of subsidence varies based on geologic materials, consolidation history, and historical water levels. Spatially-variable subsidence has changed the land-surface slope, causing operational, maintenance, and construction-design problems for surface-water infrastructure. It is important for water agencies to plan for the effects of continued water-level declines, storage losses, and/or land subsidence. To combat these effects, excess surface water, when available, is artificially recharged. As surface-water availability, land use, and artificial recharge continue to vary, long-term groundwater-level and land-subsidence monitoring and modelling are critical to understanding the dynamics of the aquifer system. Modeling tools, such as the Central Valley Hydrologic Model, can be used in the analysis and evaluation of management strategies to mitigate adverse impacts due to subsidence, while also optimizing water availability. These analyses will be critical for successful implementation of recent legislation aimed toward sustainable groundwater use.

[Influence of the substrate composition in extensive green roof on the effluent quality].

PubMed

Chen, Yu-Lin; Li, Tian; Gu, Jun-Qing

2014-11-01

By monitoring the effluent quality from different green roof assemblies during several artificial rain events, the main pollutant characteristics and the influence of substrate composition in extensive green roof on the effluent quality were studied. Results showed that the main pollutants in the effluent were N, P and COD; with the increase of cumulative rain, the concentrations of pollutants in the effluent decreased, which had obvious leaching effect; The average concentrations of heavy metals in the early effluent from all assemblies reached drinking water standard, including the assemblies using crushed bricks; When garden soil and compost were used as organic matter, the assemblies had serious leaching of nutrient substance. After the accumulated rainfall reached 150 mm, the TN, TP and COD concentrations of effluent were 2.93, 0.73 and 78 mg x L(-1), respectively, which exceeded the Surface water V class limit. By means of application of the Water Treatment Residual, the leaching of TP from green planting soil was decreased by about 60%. The inorganic compound soil had better effluent quality, however we also need to judge whether the substrate could be applied in extensive green roof or not, by analyzing its ability of water quantity reduction and the plant growth situation.

Water resource use and management by the United States forest products industry.

PubMed

Wiegand, P S; Flinders, C A; Ice, G G; Malmberg, B J; Fisher, R P

2009-01-01

The connections between forest products operations and water resources in the United States is considered and, where possible, quantified. Manufacture of wood, pulp, and paper products and the influences of forest management and forest products manufacture on water quality are discussed. Most fresh water in the US originates in forested areas. Responsible harvesting strategies, best management practices, and forest re-growth combine to minimize or eliminate changes in water availability and degradation of water quality due to harvesting. Relative to alternative land uses and large-scale disturbance events, forested areas produce the highest quality of fresh water. Water inputs for the manufacture of forest products total about 5.8 billion m(3) per year, an amount equal about 0.4% of the surface and groundwater yield from timberland. Approximately 88% of water used in manufacturing is treated and returned directly to surface waters, about 11% is converted to water vapor and released during the manufacturing process, and 1% is imparted to products or solid residuals. Extensive study and continued monitoring of treated effluents suggest few or no concerns regarding the compatibility of current effluents with healthy aquatic systems.

Antifouling membranes for sustainable water purification: strategies and mechanisms.

PubMed

Zhang, Runnan; Liu, Yanan; He, Mingrui; Su, Yanlei; Zhao, Xueting; Elimelech, Menachem; Jiang, Zhongyi

2016-10-24

One of the greatest challenges to the sustainability of modern society is an inadequate supply of clean water. Due to its energy-saving and cost-effective features, membrane technology has become an indispensable platform technology for water purification, including seawater and brackish water desalination as well as municipal or industrial wastewater treatment. However, membrane fouling, which arises from the nonspecific interaction between membrane surface and foulants, significantly impedes the efficient application of membrane technology. Preparing antifouling membranes is a fundamental strategy to deal with pervasive fouling problems from a variety of foulants. In recent years, major advancements have been made in membrane preparation techniques and in elucidating the antifouling mechanisms of membrane processes, including ultrafiltration, nanofiltration, reverse osmosis and forward osmosis. This review will first introduce the major foulants and the principal mechanisms of membrane fouling, and then highlight the development, current status and future prospects of antifouling membranes, including antifouling strategies, preparation techniques and practical applications. In particular, the strategies and mechanisms for antifouling membranes, including passive fouling resistance and fouling release, active off-surface and on-surface strategies, will be proposed and discussed extensively.

2D instabilities of surface gravity waves on a linear shear current

NASA Astrophysics Data System (ADS)

Francius, Marc; Kharif, Christian

2016-04-01

Periodic 2D surface water waves propagating steadily on a rotational current have been studied by many authors (see [1] and references therein). Although the recent important theoretical developments have confirmed that periodic waves can exist over flows with arbitrary vorticity, their stability and their nonlinear evolution have not been much studied extensively so far. In fact, even in the rather simple case of uniform vorticity (linear shear), few papers have been published on the effect of a vertical shear current on the side-band instability of a uniform wave train over finite depth. In most of these studies [2-5], asymptotic expansions and multiple scales method have been used to obtain envelope evolution equations, which allow eventually to formulate a condition of (linear) instability to long modulational perturbations. It is noted here that this instability is often referred in the literature as the Benjamin-Feir or modulational instability. In the present study, we consider the linear stability of finite amplitude two-dimensional, periodic water waves propagating steadily on the free surface of a fluid with constant vorticity and finite depth. First, the steadily propagating surface waves are computed with steepness up to very close to the highest, using a Fourier series expansions and a collocation method, which constitutes a simple extension of Fenton's method [6] to the cases with a linear shear current. Then, the linear stability of these permanent waves to infinitesimal 2D perturbations is developed from the fully nonlinear equations in the framework of normal modes analysis. This linear stability analysis is an extension of [7] to the case of waves in the presence of a linear shear current and permits the determination of the dominant instability as a function of depth and vorticity for a given steepness. The numerical results are used to assess the accuracy of the vor-NLS equation derived in [5] for the characteristics of modulational instabilities due to resonant four-wave interactions, as well as to study the influence of vorticity and nonlinearity on the characteristics of linear instabilities due to resonant five-wave and six-wave interactions. Depending on the dimensionless depth, superharmonic instabilities due to five-wave interactions can become dominant with increasing positive vorticiy. Acknowledgments: This work was supported by the Direction Générale de l'Armement and funded by the ANR project n°. ANR-13-ASTR-0007. References [1] A. Constantin, Two-dimensionality of gravity water flows of constant non-zero vorticity beneath a surface wave train, Eur. J. Mech. B/Fluids, 2011, 30, 12-16. [2] R. S. Johnson, On the modulation of water waves on shear flows, Proc. Royal Soc. Lond. A., 1976, 347, 537-546. [3] M. Oikawa, K. Chow, D. J. Benney, The propagation of nonlinear wave packets in a shear flow with a free surface, Stud. Appl. Math., 1987, 76, 69-92. [4] A. I Baumstein, Modulation of gravity waves with shear in water, Stud. Appl. Math., 1998, 100, 365-90. [5] R. Thomas, C. Kharif, M. Manna, A nonlinear Schrödinger equation for water waves on finite depth with constant vorticity, Phys. Fluids, 2012, 24, 127102. [6] M. M Rienecker, J. D Fenton, A Fourier approximation method for steady water waves , J. Fluid Mech., 1981, 104, 119-137 [7] M. Francius, C. Kharif, Three-dimensional instabilities of periodic gravity waves in shallow water, J. Fluid Mech., 2006, 561, 417-437

TOXICOLOGICAL STUDIES IN TROPICAL ECOSYSTEMS: AN ECOTOXICOLOGICAL RISK ASSESSMENT OF PESTICIDE RUNOFF IN SOUTH FLORIDA ESTUARINE ECOSYSTEMS

EPA Science Inventory

A multi-year study in the C-111 canal and associated sites in Florida Bay was undertaken in order to determine the potential contaminant risk that exists in South Florida. After examining extensive surface water data, as well as sediment, tissue, and semi-permeable membrane devic...

Vibrational sum-frequency generation spectroscopy of ionic liquid 1-butyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate at the air-water interface

NASA Astrophysics Data System (ADS)

Saha, Ankur; SenGupta, Sumana; Kumar, Awadhesh; Choudhury, Sipra; Naik, Prakash D.

2016-08-01

The structure and orientation of room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate [PF3(C2F5)3], commonly known as [bmim][fap], have been investigated at the air-[bmim][fap] and air-water interfaces, employing vibrational sum-frequency generation (VSFG) spectroscopy. The VSFG spectra in the CH stretch region suggest presence of the [bmim] cation at the interfaces. Studies reveal that the butyl chain protrudes out into air, and the imidazolium ring lies almost planar to the interface. The CH stretch intensities get enhanced at the air-water interface, mainly because of polar orientation of imidazolium cation induced by interfacial water molecules. The OH stretch intensities are also enhanced at the air-water interface due to polar orientation of interfacial water molecules induced by [bmim][fap]. The Brewster angle microscopy suggests self aggregation of [bmim][fap] in the presence of water, and the aggregation becomes extensive showing dense surface domains with time. However, the surface pressure is almost unaffected due to aggregation.

National Water Quality Laboratory Profile

USGS Publications Warehouse

Raese, Jon W.

1994-01-01

The National Water Quality Laboratory determines organic and inorganic constituents in samples of surface and ground water, river and lake sediment, aquatic plant and animal material, and precipitation collected throughout the United States and its territories by the U.S. Geological Survey. In water year 1994, the Laboratory produced more than 900,000 analytical results for about 65,000 samples. The Laboratory also coordinates an extensive network of contract laboratories for the determination of radiochemical and stable isotopes and work for the U.S. Department of Defense Environmental Contamination Hydrology Program. Heightened concerns about water quality and about the possible effects of toxic chemicals at trace and ultratrace levels have contributed to an increased demand for impartial, objective, and independent data.

Southward spreading of the Fukushima-derived radiocesium across the Kuroshio Extension in the North Pacific

PubMed Central

Kumamoto, Yuichiro; Aoyama, Michio; Hamajima, Yasunori; Aono, Tatsuo; Kouketsu, Shinya; Murata, Akihiko; Kawano, Takeshi

2014-01-01

The accident of the Fukushima Dai-ichi nuclear power plant in March 2011 released a large amount of radiocesium into the North Pacific Ocean. Vertical distributions of Fukushima-derived radiocesium were measured at stations along the 149°E meridian in the western North Pacific during the winter of 2012. In the subtropical region, to the south of the Kuroshio Extension, we found a subsurface radiocesium maximum at a depth of about 300 m. It is concluded that atmospheric-deposited radiocesium south of the Kuroshio Extension just after the accident had been transported not only eastward along with surface currents but also southward due to formation/subduction of subtropical mode waters within about 10 months after the accident. The total amount of decay-corrected 134Cs in the mode water was an estimated about 6 PBq corresponding to 10–60% of the total inventory of Fukushima-derived 134Cs in the North Pacific Ocean. PMID:24589762

Nonlinear Solver Approaches for the Diffusive Wave Approximation to the Shallow Water Equations

NASA Astrophysics Data System (ADS)

Collier, N.; Knepley, M.

2015-12-01

The diffusive wave approximation to the shallow water equations (DSW) is a doubly-degenerate, nonlinear, parabolic partial differential equation used to model overland flows. Despite its challenges, the DSW equation has been extensively used to model the overland flow component of various integrated surface/subsurface models. The equation's complications become increasingly problematic when ponding occurs, a feature which becomes pervasive when solving on large domains with realistic terrain. In this talk I discuss the various forms and regularizations of the DSW equation and highlight their effect on the solvability of the nonlinear system. In addition to this analysis, I present results of a numerical study which tests the applicability of a class of composable nonlinear algebraic solvers recently added to the Portable, Extensible, Toolkit for Scientific Computation (PETSc).

Surface- and interface-engineered heterostructures for solar hydrogen generation

NASA Astrophysics Data System (ADS)

Chen, Xiangyan; Li, Yanrui; Shen, Shaohua

2018-04-01

Photoelectrochemical (PEC) water splitting based on semiconductor photoelectrodes provides a promising platform for reducing environmental pollution and solving the energy crisis by developing clean, sustainable and environmentally friendly hydrogen energy. In this context, metal oxides with their advantages including low cost, good chemical stability and environmental friendliness, have attracted extensive attention among the investigated candidates. However, the large bandgap, poor charge transfer ability and high charge recombination rate limit the PEC performance of metal oxides as photoelectrodes. To solve this limitation, many approaches toward enhanced PEC water splitting performance, which focus on surface and interface engineering, have been presented. In this topical review, we concentrate on the heterostructure design of some typical metal oxides with narrow bandgaps (e.g. Fe2O3, WO3, BiVO4 and Cu2O) as photoelectrodes. An overview of the surface- and interface-engineered heterostructures, including semiconductor heterojunctions, surface protection, surface passivation and cocatalyst decoration, will be given to introduce the recent advances in metal oxide heterostructures for PEC water splitting. This article aims to provide fundamental references and principles for designing metal oxide heterostructures with high activity and stability as photoelectrodes for PEC solar hydrogen generation.

Observation of water mass characteristics in the southwestern Mariana Trench

NASA Astrophysics Data System (ADS)

Xu, H.; Xie, Q.; Hong, B.

2016-12-01

The identification of large water mass characteristic can help oceanographer to better understand the oceanic circulation structures and other physical processes in open oceans. In current stage, the water mass characteristics were recognized well by extensive observation in the upper ocean, however, it was rarely studied in deep oceans, especially for deep trench with > 6000 m depth. In this study, we use observed data collected by CTDs during several surveys to investigate the water mass physical characteristic and transport in the world deepest trench, `Challenger Deep', in the southwestern Mariana Trench. The preliminary results show complex vertical structures of water mass in this trench. From surface to 4500 m, the water masses are occupied by typical tropical surface water, NPTUW, NPMW, NPIW and NPDW. Under 4500m, the water mass shows mixing characteristics of NPDW and AABW, which indicate AABW can be transported by form the deep ocean of the South Ocean to Northwestern Pacific and it can affect local water mass characteristics. The baroclinic geostrophic current calculated from the CTDs data shows the westerly transport of water mass can reach about 1.0 SV in the trench which is close to previous results.

Enhanced ion signals in desorption electrospray ionization using surfactant spray solutions.

PubMed

Badu-Tawiah, Abraham; Cooks, R Graham

2010-08-01

Solvent optimization is an important procedure in desorption electrospray ionization (DESI) and in this study the effects of solvent surface tension are explored. Data are presented for methanol/water/surfactant solvent systems, which show increases in ion signals of more than an order of magnitude when low concentrations of surfactants are added to the standard methanol/water (1:1) spray solvent. Examples of analytes tested include food chemicals, peptides, pharmaceuticals, and drugs of abuse. The improvement in ion intensity is mainly attributed to the effect of surface tension in producing smaller spray droplets, which are shown to cover a larger surface area. Surfactant-containing spray solutions allowed extension of DESI-MS analysis to previously intractable analytes like melamine and highly hydrophobic compounds like the sudan dyes. Copyright 2010 American Society for Mass Spectrometry. Published by Elsevier Inc. All rights reserved.

New surface-based observations of the environment beneath Pine Island Glacier ice shelf

NASA Astrophysics Data System (ADS)

Bindschadler, Robert; Truffer, Martin; Stanton, Tim; Peters, Leo; Shortt, Mike; Pomraning, Dale; Stockel, Jim; Shaw, Bill; Steinarson, Einar; Anandakrishnan, Sridhar; Wilson, Kiya; Holland, David; Bushuk, Mitch; Behar, Alberto; Cocaud, Cedric; Stam, Christina

2013-04-01

Extensive surface, sub-shelf cavity and seabed observations of the Pine Island Glacier (PIG) ice shelf environment were collected by a surface field team during the 2012-13 austral summer. Three sites aligned along a central, flow-aligned surface valley were occupied for about one week each during which two hot-water holes were drilled at each site. In one hole, a mast-mounted set of oceanographic sensors recorded water temperature, current and salinity in the few meters immediately below the ice-shelf bottom. In the other hole, a similarly instrumented profiler was deployed to make quasi-daily vertical transects of the sub-shelf cavity by rising and sinking along a cable suspended in the cavity. These instruments are already returning data that provide direct rates of heat and momentum transfer in the boundary layer, basal melt rates and the temporal variation of water movements on daily and longer time scales. Shallow cores of the sea bed and a photographic record of the drill holes, ocean cavity and sea bed were also collected at two of the drill sites. The geophysics program was spatially much broader and consisted of phase-sensitive radars to measure basal melt rates and active seismic instrumentation to explore the character of the sea bed. Continuous profiling between the drill sites established the previously discovered ("Autosub") sea bed ridge is asymmetric with a steeper downstream face. Spot measurements upstream of the drill sites were reached by helicopter and refined the shape of the ocean cavity where extensive melt rates were measured. The field work is concluding as this abstract is being submitted, so most results are not yet available, but will be included in the presentation as first results emerge.

Electrolytes in a nanometer slab-confinement: Ion-specific structure and solvation forces

NASA Astrophysics Data System (ADS)

Kalcher, Immanuel; Schulz, Julius C. F.; Dzubiella, Joachim

2010-10-01

We study the liquid structure and solvation forces of dense monovalent electrolytes (LiCl, NaCl, CsCl, and NaI) in a nanometer slab-confinement by explicit-water molecular dynamics (MD) simulations, implicit-water Monte Carlo (MC) simulations, and modified Poisson-Boltzmann (PB) theories. In order to consistently coarse-grain and to account for specific hydration effects in the implicit methods, realistic ion-ion and ion-surface pair potentials have been derived from infinite-dilution MD simulations. The electrolyte structure calculated from MC simulations is in good agreement with the corresponding MD simulations, thereby validating the coarse-graining approach. The agreement improves if a realistic, MD-derived dielectric constant is employed, which partially corrects for (water-mediated) many-body effects. Further analysis of the ionic structure and solvation pressure demonstrates that nonlocal extensions to PB (NPB) perform well for a wide parameter range when compared to MC simulations, whereas all local extensions mostly fail. A Barker-Henderson mapping of the ions onto a charged, asymmetric, and nonadditive binary hard-sphere mixture shows that the strength of structural correlations is strongly related to the magnitude and sign of the salt-specific nonadditivity. Furthermore, a grand canonical NPB analysis shows that the Donnan effect is dominated by steric correlations, whereas solvation forces and overcharging effects are mainly governed by ion-surface interactions. However, steric corrections to solvation forces are strongly repulsive for high concentrations and low surface charges, while overcharging can also be triggered by steric interactions in strongly correlated systems. Generally, we find that ion-surface and ion-ion correlations are strongly coupled and that coarse-grained methods should include both, the latter nonlocally and nonadditive (as given by our specific ionic diameters), when studying electrolytes in highly inhomogeneous situations.

Non-contact flow gauging for the extension and development of rating curves

NASA Astrophysics Data System (ADS)

Perks, Matthew; Large, Andy; Russell, Andy

2015-04-01

Accurate measurement of river discharge is fundamental to understanding hydrological processes, associated hazards and ecological responses within fluvial systems. Established protocols for determining river discharge are partial, predominantly invasive and logistically difficult during high flows. There is demand for new methods for accurate quantification of flow velocity under high-flow/flood conditions to in turn enable better post-event reconstruction of peak discharge. As a consequence considerable effort has been devoted to the development of innovative technologies for the representation of flow in open channels. Remotely operated fixed and mobile systems capable of providing quantitative estimates of instantaneous and time-averaged flow characteristics using non-contact methods has been a major development. Amongst the new approaches for stand-alone continuous monitoring of surface flows is Large Scale Particle Image Velocimetry (LSPIV). Here we adapt the LSPIV concept, to provide continuous discharge measurements in non-uniform channels with complex flow conditions. High Definition videos (1080p; 30fps) of the water surface are acquired at 5 minute intervals. The image is rectified to correct for perspective distortion using a new, open source tool which minimises errors resulting from oblique image capture. Naturally occurring artefacts on the water surface (e.g. bubbles, debris, etc.) are tracked with the Kanade-Lucas-Tomasi (KLT) algorithm. The data generated is in the form of a complex surface water velocity field which can be interrogated to extract a range of hydrological information such as the streamwise velocity at a cross-section of interest, or even allow the interrogation of hydrodynamic flow structures. Here we demonstrate that this approach is capable of generating river discharge data comparable to concurrent measurements made using existing, accepted technologies (e.g. ADCP). The outcome is better constraint and extension of rating curves. The approach is suited to water management authorities throughout Europe who seek ever-increasingly cost-effective and non-invasive techniques for maximising the monitoring capabilities of their operational network.

Modeling river discharge and sediment transport in the Wax Lake-Atchafalaya basin with remote sensing parametrization.

NASA Astrophysics Data System (ADS)

Simard, M.; Liu, K.; Denbina, M. W.; Jensen, D.; Rodriguez, E.; Liao, T. H.; Christensen, A.; Jones, C. E.; Twilley, R.; Lamb, M. P.; Thomas, N. A.

2017-12-01

Our goal is to estimate the fluxes of water and sediments throughout the Wax Lake-Atchafalaya basin. This was achieved by parametrization of a set of 1D (HEC-RAS) and 2D (DELFT3D) hydrology models with state of the art remote sensing measurements of water surface elevation, water surface slope and total suspended sediment (TSS) concentrations. The model implementations are spatially explicit, simulating river currents, lateral flows to distributaries and marshes, and spatial variations of sediment concentrations. Three remote sensing instruments were flown simultaneously to collect data over the Wax Lake-Atchafalaya basin, and along with in situ field data. A Riegl Lidar was used to measure water surface elevation and slope, while the UAVSAR L-band radar collected data in repeat-pass interferometric mode to measure water level change within adjacent marshes and islands. These data were collected several times as the tide rose and fell. AVRIS-NG instruments measured water surface reflectance spectra, used to estimate TSS. Bathymetry was obtained from sonar transects and water level changes were recorded by 19 water level pressure transducers. We used several Acoustic Doppler Current Profiler (ADCP) transects to estimate river discharge. The remotely sensed measurements of water surface slope were small ( 1cm/km) and varied slightly along the channel, especially at the confluence with bayous and the intra-coastal waterway. The slope also underwent significant changes during the tidal cycle. Lateral fluxes to island marshes were mainly observed by UAVSAR close to the distributaries. The extensive remote sensing measurements showed significant disparity with the hydrology model outputs. Observed variations in water surface slopes were unmatched by the model and tidal wave propagation was much faster than gauge measurements. The slope variations were compensated for in the models by tuning local lateral fluxes, bathymetry and riverbed friction. Overall, the simpler 1D model could best simulate observed tidal wave propagation and water surface slope. The complexity of the 2D model requires further quantification of parameter sensitivity and improvement of the parametrization routine.

Floatable, Self-Cleaning, and Carbon-Black-Based Superhydrophobic Gauze for the Solar Evaporation Enhancement at the Air-Water Interface.

PubMed

Liu, Yiming; Chen, Jingwei; Guo, Dawei; Cao, Moyuan; Jiang, Lei

2015-06-24

Efficient solar evaporation plays an indispensable role in nature as well as the industry process. However, the traditional evaporation process depends on the total temperature increase of bulk water. Recently, localized heating at the air-water interface has been demonstrated as a potential strategy for the improvement of solar evaporation. Here, we show that the carbon-black-based superhydrophobic gauze was able to float on the surface of water and selectively heat the surface water under irradiation, resulting in an enhanced evaporation rate. The fabrication process of the superhydrophobic black gauze was low-cost, scalable, and easy-to-prepare. Control experiments were conducted under different light intensities, and the results proved that the floating black gauze achieved an evaporation rate 2-3 times higher than that of the traditional process. A higher temperature of the surface water was observed in the floating gauze group, revealing a main reason for the evaporation enhancement. Furthermore, the self-cleaning ability of the superhydrophobic black gauze enabled a convenient recycling and reusing process toward practical application. The present material may open a new avenue for application of the superhydrophobic substrate and meet extensive requirements in the fields related to solar evaporation.

Fatigue Crack Propagation from Notched Specimens of 304 SS in elevated Temperature Aqueous Environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wire, G. L.; Mills, W. J.

2002-08-01

Fatigue crack propagation (FCP) rates for 304 stainless steel (304SS) were determined in 24 degree C and 288 degree C air and 288 degree C water using double-edged notch (DEN) specimens of 304 stainless steel (304 SS). Test performed at matched loading conditions in air and water at 288 degree C with 20-6- cc h[sub]2/kg h[sub]2O provided a direct comparison of the relative crack growth rates in air and water over a wide range of crack growth rates. The DEN crack extension ranged from short cracks (0.03-0.25 mm) to long cracks up to 4.06 mm, which are consistent with conventionalmore » deep crack tests. Crack growth rates of 304 SS in water were about 12 times the air rate. This 12X environmental enhancement persisted to crack extensions up to 4.06 mm, far outside the range associated with short crack effects. The large environmental degradation for 304 SS crack growth is consistent with the strong reduction of fatigue life in high hydrogen water. Further, very similar environmental effects w ere reported in fatigue crack growth tests in hydrogen water chemistry (HWC). Most literature data in high hydrogen water show only a mild environmental effect for 304 SS, of order 2.5 times air or less, but the tests were predominantly performed at high cyclic stress intensity or equivalently, high air rates. The environmental effect in low oxygen environments at low stress intensity depends strongly on both the stress ratio, R, and the load rise time, T[sub]r, as recently reported for austenitic stainless steel in BWR water. Fractography was performed for both tests in air and water. At 288 degree C in water, the fracture surfaces were crisply faceted with a crystallographic appearance, and showed striations under high magnification. The cleavage-like facets on the fracture surfaces suggest that hydrogen embrittlement is the primary cause of accelerated cracking.« less

Fluvial sediment study of Fishtrap and Dewey Lakes drainage basins, Kentucky - Virginia

USGS Publications Warehouse

Curtis, William F.; Flint, Russell F.; George, Frederick H.; Santos, John F.

1978-01-01

Fourteen drainage basins above Fishtrap and Dewey Lakes in the Levisa Fork and Johns Creek drainage basins of eastern Kentucky and southwestern Virginia were studied to determine sedimentation rates and origin of sediment entering the two lakes. The basins ranged in size from 1.68 to 297 square miles. Sediment yields ranged from 2,890 to 21,000 tons per square mile where surface-mining techniques predominated, and from 732 to 3 ,470 tons per square mile where underground mining methods predominated. Yields, in terms of tons per acre-foot of runoff, ranged from 2.2 to 15 for surface-mined areas, and from 0.5 to 2.7 for underground-mined areas. Water and sediment discharges from direct runoff during storms were compared for selected surface-mined and underground-mined areas. Data points of two extensively surface-mined areas, one from the current project and one from a previous project in Beaver Creek basin, McCreary County, Kentucky, grouped similarly in magnitude and by season. Disturbed areas from mining activities determined from aerial photographs reached 17 percent in one study area where extensive surface mining was being practiced. For most areas where underground mining was practiced, percentage disturbed area was almost negligible. Trap efficiency of Fishtrap Lake was 89 percent, and was 62 percent for Dewey Lake. Average annual deposition rates were 464 and 146 acre-feet for Fishtrap and Dewey Lakes, respectively. The chemical quality of water in the Levisa Fork basin has been altered by man 's activities. (Woodard-USGS)

Addressing the Sustainability of Groundwater Extraction in California Using Hydrochronology

NASA Astrophysics Data System (ADS)

Moran, J. E.; Visser, A.; Singleton, M. J.; Esser, B. K.

2017-12-01

In urban and agricultural settings in California, intense pressure on water supplies has led to extensive managed aquifer recharge and extensive overdraft in these areas, respectively. The California Sustainable Groundwater Management Act (SGMA) includes criteria for pumping that maintains groundwater levels and basin storage, and avoids stream depletion and degradation of water quality. Most sustainability plans will likely use water level monitoring and water budget balancing based on integrated flow models as evidence of compliance. However, hydrochronology data are applicable to several of the criteria, and provide an independent method of addressing questions related to basin turnover time, recharge rate, surface water-groundwater interaction, and the age distribution at pumping wells. We have applied hydrochronology (mainly tritium-helium groundwater age dating and extrinsic tracers) in urban areas to delineate flowpaths of artificially recharged water, to identify stagnant zones bypassed by the engineered flow system, and to predict vulnerability of drinking water sources to contamination. In agricultural areas, we have applied multi-tracer hydrochronology to delineate groundwater stratigraphy, to identify paleowater, and to project future nitrate concentrations in long-screened wells. This presentation will describe examples in which groundwater dating and other tracer methods can be applied to directly address the SGMA criteria for sustainable groundwater pumping.

Toward chemical accuracy in the description of ion-water interactions through many-body representations. Alkali-water dimer potential energy surfaces

NASA Astrophysics Data System (ADS)

Riera, Marc; Mardirossian, Narbe; Bajaj, Pushp; Götz, Andreas W.; Paesani, Francesco

2017-10-01

This study presents the extension of the MB-nrg (Many-Body energy) theoretical/computational framework of transferable potential energy functions (PEFs) for molecular simulations of alkali metal ion-water systems. The MB-nrg PEFs are built upon the many-body expansion of the total energy and include the explicit treatment of one-body, two-body, and three-body interactions, with all higher-order contributions described by classical induction. This study focuses on the MB-nrg two-body terms describing the full-dimensional potential energy surfaces of the M+(H2O) dimers, where M+ = Li+, Na+, K+, Rb+, and Cs+. The MB-nrg PEFs are derived entirely from "first principles" calculations carried out at the explicitly correlated coupled-cluster level including single, double, and perturbative triple excitations [CCSD(T)-F12b] for Li+ and Na+ and at the CCSD(T) level for K+, Rb+, and Cs+. The accuracy of the MB-nrg PEFs is systematically assessed through an extensive analysis of interaction energies, structures, and harmonic frequencies for all five M+(H2O) dimers. In all cases, the MB-nrg PEFs are shown to be superior to both polarizable force fields and ab initio models based on density functional theory. As previously demonstrated for halide-water dimers, the MB-nrg PEFs achieve higher accuracy by correctly describing short-range quantum-mechanical effects associated with electron density overlap as well as long-range electrostatic many-body interactions.

The stable isotopes of site wide waters at an oil sands mine in northern Alberta, Canada

NASA Astrophysics Data System (ADS)

Baer, Thomas; Barbour, S. Lee; Gibson, John J.

2016-10-01

Oil sands mines have large disturbance footprints and contain a range of new landforms constructed from mine waste such as shale overburden and the byproducts of bitumen extraction such as sand and fluid fine tailings. Each of these landforms are a potential source of water and chemical release to adjacent surface and groundwater, and consequently, the development of methods to track water migration through these landforms is of importance. The stable isotopes of water (i.e. 2H and 18O) have been widely used in hydrology and hydrogeology to characterize surface water/groundwater interactions but have not been extensively applied in mining applications, or specifically to oil sands mining in northern Alberta. A prerequisite for applying these techniques is the establishment of a Local Meteoric Water Line (LMWL) to characterize precipitation at the mine sites as well as the development of a 'catalogue' of the stable water isotope signatures of various mine site waters. This study was undertaken at the Mildred Lake Mine Site, owned and operated by Syncrude Canada Ltd. The LMWL developed from 2 years (2009/2012) of sample collection is shown to be consistent with other LMWLs in western Canada. The results of the study highlight the unique stable water isotope signatures associated with hydraulically placed tailings (sand or fluid fine tailings) and overburden shale dumps relative to natural surface water and groundwater. The signature associated with the snow melt water on reclaimed landscapes was found to be similar to ground water recharge in the region. The isotopic composition of the shale overburden deposits are also distinct and consistent with observations made by other researchers in western Canada on undisturbed shales. The process water associated with the fine and coarse tailings streams has highly enriched 2H and 18O signatures. These signatures are developed through the non-equilibrium fractionation of imported fresh river water during evaporation from cooling towers used within the raw water process circuit. This highly fractionated surface water eventually becomes part of the recycled tailings water circuit, and as a consequence it undergoes further non-equilibrium fractionation as a result of surface evaporation, leading to additional enrichment along local evaporation lines.

Evaluating Impacts of Land Use/Land Cover Change on Water Resources in Semiarid Regions

NASA Astrophysics Data System (ADS)

Scanlon, B. R.; Faunt, C. C.; Pool, D. R.; Reedy, R. C.

2017-12-01

Land use/land cover (LU/LC) changes play an integral role in water resources by controlling the partitioning of water at the land surface. Here we evaluate impacts of changing LU/LC on water resources in response to climate variation and change and land use change related to agriculture using data from semiarid regions in the southwestern U.S. Land cover changes in response to climate can amplify or dampen climate impacts on water resources. Changes from wet Pleistocene to much drier Holocene climate resulted in expansion of perennial vegetation, amplifying climate change impacts on water resources by reducing groundwater recharge as shown in soil profiles in the southwestern U.S.. In contrast, vegetation response to climate extremes, including droughts and floods, dampen impacts of these extremes on water resources, as shown by water budget monitoring in the Mojave Desert. Agriculture often involves changes from native perennial vegetation to annual crops increasing groundwater recharge in many semiarid regions. Irrigation based on conjunctive use of surface water and groundwater increases water resource availability, as shown in the Central Valley of California and in southern Arizona. Surface water irrigation in these regions is enhanced by water transported from more humid settings through extensive pipelines. These projects have reversed long-term declining groundwater trends in some regions. While irrigation design has often focused on increased efficiency, "more crop per drop", optimal water resource management may benefit more from inefficient (e.g. flood irrigation) surface-water irrigation combined with efficient (e.g. subsurface drip) irrigation to maximize groundwater recharge, as seen in parts of the Central Valley. Flood irrigation of perennial crops, such as almonds and vineyards, during winter is being considered in the Central Valley to enhance groundwater recharge. Managed aquifer recharge can be considered a special case of conjunctive use of surface water and groundwater use where spreading basins focus recharge in southern California and Arizona. This overview highlights the importance of changes in LU/LC in controlling water budgets in semiarid regions. Understanding these controls should allow us to better manage water resources.

Water resources of the Marquette Iron Range area, Michigan

USGS Publications Warehouse

Wiitala, Sulo Werner; Newport, Thomas Gwyn; Skinner, Earl L.

1967-01-01

Large quantities of water are needed in the beneficiation and pelletizing processes by which the ore mined from low-grade iron-formations is upgraded into an excellent raw material for the iron and steel industry. Extensive reserves of low-grade iron-formation available for development herald an intensification of the demands upon the area's water supplies. This study was designed to provide water facts for public and private agencies in planning orderly development and in guiding the management of the water resources to meet existing and new requirements. Inland lakes and streams are the best potential sources of water for immediate development. The natural flow available for 90 percent of the time in the Middle and East Branches of the Escanaba River, the Carp River, and the Michigamme River is about 190 cubic feet per second. Potential storage sites are identified, and their complete development could increase the available supply from the above streams to about 450 cubic feet per second. Outwash deposits are the best potential sources of ground water. Large supplies could be developed from extensive outwash deposits in the eastern part of the area adjacent to Goose Lake Outlet and the East Branch Escanaba River. Other areas of outwash occur in the vicinity of Humboldt, West Branch Creek, and along the stream valleys. Streamflow data were used to make rough approximations of the ground-water potential in some areas. In general, however, the available data were not sufficient to permit quantitative evaluation of the potential ground-water supplies. Chemical quality of the surface and ground waters of the area is generally acceptable for most uses. Suspended sediment in the form of mineral tailings in effluents from ore-processing plants is a potential problem. Existing plants use settling basins to effectively remove most of the suspended material. Available records indicate that suspended-sediment concentrations and loads in the receiving waters have not been significantly increased by these operations. Present water use is about 60 cubic feet per second in the area. Thus, available water supplies are believed to be adequate for existing and foreseeable new uses. Water management, rather than water availability, is of prime consideration in this area. Time distribution of available water supplies, distribution of water to points of use, effect of surface-water development upon ground water and vice versa, and possible conflicts with competing uses are some of the management problems that are discussed. The presence of many inland lakes, favorable storage sites on streams, and several promising acquifers provide flexibility in possible water-management operations. A discussion of the interrelationships between surface and ground water and a ground-water budget are presented to render a better understanding of the hydrologic system with which water management will be concerned.

The Role of Water in Mediating Interfacial Adhesion and Shear Strength in Graphene Oxide.

PubMed

Soler-Crespo, Rafael A; Gao, Wei; Mao, Lily; Nguyen, Hoang T; Roenbeck, Michael R; Paci, Jeffrey T; Huang, Jiaxing; Nguyen, SonBinh T; Espinosa, Horacio D

2018-06-12

Graphene oxide (GO), whose highly tunable surface chemistry enables the formation of strong interfacial hydrogen-bond networks, has garnered increasing interest in the design of devices that operate in the presence of water. For instance, previous studies have suggested that controlling GO's surface chemistry leads to enhancements in interfacial shear strength, allowing engineers to manage deformation pathways and control failure mechanisms. However, these previous reports have not explored the role of ambient humidity and only offer extensive chemical modifications to GO's surface as the main pathway to control GO's interfacial properties. Herein, through atomic force microscopy experiments on GO-GO interfaces, the adhesion energy and interfacial shear strength of GO were measured as a function of ambient humidity. Experimental evidence shows that adhesion energy and interfacial shear strength can be improved by a factor of 2-3 when GO is exposed to moderate (∼30% water weight) water content. Furthermore, complementary molecular dynamics simulations uncovered the mechanisms by which these nanomaterial interfaces achieve their properties. They reveal that the strengthening mechanism arises from the formation of strongly interacting hydrogen-bond networks, driven by the chemistry of the GO basal plane and intercalated water molecules between two GO surfaces. In summary, the methodology and findings here reported provide pathways to simultaneously optimize GO's interfacial and in-plane mechanical properties, by tailoring the chemistry of GO and accounting for water content, in engineering applications such as sensors, filtration membranes, wearable electronics, and structural materials.

Impact of Water Withdrawals from Groundwater and Surface Water on Continental Water Storage Variations

NASA Technical Reports Server (NTRS)

Doell, Petra; Hoffmann-Dobrev, Heike; Portmann, Felix T.; Siebert, Stefan; Eicker, Annette; Rodell, Matthew; Strassberg, Gil

2011-01-01

Humans have strongly impacted the global water cycle, not only water flows but also water storage. We have performed a first global-scale analysis of the impact of water withdrawals on water storage variations, using the global water resources and use model WaterGAP. This required estimation of fractions of total water withdrawals from groundwater, considering five water use sectors. According to our assessment, the source of 35% of the water withdrawn worldwide (4300 cubic km/yr during 1998-2002) is groundwater. Groundwater contributes 42%, 36% and 27% of water used for irrigation, households and manufacturing, respectively, while we assume that only surface water is used for livestock and for cooling of thermal power plants. Consumptive water use was 1400 cubic km/yr during 1998-2002. It is the sum of the net abstraction of 250 cubic km/yr of groundwater (taking into account evapotranspiration and return flows of withdrawn surface water and groundwater) and the net abstraction of 1150 km3/yr of surface water. Computed net abstractions indicate, for the first time at the global scale, where and when human water withdrawals decrease or increase groundwater or surface water storage. In regions with extensive surface water irrigation, such as Southern China, net abstractions from groundwater are negative, i.e. groundwater is recharged by irrigation. The opposite is true for areas dominated by groundwater irrigation, such as in the High Plains aquifer of the central USA, where net abstraction of surface water is negative because return flow of withdrawn groundwater recharges the surface water compartments. In intensively irrigated areas, the amplitude of seasonal total water storage variations is generally increased due to human water use; however, in some areas, it is decreased. For the High Plains aquifer and the whole Mississippi basin, modeled groundwater and total water storage variations were compared with estimates of groundwater storage variations based on groundwater table observations, and with estimates of total water storage variations from the GRACE satellites mission. Due to the difficulty in estimating area-averaged seasonal groundwater storage variations from point observations of groundwater levels, it is uncertain whether WaterGAP underestimates actual variations or not. We conclude that WaterGAP possibly overestimates water withdrawals in the High Plains aquifer where impact of human water use on water storage is readily discernible based on WaterGAP calculations and groundwater observations. No final conclusion can be drawn regarding the possibility of monitoring water withdrawals in the High Plains aquifer using GRACE. For the less intensively irrigated Mississippi basin, observed and modeled seasonal groundwater storage reveals a discernible impact of water withdrawals in the basin, but this is not the case for total water storage such that water withdrawals at the scale of the whole Mississippi basin cannot be monitored by GRACE.

DROPWISE CONDENSATION ON MICRO- AND NANOSTRUCTURED SURFACES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Enright, R; Miljkovic, N; Alvarado, JL

In this review we cover recent developments in the area of surface-enhanced dropwise condensation against the background of earlier work. The development of fabrication techniques to create surface structures at the micro-and nanoscale using both bottom-up and top-down approaches has led to increased study of complex interfacial phenomena. In the heat transfer community, researchers have been extensively exploring the use of advanced surface structuring techniques to enhance phase-change heat transfer processes. In particular, the field of vapor-to-liquid condensation and especially that of water condensation has experienced a renaissance due to the promise of further optimizing this process at the micro-andmore » nanoscale by exploiting advances in surface engineering developed over the last several decades.« less

Earth Observation

NASA Image and Video Library

2013-06-24

ISS036-E-011843 (24 June 2013) --- Gravity waves and sunglint on Lake Superior are featured in this image photographed by an Expedition 36 crew member on the International Space Station. From the vantage point of the space station, crew members frequently observe Earth atmospheric and surface phenomena in ways impossible to view from the ground. Two such phenomena?gravity waves and sunglint?are illustrated in this photograph of northeastern Lake Superior. The Canadian Shield of southern Ontario (bottom) is covered with extensive green forest canopy typical of early summer. Offshore, and to the west and southwest of Pukaskwa National Park several distinct sets of parallel cloud bands are visible. Gravity waves are produced when moisture-laden air encounters imbalances in air density, such as might be expected when cool air flows over warmer air; this can cause the flowing air to oscillate up and down as it moves, causing clouds to condense as the air rises (cools) and evaporate away as the air sinks (warms). This produces parallel bands of clouds oriented perpendicular to the wind direction. The orientation of the cloud bands visible in this image, parallel to the coastlines, suggests that air flowing off of the land surfaces to the north is interacting with moist, stable air over the lake surface, creating gravity waves. The second phenomenon?sunglint?effects the water surface around and to the northeast of Isle Royale (upper right). Sunglint is caused by light reflection off a water surface; some of the reflected light travels directly back towards the observer, resulting in a bright mirror-like appearance over large expanses of water. Water currents and changes in surface tension (typically caused by presence of oils or surfactants) alter the reflective properties of the water, and can be highlighted by sunglint. For example, surface water currents are visible to the east of Isle Royale that are oriented similarly to the gravity waves ? suggesting that they too are the product of winds moving off of the land surface.

Impact of green roofs on stormwater quality in a South Australian urban environment.

PubMed

Razzaghmanesh, M; Beecham, S; Kazemi, F

2014-02-01

Green roofs are an increasingly important component of water sensitive urban design systems and can potentially improve the quality of urban runoff. However, there is evidence that they can occasionally act as a source rather than a sink for pollutants. In this study, the water quality of the outflow from both intensive and extensive green roof systems were studied in the city of Adelaide, South Australia over a period of nine months. The aim was to examine the effects of different green roof configurations on stormwater quality and to compare this with runoff from aluminium and asphalt roofs as control surfaces. The contaminant concentrations in runoff from both intensive and extensive green roofs generally decreased during the study period. A comparison between the two types of green roof showed that except for some events for EC, TDS and chloride, the values of the parameters such as pH, turbidity, nitrate, phosphate and potassium in intensive green roof outflows were higher than in the outflows from the extensive green roofs. These concentrations were compared to local, state, national and international water quality guidelines in order to investigate the potential for outflow runoff from green roofs to be reused for potable and non-potable purposes. The study found that green roof outflow can provide an alternative water source for non-potable purposes such as urban landscape irrigation and toilet flushing. © 2013.

Salinity minima, water masses and surface circulation in the Eastern Tropical Pacific off Mexico and surrounding areas

NASA Astrophysics Data System (ADS)

Portela, Esther; Beier, Emilio; Godínez, Victor; Castro, Rubén; Desmond Barton, Eric

2016-04-01

The seasonal variations of the water masses and their interactions are analyzed in the Tropical Pacific off Mexico (TPOM) and four contiguous areas of on the basis of new extensive hydrographic database. The regional water masses intervals are redefined in terms of Absolute Salinity (SA) in g kg-1 and Conservative Temperature (Θ) according to TEOS - 10. The California Current System Water (CCSW) mass is introduced as an improved description of the former California Current Water (CCW) together with the Subarctic Water (SAW) to describe better the characteristics of the components of the California Current System. Hydrographic data, Precipitation-Evaporation balance and geostrophic currents were used to investigate the origin and seasonality of two salinity minima in the area. The shallow salinity minimum of around 33.5 g kg-1 originated in the California Current System and became saltier but less dense water as it traveled to the southeast. It can be identified as a mixture of CCSW and tropical waters. The surface salinity minimum of 32 - 33 g kg-1 was seen as a sharp surface feature in the TPOM from August to November. It was produced by the arrival of tropical waters from the south in combination with the net precipitation in the area during these months. This result provides new evidence of the presence of the poleward-flowing Mexican Coastal Current and, for the first time, of its seasonal pattern of variation.

The Doe Water Cycle Pilot Study.

NASA Astrophysics Data System (ADS)

Miller, N. L.; King, A. W.; Miller, M. A.; Springer, E. P.; Wesely, M. L.; Bashford, K. E.; Conrad, M. E.; Costigan, K.; Foster, P. N.; Gibbs, H. K.; Jin, J.; Klazura, J.; Lesht, B. M.; Machavaram, M. V.; Pan, F.; Song, J.; Troyan, D.; Washington-Allen, R. A.

2005-03-01

A Department of Energy (DOE) multilaboratory Water Cycle Pilot Study (WCPS) investigated components of the local water budget at the Walnut River watershed in Kansas to study the relative importance of various processes and to determine the feasibility of observational water budget closure. An extensive database of local meteorological time series and land surface characteristics was compiled. Numerical simulations of water budget components were generated and, to the extent possible, validated for three nested domains within the Southern Great Plains-the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Cloud Atmospheric Radiation Testbed (CART), the Walnut River watershed (WRW), and the Whitewater watershed (WW), in Kansas.A 2-month intensive observation period (IOP) was conducted to gather extensive observations relevant to specific details of the water budget, including finescale precipitation, streamflow, and soil moisture measurements that were not made routinely by other programs. Event and seasonal water isotope (d18O, dD) sampling in rainwater, streams, soils, lakes, and wells provided a means of tracing sources and sinks within and external to the WW, WRW, and the ARM CART domains. The WCPS measured changes in the leaf area index for several vegetation types, deep groundwater variations at two wells, and meteorological variables at a number of sites in the WRW. Additional activities of the WCPS include code development toward a regional climate model that includes water isotope processes, soil moisture transect measurements, and water-level measurements in groundwater wells.

Potentiometric Surface of the Aquia Aquifer in Southern Maryland, September 2001

USGS Publications Warehouse

Curtin, Stephen E.; Andreasen, David C.; Wheeler, Judith C.

2002-01-01

This report presents a map showing the potentiometric surface of the Aquia aquifer in the Aquia Formation of Paleocene age in Southern Maryland during September 2001. The map is based on water-level measurements in 76 wells. The potentiometric surface was highest at 40 feet above sea level near the northern boundary and outcrop area of the aquifer in the central part of Anne Arundel County, and was below sea level in the remainder of the study area. The hydraulic gradient was directed southeastward toward an extensive cone of depression around well fields at Lexington Park and Solomons Island. A cone of depression formed in northern Calvert County due to pumpage at Chesapeake Beach and North Beach. The water level has declined to 44 feet below sea level in this area. The lowest measurement was 160 feet below sea level at the center of a cone of depression at Lexington Park.

Hydrogeology of eastern Michaud Flats, Fort Hall Indian Reservation, Idaho

USGS Publications Warehouse

Jacobson, N.D.

1984-01-01

Groundwater in Michaud Flats, southeastern Idaho, is developed extensively for irrigation and industry. Extensive clay beds overlie the Bighole Basalt and Sunbeam Formation, which yield most of the water for irrigation and industrial wells; artesian aquifers in these rock units have heads below land surface and near those in the shallow water-table aquifer in the overlying Michaud Gravel. Transmissivities in artesian aquifers range from 19,6000 to 444,000 feet squared per day. High levels of arsenic were detected in groundwater in the Flats in 1972. During 1982, concentrations of arsenic twice exceeded the recommended drinking water limit of 50 micrograms per liter. Concentrations of other chemical constituents were generally within drinking water limits. Stable-isotope data suggest more than one source of aquifer recharge and indicate some mixing between waters from industrial ponds and local groundwater. Management alternatives are being implemented by two industries for control of groundwater contamination. These include reduction of effluent, installation of liners and leachate recovery systems in ponds, and removal and reclamation of precipitates in old slurry and evaporation ponds. Six sites will be monitored through 1985 to determine changes in groundwater chemistry and migration of contaminants. (USGS)

Surface water geochemical and isotopic variations in an area of accelerating Marcellus Shale gas development.

PubMed

Pelak, Adam J; Sharma, Shikha

2014-12-01

Water samples were collected from 50 streams in an area of accelerating shale gas development in the eastern U.S.A. The geochemical/isotopic characteristics show no correlation with the five categories of Marcellus Shale production. The sub-watersheds with the greatest density of Marcellus Shale development have also undergone extensive coal mining. Hence, geochemical/isotopic compositions were used to understand sources of salinity and effects of coal mining and shale gas development in the area. The data indicates that while some streams appear to be impacted by mine drainage; none appear to have received sustained contribution from deep brines or produced waters associated with shale gas production. However, it is important to note that our interpretations are based on one time synoptic base flow sampling of a few sampling stations and hence do account potential intermittent changes in chemistry that may result from major/minor spills or specific mine discharges on the surface water chemistry. Copyright © 2014 Elsevier Ltd. All rights reserved.

Hydrology of area 50, Northern Great Plains and Rocky Mountain coal provinces, Wyoming and Montana

USGS Publications Warehouse

Lowry, Marlin E.; Wilson, James F.; ,

1983-01-01

This report is one of a series designed to characterize the hydrology of drainage basins within coal provinces, nationwide. Area 50 includes all of the Powder River Basin, Wyoming and Montana and the upstream parts of the Cheyenne and Belle Fourche River Basins - a total of 20,676 sq mi. The area has abundant coal (81.2 million tons mined in 1982), but scarce water. The information in the report is intended to describe the hydrology of the ' general area ' of any proposed mine. The report represents a summary of results of the water resources investigations of the U.S. Geological Survey, carried out in cooperation with State and other Federal agencies. Each of more than 50 topics is discussed in a brief text that is accompanied by maps, graphs, and other illustrations. Primary topics in the report are: physiography, economic development, surface-water data networks, surface water quantity and quality, and groundwater. The report also contains an extensive description of sources of additional information. (USGS)

Potentiometric Surface of the Aquia Aquifer in Southern Maryland, September 2002

USGS Publications Warehouse

Curtin, Stephen E.; Andreasen, David C.; Wheeler, Judith C.

2003-01-01

This report presents a map showing the potentiometric surface of the Aquia aquifer in the Aquia Formation of Paleocene age in Southern Maryland during September 2002. The map is based on water-level measurements in 94 wells. The highest measured water level was 38 feet above sea level near the northern boundary and outcrop area of the aquifer in the central part of Anne Arundel County, and was below sea level just south of this area and in the remainder of the study area. The hydraulic gradient increased southeastward toward an extensive cone of depression around well fields at Lexington Park and Solomons Island. Another cone of depression occurred in northern Calvert County due to pumpage at and near Chesapeake Beach and North Beach. The water level measured in this area has declined to 55 feet below sea level. The lowest water level measured was 169 feet below sea level at the center of a cone of depression at Lexington Park.

Potentiometric surface of the Aquia Aquifer in southern Maryland, September 2003

USGS Publications Warehouse

Curtin, Stephen E.; Andreason, David C.; Wheeler, Judith C.

2005-01-01

This report presents a map showing the potentiometric surface of the Aquia aquifer in the Aquia Formation of Paleocene age in Southern Maryland during September 2003. The map is based on water-level measurements in 91 wells. The highest measured water level was 40 feet above sea level near the northern boundary and outcrop area of the aquifer in the central part of Anne Arundel County, and was below sea level just south of this area and in the remainder of the study area. The hydraulic gradient increased southeastward toward an extensive cone of depression around well fields at Lexington Park and Solomons Island. Another cone of depression occurred in northern Calvert County due to pumpage at and near North Beach and Chesapeake Beach. The water level measured in this area has declined to 48 feet below sea level. The lowest water level measured was 156 feet below sea level at the center of a cone of depression at Lexington Park.

Effect of colloidal particleson the foamability and stabilization of aqueous foams by cationic surfactant CTAB

NASA Astrophysics Data System (ADS)

Cao, Huiying; Chen, Jiayi; Cai, Jie; Li, Yapin

2017-12-01

Colloidal particles can influence the foamability and stabilization of aqueous foam by addition of surfactant at the air-water interface. This occurs because particles are activated via the interaction with surfactant and are adsorbed onto the surfaces of foams. This phenomenon has been applied extensively to the development of new materials and techniques. Whether particle surface can be activated or not is decided by the interaction between the surfactant and the particle. In this work, we studied the effects of cationic surfactant CTAB (cetyltrimethylammonium bromide) on PS (polystyrene), SiO2, and TiO2 particles in aqueous solution, and compared the difference in their surface activation according to foam volume of the particles/CTAB/water system, and the degrees of foamability and foam stabilization. In addition, the influence of anionic surfactant SDS (sodium dodecyl sulfate) on the surface activation of PS in aqueous solution was also analyzed and compared with that of CTAB.

A review on wetting and water condensation - Perspectives for CO2 condensation.

PubMed

Snustad, Ingrid; Røe, Ingeborg T; Brunsvold, Amy; Ervik, Åsmund; He, Jianying; Zhang, Zhiliang

2018-06-01

Liquefaction of vapor is a necessary, but energy intensive step in several important process industries. This review identifies possible materials and surface structures for promoting dropwise condensation, known to increase efficiency of condensation heat transfer. Research on superhydrophobic and superomniphobic surfaces promoting dropwise condensation constitutes the basis of the review. In extension of this, knowledge is extrapolated to condensation of CO 2 . Global emissions of CO 2 need to be minimized in order to reduce global warming, and liquefaction of CO 2 is a necessary step in some carbon capture, transport and storage (CCS) technologies. The review is divided into three main parts: 1) An overview of recent research on superhydrophobicity and promotion of dropwise condensation of water, 2) An overview of recent research on superomniphobicity and dropwise condensation of low surface tension substances, and 3) Suggested materials and surface structures for dropwise CO 2 condensation based on the two first parts. Copyright © 2018 Elsevier B.V. All rights reserved.

Botswana water and surface energy balance research program. Part 2: Large scale moisture and passive microwaves

NASA Technical Reports Server (NTRS)

Vandegriend, A. A.; Owe, M.; Chang, A. T. C.

1992-01-01

The Botswana water and surface energy balance research program was developed to study and evaluate the integrated use of multispectral satellite remote sensing for monitoring the hydrological status of the Earth's surface. The research program consisted of two major, mutually related components: a surface energy balance modeling component, built around an extensive field campaign; and a passive microwave research component which consisted of a retrospective study of large scale moisture conditions and Nimbus scanning multichannel microwave radiometer microwave signatures. The integrated approach of both components are explained in general and activities performed within the passive microwave research component are summarized. The microwave theory is discussed taking into account: soil dielectric constant, emissivity, soil roughness effects, vegetation effects, optical depth, single scattering albedo, and wavelength effects. The study site is described. The soil moisture data and its processing are considered. The relation between observed large scale soil moisture and normalized brightness temperatures is discussed. Vegetation characteristics and inverse modeling of soil emissivity is considered.

Distribution of aquifers, liquid-waste impoundments, and municipal water-supply sources, Massachusetts

USGS Publications Warehouse

Delaney, David F.; Maevsky, Anthony

1980-01-01

Impoundments of liquid waste are potential sources of ground-water contamination in Massachusetts. The map report, at a scale of 1 inch equals 4 miles, shows the idstribution of aquifers and the locations of municipal water-supply sources and known liquid-waste impoundments. Ground water, an important source of municipal water supply, is produced from shallow sand and gravel aquifers that are generally unconfined, less than 200 feet thick, and yield less than 2,000 gallons per minute to individual wells. These aquifers commonly occupy lowlands and stream valleys and are most extensive in eastern Massachusetts. Surface impoundments of liquid waste are commonly located over these aquifers. These impoundments may leak and allow waste to infiltrate underlying aquifers and alter their water quality. (USGS)

Elementary Chemical Reactions in Surface Photocatalysis

NASA Astrophysics Data System (ADS)

Guo, Qing; Zhou, Chuanyao; Ma, Zhibo; Ren, Zefeng; Fan, Hongjun; Yang, Xueming

2018-04-01

Photocatalytic hydrogen evolution and organic degradation on oxide materials have been extensively investigated in the last two decades. Great efforts have been dedicated to the study of photocatalytic reaction mechanisms of a variety of molecules on TiO2 surfaces by using surface science methods under ultra-high vacuum (UHV) conditions, providing fundamental understanding of surface chemical reactions in photocatalysis. In this review, we summarize the recent progress in the study of photocatalysis of several important species (water, methanol, and aldehydes) on different TiO2 surfaces. The results of these studies have provided us deep insights into the elementary processes of surface photocatalysis and stimulated a new frontier of research in this area. Based on the results of these studies, a new dynamics-based photocatalysis model is also discussed.

Nitrogen and carbon dynamics beneath on-site wastewater treatment systems in Pitt County, North Carolina.

PubMed

Del Rosario, Katie L; Humphrey, Charles P; Mitra, Siddhartha; O'Driscoll, Michael A

2014-01-01

On-site wastewater treatment systems (OWS) are a potentially significant non-point source of nutrients to groundwater and surface waters, and are extensively used in coastal North Carolina. The goal of this study was to determine the treatment efficiency of four OWS in reducing total dissolved nitrogen (TDN) and dissolved organic carbon (DOC) concentrations before discharge to groundwater and/or adjacent surface water. Piezometers were installed for groundwater sample collection and nutrient analysis at four separate residences that use OWS. Septic tank effluent, groundwater, and surface water samples (from an adjacent stream) were collected four times during 2012 for TDN and DOC analysis and pH, temperature, electrical conductivity, and dissolved oxygen measurements. Treatment efficiencies from the tank to the groundwater beneath the drainfields ranged from 33 to 95% for TDN and 45 to 82% for DOC, although dilution accounted for most of the concentration reductions. There was a significant positive correlation between nitrate concentration and separation distance from trench bottom to water table and a significant negative correlation between DOC concentration and separation distance. The TDN and DOC transport (>15 m) from two OWS with groundwater saturated drainfield trenches was significant.

Rapid, sensitive and direct analysis of exopolysaccharides from biofilm on aluminum surfaces exposed to sea water using MALDI-TOF MS.

PubMed

Hasan, Nazim; Gopal, Judy; Wu, Hui-Fen

2011-11-01

Biofilm studies have extensive significance since their results can provide insights into the behavior of bacteria on material surfaces when exposed to natural water. This is the first attempt of using matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) for detecting the polysaccharides formed in a complex biofilm consisting of a mixed consortium of marine microbes. MALDI-MS has been applied to directly analyze exopolysaccharides (EPS) in the biofilm formed on aluminum surfaces exposed to seawater. The optimal conditions for MALDI-MS applied to EPS analysis of biofilm have been described. In addition, microbiologically influenced corrosion of aluminum exposed to sea water by a marine fungus was also observed and the fungus identity established using MALDI-MS analysis of EPS. Rapid, sensitive and direct MALDI-MS analysis on biofilm would dramatically speed up and provide new insights into biofilm studies due to its excellent advantages such as simplicity, high sensitivity, high selectivity and high speed. This study introduces a novel, fast, sensitive and selective platform for biofilm study from natural water without the need of tedious culturing steps or complicated sample pretreatment procedures. Copyright © 2011 John Wiley & Sons, Ltd.

Atmospheric stability analysis over statically and dynamically rough surfaces

NASA Astrophysics Data System (ADS)

Maric, Emina; Metzger, Meredith; Singha, Arindam; Sadr, Reza

2011-11-01

The ratio of buoyancy flux to turbulent kinetic energy production in the atmospheric surface layer is investigated experimentally for air flow over two types of surfaces characterized by static and dynamic roughness. In this study, ``static'' refers to the time-invariant nature of naturally-occurring roughness over a mud/salt playa; while, ``dynamic'' refers to the behavior of water waves along an air-water interface. In both cases, time-resolved measurements of the momentum and heat fluxes were acquired from synchronized 3D sonic anemometers mounted on a vertical tower. Field campaigns were conducted at two sites, representing the ``statically'' and ``dynamically'' rough surfaces, respectively: (1) the SLTEST facility in Utah's western desert, and (2) the new Doha airport in Qatar under construction along the coast of the Persian Gulf. Note, at site 2, anemometers were located directly above the water by extension from a tower secured to the end of a 1 km-long pier. Comparisons of the Monin-Obukhov length, flux Richardson number, and gradient Richardson number are presented, and discussed in the context of the observed evolution of the turbulent spectra in response to diurnal variations of atmospheric stability. Supported by the Qatar National Research Fund.

Modeling of Dense Water Production and Salt Transport from Alaskan Coastal Polynyas

NASA Technical Reports Server (NTRS)

Signorini, Sergio R.; Cavalieri, Donald J.

2000-01-01

The main significance of this paper is that a realistic, three-dimensional, high-resolution primitive equation model has been developed to study the effects of dense water formation in Arctic coastal polynyas. The model includes realistic ambient stratification, realistic bottom topography, and is forced by time-variant surface heat flux, surface salt flux, and time-dependent coastal flow. The salt and heat fluxes, and the surface ice drift, are derived from satellite observations (SSM/I and NSCAT sensors). The model is used to study the stratification, salt transport, and circulation in the vicinity of Barrow Canyon during the 1996/97 winter season. The coastal flow (Alaska coastal current), which is an extension of the Bering Sea throughflow, is formulated in the model using the wind-transport regression. The results show that for the 1996/97 winter the northeastward coastal current exports 13% to 26% of the salt produced by coastal polynyas upstream of Barrow Canyon in 20 to 30 days. The salt export occurs more rapidly during less persistent polynyas. The inclusion of ice-water stress in the model makes the coastal current slightly weaker and much wider due to the combined effects of surface drag and offshore Ekman transport.

Investigating the hydrological origins of Blood Falls - geomicrobiological insights into a briny subglacial Antarctic aquifer

NASA Astrophysics Data System (ADS)

Mikucki, J.; Tulaczyk, S. M.; Purcell, A. M.; Dachwald, B.; Lyons, W. B.; Welch, K. A.; Auken, E.; Dugan, H. A.; Walter, J. I.; Pettit, E. C.; Doran, P. T.; Virginia, R. A.; Schamper, C.; Foley, N.; Feldmann, M.; Espe, C.; Ghosh, D.; Francke, G.

2015-12-01

Subglacial waters tend to accumulate solutes from extensive rock-water interactions, which, when released to the surface, can provide nutrients to surface ecosystems providing a 'hot spot' for microbial communities. Blood Falls, an iron-rich, saline feature at the terminus of Taylor Glacier in the McMurdo Dry Valleys, Antarctica is a well-studied subglacial discharge. Here we present an overview of geophysical surveys, thermomechanical drilling exploration and geomicrobiological analyses of the Blood Falls system. A helicopter-borne transient electromagnetic system (SkyTEM) flown over the Taylor Glacier revealed a surprisingly extensive subglacial aquifer and indicates that Blood Falls may be the only surface manifestation of this extensive briny groundwater. Ground-based temperature sensing and GPR data combined with the helicopter-borne TEM data enabled targeted drilling into the englacial conduit that delivers brine to the surface. During the 2014-15 austral summer field season, we used a novel ice-melting drill (the IceMole) to collect englacial brine for geomicrobiological analyses. Results from previously collected outflow and more recent samples indicate that the brine harbors a metabolically active microbial community that persists, despite cold, dark isolation. Isotope geochemistry and molecular analysis of functional genes from BF suggested that a catalytic or 'cryptic' sulfur cycle was linked to iron reduction. Recent metagenomic analysis confirms the presence of numerous genes involved in oxidative and reductive sulfur transformations. Metagenomic and metabolic activity data also indicate that subglacial dark CO2 fixation occurs via various pathways. Genes encoding key steps in CO2 fixation pathways including the Calvin Benson Basham and Wood Ljungdahl pathway were present and brine samples showed measureable uptake of 14C-labeled bicarbonate. These results support the notion that, like the deep subsurface, subglacial environments are chemosynthetic, deriving energy in part by cycling iron and sulfur compounds. Collectively our interdisciplinary dataset indicates that subsurface brines are widespread in the Taylor Valley polar desert and this previously unknown groundwater network likely supports unique microbial life.

Geology and ground-water features of salt springs, seeps, and plains in the Arkansas and Red River basins of western Oklahoma and adjacent parts of Kansas and Texas

USGS Publications Warehouse

Ward, P.E.

1963-01-01

The salt springs, seeps, and plains described in this report are in the Arkansas and Red River basins in western Oklahoma and adjacent areas in Kansas and Texas. The springs and seeps contribute significantly to the generally poor water quality of the rivers by bringing salt (HaCI) to the surface at an estimated daily rate of more than 8,000 tons. The region investigated is characterized by low hills and rolling plains. Many of the rivers are eroded 100 feet or more below the .surrounding upland surface and in places the valleys are bordered by steep bluffs. The alluvial plains of the major rivers are wide and the river channels are shallow and unstable. The flow of many surface streams is intermittent, especially in the western part of the area. All the natural salt-contributing areas studied are within the outcrop area of rocks of Permian age. The Permian rocks, commonly termed red beds, are composed principally of red and gray gypsiferous shale, siltstone, sandstone, gypsum, anhydrite, and dolomite. Many of the formations contain halite in the subsurface. The halite occurs mostly as discontinuous lenses in shale, although some of the thicker, more massive beds are extensive. It underlies the entire region studied at depths ranging from about 30 feet to more than 2,000 feet. The salt and associated strata show evidence of extensive removal of salt through solution by ground water. Although the salt generally occurs in relatively impervious shale small joints and fractures ,allow the passage of small quantities of water which dissolves the salt. Salt water occurs in the report area at depths ranging from less than 100 feet to more than 1,000 feet. Salt water occurs both as meteoric and connate, but the water emerging as salt springs is meteoric. Tritium analyses show that the age of the water from several springs is less than 20 years. The salt springs, seeps, and plains are confined to 13 local areas. The flow of the springs and seeps is small, but the chloride concentration in the water ranges from a few hundred parts per million to about 190,000 ppm. The wide range of concentration is believed to be due, in part, to differential dilution by fresh water. Alluvium in the vicinity of the salt springs remains saturated with salt water and evaporation from the alluvial surface causes the formation of a salt crust during dry weather. Those areas appear as salt plains that range in size from less than an acre to as much as 60 square miles. The rocks exposed at the surface in the vicinity of the salt springs are permeable enough to allow the infiltration of some precipitation. Under certain geologic and hydrologic conditions ground water percolates down and through salt-bearing rocks where it dissolves the .salt. Hydrostatic pressure of ground water at higher elevations forces the salt water to emerge as salt springs at lower elevations.

Vadose zone microbiology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kieft, Thomas L.; Brockman, Fred J.

2001-01-17

The vadose zone is defined as the portion of the terrestrial subsurface that extends from the land surface downward to the water table. As such, it comprises the surface soil (the rooting zone), the underlying subsoil, and the capillary fringe that directly overlies the water table. The unsaturated zone between the rooting zone and the capillary fringe is termed the "intermediate zone" (Chapelle, 1993). The vadose zone has also been defined as the unsaturated zone, since the sediment pores and/or rock fractures are generally not completely water filled, but instead contain both water and air. The latter characteristic results inmore » the term "zone of aeration" to describe the vadose zone. The terms "vadose zone," "unsaturated zone", and "zone of aeration" are nearly synonymous, except that the vadose zone may contain regions of perched water that are actually saturated. The term "subsoil" has also been used for studies of shallow areas of the subsurface immediately below the rooting zone. This review focuses almost exclusively on the unsaturated region beneath the soil layer since there is already an extensive body of literature on surface soil microbial communities and process, e.g., Paul and Clark (1989), Metting (1993), Richter and Markowitz, (1995), and Sylvia et al. (1998); whereas the deeper strata of the unsaturated zone have only recently come under scrutiny for their microbiological properties.« less

Effects of lengthscales and attractions on the collapse of hydrophobic polymers in water

PubMed Central

Athawale, Manoj V.; Goel, Gaurav; Ghosh, Tuhin; Truskett, Thomas M.; Garde, Shekhar

2007-01-01

We present results from extensive molecular dynamics simulations of collapse transitions of hydrophobic polymers in explicit water focused on understanding effects of lengthscale of the hydrophobic surface and of attractive interactions on folding. Hydrophobic polymers display parabolic, protein-like, temperature-dependent free energy of unfolding. Folded states of small attractive polymers are marginally stable at 300 K and can be unfolded by heating or cooling. Increasing the lengthscale or decreasing the polymer–water attractions stabilizes folded states significantly, the former dominated by the hydration contribution. That hydration contribution can be described by the surface tension model, ΔG = γ(T)ΔA, where the surface tension, γ, is lengthscale-dependent and decreases monotonically with temperature. The resulting variation of the hydration entropy with polymer lengthscale is consistent with theoretical predictions of Huang and Chandler [Huang DM, Chandler D (2000) Proc Natl Acad Sci USA 97:8324–8327] that explain the blurring of entropy convergence observed in protein folding thermodynamics. Analysis of water structure shows that the polymer–water hydrophobic interface is soft and weakly dewetted, and is characterized by enhanced interfacial density fluctuations. Formation of this interface, which induces polymer folding, is strongly opposed by enthalpy and favored by entropy, similar to the vapor–liquid interface. PMID:17215352

Free energy barriers for escape of water molecules from protein hydration layer.

PubMed

Roy, Susmita; Bagchi, Biman

2012-03-08

Free energy barriers separating interfacial water molecules from the hydration layer at the surface of a protein to the bulk are obtained by using the umbrella sampling method of free energy calculation. We consider hydration layer of chicken villin head piece (HP-36) which has been studied extensively by molecular dynamics simulations. The free energy calculations reveal a strong sensitivity to the secondary structure. In particular, we find a region near the junction of first and second helix that contains a cluster of water molecules which are slow in motion, characterized by long residence times (of the order of 100 ps or more) and separated by a large free energy barrier from the bulk water. However, these "slow" water molecules constitute only about 5-10% of the total number of hydration layer water molecules. Nevertheless, they play an important role in stabilizing the protein conformation. Water molecules near the third helix (which is the important helix for biological function) are enthalpically least stable and exhibit the fastest dynamics. Interestingly, barrier height distributions of interfacial water are quite broad for water surrounding all the three helices (and the three coils), with the smallest barriers found for those near the helix-3. For the quasi-bound water molecules near the first and second helices, we use well-known Kramers' theory to estimate the residence time from the free energy surface, by estimating the friction along the reaction coordinate from the diffusion coefficient by using Einstein relation. The agreement found is satisfactory. We discuss the possible biological function of these slow, quasi-bound (but transient) water molecules on the surface.

Guide to Louisiana's ground-water resources

USGS Publications Warehouse

Stuart, C.G.; Knochenmus, D.D.; McGee, B.D.

1994-01-01

Ground water is one of the most valuable and abundant natural resources of Louisiana. Of the 4-.4 million people who live in the State, 61 percent use ground water as a source for drinking water. Most industrial and rural users and half of the irrigation users in the State rely on ground water. Quantity, however, is not the only aspect that makes ground water so valuable; quality also is important for its use. In most areas, little or no water treatment is required for drinking water and industrial purposes. Knowledge of Louisiana's ground-water resources is needed to ensure proper development and protection of this valuable resource. This report is designed to inform citizens about the availability and quality of ground water in Louisiana. It is not intended as a technical reference; rather, it is a guide to ground water and the significant role this resource plays in the state. Most of the ground water that is used in the State is withdrawn from 13 aquifers and aquifer systems: the Cockfield, Sparta, and Carrizo-Wilcox aquifersin northern Louisiana; Chicot aquifer system, Evangeline aquifer, Jasper aquifer system, and Catahoula aquifer in central and southwestern Louisiana; the Chicot equivalent, Evangeline equivalent, and Jasper equivalent aquifer systems in southeastern Louisiana; and the MississippiRiver alluvial, Red River alluvial, and upland terrace aquifers that are statewide. Ground water is affected by man's activities on the land surface, and the major ground-water concerns in Louisiana are: (1) contamination from surface disposal of hazardous waste, agricultural chemicals, and petroleum products; (2) contamination from surface wastes and saltwater through abandoned wells; (3) saltwater encroachment; and (4) local overdevelopment. Information about ground water in Louisiana is extensive and available to the public. Several State and Federal agencies provide published and unpublished material upon request.

The effects of oil-in-water nanoemulsion polyethylene glycol surface density on intracellular stability, pharmacokinetics, and biodistribution in tumor bearing mice.

PubMed

Hak, Sjoerd; Garaiova, Zuzana; Olsen, Linda Therese; Nilsen, Asbjørn Magne; de Lange Davies, Catharina

2015-04-01

Lipid-based nanoparticles are extensively studied for drug delivery. These nanoparticles are often surface-coated with polyethylene glycol (PEG) to improve their biodistribution. Until now, the effects of varying PEG surface density have been studied in a narrow and low range. Here, the effects of high and a broad range of PEG surface densities on the in vivo performance of lipid-based nanoparticles were studied. Oil-in-water nanoemulsions were prepared with PEG surface densities of 5-50 mol%. Confocal microscopy was used to assess intracellular disintegration in vitro. In vivo pharmacokinetics and biodistribution in tumor bearing mice were studied using a small animal optical imager. PEG surface density did not affect intracellular nanoemulsion stability. Surprisingly, circulation half-lives decreased with increasing PEG surface density. A plausible explanation was that nanoemulsion with high (50 mol%) PEG surface density activated the complement in a whole blood assay, whereas nanoemulsion with low (5 mol%) PEG density did not. In vivo, nanoemulsion with low PEG surface density was mostly confined to the tumor and organs of the mononuclear phagocyte system, whereas nanoemulsion with high PEG density accumulated throughout the mouse. Optimal PEG surface density of lipid-based nanoparticles for tumor targeting was found to be below 10 mol%.

Evapotranspiration from nonuniform surfaces - A first approach for short-term numerical weather prediction

NASA Technical Reports Server (NTRS)

Wetzel, Peter J.; Chang, Jy-Tai

1988-01-01

Observations of surface heterogeneity of soil moisture from scales of meters to hundreds of kilometers are discussed, and a relationship between grid element size and soil moisture variability is presented. An evapotranspiration model is presented which accounts for the variability of soil moisture, standing surface water, and vegetation internal and stomatal resistance to moisture flow from the soil. The mean values and standard deviations of these parameters are required as input to the model. Tests of this model against field observations are reported, and extensive sensitivity tests are presented which explore the importance of including subgrid-scale variability in an evapotranspiration model.

Preparation of affordable and multifunctional clay-based ceramic filter matrix for treatment of drinking water.

PubMed

Shivaraju, H Puttaiah; Egumbo, Henok; Madhusudan, P; Anil Kumar, K M; Midhun, G

2018-02-01

Affordable clay-based ceramic filters with multifunctional properties were prepared using low-cost and active ingredients. The characterization results clearly revealed well crystallinity, structural elucidation, extensive porosity, higher surface area, higher stability, and durability which apparently enhance the treatment efficiency. The filtration rates of ceramic filter were evaluated under gravity and the results obtained were compared with a typical gravity slow sand filter (GSSF). All ceramic filters showed significant filtration rates of about 50-180 m/h, which is comparatively higher than the typical GSSF. Further, purification efficiency of clay-based ceramic filters was evaluated by considering important drinking water parameters and contaminants. A significant removal potential was achieved by the clay-based ceramic filter with 25% and 30% activated carbon along with active agents. Desired drinking water quality parameters were achieved by potential removal of nitrite (98.5%), nitrate (80.5%), total dissolved solids (62%), total hardness (55%), total organic pollutants (89%), and pathogenic microorganisms (100%) using ceramic filters within a short duration. The remarkable purification and disinfection efficiencies were attributed to the extensive porosity (0.202 cm 3  g -1 ), surface area (124.61 m 2  g -1 ), stability, and presence of active nanoparticles such as Cu, TiO 2 , and Ag within the porous matrix of the ceramic filter.

Applicability of 87Sr/86Sr in examining return flow of irrigation water in highly agricultural watersheds in Japan

NASA Astrophysics Data System (ADS)

Yoshida, T.; Nakano, T.; Shin, K. C.; Tsuchihara, T.; Miyazu, S.; Kubota, T.

2017-12-01

Water flows in watersheds containing extensive areas of irrigated paddies are complex because of the substantial volumes involved and the repeated cycles of water diversion from, and return to, streams. For better management of low-flow conditions, numerous studies have attempted to quantify the return flow using the stable isotopes of water; however, the temporal variation in these isotopic compositions due to fractionation during evaporation from water surfaces hinders their application to watersheds with extensive irrigated paddies. In this study, we tested the applicability of the strontium isotopes (87Sr/86Sr, hereafter Sr ratio) for studying hydrological processes in a typical agricultural watershed located on the alluvial fan of the Kinu River, namely the Gogyo River, in central Japan. The Sr ratio of water changes only because of interactions with the porous media it flows through, or because of mixing with water that has different Sr ratios. We sampled water both at a single rice paddy, and on the watershed scale in the irrigated and non-irrigated periods. The soil water under the paddy decreased as sampling depth increased, and the soil water at a depth of 1.5 m showed a similar Sr ratio to the spring. The water sampled in the drainage channel with a concrete lined bottom showed a similar Sr ratio to the irrigation water, whereas that with a soil bottom was plotted between the plots of the irrigation water and shallow aquifer. These results suggest the Sr ratio decreases as it mixes with the soil water through percolation; whereas the Sr ratio will be less likely to change when water drains from paddies via surface pathways. The streamflow samples were plotted linearly on the Sr ratio and 1/Sr plot, indicating that the streamflow was composed of two end-members; the irrigation water and the shallow aquifer. The continuous decline in the Sr ratio along the stream suggests an exfiltration of water from the shallow aquifers. The stream water during the non-irrigated period were lower in Sr ratios and higher in Sr concentrations, suggesting an increase in contributions of the water from the shallow aquifers. Understanding the return flow of irrigation water in highly agricultural watersheds is vital for measuring any temporal changes in flow to the lower parts of the watershed, and allows for improved water management.

Short-term effects of oil ingestion on American kestrels (Falco sparverius).

PubMed

Pattee, O H; Franson, J C

1982-04-01

The Mexican Ixtoc oil well blowout resulted in extensive oil contamination along the Texas Gulf coast. This oil posed a potential hazard to migrating birds including the endangered peregrine falcon (Falco peregrinus). Laboratory tests with the American kestrel (Falco sparverius) indicated that the oil: water mixture gathered at the surface of the blowout site posed little acute hazard to falcons.

Ecological benefits and risks arising from liming sugar maple dominated forests in northeastern North America

Treesearch

Jean-David Moore; Rock Ouimet; Robert P. Long; Paul. A. Bukaveckas

2015-01-01

Liming, the application of carbonate materials (e.g., CaCO3, CaMg(CO3)2) to soils and surface waters, has been used extensively in Europe, and to a lesser extent in Canada and the United States, to mitigate the effects of acid deposition on forest and aquatic ecosystems. This literature review was...

Charge-induced equilibrium dynamics and structure at the Ag(001)–electrolyte interface

DOE PAGES

Karl Jr., Robert M.; Barbour, Andi; Komanicky, Vladimir; ...

2015-06-08

We have measured the applied potential dependent rate of atomic step motion of the Ag (001) surface in weak NaF electrolyte using a new extension of the technique of X-ray Photon Correlation Spectroscopy (XPCS). Furthermore, concurrent specular x-ray scattering measurements reveal how the ordering of the water layers at the interface correlates with the dynamics.

Potentiometric Surface of the Aquia Aquifer in Southern Maryland, September 1999

USGS Publications Warehouse

Curtin, Stephen E.; Andreasen, David C.; Wheeler, Judith C.

2001-01-01

This report presents a map showing the potentiometric surface of the Aquia aquifer in the Aquia Formation of Paleocene age in Southern Maryland during September 1999. The map is based on water-level measurements in 85 wells. The potentiometric surface was above sea level near the northern boundary and outcrop area of the aquifer in a topographically high area of Anne Arundel County, and was below sea level in the remainder of the study area. The hydraulic gradient was directed southeastward toward an extensive cone of depression around well fields at Lexington Park and Solomons Island. Ground-water levels were more than 80 feet below sea level in a 100-square-mile area surrounding the deepest part of the cone of depression. A cone of depression formed in northern Calvert County due to pumpage at Chesapeake Beach and North Beach. The water level has declined to 43 feet below sea level in this area. The lowest measurement was 164 feet below sea level in a well near the center of the cone of depression at Lexington Park.

Top-down or bottom-up? Assessing crevassing directions on surging glaciers and developments for physically testing glacier crevassing models.

NASA Astrophysics Data System (ADS)

Rea, B.; Evans, D. J. A.; Benn, D. I.; Brennan, A. J.

2012-04-01

Networks of crevasse squeeze ridges (CSRs) preserved on the forelands of many surging glaciers attest to extensive full-depth crevassing. Full-depth connections have been inferred from turbid water up-welling in crevasses and the formation of concertina eskers however, it has not been clearly established if the crevasses formed from the top-down or the bottom-up. A Linear Elastic Fracture Mechanics (LEFM) approach is used to determine the likely propagation direction for Mode I crevasses on seven surging glaciers. Results indicate that, the high extensional surface strain rates are insufficient to promote top-down full-depth crevasses but have sufficient magnitude to penetrate to depths of 4-12 m, explaining the extensive surface breakup accompanying glacier surges. Top-down, full-depth crevassing is only possible when water depth approaches 97% of the crevasse depth. However, the provision of sufficient meltwater is problematic due to the aforementioned extensive shallow surface crevassing. Full-depth, bottom-up crevassing can occur provided basal water pressures are in excess of 80-90% of flotation which is the default for surging and on occasion water pressures may even become artesian. Therefore CSRs, found across many surging glacier forelands and ice margins most likely result from the infilling of basal crevasses formed, for the most part, by bottom-up hydrofracturing. Despite the importance of crevassing for meltwater routing and calving dynamics physically testing numerical crevassing models remains problematic due to technological limitations, changing stress regimes and difficulties associated with working in crevasse zones on glaciers. Mapping of CSR spacing and matching to surface crevasse patterns can facilitate quantitative comparison between the LEFM model and observed basal crevasses provided ice dynamics are known. However, assessing full-depth top-down crevasse propagation is much harder to monitor in the field and no geomorphological record is preserved. An alternative approach is provided by geotechnical centrifuge modelling. By testing scaled models in an enhanced 'gravity' field real-world (prototype) stress conditions can be reproduced which is crucial for problems governed by self-weight stresses, of which glacier crevassing is one. Scaling relationships have been established for stress intensity factors - KI which are key to determining crevasse penetration such that KIp = √N KIm (p = prototype and m = model). Operating specifications of the University of Dundee geotechnical centrifuge (100g) will allow the testing of scaled models equivalent to prototype glaciers of 50 m thickness in order to provide a physical test of the LEFM top-down crevassing model.

River analysis and floodplain modeling using HEC-GeoRAS/RAS, GIS and ArcGIS: a case study for the Salinas River

NASA Astrophysics Data System (ADS)

Mishra, P. K.; Bernini Campos, H. E.

2016-12-01

The lower portion of the Salinas River in Monterey bay, California has a history of flood, lots of study has been made ab out the water quality since the river provides water for the crops around, but is still in need a detailed study about the river behavior and flood analysis. The floods did significant damage, affecting valuable landing farms, residences and businesses in Monterey County. The first step for this study is comprehend and collect the river bathymetry and surroundings and then analyze the discharge and how it is going to change with time. This thesis develops a model about the specific site, recruiting real data from GIS and performing a flow simulation according to flow data provided by USGS, to verify water surface elevation and floodplain. The ArcMap, developed by ESRI, was used along with an extension (HEC-GeoRAS) because it was indeed the most appropriate model to work with the Digital Elevation Model, develop the floodplain and characterizing the land surface accurately in the study site. The HEC-RAS software, developed by US Army Corp of Engineers, was used to compute one-dimension steady flow and two-dimension unsteady flow, providing flow velocity, water surface elevation and profiles, total surface area, head and friction loss and other characteristics, allowing the analysis of the flow. A mean discharge, a mean peak streamflow and a peak discharge were used for the steady flow and a Hydrograph was used for the unsteady flow, both are based on the 1995 flood and discharge history. This study provides important information about water surface elevation and water flow, allowing stakeholders and the government to analyze solutions to avoid damage to the society and landowners.

Climate Responses to Changes in Land-surface Properties due to Wildfires

NASA Astrophysics Data System (ADS)

Liu, Y.; Hao, X.; Qu, J. J.

2015-12-01

Wildfires can feedback the atmosphere by impacting atmospheric radiation transfer and cloud microphysics through emitting smoke particles and the land-air heat and water fluxes through modifying land-surface properties. While the impacts through smoke particles have been extensively investigated recently, very few studies have been conducted to examine the impacts through land-surface property change. This study is to fill this gap by examining the climate responses to the changes in land-surface properties induced by several large wildfires in the United States. Satellite remote sensing tools including MODIS and Landsat are used to quantitatively evaluate the land-surface changes characterized by reduced vegetation coverage and increased albedo over long post-fire periods. Variations in air and soil temperature and moisture of the burned areas are also monitored. Climate modeling is conducted to simulate climate responses and understand the related physical processes and interactions. The preliminary results indicate noticeable changes in water and heat transfers from the ground to the atmosphere through several mechanisms. Larger albedo reduces solar radiation absorbed on the ground, leading to less energy for latent and sensible heat fluxes. With smaller vegetation coverage, water transfer from the soil to the atmosphere through transpiration is reduced. Meanwhile, the Bowen ratio becomes larger after burning and therefore more solar energy absorbed on the ground is converted into sensible heat instead of being used as latent energy for water phase change. In addition, reduced vegetation coverage reduces roughness and increases wind speed, which modify dynamic resistances to water and heat movements. As a result of the changes in the land-air heat and water fluxes, clouds and precipitation as well as other atmospheric processes are affected by wildfires.

Gill area, permeability and Na+ ,K+ -ATPase activity as a function of size and salinity in the blue crab, Callinectes sapidus.

PubMed

Li, Tiandao; Roer, Robert; Vana, Matthew; Pate, Susan; Check, Jennifer

2006-03-01

Juvenile blue crabs, Callinectes sapidus, extensively utilize oligohaline and freshwater regions of the estuary. With a presumptively larger surface-area-to-body weight ratio, juvenile crabs could experience osmo- and ionoregulatory costs well in excess of that of adults. To test this hypothesis, crabs ranging over three orders of magnitude in body weight were acclimated to either sea water (1,000 mOsm) or dilute sea water (150 mOsm), and gill surface area, water and sodium permeabilities (calculated from the passive efflux of 3H2O and 22Na+), gill Na+, K+ -ATPase activity and expression were measured. Juveniles had a relatively larger gill surface area; weight-specific gill surface area decreased with body weight. Weight-specific water and sodium fluxes also decreased with weight, but not to the same extent as gill surface area; thus juveniles were able to decrease gill permeability slightly more than adults upon acclimation to dilute media. Crabs < 5 g in body weight had markedly higher activities of gill Na+ ,K+ -ATPase than crabs > 5 g in both posterior and anterior gills. Acclimation to dilute medium induced increased expression of Na+, K+ -ATPase and enzyme activity, but the increase was not as great in juveniles as in larger crabs. The increased weight-specific surface area for water gain and salt loss for small crabs in dilute media presents a challenge that is incompletely compensated by reduced permeability and increased affinity of gill Na+, K+ -ATPase for Na+. Juveniles maintain osmotic and ionic homeostasis by the expression and utilization of extremely high levels of gill Na+, K+ -ATPase, in posterior, as well as in anterior, gills. Copyright 2006 Wiley-Liss, Inc.

Estimation of available water capacity components of two-layered soils using crop model inversion: Effect of crop type and water regime

NASA Astrophysics Data System (ADS)

Sreelash, K.; Buis, Samuel; Sekhar, M.; Ruiz, Laurent; Kumar Tomer, Sat; Guérif, Martine

2017-03-01

Characterization of the soil water reservoir is critical for understanding the interactions between crops and their environment and the impacts of land use and environmental changes on the hydrology of agricultural catchments especially in tropical context. Recent studies have shown that inversion of crop models is a powerful tool for retrieving information on root zone properties. Increasing availability of remotely sensed soil and vegetation observations makes it well suited for large scale applications. The potential of this methodology has however never been properly evaluated on extensive experimental datasets and previous studies suggested that the quality of estimation of soil hydraulic properties may vary depending on agro-environmental situations. The objective of this study was to evaluate this approach on an extensive field experiment. The dataset covered four crops (sunflower, sorghum, turmeric, maize) grown on different soils and several years in South India. The components of AWC (available water capacity) namely soil water content at field capacity and wilting point, and soil depth of two-layered soils were estimated by inversion of the crop model STICS with the GLUE (generalized likelihood uncertainty estimation) approach using observations of surface soil moisture (SSM; typically from 0 to 10 cm deep) and leaf area index (LAI), which are attainable from radar remote sensing in tropical regions with frequent cloudy conditions. The results showed that the quality of parameter estimation largely depends on the hydric regime and its interaction with crop type. A mean relative absolute error of 5% for field capacity of surface layer, 10% for field capacity of root zone, 15% for wilting point of surface layer and root zone, and 20% for soil depth can be obtained in favorable conditions. A few observations of SSM (during wet and dry soil moisture periods) and LAI (within water stress periods) were sufficient to significantly improve the estimation of AWC components. These results show the potential of crop model inversion for estimating the AWC components of two-layered soils and may guide the sampling of representative years and fields to use this technique for mapping soil properties that are relevant for distributed hydrological modelling.

The influence of irrigation water on the hydrology and lake water budgets of two small arid-climate lakes in Khorezm, Uzbekistan

USGS Publications Warehouse

Scott, J.; Rosen, Michael R.; Saito, L.; Decker, D.L.

2011-01-01

Little is known regarding the origins and hydrology of hundreds of small lakes located in the western Uzbekistan province of Khorezm, Central Asia. Situated in the Aral Sea Basin, Khorezm is a productive agricultural region, growing mainly cotton, wheat, and rice. Irrigation is provided by an extensive canal network that conveys water from the Amu Darya River (AD) throughout the province. The region receives on average 10 cm/year of precipitation, yet potential evapotranspiration exceeds this amount by about 15 times. It was hypothesized that the perennial existence of the lakes of interest depends on periodic input of excess irrigation water. This hypothesis was investigated by studying two small lakes in the region, Tuyrek and Khodjababa. In June and July 2008, surface water and shallow groundwater samples were collected at these lake systems and surrounding communities and analyzed for δ2H, δ18O, and major ion hydrochemistry to determine water sources. Water table and lake surface elevations were monitored, and the local aquifer characteristics were determined through aquifer tests. These data and climate data from a Class A evaporation pan and meteorological stations were used to estimate water budgets for both lakes. Lake evaporation was found to be about 0.7 cm/day during the study period. Results confirm that the waters sampled at both lake systems and throughout central Khorezm were evaporated from AD water to varying degrees. Together, the water budgets and stable isotope and major ion hydrochemistry data suggest that without surface water input from some source (i.e. excess irrigation water), these and other Khorezm lakes with similar hydrology may decrease in volume dramatically, potentially to the point of complete desiccation.

Development of Highly Repellent Silica Particles for Protection of Hemp Shiv Used as Insulation Materials.

PubMed

Bourebrab, Marion A; Durand, Géraldine G; Taylor, Alan

2017-12-21

New bio-materials have recently gained interest for use in insulation panels in walls, but wider adoption by the building industry is hindered by their intrinsic properties. The fact that such materials are mainly composed of cellulose makes them combustible, and their hydrophilic surface presents a high water uptake, which would lead to faster biodegradation. A hydrophobic treatment with silica particles was successfully synthesised via Stöber process, characterised, and deposited on hemp shiv. The surface of hemp shiv coated several times with 45 and 120 nm particles were uniformly covered, as well as extensively water repellent. Those samples could withstand in humidity chamber without loss of their hydrophobic property and no sign of mould growth after 72 h of exposure.

Development of Highly Repellent Silica Particles for Protection of Hemp Shiv Used as Insulation Materials

PubMed Central

Durand, Géraldine G.

2017-01-01

New bio-materials have recently gained interest for use in insulation panels in walls, but wider adoption by the building industry is hindered by their intrinsic properties. The fact that such materials are mainly composed of cellulose makes them combustible, and their hydrophilic surface presents a high water uptake, which would lead to faster biodegradation. A hydrophobic treatment with silica particles was successfully synthesised via Stöber process, characterised, and deposited on hemp shiv. The surface of hemp shiv coated several times with 45 and 120 nm particles were uniformly covered, as well as extensively water repellent. Those samples could withstand in humidity chamber without loss of their hydrophobic property and no sign of mould growth after 72 h of exposure. PMID:29267195

Airborne Lidar Bathymetry Beam Diagnostics Using an Underwater Optical Detector Array

NASA Astrophysics Data System (ADS)

Birkebak, Matthew

The surface geometry of air-water interface is considered as an important factor affecting the performance of Airborne Lidar Bathymetry (ALB), and laser optical communication through the water surface. ALB is a remote sensing technique that utilizes a pulsed green (532 nm) laser mounted to an airborne platform in order to measure water depth. The water surface (i.e., air-water interface) can distort the light beam's ray-path geometry and add uncertainty to range calculation measurements. Previous studies on light refracting through a complex water surface are heavily dependent on theoretical models and simulations. In addition, only very limited work has been conducted to validate these theoretical models using experiments under well-controlled laboratory conditions. The goal of the study is to establish a clear relationship between water-surface conditions and the uncertainty of ALB measurement. This relationship will be determined by conducting more extensive empirical measurements to characterize the changes in beam slant path associated with a variety of short wavelength wind ripples, typically seen in ALB survey conditions. This study will focus on the effects of capillary and gravity-capillary waves with surface wavelengths smaller than the diameter of the laser beam on the water surface. Simulations using Monte-Carlo techniques of the ALB beam footprints and the environmental conditions were used to analyze the ray-path geometries. Based on the simulation results, laboratory experiments were then designed to test key parameters that have the greatest contribution on beam path and direction through the water. The laser beam dispersion experiments were conducted in well-controlled laboratory setting at the University of New Hampshire's Wave and Tow tank. The spatial elevations of the water surface were independently measured using a high resolution wave staff. The refracted laser beam footprint was measured using an underwater optical detector consisting of a 6x6 array of photodiodes. Image processing techniques were used to estimate the laser's incidence angle intercepted by the detector array. Beam patterns that resulted from intersection between the laser beam light field underwater and the detector array were modeled and used to calculate changes in position and orientation for water surface conditions containing wavelengths less than 0.1m. Finally, a total horizontal uncertainty (THU) model was estimated, which can be implemented in total propagated uncertainty (TPU) models for reporting as a measure of the quality of each measurement. The wave refraction error for various sea states and beam characteristics was successfully quantified using both experimental and analytical techniques.

Modeling large-scale human alteration of land surface hydrology and climate

NASA Astrophysics Data System (ADS)

Pokhrel, Yadu N.; Felfelani, Farshid; Shin, Sanghoon; Yamada, Tomohito J.; Satoh, Yusuke

2017-12-01

Rapidly expanding human activities have profoundly affected various biophysical and biogeochemical processes of the Earth system over a broad range of scales, and freshwater systems are now amongst the most extensively altered ecosystems. In this study, we examine the human-induced changes in land surface water and energy balances and the associated climate impacts using a coupled hydrological-climate model framework which also simulates the impacts of human activities on the water cycle. We present three sets of analyses using the results from two model versions—one with and the other without considering human activities; both versions are run in offline and coupled mode resulting in a series of four experiments in total. First, we examine climate and human-induced changes in regional water balance focusing on the widely debated issue of the desiccation of the Aral Sea in central Asia. Then, we discuss the changes in surface temperature as a result of changes in land surface energy balance due to irrigation over global and regional scales. Finally, we examine the global and regional climate impacts of increased atmospheric water vapor content due to irrigation. Results indicate that the direct anthropogenic alteration of river flow in the Aral Sea basin resulted in the loss of 510 km3 of water during the latter half of the twentieth century which explains about half of the total loss of water from the sea. Results of irrigation-induced changes in surface energy balance suggest a significant surface cooling of up to 3.3 K over 1° grids in highly irrigated areas but a negligible change in land surface temperature when averaged over sufficiently large global regions. Results from the coupled model indicate a substantial change in 2 m air temperature and outgoing longwave radiation due to irrigation, highlighting the non-local (regional and global) implications of irrigation. These results provide important insights on the direct human alteration of land surface water and energy balances, highlighting the need to incorporate human activities such as irrigation into the framework of global climate models and Earth system models for better prediction of future changes under increasing human influence and continuing global climate change.

Refraction of microwave signals by water vapor

NASA Technical Reports Server (NTRS)

Goldfinger, A. D.

1980-01-01

Tropospheric water vapor causes a refractive path length effect which is typically 5-10% of the 'dry' tropospheric effect and as large as several meters at elevation angles below 5 deg. The vertical water vapor profile is quite variable, and measurements of intensive atmospheric parameters such as temperature and humidity limited to the surface do not adequately predict the refractive effect. It is suggested that a water vapor refraction model that is a function of the amount of precipitable water alone can be successful at low elevation angles. From an extensive study of numerical ray tracings through radiosonde balloon data, such a model has been constructed. The model predicts the effect at all latitudes and elevation angles between 2 and 10 deg to an accuracy of better than 4% (11 cm at 3 deg elevation angle).

An extensive phase space for the potential martian biosphere.

PubMed

Jones, Eriita G; Lineweaver, Charles H; Clarke, Jonathan D

2011-12-01

We present a comprehensive model of martian pressure-temperature (P-T) phase space and compare it with that of Earth. Martian P-T conditions compatible with liquid water extend to a depth of ∼310 km. We use our phase space model of Mars and of terrestrial life to estimate the depths and extent of the water on Mars that is habitable for terrestrial life. We find an extensive overlap between inhabited terrestrial phase space and martian phase space. The lower martian surface temperatures and shallower martian geotherm suggest that, if there is a hot deep biosphere on Mars, it could extend 7 times deeper than the ∼5 km depth of the hot deep terrestrial biosphere in the crust inhabited by hyperthermophilic chemolithotrophs. This corresponds to ∼3.2% of the volume of present-day Mars being potentially habitable for terrestrial-like life.

Pathways to dewetting in hydrophobic confinement.

PubMed

Remsing, Richard C; Xi, Erte; Vembanur, Srivathsan; Sharma, Sumit; Debenedetti, Pablo G; Garde, Shekhar; Patel, Amish J

2015-07-07

Liquid water can become metastable with respect to its vapor in hydrophobic confinement. The resulting dewetting transitions are often impeded by large kinetic barriers. According to macroscopic theory, such barriers arise from the free energy required to nucleate a critical vapor tube that spans the region between two hydrophobic surfaces--tubes with smaller radii collapse, whereas larger ones grow to dry the entire confined region. Using extensive molecular simulations of water between two nanoscopic hydrophobic surfaces, in conjunction with advanced sampling techniques, here we show that for intersurface separations that thermodynamically favor dewetting, the barrier to dewetting does not correspond to the formation of a (classical) critical vapor tube. Instead, it corresponds to an abrupt transition from an isolated cavity adjacent to one of the confining surfaces to a gap-spanning vapor tube that is already larger than the critical vapor tube anticipated by macroscopic theory. Correspondingly, the barrier to dewetting is also smaller than the classical expectation. We show that the peculiar nature of water density fluctuations adjacent to extended hydrophobic surfaces--namely, the enhanced likelihood of observing low-density fluctuations relative to Gaussian statistics--facilitates this nonclassical behavior. By stabilizing isolated cavities relative to vapor tubes, enhanced water density fluctuations thus stabilize novel pathways, which circumvent the classical barriers and offer diminished resistance to dewetting. Our results thus suggest a key role for fluctuations in speeding up the kinetics of numerous phenomena ranging from Cassie-Wenzel transitions on superhydrophobic surfaces, to hydrophobically driven biomolecular folding and assembly.

Monitoring and assessment of seasonal land cover changes using remote sensing: a 30-year (1987-2016) case study of Hamoun Wetland, Iran.

PubMed

Kharazmi, Rasoul; Tavili, Ali; Rahdari, Mohammad Reza; Chaban, Lyudmila; Panidi, Evgeny; Rodrigo-Comino, Jesús

2018-05-23

The availability of Landsat data allows improving the monitoring and assessment of large-scale areas with land cover changes in rapid developing regions. Thus, we pretend to show a combined methodology to assess land cover changes (LCCs) in the Hamoun Wetland region (Iran) over a period of 30-year (1987-2016) and to quantify seasonal and decadal landscape and land use variabilities. Using the pixel-based change detection (PBCD) and the post-classification comparison (PCC), four land cover classes were compared among spring, summer, and fall seasons. Our findings showed for the water class a higher correlation between spring and summer (R 2  = 0.94) than fall and spring (R 2  = 0.58) seasons. Before 2000, ~ 50% of the total area was covered by bare soil and 40% by water. However, after 2000, more than 70% of wetland was transformed into bare soils. The results of the long-term monitoring period showed that fall season was the most representative time to show the inter-annual variability of LCCs monitoring and the least affected by seasonal-scale climatic variations. In the Hamoun Wetland region, land cover was highly controlled by changes in surface water, which in turn responded to both climatic and anthropogenic impacts. We were able to divide the water budget monitoring into three different ecological regimes: (1) a period of high water level, which sustained healthy extensive plant life, and approximately 40% of the total surface water was retained until the end of the hydrological year; (2) a period of drought during high evaporation rates was observed, and a mean wetland surface of about 85% was characterized by bare land; and (3) a recovery period in which water levels were overall rising, but they are not maintained from year to year. After a spring flood, in 2006 and 2013, grassland reached the highest extensions, covering till more than 20% of the region, and the dynamics of the ecosystem were affected by the differences in moisture. The Hamoun wetland region served as an important example and demonstration of the feedbacks between land cover and land uses, particularly as pertaining to water resources available to a rapidly expanding population.

Disagreement between Hydrological and Land Surface models on the water budgets in the Arctic: why is this and which of them is right?

NASA Astrophysics Data System (ADS)

Blyth, E.; Martinez-de la Torre, A.; Ellis, R.; Robinson, E.

2017-12-01

The fresh-water budget of the Artic region has a diverse range of impacts: the ecosystems of the region, ocean circulation response to Arctic freshwater, methane emissions through changing wetland extent as well as the available fresh water for human consumption. But there are many processes that control the budget including a seasonal snow packs building and thawing, freezing soils and permafrost, extensive organic soils and large wetland systems. All these processes interact to create a complex hydrological system. In this study we examine a suite of 10 models that bring all those processes together in a 25 year reanalysis of the global water budget. We assess their performance in the Arctic region. There are two approaches to modelling fresh-water flows at large scales, referred to here as `Hydrological' and `Land Surface' models. While both approaches include a physically based model of the water stores and fluxes, the Land Surface models links the water flows to an energy-based model for processes such as snow melt and soil freezing. This study will analyse the impact of that basic difference on the regional patterns of evapotranspiration, runoff generation and terrestrial water storage. For the evapotranspiration, the Hydrological models tend to have a bigger spatial range in the model bias (difference to observations), implying greater errors compared to the Land-Surface models. For instance, some regions such as Eastern Siberia have consistently lower Evaporation in the Hydrological models than the Land Surface models. For the Runoff however, the results are the other way round with a slightly higher spatial range in bias for the Land Surface models implying greater errors than the Hydrological models. A simple analysis would suggest that Hydrological models are designed to get the runoff right, while Land Surface models designed to get the evapotranspiration right. Tracing the source of the difference suggests that the difference comes from the treatment of snow and evapotranspiration. The study reveals that expertise in the role of snow on runoff generation and evapotranspiration in Hydrological and Land Surface could be combined to improve the representation of the fresh water flows in the Arctic in both approaches. Improved observations are essential to make these modelling advances possible.

Untangling the effects of urban development on subsurface storage in Baltimore

NASA Astrophysics Data System (ADS)

Bhaskar, Aditi S.; Welty, Claire; Maxwell, Reed M.; Miller, Andrew J.

2015-02-01

The impact of urban development on surface flow has been studied extensively over the last half century, but effects on groundwater systems are still poorly understood. Previous studies of the influence of urban development on subsurface storage have not revealed any consistent pattern, with results showing increases, decreases, and negligible change in groundwater levels. In this paper, we investigated the effects of four key features that impact subsurface storage in urban landscapes. These include reduced vegetative cover, impervious surface cover, infiltration and inflow (I&I) of groundwater and storm water into wastewater pipes, and other anthropogenic recharge and discharge fluxes including water supply pipe leakage and well and reservoir withdrawals. We applied the integrated groundwater-surface water-land surface model ParFlow.CLM to the Baltimore metropolitan area. We compared the base case (all four features) to simulations in which an individual urban feature was removed. For the Baltimore region, the effect of infiltration of groundwater into wastewater pipes had the greatest effect on subsurface storage (I&I decreased subsurface storage 11.1% relative to precipitation minus evapotranspiration after 1 year), followed by the impact of water supply pipe leakage and lawn irrigation (combined anthropogenic discharges and recharges led to a 7.4% decrease) and reduced vegetation (1.9% increase). Impervious surface cover led to a small increase in subsurface storage (0.56% increase) associated with decreased groundwater discharge as base flow. The change in subsurface storage due to infiltration of groundwater into wastewater pipes was largest despite the smaller spatial extent of surface flux modifications, compared to other features.

Modelling Urban diffuse pollution in groundwater

NASA Astrophysics Data System (ADS)

Jato, Musa; Smith, Martin; Cundy, Andrew

2017-04-01

Diffuse urban pollution of surface and ground waters is a growing concern in many cities and towns. Traffic-derived pollutants such as salts, heavy metals and polycyclic aromatic hydrocarbons (PAHs) may wash off road surfaces in soluble or particulate forms which later drain through soils and drainage systems into surface waters and groundwater. In Brighton, about 90% of drinking water supply comes from groundwater (derived from the Brighton Chalk block). In common with many groundwater sources the Chalk aquifer has been relatively extensively monitored and assessed for diffuse rural contaminants such as nitrate, but knowledge on the extent of contamination from road run-off is currently lacking. This project examines the transfer of traffic-derived contaminants from the road surface to the Chalk aquifer, via urban drainage systems. A transect of five boreholes have been sampled on a monthly basis and groundwater samples analysed to examine the concentrations of key, mainly road run-off derived, hydrocarbon and heavy metal contaminants in groundwater across the Brighton area. Trace concentrations of heavy metals and phenols have been observed in groundwater. Electrical conductivity changes in groundwater have also been used to assess local changes in ionic strength which may be associated with road-derived contaminants. This has been supplemented by systematic water and sediment sampling from urban gully pots, with further sampling planned from drainage and settlement ponds adjacent to major roads, to examine initial road to drainage system transport of major contaminants.

On the contribution of atmospheric moisture to dew formation

NASA Astrophysics Data System (ADS)

Garratt, J. R.; Segal, M.

1988-09-01

The relative contributions of dewfall (a flux of water vapour from air to surface) and distillation (a flux of water vapour from soil to canopy) to dew formation on closed canopy and bare soil surfaces are assessed, and the dependence of dew amount upon wind speed, absolute temperature, atmospheric stability, relative humidity, soil characteristics and cloudiness, all of which are significant factors, is evaluated. Some of these evaluations provide refinements to similar ones given in Monteith (1961). High dewfall rates are usually ≲0.06 mm hr-1 over canopy or bare soil, though upon a canopy under soil-saturated and air-saturated conditions, rates of dew formation may reach 0.07 0.09 mm hr-1 with contributions from distillation. Various sets of observations are reanalyzed to illustrate the importance of the horizontal advection of moisture in the nocturnal boundary layer (NBL) to observed high rates of dew formation arising from the atmospheric contribution of water vapour (dewfall). These locally observed high dewfall rates must be the result of small-scale or mesoscale horizontal advection of moisture in the NBL, since the humidity changes within the typically shallow NBL required to balance the loss of water at the surface are not observed. Over extensive areas of uniform surface (horizontal scales ≫10 km), such continuously high dewfall rates could only be balanced by a local supply of atmospheric moisture since advection of moisture would necessarily be small.

Extent and Depth to Top of Basalt and Interbed Hydrogeologic Units, Yakima River Basin Aquifer System, Washington

USGS Publications Warehouse

Jones, M.A.; Vaccaro, J.J.

2008-01-01

The hydrogeologic framework was delineated for the ground-water flow system of the three basalt formations and two interbeds in the Yakima River Basin, Washington. The basalt units are nearly equivalent to the Saddle Mountains, Wanapum, and Grande Ronde. The two major interbed units between the basalt formations generally are referred to as the Mabton and Vantage. The basalt formations are a productive source of ground-water for the Yakima River Basin. The Grande Ronde unit comprises the largest area in the Yakima River Basin aquifer system. This unit encompasses an area of about 5,390 mi2 and ranges in altitude from 6,900 ft, where it is exposed at land surface, to a depth of 2,800 ft below land surface. The Wanapum unit encompasses an area of 3,450 mi2 and ranges in altitude from 5,680 ft, where exposed at land surface, to a depth of 2,050 ft below land surface. The Saddle Mountains unit, the least extensive, encompasses an area of 2,290 mi2 and ranges from 4,290 ft, where exposed at the surface, to a depth of 1,840 ft below land surface.

Flexible conformable hydrophobized surfaces for turbulent flow drag reduction

NASA Astrophysics Data System (ADS)

Brennan, Joseph C.; Geraldi, Nicasio R.; Morris, Robert H.; Fairhurst, David J.; McHale, Glen; Newton, Michael I.

2015-05-01

In recent years extensive work has been focused onto using superhydrophobic surfaces for drag reduction applications. Superhydrophobic surfaces retain a gas layer, called a plastron, when submerged underwater in the Cassie-Baxter state with water in contact with the tops of surface roughness features. In this state the plastron allows slip to occur across the surface which results in a drag reduction. In this work we report flexible and relatively large area superhydrophobic surfaces produced using two different methods: Large roughness features were created by electrodeposition on copper meshes; Small roughness features were created by embedding carbon nanoparticles (soot) into Polydimethylsiloxane (PDMS). Both samples were made into cylinders with a diameter under 12 mm. To characterize the samples, scanning electron microscope (SEM) images and confocal microscope images were taken. The confocal microscope images were taken with each sample submerged in water to show the extent of the plastron. The hydrophobized electrodeposited copper mesh cylinders showed drag reductions of up to 32% when comparing the superhydrophobic state with a wetted out state. The soot covered cylinders achieved a 30% drag reduction when comparing the superhydrophobic state to a plain cylinder. These results were obtained for turbulent flows with Reynolds numbers 10,000 to 32,500.

Changes in Water Levels and Storage in the High Plains Aquifer, Predevelopment to 2005

USGS Publications Warehouse

McGuire, V.L.

2007-01-01

The High Plains aquifer underlies 111.4 million acres (174,000 square miles) in parts of eight States-Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming. The area overlying the High Plains aquifer is one of the major agricultural regions in the world. Water-level declines began in parts of the High Plains aquifer soon after the beginning of extensive ground-water irrigation. By 1980, water levels in the High Plains aquifer in parts of Texas, Oklahoma, and southwestern Kansas had declined more than 100 feet (Luckey and others, 1981). In response to these water-level declines, the U.S. Geological Survey (USGS), in cooperation with numerous Federal, State, and local water-resources agencies, began monitoring more than 7,000 wells in 1988 to assess annual water-level change in the aquifer. A report by the USGS, 'Water-Level Changes in the High Plains Aquifer, Predevelopment to 2005 and 2003 to 2005' (McGuire, 2007), shows the areas of substantial water-level changes in the aquifer from the time prior to substantial ground-water irrigation development (predevelopment or about 1950) to 2005 (fig. 1). In parts of the area, farmers began using ground water for irrigation extensively in the 1930s and 1940s. Estimated irrigated acreage in the area overlying the High Plains aquifer increased rapidly from 1940 to 1980 and changed slightly from 1980 to 2002: 1949-2.1 million acres, 1980-13.7 million acres, 1997-13.9 million acres, 2002-12.7 million acres. Irrigated acres in 2002 were 12 percent of the aquifer area, not including the areas with little or no saturated thickness (McGuire, 2007). Ground-water withdrawals for irrigation and other uses are compiled and reported by the USGS and agencies in each State about every 5 years. Ground-water withdrawals from the High Plains aquifer for irrigation increased from 4 to 19 million acre-feet from 1949 to 1974. Ground-water withdrawals for irrigation in 1980, 1985, 1990, and 1995 were from 4 to 18 percent less than withdrawals for irrigation in 1974. Ground-water withdrawals from the aquifer for irrigation in 2000 were 21 million acre-feet (McGuire, 2007). Water-level changes in the aquifer result from an imbalance between discharge and recharge. Discharge is primarily ground-water withdrawals for irrigation. Discharge also includes evapotranspiration, where the water table is near the land surface, and seepage to streams and springs, where the water table intersects with the land surface. Recharge is primarily from precipitation. Other sources of recharge are irrigation return flow and seepage from streams, canals, and reservoirs. Water-level declines may result in increased costs for ground-water withdrawals because of increased pumping lift and decreased well yields (Taylor and Alley, 2001). Water-level declines also can affect ground-water availability, surface-water flow, and near-stream (riparian) habitat areas (Alley and others, 1999).

The Sr/Ca-temperature relationship in coralline aragonite: Influence of variability in (Sr/Ca)[sub seawater] and skeletal growth parameters

DOE Office of Scientific and Technical Information (OSTI.GOV)

de Villiers, S.; Shen, G.T.; Nelson, B.K.

1994-01-01

This paper provides an evaluation of two of the most likely pitfalls of Sr/Ca thermometry, i.e., the effect of biogenic cycling of Sr vs. Ca in the surface ocean and the effect of variable extension rate on Sr incorporation in coralline aragonite. The authors also report calibration of the Sr/Ca-temperature relationship for three coral species, Porites lobata, Pocillopora eydouxi, and Pavona clavus, collected for the Hawaiian and Galapagos islands. Analyses of seawater samples show significant spatial and depth variability in the Sr:Ca ratio. The uncertainty introduced by this effect is estimated to be <0.2[degrees]C for corals located in tropical oligotrophicmore » waters, and potentially larger for corals located in upwelling areas. Sr/Ca along two different growth axes of a Galapagos Pavona clavus, with annual extension rates of [approximately]6 and 12 mm/y, respectively, indicate an offset of 1-2[degrees]C, with higher Sr/Ca values associated with slower extension rates. The offset observed between the two growth axes may be the result of variations in extension and/or calcification rate. These results are important in determining past sea surface temperatures for reconstruction of paleoclimates.« less

Observation-well network for collection of ground-water level data in Massachusetts

USGS Publications Warehouse

Socolow, Roy S.

1994-01-01

Aquifers--water-bearing deposits of sand and gravel, glacial till, and fractured bedrock--provide an extensive and readily accessible ground-water supply in Massachusetts. Ground water affects our everyday lives, not just in terms of how much water is available, but also in terms of the position of ground-water levels in relation to land surface. Knowledge of ground-water levels is needed by Federal, State, and local agencies to help plan, manage, and protect ground-water supplies, and by private construction companies for site planning and evaluation. A primary part of the mission of the U.S. Geological Survey (USGS), Water Resources Division, is the systematic collection of ground-water, surface-water, and water-quality data. These data are needed to manage and protect the nation's water resources. The Massachusetts-Rhode Island District of the USGS, in cooperation with the Massachusetts Department of Environmental Management (DEM), Office of Water Resources, and county and town environmental agencies, has maintained a network of observation wells throughout the Commonwealth since the mid 1930's. The purpose of this network is to monitor seasonal and long-term changes in groundwater storage in different lithologic, topographic, and geographic settings. These data are analyzed to provide a monthly index of ground-water conditions to aid in water-resources management and planning, and to define long-term changes in water levels resulting from manmade stresses (such as pumping and construction-site drainage) and natural stresses (such as floods and droughts).

Evaluation of water levels in major aquifers of the New Jersey coastal plain, 1978

USGS Publications Warehouse

Walker, R.L.

1983-01-01

Increased withdrawals from the major artesian aquifers that underlie the New Jersey Coastal Plain have caused water-level declines and large regional cones of depression. These cones of depression are delineated on detailed potentiometric surface maps produced from water-level data collected in the field in 1978. Water levels for 1978 are compared with those from 1970 or 1973, and water-level changes are evaluated and compared with hydrographs from observation wells. The Potomac-Raritan-Magothy aquifer system is divided into regionally extensive lower and upper aquifers. These aquifers have large cones of depression centered in Camden, Middlesex, and Monmouth Counties. Water levels declined 5 to 20 feet in these areas between 1973 and 1978. Deep cones of depression in coastal Monmouth and Ocean Counties in the Englishtown and Wenonah-Mount Laurel aquifers are similar in location and shape, due to a good hydraulic connection between these aquifers. Water levels declined 2 to 31 feet in the Englishtown aquifer and 12 to 26 feet in the Wenonah-Mount Laurel aquifer between 1973 and 1978. Water levels in the Atlantic City 800-foot sand of the Kirkwood Formation define an extensive elongated cone of depression centered near Margate, Atlantic County. Head changes ranged from a decline of 4 feet to a recovery of 9 feet during 1970-78. The lowest heads in the Cohansey Sand were about 26 feet below sea level at Cape May, Cape May County, and less than 0.5 miles from salty ground water. (USGS)

Concentration of arsenic in water, sediments and fish species from naturally contaminated rivers.

PubMed

Rosso, Juan José; Schenone, Nahuel F; Pérez Carrera, Alejo; Fernández Cirelli, Alicia

2013-04-01

Arsenic (As) may occur in surface freshwater ecosystems as a consequence of both natural contamination and anthropogenic activities. In this paper, As concentrations in muscle samples of 10 fish species, sediments and surface water from three naturally contaminated rivers in a central region of Argentina are reported. The study area is one of the largest regions in the world with high As concentrations in groundwater. However, information of As in freshwater ecosystems and associated biota is scarce. An extensive spatial variability of As concentrations in water and sediments of sampled ecosystems was observed. Geochemical indices indicated that sediments ranged from mostly unpolluted to strongly polluted. The concentration of As in sediments averaged 6.58 μg/g ranging from 0.23 to 59.53 μg/g. Arsenic in sediments barely followed (r = 0.361; p = 0.118) the level of contamination of water. All rivers showed high concentrations of As in surface waters, ranging from 55 to 195 μg/L. The average concentration of As in fish was 1.76 μg/g. The level of contamination with As differed significantly between species. Moreover, the level of bioaccumulation of As in fish species related to the concentration of As in water and sediments also differed between species. Whilst some fish species seemed to be able to regulate the uptake of this metalloid, the concentration of As in the large catfish Rhamdia quelen mostly followed the concentration of As in abiotic compartments. The erratic pattern of As concentrations in fish and sediments regardless of the invariable high levels in surface waters suggests the existence of complex biogeochemical processes behind the distribution patterns of As in these naturally contaminated ecosystems.

Surface electrostatic immobilization of thin layers of water on silver halide. Experimental and calculated infrared spectrum of cyclic trimer of water and a ponderal isotope effect.

PubMed

Kosower, Edward M; Markovich, Gil; Borz, Galina

2012-09-18

Evaporation of water on a planar AgX surface leads to a strongly bound monolayer for which IR spectra display the marker peaks for modest numbers of oligomers. From 700-1800 spectra for each isotopomer, H(2)O(16) and H(2)O(18), a pair was selected with moderate intensity at 1616 cm(-1) (a peak reported for the cyclic trimer of water) from the monolayer portion of the experiment. Every selected spectrum had lesser peaks for other oligomers. The sum of a spectroscopic pair reveals the vibrational spectra of the cyclic trimers of H(2)O(16) and H(2)O(18). All fundamentals in the mid-IR are seen including the bending, OH stretching, and intramolecular H-bonding regions, the last never previously recognized. The relative prevalence of cyclic trimer can be attributed to the "low" water concentration on the surface. In addition, a ponderal effect leads to higher concentrations of cyclic trimer in the H(2)O(18) spectra than in the H(2)O(16) spectra and allows observation of combination bands in the H(2)O(18) spectra, representing a new type of isotope effect. The spectroscopic results for the two water isotopomers are much more extensive than those obtained through matrix isolation. Remarkably complete spectra of the cyclic trimer are obtained for the first time, especially for H(2)O(18). DFT calculations with the cyclic trimer on a simplified model for the AgCl surface yield spectra consistent with the experimental spectrum. The technique can be extended to other oligomers of water and many other OH compounds.

Occurrence, fate and effects of Di (2-ethylhexyl) Phthalate in wastewater treatment plants: a review.

PubMed

Zolfaghari, M; Drogui, P; Seyhi, B; Brar, S K; Buelna, G; Dubé, R

2014-11-01

Phthalates, such as Di (2-ethylhexyl) Phthalate (DEHP) are compounds extensively used as plasticizer for long time around the world. Due to the extensive usage, DEHP is found in many surface waters (0.013-18.5 μg/L), wastewaters (0.716-122 μg/L), landfill leachate (88-460 μg/L), sludge (12-1250 mg/kg), soil (2-10 mg/kg). DEHP is persistent in the environment and the toxicity of the byproducts resulting from the degradation of DEHP sometime exacerbates the parent compound toxicity. Water/Wastewater treatment processes might play a key role in delivering safe, reliable supplies of water to households, industry and in safeguarding the quality of water in rivers, lakes and aquifers. This review addresses state of knowledge concerning the worldwide production, occurrence, fate and effects of DEHP in the environment. Moreover, the fate and behavior of DEHP in various treatment processes, including biological, physicochemical and advanced processes are reviewed and comparison (qualitative and quantitative) has been done between the processes. The trends and perspectives for treatment of wastewaters contaminated by DEHP are also analyzed in this review. Copyright © 2014 Elsevier Ltd. All rights reserved.

Groundwater quality and water-well characteristics in the Kickapoo Tribe of Oklahoma Jurisdictional Area, central Oklahoma, 1948--2011

USGS Publications Warehouse

Becker, Carol J.

2013-01-01

In 2012, the U.S. Geological Survey, in cooperation with the Kickapoo Tribe of Oklahoma, compiled historical groundwater-quality data collected from 1948 to 2011 and water-well completion information in parts of Lincoln, Oklahoma, and Pottawatomie Counties in central Oklahoma to support the development of a comprehensive water-management plan for the Tribe’s jurisdictional area. In this study, water-quality data from 155 water wells, collected from 1948 to 2011, were retrieved from the U.S. Geological Survey National Water Information System database; these data include measurements of pH, specific conductance, and hardness and concentrations of the major ions, trace elements, and radionuclides that have Maximum Contaminant Levels or Secondary Maximum Contaminant Levels in public drinking-water supplies. Information about well characteristics includes ranges of well yield and well depth of private water wells in the study area and was compiled from the Oklahoma Water Resources Board Multi-Purpose Well Completion Report database. This report also shows depth to water from land surface by using shaded 30-foot contours that were created by using a geographic information system and spatial layers of a 2009 potentiometric surface (groundwater elevation) and land-surface elevation. Wells in the study area produce water from the North Canadian River alluvial and terrace aquifers, the underlying Garber Sandstone and Wellington Formation that compose the Garber–Wellington aquifer, and the Chase, Council Grove, and Admire Groups. Water quality varies substantially between the alluvial and terrace aquifers and bedrock aquifers in the study area. Water from the alluvial aquifer has relatively high concentrations of dissolved solids and generally is used for livestock only, whereas water from the terrace aquifer has low concentrations of dissolved solids and is used extensively by households in the study area. Water from the bedrock aquifer also is used extensively by households but may have high concentrations of trace elements, including uranium, in some areas where groundwater pH is above 8.0. Well yields vary and are dependent on aquifer characteristics and well-completion practices. Well yields in the unconsolidated alluvial and terrace aquifers generally are higher than yields from bedrock aquifers but are limited by the thickness and extent of these river deposits. Well yields in the alluvium and terrace aquifers commonly range from 50 to 150 gallons per minute and may exceed 300 gallons per minute, whereas well yields in the bedrock aquifers commonly range from 25 to 50 gallons per minute in the western one-third of study area (Oklahoma County) and generally less than 25 gallons per minute in the eastern two-thirds of the study area (Lincoln and Pottawatomie Counties).

On the Complexity of Nutrient Transport in a Large Watershed in Ohio

NASA Astrophysics Data System (ADS)

Schwartz, F. W.; Allen, G.

2009-12-01

This paper examines key features of the hydrobiologic setting in controlling the cycling of nutrients through the major streams and rivers of a large agriculturally dominated watershed in central Ohio. The particular focus is on the roles of extreme rainfall events in generating nutrients, and role of reservoirs in attenuating nutrient concentrations. The study also highlights major gaps in process knowledge even in the face in the face of extensive regulatory and other monitoring. Although it has been recognized that reservoirs can significantly affect surface-water flows in watersheds, there is a growing recognition of the need for expanded and complementary studies to understand their role in nutrient transport. The study area is located in central Ohio and includes the entire Upper Scioto and the northern portion of the Lower Scioto River basins, an area encompassing approximately 9984 km2. Five of the sub-watersheds contain major surface-water storage reservoirs. Two watersheds are without reservoirs. There is intensive agriculture within the study area with corn and soybeans as the dominant crops. Tile drainage of fields provides an efficient and rapid connection of agricultural lands to surface waters, facilitating the loading of fertilizers and agrochemicals to surface streams. Storm flows in spring months that coincide with fertilizer applications often provide nitrate concentrations in excess of 10 mg/L as N. In spite of years of routine sampling for regulatory purposes, little is known about nutrient loading patterns during the few, brief, extreme events each year. Interpretations of a high resolution temporal chemical record of sampling on the Scioto River is frustrated by the complexity of loading and mixing as tributaries from sub-watersheds join the main stem of the Scioto River and nutrient utilization within the large reservoirs. Even with literally thousands of individual chemical measurements, extensive stream and precipitation data, the details of processes affecting nutrient transport remain uncertain.

UHE Cosmic Ray Observations Using the Cygnus Water - Array

NASA Astrophysics Data System (ADS)

Dion, Cynthia L.

1995-01-01

The CYGNUS water-Cerenkov array, consisting of five surface water-Cerenkov detectors, was built in the CYGNUS extensive air shower array at Los Alamos, New Mexico (latitude 36^circ N, longitude 107^circ W, altitude 2310 meters) to search for point sources of ultra-high energy particles (>1014 eV per particle) with the CYGNUS extensive air shower array. The water-Cerenkov detectors are used to improve the angular resolution of the extensive air shower array. This experiment searches for point sources of UHE gamma-radiation that may be of galactic or extra-galactic origin. The data set from December 1991 to January 1994 consists of data from both the water-Cerenkov array and the CYGNUS extensive air shower array. These data are combined, and the angular resolution of this combined data set is measured to be 0.34^circ+0.03 ^circ-0.04^circ. The measurement is made by observing the cosmic-ray shadowing of the Sun and the Moon. Using a subset of these data, three potential sources of UHE emission are studied: the Crab Pulsar, and the active galactic nuclei Markarian 421 and Markarian 501. A search is conducted for continuous emission from these three sources, and emission over shorter time scales. This experiment is particularly sensitive to emission over these shorter time scales. There is no evidence of UHE emission from these three sources over any time scales studied, and upper bounds to the flux of gamma radiation are determined. The flux upper limit for continuous emission from the Crab Pulsar is found to be 1.2times10^ {-13}/rm cm^2/s above 70 TeV. The flux upper limit for continuous emission from Markarian 421 is found to be 1.3times10^ {-13}/rm cm^2/s above 50 TeV. The flux upper limit for continuous emission from Markarian 501 is found to be 3.8times10^ {-13}/rm cm^2/s above 50 TeV.

Wind-driven currents in a shallow lake or sea

NASA Technical Reports Server (NTRS)

Goldstein, M. E.; Gedney, R. T.

1971-01-01

For shallow lakes and seas such as the great lakes (especially Lake Erie) where the depth is not much greater than the Ekman depth, the usual Ekman dynamics cannot be used to predict the wind driven currents. The necessary extension to include shallow bodies of water, given by Welander, leads to a partial differential equation for the surface displacement which in turn determines all other flow quantities. A technique for obtaining exact analytical solutions to Welander's equation for bodies of water with large class of bottom topographies which may or may not contain islands is given. It involves applying conformal mapping methods to an extension of Welander's equation into the complex plane. When the wind stress is constant (which is the usual assumption for lakes) the method leads to general solutions which hold for bodies of water of arbitrary shape (the shape appears in the solutions through a set of constants which are the coefficients in the Laurent expansion of a mapping of the particular lake geometry). The method is applied to an elliptically shaped lake and a circular lake containing an eccentrically located circular island.

Objectives and Capabilities of the Deep Space 2 (DS2) Evolved Water Experiment

NASA Astrophysics Data System (ADS)

Yen, A. S.; Murray, B.; Zent, A. P.

1999-09-01

The New Millennium Deep Space 2 (DS2) Mars Microprobes will impact the surface of Mars at a latitude of approximately 75 degrees South on December 3, 1999. The primary objective of this mission is to demonstrate penetrator technologies for future scientific applications. Nonetheless, measurements will be obtained with the goal of characterizing the atmospheric structure during entry as well as the penetrability, thermal conductivity, and water ice content of the polar layered terrains. In addition to demonstrating the ability to collect a subsurface sample, the evolved water experiment will test models of the south polar regions which indicate that water ice is stable at depths of 4 to 20 cm and greater [Paige and Keegan, 1994]. This prediction for the presence of ice is in contrast to atmospheric circulation models which suggest that water is irreversibly lost from southern latitudes and that the only extensive, permanent ice deposits are located in the northern hemisphere [Houben et al., 1997]. Furthermore, MOC images from the 1998 aerobraking phase suggest a rougher and perhaps more devolatilized surface than inferred from Viking and Mariner 9 data. Thus, the direct determination of the presence or absence of near-surface ice by the DS2 probes is important in the resolution of the fundamental questions about Mars regarding the global inventory of water and the climate history. In pursuit of these objectives, a 160 milliliter soil sample will be actively collected by a miniature drill and analyzed for water ice both thermally and spectroscopically. Specific capabilities and detection limits for the abundance of water ice will be presented at the meeting.

Improved representations of coupled soil–canopy processes in the CABLE land surface model (Subversion revision 3432)

DOE PAGES

Haverd, Vanessa; Cuntz, Matthias; Nieradzik, Lars P.; ...

2016-09-07

CABLE is a global land surface model, which has been used extensively in offline and coupled simulations. While CABLE performs well in comparison with other land surface models, results are impacted by decoupling of transpiration and photosynthesis fluxes under drying soil conditions, often leading to implausibly high water use efficiencies. Here, we present a solution to this problem, ensuring that modelled transpiration is always consistent with modelled photosynthesis, while introducing a parsimonious single-parameter drought response function which is coupled to root water uptake. We further improve CABLE's simulation of coupled soil–canopy processes by introducing an alternative hydrology model with amore » physically accurate representation of coupled energy and water fluxes at the soil–air interface, including a more realistic formulation of transfer under atmospherically stable conditions within the canopy and in the presence of leaf litter. The effects of these model developments are assessed using data from 18 stations from the global eddy covariance FLUXNET database, selected to span a large climatic range. Here, marked improvements are demonstrated, with root mean squared errors for monthly latent heat fluxes and water use efficiencies being reduced by 40 %. Results highlight the important roles of deep soil moisture in mediating drought response and litter in dampening soil evaporation.« less

Assessing the Benefits Provided by SWOT Data Towards Estimating Reservoir Residence Time in the Mekong River Basin

NASA Astrophysics Data System (ADS)

Bonnema, M.; Hossain, F.

2016-12-01

The Mekong River Basin is undergoing rapid hydropower development. Nine dams are planned on the main stem of the Mekong and many more on its extensive tributaries. Understanding the effects that current and future dams have on the river system and water cycle as a whole is vital for the millions of people living in the basin. reservoir residence time, the amount of time water spends stored in a reservoir, is a key parameter in investigating these impacts. The forthcoming Surface Water and Ocean Topography (SWOT) mission is poised to provide an unprecedented amount of surface water observations. SWOT, when augmented by current satellite missions, will provide the necessary information to estimate the residence time of reservoirs across the entire basin in a more comprehensive way than ever before. In this study, we first combine observations from current satellite missions (altimetry, spectral imaging, precipitation) to estimate the residence times of existing reservoirs. We then use this information to project how future reservoirs will increase the residence time of the river system. Next, we explore how SWOT observations can be used to improve residence time estimation by examining the accuracy of reservoir surface area and elevation observations as well as the accuracy of river discharge observations.

Improved representations of coupled soil–canopy processes in the CABLE land surface model (Subversion revision 3432)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haverd, Vanessa; Cuntz, Matthias; Nieradzik, Lars P.

CABLE is a global land surface model, which has been used extensively in offline and coupled simulations. While CABLE performs well in comparison with other land surface models, results are impacted by decoupling of transpiration and photosynthesis fluxes under drying soil conditions, often leading to implausibly high water use efficiencies. Here, we present a solution to this problem, ensuring that modelled transpiration is always consistent with modelled photosynthesis, while introducing a parsimonious single-parameter drought response function which is coupled to root water uptake. We further improve CABLE's simulation of coupled soil–canopy processes by introducing an alternative hydrology model with amore » physically accurate representation of coupled energy and water fluxes at the soil–air interface, including a more realistic formulation of transfer under atmospherically stable conditions within the canopy and in the presence of leaf litter. The effects of these model developments are assessed using data from 18 stations from the global eddy covariance FLUXNET database, selected to span a large climatic range. Here, marked improvements are demonstrated, with root mean squared errors for monthly latent heat fluxes and water use efficiencies being reduced by 40 %. Results highlight the important roles of deep soil moisture in mediating drought response and litter in dampening soil evaporation.« less

Improved representations of coupled soil-canopy processes in the CABLE land surface model (Subversion revision 3432)

NASA Astrophysics Data System (ADS)

Haverd, Vanessa; Cuntz, Matthias; Nieradzik, Lars P.; Harman, Ian N.

2016-09-01

CABLE is a global land surface model, which has been used extensively in offline and coupled simulations. While CABLE performs well in comparison with other land surface models, results are impacted by decoupling of transpiration and photosynthesis fluxes under drying soil conditions, often leading to implausibly high water use efficiencies. Here, we present a solution to this problem, ensuring that modelled transpiration is always consistent with modelled photosynthesis, while introducing a parsimonious single-parameter drought response function which is coupled to root water uptake. We further improve CABLE's simulation of coupled soil-canopy processes by introducing an alternative hydrology model with a physically accurate representation of coupled energy and water fluxes at the soil-air interface, including a more realistic formulation of transfer under atmospherically stable conditions within the canopy and in the presence of leaf litter. The effects of these model developments are assessed using data from 18 stations from the global eddy covariance FLUXNET database, selected to span a large climatic range. Marked improvements are demonstrated, with root mean squared errors for monthly latent heat fluxes and water use efficiencies being reduced by 40 %. Results highlight the important roles of deep soil moisture in mediating drought response and litter in dampening soil evaporation.

[Simultaneous determination of sixteen perfluorinated organic compounds in surface water by solid phase extraction and ultra performance liquid chromatography with electrospray ionization tandem mass spectrometry].

PubMed

Zhang, Ming; Tang, Fangliang; Yu, Yayun; Chen, Feng; Xu, Jianfen; Ye, Yonggen

2014-05-01

A high-throughput detection method has been developed for the determination of sixteen perfluorinated organic compounds (PFCs) in surface water by solid phase extraction-ultra performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (SPE-UPLC-ESI-MS/MS). The water samples were concentrated and purified through WAX solid phase extraction cartridges. The UPLC separation was performed on an ACQUITY UPLC BEH C18 column utilizing a gradient elution program of methanol (containing 2 mmol/L ammonium acetate) and water (containing 2 mmol/L ammonium acetate) as the mobile phases at a flow rate of 0.4 mL/min. The MS/MS detection was performed under negative electrospray ionization ( ESI ) in multiple reaction monitoring (MRM) mode. Good linearities were observed in the range of 0.5-100 gg/L or 1.0 - 100 microg/L with correlation coefficients from 0.998 7 to 0.999 9. The limits of detection (LODs) for the sixteen perfluorinated organic compounds were in the range of 0.06-0.46 ng/L. The recoveries ranged from 67.6% to 103% with the relative standard deviations between 2.94% and 12.0%. This method was characterized by high sensitivity and precision, extensive range and high speed, and can be applied for the analysis of PFC contaminants in surface water.

Soil Moisture and Vegetation Effects on GPS Reflectivity From Land

NASA Astrophysics Data System (ADS)

Torres, O.; Grant, M. S.; Bosch, D.

2004-12-01

While originally designed as a navigation system, the GPS signal has been used to achieve a number of useful scientific measurements. One of these measurements utilizes the reflection of the GPS signal from land to determine soil moisture. The study of GPS reflections is based on a bistatic configuration that utilizes forward reflection from the surface. The strength of the GPS signal varies in proportion to surface parameters such as soil moisture, soil type, vegetation cover, and topography. This paper focuses on the effects of soil water content and vegetation cover on the surface based around a reflectivity. A two-part method for calibrating the GPS reflectivity was developed that permits the comparison of the data with surface parameters. The first part of the method relieves the direct signal from any multipath effects, the second part is an over-water calibration that yields a reflectivity independent of the transmitting satellite. The sensitivity of the GPS signal to water in the soil is shown by presenting the increase in reflectivity after rain as compared to before rain. The effect of vegetation on the reflected signal is also presented by the inclusion of leaf area index as a fading parameter in the reflected signal from corn and soy bean fields. The results are compared to extensive surface measurements made as part of the Soil Moisture Experiment 2002 (SMEX 2002) in Iowa and SMEX 2003 in Georgia.

Hydraulic "fracking": are surface water impacts an ecological concern?

PubMed

Burton, G Allen; Basu, Niladri; Ellis, Brian R; Kapo, Katherine E; Entrekin, Sally; Nadelhoffer, Knute

2014-08-01

Use of high-volume hydraulic fracturing (HVHF) in unconventional reservoirs to recover previously inaccessible oil and natural gas is rapidly expanding in North America and elsewhere. Although hydraulic fracturing has been practiced for decades, the advent of more technologically advanced horizontal drilling coupled with improved slickwater chemical formulations has allowed extensive natural gas and oil deposits to be recovered from shale formations. Millions of liters of local groundwaters are utilized to generate extensive fracture networks within these low-permeability reservoirs, allowing extraction of the trapped hydrocarbons. Although the technology is relatively standardized, the geographies and related policies and regulations guiding these operations vary markedly. Some ecosystems are more at risk from these operations than others because of either their sensitivities or the manner in which the HVHF operations are conducted. Generally, the closer geographical proximity of the susceptible ecosystem to a drilling site or a location of related industrial processes, the higher the risk of that ecosystem being impacted by the operation. The associated construction of roads, power grids, pipelines, well pads, and water-extraction systems along with increased truck traffic are common to virtually all HVHF operations. These operations may result in increased erosion and sedimentation, increased risk to aquatic ecosystems from chemical spills or runoff, habitat fragmentation, loss of stream riparian zones, altered biogeochemical cycling, and reduction of available surface and hyporheic water volumes because of withdrawal-induced lowering of local groundwater levels. The potential risks to surface waters from HVHF operations are similar in many ways to those resulting from agriculture, silviculture, mining, and urban development. Indeed, groundwater extraction associated with agriculture is perhaps a larger concern in the long term in some regions. Understanding the ecological impacts of these anthropogenic activities provides useful information for evaluations of potential HVHF hazards. Geographic information system-based modeling combined with strategic site monitoring has provided insights into the relative importance of these and other ecoregion and land-use factors in discerning potential HVHF impacts. Recent findings suggest that proper siting and operational controls along with strategic monitoring can reduce the potential for risks to aquatic ecosystems. Nevertheless, inadequate data exist to predict ecological risk at this time. The authors suggest considering the plausibility of surface water hazards associated with the various HVHF operations in terms of the ecological context and in the context of relevant anthropogenic activities. © 2014 SETAC.

Providing the physical basis of SCS curve number method and its proportionality relationship from Richards' equation

NASA Astrophysics Data System (ADS)

Hooshyar, M.; Wang, D.

2016-12-01

The empirical proportionality relationship, which indicates that the ratio of cumulative surface runoff and infiltration to their corresponding potentials are equal, is the basis of the extensively used Soil Conservation Service Curve Number (SCS-CN) method. The objective of this paper is to provide the physical basis of the SCS-CN method and its proportionality hypothesis from the infiltration excess runoff generation perspective. To achieve this purpose, an analytical solution of Richards' equation is derived for ponded infiltration in shallow water table environment under the following boundary conditions: 1) the soil is saturated at the land surface; and 2) there is a no-flux boundary which moves downward. The solution is established based on the assumptions of negligible gravitational effect, constant soil water diffusivity, and hydrostatic soil moisture profile between the no-flux boundary and water table. Based on the derived analytical solution, the proportionality hypothesis is a reasonable approximation for rainfall partitioning at the early stage of ponded infiltration in areas with a shallow water table for coarse textured soils.

An analytical solution of Richards' equation providing the physical basis of SCS curve number method and its proportionality relationship

NASA Astrophysics Data System (ADS)

Hooshyar, Milad; Wang, Dingbao

2016-08-01

The empirical proportionality relationship, which indicates that the ratio of cumulative surface runoff and infiltration to their corresponding potentials are equal, is the basis of the extensively used Soil Conservation Service Curve Number (SCS-CN) method. The objective of this paper is to provide the physical basis of the SCS-CN method and its proportionality hypothesis from the infiltration excess runoff generation perspective. To achieve this purpose, an analytical solution of Richards' equation is derived for ponded infiltration in shallow water table environment under the following boundary conditions: (1) the soil is saturated at the land surface; and (2) there is a no-flux boundary which moves downward. The solution is established based on the assumptions of negligible gravitational effect, constant soil water diffusivity, and hydrostatic soil moisture profile between the no-flux boundary and water table. Based on the derived analytical solution, the proportionality hypothesis is a reasonable approximation for rainfall partitioning at the early stage of ponded infiltration in areas with a shallow water table for coarse textured soils.

Investigation of the Martian environment by infrared spectroscopy on Mariner 9

NASA Technical Reports Server (NTRS)

Conrath, H. R.; Conrath, B. J.; Novis, W.; Kunde, V. G.; Lowman, P.; Maguire, W.; Pearl, J. C.; Pirraglia, J.; Prabhakara, C.; Schlachman, B.

1972-01-01

Measurements obtained during and after the planet-wide dust storm indicate that large diurnal variations in atmospheric temperature existed up to at least 30 km; winds inferred from the temperature fields show a strong tidal component and significant ageostrophic behavior. With the dissipation of the dust, the daily maximum in the atmospheric temperature field moved from approximately latitude -60 and late afternoon local time to near the subsolar point in latitude and time. Analysis of spectral features due to the atmospheric dust indicates as SIO2 content of 60 ? 10%, implying that substantial geochemical differentiation has occurred. Water vapor estimates indicate abundances of 10 to 20 precipitable micrometers. Between November 1971 and April 1972 no gross latitudinal or temporal dependence in the water vapor distribution was detected from the south polar region to the equator. Water vapor was not detected over the north polar regions. Surface pressure mapping was carried out from which topographic relief of nearly two pressure scale heights is inferred. Extensive regions were found where the surface pressure exceeds the triple point pressure of water.

Indicators of streamflow alteration, habitat fragmentation, impervious cover, and water quality for Massachusetts stream basins

USGS Publications Warehouse

Weiskel, Peter K.; Brandt, Sara L.; DeSimone, Leslie A.; Ostiguy, Lance J.; Archfield, Stacey A.

2010-01-01

Massachusetts streams and stream basins have been subjected to a wide variety of human alterations since colonial times. These alterations include water withdrawals, treated wastewater discharges, construction of onsite septic systems and dams, forest clearing, and urbanization—all of which have the potential to affect streamflow regimes, water quality, and habitat integrity for fish and other aquatic biota. Indicators were developed to characterize these types of potential alteration for subbasins and groundwater contributing areas in Massachusetts. The potential alteration of streamflow by the combined effects of withdrawals and discharges was assessed under two water-use scenarios. Water-use scenario 1 incorporated publicly reported groundwater withdrawals and discharges, direct withdrawals from and discharges to streams, and estimated domestic-well withdrawals and septic-system discharges. Surface-water-reservoir withdrawals were excluded from this scenario. Water-use scenario 2 incorporated all the types of withdrawal and discharge included in scenario 1 as well as withdrawals from surface-water reservoirs—all on a long-term, mean annual basis. All withdrawal and discharge data were previously reported to the State for the 2000–2004 period, except domestic-well withdrawals and septic-system discharges, which were estimated for this study. The majority of the state’s subbasins and groundwater contributing areas were estimated to have relatively minor (less than 10 percent) alteration of streamflow under water-use scenario 1 (seasonally varying water use; no surface-water-reservoir withdrawals). However, about 12 percent of subbasins and groundwater contributing areas were estimated to have extensive alteration of streamflows (greater than 40 percent) in August; most of these basins were concentrated in the outer metropolitan Boston region. Potential surcharging of streamflow in August was most commonly indicated for main-stem river subbasins, although surcharging was also indicated for some smaller tributary subbasins. In the high-flow month of April, only 4.8 percent of subbasins and groundwater contributing areas had more than 10 percent potential flow alteration. A majority of the state’s subbasins and groundwater contributing areas were also indicated to have relatively minor alteration of streamflow under water-use scenario 2 (long-term average water use, including surface-water-reservoir withdrawals). Extensive alteration of mean annual flows was estimated for about 6 percent of the state’s subbasins and groundwater contributing areas. The majority of subbasins estimated to have extensive long-term flow alteration contained reservoirs that were specifically designed, constructed, and managed to supply drinking water to cities. Only a small number of subbasins and groundwater contributing areas (1 percent) were extensively surcharged on a long-term, mean annual basis. Because site-specific data concerning surface-water-reservoir storage dynamics and management practices are not available statewide, the seasonal effects of surface-water-reservoir withdrawals on downstream flows could not be assessed in this study. The impounded storage ratio (volume of impounded subbasin or groundwater-contributing-area storage divided by mean annual predevelopment outflow from the subbasin or contributing area, in units of days) indicates the potential for alteration of streamflow, sediment-transport, and temperature regimes by dams, independent of water use. Storage ratios were less than 1 day for 33 percent of the subbasins and groundwater contributing areas, greater than 1 month for about 40 percent of the cases, and greater than 1 year for 3.2 percent of the cases statewide. Dam density, an indicator of stream-habitat fragmentation by dams, averaged 1 dam for every 6.7 stream miles statewide. Many of these dams are not presently (2009) being managed. The highest dam densities were in portions of Worcester County and in the Plymouth-Carver region, respectively, reflecting the historical reliance of Massachusetts industry upon water power and agricultural water-management practices in southeastern Massachusetts. Impervious cover is a frequently used indicator of urban land use. About 33 percent of the state’s 1,429 subbasins and groundwater contributing areas are relatively undeveloped at the local scale, with a local impervious cover of less than 4 percent. About 18 percent of Massachusetts subbasins and contributing areas are highly developed, with a local impervious cover greater than 16 percent. The remaining 49 percent of subbasins and contributing areas have levels of urban development between these extremes (4 to 16 percent local impervious cover). Cumulative impervious cover, defined for the entire upstream area encompassed by each subbasin, shows a smaller range (0 to 55 percent) than local impervious cover. Both local and cumulative impervious cover were highest in metropolitan Boston and other urban centers. High elevated impervious-cover values were also found along major transportation corridors. The water-quality status of Massachusetts streams is assessed periodically by the Massachusetts Department of Environmental Protection pursuant to the requirements of the Federal Clean Water Act. Streams selected for assessment are commonly located in larger subbasins where some degree of impairment is expected. In the 72 percent of the state’s subbasins and groundwater contributing areas with assessed streams in 2002, more than 50 percent of the assessed stream miles were considered impaired. All of the assessed stream miles were considered impaired in 66 percent of the subbasins and groundwater contributing areas with assessed streams. Large streams, such as the main stems of rivers that make up most of the assessed stream miles, also are in many cases the receiving waters for treated wastewater discharges and for this reason may be more susceptible to water-quality impairments than smaller streams. Subbasins and contributing areas with large fractions of assessed stream miles that are listed as impaired are distributed across the state, but are more prevalent in eastern Massachusetts.

Chapter A6. Section 6.7. Turbidity

USGS Publications Warehouse

Anderson, Chauncey W.

2005-01-01

Turbidity is one of the indicators used to assess the environmental health of water bodies. Turbidity is caused by the presence of suspended and dissolved matter, such as clay, silt, finely divided organic matter, plankton and other microscopic organisms, organic acids, and dyes. This section of the National Field Manual (NFM) describes the USGS protocols for determining turbidity in surface and ground waters, including extensive guidance for equipment selection and data reporting. It includes the revised approach to turbidity measurement and reporting that was implemented by the U.S. Geological Survey (USGS) in October 2004 to account for technological advances and consequent measurement complexities.

Cryovolcanic features on Titan's surface as revealed by the Cassini Titan Radar Mapper

USGS Publications Warehouse

Lopes, R.M.C.; Mitchell, K.L.; Stofan, E.R.; Lunine, J.I.; Lorenz, R.; Paganelli, F.; Kirk, R.L.; Wood, C.A.; Wall, S.D.; Robshaw, L.E.; Fortes, A.D.; Neish, Catherine D.; Radebaugh, J.; Reffet, E.; Ostro, S.J.; Elachi, C.; Allison, M.D.; Anderson, Y.; Boehmer, R.; Boubin, G.; Callahan, P.; Encrenaz, P.; Flamini, E.; Francescetti, G.; Gim, Y.; Hamilton, G.; Hensley, S.; Janssen, M.A.; Johnson, W.T.K.; Kelleher, K.; Muhleman, D.O.; Ori, G.; Orosei, R.; Picardi, G.; Posa, F.; Roth, L.E.; Seu, R.; Shaffer, S.; Soderblom, L.A.; Stiles, B.; Vetrella, S.; West, R.D.; Wye, L.; Zebker, H.A.

2007-01-01

The Cassini Titan Radar Mapper obtained Synthetic Aperture Radar images of Titan's surface during four fly-bys during the mission's first year. These images show that Titan's surface is very complex geologically, showing evidence of major planetary geologic processes, including cryovolcanism. This paper discusses the variety of cryovolcanic features identified from SAR images, their possible origin, and their geologic context. The features which we identify as cryovolcanic in origin include a large (180 km diameter) volcanic construct (dome or shield), several extensive flows, and three calderas which appear to be the source of flows. The composition of the cryomagma on Titan is still unknown, but constraints on rheological properties can be estimated using flow thickness. Rheological properties of one flow were estimated and appear inconsistent with ammonia-water slurries, and possibly more consistent with ammonia-water-methanol slurries. The extent of cryovolcanism on Titan is still not known, as only a small fraction of the surface has been imaged at sufficient resolution. Energetic considerations suggest that cryovolcanism may have been a dominant process in the resurfacing of Titan. ?? 2006 Elsevier Inc.

Modeling the surface evapotranspiration over the southern Great Plains

NASA Technical Reports Server (NTRS)

Liljegren, J. C.; Doran, J. C.; Hubbe, J. M.; Shaw, W. J.; Zhong, S.; Collatz, G. J.; Cook, D. R.; Hart, R. L.

1996-01-01

We have developed a method to apply the Simple Biosphere Model of Sellers et al to calculate the surface fluxes of sensible heat and water vapor at high spatial resolution over the domain of the US DOE's Cloud and Radiation Testbed (CART) in Kansas and Oklahoma. The CART, which is within the GCIP area of interest for the Mississippi River Basin, is an extensively instrumented facility operated as part of the DOE's Atmospheric Radiation Measurement (ARM) program. Flux values calculated with our method will be used to provide lower boundary conditions for numerical models to study the atmosphere over the CART domain.

Fluids and their Effect on Measurements on Lunar Soil Particle size Distribution

NASA Technical Reports Server (NTRS)

Cooper, B. L.; McKay, D. S.; Wallace, W. T.; Gonzalex, C. P.

2011-01-01

From the late 1960s until now, lunar soil particle size distributions have typically been determined by sieving sometimes dry, and at other times with fluids such as water or Freon. Laser diffraction instruments allow rapid assessment of particle size distribution, and eventually may replace sieve measurements. However, when measuring lunar soils with laser diffraction instruments, care must be taken in choosing a carrier fluid that is compatible with lunar material. Distilled water is the fluid of choice for laser diffraction measurements of substances when there is no concern about adverse effects of water on the material being measured. When we began our analyses of lunar soils using laser diffraction, our first measurements were made with distilled water. Although the medians that we measured were comparable to earlier sieve data, the means tended to be significantly larger than expected. The effect of water vapor on lunar soil has been studied extensively. The particles interact strongly with water vapor, and subsequent adsorptions of nitrogen showed that the specific surface area increased as much as threefold after exposure to moisture. It was observed that significant porosity had been generated by this exposure to water vapor. The possibility of other physical changes in the surfaces of the grains was not studied.

Organic matter controls of soil water retention in an alpine grassland and its significance for hydrological processes

NASA Astrophysics Data System (ADS)

Yang, Fei; Zhang, Gan-Lin; Yang, Jin-Ling; Li, De-Cheng; Zhao, Yu-Guo; Liu, Feng; Yang, Ren-Min; Yang, Fan

2014-11-01

Soil water retention influences many soil properties and soil hydrological processes. The alpine meadows and steppes of the Qilian Mountains on the northeast border of the Qinghai-Tibetan Plateau form the source area of the Heihe River, the second largest inland river in China. The soils of this area therefore have a large effect on water movement and storage of the entire watershed. In order to understand the controlling factors of soil water retention and how they affect regional eco-hydrological processes in an alpine grassland, thirty-five pedogenic horizons in fourteen soil profiles along two facing hillslopes in typical watersheds of this area were selected for study. Results show that the extensively-accumulated soil organic matter plays a dominant role in controlling soil water retention in this alpine environment. We distinguished two mechanisms of this control. First, at high matric potentials soil organic matter affected soil water retention mainly through altering soil structural parameters and thereby soil bulk density. Second, at low matric potentials the water adsorbing capacity of soil organic matter directly affected water retention. To investigate the hydrological functions of soils at larger scales, soil water retention was compared by three generalized pedogenic horizons. Among these soil horizons, the mattic A horizon, a diagnostic surface horizon of Chinese Soil Taxonomy defined specially for alpine meadow soils, had the greatest soil water retention over the entire range of measured matric potentials. Hillslopes with soils having these horizons are expected to have low surface runoff. This study promotes the understanding of the critical role of alpine soils, especially the vegetated surface soils in controlling the eco-hydrological processes in source regions of the Heihe River watershed.

Forecasting in an integrated surface water-ground water system: The Big Cypress Basin, South Florida

NASA Astrophysics Data System (ADS)

Butts, M. B.; Feng, K.; Klinting, A.; Stewart, K.; Nath, A.; Manning, P.; Hazlett, T.; Jacobsen, T.

2009-04-01

The South Florida Water Management District (SFWMD) manages and protects the state's water resources on behalf of 7.5 million South Floridians and is the lead agency in restoring America's Everglades - the largest environmental restoration project in US history. Many of the projects to restore and protect the Everglades ecosystem are part of the Comprehensive Everglades Restoration Plan (CERP). The region has a unique hydrological regime, with close connection between surface water and groundwater, and a complex managed drainage network with many structures. Added to the physical complexity are the conflicting needs of the ecosystem for protection and restoration, versus the substantial urban development with the accompanying water supply, water quality and flood control issues. In this paper a novel forecasting and real-time modelling system is presented for the Big Cypress Basin. The Big Cypress Basin includes 272 km of primary canals and 46 water control structures throughout the area that provide limited levels of flood protection, as well as water supply and environmental quality management. This system is linked to the South Florida Water Management District's extensive real-time (SCADA) data monitoring and collection system. Novel aspects of this system include the use of a fully distributed and integrated modeling approach and a new filter-based updating approach for accurately forecasting river levels. Because of the interaction between surface- and groundwater a fully integrated forecast modeling approach is required. Indeed, results for the Tropical Storm Fay in 2008, the groundwater levels show an extremely rapid response to heavy rainfall. Analysis of this storm also shows that updating levels in the river system can have a direct impact on groundwater levels.

Anthropogenic sources and environmentally relevant concentrations of heavy metals in surface water of a mining district in Ghana: a multivariate statistical approach.

PubMed

Armah, Frederick A; Obiri, Samuel; Yawson, David O; Onumah, Edward E; Yengoh, Genesis T; Afrifa, Ernest K A; Odoi, Justice O

2010-11-01

The levels of heavy metals in surface water and their potential origin (natural and anthropogenic) were respectively determined and analysed for the Obuasi mining area in Ghana. Using Hawth's tool an extension in ArcGIS 9.2 software, a total of 48 water sample points in Obuasi and its environs were randomly selected for study. The magnitude of As, Cu, Mn, Fe, Pb, Hg, Zn and Cd in surface water from the sampling sites were measured by flame Atomic Absorption Spectrophotometry (AAS). Water quality parameters including conductivity, pH, total dissolved solids and turbidity were also evaluated. Principal component analysis and cluster analysis, coupled with correlation coefficient analysis, were used to identify possible sources of these heavy metals. Pearson correlation coefficients among total metal concentrations and selected water properties showed a number of strong associations. The results indicate that apart from tap water, surface water in Obuasi has elevated heavy metal concentrations, especially Hg, Pb, As, Cu and Cd, which are above the Ghana Environmental Protection Agency (GEPA) and World Health Organisation (WHO) permissible levels; clearly demonstrating anthropogenic impact. The mean heavy metal concentrations in surface water divided by the corresponding background values of surface water in Obuasi decrease in the order of Cd > Cu > As > Pb > Hg > Zn > Mn > Fe. The results also showed that Cu, Mn, Cd and Fe are largely responsible for the variations in the data, explaining 72% of total variance; while Pb, As and Hg explain only 18.7% of total variance. Three main sources of these heavy metals were identified. As originates from nature (oxidation of sulphide minerals particularly arsenopyrite-FeAsS). Pb derives from water carrying drainage from towns and mine machinery maintenance yards. Cd, Zn, Fe and Mn mainly emanate from industry sources. Hg mainly originates from artisanal small-scale mining. It cannot be said that the difference in concentration of heavy metals might be attributed to difference in proximity to mining-related activities because this is inconsistent with the cluster analysis. Based on cluster analysis SN32, SN42 and SN43 all belong to group one and are spatially similar. But the maximum Cu concentration was found in SN32 while the minimum Cu concentration was found in SN42 and SN43.

Humidity-dependent compression-induced glass transition of the air-water interfacial Langmuir films of poly(D,L-lactic acid-ran-glycolic acid) (PLGA).

PubMed

Kim, Hyun Chang; Lee, Hoyoung; Jung, Hyunjung; Choi, Yun Hwa; Meron, Mati; Lin, Binhua; Bang, Joona; Won, You-Yeon

2015-07-28

Constant rate compression isotherms of the air-water interfacial Langmuir films of poly(D,L-lactic acid-ran-glycolic acid) (PLGA) show a distinct feature of an exponential increase in surface pressure in the high surface polymer concentration regime. We have previously demonstrated that this abrupt increase in surface pressure is linked to the glass transition of the polymer film, but the detailed mechanism of this process is not fully understood. In order to obtain a molecular-level understanding of this behavior, we performed extensive characterizations of the surface mechanical, structural and rheological properties of Langmuir PLGA films at the air-water interface, using combined experimental techniques including the Langmuir film balance, X-ray reflectivity and double-wall-ring interfacial rheometry methods. We observed that the mechanical and structural responses of the Langmuir PLGA films are significantly dependent on the rate of film compression; the glass transition was induced in the PLGA film only at fast compression rates. Surprisingly, we found that this deformation rate dependence is also dependent on the humidity of the environment. With water acting as a plasticizer for the PLGA material, the diffusion of water molecules through the PLGA film seems to be the key factor in the determination of the glass transformation properties and thus the mechanical response of the PLGA film against lateral compression. Based on our combined results, we hypothesize the following mechanism for the compression-induced glass transformation of the Langmuir PLGA film; (1) initially, a humidified/non-glassy PLGA film is formed in the full surface-coverage region (where the surface pressure shows a plateau) during compression; (2) further compression leads to the collapse of the PLGA chains and the formation of new surfaces on the air side of the film, and this newly formed top layer of the PLGA film is transiently glassy in character because the water evaporation rate in the top surface region is momentarily faster than the humidification rate (due to the initial roughness of the newly formed surface); (3) after some time, the top layer itself becomes humidified through diffusion of water from the subphase, and thus it becomes non-glassy, leading to the relaxation of the applied compressive stress.

Interactions of 14C-labeled multi-walled carbon nanotubes with soil minerals in water.

PubMed

Zhang, Liwen; Petersen, Elijah J; Zhang, Wen; Chen, Yongsheng; Cabrera, Miguel; Huang, Qingguo

2012-07-01

Carbon nanotubes are often modified to be stable in the aqueous phase by adding extensive hydrophilic surface functional groups. The stability of such CNTs in water with soil or sediment is one critical factor controlling their environmental fate. We conducted a series of experiments to quantitatively assess the association between water dispersed multi-walled carbon nanotubes (MWCNTs) and three soil minerals (kaolinite, smectite, or shale) in aqueous solution under different sodium concentrations. (14)C-labeling was used in these experiments to unambiguously quantify MWCNTs. The results showed that increasing ionic strength strongly promoted the removal of MWCNTs from aqueous phase. The removal tendency is inversely correlated with the soil minerals' surface potential and directly correlated with their hydrophobicity. This removal can be interpreted by the extended Derjaguin-Landau-Verwey-Overbeek (EDLVO) theory especially for kaolinite and smectite. Shale, which contains large and insoluble organic materials, sorbed MWCNTs the most strongly. Copyright © 2012 Elsevier Ltd. All rights reserved.

Interstellar hydrogen bonding

NASA Astrophysics Data System (ADS)

Etim, Emmanuel E.; Gorai, Prasanta; Das, Ankan; Chakrabarti, Sandip K.; Arunan, Elangannan

2018-06-01

This paper reports the first extensive study of the existence and effects of interstellar hydrogen bonding. The reactions that occur on the surface of the interstellar dust grains are the dominant processes by which interstellar molecules are formed. Water molecules constitute about 70% of the interstellar ice. These water molecules serve as the platform for hydrogen bonding. High level quantum chemical simulations for the hydrogen bond interaction between 20 interstellar molecules (known and possible) and water are carried out using different ab-intio methods. It is evident that if the formation of these species is mainly governed by the ice phase reactions, there is a direct correlation between the binding energies of these complexes and the gas phase abundances of these interstellar molecules. Interstellar hydrogen bonding may cause lower gas abundance of the complex organic molecules (COMs) at the low temperature. From these results, ketenes whose less stable isomers that are more strongly bonded to the surface of the interstellar dust grains have been observed are proposed as suitable candidates for astronomical observations.

Antimicrobial cotton textiles with robust superhydrophobicity via plasma for oily water separation

NASA Astrophysics Data System (ADS)

Zhang, Ming; Pang, Jiuyin; Bao, Wenhui; Zhang, Wenbo; Gao, He; Wang, Chengyu; Shi, Junyou; Li, Jian

2017-10-01

During these decades, functional materials are facing the severe challenge of their weak surface structure. To solve this problem, plasma technology and spraying technology were utilized to improve the bonding effect between cotton substrates and coating structures. Herein, silica/silver nanoparticles (SiO2/Ag NPs) were prepared and introduced to the nano-/micro- structures on sample surface by spraying technology in the existence of polyurethane adhesive. Then the circles of spraying procedure containing adhesive and SiO2/Ag NPs had been discussed. After further fluorination, the samples still displayed an excellent waterproof property even after abrasion test with sand paper and various washing test by its solvent-acetone or harsh liquids with strong acidity/alkalinity, indicating their robust surfaces structures. More importantly, this product displayed the outstanding performance no matter in laboratory oil/water filtration or the extensive oil leakage and spill. At last, our modification also endowed the cotton sample with great antimicrobial property.

Assessing ecohydrological controls on catchment water storage, flux and age dynamics using tracers in a physically-based, spatially distributed model

NASA Astrophysics Data System (ADS)

Kuppel, S.; Tetzlaff, D.; Maneta, M. P.; Soulsby, C.

2017-12-01

Stable water isotope tracing has been extensively used in a wide range of geographical environments as a means to understand the sources, flow paths and ages of water stored and exiting a landscape via evapotranspiration, surface runoff and/or stream flow. Comparisons of isotopic signatures of precipitation and water in streams, soils, groundwater and plant xylem facilitates the assessment of how plant water use may affect preferential hydrologic pathways, storage dynamics and transit times in the critical zone. While tracers are also invaluable for testing model structure and accuracy, in most cases the measured isotopic signatures have been used to guide the calibration of conceptual runoff models with simplified vegetation and energy balance representation, which lacks sufficient detail to constrain key ecohydrological controls on flow paths and water ages. Here, we use a physically-based, distributed ecohydrological model (EcH2O) which we have extended to track 2H and 18O (including fractionation processes), and water age. This work is part of the "VeWa" project which aims at understanding ecohydrological couplings across climatic gradients in the wider North, where the hydrological implications of projected environmental change are essentially unknown though expected to be high. EcH2O combines a hydrologic scheme with an explicit representation of plant growth and phenology while resolving the energy balance across the soil-vegetation-atmosphere continuum. We focus on a montane catchment in Scotland, where unique long-term, high resolution hydrometric, ecohydrological and isotopic data allows for extensive model testing and projections. Results show the importance of incorporating soil fractionation processes to explain stream isotope dynamics, particularly seasonal enrichment in this humid, energy-limited catchment. This generic process-based approach facilitates analysis of dynamics in isotopes, storage and ages for the different hydrological compartments (canopy to groundwater) and, in particular, the explicit partitioning between soil evaporation and plant transpiration. Our study clearly advances our understanding of dynamics in water storage, flux and age in northern ecosystems, integrating ecohydrology, unsaturated zone, surface water, and groundwater hydrology.

Household water treatment systems: A solution to the production of safe drinking water by the low-income communities of Southern Africa

NASA Astrophysics Data System (ADS)

Mwabi, J. K.; Adeyemo, F. E.; Mahlangu, T. O.; Mamba, B. B.; Brouckaert, B. M.; Swartz, C. D.; Offringa, G.; Mpenyana-Monyatsi, L.; Momba, M. N. B.

One of the United Nations Millennium Development Goals is to reduce to half by 2015 the number of people, worldwide, who lack access to safe water. Due to the numerous deaths and illnesses caused by waterborne pathogens, various household water treatment devices and safe storage technologies have been developed to treat and manage water at the household level. The new approaches that are continually being examined need to be durable, lower in overall cost and more effective in the removal of the contaminants. In this study, an extensive literature survey was conducted to regroup various household treatment devices that are suitable for the inexpensive treatment of water on a household basis. The survey has resulted in the selection of four household treatment devices: the biosand filter (BSF), bucket filter (BF), ceramic candle filter (CCF) and the silver-impregnated porous pot filter (SIPP). The first three filters were manufactured in a Tshwane University of Technology workshop, using modified designs reported in literature. The SIPP filter is a product of the Tshwane University of Technology. The performance of the four filters was evaluated in terms of flow rate, physicochemical contaminant (turbidity, fluorides, phosphates, chlorophyll a, magnesium, calcium and nitrates) and microbial contaminant ( Escherichia coli, Vibrio cholerae, Salmonella typhimurium, Shigella dysenteriae) removals. The flow rates obtained during the study period were within the recommended limits (171 l/h, 167 l/h, 6.4 l/h and 3.5 l/h for the BSF, BF, CCF and SIPP, respectively). Using standard methods, the results of the preliminary laboratory and field studies with spiked and environmental water samples indicated that all filters decreased the concentrations of contaminants in test water sources. The most efficiently removed chemical contaminant in spiked water was fluoride (99.9%) and the poorest removal efficiency was noted for magnesium (26-56%). A higher performance in chemical contaminant removal was noted with the BF. For pathogenic bacteria, the mean percentage removals ranged between 97% and 100%. Although the concentrations of most chemical parameters were within the recommended limits in raw surface water, poor removal efficiencies were recorded for all filters, with the poorest reduction noted with fluorides (16-48%). The average turbidity removals from surface water ranged between 90% and 95% for all filters. The highest bacterial removal efficiency was recorded by the SIPP (99-100%) and the lowest by the BF (20-45%) and the BSF (20-60%). Extensive experimental studies with various types of raw surface water will still determine the long-term performance of each filter, as well as the filters that can be recommended to the communities for household treatment of drinking water.

Land subsidence caused by ground water withdrawal in urban areas

USGS Publications Warehouse

Holzer, T.L.; Johnson, A.I.

1985-01-01

At least eight urban areas in the world have encountered significant economic impact from land subsidence caused by pumping of ground water from unconsolidated sediment. The areas, most of which are coastal, include Bangkok, Houston, Mexico City, Osaka, San Jose, Shanghai, Tokyo, and Venice. Flooding related to decreased ground elevation is the principal adverse effect of the subsidence. Lesser effects include regional tilting, well-casing failures, "rising" buildings, and ground failure or rupture. Subsidence of most of these urban areas began before the phenomenon was discovered and understood. Thus, the subsidence problems were unanticipated. Methods to arrest subsidence typically have included control of ground water pumping and development of surface water to offset the reductions of ground water pumping. Ground water recharge has also been practiced. Areas threatened by flooding have been protected by extensive networks of dikes and sea walls, locks, and pumping stations to remove storm runoff. ?? 1985 D. Reidel Publishing Company.

Atomic-scale imaging of the dissolution of NaCl islands by water at low temperature

NASA Astrophysics Data System (ADS)

Peng, Jinbo; Guo, Jing; Ma, Runze; Meng, Xiangzhi; Jiang, Ying

2017-03-01

The dissolution of sodium chloride (NaCl) in water is a frequently encountered process in our daily lives. While the NaCl dissolution process in liquid water has been extensively studied, whether and how the dissolution occurs below the freezing point is still not clear. Using a low-temperature scanning tunneling microscope (STM), here we were able to directly visualize the dissolution of Au-supported NaCl (0 0 1) bilayer islands by water at atomic level. We found that the single water molecule on the STM tip can assist the extraction of single Na+ from the NaCl surface even at 5 K, while leaving the Cl- intact. When covered with a full water monolayer, the NaCl islands started to dissolve from the step edges and also showed evidence of dissolution inside the terraces as the temperature was raised up to 145 K. At 155 K, the water molecules completely desorbed from the surface, which was accompanied with the decomposition and restructuring of the bilayer NaCl islands. Those results suggest that the dissolution of NaCl may occur well below the freezing point at the ice/NaCl interfaces and is mainly driven by the interaction between the water molecules and the Na+, which is in clear contrast with the NaCl dissolution in liquid water.

The Basin of Mexico and its metropolitan area: water abstraction and related environmental problems

NASA Astrophysics Data System (ADS)

González-Morán, T.; Rodríguez, R.; Cortes, S. A.

1999-11-01

The Basin of Mexico is a closed basin of lacustrine character, with an average elevation of 2200 m above sea level. The watershed covers a vast extension in five states. Mexico City and its metropolitan area are located within this basin. The aquifer system is the main source of water supply for more than 20 million people. Water consumption is about 60 m 3/s. The aquifer supplies about 43 m 3/s from around 1000 wells at 70-200 m depth. Pumping policies have generated subsidence and degradation of the ground water quality in the Basin of Mexico The lacustrian clay layers play an important role in the local hydrogeology, protecting the aquifer from pollution, but the transition and piedmont areas are highly vulnerable to surface pollutants.

Differences in mechanical and structural properties of surface and aerial petioles of the aquatic plant Nymphaea odorata subsp. tuberosa (Nymphaeaceae).

PubMed

Etnier, Shelley A; Villani, Philip J

2007-07-01

Lily pads (Nymphaea odorata) exhibit heterophylly where a single plant may have leaves that are submerged, floating, or above (aerial) the surface of the water. Lily pads are placed in a unique situation because each leaf form is exposed to a distinctly different set of mechanical demands. While surface petioles may be loaded in tension under conditions of wind or waves, aerial petioles are loaded in compression because they must support the weight of the lamina. Using standard techniques, we compared the mechanical and morphological properties of both surface and aerial leaf petioles. Structural stiffness (EI) and the second moment of area (I) were higher in aerial petioles, although we detected no differences in other mechanical values (elastic modulus [E], extension ratio, and breaking strength). Morphologically, aerial petioles had a thicker rind, with increased collenchyma tissue and sclereid cell frequency. Aerial petioles also had a larger cross-sectional area and were more elliptical. Thus, subtle changes in the distribution of materials, rather than differences in their makeup, differentiate petiole forms. We suggest that the growth of aerial petioles may be an adaptive response to shading, allowing aerial leaves to rise above a crowded water surface.

Effects of surface mining on fish and wildlife in Appalachia

USGS Publications Warehouse

Boccardy, Joseph A.; Spaulding, William M.

1968-01-01

This report on the effects of strip and surface mining on the fish and wildlife resources in eight Appalachian States is based in part on observation made during a tour of strip and surface mined area by the authors, as members of a team of specialist from six Federal agencies. Surface mining has caused extensive damage to fish and wildlife habitats and populations. A total of 832,605 acres of land have been disturbed; 81 percent of these are in Ohio, Pennsylvania, and West Virginia. More than 5,000 miles of Appalachian streams and 13,800 acres of impoundments have been seriously contaminated by acid mine water, some of it from surface mining. Additional water acreage has been adversely affected by tremendous quantities of silt and sediment. Reclamation of mined lands is needed. Three of the eight states visited in 1965-66 had no law requiring restoration of strip-mined lands, and other States needed stronger laws and more enforcement (Virginia and Tennessee have since passed laws governing strip mining). Reclamation as currently practiced in the Appalachian region does not adequately restore mined lands to minimal standards necessary to protect and improve fish and wildlife resources.

Mapping permeability over the surface of the Earth

USGS Publications Warehouse

Gleeson, T.; Smith, L.; Moosdorf, N.; Hartmann, J.; Durr, H.H.; Manning, A.H.; Van Beek, L. P. H.; Jellinek, A. Mark

2011-01-01

Permeability, the ease of fluid flow through porous rocks and soils, is a fundamental but often poorly quantified component in the analysis of regional-scale water fluxes. Permeability is difficult to quantify because it varies over more than 13 orders of magnitude and is heterogeneous and dependent on flow direction. Indeed, at the regional scale, maps of permeability only exist for soil to depths of 1-2 m. Here we use an extensive compilation of results from hydrogeologic models to show that regional-scale (>5 km) permeability of consolidated and unconsolidated geologic units below soil horizons (hydrolithologies) can be characterized in a statistically meaningful way. The representative permeabilities of these hydrolithologies are used to map the distribution of near-surface (on the order of 100 m depth) permeability globally and over North America. The distribution of each hydrolithology is generally scale independent. The near-surface mean permeability is of the order of ???5 ?? 10-14 m2. The results provide the first global picture of near-surface permeability and will be of particular value for evaluating global water resources and modeling the influence of climate-surface-subsurface interactions on global climate change. Copyright ?? 2011 by the American Geophysical Union.

Mapping permeability over the surface of the Earth

USGS Publications Warehouse

Gleeson, Tom; Smith, Leslie; Moosdorf, Nils; Hartmann, Jens; Durr, Hans H.; Manning, Andrew H.; van Beek, Ludovicus P. H.; Jellinek, A. Mark

2011-01-01

Permeability, the ease of fluid flow through porous rocks and soils, is a fundamental but often poorly quantified component in the analysis of regional-scale water fluxes. Permeability is difficult to quantify because it varies over more than 13 orders of magnitude and is heterogeneous and dependent on flow direction. Indeed, at the regional scale, maps of permeability only exist for soil to depths of 1-2 m. Here we use an extensive compilation of results from hydrogeologic models to show that regional-scale (>5 km) permeability of consolidated and unconsolidated geologic units below soil horizons (hydrolithologies) can be characterized in a statistically meaningful way. The representative permeabilities of these hydrolithologies are used to map the distribution of near-surface (on the order of 100 m depth) permeability globally and over North America. The distribution of each hydrolithology is generally scale independent. The near-surface mean permeability is of the order of -5 x 10-14 m2. The results provide the first global picture of near-surface permeability and will be of particular value for evaluating global water resources and modeling the influence of climate-surface-subsurface interactions on global climate change.

Investigation of statistical parameters of the evolving wind wave field using a laser slope gauge

NASA Astrophysics Data System (ADS)

Zavadsky, A.; Shemer, L.

2017-05-01

Statistical parameters of water waves generated by wind in a small scale facility are studied using extensively a Laser Slope Gauge (LSG), in addition to conventional measuring instruments such as a wave gauge and Pitot tube. The LSG enables direct measurements of two components of the instantaneous surface slope. Long sampling duration in a relatively small experimental facility allowed accumulating records of the measured parameters containing a large number of waves. Data were accumulated for a range of wind velocities at multiple fetches. Frequency spectra of the surface elevation and of the instantaneous local slope variation measured under identical conditions are compared. Higher moments of the surface slope are presented. Information on the waves' asymmetry is retrieved from the computed skewness of the surface slope components.

Stable isotope variations (δ18O and δD) in modern waters across the Andean Plateau

NASA Astrophysics Data System (ADS)

Bershaw, John; Saylor, Joel E.; Garzione, Carmala N.; Leier, Andrew; Sundell, Kurt E.

2016-12-01

Environmental parameters that influence the isotopic composition of meteoric water (δ18O and δD) are well characterized up the windward side of mountains, where orographic precipitation results in a predictable relationship between the isotopic composition of precipitation and elevation. The topographic and climatic evolution of the Andean Plateau and surrounding regions has been studied extensively by exploiting this relationship through the use of paleowater proxies. However, interpretation on the plateau itself is challenged by a poor understanding of processes that fractionate isotopes during vapor transport and rainout, and by the relative contribution of unique moisture sources. Here, we present an extensive dataset of modern surface water samples for the northern Andean Plateau and surrounding regions to elucidate patterns and causes of isotope fractionation in this continental environment. These data show a progressive increase in δ18O of stream water west of the Eastern Cordillera (∼1‰/70 km), almost identical to the rate observed across the Tibetan Plateau, attributed to a larger fraction of recycled water in precipitation and/or increased evaporative enrichment downwind. This may lead to underestimates of paleoelevation, particularly for sites deep into the rainshadow of the Eastern Cordilleran crest. That said, elevation is a primary control on the isotopic composition of surface waters across the entire Andean Plateau and its flanks when considering the most negative δ18O values, highlighting the need for sufficiently large datasets to distinguish minimally evaporated samples. There is a general increase in δ18O on the plateau from north to south, concomitant with an increase in aridity and decrease in convective moistening (amount effect). Lastly, stable isotope and seasonal precipitation patterns suggest easterlies provide the vast majority of moisture that falls as precipitation across the Andean Plateau and Western Cordillera, from Peru to northern Bolivia (-13° to -20° latitude), with Pacific-derived moisture contributing a minor amount at low elevations near the coast.

Mechanisms of Forming Intergranular Microcracks and Microscopic Surface Discontinuities in Welds

DTIC Science & Technology

1992-06-01

SCC) is defined as slow stable crack extension occurring under static loading in sea water at stress intensity values below KIc (critical stress...preheating on the cold cracking resistance is reflected mainly in a reduction of the degree of localization of microplastic strains, their...deconcentration and an increase of the basis over which microplastic yielding takes place. This increases the amount of energy used for local plastic deformation

Root nodulation in the wetland tree Pterocarpus officinalis along coastal and montane systems of Northeast of Puerto Rico

Treesearch

Rachel Pérez; Tamara Heartsill Scalley

2008-01-01

In Puerto Rico, brackish water wetlands were dominated by Pterocarpus officinalis previous to extensive deforestation due to agriculture. Today remnant wetlands are limited to small areas that are threatened by rise in sea level. We examined the root nodules of P. officinalis in montane and coastal sites and at 0, 10, 20 cm from the surface to determine if site...

Phosphorus loss to runoff water twenty-four hours after application of liquid swine manure or fertilizer.

PubMed

Tabbara, Hadi

2003-01-01

Phosphorus (P) added to soil from fertilizer or manure application could pose a threat to water quality due to its role in eutrophication of fresh water resources. Incorporating such amendments into the soil is an established best management practice (BMP) for reducing soluble P losses in runoff water, but could also lead to higher erosion. The objective of this study was to test whether incorporation of manure or fertilizer 24 h before an intense rain could also reduce sediment-bound and total phosphorus (TP) losses in runoff. A rainfall simulation study was conducted on field plots (sandy loam with 6-7% slope, little surface residue, recently cultivated) that received two application rates of liquid swine manure or liquid ammonium polyphosphate fertilizer, using either surface-broadcast or incorporated methods of application. Incorporation increased the total suspended solids (TSS) concentrations in runoff but mass losses were not affected. Incorporation also reduced flow-weighted concentrations and losses of dissolved reactive phosphorus (DRP) and TP by as much as 30 to 60% depending on source (fertilizer vs. manure) and application rate. Phosphorus is moved below the mixing zone of interaction on incorporation, and thus the effect of the amount and availability of P in this zone is more important than cultivation on subsequent P losses in runoff. Incorporating manure or fertilizer in areas of intense erosive rain, recent extensive tillage, and with little or no surface residue is therefore a best management practice that should be adhered to in order to minimize contamination of surface water. Results also show comparatively lower P losses from manure than fertilizer.

Study of the air-water interfacial properties of biodegradable polyesters and their block copolymers with poly(ethylene glycol).

PubMed

Park, Hae-Woong; Choi, Je; Ohn, Kimberly; Lee, Hyunsuk; Kim, Jin Woong; Won, You-Yeon

2012-08-07

It has been reported that the surface pressure-area isotherm of poly(D,L-lactic acid-ran-glycolic acid) (PLGA) at the air-water interface exhibits several interesting features: (1) a plateau at intermediate compression levels, (2) a sharp rise in surface pressure upon further compression, and (3) marked surface pressure-area hysteresis during compression-expansion cycles. To investigate the molecular origin of this behavior, we conducted an extensive set of surface pressure and AFM imaging measurements with PLGA materials having several different molecular weights and also a poly(D,L-lactic acid-ran-glycolic acid-ran-caprolactone) (PLGACL) material in which the caprolactone monomers were incorporated as a plasticizing component. The results suggest that (i) the plateau in the surface pressure-area isotherm of PLGA (or PLGACL) occurs because of the formation (and collapse) of a continuous monolayer of the polymer under continuous compression; (ii) the PLGA monolayer becomes significantly resistant to compression at high compression because under that condition the collapsed domains become large enough to become glassy (such behavior was not observed in the nonglassy PLGACL sample); and (iii) the isotherm hysteresis is due to a coarsening of the collapsed domains that occurs under high-compression conditions. We also investigated the monolayer properties of PEG-PLGA and PEG-PLGACL diblock copolymers. The results demonstrate that the tendency of PLGA (or PLGACL) to spread on water allows the polymer to be used as an anchoring block to form a smooth biodegradable monolayer of block copolymers at the air-water interface. These diblock copolymer monolayers exhibit protein resistance.

How to spy on your neighbor's water consumption from space

NASA Astrophysics Data System (ADS)

Neely, W.; Borsa, A. A.; Burney, J. A.

2017-12-01

Dependence on groundwater has increased in the agricultural production regions of California's Central Valley due to recent and persistent droughts. To protect the long-term reliability of groundwater resources in California, the state passed the Sustainable Groundwater Management Act (SGMA) in September 2014. In situ observation of subsurface reservoir levels is ideal for monitoring aquifer health at a water district scale, but is limited by the low density of monitoring wells and temporal gaps between measurements. An alternative to well measurements relies on the fact that groundwater extraction may lead to surface subsidence due to the compaction of the aquifer at depth. Such surface displacements can be resolved using geodetic techniques. We present an integrative approach using Interferometric Synthetic Aperture Radar (InSAR) and continuous Global Positioning System (cGPS) station observations to characterize surface deformation related to extensive pumping at a farm-level resolution every 12-24 days. We demonstrate our technique in the southern Central Valley where we observe subsidence upwards of 25 cm/yr from late 2014 to early 2017. Our methods offer an inexpensive supplement to in situ measurements that allows for the detection and deterrence of water mismanagement.

The Influence of Surface Coal Mining on Runoff Processes and Stream Chemistry in the Elk Valley, British Colubmbia, Canada

NASA Astrophysics Data System (ADS)

Carey, S. K.; Wellen, C. C.; Shatilla, N. J.

2015-12-01

Surface mining is a common method of accessing coal. In high-elevation environments, vegetation and soils are typically removed prior to the blasting of overburden rock, thereby allowing access to mineable ore. Following this, the removed overburden rock is deposited in adjacent valleys as waste rock spoils. Previous research has identified that areas downstream of surface coal mining have impaired water quality, yet there is limited information about the interaction of hydrology and geochemistry across a range of mining conditions, particularly at the headwater scale. Here, we provide an analysis of an extensive long-term data set of geochemistry and flows across a gradient of coal mining in the Elk Valley, British Columbia, Canada. This work is part of a broader R&D program examining the influence of surface coal mining on hydrological and water quality responses in the Elk Valley aimed at informing effective management responses. Results indicate that water from waste rock piles has an ionic profile distinct from unimpacted catchments. While the concentration of geochemicals increased with the degree of mine impact, the control of hydrological transport capacity over geochemical export did not vary with degree of mine impact. Geochemical export in mine-influenced catchments was limited more strongly by transport capacity than supply, implying that more water moving through the waste rock mobilized more geochemicals. Placement of waste rock within the catchment (headwaters or outlet) did not affect chemical concentrations but did alter the timing with which chemically distinct water mixed. This work advances on results reported earlier using empirical models of selenium loading and further highlights the importance of limiting water inputs into waste rock piles.

Macro-Invertebrate Decline in Surface Water Polluted with Imidacloprid

PubMed Central

Van Dijk, Tessa C.; Van Staalduinen, Marja A.; Van der Sluijs, Jeroen P.

2013-01-01

Imidacloprid is one of the most widely used insecticides in the world. Its concentration in surface water exceeds the water quality norms in many parts of the Netherlands. Several studies have demonstrated harmful effects of this neonicotinoid to a wide range of non-target species. Therefore we expected that surface water pollution with imidacloprid would negatively impact aquatic ecosystems. Availability of extensive monitoring data on the abundance of aquatic macro-invertebrate species, and on imidacloprid concentrations in surface water in the Netherlands enabled us to test this hypothesis. Our regression analysis showed a significant negative relationship (P<0.001) between macro-invertebrate abundance and imidacloprid concentration for all species pooled. A significant negative relationship was also found for the orders Amphipoda, Basommatophora, Diptera, Ephemeroptera and Isopoda, and for several species separately. The order Odonata had a negative relationship very close to the significance threshold of 0.05 (P = 0.051). However, in accordance with previous research, a positive relationship was found for the order Actinedida. We used the monitoring field data to test whether the existing three water quality norms for imidacloprid in the Netherlands are protective in real conditions. Our data show that macrofauna abundance drops sharply between 13 and 67 ng l−1. For aquatic ecosystem protection, two of the norms are not protective at all while the strictest norm of 13 ng l−1 (MTR) seems somewhat protective. In addition to the existing experimental evidence on the negative effects of imidacloprid on invertebrate life, our study, based on data from large-scale field monitoring during multiple years, shows that serious concern about the far-reaching consequences of the abundant use of imidacloprid for aquatic ecosystems is justified. PMID:23650513

Early Mars: A Warm Wet Niche for Life

NASA Technical Reports Server (NTRS)

Gibson, Everett K.; McKay, David S.; Thomas-Keprta, Kathie L.; Clemett, Simon J.

2010-01-01

Exploration of Mars has begun to unveil the history of the planet. Combinations of remote sensing, in situ compositional measurements and photographic observations have shown Mars had a dynamic and active geologic evolution. Mars geologic evolution had conditions that were suitable for supporting life. A habitable planet must have water, carbon and energy sources along with a dynamic geologic past. Mars meets all of these requirements. The first 600 Ma of Martian history were ripe for life to develop because of the abundance of: (i) Water-as shown by carved canyons and oceans or lakes with the early presence of near surface water shown by precipitated carbonates in ALH84001, well-dated at approx.3.9 Ga, (ii) Energy from the original accretional processes, a molten core which generated a strong magnetic field leaving a permanent record in the early crust, active volcanism continuing throughout Martian history, and continuing impact processes, (iii) Carbon, water and a likely thicker atmosphere from extensive volcanic outgassing (i.e. H2O, CO2, CH4, CO, O2, N2, H2S, SO2, etc.) and (iv) crustal tectonics as revealed by faulting and possible plate movement reflected by the magnetic patterns in the crust [1]. The question arises: "Why would life not develop from these favorable conditions on Mars in its first 600 Ma?" During this period, environmental near-surface conditions on Mars were more favorable to life than at any later time. Standing bodies of water, precipitation and flowing surface water, and possibly abundant hydrothermal energy would favor the formation of early life. (Even if life developed elsewhere on Earth, Venus, or on other bodies-it was transported to Mars where surface conditions were suitable for life to evolve)

Geo-spatial analysis of land-water resource degradation in two economically contrasting agricultural regions adjoining national capital territory (Delhi).

PubMed

Kaur, Ravinder; Minhas, P S; Jain, P C; Singh, P; Dubey, D S

2009-07-01

The present study was aimed at characterizing the soil-water resource degradation in the rural areas of Gurgaon and Mewat districts, the two economically contrasting areas in policy zones-II and III of the National Capital Region (NCR), and assessing the impact of the study area's local conditions on the type and extent of resource degradation. This involved generation of detailed spatial information on the land use, cropping pattern, farming practices, soils and surface/ground waters of Gurgaon and Mewat districts through actual resource surveys, standard laboratory methods and GIS/remote sensing techniques. The study showed that in contrast to just 2.54% (in rabi season) to 4.87% (in kharif season) of agricultural lands in Gurgaon district, about 11.77% (in rabi season) to 24.23% (in kharif season) of agricultural lands in Mewat district were irrigated with saline to marginally saline canal water. Further, about 10.69% of agricultural lands in the Gurgaon district and 42.15% of agricultural lands in the Mewat district were drain water irrigated. A large part of this surface water irrigated area, particularly in Nuh (48.7%), Nagina (33.5%), and Punhana (24.1%) blocks of Mewat district, was either waterlogged (7.4% area with 0.05 ppm). In fact, sub-surface drinking waters of some areas around battery and automobile manufacturing units in Gurgaon and Pataudi blocks were associated with exceptionally high (>0.1 ppm) Ni concentrations. In general, the ground waters of waterlogged or potentially waterlogged areas in the rural areas of Mewat were more contaminated than the ground waters in the rural areas of Gurgaon district with deeper (>5 m) water depths.Though Cr concentrations in the surface and sub-surface irrigation waters of both Gurgaon and Mewat districts were far above the maximum permissible limit of 1 ppm, their bio-available soil-Cr concentrations were well within permissible limit. Even bio-available Ni concentrations in agricultural lands of Gurgaon district associated with Ni contaminated sub-surface irrigations were well within desirable limit of 0.20 ppm. This was primarily attributed to the calcareous nature of the soils of the study area. About 35% of Gurgaon district and 59% of Mewat district irrigated with poor quality waters were salt-affected. These waterlogged/potentially waterlogged calcareous-salt affected soils of Mewat district were having acute zinc (Zn) deficiency (<0.6 ppm). Some areas with extremely high iron (Fe: 20-25 ppm) and Mn (10-25 ppm) concentrations were also noticed in the Gurgaon, Nuh and Punhana blocks. Generation of reduced conditions owing to paddy cultivation in areas with 3-3.5 m water depths appeared to be the main cause of such point contaminations. Extensive cadmium (Cd) contamination was also noticed in the waterlogged sodic agricultural lands of Nagina village in Mewat district associated with a large scale scrap automobile and battery business. The study could document the processes and provide spatially accurate information to the managers (e.g., National Capital Region Planning Board) and the concerned citizen groups. It could, in fact, clearly point out that dumping of industrial and domestic wastewaters especially from NCT-Delhi into river Yamuna and, to some extent, from NCT-Delhi re-located hazardous industrial units into Najafgarh drain tributaries at Delhi-Gurgaon boundary, and poor "off-farm" water management practices were the main reasons for extensive (point/non-point source) land-water degradation in Gurgaon and Mewat districts of NCR.

Insights into the effects of patchy ice layers on water balance heterogeneity in peatlands

NASA Astrophysics Data System (ADS)

Dixon, Simon; Kettridge, Nicholas; Devito, Kevin; Petrone, Rich; Mendoza, Carl; Waddington, Mike

2017-04-01

Peatlands in boreal and sub-arctic settings are characterised by a high degree of seasonality. During winter soils are frozen and snow covers the surface preventing peat moss growth. Conversely, in summer, soils unfreeze and rain and evapotranspiration drive moss productivity. Although advances have been made in understanding growing season water balance and moss dynamics in northern peatlands, there remains a gap in knowledge of inter-seasonal water balance as layers of ice break up during the spring thaw. Understanding the effects of ice layers on spring water balance is important as this coincides with periods of high wildfire risk, such as the devastating Fort McMurrary wildfire of May, 2016. We hypothesise that shallow layers of ice disconnect the growing surface of moss from a falling water table, and prevent water from being supplied from depth. A disconnect between the evaporating surface and deeper water storage will lead to the drying out of the surface layer of moss and a greater risk of severe spring wildfires. We utilise the unsaturated flow model Hydrus 2D to explore water balance in peat layers with an impermeable layer representing ice. Additionally we create models to represent the heterogeneous break up of ice layers observed in Canadian boreal peatlands; these models explore the ability of breaks in an ice layer to connect the evaporating surface to a deeper water table. Results show that peatlands with slower rates of moss growth respond to dry periods by limiting evapotranspiration and thus maintain moist conditions in the sub-surface and a water table above the ice layer. Peatlands which are more productive continue to grow moss and evaporate during dry periods; this results in the near surface mosses drying out and the water table dropping below the level of the ice. Where there are breaks in the ice layer the evaporating surface is able to maintain contact with a falling water table, but connectivity is limited to above the breaks, with limited lateral transfer of water above the ice. Conceptually this means that peatlands which tend to have lower rates of growth are largely unaffected by the presence of a shallow ice layer in the early growing season, and are able to maintain moist sub-surface conditions in the absence of precipitation. They will thus be more resistant to severe wildfire. Conversely, peatlands which tend towards higher levels of moss productivity are able to maintain moss growth during dry periods. In the presence of an ice layer this greater productivity leads to a disconnection from deep water sources, extensive drying out of moss above the ice, and a greater susceptibility to severe wildfires. Our study gives important insights into the mechanisms behind heterogeneity in burning and depth of burn in northern peatland wildfires, as well as into burn heterogeneity within peatland microtopography.

Efficacy of home washing methods in controlling surface microbial contamination on fresh produce.

PubMed

Kilonzo-Nthenge, Agnes; Chen, Fur-Chi; Godwin, Sandria L

2006-02-01

Much effort has been focused on sanitation of fresh produce at the commercial level; however, few options are available to the consumer. The purpose of this study was to determine the efficacy of different cleaning methods in reducing bacterial contamination on fresh produce in a home setting. Lettuce, broccoli, apples, and tomatoes were inoculated with Listeria innocua and then subjected to combinations of the following cleaning procedures: (i) soak for 2 min in tap water, Veggie Wash solution, 5% vinegar solution, or 13% lemon solution and (ii) rinse under running tap water, rinse and rub under running tap water, brush under running tap water, or wipe with wet/dry paper towel. Presoaking in water before rinsing significantly reduced bacteria in apples, tomatoes, and lettuce, but not in broccoli. Wiping apples and tomatoes with wet or dry paper towel showed lower bacterial reductions compared with soaking and rinsing procedures. Blossom ends of apples were more contaminated than the surface after soaking and rinsing; similar results were observed between flower section and stem of broccoli. Reductions of L. innocua in both tomatoes and apples (2.01 to 2.89 log CFU/g) were more than in lettuce and broccoli (1.41 to 1.88 log CFU/g) when subjected to same washing procedures. Reductions of surface contamination of lettuce after soaking in lemon or vinegar solutions were not significantly different (P > 0.05) from lettuce soaking in cold tap water. Therefore, educators and extension workers might consider it appropriate to instruct consumers to rub or brush fresh produce under cold running tap water before consumption.

Adsorption, folding, and packing of an amphiphilic peptide at the air/water interface.

PubMed

Engin, Ozge; Sayar, Mehmet

2012-02-23

Peptide oligomers play an essential role as model compounds for identifying key motifs in protein structure formation and protein aggregation. Here, we present our results, based on extensive molecular dynamics simulations, on adsorption, folding, and packing within a surface monolayer of an amphiphilic peptide at the air/water interface. Experimental results suggest that these molecules spontaneously form ordered monolayers at the interface, adopting a β-hairpin-like structure within the surface layer. Our results reveal that the β-hairpin structure can be observed both in bulk and at the air/water interface. However, the presence of an interface leads to ideal partitioning of the hydrophobic and hydrophilic residues, and therefore reduces the conformational space for the molecule and increases the stability of the hairpin structure. We obtained the adsorption free energy of a single β-hairpin at the air/water interface, and analyzed the enthalpic and entropic contributions. The adsorption process is favored by two main factors: (1) Free-energy reduction due to desolvation of the hydrophobic side chains of the peptide and release of the water molecules which form a cage around these hydrophobic groups in bulk water. (2) Reduction of the total air/water contact area at the interface upon adsorption of the peptide amphiphile. By performing mutations on the original molecule, we demonstrated the relative role of key design features of the peptide. Finally, by analyzing the potential of mean force among two peptides at the interface, we investigated possible packing mechanisms for these molecules within the surface monolayer. © 2012 American Chemical Society

Insights from 14C into C loss pathways in degraded peatlands

NASA Astrophysics Data System (ADS)

Evans, Martin; Evans, Chris; Allott, Tim; Stimson, Andrew; Goulsbra, Claire

2016-04-01

Peatlands are important global stores of terrestrial carbon. Lowered water tables due to changing climate and direct or indirect human intervention produce a deeper aerobic zone and have the potential to enhance loss of stored carbon from the peat profile. The quasi continuous accumulation of organic matter in active peatlands means that the age of fluvial dissolved organic carbon exported from peatland systems is related to the source depth in the peat profile. Consequently 14C analysis of DOC in waters draining peatlands has the potential not only to tell us about the source of fluvial carbon and the stability of the peatland but also about the dominant hydrological pathways in the peatland system. This paper will present new radiocarbon determinations from peatland streams draining the heavily eroded peatlands of the southern Pennine uplands in the UK. These blanket peatland systems are highly degraded, with extensive bare peat and gully erosion resulting from air pollution during the industrial revolution, overgrazing, wildfire and climatic changes. Deep and extensive gullying has significantly modified the hydrology of these systems leading to local and more widespread drawdown of water table. 14C data from DOC in drainage waters are presented from two catchments; one with extensive gully erosion and the other with a combination of gully erosion and sheet erosion of the peat. At the gully eroded site DOC in drainage waters is as old as 160 BP but at the site with extensive sheet erosion dates of up to 1069 BP are amongst the oldest recorded from blanket peatland globally These data indicate significant degradation of stored carbon from the eroding peatlands. Initial comparisons of the 14C data with modelled water table for the catchments and depth-age curves for catchment peats suggests that erosion of the peat surface, allowing decomposition of exposed older organic material is a potential mechanism producing aged carbon from the eroded catchment. This mechanism may be as important as changes in hydrological flow pathways within the peat in mobilising aged carbon from the systems.

Zooplankton responses to increasing sea surface temperatures in the southeastern Australia global marine hotspot

NASA Astrophysics Data System (ADS)

Kelly, Paige; Clementson, Lesley; Davies, Claire; Corney, Stuart; Swadling, Kerrie

2016-10-01

Southeastern Australia is a 'hotspot' for oceanographic change. Here, rapidly increasing sea surface temperatures, rising at more than double the global trend, are largely associated with a southerly extension of the East Australian Current (EAC) and its eddy field. Maria Island, situated at the southern end of the EAC extension at 42°S, 148°E, has been used as a site to study temperature-driven biological trends in this region of accelerated change. Zooplankton have short life cycles (usually < 1 year) and are highly sensitive to environmental change, making them an ideal indicator of the biological effects of an increased southward flow of the EAC. Data from in-situ net drops and the Continuous Plankton Recorder (CPR), collected since 2009, together with historical zooplankton abundance data, have been analysed in this study. Like the North Atlantic, zooplankton communities of southeastern Australia are responding to increased temperatures through relocation, long-term increases in warm-water species and a shift towards a zooplankton community dominated by small copepods. The biological trends present evidence of extended EAC influence at Maria Island into autumn and winter months, which has allowed for the rapid establishment of warm-water species during these seasons, and has increased the similarity between Maria Island and the more northerly Port Hacking zooplankton community. Generalised Linear Models (GLM) suggest the high salinity and low nutrient properties of EAC-water to be the primary drivers of increasing abundances of warm-water species off southeastern Australia. Changes in both the species composition and size distribution of the Maria Island zooplankton community will have effects for pelagic fisheries. This study provides an indication of how zooplankton communities influenced by intensifying Western Boundary currents may respond to rapid environmental change.

Satellite detection, tracing, and early warning of harmful algal blooms (HABs) for the Asian waters

NASA Astrophysics Data System (ADS)

Tang, D. L.

Over the past two decades, Harmful Algal Blooms (HABs) appear to have increased in frequency, intensity and geographic distribution worldwide, and have caused large economic losses in aquacultured and wild fisheries in recent years. Understanding of the oceanic mechanisms is important for early warning of HAB events. The present study reported several extensive HABs in the Asian waters during 1998 to 2003 detected by satellite remote sensing data (SeaWiFS, NOAA AVHRR, and QuikScat) and in situ observations. An extensive HAB off southeastern Vietnamese waters during late June to July 2002 was detected and its related oceanographic features were analyzed. The HAB had high Chlorophyll-a (Chl-a) concentrations (up to 4.5 mg m-3), occurring about 200 km off the coast and about 200 km northeast of the Mekong River mouth, for a period of about 6 weeks. The bloom was dominated by the harmful algae haptophyte Phaeocystis cf. globosa, and caused a very significant mortality of aquacultured fishes and other marine life. In the same period, Sea Surface Temperature (SST) imagery showed a coldwater plume extending from the coast to the open sea, and QuikScat data showed strong southwesterly winds blowing parallel with the coastline. It indicated the HAB was induced and supported by offshore upwelling that bring nutrients from the deep ocean to the surface and from coastal water to the offshore, and the upwelling was driven by strong wind through Ekman transport when winds were parallel with the coastline. This study demonstrated the possibility of utilizing a combination of satellite data of Chl-a, SST and wind velocity together with coastal bathymetric information and in situ observation to give a better understanding of the biological oceanography of HABs; these results may help for the early warming of HAB.

Effects of hydraulic and geologic factors on streamflow of the Yakima River Basin, Washington

USGS Publications Warehouse

Kinnison, Hallard B.; Sceva, Jack E.

1963-01-01

The Yakima River basin, in south-central Washington, is the largest single river system entirely within the confines of the State. Its waters are the most extensively utilized of all the rivers in Washington. The river heads high on the eastern slope of the Cascade Mountains, flows for 180 miles in a generally southeast direction, and discharges into the Columbia River. The western part of the basin is a mountainous area formed by sedimentary, volcanic, and metamorphic rocks, which generally have a low capacity for storing and transmitting water. The eastern part of the basin is. formed by a thick sequence of lava flows that have folded into long ridges and troughs. Downwarped structural basins between many of the ridges are partly filled with younger sedimentary deposits, which at some places are many hundreds of feet thick. The Yakima River flows from structural basin to structural basin through narrow water gaps that have been eroded through the anticlinal ridges. Each basin is also a topographic basin and a ground-water subbasin. A gaging station will measure the total outflow of a drainage area only if it is located at the surface outlet of a ground-water subbasin and then only if the stream basin is nearly coextensive with the ground-water subbasin. Many gaging stations in the Yakima basin are so located. The geology, hydrology, size. and location of 25 ground-water subbasins are described. Since the settlement of the valley began, the development of the land and water resources have caused progressive changes in the natural regimen of the basin's runoff. These changes have resulted from diversion of water from the streams, the application of water on the land for irrigation, the storage and release of flood waters, the pumping of ground water, and other factors Irrigation in the Yakima basin is reported 'to have begun about 1864. In 1955 about 425,000 acres were under irrigation. During the past 60-odd years many gaging stations have been operated at different sites within the basin. Only stations in the upper reaches, such as those below Keechelus, Kachess, or Cle Elum Lakes, give discharge records which are an accurate measure of the natural outflow of the drainage area. Farther down, stream, as the utilization of water becomes more extensive, the records at a gaging station show the discharge passing a particular point, but they do not reflect the natural outflow of the basin. Large canals divert water for use on lands above a station or carry it around a station for irrigation downstream. The deep sedimentary deposits within subbasins and the overlying alluvial gravels permit downvalley movement of large subsurface flows which bypass the gaging stations, except in the near vicinity of the water gaps. At the water gaps ground water rises to the surface, becoming streamflow, and can be accurately measured. The location of gaging stations within each subbasin is important, therefore, in determining whether the flow measured represents the total downvalley outflow or whether it is merely the surface-water component. Surface and subsurface factors that may affect the discharge records at each gaging station in the Yakima River basin include a description of upstream diversions, surface return flows, bypass canals, storage reservoirs, subsurface bypass flows, ground-water withdrawals, and other items. The available data are not sufficiently complete to permit a quantitative determination of the total basin yield at most gaging stations. However, data on the existing bypass channels, such as canals and drainage ditches, and on related subsurface movement of water provide valuable information necessary to proper use and interpretation of the streamflow records.

Water at Biological Phase Boundaries: Its Role in Interfacial Activation of Enzymes and Metabolic Pathways.

PubMed

Damodaran, Srinivasan

2015-01-01

Many life-sustaining activities in living cells occur at the membrane-water interface. The pertinent questions that we need to ask are, what are the evolutionary reasons in biology for choosing the membrane-water interface as the site for performing and/or controlling crucial biological reactions, and what is the key physical principle that is very singular to the membrane-water interface that biology exploits for regulating metabolic processes in cells? In this chapter, a hypothesis is developed, which espouses that cells control activities of membrane-bound enzymes through manipulation of the thermodynamic activity of water in the lipid-water interfacial region. The hypothesis is based on the fact that the surface pressure of a lipid monolayer is a direct measure of the thermodynamic activity of water at the lipid-water interface. Accordingly, the surface pressure-dependent activation or inactivation of interfacial enzymes is directly related to changes in the thermodynamic activity of interfacial water. Extension of this argument suggests that cells may manipulate conformations (and activities) of membrane-bound enzymes by manipulating the (re)activity of interfacial water at various locations in the membrane by localized compression or expansion of the interface. In this respect, cells may use the membrane-bound hormone receptors, lipid phase transition, and local variations in membrane lipid composition as effectors of local compression and/or expansion of membrane, and thereby local water activity. Several experimental data in the literature will be reexamined in the light of this hypothesis.

Hydrologic characteristics and possible effects of surface mining in the northwestern part of West Branch Antelope Creek basin, Mercer County, North Dakota

USGS Publications Warehouse

Crawley, Mark E.; Emerson, Douglas G.

1981-01-01

Lignite beds and abundant discontinuous sandstone beds of the Paleocene Sentinel Butte Member of the Fort Union Formation and sand and gravel beds in the Quarternary glaciofluvial deposits (Antelope Creek aquifer) are the most important aquifers for domestic and livestock water supplies in the West Branch Antelope Creek basin. In the Beulah-Zap lignite, ground water moves from highland area in the west toward the Antelope Creek aquifer. Water levels in the basal Sentinel Butte sandstone appear to be controlled by the level of Lake Sakakawea. In the glaciofluvial deposits of the Antelope Creek aquifer water moves from a ground-water divide northwestward to Lake Sakakawea and southeastward toward the Knife River. Large water-level declines in wells completed in the lignite and shallower aquifers could be expected with mining. The effects probably would be limited to within 1 to 2 miles of an active mine. Surface-runoff duration could be altered by increased infiltration and retention in the reclaimed are and possible temporal extension of base flow could occur. Shallow ground water beneath mine sites would be expected to increase in dissolved solids and locally to contain large sodium and sulfate concentrations. In some locations movement of poor quality water toward the Antelope Creek aquifer would be expected. (USGS)

Lipase hydration state in the gas phase: sorption isotherm measurements and inverse gas chromatography.

PubMed

Marton, Zsuzsanna; Chaput, Ludovic; Pierre, Guillaume; Graber, Marianne

2010-11-01

The adsorption of water and substrate on immobilized Candida antarctica lipase B was studied by performing adsorption isotherm measurements and using inverse gas chromatography (IGC). Water adsorption isotherm of the immobilized enzyme showed singular profile absorption incompatible with the Brunauer-Emmet-Teller model, probably due to the hydrophobic nature of the support, leading to very low interactions with water. IGC allowed determining the evolution with water thermodynamic activity (a(W)) of both dispersive surface energies and acidity and basicity constants of immobilized enzyme. These results showed that water molecules progressively covered immobilized enzyme, when increasing a(W), leading to a saturation of polar groups above a(W) 0.1 and full coverage of the surface above a(W) 0.25. IGC also enabled relevant experiments to investigate the behavior of substrates under a(W) that they will experience, in a competitive situation with water. Results indicated that substrates had to displace water molecules in order to adsorb on the enzyme from a(W) values ranging from 0.1 to 0.2, depending on the substrate. As the conditions used for these adsorption studies resemble the ones of the continuous enzymatic solid/gas reactor, in which activity and selectivity of the lipase were extensively studied, it was possible to link adsorption results with particular effects of water on enzyme properties.

210Pb in the western Indian Ocean: distribution, disequilibrium, and partitioning between dissolved and particulate phases

NASA Astrophysics Data System (ADS)

Chung, Y.

1987-09-01

Dissolved 210Pb profiles are presented for 13 GEOSECS stations in the western Indian Ocean. In surface water away from high southern latitudes, 210Pb is in excess over 226Ra due to the atmospheric fallout from decay of 222Rn. Except in the Circumpolar region, the dissolved 210Pb profiles display a gentle mid-depth maximum similar to the corresponding 226Ra profiles. The 210Pb/ 226Ra activity ratio ranges from 1.6 in the surface water east of Madagascar to 0.4 or less in the bottom water of all the basins. The lowest ratio observed was 0.1 in the Gulf of Aden very close to the continental land mass. A ratio of 0.6 divides the western Indian Ocean horizontally into two portions, with the contour at shallower depth in the north than in the south. The deep water disequilibrium is thus more extensive north of Madagascar than south of it. It appears that locality and bottom topography play a strong role in controlling the distributions of 210Pb and 226Ra as well as their extent of disequilibrium in the water column. The mean residence time for Pb with respect to particulate and boundary scavenging in the deep water ranges from about 15 to 75 years.

Southern Florida's River of Grass

NASA Technical Reports Server (NTRS)

2002-01-01

Florida's Everglades is a region of broad, slow-moving sheets of water flowing southward over low-lying areas from Lake Okeechobeeto the Gulf of Mexico. In places this remarkable 'river of grass' is 80 kilometers wide. These images from the Multi-angle Imaging SpectroRadiometer show the Everglades region on January 16, 2002. Each image covers an area measuring 191 kilometers x 205 kilometers. The data were captured during Terra orbit 11072.

On the left is a natural color view acquired by MISR's nadir camera. A portion of Lake Okeechobee is visible at the top, to the right of image center. South of the lake, whose name derives from the Seminole word for 'big water,' an extensive region of farmland known as the Everglades Agricultural Area is recognizable by its many clustered squares. Over half of the sugar produced in United States is grown here. Urban areas along the east coast and in the northern part of the image extend to the boundaries of Big Cypress Swamp, situated north of Everglades National Park.

The image on the right combines red-band data from the 46-degree backward, nadir and 46-degree forward-viewing camera angles to create a red, green, blue false-color composite. One of the interesting uses of the composite image is for detecting surface water. Wet surfaces appear blue in this rendition because sun glitter produces a greater signal at the forward camera's view angle. Wetlands visible in these images include a series of shallow impoundments called Water Conservation Areas which were built to speed water flow through the Everglades in times of drought. In parts of the Everglades, these levees and extensive systems such as the Miami and Tamiami Canals have altered the natural cycles of water flow. For example, the water volume of the Shark River Slough, a natural wetland which feeds Everglades National Park, is influenced by the Tamiami Canal. The unique and intrinsic value of the Everglades is now widely recognized, and efforts to restore the natural water cycles are underway.

Flexible conformable hydrophobized surfaces for turbulent flow drag reduction

PubMed Central

Brennan, Joseph C; Geraldi, Nicasio R; Morris, Robert H; Fairhurst, David J; McHale, Glen; Newton, Michael I

2015-01-01

In recent years extensive work has been focused onto using superhydrophobic surfaces for drag reduction applications. Superhydrophobic surfaces retain a gas layer, called a plastron, when submerged underwater in the Cassie-Baxter state with water in contact with the tops of surface roughness features. In this state the plastron allows slip to occur across the surface which results in a drag reduction. In this work we report flexible and relatively large area superhydrophobic surfaces produced using two different methods: Large roughness features were created by electrodeposition on copper meshes; Small roughness features were created by embedding carbon nanoparticles (soot) into Polydimethylsiloxane (PDMS). Both samples were made into cylinders with a diameter under 12 mm. To characterize the samples, scanning electron microscope (SEM) images and confocal microscope images were taken. The confocal microscope images were taken with each sample submerged in water to show the extent of the plastron. The hydrophobized electrodeposited copper mesh cylinders showed drag reductions of up to 32% when comparing the superhydrophobic state with a wetted out state. The soot covered cylinders achieved a 30% drag reduction when comparing the superhydrophobic state to a plain cylinder. These results were obtained for turbulent flows with Reynolds numbers 10,000 to 32,500. PMID:25975704

Experimental Investigation on the Basic Law of the Fracture Spatial Morphology for Water Pressure Blasting in a Drillhole Under True Triaxial Stress

NASA Astrophysics Data System (ADS)

Huang, Bingxiang; Li, Pengfeng

2015-07-01

The present literature on the morphology of water pressure blasting fractures in drillholes is not sufficient and does not take triaxial confining stress into account. Because the spatial morphology of water pressure blasting fractures in drillholes is not clear, the operations lack an exact basis. Using a large true triaxial water pressure blasting experimental system and an acoustic emission 3-D positioning system, water pressure blasting experiments on cement mortar test blocks (300 mm × 300 mm × 300 mm) were conducted to study the associated basic law of the fracture spatial morphology. The experimental results show that water pressure blasting does not always generate bubble pulsation. After water pressure blasting under true triaxial stress, a crushed compressive zone and a blasting fracture zone are formed from the inside, with the blasting section of the naked drillhole as the center, to the outside. The shape of the outer edges of the two zones is ellipsoidal. The range of the blasting fracture is large in the radial direction of the drillhole, where the surrounding pressure is large, i.e., the range of the blasting fracture in the drillhole radial cross-section is approximately ellipsoidal. The rock near the drillhole wall is affected by a tensile stress wave caused by the test block boundary reflection, resulting in more flake fractures appearing in the fracturing crack surface in the drillhole axial direction and parallel to the boundary surface. The flake fracture is thin, presenting a small-range flake fracture. The spatial morphology of the water pressure blasting fracture in the drillhole along the axial direction is similar to a wide-mouth Chinese bottle: the crack extent is large near the drillhole orifice, gradually narrows inward along the drillhole axial direction, and then increases into an approximate ellipsoid in the internal naked blasting section. Based on the causes of the crack generation, the blasting cracks are divided into three zones: the blasting shock zone, the axial extension zone, and the orifice influence zone. The explosion shock zone is the range that is directly impacted by the explosive shock waves. The axial extension zone is the axial crack area with uniform width, which is formed when the blasting fracture in the edge of the explosion shock zone extends along the drillhole wall. The extension of the orifice influence zone is very large because the explosion stress waves reflect at the free face and generate tensile stress waves. In the water pressure blasting of the drillhole, the sealing section should be lengthened to allow the drillhole blasting cracks to extend sufficiently under the long-time effect of the blasting stress field of quasi-hydrostatic pressure.

Indicating anthropogenic effectson urban water system - indicators and extension

NASA Astrophysics Data System (ADS)

Strauch, G.; Ufz-Team

2003-04-01

Urban water systems are polluted by diffusive and direct contribution of anthropogenic activities. Besides industrial contaminants like aromatic and chlorinated HC and other persistent organic compounds, the urban aquatic environment is increasingly polluted by low concentrated but high eco-toxic compounds as pharmaceuticals, fragrances, plasticizers which most have disrupt endocrine functions, and trace elements carried in by surface and sub-surface waste water and seeping processes. This contamination could have a longtime impact on the urban ecosystem and on the human health. The interdisciplinary project on risk assessment of water pollution was initiated to explore new methodologies for assessing human activities on the urban water system and processes among urban watersheds. In a first assumption we used a flow model concept with in- and output and surface water transport represented by the city of Halle, Germany, and the river Saale. The river Saale acts as surface water system collecting waste water inputs along the city traverse. We investigated the anthropogenic effect on the urban water system using the indicators hydrological parameters, compound specific pattern of complex organic substances and trace elements, isotopic signatures of water (H, O) and dissolved substances (sulfate, DIC, nitrate), pathogens, and microbiota. A first balance modeling showed that main ions are not very sensitive concerning the direct urban input into the river. Depending on the discharge of the river in high and low flood stages the load of dissolved matter has no specific urban effect. However, the concentration pattern of fragrances (tonalid, galaxolid) and endocrine disrupters (t-nonylphenol) point to a different pollution along the city traverse: downstream of the sewage plant a higher load was observed in comparison to the upstream passage. Furthermore, a degradation ability of fungi and bacteria occurred in the bank sediments could be detected in lab experiments concerning the fragrances, and endocrine disrupters (t-nonylphenol, phthalate). The Saale water samples contain components able to eco-toxic and immunomodulated effects as measured on the vitality and cytokine-secretion profile of human peripheral blood mononuclear cells (PBMC). Even fragrances caused such effects which are unknown so far. The study of assessing urban effects onto the water system is still under investigation.

Local feedback mechanisms of the shallow water region around the Maritime Continent

NASA Astrophysics Data System (ADS)

Xue, Pengfei; Eltahir, Elfatih A. B.; Malanotte-Rizzoli, Paola; Wei, Jun

2014-10-01

The focus of this study is the local-scale air-sea feedback mechanisms over the shallow shelf water region (water depth <200 m) of the Maritime Continent (MC). MC was selected as a pilot study site for its extensive shallow water coverage, geographic complexity, and importance in the global climate system. To identify the local-scale air-sea feedback processes, we ran numerical experiments with perturbed surface layer water temperature using a coupled ocean-atmosphere model and an uncoupled ocean model. By examining the responses of the coupled and uncoupled models to the water temperature perturbation, we identify that, at a local-scale, a negative feedback process through the coupled dynamics that tends to restore the SST from its perturbation could dominate the shallow water region of the MC at a short time scale of several days. The energy budget shows that 38% of initial perturbation-induced heat energy was adjusted through the air-sea feedback mechanisms within 2 weeks, of which 58% is directly transferred into the atmosphere by the adjustment of latent heat flux due to the evaporative cooling mechanism. The increased inputs of heat and moisture into the lower atmosphere then modifies its thermal structure and increases the formation of low-level clouds, which act as a shield preventing incoming solar radiation from reaching the sea surface, accounts for 38% of the total adjustment of surface heat fluxes, serving as the second mechanism for the negative feedback process. The adjustment of sensible heat flux and net longwave radiation play a secondary role. The response of the coupled system to the SST perturbation suggests a response time scale of the coupled feedback process of about 3-5 days. The two-way air-sea feedback tightly links the surface heat fluxes, clouds and SST, and can play an important role in regulating the short-term variability of the SST over the shallow shelf water regions.

Conditions on Early Mars Might Have Fostered Rapid and Early Development of Life

NASA Technical Reports Server (NTRS)

Gibson, Everett K.; McKay, David S.; Thomas-Keprta, Kathie L.; Clemett, Simon J.; Wentworth, Susan J.

2007-01-01

The exploration of Mars during the past decades has begun to unveil the history of the planet. The combinations of remote sensing, in situ geochemical compositional measurements and photographic observations from both above and on the surface have shown Mars to have a dynamic and active geologic evolution. Mars geologic evolution clearly had conditions that were suitable for supporting life. For a planet to be able to be habitable, it must have water, carbon sources, energy sources and a dynamic geologic past. Mars meets all of these requirements. The first 600 My of Martian history were ripe for life to develop because of the abundance of (i) Water-carved canyons and oceans or lakes with the early presence of near surface water shown by precipitated carbonates in ALH84001 well-dated at approx.3.9 Gy., (ii) Energy from the original accretional processes, a molten core which generated a strong magnetic field leaving a permanent record in the early crust, early active volcanism continuing throughout Martian history, and, and continuing impact processes, (iii) Carbon and water from possibly extensive volcanic outgassing (i.e. H2O, CO2, CH4, CO, O2, N2, H2S, SO2, etc.) and (iv) some crustal tectonics as revealed by faulting and possible plate movement reflected by the magnetic pattern in the crust. The question arises: "Why would life not evolve from these favorable conditions on early Mars in its first 600 My?" During this period, it seems likely that environmental near-surface conditions on Mars were more favorable to life than at any later time. Standing bodies of water, precipitation and flowing surface water, and possibly abundant hydrothermal energy would all favor the formation of early life. Even if life developed elsewhere (on Earth, Venus, or on other solar systems) and was transported to Mars, the surface conditions were likely very hospitable for that introduced life to multiply and evolve.

Water development for phosphate mining in a karst setting in Florida—a complex environmental problem

NASA Astrophysics Data System (ADS)

Lamoreaux, P. E.

1989-09-01

The State of Florida, U.S.A., passed legislation in the early 1970s and developed regulations applied to large withdrawals of groundwater. These regulations require strict adherence to defining the impact on surface water, shallow Surficial Aquifers, and the deeper aquifers within the Floridan Aquifer System. These regulations require the development of a Regional Impact Statement and a Consumptive Use Permit. To meet these requirements it is necessary to perform surface- and groundwater studies, extensive pumping tests and the collection of detailed monitoring and water quality data. These permits fall under the jurisdiction of the Florida Department of Environmental Regulations and are administrated under Regional Water Management districts, such as the Southwest Florida Management District. These regional district offices have a regulatory hearing board, hold public hearings that are properly advertized, and have support staffs of geologists, engineers, chemists, and biologists. The Florida Code involved required that, “The water crop, in the absence of data to the contrary, is 1,000 gallons per day per acre.” A “5—3—1 Criteria” also applies that requires that a determination be made to show that there will not be more than a 5 foot average decline in water level in the Floridan Aquifer at the boundary of a property to be developed, not more than a 3-foot decline in the Surficial Aquifer at the boundary, and no more than a 1-foot decline in the nearest water body (pond, lake, etc.). In addition, surface-water flow in streams of the area must not be decreased more than 5 percent unless a variance to the rule is obtained. The hydrogeological work required to meet these regulations is described in the following report.

Deflection of natural oil droplets through the water column in deep-water environments: The case of the Lower Congo Basin

NASA Astrophysics Data System (ADS)

Jatiault, Romain; Dhont, Damien; Loncke, Lies; de Madron, Xavier Durrieu; Dubucq, Dominique; Channelliere, Claire; Bourrin, François

2018-06-01

Numerous recurrent seep sites were identified in the deep-water environment of the Lower Congo Basin from the analysis of an extensive dataset of satellite-based synthetic-aperture radar images. The integration of current data was used to link natural oil slicks with active seep-related seafloor features. Acoustic Doppler current profiler measurements across the water column provided an efficient means to evaluate the horizontal deflection of oil droplets rising through the water column. Eulerian propagation model based on a range of potential ascension velocities helped to approximate the path for rising oil plume through the water column using two complementary methods. The first method consisted in simulating the reversed trajectory of oil droplets between sea-surface oil slick locations observed during current measurements and seep-related seafloor features while considering a range of ascension velocities. The second method compared the spatial spreading of natural oil slicks from 21 years of satellite monitoring observations for water depths ranging from 1200 to 2700 m against the modeled deflections during the current measurement period. The mapped oil slick origins are restricted to a 2.5 km radius circle from associated seep-related seafloor features. The two methods converge towards a range of ascension velocities for oil droplets through the water column, estimated between 3 and 8 cm s-1. The low deflection values validate that the sub-vertical projection of the average surface area of oil slicks at the sea surface can be used to identify the origin of expelled hydrocarbon from the seafloor, which expresses as specific seafloor disturbances (i.e. pockmarks or mounds) known to expel fluids.

Boundary layers of aqueous surfactant and block copolymer solutions against hydrophobic and hydrophilic solid surfaces

NASA Astrophysics Data System (ADS)

Steitz, Roland; Schemmel, Sebastian; Shi, Hongwei; Findenegg, Gerhard H.

2005-03-01

The boundary layer of aqueous surfactants and amphiphilic triblock copolymers against flat solid surfaces of different degrees of hydrophobicity was investigated by neutron reflectometry (NR), grazing incidence small angle neutron scattering (GISANS) and atomic force microscopy (AFM). Solid substrates of different hydrophobicities were prepared by appropriate surface treatment or by coating silicon wafers with polymer films of different chemical natures. For substrates coated with thin films (20-30 nm) of deuterated poly(styrene) (water contact angle \\theta_{\\mathrm {w}} \\approx 90^\\circ ), neutron reflectivity measurements on the polymer/water interface revealed a water depleted liquid boundary layer of 2-3 nm thickness and a density about 90% of the bulk water density. No pronounced depletion layer was found at the interface of water against a less hydrophobic polyelectrolyte coating (\\theta_{\\mathrm {w}} \\approx 63^\\circ ). It is believed that the observed depletion layer at the hydrophobic polymer/water interface is a precursor of the nanobubbles which have been observed by AFM at this interface. Decoration of the polymer coatings by adsorbed layers of nonionic CmEn surfactants improves their wettability by the aqueous phase at surfactant concentrations well below the critical micellar concentration (CMC) of the surfactant. Here, GISANS experiments conducted on the system SiO2/C8E4/D2O reveal that there is no preferred lateral organization of the C8E4 adsorption layers. For amphiphilic triblock copolymers (PEO-PPO-PEO) it is found that under equilibrium conditions they form solvent-swollen brushes both at the air/water and the solid/water interface. In the latter case, the brushes transform to uniform, dense layers after extensive rinsing with water and subsequent solvent evaporation. The primary adsorption layers maintain properties of the precursor brushes. In particular, their thickness scales with the number of ethylene oxide units (EO) of the block copolymer. In the case of dip-coating without subsequent rinsing, surface patterns of the presumably crystalline polymer on top of the primary adsorption layer develop upon drying under controlled conditions. The morphology depends mainly on the nominal surface coverage with the triblock copolymer. Similar morphologies are found on bare and polystyrene-coated silicon substrates, indicating that the surface patterning is mainly driven by segregation forces within the polymer layers and not by interactions with the substrate.

Polyamide desalination membrane characterization and surface modification to enhance fouling resistance.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, Mukul M.; Freeman, Benny D.; Van Wagner, Elizabeth M.

2010-08-01

The market for polyamide desalination membranes is expected to continue to grow during the coming decades. Purification of alternative water sources will also be necessary to meet growing water demands. Purification of produced water, a byproduct of oil and gas production, is of interest due to its dual potential to provide water for beneficial use as well as to reduce wastewater disposal costs. However, current polyamide membranes are prone to fouling, which decreases water flux and shortens membrane lifetime. This research explored surface modification using poly(ethylene glycol) diglycidyl ether (PEGDE) to improve the fouling resistance of commercial polyamide membranes. Characterizationmore » of commercial polyamide membrane performance was a necessary first step before undertaking surface modification studies. Membrane performance was found to be sensitive to crossflow testing conditions. Concentration polarization and feed pH strongly influenced NaCl rejection, and the use of continuous feed filtration led to higher water flux and lower NaCl rejection than was observed for similar tests performed using unfiltered feed. Two commercial polyamide membranes, including one reverse osmosis and one nanofiltration membrane, were modified by grafting PEGDE to their surfaces. Two different PEG molecular weights (200 and 1000) and treatment concentrations (1% (w/w) and 15% (w/w)) were studied. Water flux decreased and NaCl rejection increased with PEGDE graft density ({micro}g/cm{sup 2}), although the largest changes were observed for low PEGDE graft densities. Surface properties including hydrophilicity, roughness and charge were minimally affected by surface modification. The fouling resistance of modified and unmodified membranes was compared in crossflow filtration studies using model foulant solutions consisting of either a charged surfactant or an oil in water emulsion containing n-decane and a charged surfactant. Several PEGDE-modified membranes demonstrated improved fouling resistance compared to unmodified membranes of similar initial water flux, possibly due to steric hindrance imparted by the PEG chains. Fouling resistance was higher for membranes modified with higher molecular weight PEG. Fouling was more extensive for feeds containing the cationic surfactant, potentially due to electrostatic attraction with the negatively charged membranes. However, fouling was also observed in the presence of the anionic surfactant, indicating hydrodynamic forces are also responsible for fouling.« less

A bootstrap method for estimating uncertainty of water quality trends

USGS Publications Warehouse

Hirsch, Robert M.; Archfield, Stacey A.; DeCicco, Laura

2015-01-01

Estimation of the direction and magnitude of trends in surface water quality remains a problem of great scientific and practical interest. The Weighted Regressions on Time, Discharge, and Season (WRTDS) method was recently introduced as an exploratory data analysis tool to provide flexible and robust estimates of water quality trends. This paper enhances the WRTDS method through the introduction of the WRTDS Bootstrap Test (WBT), an extension of WRTDS that quantifies the uncertainty in WRTDS-estimates of water quality trends and offers various ways to visualize and communicate these uncertainties. Monte Carlo experiments are applied to estimate the Type I error probabilities for this method. WBT is compared to other water-quality trend-testing methods appropriate for data sets of one to three decades in length with sampling frequencies of 6–24 observations per year. The software to conduct the test is in the EGRETci R-package.

What can nuclear collisions teach us about the boiling of water or the formation of multi-star systems

NASA Astrophysics Data System (ADS)

Gross, D. H. E.

2001-11-01

Phase transitions in nuclei, small atomic clusters and self-gravitating systems demand the extension of thermo-statistics to "Small" systems. The main obstacle is the thermodynamic limit. It is shown how the original definition of the entropy by Boltzmann as the volume of the energy-manifold of the N-body phase space allows a geometrical definition of the entropy as function of the conserved quantities. Without invoking the thermodynamic limit the whole "zoo" of phase transitions and critical points/lines can be unambiguously defined. The relation to the Yang-Lee singularities of the grand-canonical partition sum is pointed out. It is shown that just phase transitions in non-extensive systems give the complete set of characteristic parameters of the transition including the surface tension. Nuclear heavy-ion collisions are an experimental playground to explore this extension of thermo-statistics

Extended principle component analysis - a useful tool to understand processes governing water quality at catchment scales

NASA Astrophysics Data System (ADS)

Selle, B.; Schwientek, M.

2012-04-01

Water quality of ground and surface waters in catchments is typically driven by many complex and interacting processes. While small scale processes are often studied in great detail, their relevance and interplay at catchment scales remain often poorly understood. For many catchments, extensive monitoring data on water quality have been collected for different purposes. These heterogeneous data sets contain valuable information on catchment scale processes but are rarely analysed using integrated methods. Principle component analysis (PCA) has previously been applied to this kind of data sets. However, a detailed analysis of scores, which are an important result of a PCA, is often missing. Mathematically, PCA expresses measured variables on water quality, e.g. nitrate concentrations, as linear combination of independent, not directly observable key processes. These computed key processes are represented by principle components. Their scores are interpretable as process intensities which vary in space and time. Subsequently, scores can be correlated with other key variables and catchment characteristics, such as water travel times and land use that were not considered in PCA. This detailed analysis of scores represents an extension of the commonly applied PCA which could considerably improve the understanding of processes governing water quality at catchment scales. In this study, we investigated the 170 km2 Ammer catchment in SW Germany which is characterised by an above average proportion of agricultural (71%) and urban (17%) areas. The Ammer River is mainly fed by karstic springs. For PCA, we separately analysed concentrations from (a) surface waters of the Ammer River and its tributaries, (b) spring waters from the main aquifers and (c) deep groundwater from production wells. This analysis was extended by a detailed analysis of scores. We analysed measured concentrations on major ions and selected organic micropollutants. Additionally, redox-sensitive variables and environmental tracers indicating groundwater age were analysed for deep groundwater from production wells. For deep groundwater, we found that microbial turnover was stronger influenced by local availability of energy sources than by travel times of groundwater to the wells. Groundwater quality primarily reflected the input of pollutants determined by landuse, e.g. agrochemicals. We concluded that for water quality in the Ammer catchment, conservative mixing of waters with different origin is more important than reactive transport processes along the flow path.

January 2016 extensive summer melt in West Antarctica favoured by strong El Niño

DOE PAGES

Nicolas, Julien P.; Vogelmann, Andrew M.; Scott, Ryan C.; ...

2017-06-15

Over the past two decades the primary driver of mass loss from the West Antarctic Ice Sheet (WAIS) has been warm ocean water underneath coastal ice shelves, not a warmer atmosphere. Yet, surface melt occurs sporadically over low-lying areas of the WAIS and is not fully understood. Here we report on an episode of extensive and prolonged surface melting observed in the Ross Sea sector of the WAIS in January 2016. A comprehensive cloud and radiation experiment at the WAIS ice divide, downwind of the melt region, provided detailed insight into the physical processes at play during the event. Themore » unusual extent and duration of the melting are linked to strong and sustained advection of warm marine air toward the area, likely favoured by the concurrent strong El Niño event. Finally, the increase in the number of extreme El Niño events projected for the twenty-first century could expose the WAIS to more frequent major melt events.« less

January 2016 extensive summer melt in West Antarctica favoured by strong El Niño

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nicolas, Julien P.; Vogelmann, Andrew M.; Scott, Ryan C.

Over the past two decades the primary driver of mass loss from the West Antarctic Ice Sheet (WAIS) has been warm ocean water underneath coastal ice shelves, not a warmer atmosphere. Yet, surface melt occurs sporadically over low-lying areas of the WAIS and is not fully understood. Here we report on an episode of extensive and prolonged surface melting observed in the Ross Sea sector of the WAIS in January 2016. A comprehensive cloud and radiation experiment at the WAIS ice divide, downwind of the melt region, provided detailed insight into the physical processes at play during the event. Themore » unusual extent and duration of the melting are linked to strong and sustained advection of warm marine air toward the area, likely favoured by the concurrent strong El Niño event. Finally, the increase in the number of extreme El Niño events projected for the twenty-first century could expose the WAIS to more frequent major melt events.« less

January 2016 extensive summer melt in West Antarctica favoured by strong El Niño

NASA Astrophysics Data System (ADS)

Nicolas, Julien P.; Vogelmann, Andrew M.; Scott, Ryan C.; Wilson, Aaron B.; Cadeddu, Maria P.; Bromwich, David H.; Verlinde, Johannes; Lubin, Dan; Russell, Lynn M.; Jenkinson, Colin; Powers, Heath H.; Ryczek, Maciej; Stone, Gregory; Wille, Jonathan D.

2017-06-01

Over the past two decades the primary driver of mass loss from the West Antarctic Ice Sheet (WAIS) has been warm ocean water underneath coastal ice shelves, not a warmer atmosphere. Yet, surface melt occurs sporadically over low-lying areas of the WAIS and is not fully understood. Here we report on an episode of extensive and prolonged surface melting observed in the Ross Sea sector of the WAIS in January 2016. A comprehensive cloud and radiation experiment at the WAIS ice divide, downwind of the melt region, provided detailed insight into the physical processes at play during the event. The unusual extent and duration of the melting are linked to strong and sustained advection of warm marine air toward the area, likely favoured by the concurrent strong El Niño event. The increase in the number of extreme El Niño events projected for the twenty-first century could expose the WAIS to more frequent major melt events.

Airborne Tomographic Swath Ice Sounding Processing System

NASA Technical Reports Server (NTRS)

Wu, Xiaoqing; Rodriquez, Ernesto; Freeman, Anthony; Jezek, Ken

2013-01-01

Glaciers and ice sheets modulate global sea level by storing water deposited as snow on the surface, and discharging water back into the ocean through melting. Their physical state can be characterized in terms of their mass balance and dynamics. To estimate the current ice mass balance, and to predict future changes in the motion of the Greenland and Antarctic ice sheets, it is necessary to know the ice sheet thickness and the physical conditions of the ice sheet surface and bed. This information is required at fine resolution and over extensive portions of the ice sheets. A tomographic algorithm has been developed to take raw data collected by a multiple-channel synthetic aperture sounding radar system over a polar ice sheet and convert those data into two-dimensional (2D) ice thickness measurements. Prior to this work, conventional processing techniques only provided one-dimensional ice thickness measurements along profiles.

Increased exposure of Southern Ocean phytoplankton to ultraviolet radiation

NASA Astrophysics Data System (ADS)

Lubin, Dan; Arrigo, Kevin R.; van Dijken, Gert L.

2004-05-01

Satellite remote sensing of both surface solar ultraviolet radiation (UVR) and chlorophyll over two decades shows that biologically significant ultraviolet radiation increases began to occur over the Southern Ocean three years before the ozone ``hole'' was discovered. Beginning in October 1983, the most frequent occurrences of enhanced UVR over phytoplankton-rich waters occurred in the Weddell Sea and Indian Ocean sectors of the Southern Ocean, impacting 60% of the surface biomass by the late 1990s. These results suggest two reasons why more serious impacts to the base of the marine food web may not have been detected by field experiments: (1) the onset of UVR increases several years before dedicated field work began may have impacted the most sensitive organisms long before such damage could be detected, and (2) most biological field work has so far not taken place in Antarctic waters most extensively subjected to enhanced UVR.

Complete characterization of the water dimer vibrational ground state and testing the VRT(ASP-W)III, SAPT-5st, and VRT(MCY-5f) surfaces

NASA Astrophysics Data System (ADS)

Keutsch, Frank N.; Goldman, Nir; Harker, Heather A.; Leforestier, Claude; Saykally, Richard J.

We report the observation of extensive a- and c-type rotation-tunnelling (RT) spectra of (H2O)2 for Ka =0-3, and (D2O)2 for Ka =0-4. These data allow a detailed characterization of the vibrational ground state to energies comparable to those of the low-lying (70-80 cm-1) intermolecular vibrations. We present a comparison of the experimentally determined molecular constants and tunnelling splittings with those calculated on the VRT(ASP-W)III, SAPT-5st, and VRT(MCY-5f) intermolecular potential energy surfaces. The SAPT-5st potential reproduces the vibrational ground state properties of the water dimer very well. The VRT(MCY-5f) and especially the VRT(ASP-W)III potentials show larger disagreements, in particular for the bifurcation tunnelling splitting.

Plan of study for the regional aquifer-system analysis of the San Juan structural basin, New Mexico, Colorado, Arizona, and Utah

USGS Publications Warehouse

Welder, G.E.

1986-01-01

The San Juan structural basin is an 18,000 sq mi area that contains several extensive aquifers. The basin includes three surface drainage basins and parts of New Mexico, Colorado, Arizona, and Utah. Surface water in the area is fully appropriated, and the steadily increasing demand for groundwater has resulted in water supply concerns. Competition is great between mining and electric power companies, municipalities, and Indian communities for the limited groundwater supplies. This report outlines a 4-year plan for a study of the regional aquifer system in the San Juan structural basin. The purposes of the study are to define and understand the aquifer system; to assess the effects of groundwater use on the aquifers and streams; and to determine the availability and quality of groundwater in the basin. (Author 's abstract)

Band Formation and Ocean-Surface Interaction on Europa and Ganymede

NASA Astrophysics Data System (ADS)

Howell, Samuel M.; Pappalardo, Robert T.

2018-05-01

Geologic activity in the outer H2O ice shells of Europa and Ganymede, Galilean moons of Jupiter, may facilitate material exchange between global water oceans and the icy surface, fundamentally affecting potential habitability and the future search for life. Spacecraft imagery reveals surfaces rich with tectonic bands, predominantly attributed to the extension of brittle ice overlaying a convecting ice layer. However, the details of band-forming processes and links to potential ocean-surface exchange have remained elusive. We simulate ice shell faulting and convection with two-dimensional numerical models and track the movement of "fossil" ocean material frozen into the base of the ice shell and deformed through geologic time. We find that distinct band types form within a spectrum of extensional terrains correlated to lithosphere strength, governed by lithosphere thickness and cohesion. Furthermore, we find that smooth bands formed in weak lithosphere promote exposure of fossil ocean material at the surface.

Geothermal potential on Kirtland Air Force Base lands, Bernalillo County, New Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grant, P.R. Jr.

Extensive sampling and geochemical analysis of groundwater in and near the base disclosed no significant geothermal parameters. However, structural conditions and current hydrologic regimes strongly suggest that thermal waters would be masked by near surface, low temperature meteoric water originating as rain and snowfall in the nearby mountains. Controlled source audio-magnetotelluric (CSAMT) electromagnetic techniques, refraction seismic experiments, and gravity traverses were utilized on the base. These, together with published geohysical information that presents evidence for a shallow magma body beneath the Albuquerque Basin; favorable terrestrial heat flow, water chemistry, and shallow temperature gradient holes on the nearby mesa west ofmore » the Rio Grande; interpretation of regional gravity data; and geological data from nearby deep wells tend to confirm structural, stratigraphic, and hydrologic conditions favorable for developing an extensive intermediate to high-temperature hydrothermal regime on portions of Kirtland AFB lands where intensive land use occurs. Two possible exploration and development scenarios are presented. One involves drilling a well to a depth of 3000 to 5000 ft (914 to 1524 m) to test the possibility of encountering higher than normal water temperatures on the basinward side of the faults underlying the travertine deposits. The other is to conduct limited reflection seismograph surveys in defined areas on the base to determine the depth to basement (granite) and thickness of the overyling, unconfined, water filled, relatively unconsolidated sand and gravel aquifer.« less

Food safety/food security aspects related to the environmental release of pharmaceuticals.

PubMed

Brambilla, Gianfranco; Testa, Cecilia

2014-11-01

The environmental presence of pharmaceuticals in top soil and in water where extensive animal farming occurs may represent an involuntary source of residues in food that might affect both food safety and food security. We modelled the presence of residues in animal matrices from the inventoried environmental concentration of selected drugs in surface waters (range: 0.1-10μgL(-1)) and agriculture soils (range: 1-100μgkg(-1) dry weight), accounting for animal production parameters (i.e., forages, water intake and milk and egg production) and drug pharmacokinetics. The results indicate that the contamination of tetracyclines in top soil may represent a major issue both for the compliance with maximum residue levels in food (100-300ngg(-1)) and for the claim of organic products. via surface water, animals may be vulnerable to the intake of anabolics and growth-promoting agents, such as 17-beta estradiol and clenbuterol, only under a worst-case scenario. Their identification, which is currently achievable at a pgg(-1) level in animal specimens, is considered proof of illegal treatment and can lead to the prosecution of farmers. The Environmental Quality Standards that have been proposed for priority substances in surface waters may also be considered protective in terms of food security/food safety; however, a broad-spectrum characterisation of drugs within the agriculture context could be envisaged to refine the uncertainties in the risk assessment and for combined intakes. Copyright © 2014 Elsevier Ltd. All rights reserved.

Agricultural peat lands; towards a greenhouse gas sink - a synthesis of a Dutch landscape study

NASA Astrophysics Data System (ADS)

Schrier-Uijl, A. P.; Kroon, P. S.; Hendriks, D. M. D.; Hensen, A.; Van Huissteden, J. C.; Leffelaar, P. A.; Berendse, F.; Veenendaal, E. M.

2013-06-01

It is generally known that managed, drained peatlands act as carbon sources. In this study we examined how mitigation through the reduction of management and through rewetting may affect the greenhouse gas (GHG) emission and the carbon balance of intensively managed, drained, agricultural peatlands. Carbon and GHG balances were determined for three peatlands in the western part of the Netherlands from 2005 to 2008 by considering spatial and temporal variability of emissions (CO2, CH4 and N2O). One area (Oukoop) is an intensively managed grass-on-peatland, including a dairy farm, with the ground water level at an average annual depth of 0.55 m below the soil surface. The second area (Stein) is an extensively managed grass-on-peatland, formerly intensively managed, with a dynamic ground water level at an average annual depth of 0.45 m below the soil surface. The third area is an (since 1998) rewetted former agricultural peatland (Horstermeer), close to Oukoop and Stein, with the average annual ground water level at a depth of 0.2 m below the soil surface. During the measurement campaigns we found that both agriculturally managed sites acted as carbon and GHG sources but the rewetted agricultural peatland acted as a carbon and GHG sink. The terrestrial GHG source strength was 1.4 kg CO2-eq m-2 yr-1 for the intensively managed area and 1.0 kg CO2-eq m-2 yr-1 for the extensively managed area; the unmanaged area acted as a GHG sink of 0.7 kg CO2-eq m-2 yr-1. Water bodies contributed significantly to the terrestrial GHG balance because of a high release of CH4 and the loss of DOC only played a minor role. Adding the farm-based CO2 and CH4 emissions increased the source strength for the managed sites to 2.7 kg CO2-eq m-2 yr-1 for Oukoop and 2.1 kg CO2-eq m-2 yr-1 for Stein. Shifting from intensively managed to extensively managed grass-on-peat reduced GHG emissions mainly because N2O emission and farm-based CH4 emissions decreased. Overall, this study suggests that managed peatlands are large sources of GHG and carbon, but, if appropriate measures are taken they can be turned back into GHG and carbon sinks within 15 yr of abandonment and rewetting.

Respiratory strategy is a major determinant of [3H]water and [14C]chlorpyrifos uptake in aquatic insects

USGS Publications Warehouse

Buchwalter, D.B.; Jenkins, J.J.; Curtis, L.R.

2002-01-01

Despite the extensive use of aquatic insects to evaluate freshwater ecosystem health, little is known about the underlying factors that result in sensitivity differences between taxa. Organismal characteristics (respiratory strategy and body size) were used to explore the rates of [3H]H2O and [14)C]chlorpyrifos accumulation in aquatic insects. Ten aquatic insect taxa, including ephemeropteran, trichopteran, dipteran, hemipteran, and coleopteran species, were exposed to [14C]chlorpyrifos (240 ng??L-1) and [3H]H2O for up to 12 h. Because exchange epithelial surfaces on the)integument are permeable to water, [3H]H2O was used as a quantitative surrogate for exposed cellular surface area.) [14C]Chlorpyrifos uptake rates were highly correlated with water permeability in all 10 taxa tested and largely covaried with body size and respiratory strategy. Rates were highest among smaller organisms on a per-weight basis and in taxa with relatively large external cellular surfaces such as gills. Air-breathing taxa were significantly less permeable to both [3)HH20 and [14C)C]chlorpyrifos. A method for labeling exposed epithelial surfaces with a fluorescent dye was developed. This technique allowed discrimination between exchange epithelium and barrier tissue on the integument. Fluorescent dye distributions on the body surface provided a rapid method for estimating exposed epithelium consistent with [3H]H2O and [14)C]chlorpyrifos accumulation.

Remote Sensing for Hydrology: Surface Water Dynamics from Three Decades of Landsat Data

NASA Astrophysics Data System (ADS)

Tulbure, M. G.; Broich, M.; Kingsford, R.; Lucas, R.; Keith, D.

2014-12-01

Surface water is a vital resource affected by changes in climate and anthropogenic factors. Knowledge of surface water dynamics provides critical information for flood and drought management. Here we focused on the on the entire Murray-Darling Basin (MDB) of Australia, a large semi-arid region with scarce water resources, high hydroclimatic variability and competing water demands, impacted by climate change, altered flow regimes and land use changes. The MDB is also an area where substantial investment in environmental water allocation of large volumes of environmental flow was made. We used Landsat TM and ETM+ time series to synoptically map the dynamic of surface water extent with an internally consistent algorithm (Tulbure and Broich, 2013) over decades (1986-2011). We used a subset of Landsat path/rows for image training in both wet and dry years. Results show high interannual variability in number and size of flooded areas, with flooded areas during the Millennium Drought (until 2009) being substantially smaller than during the excessive 2010-2011 La Nina flooding. Flooding frequency in 2006, a very dry year was lower than in 2010, the La Nina year when extensive floods occurred. More developed areas of the basin showed different inter-annual patterns from natural areas of the basin. At Barmah-Millewa, the largest river red gum forest in the world, we also mapped flooded forest and tracked changes in NDVI. Higher NDVI values were found in areas more frequently flooded. Knowledge of the spatial and temporal dynamics of flooding and the response of riparian vegetation communities to flooding is important for management of floodplain wetlands and vegetation communities and for investigating effectiveness of environmental flows and flow regimes in the MDB. Existing maps of inundated areas are linked with river flow to quantify the relationship between river flow and inundated area in the MDB. Historic flood inundation extent mapped via remote sensing can be used to quantify spatially explicit changes in surface water dynamics and vegetation communities as outcomes of management scenarios in response to water management decisions. This methodology is globally applicable and relevant to areas prone to flooding with competing water demands and can be used for mapping water availability in data scarce regions.

Variability in surface water productivity in the central Gulf of California during the Medieval Climate Anomaly and Little Ice Age

NASA Astrophysics Data System (ADS)

Schwartz, V.; Barron, J. A.; Addison, J. A.; Bukry, D.

2016-12-01

The 1100-km-long Gulf of California (GOC) is separated from the cool waters of the eastern North Pacific by Baja California, and experiences both a temperate and sub-tropical climatology. In the eastern GOC, extensive diatom blooms are generated by strong northwest winds that upwell nutrient-rich waters during the winter. Slackening of these upwelling-favorable winds during the late spring allows for northward flow of tropical waters up the axis of the Gulf, prompting the flow of tropical moisture into northwestern Mexico and Arizona. Similar to the eastern bias during winter upwelling, northward flowing surface currents transporting tropical waters into the GOC during summer are also strongest on the eastern side of the Gulf. This study utilizes strew slide and biogenic silica (opal) analyses of diatoms and silicoflagellates to examine changes in primary productivity, over the past 2000 years from three marine sediment cores from Guaymas Basin in the central GOC. The cores include the eastern BAM80 E-17 (27.920° N, 111.610°W, 620 m water depth); the western MD02-2517c2 at 27.485° N, 112.074°W, water depth 887 m); and the southwestern DR373-VC-214 (26.879°N, 111.339°W, 1860 m water depth). This detailed productivity transect will test the hypothesis that the surface water productivity of the eastern and western portions of the Guaymas Basin responded differently to late Holocene climatic forcings. These records document distinct changes in the east-to-west productivity gradient during the Medieval Climate Anomaly (MCA) ( 850-1250 CE) and the Little Ice Age (LIA) ( 1300-1850 CE). Diatom and silicoflagellate assemblages suggest that the MCA was characterized by a reduced east- west productivity gradient and generally warm surface water conditions. The LIA appeared to be more similar to that of modern GOC surface water conditions, with a stronger east- west productivity gradient. The data also show that a warmer interval similar to that of the MCA occurred between 1450 and 1550 CE. Ongoing collaborative alkenone SST studies on MD02-2517 by Erin McClymont (Durham University) should help to further resolve the character of the MCA and LIA in the GOC.

Microbial colonization and controls in dryland systems

USGS Publications Warehouse

Pointing, Stephen B.; Belnap, Jayne

2012-01-01

Drylands constitute the most extensive terrestrial biome, covering more than one-third of the Earth's continental surface. In these environments, stress limits animal and plant life, so life forms that can survive desiccation and then resume growth following subsequent wetting assume the foremost role in ecosystem processes. In this Review, we describe how these organisms assemble in unique soil- and rock-surface communities to form a thin veneer of mostly microbial biomass across hot and cold deserts. These communities mediate inputs and outputs of gases, nutrients and water from desert surfaces, as well as regulating weathering, soil stability, and hydrological and nutrient cycles. The magnitude of regional and global desert-related environmental impacts is affected by these surface communities; here, we also discuss the challenges for incorporating the consideration of these communities and their effects into the management of dryland resources.

Inferring field-scale properties of a fractured aquifer from ground surface deformation during a well test

NASA Astrophysics Data System (ADS)

Schuite, Jonathan; Longuevergne, Laurent; Bour, Olivier; Boudin, Frédérick; Durand, Stéphane; Lavenant, Nicolas

2015-12-01

Fractured aquifers which bear valuable water resources are often difficult to characterize with classical hydrogeological tools due to their intrinsic heterogeneities. Here we implement ground surface deformation tools (tiltmetry and optical leveling) to monitor groundwater pressure changes induced by a classical hydraulic test at the Ploemeur observatory. By jointly analyzing complementary time constraining data (tilt) and spatially constraining data (vertical displacement), our results strongly suggest that the use of these surface deformation observations allows for estimating storativity and structural properties (dip, root depth, and lateral extension) of a large hydraulically active fracture, in good agreement with previous studies. Hence, we demonstrate that ground surface deformation is a useful addition to traditional hydrogeological techniques and opens possibilities for characterizing important large-scale properties of fractured aquifers with short-term well tests as a controlled forcing.

Nonylphenol and estrogenic activity in aquatic environmental samples

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanghe, T.; Devriese, G.; Verstraete, W.

1999-03-01

The authors surveyed a series of surface waters and sewage treatment plants in Flanders (north of Belgium) for the presence of estrogenic activity and a xeno-estrogenic compound para-nonylphenol (NP), respectively. The surface waters of rural origin, used for drinking water production were free of significant levels of estrogenic activity and NP. Domestic sewage, after proper treatment, appeared to be no major source of this chemical. Yet, in some industrial effluents and surface waters of highly industrialized regions, NP and/or estrogenic activity was prominent, that is, <1 to 122 {micro}g NP/L and 11 to 42 {micro}g NP/L, respectively. This is becausemore » of the ongoing use of NP polyethoxylates in industry. The response of the recombinant yeast estrogen assay to the environmental samples tested was not consistent with the detected concentrations of NP. Standard addition of a natural estrogen, 17{beta}-estradiol, generated no or a reduced response compared to the standard curve concentration. Application of humic acids to standard series of NP and 17{beta}-estradiol resulted in a dose-dependent decrease of the estrogenic response. It appears that this bioassay is subject to considerable interferences due to the complexity of environmental samples. Parallel implementation of extensive chemical screening for xenobiotics and use of the bioassay are needed for adequate assessment of the potential estrogenic hazard to avoid false negative evaluations.« less

Changing Hydrology in Glacier-fed High Altitude Andean Peatbogs

NASA Astrophysics Data System (ADS)

Slayback, D. A.; Yager, K.; Baraer, M.; Mohr, K. I.; Argollo, J.; Wigmore, O.; Meneses, R. I.; Mark, B. G.

2012-12-01

Montane peatbogs in the glacierized Andean highlands of Peru and Bolivia provide critical forage for camelids (llama and alpaca) in regionally extensive pastoral agriculture systems. During the long dry season, these wetlands often provide the only available green forage. A key question for the future of these peatbog systems, and the livelihoods they support, is the impact of climate change and glacier recession on their hydrology, and thus forage production. We have already documented substantial regional glacier recession, of, on average, approximately 30% of surface area over the past two decades. As glaciers begin to retreat under climate change, there is initially a period of increased meltwater outflow, culminating in a period of "peak water", and followed by a continual decline in outflows. Based on previous work, we know that some glaciers in the region have already passed peak water conditions, and are now declining. To better understand the impacts of these processes on peatbog hydrology and productivity, we have begun collecting a variety of surface data at several study sites in both Bolivia and Peru. These include precipitation, stream flow, water levels, water chemistry and isotope analyses, and peatbog biodiversity and biomass. These measurements will be used in conjunction with a regional model driven by satellite data to predict likely future impacts. We will present the results from these initial surface measurements, and an overview of satellite datasets to be used in the regional model.

Interaction between ground water and surface water in the northern Everglades and relation to water budget and mercury cycling; study methods and appendixes

USGS Publications Warehouse

Harvey, Judson W.; Krupa, S.L.; Gefvert, C.J.; Choi, Jungyill; Mooney, R.H.; Giddings, J.B.

2000-01-01

The data presented in this report are products of an investigation that quantified interactions between ground water and surface water at several study sites in the northern Everglades. Goals included identifying the major geologic controls and human alterations that affect interactions between ground water and surface water, and determining how those interactions affect mercury contamination. The primary study area was the 3,815-acre Everglades Nutrient Removal (ENR), a wetland constructed in the early 1990s as a prototype Stormwater Treatment Area (STA), to determine the effectiveness in removing excess nutrients from agricultural drainage. In order to ensure that results from ENR are broadly informative, work was also conducted in Water Conservation Area-2A (WCA-2A), a 105,000-acre basin surrounded by levees. In the past 50 years, WCA-2A has experienced extensive re- engineering of water flow, alterations in the pattern of water-level fluctuations and timing of fire frequency, as well as substantial ecological changes. The most visible ecological alteration is the change in dominance over the past 30 years from a sawgrass wetland to cattail wetland in the northeastern part of WCA-2A. The drastic change in vegetation in WCA-2A resulted at least in part from inputs of excess phosphorus from agricultural drainage. Substantial data collection programs were already in progress in both ENR and WCA- 2A when the present work began. The South Florida Water Management District (SFWMD) constructed the ENR project in 1994 to determine the effectiveness of constructed wetlands for water treatment. Measurements of surface water flow and water quality were made frequently in ENR between 1994 and 1998. Fewer ground water data were collected at ENR, and almost all of it was collected from shallow wells emplaced on perimeter levees. In contrast to the short-term nature of data collection in ENR, hydrologic and chemical data were collected over a much longer period in WCA-2A (since at least the mid- 1970s), but the number of sites and data- collection frequency is much less. Very little prior ground water data were available in WCA-2A. Given the availability of prior information, the present study emphasized the collection of ground water field data, particularly in the interior wetland areas of ENR and WCA- 2A. New wells were emplaced to permit the geologic, hydraulic, and chemical sampling that was needed to characterize interactions between surface water and ground water. In particular, lithology and hydraulic properties of the Surficial aquifer were determined, ground water flow paths and velocities were delineated, hydrologic fluxes between surface water and ground water were measured, and water budgets and surface- subsurface fluxes of mercury were determined. The purpose of this report is to compile under one cover all of the data collected in this investigation. In addition, the report contains a detailed description of the study methods and information about study sites, borehole drilling, well construction, seepage meter installation, and hydraulic and geochemical chemical sampling. Data interpretations are the subject of a companion report.

[Distributions and influencing factors of total dissolved inorganic antimony in the coastal area of Zhejiang and Fujian].

PubMed

Zhang, Xu-Zhou; Ren, Jing-Ling; Liu, Zong-Guang; Fan, Xiao-Peng; Liu, Cheng-Gang; Wu, Ying

2014-02-01

Antimony has been ubiquitously present in the aquatic environment as a toxic and rare metalloid element. The contamination of antimony and its compounds in the environment is increasingly severe, so it has been received extensive attention by the international scientific community. The cruise was carried out in the coastal area of Zhejiang and Fujian provinces in the East China Sea (ECS) in May 2008. The concentrations of total dissolved inorganic antimony (TDISb) were measured by Hydride Generation-Atomic Fluorescence (HG-AFS). The concentration ranges of TDISb in the surface and bottom layer were 0.68-5.64 nmol x L(-1) and 0.71-5.25 nmol x L(-1) with averages of 2.25 and 1.79 nmol x L(-1), respectively. The concentration of TDISb in the study area was lower than the environmental quality standards for surface water of China and drinking water standards of World Health Organization (about 41.08 nmol x L(-1)), indicating that it remained at the pristine level. The concentration of TDISb decreased gradually from the coastal area to the central ECS shelf with higher concentration in the surface layer than the bottom. Water mass mixing, adsorption/desorption behavior on the surface of the suspended particulate matters (SPM) and biological activities were the main influence factors of TDISb biogeochemistry in the study area.

Groundwater Contributions to Intermittent Streamflow in a Headwater Catchment: How do Geoclimatic Controls Influence Downstream Water Quality?

NASA Astrophysics Data System (ADS)

Smull, E. M.; Gooseff, M. N.; Singha, K.

2014-12-01

Hydrologic connectivity of headwater catchments affects surface water yield and quality of downstream drinking water supplies. Lower Gordon Gulch, a 2.75 km2 catchment, is part of the Boulder Creek watershed - the primary drinking water supply for the city of Boulder, Colorado. We hypothesize that the geologic and climatic environment within the catchment controls the magnitude, timing, and duration of hydrologic connection between the landscape and the stream, and thus the distribution of major ions to the surface water. Specifically, bedrock patterns, vegetation type and density, and snowpack dynamics influence how precipitation inputs move from the hillslopes to the catchment outlet. Preliminary results suggest that north-facing hillslopes with steeper slopes, deeper weathering of bedrock, denser vegetation stands, and a seasonal snowpack, provide consistently greater groundwater inputs to the stream compared to the south-facing hillslopes. We believe that this is in part due to subsurface bedrock patterns forcing a dominate cross-valley gradient. Through an extensive observation network of hillslope wells, periodic stream water balance measurements, and synoptic chemistry samples, we plan to continue our assessment of the spatio-temporal connectivity dynamics throughout the seasonal dry down (late summer through winter), during which streamflow can be intermittent. Results will help to guide landuse practices of upland catchments with respect to their role in Boulder's drinking water supply.

The influence of regional hydrology on nesting behavior and nest fate of the American alligator

USGS Publications Warehouse

Ugarte, Cristina A.; Bass, Oron L.; Nuttle, William; Mazzotti, Frank J.; Rice, Kenneth G.; Fujisaki, Ikuko; Whelan, Kevin R.T.

2013-01-01

Hydrologic conditions are critical to the nesting behavior and reproductive success of crocodilians. In South Florida, USA, growing human settlement has led to extensive surface water management and modification of historical water flows in the wetlands, which have affected regional nesting of the American alligator (Alligator mississippiensis). Although both natural and anthropogenic factors are considered to determine hydrologic conditions, the aspects of hydrological patterns that affect alligator nest effort, flooding (partial and complete), and failure (no hatchling) are unclear. We deconstructed annual hydrological patterns using harmonic models that estimated hydrological matrices including mean, amplitude, timing of peak, and periodicity of surface water depth and discharge and examined their effects on alligator nesting using survey data from Shark Slough, Everglades National Park, from 1985 to 2005. Nest effort increased in years with higher mean and lesser periodicity of water depth. A greater proportion of nests were flooded and failed when peak discharge occurred earlier in the year. Also, nest flooding rates were greater in years with greater periodicity of water depth, and nest failure rate was greater when mean discharge was higher. This study guides future water management decisions to mitigate negative impacts on reproduction of alligators and provides wildlife managers with a tool for assessing and modifying annual water management plans to conserve crocodilians and other wetland species.

Evaluation of a prototype surface flow bypass for juvenile salmon and steelhead at the powerhouse of Lower Granite Dam, Snake River, Washington, 1996-2000

USGS Publications Warehouse

Johnson, G.E.; Anglea, S.M.; Adams, N.S.; Wik, T.O.

2005-01-01

A surface flow bypass takes advantage of the natural surface orientation of most juvenile salmon Oncorhynchus spp. and steelhead O. mykiss by providing a route in the upper water column that downstream migrant fishes can use to pass a hydroelectric dam safely. A prototype structure, called the surface bypass and collector (SBC), was retrofitted on the powerhouse of Lower Granite Dam and was evaluated annually with biotelemetry and hydroacoustic techniques during the 5-year life span of the structure (1996-2000) to determine the entrance configuration that maximized passage efficiency and minimized forebay residence time. The best tested entrance configuration had maximum inflow (99 m 3/s) concentrated in a single surface entrance (5 m wide, 8.5 m deep). We identified five important considerations for future surface flow bypass development in the lower Snake River and elsewhere: (1) an extensive flow net should be formed in the forebay by use of relatively high surface flow bypass discharge (>7% of total project discharge); (2) a gradual increase in water velocity with increasing proximity to the surface flow bypass (ideally, acceleration 3 m/s) to entrain the subject juvenile fishes; (4) the shape and orientation of the surface entrance(s) should be adapted to fit site-specific features; and (5) construction of a forebay wall to increase fish availability to the surface flow bypass should be considered. The efficiency of the SBC was not high enough (maximum of 62% relative to passage at turbine units 4-5) for the SBC to operate as a stand-alone bypass. Anywhere that surface-oriented anadromous fish must negotiate hydroelectric dams, surface flow bypass systems can provide cost-effective use of typically limited water supplies to increase the nonturbine passage, and presumably survival, of downstream migrants. ??Copyright by the American Fisheries Society 2005.

Method Evaluations for Adsorption Free Energy Calculations at the Solid/Water Interface through Metadynamics, Umbrella Sampling, and Jarzynski's Equality.

PubMed

Wei, Qichao; Zhao, Weilong; Yang, Yang; Cui, Beiliang; Xu, Zhijun; Yang, Xiaoning

2018-03-19

Considerable interest in characterizing protein/peptide-surface interactions has prompted extensive computational studies on calculations of adsorption free energy. However, in many cases, each individual study has focused on the application of free energy calculations to a specific system; therefore, it is difficult to combine the results into a general picture for choosing an appropriate strategy for the system of interest. Herein, three well-established computational algorithms are systemically compared and evaluated to compute the adsorption free energy of small molecules on two representative surfaces. The results clearly demonstrate that the characteristics of studied interfacial systems have crucial effects on the accuracy and efficiency of the adsorption free energy calculations. For the hydrophobic surface, steered molecular dynamics exhibits the highest efficiency, which appears to be a favorable method of choice for enhanced sampling simulations. However, for the charged surface, only the umbrella sampling method has the ability to accurately explore the adsorption free energy surface. The affinity of the water layer to the surface significantly affects the performance of free energy calculation methods, especially at the region close to the surface. Therefore, a general principle of how to discriminate between methodological and sampling issues based on the interfacial characteristics of the system under investigation is proposed. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Arsenic control during aquifer storage recovery cycle tests in the Floridan Aquifer.

PubMed

Mirecki, June E; Bennett, Michael W; López-Baláez, Marie C

2013-01-01

Implementation of aquifer storage recovery (ASR) for water resource management in Florida is impeded by arsenic mobilization. Arsenic, released by pyrite oxidation during the recharge phase, sometimes results in groundwater concentrations that exceed the 10 µg/L criterion defined in the Safe Drinking Water Act. ASR was proposed as a major storage component for the Comprehensive Everglades Restoration Plan (CERP), in which excess surface water is stored during the wet season, and then distributed during the dry season for ecosystem restoration. To evaluate ASR system performance for CERP goals, three cycle tests were conducted, with extensive water-quality monitoring in the Upper Floridan Aquifer (UFA) at the Kissimmee River ASR (KRASR) pilot system. During each cycle test, redox evolution from sub-oxic to sulfate-reducing conditions occurs in the UFA storage zone, as indicated by decreasing Fe(2+) /H2 S mass ratios. Arsenic, released by pyrite oxidation during recharge, is sequestered during storage and recovery by co-precipitation with iron sulfide. Mineral saturation indices indicate that amorphous iron oxide (a sorption surface for arsenic) is stable only during oxic and sub-oxic conditions of the recharge phase, but iron sulfide (which co-precipitates arsenic) is stable during the sulfate-reducing conditions of the storage and recovery phases. Resultant arsenic concentrations in recovered water are below the 10 µg/L regulatory criterion during cycle tests 2 and 3. The arsenic sequestration process is appropriate for other ASR systems that recharge treated surface water into a sulfate-reducing aquifer. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.

Robust and biodegradable elastomers based on corn starch and polydimethylsiloxane (PDMS).

PubMed

Ceseracciu, Luca; Heredia-Guerrero, José Alejandro; Dante, Silvia; Athanassiou, Athanassia; Bayer, Ilker S

2015-02-18

Designing starch-based biopolymers and biodegradable composites with durable mechanical properties and good resistance to water is still a challenging task. Although thermoplastic (destructured) starch has emerged as an alternative to petroleum-based polymers, its poor dimensional stability under humid and dry conditions extensively hinders its use as the biopolymer of choice in many applications. Unmodified starch granules, on the other hand, suffer from incompatibility, poor dispersion, and phase separation issues when compounded into other thermoplastics above a concentration level of 5%. Herein, we present a facile biodegradable elastomer preparation method by incorporating large amounts of unmodified corn starch, exceeding 80% by volume, in acetoxy-polyorganosiloxane thermosets to produce mechanically robust, hydrophobic bioelastomers. The naturally adsorbed moisture on the surface of starch enables autocatalytic rapid hydrolysis of polyorganosiloxane to form Si-O-Si networks. Depending on the amount of starch granules, the mechanical properties of the bioelastomers can be easily tuned with high elastic recovery rates. Moreover, starch granules considerably lowered the surface friction coefficient of the polyorganosiloxane network. Stress relaxation measurements indicated that the bioelastomers have strain energy dissipation factors that are lower than those of conventional rubbers, rendering them as promising green substitutes for plastic mechanical energy dampeners. Corn starch granules also have excellent compatibility with addition-cured polysiloxane chemistry that is used extensively in microfabrication. Regardless of the starch concentration, all of the developed bioelastomers have hydrophobic surfaces with lower friction coefficients and much less water uptake capacity than those of thermoplastic starch. The bioelastomers are biocompatible and are estimated to biodegrade in Mediterranean seawater within three to six years.

The potential of high-frequency profiling to assess vertical and seasonal patterns of phytoplankton dynamics in lakes: An extension of the Plankton Ecology Group (PEG) model

USGS Publications Warehouse

Brentrup, Jennifer A.; Williamson, Craig E.; Colom-Montero, William; Eckert, Werner; de Eyto, Elvira; Grossart, Hans-Peter; Huot, Yannick; Isles, Peter D. F.; Knoll, Lesley B.; Leach, Taylor H.; McBride, Christopher G.; Pierson, Don; Pomati, Francesco; Read, Jordan S.; Rose, Kevin C.; Samal, Nihar R.; Staehr, Peter A.; Winslow, Luke A.

2016-01-01

The use of high-frequency sensors on profiling buoys to investigate physical, chemical, and biological processes in lakes is increasing rapidly. Profiling buoys with automated winches and sensors that collect high-frequency chlorophyll fluorescence (ChlF) profiles in 11 lakes in the Global Lake Ecological Observatory Network (GLEON) allowed the study of the vertical and temporal distribution of ChlF, including the formation of subsurface chlorophyll maxima (SSCM). The effectiveness of 3 methods for sampling phytoplankton distributions in lakes, including (1) manual profiles, (2) single-depth buoys, and (3) profiling buoys were assessed. High-frequency ChlF surface data and profiles were compared to predictions from the Plankton Ecology Group (PEG) model. The depth-integrated ChlF dynamics measured by the profiling buoy data revealed a greater complexity that neither conventional sampling nor the generalized PEG model captured. Conventional sampling techniques would have missed SSCM in 7 of 11 study lakes. Although surface-only ChlF data underestimated average water column ChlF, at times by nearly 2-fold in 4 of the lakes, overall there was a remarkable similarity between surface and mean water column data. Contrary to the PEG model’s proposed negligible role for physical control of phytoplankton during the growing season, thermal structure and light availability were closely associated with ChlF seasonal depth distribution. Thus, an extension of the PEG model is proposed, with a new conceptual framework that explicitly includes physical metrics to better predict SSCM formation in lakes and highlight when profiling buoys are especially informative.

Hydrologic Record Extension of Water-Level Data in the Everglades Depth Estimation Network (EDEN) Using Artificial Neural Network Models, 2000-2006

USGS Publications Warehouse

Conrads, Paul; Roehl, Edwin A.

2007-01-01

The Everglades Depth Estimation Network (EDEN) is an integrated network of real-time water-level gaging stations, ground-elevation models, and water-surface models designed to provide scientists, engineers, and water-resource managers with current (2000-present) water-depth information for the entire freshwater portion of the greater Everglades. The U.S. Geological Survey Greater Everglades Priority Ecosystem Science provides support for EDEN and the goal of providing quality assured monitoring data for the U.S. Army Corps of Engineers Comprehensive Everglades Restoration Plan. To increase the accuracy of the water-surface models, 25 real-time water-level gaging stations were added to the network of 253 established water-level gaging stations. To incorporate the data from the newly added stations to the 7-year EDEN database in the greater Everglades, the short-term water-level records (generally less than 1 year) needed to be simulated back in time (hindcasted) to be concurrent with data from the established gaging stations in the database. A three-step modeling approach using artificial neural network models was used to estimate the water levels at the new stations. The artificial neural network models used static variables that represent the gaging station location and percent vegetation in addition to dynamic variables that represent water-level data from the established EDEN gaging stations. The final step of the modeling approach was to simulate the computed error of the initial estimate to increase the accuracy of the final water-level estimate. The three-step modeling approach for estimating water levels at the new EDEN gaging stations produced satisfactory results. The coefficients of determination (R2) for 21 of the 25 estimates were greater than 0.95, and all of the estimates (25 of 25) were greater than 0.82. The model estimates showed good agreement with the measured data. For some new EDEN stations with limited measured data, the record extension (hindcasts) included periods beyond the range of the data used to train the artificial neural network models. The comparison of the hindcasts with long-term water-level data proximal to the new EDEN gaging stations indicated that the water-level estimates were reasonable. The percent model error (root mean square error divided by the range of the measured data) was less than 6 percent, and for the majority of stations (20 of 25), the percent model error was less than 1 percent.

Instability of water-ice interface under turbulent flow

NASA Astrophysics Data System (ADS)

Izumi, Norihiro; Naito, Kensuke; Yokokawa, Miwa

2015-04-01

It is known that plane water-ice interface becomes unstable to evolve into a train of waves. The underside of ice formed on the water surface of rivers are often observed to be covered with ice ripples. Relatively steep channels which discharge melting water from glaciers are characterized by beds covered with a series of steps. Though the flowing agent inducing instability is not water but gas including water vapor, a similar train of steps have been recently observed on the Polar Ice Caps on Mars (Spiral Troughs). They are expected to be caused by the instability of water-ice interface induced by flowing fluid on ice. There have been some studies on this instability in terms of linear stability analysis. Recently, Caporeale and Ridolfi (2012) have proposed a complete linear stability analysis in the case of laminar flow, and found that plane water-ice interface is unstable in the range of sufficiently large Reynolds numbers, and that the important parameters are the Reynolds number, the slope angle, and the water surface temperature. However, the flow inducing instability on water-ice interface in the field should be in the turbulent regime. Extension of the analysis to the case of fully developed turbulent flow with larger Reynolds numbers is needed. We have performed a linear stability analysis on the instability of water-ice interface under turbulent flow conditions with the use of the Reynolds-averaged Navier-Stokes equations with the mixing length turbulent model, the continuity equation of flow, the diffusion/dispersion equation of heat, and the Stefan equation. In order to reproduce the accurate velocity distribution and the heat transfer in the vicinity of smooth walls with the use of the mixing length model, it is important to take into account of the rapid decrease in the mixing length in the viscous sublayer. We employ the Driest model (1956) to the formulation. In addition, as the thermal boundary condition at the water surface, we describe the continuity of the heat fluxes from inside of water to the water surface and from the water surface to the surrounding air with the use of the heat transfer coefficient. The boundary condition then becomes the Robin boundary condition. It is found from the analysis, that the instability takes place in the range of large Froude numbers and small wavenumbers in the wavenumber-Froude number plane. It is also found that the unstable region does not show a significant difference when the Reynolds number is larger than somewhere around 5,000.

Climate and infectious disease: use of remote sensing for detection of Vibrio cholerae by indirect measurement

NASA Technical Reports Server (NTRS)

Lobitz, B.; Beck, L.; Huq, A.; Wood, B.; Fuchs, G.; Faruque, A. S.; Colwell, R.

2000-01-01

It has long been known that cholera outbreaks can be initiated when Vibrio cholerae, the bacterium that causes cholera, is present in drinking water in sufficient numbers to constitute an infective dose, if ingested by humans. Outbreaks associated with drinking or bathing in unpurified river or brackish water may directly or indirectly depend on such conditions as water temperature, nutrient concentration, and plankton production that may be favorable for growth and reproduction of the bacterium. Although these environmental parameters have routinely been measured by using water samples collected aboard research ships, the available data sets are sparse and infrequent. Furthermore, shipboard data acquisition is both expensive and time-consuming. Interpolation to regional scales can also be problematic. Although the bacterium, V. cholerae, cannot be sensed directly, remotely sensed data can be used to infer its presence. In the study reported here, satellite data were used to monitor the timing and spread of cholera. Public domain remote sensing data for the Bay of Bengal were compared directly with cholera case data collected in Bangladesh from 1992-1995. The remote sensing data included sea surface temperature and sea surface height. It was discovered that sea surface temperature shows an annual cycle similar to the cholera case data. Sea surface height may be an indicator of incursion of plankton-laden water inland, e.g., tidal rivers, because it was also found to be correlated with cholera outbreaks. The extensive studies accomplished during the past 25 years, confirming the hypothesis that V. cholerae is autochthonous to the aquatic environment and is a commensal of zooplankton, i.e., copepods, when combined with the findings of the satellite data analyses, provide strong evidence that cholera epidemics are climate-linked.

Seasonal cycle of circulation in the Antarctic Peninsula and the off-shelf transport of shelf waters into southern Drake Passage and Scotia Sea

NASA Astrophysics Data System (ADS)

Jiang, Mingshun; Charette, Matthew A.; Measures, Christopher I.; Zhu, Yiwu; Zhou, Meng

2013-06-01

The seasonal cycle of circulation and transport in the Antarctic Peninsula shelf region is investigated using a high-resolution (˜2 km) regional model based on the Regional Oceanic Modeling System (ROMS). The model also includes a naturally occurring tracer with a strong source over the shelf (radium isotope 228Ra, t1/2=5.8 years) to investigate the sediment Fe input and its transport. The model is spun-up for three years using climatological boundary and surface forcing and then run for the 2004-2006 period using realistic forcing. Model results suggest a persistent and coherent circulation system throughout the year consisting of several major components that converge water masses from various sources toward Elephant Island. These currents are largely in geostrophic balance, driven by surface winds, topographic steering, and large-scale forcing. Strong off-shelf transport of the Fe-rich shelf waters takes place over the northeastern shelf/slope of Elephant Island, driven by a combination of topographic steering, extension of shelf currents, and strong horizontal mixing between the ACC and shelf waters. These results are generally consistent with recent and historical observational studies. Both the shelf circulation and off-shelf transport show a significant seasonality, mainly due to the seasonal changes of surface winds and large-scale circulation. Modeled and observed distributions of 228Ra suggest that a majority of Fe-rich upper layer waters exported off-shelf around Elephant Island are carried by the shelfbreak current and the Bransfield Strait Current from the shallow sills between Gerlache Strait and Livingston Island, and northern shelf of the South Shetland Islands, where strong winter mixing supplies much of the sediment derived nutrients (including Fe) input to the surface layer.

Ephemeral liquid water at the surface of the martian North Polar Residual Cap: Results of numerical modelling

NASA Astrophysics Data System (ADS)

Losiak, Anna; Czechowski, Leszek; Velbel, Michael A.

2015-12-01

Gypsum, a mineral that requires water to form, is common on the surface of Mars. Most of it originated before 3.5 Gyr when the Red Planet was more humid than now. However, occurrences of gypsum dune deposits around the North Polar Residual Cap (NPRC) seem to be surprisingly young: late Amazonian in age. This shows that liquid water was present on Mars even at times when surface conditions were as cold and dry as the present-day. A recently proposed mechanism for gypsum formation involves weathering of dust within ice (e.g., Niles, P.B., Michalski, J. [2009]. Nat. Geosci. 2, 215-220.). However, none of the previous studies have determined if this process is possible under current martian conditions. Here, we use numerical modelling of heat transfer to show that during the warmest days of the summer, solar irradiation may be sufficient to melt pure water ice located below a layer of dark dust particles (albedo ⩽ 0.13) lying on the steepest sections of the equator-facing slopes of the spiral troughs within martian NPRC. During the times of high irradiance at the north pole (every 51 ka; caused by variation of orbital and rotational parameters of Mars e.g., Laskar, J. et al. [2002]. Nature 419, 375-377.) this process could have taken place over larger parts of the spiral troughs. The existence of small amounts of liquid water close to the surface, even under current martian conditions, fulfils one of the main requirements necessary to explain the formation of the extensive gypsum deposits around the NPRC. It also changes our understanding of the degree of current geological activity on Mars and has important implications for estimating the astrobiological potential of Mars.

Europa's Great Lakes

NASA Astrophysics Data System (ADS)

Schmidt, B. E.; Blankenship, D. D.; Patterson, G. W.; Schenk, P. M.

2012-04-01

Unique to the surface of Europa, chaos terrain is diagnostic of the properties and dynamics of its icy shell. While models have suggested that partial melt within a thick shell or melt-through of a thin shell may form chaos, neither model has been able to definitively explain all observations of chaos terrain. However, we present a new model that suggests large melt lenses form within the shell and that water-ice interactions above and within these lenses drive the production of chaos. Our analysis of the geomorphology of Conamara Chaos and Thera Macula, was used to infer and test a four-stage lens-collapse chaos formation model: 1) Thermal plumes of warm, pure ice ascend through the shell melting the impure brittle ice above, producing a lake of briny water and surface down draw due to volume reduction. 2) Surface deflection and driving force from the plume below hydraulically seals the water in place. 3) Extension of the brittle ice lid generates fractures from below, allowing brines to enter and fluidize the ice matrix. 4) As the lens and now brash matrix refreeze, thermal expansion creates domes and raises the chaos feature above the background terrain. This new "lense-collapse" model indicates that chaos features form in the presence of a great deal of liquid water, and that large liquid water bodies exist within 3km of Europa's surface comparable in volume to the North American Great Lakes. The detection of shallow subsurface "lakes" implies that the ice shell is recycling rapidly and that Europa may be currently active. In this presentation, we will explore environments on Europa and their analogs on Earth, from collapsing Antarctic ice shelves to to subglacial volcanos in Iceland. I will present these new analyses, and describe how this new perspective informs the debate about Europa's habitability and future exploration.

Influence of traditional agricultural practices on mobilization of arsenic from sediments to groundwater in Bengal delta.

PubMed

Farooq, S H; Chandrasekharam, D; Berner, Z; Norra, S; Stüben, D

2010-11-01

In the wake of the idea that surface derived dissolved organic carbon (DOC) plays an important role in the mobilization of arsenic (As) from sediments to groundwater and may provide a vital tool in understanding the mechanism of As contamination (mobilization/fixation) in Bengal delta; a study has been carried out. Agricultural fields that mainly cultivate rice (paddy fields) leave significantly large quantities of organic matter/organic carbon on the surface of Bengal delta which during monsoon starts decomposing and produces DOC. The DOC thus produced percolates down with rain water and mobilizes As from the sediments. Investigations on sediment samples collected from a paddy field clearly indicate that As coming on to the surface along with the irrigation water accumulates itself in the top few meters of sediment profile. The column experiments carried out on a 9 m deep sediment profile demonstrates that DOC has a strong potential to mobilize As from the paddy fields and the water recharging the aquifer through such agricultural fields contain As well above the WHO limit thus contaminating the shallow groundwater. Experiment also demonstrates that decay of organic matter induces reducing condition in the sediments. Progressively increasing reducing conditions not only prevent the adsorption of As on mineral surfaces but also cause mobilization of previously sorbed arsenic. There seems to be a cyclic pattern where As from deeper levels comes to the surface with irrigational water, accumulates itself in the sediments, and ultimately moves down to the shallow groundwater. The extensive and continual exploitation of intermediate/deep groundwater accelerates this cyclic process and helps in the movement of shallow contaminated groundwater to the deeper levels. Copyright © 2010 Elsevier Ltd. All rights reserved.

Cooperative effects in the structuring of fluoride water clusters: Ab initio hybrid quantum mechanical/molecular mechanical model incorporating polarizable fluctuating charge solvent

NASA Astrophysics Data System (ADS)

Bryce, Richard A.; Vincent, Mark A.; Malcolm, Nathaniel O. J.; Hillier, Ian H.; Burton, Neil A.

1998-08-01

A new hybrid quantum mechanical/molecular mechanical model of solvation is developed and used to describe the structure and dynamics of small fluoride/water clusters, using an ab initio wave function to model the ion and a fluctuating charge potential to model the waters. Appropriate parameters for the water-water and fluoride-water interactions are derived, with the fluoride anion being described by density functional theory and a large Gaussian basis. The role of solvent polarization in determining the structure and energetics of F(H2O)4- clusters is investigated, predicting a slightly greater stability of the interior compared to the surface structure, in agreement with ab initio studies. An extended Lagrangian treatment of the polarizable water, in which the water atomic charges fluctuate dynamically, is used to study the dynamics of F(H2O)4- cluster. A simulation using a fixed solvent charge distribution indicates principally interior, solvated states for the cluster. However, a preponderance of trisolvated configurations is observed using the polarizable model at 300 K, which involves only three direct fluoride-water hydrogen bonds. Ab initio calculations confirm this trisolvated species as a thermally accessible state at room temperature, in addition to the tetrasolvated interior and surface structures. Extension of this polarizable water model to fluoride clusters with five and six waters gave less satisfactory agreement with experimental energies and with ab initio geometries. However, our results do suggest that a quantitative model of solvent polarization is fundamental for an accurate understanding of the properties of anionic water clusters.

Molecular-Scale Description of SPAN80 Desorption from a Squalane-Water Interface.

PubMed

Tan, L; Pratt, L R; Chaudhari, M I

2018-04-05

Extensive all-atom molecular dynamics calculations on the water-squalane interface for nine different loadings with sorbitan monooleate (SPAN80), at T = 300 K, are analyzed for the surface tension equation of state, desorption free-energy profiles as they depend on loading, and to evaluate escape times for adsorbed SPAN80 into the bulk phases. These results suggest that loading only weakly affects accommodation of a SPAN80 molecule by this squalane-water interface. Specifically, the surface tension equation of state is simple through the range of high tension to high loading studied, and the desorption free-energy profiles are weakly dependent on loading here. The perpendicular motion of the centroid of the SPAN80 headgroup ring is well-described by a diffusional model near the minimum of the desorption free-energy profile. Lateral diffusional motion is weakly dependent on loading. Escape times evaluated on the basis of a diffusional model and the desorption free energies are 7 × 10 -2 s (into the squalane) and 3 × 10 2 h (into the water). The latter value is consistent with desorption times of related lab-scale experimental work.

A Study of Water Wave Wakes of Washington State Ferries

NASA Astrophysics Data System (ADS)

Perfect, Bradley; Riley, James; Thomson, Jim; Fay, Endicott

2015-11-01

Washington State Ferries (WSF) operates a ferry route that travels through a 600m-wide channel called Rich Passage. Concerns of shoreline erosion in Rich Passage have prompted this study of the generation and propagation of surface wave wakes caused by WSF vessels. The problem was addressed in three ways: analytically, using an extension of the Kelvin wake model by Darmon et al. (J. Fluid Mech., 738, 2014); computationally, employing a RANS Navier-Stokes model in the CFD code OpenFOAM which uses the Volume of Fluid method to treat the free surface; and with field data taken in Sept-Nov, 2014, using a suite of surface wave measuring buoys. This study represents one of the first times that model predictions of ferry boat-generated wakes can be tested against measurements in open waters. The results of the models and the field data are evaluated using direct comparison of predicted and measured surface wave height as well as other metrics. Furthermore, the model predictions and field measurements suggest differences in wake amplitudes for different class vessels. Finally, the relative strengths and weaknesses of each prediction method as well as of the field measurements will be discussed. Washington State Department of Transportation.

Hurricanes Harvey and Irma - High-Resolution Flood Mapping and Monitoring from Sentinel SAR with the Depolarization Reduction Algorithm for Global Observations of InundatioN (DRAGON)

NASA Astrophysics Data System (ADS)

Nghiem, S. V.; Brakenridge, G. R.; Nguyen, D. T.

2017-12-01

Hurricane Harvey inflicted historical catastrophic flooding across extensive regions around Houston and southeast Texas after making landfall on 25 August 2017. The Federal Emergency Management Agency (FEMA) requested urgent supports for flood mapping and monitoring in an emergency response to the extreme flood situation. An innovative satellite remote sensing method, called the Depolarization Reduction Algorithm for Global Observations of inundatioN (DRAGON), has been developed and implemented for use with Sentinel synthetic aperture radar (SAR) satellite data at a resolution of 10 meters to identify, map, and monitor inundation including pre-existing water bodies and newly flooded areas. Results from this new method are hydrologically consistent and have been verified with known surface waters (e.g., coastal ocean, rivers, lakes, reservoirs, etc.), with clear-sky high-resolution WorldView images (where waves can be seen on surface water in inundated areas within a small spatial coverage), and with other flood maps from the consortium of Global Flood Partnership derived from multiple satellite datasets (including clear-sky Landsat and MODIS at lower resolutions). Figure 1 is a high-resolution (4K UHD) image of a composite inundation map for the region around Rosharon (in Brazoria County, south of Houston, Texas). This composite inundation map reveals extensive flooding on 29 August 2017 (four days after Hurricane Harvey made landfall), and the inundation was still persistent in most of the west and south of Rosharon one week later (5 September 2017) while flooding was reduced in the east of Rosharon. Hurricane Irma brought flooding to a number of areas in Florida. As of 10 September 2017, Sentinel SAR flood maps reveal inundation in the Florida Panhandle and over lowland surfaces on several islands in the Florida Keys. However, Sentinel SAR results indicate that flooding along the Florida coast was not extreme despite Irma was a Category-5 hurricane that might have inflicted a potentially strong storm surge. DRAGON flood mapping products over various regions in Texas and in Florida were provided to FEMA. Figure 1. Composite inundation map derived from Sentinel SAR data for the region around Rosharon on 9/5/2017 (orange), inundation on 8/29/2017 (yellow), and pre-existing surface waters on 8/5/2017 (blue).

Iapetus Surface Temperatures, and the Influence of Sublimation on the Albedo Dichotomy: Cassini CIRS Constraints

NASA Astrophysics Data System (ADS)

Spencer, J. R.; Pearl, J. C.; Segura, M.; Cassini CIRS Team

2005-08-01

The Composite Infrared Spectrometer (CIRS) on the Cassini orbiter obtained extensive observations of Iapetus' thermal emission during the New Year 2005 flyby, with best 8 - 16 μ m spatial resolution of 35 km per pixel. Observed subsolar temperatures on the dark terrain reach nearly 130 K, much warmer than any other satellite surface in the Saturn system, due to the combination of low albedo and slow rotation. These high temperatures mean that, uniquely in the Saturn system, water ice sublimation rates are significant at low latitudes on Iapetus' dark side, and surface water ice is probably not stable there on geological timescales. This result is consistent with the lack of water ice at low latitudes on the dark terrain inferred from Cassini UVIS UV spectra (Hendrix et al., 2005 LPSC). Thermally-controlled migration of water ice may thus contribute to the curious shape of the light/dark boundary on Iapetus, with bright poles and dark terrain extending round the equator onto the trailing side. Impacts of Saturn-centric or prograde heliocentric material cannot alone explain this shape, as their impact flux depends only on distance from the apex of motion (though the impact distribution of Oort cloud comet dust may be consistent with the observed albedo pattern (Cook and Franklin 1970)). We model the ballistic migration of water ice across the surface of Iapetus, determining temperatures and sublimation rates assuming CIRS-constrained thermal inertia and a simple dependence of albedo on distance from the apex of motion. Water ice is lost rapidly from low latitudes on the dark leading side and accumulates near the poles, and is also lost, though more slowly, in equatorial regions near the sub-Saturn and anti-Saturn points. The resulting water ice distribution pattern matches the distribution of Iapetus' bright terrain remarkably well. Albedo modification by thermal migration can thus help to reconcile Iapetus' albedo patterns with albedo control by Saturn-centric or prograde heliocentric impactors.

Aquifer recharge from infiltration basins in a highly urbanized area: the river Po Plain (Italy)

NASA Astrophysics Data System (ADS)

Masetti, M.; Nghiem, S. V.; Sorichetta, A.; Stevenazzi, S.; Santi, E. S.; Pettinato, S.; Bonfanti, M.; Pedretti, D.

2015-12-01

Due to the extensive urbanization in the Po Plain in northern Italy, rivers need to be managed to alleviate flooding problems while maintaining an appropriate aquifer recharge under an increasing percentage of impermeable surfaces. During the PO PLain Experiment field campaign in July 2015 (POPLEX 2015), both active and under-construction infiltration basins have been surveyed and analyzed to identify appropriate satellite observations that can be integrated to ground based monitoring techniques. A key strategy is to have continuous data time series on water presence and level within the basin, for which ground based monitoring can be costly and difficult to be obtained consistently.One of the major and old infiltration basin in the central Po Plain has been considered as pilot area. The basin is active from 2003 with ground based monitoring available since 2009 and supporting the development of a calibrated unsaturated-saturated two-dimensional numerical model simulating the infiltration dynamics through the basin.A procedure to use satellite data to detect surface water change is under development based on satellite radar backscatter data with an appropriate incidence angle and polarization combination. An advantage of satellite radar is that it can observe surface water regardless of cloud cover, which can be persistent during rainy seasons. Then, the surface water change is correlated to the reservoir water stage to determine water storage in the basin together with integrated ground data and to give quantitative estimates of variations in the local water cycle.We evaluated the evolution of the infiltration rate, to obtain useful insights about the general recharge behavior of basins that can be used for informed design and maintenance. Results clearly show when the basin becomes progressively clogged by biofilms that can reduce the infiltration capacity of the basin by as much as 50 times compared to when it properly works under clean conditions.

Quantifying peak discharges for historical floods

USGS Publications Warehouse

Cook, J.L.

1987-01-01

It is usually advantageous to use information regarding historical floods, if available, to define the flood-frequency relation for a stream. Peak stages can sometimes be determined for outstanding floods that occurred many years ago before systematic gaging of streams began. In the United States, this information is usually not available for more than 100-200 years, but in countries with long cultural histories, such as China, historical flood data are available at some sites as far back as 2,000 years or more. It is important in flood studies to be able to assign a maximum discharge rate and an associated error range to the historical flood. This paper describes the significant characteristics and uncertainties of four commonly used methods for estimating the peak discharge of a flood. These methods are: (1) rating curve (stage-discharge relation) extension; (2) slope conveyance; (3) slope area; and (4) step backwater. Logarithmic extensions of rating curves are based on theoretical plotting techniques that results in straight line extensions provided that channel shape and roughness do not change significantly. The slope-conveyance and slope-area methods are based on the Manning equation, which requires specific data on channel size, shape and roughness, as well as the water-surface slope for one or more cross-sections in a relatively straight reach of channel. The slope-conveyance method is used primarily for shaping and extending rating curves, whereas the slope-area method is used for specific floods. The step-backwater method, also based on the Manning equation, requires more cross-section data than the slope-area ethod, but has a water-surface profile convergence characteristic that negates the need for known or estimated water-surface slope. Uncertainties in calculating peak discharge for historical floods may be quite large. Various investigations have shown that errors in calculating peak discharges by the slope-area method under ideal conditions for recent floods (i.e., when flood elevations, slope and channel characteristics are reasonably certain), may be on the order of 10-25%. Under less than ideal conditions, where streams are hydraulically steep and rough, errors may be much larger. The additional uncertainties for historical floods created by the passage of time may result in even larger errors of peak discharge. ?? 1987.

A new methodology to identify surface water bodies at risk by using pesticide monitoring data: The glyphosate case study in Lombardy Region (Italy).

PubMed

Di Guardo, Andrea; Finizio, Antonio

2018-01-01

In the last decades, several monitoring programs were established as an effect of EU Directives addressing the quality of water resources (drinking water, groundwater and surface water). Plant Protection Products (PPPs) are an obvious target of monitoring activities, since they are directly released into the environment. One of the challenges in managing the risk of pesticides at the territorial scale is identifying the locations in water bodies needing implementation of risk mitigation measures. In this, the national pesticides monitoring plans could be very helpful. However, monitoring of pesticides is a challenging task because of the high number of registered pesticides, cost of analyses, and the periodicity of sampling related to pesticide application and use. Extensive high-quality data-sets are consequently often missing. More in general, the information that can be obtained from monitoring studies are frequently undervalued by risk managers. In this study, we propose a new methodology providing indications about the need to implement mitigation measures in stretches of surface water bodies on a territory by combining historical series of monitoring data and GIS. The methodology is articulated in two distinct phases: a) acquisition of monitoring data and setting-up of informative layers of georeferenced data (phase 1) and b) statistical and expert analysis for the identification of areas where implementation of limitation or mitigation measures are suggested (phase 2). Our methodology identifies potentially vulnerable water bodies, considering temporal contamination trends and relative risk levels at selected monitoring stations. A case study is presented considering glyphosate monitoring data in Lombardy Region (Northern of Italy) for the 2008-2014 period. Copyright © 2017 Elsevier B.V. All rights reserved.

Transport driven by eddy momentum fluxes in the Gulf Stream Extension region

NASA Astrophysics Data System (ADS)

Greatbatch, R. J.; Zhai, X.; Claus, M.; Czeschel, L.; Rath, W.

2010-12-01

The importance of the Gulf Stream Extension region in climate and seasonal prediction research is being increasingly recognised. Here we use satellite-derived eddy momentum fluxes to drive a shallow water model for the North Atlantic Ocean that includes the realistic ocean bottom topography. The results show that the eddy momentum fluxes can drive significant transport, sufficient to explain the observed increase in transport of the Gulf Stream following its separation from the coast at Cape Hatteras, as well as the observed recirculation gyres. The model also captures recirculating gyres seen in the mean sea surface height field within the North Atlantic Current system east of the Grand Banks of Newfoundland, including a representation of the Mann Eddy.

Drought-induced xylem cavitation and hydraulic deterioration: risk factors for urban trees under climate change?

PubMed

Savi, Tadeja; Bertuzzi, Stefano; Branca, Salvatore; Tretiach, Mauro; Nardini, Andrea

2015-02-01

Urban trees help towns to cope with climate warming by cooling both air and surfaces. The challenges imposed by the urban environment, with special reference to low water availability due to the presence of extensive pavements, result in high rates of mortality of street trees, that can be increased by climatic extremes. We investigated the water relations and xylem hydraulic safety/efficiency of Quercus ilex trees growing at urban sites with different percentages of surrounding impervious pavements. Seasonal changes of plant water potential and gas exchange, vulnerability to cavitation and embolism level, and morpho-anatomical traits were measured. We found patterns of increasing water stress and vulnerability to drought at increasing percentages of impervious pavement cover, with a consequent reduction in gas exchange rates, decreased safety margins toward embolism development, and increased vulnerability to cavitation, suggesting the occurrence of stress-induced hydraulic deterioration. The amount of impermeable surface and chronic exposure to water stress influence the site-specific risk of drought-induced dieback of urban trees under extreme drought. Besides providing directions for management of green spaces in towns, our data suggest that xylem hydraulics is key to a full understanding of the responses of urban trees to global change. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

Evaluating the Historical Importance of Impact Induced Hydrothermal Systems on Mars Using the Stable Isotopic Composition of Martian Water

NASA Technical Reports Server (NTRS)

Niles, Paul B.

2010-01-01

The importance of impact events during the early history of Mars is obvious through a simple examination of the character of the martian surface. This ancient, heavily cratered terrain has been shown to be associated with extensive phyllosilicate deposits. This geologic link could suggest that the extensive phyllosilicate-forming alteration may have occurred during early martian history through impact-induced hydrothermal alteration. However, examination of the oxygen isotopic composition of water on Mars suggests that the extensive phyllosilicate deposits were formed primarily through low temperature (<30 C) interactions, and that high temperature weathering in impact-induced hydrothermal systems have not been a dominant process on Mars. The average oxygen isotopic composition of water on Earth is dictated by the nature of water-rock interactions. If these interactions occur at higher temperatures then the water will contain a higher proportion of 18O, while lower temperature interactions will result in water with a lower proportion of 18O. Water on Earth today contains a higher proportion of 18O because of plate tectonics and hydrothermal interaction at mid-ocean ridges. The oxygen isotopic composition of water on early earth, however, may have been quite different, containing a smaller proportion of 18O suggesting much less hydrothermal interaction. Because there are not yet any direct measurements of the oxygen isotopic composition of water on Mars, it needs to be inferred through examination of carbonates preserved in martian meteorites and the isotopic composition of atmospheric CO2. This can be done because the oxygen incorporated into carbonates and CO2 is easily exchanged with liquid water if it is present. Independently, both measurements provide an estimate for the (Sigma)18O of water on Mars to be near -16%. This composition is consistent with low temperature weathering of the silicate crust, and indicates that impact hydrothermal systems did not play an important role in the early alteration of the planet. However, our understanding of impact-induced hydrothermal systems remains unclear. If most of the water mobilized by an impact event remained at relatively low temperatures (<30deg), low-temperature interactions could predominate in these environments. These conditions would be consistent with the isotopic constraints suggested in this study.

Tritium behavior on a cultivated plot in the 1994 chronic HT release experiment at Chalk River

DOE Office of Scientific and Technical Information (OSTI.GOV)

Noguchi, H.; Yokoyama, S.; Kinouchi, N.

1995-10-01

The behavior of HT and HTO in air and surface soil has been studied extensively in the chronic HT release experiment carried out at Chalk River during the summer of 1994. HTO concentrations in air moisture and soil water collected in a cultivated plot showed similar time-variations, increasing rapidly during the first and second days and becoming gradual after the first 3-4 days. The air HTO concentration decreased during and following rainfall but recovered within a day. The rainfall reduced the HTO concentrations in ridge soil water but little in furrows. Time histories of HTO concentrations in air moisture andmore » soil water suggest that the system was near steady-state within a continuous HT release period of 12 days, in spite of the presence of rain during the period. The air HTO concentrations on clear days showed diurnal cycles that were higher during daytime than at night. The experimental field had a very complex soil regime with respect to HT deposits. The deposits to soil surface varied depending on soil conditions. 12 refs., 5 figs.« less

Uranium-isotope variations in groundwaters of the Floridan aquifer and Boulder Zone of south Florida

USGS Publications Warehouse

Cowart, J.B.; Kaufman, M.I.; Osmond, J.K.

1978-01-01

Water samples from four wells from the main Floridan aquifer (300-400 m below mean sea level) in southeast Florida exhibit 234U 233U activity ratios that are significantly lower than the secular equilibrium value of 1.00. Such anomalous values have been observed previously only in waters from sedimentary aquifers in the near-surface oxidizing environments. These four wells differ from six others, all producing from the same general horizon, in being located in cavernous highly transmissive zones. We hypothesize that the low activity ratios are indicative of a relic circulation pattern whereby water from the surface aquifer was channelled to lower levels when sea level was much lower. At a deeper cavernous level, known as the Boulder Zone (800-1,000 m below mean sea level), the U isotopes, along with other chemical constituents, show progressive changes with increasing distance from an inferred flow source in the Straits of Florida. This tends to support the hypothesized landward flow (though with a more northerly component) of cold seawater in the extensively transmissive Boulder Zone. ?? 1978.

Geologic context of recurring slope lineae in Melas and Coprates Chasmata, Mars

NASA Astrophysics Data System (ADS)

Chojnacki, Matthew; McEwen, Alfred; Dundas, Colin; Ojha, Lujendra; Urso, Anna; Sutton, Sarah

2016-07-01

One of the major Mars discoveries of recent years is the existence of recurring slope lineae (RSL), which suggests that liquid water occurs on or near the surface of Mars today. These dark and narrow features emerge from steep, rocky exposures and incrementally grow, fade, and reform on a seasonal basis and are detected in images from the High Resolution Imaging Science Experiment camera. RSL are known to occur at scattered midlatitude and equatorial sites with little spatial connection to one another. One major exception is the steep, low-albedo slopes of Melas and Coprates Chasmata, in Valles Marineris where RSL are detected among diverse geologic surfaces (e.g., bedrock and talus) and landforms (e.g., inselbergs and landslides). New images show topographic changes including sediment deposition on active RSL slopes. Midwall locations in Coprates and Melas appear to have more areally extensively abundant RSL and related fans as compared with other RSL sites found on Mars. Water budget estimates for regional RSL are on the order of 105 to 106 m3 of fluid, for depths of 10 to 100 mm, and suggest that a significant amount of near-surface water might be present. Many RSL are concentrated near local topographic highs, such as ridge crests or peaks, which is challenging to explain via groundwater or ice without a recharge mechanism. Collectively, results provide additional support for the notion that significant amounts of near-surface water can be found on Mars today and suggest that a widespread mechanism, possibly related to the atmosphere, is recharging RSL sources.

North Pacific Cloud Feedbacks Inferred from Synoptic-Scale Dynamic and Thermodynamic Relationships

NASA Technical Reports Server (NTRS)

Norris, Joel R.; Iacobellis, Sam F.

2005-01-01

This study analyzed daily satellite cloud observations and reanalysis dynamical parameters to determine how mid-tropospheric vertical velocity and advection over the sea surface temperature gradient control midlatitude North Pacific cloud properties. Optically thick clouds with high tops are generated by synoptic ascent, but two different cloud regimes occur under synoptic descent. When vertical motion is downward during summer, extensive stratocumulus cloudiness is associated with near surface northerly wind, while frequent cloudless pixels occur with southerly wind. Examinations of ship-reported cloud types indicates that midlatitude stratocumulus breaks up as the the boundary level decouples when it is advected equatorward over warmer water. Cumulus is prevalent under conditions of synoptic descent and cold advection during winter. Poleward advection of subtropical air over colder water causes stratification of the near-surface layer that inhibits upward mixing of moisture and suppresses cloudiness until a fog eventually forms. Averaging of cloud and radiation data into intervals of 500-hPa vertical velocity and advection over the SST gradient enables the cloud response to changes in temperature and the stratification of the lower troposphere to be investigated independent of the dynamics.

Reductive dechlorination of trichloroethylene by iron bimetallics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Orth, R.G.; Dauda, T.; McKenzie, D.E.

1998-07-01

Reductive dechlorination using a zero valence metal such as iron has seen an increase in interest with the extension of iron dechlorination to in-situ treatment of ground water. Studies to increase the rate of dechlorination and the long term stability have lead many to examine the use of bimetallic iron systems. Results are shown for bimetallic iron systems of Cu, Sn, Ni, Ag, Au, and Pd. All of these bimetallic couples form a galvanic couple which increase corrosion rates and the production of hydrogen. Increased rates of reaction normalized to surface area were observed for all the couples. The reactionmore » rates were found to depended on surface area and surface coverage of the iron. The results of studies in deuterium oxide indicate that the pathways changed as the bimetallic is changed and that the pathway in all cases could be a combination of dehydrohalgenation and sequential dechlorination. Degradation of DNAPL TCE by iron was found to be zero order and the type of product observed was different from that observed for TCE dissolved in water.« less

Adsorption of non-ionic ABC triblock copolymers: Surface modification of TiO2 suspensions in aqueous and non-aqueous medium

NASA Astrophysics Data System (ADS)

Lerch, Jean-Philippe; Atanase, Leonard Ionut; Riess, Gérard

2017-10-01

A series of non-ionic ABC triblock copolymers, such as poly(butadiene)-b-poly(2-vinylpyrridine)-b-poly(ethylene oxide) (PB-P2VP-PEO) were synthesized by sequential anionic polymerizations. For these copolymers comprising an organo-soluble PB and a water-soluble PEO block, their P2VP middle block has been selected for its anchoring capacity on solid surfaces. The adsorption isotherms on TiO2 were obtained in heptane and in aqueous medium, as selective solvents. In both of these cases, the P2VP middle block provides the surface anchoring, whereas PB and PEO sequences are acting as stabilizing moieties in heptane and water respectively. By extension to ABC triblock copolymers of the scaling theory developed for diblock copolymers, the density of adsorbed chains could be correlated with the molecular characteristics of the PB-P2VP-PEO triblock copolymers. From a practical point a view, it could be demonstrated that these copolymers are efficient dispersing agents for the TiO2 pigments in both aqueous and non-aqueous medium.

Shallow Sub-Permafrost Groundwater Systems In A Buried Fjord: Taylor Valley, Antarctica

NASA Astrophysics Data System (ADS)

Foley, N.; Tulaczyk, S. M.; Auken, E.; Mikucki, J.

2014-12-01

The McMurdo Dry Valleys (MDV), Antarctica, represent a unique geologic setting where permanent lakes, ephemeral streams, and subglacial waters influence surface hydrology in a cold polar desert. Past research suggested that the MDV are underlain by several hundreds of meters of permafrost. Here, we present data collected from an Airborne EM (AEM) resistivity sensor flown over the MDV during the 2011-12 austral summer. A focus of our survey was over the Taylor Glacier where saline, iron-rich subglacial fluid releases at the glacier snout at a feature known as Blood Falls, and over Taylor Valley, where a series of isolated lakes lie between Taylor Glacier and the Ross Sea. Our data show that in Taylor Valley there are extensive areas of low resistivity, interpreted as hypersaline brines, beneath a relatively thin layer of high resistivity material, interpreted as dry- or ice-cemented permafrost. These hypersaline brines remain liquid at temperatures well below 0°C due to their salinity. They appear to be contained within the sedimentary fill deposited in Taylor Valley when it was still a fjord. This brine system continues up valley and has a subglacial extension beneath Taylor Glacier, where it may provide the source that feeds Blood Falls. By categorizing the resistivity measurements according to surficial land cover, we are able to distinguish between ice, permafrost, lake water, and seawater based on characteristic resistivity distributions. Furthermore, this technique shows that areas of surface permafrost become increasingly conductive (brine-filled) with depth, whereas the large lakes exhibit taliks that extend through the entire thickness of the permafrost. The subsurface brines represent a large, unstudied and potentially connected hydrogeologic system, in which subsurface flows may help transfer water and nutrients between lakes in the MDV and into the Ross Sea. Such a system is a potential habitat for extremophile life, similar to that already detected in the Blood Falls outflow, and may serve as a terrestrial analogue to potential extraterrestrial habits, where liquid surface waters are not expected to exist.

The background state leading to arsenic contamination of Bengal basin groundwater.

PubMed

Adel, Miah M

2005-12-01

The Bengal basin has the world's densest water diversion constructions on the natural courses of rivers. The most damaging water diversion construction is the Farakka Barrage upon the international River Ganges. The diversion of water through this barrage and other constructions upstream of it has reduced the Ganges flow rate by 2.5 times. The resulting downstream effects are the depletion of surface water resources, more withdrawal than recharge of groundwater, sinking groundwater table, spread in depth and extension of the vadose zone, changes in surface features, climatic changes, etc. An investigation was carried out to find the contributions of water diversion to the arsenic contamination of groundwater in the Bengal basin. The reasonable scenario for arsenic contamination is the oxygen deficiency in groundwater and aeration of arsenopyrites buried in the sediment that would remain under water prior to 1975. The mineral forms water-soluble compounds of arsenic when react with atmospheric oxygen. These soluble arsenic compounds infiltrates to the groundwater. This article summarizes the short-time and incomplete study-based quick conclusions reached by investigators that have totally avoided the vital issue of water diversion. It then shows the depleting condition of the water resources under continuing diversions, the generation of favorable condition for arsenic release, the reasons for low sulfur concentration, the reason for first contamination in the Hugly basin, and the hindrance to water's self-purification. The articles advocates that the restoration of the virgin wetland ecosystems in the Bengal basin following the stoppage of the inordinate amount of unilateral upstream water withdrawals can remove the catastrophe.

Prokaryotic responses to hydrostatic pressure in the ocean--a review.

PubMed

Tamburini, Christian; Boutrif, Mehdi; Garel, Marc; Colwell, Rita R; Deming, Jody W

2013-05-01

Effects of hydrostatic pressure on pure cultures of prokaryotes have been studied extensively but impacts at the community level in the ocean are less well defined. Here we consider hydrostatic pressure effects on natural communities containing both unadapted (piezosensitive) prokaryotes originating from surface water and adapted (including piezophilic) prokaryotes from the deep sea. Results from experiments mimicking pressure changes experienced by particle-associated prokaryotes during their descent through the water column show that rates of degradation of organic matter (OM) by surface-originating microorganisms decrease with sinking. Analysis of a much larger data set shows that, under stratified conditions, deep-sea communities adapt to in situ conditions of high pressure, low temperature and low OM. Measurements made using decompressed samples and atmospheric pressure thus underestimate in situ activity. Exceptions leading to overestimates can be attributed to deep mixing events, large influxes of surface particles, or provision of excessive OM during experimentation. The sediment-water interface, where sinking particles accumulate, will be populated by a mixture of piezosensitive, piezotolerant and piezophilic prokaryotes, with piezophilic activity prevailing deeper within sediment. A schematic representation of how pressure shapes prokaryotic communities in the ocean is provided, allowing a reasonably accurate interpretation of the available activity measurements. © 2013 Society for Applied Microbiology and Blackwell Publishing Ltd.

Comparative hydraulics of two fishery research circular tanks and recommendations for control of experimental bias

USGS Publications Warehouse

Odeh, M.; Schrock, R.M.; Gannam, A.

2003-01-01

Hydraulic characteristics inside two research circular tanks (1.5-m and 1.2-m diameter) with the same volume of water were studied to understand how they might affect experimental bias by influencing the behavior and development of juvenile fish. Water velocities inside each tank were documented extensively and flow behavior studied. Surface inflow to the 1.5-m tank created a highly turbulent and aerated surface, and produced unevenly distributed velocities within the tank. A low-flow velocity, or "dead" zone, persisted just upstream of the surface inflow. A single submerged nozzle in the 1.2-m tank created uniform flow and did not cause undue turbulence or introduce air. Flow behavior in the 1.5-m tank is believed to have negatively affected the feeding behavior and physiological development of a group of juvenile fall chinook salmon, Oncorhynchus tshawytscha. A new inflow nozzle design provided comparable flow behavior regardless of tank size and water depth. Maintaining similar hydraulic conditions inside tanks used for various biological purposes, including fish research, would minimize experimental bias caused by differences in flow behavior. Other sources of experimental bias are discussed and recommendations given for reporting and control of experimental conditions in fishery research tank experiments.

Past, present, and future life on Mars

NASA Technical Reports Server (NTRS)

McKay, C. P.

1998-01-01

Although the Viking results indicated that the surface of Mars is dry and lifeless, there is direct geomorphological evidence that Mars had large amounts of liquid water on its surface in the past. From a biological perspective the existence of liquid water, by itself, motivates the question of the origin of life on Mars. One of the martian meteorites dates back to this early period and may contain evidence consistent with life. The Mars environment 3.5 to 4.0 Gyr ago was comparable to that on the Earth at this time in that both contained liquid water. Life had originated on Earth and reached a fair degree of biological sophistication by 3.5 Gyr ago. To determine if life similarly arose on Mars may require extensive robotic exploration and ultimately human exploration. Intensive exploration of Mars will require a continued presence on the Martian surface and the development of a self sustaining community in which humans can live and work for very long periods of time. A permanent Mars research station can obtain its life support requirements directly from the martian environment enabling a high degree of self-sufficiency. In the longer term, it is possible that in the future we might restore a habitable climate on Mars, returning it to the life-bearing state it may have enjoyed early in its history.

Presence of organoarsenicals used in cotton production in agricultural water and soil of the Southern United States

USGS Publications Warehouse

Bednar, A.J.; Garbarino, J.R.; Ranville, J.F.; Wildeman, T.R.

2002-01-01

Arsenicals have been used extensively in agriculture in the United States as insecticides and herbicides. Mono- and disodium methylarsonate and dimethylarsinic acid are organoarsenicals used to control weeds in cotton fields and as defoliation agents applied prior to cotton harvesting. Because the toxicity of most organoarsenicals is less than that of inorganic arsenic species, the introduction of these compounds into the environment might seem benign. However, biotic and abiotic degradation reactions can produce more problematic inorganic forms of arsenic, such as arsenite [As(III)] and arsenate [As(V)]. This study investigates the occurrences of these compounds in samples of soil and associated surface and groundwaters. Preliminary results show that surface water samples from cotton-producing areas have elevated concentrations of methylarsenic species (>10 ??g of As/L) compared to background areas (<1 ??g of As/L). Species transformations also occur between surface waters and adjacent soils and groundwaters, which also contain elevated arsenic. The data indicate that point sources of arsenic related to agriculture might be responsible for increased arsenic concentrations in local irrigation wells, although the elevated concentrations did not exceed the new (2002) arsenic maximum contaminant level of 10 ??g/L in any of the wells sampled thus far.

Classification of sea ice types with single-band (33.6 GHz) airborne passive microwave imagery

NASA Astrophysics Data System (ADS)

Eppler, Duane T.; Farmer, L. Dennis; Lohanick, Alan W.; Hoover, Mervyn

1986-09-01

During March 1983 extensive high-quality airborne passive Ka band (33.6 GHz) microwave imagery and coincident high-resolution aerial photography were obtained of ice along a 378-km flight line in the Beaufort Sea. Analysis of these data suggests that four classes of winter surfaces can be distinguished solely on the basis of 33.6-GHz brightness temperature: open water, frazil, old ice, and young/first-year ice. New ice (excluding frazil) and nilas display brightness temperatures that overlap the range of temperatures characteristic of old ice and, to a lesser extent, young/first-year ice. Scenes in which a new ice or nilas are present in appreciable amounts are subject to substantial errors in classification if static measures of Ka band radiometric brightness temperature alone are considered. Textural characteristics of nilas and new ice, however, differ significantly from textural features characteristic of other ice types and probably can be used with brightness temperature data to classify ice type in high-resolution single-band microwave images. In any case, open water is radiometrically the coldest surface observed in any scene. Lack of overlap between brightness temperatures characteristic of other surfaces indicates that estimates of the areal extent of open water based on only 33.6-GHz brightness temperatures are accurate.

Past, present, and future life on Mars.

PubMed

McKay, C P

1998-05-01

Although the Viking results indicated that the surface of Mars is dry and lifeless, there is direct geomorphological evidence that Mars had large amounts of liquid water on its surface in the past. From a biological perspective the existence of liquid water, by itself, motivates the question of the origin of life on Mars. One of the martian meteorites dates back to this early period and may contain evidence consistent with life. The Mars environment 3.5 to 4.0 Gyr ago was comparable to that on the Earth at this time in that both contained liquid water. Life had originated on Earth and reached a fair degree of biological sophistication by 3.5 Gyr ago. To determine if life similarly arose on Mars may require extensive robotic exploration and ultimately human exploration. Intensive exploration of Mars will require a continued presence on the Martian surface and the development of a self sustaining community in which humans can live and work for very long periods of time. A permanent Mars research station can obtain its life support requirements directly from the martian environment enabling a high degree of self-sufficiency. In the longer term, it is possible that in the future we might restore a habitable climate on Mars, returning it to the life-bearing state it may have enjoyed early in its history.

Water-polysaccharide interactions in the primary cell wall of Arabidopsis thaliana from polarization transfer solid-state NMR.

PubMed

White, Paul B; Wang, Tuo; Park, Yong Bum; Cosgrove, Daniel J; Hong, Mei

2014-07-23

Polysaccharide-rich plant cell walls are hydrated under functional conditions, but the molecular interactions between water and polysaccharides in the wall have not been investigated. In this work, we employ polarization transfer solid-state NMR techniques to study the hydration of primary-wall polysaccharides of the model plant, Arabidopsis thaliana. By transferring water (1)H polarization to polysaccharides through distance- and mobility-dependent (1)H-(1)H dipolar couplings and detecting it through polysaccharide (13)C signals, we obtain information about water proximity to cellulose, hemicellulose, and pectins as well as water mobility. Both intact and partially extracted cell wall samples are studied. Our results show that water-pectin polarization transfer is much faster than water-cellulose polarization transfer in all samples, but the extent of extraction has a profound impact on the water-polysaccharide spin diffusion. Removal of calcium ions and the consequent extraction of homogalacturonan (HG) significantly slowed down spin diffusion, while further extraction of matrix polysaccharides restored the spin diffusion rate. These trends are observed in cell walls with similar water content, thus they reflect inherent differences in the mobility and spatial distribution of water. Combined with quantitative analysis of the polysaccharide contents, our results indicate that calcium ions and HG gelation increase the amount of bound water, which facilitates spin diffusion, while calcium removal disrupts the gel and gives rise to highly dynamic water, which slows down spin diffusion. The recovery of spin diffusion rates after more extensive extraction is attributed to increased water-exposed surface areas of the polysaccharides. Water-pectin spin diffusion precedes water-cellulose spin diffusion, lending support to the single-network model of plant primary walls in which a substantial fraction of the cellulose surface is surrounded by pectins.

Thermal infrared remote sensing of water temperature in riverine landscapes

USGS Publications Warehouse

Handcock, Rebecca N.; Torgersen, Christian E.; Cherkauer, Keith A.; Gillespie, Alan R.; Klement, Tockner; Faux, Russell N.; Tan, Jing; Carbonneau, Patrice E.; Piégay, Hervé

2012-01-01

Water temperature in riverine landscapes is an important regional indicator of water quality that is influenced by both ground- and surface-water inputs, and indirectly by land use in the surrounding watershed (Brown and Krygier, 1970; Beschta et al., 1987; Chen et al., 1998; Poole and Berman, 2001).Coldwater fishes such as salmon and trout are sensitive to elevated water temperature; therefore, water temperature must meet management guidelines and quality standards, which aim to create a healthy environment for endangered populations (McCullough et al., 2009). For example, in the USA, the Environmental Protection Agency (EPA) has established water quality standards to identify specific temperature criteria to protect coldwater fishes (Environmental Protection Agency, 2003). Trout and salmon can survive in cool-water refugia even when temperatures at other measurement locations are at or above the recommended maximums (Ebersole et al., 2001; Baird and Krueger, 2003; High et al., 2006). Spatially extensive measurements of water temperature are necessary to locate these refugia, to identify the location of ground- and surface-water inputs to the river channel, and to identify thermal pollution sources. Regional assessment of water temperature in streams and rivers has been limited by sparse sampling in both space and time. Water temperature has typically been measured using a network of widely distributed instream gages, which record the temporal change of the bulk, or kinetic, temperature of the water (Tk) at specific locations. For example, the State of Washington (USA) recorded water quality conditions at 76 stations within the Puget Lowlands eco region, which contains 12,721 km of streams and rivers (Washington Department of Ecology, 1998). Such gages are sparsely distributed, are typically located only in larger streams and rivers, and give limited information about the spatial distribution of water temperature.

Thermal infrared remote sensing of water temperature in riverine landscapes: Chapter 5

USGS Publications Warehouse

Carbonneau, Rebecca N.; Piégay, Hervé; Handcock, R.N; Torgersen, Christian E.; Cherkauer, K.A; Gillespie, A.R; Tockner, K; Faux, R. N.; Tan, Jing

2012-01-01

Water temperature in riverine landscapes is an important regional indicator of water quality that is influenced by both ground- and surface-water inputs, and indirectly by land use in the surrounding watershed (Brown and Krygier, 1970; Beschta et al., 1987; Chen et al., 1998; Poole and Berman, 2001). Coldwater fishes such as salmon and trout are sensitive to elevated water temperature; therefore, water temperature must meet management guidelines and quality standards, which aim to create a healthy environment for endangered populations (McCullough et al., 2009). For example, in the USA, the Environmental Protection Agency (EPA) has established water quality standards to identify specific temperature criteria to protect coldwater fishes (Environmental Protection Agency, 2003). Trout and salmon can survive in cool-water refugia even when temperatures at other measurement locations are at or above the recommended maximums (Ebersole et al., 2001; Baird and Krueger, 2003; High et al., 2006). Spatially extensive measurements of water temperature are necessary to locate these refugia, to identify the location of ground- and surface-water inputs to the river channel, and to identify thermal pollution sources. Regional assessment of water temperature in streams and rivers has been limited by sparse sampling in both space and time. Water temperature has typically been measured using a network of widely distributed instream gages, which record the temporal change of the bulk, or kinetic, temperature of the water (Tk) at specific locations. For example, the State of Washington (USA) recorded water quality conditions at 76 stations within the Puget Lowlands eco region, which contains 12,721 km of streams and rivers (Washington Department of Ecology, 1998). Such gages are sparsely distributed, are typically located only in larger streams and rivers, and give limited information about the spatial distribution of water temperature (Cherkauer et al., 2005).

Analytic algorithms for determining radiative transfer optical properties of ocean waters.

PubMed

Kaskas, Ayse; Güleçyüz, Mustafa C; Tezcan, Cevdet; McCormick, Norman J

2006-10-10

A synthetic model for the scattering phase function is used to develop simple algebraic equations, valid for any water type, for evaluating the ratio of the backscattering to absorption coefficients of spatially uniform, very deep waters with data from upward and downward planar irradiances and the remotely sensed reflectance. The phase function is a variable combination of a forward-directed Dirac delta function plus isotropic scattering, which is an elementary model for strongly forward scattering such as that encountered in oceanic optics applications. The incident illumination at the surface is taken to be diffuse plus a collimated beam. The algorithms are compared with other analytic correlations that were previously derived from extensive numerical simulations, and they are also numerically tested with forward problem results computed with a modified FN method.

Correcting Bidirectional Effects in Remote Sensing Reflectance from Coastal Waters

NASA Astrophysics Data System (ADS)

Stamnes, K. H.; Fan, Y.; Li, W.; Voss, K. J.; Gatebe, C. K.

2016-02-01

Understanding bidirectional effects including sunglint is important for GEO-CAPE for several reasons: (i) correct interpretation of ocean color data; (ii) comparing consistency of spectral radiance data derived from space observations with a single instrument for a variety of illumination and viewing conditions; (iii) merging data collected by different instruments operating simultaneously. We present a new neural network (NN) method to correct bidirectional effects in water-leaving radiance for both Case 1 and Case 2 waters. We also discuss a new BRDF and 2D sun-glint model that was validated by comparing simulated surface reflectances with Cloud Absorption Radiometer (CAR) data. Finally, we present an extension of our marine bio-optical model to the UV range that accounts for the seasonal dependence of the inherent optical properties (IOPs).

Dynamic factor modeling of ground and surface water levels in an agricultural area adjacent to Everglades National Park

NASA Astrophysics Data System (ADS)

Ritter, A.; Muñoz-Carpena, R.

2006-02-01

The extensive eastern boundary of Everglades National Park (ENP) in south Florida (USA) is subject to one the most expensive and ambitious environmental restoration projects in history. Understanding and predicting the interaction between the shallow aquifer and surface water is a key component for fine-tuning the process. The Frog Pond is an intensively instrumented agricultural 2023 ha area adjacent to ENP. The interactions among 21 multivariate daily time series (ground and surface water elevations, rainfall and evapotranspiration) available from this area were studied by means of dynamic factor analysis, a novel technique in the field of hydrology. This method is designed to determine latent or background effects governing variability or fluctuations in non-stationary time series. Water levels in 16 wells and two drainage ditch locations inside the area were selected as response variables, and canal levels and net recharge as explanatory variables. Elevations in the two canals delimiting the Frog Pond area were found to be the main factors explaining the response variables. This influence of canal elevations on water levels inside the area was complementary and inversely related to the distance between the observation point and each canal. Rainfall events do not affect daily water levels significantly but are responsible for instantaneous or localized groundwater responses that in some cases can be directly associated with the risk of flooding. This close coupling between surface and groundwater levels, that corroborates that found by other authors using different methods, could hinder on-going environmental restoration efforts in the area by bypassing the function of wetlands and other surface features. An empirical model with a reduced set of parameters was successfully developed and validated in the area by interpolating the results from the dynamic factor analysis across the spatial domain (coefficient of efficiency across the domain: 0.66-0.99). Although specific to the area, the resulting model is deemed useful for water management within the wide range of conditions similar to those present during the experimental period.

Tower-Perturbation Measurements in Above-Water Radiometry

NASA Technical Reports Server (NTRS)

Hooker, Stanford B. (Editor); Firestone, Elaine R. (Editor); Zibordi, Giuseppe; Berthon, Jean-Francois; DAlimonte, Davide; vanderLinde, Dirk; Brown, James W.

2003-01-01

This report documents the scientific activities which took place during June 2001 and June 2002 on the Acqua Alta Oceanographic Tower (AAOT) in the northern Adriatic Sea. The primary objective of these field campaigns was to quantify the effect of platform perturbations (principally reflections of sunlight onto the sea surface) on above-water measurements of water-leaving radiances. The deployment goals documented in this report were to: a) collect an extensive and simultaneous set of above- and in-water optical measurements under predominantly clear-sky conditions; b) establish the vertical properties of the water column using a variety of ancillary measurements, many of which were taken coincidently with the optical measurements; and c) determine the bulk properties of the environment using a diversity of atmospheric, biogeochemical, and meteorological techniques. A preliminary assessment of the data collected during the two field campaigns shows the perturbation in above-water radiometry caused by a large offshore structure is very similar to that caused by a large research vessel.

Tower-Perturbation Measurements in Above-Water Radiometry. Volume 23

NASA Technical Reports Server (NTRS)

Hooker, Stanford B. (Editor); Firestone, Elaine R. (Editor); Zibordi, Giuseppe; Berthon, Jean-Francois; D'Alimonte, Davide; vanderLinde, Dirk; Brown, James W.

2003-01-01

This report documents the scientific activities which took place during June 2001 and June 2002 on the Acqua Alta Oceanographic Tower (AAOT) in the northern Adriatic Sea. The primary objective of these field campaigns was to quantify the effect of platform perturbations (principally reflections of sunlight onto the sea surface) on above-water measurements of water-leaving radiances. The deployment goals documented in this report were to: a) collect an extensive and simultaneous set of above- and in-water optical measurements under predominantly clear-sky conditions; b) establish the vertical properties of the water column using a variety of ancillary measurements, many of which were taken coincidently with the optical measurements; and c) determine the bulk properties of the environment using a diversity of atmospheric, biogeochemical, and meteorological techniques. A preliminary assessment of the data collected during the two field campaigns shows the perturbation in above-water radiometry caused by a large offshore structure is very similar to that caused by a large research vessel.

Slime coating of kaolinite on chalcopyrite in saline water flotation

NASA Astrophysics Data System (ADS)

Li, Zhi-li; Rao, Feng; Song, Shao-xian; Li, Yan-mei; Liu, Wen-biao

2018-05-01

In saline water flotation, the salinity can cause a distinguishable slime coating of clay minerals on chalcopyrite particles through its effect on their electrical double layers in aqueous solutions. In this work, kaolinite was used as a representative clay mineral for studying slime coating during chalcopyrite flotation. The flotation of chalcopyrite in the presence and absence of kaolinite in tap water, seawater, and gypsum-saturated water and the stability of chalcopyrite and kaolinite particles in slurries are presented. Zeta-potential distributions and scanning electron microscopy images were used to characterize and explain the different slime coating degrees and the different flotation performances. Kaolinite particles induced slime coating on chalcopyrite surfaces and reduced chalcopyrite floatability to the greatest extent when the pH value was in the alkaline range. At 0.24wt% of kaolinite, the chalcopyrite floatability was depressed by more than 10% at alkaline pH levels in tap water. Salinity in seawater and gypsum-saturated water compressed the electrical double layers and resulted in extensive slime coating.

Impact of Extensive Urbanization on Summertime Rainfall in the Beijing Region and the Role of Local Precipitation Recycling

NASA Astrophysics Data System (ADS)

Wang, Jun; Feng, Jinming; Yan, Zhongwei

2018-04-01

In this study, we conducted nested high-resolution simulations using the Weather Research and Forecasting model coupled with a single-layer urban canopy model to investigate the impact of extensive urbanization on regional precipitation over the Beijing-Tianjin-Hebei region in China. The results showed that extensive urbanization decreased precipitation considerably over and downwind of Beijing city. The prevalence of impermeable urban land inhibits local evaporation that feeds moisture into the overlying atmosphere, decreasing relative humidity and atmospheric instability. The dynamic precipitation recycling model was employed to estimate the precipitation that originates from local surface evaporation and large-scale advection of moisture. Results showed that about 11% of the urbanization-induced decrease in total precipitation over the Greater Beijing Region and its surroundings was contributed by the decrease in local recycled precipitation, while the other part (89%) was due to decreasing large-scale advected precipitation. Results suggest that the low evaporation from urban land surfaces not only reduces the supply of water vapor for local recycled precipitation directly but also decreases the convective available potential energy and hence the conversion efficiency of atmospheric moisture into rainfall. The urbanization-induced variations in local recycled precipitation were found to be correlated with the net atmospheric moisture flux on a monthly time scale.

Creating poly(ethylene glycol) film on the surface of NiTi alloy by gamma irradiation

NASA Astrophysics Data System (ADS)

Yu, Hongyan; Yan, Jin; Ma, Huiling; Zeng, Xinmiao; Liu, Yang; Zhao, Xinqing

2015-07-01

NiTi alloy has been extensively utilized as biomaterials owing to its unique shape memory effect, superelasticity and biocompatibility. However, concern with the toxic and allergic responses of nickel potentially releasing from implants stimulated lots of researches of modification on NiTi alloy surface. Creating chemical bond attachment of bioorganic film on NiTi alloy surface could effectively inhibit Ni releasing and obtain bioactive functions for further application. In this work, to get a bioorganic surface, NiTi alloy was modified with poly(ethylene glycol) (PEG) film by gamma ray induced grafting or crosslinking. X-ray diffraction (XRD) spectrum, water contact angle geometer and X-ray photoelectron spectroscopy (XPS) techniques were used to characterize the NiTi surface. The results indicated that PEG was covalent bonded on NiTi alloy surface. Fluorescence microscope (FM) images for morphology of 1 day osteoblast culture on the PEG coated NiTi surface showed that PEG could improve cell proliferation on NiTi surface. Our work offers a way to introduce a bioorganic metal surface by gamma irradiation.

Macroscopic and microscopic investigation of Ni(II) sequestration on diatomite by batch, XPS, and EXAFS techniques.

PubMed

Sheng, Guodong; Yang, Shitong; Sheng, Jiang; Hu, Jun; Tan, Xiaoli; Wang, Xiangke

2011-09-15

Sequestration of Ni(II) on diatomite as a function of time, pH, and temperature was investigated by batch, XPS, and EXAFS techniques. The ionic strength-dependent sorption at pH < 7.0 was consistent with outer-sphere surface complexation, while the ionic strength-independent sorption at pH = 7.0-8.6 was indicative of inner-sphere surface complexation. EXAFS results indicated that the adsorbed Ni(II) consisted of ∼6 O at R(Ni-O) ≈ 2.05 Å. EXAFS analysis from the second shell suggested that three phenomena occurred at the diatomite/water interface: (1) outer-sphere and/or inner-sphere complexation; (2) dissolution of Si which is the rate limiting step during Ni uptake; and (3) extensive growth of surface (co)precipitates. Under acidic conditions, outer-sphere complexation is the main mechanism controlling Ni uptake, which is in good agreement with the macroscopic results. At contact time of 1 h or 1 day or pH = 7.0-8.0, surface coprecipitates occur concurrently with inner-sphere complexes on diatomite surface, whereas at contact time of 1 month or pH = 10.0, surface (co)precipitates dominate Ni uptake. Furthermore, surface loading increases with temperature increasing, and surface coprecipitates become the dominant mechanism at elevated temperature. The results are important to understand Ni interaction with minerals at the solid-water interface, which is helpful to evaluate the mobility of Ni(II) in the natural environment.

The estuarine chemistry and isotope systematics of 234,238U in the Amazon and Fly Rivers

USGS Publications Warehouse

Swarzenski, P.; Campbell, P.; Porcelli, D.; McKee, B.

2004-01-01

Natural concentrations of 238U and ??234U values were determined in estuarine surface waters and pore waters of the Amazon and Fly (Papua New Guinea) Rivers to investigate U transport phenomena across river-dominated land-sea margins. Discharge from large, tropical rivers is a major source of dissolved and solid materials transported to the oceans, and are important in defining not only oceanic mass budgets, but also terrestrial weathering rates. On the Amazon shelf, salinity-property plots of dissolved organic carbon, pH and total suspended matter revealed two vastly contrasting water masses that were energetically mixed. In this mixing zone, the distribution of uranium was highly non-conservative and exhibited extensive removal from the water column. Uranium removal was most pronounced within a salinity range of 0-16.6, and likely the result of scavenging and flocculation reactions with inorganic (i.e., Fe/Mn oxides) and organic colloids/particles. Removal of uranium may also be closely coupled to exchange and resuspension processes at the sediment/water interface. An inner-shelf pore water profile indicated the following diagenetic processes: extensive (???1 m) zones of Fe(III) - and, to a lesser degree, Mn(IV) - reduction in the absence of significant S(II) concentrations appeared to facilitate the formation of various authigenic minerals (e.g., siderite, rhodocrosite and uraninite). The pore water dissolved 238U profile co-varied closely with Mn(II). Isotopic variations as evidenced in ??234U pore waters values from this site revealed information on the origin and history of particulate uranium. Only after a depth of about 1 m did the ??234U value approach unity (secular equilibrium), denoting a residual lattice bound uranium complex that is likely an upper-drainage basin weathering product. This suggests that the enriched ??234U values represent a riverine surface complexation product that is actively involved in Mn-Fe diagenetic cycles and surface complexation reactions. In the Fly River estuary, 238U appears to exhibit a reasonably conservative distribution as a function of salinity. The absence of observed U removal does not necessarily imply non-reactivity, but instead may record an integration of concurrent U removal and release processes. There is not a linear correlation between ??234U vs. 1/ 238U that would imply simple two component mixing. It is likely that resuspension of bottom sediments, prolonged residence times in the lower reaches of the Fly River, and energetic particle-colloid interactions contribute to the observed estuarine U distribution. The supply of uranium discharged from humid, tropical river systems to the sea appears to be foremost influenced by particle/water interactions that are ultimately governed by the particular physiographic and hydrologic characteristics of an estuary. ?? 2004 Elsevier Ltd. All rights reserved.

Understanding solute transport at catchment scales by using a synthesis of bottom-up and top-down modelling approaches

NASA Astrophysics Data System (ADS)

Selle, Benny; Schwientek, Marc; Osenbrück, Karsten

2013-04-01

The understanding of flow paths and travel times of water and solutes in catchments can be substantially improved by a combination of bottom-up and top-down modelling approaches. This hypothesis was tested for the 180 km² Ammer catchment in south-western Germany in which the landuse is dominated by agricultural and urban areas. The Ammer River with a mean discharge of 1 m³/s is mainly fed by springs from karstified and fractured aquifers. A limestone aquifer is extensively used for groundwater production. As a first step, we analysed measured concentrations of major ions, selected organic micro-pollutants and environmental tracers for surface water, springs and deep groundwater from wells using typical top-down approaches such as principal component analysis and lumped parameter models. From these approaches, we gained an initial understanding of water and solute fluxes in the catchment. The initial hypotheses on subsurface flow paths and travel times were subsequently tested using a numerical, 3-D groundwater model as a typical bottom-up approach. Our synthesis of top-down and bottom-up approaches provided us with a reliable picture of the dominant processes governing water and solute fluxes in the Ammer catchment. Several spring waters indicated mixing with wastewater. These contaminations were indentified to be caused by either recharge of surface water or leaky sewer systems. Deep percolation below the plant root zone polluted with agrochemicals was found to affect most springs and surface waters resulting in nitrate concentrations of approximately 30 mg/l. This process also influenced some of the drinking-water wells, although water quality for most of these wells is still relatively high due to some attenuation of pollutants but - above all - due to a significant proportion of groundwater with ages > 50 years. However, water quality will likely decrease if contaminants break through and/or conditions for microbiological attenuation process will deteriorate, for example due to depletion of suitable electron donors.

Recharge source identification using isotope analysis and groundwater flow modeling for Puri city in India

NASA Astrophysics Data System (ADS)

Nayak, P. C.; Vijaya Kumar, S. V.; Rao, P. R. S.; Vijay, T.

2017-11-01

The holy city of Lord Jagannath is situated on the sea shore of the Bay of Bengal in Odisha state in India. Puri is a city of high religious importance and heritage value, details of the rituals, fairs, and festivals, and related aspects are covered extensively. It is found that water levels in two wells (Ganga and Yamuna) are declining and the causes are studied by undertaking modeling study of rainfall-recharge processes, surface water-groundwater interactions, and increasing demands due to urbanization at basin scale. Hydrochemical analysis of groundwater samples indicates that pH value is varying from 7 to 8.4 and electrical conductivity (EC) is found in between 238 and 2710 μmhos/cm. The EC values indicate that the shallow groundwater in Puri is not saline. Stable isotopic signatures of O-18, Deuterium indicate two different sources are active in the city area. In most of the handpumps, water recharged by the surface water sources. From the current investigation, it is evident that in a few handpumps and most of the dug-wells, isotopic signatures of water samples resembles with local precipitation. The groundwater recharge is taking place from the north-southern direction. Visual MODFLOW has been used for studying groundwater aspects and different scenarios have been developed. It is suggested to maintain water level in Samang Lake to restore depletion in groundwater level in two wells.

Health risks from large-scale water pollution: Current trends and implications for improving drinking water quality in the lower Amu Darya drainage basin, Uzbekistan

NASA Astrophysics Data System (ADS)

Törnqvist, Rebecka; Jarsjö, Jerker

2010-05-01

Safe drinking water is a primary prerequisite to human health, well being and development. Yet, there are roughly one billion people around the world that lack access to safe drinking water supply. Health risk assessments are effective for evaluating the suitability of using various water sources as drinking water supply. Additionally, knowledge of pollutant transport processes on relatively large scales is needed to identify effective management strategies for improving water resources of poor quality. The lower Amu Darya drainage basin close to the Aral Sea in Uzbekistan suffers from physical water scarcity and poor water quality. This is mainly due to the intensive agriculture production in the region, which requires extensive freshwater withdrawals and use of fertilizers and pesticides. In addition, recurrent droughts in the region affect the surface water availability. On average 20% of the population in rural areas in Uzbekistan lack access to improved drinking water sources, and the situation is even more severe in the lower Amu Darya basin. In this study, we consider health risks related to water-borne contaminants by dividing measured substance concentrations with health-risk based guideline values from the World Health Organisation (WHO). In particular, we analyse novel results of water quality measurements performed in 2007 and 2008 in the Mejdurechye Reservoir (located in the downstream part of the Amu Darya river basin). We furthermore identify large-scale trends by comparing the Mejdurechye results to reported water quality results from a considerable stretch of the Amu Darya river basin, including drainage water, river water and groundwater. The results show that concentrations of cadmium and nitrite exceed the WHO health-risk based guideline values in Mejdurechye Reservoir. Furthermore, concentrations of the since long ago banned and highly toxic pesticides dichlorodiphenyltrichloroethane (DDT) and γ-hexachlorocyclohexane (γ-HCH) were detected in the reservoir water for the first time in a decade. However, a relatively pronounced temporal variability in concentrations was observed for many of the substances, implying that the reservoir could contain low-risk waters temporarily. Health risk factors related to lead and chromium concentrations in groundwater were up to 200 times higher than for river water. The identified major divergence in health risk between groundwater and surface water illuminates the risk of using groundwater for drinking water supply during recurrent surface water deficits in the study area. However, the severe water scarcity and lack of financial resources in the region makes the choices of alternative water supply sources limited. Due to the presence of multiple contaminants, it appears reasonable that the aggregated toxicity of contaminant mixtures should be in focus in surface and groundwater water monitoring and management in the region. Key words: Aral Sea, Drinking water, Groundwater, Health Risk, Surface Water

Informing Extension Program Development through Audience Segmentation: Targeting High Water Users

ERIC Educational Resources Information Center

Huang, Pei-wen; Lamm, Alexa J.; Dukes, Michael D.

2016-01-01

Human reliance on water has led to water issues globally. Although extension professionals have made efforts successfully to educate the general public about water conservation to enhance water resource sustainability, difficulty has been found in reaching high water users, defined as residents irrigating excessively to their landscape irrigation…

18 CFR 701.207 - Extension of time limits for WRC initial and final determinations.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 18 Conservation of Power and Water Resources 2 2012-04-01 2012-04-01 false Extension of time limits for WRC initial and final determinations. 701.207 Section 701.207 Conservation of Power and Water Resources WATER RESOURCES COUNCIL COUNCIL ORGANIZATION Availability of Information § 701.207 Extension of...

18 CFR 701.207 - Extension of time limits for WRC initial and final determinations.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 18 Conservation of Power and Water Resources 2 2011-04-01 2011-04-01 false Extension of time limits for WRC initial and final determinations. 701.207 Section 701.207 Conservation of Power and Water Resources WATER RESOURCES COUNCIL COUNCIL ORGANIZATION Availability of Information § 701.207 Extension of...

18 CFR 701.207 - Extension of time limits for WRC initial and final determinations.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 18 Conservation of Power and Water Resources 2 2013-04-01 2012-04-01 true Extension of time limits for WRC initial and final determinations. 701.207 Section 701.207 Conservation of Power and Water Resources WATER RESOURCES COUNCIL COUNCIL ORGANIZATION Availability of Information § 701.207 Extension of...

18 CFR 701.207 - Extension of time limits for WRC initial and final determinations.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 18 Conservation of Power and Water Resources 2 2010-04-01 2010-04-01 false Extension of time limits for WRC initial and final determinations. 701.207 Section 701.207 Conservation of Power and Water Resources WATER RESOURCES COUNCIL COUNCIL ORGANIZATION Availability of Information § 701.207 Extension of...

18 CFR 701.207 - Extension of time limits for WRC initial and final determinations.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 18 Conservation of Power and Water Resources 2 2014-04-01 2014-04-01 false Extension of time limits for WRC initial and final determinations. 701.207 Section 701.207 Conservation of Power and Water Resources WATER RESOURCES COUNCIL COUNCIL ORGANIZATION Availability of Information § 701.207 Extension of...

Massive radius-dependent flow slippage in carbon nanotubes

NASA Astrophysics Data System (ADS)

Siria, Alessandro; Secchi, Eleonora; Marbach, Sophie; Niguès, Antoine; Stein, Derek; Bocquet, Lydéric

2016-11-01

Nanofluidics is the frontier where the continuum picture of fluid mechanics confronts the atomic nature of matter. Recent reports indicate that carbon nanotubes exhibit exceptional water transport properties due to nearly frictionless interfaces and this has stimulated interest in nanotube-based membranes for desalination, nano-filtration, and energy harvesting. However, the fundamental mechanisms of water transport inside nanotubes and at water-carbon interfaces remain controversial, as existing theories fail to provide a satisfying explanation for the limited experimental results. We report a study of water jets emerging from single nanotubes made of carbon and boron-nitride materials. Our experiments reveal extensive and radius-dependent surface slippage in carbon nanotubes (CNT). In stark contrast, boron-nitride nanotubes (BNNT), which are crystallographically similar to CNTs but electronically different, exhibit no slippage. This shows that slippage originates in subtle atomic-scale details of the solid-liquid interface. ERC StG - NanoSOFT.

Dictating anisotropic electric conductivity of a transparent copper nanowire coating by the surface structure of wood.

PubMed

Guo, Huizhang; Büchel, Martin; Li, Xing; Wäckerlin, Aneliia; Chen, Qing; Burgert, Ingo

2018-05-01

In this article, a robust, air-stable, flexible and transparent copper (Cu) nanowire (NW) network coating on the surface of the wood is presented, based on a fusion welding of the Cu NWs by photonic curing. Thereby, an anisotropic conductivity can be achieved, which is originating from the structural organization of the wood body and its surface. Furthermore, the Cu NWs are protected from oxidation or wear by a commercially available paraffin wax-polyolefin, which also results in surface water repellency. The developed processing steps present a facile and flexible routine for applying Cu NW transparent conductors to abundant biomaterials and solve current manufacturing obstacles for corrosion-resistant circuits while keeping the natural appearance of the substrate. It may open a venue for more extensive utilization of materials from renewable resources such as wood for electronic devices in smart buildings or mobility applications. © 2018 The Author(s).

Water flow through temperate glaciers

USGS Publications Warehouse

Fountain, A.G.; Walder, J.S.

1998-01-01

Understanding water movement through a glacier is fundamental to several critical issues in glaciology, including glacier dynamics, glacier-induced floods, and the prediction of runoff from glacierized drainage basins. to this end we have synthesized a conceptual model os water movement through a temperate glacier from the surface to the outlet stream. Processes that regulate the rate and distribution of water input at the glacier surface and that regulate water movement from the surface to the bed play important but commonly neglected roles in glacier hydrology. Where a glacier is covered by a layer of porous, permeable firn (the accumulation zone), the flux of water to the glacier interior varies slowly because the firn temporarily stores water and thereby smooths out variations in the supply rate. In the firn-free ablation zone, in contrast, the flux of water into the glacier depends directly on the rate of surface melt or rainfall and therefore varies greatly in time. Water moves from the surface to the bed through an upward branching arborescent network consisting of both steeply inclined conduits, formed by the enlargement of intergranular veins, and gently inclined conduits, sprqwned by water flow along the bottoms of near-surface fractures (crevasses). Englacial drainage conduits deliver water to the glacier bed at a linited number of points, probably a long distance downglacier of where water enters the glacier. Englacial conduits supplied from the accumulation zone are quasi steady state features that convey the slowly varying water flux delivered via the firn. their size adjusts so that they are usually full of water and flow is pressurized. In contrast, water flow in englacial conduits supplied from the ablation area is pressurized only near times of peak daily flow or during rainstorms; flow is otherwise in an open-channel configuration. The subglacial drainage system typically consists of several elements that are distinct both morpphologically and hydrologically. An up-glacier branching, arborescent network of channels incised into the basal ice conveys water rapidly. Much of the water flux to the bed probably enters directly into the arborescent channel network, which covers only a small fraction of the glacier bed. More extensive spatially is a nonarborescent network, which commonly includes cabities (gaps between the glacier sole and bed), channels incised into the bed, and a layer of permeable sediment. The nonarborescent network conveys water slowly and is usually poorly connected to the arborescent system. The arborescent channel network largely collapses during winter but reforms in the spring as the first flush of meltwater to the bed destabilizes the cavities within the nonarborescent net6work. The volume of water stored by a glacier varies diurnally and seasonally. Small, temperate alpine glaciers seem to attain a maximum seasonal water storage of ~200 mm of water averaged over the area of the glacier bed, with daily fluctuations of as much as 20-30 mm. The likely storage capacity of subglacial cavities is insufficient to account for estimated stored water volumes, so most water storage may actually occur englacially. Sotred water may also be released abruptly and catastrophically in the form of outburst floods.

Cycling of Redox-Sensitive Trace Elements in the Lower Mississippi River Delta as a Function of River Stage and Sediment Heterogeneity

NASA Astrophysics Data System (ADS)

Telfeyan, K.; Breaux, A.; Kim, J.; Johannesson, K. H.; Kolker, A.; Cable, J. E.

2015-12-01

Telfeyan, K.1, Johannesson, K.H.1, Breaux, A.M.2,1, Kim, J.3, Kolker, A.S.2,1, Cable, J.E.31 Department of Earth and Environmental Sciences, Tulane University, New Orleans, LA, USA 2 Louisiana Universities Marine Consortium, Cocoderie, LA, USA 3 Department of Marine Sciences, University of North Carolina, Chapel Hill, NC, USA The Mississippi River drains 40% of the continental United States and discharges 0.1 Pg sediment and an average of 18,400 m3 s-1 water annually to the Gulf of Mexico1. The flow of groundwater through the Mississippi River Delta (MRD) to the Gulf, however, has been largely understudied and is typically overlooked in MRD biogeochemical studies. Previous work demonstrated that sand-rich paleochannels that maintain a hydrologic connection to the Mississippi River could transport riverine water to the MRD2. We present data from biogeochemical surveys at 2 sites in the lower MRD to explore the effects of river-derived submarine groundwater discharge on the biogeochemistry of MRD wetlands. Lac des Allemands is a fresh water lake and Myrtle Grove is a brackish canal with variable salinities. Both are surrounded by extensive wetlands. Over the course of a year, surface water, shallow pore water, and deeper groundwaters were sampled to understand the cycling of redox-sensitive trace elements (Fe, Mn, V, As) and the potential supply from groundwater to surface water bodies. Major ion chemistry suggests that both Lac des Allemands and Myrtle Grove Canal receive river-derived terrestrial water at their heads, the flux of which varies as a function of river stage. However, the lateral flow through adjacent wetlands is altered as a function of sediment heterogeneity. Evidence for sulfate reduction exists in the near-surface sediment and at depth where a continuous vertical organic matter layer exists. In sand-rich layers, iron reduction buffers redox conditions, and V varies inversely with dissolved Fe. Concentrations of V and As are much greater in near-surface pore waters than in deeper groundwaters and in surface waters, suggesting that the subterranean estuary serves as a sink of these redox-sensitive trace elements. [1] Bianchi and Allison (2009) PNAS 1068085-8092. [2] Kolker et al. (2013) Journal of Hydrology 498 319-334.

Liquid-infused nanostructured surfaces with extreme anti-ice and anti-frost performance.

PubMed

Kim, Philseok; Wong, Tak-Sing; Alvarenga, Jack; Kreder, Michael J; Adorno-Martinez, Wilmer E; Aizenberg, Joanna

2012-08-28

Ice-repellent coatings can have significant impact on global energy savings and improving safety in many infrastructures, transportation, and cooling systems. Recent efforts for developing ice-phobic surfaces have been mostly devoted to utilizing lotus-leaf-inspired superhydrophobic surfaces, yet these surfaces fail in high-humidity conditions due to water condensation and frost formation and even lead to increased ice adhesion due to a large surface area. We report a radically different type of ice-repellent material based on slippery, liquid-infused porous surfaces (SLIPS), where a stable, ultrasmooth, low-hysteresis lubricant overlayer is maintained by infusing a water-immiscible liquid into a nanostructured surface chemically functionalized to have a high affinity to the infiltrated liquid and lock it in place. We develop a direct fabrication method of SLIPS on industrially relevant metals, particularly aluminum, one of the most widely used lightweight structural materials. We demonstrate that SLIPS-coated Al surfaces not only suppress ice/frost accretion by effectively removing condensed moisture but also exhibit at least an order of magnitude lower ice adhesion than state-of-the-art materials. On the basis of a theoretical analysis followed by extensive icing/deicing experiments, we discuss special advantages of SLIPS as ice-repellent surfaces: highly reduced sliding droplet sizes resulting from the extremely low contact angle hysteresis. We show that our surfaces remain essentially frost-free in which any conventional materials accumulate ice. These results indicate that SLIPS is a promising candidate for developing robust anti-icing materials for broad applications, such as refrigeration, aviation, roofs, wires, outdoor signs, railings, and wind turbines.

Case History: Merging the Tools of DC Resistivity and Fracture Trace Analysis for Locating High Yield Domestic Water Wells in Karst Terrain, Shenandoah Valley, Virginia, USA

NASA Astrophysics Data System (ADS)

Frangos, W.; Eaton, L. S.

2004-05-01

The karstic eastern margin of Virginia's Shenandoah Valley hosts large volumes of high quality ground water in discrete zones or pockets. Industrial and culinary exploitation poses a challenging exploration problem. Recent work by the authors using geophysical and aerial photogrammetric techniques resulted in the successful location of three high- yield water wells. This indirect methodology increases the probability of locating valuable wells by locating geologic features that may harbor water-bearing zones. The eastern Shenandoah Valley is geologically complex. The underlying bedrock is dominantly limestones, dolomites, and shales of Cambrian age that have been extensively folded, fractured, and faulted. Geomorphologic features such as solution cavities, caves, disappearing streams, and sinkholes are common. Extensive alluvial fan and river terrace deposits, comprised dominantly of quartzite gravel and sand, cover much of the land surface, and fill surface depressions. The combination of sand and gravel filtering and large storage capacity in the voids makes this region ideal for producing a large quantity of high quality groundwater. Two sites were investigated for karst aquifers near the town of Stuarts Draft. Interbedded limestones and dolomites underlie Barth Farm, situated on the north bank of the South River. The owners attempted to installed a water well to service an active vineyard. The drilling located a previously unknown, water-filled cavern ~5 m below the surface; subsequent high pumping rates in finishing the well resulted in a surface collapse and the creation of a sinkhole. A second effort, offset by ~30 meters, resulted in a catastrophic collapse, and seriously endangered the lives of the drillers. A subsequent dipole-dipole DC resistivity survey delineated a conductive zone coincident with the two sinkholes. Fracture trace analysis of pre-drilling aerial photographs indicates the presence of lineaments that pass through this drilling site, suggesting underground voids. This knowledge could serve as a future guide for both well placement and for site evaluation of the potential for sinkhole occurrence. The second site is located 5 km due south of the Barth Farm. A potential residential and farm operations site was being evaluated for construction based on the availability of adequate water yield. Previous attempts of drilling on a contiguous property resulted in a fruitless 800 ft dry hole. The site is mapped as folded sedimentary rock (limestone, dolomite, shale), but outcrops are masked by ~25 m thick alluvial deposits of quartzite gravel and sand. The presence of numerous sinkholes and ponds suggests karst terrain. Fracture trace analysis was initially conducted to identify zones that may contain water-bearing conduits. A dipole-dipole DC resistivity survey followed in areas specifically delineated by the fracture trace analysis. The results lead to two strong wells, one producing 60-100 gpm at 286 ft deep, and the second well 40 gpm at 395 ft. Based on the previous drilling difficulty in this terrain, the complementary tools of high-resolution resistivity and fracture trace analysis are effective in locating high-yield water wells in karst environments. In the first case, the shallow aquifer was detected directly by the resistivity and indirectly by photo interpretation; in the second, both methods provided indirect evidence. The combined use of near-surface indications of underlying karst reservoirs is recommended for future exploration work.

Upwellings mitigated Plio-Pleistocene heat stress for reef corals on the Florida platform (USA)

NASA Astrophysics Data System (ADS)

Brachert, T. C.; Reuter, M.; Krüger, S.; Kirkerowicz, J.; Klaus, J. S.

2015-10-01

The fast growing calcareous skeletons of zooxanthellate reef corals (z-corals) represent unique environmental proxy archives through their oxygen and carbon stable isotope composition (δ18O, δ13C). In addition, the accretion of the skeleton itself is ultimately linked to the environment and responds with variable growth rates (extension rate) and density to environmental changes. Here we present classical proxy data (δ18O, δ13C) in combination with calcification records from 15 massive z-corals. The z-corals were sampled from four interglacial units of the Florida carbonate platform (USA) dated approximately 3.2, 2.9, 1.8 and 1.2 Ma (middle Pliocene to early Pleistocene). The z-corals (Solenastrea, Orbicella, Porites) derive from unlithified shallow marine carbonates and were carefully screened for primary preservation suited for proxy analysis. We show that skeletal accretion was non-linear and responded with decreasing overall calcification rates (decreasing extension rate but increasing density) to warmer water temperatures. Under high annual water temperatures, inferred from subannually resolved δ18O data, skeletal bulk density was high, but extension rates and overall calcification rates were at a minimum (endmember scenario 1). Maximum skeletal density was reached during the summer season giving rise to a growth band of high density within the annually banded skeletons ("high density band", HDB). With low mean annual water temperatures (endmember scenario 2), bulk skeletal density was low but extension rates and calcification rates reached a maximum, and under these conditions the HDB formed during winter. Although surface water temperatures in the Western Atlantic warm pool during the interglacials of the late Neogene where ∼ 2 °C higher than they are in the present-day, intermittent upwelling of cool, nutrient rich water mitigated water temperatures off southwestern Florida in the middle of the Atlantic warm pool and created temporary refuges for z-coral growth. Based on the subannually resolved δ18O and δ13C records, the duration of the upwelling episodes causing the endmember 2 conditions was variable and lasted from a few years to a number of decades. The episodes of upwelling were interrupted by phases without upwelling (endmember 1) which lasted for at least a few years and led to high surface water temperatures. This variable environment is likely one of the reasons why the coral fauna is dominated by the eurytopic genus Solenastrea, also a species resistant to high turbidity. Over a period of ∼ 50 years, the oldest subannually resolved proxy record available (3.2 Ma) documents a persistent occurrence of the HDB during winter. In contrast, the HDB forms in summer in modern z-corals from the Florida reef tract. We suggest this difference to be the expression of a tendency towards decreasing upwelling since the middle Pliocene. The number of z-coral sclerochronological records for this time period is still, however, rather low and requires an improved resolution through data from additional time-slices. These data can contribute to predicting the effects of future ocean warming on z-coral health along the Florida reef tract.

Symmetric and asymmetric capillary bridges between a rough surface and a parallel surface.

PubMed

Wang, Yongxin; Michielsen, Stephen; Lee, Hoon Joo

2013-09-03

Although the formation of a capillary bridge between two parallel surfaces has been extensively studied, the majority of research has described only symmetric capillary bridges between two smooth surfaces. In this work, an instrument was built to form a capillary bridge by squeezing a liquid drop on one surface with another surface. An analytical solution that describes the shape of symmetric capillary bridges joining two smooth surfaces has been extended to bridges that are asymmetric about the midplane and to rough surfaces. The solution, given by elliptical integrals of the first and second kind, is consistent with a constant Laplace pressure over the entire surface and has been verified for water, Kaydol, and dodecane drops forming symmetric and asymmetric bridges between parallel smooth surfaces. This solution has been applied to asymmetric capillary bridges between a smooth surface and a rough fabric surface as well as symmetric bridges between two rough surfaces. These solutions have been experimentally verified, and good agreement has been found between predicted and experimental profiles for small drops where the effect of gravity is negligible. Finally, a protocol for determining the profile from the volume and height of the capillary bridge has been developed and experimentally verified.

Ground water in the Piedmont upland of central Maryland

USGS Publications Warehouse

Richardson, Claire A.

1982-01-01

This report, describing ground-water occurrence in a 130-square-mile area of the central Maryland Piedmont, was originally designed for use by the U.S. Environmental Protection Agency in replying to a request for designation of the aquifers to be the sole or principal source of ground water. However, the information contained in the report is pertinent to other crystalline-rock areas as well. The study area is underlain chiefly by crystalline rocks and partly by unaltered sandstones and siltstones. The ground water is derived from local precipitation and generally occurs under water-table conditions. Its movement is restricted by the lack of interconnected openings, and most ground water occurs within 300 feet of the land surface. Hydrographs indicate no long-term change in ground-water storage. A few wells yield more than 100 gallons per minute, but about 70 percent of 286 inventoried wells yield 10 gallons per minute or less; most specific capacities are less than 1.0 gallon per minute per foot. The ground-water quality is generally satisfactory without treatment, and there are no known widespread pollution problems. Estimated daily figures on ground-water use are as follows: 780,000 gallons for domestic purposes; 55,000, for commercial purposes; and 160,000, for public supply. Although part of the area is served by an existing surface-water supply and could be served by possible extension of it and of other public-supply water mains, much of the rural population is dependent on the ground water available from private wells tapping the single aquifer that underlies any given location. Neither the ground-water conditions nor this dependence on individual wells is unique to the study area, but, rather, applies to the entire Piedmont province.

33 CFR 151.1513 - Extension of compliance date.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Extension of compliance date. 151.1513 Section 151.1513 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... basis for the extension will be promptly posted on the Internet. Extensions will be for no longer than...

33 CFR 151.1513 - Extension of compliance date.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Extension of compliance date. 151.1513 Section 151.1513 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... basis for the extension will be promptly posted on the Internet. Extensions will be for no longer than...

33 CFR 151.1513 - Extension of compliance date.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Extension of compliance date. 151.1513 Section 151.1513 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... basis for the extension will be promptly posted on the Internet. Extensions will be for no longer than...

Occurrence of phthalates in aquatic environment and their removal during wastewater treatment processes: a review.

PubMed

Gani, Khalid Muzamil; Tyagi, Vinay Kumar; Kazmi, Absar Ahmad

2017-07-01

Phthalates are plasticizers and are concerned environmental endocrine-disrupting compounds. Due to their extensive usage in plastic manufacturing and personal care products as well as the potential to leach out from these products, phthalates have been detected in various aquatic environments including drinking water, groundwater, surface water, and wastewater. The primary source of their environmental occurrence is the discharge of phthalate-laden wastewater and sludge. This review focuses on recent knowledge on the occurrence of phthalate in different aquatic environments and their fate in conventional and advanced wastewater treatment processes. This review also summarizes recent advances in biological removal and degradation mechanisms of phthalates, identifies knowledge gaps, and suggests future research directions.

Harvesting electrostatic energy using super-hydrophobic surfaces

NASA Astrophysics Data System (ADS)

Pociecha, Dominik; Zylka, Pawel

2016-11-01

Almost all environments are now being extensively populated by miniaturized, nano-powered electronic sensor devices communicated together through wireless sensor networks building Internet of Things (IoT). Various energy harvesting techniques are being more and more frequently proposed for battery-less powering of such remote, unattended, implantable or wearable sensors or other low-power electronic gadgets. Energy harvesting relays on extracting energy from the ambient sources readily accessible at the sensor location and converting it into electrical power. The paper exploits possibility of generating electric energy safely accessible for nano-power electronics using tribo-electric and electrostatic induction phenomena displayed at super-hydrophobic surfaces impinged by water droplets. Mechanism of such interaction is discussed and illustrated by experimental results.

Sea Surface Salinity Variability in Response to the Congo River Discharge

NASA Astrophysics Data System (ADS)

Moller, D.; Chao, Y.; Farrara, J. D.; Schumann, G.; Andreadis, K.

2014-12-01

Sea surface salinity (SSS) variability associated with the Congo River discharge is examined using Aquarius satellite-retrieved SSS data and vertical profiles of salinity measured by the Argo floats. The Congo River plume can be clearly identified in the Aquarius SSS data with a westward extension of 500 to 1000 km off the coast of the Democratic Republic of Congo (DRC). The peak amplitude of the SSS variability associated with the Congo River discharge exceeds 2.0 psu. Using the first two years of Aquarius data, a well-defined seasonal cycle is described: maximum fresh-water anomalies are found in the boreal winter and spring seasons. The fresh-water anomalies during the 2012-2013 winter and spring seasons are significantly fresher than the 2011-2012 winter and spring seasons. Vertical profiles of salinity derived from the Argo floats reveal that these fresh-water anomalies can be traced to 40 meters below the sea surface. Combining the Aquarius SSS data with the Argo vertical profiles of salinity, the 3D volume of these fresh-water anomalies can be inferred and used to estimate the Congo River discharge. Reasonably good agreement is found between the Congo River discharge as observed by a stream gauge at Kinshasa and that estimated from the combined Aquarius and Argo data, indicating that Aquarius data can be used to close the fresh-water budget between the coastal ocean and the Congo River. The precipitation minus evaporation portion of the freshwater flux is found to play a secondary role in this region.

Overview of water resources in and near Wichita and Affiliated Tribes treaty lands in western Oklahoma

USGS Publications Warehouse

Abbott, Marvin M.; Tortorelli, R.L.; Becker, M.F.; Trombley, T.J.

2003-01-01

This report is an overview of water resources in and near the Wichita and Affiliated Tribes treaty lands in western Oklahoma. The tribal treaty lands are about 1,140 square miles and are bordered by the Canadian River on the north, the Washita River on the south, 98? west longitude on the east, and 98? 40' west longitude on the west. Seventy percent of the study area lies within the Washita River drainage basin and 30 percent of the area lies within the Canadian River drainage basin. March through June are months of greatest average streamflow, with 49 to 57 percent of the annual streamflow occurring in these four months. November through February, July, and August have the least average streamflow with only 26 to 36 percent of the annual streamflow occurring in these six months. Two streamflow-gaging stations, Canadian River at Bridgeport and Cobb Creek near Fort Cobb, indicated peak streamflows generally decrease with regulation. Two other streamflow-gaging stations, Washita River at Carnegie and Washita River at Anadarko, indicated a decrease in peak streamflows after regulation at less than the 100-year recurrence and an increase in peak streamflows greater than the 100-year recurrence. Canadian River at Bridgeport and Washita River at Carnegie had estimated annual low flows that generally increased with regulation. Cobb Creek near Fort Cobb had a decrease of estimated annual low flows after regulation. There are greater than 900 ground-water wells in the tribal treaty lands. Eighty percent of the wells are in Caddo County.The major aquifers in the study area are the Rush Springs Aquifer and portions of the Canadian River and Washita River valley alluvial aquifers. The Rush Springs Aquifer is used extensively for irrigation as well as industrial and municipal purposes, especially near population centers.The Canadian River and Washita River valley alluvial aquifers are not used extensively in the study area. Well yields from the Rush Springs Aquifer ranged from 11 to greater than 850 gallons per minute. The Rush Springs Aquifer is recharged by the infiltration of precipitation. The estimated recharge is about 1.80 inches per year evenly distributed over the outcrop of the aquifer in the study area. Principal factors affecting the water quality in the study area include geology, agricultural practices,and oil and gas production. Calcium, magnesium, sulfate, and bicarbonate are the dominant dissolved constituents in water in the study area. Interquartile dissolved-solids concentrations in surface-water samples in the study area generally were greater than interquartile concentrations in ground-water samples. Median dissolved-solids concentrations for ground-water samples from Canadian River, Ionine Creek, Spring Creek,and Washita River Basins, which ranged from 535 to 1,195 milligrams per liter,exceeded the U.S. Environmental Protection Agency Secondary Drinking Water Standard of 500 milligrams per liter. Interquartile sulfate concentrations in surface-water samples in the study area generally were greater than interquartile concentrations in ground-water samples. Median sulfate concentrations from ground-water samples in the Canadian River, IonineCreek,and Spring Creek Basins, which ranged from 385 to 570 milligrams per liter, exceeded the U.S. Environmental Protection Agency Secondary Drinking Water Standard of 250 milligrams per liter. Nitrite plus nitrate as nitrogen concentrations in surface-water samples in the study area generally were less than concentrations in ground-water samples. The median nitrite plus nitrate as nitrogen concentration in ground water was 9.8 milligrams per liter, suggesting almost one-half the ground-water samples exceeded the U.S. Environmental Protection Agency Primary Drinking Water Standard (10 milligrams per liter). An estimated 100 million gallons of water per day were withdrawn from surface and ground water for all uses in

Ocean Surface Emissivity at L-band (1.4 GHz): The Dependence on Salinity and Roughness

NASA Technical Reports Server (NTRS)

LeVine, D. M.; Lang, R.; Wentz, F.; Messiner, T.

2012-01-01

A characterization of the emissivity of sea water at L-band is important for the remote sensing of sea surface salinity. Measurements of salinity are currently being made in the radio astronomy band at 1.413 GHz by ESA's Soil Moisture and Ocean Salinity (SMOS) mission and NASA's Aquarius instrument aboard the Aquarius/SAC-D observatory. The goal of both missions is accuracy on the order of 0.1 psu. This requires accurate knowledge of the dielectric constant of sea water as a function of salinity and temperature and also the effect of waves (roughness). The former determines the emissivity of an ideal (i.e. flat) surface and the later is the major source of error from predictions based on a flat surface. These two aspects of the problem of characterizing the emissivity are being addressed in the context of the Aquarius mission. First, laboratory measurements are being made of the dielectric constant of sea water. This is being done at the George Washington University using a resonant cavity. In this technique, sea water of known salinity and temperature is fed into the cavity along its axis through a narrow tube. The sea water changes the resonant frequency and Q of the cavity which, if the sample is small enough, can be related to the dielectric constant of the sample. An extensive set of measurements have been conducted at 1.413 GHz to develop a model for the real and imaginary part of the dielectric constant as a function of salinity and temperature. The results are compared to the predictions of models based on parameterization of the Debye resonance of the water molecule. The models and measurements are close; however, the differences are significant for remote sensing of salinity. This is especially true at low temperatures where the sensitivity to salinity is lowest.

A comprehensive estimate for loss of atmospheric carbon tetrachloride (CCl4) to the ocean

NASA Astrophysics Data System (ADS)

Butler, James H.; Yvon-Lewis, Shari A.; Lobert, Jurgen M.; King, Daniel B.; Montzka, Stephen A.; Bullister, John L.; Koropalov, Valentin; Elkins, James W.; Hall, Bradley D.; Hu, Lei; Liu, Yina

2016-09-01

Extensive undersaturations of carbon tetrachloride (CCl4) in Pacific, Atlantic, and Southern Ocean surface waters indicate that atmospheric CCl4 is consumed in large amounts by the ocean. Observations made on 16 research cruises between 1987 and 2010, ranging in latitude from 60° N to 77° S, show that negative saturations extend over most of the surface ocean. Corrected for physical effects associated with radiative heat flux, mixing, and air injection, these anomalies were commonly on the order of -5 to -10 %, with no clear relationship to temperature, productivity, or other gross surface water characteristics other than being more negative in association with upwelling. The atmospheric flux required to sustain these undersaturations is 12.4 (9.4-15.4) Gg yr-1, a loss rate implying a partial atmospheric lifetime with respect to the oceanic loss of 183 (147-241) yr and that ˜ 18 (14-22) % of atmospheric CCl4 is lost to the ocean. Although CCl4 hydrolyzes in seawater, published hydrolysis rates for this gas are too slow to support such large undersaturations, given our current understanding of air-sea gas exchange rates. The even larger undersaturations in intermediate depth waters associated with reduced oxygen levels, observed in this study and by other investigators, strongly suggest that CCl4 is ubiquitously consumed at mid-depth, presumably by microbiota. Although this subsurface sink creates a gradient that drives a downward flux of CCl4, the gradient alone is not sufficient to explain the observed surface undersaturations. Since known chemical losses are likewise insufficient to sustain the observed undersaturations, this suggests a possible biological sink for CCl4 in surface or near-surface waters of the ocean. The total atmospheric lifetime for CCl4, based on these results and the most recent studies of soil uptake and loss in the stratosphere is now 32 (26-43) yr.

Response of Tropical Forests to Intense Climate Variability and Rainfall Anomaly over the Last Decade

NASA Astrophysics Data System (ADS)

Saatchi, S.; Asefi, S.

2012-04-01

During the last decade, strong precipitation anomalies resulted from increased sea surface temperature in the tropical Atlantic, have caused extensive drying trends in rainforests of western Amazonia, exerting water stress, tree mortality, biomass loss, and large-scale fire disturbance. In contrast, there have been no reports on large-scale disturbance in rainforests of west and central Africa, though being exposed to similar intensity of climate variability. Using data from Tropical Rainfall Mapping Mission (TRMM) (1999-2010), and time series of rainfall observations from meteorological stations (1971-2000), we show that both Amazonian and African rainforest experienced strong precipitation anomalies from 2005-2010. We monitored the response of forest to the climate variability by analyzing the canopy water content observed by SeaWinds Ku-band Scatterometer (QSCAT) (1999-2009) and found that more than 70 million ha of forests in western Amazonia experienced a strong water deficit during the dry season of 2005 and a closely corresponding decline in canopy backscatter that persisted until the next major drought in 2010. This decline in backscatter has been attributed to loss of canopy water content and large-scale tree mortality corroborated by ground and airborne observations. However, no strong impacts was observed on tropical forests of Africa, suggesting that the African rainforest may have more resilience to droughts. We tested this hypothesis by examining the seasonal rainfall patterns, maximum water deficit, and the surface temperature variations. Results show that there is a complex pattern of low annual rainfall, moderate seasonality, and lower surface temperature in Central Africa compared to Amazonia, indicating potentially a lower evapotranspiration circumventing strong water deficits

Response of Tropical Forests to Intense Climate Variability and Rainfall Anomaly of Last Decade

NASA Astrophysics Data System (ADS)

Saatchi, S. S.; Asefi Najafabady, S.

2011-12-01

During the last decade, strong precipitation anomalies resulted from increased sea surface temperature in the tropical Atlantic, have caused extensive drying trends in rainforests of western Amazonia, exerting water stress, tree mortality, biomass loss, and large-scale fire disturbance. In contrast, there have been no reports on large-scale disturbance in rainforests of west and central Africa, though being exposed to similar intensity of climate variability. Using data from Tropical Rainfall Mapping Mission (TRMM) (1999-2010), and time series of rainfall observations from meteorological stations (1971-2000), we show that both Amazonian and African rainforest experienced strong precipitation anomalies from 2005-2010. We monitored the response of forest to the climate variability by analyzing the canopy water content observed by SeaWinds Ku-band Scatterometer (QSCAT) (1999-2009) and found that more than 70 million ha of forests in western Amazonia experienced a strong water deficit during the dry season of 2005 and a closely corresponding decline in canopy backscatter that persisted until the next major drought in 2010. This decline in backscatter has been attributed to loss of canopy water content and large-scale tree mortality corroborated by ground and airborne observations. However, no strong impacts was observed on tropical forests of Africa, suggesting that the African rainforest may have more resilience to droughts. We tested this hypothesis by examining the seasonal rainfall patterns, maximum water deficit, and the surface temperature variations. Results show that there is a complex pattern of low annual rainfall, moderate seasonality, and lower surface temperature in Central Africa compared to Amazonia, indicating potentially a lower evapotranspiration circumventing strong water deficits.

Understanding Public Engagement in Water Conservation Behaviors and Knowledge of Water Policy: Promising Hints for Extension

ERIC Educational Resources Information Center

Huang, Pei-wen; Lamm, Alexa J.

2015-01-01

Sustaining water resources is a primary issue facing Florida Extension. The study reported here identified how experience with water issues and familiarity with water policies affected individuals' engagement in water conservation behaviors. A public opinion survey was conducted online to capture Florida residents' responses. The findings…

South Atlantic circulation in a world ocean model

NASA Astrophysics Data System (ADS)

England, Matthew H.; Garçon, Véronique C.

1994-09-01

The circulation in the South Atlantic Ocean has been simulated within a global ocean general circulation model. Preliminary analysis of the modelled ocean circulation in the region indicates a rather close agreement of the simulated upper ocean flows with conventional notions of the large-scale geostrophic currents in the region. The modelled South Atlantic Ocean witnesses the return flow and export of North Atlantic Deep Water (NADW) at its northern boundary, the inflow of a rather barotropic Antarctic Circumpolar Current (ACC) through the Drake Passage, and the inflow of warm saline Agulhas water around the Cape of Good Hope. The Agulhas leakage amounts to 8.7 Sv, within recent estimates of the mass transport shed westward at the Agulhas retroflection. Topographic steering of the ACC dominates the structure of flow in the circumpolar ocean. The Benguela Current is seen to be fed by a mixture of saline Indian Ocean water (originating from the Agulhas Current) and fresher Subantarctic surface water (originating in the ACC). The Benguela Current is seen to modify its flow and fate with depth; near the surface it flows north-westwards bifurcating most of its transport northward into the North Atlantic Ocean (for ultimate replacement of North Atlantic surface waters lost to the NADW conveyor). Deeper in the water column, more of the Benguela Current is destined to return with the Brazil Current, though northward flows are still generated where the Benguela Current extension encounters the coast of South America. At intermediate levels, these northward currents trace the flow of Antarctic Intermediate Water (AAIW) equatorward, though even more AAIW is seen to recirculate poleward in the subtropical gyre. In spite of the model's rather coarse resolution, some subtle features of the Brazil-Malvinas Confluence are simulated rather well, including the latitude at which the two currents meet. Conceptual diagrams of the recirculation and interocean exchange of thermocline, intermediate and deep waters are constructed from an analysis of flows bound between isothermal and isobaric surfaces. This analysis shows how the return path of NADW is partitioned between a cold water route through the Drake Passage (6.5 Sv), a warm water route involving the Agulhas Current sheeding thermocline water westward (2.5 Sv), and a recirculation of intermediate water originating in the Indian Ocean (1.6 Sv).

Green roof stormwater retention: effects of roof surface, slope, and media depth.

PubMed

VanWoert, Nicholaus D; Rowe, D Bradley; Andresen, Jeffrey A; Rugh, Clayton L; Fernandez, R Thomas; Xiao, Lan

2005-01-01

Urban areas generate considerably more stormwater runoff than natural areas of the same size due to a greater percentage of impervious surfaces that impede water infiltration. Roof surfaces account for a large portion of this impervious cover. Establishing vegetation on rooftops, known as green roofs, is one method of recovering lost green space that can aid in mitigating stormwater runoff. Two studies were performed using several roof platforms to quantify the effects of various treatments on stormwater retention. The first study used three different roof surface treatments to quantify differences in stormwater retention of a standard commercial roof with gravel ballast, an extensive green roof system without vegetation, and a typical extensive green roof with vegetation. Overall, mean percent rainfall retention ranged from 48.7% (gravel) to 82.8% (vegetated). The second study tested the influence of roof slope (2 and 6.5%) and green roof media depth (2.5, 4.0, and 6.0 cm) on stormwater retention. For all combined rain events, platforms at 2% slope with a 4-cm media depth had the greatest mean retention, 87%, although the difference from the other treatments was minimal. The combination of reduced slope and deeper media clearly reduced the total quantity of runoff. For both studies, vegetated green roof systems not only reduced the amount of stormwater runoff, they also extended its duration over a period of time beyond the actual rain event.

Measuring and Modeling the Effect of Surface Moisture on the Spectral Reflectance of Coastal Beach Sand

PubMed Central

Nolet, Corjan; Poortinga, Ate; Roosjen, Peter; Bartholomeus, Harm; Ruessink, Gerben

2014-01-01

Surface moisture is an important supply limiting factor for aeolian sand transport, which is the primary driver of coastal dune development. As such, it is critical to account for the control of surface moisture on available sand for dune building. Optical remote sensing has the potential to measure surface moisture at a high spatio-temporal resolution. It is based on the principle that wet sand appears darker than dry sand: it is less reflective. The goals of this study are (1) to measure and model reflectance under controlled laboratory conditions as function of wavelength () and surface moisture () over the optical domain of 350–2500 nm, and (2) to explore the implications of our laboratory findings for accurately mapping the distribution of surface moisture under natural conditions. A laboratory spectroscopy experiment was conducted to measure spectral reflectance (1 nm interval) under different surface moisture conditions using beach sand. A non-linear increase of reflectance upon drying was observed over the full range of wavelengths. Two models were developed and tested. The first model is grounded in optics and describes the proportional contribution of scattering and absorption of light by pore water in an unsaturated sand matrix. The second model is grounded in soil physics and links the hydraulic behaviour of pore water in an unsaturated sand matrix to its optical properties. The optical model performed well for volumetric moisture content 24% ( 0.97), but underestimated reflectance for between 24–30% ( 0.92), most notable around the 1940 nm water absorption peak. The soil-physical model performed very well ( 0.99) but is limited to 4% 24%. Results from a field experiment show that a short-wave infrared terrestrial laser scanner ( = 1550 nm) can accurately relate surface moisture to reflectance (standard error 2.6%), demonstrating its potential to derive spatially extensive surface moisture maps of a natural coastal beach. PMID:25383709

Milling induced amorphisation and recrystallization of α-lactose monohydrate.

PubMed

Badal Tejedor, Maria; Pazesh, Samaneh; Nordgren, Niklas; Schuleit, Michael; Rutland, Mark W; Alderborn, Göran; Millqvist-Fureby, Anna

2018-02-15

Preprocessing of pharmaceutical powders is a common procedure to condition the materials for a better manufacturing performance. However, such operations may induce undesired material properties modifications when conditioning particle size through milling, for example. Modification of both surface and bulk material structure will change the material properties, thus affecting the processability of the powder. Hence it is essential to control the material transformations that occur during milling. Topographical and mechanical changes in surface properties can be a preliminary indication of further material transformations. Therefore a surface evaluation of the α-lactose monohydrate after short and prolonged milling times has been performed. Unprocessed α-lactose monohydrate and spray dried lactose were evaluated in parallel to the milled samples as reference examples of the crystalline and amorphous lactose structure. Morphological differences between unprocessed α-lactose, 1 h and 20 h milled lactose and spray dried lactose were detected from SEM and AFM images. Additionally, AFM was used to simultaneously characterize particle surface amorphicity by measuring energy dissipation. Extensive surface amorphicity was detected after 1 h of milling while prolonged milling times showed only a moderate particle surface amorphisation. Bulk material characterization performed with DSC indicated a partial amorphicity for the 1 h milled lactose and a fully amorphous thermal profile for the 20 h milled lactose. The temperature profiles however, were shifted somewhat in the comparison to the amorphous reference, particularly after extended milling, suggesting a different amorphous state compared to the spray-dried material. Water loss during milling was measured with TGA, showing lower water content for the lactose amorphized through milling compared to spray dried amorphous lactose. The combined results suggest a surface-bulk propagation of the amorphicity during milling in combination with a different amorphous structural conformation to that of the amorphous spray dried lactose. The hardened surface may be due to either surface crystallization of lactose or to formation of a low-water glass transition. Copyright © 2017 Elsevier B.V. All rights reserved.

Rethinking hyporheic flow and transient storage to advance understanding of stream-catchment connections

USGS Publications Warehouse

Bencala, K.E.; Gooseff, M.N.; Kimball, B.A.

2011-01-01

Although surface water and groundwater are increasingly referred to as one resource, there remain environmental and ecosystem needs to study the 10 m to 1 km reach scale as one hydrologic system. Streams gain and lose water over a range of spatial and temporal scales. Large spatial scales (kilometers) have traditionally been recognized and studied as river-aquifer connections. Over the last 25 years hyporheic exchange flows (1-10 m) have been studied extensively. Often a transient storage model has been used to quantify the physical solute transport setting in which biogeochemical processes occur. At the longer 10 m to 1 km scale of stream reaches it is now clear that streams which gain water overall can coincidentally lose water to the subsurface. At this scale, the amounts of water transferred are not necessarily significant but the exchanges can, however, influence solute transport. The interpretation of seemingly straightforward questions about water, contaminant, and nutrient fluxes into and along a stream can be confounded by flow losses which are too small to be apparent in stream gauging and along flow paths too long to be detected in tracer experiments. We suggest basic hydrologic approaches, e.g., measurement of flow along the channel, surface and subsurface solute sampling, and routine measurements of the water table that, in our opinion, can be used to extend simple exchange concepts from the hyporheic exchange scale to a scale of stream-catchment connection. Copyright 2011 by the American Geophysical Union.

Pathways to dewetting in hydrophobic confinement

PubMed Central

Remsing, Richard C.; Xi, Erte; Vembanur, Srivathsan; Sharma, Sumit; Debenedetti, Pablo G.; Garde, Shekhar; Patel, Amish J.

2015-01-01

Liquid water can become metastable with respect to its vapor in hydrophobic confinement. The resulting dewetting transitions are often impeded by large kinetic barriers. According to macroscopic theory, such barriers arise from the free energy required to nucleate a critical vapor tube that spans the region between two hydrophobic surfaces—tubes with smaller radii collapse, whereas larger ones grow to dry the entire confined region. Using extensive molecular simulations of water between two nanoscopic hydrophobic surfaces, in conjunction with advanced sampling techniques, here we show that for intersurface separations that thermodynamically favor dewetting, the barrier to dewetting does not correspond to the formation of a (classical) critical vapor tube. Instead, it corresponds to an abrupt transition from an isolated cavity adjacent to one of the confining surfaces to a gap-spanning vapor tube that is already larger than the critical vapor tube anticipated by macroscopic theory. Correspondingly, the barrier to dewetting is also smaller than the classical expectation. We show that the peculiar nature of water density fluctuations adjacent to extended hydrophobic surfaces—namely, the enhanced likelihood of observing low-density fluctuations relative to Gaussian statistics—facilitates this nonclassical behavior. By stabilizing isolated cavities relative to vapor tubes, enhanced water density fluctuations thus stabilize novel pathways, which circumvent the classical barriers and offer diminished resistance to dewetting. Our results thus suggest a key role for fluctuations in speeding up the kinetics of numerous phenomena ranging from Cassie–Wenzel transitions on superhydrophobic surfaces, to hydrophobically driven biomolecular folding and assembly. PMID:26100866

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Zongyuan; Duchon, Tomas; Wang, Huanru

Ambient-Pressure X-ray Photoelectron Spectroscopy (AP-XPS) and Infrared Reflection Absorption Spectroscopy (AP-IRRAS) have been used to elucidate the active sites and mechanistic steps associated with the ethanol steam reforming reaction (ESR) over Ni–CeO 2(111) model catalysts. Our results reveal that surface layers of the ceria substrate are both highly reduced and hydroxylated under reaction conditions while the small supported Ni nanoparticles are present as Ni 0/NixC. A multifunctional, synergistic role is highlighted in which Ni, CeO x and the interface provide an ensemble effect in the active chemistry that leads to H 2. Ni 0 is the active phase leading tomore » both C–C and C–H bond cleavage in ethanol and it is also responsible for carbon accumulation. On the other hand, CeO x is important for the deprotonation of ethanol/water to ethoxy and OH intermediates. The active state of CeO x is a Ce 3+(OH) x compound that results from extensive reduction by ethanol and the efficient dissociation of water. Additionally, we gain an important insight into the stability and selectivity of the catalyst by its effective water dissociation, where the accumulation of surface carbon can be mitigated by the increased presence of surface OH groups. As a result, the co-existence and cooperative interplay of Ni 0 and Ce 3+(OH) x through a metal–support interaction facilitate oxygen transfer, activation of ethanol/water as well as the removal of coke.« less

The Uranian satellites and Hyperion - New spectrophotometry and compositional implications

NASA Astrophysics Data System (ADS)

Brown, R. H.

1983-12-01

New reflectance spectra at 3.5 percent resolution have been obtained for Ariel, Titania, Oberon, and Hyperion in the 0.8 to 1.6-micron spectrum region. The new spectra show no absorptions other than the 1.5 micron water-ice feature (within the precision of the data), and demonstrate extension into the 0.8- to 1.6 micron region of the 1.5- to 2.5 micron spectral similarity ofo Ariel to Hyperion (Brown and Cruikshank, 1983). The new data confirm the presence of a dark, spectrally bland component on/in the water-ice surfaces of the Uranian satellites, which, with some reservations, has spectral similarities to the dark substance on the leading side of lapetus and the dark material on/in the surface of Hyperion, as well as other dark, spectrally neutral substances such as charcoal. Attempts were made to match the spectra of Ariel, Titania, and Oberon with additive reflectance mixes (aeral coverage) of fine-grained water frost and various dark components such as charcoal, lampblack, and charcoal-water-ice mixtures. The results were broad limits on the amounts of possible areal coverage of a charcoal-like spectral component on the surfaces of the Uranian satellites, but the data are not of sufficient precision to conclusively determine whether the dominant mode of contaminant dispersal is areal or voluminal. The effect of highly variegated albedos on the diameters derived by Brown, Cruikshank, and Morrison (1982) is found to be small.

The Uranian satellites and Hyperion - New spectrophotometry and compositional implications

NASA Technical Reports Server (NTRS)

Brown, R. H.

1983-01-01

New reflectance spectra at 3.5 percent resolution have been obtained for Ariel, Titania, Oberon, and Hyperion in the 0.8 to 1.6-micron spectrum region. The new spectra show no absorptions other than the 1.5 micron water-ice feature (within the precision of the data), and demonstrate extension into the 0.8- to 1.6 micron region of the 1.5- to 2.5 micron spectral similarity ofo Ariel to Hyperion (Brown and Cruikshank, 1983). The new data confirm the presence of a dark, spectrally bland component on/in the water-ice surfaces of the Uranian satellites, which, with some reservations, has spectral similarities to the dark substance on the leading side of lapetus and the dark material on/in the surface of Hyperion, as well as other dark, spectrally neutral substances such as charcoal. Attempts were made to match the spectra of Ariel, Titania, and Oberon with additive reflectance mixes (aeral coverage) of fine-grained water frost and various dark components such as charcoal, lampblack, and charcoal-water-ice mixtures. The results were broad limits on the amounts of possible areal coverage of a charcoal-like spectral component on the surfaces of the Uranian satellites, but the data are not of sufficient precision to conclusively determine whether the dominant mode of contaminant dispersal is areal or voluminal. The effect of highly variegated albedos on the diameters derived by Brown, Cruikshank, and Morrison (1982) is found to be small.

Amine Enrichment of Thin-Film Composite Membranes via Low Pressure Plasma Polymerization for Antimicrobial Adhesion.

PubMed

Reis, Rackel; Dumée, Ludovic F; He, Li; She, Fenghua; Orbell, John D; Winther-Jensen, Bjorn; Duke, Mikel C

2015-07-15

Thin-film composite membranes, primarily based on poly(amide) (PA) semipermeable materials, are nowadays the dominant technology used in pressure driven water desalination systems. Despite offering superior water permeation and salt selectivity, their surface properties, such as their charge and roughness, cannot be extensively tuned due to the intrinsic fabrication process of the membranes by interfacial polymerization. The alteration of these properties would lead to a better control of the materials surface zeta potential, which is critical to finely tune selectivity and enhance the membrane materials stability when exposed to complex industrial waste streams. Low pressure plasma was employed to introduce amine functionalities onto the PA surface of commercially available thin-film composite (TFC) membranes. Morphological changes after plasma polymerization were analyzed by SEM and AFM, and average surface roughness decreased by 29%. Amine enrichment provided isoelectric point changes from pH 3.7 to 5.2 for 5 to 15 min of plasma polymerization time. Synchrotron FTIR mappings of the amine-modified surface indicated the addition of a discrete 60 nm film to the PA layer. Furthermore, metal affinity was confirmed by the enhanced binding of silver to the modified surface, supported by an increased antimicrobial functionality with demonstrable elimination of E. coli growth. Essential salt rejection was shown minimally compromised for faster polymerization processes. Plasma polymerization is therefore a viable route to producing functional amine enriched thin-film composite PA membrane surfaces.

A global assessment of wildfire risks to human and environmental water security

NASA Astrophysics Data System (ADS)

Robinne, François-Nicolas; Parisien, Marc-André; Flannigan, Mike; Miller, Carol; Bladon, Kevin D.

2017-04-01

Extreme wildfire events extensively affect hydrosystem stability and generate an important threat to the reliability of the water supply for human and natural communities. While actively studied at the watershed scale, the development of a global vision of wildfire risk to water security has only been undertaken recently, pointing at potential water security concerns in an era of global changes. In order to address this concern, we propose a global-scale analysis of the wildfire risk to surface water supplies based on the Driving forces-Pressures-States-Impacts-Responses (DPSIR) framework. This framework relies on the cause-and-effect relationships existing between the five categories of the DPSIR chain. Based on the literature, we gathered an extensive set of spatial indicators relevant to fire-induced hydrological hazards and water consumption patterns by human and natural communities. Each indicator was assigned a DPSIR category. Then, we collapsed the information in each category using a principal component analysis in order to extract the most relevant pixel-based information provided by each spatial indicator. Finally, we compiled our five categories using an additive indexation process to produce a spatially-explicit index of the wildfire-water risk (WWR). For comparison purposes, we aggregated index scores by global hydrological regions, or hydrobelts, for analysis. Overall, our results show a distinct pattern of medium-to-high risk levels in areas where sizeable wildfire activity, water resources, and water consumption are concomitant, which mainly encompasses temperate and sub-tropical zones. A closer look at hydrobelts reveals differences in the factors driving the risk, with fire activity being the primary factor of risk in the circumboreal forest, and freshwater resource density being prevalent in tropical areas. We also identified major urban areas across the world whose source waters should be protected from extreme fire events, particularly when they are dependent on mountainous headwaters. This study offers new insights towards a better understanding of global water security issues that can inform and help guide international water governance.

Implementations of Riga city water supply system founded on groundwater sources

NASA Astrophysics Data System (ADS)

Lāce, I.; Krauklis, K.; Spalviņš, A.; Laicāns, J.

2017-10-01

Drinking water for Riga city is provided by the groundwater well field complex “Baltezers, Zakumuiza, Rembergi” and by the Daugava river as a surface water source. Presently (2016), the both sources jointly supply 122 thous.metre3day-1 of drinking water. It seems reasonable to use in future only groundwater, because river water is of low quality and its treatment is expensive. The research on this possibility was done by scientists of Riga Technical university as the task drawn up by the company “Aqua-Brambis”. It was required to evaluate several scenario of the groundwater supply for Riga city. By means of hydrogeological modelling, it was found out that groundwater well fields could provide 120-122 thous.metre3day-1 of drinking water for the Riga city and it is possible further not to use water of the Daugava river. However, in order to provide more extensive use of groundwater sources, existing water distribution network shall be adapted to the change of the water sources and supply directions within the network. Safety of water supply shall be ensured. The publication may be of interest for specialists dealing with problems of water supply for large towns.

Decadal and seasonal changes in temperature, salinity, nitrate, and chlorophyll in inshore and offshore waters along southeast Australia

NASA Astrophysics Data System (ADS)

Kelly, Paige; Clementson, Lesley; Lyne, Vincent

2015-06-01

Sixty years of oceanographic in situ data at Port Hacking (34°S) and Maria Island (42°S) and 15 years of satellite-derived chlorophyll a (chl a) in inshore and offshore waters of southeast Australia show changes in the seasonality and trend of water properties consistent with long-term intensification and southerly extensions of East Australian Current (EAC) water. Decadal analyses reveal that the EAC extension water at Maria Island increased gradually from the 1940s to 1980s, followed by a rapid increase since the 1990s. This acceleration coincided with enhanced winter nitrate, implying increased injections of subantarctic water at Maria Island. Satellite-derived chl a at six coastal sites and offshore companion sites in the western Tasman Sea showed significant inshore-offshore variations in seasonal cycle and long-term trend. After 2004-2005, the Maria Island seasonal cycle became increasingly similar to those of Bass Strait and St. Helens, suggesting that the EAC extension water was extending further southward. Comparative analyses of inshore-offshore sites showed that the presence of EAC extension water declined offshore. Seasonal cycles at Maria Island show a recent shift away from the traditional spring bloom, toward increased winter biomass, and enhanced primary productivity consistent with extensions of warm, energetic EAC extension water and more frequent injections of cooler, fresher nitrate-replete waters. Overall, we find complex temporal, latitudinal, and inshore-offshore changes in multiple water masses, particularly at Maria Island, and changes in primary productivity that will profoundly impact fisheries and ecosystems.

Seasonal uranium distributions in the coastal waters off the Amazon and Mississippi Rivers

USGS Publications Warehouse

Swarzenski, P.W.; McKee, B.A.

1998-01-01

The chemical reactivity of uranium was investigated across estuarine gradients from two of the world's largest river systems: the Amazon and Mississippi. Concentrations of dissolved (<0.45 ??m) uranium (U) were measured in surface waters of the Amazon shelf during rising (March 1990), flood (June 1990) and low (November 1991) discharge regimes. The dissolved U content was also examined in surface waters collected across estuarine gradients of the Mississippi outflow region during April 1992, August 1993, and November (1993). All water samples were analyzed for U by isotope dilution inductively coupled plasma mass spectrometry (ICP-MS). In Amazon shelf surface waters uranium increased nonconservatively from about 0.01 ??g l-1 at the river's mouth to over 3 ??g l-1 at the distal site, irrespective of river discharge stage. Observed large-scale U removal at salinities generally less than 15 implies a) that riverine dissolved U was extensively adsorbed by freshly-precipitated hydrous metal oxides (e.g., FeOOH, MnO2) as a result of flocculation and aggregation, and b) that energetic resuspension and reworking of shelf sediments and fluid muds on the Amazon shelf released a chemically reactive particle/colloid to the water column which can further scavenge dissolved U across much of the estuarine gradient. In contrast, the estuarine chemistry of U is inconclusive within surface waters of the Mississippi shelf-break region. U behavior is most likely controlled less by traditional sorption and/or desorption reactions involving metal oxides or colloids than by the river's variable discharge regime (e.g., water parcel residence time during estuarine mixing, nature of particulates, sediment storage and resuspension in the confined lower river), and plume dispersal. Mixing of the thin freshwater lens into ambient seawater is largely defined by wind-driven rather than physical processes. As a consequence, in the Mississippi outflow region uranium predominantly displays ConserVative behavior; removal is evident only during anomalous river discharge regimes. 'Products-approach' mixing experiments conducted during the Flood of 1993 suggest the importance of small particles and/or colloids in defining a depleted U versus salinity distribution.

How many molecular layers of polar solvent molecules control chemistry? The concept of compensating dipoles.

PubMed

Langhals, Heinz; Braun, Patricia; Dietl, Christian; Mayer, Peter

2013-09-27

The extension of the solvent influence of the shell into the volume of a polar medium was examined by means of anti-collinear dipoles on the basis of the E(T)(30) solvent polarity scale (i.e., the molar energy of excitation of a pyridinium-N-phenolatebetaine dye; generally: E(T) =28,591 nm kcal mol(-1)/λmax) where no compensation effects were found. As a consequence, solvent polarity effects are concentrated to a very thin layer of a few thousand picometres around the solute where extensions into the bulk solvent become unimportant. A parallelism to the thin surface layer of water to the gas phase is discussed. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Impact of Sea Ice Loss on Wave Dynamics and Coastal Erosion Along the Arctic Coast

NASA Astrophysics Data System (ADS)

Overeem, I.; Anderson, R. S.; Wobus, C. W.; Matell, N.; Urban, F. E.; Clow, G. D.; Stanton, T. P.

2010-12-01

The extent of Arctic sea ice has been shrinking rapidly over the past few decades, and attendant acceleration of erosion is now occurring along the Arctic coast. This both brings coastal infrastructure into harm’s way and promotes a complex response of the adjacent landscape to global change. We quantify the effects of declining sea ice extent on coastal erosion rates along a 75-km stretch of coastal permafrost bluffs adjacent to the Beaufort Sea, Alaska, where present-day erosion rates are among the highest in the world at ~14 m yr-1. Our own observations reinforce those of others, and suggest that the rate-limiting process is thermal erosion at the base of the several-meter tall bluffs. Here we focus on the interaction between the nearshore sea ice concentration, the location of the sea ice margin, and the fetch-limited, shallow water wave field, since these parameters ultimately control both sea surface temperatures and the height to which these waters can bathe the frozen bluffs. Thirty years of daily or bi-daily passive microwave data from Nimbus-7 SMMR and DMSP SSM/I satellites reveal that the nearshore open water season lengthened ~54 days over 1979-2009. The open water season, centered in August, expands more rapidly into the fall (September and October~0.92 day yr-1) than into the early summer (July~0.71 days yr-1). Average fetch, defined for our purposes as the distance from the sea ice margin to the coast over which the wind is blowing, increased by a factor 1.7 over the same time-span. Given these time series, we modeled daily nearshore wave heights during the open water season for each year, which we integrated to provide a quantitative metric for the annual exposure of the coastal bluffs to thermal erosion. This “annual wave exposure” increased by 250% during 1979-2009. In the same interval, coastal erosion rates reconstructed from satellite and aerial photo records show less acceleration. We attribute this to a disproportionate extension of the open-water season toward the fall than toward the early summer. This asymmetry fails to tap into the high insolation portion of the summer; expansion into the fall exerts less leverage on coastal change, as sea surface temperatures have significantly declined by late fall. Should the extension of ice-free conditions more strongly advance into the middle of summer, when insolation peaks, we suspect that sea surface temperatures will warm even faster and hence erosion may accelerate yet more strongly.

Satellite detection of oil on the marine surface

NASA Technical Reports Server (NTRS)

Wilson, M. J.; Oneill, P. E.; Estes, J. E.

1981-01-01

The ability of two widely dissimilar spaceborne imaging sensors to detect surface oil accumulations in the marine environment has been evaluated using broadly different techniques. Digital Landsat multispectral scanner (MSS) data consisting of two visible and two near infrared channels has been processed to enhance contrast between areas of known oil coverage and background clean surface water. These enhanced images have then been compared to surface verification data gathered by aerial reconnaissance during the October 15, 1975, Landsat overpass. A similar evaluation of oil slick imaging potential has been made for digitally enhanced Seasat-A synthetic aperture radar (SAR) data from July 18, 1979. Due to the premature failure of this satellite, however, no concurrent surface verification data were collected. As a substitute, oil slick configuration information has been generated for the comparison using meteorological and oceanographic data. The test site utilized in both studies was the extensive area of natural seepage located off Coal Oil Point, adjacent to the University of California, Santa Barbara.

Assessing background ground water chemistry beneath a new unsewered subdivision

USGS Publications Warehouse

Wilcox, J.D.; Bradbury, K.R.; Thomas, C.L.; Bahr, J.M.

2005-01-01

Previous site-specific studies designed to assess the impacts of unsewered subdivisions on ground water quality have relied on upgradient monitoring wells or very limited background data to characterize conditions prior to development. In this study, an extensive monitoring program was designed to document ground water conditions prior to construction of a rural subdivision in south-central Wisconsin. Previous agricultural land use has impacted ground water quality; concentrations of chloride, nitrate-nitrogen, and atrazine ranged from below the level of detection to 296 mg/L, 36 mg/L, and 0.8 ??g/L, respectively, and were highly variable from well to well and through time. Seasonal variations in recharge, surface topography, aquifer heterogeneities, surficial loading patterns, and well casing depth explain observed variations in ground water chemistry. This variability would not have been detected if background conditions were determined from only a few monitoring wells or inferred from wells located upgradient of the subdivision site. This project demonstrates the importance of characterizing both ground water quality and chemical variability prior to land-use change to detect any changes once homes are constructed. Copyright ?? 2005 National Ground Water Association.

Large-Scale and Global Hydrology. Chapter 92

NASA Technical Reports Server (NTRS)

Rodell, Matthew; Beaudoing, Hiroko Kato; Koster, Randal; Peters-Lidard, Christa D.; Famiglietti, James S.; Lakshmi, Venkat

2016-01-01

Powered by the sun, water moves continuously between and through Earths oceanic, atmospheric, and terrestrial reservoirs. It enables life, shapes Earths surface, and responds to and influences climate change. Scientists measure various features of the water cycle using a combination of ground, airborne, and space-based observations, and seek to characterize it at multiple scales with the aid of numerical models. Over time our understanding of the water cycle and ability to quantify it have improved, owing to advances in observational capabilities, the extension of the data record, and increases in computing power and storage. Here we present some of the most recent estimates of global and continental ocean basin scale water cycle stocks and fluxes and provide examples of modern numerical modeling systems and reanalyses.Further, we discuss prospects for predicting water cycle variability at seasonal and longer scales, which is complicated by a changing climate and direct human impacts related to water management and agriculture. Changes to the water cycle will be among the most obvious and important facets of climate change, thus it is crucial that we continue to invest in our ability to monitor it.

The initial stages of NaCl dissolution: Ion or ion pair solvation?

NASA Astrophysics Data System (ADS)

Klimes, Jiri; Michaelides, Angelos

2009-03-01

The interaction of water with rock salt (NaCl) is important in a wide variety of natural processes and human activities. A lot is known about NaCl dissolution at the macroscopic level but we do not yet have a detailed atomic scale picture of how salt crystals dissolve. Here we report an extensive series of density functional theory, forcefield and molecular dynamics studies of water clusters at flat and defective NaCl surfaces and NaCl clusters. The focus is on answering seemingly elementary questions such as how many water molecules are needed before it becomes favorable to extract an ion or a pair of ions from the crystal or the cluster. It turns out, however, that the answers to these questions are not so straightforward: below a certain number of water molecules (˜ 12) solvation of individual ions is less costly and above this number solvation of ion pairs is favored. These results reveal a hitherto unknown complexity in the NaCl dissolution process born out of a subtle interplay between water-water and water-ion interactions.

Hydrogeology and water quality of the shallow aquifer system at the Mainside, Naval Surface Warfare Center, Dahlgren Site, Dahlgren, Virginia

USGS Publications Warehouse

Harlow, G.E.; Bell, C.F.

1996-01-01

Lithologic and geophysical logs of boreholes at 29 sites show that the hydrogeologic framework of the Mainside of the Naval Surface Warfare Center, Dahlgren Site at Dahlgren, Virginia, consists of un-consolidated sedimentary deposits of gravel, sand, silt, and clay. The upper 220 feet of these sediments are divided into five hydrogeologic units, including the (1) Columbia (water-table) aquifer, (2) upper confining unit, (3) upper confined aquifer, (4) Nanjemoy-Marlboro confining unit, and (5) Aquia aquifer. The Columbia aquifer in the study area is a local system that is not affected by regional pumping. Ground-water recharge occurs at topographic highs in the northern part of the Mainside, and ground-water discharge occurs at topographic lows associated with adjacent surface-water bodies. Regionally, the direction of ground-water flow in the upper confined and Aquia aquifers is toward the southwest and southeast, respectively. A downward hydraulic gradient exists between the aquifers in the shallow system, and stresses on the Aquia aquifer are indicated by heads that range between 2 and 12 feet below sea level. The ratio of median horizontal hydraulic conductivity of the Columbia aquifer to median vertical hydraulic con-ductivity of the upper confining unit, however, is approximately 2,600:1; therefore, under natural- flow conditions, most water in the Columbia aquifer probably discharges to adjacent surface- water bodies. The composition and distribution of major ions vary in the Columbia aquifer. In general, water samples from wells located along the inland perimeter roads of the study area have chloride or a combination of chloride and sulfate as the dominant anions, and water samples from wells located in the interior of the study area have bicarbonate or a combination of bicarbonate and sulfate as the dominant anions. Sodium and calcium were the dominant cations in most samples. Dissolved solids and four inorganic constituents are present in water from the Columbia aquifer at concentrations that exceed the secondary maximum contaminant levels (SMCL's) for drinking water established by the U.S. Environmental Protection Agency. Concentration of dissolved solids exceed the SMCL of 500 milligrams per liter in 3 of 29 samples from the Columbia aquifer. An elevated concentration of sodium is present in one water sample, and elevated concentrations of chloride are present in two water samples. Concentrations of dissolved iron and manga-nese exceed the SMCL in 10 and 17 of 29 water samples, respectively, and are the most extensive water-quality problem with regard to inorganic constituents in the Columbia aquifer.

Dynamic Ice-Water Interactions Form Europa's Chaos Terrains

NASA Astrophysics Data System (ADS)

Blankenship, D. D.; Schmidt, B. E.; Patterson, G. W.; Schenk, P.

2011-12-01

Unique to the surface of Europa, chaos terrain is diagnostic of the properties and dynamics of its icy shell. We present a new model that suggests large melt lenses form within the shell and that water-ice interactions above and within these lenses drive the production of chaos. This model is consistent with key observations of chaos, predicts observables for future missions, and indicates that the surface is likely still active today[1]. We apply lessons from ice-water interaction in the terrestrial cryosphere to hypothesize a dynamic lense-collapse model to for Europa's chaos terrain. Chaos terrain morphology, like that of Conamara chaos and Thera Macula, suggests a four-phase formation [1]: 1) Surface deflection occurs as ice melts over ascending thermal plumes, as regularly occurs on Earth as subglacial volcanoes activate. The same process can occur at Europa if thermal plumes cause pressure melt as they cross ice-impurity eutectics. 2) Resulting hydraulic gradients and driving forces produce a sealed, pressurized melt lense, akin to the hydraulic sealing of subglacial caldera lakes. On Europa, the water cannot escape the lense due to the horizontally continuous ice shell. 3) Extension of the brittle ice lid above the lense opens cracks, allowing for the ice to be hydrofractured by pressurized water. Fracture, brine injection and percolation within the ice and possible iceberg toppling produces ice-melange-like granular matrix material. 4) Refreezing of the melt lense and brine-filled pores and cracks within the matrix results in raised chaos. Brine soaking and injection concentrates the ice in brines and adds water volume to the shell. As this englacial water freezes, the now water-filled ice will expand, not unlike the process of forming pingos and other "expansion ice" phenomena on Earth. The refreezing can raise the surface and create the oft-observed matrix "domes" In this presentation, we describe how catastrophic ice-water interactions on Earth have informed us about how such dynamics occur on Europa. We will discuss the observations of iceberg and matrix properties that imply shallow liquid water bodies on Europa, argue for the importance of granular mechanics in the interpretation of Europa's geology and present constraints on the properties of its ice shell. [1] Schmidt, B. E., Blankenship, D. D., Patterson, W., Schenk, P: Active chaos formation over shallow subsurface water on Europa, in review, 2011.

2007-2008 Annual Progress Report for BPA Grant Exp Restore Walla Walla River Flow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bower, Bob

WWBWC and its partners have been working on a wide variety of conservation and aquifer recharge related activities including: monitoring groundwater and surface water conditions, creating a geospatial database for the Walla Walla River valley (project focal area), expanding aquifer recharge testing at the HBDIC site and conducting an extensive outreach/education program by which to share the information, ideas and potential solutions to our current water management issues in this basin. This report is an outline of those activities and is accompanied by individual program-component (attached as appendices) reports for the areas that BPA is assisting to fund these on-the-groundmore » projects along with the innovative research and monitoring being done to further aquifer recharge as a water management tool for the Pacific Northwest.« less

An empirically derived basis for calculating the area, rate, and distribution of water-drop impingement on airfoils

NASA Technical Reports Server (NTRS)

Bergrun, Norman R

1952-01-01

An empirically derived basis for predicting the area, rate, and distribution of water-drop impingement on airfoils of arbitrary section is presented. The concepts involved represent an initial step toward the development of a calculation technique which is generally applicable to the design of thermal ice-prevention equipment for airplane wing and tail surfaces. It is shown that sufficiently accurate estimates, for the purpose of heated-wing design, can be obtained by a few numerical computations once the velocity distribution over the airfoil has been determined. The calculation technique presented is based on results of extensive water-drop trajectory computations for five airfoil cases which consisted of 15-percent-thick airfoils encompassing a moderate lift-coefficient range. The differential equations pertaining to the paths of the drops were solved by a differential analyzer.

Distinct characteristics of the intermediate water observed off the east coast of Korea during two contrasting years

NASA Astrophysics Data System (ADS)

Nam, S.; Yoon, S.; Park, J. H.; Kim, Y. H.; Chang, K. I.

2016-02-01

The intermediate water known as `East Sea Intermediate Water' and its coastal mode `North Korea Cold Water' found south of the Subpolar Front (SF) is formed in the northern East (Japan) Sea, and its physical properties are known to be determined by wintertime air-sea interaction north of the SF. Hydrographic data collected off the coast bi-monthly from 1994 to 2011 show significant decadal oscillations in spiciness following isopycnals of intermediate water (27.1-27.2 sigma-theta typically corresponding to 150 m depth), which are explained by the Arctic Oscillation (AO) and consequent cold-air outbreaks. During positive AO phases over the decades, the cold-air outbreak and water formation are more active and the intermediate water having the same spiciness reaches higher density (higher spiciness following the same isopycnals). At interannual timescale, however, the spiciness variability is well beyond the relationship with the AO. Especially, significantly lower spiciness (or both less saline and lower temperature) intermediate water was observed in spring of 2010 than 2001 under the similar AO condition (negative peaks). Strong cooling with common negative peaks in surface net-heat flux (with different patterns) and common negative peaks in the AO index are prominent in winter of the two years over past two decades. Such contrasting characteristics of intermediate water between 2001 and 2010 are consistent with the HYCOM reanalysis results which, along with the satellite altimetry-derived sea surface height maps, indicates widespread extension of low (high) spiciness intermediate water in the southwestern East Sea in 2010 (2001). A clear contrast in circulation pattern, along with net-heat flux pattern, is suggested to derive the observational results in the distinctly different characteristics of the intermediate water.

Satellite-based estimates of groundwater depletion in India.

PubMed

Rodell, Matthew; Velicogna, Isabella; Famiglietti, James S

2009-08-20

Groundwater is a primary source of fresh water in many parts of the world. Some regions are becoming overly dependent on it, consuming groundwater faster than it is naturally replenished and causing water tables to decline unremittingly. Indirect evidence suggests that this is the case in northwest India, but there has been no regional assessment of the rate of groundwater depletion. Here we use terrestrial water storage-change observations from the NASA Gravity Recovery and Climate Experiment satellites and simulated soil-water variations from a data-integrating hydrological modelling system to show that groundwater is being depleted at a mean rate of 4.0 +/- 1.0 cm yr(-1) equivalent height of water (17.7 +/- 4.5 km(3) yr(-1)) over the Indian states of Rajasthan, Punjab and Haryana (including Delhi). During our study period of August 2002 to October 2008, groundwater depletion was equivalent to a net loss of 109 km(3) of water, which is double the capacity of India's largest surface-water reservoir. Annual rainfall was close to normal throughout the period and we demonstrate that the other terrestrial water storage components (soil moisture, surface waters, snow, glaciers and biomass) did not contribute significantly to the observed decline in total water levels. Although our observational record is brief, the available evidence suggests that unsustainable consumption of groundwater for irrigation and other anthropogenic uses is likely to be the cause. If measures are not taken soon to ensure sustainable groundwater usage, the consequences for the 114,000,000 residents of the region may include a reduction of agricultural output and shortages of potable water, leading to extensive socioeconomic stresses.

Durable and mass producible polymer surface structures with different combinations of micro-micro hierarchy

NASA Astrophysics Data System (ADS)

Jiang, Yu; Suvanto, Mika; Pakkanen, Tapani A.

2016-01-01

Extensive studies have been performed with the aim of fabricating hierarchical surface structures inspired by nature. However, synthetic hierarchical structures have to sacrifice mechanical resistance to functionality by introducing finer scaled structures. Therefore, surfaces are less durable. Surface micro-micro hierarchy has been proven to be effective in replacing micro-nano hierarchy in the sense of superhydrophobicity. However, less attention has been paid to the combined micro-micro hierarchies with surface pillars and pits incorporated together. The fabrication of this type of hierarchy may be less straightforward, with the possibility of being a complicated multi-step process. In this study, we present a simple yet mass producible fabrication method for hierarchical structures with different combinations of surface pillars and pits. The fabrication was based on only one aluminum (Al) mold with sequential mountings. The fabricated structures exhibit high mechanical durability and structural stabilities with a normal load up to 100 kg. In addition, the theoretical estimation of the wetting state shows a promising way of stabilizing a water droplet on the surface pit structures with a more stable Cassie-Baxter state.

Global Validation of MODIS Atmospheric Profile-Derived Near-Surface Air Temperature and Dew Point Estimates

NASA Astrophysics Data System (ADS)

Famiglietti, C.; Fisher, J.; Halverson, G. H.

2017-12-01

This study validates a method of remote sensing near-surface meteorology that vertically interpolates MODIS atmospheric profiles to surface pressure level. The extraction of air temperature and dew point observations at a two-meter reference height from 2001 to 2014 yields global moderate- to fine-resolution near-surface temperature distributions that are compared to geographically and temporally corresponding measurements from 114 ground meteorological stations distributed worldwide. This analysis is the first robust, large-scale validation of the MODIS-derived near-surface air temperature and dew point estimates, both of which serve as key inputs in models of energy, water, and carbon exchange between the land surface and the atmosphere. Results show strong linear correlations between remotely sensed and in-situ near-surface air temperature measurements (R2 = 0.89), as well as between dew point observations (R2 = 0.77). Performance is relatively uniform across climate zones. The extension of mean climate-wise percent errors to the entire remote sensing dataset allows for the determination of MODIS air temperature and dew point uncertainties on a global scale.

Modeling Linkages Between Effective Impervious Surface and Urban Vegetation Productivity in Semi-arid Environments

NASA Astrophysics Data System (ADS)

Shields, C. A.; Tague, C.

2010-12-01

With a majority of the world's population now living in urban areas, the role of vegetation in urban ecosystems warrants increased attention. We address the question of how the fine scale (<5m) spatial arrangement of impervious surfaces affects water available to vegetation, which in turn can significantly impact the productivity of vegetation and uptake of C and N. To gain insight into how landscape features influence vegetation productivity, we use a coupled ecohydrogic model to estimate impacts of the amount and arrangement of impervious surfaces on vegetation water use. We use the model to explore how concepts from research in natural semi-arid ecosystems can be applied in the urban context. Ecological research in semi-arid ecosystems has shown that the arrangement of vegetated and bare surfaces plays a key role in regulating both runoff and ecosystem water use and productivity. Systems that include a mixture of bare and vegetated surfaces, for example, tend to show less runoff and more productivity than those with more homogeneous cover. In some instances, patchiness of bare and vegetated surfaces is more important than total vegetated area in determining rates of runoff and vegetation use of rainfall. In an urban context, impervious surfaces can be viewed as analogous to the bare surfaces present in undeveloped ecosystems. We consider not only the total impervious area (TIA), but also the effect of impervious area with a direct hydrologic connection to the stream network, effective impervious area (EIA). While increases in total impervious area (TIA) have been widely shown to impact catchment hydrology, the role of effective impervious area (EIA) has been less extensively studied. A consensus is emerging from the literature that EIA is as important or even more important than TIA as an indicator of catchment response to urbanization. Ecohydrologic models offer a tool to quantify the role of EIA on water availability and plant productivity and demonstrate the potential of urban areas to act as C or N sinks (and minimize the impacts such as increased storm runoff and degraded downstream water quality). We explore the relative roles of TIA and EIA on water availability and plant productivity in a semi-arid urban environment through a series of modeling exercises. The Regional HydroEcological Simulation System (RHESSys) is used to model a range of impervious surface and vegetation scenarios on a test hillslope in the Mission Creek catchment in Santa Barbara CA. Results indicate that reduced EIA can indeed act to mitigate the impact of TIA on water available to plants. We then implement a modification to the RHESSys model that incorporates patch scale estimates of EIA into simulations of the entire Mission Creek catchment, allowing us to quantify likely catchment-scale impacts of altering EIA.

Structural features of reconstituted wheat wax films

PubMed Central

Pambou, Elias; Li, Zongyi; Campana, Mario; Hughes, Arwel; Clifton, Luke; Gutfreund, Philipp; Foundling, Jill

2016-01-01

Cuticular waxes are essential for the well-being of all plants, from controlling the transport of water and nutrients across the plant surface to protecting them against external environmental attacks. Despite their significance, our current understanding regarding the structure and function of the wax film is limited. In this work, we have formed representative reconstituted wax film models of controlled thicknesses that facilitated an ex vivo study of plant cuticular wax film properties by neutron reflection (NR). Triticum aestivum L. (wheat) waxes were extracted from two different wheat straw samples, using two distinct extraction methods. Waxes extracted from harvested field-grown wheat straw using supercritical CO2 are compared with waxes extracted from laboratory-grown wheat straw via wax dissolution by chloroform rinsing. Wax films were produced by spin-coating the two extracts onto silicon substrates. Atomic force microscopy and cryo-scanning electron microscopy imaging revealed that the two reconstituted wax film models are ultrathin and porous with characteristic nanoscale extrusions on the outer surface, mimicking the structure of epicuticular waxes found upon adaxial wheat leaf surfaces. On the basis of solid–liquid and solid–air NR and ellipsometric measurements, these wax films could be modelled into two representative layers, with the diffuse underlying layer fitted with thicknesses ranging from approximately 65 to 70 Å, whereas the surface extrusion region reached heights exceeding 200 Å. Moisture-controlled NR measurements indicated that water penetrated extensively into the wax films measured under saturated humidity and under water, causing them to hydrate and swell significantly. These studies have thus provided a useful structural basis that underlies the function of the epicuticular waxes in controlling the water transport of crops. PMID:27466439

Thermal and Hydrologic Signatures of Soil Controls on Evaporation: A Combined Energy and Water Balance Approach with Implications for Remote Sensing of Evaporation

NASA Technical Reports Server (NTRS)

Salvucci, Guido D.

2000-01-01

The overall goal of this research is to examine the feasibility of applying a newly developed diagnostic model of soil water evaporation to large land areas using remotely sensed input parameters. The model estimates the rate of soil evaporation during periods when it is limited by the net transport resulting from competing effects of capillary rise and drainage. The critical soil hydraulic properties are implicitly estimated via the intensity and duration of the first stage (energy limited) evaporation, removing a major obstacle in the remote estimation of evaporation over large areas. This duration, or 'time to drying' (t(sub d)) is revealed through three signatures detectable in time series of remote sensing variables. The first is a break in soil albedo that occurs as a small vapor transmission zone develops near the surface. The second is a break in either surface to air temperature differences or in the diurnal surface temperature range, both of which indicate increased sensible heat flux (and/or storage) required to balance the decrease in latent heat flux. The third is a break in the temporal pattern of near surface soil moisture. Soil moisture tends to decrease rapidly during stage I drying (as water is removed from storage), and then become more or less constant during soil limited, or 'stage II' drying (as water is merely transmitted from deeper soil storage). The research tasks address: (1) improvements in model structure, including extensions to transpiration and aggregation over spatially variable soil and topographic landscape attributes; and (2) applications of the model using remotely sensed input parameters.

Thermal and Hydrologic Signatures of Soil Controls on Evaporation: A Combined Energy and Water Balance Approach with Implications for Remote Sensing of Evaporation

NASA Technical Reports Server (NTRS)

Salvucci, Guido D.

1997-01-01

The overall goal of this research is to examine the feasibility of applying a newly developed diagnostic model of soil water evaporation to large land areas using remotely sensed input parameters. The model estimates the rate of soil evaporation during periods when it is limited by the net transport resulting from competing effects of capillary rise and drainage. The critical soil hydraulic properties are implicitly estimated via the intensity and duration of the first stage (energy limited) evaporation, removing a major obstacle in the remote estimation of evaporation over large areas. This duration, or "time to drying" (t(sub d)), is revealed through three signatures detectable in time series of remote sensing variables. The first is a break in soil albedo that occurs as a small vapor transmission zone develops near the surface. The second is a break in either surface to air temperature differences or in the diurnal surface temperature range, both of which indicate increased sensible heat flux (and/or storage) required to balance the decrease in latent heat flux. The third is a break in the temporal pattern of near surface soil moisture. Soil moisture tends to decrease rapidly during stage 1 drying (as water is removed from storage), and then become more or less constant during soil limited, or "stage 2" drying (as water is merely transmitted from deeper soil storage). The research tasks address: (1) improvements in model structure, including extensions to transpiration and aggregation over spatially variable soil and topographic landscape attributes; and (2) applications of the model using remotely sensed input parameters.

On the use of satellite data to implement a parsimonious ecohydrological model in the upper Ewaso Ngiro river basin

NASA Astrophysics Data System (ADS)

Ruiz-Pérez, G.

2015-12-01

Drylands are extensive, covering 30% of the Earth's land surface and 50% of Africa. Projections of the IPCC (Intergovernmental Panel on Climate Change, 2007) indicate that the extent of these regions have high probability to increase with a considerable additional impact on water resources, which should be taken into account by water management plans. In these water-controlled areas, vegetation plays a key role in the water cycle. Ecohydrological models provide a tool to investigate the relationships between vegetation and water resources. However, studies in Africa often face the problem that many ecohydrological models have quite extensive parametrical requirements, while available data are scarce. Therefore, there is a need for assessments using models whose requirements match the data availability. In that context, parsimonious models, together with available remote sensing information, can be valuable tools for ecohydrological studies. For this reason, we have focused on the use of a parsimonious model based on the amount of photosynthetically active radiation absorbed by green vegetation (APAR) and the Light Use Efficiency index (the efficiency by which that radiation is converted to plant biomass increment) in order to compute the gross primary production (GPP).This model has been calibrated using only remote sensing data (particularly, NDVI data from Modis products) in order to explore the potential of satellite information in implementing a simple distributed model. The model has been subsequently validated against stream flow data with the aim to define a tool able to account for landuse characteristics in describing water budget. Results are promising for studies aimed at the description of the consequences of ongoing land use changes on water resources.

Late Spring Nitrate Distributions Beneath the Ice-Covered Northeastern Chukchi Shelf

NASA Astrophysics Data System (ADS)

Arrigo, Kevin R.; Mills, Matthew M.; van Dijken, Gert L.; Lowry, Kate E.; Pickart, Robert S.; Schlitzer, Reiner

2017-09-01

Measurements of late springtime nutrient concentrations in Arctic waters are relatively rare due to the extensive sea ice cover that makes sampling difficult. During the SUBICE (Study of Under-ice Blooms In the Chukchi Ecosystem) cruise in May-June 2014, an extensive survey of hydrography and prebloom concentrations of inorganic macronutrients, oxygen, particulate organic carbon and nitrogen, and chlorophyll a was conducted in the northeastern Chukchi Sea. Cold (<-1.5°C) winter water was prevalent throughout the study area, and the water column was weakly stratified. Nitrate (NO3-) concentration averaged 12.6 ± 1.92 μM in surface waters and 14.0 ± 1.91 μM near the bottom and was significantly correlated with salinity. The highest NO3- concentrations were associated with winter water within the Central Channel flow path. NO3- concentrations were much reduced near the northern shelf break within the upper halocline waters of the Canada Basin and along the eastern side of the shelf near the Alaskan coast. Net community production (NCP), estimated as the difference in depth-integrated NO3- content between spring (this study) and summer (historical), varied from 28 to 38 g C m-2 a-1. This is much lower than previous NCP estimates that used NO3- concentrations from the southeastern Bering Sea as a baseline. These results demonstrate the importance of using profiles of NO3- measured as close to the beginning of the spring bloom as possible when estimating local NCP. They also show that once the snow melts in spring, increased light transmission through the sea ice to the waters below the ice could fuel large phytoplankton blooms over a much wider area than previously known.

Fabrication of a superhydrophobic and high-glossy copper coating on aluminum substrates

NASA Astrophysics Data System (ADS)

Yang, Hao; He, Yuantao; Wu, Zhongqiang; Miao, Jing; Yang, Fang; Lu, Zhong

2018-03-01

Superhydrophobic metal coatings have been extensively studied in recent years because of their significant potential applications. Unfortunately, most of them lost the original metallic luster due to the micro/nano binary structures. In this paper, a facile method was developed to prepare a superhydrophobic and high-glossy copper coating on aluminum substrates. The bionic lotus leaf surfaces were constructed by electroless plating method and further modified with octadecanethiol. The wettability and gloss could be tuned by the concentration of the precursor. With the increase of CuSO4 concentration, the surface roughness of the coating raised, thus resulting in increase of contact angle and decrease of glossiness. When the CuSO4 concentration was 30 mmol/L, the coating exhibited a sub-micro/nano binary structure, in which 20-30 nm protuberances were grown on 300-500 nm mastoids. Such special morphology endowed the coating with superhydrophobic and high-glossy properties, and the coating also showed ultra-low water adhesion and stable dynamic water repellence.

Distribution of leached radioactive material in the Legin Group Area, San Miguel County, Colorado

USGS Publications Warehouse

Rogers, Allen S.

1950-01-01

Radioactivity anomalies, which are small in magnitude, and probably are not caused by extensions of known uranium-vanadium ore bodies, were detected during the gamma-ray logging of diamond-drill holes in the Legin group of claims, southwest San Miguel County, Colo. The positions of these anomalies are at the top surfaces of mudstone strata within, and at the base of, the ore-bearing sandstone of the Salt Wash member of the Morrison formation. The distribution of these anomalies suggests that ground water has leached radioactive material from the ore bodies and has carried it down dip and laterally along the top surfaces of underlying impermeable mudstone strata for distance as great as 300 feet. The anomalies are probably caused by radon and its daughter elements. Preliminary tests indicate that radon in quantities up to 10-7 curies per liter may be present in ground water flowing along sandstone-mudstone contacts under carnotite ore bodies. In comparison, the radium content of the same water is less than 10-10 curies per liter. Further substantiation of the relationship between ore bodies, the movement of water, and the radon-caused anomalies may greatly increase the scope of gamma-ray logs of drill holes as an aid to prospecting.

Reservoir-development impacts on surface-water quantity and quality in the Yampa River basin, Colorado and Wyoming

USGS Publications Warehouse

Adams, D. Briane; Bauer, Daniel P.; Dale, Robert H.; Steele, Timothy Doak

1983-01-01

Development of coal resources and associated economy is accelerating in the Yampa River basin in northwestern Colorado and south-central Wyoming. Increased use of the water resources of the area will have a direct impact on their quantity and quality. As part of 18 surface-water projects, 35 reservoirs have been proposed with a combined total storage of 2.18 million acre-feet, 41% greater than the mean annual outflow from the basin. Three computer models were used to demonstrate methods of evaluating future impacts of reservoir development in the Yampa River basin. Four different reservoir configurations were used to simulate the effects of different degrees of proposed reservoir development. A multireservoir-flow model included both within-basin and transmountain diversions. Simulations indicated that in many cases diversion amounts would not be available for either type of diversion. A corresponding frequency analysis of reservoir storage levels indicated that most reservoirs would be operating with small percentages of total capacities and generally with less than 20% of conservation-pool volumes. Simulations using a dissolved-solids model indicated that extensive reservoir development could increase average annual concentrations at most locations. Simulations using a single-reservoir model indicated no significant occurrence of water-temperature stratification in most reservoirs due to limited reservoir storage. (USGS)

Daytime Land Surface Temperature Extraction from MODIS Thermal Infrared Data under Cirrus Clouds

PubMed Central

Fan, Xiwei; Tang, Bo-Hui; Wu, Hua; Yan, Guangjian; Li, Zhao-Liang

2015-01-01

Simulated data showed that cirrus clouds could lead to a maximum land surface temperature (LST) retrieval error of 11.0 K when using the generalized split-window (GSW) algorithm with a cirrus optical depth (COD) at 0.55 μm of 0.4 and in nadir view. A correction term in the COD linear function was added to the GSW algorithm to extend the GSW algorithm to cirrus cloudy conditions. The COD was acquired by a look up table of the isolated cirrus bidirectional reflectance at 0.55 μm. Additionally, the slope k of the linear function was expressed as a multiple linear model of the top of the atmospheric brightness temperatures of MODIS channels 31–34 and as the difference between split-window channel emissivities. The simulated data showed that the LST error could be reduced from 11.0 to 2.2 K. The sensitivity analysis indicated that the total errors from all the uncertainties of input parameters, extension algorithm accuracy, and GSW algorithm accuracy were less than 2.5 K in nadir view. Finally, the Great Lakes surface water temperatures measured by buoys showed that the retrieval accuracy of the GSW algorithm was improved by at least 1.5 K using the proposed extension algorithm for cirrus skies. PMID:25928059

Abandoned floodplain plant communities along a regulated dryland river

USGS Publications Warehouse

Reynolds, L. V.; Shafroth, Patrick B.; House, P. K.

2014-01-01

Rivers and their floodplains worldwide have changed dramatically over the last century because of regulation by dams, flow diversions and channel stabilization. Floodplains no longer inundated by river flows following dam-induced flood reduction comprise large areas of bottomland habitat, but the effects of abandonment on plant communities are not well understood. Using a hydraulic flow model, geomorphic mapping and field surveys, we addressed the following questions along the Bill Williams River, Arizona: (i) What per cent of the bottomland do abandoned floodplains comprise? and (ii) Are abandoned floodplains quantitatively different from adjacent xeric and riparian surfaces in terms of vegetation composition and surface sediment? We found that nearly 70% of active channel and floodplain area was abandoned following dam installation. Abandoned floodplains along the Bill Williams River tend to be similar to each other yet distinct from neighbouring habitats: they have been altered physically from their historic state, leading to distinct combinations of surface sediments, hydrology and plant communities. Abandoned floodplains may transition to xeric communities over time but are likely to retain some riparian qualities as long as there is access to relatively shallow ground water. With expected increases in water demand and drying climatic conditions in many regions, these surfaces and associated vegetation will continue to be extensive in riparian landscapes worldwide

Assessment of sea water inundation along Daboo creek area in Indus Delta Region, Pakistan

NASA Astrophysics Data System (ADS)

Zia, Ibrahim; Zafar, Hina; Shahzad, Muhammad I.; Meraj, Mohsin; Kazmi, Jamil H.

2017-12-01

Indus Deltaic Region (IDR) in Pakistan is an erosion vulnerable coast due to the high deep water wave energy. Livelihood of millions of people depends on the fisheries and mangrove forests in IDR. IDR consists of many creeks where Daboo is a major creek located at southeast of the largest city of Pakistan, Karachi. Unfortunately, there has been no detailed study to analyze the damages of sea water intrusion at a large temporal and spatial scale. Therefore, this study is designed to estimate the effects of sea water inundation based on changing sea water surface salinity and sea surface temperature (SST). Sea surface salinity and SST data from two different surveys in Daboo creek during 1986 and 2010 are analyzed to estimate the damages and extent of sea water intrusion. Mean salinity has increased 33.33% whereas mean SST decreased 13.79% from 1987 to 2010. Spatio-temporal analysis of creek area using LANDSAT 5 Thematic mapper (TM) data for the years 1987 and 2010 shows significant amount of erosion at macro scale. Creek area has increased approximately 9.93% (260.86 m2 per year) which is roughly equal to 60 extensive sized shrimp farms. Further Land Use Land Cover (LULC) analyses for years 2001 and 2014 using LANDSAT 7 Enhanced Thematic Mapper Plus (ETM+) has indicated 42.3% decrease in cultivated land. Wet mud flats have spread out at the inner mouth of creek with enormous increase of 123.3%. Significant sea water intrusion has increased the area of barren land by 37.9%. This also resulted in overall decrease of 6.7% in area covered by mangroves. Therefore, this study recorded a significant evidence of sea water intrusion in IDR that has caused serious damages to community living in the area, economical losses. Additionally, it has also changed the environment by reducing creek biological productivity as reported by earlier studies over other regions of the world.

Numerical simulation of hydrothermal circulation in the Cascade Range, north-central Oregon

USGS Publications Warehouse

Ingebritsen, S.E.; Paulson, K.M.

1990-01-01

Alternate conceptual models to explain near-surface heat-flow observations in the central Oregon Cascade Range involve (1) an extensive mid-crustal magmatic heat source underlying both the Quaternary arc and adjacent older rocks or (2) a narrower deep heat source which is flanked by a relatively shallow conductive heat-flow anomaly caused by regional ground-water flow (the lateral-flow model). Relative to the mid-crustal heat source model, the lateral-flow model suggests a more limited geothermal resource base, but a better-defined exploration target. We simulated ground-water flow and heat transport through two cross sections trending west from the Cascade range crest in order to explore the implications of the two models. The thermal input for the alternate conceptual models was simulated by varying the width and intensity of a basal heat-flow anomaly and, in some cases, by introducing shallower heat sources beneath the Quaternary arc. Near-surface observations in the Breitenbush Hot Springs area are most readily explained in terms of lateral heat transport by regional ground-water flow; however, the deep thermal structure still cannot be uniquely inferred. The sparser thermal data set from the McKenzie River area can be explained either in terms of deep regional ground-water flow or in terms of a conduction-dominated system, with ground-water flow essentially confined to Quaternary rocks and fault zones.

Ground water in the carbonate rocks of the Franklin area, Tennessee

USGS Publications Warehouse

Zurawski, Ann; Burchett, C.R.

1980-01-01

A study of ground water in the Franklin area, Tennessee, was undertaken to fill a growing need for information on ground-water occurrence in the carbonate rocks of central Tennessee. Fifteen drilling sites were selected that had one or more of the following characteristics: medium- to thick-bedded limestones within 200 feet of land surface, structural lows, significant streamflow gains and losses, elongated sinkholes, straight stream reaches, linear features or other surface indications of solution cavities at depth. The 15 test wells produced from less than 1 to about 600 gallons per minute and had an average yield of 68 gallons per minute, measured while pumping the wells with compressed air. The average driller-reported yield for the area is five gallons per minute. Specific capacities for the four highest yielding wells ranged from 0.6 to 357 gallons per minute per foot of drawdown after 8 hours of pumping at rates ranging from 70 to 225 gallons per minute. Additional drilling at two sites revealed extensive solution openings. At one site, drawdown in five observation wells did not exceed 8.5 feet during 48 hours of pumping at an average rate of 502 gallons per minute. Raw water in the test wells meets most drinking-water standards and is of rather uniform quality from well to well and throughout the year. (USGS)

Soft-bed experiments beneath Engabreen, Norway: Regelation, infiltration, basal slip and bed deformation

USGS Publications Warehouse

Iverson, N.R.; Hooyer, T.S.; Fischer, U.H.; Cohen, D.; Moore, P.L.; Jackson, M.; Lappegard, G.; Kohler, J.

2007-01-01

To avoid some of the limitations of studying soft-bed processes through boreholes, a prism of simulated till (1.8 m ?? 1.6 m ?? 0.45 m) with extensive instrumentation was constructed in a trough blasted in the rock bed of Engabreen, a temperate glacier in Norway. Tunnels there provide access to the bed beneath 213 m of ice. Pore-water pressure was regulated in the prism by pumping water to it. During experiments lasting 7-12 days, the glacier regelated downward into the prism to depths of 50-80 mm, accreting ice-infiltrated till at rates predicted by theory. During periods of sustained high pore-water pressure (70-100% of overburden), ice commonly slipped over the prism, due to a water layer at the prism surface. Deformation of the prism was activated when this layer thinned to a sub-millimeter thickness. Shear strain in the till was pervasive and decreased with depth. A model of slip by ploughing of ice-infiltrated till across the prism surface accounts for the slip that occurred when effective pressure was sufficiently low or high. Slip at low effective pressures resulted from water-layer thickening that increased non-linearly with decreasing effective pressure. If sufficiently widespread, such slip over soft glacier beds, which involves no viscous deformation resistance, may instigate abrupt increases in glacier velocity.

Geochemical investigation of weathering processes in a forested headwater catchment: Mass-balance weathering fluxes

USGS Publications Warehouse

Jones, B.F.; Herman, J.S.

2008-01-01

Geochemical research on natural weathering has often been directed towards explanations of the chemical composition of surface water and ground water resulting from subsurface water-rock interactions. These interactions are often defined as the incongruent dissolution of primary silicates, such as feldspar, producing secondary weathering products, such as clay minerals and oxyhydroxides, and solute fluxes (Meunier and Velde, 1979). The chemical composition of the clay-mineral product is often ignored. However, in earlier investigations, the saprolitic weathering profile at the South Fork Brokenback Run (SFBR) watershed, Shenandoah National Park, Virginia, was characterized extensively in terms of its mineralogical and chemical composition (Piccoli, 1987; Pochatila et al., 2006; Jones et al., 2007) and its basic hydrology. O'Brien et al. (1997) attempted to determine the contribution of primary mineral weathering to observed stream chemistry at SFBR. Mass-balance model results, however, could provide only a rough estimate of the weathering reactions because idealized mineral compositions were utilized in the calculations. Making use of detailed information on the mineral occurrence in the regolith, the objective of the present study was to evaluate the effects of compositional variation on mineral-solute mass-balance modelling and to generate plausible quantitative weathering reactions that support both the chemical evolution of the surface water and ground water in the catchment, as well as the mineralogical evolution of the weathering profile. ?? 2008 The Mineralogical Society.

Nanofiltration and Tight Ultrafiltration Membranes for Natural Organic Matter Removal—Contribution of Fouling and Concentration Polarization to Filtration Resistance

PubMed Central

Winter, Joerg; Bérubé, Pierre

2017-01-01

Nanofiltration (NF) and tight ultrafiltration (tight UF) membranes are a viable treatment option for high quality drinking water production from sources with high concentrations of contaminants. To date, there is limited knowledge regarding the contribution of concentration polarization (CP) and fouling to the increase in resistance during filtration of natural organic matter (NOM) with NF and tight UF. Filtration tests were conducted with NF and tight UF membranes with molecular weight cut offs (MWCOs) of 300, 2000 and 8000 Da, and model raw waters containing different constituents of NOM. When filtering model raw waters containing high concentrations of polysaccharides (i.e., higher molecular weight NOM), the increase in resistance was dominated by fouling. When filtering model raw waters containing humic substances (i.e., lower molecular weight NOM), the increase in filtration resistance was dominated by CP. The results indicate that low MWCO membranes are better suited for NOM removal, because most of the NOM in surface waters consist mainly of humic substances, which were only effectively rejected by the lower MWCO membranes. However, when humic substances are effectively rejected, CP can become extensive, leading to a significant increase in filtration resistance by the formation of a cake/gel layer at the membrane surface. For this reason, cross-flow operation, which reduces CP, is recommended. PMID:28671604

Water chemistry in 179 randomly selected Swedish headwater streams related to forest production, clear-felling and climate.

PubMed

Löfgren, Stefan; Fröberg, Mats; Yu, Jun; Nisell, Jakob; Ranneby, Bo

2014-12-01

From a policy perspective, it is important to understand forestry effects on surface waters from a landscape perspective. The EU Water Framework Directive demands remedial actions if not achieving good ecological status. In Sweden, 44 % of the surface water bodies have moderate ecological status or worse. Many of these drain catchments with a mosaic of managed forests. It is important for the forestry sector and water authorities to be able to identify where, in the forested landscape, special precautions are necessary. The aim of this study was to quantify the relations between forestry parameters and headwater stream concentrations of nutrients, organic matter and acid-base chemistry. The results are put into the context of regional climate, sulphur and nitrogen deposition, as well as marine influences. Water chemistry was measured in 179 randomly selected headwater streams from two regions in southwest and central Sweden, corresponding to 10 % of the Swedish land area. Forest status was determined from satellite images and Swedish National Forest Inventory data using the probabilistic classifier method, which was used to model stream water chemistry with Bayesian model averaging. The results indicate that concentrations of e.g. nitrogen, phosphorus and organic matter are related to factors associated with forest production but that it is not forestry per se that causes the excess losses. Instead, factors simultaneously affecting forest production and stream water chemistry, such as climate, extensive soil pools and nitrogen deposition, are the most likely candidates The relationships with clear-felled and wetland areas are likely to be direct effects.

A new tool for laboratory studies on volatilization: extension of applicability of the photovolatility chamber.

PubMed

Wolters, André; Kromer, Thomas; Linnemann, Volker; Schäffer, Andreas; Vereecken, Harry

2003-04-01

Volatilization from soil and plant surfaces after application is an important source of pesticide residues to the atmosphere. The laboratory photovolatility chamber allows the simultaneous measurement of volatilization and photodegradation of 14C-labeled pesticides under controlled climatic conditions. Both continuous air sampling, which quantifies volatile organic compounds and 14CO2 separately, and the detection of surface-located residues allow for a mass balance of radioactivity. The setup of the photovolatility chamber was optimized, and additional sensors were installed to characterize the influence of soil moisture, soil temperature, and evaporation on volatilization. The modified flow profile in the glass dome of the chamber arising from the use of a high-performance metal bellows pump was measured. Diminished air velocity near the soil surface and a wind velocity of 0.2 m/s in 3 cm height allowed the requirements of the German guideline on assessing pesticide volatilization for registration purposes to be fulfilled. Determination of soil moisture profiles of the upper soil layer illustrated that defined water content in the soil up to a depth of 4 cm could be achieved by water saturation of air. Cumulative volatilization of [phenyl-UL-14C]parathion-methyl ranged from 2.4% under dry conditions to 32.9% under moist conditions and revealed the clear dependence of volatilization on the water content in the top layer.

Thermal infrared remote sensing in assessing groundwater and surface-water resources related to Hannukainen mining development site, northern Finland

NASA Astrophysics Data System (ADS)

Rautio, Anne B.; Korkka-Niemi, Kirsti I.; Salonen, Veli-Pekka

2018-02-01

Mining development sites occasionally host complicated aquifer systems with notable connections to natural surface water (SW) bodies. A low-altitude thermal infrared (TIR) imaging survey was conducted to identify hydraulic connections between aquifers and rivers and to map spatial surface temperature patterns along the subarctic rivers in the proximity of the Hannukainen mining development area, northern Finland. In addition to TIR data, stable isotopic compositions ( δ 18O, δD) and dissolved silica concentrations were used as tracers to verify the observed groundwater (GW) discharge into the river system. Based on the TIR survey, notable GW discharge into the main river channel and its tributaries (61 km altogether) was observed and over 500 GW discharge sites were located. On the basis of the survey, the longitudinal temperature patterns of the studied rivers were found to be highly variable. Hydrological and hydrogeological information is crucial in planning and siting essential mining operations, such as tailing areas, in order to prevent any undesirable environmental impacts. The observed notable GW discharge was taken into consideration in the planning of the Hannukainen mining development area. The results of this study support the use of TIR imagery in GW-SW interaction and environmental studies in extensive and remote areas with special concerns for water-related issues but lacking the baseline research.

Episodic Endogenetic-driven Atmospheric and Hydrologic Cycles and Their Influence on the Geologic Records of the Northern and Southern Hemispheres, Mars

NASA Technical Reports Server (NTRS)

Dohm, J. M.; Fairen, A. G.; Baker, V. R.; Ferris, J. C.; Anderson, R. C.; Uceda, E. R.

2003-01-01

Diverse evidence shows a direct correlation between episodic endogenetic events of the Tharsis magmatic complex (TMC)/Superplume, flood inundations in the northern plains, and glacial/ lacustrine/ice sheet activity in the south polar region, which includes Hellas and Argyre impact basins, corroborating the MEGAOUTFLO hypothesis. The TMC encompasses a total surface area of approximately 2 x 10(exp 7) sq km, which is slightly larger than the estimated size of the Southern Pacific Superplume. These hydrologic events include: (1) a Noachian to possibly Early Hesperian oceanic epoch and related atmospheric and environmental change (a water body covering about 1/3 of the planet s surface area) related to the incipient development of Tharsis Superplume and the northwestern sloping valleys (NSVs) and possibly early circum-Chryse development, the northwest and northeast watersheds of Tharsis, respectively, (2) a smaller ocean inset within the former larger ocean related to extensive Late Hesperian to Early Amazonian effusive volcanism at Tharsis and Elysium and incisement of the circum-Chryse outflow system. During this time, magmatic/plume-driven tectonic activity transitioned into more centralized volcanism. This Late Hesperian water body may have simply diminished into smaller seas and/or lakes during the Amazonian Period, or renewed activity at Tharsis and Elysium resulted in brief perturbations from the prevailing cold and dry climatic conditions to later form minor seas or lakes. All of the hydrologic phases transitioned into extensive periods of quiescence.

Sources of Water to Wells for Transient Cyclic Systems

USGS Publications Warehouse

Reilly, T.E.; Pollock, D.W.

1996-01-01

Many state agencies are currently (1995) developing wellhead protection programs. The thrust of some of these programs is to protect water supplies by determining the areas contributing recharge to water-supply wells and by specifying regulations to minimize the opportunity for contamination of the recharge water by activities at the land surface. The area contributing recharge to a discharging well is the surface area at the water table through which the water flowing to the well entered the ground-water system. In the analyses of ground-water flow systems, steady-state average conditions are commonly used to simplify the problem and make a solution tractable. However, recharge is usually cyclic in nature, with seasonal cycles and longer term climatic cycles. The effect of these cyclic stresses on the area contributing recharge to wells is quantitatively analyzed for a hypothetical alluvial valley aquifer system that is representative of a large class of ground-water systems that are extensively developed for water supply. The analysis shows that, in many cases, these cyclic changes in the recharge rates do not significantly affect the location and size of the areas contributing recharge to wells. The ratio of the mean travel time to the length of the cyclic stress period appears to be an indicator of whether the transient effects of the cyclic stress must be explicitly represented in the analysis of contributing areas to wells. For the cases examined, if the ratio of the mean travel time to the period of the cyclic stress was much greater than one, then the transient area contributing recharge to wells was similar to the area calculated using an average steady-state condition. However, cyclic stresses on systems with ratios less than one do have an effect on the location and size of the areas contributing recharge to wells.

Assimilation of Remotely Sensed Evaporative Fraction for Improved Agricultural Irrigation Water Management

NASA Astrophysics Data System (ADS)

Lei, F.; Crow, W. T.; Kustas, W. P.; Yang, Y.; Anderson, M. C.

2017-12-01

Improving the water usage efficiency and maintaining water use sustainability is challenging under rapidly changed natural environments. For decades, extensive field investigations and conceptual/physical numerical modeling have been developed to quantify and track surface water and energy fluxes at different spatial and temporal scales. Meanwhile, with the development of satellite-based sensors, land surface eco-hydrological parameters can be retrieved remotely to supplement ground-based observations. However, both models and remote sensing retrievals contain various sources of errors and an accurate and spatio-temporally continuous simulation and forecasting system at the field-scale is crucial for the efficient water management in agriculture. Specifically, data assimilation technique can optimally integrate measurements acquired from various sources (including in-situ and remotely-sensed data) with numerical models through consideration of different types of uncertainties. In this presentation, we will focus on improving the estimation of water and energy fluxes over a vineyard in California, U.S. A high-resolution remotely-sensed Evaporative Fraction (EF) product from the Atmosphere-Land Exchange Inverse (ALEXI) model will be incorporated into a Soil Vegetation Atmosphere Transfer (SVAT) model via a 2-D data assimilation method. The results will show that both the accuracy and spatial variability of soil water content and evapotranspiration in SVAT model can be enhanced through the assimilation of EF data. Furthermore, we will demonstrate that by taking the optimized soil water flux as initial condition and combining it with weather forecasts, future field water status can be predicted under different irrigation scenarios. Finally, we will discuss the practical potential of these advances by leveraging our numerical experiment for the design of new irrigation strategies and water management techniques.

Coping with drought: A High Resolution Drought Monitoring and Prediction System for the Pacific Northwest

NASA Astrophysics Data System (ADS)

Xiao, M.; Nijssen, B.; Shukla, S.; Lettenmaier, D. P.

2013-12-01

The Pacific Northwest (PNW) region in North America (defined here as the Columbia and Klamath River basins plus the coastal drainages) is a diverse geographic region with complex topography and a variety of climates. Agriculture (dryland and irrigated), forestry, fisheries, and hydropower provide significant economic benefit to the region and are directly dependent on the availability of sufficient water at the right time. Additional demands are made on water supplies by recreation, ecosystem services and emerging needs such as hydropower generation in support of wind energy integration. Several major droughts have occurred over the region in recent decades (notably 1977, 2001, and 2004), which have had significant consequences for the region's agricultural, hydropower production, and environment. An emerging need for the region is the coordination of existing regional climate activities, including a better awareness of the current water availability conditions across the region. The University of Washington has operated a surface water monitor for the continental United States since 2005, which provides near real-time estimates of surface water conditions at a spatial resolution of 1/2 degree in terms of soil moisture, snow water equivalent, and total moisture based on a suite of land surface models. A higher resolution Drought Monitoring and Prediction System (DMPS) for Washington State was originally implemented at 1/8 degree and later increased to 1/16 degree. This presentation describes the extension of this system to the entire PNW region at 1/16 degree. The expanded system provides daily updates of three primary drought-related indices based on near real-time station observations in the region: Standardized Precipitation Index (SPI), Standardized Runoff Index (SRI), and Soil Moisture Percentiles (SMP). To make the drought measures relevant to water managers, surface water conditions are not only reported on a gridded map, but watershed-level drought summary indices are reported for larger aggregates such as the Water Resource Inventory Areas (WRIAs) in Washington State and the Water Allocation Basins (WABs) within Oregon. We explore the ability of the system to reproduce historic droughts for the period since 1915 and analyze regional differences in drought dynamics within the PNW. We also evaluate the lead time that would have been provided by the system had it been available relative to official drought declarations.

Applying Henry`s Law to groundwater treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chidgopkar, V.R.

Air strippers are very popular equipment for mass transfer where air and water are contacted and the contaminants are transferred from water into the air phase. In a typical air-stripper arrangement, water flows from the top and air is blown from the bottom. The increase in surface area between the air and the water phases increases the removal efficiency. In packed towers, high-surface-area packing materials are used to that end. In a sieve tray tower, water flows across the tray through channels separated by baffles and air flows from the bottom, up through holes in the tray. In diffused aerators,more » air is introduced through a bubbler or a nozzle into the water stream. All these units are commercially available. Several environmental consulting and remediation engineering firms use Henry`s Law to predict the stripping performance of volatile and semi-volatile contaminants present using the above equipment. Extensive work has been done during the past few decades to determine Henry`s Law constant, H. Different procedures are reported in the literature to determine henry`s Law constant for various chemicals from the experimental data and from empirical correlations. This article discusses the reasons why so much error is observed in reported values of henry`s Law constants in the literature--the effect of various parameters such as temperature, co-solubility, etc., on H value. A modified experimental procedure to measure Henry`s Law constant is presented, then the law is applied in predicting stripping performance of various chemicals.« less

GCIP water and energy budget synthesis (WEBS)

USGS Publications Warehouse

Roads, J.; Lawford, R.; Bainto, E.; Berbery, E.; Chen, S.; Fekete, B.; Gallo, K.; Grundstein, A.; Higgins, W.; Kanamitsu, M.; Krajewski, W.; Lakshmi, V.; Leathers, D.; Lettenmaier, D.; Luo, L.; Maurer, E.; Meyers, T.; Miller, D.; Mitchell, Ken; Mote, T.; Pinker, R.; Reichler, T.; Robinson, D.; Robock, A.; Smith, J.; Srinivasan, G.; Verdin, K.; Vinnikov, K.; Vonder, Haar T.; Vorosmarty, C.; Williams, S.; Yarosh, E.

2003-01-01

As part of the World Climate Research Program's (WCRPs) Global Energy and Water-Cycle Experiment (GEWEX) Continental-scale International Project (GCIP), a preliminary water and energy budget synthesis (WEBS) was developed for the period 1996-1999 fromthe "best available" observations and models. Besides this summary paper, a companion CD-ROM with more extensive discussion, figures, tables, and raw data is available to the interested researcher from the GEWEX project office, the GAPP project office, or the first author. An updated online version of the CD-ROM is also available at http://ecpc.ucsd.edu/gcip/webs.htm/. Observations cannot adequately characterize or "close" budgets since too many fundamental processes are missing. Models that properly represent the many complicated atmospheric and near-surface interactions are also required. This preliminary synthesis therefore included a representative global general circulation model, regional climate model, and a macroscale hydrologic model as well as a global reanalysis and a regional analysis. By the qualitative agreement among the models and available observations, it did appear that we now qualitatively understand water and energy budgets of the Mississippi River Basin. However, there is still much quantitative uncertainty. In that regard, there did appear to be a clear advantage to using a regional analysis over a global analysis or a regional simulation over a global simulation to describe the Mississippi River Basin water and energy budgets. There also appeared to be some advantage to using a macroscale hydrologic model for at least the surface water budgets. Copyright 2003 by the American Geophysical Union.

First-Principles Study of the Electric Field Effect on the Water-Adsorbed Rutile Titanium Dioxide Surface

NASA Astrophysics Data System (ADS)

Hmiel, Abraham L.

TiO2 is a semiconducting material that has been used extensively in many industrial applications, and recently has become a candidate for photocatalytic water splitting, fuel cell anode support materials, sensors, and other novel nanodevices. The interface of TiO2 with water, historically well-studied but still poorly understood, presents a ubiquitous environmental challenge towards the ultimate practical usefulness of these technologies. Ground-state density functional theory (DFT) calculations studying the characteristics of molecular adsorption on model surfaces have been studied for decades, showing constant improvement in the description of the energetics and electronic structure at interfaces. These simulations are invaluable in the materials science innovation pipeline because they can interpret the results of experiments and investigate properties at the nanoscale that traditional methods cannot reach. In this work, spin-polarized DFT calculations within the generalized gradient approximation and with the recent self-consistent opt-B88 van der Waals functional have been applied to investigate the problem of molecularly adsorbed water on the rutile (110) TiO2 surface under the influence of an applied electric field. The effective screening medium theory is used to break the symmetry of the simulation in the slab normal direction and implement a metal-like boundary condition at the edges of the simulation cell to model the charged capacitor in a real electrochemical device. This study begins with an investigation of bulk and surface properties of TiO2 to obtain a sound theoretical baseline. Following that, an attempt to obtain simple and meaningful structure-property relationships of rectangular TiO 2 nanowires with (110) facets resulting from quantum confinement. Finally, a systematic study of energetics, geometrical configuration, charge partitioning, and electronic structure of water in monomer coverage up to monolayer coverage provides insight into the usefulness of the inclusion of self-consistent van der Waals correlation effects and the effect of an external electric field in this model of adsorption on a prototypical metal oxide surface. Nontrivial differences between the two functionals' description of adsorption of water, electrostatic characteristics, and electronic structure of the model surface are reported in the zero-field limit as well as with an applied field.

The occurrence and geochemistry of fluoride in some natural waters of Kenya

NASA Astrophysics Data System (ADS)

Gaciri, S. J.; Davies, T. C.

1993-03-01

In recent years the acquisition of considerable additional data on the hydrogeochemical behaviour of fluoride in natural waters of Kenya has been made possible by extensive surface-water and groundwater sampling campaigns as well as by improvements in analytical techniques. Ultimately, the principal source of fluoride relates to emissions from volcanic activity associated with the East African Rift System. Through various intermediate steps, but also directly, fluoride passes into the natural water system and components of the food chain. Ingestion by man is mainly through drinking water and other beverages. River waters in Kenya generally have a fluoride concentration lower than the recommended level (1.3 ppm) for potable water, thus promoting susceptibility to dental caries. Groundwaters and lake waters show considerably higher fluoride contents, resulting in the widespread incidence of fluorosis in areas where groundwater is the major source of drinking water, and lake fish is a regular component of the diet. This paper presents a synthesis of the data so far obtained on the sources and distribution of fluoride in the hydrological system of Kenya, examines the extent of fluorine toxicity and puts forward recommendations to combat or minimise the problem.

Veneers, rinds, and fracture fills: Relatively late alteration of sedimentary rocks at Meridiani Planum, Mars

USGS Publications Warehouse

Knoll, A.H.; Jolliff, B.L.; Farrand, W. H.; Bell, J.F.; Clark, B. C.; Gellert, Ralf; Golombek, M.P.; Grotzinger, J.P.; Herkenhoff, K. E.; Johson, J.R.; McLennam, S.M.; Morris, Robert; Squyres, S. W.; Sullivan, R.; Tosca, N.J.; Yen, A.; Learner, Z.

2008-01-01

Veneers and thicker rinds that coat outcrop surfaces and partially cemented fracture fills formed perpendicular to bedding document relatively late stage alteration of ancient sedimentary rocks at Meridiani Planum, Mars. The chemistry of submillimeter thick, buff-colored veneers reflects multiple processes at work since the establishment of the current plains surface. Veneer composition is dominated by the mixing of silicate-rich dust and sulfate-rich outcrop surface, but it has also been influenced by mineral precipitation, including NaCl, and possibly by limited physical or chemical weathering of sulfate minerals. Competing processes of chemical alteration (perhaps mediated by thin films of water or water vapor beneath blanketing soils) and sandblasting of exposed outcrop surfaces determine the current distribution of veneers. Dark-toned rinds several millimeters thick reflect more extensive surface alteration but also indicate combined dust admixture, halite precipitation, and possible minor sulfate removal. Cemented fracture fills that are differentially resistant to erosion occur along the margins of linear fracture systems possibly related to impact. These appear to reflect limited groundwater activity along the margins of fractures, cementing mechanically introduced fill derived principally from outcrop rocks. The limited thickness and spatial distribution of these three features suggest that aqueous activity has been rare and transient or has operated at exceedingly low rates during the protracted interval since outcropping Meridiani strata were exposed on the plains surface. Copyright 2008 by the American Geophysical Union.

Ground water resources of southeastern Oakland County, Michigan

USGS Publications Warehouse

Ferris, J.G.; Burt, E.M.; Stramel, G.J.; Crosthwaite, E.G.

1954-01-01

The area covered by this report comprises a square which measures three townships on a side and enclose 318 square miles in southeastern Oakland County. The investigation of the ground-water resources of this area was made by the U.S. Geological Survey in cooperation with the Detroit Metropolitan Area Regional Planning Commission, the Michigan Department of Conservation, and the Michigan Water Resources Commission.In 1950 the population of this nine-township area exceeded 341,000, or more than 86 percent of the total population of Oakland County. This county ranks third in the state in number of industrial establishments and workers and is fifteenth in agricultural importance. Its numerous lakes and rolling uplands contribute to its top rank in the state in the number of recreational enterprises in rural or suburban areas.The climate is moderately humid. The average annual precipitation is 30 inches and the mean air temperature is 47.2° F. Snowfall averages 38 inches in the November-April interval. The growing season averages 151 days.The regional land surface slopes from northwest to southeast and has a total relief of 360 feet. Pitted outwash plains and morainal hills that are more than 1,000 feet above sea level in the northwest corner of the area give way southeastward to a sequence of terminal moraines and intervening till plains in the middle part. These give way to the broad lake plains that cover the southeastern third of the area.The area lies on the southeast edge of the Michigan Basin and the bedrock is composed of northwest dipping strata of the Devonian and Mississippian systems. The Antrim shale, of Lake Devonian and early Mississippian age, is the oldest formation cropping out beneath the mantle of glacial Berea sandstone, and Sunbury shale overlie the Antrim and are overlain by the Coldwater shale, their areas of outcrop beneath the drift lying successively farther northwest. These formations are of early Mississippian age.Throughout the area the bedrock is covered by glacial drift which ranges in thickness from 25 to more than 350 feet. The drift increases in thickness from southeast to northwest, but considerable relief on the underlying bedrock surface greatly modifies this trend. Extensive moraines, till plains, lake plains, and gravel outwash plains cover the area. In the northwestern third of the area an extensive upland of gravel plains is dotted with lakes ranging from a few feet to more than 100 feet in depth.Precipitation is the perennial source of all water in this area, whether on the surface of underground. The average annual rainfall on the nine-townships is equivalent to a continuous supply of 450 m.g.d. or  9 times the combined annual withdrawal from all wells in the area.About 53 percent of the area is drained by the Clinton River, 44 percent by the River Rouge, and the remaining 3 percent by the Huron River. Less than one-third of the annual precipitation reappears as surface discharge from the watersheds of this area.About two-thirds of the annual precipitation on the area is lost by evaporation from water and land surfaces and by transpirations from vegetative cover. A substantial part of this large annual water loss is from the many lakes and other exposed water surfaces and from contiguous lands where the depth to the water table is slight. Average annual water losses by evapotranspiration are equivalent to about 280 m.g.d. or nearly 6 times the combined withdrawal from all ground-water supplies in the area.The principal aquifers are the alluvial deposits bordering streams and the buried outwash deposits which represent alluvial fills in preglacial or interglacial stream channels. Intensive well developments in the urban areas have greatly lowered ground-water levels in the buried outwash deposits, have brought localized problems of declining well yield, and have induced migration of mineralized waters from the underlying consolidated formations. During 1952, withdrawals of ground water in the nine township area averages about 50 m.g.d., most of this quantity being pumped from municipal wells. This annual pumpage was distributed as follows: 60 percent in Pontiac and environs; 20 percent in Birmingham, Royal Oak and Troy Township; and the remaining 20 percent throughout the suburban and rural areas.

Mechanistic Insights on the Photosensitized Chemistry of a Fatty Acid at the Air/Water Interface

PubMed Central

2016-01-01

Interfaces are ubiquitous in the environment and many atmospheric key processes, such as gas deposition, aerosol, and cloud formation are, at one stage or another, strongly impacted by physical and chemical processes occurring at interfaces. Here, the photoinduced chemistry of an air/water interface coated with nonanoic acid—a fatty acid surfactant we use as a proxy for chemically complex natural aqueous surface microlayers—was investigated as a source of volatile and semivolatile reactive organic species. The carboxylic acid coating significantly increased the propensity of photosensitizers, chosen to mimic those observed in real environmental waters, to partition to the interface and enhance reactivity there. Photochemical formation of functionalized and unsaturated compounds was systematically observed upon irradiation of these coated surfaces. The role of a coated interface appears to be critical in providing a concentrated medium allowing radical–radical reactions to occur in parallel with molecular oxygen additions. Mechanistic insights are provided from extensive analysis of products observed in both gas and aqueous phases by online switchable reagent ion-time of flight-mass spectrometry and by off-line ultraperformance liquid chromatography coupled to a Q Exactive high resolution mass spectrometer through heated electrospray ionization, respectively. PMID:27611489

Possibility of accommodation in a satellite Europe

NASA Astrophysics Data System (ADS)

Steklov, A. F.; Vidmachenko, A. P.

2018-05-01

It is believed that the presence of liquid water below the surface makes the satellite one of the most probable potential targets in Solar system, suitable for finding life there. Taking into account the fact that the radiation of Jupiter and Sun constantly affects Europe, free oxygen and a number of other oxidants are formed in the ice. In the old days, it was active oxygen led to the emergence of multicellular life on Earth. Now we know that the oceans of Europe contain much more oxygen than previously thought. And this increases the likelihood of the existence of life in Europe. In 2010 it was pointed out the possibility of the existence in ice of Europe of extensive lenses with liquid water, whose composition is significantly different from the composition of water in the ocean. This provides a mechanism for the possible transfer of vital chemicals created in the sunlit areas on the surface, and near of it in deeper layers. That is, such lakes can be another potential place of habitations. Thus, the subsurface ocean and lakes of Europe should be considered one of the best places for the existence of some forms of life.

Blowing bubbles in Lennard-Jonesium along the saturation curve.

PubMed

Ashbaugh, Henry S

2009-05-28

Extensive molecular simulations of the Lennard-Jones fluid have been performed to determine its liquid-vapor coexistence properties and solvent contact densities with cavities up to ten times the diameter of the solvent from the triple point to the critical point. These simulations are analyzed using a revised scaled-particle theory [H. S. Ashbaugh and L. R. Pratt, Rev. Mod. Phys. 78, 159 (2006)] to evaluate the thermodynamics of cavity solvation and curvature dependent interfacial properties along the saturation curve. While the thermodynamic signatures of cavity solvation are distinct from those in water, exhibiting a chemical potential dominated by a large temperature independent enthalpy, the solvent dewets cavities of increasing size similar with water near coexistence. The interfacial tension for forming a liquid-wall interface is found to be consistently greater than the liquid-vapor surface tension of the Lennard-Jones fluid by up to 10% and potentially reflects the suppression of high amplitude fluctuations at the cavity surface. The first-order curvature correction for the surface tension is negative and appears to diverge to negative infinity at temperatures approaching the critical point. Our results point to the success of the revised scaled-particle theory at bridging molecular and macroscopic descriptions of cavity solvation.

Mars atmosphere studies with the SPICAM IR emission phase function observations

NASA Astrophysics Data System (ADS)

Trokhimovskiy, Alexander; Fedorova, Anna; Montmessin, Franck; Korablev, Oleg; Bertaux, Jean-Loup

Emission Phase Function (EPF) observations is a powerful tool for characterization of atmosphere and surface. EPF sequence provides the extensive coverage of scattering angles above the targeted surface location which allow to separate the surface and aerosol scattering, study a vertical distribution of minor species and aerosol properties. SPICAM IR instrument on Mars Express mission provides continuous atmospheric observations in near IR (1-1.7 mu) in nadir and limb starting from 2004. For the first years of SPICAM operation only a very limited number of EPFs was performed. But from the mid 2013 (Ls=225, MY31) SPICAM EPF observations become rather regular. Based on the multiple-scattering radiative transfer model SHDOM, we analyze equivalent depths of carbon dioxide (1,43 mu) and water vapour (1,38 mu) absorption bands and their dependence on airmass during observation sequence to get aerosol optical depths and properties. The derived seasonal dust opacities from near IR can be used to retrieve the size distribution from comparison with simultaneous results of other instruments in different spectral ranges. Moreover, the EPF observations of water vapour band allow to access poorly known H2O vertical distribution for different season and locations.

A Framework to Evaluate the Impact of Armourstones on the Chemical Quality of Surface Water.

PubMed

Duester, Lars; Wahrendorf, Dierk-Steffen; Brinkmann, Corinna; Fabricius, Anne-Lena; Meermann, Björn; Pelzer, Juergen; Ecker, Dennis; Renner, Monika; Schmid, Harald; Ternes, Thomas A; Heininger, Peter

2017-01-01

Today, basic requirements for construction works include the protection of human health and of the environment. In the tension area between economic demands, circular flow economy and environmental safety, a link between the results from standardized leaching tests and the respective environmental quality standards must be created. To derive maximum release limits of metals and metalloids for armourstones in hydraulic engineering, this link is accomplished via a simple model approach. By treating natural materials and industrial by-products the same way, the article delivers an overview on the recent regulative situation in Europe as well as describes and discusses an innovative approach to derive maximum release limits for monolithic construction products in hydraulic engineering on a conceptual level. On a practical level, a list of test parameters is derived by connecting an extensive dataset (seven armourstone materials with five repetitions and 31 elements tested with the worldwide applied dynamic surface leaching test) with surface water quality standards and predicted no effect concentrations. Finally, the leaching tests results are compared with the envisaged maximum release limits, offering a direct comparison between natural materials and industrial by-products.

Development of a carbonate platform with potential for large discoveries - an example from Vietnam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mayall, M.; Bent, A.; Dale, B.

1996-01-01

In offshore central and southern Vietnam a number of carbonate accumulations can be recognized. Platform carbonates form basin-wide units of carbonate characterized by strong, continuous parallel seismic reflectors. Facies are dominated by bioclastic wackestones with poor-moderate reservoir quality. On the more isolated highs, large buildups developed. These are typically 5-10 km across and 300 m thick. They unconformably overlie the platform carbonate facies which are extensively karstified. In places these are pinnacles, typically 2-5 km across, 300 m+ thick with chaotic or mounded internal seismic facies. The large carbonate buildups are characterized by steep sided slopes with talus cones, reef-marginmore » rims usually developed around only part of the buildup, and a prominent back-stepping geometry. Buildup interior facies form the main potential reservoirs They are dominated by fine to coarse grained coralgal packstones. Fine grained carbonates are associated with deeper water events and multiple karst surfaces can also be identified. Reservoir quality is excellent, largely controlled by extensive dissolution and dolomitization believed to be related to the exposure events. Gas has been found in a number of reservoirs. Heterogeneities can be recognized which could potentially effect production. These include the extensive finer grained facies, cementation or open fissures associated with the karst surfaces, a more cemented reef rim, shallowing upwards facies cycles and faults.« less

Development of a carbonate platform with potential for large discoveries - an example from Vietnam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mayall, M.; Bent, A.; Dale, B.

1996-12-31

In offshore central and southern Vietnam a number of carbonate accumulations can be recognized. Platform carbonates form basin-wide units of carbonate characterized by strong, continuous parallel seismic reflectors. Facies are dominated by bioclastic wackestones with poor-moderate reservoir quality. On the more isolated highs, large buildups developed. These are typically 5-10 km across and 300 m thick. They unconformably overlie the platform carbonate facies which are extensively karstified. In places these are pinnacles, typically 2-5 km across, 300 m+ thick with chaotic or mounded internal seismic facies. The large carbonate buildups are characterized by steep sided slopes with talus cones, reef-marginmore » rims usually developed around only part of the buildup, and a prominent back-stepping geometry. Buildup interior facies form the main potential reservoirs They are dominated by fine to coarse grained coralgal packstones. Fine grained carbonates are associated with deeper water events and multiple karst surfaces can also be identified. Reservoir quality is excellent, largely controlled by extensive dissolution and dolomitization believed to be related to the exposure events. Gas has been found in a number of reservoirs. Heterogeneities can be recognized which could potentially effect production. These include the extensive finer grained facies, cementation or open fissures associated with the karst surfaces, a more cemented reef rim, shallowing upwards facies cycles and faults.« less

A significant reduction of ice adhesion on nanostructured surfaces that consist of an array of single-walled carbon nanotubes: A molecular dynamics simulation study

NASA Astrophysics Data System (ADS)

Bao, Luyao; Huang, Zhaoyuan; Priezjev, Nikolai V.; Chen, Shaoqiang; Luo, Kai; Hu, Haibao

2018-04-01

It is well recognized that excessive ice accumulation at low-temperature conditions can cause significant damage to civil infrastructure. The passive anti-icing surfaces provide a promising solution to suppress ice nucleation and enhance ice removal. However, despite extensive efforts, it remains a challenge to design anti-icing surfaces with low ice adhesion. Using all-atom molecular dynamics (MD) simulations, we show that surfaces with single-walled carbon nanotube array (CNTA) significantly reduce ice adhesion due to the extremely low solid areal fraction. It was found that the CNTA surface exhibits up to a 45% decrease in the ice adhesion strength in comparison with the atomically smooth graphene surface. The details of the ice detachment from the CNTA surface were examined for different water-carbon interaction energies and temperatures of the ice cube. Remarkably, the results of MD simulations demonstrate that the ice detaching strength depends linearly on the ratio of the ice-surface interaction energy and the ice temperature. These results open the possibility for designing novel robust surfaces with low ice adhesion for passive anti-icing applications.

Groundwater mining of bedrock aquifers in the Denver Basin - Past, present, and future

USGS Publications Warehouse

Moore, J.E.; Raynolds, R.G.; Barkmann, P.E.

2004-01-01

The Denver Basin bedrock aquifer system is an important source of water for municipal and agricultural uses in the Denver and Colorado Springs metropolitan areas. The Denver area is one of the fastest growing areas in the United States with a population of 1.2 million in 1960 that has increased to over 2.4 million by 2000. This rapid population growth has produced a corresponding increase in demand for potable water. Historically, the Denver area has relied on surface water, however, in the past 10 years new housing and recreation developments have begun to rely on groundwater from the bedrock aquifers as the surface water is fully appropriated and in short supply. The Denver Basin bedrock aquifer system consists of Tertiary and Cretaceous age sedimentary rocks known as the Dawson, Denver, Arapahoe and Laramie-Fox Hills Aquifers. The number of bedrock wells has increased from 12,000 in 1985 to 33,700 in 2001 and the withdrawal of groundwater has caused water level declines of 76 m. Water level declines for the past 10 years have ranged from 3 to 12 m per year. The groundwater supplies were once thought to last 100 years but there is concern that the groundwater supplies may be essentially depleted in 10 to 15 years in areas on the west side of the basin. Extensive development of the aquifer system has occurred in the last 25 years especially near the center of the basin in Douglas and El Paso Counties where rapid urban growth continues and surface water is lacking. Groundwater is being mined from the aquifer system because the discharge by wells exceeds the rate of recharge. Concern is mounting that increased groundwater withdrawal will cause water level declines, increased costs to withdraw groundwater, reduced well yield, and reduced groundwater storage. As the long-term sustainability of the groundwater resource is in doubt, water managers believe that the life of the Denver Basin aquifers can be extended with artificial recharge, water reuse, restrictions on lawn watering, well permit restrictions and conservation measures.

Impact of highway construction on land surface energy balance and local climate derived from LANDSAT satellite data.

PubMed

Nedbal, Václav; Brom, Jakub

2018-08-15

Extensive construction of highways has a major impact on the landscape and its structure. They can also influence local climate and heat fluxes in the surrounding area. After the removal of vegetation due to highway construction, the amount of solar radiation energy used for plant evapotranspiration (latent heat flux) decreases, bringing about an increase in landscape surface temperature, changing the local climate and increasing surface run-off. In this study, we evaluated the impact of the D8 highway construction (Central Bohemia, Czech Republic) on the distribution of solar radiation energy into the various heat fluxes (latent, sensible and ground heat flux) and related surface functional parameters (surface temperature and surface wetness). The aim was to describe the severity of the impact and the distance from the actual highway in which it can be observed. LANDSAT multispectral satellite images and field meteorological measurements were used to calculate surface functional parameters and heat balance before and during the highway construction. Construction of a four-lane highway can influence the heat balance of the landscape surface as far as 90m in the perpendicular direction from the highway axis, i.e. up to 75m perpendicular from its edge. During a summer day, the decrease in evapotranspired water can reach up to 43.7m 3 per highway kilometre. This means a reduced cooling effect, expressed as the decrease in latent heat flux, by an average of 29.7MWh per day per highway kilometre and its surroundings. The loss of the cooling ability of the land surface by evaporation can lead to a rise in surface temperature by as much as 7°C. Thus, the results indicate the impact of extensive line constructions on the local climate. Copyright © 2018 Elsevier B.V. All rights reserved.

Quantitative analysis on the urban flood mitigation effect by the extensive green roof system.

PubMed

Lee, J Y; Moon, H J; Kim, T I; Kim, H W; Han, M Y

2013-10-01

Extensive green-roof systems are expected to have a synergetic effect in mitigating urban runoff, decreasing temperature and supplying water to a building. Mitigation of runoff through rainwater retention requires the effective design of a green-roof catchment. This study identified how to improve building runoff mitigation through quantitative analysis of an extensive green-roof system. Quantitative analysis of green-roof runoff characteristics indicated that the extensive green roof has a high water-retaining capacity response to rainfall of less than 20 mm/h. As the rainfall intensity increased, the water-retaining capacity decreased. The catchment efficiency of an extensive green roof ranged from 0.44 to 0.52, indicating reduced runoff comparing with efficiency of 0.9 for a concrete roof. Therefore, extensive green roofs are an effective storm water best-management practice and the proposed parameters can be applied to an algorithm for rainwater-harvesting tank design. © 2013 Elsevier Ltd. All rights reserved.

Accurate green water loads calculation using naval hydro pack

NASA Astrophysics Data System (ADS)

Jasak, H.; Gatin, I.; Vukčević, V.

2017-12-01

An extensive verification and validation of Finite Volume based CFD software Naval Hydro based on foam-extend is presented in this paper for green water loads. Two-phase numerical model with advanced methods for treating the free surface is employed. Pressure loads on horizontal deck of Floating Production Storage and Offloading vessel (FPSO) model are compared to experimental results from [1] for three incident regular waves. Pressure peaks and integrals of pressure in time are measured on ten different locations on deck for each case. Pressure peaks and integrals are evaluated as average values among the measured incident wave periods, where periodic uncertainty is assessed for both numerical and experimental results. Spatial and temporal discretization refinement study is performed providing numerical discretization uncertainties.

Efficient Approaches for Propagating Hydrologic Forcing Uncertainty: High-Resolution Applications Over the Western United States

NASA Astrophysics Data System (ADS)

Hobbs, J.; Turmon, M.; David, C. H.; Reager, J. T., II; Famiglietti, J. S.

2017-12-01

NASA's Western States Water Mission (WSWM) combines remote sensing of the terrestrial water cycle with hydrological models to provide high-resolution state estimates for multiple variables. The effort includes both land surface and river routing models that are subject to several sources of uncertainty, including errors in the model forcing and model structural uncertainty. Computational and storage constraints prohibit extensive ensemble simulations, so this work outlines efficient but flexible approaches for estimating and reporting uncertainty. Calibrated by remote sensing and in situ data where available, we illustrate the application of these techniques in producing state estimates with associated uncertainties at kilometer-scale resolution for key variables such as soil moisture, groundwater, and streamflow.

Highly fluorescent carbon quantum dots as nanoprobes for sensitive and selective determination of mercury (II) in surface waters

NASA Astrophysics Data System (ADS)

Hua, Jianhao; Yang, Jian; Zhu, Yan; Zhao, Chunxi; Yang, Yaling

2017-12-01

A novel carbon quantum dots (CQDs) was successfully prepared through one-step green hydrothermal method using polyacrylamide as carbon source. The prepared CQDs were characterized using TEM, XRD, XPS, FT-IR, UV-Vis, and fluorescence spectroscopy. The CQDs was demonstrated as nanoprobes for mercury ion detection, moreover, it demonstrated excitation-dependent and superior stability in acidic and alkaline media. Besides, the probe exhibited a good linearity range (0.25-50 μM) and a low detection limit (13.48 nM). These attractive properties indicated that this novel CQDs can adapt to a variety of complex pH environment, which had extensive prospect and promising application for detection of mercury ions in complex water samples.

Improvement and extension of a radar forest backscattering model

NASA Technical Reports Server (NTRS)

Simonett, David S.; Wang, Yong

1989-01-01

Radar modeling of mangal forest stands, in the Sundarbans area of Southern Bangladesh, was developed. The modeling employs radar system parameters with forest data on tree height, spacing, biomass, species combinations, and water (including slightly conductive water), content both in leaves and trunks of the mangal. For Sundri and Gewa tropical mangal forests, six model components are proposed, which are required to explain the contributions of various forest species combinations in the attenuation and scattering of mangal vegetated nonflooded or flooded surfaces. Statistical data of simulated images were compared with those of SIR-B images both to refine the modeling procedures and to appropriately characterize the model output. The possibility of delineation of flooded or nonflooded boundaries is discussed.

Sensors and OBIA synergy for operational monitoring of surface water

NASA Astrophysics Data System (ADS)

Masson, Eric; Thenard, Lucas

2010-05-01

This contribution will focus on combining Object Based Image Analysis (i.e. OBIA with e-Cognition 8) and recent sensors (i.e. Spot 5 XS, Pan and ALOS Prism, Avnir2, Palsar) to address the technical feasibility for an operational monitoring of surface water. Three cases of river meandering (India), flood mapping (Nepal) and dam's seasonal water level monitoring (Morocco) using recent sensors will present various application of surface water monitoring. The operational aspect will be demonstrated either by sensor properties (i.e. spatial resolution and bandwidth), data acquisition properties (i.e. multi sensor, return period and near real-time acquisition) but also with OBIA algorithms (i.e. fusion of multi sensors / multi resolution data and batch processes). In the first case of river meandering (India) we will address multi sensor and multi date satellite acquisition to monitor the river bed mobility within a floodplain using an ALOS dataset. It will demonstrate the possibility of an operational monitoring system that helps the geomorphologist in the analysis of fluvial dynamic and sediment budget for high energy rivers. In the second case of flood mapping (Nepal) we will address near real time Palsar data acquisition at high spatial resolution to monitor and to map a flood extension. This ALOS sensor takes benefit both from SAR and L band properties (i.e. atmospheric transparency, day/night acquisition, low sensibility to surface wind). It's a real achievement compared to optical imagery or even other high resolution SAR properties (i.e. acquisition swath, bandwidth and data price). These advantages meet the operational needs set by crisis management of hydrological disasters but also for the implementation of flood risk management plans. The last case of dam surface water monitoring (Morocco) will address an important issue of water resource management in countries affected by water scarcity. In such countries water users have to cope with over exploitation, frequent drought period and now with foreseen climate change impacts. This third case will demonstrate the efficiency of SPOT 5 programming in synergy with OBIA methodology to assess the evolution of dam surface water within a complete water cycle (i.e. 2008-09). In all those three cases image segmentation and classification algorithms developed with e-Cognition 8 software allow an easy to use implementation of simple to highly sophisticate OBIA rulsets fully operational in batch processes. Finally this contribution foresees the new opportunity of integration of Worldview 2 multispectral imagery (i.e. 8 bands) including its "coastal" band that will also find an application in continental surface water bathymetry. Worldview 2 is a recently launch satellite (e.g. October 2009) that starts to collect earth observation data since January 2010. It is therefore a promising new remote sensing tool to develop operational hydrology in combination high resolution SAR imagery and OBIA methodology. This contribution will conclude on the strong potential for operationalisation in hydrology and water resources management that recent and future sensors and image analysis methodologies are offering to water management and decision makers.

On influencing factors of hypoxia in waters adjacent to the Changjiang estuary

NASA Astrophysics Data System (ADS)

Luo, Xiaofan; Wei, Hao; Fan, Renfu; Liu, Zhe; Zhao, Liang; Lu, Youyu

2018-01-01

Based on observational data from ten cruises carried out in 2012 and 2013, the distribution of dissolved oxygen (DO) and the evolution of hypoxia (DO concentrations < 2.0 mg L-1) in waters adjacent to the Changjiang estuary are studied. The linkage between summer hypoxia and hydrodynamic conditions is explored. The results suggest that hypoxia frequently occurred from June to October to the south of the Changjiang estuary near the 30-50 m isobaths and was prone to happening under strong stratification without the presence of the Kuroshio Subsurface Water (KSW). Over the Changjiang Bank, hypoxia mainly occurred in July, August and September. Low-oxygen areas initially appeared under strong stratification induced by the spreading of the Changjiang Diluted Water (CDW), and developed into hypoxic zones due to lack of DO replenishment from the relatively DO-rich Yellow Sea Water and the KSW. The yearly evolution of hypoxia was influenced by shelf circulation especially the path of the KSW in the bottom layer of the water to the south of the Changjiang estuary, and the extension of the CDW in the surface layer over the Changjiang Bank.

Susceptibility of ground water to surface and shallow sources of contamination in Mississippi

USGS Publications Warehouse

O'Hara, Charles G.

1996-01-01

Ground water, because of its extensive use in agriculture, industry, and public-water supply, is one of Mississippi's most important natural resources.  Ground water is the source for about 80 percent of the total freshwater used by the State's population (Solley and others, 1993).  About 2,600 Mgal/d of freshwater is withdrawn from aquifers in Mississippi (D.E. Burt, Jr., U.S. Geological Survey, oral commun., 1995).  Wells capable of yielding 200 gal/min of water with quality suitable for most uses can be developed nearly anywhere in the State (Bednar, 1988).  The U.S. Geological Survey (USGS), in cooperation with the Mississippi Department of Environmental Quality, Office of Pollution Control, and the Mississippi Department of Agriculture and Commerce, Bureau of Plant Industry, conducted an investigation to evaluate the susceptibility of ground water to contamination from surgace and shallow sources in Mississippi.  A geographic information system (GIS) was used to develop and analyze statewide spatial data layers that contain geologic, hydrologic, physiographic, and cultural information.

A mechanistic model for mercury capture with in situ-generated titania particles: role of water vapor.

PubMed

Rodríguez, Sylian; Almquist, Catherine; Lee, Tai Gyu; Furuuchi, Masami; Hedrick, Elizabeth; Biswas, Pratim

2004-02-01

A mechanistic model to predict the capture of gas-phase mercury (Hg) species using in situ-generated titania nanosize particles activated by UV irradiation is developed. The model is an extension of a recently reported model for photochemical reactions by Almquist and Biswas that accounts for the rates of electron-hole pair generation, the adsorption of the compound to be oxidized, and the adsorption of water vapor. The role of water vapor in the removal efficiency of Hg was investigated to evaluate the rates of Hg oxidation at different water vapor concentrations. As the water vapor concentration is increased, more hydroxy radical species are generated on the surface of the titania particle, increasing the number of active sites for the photooxidation and capture of Hg. At very high water vapor concentrations, competitive adsorption is expected to be important and reduce the number of sites available for photooxidation of Hg. The predictions of the developed phenomenological model agreed well with the measured Hg oxidation rates in this study and with the data on oxidation of organic compounds reported in the literature.

Water-Chemistry and Its Utility Systems in CCP Power Units (Review)

NASA Astrophysics Data System (ADS)

Larin, B. M.

2018-01-01

Damageability of heat transfer surfaces of waste heat recovery steam generators (HRSG) of combined- cycle plants (CCP) can be reduced due to an increase in the quality of make-up and feed water, the use of phosphate-alkaline or amino compound water chemistry (WC), and improved chemical quality control of the heat carrier and make-up water preparation techniques. Temporary quality standards for the heat medium developed by the All-Russia Thermal Engineering institute (VTI) for CCP power units are presented in comparison with the IAPWS standards; preferences for the choice of a WC type for some power units commissioned in Russia in the first decade of this century are shown; and operational data on the quality of feed, boiler water, and steam for two large CCP-450 and CCP-425 power units are given. The state and prospects for the development of chemical-technological monitoring systems and CCP water treatment plants are noted. Estimability of some CCP diagnostic parameters by measuring specific electric conductivity and pH is shown. An extensive bibliography on this topic is given.

Reconnaissance samplings and characterization of aquatic humic substances at the Yuma Desalting Test Facility, Arizona

USGS Publications Warehouse

Malcolm, R.L.; Wershaw, R. L.; Thurman, E.M.; Aiken, G.R.; Pinckney, D.J.; Kaakinen, J.

1981-01-01

Smectite clay minerals were found to be the principal compound on the surface of the cellulose-acetate, reverse-osmosis membranes at the Yuma Desalting Test Facility. These clay minerals were not present in the pumped ground water, but were blown into the conveyance canal from adjacent soils. Humic substances from the water and suspended sediments were associated with the clay films on the membrane, but no definitive results concerning their role in fouling were achieved. Microbial fouling is believed to be only a minor aspect of membrane fouling. Chemical and physical changes in humic substances were extensively studied at four points in the water-treatment process. Humic substances accounted for the largest component (over 25 percent) of organic constituents. Humic substances in the canal source water were similar to other aquatic humic substances present in natural waters. During the treatment process, these substances are brominated and decolorized. The effect of these halogenated humic substances on membrane fouling is unclear, but their presence in the reverse-osmosis product water and reverse-osmosis reject brine, along with volatile trihalomethanes, has led to environmental concerns. (USGS)

Possible Sea Ice Impacts on Oceanic Deep Convection

NASA Technical Reports Server (NTRS)

Parkinson, C. L.

1984-01-01

Many regions of the world ocean known or suspected to have deep convection are sea-ice covered for at least a portion of the annual cycle. As this suggests that sea ice might have some impact on generating or maintaining this phenomenon, several mechanisms by which sea ice could exert an influence are presented in the following paragraphs. Sea ice formation could be a direct causal factor in deep convection by providing the surface density increase necessary to initiate the convective overturning. As sea ice forms, either by ice accretion or by in situ ice formation in open water or in lead areas between ice floes, salt is rejected to the underlying water. This increases the water salinity, thereby increasing water density in the mixed layer under the ice. A sufficient increase in density will lead to mixing with deeper waters, and perhaps to deep convection or even bottom water formation. Observations are needed to establish whether this process is actually occurring; it is most likely in regions with extensive ice formation and a relatively unstable oceanic density structure.

Rapid hydraulic recovery in Eucalyptus pauciflora after drought: linkages between stem hydraulics and leaf gas exchange.

PubMed

Martorell, Sebastià; Diaz-Espejo, Antonio; Medrano, Hipólito; Ball, Marilyn C; Choat, Brendan

2014-03-01

In woody plants, photosynthetic capacity is closely linked to rates at which the plant hydraulic system can supply water to the leaf surface. Drought-induced embolism can cause sharp declines in xylem hydraulic conductivity that coincide with stomatal closure and reduced photosynthesis. Recovery of photosynthetic capacity after drought is dependent on restored xylem function, although few data exist to elucidate this coordination. We examined the dynamics of leaf gas exchange and xylem function in Eucalyptus pauciflora seedlings exposed to a cycle of severe water stress and recovery after re-watering. Stomatal closure and leaf turgor loss occurred at water potentials that delayed the extensive spread of embolism through the stem xylem. Stem hydraulic conductance recovered to control levels within 6 h after re-watering despite a severe drought treatment, suggesting an active mechanism embolism repair. However, stomatal conductance did not recover after 10 d of re-watering, effecting tighter control of transpiration post drought. The dynamics of recovery suggest that a combination of hydraulic and non-hydraulic factors influenced stomatal behaviour post drought. © 2013 John Wiley & Sons Ltd.

Evaluation of Millstone-2 steam generator chemical decontamination

DOE Office of Scientific and Technical Information (OSTI.GOV)

Snyder, D.T.; Blok, J.

The steam generator channel heads at Millstone-2 were decontaminated prior to carrying out extensive maintenance work in 1983. Isotopic gamma ray measurements were made of the inner channel head surfaces before and after the decontamination to evaluate the effectiveness of the process. The Combustion Engineering/Kraftwerk Union chemical decontamination, by itself, provided a decontamination factor ranging from 2.7 to 6.6 for the various steam generator surfaces. The corresponding average dose rate reduction factor, based on gross-gamma radiation surveys, was approximately 1.5 to 2.5. Following the chemical treatment, high pressure water flushing reduced the radiation levels still further, to an average overallmore » dose reduction factor of 5.3 to 7.2.« less

Five-year performance monitoring of a high-density polyethylene (HDPE) cover system at a reclaimed mine waste rock pile in the Sydney Coalfield (Nova Scotia, Canada).

PubMed

Power, Christopher; Ramasamy, Murugan; MacAskill, Devin; Shea, Joseph; MacPhee, Joseph; Mayich, David; Baechler, Fred; Mkandawire, Martin

2017-12-01

Cover systems are commonly placed over waste rock piles (WRPs) to limit atmospheric water and oxygen ingress and control the generation and release of acid mine drainage (AMD) to the receiving environment. Although covers containing geomembranes such as high-density polyethylene (HDPE) exhibit the attributes to be highly effective, there are few, if any, published studies monitoring their performance at full-scale WRPs. In 2011, a HDPE cover was installed over the Scotchtown Summit WRP in Nova Scotia, Canada, and extensive field performance monitoring was conducted over the next five years. A range of parameters within the atmosphere, cover, waste rock, groundwater and surface water, were monitored and integrated into a comprehensive hydrogeochemical conceptual model to assess (i) atmospheric ingress to the waste rock, (ii) waste rock acidity and depletion and (iii) evolution of groundwater and surface water quality. Results demonstrate that the cover is effective and meeting site closure objectives. Depletion in oxygen influx resulted in slower sulphide oxidation and AMD generation, while a significant reduction in water influx (i.e. 512 to 50 mm/year) resulted in diminished AMD release. Consistent improvements in groundwater quality (decrease in sulphate and metals; increase in pH) beneath and downgradient of the WRP were observed. Protection and/or significant improvement in surface water quality was evident in all surrounding watercourses due to the improved groundwater plume and elimination of contaminated runoff over previously exposed waste rock. A variably saturated flow and contaminant transport model is currently being developed to predict long-term cover system performance.

Partitioning groundwater recharge between rainfall infiltration and irrigation return flow using stable isotopes: The Crau aquifer

NASA Astrophysics Data System (ADS)

Séraphin, Pierre; Vallet-Coulomb, Christine; Gonçalvès, Julio

2016-11-01

This study reports an assessment of the water budget of the Crau aquifer (Southern France), which is poorly referenced in the literature. Anthropogenically controlled by a traditional irrigation practice, this alluvial type aquifer requires a robust quantification of the groundwater mass balance in order to establish sustainable water management in the region. In view of the high isotopic contrast between exogenous irrigation waters and local precipitations, stable isotopes of water can be used as conservative tracers to deduce their contributions to the surface recharge. Extensive groundwater sampling was performed to obtain δ18O and δ2H over the whole aquifer. Based on a new piezometric contour map, combined with an updated aquifer geometry, the isotopic data were implemented in a geostatistical approach to produce a conceptual equivalent homogeneous reservoir. This makes it possible to implement a parsimonious water and isotope mass-balance mixing model. The isotopic compositions of the two end-members were assessed, and the quantification of groundwater flows was then used to calculate the two recharge fluxes (natural and irrigation). Nearly at steady-state, the set of isotopic data treated by geostatistics gave a recharge by irrigation of 4.92 ± 0.89 m3 s-1, i.e. 1109 ± 202 mm yr-1, and a natural recharge of 2.19 ± 0.85 m3 s-1, i.e. 128 ± 50 mm yr-1. Thus, 69 ± 9% of the surface recharge is caused by irrigation return flow. This study constitutes a straightforward and independent approach to assess groundwater surface recharges including uncertainties and will help to constrain future transient groundwater models of the Crau aquifer.