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.

PAHs behavior in surface water and groundwater of the Yellow River estuary: Evidence from isotopes and hydrochemistry.

PubMed

Li, Jing; Li, Fadong; Liu, Qiang

2017-07-01

Large-scale irrigation projects have impacted the regional surface-groundwater interactions in the North China Plain (NCP). Given this concern, the aim of this study is to evaluate levels of PAH pollution, identify the sources of the PAHs, analyze the influence of surface-groundwater interactions on PAH distribution, and propose urgent management strategies for PAHs in China's agricultural areas. PAH concentrations, hydrochemical indicators and stable isotopic compositions (δ 18 O and δ 2 H) were determined for surface water (SW) and groundwater (GW) samples. PAHs concentrations in surface water and groundwater varied from 11.84 to 393.12 ng/L and 8.51-402.84 ng/L, respectively, indicating mild pollution. The seasonal variations showed the following trend: PAHs in surface water at the low-water phase > PAHs in groundwater at the low-water phase > PAHs in surface water at the high-water phase > PAHs in groundwater at the high-water phase. Hydrochemical and δ 18 O value of most groundwater samples distributed between the Yellow River and seawater. The mean value of mixture ratio of the Yellow River water recharge to the groundwater was 65%, few anomalous sites can reach to 90%. Surface-groundwater interactions influence the spatial distribution of PAHs in the study area. In light of the ongoing serious pollution, management practices for source control, improved control technologies, and the construction of a monitoring network to warn of increased risk are urgently needed. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Relationship between the Distribution of Common Carp and Their Environmental DNA in a Small Lake

PubMed Central

Eichmiller, Jessica J.; Bajer, Przemyslaw G.; Sorensen, Peter W.

2014-01-01

Although environmental DNA (eDNA) has been used to infer the presence of rare aquatic species, many facets of this technique remain unresolved. In particular, the relationship between eDNA and fish distribution is not known. We examined the relationship between the distribution of fish and their eDNA (detection rate and concentration) in a lake. A quantitative PCR (qPCR) assay for a region within the cytochrome b gene of the common carp (Cyprinus carpio or ‘carp’), an ubiquitous invasive fish, was developed and used to measure eDNA in Lake Staring (MN, USA), in which both the density of carp and their distribution have been closely monitored for several years. Surface water, sub-surface water, and sediment were sampled from 22 locations in the lake, including areas frequently used by carp. In water, areas of high carp use had a higher rate of detection and concentration of eDNA, but there was no effect of fish use on sediment eDNA. The detection rate and concentration of eDNA in surface and sub-surface water were not significantly different (p≥0.5), indicating that eDNA did not accumulate in surface water. The detection rate followed the trend: high-use water > low-use water > sediment. The concentration of eDNA in sediment samples that were above the limit of detection were several orders of magnitude greater than water on a per mass basis, but a poor limit of detection led to low detection rates. The patchy distribution of eDNA in the water of our study lake suggests that the mechanisms that remove eDNA from the water column, such as decay and sedimentation, are rapid. Taken together, these results indicate that effective eDNA sampling methods should be informed by fish distribution, as eDNA concentration was shown to vary dramatically between samples taken less than 100 m apart. PMID:25383965

The relationship between the distribution of common carp and their environmental DNA in a small lake.

PubMed

Eichmiller, Jessica J; Bajer, Przemyslaw G; Sorensen, Peter W

2014-01-01

Although environmental DNA (eDNA) has been used to infer the presence of rare aquatic species, many facets of this technique remain unresolved. In particular, the relationship between eDNA and fish distribution is not known. We examined the relationship between the distribution of fish and their eDNA (detection rate and concentration) in a lake. A quantitative PCR (qPCR) assay for a region within the cytochrome b gene of the common carp (Cyprinus carpio or 'carp'), an ubiquitous invasive fish, was developed and used to measure eDNA in Lake Staring (MN, USA), in which both the density of carp and their distribution have been closely monitored for several years. Surface water, sub-surface water, and sediment were sampled from 22 locations in the lake, including areas frequently used by carp. In water, areas of high carp use had a higher rate of detection and concentration of eDNA, but there was no effect of fish use on sediment eDNA. The detection rate and concentration of eDNA in surface and sub-surface water were not significantly different (p≥0.5), indicating that eDNA did not accumulate in surface water. The detection rate followed the trend: high-use water > low-use water > sediment. The concentration of eDNA in sediment samples that were above the limit of detection were several orders of magnitude greater than water on a per mass basis, but a poor limit of detection led to low detection rates. The patchy distribution of eDNA in the water of our study lake suggests that the mechanisms that remove eDNA from the water column, such as decay and sedimentation, are rapid. Taken together, these results indicate that effective eDNA sampling methods should be informed by fish distribution, as eDNA concentration was shown to vary dramatically between samples taken less than 100 m apart.

Water Cycling in the North Polar Region of Mars

NASA Technical Reports Server (NTRS)

Tamppari, L. K.; Smith, M. D.; Bass, D. S.

2003-01-01

To date, there has been no comprehensive study to understand the partitioning of water into vapor and ice clouds, and the associated effects of dust and surface temperature in the north polar region. Ascertaining the degree to which water is transported out of the cap region versus within the cap region will give much needed insight into the overall story of water cycling on a seasonal basis. In particular, understanding the mechanism for the polar cap surface albedo changes would go along way in comprehending the sources and sinks of water in the northern polar region. We approach this problem by examining Thermal Emission Spectrometer (TES) atmospheric and surface data acquired in the northern summer season and comparing it to Viking data when possible. Because the TES instrument spans the absorption bands of water vapor, water ice, dust, and measures surface temperature, all three aerosols and surface temperature can be retrieved simultaneously. This presentation will show our latest results on the water vapor, water-ice clouds seasonal and spatial distributions, as well as surface temperatures and dust distribution which may lend insight into where the water is going.

The nitrate response of a lowland catchment and groundwater travel times

NASA Astrophysics Data System (ADS)

van der Velde, Ype; Rozemeijer, Joachim; de Rooij, Gerrit; van Geer, Frans

2010-05-01

Intensive agriculture in lowland catchments causes eutrophication of downstream waters. To determine effective measures to reduce the nutrient loads from upstream lowland catchments, we need to understand the origin of long-term and daily variations in surface water nutrient concentrations. Surface water concentrations are often linked to travel time distributions of water passing through the saturated and unsaturated soil of the contributing catchment. This distribution represents the contact time over which sorption, desorption and degradation takes place. However, travel time distributions are strongly influenced by processes like tube drain flow, overland flow and the dynamics of draining ditches and streams and therefore exhibit strong daily and seasonal variations. The study we will present is situated in the 6.6 km2 Hupsel brook catchment in The Netherlands. In this catchment nitrate and chloride concentrations have been intensively monitored for the past 26 years under steadily decreasing agricultural inputs. We described the complicated dynamics of subsurface water fluxes as streams, ditches and tube drains locally switch between active or passive depending on the ambient groundwater level by a groundwater model with high spatial and temporal resolutions. A transient particle tracking approach is used to derive a unique catchment-scale travel time distribution for each day during the 26 year model period. These transient travel time distributions are not smooth distributions, but distributions that are strongly spiked reflecting the contribution of past rainfall events to the current discharge. We will show that a catchment-scale mass response function approach that only describes catchment-scale mixing and degradation suffices to accurately reproduce observed chloride and nitrate surface water concentrations as long as the mass response functions include the dynamics of travel time distributions caused by the highly variable connectivity of the surface water network.

Assessing the influence of climate change and inter-basin water diversion on Haihe River basin, eastern China: a coupled model approach

NASA Astrophysics Data System (ADS)

Xia, Jun; Wang, Qiang; Zhang, Xiang; Wang, Rui; She, Dunxian

2018-04-01

The modeling of changes in surface water and groundwater in the areas of inter-basin water diversion projects is quite difficult because surface water and groundwater models are run separately most of the time and the lack of sufficient data limits the application of complex surface-water/groundwater coupling models based on physical laws, especially for developing countries. In this study, a distributed surface-water and groundwater coupling model, named the distributed time variant gain model-groundwater model (DTVGM-GWM), was used to assess the influence of climate change and inter-basin water diversion on a watershed hydrological cycle. The DTVGM-GWM model can reflect the interaction processes of surface water and groundwater at basin scale. The model was applied to the Haihe River Basin (HRB) in eastern China. The possible influences of climate change and the South-to-North Water Diversion Project (SNWDP) on surface water and groundwater in the HRB were analyzed under various scenarios. The results showed that the newly constructed model DTVGM-GWM can reasonably simulate the surface and river runoff, and describe the spatiotemporal distribution characteristics of groundwater level, groundwater storage and phreatic recharge. The prediction results under different scenarios showed a decline in annual groundwater exploitation and also runoff in the HRB, while an increase of groundwater storage and groundwater level after the SNWDP's operation. Additionally, as the project also addresses future scenarios, a slight increase is predicted in the actual evapotranspiration, soil water content and phreatic recharge. This study provides valuable insights for developing sustainable groundwater management options for the HRB.

Safe drinking water and waterborne outbreaks.

PubMed

Moreira, N A; Bondelind, M

2017-02-01

The present work compiles a review on drinking waterborne outbreaks, with the perspective of production and distribution of microbiologically safe water, during 2000-2014. The outbreaks are categorised in raw water contamination, treatment deficiencies and distribution network failure. The main causes for contamination were: for groundwater, intrusion of animal faeces or wastewater due to heavy rain; in surface water, discharge of wastewater into the water source and increased turbidity and colour; at treatment plants, malfunctioning of the disinfection equipment; and for distribution systems, cross-connections, pipe breaks and wastewater intrusion into the network. Pathogens causing the largest number of affected consumers were Cryptosporidium, norovirus, Giardia, Campylobacter, and rotavirus. The largest number of different pathogens was found for the treatment works and the distribution network. The largest number of affected consumers with gastrointestinal illness was for contamination events from a surface water source, while the largest number of individual events occurred for the distribution network.

Data catalog for JPL Physical Oceanography Distributed Active Archive Center (PO.DAAC)

NASA Technical Reports Server (NTRS)

Digby, Susan

1995-01-01

The Physical Oceanography Distributed Active Archive Center (PO.DAAC) archive at the Jet Propulsion Laboratory contains satellite data sets and ancillary in-situ data for the ocean sciences and global-change research to facilitate multidisciplinary use of satellite ocean data. Geophysical parameters available from the archive include sea-surface height, surface-wind vector, surface-wind speed, surface-wind stress vector, sea-surface temperature, atmospheric liquid water, integrated water vapor, phytoplankton pigment concentration, heat flux, and in-situ data. PO.DAAC is an element of the Earth Observing System Data and Information System and is the United States distribution site for TOPEX/POSEIDON data and metadata.

Detecting surface runoff location in a small catchment using distributed and simple observation method

NASA Astrophysics Data System (ADS)

Dehotin, Judicaël; Breil, Pascal; Braud, Isabelle; de Lavenne, Alban; Lagouy, Mickaël; Sarrazin, Benoît

2015-06-01

Surface runoff is one of the hydrological processes involved in floods, pollution transfer, soil erosion and mudslide. Many models allow the simulation and the mapping of surface runoff and erosion hazards. Field observations of this hydrological process are not common although they are crucial to evaluate surface runoff models and to investigate or assess different kinds of hazards linked to this process. In this study, a simple field monitoring network is implemented to assess the relevance of a surface runoff susceptibility mapping method. The network is based on spatially distributed observations (nine different locations in the catchment) of soil water content and rainfall events. These data are analyzed to determine if surface runoff occurs. Two surface runoff mechanisms are considered: surface runoff by saturation of the soil surface horizon and surface runoff by infiltration excess (also called hortonian runoff). The monitoring strategy includes continuous records of soil surface water content and rainfall with a 5 min time step. Soil infiltration capacity time series are calculated using field soil water content and in situ measurements of soil hydraulic conductivity. Comparison of soil infiltration capacity and rainfall intensity time series allows detecting the occurrence of surface runoff by infiltration-excess. Comparison of surface soil water content with saturated water content values allows detecting the occurrence of surface runoff by saturation of the soil surface horizon. Automatic records were complemented with direct field observations of surface runoff in the experimental catchment after each significant rainfall event. The presented observation method allows the identification of fast and short-lived surface runoff processes at a small spatial and temporal resolution in natural conditions. The results also highlight the relationship between surface runoff and factors usually integrated in surface runoff mapping such as topography, rainfall parameters, soil or land cover. This study opens interesting prospects for the use of spatially distributed measurement for surface runoff detection, spatially distributed hydrological models implementation and validation at a reasonable cost.

Synoptic thermal and oceanographic parameter distributions in the New York Bight Apex

NASA Technical Reports Server (NTRS)

Johnson, R. W.; Bahn, G. S.; Thomas, J. P.

1981-01-01

Concurrent surface water measurements made from a moving oceanographic research vessel were used to calibrate and interpret remotely sensed data collected over a plume in the New York Bight Apex on 23 June 1977. Multiple regression techniques were used to develop equations to map synoptic distributions of chlorophyll a and total suspended matter in the remotely sensed scene. Thermal (which did not have surface calibration values) and water quality parameter distributions indicated a cold mass of water in the Bight Apex with an overflowing nutrient-rich warm water plume that originated in the Sandy Hook Bay and flowed south near the New Jersey shoreline. Data analysis indicates that remotely sensed data may be particularly useful for studying physical and biological processes in the top several metres of surface water at plume boundaries.

CHANGES IN BACTERIAL COMPOSITION OF BIOFILM IN A METROPOLITAN DRINKING WATER DISTRIBUTION SYSTEM

EPA Science Inventory

This study examined the development of bacterial biofilms within a metropolitan distribution system. The distribution system is fed with different source water (i.e., groundwater, GW and surface water, SW) and undergoes different treatment processes in separate facilities. The b...

Spatially variable stage-driven groundwater-surface water interaction inferred from time-frequency analysis of distributed temperature sensing data

USGS Publications Warehouse

Mwakanyamale, Kisa; Slater, Lee; Day-Lewis, Frederick D.; Elwaseif, Mehrez; Johnson, Carole D.

2012-01-01

Characterization of groundwater-surface water exchange is essential for improving understanding of contaminant transport between aquifers and rivers. Fiber-optic distributed temperature sensing (FODTS) provides rich spatiotemporal datasets for quantitative and qualitative analysis of groundwater-surface water exchange. We demonstrate how time-frequency analysis of FODTS and synchronous river stage time series from the Columbia River adjacent to the Hanford 300-Area, Richland, Washington, provides spatial information on the strength of stage-driven exchange of uranium contaminated groundwater in response to subsurface heterogeneity. Although used in previous studies, the stage-temperature correlation coefficient proved an unreliable indicator of the stage-driven forcing on groundwater discharge in the presence of other factors influencing river water temperature. In contrast, S-transform analysis of the stage and FODTS data definitively identifies the spatial distribution of discharge zones and provided information on the dominant forcing periods (≥2 d) of the complex dam operations driving stage fluctuations and hence groundwater-surface water exchange at the 300-Area.

The occurrence and distribution of a group of organic micropollutants in Mexico City's water sources.

PubMed

Félix-Cañedo, Thania E; Durán-Álvarez, Juan C; Jiménez-Cisneros, Blanca

2013-06-01

The occurrence and distribution of a group of 17 organic micropollutants in surface and groundwater sources from Mexico City was determined. Water samples were taken from 7 wells, 4 dams and 15 tanks where surface and groundwater are mixed and stored before distribution. Results evidenced the occurrence of seven of the target compounds in groundwater: salicylic acid, diclofenac, di-2-ethylhexylphthalate (DEHP), butylbenzylphthalate (BBP), triclosan, bisphenol A (BPA) and 4-nonylphenol (4-NP). In surface water, 11 target pollutants were detected: same found in groundwater as well as naproxen, ibuprofen, ketoprofen and gemfibrozil. In groundwater, concentration ranges of salicylic acid, 4-NP and DEHP, the most frequently found compounds, were 1-464, 1-47 and 19-232 ng/L, respectively; while in surface water, these ranges were 29-309, 89-655 and 75-2,282 ng/L, respectively. Eleven target compounds were detected in mixed water. Concentrations in mixed water were higher than those determined in groundwater but lower than the detected in surface water. Different to that found in ground and surface water, the pesticide 2,4-D was found in mixed water, indicating that some pollutants can reach areas where they are not originally present in the local water sources. Concentration of the organic micropollutants found in this study showed similar to lower to those reported in water sources from developed countries. This study provides information that enriches the state of the art on the occurrence of organic micropollutants in water sources worldwide, notably in megacities of developing countries. Copyright © 2013 Elsevier B.V. All rights reserved.

Silver disinfection in water distribution systems

NASA Astrophysics Data System (ADS)

Silvestry Rodriguez, Nadia

Silver was evaluated as disinfectant to maintain water quality in water distribution system. It was used to inhibit growth of two opportunistic bacteria in planktonik form and in biofilm formation in Robbins devices with stainless steel and PVC surfaces. The results of this work show that silver is a potential secondary disinfectant to be used in water distribution systems.

Mississippi Sound remote sensing study. [NASA Earth Resources Laboratory seasonal experiments

NASA Technical Reports Server (NTRS)

Atwell, B. H.; Thomann, G. C.

1973-01-01

A study of the Mississippi Sound was initiated in early 1971 by personnel of NASA Earth Resources Laboratory. Four separate seasonal experiments consisting of quasi-synoptic remote and surface measurements over the entire area were planned. Approximately 80 stations distributed throughout Mississippi Sound were occupied. Surface water temperature and secchi extinction depth were measured at each station and water samples were collected for water quality analyses. The surface distribution of three water parameters of interest from a remote sensing standpoint - temperature, salinity and chlorophyll content - are displayed in map form. Areal variations in these parameters are related to tides and winds. A brief discussion of the general problem of radiative measurements of water temperature is followed by a comparison of remotely measured temperatures (PRT-5) to surface vessel measurements.

JPL Physical Oceanography Distributed Active Archive Center (PO.DAAC) data availability, version 1-94

NASA Technical Reports Server (NTRS)

1994-01-01

The Physical Oceanography Distributed Active Archive Center (PO.DAAC) archive at the Jet Propulsion Laboratory (JPL) includes satellite data sets for the ocean sciences and global-change research to facilitate multidisciplinary use of satellite ocean data. Parameters include sea-surface height, surface-wind vector, sea-surface temperature, atmospheric liquid water, and integrated water vapor. The JPL PO.DAAC is an element of the Earth Observing System Data and Information System (EOSDIS) and is the United States distribution site for Ocean Topography Experiment (TOPEX)/POSEIDON data and metadata.

Airflow in Gravity Sewers - Determination of Wastewater Drag Coefficient.

PubMed

Bentzen, Thomas Ruby; Østertoft, Kristian Kilsgaard; Vollertsen, Jes; Fuglsang, Emil Dietz; Nielsen, Asbjørn Haaning

2016-03-01

Several experiments have been conducted in order to improve the understanding of the wastewater drag and the wall frictional force acting on the headspace air in gravity sewers. The aim of the study is to improve the data basis for a numerical model of natural sewer ventilation. The results of the study shows that by integrating the top/side wall shear stresses the log-law models for the air velocity distribution along the unwetted perimeter resulted in a good agreement with the friction forces calculated by use of the Colebrook-White formula for hydraulic smooth pipes. Secondly, the water surface drags were found by log-law models of the velocity distribution in turbulent flows to fit velocity profiles measured from the water surface and by integrating the water surface drags along the wetted perimeter, mean water surface drags were found and a measure of the water surface drag coefficient was found.

Characterization of water bodies for mosquito habitat using a multi-sensor approach

NASA Astrophysics Data System (ADS)

Midekisa, A.; Wimberly, M. C.; Senay, G. B.

2012-12-01

Malaria is a major health problem in Ethiopia. Anopheles arabiensis, which inhabits and breeds in a variety of aquatic habitats, is the major mosquito vector for malaria transmission in the region. In the Amhara region of Ethiopia, mosquito breeding sites are heterogeneously distributed. Therefore, accurate characterization of aquatic habitats and potential breeding sites can be used as a proxy to measure the spatial distribution of malaria risk. Satellite remote sensing provides the ability to map the spatial distribution and monitor the temporal dynamics of surface water. The objective of this study is to map the probability of surface water accumulation to identify potential vector breeding sites for Anopheles arabiensis using remote sensing data from sensors at multiple spatial and temporal resolutions. The normalized difference water index (NDWI), which is based on reflectance in the green and the near infrared (NIR) bands were used to estimate fractional cover of surface water. Temporal changes in surface water were mapped using NDWI indices derived from MODIS surface reflectance product (MOD09A1) for the period 2001-2012. Landsat TM and ETM+ imagery were used to train and calibrate model results from MODIS. Results highlighted interannual variation and seasonal changes in surface water that were observed from the MODIS time series. Static topographic indices that estimate the potential for water accumulation were generated from 30 meter Shuttle Radar Topography Mission (SRTM) elevation data. Integrated fractional surface water cover was developed by combining the static topographic indices and dynamic NDWI indices using Geographic Information System (GIS) overlay methods. Accuracy of the results was evaluated based on ground truth data that was collected on presence and absence of surface water immediately after the rainy season. The study provided a multi-sensor approach for mapping areas with a high potential for surface water accumulation that are potential breeding habitats for anopheline mosquitoes. The resulting products are useful for public health decision making towards effective prevention and control of the malaria burden in the Amhara region of Ethiopia.

Terrestrial water storage variations and surface vertical deformation derived from GPS and GRACE observations in Nepal and Himalayas

NASA Astrophysics Data System (ADS)

Pan, Y.; Shen, W.; Hwang, C.

2015-12-01

As an elastic Earth, the surface vertical deformation is in response to hydrological mass change on or near Earth's surface. The continuous GPS (CGPS) records show surface vertical deformations which are significant information to estimate the variation of terrestrial water storage. We compute the loading deformations at GPS stations based on synthetic models of seasonal water load distribution and then invert the synthetic GPS data for surface mass distribution. We use GRACE gravity observations and hydrology models to evaluate seasonal water storage variability in Nepal and Himalayas. The coherence among GPS inversion results, GRACE and hydrology models indicate that GPS can provide quantitative estimates of terrestrial water storage variations by inverting the surface deformation observations. The annual peak-to-peak surface mass change derived from GPS and GRACE results reveal seasonal loads oscillations of water, snow and ice. Meanwhile, the present uplifting of Nepal and Himalayas indicates the hydrology mass loss. This study is supported by National 973 Project China (grant Nos. 2013CB733302 and 2013CB733305), NSFC (grant Nos. 41174011, 41429401, 41210006, 41128003, 41021061).

Chlorine stress mediates microbial surface attachment in drinking water systems.

PubMed

Liu, Li; Le, Yang; Jin, Juliang; Zhou, Yuliang; Chen, Guowei

2015-03-01

Microbial attachment to drinking water pipe surfaces facilitates pathogen survival and deteriorates disinfection performance, directly threatening the safety of drinking water. Notwithstanding that the formation of biofilm has been studied for decades, the underlying mechanisms for the origins of microbial surface attachment in biofilm development in drinking water pipelines remain largely elusive. We combined experimental and mathematical methods to investigate the role of environmental stress-mediated cell motility on microbial surface attachment in chlorination-stressed drinking water distribution systems. Results show that at low levels of disinfectant (0.0-1.0 mg/L), the presence of chlorine promotes initiation of microbial surface attachment, while higher amounts of disinfectant (>1.0 mg/L) inhibit microbial attachment. The proposed mathematical model further demonstrates that chlorination stress (0.0-5.0 mg/L)-mediated microbial cell motility regulates the frequency of cell-wall collision and thereby controls initial microbial surface attachment. The results reveal that transport processes and decay patterns of chlorine in drinking water pipelines regulate microbial cell motility and, thus, control initial surface cell attachment. It provides a mechanistic understanding of microbial attachment shaped by environmental disinfection stress and leads to new insights into microbial safety protocols in water distribution systems.

Predictability and Quantification of Complex Groundwater Table Dynamics Driven by Irregular Surface Water Fluctuations

NASA Astrophysics Data System (ADS)

Xin, Pei; Wang, Shen S. J.; Shen, Chengji; Zhang, Zeyu; Lu, Chunhui; Li, Ling

2018-03-01

Shallow groundwater interacts strongly with surface water across a quarter of global land area, affecting significantly the terrestrial eco-hydrology and biogeochemistry. We examined groundwater behavior subjected to unimodal impulse and irregular surface water fluctuations, combining physical experiments, numerical simulations, and functional data analysis. Both the experiments and numerical simulations demonstrated a damped and delayed response of groundwater table to surface water fluctuations. To quantify this hysteretic shallow groundwater behavior, we developed a regression model with the Gamma distribution functions adopted to account for the dependence of groundwater behavior on antecedent surface water conditions. The regression model fits and predicts well the groundwater table oscillations resulting from propagation of irregular surface water fluctuations in both laboratory and large-scale aquifers. The coefficients of the Gamma distribution function vary spatially, reflecting the hysteresis effect associated with increased amplitude damping and delay as the fluctuation propagates. The regression model, in a relatively simple functional form, has demonstrated its capacity of reproducing high-order nonlinear effects that underpin the surface water and groundwater interactions. The finding has important implications for understanding and predicting shallow groundwater behavior and associated biogeochemical processes, and will contribute broadly to studies of groundwater-dependent ecology and biogeochemistry.

Occurrence and distribution of perfluoroalkyl substances (PFASs) in surface water and bottom water of the Shuangtaizi Estuary, China.

PubMed

Shao, Mihua; Ding, Guanghui; Zhang, Jing; Wei, Lie; Xue, Huanhuan; Zhang, Nannan; Li, Yang; Chen, Guanqun; Sun, Yeqing

2016-09-01

Perfluoroalkyl substances (PFASs) have been recognized as emerging environmental pollutants. However, there is limited information on the contamination level and spatial distribution of PFASs in the Shuangtaizi Estuary, where the Shuangtaizi Hekou Nature Reserve is located. In the present study, the contamination level and spatial distribution of PFASs in surface water (approximately 0.5 m below the surface) and bottom water (about 0.5 m above the bottom) of the Shuangtaizi Estuary were investigated. The data indicated that the Shuangtaizi Estuary was commonly contaminated by PFASs. The total concentration of PFASs in surface and bottom water of the Shuangtaizi Estuary ranged from 66.2 to 185 ng L(-1) and from 44.8 to 209 ng L(-1), respectively. The predominant PFASs were perfluorobutanoic acid (PFBA), perfluoropentanoic acid, perfluorooctanoic acid, perfluorohexanoic acid and perfluorobutane sulfonate (PFBS). In general, PFAS concentrations in surface water samples were lower than those in bottom water samples. The spatial distribution of PFASs in the Shuangtaizi Estuary was mainly affected by particular landform, tide and residual currents in Liaodong Bay. The total mass flux of 15 PFASs from the Shuangtaizi River to Liaodong Bay was estimated to be 352 kg year(-1), which was lower than the total flux from the Daling River and the Daliao River. As short-chain PFASs, such as PFBS and PFBA, have been the prevalent compounds in some places and are continuously produced and used, long-term monitoring and effective pollution controls are suggested. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Modelling Analysis of the Response of Convective Transport of Energy and Water to Multiscale Surface Heterogeneity over Tibetan Plateau

NASA Astrophysics Data System (ADS)

SUN, G.; Hu, Z.; Ma, Y.; Ma, W.

2017-12-01

The land-atmospheric interactions over a heterogeneous surface is a tricky issue for accurately understanding the energy-water exchanges between land surface and atmosphere. We investigate the vertical transport of energy and water over a heterogeneous land surface in Tibetan Plateau during the evolution of the convective boundary layer using large eddy simulation (WRF_LES). The surface heterogeneity is created according to remote sensing images from high spatial resolution LandSat ETM+ images. The PBL characteristics over a heterogeneous surface are analyzed in terms of secondary circulations under different background wind conditions based on the horizontal and vertical distribution and evolution of wind. The characteristics of vertical transport of energy and heat over a heterogeneous surface are analyzed in terms of the horizontal distribution as well as temporal evolution of sensible and latent heat fluxes at different heights under different wind conditions on basis of the simulated results from WRF_LES. The characteristics of the heat and water transported into the free atmosphere from surface are also analyzed and quantified according to the simulated results from WRF_LES. The convective transport of energy and water are analyzed according to horizontal and vertical distributions of potential temperature and vapor under different background wind conditions. With the analysis based on the WRF_LES simulation, the performance of PBL schemes of mesoscale simulation (WRF_meso) is evaluated. The comparison between horizontal distribution of vertical fluxes and domain-averaged vertical fluxes of the energy and water in the free atmosphere is used to evaluate the performance of PBL schemes of WRF_meso in the simulation of vertical exchange of energy and water. This is an important variable because only the energy and water transported into free atmosphere is able to influence the regional and even global climate. This work would will be of great significance not only for understanding the land atmosphere interactions over a heterogeneous surface by evaluating and improving the performance PBL schemes in WRF-meso, but also for the understanding the profound effect of Tibetan Plateau on the regional and global climate.

Distribution and Identification of Luminous Bacteria from the Sargasso Sea

PubMed Central

Orndorff, S. A.; Colwell, R. R.

1980-01-01

Vibrio fischeri and Lucibacterium harveyi constituted 75 of the 83 luminous bacteria isolated from Sargasso Sea surface waters. Photobacterium leiognathi and Photobacterium phosphoreum constituted the remainder of the isolates. Luminescent bacteria were recovered at concentrations of 1 to 63 cells per 100 ml from water samples collected at depths of 160 to 320 m. Two water samples collected at the thermocline yielded larger numbers of viable, aerobic heterotrophic and luminous bacteria. Luminescent bacteria were not recovered from surface microlayer samples. The species distribution of the luminous bacteria reflected previously recognized growth patterns; i.e., L. harveyi and V. fischeri were predominant in the upper, warm waters (only one isolate of P. phosphoreum was obtained from surface tropical waters). PMID:16345575

Soil water content spatial pattern estimated by thermal inertia from air-borne sensors

NASA Astrophysics Data System (ADS)

Coppola, Antonio; Basile, Angelo; Esposito, Marco; Menenti, Massimo; Buonanno, Maurizio

2010-05-01

Remote sensing of soil water content from air- or space-borne platforms offer the possibility to provide large spatial coverage and temporal continuity. The water content can be actually monitored in a thin soil layer, usually up to a depth of 0.05m below the soil surface. To the contrary, difficulties arise in the estimation of the water content storage along the soil profile and its spatial (horizontal) distribution, which are closely connected to soil hydraulic properties and their spatial distribution. A promising approach for estimating soil water contents profiles is the integration of remote sensing of surface water content and hydrological modeling. A major goal of the scientific group is to develop a practical and robust procedure for estimating water contents throughout the soil profile from surface water content. As a first step, in this work, we will show some preliminary results from aircraft images analysis and their validation by field campaigns data. The data extracted from the airborne sensors provided the opportunity of retrieving land surface temperatures with a very high spatial resolution. The surface water content pattern, as deduced by the thermal inertia estimations, was compared to the surface water contents maps measured in situ by time domain reflectometry-based probes.

Spatial Distributions of DDTs in the Water Masses of the Arctic Ocean.

PubMed

Carrizo, Daniel; Sobek, Anna; Salvadó, Joan A; Gustafsson, Örjan

2017-07-18

There is a scarcity of data on the amount and distribution of the organochlorine pesticide dichlorodiphenyltrichloroethane (DDT) and its metabolites in intermediate and deep ocean water masses. Here, the distribution and inventories of DDTs in water of the Arctic shelf seas and the interior basin are presented. The occurrence of ∑ 6 DDT (0.10-66 pg L -1 ) in the surface water was dominated by 4,4'-DDE. In the Central Arctic Ocean increasing concentrations of DDE with depth were observed in the Makarov and Amundsen basins. The increasing concentrations down to 2500 m depth is in accordance with previous findings for PCBs and PBDEs. Similar concentrations of DDT and DDEs were found in the surface water, while the relative contribution of DDEs increased with depth, demonstrating a transformation over time and depth. Higher concentrations of DDTs were found in the European part of the Arctic Ocean; these distributions likely reflect a combination of different usage patterns, transport, and fate of these compounds. For instance, the elevated concentrations of DDTs in the Barents and Atlantic sectors of the Arctic Ocean indicate the northbound Atlantic current as a significant conveyor of DDTs. This study contributes to the very rare data on OCPs in the vast deep-water compartments and combined with surface water distribution across the Arctic Ocean helps to improve our understanding of the large-scale fate of DDTs in the Arctic.

Field Evaluation Of Arsenic Transport Across The Ground-Water/Surface Water Interface: Ground-Water Discharge And Iron Oxide Precipitation

EPA Science Inventory

A field investigation was conducted to examine the distribution of arsenic in ground water, surface water, and sediments at a Superfund Site in the northeastern United States (see companion presentation by K. G. Scheckel et al). Ground-water discharge into the study area was cha...

Bisphenol analogues in surface water and sediment from the shallow Chinese freshwater lakes: Occurrence, distribution, source apportionment, and ecological and human health risk.

PubMed

Yan, Zhengyu; Liu, Yanhua; Yan, Kun; Wu, Shengmin; Han, Zhihua; Guo, Ruixin; Chen, Meihong; Yang, Qiulian; Zhang, Shenghu; Chen, Jianqiu

2017-10-01

Compared to Bisphenol A (BPA), current knowledge on the spatial distribution, potential sources and environmental risk assessment of other bisphenol analogues (BPs) remains limited. The occurrence, distribution and sources of seven BPs were investigated in the surface water and sediment from Taihu Lake and Luoma Lake, which are the Chinese shallow freshwater lakes. Because there are many industries and living areas around Taihu Lake, the total concentrations of ∑BPs were much higher than that in Luoma Lake, which is away from the industry-intensive areas. For the two lakes, BPA was still the dominant BPs in both surface water and sediment, followed by BPF and BPS. The spatial distribution and principal component analysis showed that BPs in Luoma Lake was relatively homogeneous and the potential sources were relatively simple than that in Taihu Lake. The spatial distribution of BPs in sediment of Taihu Lake indicated that ∑BPs positively correlated with the TOC content. For both Taihu Lake and Luoma Lake, the risk assessment at the sampling sites showed that no high risk in surface water and sediment (RQ t  < 1.0, and EEQ t  < 1.0 ng E 2 /L). Copyright © 2017 Elsevier Ltd. All rights reserved.

Composition profiles, levels, distributions and ecological risk assessments of trihalomethanes in surface water from a typical estuary of Bohai Bay, China.

PubMed

Niu, Zhiguang; Li, Xiaonan; Zhang, Ying

2017-04-15

To characterize the spatiotemporal distribution and potential ecological risk for trihalomethanes (THMs) in the surface water of a river estuary, surface water samples were collected over five consecutive months (from March to July 2016) from four sites in the Haihe River estuary of Bohai Bay. The potential ecological risks of THMs were evaluated quantitatively based on a species sensitivity distribution (SSD) model. The results demonstrate that trichloromethane (TCM) was the predominant THM in surface water of the Haihe River estuary (2.93±1.98μg/L) followed by tribromomethane (TBM) (0.42±0.33μg/L), bromodichloromethane (BDCM) (0.14±0.06μg/L) and dibromochloromethane (DBCM) (0.09±0.10μg/L). The concentration of TCM was higher in summer than that in spring, while TBM displayed the opposite trend. The TCM concentration decreased from the estuary to the adjacent sea. However, the levels of TBM and DBCM in the adjacent sea were higher than those in the estuary. The ecological risks of THMs in surface water of Haihe River were notably low, and the ecological risks of THMs in freshwater were generally higher than those in seawater. Compared with other contaminants in water and surface sediment from rivers and coastal areas, the ecological risk levels of THMs in surface water can be considered low. This study is a contribution to the progress of ecological risk assessment of THMs. Copyright © 2017 Elsevier Ltd. All rights reserved.

Patterned gradient surface for spontaneous droplet transportation and water collection: simulation and experiment

NASA Astrophysics Data System (ADS)

Tan, Xianhua; Zhu, Yiying; Shi, Tielin; Tang, Zirong; Liao, Guanglan

2016-11-01

We demonstrate spontaneous droplet transportation and water collection on wedge-shaped gradient surfaces consisting of alternating hydrophilic and hydrophobic regions. Droplets on the surfaces are modeled and simulated to analyze the Gibbs free energy and free energy gradient distributions. Big half-apex angle and great wettability difference result in considerable free energy gradient, corresponding to large driving force for spontaneous droplet transportation, thus causing the droplets to move towards the open end of the wedge-shaped hydrophilic regions, where the Gibbs free energy is low. Gradient surfaces are then fabricated and tested. Filmwise condensation begins on the hydrophilic regions, forming wedge-shaped tracks for water collection. Dropwise condensation occurs on the hydrophobic regions, where the droplet size distribution and departure diameters are controlled by the width of the regions. Condensate water from both the hydrophilic and hydrophobic regions are collected directionally to the open end of the wedge-shaped hydrophilic regions, agreeing with the simulations. Directional droplet transport and controllable departure diameters make the branched gradient surfaces more efficient than smooth surfaces for water collection, which proves that gradient surfaces are potential in water collection, microfluidic devices, anti-fogging and self-cleaning.

Methane Emissions from Small Lakes: Dynamics and Distribution Patterns

NASA Astrophysics Data System (ADS)

Encinas Fernández, J. M.; Peeters, F.; Hofmann, H.

2014-12-01

The dynamics of dissolved methane were measured during three years in five small lakes with different surface areas and maximum water depth. We analyze and compare the horizontal and vertical distribution of dissolved methane within these lakes during different time periods: the stratified period in summer, the autumn overturn, the winter mixing period, and the period from spring to summer stratification. The horizontal distributions of dissolved methane within the lakes suggest that the relation between surface area and maximum water-depth is a key factor determining the heterogeneity of methane concentrations in the surface water. During most of the year littoral zones are the main source of the methane that is emitted to the atmosphere except for the overturn periods. The vertical distributions of temperature and dissolved oxygen within the different seasons affect the vertical distribution of dissolved methane and thus the methane budget within lakes. Anoxic conditions in the hypolimnion and the intense mixing during overturn periods are key factors for the overall annual methane emissions from lakes.

Fractal topography and subsurface water flows from fluvial bedforms to the continental shield

USGS Publications Warehouse

Worman, A.; Packman, A.I.; Marklund, L.; Harvey, J.W.; Stone, S.H.

2007-01-01

Surface-subsurface flow interactions are critical to a wide range of geochemical and ecological processes and to the fate of contaminants in freshwater environments. Fractal scaling relationships have been found in distributions of both land surface topography and solute efflux from watersheds, but the linkage between those observations has not been realized. We show that the fractal nature of the land surface in fluvial and glacial systems produces fractal distributions of recharge, discharge, and associated subsurface flow patterns. Interfacial flux tends to be dominated by small-scale features while the flux through deeper subsurface flow paths tends to be controlled by larger-scale features. This scaling behavior holds at all scales, from small fluvial bedforms (tens of centimeters) to the continental landscape (hundreds of kilometers). The fractal nature of surface-subsurface water fluxes yields a single scale-independent distribution of subsurface water residence times for both near-surface fluvial systems and deeper hydrogeological flows. Copyright 2007 by the American Geophysical Union.

Microbial Community Profile of a Lead Service Line Removed from a Drinking Water Distribution System

EPA Science Inventory

A corroded lead water pipe was removed from a drinking water distribution system and the microbial community was profiled using 16S rDNA techniques. This is the first report of the characterization of biofilm on a surface of a corroded lead drinking water pipe. The majority of ...

The spatial and temporal distribution of chemical species in Padaviya Reservoir, Sri Lanka.

NASA Astrophysics Data System (ADS)

Koliyabandara, S. M. P. A.; Siriwardhana, C.; Cooray, P. L. A. T.; Liyanage, S. S.

2017-12-01

Water is one of the most important assets for human life. Eutrophication and pollution are some of the major threats to many freshwater bodies. There are thousands of reservoirs exist in Sri Lanka; however, only a handful of them has been thoroughly monitored and studied. The main objective of this study is to investigate the temporal and spatial distribution of chemical species in Padaviya reservoir which is shallow man-made irrigation reservoir (8°49'30.6" N and 80°46'2.05"E) located in Sri Lanka constructed around 300 BC. The average depth is 8 m and 4 m in wet and dry seasons respectively. It has a catchment area of 270 km2. Water sampling was done at bi-monthly intervals for a period of one year staring from January 2016. Chemical analyses were conducted according to standard protocols. The maximum temperature difference between the surface and bottom waters of the reservoir was 2 °C throughout the year. The surface and bottom water conductivity varied between 175 ± 2.3 to 250 ± 3.0 μS cm-1 and 475 ± 3.7 to 600 ± 4.5 μScm-1 respectively. The average pH of surface and bottom waters varied between 8.5 ± 0.1 to 7.8 ± 0.2 and 7.2 ± 0.02 to 6.8 ± 0.2 respectively. The dissolved oxygen concentration showed a clinograde type distribution throughout the year where the surface waters were well oxygenated (DO ≈ 7.5 ppm) and the bottom waters were anoxic (DO ≈ 0.15 ppm). Ammonia concentration increased with the depth from surface concentration of 150 ± 50 to 300 ± 25 ppb at the bottom. Nitrite distribution was similar to ammonia and the surface concentration was 100 ± 25ppb throughtout the year and at the bottom it varied between 300 ± 30 to 4500 ± 30 ppb. Water soluble phosphate distribution was also similar to ammonia. The surface concentration was 200 ± 20 ppb throughtout the year and varied from 100 ± 20 to 2000 ±20 ppb at the bottom. Nitrate distribution was inverse of the ammonia. The surface concentration was 500 ± 30 to 900 ± 30 ppb while the it was 100 ± 30ppb at the bottom throughout the year. The fluctionations of the concentrations of chemical species was attributed to the wet and dry seasons of the reservoir. Key words - Chemical species, Water quality, Padaviya,Acknowledgement - Financial support by University of Sri Jayewardenepura, ASP/01/RE/SCI/2015/29.

Distribution of acidic and neutral drugs in surface waters near sewage treatment plants in the lower Great Lakes, Canada.

PubMed

Metcalfe, Chris D; Miao, Xiu-Sheng; Koenig, Brenda G; Struger, John

2003-12-01

Prescription and nonprescription drugs have been detected in rivers and streams in Europe and the United States. Sewage treatment plants (STPs) are an important source of these contaminants, but few data exist on the spatial distribution of drugs in surface waters near STPs. Samples of surface water were collected in the summer and fall of 2000 at open-water sites in the lower Great Lakes (Lake Ontario and Lake Erie), at sites near the two STPs for the city of Windsor (ON, Canada), and at sites in Hamilton Harbour (ON, Canada), an embayment of western Lake Ontario that receives discharges from several STPs. In a follow-up study in the summer of 2002, samples of surface water and final effluent from adjacent STPs were collected from sites in Hamilton Harbour and Windsor. In addition, surface water and STP effluent samples were collected in Peterborough (ON, Canada). All samples of surface water and STP effluents were analyzed for selected acidic and neutral drugs. In the survey of Hamilton Harbour and Windsor conducted in 2000, acidic drugs and the antiepileptic drug carbamazepine were detected at ng/L concentrations at sites that were up to 500 m away from the STP, but the hydrological conditions of the receiving waters strongly influenced the spatial distribution of these compounds. Drugs were not detected at open-water locations in western Lake Erie or in the Niagara River near the municipality of Niagara-on-the-Lake (ON, Canada). However, clofibric acid, ketoprofen, fenoprofen, and carbamazepine were detected in samples collected in the summer of 2000 at sites in Lake Ontario and at a site in the Niagara River (Fort Erie, ON, Canada) that were relatively remote from STP discharges. Follow-up studies in the summer of 2002 indicated that concentrations of acidic and neutral drugs in surface waters near the point of sewage discharge into the Little River (ON, Canada) STP were approximately equal to the concentrations in the final effluent from the STP. Caffeine and cotinine, a metabolite of nicotine, were generally present in STP effluents and surface waters contaminated by drugs. The antidepressant fluoxetine and the antibiotic trimethoprom were also detected in most STP effluents and some surface water samples. For the first time, the lipid regulating drug atorvastatin was detected in samples of STP effluent and surface water.

Seasonally-Active Water on Mars: Vapour, Ice, Adsorbate, and the Possibility of Liquid

NASA Astrophysics Data System (ADS)

Richardson, M. I.

2002-12-01

Seasonally-active water can be defined to include any water reservoir that communicates with other reservoirs on time scales of a year or shorter. It is the interaction of these water reservoirs, under the influence of varying solar radiation and in conjunction with surface and atmospheric temperatures, that determines the phase-stability field for water at the surface, and the distribution of water in various forms below, on, and above the surface. The atmosphere is the critical, dynamical link in this cycling system, and also (fortunately) one of the easiest to observe. Viking and Mars Global Surveyor observations paint a strongly asymmetric picture of the global seasonal water cycle, tied proximately to planetary eccentricity, and the existence of residual ice caps of different composition at the two poles. The northern summer experiences the largest water vapour columns, and is associated with sublimation from the northern residual water ice cap. The southern summer residual carbon dioxide ice cap is cold trap for water. Asymmetry in the water cycle is an unsolved problem. Possible solutions may involve the current timing of perihelion (the water cap resides at the pole experiencing the longer but cooler summer), the trapping of water ice in the northern hemisphere by tropical water ice clouds, and the bias in the annual-average, zonal-mean atmospheric circulation resulting from the zonal-mean difference in the elevation of the northern and southern hemispheres. Adsorbed and frozen water have proven harder to constrain. Recent Odyssey Gamma Ray Spectrometer results suggest substantial ground ice in the mid- and high-latitudes, but this water is likely below the seasonal skin depth for two reasons: the GRS results are best fit with such a model, and GCM models of the water cycle produce dramatically unrealistic atmospheric vapour distributions when such a very near surface, GRS-like distribution is initialized - ultimately removing the water to the northern and southern caps. Similar climate-models of the water cycle also do not need much exchangeable adsorbed water in order to explain the observed vapour distributions. The possibility of liquid water is tantalizing, but difficult to definitively judge. On scales greater than a meter or so, Mars is most definitely well away from the water triple point--although the surface pressure can exceed 6.1 mbars, the partial pressure of water vapor (to which the triple point refers) is at best orders of magnitude lower. Several careful studies have shown, however, that locally transient (meta-stable) liquid is possible, if the net heating of ice deposits is high enough. This process is aided if the total surface pressure exceeds 6.1mbar (this prevents boiling, or the explosive loss of vapour into the atmosphere) or if the liquid is covered by a thin ice shell, and is only possible if surface temperatures exceed 273K (for pure water, or the appropriate eutectic for brines) and if ice is present. The former challenge is much easier to meet than the latter. The melt scenario requires that ice deposited in winter must be protected from sublimation as surface temperatures increase in spring, but then exposed to the peak of solar heating in summer. Available spacecraft observations of seasonal water will be discussed with the aid of GCM model simulations, and examined in the context of water distributions and phases.

A Geology-Based Estimate of Connate Water Salinity Distribution

DTIC Science & Technology

2014-09-01

poses serious environmental concerns if connate water is mobilized into shallow aquifers or surface water systems. Estimating the distribution of...groundwater flow and salinity transport near the Herbert Hoover Dike (HHD) surrounding Lake Okeechobee in Florida . The simulations were conducted using the...on the geologic configuration at equilibrium, and the horizontal salinity distribution is strongly linked to aquifer connectivity because

Characteristics of Chernobyl-derived radionuclides in particulate form in surface waters in the exclusion zone around the Chernobyl Nuclear Power Plant

NASA Astrophysics Data System (ADS)

Matsunaga, Takeshi; Ueno, Takashi; Amano, Hikaru; Tkatchenko, Y.; Kovalyov, A.; Watanabe, Miki; Onuma, Yoshikazu

1998-12-01

The distribution of Chernobyl-derived radionuclides in river and lake water bodies at 6-40 km from the Chernobyl Nuclear Power Plant was studied. Current levels of radionuclides (Cesium-137, Strontium-90, Plutonium, Americium and Curium isotopes) in water bodies and their relation to the ground contamination are presented. The investigation of the radionuclide composition of aqueous and ground contamination revealed that radionuclides on suspended solids (particulate form) originate mainly from the erosion of the contaminated surface soil layer in the zone. Apparent distribution ratios between particulate and dissolved forms are compared to known distribution coefficients.

DISTRIBUTION OF ORGANIC WASTEWATER CONTAMINANTS BETWEEN WATER AND SEDIMENT IN SURFACE WATERS OF THE UNITED STATES

EPA Science Inventory

Trace concentrations of pharmaceuticals and other organic wastewater contaminants have been determined in the surface waters of Europe and the United States. A preliminary report of substantially higher concentrations of pharmaceuticals in sediment suggests that bottom sediment ...

Iron and copper release in drinking-water distribution systems.

PubMed

Shi, Baoyou; Taylor, James S

2007-09-01

A large-scale pilot study was carried out to evaluate the impacts of changes in water source and treatment process on iron and copper release in water distribution systems. Finished surface waters, groundwaters, and desalinated waters were produced with seven different treatment systems and supplied to 18 pipe distribution systems (PDSs). The major water treatment processes included lime softening, ferric sulfate coagulation, reverse osmosis, nanofiltration, and integrated membrane systems. PDSs were constructed from PVC, lined cast iron, unlined cast iron, and galvanized pipes. Copper pipe loops were set up for corrosion monitoring. Results showed that surface water after ferric sulfate coagulation had low alkalinity and high sulfates, and consequently caused the highest iron release. Finished groundwater treated by conventional method produced the lowest iron release but the highest copper release. The iron release of desalinated water was relatively high because of the water's high chloride level and low alkalinity. Both iron and copper release behaviors were influenced by temperature.

Monitoring monthly surface water dynamics of Dongting Lake using Sentinel-1 data at 10 m.

PubMed

Xing, Liwei; Tang, Xinming; Wang, Huabin; Fan, Wenfeng; Wang, Guanghui

2018-01-01

High temporal resolution water distribution maps are essential for surface water monitoring because surface water exhibits significant inner-annual variation. Therefore, high-frequency remote sensing data are needed for surface water mapping. Dongting Lake, the second-largest freshwater lake in China, is famous for the seasonal fluctuations of its inundation extents in the middle reaches of the Yangtze River. It is also greatly affected by the Three Gorges Project. In this study, we used Sentinel-1 data to generate surface water maps of Dongting Lake at 10 m resolution. First, we generated the Sentinel-1 time series backscattering coefficient for VH and VV polarizations at 10 m resolution by using a monthly composition method. Second, we generated the thresholds for mapping surface water at 10 m resolution with monthly frequencies using Sentinel-1 data. Then, we derived the monthly surface water distribution product of Dongting Lake in 2016, and finally, we analyzed the inner-annual surface water dynamics. The results showed that: (1) The thresholds were -21.56 and -15.82 dB for the backscattering coefficients for VH and VV, respectively, and the overall accuracy and Kappa coefficients were above 95.50% and 0.90, respectively, for the VH backscattering coefficient, and above 94.50% and 0.88, respectively, for the VV backscattering coefficient. The VV backscattering coefficient achieved lower accuracy due to the effect of the wind causing roughness on the surface of the water. (2) The maximum and minimum areas of surface water were 2040.33 km 2 in July, and 738.89 km 2 in December. The surface water area of Dongting Lake varied most significantly in April and August. The permanent water acreage in 2016 was 556.35 km 2 , accounting for 19.65% of the total area of Dongting Lake, and the acreage of seasonal water was 1525.21 km 2 . This study proposed a method to automatically generate monthly surface water at 10 m resolution, which may contribute to monitoring surface water in a timely manner.

Streamflow distribution maps for the Cannon River drainage basin, southeast Minnesota, and the St. Louis River drainage basin, northeast Minnesota

USGS Publications Warehouse

Smith, Erik A.; Sanocki, Chris A.; Lorenz, David L.; Jacobsen, Katrin E.

2017-12-27

Streamflow distribution maps for the Cannon River and St. Louis River drainage basins were developed by the U.S. Geological Survey, in cooperation with the Legislative-Citizen Commission on Minnesota Resources, to illustrate relative and cumulative streamflow distributions. The Cannon River was selected to provide baseline data to assess the effects of potential surficial sand mining, and the St. Louis River was selected to determine the effects of ongoing Mesabi Iron Range mining. Each drainage basin (Cannon, St. Louis) was subdivided into nested drainage basins: the Cannon River was subdivided into 152 nested drainage basins, and the St. Louis River was subdivided into 353 nested drainage basins. For each smaller drainage basin, the estimated volumes of groundwater discharge (as base flow) and surface runoff flowing into all surface-water features were displayed under the following conditions: (1) extreme low-flow conditions, comparable to an exceedance-probability quantile of 0.95; (2) low-flow conditions, comparable to an exceedance-probability quantile of 0.90; (3) a median condition, comparable to an exceedance-probability quantile of 0.50; and (4) a high-flow condition, comparable to an exceedance-probability quantile of 0.02.Streamflow distribution maps were developed using flow-duration curve exceedance-probability quantiles in conjunction with Soil-Water-Balance model outputs; both the flow-duration curve and Soil-Water-Balance models were built upon previously published U.S. Geological Survey reports. The selected streamflow distribution maps provide a proactive water management tool for State cooperators by illustrating flow rates during a range of hydraulic conditions. Furthermore, after the nested drainage basins are highlighted in terms of surface-water flows, the streamflows can be evaluated in the context of meeting specific ecological flows under different flow regimes and potentially assist with decisions regarding groundwater and surface-water appropriations. Presented streamflow distribution maps are foundational work intended to support the development of additional streamflow distribution maps that include statistical constraints on the selected flow conditions.

Diversity, community composition, and dynamics of nonpigmented and late-pigmenting rapidly growing mycobacteria in an urban tap water production and distribution system.

PubMed

Dubrou, S; Konjek, J; Macheras, E; Welté, B; Guidicelli, L; Chignon, E; Joyeux, M; Gaillard, J L; Heym, B; Tully, T; Sapriel, G

2013-09-01

Nonpigmented and late-pigmenting rapidly growing mycobacteria (RGM) have been reported to commonly colonize water production and distribution systems. However, there is little information about the nature and distribution of RGM species within the different parts of such complex networks or about their clustering into specific RGM species communities. We conducted a large-scale survey between 2007 and 2009 in the Parisian urban tap water production and distribution system. We analyzed 1,418 water samples from 36 sites, covering all production units, water storage tanks, and distribution units; RGM isolates were identified by using rpoB gene sequencing. We detected 18 RGM species and putative new species, with most isolates being Mycobacterium chelonae and Mycobacterium llatzerense. Using hierarchical clustering and principal-component analysis, we found that RGM were organized into various communities correlating with water origin (groundwater or surface water) and location within the distribution network. Water treatment plants were more specifically associated with species of the Mycobacterium septicum group. On average, M. chelonae dominated network sites fed by surface water, and M. llatzerense dominated those fed by groundwater. Overall, the M. chelonae prevalence index increased along the distribution network and was associated with a correlative decrease in the prevalence index of M. llatzerense, suggesting competitive or niche exclusion between these two dominant species. Our data describe the great diversity and complexity of RGM species living in the interconnected environments that constitute the water production and distribution system of a large city and highlight the prevalence index of the potentially pathogenic species M. chelonae in the distribution network.

Diversity, Community Composition, and Dynamics of Nonpigmented and Late-Pigmenting Rapidly Growing Mycobacteria in an Urban Tap Water Production and Distribution System

PubMed Central

Dubrou, S.; Konjek, J.; Macheras, E.; Welté, B.; Guidicelli, L.; Chignon, E.; Joyeux, M.; Gaillard, J. L.; Heym, B.; Tully, T.

2013-01-01

Nonpigmented and late-pigmenting rapidly growing mycobacteria (RGM) have been reported to commonly colonize water production and distribution systems. However, there is little information about the nature and distribution of RGM species within the different parts of such complex networks or about their clustering into specific RGM species communities. We conducted a large-scale survey between 2007 and 2009 in the Parisian urban tap water production and distribution system. We analyzed 1,418 water samples from 36 sites, covering all production units, water storage tanks, and distribution units; RGM isolates were identified by using rpoB gene sequencing. We detected 18 RGM species and putative new species, with most isolates being Mycobacterium chelonae and Mycobacterium llatzerense. Using hierarchical clustering and principal-component analysis, we found that RGM were organized into various communities correlating with water origin (groundwater or surface water) and location within the distribution network. Water treatment plants were more specifically associated with species of the Mycobacterium septicum group. On average, M. chelonae dominated network sites fed by surface water, and M. llatzerense dominated those fed by groundwater. Overall, the M. chelonae prevalence index increased along the distribution network and was associated with a correlative decrease in the prevalence index of M. llatzerense, suggesting competitive or niche exclusion between these two dominant species. Our data describe the great diversity and complexity of RGM species living in the interconnected environments that constitute the water production and distribution system of a large city and highlight the prevalence index of the potentially pathogenic species M. chelonae in the distribution network. PMID:23835173

Summer distributions of forage fish in the eastern Bering Sea

NASA Astrophysics Data System (ADS)

Parker-Stetter, Sandra L.; Horne, John K.; Farley, Edward V.; Barbee, David H.; Andrews, Alexander G.; Eisner, Lisa B.; Nomura, Jennifer M.

2013-10-01

Juvenile and small adult fish, typically called forage fish, are an important but poorly studied part of the eastern Bering Sea (EBS) ecosystem. Acoustic and trawl data from a non-target survey were used to evaluate distributions of capelin (Mallotus villosus), age-0 Pacific cod (Gadus macrocephalus), and age-0 walleye pollock (Theragra chalcogramma, herein pollock) in 2006-2010. Within the surface zone (15 m to ~35 m, evaluated 2006-2010), capelin occurred throughout the EBS but primarily in the middle shelf. Capelin were also present in the midwater zone (~35 m to 0.5 m off-bottom) in both 2009 and 2010 (evaluated 2009-2010), and resulted in water column zone (15 m to 0.5 m off-bottom) distributions that differed from surface zone characterizations. Age-0 Pacific cod occurred primarily in the surface zone of the middle and outer shelf regions in all years. As midwater and surface zone age-0 Pacific cod were often coincident, water column zone distributions in 2009-2010 were similar to surface zone distributions. Age-0 pollock were found in the EBS surface zone in all years, primarily in the middle and outer shelf regions. High densities of age-0 pollock occurred in the midwater zone in 2006-2007 and 2009-2010. Water column zone distributions of age-0 pollock were similar to surface zone distributions in 2006-2007, but differed in 2009-2010 due to low numbers of age-0 pollock in the surface zone and presence of high densities in the midwater zone of the outer shelf region. While general patterns in capelin distribution in the surface zone were similar between the present and the previous studies, the acoustic-trawl characterization suggested that capelin densities were high in the middle shelf region. As expected, surface zone distributions of age-0 Pacific cod and age-0 pollock were similar to previous characterizations. Observed high densities of midwater age-0 pollock have not been described by previous studies. Annual abundance indices based on bottom or surface trawl data alone will not be sufficient in all years. Data and conclusions from non-target surveys may be constrained compared to dedicated survey efforts, but can provide baseline distributions, potential abundance indices, and insight for planning future research.

Molecular dynamics studies of water deposition on hematite surfaces

NASA Astrophysics Data System (ADS)

Kvamme, Bjørn; Kuznetsova, Tatiana; Haynes, Martin

2012-12-01

The interest in carbon dioxide for enhanced oil recovery is increasing proportional to the decrease in naturally driven oil production and also due to the increasing demand for reduced emission of carbon dioxide to the atmosphere. Transport of carbon dioxide in offshore pipelines involves high pressure and low temperatures which may lead to the formation of hydrate between residual water dissolved in carbon dioxide. The critical question is whether the water at some condition of temperature and pressure will drop out as liquid droplets or as water adsorbed on the surfaces of the pipeline and then subsequently form hydrates heterogeneously. In this work we have used the 6-311G basis set with B3LYP to estimate the charge distribution of different sizes of hematite crystals. The obtained surface charge distribution were kept unchanged while the inner charge distribution where scaled so as to result in an overall neutral crystal. These rust particles were embedded in water and chemical potential for adsorbed water molecules were estimated through thermodynamic integration and compared to similar estimates for same size water cluster. Estimated values of water chemical potentials indicate that it is thermodynamically favorable for water to adsorb on hematite, and that evaluation of potential carbon dioxide hydrate formation conditions and kinetics should be based this sequence of processes.

Three-dimensional evolution of water vapor distributions in the Northern Hemisphere stratosphere as observed by the MLS

NASA Technical Reports Server (NTRS)

Lahoz, W. A.; O'Neill, A.; Carr, E. S.; Harwood, R. S.; Froidevaux, L.; Read, W. G.; Waters, J. W.; Kumer, J. B.; Mergenthaler, J. L.; Roche, A. E.

1994-01-01

The three-dimensional evolution of stratospheric water vapor distributions observed by the Microwave Limb Sounder (MLS) during the period October 1991 - July 1992 is documented. The transport features inferred from the MLS water vapor distributions are corroborated using other dynamical fields, namely, nitrous oxide from the Cryogenic Limb Array Etalon Spectrometer instrument, analyzed winds from the U.K. Meteorological Office (UKMO), UKMO-derived potential vorticity, and the diabatic heating field. By taking a vortex-centered view and an along-track view, the authors observe in great detail the vertical and horizontal structure of the northern winter stratosphere. It is demonstrated that the water vapor distributions show clear signatures of the effects of diabatic descent through isentropic surfaces and quasi-horizontal transport along isentropic surfaces, and that the large-scale winter flow is organized by the interaction between the westerly polar vortex and the Aleutian high.

Two-dimensional description of surface-bounded exospheres with application to the migration of water molecules on the Moon

NASA Astrophysics Data System (ADS)

Schorghofer, Norbert

2015-05-01

On the Moon, water molecules and other volatiles are thought to migrate along ballistic trajectories. Here, this migration process is described in terms of a two-dimensional partial differential equation for the surface concentration, based on the probability distribution of thermal ballistic hops. A random-walk model, a corresponding diffusion coefficient, and a continuum description are provided. In other words, a surface-bounded exosphere is described purely in terms of quantities on the surface, which can provide computational and conceptual advantages. The derived continuum equation can be used to calculate the steady-state distribution of the surface concentration of volatile water molecules. An analytic steady-state solution is obtained for an equatorial ring; it reveals the width and mass of the pileup of molecules at the morning terminator.

Irrigation waters and pipe-based biofilms as sources for antibiotic-resistant bacteria

USDA-ARS?s Scientific Manuscript database

The presence of antibiotic-resistant bacteria in environmental surface waters has gained recent attention. Wastewater- and drinking water distribution systems are known to disseminate antibiotic-resistant bacteria, with the biofilms that form on the inner-surfaces of the pipeline as a hotspot for pr...

Mass transfer in fuel cells. [electron microscopy of components, thermal decomposition of Teflon, water transport, and surface tension of KOH solutions

NASA Technical Reports Server (NTRS)

Walker, R. D., Jr.

1973-01-01

Results of experiments on electron microscopy of fuel cell components, thermal decomposition of Teflon by thermogravimetry, surface area and pore size distribution measurements, water transport in fuel cells, and surface tension of KOH solutions are described.

Atomic Level Cleaning of Poly Methyl Methacrylate Residues from the Graphene Surface Using Radiolized Water at High Temperatures (Postprint)

DTIC Science & Technology

2017-09-05

AFRL-RX-WP-JA-2017-0321 ATOMIC LEVEL CLEANING OF POLY-METHYL- METHACRYLATE RESIDUES FROM THE GRAPHENE SURFACE USING RADIOLIZED WATER AT...N. Zakharov and Eric A. Stach Brookhaven National Laboratory Jennifer Carpena-Nunez National Research Council 9 March 2017 Interim Report...Distribution Statement A. Approved for public release: distribution unlimited. © 2017 AIP PUBLISHING (STINFO COPY) AIR FORCE RESEARCH

Use of satellite images to determine surface-water cover during the flood event of September 13, 2013, in Lyons and western Longmont, Colorado

USGS Publications Warehouse

Cole, Christopher J.; Friesen, Beverly A.; Wilson, Earl M.; Wilds, Stanley R.; Noble, Suzanne M.

2015-01-01

This surface-water cover dataset was created as a timely representation of post-flood ground conditions to support response efforts. This dataset and all processed imagery and derived products were uploaded to the USGS Hazards Data Distribution System (HDDS) website (http://hddsexplorer.usgs.gov/uplift/hdds/) for distribution to those responding to the flood event.

Spatial distribution of perchlorate, iodide and thiocyanate in the aquatic environment of Tianjin, China: environmental source analysis.

PubMed

Qin, Xiaolei; Zhang, Tao; Gan, Zhiwei; Sun, Hongwen

2014-09-01

Although China is the largest producer of fireworks (perchlorate-containing products) in the world, the pathways through which perchlorate enters the environment have not been characterized completely in this country. In this study, perchlorate, iodide and thiocyanate were measured in 101 water samples, including waste water, surface water, sea water and paired samples of rain water and surface runoff collected in Tianjin, China. The concentrations of the target anions were generally on the order of rain>surface water≈waste water treatment plant (WWTP) influent>WWTP effluent. High concentrations of perchlorate, iodide and thiocyanate were detected in rain samples, ranging from 0.35 to 27.3 (median: 4.05), 0.51 to 8.33 (2.92), and 1.31 to 107 (5.62) ngmL(-)(1), respectively. Furthermore, the concentrations of the target anions in rain samples were significantly (r=0.596-0.750, p<0.01) positively correlated with the concentrations obtained in the paired surface runoff samples. The anions tested showed a clear spatial distribution, and higher concentrations were observed in the upper reaches of rivers, sea waters near the coast, and rain-surface runoff pairs sampled in urban areas. Our results revealed that precipitation may act as an important source of perchlorate, iodide and thiocyanate in surface water. Moreover, iodide concentrations in the Haihe River and Dagu Drainage Canal showed a good correlation with an ideal marker (acesulfame) of domestic waste water, indicating that input from domestic waste water was an important source of iodide in the surface waters of Tianjin. Copyright © 2014 Elsevier Ltd. All rights reserved.

Migration of the FDNPP-derived 134Cs and 137Cs along with 226Ra and 228Ra concentrations across the northwestern North Pacific Ocean.

PubMed

Inoue, M; Shirotani, Y; Nagao, S; Kofuji, H; Volkov, Y N; Nishioka, J

2016-10-01

We examined lateral distributions of 134 Cs, 137 Cs, 226 Ra, and 228 Ra in the surface seawaters around the Kuril Islands and the Kamchatka Peninsula in the northwestern North Pacific Ocean during June 2014. The sampling area included three water current areas, the Oyashio Current, the current from the Okhotsk Sea, and the coastal current along the east Kamchatka Peninsula. 226 Ra and 228 Ra distributions differed along the three currents. Low levels of 134 Cs were detected in the surface waters of the Oyashio Current (0.09-0.35 mBq/L), but it was <∼0.1 mBq/L at the surface along the other two currents. This indicates that the distribution of Fukushima Dai-ichi Nuclear Power Plant (FDNPP)-derived radiocesium in surface waters off the Kamchatka and along the Kuril Islands is predominantly governed by the Oyashio current system. Copyright © 2016 Elsevier Ltd. All rights reserved.

Vertical mercury distributions in the oceans

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

Gill, G.A.; Fitzgerald, W.F.

1988-06-01

The vertical distribution of mercury (Hg) was determined at coastal and open ocean sites in the northwest Atlantic and Pacific Oceans. Reliable and diagnostic Hg distribution were obtained, permitting major processes governing the marine biogeochemistry of Hg to be identified. The northwest Atlantic near Bermuda showed surface water Hg concentrations near 4 pM, a maximum of 10 pM within the main thermocline, and concentrations less than or equal to surface water values below the depth of the maximum. The maximum appears to result from lateral transport of Hg enriched waters from higher latitudes. In the central North Pacific, surface watersmore » (to 940 m) were slightly elevated (1.9 {plus minus} 0.7 pM) compared to deeper waters (1.4 {plus minus} 0.4 pM), but on thermocline Hg maximum was observed. At similar depths, Hg concentrations near Bermuda were elevated compared to the central North Pacific Ocean. The authors hypothesize that the source of this Hg comes from diagenetic reactions in oxic margin sediments, releasing dissolved Hg to overlying water. Geochemical steady-state box modeling arguments predict a relatively short ({approximately}350 years) mean residence time for Hg in the oceans, demonstrating the reactive nature of Hg in seawater and precluding significant involvement in nutrient-type recycling. Mercury's distributional features and reactive nature suggest that interaction of Hg with settling particulate matter and margin sediments play important roles in regulating oceanic Hg concentrations. Oceanic Hg distributions are governed by an external cycling process, in which water column distributions reflect a rapid competition between the magnitude of the input source and the intensity of the (water column) removal process.« less

The polarization patterns of skylight reflected off wave water surface.

PubMed

Zhou, Guanhua; Xu, Wujian; Niu, Chunyue; Zhao, Huijie

2013-12-30

In this paper we propose a model to understand the polarization patterns of skylight when reflected off the surface of waves. The semi-empirical Rayleigh model is used to analyze the polarization of scattered skylight; the Harrison and Coombes model is used to analyze light radiance distribution; and the Cox-Munk model and Mueller matrix are used to analyze reflections from wave surface. First, we calculate the polarization patterns and intensity distribution of light reflected off wave surface. Then we investigate their relationship with incident radiation, solar zenith angle, wind speed and wind direction. Our results show that the polarization patterns of reflected skylight from waves and flat water are different, while skylight reflected on both kinds of water is generally highly polarized at the Brewster angle and the polarization direction is approximately parallel to the water's surface. The backward-reflecting Brewster zone has a relatively low reflectance and a high DOP in all observing directions. This can be used to optimally diminish the reflected skylight and avoid sunglint in ocean optics measurements.

Occurrence, distribution, and risk assessment of alkylphenols, bisphenol A, and tetrabromobisphenol A in surface water, suspended particulate matter, and sediment in Taihu Lake and its tributaries.

PubMed

Liu, Dan; Liu, Jining; Guo, Min; Xu, Huaizhou; Zhang, Shenghu; Shi, Lili; Yao, Cheng

2016-11-15

The occurrence and distribution of nine selected compounds were investigated in surface water, suspended particulate matter (SPM), and sediment in Taihu Lake and its tributaries. With the exception of 4-Butylphenol, all compounds were detected in at least two phases, and nonylphenol (NP) and 4-tert-Octylphenol (4-OP) were the predominant alkylphenols (APs) in the lake. A significant correlation was observed between NP and 4-OP, indicating that they may share the same source. Moreover, surface water phase was the dominant sink of Bisphenol A (BPA) in the aquatic environment. The concentrations of BPA between the surface water and SPM phases were closely related to each other. In addition, Tetrabromobisphenol A (TBBPA) exhibited relatively higher concentrations and detection frequencies in the SPM. Risk assessment revealed greater risk associated with the surface water than the sediment, indicating that the discharge of industrial wastewater and domestic sewage poses a serious threat to aquatic ecosystems. Copyright © 2016 Elsevier Ltd. All rights reserved.

Small scale patches of suspended matter and phytoplankton in the Elbe River estuary, German Bight and tidal flats

NASA Technical Reports Server (NTRS)

Doerffer, R.; Fischer, J.; Stoessel, M.; Brockmann, C.; Grassl, H.

1989-01-01

Landsat 5 TM measurements are found suitable for study of small scale features in coastal waters; three independent factors, namely suspended matter concentration, atmospheric scattering, and sea-surface temperature, were extracted from all seven TM channels on the basis of factor analysis. The distribution of suspended matter in near-surface water layer and sea surface temperature is observable with a spatial resolution of at least 120 x 120 sq m. The high correlation between water depth and suspended matter distribution established by ship-gathered data supports the presently hypothesized control by bottom topography and wind-modified tidal currents of eddy and front formation.

Modeling Source Water Threshold Exceedances with Extreme Value Theory

NASA Astrophysics Data System (ADS)

Rajagopalan, B.; Samson, C.; Summers, R. S.

2016-12-01

Variability in surface water quality, influenced by seasonal and long-term climate changes, can impact drinking water quality and treatment. In particular, temperature and precipitation can impact surface water quality directly or through their influence on streamflow and dilution capacity. Furthermore, they also impact land surface factors, such as soil moisture and vegetation, which can in turn affect surface water quality, in particular, levels of organic matter in surface waters which are of concern. All of these will be exacerbated by anthropogenic climate change. While some source water quality parameters, particularly Total Organic Carbon (TOC) and bromide concentrations, are not directly regulated for drinking water, these parameters are precursors to the formation of disinfection byproducts (DBPs), which are regulated in drinking water distribution systems. These DBPs form when a disinfectant, added to the water to protect public health against microbial pathogens, most commonly chlorine, reacts with dissolved organic matter (DOM), measured as TOC or dissolved organic carbon (DOC), and inorganic precursor materials, such as bromide. Therefore, understanding and modeling the extremes of TOC and Bromide concentrations is of critical interest for drinking water utilities. In this study we develop nonstationary extreme value analysis models for threshold exceedances of source water quality parameters, specifically TOC and bromide concentrations. In this, the threshold exceedances are modeled as Generalized Pareto Distribution (GPD) whose parameters vary as a function of climate and land surface variables - thus, enabling to capture the temporal nonstationarity. We apply these to model threshold exceedance of source water TOC and bromide concentrations at two locations with different climate and find very good performance.

Effects of surface active agents on DNAPL migration and distribution in saturated porous media.

PubMed

Cheng, Zhou; Gao, Bin; Xu, Hongxia; Sun, Yuanyuan; Shi, Xiaoqing; Wu, Jichun

2016-11-15

Dissolved surface active agents such as surfactant and natural organic matter can affect the distribution and fate of dense nonaqueous liquids (DNAPLs) in soil and groundwater systems. This work investigated how two common groundwater surface active agents, humic acid (HA) and Tween 80, affected tetrachloroethylene (PCE) migration and source zone architecture in saturated porous media under environmentally relevant conditions. Batch experiments were first conducted to measure the contact angles and interfacial tensions (IFT) between PCE and quartz surface in water containing different amount of surface active agents. Results showed that the contact angle increased and IFT decreased with concentration of surface active agent increasing, and Tween 80 was much more effective than HA. Five 2-D flow cell experiments were then conducted. Correspondingly, Tween 80 showed strong effects on the migration and distribution of PCE in the porous media due to its ability to change the medium wettability from water-wet into intermediate/NAPL-wet. The downward migration velocities of the PCE in three Tween 80 cells were slower than those in the other two cells. In addition, the final saturation of the PCE in the cells containing surface active agents was higher than that in the water-only cell. Results from this work indicate that the presence of surface active agents in groundwater may strongly affect the fate and distribution of DNAPL through altering porous medium wettability. Copyright © 2016 Elsevier B.V. All rights reserved.

Occurrence and distribution of pesticides and volatile organic compounds in ground water and surface water in Central Arizona Basins, 1996-98, and their relation to land use

USGS Publications Warehouse

Gellenbeck, Dorinda J.; Anning, David W.

2002-01-01

Samples of ground water and surface water from the Sierra Vista subbasin, the Upper Santa Cruz Basin, and the West Salt River Valley were collected and analyzed to determine the occurrence and distribution of pesticides and volatile organic compounds in central Arizona. The study was done during 1996-98 within the Central Arizona Basins study unit of the National Water-Quality Assessment program. This study included 121 wells and 4 surface-water sites in the 3 basins and the analyses of samples from 4 sites along the Santa Cruz River that were part of a separate study. Samples were collected from 121 wells and 3 surface-water sites for pesticide analyses, and samples were collected from 109 wells and 3 surface-water sites for volatile organic compound analyses. Certain pesticides detected in ground water and surface water can be related specifically to agricultural or urban uses; others can be related to multiple land uses. Effects from historical agriculture are made evident by detections of DDE in ground-water and surface-water samples collected in the West Salt River Valley and detections of atrazine and deethylatrazine in the ground water in the Upper Santa Cruz Basin. Effects from present agriculture are evident in the seasonal variability in concentrations of pre-emergent pesticides in surface-water samples from the West Salt River Valley. Several detections of DDE and dieldrin in surface water were higher than established water-quality limits. Effects of urban land use are made evident by detections of volatile organic compounds in ground water and surface water from the West Salt River Valley. Detections of volatile organic compounds in surface water from the Santa Cruz River near Nogales, Arizona, also are indications of the effects of urban land use. One detection of tetrachloroethene in ground water was higher than established water-quality limits. Water reuse is an important conservation technique in the Southwest; however, the reuse of water provides a transport mechanism for pesticides and volatile organic compounds to reach areas that are not normally affected by manmade compounds from specific land-use activities. The most complex mixture of pesticides and volatile organic compounds is in the West Salt River Valley and is the result of water-management practices and the combination of land uses in this basin throughout history.

Atmospheric water distribution in a midlatitude cyclone observed by the Seasat Scanning Multichannel Microwave Radiometer

NASA Technical Reports Server (NTRS)

Mcmurdie, L. A.; Katsaros, K. B.

1985-01-01

Patterns in the horizontal distribution of integrated water vapor, integrated liquid water and rainfall rate derived from the Seasat Scanning Multichannel Microwave Radiometer (SMMR) during a September 10-12, 1978 North Pacific cyclone are studied. These patterns are compared with surface analyses, ship reports, radiosonde data, and GOES-West infrared satellite imagery. The SMMR data give a unique view of the large mesoscale structure of a midlatitude cyclone. The water vapor distribution is found to have characteristic patterns related to the location of the surface fronts throughout the development of the cyclone. An example is given to illustrate that SMMR data could significantly improve frontal analysis over data-sparse oceanic regions. The distribution of integrated liquid water agrees qualitatively well with corresponding cloud patterns in satellite imagery and appears to provide a means to distinguish where liquid water clouds exist under a cirrus shield. Ship reports of rainfall intensity agree qualitatively very well with SMMR-derived rainrates. Areas of mesoscale rainfall, on the order of 50 km x 50 km or greater are detected using SMMR derived rainrates.

Topographic effects on flow path and surface water chemistry of the Llyn Brianne catchments in Wales

USGS Publications Warehouse

Wolock, D.M.; Hornberger, G.M.; Musgrove, T.J.

1990-01-01

Topographic shape is a watershed attribute thought to influence the flow path followed by water as it traverses a catchment. Flow path, in turn, may affect the chemical composition of surface waters. Topography is quantified in the hydrological model TOPMODEL as the relative frequency distribution of the index ln( a tanB), where a is the upslope area per unit contour that drains past a point and tanB is the local surface slope. Spatial distributions of ln( a tanB) were calculated for eight catchments in Wales on a 25 m ?? 25 m grid. Among the catchments, mean observed stream H+ concentration during high flow periods was highly correlated with the mean of the ln( a tanB) distribution. The steady-state gain of a transfer function (time series) model relating H+ to discharge was positively correlated with the mean of the ln( a tanB) distribution. These results suggest that during high flow periods, both the average stream acidity and the magnitude of fluctuations in H+ are conditioned by the topographic shape of the catchment. By performing a sensitivity analysis on TOPMODEL, we also show that as the mean of the ln( a tanB) distribution for a catchment increases, so does its theoretical likelihood to produce significant quantities of surface and near-surface runoff. Our observed results in the Llyn Brianne catchments are consistent with this theoretical expectation in that surface or near-surface runoff is often higher in acidity than are deeper sources of hillslope runoff. ?? 1990.

Water's Interfacial Hydrogen Bonding Structure Reveals the Effective Strength of Surface-Water Interactions.

PubMed

Shin, Sucheol; Willard, Adam P

2018-06-05

We combine all-atom molecular dynamics simulations with a mean field model of interfacial hydrogen bonding to analyze the effect of surface-water interactions on the structural and energetic properties of the liquid water interface. We show that the molecular structure of water at a weakly interacting ( i.e., hydrophobic) surface is resistant to change unless the strength of surface-water interactions are above a certain threshold. We find that below this threshold water's interfacial structure is homogeneous and insensitive to the details of the disordered surface, however, above this threshold water's interfacial structure is heterogeneous. Despite this heterogeneity, we demonstrate that the equilibrium distribution of molecular orientations can be used to quantify the energetic component of the surface-water interactions that contribute specifically to modifying the interfacial hydrogen bonding network. We identify this specific energetic component as a new measure of hydrophilicity, which we refer to as the intrinsic hydropathy.

Environmental DNA method for estimating salamander distribution in headwater streams, and a comparison of water sampling methods.

PubMed

Katano, Izumi; Harada, Ken; Doi, Hideyuki; Souma, Rio; Minamoto, Toshifumi

2017-01-01

Environmental DNA (eDNA) has recently been used for detecting the distribution of macroorganisms in various aquatic habitats. In this study, we applied an eDNA method to estimate the distribution of the Japanese clawed salamander, Onychodactylus japonicus, in headwater streams. Additionally, we compared the detection of eDNA and hand-capturing methods used for determining the distribution of O. japonicus. For eDNA detection, we designed a qPCR primer/probe set for O. japonicus using the 12S rRNA region. We detected the eDNA of O. japonicus at all sites (with the exception of one), where we also observed them by hand-capturing. Additionally, we detected eDNA at two sites where we were unable to observe individuals using the hand-capturing method. Moreover, we found that eDNA concentrations and detection rates of the two water sampling areas (stream surface and under stones) were not significantly different, although the eDNA concentration in the water under stones was more varied than that on the surface. We, therefore, conclude that eDNA methods could be used to determine the distribution of macroorganisms inhabiting headwater systems by using samples collected from the surface of the water.

Surface-water radon-222 distribution along the west-central Florida shelf

USGS Publications Warehouse

Smith, C.G.; Robbins, L.L.

2012-01-01

In February 2009 and August 2009, the spatial distribution of radon-222 in surface water was mapped along the west-central Florida shelf as collaboration between the Response of Florida Shelf Ecosystems to Climate Change project and a U.S. Geological Survey Mendenhall Research Fellowship project. This report summarizes the surface distribution of radon-222 from two cruises and evaluates potential physical controls on radon-222 fluxes. Radon-222 is an inert gas produced overwhelmingly in sediment and has a short half-life of 3.8 days; activities in surface water ranged between 30 and 170 becquerels per cubic meter. Overall, radon-222 activities were enriched in nearshore surface waters relative to offshore waters. Dilution in offshore waters is expected to be the cause of the low offshore activities. While thermal stratification of the water column during the August survey may explain higher radon-222 activities relative to the February survey, radon-222 activity and integrated surface-water inventories decreased exponentially from the shoreline during both cruises. By estimating radon-222 evasion by wind from nearby buoy data and accounting for internal production from dissolved radium-226, its radiogenic long-lived parent, a simple one-dimensional model was implemented to determine the role that offshore mixing, benthic influx, and decay have on the distribution of excess radon-222 inventories along the west Florida shelf. For multiple statistically based boundary condition scenarios (first quartile, median, third quartile, and maximum radon-222 inshore of 5 kilometers), the cross-shelf mixing rates and average nearshore submarine groundwater discharge (SGD) rates varied from 100.38 to 10-3.4 square kilometers per day and 0.00 to 1.70 centimeters per day, respectively. This dataset and modeling provide the first attempt to assess cross-shelf mixing and SGD on such a large spatial scale. Such estimates help scale up SGD rates that are often made at 1- to 10-meter resolution to a coarser but more regionally applicable scale of 1- to 10-kilometer resolution. More stringent analyses and model evaluation are required, but results and analyses presented in this report provide the foundation for conducting a more rigorous statistical assessment.

Suspended particulate loads and transports in the nepheloid layer of the abyssal Atlantic Ocean

USGS Publications Warehouse

Biscaye, P.E.; Eittreim, S.L.

1977-01-01

Vertical profiles of light scattering from over 1000 L-DGO nephelometer stations in the Atlantic Ocean have been used to calculate mass concentrations of suspended particles based on a calibration from the western North American Basin. From these data are plotted the distributions of particulate concentrations at clear water and in the more turbid near-bottom water. Clear water is the broad minimum in concentration and light scattering that occurs at varying mid-depths in the water column. Concentrations at clear water are as much as one-to-two orders of magnitude lower than those in surface water but still reflect a similar geographic distribution: relatively higher concentrations at ocean margins, especially underneath upwelling areas, and the lowest concentrations underneath central gyre areas. These distributions within the clear water reflect surface-water biogenic productivity, lateral injection of particles from shelf areas and surface circulation patterns and require that the combination of downward vertical and horizontal transport processes of particles retain this pattern throughout the upper water column. Below clear water, the distribution of standing crops of suspended particulate concentrations in the lower water column are presented. The integration of mass of all particles per unit area (gross particulate standing crop) reflects a relative distribution similar to that at the surface and at clear water levels, superimposed on which is the strong imprint of boundary currents along the western margins of the Atlantic. Reducing the gross particulate standing crop by the integral of the concentration of clear water yields a net particulate standing crop. The distribution of this reflects primarily the interaction of circulating abyssal waters with the ocean bottom, i.e. a strong nepheloid layer which is coincident with western boundary currents and which diminishes in intensity equatorward. The resuspended particulate loads in the nepheloid layer of the basins west of the Mid-Atlantic Ridge, resulting from interaction of abyssal currents with the bottom, range from ??? 2 ?? 106 tons in the equatorial Guyana Basin to ??? 50 ?? 106 tons in the North American Basin. The total resuspended particulate load in the western basins (111 ?? 106 tons) is almost an order of magnitude greater than that in the basins east of the Mid-Atlantic Ridge (13 ?? 106 tons). The net northward flux of resuspended particles carried in the AABW drops from ??? 8 ?? 106 tons/year between the southern and northern ends of the Brazil Basin and remains ??? 1 ?? 106 tons/year across the Guyana Basin. ?? 1977.

Slowly biodegradable organic compounds impact the biostability of non-chlorinated drinking water produced from surface water.

PubMed

Hijnen, W A M; Schurer, R; Bahlman, J A; Ketelaars, H A M; Italiaander, R; van der Wal, A; van der Wielen, P W J J

2018-02-01

It is possible to distribute drinking water without a disinfectant residual when the treated water is biologically stable. The objective of this study was to determine the impact of easily and slowly biodegradable compounds on the biostability of the drinking water at three full-scale production plants which use the same surface water, and on the regrowth conditions in the related distribution systems. Easily biodegradable compounds in the drinking water were determined with AOC-P17/Nox during 2012-2015. Slowly biodegradable organic compounds measured as particulate and/or high-molecular organic carbon (PHMOC), were monitored at the inlet and after the different treatment stages of the three treatments during the same period. The results show that PHMOC (300-470 μg C L -1 ) was approximately 10% of the TOC in the surface water and was removed to 50-100 μg C L -1 . The PHMOC in the water consisted of 40-60% of carbohydrates and 10% of proteins. A significant and strong positive correlation was observed for PHMOC concentrations and two recently introduced bioassay methods for slowly biodegradable compounds (AOC-A3 and biomass production potential, BPC 14 ). Moreover, these three parameters in the biological active carbon effluent (BACF) of the three plants showed a positive correlation with regrowth in the drinking water distribution system, which was assessed with Aeromonas, heterotrophic plate counts, coliforms and large invertebrates. In contrast, the AOC-P17/Nox concentrations did not correlate with these regrowth parameters. We therefore conclude that slowly biodegradable compounds in the treated water from these treatment plants seem to have a greater impact on regrowth in the distribution system than easily biodegradable compounds. Copyright © 2017 Elsevier Ltd. All rights reserved.

Insights into the role of wettability in cathode catalyst layer of proton exchange membrane fuel cell; pore scale immiscible flow and transport processes

NASA Astrophysics Data System (ADS)

Fathi, H.; Raoof, A.; Mansouri, S. H.

2017-05-01

The production of liquid water in cathode catalyst layer, CCL, is a significant barrier to increase the efficiency of proton exchange membrane fuel cell. Here we present, for the first time, a direct three-dimensional pore-scale modelling to look at the complex immiscible two-phase flow in CCL. After production of the liquid water at the surface of CCL agglomerates due to the electrochemical reactions, water spatial distribution affects transport of oxygen through the CCL as well as the rate of reaction at the agglomerate surfaces. To explore the wettability effects, we apply hydrophilic and hydrophobic properties using different surface contact angles. Effective diffusivity is calculated under several water saturation levels. Results indicate larger diffusive transport values for hydrophilic domain compared to the hydrophobic media where the liquid water preferentially floods the larger pores. However, hydrophobic domain showed more available surface area and higher oxygen consumption rate at the reaction sites under various saturation levels, which is explained by the effect of wettability on pore-scale distribution of water. Hydrophobic domain, with a contact angle of 150, reveals efficient water removal where only 28% of the pore space stays saturated. This condition contributes to the enhanced available reaction surface area and oxygen diffusivity.

Detection of Leaks in Water Distribution System using Non-Destructive Techniques

NASA Astrophysics Data System (ADS)

Aslam, H.; Kaur, M.; Sasi, S.; Mortula, Md M.; Yehia, S.; Ali, T.

2018-05-01

Water is scarce and needs to be conserved. A considerable amount of water which flows in the water distribution systems was found to be lost due to pipe leaks. Consequently, innovations in methods of pipe leakage detections for early recognition and repair of these leaks is vital to ensure minimum wastage of water in distribution systems. A major component of detection of pipe leaks is the ability to accurately locate the leak location in pipes through minimum invasion. Therefore, this paper studies the leak detection abilities of the three NDT’s: Ground Penetration Radar (GPR) and spectrometer and aims at determining whether these instruments are effective in identifying the leak. An experimental setup was constructed to simulate the underground conditions of water distribution systems. After analysing the experimental data, it was concluded that both the GPR and the spectrometer were effective in detecting leaks in the pipes. However, the results obtained from the spectrometer were not very differentiating in terms of observing the leaks in comparison to the results obtained from the GPR. In addition to this, it was concluded that both instruments could not be used if the water from the leaks had reached on the surface, resulting in surface ponding.

Three-dimensional water impact at normal incidence to a blunt structure

PubMed Central

Cooker, M. J.; Korobkin, A. A.

2016-01-01

The three-dimensional water impact onto a blunt structure with a spreading rectangular contact region is studied. The structure is mounted on a flat rigid plane with the impermeable curved surface of the structure perpendicular to the plane. Before impact, the water region is a rectangular domain of finite thickness bounded from below by the rigid plane and above by the flat free surface. The front free surface of the water region is vertical, representing the front of an advancing steep wave. The water region is initially advancing towards the structure at a constant uniform speed. We are concerned with the slamming loads acting on the surface of the structure during the initial stage of water impact. Air, gravity and surface tension are neglected. The problem is analysed by using some ideas of pressure-impulse theory, but including the time-dependence of the wetted area of the structure. The flow caused by the impact is three-dimensional and incompressible. The distribution of the pressure-impulse (the time-integral of pressure) over the surface of the structure is analysed and compared with the distributions provided by strip theories. The total impulse exerted on the structure during the impact stage is evaluated and compared with numerical and experimental predictions. An example calculation is presented of water impact onto a vertical rigid cylinder. Three-dimensional effects on the slamming loads are the main concern in this study. PMID:27616912

Distribution of the Fukushima-derived radionuclides in seawater in the Pacific off the coast of Miyagi, Fukushima, and Ibaraki Prefectures, Japan

NASA Astrophysics Data System (ADS)

Oikawa, S.; Takata, H.; Watabe, T.; Misonoo, J.; Kusakabe, M.

2013-07-01

The activities of artificial radionuclides in seawater samples collected off the coast of Miyagi, Fukushima, and Ibaraki Prefectures were measured as part of a monitoring program initiated by the Japanese Ministry of Education, Sports, Science and Technology immediately after the Fukushima Dai-ichi Nuclear Power Plant accident. The spatial and temporal distributions of those activities are summarized herein. The activities of strontium-90, iodine-131, cesium-134 and -137 (i.e. 90Sr, 131I, 134Cs, and 137Cs) derived from the accident were detected in seawater samples taken from areas of the coastal ocean adjacent to the power plant. No 131I was detected in surface waters (≤ 5 m depth) or in intermediate and bottom waters after 30 April 2011. Strontium-90 was found in surface waters collected from a few sampling stations in mid-August 2011 to mid-December 2011. Temporal changes of 90Sr activity in surface waters were evident, although the 90Sr activity at a given time varied widely between sampling stations. The activity of 90Sr in surface waters decreased slowly over time, and by the end of December 2011 had reached background levels recorded before the accident. Radiocesium, 134Cs and 137Cs, was found in seawater samples immediately after the accident. There was a remarkable change in radiocesium activities in surface waters during the first 7 months (March through September 2011) after the accident; the activity reached a maximum in the middle of April and thereafter decreased exponentially with time. Qualitatively, the distribution patterns in surface waters suggested that in early May radiocesium-polluted water was advected northward; some of the water then detached and was transported to the south. Two water cores with high 137Cs activity persisted at least until July 2011. In subsurface waters radiocesium activity was first detected in the beginning of April 2011, and the water masses were characterized by σt (an indicator of density) values of 25.5-26.5. From 9-14 May to 5-16 December 2011, the depths of the water masses increased with time, an indication that deepening of the isopycnal surfaces with time can be an important mechanism for the transport of radiocesium downward in coastal waters. During 4-21 February 2012, the water column became vertically homogeneous, probably because of convective mixing during the winter; the result was nearly constant values of radiocesium activity throughout the water column from the surface to the bottom (~200 m depth) at each station.

Pharmaceutical residues in the drinking water supply: modeling residue concentrations in surface waters of drugs prescribed in the United States.

PubMed

Guerrero-Preston, Rafael; Brandt-Rauf, Paul

2008-09-01

Pharmaceutical residues and other organic wastewater contaminants (OWC) have been shown to survive conventional water-treatment processes and persist in potable water supplies. To estimate the geographical distribution of the Predicted Environmental Concentration (PEC) of selected drugs prescribed by office based physicians in the United States (US), after non-metabolized residues have been excreted and processed in wastewater treatment plants. The geographical distribution of the PEC in surface waters of pharmaceutical residues was calculated, in four regions of the US. Prescription drug data was obtained from the National Ambulatory Medical Care Survey (NAMCS). The PEC of three drugs prescribed by office based physicians in the US between 1998 and 2000 was compared to the concentrations of these pharmaceuticals found in a surface water characterization project conducted by the United States Geological Survey between 1999 and 2000. There were 803,185,420 medications prescribed by office-based physicians in the US between 1998 and 2000. Relief of pain, hormonal, cardiovascular and antimicrobial medications followed very similar prescription patterns, both in terms of quantity and geographical distribution. Together these four types of medications account for more than half of the medications prescribed between 1998 and 2000. The concentration of pharmaceutical residues found in the drinking water supply was not significantly correlated to the PEC of pharmaceuticals prescribed by office-based physicians. The geographical distribution of medications prescribed by office based physicians in the US underlines the need to implement effective public health strategies.

Hydrogen Isotopic Constraints on the Evolution of Surface and Subsurface Water on Mars

NASA Technical Reports Server (NTRS)

Usui, T.; Kurokawa, H.; Wang, J.; Alexander, C. M. O’D.; Simon, J. I.; Jones, J. H.

2017-01-01

The geology and geomorphology of Mars provide clear evidence for the presence of liquid water on its surface during the Noachian and Hesperien eras (i.e., >3 Ga). In contrast to the ancient watery environment, today the surface of Mars is relatively dry. The current desert-like surface conditions, however, do not necessarily indicate a lack of surface or near-surface water/ice. In fact, massive deposits of ground ice and/or icy sediments have been proposed based on subsurface radar sounder observations. Hence, accurate knowledge of both the evolution of the distribution of water and of the global water inventory is crucial to our understanding of the evolution of the climate and near-surface environments and the potential habitability of Mars. This study presents insights from hydrogen isotopes for the interactive evolution of Martian water reservoirs. In particular, based on our new measurement of the D/H ratio of 4 Ga-old Noachian water, we constrain the atmospheric loss and possible exchange of surface and subsurface water through time.

Detecting changes in the spatial distribution of nitrate contamination in ground water

USGS Publications Warehouse

Liu, Z.-J.; Hallberg, G.R.; Zimmerman, D.L.; Libra, R.D.

1997-01-01

Many studies of ground water pollution in general and nitrate contamination in particular have often relied on a one-time investigation, tracking of individual wells, or aggregate summaries. Studies of changes in spatial distribution of contaminants over time are lacking. This paper presents a method to compare spatial distributions for possible changes over time. The large-scale spatial distribution at a given time can be considered as a surface over the area (a trend surface). The changes in spatial distribution from period to period can be revealed by the differences in the shape and/or height of surfaces. If such a surface is described by a polynomial function, changes in surfaces can be detected by testing statistically for differences in their corresponding polynomial functions. This method was applied to nitrate concentration in a population of wells in an agricultural drainage basin in Iowa, sampled in three different years. For the period of 1981-1992, the large-scale spatial distribution of nitrate concentration did not show significant change in the shape of spatial surfaces; while the magnitude of nitrate concentration in the basin, or height of the computed surfaces showed significant fluctuations. The change in magnitude of nitrate concentration is closely related to climatic variations, especially in precipitation. The lack of change in the shape of spatial surfaces means that either the influence of land use/nitrogen management was overshadowed by climatic influence, or the changes in land use/management occurred in a random fashion.

Surface waves generated by shallow underwater explosions

NASA Technical Reports Server (NTRS)

Falade, A.; Holt, M.

1978-01-01

Surface water waves generated by surface and near surface point explosions are calculated. Taking the impulse distribution imparted at the water surface by the explosion as the overriding mechanism for transferring energy of the explosive to surface wave motion, the linearized theory of Kranzer and Keller is used to obtain the wave displacement in the far field. The impulse distribution is obtained by integrating the pressure wave over an appropriate time interval on a horizontal surface just beneath the undisturbed water surface. For surface explosions, a modified form of the similarity method first used by Collins and Holt is used to obtain the flow field. In the case of submerged explosions, the flow field is estimated by making necessary modifications to Sedov's similarity solution to account for the venting that accompanies the interaction of the leading (blast) wave with the ocean surface. Surface waves generated by a charge at six depths of placement (0.15 m, 0.30 m, 0.61 m, 0.91 m, 1.37 m, 3.05 m) are considered in addition to surface explosions. The results seem to support the existence of an upper critical depth phenomenon (of the type already established for chemical explosions) for point (nuclear) explosions.

On the vertical distribution of water vapor in the Martian tropics

NASA Technical Reports Server (NTRS)

Haberle, Robert M.

1988-01-01

Although measurements of the column abundance of atmospheric water vapor on Mars have been made, measurements of its vertical distribution have not. How water is distributed in the vertical is fundamental to atmosphere-surface exchange processes, and especially to transport within the atmosphere. Several lines of evidence suggest that in the lowest several scale heights of the atmosphere, water vapor is nearly uniformly distributed. However, most of these arguments are suggestive rather than conclusive since they only demonstrate that the altitude to saturation is very high if the observed amount of water vapor is distributed uniformly. A simple argument is presented, independent of the saturation constraint, which suggests that in tropical regions, water vapor on Mars should be very nearly uniformly mixed on an annual and zonally averaged basis.

Impact of RO-desalted water on distribution water qualities.

PubMed

Taylor, J; Dietz, J; Randall, A; Hong, S

2005-01-01

A large-scale pilot distribution study was conducted to investigate the impacts of blending different source waters on distribution water qualities, with an emphasis on metal release (i.e. corrosion). The principal source waters investigated were conventionally treated ground water (G1), surface water processed by enhanced treatment (S1), and desalted seawater by reverse osmosis membranes (RO). Due to the nature of raw water quality and associated treatment processes, G1 water had high alkalinity, while S1 and RO sources were characterized as high sulfate and high chloride waters, respectively. The blending ratio of different treated waters determined the quality of finished waters. Iron release from aged cast iron pipes increased significantly when exposed to RO and S1 waters: that is, the greater iron release was experienced with alkalinity reduced below the background of G1 water. Copper release to drinking water, however, increased with increasing alkalinity and decreasing pH. Lead release, on the other hand, increased with increasing chloride and decreasing sulfate. The effect of pH and alkalinity on lead release was not clearly observed from pilot blending study. The flat and compact corrosion scales observed for lead surface exposed to S1 water may be attributable to lead concentration less than that of RO water blends.

(abstract) Satellite Physical Oceanography Data Available From an EOSDIS Archive

NASA Technical Reports Server (NTRS)

Digby, Susan A.; Collins, Donald J.

1996-01-01

The Physical Oceanography Distributed Active Archive Center (PO.DAAC) at the Jet Propulsion Laboratory archives and distributes data as part of the Earth Observing System Data and Information System (EOSDIS). Products available from JPL are largely satellite derived and include sea-surface height, surface-wind speed and vectors, integrated water vapor, atmospheric liquid water, sea-surface temperature, heat flux, and in-situ data as it pertains to satellite data. Much of the data is global and spans fourteen years.There is email access, a WWW site, product catalogs, and FTP capabilities. Data is free of charge.

Hydrochemical characteristics and water quality assessment of surface water and groundwater in Songnen plain, Northeast China.

PubMed

Zhang, Bing; Song, Xianfang; Zhang, Yinghua; Han, Dongmei; Tang, Changyuan; Yu, Yilei; Ma, Ying

2012-05-15

Water quality is the critical factor that influence on human health and quantity and quality of grain production in semi-humid and semi-arid area. Songnen plain is one of the grain bases in China, as well as one of the three major distribution regions of soda saline-alkali soil in the world. To assess the water quality, surface water and groundwater were sampled and analyzed by fuzzy membership analysis and multivariate statistics. The surface water were gather into class I, IV and V, while groundwater were grouped as class I, II, III and V by fuzzy membership analysis. The water samples were grouped into four categories according to irrigation water quality assessment diagrams of USDA. Most water samples distributed in category C1-S1, C2-S2 and C3-S3. Three groups were generated from hierarchical cluster analysis. Four principal components were extracted from principal component analysis. The indicators to water quality assessment were Na, HCO(3), NO(3), Fe, Mn and EC from principal component analysis. We conclude that surface water and shallow groundwater are suitable for irrigation, the reservoir and deep groundwater in upstream are the resources for drinking. The water for drinking should remove of the naturally occurring ions of Fe and Mn. The control of sodium and salinity hazard is required for irrigation. The integrated management of surface water and groundwater for drinking and irrigation is to solve the water issues. Copyright © 2012 Elsevier Ltd. All rights reserved.

Transformation of Deep Water Masses Along Lagrangian Upwelling Pathways in the Southern Ocean

NASA Astrophysics Data System (ADS)

Tamsitt, V.; Abernathey, R. P.; Mazloff, M. R.; Wang, J.; Talley, L. D.

2018-03-01

Upwelling of northern deep waters in the Southern Ocean is fundamentally important for the closure of the global meridional overturning circulation and delivers carbon and nutrient-rich deep waters to the sea surface. We quantify water mass transformation along upwelling pathways originating in the Atlantic, Indian, and Pacific and ending at the surface of the Southern Ocean using Lagrangian trajectories in an eddy-permitting ocean state estimate. Recent related work shows that upwelling in the interior below about 400 m depth is localized at hot spots associated with major topographic features in the path of the Antarctic Circumpolar Current, while upwelling through the surface layer is more broadly distributed. In the ocean interior upwelling is largely isopycnal; Atlantic and to a lesser extent Indian Deep Waters cool and freshen while Pacific deep waters are more stable, leading to a homogenization of water mass properties. As upwelling water approaches the mixed layer, there is net strong transformation toward lighter densities due to mixing of freshwater, but there is a divergence in the density distribution as Upper Circumpolar Deep Water tends become lighter and dense Lower Circumpolar Deep Water tends to become denser. The spatial distribution of transformation shows more rapid transformation at eddy hot spots associated with major topography where density gradients are enhanced; however, the majority of cumulative density change along trajectories is achieved by background mixing. We compare the Lagrangian analysis to diagnosed Eulerian water mass transformation to attribute the mechanisms leading to the observed transformation.

Seasonal lake surface water temperature trends reflected by heterocyst glycolipid-based molecular thermometers

NASA Astrophysics Data System (ADS)

Bauersachs, T.; Rochelmeier, J.; Schwark, L.

2015-06-01

It has been demonstrated that the relative distribution of heterocyst glycolipids (HGs) in cultures of N2-fixing heterocystous cyanobacteria is largely controlled by growth temperature, suggesting a potential use of these components in paleoenvironmental studies. Here, we investigated the effect of environmental parameters (e.g., surface water temperatures, oxygen concentrations and pH) on the distribution of HGs in a natural system using water column filtrates collected from Lake Schreventeich (Kiel, Germany) from late July to the end of October 2013. HPLC-ESI/MS (high-performance liquid chromatography coupled to electrospray ionization-mass spectrometry) analysis revealed a dominance of 1-(O-hexose)-3,25-hexacosanediols (HG26 diols) and 1-(O-hexose)-3-keto-25-hexacosanol (HG26 keto-ol) in the solvent-extracted water column filtrates, which were accompanied by minor abundances of 1-(O-hexose)-3,27-octacosanediol (HG28 diol) and 1-(O-hexose)-3-keto-27-octacosanol (HG28 keto-ol) as well as 1-(O-hexose)-3,25,27-octacosanetriol (HG28 triol) and 1-(O-hexose)-3-keto-25,27-octacosanediol (HG28 keto-diol). Fractional abundances of alcoholic and ketonic HGs generally showed strong linear correlations with surface water temperatures and no or only weak linear correlations with both oxygen concentrations and pH. Changes in the distribution of the most abundant diol and keto-ol (e.g., HG26 diol and HG26 keto-ol) were quantitatively expressed as the HDI26 (heterocyst diol index of 26 carbon atoms) with values of this index ranging from 0.89 in mid-August to 0.66 in mid-October. An average HDI26 value of 0.79, which translates into a calculated surface water temperature of 15.8 ± 0.3 °C, was obtained from surface sediments collected from Lake Schreventeich. This temperature - and temperatures obtained from other HG indices (e.g., HDI28 and HTI28) - is similar to the one measured during maximum cyanobacterial productivity in early to mid-September and suggests that HGs preserved in the sediment record of Lake Schreventeich reflect summer surface water temperatures. As N2-fixing heterocystous cyanobacteria are widespread in present-day freshwater and brackish environments, we conclude that the distribution of HGs in sediments may allow for the reconstruction of surface water temperatures of modern and potentially ancient lacustrine settings.

Thermal Characteristics of ThermoBrachytherapy Surface Applicators (TBSA) for Treating Chestwall Recurrence

PubMed Central

Arunachalam, K.; Maccarini, P. F.; Craciunescu, O. I.; Schlorff, J. L.; Stauffer, P. R.

2010-01-01

Purpose To study temperature and thermal dose distributions of ThermoBrachytherapy Surface Applicators (TBSA) developed for concurrent or sequential high dose rate (HDR) brachytherapy and microwave hyperthermia treatment of chest wall recurrence and other superficial disease. Methods A steady state thermodynamics model coupled with the fluid dynamics of water bolus and electromagnetic radiation of hyperthermia applicator is used to characterize the temperature distributions achievable with TBSA applicators in an elliptical phantom model of the human torso. Power deposited by 915 MHz conformal microwave array (CMA) applicators is used to assess the specific absorption rate (SAR) distributions of rectangular (500 cm2) and L-shaped (875 cm2) TBSA. The SAR distribution in tissue and fluid flow distribution inside the Dual-Input Dual-Output (DIDO) water bolus are coupled to solve the steady state temperature and thermal dose distributions of rectangular TBSA (R-TBSA) for superficial tumor targets extending 10–15 mm beneath the skin surface. Thermal simulations are carried out for a range of bolus inlet temperature (Tb=38–43°C), water flow rate (Qb=2–4 L/min) and tumor blood perfusion (ωb=2–5 kg/m3/s) to characterize their influence on thermal dosimetry. Results Steady state SAR patterns of R- and L-TBSA demonstrate the ability to produce conformal and localized power deposition inside tumor target sparing surrounding normal tissues and nearby critical organs. Acceptably low variation in tissue surface cooling and surface temperature homogeneity was observed for the new DIDO bolus at 2 L/min water flow rate. Temperature depth profiles and thermal dose volume histograms indicate bolus inlet temperature (Tb) to be the most influential factor on thermal dosimetry. A 42 °C water bolus was observed to be the optimal choice for superficial tumors extending 10–15 mm from the surface even under significant blood perfusion. Lower bolus temperature may be chosen to reduce thermal enhancement ratio (TER) in the most sensitive skin where maximum radiation dose is delivered and to extend thermal enhancement of radiation dose deeper. Conclusion This computational study indicates that well-localized elevation of tumor target temperature to 40–44 °C can be accomplished by large surface-conforming TBSA applicators using appropriate selection of coupling bolus temperature. PMID:20224154

Thorium isotopes in colloidal fraction of water from San Marcos Dam, Chihuahua, Mexico

NASA Astrophysics Data System (ADS)

Cabral-Lares, M.; Melgoza, A.; Montero-Cabrera, M. E.; Renteria-Villalobos, M.

2013-07-01

The main interest of this stiidy is to assess the contents and distribution of Th-series isotopes in colloidal fraction of surface water from San Marcos dam, because the suspended particulate matter serves as transport medium for several pollutants. The aim of this work was to assess the distribution of thorium isotopes (232Th and 230Th) contained in suspended matter. Samples were taken from three surface points along the San Marcos dam: water input, midpoint, and near to dam wall. In this last point, a depth sampling was also carried out. Here, three depth points were taken at 0.4, 8 and 15 meters. To evaluate the thorium behavior in surface water, from every water sample the colloidal fraction was separated, between 1 and 0.1 μm. Thorium isotopes concentraron in samples were obtained by alpha spectrometry. Activity concentrations obtained of 232Th and 230Th in surface points ranged from 0.3 to 0.5 Bq ṡ L-1, whereas in depth points ranged from 0.4 to 3.2 Bq ṡ L-1, respectively. The results show that 230Th is in higher concentration than 232Th in colloidal fraction. This can be attributed to a preference of these colloids to adsorb uranium. Thus, the activity ratio 230Th/232Th in colloidal fraction showed values from 2.3 to 10.2. In surface points along the dam, 230Th activity concentration decreases while 232Th concentration remains constant. On the other hand, activity concentrations of both isotopes showed a pointed out enhancement with depth. The results have shown a possible lixiviation of uranium from geological substrate into the surface water and an important fractionation of thorium isotopes, which suggest that thorium is non-homogeneously distributed along San Marcos dam.

Understanding Microplastic Distribution: A Global Citizen Monitoring Effort

NASA Astrophysics Data System (ADS)

Barrows, A.

2016-02-01

Understanding distribution and abundance of microplastics in the world's oceans will continue to help inform global law-making. Through recruiting and training over 500 volunteers our study has collected over 1000 samples from remote and populated areas world-wide. Samples include water collected at the sea surface and throughout the water column. Surface to depth sampling has provided insight into vertical plastic distribution. The development of unique field and laboratory methodology has enabled plastics to be quantified down to 50 µm. In 2015, the study expanded to include global freshwater systems. By understanding plastic patterns, distribution and concentration in large and small watersheds we will better understand how freshwater systems are contributing to marine microplastic pollution.

Occurrence, spatiotemporal distribution, and ecological risks of steroids in a large shallow Chinese lake, Lake Taihu.

PubMed

Zhou, Li-Jun; Zhang, Bei-Bei; Zhao, Yong-Gang; Wu, Qinglong L

2016-07-01

Steroids have been frequently detected in surface waters, and might pose adverse effects on aquatic organisms. However, little information is available regarding the occurrence and spatiotemporal distribution of steroids in lake environments. In addition to pollution sources, the occurrence and spatiotemporal distribution of steroids in lake environments might be related to lake types (shallow or deep), lake hydrodynamics, and sorption-desorption processes in the water-sediment systems. In this study, the occurrence, spatiotemporal distribution, and ecological risks of 36 steroids in a large shallow lake were evaluated by investigating surface water and sediment samples at 32 sites in Lake Taihu over two seasons. Twelve and 15 analytes were detected in aqueous and sedimentary phases, respectively, with total concentrations ranging from 0.86 to 116ng/L (water) and from 0.82 to 16.2ng/g (sediment, dry weight). Temporal variations of steroid concentrations in the water and sediments were statistically significant, with higher concentrations in winter. High concentrations of steroids were found in the seriously polluted bays rather than in the pelagic zone of the lake. Strong lake currents might mix pelagic waters, resulting in similar concentrations of steroids in the pelagic zone. Mass balance analysis showed that sediments in shallow lakes are in general an important sink for steroids. Steroids in the surface water and sediments of Lake Taihu might pose potential risks to aquatic organisms. Overall, our study indicated that the concentrations and spatiotemporal distribution of steroids in the large shallow lake are influenced simultaneously by pollution sources and lake hydrodynamics. Steroids in the large shallow Lake Taihu showed clear temporal and spatial variations and lake sediments may be a potential sink of steroids. Copyright © 2016 Elsevier B.V. All rights reserved.

The Mars water cycle

NASA Technical Reports Server (NTRS)

Davies, D. W.

1981-01-01

A model has been developed to test the hypothesis that the observed seasonal and latitudinal distribution of water on Mars is controlled by the sublimation and condensation of surface ice deposits in the Arctic and Antarctic, and the meridional transport of water vapor. Besides reproducing the observed water vapor distribution, the model correctly reproduces the presence of a large permanent ice cap in the Arctic and not in the Antarctic. No permanent ice reservoirs are predicted in the temperate or equatorial zones. Wintertime ice deposits in the Arctic are shown to be the source of the large water vapor abundances observed in the Arctic summertime, and the moderate water vapor abundances in the northern temperate region. Model calculations suggest that a year without dust storms results in very little change in the water vapor distribution. The current water distribution appears to be the equilibrium distribution for present atmospheric conditions.

The Effect of Reduced Water Availability in the Great Ruaha River on the Vulnerable Common Hippopotamus in the Ruaha National Park, Tanzania.

PubMed

Stommel, Claudia; Hofer, Heribert; East, Marion L

2016-01-01

In semi-arid environments, 'permanent' rivers are essential sources of surface water for wildlife during 'dry' seasons when rainfall is limited or absent, particularly for species whose resilience to water scarcity is low. The hippopotamus (Hippopotamus amphibius) requires submersion in water to aid thermoregulation and prevent skin damage by solar radiation; the largest threat to its viability are human alterations of aquatic habitats. In the Ruaha National Park (NP), Tanzania, the Great Ruaha River (GRR) is the main source of surface water for wildlife during the dry season. Recent, large-scale water extraction from the GRR by people upstream of Ruaha NP is thought to be responsible for a profound decrease in dry season water-flow and the absence of surface water along large sections of the river inside the NP. We investigated the impact of decreased water flow on daytime hippo distribution using regular censuses at monitoring locations, transects and camera trap records along a 104km section of the GRR within the Ruaha NP during two dry seasons. The minimum number of hippos per monitoring location increased with the expanse of surface water as the dry seasons progressed, and was not affected by water quality. Hippo distribution significantly changed throughout the dry season, leading to the accumulation of large numbers in very few locations. If surface water loss from the GRR continues to increase in future years, this will have serious implications for the hippo population and other water dependent species in Ruaha NP.

Evaluating the spatial distribution of water balance in a small watershed, Pennsylvania

NASA Astrophysics Data System (ADS)

Yu, Zhongbo; Gburek, W. J.; Schwartz, F. W.

2000-04-01

A conceptual water-balance model was modified from a point application to be distributed for evaluating the spatial distribution of watershed water balance based on daily precipitation, temperature and other hydrological parameters. The model was calibrated by comparing simulated daily variation in soil moisture with field observed data and results of another model that simulates the vertical soil moisture flow by numerically solving Richards' equation. The impacts of soil and land use on the hydrological components of the water balance, such as evapotranspiration, soil moisture deficit, runoff and subsurface drainage, were evaluated with the calibrated model in this study. Given the same meteorological conditions and land use, the soil moisture deficit, evapotranspiration and surface runoff increase, and subsurface drainage decreases, as the available water capacity of soil increases. Among various land uses, alfalfa produced high soil moisture deficit and evapotranspiration and lower surface runoff and subsurface drainage, whereas soybeans produced an opposite trend. The simulated distribution of various hydrological components shows the combined effect of soil and land use. Simulated hydrological components compare well with observed data. The study demonstrated that the distributed water balance approach is efficient and has advantages over the use of single average value of hydrological variables and the application at a single point in the traditional practice.

Heat transfer and phase transitions of water in multi-layer cryolithozone-surface systems

NASA Astrophysics Data System (ADS)

Khabibullin, I. L.; Nigametyanova, G. A.; Nazmutdinov, F. F.

2018-01-01

A mathematical model for calculating the distribution of temperature and the dynamics of the phase transfor-mations of water in multilayer systems on permafrost-zone surface is proposed. The model allows one to perform calculations in the annual cycle, taking into account the distribution of temperature on the surface in warm and cold seasons. A system involving four layers, a snow or land cover, a top layer of soil, a layer of thermal-insulation materi-al, and a mineral soil, is analyzed. The calculations by the model allow one to choose the optimal thickness and com-position of the layers which would ensure the stability of structures built on the permafrost-zone surface.

Large-Scale Ichthyoplankton and Water Mass Distribution along the South Brazil Shelf

PubMed Central

de Macedo-Soares, Luis Carlos Pinto; Garcia, Carlos Alberto Eiras; Freire, Andrea Santarosa; Muelbert, José Henrique

2014-01-01

Ichthyoplankton is an essential component of pelagic ecosystems, and environmental factors play an important role in determining its distribution. We have investigated simultaneous latitudinal and cross-shelf gradients in ichthyoplankton abundance to test the hypothesis that the large-scale distribution of fish larvae in the South Brazil Shelf is associated with water mass composition. Vertical plankton tows were collected between 21°27′ and 34°51′S at 107 stations, in austral late spring and early summer seasons. Samples were taken with a conical-cylindrical plankton net from the depth of chlorophyll maxima to the surface in deep stations, or from 10 m from the bottom to the surface in shallow waters. Salinity and temperature were obtained with a CTD/rosette system, which provided seawater for chlorophyll-a and nutrient concentrations. The influence of water mass on larval fish species was studied using Indicator Species Analysis, whereas environmental effects on the distribution of larval fish species were analyzed by Distance-based Redundancy Analysis. Larval fish species were associated with specific water masses: in the north, Sardinella brasiliensis was found in Shelf Water; whereas in the south, Engraulis anchoita inhabited the Plata Plume Water. At the slope, Tropical Water was characterized by the bristlemouth Cyclothone acclinidens. The concurrent analysis showed the importance of both cross-shelf and latitudinal gradients on the large-scale distribution of larval fish species. Our findings reveal that ichthyoplankton composition and large-scale spatial distribution are determined by water mass composition in both latitudinal and cross-shelf gradients. PMID:24614798

Large-scale ichthyoplankton and water mass distribution along the South Brazil Shelf.

PubMed

de Macedo-Soares, Luis Carlos Pinto; Garcia, Carlos Alberto Eiras; Freire, Andrea Santarosa; Muelbert, José Henrique

2014-01-01

Ichthyoplankton is an essential component of pelagic ecosystems, and environmental factors play an important role in determining its distribution. We have investigated simultaneous latitudinal and cross-shelf gradients in ichthyoplankton abundance to test the hypothesis that the large-scale distribution of fish larvae in the South Brazil Shelf is associated with water mass composition. Vertical plankton tows were collected between 21°27' and 34°51'S at 107 stations, in austral late spring and early summer seasons. Samples were taken with a conical-cylindrical plankton net from the depth of chlorophyll maxima to the surface in deep stations, or from 10 m from the bottom to the surface in shallow waters. Salinity and temperature were obtained with a CTD/rosette system, which provided seawater for chlorophyll-a and nutrient concentrations. The influence of water mass on larval fish species was studied using Indicator Species Analysis, whereas environmental effects on the distribution of larval fish species were analyzed by Distance-based Redundancy Analysis. Larval fish species were associated with specific water masses: in the north, Sardinella brasiliensis was found in Shelf Water; whereas in the south, Engraulis anchoita inhabited the Plata Plume Water. At the slope, Tropical Water was characterized by the bristlemouth Cyclothone acclinidens. The concurrent analysis showed the importance of both cross-shelf and latitudinal gradients on the large-scale distribution of larval fish species. Our findings reveal that ichthyoplankton composition and large-scale spatial distribution are determined by water mass composition in both latitudinal and cross-shelf gradients.

Effectiveness of Devices to Monitor Biofouling and Metals Deposition on Plumbing Materials Exposed to a Full-Scale Drinking Water Distribution System

PubMed Central

Garbin, Scott; Wylie, Jason; Krishna, K. C. Bal

2017-01-01

A Modified Robbins Device (MRD) was installed in a full-scale water distribution system to investigate biofouling and metal depositions on concrete, high-density polyethylene (HDPE) and stainless steel surfaces. Bulk water monitoring and a KIWA monitor (with glass media) were used to offline monitor biofilm development on pipe wall surfaces. Results indicated that adenosine triphosphate (ATP) and metal concentrations on coupons increased with time. However, bacterial diversities decreased. There was a positive correlation between increase of ATP and metal deposition on pipe surfaces of stainless steel and HDPE and no correlation was observed on concrete and glass surfaces. The shared bacterial diversity between bulk water and MRD was less than 20% and the diversity shared between the MRD and KIWA monitor was only 10%. The bacterial diversity on biofilm of plumbing material of MRD however, did not show a significant difference suggesting a lack of influence from plumbing material during early stage of biofilm development. PMID:28060947

Impact of water depth on the distribution of iGDGTs in the surface sediments from the northern South China Sea: applicability of TEX86 in marginal seas

NASA Astrophysics Data System (ADS)

Chen, Jiali; Hu, Pengju; Li, Xing; Yang, Yang; Song, Jinming; Li, Xuegang; Yuan, Huamao; Li, Ning; Lü, Xiaoxia

2018-03-01

The TEX 86 H paleothermometer on the base of isoprenoid glycerol dialkyl glycerol tetraethers (iGDGTs) has been widely applied to various marine settings to reconstruct past sea surface temperatures (SSTs). However, it remains uncertain how well this proxy reconstructs SSTs in marginal seas. In this study, we analyze the environmental factors governing distribution of iGDGTs in surface sediments to assess the applicability of TEX 86 H paleothermometer in the South China Sea (SCS). Individual iGDGT concentrations increase gradually eastwards. Redundancy analysis based on the relative abundance of an individual iGDGT compound and environmental parameters suggests that water depth is the most influential factor to the distribution of iGDGTs, because thaumarchaeota communities are water-depth dependent. Interestingly, the SST difference (Δ T) between TEX 86 H derived temperature and remote-sensing SST is less than 1°C in sediments with water depth>200 m, indicating that TEX 86 H was the robust proxy to trace the paleo-SST in the region if water depth is greater than 200 m.

Contents of the JPL Distributed Active Archive Center (DAAC) archive, version 2-91

NASA Technical Reports Server (NTRS)

Smith, Elizabeth A. (Editor); Lassanyi, Ruby A. (Editor)

1991-01-01

The Distributed Active Archive Center (DAAC) archive at the Jet Propulsion Laboratory (JPL) includes satellite data sets for the ocean sciences and global change research to facilitate multidisciplinary use of satellite ocean data. Parameters include sea surface height, surface wind vector, sea surface temperature, atmospheric liquid water, and surface pigment concentration. The Jet Propulsion Laboratory DAAC is an element of the Earth Observing System Data and Information System (EOSDIS) and will be the United States distribution site for the Ocean Topography Experiment (TOPEX)/POSEIDON data and metadata.

Phytoplankton distributions and their nutrient environment in the Eastern Bering Sea.

NASA Astrophysics Data System (ADS)

Zhang, J.; Nishitani, H.; Narita, H.; Jordan, R. W.

2004-12-01

After 1997, coccolithophorids blooms have been frequently observed by research vessels and satellites in the Eastern Bering Sea shelf, where diatoms have previously been dominate. Here, we present CTD, Chl-a, nutrient and phytoplankton data collected during cruises of the T/S Oshoro-Maru and R/V Mirai vessels from 2000 to 2003. Our goal is to refine the relation between phytoplankton distribution and water characteristics, and the controlling features of coccolithophorids blooms in the Eearstern Bering Sea. Samplings were carried out alone 166_E#8249;W from 55_E#8249;N to 59_E#8249;N. For cell counting, seawater samples were filtered through a 25-mm Millipore HA filter, and identification and counting of phytoplankton was performed with a scanning electron microscope. The scale of bloom and abundance of coccolithophorids were different in each year. The most dominant phytoplankton group was coccolithophorids in 2000, which agrees with the large bloom observed by satellite. In 2001, diatoms dominated at 70% and coccolithophorids accounted for 30% at 58, 58.5_E#8249;N. In 2002 and 2003, diatoms dominated at nearly 100% at all stations. Coccolithophorids abundance was nearly halted by pycnocline, since coccolithophorids existed in the middle shelf domain, which is known to be an area of cold-water pool distribution. The difference in density between the surface mixed layer and the cold-water pool gradually increased from 1980 to 2002, that is, seawater stratification in the middle shelf domain was strengthened as the result of the increased surface temperature and decreased salinity that have occurred recently. When stratification strengthens, the supply of nutrients to the surface from the cold-water pool is reduced. Consequently, coccolithophorids take precedence over diatoms in this condition. However, if the decreased salinity in the surface water depended on the increased river discharge, then the nutrients in the surface water would increase. River discharge has two peaks (spring and late summer) in one year (Chikita, 2001). Since river water contains high volumes of silicate and iron, an increase in river discharge would lead to the predominance of diatoms. The frequency and timing of storms, which influence the thickness of the surface mixed layer, may be another controlling factor of coccolithophorids blooms. In fact, there was a second peak in October 2000 and in August 2001. In 2000, the thickness of the surface mixed layer increased from July to September. Because the timing of storms and river discharges in summer controlled the stratification in the middle shelf domain, it greatly influenced the species_f composition of phytoplankton. In 2002 and 2003, the phytoplankton concetrations distribute peaks respectively at the south and north. The dominant classes are centric diatoms in the south, and is penate diatoms in the north, caused by defferent nutrients and temperature distribution. The sources of nutrients to the Estern bering Sea can be classified into three groups: up welling at the shelf edge, from the cold water pool, and from riverwater. The nutrients of surface water are high in the south and are low in the north, and dispense the diffenrent phytoplankton distribution.

Seismic seiches from the March 1964 Alaska earthquake: Chapter E in The Alaska earthquake, March 27, 1964: effects on hydrologic regimen

USGS Publications Warehouse

McGarr, Arthur; Vorhis, Robert C.

1968-01-01

Seismic seiches caused by the Alaska earthquake of March 27, 1964, were recorded at more than 850 surface-water gaging stations in North America and at 4 in Australia. In the United States, including Alaska and Hawaii, 763 of 6,435 gages registered seiches. Nearly all the seismic seiches were recorded at teleseismic distance. This is the first time such far-distant effects have been reported from surface-water bodies in North America. The densest occurrence of seiches was in States bordering the Gulf of Mexico. The seiches were recorded on bodies of water having a wide range in depth, width, and rate of flow. In a region containing many bodies of water, seiche distribution is more dependent on geologic and seismic factors than on hydro-dynamic ones. The concept that seiches are caused by the horizontal acceleration of water by seismic surface waves has been extended in this paper to show that the distribution of seiches is related to the amplitude distribution of short-period seismic surface waves. These waves have their greatest horizontal acceleration when their periods range from 5 to 15 seconds. Similarly, the water bodies on which seiches were recorded have low-order modes whose periods of oscillation also range from 5 to 15 seconds. Several factors seem to control the distribution of seiches. The most important is variations of thickness of low-rigidity sediments. This factor caused the abundance of seiches in the Gulf Coast area and along the edge of sedimentary overlaps. Major tectonic features such as thrust faults, basins, arches, and domes seem to control seismic waves and thus affect the distribution of seiches. Lateral refraction of seismic surface waves due to variations in local phase-velocity values was responsible for increase in seiche density in certain areas. For example, the Rocky Mountains provided a wave guide along which seiches were more numerous than in areas to either side. In North America, neither direction nor distance from the epicenter had any apparent effect on the distribution of seiches. Where seismic surface waves propagated into an area with thicker sediment, the horizontal acceleration increased about in proportion to the increasing thickness of the sediment. In the Mississippi Embayment however, where the waves emerged from high rigidity crust into the sediment, the horizontal acceleration increased near the edge of the embayment but decreased in the central part and formed a shadow zone. Because both seiches and seismic intensity depend on the horizontal acceleration from surface waves, the distribution of seiches may be used to map the seismic intensity that can be expected from future local earthquakes.

Virtual mission stage I: Implications of a spaceborne surface water mission

NASA Astrophysics Data System (ADS)

Clark, E. A.; Alsdorf, D. E.; Bates, P.; Wilson, M. D.; Lettenmaier, D. P.

2004-12-01

The interannual and interseasonal variability of the land surface water cycle depend on the distribution of surface water in lakes, wetlands, reservoirs, and river systems; however, measurements of hydrologic variables are sparsely distributed, even in industrialized nations. Moreover, the spatial extent and storage variations of lakes, reservoirs, and wetlands are poorly known. We are developing a virtual mission to demonstrate the feasibility of observing surface water extent and variations from a spaceborne platform. In the first stage of the virtual mission, on which we report here, surface water area and fluxes are emulated using simulation modeling over three continental scale river basins, including the Ohio River, the Amazon River and an Arctic river. The Variable Infiltration Capacity (VIC) macroscale hydrologic model is used to simulate evapotranspiration, soil moisture, snow accumulation and ablation, and runoff and streamflow over each basin at one-eighth degree resolution. The runoff from this model is routed using a linear transfer model to provide input to a much more detailed flow hydraulics model. The flow hydraulics model then routes runoff through various channel and floodplain morphologies at a 250 m spatial and 20 second temporal resolution over a 100 km by 500 km domain. This information is used to evaluate trade-offs between spatial and temporal resolutions of a hypothetical high resolution spaceborne altimeter by synthetically sampling the resultant model-predicted water surface elevations.

The Inferred Distribution of Liquid Water in Europa's Ice Shell: Implications for the Europa Lander Mission

NASA Astrophysics Data System (ADS)

Noviello, J. L.; Torrano, Z. A.; Rhoden, A.; Manga, M.

2017-12-01

A key objective of the Europa lander mission is to identify liquid water within 30 km of the lander (Europa Lander SDT report, 2017), to provide essential context with which to evaluate samples and enable assessment of Europa's overall habitability. To inform lander mission development, we utilize a model of surface feature formation that invokes liquid water within Europa's ice shell to map out the implied 3D distribution of liquid water and assess the likelihood of a lander to be within 30 km of liquid water given regional variability. Europa's surface displays a variety of microfeatures, also called lenticulae, including pits, domes, spots, and microchaos. A recent model by Manga and Michaut (2017) attributes these features to various stages in the thermal-mechanical evolution of liquid water intrusions (i.e. sills) within the ice shell, from sill emplacement to surface breaching (in the case of microchaos) to freezing of the sill. Pits are of particular interest because they appear only when liquid water is still present. Another key feature of the model is that the size of a microfeature at the surface is controlled by the depth of the sill. Hence, we can apply this model to regions of Europa that contain microfeatures to infer the size, depth, and spatial distribution of liquid water within the ice shell. We are creating a database of microfeatures that includes digitized, collated data from previous mapping efforts along with our own mapping study. We focus on images with 220 m/pixel resolution, which includes the regional mapping data sets. Analysis of a preliminary study area suggests that sills are typically located at depths of 2km or less from the surface. We will present analysis of the full database of microfeatures and the corresponding 3D distribution of sills implied by the model. Our preliminary analysis also shows that pits are clustered in some regions, consistent with previous results, although individual pits are also observed. We apply a statistical method, using the distribution of nearest neighbor distances, to quantify the degree of clustering and to determine the typical spatial separation among and between microfeature types. We will create density maps of microfeatures in several regions of Europa, and determine the likelihood that a lander will be within 30 km of a sill, assuming an arbitrary landing site.

Electric double layer at metal oxide surfaces:static properties of the cassiterite-water interface.

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

Vlcek, L.; Zhang, Z.; Machesky, M .L.

2007-03-24

The structure of water at the (110) surface of cassiterite ({alpha}-SnO{sub 2}) at ambient conditions was studied by means of molecular dynamics simulations and X-ray crystal truncation rod experiments and interpreted with the help of the revised MUSIC model of surface protonation. The interactions of the metal oxide in the simulations were described by a recently developed classical force field based on the SPC/E model of water. Two extreme cases of completely hydroxylated and nonhydroxylated surfaces were considered along with a mixed surface with 50% dissociation. To study the dependence of the surface properties on pH, neutral and negatively chargedmore » variants of the surfaces were constructed. Axial and lateral density distributions of water for different types of surfaces were compared to each other and to experimental axial density distributions found by X-ray experiments. Although significant differences were found between the structures of the studied interfaces, the axial distances between Sn and O atoms are very similar and therefore could not be clearly distinguished by the diffraction technique. The explanation of structures observed in the density distributions was provided by a detailed analysis of hydrogen bonding in the interfacial region. It revealed qualitatively different hydrating patterns formed at neutral hydroxylated and nonhydroxylated surfaces and suggested a preference for the dissociative adsorption of water. At negatively charged surfaces, however, the situation can be reversed by the electric field stabilizing a hydrogen bond network similar to that found at the neutral nonhydroxylated surface. Comparison with previously studied rutile ({alpha}-TiO{sub 2}) surfaces provided insight into the differences between the hydration of these two metal oxides, and an important role was ascribed to their different lattice parameters. A link to macroscopic properties was provided by the revised MUSIC surface protonation model. Explicit use of the Sn-O bond lengths based on ab initio calculations and H-bond configurations as inputs led to the prediction of a pH of zero net-proton induced surface charge (pH{sub pzc}) that agrees very well with those determined experimentally (about 4.4 at 298 K).« less

Electric double layer at metal oxide surfaces: Static properties of the cassiterite - Water Interface

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

Vlcek, Lukas; Zhang, Zhan; Machesky, Michael L.

2007-01-01

The structure of water at the (110) surface of cassiterite ({alpha}-SnO{sub 2}) at ambient conditions was studied by means of molecular dynamics simulations and X-ray crystal truncation rod experiments and interpreted with the help of the revised MUSIC model of surface protonation. The interactions of the metal oxide in the simulations were described by a recently developed classical force field based on the SPC/E model of water. Two extreme cases of completely hydroxylated and nonhydroxylated surfaces were considered along with a mixed surface with 50% dissociation. To study the dependence of the surface properties on pH, neutral and negatively chargedmore » variants of the surfaces were constructed. Axial and lateral density distributions of water for different types of surfaces were compared to each other and to experimental axial density distributions found by X-ray experiments. Although significant differences were found between the structures of the studied interfaces, the axial distances between Sn and O atoms are very similar and therefore could not be clearly distinguished by the diffraction technique. The explanation of structures observed in the density distributions was provided by a detailed analysis of hydrogen bonding in the interfacial region. It revealed qualitatively different hydrating patterns formed at neutral hydroxylated and nonhydroxylated surfaces and suggested a preference for the dissociative adsorption of water. At negatively charged surfaces, however, the situation can be reversed by the electric field stabilizing a hydrogen bond network similar to that found at the neutral nonhydroxylated surface. Comparison with previously studied rutile ({alpha}-TiO{sub 2}) surfaces provided insight into the differences between the hydration of these two metal oxides, and an important role was ascribed to their different lattice parameters. A link to macroscopic properties was provided by the revised MUSIC surface protonation model. Explicit use of the Sn-O bond lengths based on ab initio calculations and H-bond configurations as inputs led to the prediction of a pH of zero net-proton induced surface charge (pH{sub pzc}) that agrees very well with those determined experimentally (about 4.4 at 298 K).« less

Molecular dynamics of the water liquid-vapor interface

NASA Technical Reports Server (NTRS)

Wilson, M. A.; Pohorille, A.; Pratt, L. R.; MacElroy, R. D. (Principal Investigator)

1987-01-01

The results of molecular dynamics calculations on the equilibrium interface between liquid water and its vapor at 325 K are presented. For the TIP4P model of water intermolecular pair potentials, the average surface dipole density points from the vapor to the liquid. The most common orientations of water molecules have the C2 nu molecular axis roughly parallel to the interface. The distributions are quite broad and therefore compatible with the intermolecular correlations characteristic of bulk liquid water. All near-neighbor pairs in the outermost interfacial layers are hydrogen bonded according to the common definition adopted here. The orientational preferences of water molecules near a free surface differ from those near rigidly planar walls which can be interpreted in terms of patterns found in hexagonal ice 1. The mean electric field in the interfacial region is parallel to the mean polarization which indicates that attention cannot be limited to dipolar charge distributions in macroscopic descriptions of the electrical properties of this interface. The value of the surface tension obtained is 132 +/- 46 dyn/cm, significantly different from the value for experimental water of 68 dyn/cm at 325 K.

Character and spatial distribution of OH/H2O on the surface of the Moon seen by M3 on Chandrayaan-1.

PubMed

Pieters, C M; Goswami, J N; Clark, R N; Annadurai, M; Boardman, J; Buratti, B; Combe, J-P; Dyar, M D; Green, R; Head, J W; Hibbitts, C; Hicks, M; Isaacson, P; Klima, R; Kramer, G; Kumar, S; Livo, E; Lundeen, S; Malaret, E; McCord, T; Mustard, J; Nettles, J; Petro, N; Runyon, C; Staid, M; Sunshine, J; Taylor, L A; Tompkins, S; Varanasi, P

2009-10-23

The search for water on the surface of the anhydrous Moon had remained an unfulfilled quest for 40 years. However, the Moon Mineralogy Mapper (M3) on Chandrayaan-1 has recently detected absorption features near 2.8 to 3.0 micrometers on the surface of the Moon. For silicate bodies, such features are typically attributed to hydroxyl- and/or water-bearing materials. On the Moon, the feature is seen as a widely distributed absorption that appears strongest at cooler high latitudes and at several fresh feldspathic craters. The general lack of correlation of this feature in sunlit M3 data with neutron spectrometer hydrogen abundance data suggests that the formation and retention of hydroxyl and water are ongoing surficial processes. Hydroxyl/water production processes may feed polar cold traps and make the lunar regolith a candidate source of volatiles for human exploration.

Character and spatial distribution of OH/H2O on the surface of the moon seen by M3 on chandrayaan-1

USGS Publications Warehouse

Pieters, C.M.; Goswami, J.N.; Clark, R.N.; Annadurai, M.; Boardman, J.; Buratti, B.; Combe, J.-P.; Dyar, M.D.; Green, R.; Head, J.W.; Hibbitts, C.; Hicks, M.; Isaacson, P.; Klima, R.; Kramer, G.; Kumar, S.; Livo, E.; Lundeen, S.; Malaret, E.; McCord, T.; Mustard, J.; Nettles, J.; Petro, N.; Runyon, C.; Staid, M.; Sunshine, J.; Taylor, L.A.; Tompkins, S.; Varanasi, P.

2009-01-01

The search for water on the surface of the anhydrous Moon had remained an unfulfilled quest for 40 years. However, the Moon Mineralogy Mapper (M 3) on Chandrayaan-1 has recently detected absorption features near 2.8 to 3.0 micrometers on the surface of the Moon. For silicate bodies, such features are typically attributed to hydroxyl- and/or water-bearing materials. On the Moon, the feature is seen as a widely distributed absorption that appears strongest at cooler high latitudes and at several fresh feldspathic craters. The general lack of correlation of this feature in sunlit M3 data with neutron spectrometer hydrogen abundance data suggests that the formation and retention of hydroxyl and water are ongoing surficial processes. Hydroxyl/water production processes may feed polar cold traps and make the lunar regolith a candidate source of volatiles for human exploration.

Evapotranspiration and runoff from large land areas: Land surface hydrology for atmospheric general circulation models

NASA Technical Reports Server (NTRS)

Famiglietti, J. S.; Wood, Eric F.

1993-01-01

A land surface hydrology parameterization for use in atmospheric GCM's is presented. The parameterization incorporates subgrid scale variability in topography, soils, soil moisture and precipitation. The framework of the model is the statistical distribution of a topography-soils index, which controls the local water balance fluxes, and is therefore taken to represent the large land area. Spatially variable water balance fluxes are integrated with respect to the topography-soils index to yield our large topography-soils distribution, and interval responses are weighted by the probability of occurrence of the interval. Grid square averaged land surface fluxes result. The model functions independently as a macroscale water balance model. Runoff ratio and evapotranspiration efficiency parameterizations are derived and are shown to depend on the spatial variability of the above mentioned properties and processes, as well as the dynamics of land surface-atmosphere interactions.

Molecular dynamics simulations of the surface tension and structure of salt solutions and clusters.

PubMed

Sun, Lu; Li, Xin; Hede, Thomas; Tu, Yaoquan; Leck, Caroline; Ågren, Hans

2012-03-15

Sodium halides, which are abundant in sea salt aerosols, affect the optical properties of aerosols and are active in heterogeneous reactions that cause ozone depletion and acid rain problems. Interfacial properties, including surface tension and halide anion distributions, are crucial issues in the study of the aerosols. We present results from molecular dynamics simulations of water solutions and clusters containing sodium halides with the interatomic interactions described by a conventional force field. The simulations reproduce experimental observations that sodium halides increase the surface tension with respect to pure water and that iodide anions reach the outermost layer of water clusters or solutions. It is found that the van der Waals interactions have an impact on the distribution of the halide anions and that a conventional force field with optimized parameters can model the surface tension of the salt solutions with reasonable accuracy. © 2012 American Chemical Society

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.

[Heavy metals distribution characteristics and risk assessment of water below an electroplating factory].

PubMed

Hang, Xiao-Shuai; Wang, Huo-Yan; Zhou, Jian-Min

2008-10-01

Surface water and shallow groundwater within the flow of an electroplating factory was analyzed in order to study the resulting impact. The analysis method of ICP-AES was used to analyze content of zinc, manganese, chromium, copper and nickel in surface water and groundwater samples. The results indicate acidic pollutants of zinc, manganese, chromium, copper and nickel were discharged from the factory with concentrations of 1.34, 3.77, 28.1, 6.40 and 9.37 mg x L(-1), respectively; and pH was 2.32. They all exceeded permissible levels according to Integrated Wastewater Discharge Standard except zinc. Factory discharge is responsible for the longitudinal distribution characteristics of heavy metals in the stream water downstream from the factory. Heavy metals variations in the well water do not suggest they were affected by heavy metals in the stream, indicating that the migration rates of heavy metals in soils were relatively low. Risk assessment shows surface water quality significantly deteriorated. Nickel and manganese in the stream water exceeded the standard levels seriously, and chromium and copper in some samples were also above Grade III standard levels according to Environmental Quality Standard for Surface Water. Moreover, all studied heavy metals in 14 groundwater samples measured within drinking water standard, except manganese in 4 groundwater samples, which were Grade IV according to Quality Standard for Ground water.

Distributions of polycyclic aromatic hydrocarbons in surface waters, sediments and soils of Hangzhou City, China.

PubMed

Chen, Baoliang; Xuan, Xiaodong; Zhu, Lizhong; Wang, Jing; Gao, Yanzheng; Yang, Kun; Shen, Xueyou; Lou, Baofeng

2004-09-01

Ten polycyclic aromatic hydrocarbons (PAHs) were simultaneously measured in 17 surface water samples and 11 sediments of four water bodies, and 3 soils near the water-body bank in Hangzhou, China in December 2002. It was observed that the sum of PAHs concentrations ranged from 0.989 to 9.663 microg/L in surface waters, from 132.7 to 7343 ng/g dry weight in sediments, and from 59.71 to 615.8 ng/g dry weight in soils. The composition pattern of PAHs by ring size in water, sediment and soil were surveyed. Three-ring PAHs were dominated in surface waters and soils, meanwhile sediments were mostly dominated by four-ring PAHs. Furthermore, PAHs apparent distribution coefficients (K(d)) and solid f(oc)-normalized K(d) (e.g. K(oc)= K(d) / f(oc)) were calculated. The relationship between logK(oc) and logK(ow) of PAHs for field data on sediments and predicted values were compared. The sources of PAHs in different water bodies were evaluated by comparison of K (oc) values in sediments of the river downstream with that in soils. Hangzhou section of the Great Canal was heavily polluted by PAHs released from industrial wastewater in the past and now PAHs in sediment may serve as sources of PAHs in surface water. PAHs in Qiantang River were contributed from soil runoff. Municipal road runoff was mostly contributed to West Lake PAHs.

Quantifying Subsurface Water and Heat Distribution and its Linkage with Landscape Properties in Terrestrial Environment using Hydro-Thermal-Geophysical Monitoring and Coupled Inverse Modeling

NASA Astrophysics Data System (ADS)

Dafflon, B.; Tran, A. P.; Wainwright, H. M.; Hubbard, S. S.; Peterson, J.; Ulrich, C.; Williams, K. H.

2015-12-01

Quantifying water and heat fluxes in the subsurface is crucial for managing water resources and for understanding the terrestrial ecosystem where hydrological properties drive a variety of biogeochemical processes across a large range of spatial and temporal scales. Here, we present the development of an advanced monitoring strategy where hydro-thermal-geophysical datasets are continuously acquired and further involved in a novel inverse modeling framework to estimate the hydraulic and thermal parameter that control heat and water dynamics in the subsurface and further influence surface processes such as evapotranspiration and vegetation growth. The measured and estimated soil properties are also used to investigate co-interaction between subsurface and surface dynamics by using above-ground aerial imaging. The value of this approach is demonstrated at two different sites, one in the polygonal shaped Arctic tundra where water and heat dynamics have a strong impact on freeze-thaw processes, vegetation and biogeochemical processes, and one in a floodplain along the Colorado River where hydrological fluxes between compartments of the system (surface, vadose zone and groundwater) drive biogeochemical transformations. Results show that the developed strategy using geophysical, point-scale and aerial measurements is successful to delineate the spatial distribution of hydrostratigraphic units having distinct physicochemical properties, to monitor and quantify in high resolution water and heat distribution and its linkage with vegetation, geomorphology and weather conditions, and to estimate hydraulic and thermal parameters for enhanced predictions of water and heat fluxes as well as evapotranspiration. Further, in the Colorado floodplain, results document the potential presence of only periodic infiltration pulses as a key hot moment controlling soil hydro and biogeochemical functioning. In the arctic, results show the strong linkage between soil water content, thermal parameters, thaw layer thickness and vegetation distribution. Overall, results of these efforts demonstrate the value of coupling various datasets at high spatial and temporal resolution to improve predictive understanding of subsurface and surface dynamics.

Surface nanobubble nucleation dynamics during water-ethanol exchange

NASA Astrophysics Data System (ADS)

Chan, Chon U.; Ohl, Claus-Dieter

2015-11-01

Water-ethanol exchange has been a promising nucleation method for surface attached nanobubbles since their discovery. In this process, water and ethanol displace each other sequentially on a substrate. As the gas solubility is 36 times higher in ethanol than water, it was suggested that the exchange process leads to transient supersaturation and is responsible for the nanobubble nucleation. In this work, we visualize the nucleation dynamics by controllably mixing water and ethanol. It depicts the temporal evolution of the conventional exchange in a single field of view, detailing the conditions for surface nanobubble nucleation and the flow field that influences their spatial organization. This technique can also pattern surface nanobubbles with variable size distribution.

Polarization optics of the Brewster's dark patch visible on water surfaces versus solar height and sky conditions: theory, computer modeling, photography, and painting.

PubMed

Takács, Péter; Barta, András; Pye, David; Horváth, Gábor

2017-10-20

When the sun is near the horizon, a circular band with approximately vertically polarized skylight is formed at 90° from the sun, and this skylight is only weakly reflected from the region of the water surface around the Brewster's angle (53° from the nadir). Thus, at low solar heights under a clear sky, an extended dark patch is visible on the water surface when one looks toward the north or south quarter perpendicular to the solar vertical. In this work, we study the radiance distribution of this so-called Brewster's dark patch (BDP) in still water as functions of the solar height and sky conditions. We calculate the pattern of reflectivity R of a water surface for a clear sky and obtain from this idealized situation the shape of the BDP. From three full-sky polarimetric pictures taken about a clear, a partly cloudy, and an overcast sky, we determine the R pattern and compose from that synthetic color pictures showing how the radiance distribution of skylight reflected at the water surface and the BDPs would look under these sky conditions. We also present photographs taken without a linearly polarizing filter about the BDP. Finally, we show a 19th century painting on which a river is seen with a dark region of the water surface, which can be interpreted as an artistic illustration of the BDP.

Reuse of spent granular activated carbon for organic micro-pollutant removal from treated wastewater.

PubMed

Hu, Jingyi; Shang, Ran; Heijman, Bas; Rietveld, Luuk

2015-09-01

Spent granular activated carbons (sGACs) for drinking water treatments were reused via pulverizing as low-cost adsorbents for micro-pollutant adsorption from a secondary treated wastewater effluent. The changes of physicochemical characteristics of the spent carbons in relation to the fresh carbons were determined and were correlated to the molecular properties of the respective GAC influents (i.e. a surface water and a groundwater). Pore size distribution analysis showed that the carbon pore volume decreased over a wider size range due to preloading by surface water, which contains a broader molecular weight distribution of organic matter in contrast to the groundwater. However, there was still considerable capacity available on the pulverized sGACs for atrazine adsorption in demineralized water and secondary effluent, and this was particularly the case for the groundwater spent GAC. However, as compared to the fresh counterparts, the decreased surface area and the induced surface acidic groups on the pulverized sGACs contributed both to the lower uptake and the more impeded adsorption kinetic of atrazine in the demineralized water. Nonetheless, the pulverized sGACs, especially the one preloaded by surface water, was less susceptible to adsorption competition in the secondary effluent, due to its negatively charged surface which can repulse the accessibility of the co-present organic matter. This suggests the reusability of the drinking water spent GACs for micro-pollutant adsorption in the treated wastewater. Copyright © 2015 Elsevier Ltd. All rights reserved.

The Large Scale Distribution of Water Ice in the Polar Regions of the Moon

NASA Astrophysics Data System (ADS)

Jordan, A.; Wilson, J. K.; Schwadron, N.; Spence, H. E.

2017-12-01

For in situ resource utilization, one must know where water ice is on the Moon. Many datasets have revealed both surface deposits of water ice and subsurface deposits of hydrogen near the lunar poles, but it has proved difficult to resolve the differences among the locations of these deposits. Despite these datasets disagreeing on how deposits are distributed on small scales, we show that most of these datasets do agree on the large scale distribution of water ice. We present data from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on the Lunar Reconnaissance Orbiter (LRO), LRO's Lunar Exploration Neutron Detector (LEND), the Neutron Spectrometer on Lunar Prospector (LPNS), LRO's Lyman Alpha Mapping Project (LAMP), LRO's Lunar Orbiter Laser Altimeter (LOLA), and Chandrayaan-1's Moon Mineralogy Mapper (M3). All, including those that show clear evidence for water ice, reveal surprisingly similar trends with latitude, suggesting that both surface and subsurface datasets are measuring ice. All show that water ice increases towards the poles, and most demonstrate that its signature appears at about ±70° latitude and increases poleward. This is consistent with simulations of how surface and subsurface cold traps are distributed with latitude. This large scale agreement constrains the origin of the ice, suggesting that an ancient cometary impact (or impacts) created a large scale deposit that has been rendered locally heterogeneous by subsequent impacts. Furthermore, it also shows that water ice may be available down to ±70°—latitudes that are more accessible than the poles for landing.

Experimental evaluation of theoretical sea surface reflectance factors relevant to above-water radiometry.

PubMed

Zibordi, Giuseppe

2016-03-21

Determination of the water-leaving radiance L_W through above-water radiometry requires knowledge of accurate reflectance factors ρ of the sea surface. Publicly available ρ relevant to above-water radiometry include theoretical data sets generated: i. by assuming a sky radiance distribution accounting for aerosols and multiple scattering, but neglecting polarization, and quantifying sea surface effects through Cox-Munk wave slope statistics; or differently ii. accounting for polarization, but assuming an ideal Rayleigh sky radiance distribution, and quantifying sea surface effects through modeled wave elevation and slope variance spectra. The impact on above-water data products of differences between those factors ρ was quantified through comparison of L_W from the Ocean Color component of the Aerosol Robotic Network (AERONET-OC) with collocated L_W from in-water radiometry. Results from the analysis of radiance measurements from the sea performed with 40 degrees viewing angle and 90 degrees azimuth offset with respect to the sun plane, indicated a slightly better agreement between above- and in-water L_W determined for wind speeds tentatively lower than 4 m s^-1 with ρ computed accounting for aerosols, multiple scattering and Cox-Munk surfaces. Nevertheless, analyses performed by partitioning the investigated data set also indicated that actual ρ values would exhibit dependence on sun zenith comprised between those characterizing the two sets of reflectance factors.

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.

Surface-water-quality assessment of the Yakima River basin, Washington; distribution of pesticides and other organic compounds in water, sediment, and aquatic biota, 1987-91; with a section on dissolved organic carbon in the Yakima River basin

USGS Publications Warehouse

Rinella, Joseph F.; McKenzie, Stuart W.; Crawford, J. Kent; Foreman, William T.; Fuhrer, Gregory J.; Morace, Jennifer L.; Aiken, George R.

1999-01-01

During 1987-91, chemical data were collected for pesticides and other organic compounds in surface water, streambed sediment, suspended sediment, agricultural soil, and aquatic biota to determine the occurrence, distribution, transport, and fate of organic compounds in the Yakima River basin in Washington. The report describes the chemical and physical properties of the compounds most frequently detected in the water column; organochlorine compounds including DDT, organophosphorus compounds, thiocarbamate and sulfite compounds, acetamide and triazine compounds, and chlorophenoxy-acetic acid and benzoic compounds. Concentrations are evaluated relative to chronic-toxicity water quality criteria and guidelines for the protection of human health and freshwater aquatic life.

The investigation of atmospheric deposition distribution of organochlorine pesticides (OCPs) in Turkey

NASA Astrophysics Data System (ADS)

Cindoruk, S. Sıddık; Tasdemir, Yücel

2014-04-01

Atmospheric deposition is a significant pollution source leading to contamination of remote and clean sites, surface waters and soils. Since persistent organic pollutants (POPs) stay in atmosphere without any degradation, they can be transported and deposited to clean surfaces. Organochlorine pesticides are an important group of POPs which have toxic and harmful effects to living organisms and environment. Therefore, atmospheric deposition levels and characteristics are of importance to determine the pollution quantity of water and soil surfaces in terms of POPs. This study reports the distribution quantities of atmospheric deposition including bulk, dry, wet and air-water exchange of particle and gas phase OCPs as a result of 1-year sampling campaign. Atmospheric deposition distribution showed that the main mechanism for OCPs deposition is wet processes with percentage of 69 of total deposition. OCP compounds' deposition varied according to atmospheric concentration and deposition mechanism. HCH compounds were dominant pesticide species for all deposition mechanisms. HCH deposition constituted the 65% of Σ10OCPs.

Molecular Dynamics of a Water-Lipid Bilayer Interface

NASA Technical Reports Server (NTRS)

Wilson, Michael A.; Pohorille, Andrew

1994-01-01

We present results of molecular dynamics simulations of a glycerol 1-monooleate bilayer in water. The total length of analyzed trajectories is 5ns. The calculated width of the bilayer agrees well with the experimentally measured value. The interior of the membrane is in a highly disordered fluid state. Atomic density profile, orientational and conformational distribution functions, and order parameters indicate that disorder increases toward the center of the bilayer. Analysis of out-of-plane thermal fluctuations of the bilayer surfaces occurring at the time scale of the present calculations reveals that the distribution of modes agrees with predictions of the capillary wave model. Fluctuations of both bilayer surfaces are uncorrelated, yielding Gaussian distribution of instantaneous widths of the membrane. Fluctuations of the width produce transient thinning defects in the bilayer which occasionally span almost half of the membrane. The leading mechanism of these fluctuations is the orientational and conformational motion of head groups rather than vertical motion of the whole molecules. Water considerably penetrates the head group region of the bilayer but not its hydrocarbon core. The total net excess dipole moment of the interfacial water points toward the aqueous phase, but the water polarization profile is non-monotonic. Both water and head groups significantly contribute to the surface potential across the interface. The calculated sign of the surface potential is in agreement with that from experimental measurements, but the value is markedly overestimated. The structural and electrical properties of the water-bilayer system are discussed in relation to membrane functions, in particular transport of ions and nonelectrolytes across membranes.

Regular patterns of Cs-137 distribution in natural conjugated elementary landscapes as a result of a balanced surface and depth water migration

NASA Astrophysics Data System (ADS)

Korobova, Elena; Romanov, Sergey

2016-04-01

Distribution of artificial radionuclides in the environment has long been used successfully for revealing migration pathways of their stable analogues. Migration of water in natural conjugated elementary landscapes characterizing the system of top-slope-resulting depression, has a specific structure and the radionuclide tracer is inevitably reflecting it by specific sorption and exchange processes. Other important issues are the concentration levels and the difference in characteristic time of chemical element dispersion. Modern biosphere has acquired its sustainable structure within a long period of time and is formed by basic macroelements allowing the water soluble portion of elements functioning as activators of chemical exchange. Water migration is controlled by gravitation, climate and relief while fixation depends upon the parameters of surfaces and chemical composition. The resulting structure depends on specificity and duration of the process. The long-term redistribution of chemical elements in terrestrial environment has led to a distinct geochemical structure of conjugated landscapes with a specific geometry of redistribution and accumulation of chemical elements. Migration of the newly born anthropogenic radionuclides followed natural pathways in biosphere. The initial deposition of the Chernobyl's radionuclides within the elementary landscape-geochemical system was even by condition of aerial deposition. But further exchange process is controlled by the strength of fixation and migration ability of the carriers. Therefore patterns of spatial distribution of artificial radionuclides in natural landscapes are considerably different as compared to those of the long-term forming the basic structure of chemical fields in biosphere. Our monitoring of Cs-137 radial and lateral distribution in the test plots characterizing natural undisturbed conjugated elementary landscapes performed in the period from 2005 until now has revealed a stable and specifically polycentric structure of radiocesium distribution believed to reflect the character of radial and lateral water body migration and a high sensitivity of water distribution to surface parameters. This leads to an unusual wavy type of Cs-137 distribution down, along and across all the slopes examined for surface Cs-137 activity at every measured point. The finding is believed to have an important practical outcome allowing much more detailed evaluation of micronutrients distribution and optimization of their application.

Distribution of polycyclic aromatic hydrocarbons in southern Chesapeake Bay surface water: Evaluation of three methods for determining freely dissolved water concentrations

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

Gustafson, K.E.; Dickhut, R.M.

1997-03-01

Gas sparging, semipermeable-membrane devices (SPMDs), and filtration with sorption of dissolved polycyclic aromatic hydrocarbons (PAHs) to XAD-2 resin were evaluated for determining the concentrations of freely dissolved PAHs in estuarine waters of southern Chesapeake Bay at sites ranging from rural to urban and highly industrialized. Gas sparging had significant sampling artifacts due to particle scavenging by rising bubbles, and SPMDs were kinetically limited for four-ring and larger PAHs relative to short-term temporal changes in water concentrations. Filtration with sorption of the dissolved contaminant fraction to XAD-2 resin was found to be the most accurate and feasible method for determining concentrationsmore » of freely dissolved PAHs in estuarine water. Concentrations and distribution coefficients of dissolved and particulate PAHs were measured using the filtration/XAD-2 method. Concentrations of PAHs in surface waters of southern Chesapeake Bay were higher than those reported for the northern bay; concentrations in the Elizabeth River were elevated relative to all other sites. A gradient for particulate PAHs was observed from urban to remote sites. No seasonal trends were observed in dissolved or particle-bound PAH fractions at any site. Distributions of dissolved and particulate PAHs in surface waters of the Chesapeake Bay are near equilibrium at all locations and during all seasons.« less

The conservative behavior of dissolved organic carbon in surface waters of the southern Chukchi Sea, Arctic Ocean, during early summer

PubMed Central

Tanaka, Kazuki; Takesue, Nobuyuki; Nishioka, Jun; Kondo, Yoshiko; Ooki, Atsushi; Kuma, Kenshi; Hirawake, Toru; Yamashita, Youhei

2016-01-01

The spatial distribution of dissolved organic carbon (DOC) concentrations and the optical properties of dissolved organic matter (DOM) determined by ultraviolet-visible absorbance and fluorescence spectroscopy were measured in surface waters of the southern Chukchi Sea, western Arctic Ocean, during the early summer of 2013. Neither the DOC concentration nor the optical parameters of the DOM correlated with salinity. Principal component analysis using the DOM optical parameters clearly separated the DOM sources. A significant linear relationship was evident between the DOC and the principal component score for specific water masses, indicating that a high DOC level was related to a terrigenous source, whereas a low DOC level was related to a marine source. Relationships between the DOC and the principal component scores of the surface waters of the southern Chukchi Sea implied that the major factor controlling the distribution of DOC concentrations was the mixing of plural water masses rather than local production and degradation. PMID:27658444

An algorithm for modeling entrainment and naturally and chemically dispersed oil droplet size distribution under surface breaking wave conditions.

PubMed

Li, Zhengkai; Spaulding, Malcolm L; French-McCay, Deborah

2017-06-15

A surface oil entrainment model and droplet size model have been developed to estimate the flux of oil under surface breaking waves. Both equations are expressed in dimensionless Weber number (We) and Ohnesorge number (Oh, which explicitly accounts for the oil viscosity, density, and oil-water interfacial tension). Data from controlled lab studies, large-scale wave tank tests, and field observations have been used to calibrate the constants of the two independent equations. Predictions using the new algorithm compared well with the observed amount of oil removed from the surface and the sizes of the oil droplets entrained in the water column. Simulations with the new algorithm, implemented in a comprehensive spill model, show that entrainment rates increase more rapidly with wind speed than previously predicted based on the existing Delvigne and Sweeney's (1988) model, and a quasi-stable droplet size distribution (d<~50μm) is developed in the near surface water. Copyright © 2017 Elsevier Ltd. All rights reserved.

Groundwater surface water interactions and the role of phreatophytes in identifying recharge zones

USDA-ARS?s Scientific Manuscript database

Groundwater and surface water interactions within riparian corridors impact the distribution of phreatophytes that tap into groundwater stores. The changes in canopy area of phreatophytes over time is related to changes in depth to groundwater, distance from a stream or river, and hydrologic soil gr...

Perfluorinated Chemicals in Surface Waters and Sediments from Northwest Georgia, USA, and Their Bioaccumulation in Lumbriculus variegatus

EPA Science Inventory

Concentrations of perfluorinated chemicals (PFCs) were measured in surface waters and sediments from the Coosa River watershed in northwest Georgia, USA, to examine their distribution downstream of a suspected source. Samples from eight sites were analyzed using liquid chromatogr...

Effects of protein conformational motions in the native form and non-uniform distribution of electrostatic interaction sites on interfacial water

NASA Astrophysics Data System (ADS)

Pal, Somedatta; Bandyopadhyay, Sanjoy

2013-07-01

Protein-water interactions and their influence on surrounding water is a long-standing problem. Despite its importance, the origin of differential water behavior at the protein surface is still elusive. We have performed molecular simulations of the protein barstar in aqueous medium. Efforts have been made to explore how the conformational motions of the protein segments in the native form and the heterogeneous electrostatic interactions with the polar and charged groups of the protein affect the interfacial water properties. The calculations reveal that reduced dimension of the hydration layer on freezing the protein's degrees of freedom does not modify the heterogeneous water distributions around the protein. However, turning off the protein-water electrostatic contribution leads to non-preferential near-uniform water arrangements at the surface. It is further shown that with protein-water electrostatic interactions turned on, the local structuring of water molecules around the segments are correlated with their degree of exposure to the solvent.

Occurrence and distribution pattern of acidic pharmaceuticals in surface water, wastewater, and sediment of the Msunduzi River, Kwazulu-Natal, South Africa.

PubMed

Agunbiade, Foluso O; Moodley, Brenda

2016-01-01

The paucity of information on the occurrence of pharmaceuticals in the environment in African countries led the authors to investigate 8 acidic pharmaceuticals (4 antipyretics, 3 antibiotics, and 1 lipid regulator) in wastewater, surface water, and sediments from the Msunduzi River in the province of KwaZulu-Natal, South Africa, using solid-phase extraction (SPE) and liquid chromatography-mass spectrometry (LC/MS). The method recoveries, limits of detection (LOD), and limits of quantification were determined. The method recoveries were 58.4% to 103%, and the LODs ranged between 1.16 ng/L and 29.1 ng/L for water and between 0.58 ng/g and 14.5 ng/g for sediment. The drugs were all present in wastewater and in most of the surface water and sediment samples. Aspirin was the most abundant pharmaceutical observed, 118 ± 0.82 μg/L in wastewater influent, and the most observed antibiotic was nalidixic acid (25.2-29.9 μg/L in wastewater); bezafibrate was the least observed. The distribution pattern of the antipyretic in water indicates more impact in suburban sites. The solid-liquid partitioning of the pharmaceuticals between sediment and water, measured as the distribution coefficient (log KD ) gave an average accumulation magnitude of 10× to 32× in sediments than in water. The downstream distribution patterns for both water and sediment indicate discharge contributions from wastewater, agricultural activities, domestic waste disposal, and possible sewer system leakages. Although concentrations of the pharmaceuticals were comparable with those obtained from some other countries, the contamination of the present study site with pharmaceuticals has been over time and continues at present, making effective management and control necessary. © 2015 SETAC.

Large Scale Ice Water Path and 3-D Ice Water Content

DOE Data Explorer

Liu, Guosheng

2008-01-15

Cloud ice water concentration is one of the most important, yet poorly observed, cloud properties. Developing physical parameterizations used in general circulation models through single-column modeling is one of the key foci of the ARM program. In addition to the vertical profiles of temperature, water vapor and condensed water at the model grids, large-scale horizontal advective tendencies of these variables are also required as forcing terms in the single-column models. Observed horizontal advection of condensed water has not been available because the radar/lidar/radiometer observations at the ARM site are single-point measurement, therefore, do not provide horizontal distribution of condensed water. The intention of this product is to provide large-scale distribution of cloud ice water by merging available surface and satellite measurements. The satellite cloud ice water algorithm uses ARM ground-based measurements as baseline, produces datasets for 3-D cloud ice water distributions in a 10 deg x 10 deg area near ARM site. The approach of the study is to expand a (surface) point measurement to an (satellite) areal measurement. That is, this study takes the advantage of the high quality cloud measurements at the point of ARM site. We use the cloud characteristics derived from the point measurement to guide/constrain satellite retrieval, then use the satellite algorithm to derive the cloud ice water distributions within an area, i.e., 10 deg x 10 deg centered at ARM site.

Fluoride: A naturally-occurring health hazard in drinking-water resources of Northern Thailand.

PubMed

Chuah, C Joon; Lye, Han Rui; Ziegler, Alan D; Wood, Spencer H; Kongpun, Chatpat; Rajchagool, Sunsanee

2016-03-01

In Northern Thailand, incidences of fluorosis resulting from the consumption of high-fluoride drinking-water have been documented. In this study, we mapped the high-fluoride endemic areas and described the relevant transport processes of fluoride in enriched waters in the provinces of Chiang Mai and Lamphun. Over one thousand surface and sub-surface water samples including a total of 995 collected from shallow (depth: ≤ 30 m) and deep (> 30 m) wells were analysed from two unconnected high-fluoride endemic areas. At the Chiang Mai site, 31% of the shallow wells contained hazardous levels (≥ 1.5 mg/L) of fluoride, compared with the 18% observed in the deep wells. However, at the Lamphun site, more deep wells (35%) contained water with at least 1.5mg/L fluoride compared with the shallow wells (7%). At the Chiang Mai site, the high-fluoride waters originate from a nearby geothermal field. Fluoride-rich geothermal waters are distributed across the area following natural hydrological pathways of surface and sub-surface water flow. At the Lamphun site, a well-defined, curvilinear high-fluoride anomalous zone, resembling that of the nearby conspicuous Mae Tha Fault, was identified. This similarity provides evidence of the existence of an unmapped, blind fault as well as its likely association to a geogenic source (biotite-granite) of fluoride related to the faulted zone. Excessive abstraction of ground water resources may also have affected the distribution and concentration of fluoride at both sites. The distribution of these high-fluoride waters is influenced by a myriad of complex natural and anthropogenic processes which thus created a challenge for the management of water resources for safe consumption in affected areas. The notion of clean and safe drinking water can be found in deeper aquifers is not necessarily true. Groundwater at any depth should always be tested before the construction of wells. Copyright © 2015 Elsevier B.V. All rights reserved.

First UAV Measurements of Entrainment Layer Fluxes with Coupled Cloud Property Measurements

NASA Astrophysics Data System (ADS)

Thomas, R. M.; Praveen, P. S.; Wilcox, E. M.; Pistone, K.; Bender, F.; Ramanathan, V.

2012-12-01

This study details entrainment flux measurements made from a lightweight unmanned aerial vehicle (UAV) containing turbulent water vapor flux instrumentation (Thomas et al., 2012). The system was flown for 26 flights during the Cloud, Aerosol, Radiative forcing, Dynamics EXperiment (CARDEX) in the Maldives in March 2012 to study interrelationships between entrainment, aerosols, water budget, cloud microphysics and radiative fluxes in a trade wind cumulus cloud regime. A major advantage of using this lightweight, precision autopiloted UAV system with scientific telemetry is the ability to target small-scale features in the boundary layer, such as an entrainment layer, with minimal aircraft induced disruption. Results are presented from two UAVs flown in stacked formation: one UAV situated in-cloud measuring cloud-droplet size distribution spectra and liquid water content, and another co-located 100m above measuring turbulent properties and entrainment latent heat flux (λEE). We also show latent heat flux and turbulence measurements routinely made at the entrainment layer base and altitudes from the surface up to 4kft. Ratios of λEE to corresponding surface tower values (λES) display a bimodal frequency distribution with ranges 0.22-0.53 and 0.79-1.5, with occasional events >7. Reasons for this distribution are discussed drawing upon boundary layer and free tropospheric dynamics and meteorology, turbulence length scales, surface conditions, and cloud interactions. Latent heat flux profiles are combined with in-cloud UAV Liquid Water Content (LWC) data and surface based Liquid Water Path (LWP) and Precipitable Water Vapor (PWV) measurements to produce observationally constrained vertical water budgets, providing insights into diurnal coupling of λEE and λES. Observed λEE, λES, water budgets, and cloud microphysical responses to entrainment are then contextualized with respect to measured aerosol loading profiles and airmass history.

Numerical Simulations of Martian Fog Formation in the Low Latitudes

NASA Astrophysics Data System (ADS)

Inada, A.

2002-09-01

The formation of Martian surface fog is simulated by a one-dimensional model including the micro-physical processes of heterogeneous nucleation, condensation, and sublimation. The model includes diurnal cycle of water vapor in the 1 km surface layer which is spatially resolved. The results show that the column density of water ice in fog strongly depends on the water vapor density near the surface. If the mixing ratio of water vapor is 300 ppm near the surface, the simulations show that a thin fog layer appears with a maximum column density of 0.145 precipitable microns. If the mixing ratio is 600 ppm, the value measured by the Mars Pathfinder, the column density of water ice reaches 0.75 precipitable microns. It is also found that if the boundary layer is strongly turbulent the total amount of ice formed is small, since the ice particles are transported to the unsaturated higher atmospheric layers and sublimate there. Fog particles, which are large enough to precipitate to the lower atmosphere play a significant role in determining the altitude distribution of water vapor. It is noteworthy that the size distribution of all of the aerosols has two peaks once fog appears. This is because nucleation on large dust particles is so much faster than on the small ones, that the small dust particles are hardly coated by ice. The simulations assume an initial dust distribution with effective radius of 1.6 microns. Once fog forms this peak remains and is populated with particles with little water ice. A secondary peak is formed at about 10 microns corresponding to particles which are mostly water ice. This research was carried out under the partial support of JSPS Postdoctoral Fellowships for Research Abroad.

Contents of the NASA ocean data system archive, version 11-90

NASA Technical Reports Server (NTRS)

Smith, Elizabeth A. (Editor); Lassanyi, Ruby A. (Editor)

1990-01-01

The National Aeronautics and Space Administration (NASA) Ocean Data System (NODS) archive at the Jet Propulsion Laboratory (JPL) includes satellite data sets for the ocean sciences and global-change research to facilitate multidisciplinary use of satellite ocean data. Parameters include sea-surface height, surface-wind vector, sea-surface temperature, atmospheric liquid water, and surface pigment concentration. NODS will become the Data Archive and Distribution Service of the JPL Distributed Active Archive Center for the Earth Observing System Data and Information System (EOSDIS) and will be the United States distribution site for Ocean Topography Experiment (TOPEX)/POSEIDON data and metadata.

REGRESSION ANALYSIS OF SEA-SURFACE-TEMPERATURE PATTERNS FOR THE NORTH PACIFIC OCEAN.

DTIC Science & Technology

SEA WATER, *SURFACE TEMPERATURE, *OCEANOGRAPHIC DATA, PACIFIC OCEAN, REGRESSION ANALYSIS , STATISTICAL ANALYSIS, UNDERWATER EQUIPMENT, DETECTION, UNDERWATER COMMUNICATIONS, DISTRIBUTION, THERMAL PROPERTIES, COMPUTERS.

Water shortage risk assessment considering large-scale regional transfers: a copula-based uncertainty case study in Lunan, China.

PubMed

Gao, Xueping; Liu, Yinzhu; Sun, Bowen

2018-06-05

The risk of water shortage caused by uncertainties, such as frequent drought, varied precipitation, multiple water resources, and different water demands, brings new challenges to the water transfer projects. Uncertainties exist for transferring water and local surface water; therefore, the relationship between them should be thoroughly studied to prevent water shortage. For more effective water management, an uncertainty-based water shortage risk assessment model (UWSRAM) is developed to study the combined effect of multiple water resources and analyze the shortage degree under uncertainty. The UWSRAM combines copula-based Monte Carlo stochastic simulation and the chance-constrained programming-stochastic multiobjective optimization model, using the Lunan water-receiving area in China as an example. Statistical copula functions are employed to estimate the joint probability of available transferring water and local surface water and sampling from the multivariate probability distribution, which are used as inputs for the optimization model. The approach reveals the distribution of water shortage and is able to emphasize the importance of improving and updating transferring water and local surface water management, and examine their combined influence on water shortage risk assessment. The possible available water and shortages can be calculated applying the UWSRAM, also with the corresponding allocation measures under different water availability levels and violating probabilities. The UWSRAM is valuable for mastering the overall multi-water resource and water shortage degree, adapting to the uncertainty surrounding water resources, establishing effective water resource planning policies for managers and achieving sustainable development.

A summary of selected early results from the ERTS-1 menhaden experiment

NASA Technical Reports Server (NTRS)

Stevenson, W. H. (Principal Investigator); Kemmerer, A. J.; Benigno, J. A.; Reese, G. B.; Minkler, F. C.

1973-01-01

The author has identified the following significant results. Imagery from ERTS-1 satellite was used in conjunction with aerial photographically-sensed menhaden distribution information, sea truth oceanographic measurements, and commercial fishing information from a 8685 square kilometer study area in the north-central portion of the Gulf of Mexico to demonstrate relationships between selected oceanographic parameters and menhaden distribution, ERTS-1 imagery and menhaden distribution, and ERTS-1 imagery and oceanographic parameters. ERTS-1, MSS band 5 imagery density levels correlated with photographically detected menhaden distribution patterns and could be explained based on sea truth Secchi disc transparency and water depth measurements. These two parameters, together with surface salinity, Forel-Ule color, and chlorophyll-a also were found to correlate significantly with menhaden distribution. Eight empirical models were developed which provided menhaden distribution predictions for the study area on combinations of Secchi disc transparency, water depth, surface salinity, and Forel-Ule color measurements.

Contaminant transport from point source on water surface in open channel flow with bed absorption

NASA Astrophysics Data System (ADS)

Guo, Jinlan; Wu, Xudong; Jiang, Weiquan; Chen, Guoqian

2018-06-01

Studying solute dispersion in channel flows is of significance for environmental and industrial applications. Two-dimensional concentration distribution for a most typical case of a point source release on the free water surface in a channel flow with bed absorption is presented by means of Chatwin's long-time asymptotic technique. Five basic characteristics of Taylor dispersion and vertical mean concentration distribution with skewness and kurtosis modifications are also analyzed. The results reveal that bed absorption affects both the longitudinal and vertical concentration distributions and causes the contaminant cloud to concentrate in the upper layer. Additionally, the cross-sectional concentration distribution shows an asymptotic Gaussian distribution at large time which is unaffected by the bed absorption. The vertical concentration distribution is found to be nonuniform even at large time. The obtained results are essential for practical implements with strict environmental standards.

Molecular dynamics studies of interfacial water at the alumina surface.

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

Argyris, Dr. Dimitrios; Ho, Thomas; Cole, David

2011-01-01

Interfacial water properties at the alumina surface were investigated via all-atom equilibrium molecular dynamics simulations at ambient temperature. Al-terminated and OH-terminated alumina surfaces were considered to assess the structural and dynamic behavior of the first few hydration layers in contact with the substrates. Density profiles suggest water layering up to {approx}10 {angstrom} from the solid substrate. Planar density distribution data indicate that water molecules in the first interfacial layer are organized in well-defined patterns dictated by the atomic terminations of the alumina surface. Interfacial water exhibits preferential orientation and delayed dynamics compared to bulk water. Water exhibits bulk-like behavior atmore » distances greater than {approx}10 {angstrom} from the substrate. The formation of an extended hydrogen bond network within the first few hydration layers illustrates the significance of water?water interactions on the structural properties at the interface.« less

Vertical counterflow evaporative cooler

DOEpatents

Bourne, Richard C.; Lee, Brian Eric; Callaway, Duncan

2005-01-25

An evaporative heat exchanger having parallel plates that define alternating dry and wet passages. A water reservoir is located below the plates and is connected to a water distribution system. Water from the water distribution system flows through the wet passages and wets the surfaces of the plates that form the wet passages. Air flows through the dry passages, mixes with air below the plates, and flows into the wet passages before exiting through the top of the wet passages.

Storm water runoff concentration matrix for urban areas.

PubMed

Göbel, P; Dierkes, C; Coldewey, W G

2007-04-01

The infrastructure (roads, sidewalk, commercial and residential structures) added during the land development and urbanisation process is designed to collect precipitation and convey it out of the watershed, typically in existing surface water channels, such as streams and rivers. The quality of surface water, seepage water and ground water is influenced by pollutants that collect on impervious surfaces and that are carried by urban storm water runoff. Heavy metals, e.g. lead (Pb), zinc (Zn), copper (Cu), cadmium (Cd), polycyclic aromatic hydrocarbons (PAH), mineral oil hydrocarbons (MOH) and readily soluble salts in runoff, contribute to the degradation of water. An intensive literature search on the distribution and concentration of the surface-dependent runoff water has been compiled. Concentration variations of several pollutants derived from different surfaces have been averaged. More than 300 references providing about 1300 data for different pollutants culminate in a representative concentration matrix consisting of medians and extreme values. This matrix can be applied to long-term valuations and numerical modelling of storm water treatment facilities.

Comparison between Synthesized Lead Particles and Lead Solids Formed on Surfaces in Real Drinking Water Distribution Systems

EPA Science Inventory

The objective of this work is to compare the properties of lead solids formed during bench-scale precipitation experiments to solids found on lead pipe removed from real drinking water distribution systems and metal coupons used in pilot scale corrosion testing. Specifically, so...

Numerical simulation of hydrodynamic processes beneath a wind-driven water surface

NASA Astrophysics Data System (ADS)

Tsai, Wu-ting

Turbulent flow driven by a constant wind stress acting at the water surface was simulated numerically to gain a better understanding of the hydrodynamic processes governing the transfer of slightly soluble gases across the atmosphere-water interfaces. Simulation results show that two distinct flow features, attributed to subsurface surface renewal eddies, appear at the water surface. The first characteristic feature is surface streaming, which consists of high-speed streaks aligned with the wind stress. Floating Lagrangian particles, which are distributed uniformly at the water surface, merge to the predominantly high-speed streaks and form elongated streets immediately after they are released. The second characteristic surface signatures are localized low-speed spots which emerge randomly at the water surface. A high-speed streak bifurcates and forms a dividing flow when it encounters a low-speed surface spot. These coherent surface flow structures are qualitatively identical to those observed in the experiment of Melville et al. [1998]. The persistence of these surface features also suggests that there must exist organized subsurface vortical structures that undergo autonomous generation cycles maintained by self-sustaining mechanisms. These coherent vortical flows serve as the renewal eddies that pump the submerged fluids toward the water surface and bring down the upper fluids, and therefore enhance the scalar exchange between the atmosphere and the water body.

Application of bimodal distribution to the detection of changes in uranium concentration in drinking water collected by random daytime sampling method from a large water supply zone.

PubMed

Garboś, Sławomir; Święcicka, Dorota

2015-11-01

The random daytime (RDT) sampling method was used for the first time in the assessment of average weekly exposure to uranium through drinking water in a large water supply zone. Data set of uranium concentrations determined in 106 RDT samples collected in three runs from the water supply zone in Wroclaw (Poland), cannot be simply described by normal or log-normal distributions. Therefore, a numerical method designed for the detection and calculation of bimodal distribution was applied. The extracted two distributions containing data from the summer season of 2011 and the winter season of 2012 (nI=72) and from the summer season of 2013 (nII=34) allowed to estimate means of U concentrations in drinking water: 0.947 μg/L and 1.23 μg/L, respectively. As the removal efficiency of uranium during applied treatment process is negligible, the effect of increase in uranium concentration can be explained by higher U concentration in the surface-infiltration water used for the production of drinking water. During the summer season of 2013, heavy rains were observed in Lower Silesia region, causing floods over the territory of the entire region. Fluctuations in uranium concentrations in surface-infiltration water can be attributed to releases of uranium from specific sources - migration from phosphate fertilizers and leaching from mineral deposits. Thus, exposure to uranium through drinking water may increase during extreme rainfall events. The average chronic weekly intakes of uranium through drinking water, estimated on the basis of central values of the extracted normal distributions, accounted for 3.2% and 4.1% of tolerable weekly intake. Copyright © 2015 Elsevier Ltd. All rights reserved.

Presence and distribution of organic wastewater compounds in wastewater, surface, ground, and drinking waters, Minnesota, 2000-02

USGS Publications Warehouse

Lee, Kathy E.; Barber, Larry B.; Furlong, Edward T.; Cahill, Jeffery D.; Kolpin, Dana W.; Meyer, Michael T.; Zaugg, Steven D.

2004-01-01

Results of this study indicate ubiquitous distribution of measured OWCs in the environment that originate from numerous sources and pathways. During this reconnaissance of OWCs in Minnesota it was not possible to determine the specific sources of OWCs to surface, ground, or drinking waters. The data indicate WWTP effluent is a major pathway of OWCs to surface waters and that landfill leachate at selected facilities is a potential source of OWCs to WWTPs. Aquatic organism or human exposure to some OWCs is likely based on OWC distribution. Few aquatic or human health standards or criteria exist for the OWCs analyzed, and the risks to humans or aquatic wildlife are not known. Some OWCs detected in this study are endocrine disrupters and have been found to disrupt or influence endocrine function in fish. Thirteen endocrine disrupters, 3-tert-butyl-4-hydoxyanisole (BHA), 4- cumylphenol, 4-normal-octylphenol, 4-tert-octylphenol, acetyl-hexamethyl-tetrahydro-naphthalene (AHTN), benzo[α]pyrene, beta-sitosterol, bisphenol-A, diazinon, nonylphenol diethoxylate (NP2EO), octyphenol diethoxylate (OP2EO), octylphenol monoethoxylate (OP1EO), and total para-nonylphenol (NP) were detected. Results of reconnaissance studies may help regulators who set water-quality standards begin to prioritize which OWCs to focus upon for given categories of water use.

Gradual Crossover from Subdiffusion to Normal Diffusion: A Many-Body Effect in Protein Surface Water

NASA Astrophysics Data System (ADS)

Tan, Pan; Liang, Yihao; Xu, Qin; Mamontov, Eugene; Li, Jinglai; Xing, Xiangjun; Hong, Liang

2018-06-01

Dynamics of hydration water is essential for the function of biomacromolecules. Previous studies have demonstrated that water molecules exhibit subdiffusion on the surface of biomacromolecules; yet the microscopic mechanism remains vague. Here, by performing neutron scattering, molecular dynamics simulations, and analytic modeling on hydrated perdeuterated protein powders, we found water molecules jump randomly between trapping sites on protein surfaces, whose waiting times obey a broad distribution, resulting in subdiffusion. Moreover, the subdiffusive exponent gradually increases with observation time towards normal diffusion due to a many-body volume-exclusion effect.

Distribution and Risk Assessment of Antibiotics in a Typical River in North China Plain.

PubMed

Li, Qingzhao; Gao, Junxia; Zhang, Qiuling; Liang, Lizhen; Tao, He

2017-04-01

We evaluated the occurrence and distribution of 12 antibiotics from the sulfonamide (SAs), fluoroquinolone (FQs) and tetracycline (TCs) groups in the Weihe River, North China. The total antibiotic concentrations in surface water, pore water, and sediment samples ranged from 11.1 to 173.1 ng/L, 5.8 to 103.9 ng/L, and 9.5 to 153.4 μg/kg, respectively. The values of the sediment-water partitioning coefficient in the Weihe River varied widely, from not detected to 943, 2213, and 2405 L/kg for SAs, FQs, and TCs, respectively. The values of the partitioning coefficients between sediment and surface water were generally lower than those between sediment and pore water, which indicated ongoing inputs to the water. The risk assessment showed that there were relatively high ecological risks to aquatic algae in this area from sulfamethoxazole, norfloxacin, tetracycline, ofloxacin, and ciprofloxacin.

Preliminary indications of water film distribution and thickness on an airfoil in a water spray

NASA Technical Reports Server (NTRS)

Hastings, E. C., Jr.; Weinstein, L. M.

1984-01-01

A sensor for measuring water film thickness is evaluated. The test is conducted in a small flow apparatus with a 1 ft chord model wing in a water spray. Photographic and visual observations are made of the upper wing surface and film thickness is measured on the upper and lower wing surfaces. The performance of the sensor appears highly satisfactory, and where valid comparisons can be made, repeatable results are obtained.

The dynamic response of Kennicott Glacier, Alaska, USA, to the Hidden Creek Lake outburst flood

USGS Publications Warehouse

Anderson, R. Scott; Walder, J.S.; Anderson, S.P.; Trabant, D.C.; Fountain, A.G.

2005-01-01

Glacier sliding is commonly linked with elevated water pressure at the glacier bed. Ice surface motion during a 3 week period encompassing an outburst of ice-dammed Hidden Creek Lake (HCL) at Kennicott Glacier, Alaska, USA, showed enhanced sliding during the flood. Two stakes, 1.2 km from HCL, revealed increased speed in two episodes, both associated with uplift of the ice surface relative to the trajectory of bed-parallel motion. Uplift of the surface began 12 days before the flood, initially stabilizing at a value of 0.25 m. Two days after lake drainage began, further uplift (reaching 0.4 m) occurred while surface speed peaked at 1.2 m d-1. Maximum surface uplift coincided with peak discharge from HCL, high water level in a down-glacier ice-marginal basin, and low solute concentrations in the Kennicott River. Each of these records is consistent with high subglacial water pressure. We interpret the ice surface motion as arising from sliding up backs of bumps on the bed, which enlarges cavities and produces bed separation. The outburst increased water pressure over a broad region, promoting sliding, inhibiting cavity closure, and blocking drainage of solute-rich water from the distributed system. Pressure drop upon termination of the outburst drained water from and depressurized the distributed system, reducing sliding speeds. Expanded cavities then collapsed with a 1 day time-scale set by the local ice thickness.

Contamination mechanisms of air basin with tritium in venues of underground nuclear explosions at the former Semipalatinsk test site.

PubMed

Lyakhova, O N; Lukashenko, S N; Larionova, N V; Tur, Y S

2012-11-01

During the period of testing from 1945 to 1962 at the territory of Semipalatinsk test site (STS) within the Degelen Mountains in tunnels, 209 underground nuclear explosions were produced. Many of the tunnels have seasonal water seepage in the form of streams, through which tritium migrates from the underground nuclear explosion (UNE) venues towards the surface. The issue of tritium contamination occupies a special place in the radioactive contamination of the environment. In this paper we assess the level and distribution of tritium in the atmospheric air of ecosystems with water seepage at tunnels № 176 and № 177, located on "Degelen" site. There has been presented general nature of tritium distribution in the atmosphere relative to surface of a watercourse which has been contaminated with tritium. The basic mechanisms were studied for tritium distribution in the air of studied ecosystems, namely, the distribution of tritium in the systems: water-atmosphere, tunnel air-atmosphere, soil water-atmosphere, vegetation-atmosphere. An analytical calculation of tritium concentration in the atmosphere by the concentration of tritium in water has been performed. There has experimentally obtained the dependence for predictive assessment of tritium concentrations in air as a function of tritium concentration in one of the inlet sources such as water, tunnel air, soil water, vegetation, etc.. The paper also describes the general nature of tritium distribution in the air in the area "Degelen". Copyright © 2012 Elsevier Ltd. All rights reserved.

Spatial distributions and seasonal variations of organochlorine pesticides in water and soil samples in Bolu, Turkey.

PubMed

Karadeniz, Hatice; Yenisoy-Karakaş, Serpil

2015-03-01

In this study, a total of 75 water samples (38 groundwater and 37 surface water samples) and 54 surface soil samples were collected from the five districts of Bolu, which is located in the Western Black Sea Region of Turkey in the summer season of 2009. In the autumn season, 17 water samples (surface water and groundwater samples) and 17 soil samples were collected within the city center to observe the seasonal changes of organochlorine pesticides (OCPs). Groundwater and surface water samples were extracted using solid phase extraction. Soil samples were extracted ultrasonically. Sixteen OCP compounds in the standard solution were detected by a gas chromatography-electron capture detector (GC-ECD). Therefore, the method validation was performed for those 16 OCP compounds. However, 13 OCP compounds could be observed in the samples. The concentrations of most OCPs were higher in samples collected in the summer than those in the autumn. The most frequently observed pesticides were endosulfan sulfate and 4,4'-dichlorodiphenyltrichloroethane (DDT) in groundwater samples, α-HCH in surface water samples, and endosulfan sulfate in soil samples. The average concentration of endosulfan sulfate was the highest in water and soil samples. Compared to the literature values, the average concentrations in this study were lower values. Spatial distribution of OCPs was evaluated with the aid of contour maps for the five districts of Bolu. Generally, agricultural processes affected the water and soil quality in the region. However, non-agricultural areas were also affected by pesticides. The concentrations of pesticides were below the legal limits of European directives for each pesticide.

Active and Passive Remote Sensing Data Time Series for Flood Detection and Surface Water Mapping

NASA Astrophysics Data System (ADS)

Bioresita, Filsa; Puissant, Anne; Stumpf, André; Malet, Jean-Philippe

2017-04-01

As a consequence of environmental changes surface waters are undergoing changes in time and space. A better knowledge of the spatial and temporal distribution of surface waters resources becomes essential to support sustainable policies and development activities. Especially because surface waters, are not only a vital sweet water resource, but can also pose hazards to human settlements and infrastructures through flooding. Floods are a highly frequent disaster in the world and can caused huge material losses. Detecting and mapping their spatial distribution is fundamental to ascertain damages and for relief efforts. Spaceborne Synthetic Aperture Radar (SAR) is an effective way to monitor surface waters bodies over large areas since it provides excellent temporal coverage and, all-weather day-and-night imaging capabilities. However, emergent vegetation, trees, wind or flow turbulence can increase radar back-scatter returns and pose problems for the delineation of inundated areas. In such areas, passive remote sensing data can be used to identify vegetated areas and support the interpretation of SAR data. The availability of new Earth Observation products, for example Sentinel-1 (active) and Sentinel-2 (passive) imageries, with both high spatial and temporal resolution, have the potential to facilitate flood detection and monitoring of surface waters changes which are very dynamic in space and time. In this context, the research consists of two parts. In the first part, the objective is to propose generic and reproducible methodologies for the analysis of Sentinel-1 time series data for floods detection and surface waters mapping. The processing chain comprises a series of pre-processing steps and the statistical modeling of the pixel value distribution to produce probabilistic maps for the presence of surface waters. Images pre-processing for all Sentinel-1 images comprise the reduction SAR effect like orbit errors, speckle noise, and geometric effects. A modified Split Based Approach (MSBA) is used in order to focus on surface water areas automatically and facilitate the estimation of class models for water and non-water areas. A Finite Mixture Model is employed as the underlying statistical model to produce probabilistic maps. Subsequently, bilateral filtering is applied to take into account spatial neighborhood relationships in the generation of final map. The elimination of shadows effect is performed in a post-processing step. The processing chain is tested on three case studies. The first case is a flood event in central Ireland, the second case is located in Yorkshire county / Great Britain, and the third test case covers a recent flood event in northern Italy. The tests showed that the modified SBA step and the Finite Mixture Models can be applied for the automatic surface water detection in a variety of test cases. An evaluation again Copernicus products derived from very-high resolution imagery was performed, and showed a high overall accuracy and F-measure of the obtained maps. This evaluation also showed that the use of probability maps and bilateral filtering improved the accuracy of classification results significantly. Based on this quantitative evaluation, it is concluded that the processing chain can be applied for flood mapping from Sentinel-1 data. To estimate robust statistical distributions the method requires sufficient surface waters areas in the observed zone and sufficient contrast between surface waters and other land use classes. Ongoing research addresses the fusion of Sentinel-1 and passive remote sensing data (e.g. Sentinel-2) in order to reduce the current shortcomings in the developed processing chain. In this work, fusion is performed at the feature level to better account for the difference image properties of SAR and optical sensors. Further, the processing chain is currently being optimized in terms of calculation time for a further integration as a flood mapping service on the A2S (Alsace Aval Sentinel) high-performance computing infrastructure of University of Strasbourg.

Arsenic Fate, Transport And Stability Study: Groundwater, Surface Water, Soil And Sediment Investigation At Fort Devens Superfund Site

EPA Science Inventory

A field investigation was conducted to examine the distribution of arsenic in groundwater, surface water, and sediments at the Fort Devens Superfund Site. The study area encompassed a portion of plow Shop Pond (Red Cove), which receives groundwater discharge from the aquifer und...

Phosphorus fractionation and distribution in sediments from wetlands and canals of a water conservation area in the Florida Everglades

Treesearch

Qingren Wang; Yuncong Li; Ying Ouyang

2011-01-01

Phosphorus (P) fractionation and distribution in sediments are of great concern in the Florida Everglades ecosystem because potential eutrophication of surface waters usually results from P external loading and stability. Intact core sediment samples were collected to a depth of 35 cm from wetlands and canals across Water Conservation Area 3 (WCA‐3) of the Florida...

Microbial Community Profile of a Lead Service Line Removed from a Drinking Water Distribution System▿

PubMed Central

White, Colin; Tancos, Matthew; Lytle, Darren A.

2011-01-01

A corroded lead service line was removed from a drinking water distribution system, and the microbial community was profiled using 16S rRNA gene techniques. This is the first report of the characterization of a biofilm on the surface of a corroded lead drinking water service line. The majority of phylotypes have been linked to heavy-metal-contaminated environments. PMID:21652741

Ion-specific effects under confinement: the role of interfacial water.

PubMed

Argyris, Dimitrios; Cole, David R; Striolo, Alberto

2010-04-27

All-atom molecular dynamics simulations were employed for the study of the structure and dynamics of aqueous electrolyte solutions within slit-shaped silica nanopores with a width of 10.67 A at ambient temperature. All simulations were conducted for 250 ns to capture the dynamics of ion adsorption and to obtain the equilibrium distribution of multiple ionic species (Na+, Cs+, and Cl(-)) within the pores. The results clearly support the existence of ion-specific effects under confinement, which can be explained by the properties of interfacial water. Cl(-) strongly adsorbs onto the silica surface. Although neither Na+ nor Cs+ is in contact with the solid surface, they show ion-specific behavior. The differences between the density distributions of cations within the pore are primarily due to size effects through their interaction with confined water molecules. The majority of Na+ ions appear within one water layer in close proximity to the silica surface, whereas Cs+ is excluded from well-defined water layers. As a consequence of this preferential distribution, we observe enhanced in-plane mobility for Cs+ ions, found near the center of the pore, compared to that for Na+ ions, closer to the solid substrate. These observations illustrate the key role of interfacial water in determining ion-specific effects under confinement and have practical importance in several fields, from geology to biology.

Distributional pattern of planktonic foraminifers and pteropods in surface waters and top core sediments of the Red Sea, and adjacent areas controlled by the monsoonal regime and other ecological factors

NASA Astrophysics Data System (ADS)

Auras-Schudnagies, Anabelle; Kroon, Dick; Ganssen, Gerald; Hemleben, Christoph; Van Hinte, Jan E.

1989-10-01

Living planktonic foraminiferal and pteropod distribution patterns in the western Arabian Sea, Gulf of Aden and Red Sea, collected during two summer cruises (1984, 1985), reflect the hydrographical system that is mainly controlled by a combination of monsoonal winds and evaporation rates. Spinose species constitute the majority of the planktonic foraminiferal assemblages in the Red Sea during both monsoonal seasons. The non-spinose species Globorotalia menardii, Neogloboquadrina dutertrei and Pulleniatina obliquiloculata, which are always abundant in the Arabian Sea, are present only during winter inflow. The intensity and duration of these inflowing surface currents control their distribution pattern. Stable oxygen isotope ratios show that G. menardii survives but ceases to grow north of Bab el Mandeb, while N. dutertrei continues to grow. Trends in the foraminiferal distribution in surface waters compare well with those of the sea floor, as far as larger specimens (>250 μm) are concerned, but differ for the small ones. Surface distribution patterns of small-sized specimens and juvenile/neanic stages of large-sized fully grown species do not correspond to those in the core top samples. The distribution pattern of living pteropods in the Red Sea is closely related to distinct water masses and corresponds to the distribution in top core sediments. Pteropods are absent in the sediments of the Gulf of Aden and the western Arabian Sea due to dissolution. Peak abundances of various pteropods and foraminifers indicate the presence of local upwelling processes in the Bab el Mandeb area. Determining these dynamics allows for the reconstruction of ancient oceanic environments and climatic interactions in the area.

Role of oxygen functional groups for structure and dynamics of interfacial water on low rank coal surface: a molecular dynamics simulation

NASA Astrophysics Data System (ADS)

You, Xiaofang; Wei, Hengbin; Zhu, Xianchang; Lyu, Xianjun; Li, Lin

2018-07-01

Molecular dynamics simulations were employed to study the effects of oxygen functional groups for structure and dynamics properties of interfacial water molecules on the subbituminous coal surface. Because of complex composition and structure, the graphite surface modified by hydroxyl, carboxyl and carbonyl groups was used to represent the surface model of subbituminous coal according to XPS results, and the composing proportion for hydroxyl, carbonyl and carboxyl is 25:3:5. The hydration energy with -386.28 kJ/mol means that the adsorption process between water and coal surface is spontaneous. Density profiles for oxygen atoms and hydrogen atoms indicate that the coal surface properties affect the structural and dynamic characteristics of the interfacial water molecules. The interfacial water exhibits much more ordering than bulk water. The results of radial distribution functions, mean square displacement and local self-diffusion coefficient for water molecule related to three oxygen moieties confirmed that the water molecules prefer to absorb with carboxylic groups, and adsorption of water molecules at the hydroxyl and carbonyl is similar.

40 CFR 141.63 - Maximum contaminant levels (MCLs) for microbiological contaminants.

Code of Federal Regulations, 2012 CFR

2012-07-01

... water pressure in all parts of the distribution system; (4) Filtration and/or disinfection of surface water, as described in subpart H, or disinfection of ground water using strong oxidants such as chlorine... (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS National Primary Drinking...

Trends in ground-water levels in Wisconsin through 1966

USGS Publications Warehouse

Devaul, Robert W.

1967-01-01

The water supplies of Wisconsin are the State's most valuable natural resource. Although the State has abundant water supplies to maintain the perennial flow of most streams, and to sustain large increases in municipal, agricultural, and industrial use in many areas, the available supply is not distributed equally throughout the State, either areally or in time. Intelligent development of all water resources depends on knowledge of the occurrence, distribution and movement of water, the amount of discharge to and from a region, the interrelationship of ground and surface water, and the quantity and quality of the water available.

Spatial variation in water loss predicts terrestrial salamander distribution and population dynamics.

PubMed

Peterman, W E; Semlitsch, R D

2014-10-01

Many patterns observed in ecology, such as species richness, life history variation, habitat use, and distribution, have physiological underpinnings. For many ectothermic organisms, temperature relationships shape these patterns, but for terrestrial amphibians, water balance may supersede temperature as the most critical physiologically limiting factor. Many amphibian species have little resistance to water loss, which restricts them to moist microhabitats, and may significantly affect foraging, dispersal, and courtship. Using plaster models as surrogates for terrestrial plethodontid salamanders (Plethodon albagula), we measured water loss under ecologically relevant field conditions to estimate the duration of surface activity time across the landscape. Surface activity time was significantly affected by topography, solar exposure, canopy cover, maximum air temperature, and time since rain. Spatially, surface activity times were highest in ravine habitats and lowest on ridges. Surface activity time was a significant predictor of salamander abundance, as well as a predictor of successful recruitment; the probability of a juvenile salamander occupying an area with high surface activity time was two times greater than an area with limited predicted surface activity. Our results suggest that survival, recruitment, or both are demographic processes that are affected by water loss and the ability of salamanders to be surface-active. Results from our study extend our understanding of plethodontid salamander ecology, emphasize the limitations imposed by their unique physiology, and highlight the importance of water loss to spatial population dynamics. These findings are timely for understanding the effects that fluctuating temperature and moisture conditions predicted for future climates will have on plethodontid salamanders.

Coupling surface water (Delft3D) to groundwater (MODFLOW) in the Bay-Delta community model: the effect of major abstractions in the Delta

NASA Astrophysics Data System (ADS)

Hendriks, D.; Ball, S. M.; Van der Wegen, M.; Verkaik, J.; van Dam, A.

2016-12-01

We present a coupled groundwater-surface water model for the San Francisco Bay and Sacramento Valley that consists of a combination of a spatially-distributed groundwater model (Modflow) based on the USGS Central Valley model(1) and the Flexible Mesh (FM) surface water model of the Bay Area(2). With this coupled groundwater-surface water model, we assessed effects of climate, surface water abstractions and groundwater pumping on surface water and groundwater levels, groundwater-surface water interaction and infiltration/seepage fluxes. Results show that the effect of climate (high flow and low flow) on surface water and groundwater is significant and most prominent in upstream areas. The surface water abstractions cause significant local surface water levels decrease (over 2 m), which may cause inflow of bay water during low flow periods, resulting in salinization of surface water in more upstream areas. Groundwater level drawdown due to surface water withdrawal is moderate and limited to the area of the withdrawals. The groundwater pumping causes large groundwater level drawdowns (up to 0.8 m) and significant changes in seepage/infiltration fluxes in the model. However, the effect on groundwater-surface water exchange is relatively small. The presented model instrument gives a sound first impression of the effects of climate and water abstraction on both surface water and groundwater. The combination of Modflow and Flexible Mesh has potential for modelling of groundwater-surface water exchange in deltaic areas, also in other parts of the world. However, various improvements need to be made in order to make the simulation results useful in practice. In addition, a water quality aspect could be added to assess salinization processes as well as groundwater-surface water aspects of water and soil pollution. (1) http://ca.water.usgs.gov/projects/central-valley/central-valley-hydrologic-model.html (2) www.d3d-baydelta.org

Occurrence of Mycobacteria in Water Treatment Lines and in Water Distribution Systems

PubMed Central

Le Dantec, Corinne; Duguet, Jean-Pierre; Montiel, Antoine; Dumoutier, Nadine; Dubrou, Sylvie; Vincent, Véronique

2002-01-01

The frequency of recovery of atypical mycobacteria was estimated in two treatment plants providing drinking water to Paris, France, at some intermediate stages of treatment. The two plants use two different filtration processes, rapid and slow sand filtration. Our results suggest that slow sand filtration is more efficient for removing mycobacteria than rapid sand filtration. In addition, our results show that mycobacteria can colonize and grow on granular activated carbon and are able to enter distribution systems. We also investigated the frequency of recovery of mycobacteria in the water distribution system of Paris (outside buildings). The mycobacterial species isolated from the Paris drinking water distribution system are different from those isolated from the water leaving the treatment plants. Saprophytic mycobacteria (present in 41.3% of positive samples), potentially pathogenic mycobacteria (16.3%), and unidentifiable mycobacteria (54.8%) were isolated from 12 sites within the Paris water distribution system. Mycobacterium gordonae was preferentially recovered from treated surface water, whereas Mycobacterium nonchromogenicum was preferentially recovered from groundwater. No significant correlations were found among the presence of mycobacteria, the origin of water, and water temperature. PMID:12406720

Distribution of the Fukushima-derived radionuclides in seawater in the Pacific off the coast of Miyagi, Fukushima, and Ibaraki Prefectures, Japan

NASA Astrophysics Data System (ADS)

Oikawa, S.; Takata, H.; Watabe, T.; Misonoo, J.; Kusakabe, M.

2013-03-01

The activities of artificial radionuclides in seawater samples collected off the coast of Miyagi, Fukushima, and Ibaraki Prefectures were measured as part of a monitoring program initiated by the Japanese government Ministry of Education, Sports, Science and Technology immediately after the Fukushima Dai-ichi nuclear power plant accident. The spatial and temporal distributions of those activities are summarized herein. The activities of strontium-90, iodine-131, cesium-134 and -137 (i.e. 90Sr, 131I, 134Cs, and 137Cs) derived from the accident were detected in seawater samples taken from areas of the coastal ocean adjacent to the power plant. No 131I was detected in surface waters (≤ 5 m depth) or in intermediate and bottom waters after 30 April 2011. Strontium-90 was found in surface waters collected from a few sampling stations in mid-August 2011 to mid-December 2011. Temporal changes of 90Sr activity in surface waters were evident, although the 90Sr activity at a given time varied widely between sampling stations. The activity of 90Sr in surface waters decreased slowly over time, and by the end of December 2011 had reached background levels recorded before the accident. Radiocesium, 134Cs and 137Cs, was found in seawater samples immediately after the accident. There was a remarkable change in 137Cs activities in surface waters during the first 7 months (March through September 2011) after the accident; the activity reached a maximum in the middle of April and thereafter decreased exponentially with time. Qualitatively, the distribution patterns in surface waters suggested that in early May 137Cs-polluted water was advected northward; some of the water then detached and was transported to the south. Two cores of the water with high 137Cs activity persisted at least until July 2011. In subsurface waters 137Cs activity was first detected in the beginning of April 2011, and the water masses were characterized by σt (an indicator of density) values of 25.5-26.5. From 9-14 May to 5-16 December 2011, the depths of the water masses increased with time, an indication that deepening of the isopycnals with time can be an important mechanism for the transport of 137Cs downward in coastal waters. During 4-21 February 2012, the water column became vertically homogeneous, probably because of convective mixing during the winter, the result being nearly constant values of 137Cs activity throughout the water column from the surface to the bottom (~200 m depth) at each station.

Influence of environmental and anthropogenic factors on the composition, concentration and spatial distribution of microplastics: A case study of the Bay of Brest (Brittany, France).

PubMed

Frère, L; Paul-Pont, I; Rinnert, E; Petton, S; Jaffré, J; Bihannic, I; Soudant, P; Lambert, C; Huvet, A

2017-06-01

The concentration and spatial distribution of microplastics in the Bay of Brest (Brittany, France) was investigated in two surveys. Surface water and sediment were sampled at nine locations in areas characterized by contrasting anthropic pressures, riverine influences or water mixing. Microplastics were categorized by their polymer type and size class. Microplastic contamination in surface water and sediment was dominated by polyethylene fragments (PE, 53-67%) followed by polypropylene (PP, 16-30%) and polystyrene (PS, 16-17%) microparticles. The presence of buoyant microplastics (PE, PP and PS) in sediment suggests the existence of physical and/or biological processes leading to vertical transfer of lightweight microplastics in the bay. In sediment (upper 5 cm), the percentage of particles identified by Raman micro-spectroscopy was lower (41%) than in surface water (79%) and may explain the apparent low concentration observed in this matrix (0.97 ± 2.08 MP kg -1 dry sediment). Mean microplastic concentration was 0.24 ± 0.35 MP m -3 in surface water. We suggest that the observed spatial MP distribution is related to proximity to urbanized areas and to hydrodynamics in the bay. A particle dispersal model was used to study the influence of hydrodynamics on surface microplastic distribution. The outputs of the model showed the presence of a transitional convergence zone in the centre of the bay during flood tide, where floating debris coming from the northern and southern parts of the bay tends to accumulate before being expelled from the bay. Further modelling work and observations integrating (i) the complex vertical motion of microplastics, and (ii) their point sources is required to better understand the fate of microplastics in such a complex coastal ecosystem. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of PVC and iron materials on Mn(II) deposition in drinking water distribution systems.

PubMed

Cerrato, José M; Reyes, Lourdes P; Alvarado, Carmen N; Dietrich, Andrea M

2006-08-01

Polyvinyl chloride (PVC) and iron pipe materials differentially impacted manganese deposition within a drinking water distribution system that experiences black water problems because it receives soluble manganese from a surface water reservoir that undergoes biogeochemical cycling of manganese. The water quality study was conducted in a section of the distribution system of Tegucigalpa, Honduras and evaluated the influence of iron and PVC pipe materials on the concentrations of soluble and particulate iron and manganese, and determined the composition of scales formed on PVC and iron pipes. As expected, total Fe concentrations were highest in water from iron pipes. Water samples obtained from PVC pipes showed higher total Mn concentrations and more black color than that obtained from iron pipes. Scanning electron microscopy demonstrated that manganese was incorporated into the iron tubercles and thus not readily dislodged from the pipes by water flow. The PVC pipes contained a thin surface scale consisting of white and brown layers of different chemical composition; the brown layer was in contact with the water and contained 6% manganese by weight. Mn composed a greater percentage by weight of the PVC scale than the iron pipe scale; the PVC scale was easily dislodged by flowing water. This research demonstrates that interactions between water and the infrastructure used for its supply affect the quality of the final drinking water.

Surface-water, ground-water, and sediment geochemistry of epizonal and shear-hosted mineral deposits in the Tintina Gold Province--arsenic and antimony distribution and mobility: Chapter G 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

Mueller, Seth H.; Goldfarb, Richard J.; Verplanck, Philip L.; Trainor, Thomas P.; Sanzolone, Richard F.; Adams, Monique; Gough, Larry P.; Day, Warren C.

2007-01-01

Epigenetic mineral deposits in the Tintina Gold Province are generally characterized by high concentrations of arsenic and antimony in their mineral assemblage. A total of 347 samples (ground water, surface water, and stream sediment) were collected to investigate the distribution and mobility of arsenic and antimony in the environment near known mineral deposits. Samples were collected from east to west at Keno Hill and Brewery Creek, Yukon, Canada; and Cleary Hill, True North, Scrafford Mine, Fairbanks, Ryan Lode, Stampede Creek, Slate Creek, and Donlin Creek, all in Alaska. Surface- and ground-water samples are all slightly acidic to near-neutral in pH (5-8), have a wide range in specific conductance (surface water 17-2,980 microsiemens per centimeter and ground water 170-2,940 microsiemens per centimeter), and show elevated dissolved arsenic and antimony concentrations (arsenic in surface water is less than 1 to 380 micrograms per liter and in ground water is less than 1 micrograms per liter to 1.5 milligrams per liter; antimony in surface water is less than 2 to 660 micrograms per liter and in ground water is less than 2 to 60 micrograms per liter). Stream sediments downstream from these deposits have high concentrations of arsenic and antimony (arsenic median is 1,670 parts per million, maximum is 10,000 parts per million; antimony median is 192 parts per million, maximum is 7,200 parts per million). The mobility of arsenic and antimony is controlled by the local redox environment, with arsenic being less mobile in oxidized surface waters relative to antimony, and arsenic more mobile in reduced ground water. These factors suggest that both antimony and arsenic may be useful pathfinder elements in water and sediment for targeting similar style deposits elsewhere in the Tintina Gold Province.

The global distribution and dynamics of surface soil moisture

NASA Astrophysics Data System (ADS)

McColl, Kaighin A.; Alemohammad, Seyed Hamed; Akbar, Ruzbeh; Konings, Alexandra G.; Yueh, Simon; Entekhabi, Dara

2017-01-01

Surface soil moisture has a direct impact on food security, human health and ecosystem function. It also plays a key role in the climate system, and the development and persistence of extreme weather events such as droughts, floods and heatwaves. However, sparse and uneven observations have made it difficult to quantify the global distribution and dynamics of surface soil moisture. Here we introduce a metric of soil moisture memory and use a full year of global observations from NASA's Soil Moisture Active Passive mission to show that surface soil moisture--a storage believed to make up less than 0.001% of the global freshwater budget by volume, and equivalent to an, on average, 8-mm thin layer of water covering all land surfaces--plays a significant role in the water cycle. Specifically, we find that surface soil moisture retains a median 14% of precipitation falling on land after three days. Furthermore, the retained fraction of the surface soil moisture storage after three days is highest over arid regions, and in regions where drainage to groundwater storage is lowest. We conclude that lower groundwater storage in these regions is due not only to lower precipitation, but also to the complex partitioning of the water cycle by the surface soil moisture storage layer at the land surface.

Decadal water quality variations at three typical basins of Mekong, Murray and Yukon

NASA Astrophysics Data System (ADS)

Khan, Afed U.; Jiang, Jiping; Wang, Peng

2018-02-01

Decadal distribution of water quality parameters is essential for surface water management. Decadal distribution analysis was conducted to assess decadal variations in water quality parameters at three typical watersheds of Murray, Mekong and Yukon. Right distribution shifts were observed for phosphorous and nitrogen parameters at the Mekong watershed monitoring sites while left shifts were noted at the Murray and Yukon monitoring sites. Nutrients pollution increases with time at the Mekong watershed while decreases at the Murray and Yukon watershed monitoring stations. The results implied that watershed located in densely populated developing area has higher risk of water quality deterioration in comparison to thinly populated developed area. The present study suggests best management practices at watershed scale to modulate water pollution.

Effects of Acids, Bases, and Heteroatoms on Proximal Radial Distribution Functions for Proteins.

PubMed

Nguyen, Bao Linh; Pettitt, B Montgomery

2015-04-14

The proximal distribution of water around proteins is a convenient method of quantifying solvation. We consider the effect of charged and sulfur-containing amino acid side-chain atoms on the proximal radial distribution function (pRDF) of water molecules around proteins using side-chain analogs. The pRDF represents the relative probability of finding any solvent molecule at a distance from the closest or surface perpendicular protein atom. We consider the near-neighbor distribution. Previously, pRDFs were shown to be universal descriptors of the water molecules around C, N, and O atom types across hundreds of globular proteins. Using averaged pRDFs, a solvent density around any globular protein can be reconstructed with controllable relative error. Solvent reconstruction using the additional information from charged amino acid side-chain atom types from both small models and protein averages reveals the effects of surface charge distribution on solvent density and improves the reconstruction errors relative to simulation. Solvent density reconstructions from the small-molecule models are as effective and less computationally demanding than reconstructions from full macromolecular models in reproducing preferred hydration sites and solvent density fluctuations.

Water Quality Research Program: Abstracts of the International Symposium on Gas Transfer at Water Surfaces (2nd) Held in Minneapolis, Minnesota on 11-14 September 1990

DTIC Science & Technology

1990-08-01

layer on the surface) it is 2 - 3 times less. Many in- situ observations show that different patterns of temperature distribution in the surface water...Coeficiente de Reaeracao dos Escoamentos Naturais da Agua com o Emprego de Tracador Gasoso. M.Sc Dissertation, Universidade de Sao Paulo, EESC, Depto. de...structure. If methane is present in measurable quantities it may prove to be an excellent in- situ tracer of gas transfer. Transfer efficiency has been used

Heterogeneous Ice Nucleation: Interplay of Surface Properties and Their Impact on Water Orientations.

PubMed

Glatz, Brittany; Sarupria, Sapna

2018-01-23

Ice is ubiquitous in nature, and heterogeneous ice nucleation is the most common pathway of ice formation. How surface properties affect the propensity to observe ice nucleation on that surface remains an open question. We present results of molecular dynamics studies of heterogeneous ice nucleation on model surfaces. The models surfaces considered emulate the chemistry of kaolinite, an abundant component of mineral dust. We investigate the interplay of surface lattice and hydrogen bonding properties in affecting ice nucleation. We find that lattice matching and hydrogen bonding are necessary but not sufficient conditions for observing ice nucleation at these surfaces. We correlate this behavior to the orientations sampled by the metastable supercooled water in contact with the surfaces. We find that ice is observed in cases where water molecules not only sample orientations favorable for bilayer formation but also do not sample unfavorable orientations. This distribution depends on both surface-water and water-water interactions and can change with subtle modifications to the surface properties. Our results provide insights into the diverse behavior of ice nucleation observed at different surfaces and highlight the complexity in elucidating heterogeneous ice nucleation.

Quantifying the Contribution of Regional Aquifers to Stream Flow in the Upper Colorado River Basin

NASA Astrophysics Data System (ADS)

Masbruch, M.; Dickinson, J.

2017-12-01

The growing population of the arid and semiarid southwestern U.S. relies on over-allocated surface water resources and poorly quantified groundwater resources. In the Upper Colorado River Basin, recent studies have found that about 50 percent of the surface water at U.S. Geological Survey (USGS) stream gages is derived from groundwater contributions as base flow. Prior USGS and other studies for the Colorado Plateau region have mainly examined groundwater and surface water as separate systems, and there has yet to be regional synthesis of groundwater availability in aquifers that contribute to surface water. A more physically based representation of groundwater flow could improve simulations of surface-water capture by groundwater pumping, and changes of groundwater discharge to surface water caused by possible shifts in the distribution, magnitude, and timing of recharge in the future. We seek to improve conceptual and numerical models of groundwater and surface-water interactions in the Colorado Plateau region as part of a USGS regional groundwater availability assessment. Numerical modeling is used to simulate and quantify the base flow from groundwater to the Colorado River and its major tributaries. Groundwater/surface-water interactions will be simulated using the USGS code GSFLOW, which couples the Precipitation Runoff Modeling System (PRMS) to the groundwater flow model MODFLOW. Initial results suggest that interactions between groundwater and surface water are important for projecting long-term changes in surface water budgets.

MICROBIAL CHARACTERIZATION OF DRINKING WATER SYSTEMS RECEIVING GROUNDWATER AND SURFACE WATER AS THE PRIMARY SOURCES OF WATER

EPA Science Inventory

Earlier descriptions of water distribution systems (WDS) microbial communities have relied on culturing techniques. These techniques are known to be highly selective in nature, but more importantly, they tend to grossly underestimate the microbial diversity of most environments. ...

Water adsorption on surface-modified cellulose nanocrystals

NASA Astrophysics Data System (ADS)

Wei, Zonghui; Sinko, Robert; Keten, Sinan; Luijten, Erik

Cellulose nanocrystals (CNCs) have attracted much attention as a filler phase for polymer nanocomposites due to their impressive mechanical properties, low cost, and environmental sustainability. Despite their promise for this application, there are still numerous obstacles that prevent optimal performance of CNC-polymer nanocomposites, such as poor filler dispersion and high levels of water absorption. One way to mitigate these negative effects is to modify CNC surfaces. Computational approaches can be utilized to obtain direct insight into the properties of modified CNC surfaces and probe the interactions of CNCs with other materials to facilitate the experimental design of nanocomposites. We use atomistic grand-canonical Monte Carlo simulations to study how surface modification of ion-exchanged sulfated cellulose nanocrystals (Na-CNCs) impacts water adsorption. We find that methyl(triphenyl)phosphonium-exchanged CNCs adsorb less water than Na-CNCs at the same relative humidity, supporting recent experimental dynamic vapor sorption measurements. By characterizing the distribution and configuration of water molecules near the modified CNC surfaces we determine how surface modifications disrupt CNC-water interactions.

Interaction of gases with lunar materials

NASA Technical Reports Server (NTRS)

Holmes, H. F.; Fuller, E. L., Jr.; Gammage, R. B.

1974-01-01

Quantitative efforts to assess the surface properties of lunar fines, particularly water induced porosity are discussed. Data show that: (1) changes induced in lunar fines are not visible in high energy electron micrographs, (2) scanning micrographs show no change in particle size distribution as a result of reaction with water, (3) water induced changes are internal to the particles themselves, (4) normal laboratory atmosphere blocks alteration reaction with water, and (5) surface properties of mature lunar soils appear to be almost independent of chemical composition and mineralogy, but there are some variations in their reactivity toward water.

HydroCrowd: a citizen science snapshot to assess the spatial control of nitrogen solutes in surface waters

PubMed Central

Breuer, Lutz; Hiery, Noreen; Kraft, Philipp; Bach, Martin; Aubert, Alice H.; Frede, Hans-Georg

2015-01-01

We organized a crowdsourcing experiment in the form of a snapshot sampling campaign to assess the spatial distribution of nitrogen solutes, namely, nitrate, ammonium and dissolved organic nitrogen (DON), in German surface waters. In particular, we investigated (i) whether crowdsourcing is a reasonable sampling method in hydrology and (ii) what the effects of population density, soil humus content and arable land were on actual nitrogen solute concentrations and surface water quality. The statistical analyses revealed a significant correlation between nitrate and arable land (0.46), as well as soil humus content (0.37) but a weak correlation with population density (0.12). DON correlations were weak but significant with humus content (0.14) and arable land (0.13). The mean contribution of DON to total dissolved nitrogen was 22%. Samples were classified as water quality class II or above, following the European Water Framework Directive for nitrate and ammonium (53% and 82%, respectively). Crowdsourcing turned out to be a useful method to assess the spatial distribution of stream solutes, as considerable amounts of samples were collected with comparatively little effort. PMID:26561200

Distributed Water Pollution Source Localization with Mobile UV-Visible Spectrometer Probes in Wireless Sensor Networks.

PubMed

Ma, Junjie; Meng, Fansheng; Zhou, Yuexi; Wang, Yeyao; Shi, Ping

2018-02-16

Pollution accidents that occur in surface waters, especially in drinking water source areas, greatly threaten the urban water supply system. During water pollution source localization, there are complicated pollutant spreading conditions and pollutant concentrations vary in a wide range. This paper provides a scalable total solution, investigating a distributed localization method in wireless sensor networks equipped with mobile ultraviolet-visible (UV-visible) spectrometer probes. A wireless sensor network is defined for water quality monitoring, where unmanned surface vehicles and buoys serve as mobile and stationary nodes, respectively. Both types of nodes carry UV-visible spectrometer probes to acquire in-situ multiple water quality parameter measurements, in which a self-adaptive optical path mechanism is designed to flexibly adjust the measurement range. A novel distributed algorithm, called Dual-PSO, is proposed to search for the water pollution source, where one particle swarm optimization (PSO) procedure computes the water quality multi-parameter measurements on each node, utilizing UV-visible absorption spectra, and another one finds the global solution of the pollution source position, regarding mobile nodes as particles. Besides, this algorithm uses entropy to dynamically recognize the most sensitive parameter during searching. Experimental results demonstrate that online multi-parameter monitoring of a drinking water source area with a wide dynamic range is achieved by this wireless sensor network and water pollution sources are localized efficiently with low-cost mobile node paths.

Distributed Water Pollution Source Localization with Mobile UV-Visible Spectrometer Probes in Wireless Sensor Networks

PubMed Central

Zhou, Yuexi; Wang, Yeyao; Shi, Ping

2018-01-01

Pollution accidents that occur in surface waters, especially in drinking water source areas, greatly threaten the urban water supply system. During water pollution source localization, there are complicated pollutant spreading conditions and pollutant concentrations vary in a wide range. This paper provides a scalable total solution, investigating a distributed localization method in wireless sensor networks equipped with mobile ultraviolet-visible (UV-visible) spectrometer probes. A wireless sensor network is defined for water quality monitoring, where unmanned surface vehicles and buoys serve as mobile and stationary nodes, respectively. Both types of nodes carry UV-visible spectrometer probes to acquire in-situ multiple water quality parameter measurements, in which a self-adaptive optical path mechanism is designed to flexibly adjust the measurement range. A novel distributed algorithm, called Dual-PSO, is proposed to search for the water pollution source, where one particle swarm optimization (PSO) procedure computes the water quality multi-parameter measurements on each node, utilizing UV-visible absorption spectra, and another one finds the global solution of the pollution source position, regarding mobile nodes as particles. Besides, this algorithm uses entropy to dynamically recognize the most sensitive parameter during searching. Experimental results demonstrate that online multi-parameter monitoring of a drinking water source area with a wide dynamic range is achieved by this wireless sensor network and water pollution sources are localized efficiently with low-cost mobile node paths. PMID:29462929

In situ observations of Arctic cloud properties across the Beaufort Sea marginal ice zone

NASA Astrophysics Data System (ADS)

Corr, C.; Moore, R.; Winstead, E.; Thornhill, K. L., II; Crosbie, E.; Ziemba, L. D.; Beyersdorf, A. J.; Chen, G.; Martin, R.; Shook, M.; Corbett, J.; Smith, W. L., Jr.; Anderson, B. E.

2016-12-01

Clouds play an important role in Arctic climate. This is particularly true over the Arctic Ocean where feedbacks between clouds and sea-ice impact the surface radiation budget through modifications of sea-ice extent, ice thickness, cloud base height, and cloud cover. This work summarizes measurements of Arctic cloud properties made aboard the NASA C-130 aircraft over the Beaufort Sea during ARISE (Arctic Radiation - IceBridge Sea&Ice Experiment) in September 2014. The influence of surface-type on cloud properties is also investigated. Specifically, liquid water content (LWC), droplet concentrations, and droplet size distributions are compared for clouds sampled over three distinct regimes in the Beaufort Sea: 1) open water, 2) the marginal ice zone, and 3) sea-ice. Regardless of surface type, nearly all clouds intercepted during ARISE were liquid-phase clouds. However, differences in droplet size distributions and concentrations were evident for the surface types; clouds over the MIZ and sea-ice generally had fewer and larger droplets compared to those over open water. The potential implication these results have for understanding cloud-surface albedo climate feedbacks in Arctic are discussed.

Surface wave effects on water temperature in the Baltic Sea: simulations with the coupled NEMO-WAM model

NASA Astrophysics Data System (ADS)

Alari, Victor; Staneva, Joanna; Breivik, Øyvind; Bidlot, Jean-Raymond; Mogensen, Kristian; Janssen, Peter

2016-08-01

Coupled circulation (NEMO) and wave model (WAM) system was used to study the effects of surface ocean waves on water temperature distribution and heat exchange at regional scale (the Baltic Sea). Four scenarios—including Stokes-Coriolis force, sea-state dependent energy flux (additional turbulent kinetic energy due to breaking waves), sea-state dependent momentum flux and the combination these forcings—were simulated to test the impact of different terms on simulated temperature distribution. The scenario simulations were compared to a control simulation, which included a constant wave-breaking coefficient, but otherwise was without any wave effects. The results indicate a pronounced effect of waves on surface temperature, on the distribution of vertical temperature and on upwelling's. Overall, when all three wave effects were accounted for, did the estimates of temperature improve compared to control simulation. During the summer, the wave-induced water temperature changes were up to 1 °C. In northern parts of the Baltic Sea, a warming of the surface layer occurs in the wave included simulations in summer months. This in turn reduces the cold bias between simulated and measured data, e.g. the control simulation was too cold compared to measurements. The warming is related to sea-state dependent energy flux. This implies that a spatio-temporally varying wave-breaking coefficient is necessary, because it depends on actual sea state. Wave-induced cooling is mostly observed in near-coastal areas and is the result of intensified upwelling in the scenario, when Stokes-Coriolis forcing is accounted for. Accounting for sea-state dependent momentum flux results in modified heat exchange at the water-air boundary which consequently leads to warming of surface water compared to control simulation.

Landsat classification of surface-water presence during multiple years to assess response of playa wetlands to climatic variability across the Great Plains Landscape Conservation Cooperative region

USGS Publications Warehouse

Manier, Daniel J.; Rover, Jennifer R.

2018-02-15

To improve understanding of the distribution of ecologically important, ephemeral wetland habitats across the Great Plains, the occurrence and distribution of surface water in playa wetland complexes were documented for four different years across the Great Plains Landscape Conservation Cooperative (GPLCC) region. This information is important because it informs land and wildlife managers about the timing and location of habitat availability. Data with an accurate timestamp that indicate the presence of water, the percent of the area inundated with water, and the spatial distribution of playa wetlands with water are needed for a host of resource inventory, monitoring, and research applications. For example, the distribution of inundated wetlands forms the spatial pattern of available habitat for resident shorebirds and water birds, stop-over habitats for migratory birds, connectivity and clustering of wetland habitats, and surface waters that recharge the Ogallala aquifer; there is considerable variability in the distribution of playa wetlands holding water through time. Documentation of these spatially and temporally intricate processes, here, provides data required to assess connections between inundation and multiple environmental drivers, such as climate, land use, soil, and topography. Climate drivers are understood to interact with land cover, land use and soil attributes in determining the amount of water that flows overland into playa wetlands. Results indicated significant spatial variability represented by differences in the percent of playas inundated among States within the GPLCC. Further, analysis-of-variance comparison of differences in inundation between years showed significant differences in all cases. Although some connections with seasonal moisture patterns may be observed, the complex spatial-temporal gradients of precipitation, temperature, soils, and land use need to be combined as covariates in multivariate models to effectively account for these patterns. We demonstrate the feasibility of using classification of Landsat satellite imagery to describe playa-wetland inundation across years and seasons. Evaluating classifications representing only 4 years of imagery, we found significant year-to-year and state-to-state differences in inundation rates.

On the Interaction between Marine Boundary Layer Cellular Cloudiness and Surface Heat Fluxes

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

Kazil, J.; Feingold, G.; Wang, Hailong

2014-01-02

The interaction between marine boundary layer cellular cloudiness and surface uxes of sensible and latent heat is investigated. The investigation focuses on the non-precipitating closed-cell state and the precipitating open-cell state at low geostrophic wind speed. The Advanced Research WRF model is used to conduct cloud-system-resolving simulations with interactive surface fluxes of sensible heat, latent heat, and of sea salt aerosol, and with a detailed representation of the interaction between aerosol particles and clouds. The mechanisms responsible for the temporal evolution and spatial distribution of the surface heat fluxes in the closed- and open-cell state are investigated and explained. Itmore » is found that the horizontal spatial structure of the closed-cell state determines, by entrainment of dry free tropospheric air, the spatial distribution of surface air temperature and water vapor, and, to a lesser degree, of the surface sensible and latent heat flux. The synchronized dynamics of the the open-cell state drives oscillations in surface air temperature, water vapor, and in the surface fluxes of sensible and latent heat, and of sea salt aerosol. Open-cell cloud formation, cloud optical depth and liquid water path, and cloud and rain water path are identified as good predictors of the spatial distribution of surface air temperature and sensible heat flux, but not of surface water vapor and latent heat flux. It is shown that by enhancing the surface sensible heat flux, the open-cell state creates conditions by which it is maintained. While the open-cell state under consideration is not depleted in aerosol, and is insensitive to variations in sea-salt fluxes, it also enhances the sea-salt flux relative to the closed-cell state. In aerosol-depleted conditions, this enhancement may replenish the aerosol needed for cloud formation, and hence contribute to the perpetuation of the open-cell state as well. Spatial homogenization of the surface fluxes is found to have only a small effect on cloud properties in the investigated cases. This indicates that sub-grid scale spatial variability in the surface flux of sensible and latent heat and of sea salt aerosol may not be required in large scale and global models to describe marine boundary layer cellular cloudiness.« less

Biomimetic Water-Collecting Fabric with Light-Induced Superhydrophilic Bumps.

PubMed

Wang, Yuanfeng; Wang, Xiaowen; Lai, Chuilin; Hu, Huawen; Kong, Yeeyee; Fei, Bin; Xin, John H

2016-02-10

To develop an efficient water-collecting surface that integrates both fast water-capturing and easy drainage properties is of high current interest for addressing global water issues. In this work, a superhydrophobic surface was fabricated on cotton fabric via manipulation of both the surface roughness and surface energy. This was followed by a subsequent spray coating of TiO2 nanosol that created light-induced superhydrophilic bumps with a unique raised structure as a result of the interfacial tension of the TiO2 nanosol sprayed on the superhydrophobic fiber surface. These raised TiO2 bumps induce both a wettability gradient and a shape gradient, synergistically accelerating water coalescence and water collection. The in-depth study revealed that the quantity and the distribution of the TiO2 had a significant impact on the final water collection efficiency. This inexpensive and facilely fabricated fabric biomimicks the desert beetle's back and spider silk, which are capable of fog harvesting without additional energy consumption.

Urban evaporation rates for water-permeable pavements.

PubMed

Starke, P; Göbel, P; Coldewey, W G

2010-01-01

In urban areas the natural water balance is disturbed. Infiltration and evaporation are reduced, resulting in a high surface runoff and a typical city climate, which can lead to floods and damages. Water-permeable pavements have a high infiltration rate that reduces surface runoff by increasing the groundwater recharge. The high water retention capacity of the street body of up to 51 l/m(2) and its connection via pores to the surface lead to higher evaporation rates than impermeable surfaces. A comparison of these two kinds of pavements shows a 16% increase in evaporation levels of water-permeable pavements. Furthermore, the evaporation from impermeable pavements is linked directly to rain events due to fast-drying surfaces. Water-permeable pavements show a more evenly distributed evaporation after a rain event. Cooling effects by evaporative heat loss can improve the city climate even several days after rain events. On a large scale use, uncomfortable weather like sultriness or dry heat can be prevented and the urban water balance can be attenuated towards the natural.

Biofilm-induced changes in microbial quality of irrigation water: Indicator bacteria and antibiotic-resistance

USDA-ARS?s Scientific Manuscript database

Irrigation waters are implicated in the transmission of pathogens to fresh produce, and microbial release and retention from biofilms that form on inner surfaces of irrigation lines may impact the quality of delivered water. Biofilms in water distribution systems have been suggested as a reservoir ...

Use of Water Content Reflectometers in Bioinfiltration/Bioretention to Measure Water Movement and Estimate Evapotranspiration - abstract

EPA Science Inventory

Most bioinfiltration/bioretention models assume runoff is evenly distributed across the surface area and after the engineered fill media is no longer saturated, the volumetric water content (VWC) is constant throughout the media profile and at field capacity. Four to nine water ...

Use of Water Content Reflectometers in Bioinfiltration/Bioretention to Measure Water Movement and Estimate Evapotranspiration

EPA Science Inventory

Most bioinfiltration/bioretention models assume runoff is evenly distributed across the surface area and after the engineered fill media is no longer saturated, the volumetric water content (VWC) is constant throughout the media profile and at field capacity. Four to nine water ...

Ground-water geochemistry of the Albuquerque-Belen Basin, central New Mexico

USGS Publications Warehouse

Anderholm, S.K.

1988-01-01

The purpose of this study was to define the areal distribution of different water types, use the distribution to help define the groundwater flow system, and identify processes resulting in differences in groundwater quality in the Albuquerque-Belen Basin in central New Mexico. The chemistry of surface water inflow from adjacent areas, which infiltrates and recharges the aquifer along the basin margin, affects the groundwater quality in the eastern and southeastern areas of the basin. Groundwater in the eastern area generally has a specific conductance less than 400 microsiemens, and calcium and bicarbonate are the dominant ions. Mixing of recharge, groundwater inflow, and surface inflow from adjacent areas, which have different chemical compositions, is the major process affecting groundwater quality in the southwestern, western, and northern areas of the basin. In these areas, there is a large range in specific conductance and distribution of dissolved ions. Groundwater quality in the Rio Grande valley is affected by the infiltration of excess irrigation water. The excess irrigation water generally has a larger specific conductance than other groundwater in the valley, so mixing of these waters results in shallow groundwater generally having larger specific conductance than the deeper groundwater. (USGS)

Characterizing hydrophobicity at the nanoscale: a molecular dynamics simulation study.

PubMed

Bandyopadhyay, Dibyendu; Choudhury, Niharendu

2012-06-14

We use molecular dynamics (MD) simulations of water near nanoscopic surfaces to characterize hydrophobic solute-water interfaces. By using nanoscopic paraffin like plates as model solutes, MD simulations in isothermal-isobaric ensemble have been employed to identify characteristic features of such an interface. Enhanced water correlation, density fluctuations, and position dependent compressibility apart from surface specific hydrogen bond distribution and molecular orientations have been identified as characteristic features of such interfaces. Tetrahedral order parameter that quantifies the degree of tetrahedrality in the water structure and an orientational order parameter, which quantifies the orientational preferences of the second solvation shell water around a central water molecule, have also been calculated as a function of distance from the plate surface. In the vicinity of the surface these two order parameters too show considerable sensitivity to the surface hydrophobicity. The potential of mean force (PMF) between water and the surface as a function of the distance from the surface has also been analyzed in terms of direct interaction and induced contribution, which shows unusual effect of plate hydrophobicity on the solvent induced PMF. In order to investigate hydrophobic nature of these plates, we have also investigated interplate dewetting when two such plates are immersed in water.

A Facile All-Solution-Processed Surface with High Water Contact Angle and High Water Adhesive Force.

PubMed

Chen, Mei; Hu, Wei; Liang, Xiao; Zou, Cheng; Li, Fasheng; Zhang, Lanying; Chen, Feiwu; Yang, Huai

2017-07-12

A series of sticky superhydrophobicity surfaces with high water contact angle and high water adhesive force is facilely prepared via an all-solution-processed method based on polymerization-induced phase separation between liquid crystals (LCs) and epoxy resin, which produces layers of epoxy microspheres (EMSs) with nanofolds on the surface of a substrate. The morphologies and size distributions of EMSs are confirmed by scanning electron microscopy. Results reveal that the obtained EMS coated-surface exhibits high apparent contact angle of 152.0° and high water adhesive force up to 117.6 μN. By varying the composition of the sample or preparing conditions, the sizes of the produced EMSs can be artificially regulated and, thus, control the wetting properties and water adhesive behaviors. Also, the sticky superhydrophobic surface exhibits excellent chemical stability, as well as long-term durability. Water droplet transportation experiments further prove that the as-made surface can be effectively used as a mechanical hand for water transportation applications. Based on this, it is believed that the simple method proposed in this paper will pave a new way for producing a sticky superhydrophobic surface and obtain a wide range of use.

On the wettability diversity of C/SiC surface: Comparison of the ground C/SiC surface and ablated C/SiC surface from three aspects

NASA Astrophysics Data System (ADS)

Wu, M. L.; Ren, C. Z.; Xu, H. Z.

2016-11-01

The coefficient of thermal conductivity was influenced by the wetting state of material. The wetting state usually depends on the surface wettability. C/SiC is a promising ceramic composites with multi-components. The wettability of C/SiC composites is hard to resort to the classical wetting theory directly. So far, few investigations focused on C/SiC surface wettability diversity after different material removal processes. In this investigation, comparative studies of surface wettability of ground C/SiC surface and laser-ablated C/SiC surface were carried out through apparent contact angle (APCA) measurements. The results showed that water droplets easily reached stable state on ground C/SiC surface; while the water droplets rappidly penetrated into the laser-ablated C/SiC surface. In order to find out the reason for wettability distinctions between the ground C/SiC surface and the laser-ablated C/SiC surface, comparative studies on the surface micro-structure, surface C-O-Si distribution, and surface C-O-Si weight percentage were carried out. The results showed that (1) A large number of micro cracks in the fuzzy pattern layer over laser-ablated C/SiC surfaces easily destoried the surface tension of water droplets, while only a few cracks existed over the ground C/SiC surfaces. (2) Chemical components (C, O, Si) were non-uniformly distributed on ground C/SiC surfaces, while the chemical components (C, O, Si) were uniformly distributed on laser-ablated C/SiC surfaces. (3) The carbon weight percentage on ground C/SiC surfaces were higher than that on laser-ablated C/SiC surfaces. All these made an essential contribution to the surface wettability diversity of C/SiC surface. Although more investigations about the quantitative influence of surface topography and surface chemical composition on composites wettability are still needed, the conslusion can be used in application: the wettability of C/SiC surface can be controlled by different material removal process without individual following up surface modification process.

Experimental study on water content detection of traditional masonry based on infrared thermal image

NASA Astrophysics Data System (ADS)

Zhang, Baoqing; Lei, Zukang

2017-10-01

Based on infrared thermal imaging technology for seepage test of two kinds of brick masonry, find out the relationship between the distribution of one-dimensional two brick surface temperature distribution and one-dimensional surface moisture content were determined after seepage brick masonry minimum temperature zone and water content determination method of the highest point of the regression equation, the relationship between temperature and moisture content of the brick masonry reflected the quantitative and establish the initial wet masonry building disease analysis method, then the infrared technology is applied to the protection of historic buildings in.

Analysis of the contaminants released from municipal solid waste landfill site: A case study.

PubMed

Samadder, S R; Prabhakar, R; Khan, D; Kishan, D; Chauhan, M S

2017-02-15

Release and transport of leachate from municipal solid waste landfills pose a potential hazard to both surrounding ecosystems and human populations. In the present study, soil, groundwater, and surface water samples were collected from the periphery of a municipal solid waste landfill (located at Ranital of Jabalpur, Madhya Pradesh, India) for laboratory analysis to understand the release of contaminants. The landfill does not receive any solid wastes for dumping now as the same is under a landfill closure plan. Groundwater and soil samples were collected from the bore holes of 15m deep drilled along the periphery of the landfill and the surface water samples were collected from the existing surface water courses near the landfill. The landfill had neither any bottom liner nor any leachate collection and treatment system. Thus the leachate generated from the landfills finds paths into the groundwater and surrounding surface water courses. Concentrations of various physico-chemical parameters including some toxic metals (in collected groundwater, soil, and surface water samples) and microbiological parameters (in surface water samples) were determined. The analyzed data were integrated into ArcGIS environment and the spatial distribution of the metals and other physic- chemical parameter across the landfill was extrapolated to observe the distribution. The statistical analysis and spatial variations indicated the leaching of metals from the landfill to the groundwater aquifer system. The study will help the readers and the municipal engineers to understand the release of contaminants from landfills for better management of municipal solid wastes. Copyright © 2016 Elsevier B.V. All rights reserved.

The diffusive boundary layer of sediments: oxygen microgradients over a microbial mat

NASA Technical Reports Server (NTRS)

Jorgensen, B. B.; Des Marais, D. J.

1990-01-01

Oxygen microelectrodes were used to analyze the distribution of the diffusive boundary layer (DBL) at the sediment-water interface in relation to surface topography and flow velocity. The sediment, collected from saline ponds, was covered by a microbial mat that had high oxygen consumption rate and well-defined surface structure. Diffusion through the DBL constituted an important rate limitation to the oxygen uptake of the sediment. The mean effective DBL thickness decreased from 0.59 to 0.16 mm as the flow velocity of the overlying water was increased from 0.3 to 7.7 cm s-1 (measured 1 cm above the mat). The oxygen uptake rate concurrently increased from 3.9 to 9.4 nmol cm-2 min-1. The effects of surface roughness and topography on the thickness and distribution of the DBL were studied by three-dimensional mapping of the sediment-water interface and the upper DBL boundary at 0.1-mm spatial resolution. The DBL boundary followed mat structures that had characteristic dimensions > 1/2 DBL thickness but the DBL had a dampened relief relative to the mat. The effective surface area of the sediment-water interface and of the upper DBL boundary were 31 and 14% larger, respectively, than a flat plane. Surface topography thereby increased the oxygen flux across the sediment-water interface by 49% relative to a one-dimensional diffusion flux calculated from the vertical oxygen microgradients.

A framework for modeling connections between hydraulics, water surface roughness, and surface reflectance in open channel flows

USGS Publications Warehouse

Legleiter, Carl; Mobley, Curtis D.; Overstreet, Brandon

2017-01-01

This paper introduces a framework for examining connections between the flow field, the texture of the air-water interface, and the reflectance of the water surface and thus evaluating the potential to infer hydraulic information from remotely sensed observations of surface reflectance. We used a spatial correlation model describing water surface topography to illustrate the application of our framework. Nondimensional relations between model parameters and flow intensity were established based on a prior flume study. Expressing the model in the spatial frequency domain allowed us to use an efficient Fourier transform-based algorithm for simulating water surfaces. Realizations for both flume and field settings had water surface slope distributions positively correlated with velocity and water surface roughness. However, most surface facets were gently sloped and thus unlikely to yield strong specular reflections; the model exaggerated the extent of water surface features, leading to underestimation of facet slopes. A ray tracing algorithm indicated that reflectance was greatest when solar and view zenith angles were equal and the sensor scanned toward the Sun to capture specular reflections of the solar beam. Reflected energy was concentrated in a small portion of the sky, but rougher water surfaces reflected rays into a broader range of directions. Our framework facilitates flight planning to avoid surface-reflected radiance while mapping other river attributes, or to maximize this component to exploit relationships between hydraulics and surface reflectance. This initial analysis also highlighted the need for improved models of water surface topography in natural rivers.

A nested observation and model approach to non linear groundwater surface water interactions.

NASA Astrophysics Data System (ADS)

van der Velde, Y.; Rozemeijer, J. C.; de Rooij, G. H.

2009-04-01

Surface water quality measurements in The Netherlands are scattered in time and space. Therefore, water quality status and its variations and trends are difficult to determine. In order to reach the water quality goals according to the European Water Framework Directive, we need to improve our understanding of the dynamics of surface water quality and the processes that affect it. In heavily drained lowland catchment groundwater influences the discharge towards the surface water network in many complex ways. Especially a strong seasonal contracting and expanding system of discharging ditches and streams affects discharge and solute transport. At a tube drained field site the tube drain flux and the combined flux of all other flow routes toward a stretch of 45 m of surface water have been measured for a year. Also the groundwater levels at various locations in the field and the discharge at two nested catchment scales have been monitored. The unique reaction of individual flow routes on rainfall events at the field site allowed us to separate the discharge at a 4 ha catchment and at a 6 km2 into flow route contributions. The results of this nested experimental setup combined with the results of a distributed hydrological model has lead to the formulation of a process model approach that focuses on the spatial variability of discharge generation driven by temporal and spatial variations in groundwater levels. The main idea of this approach is that discharge is not generated by catchment average storages or groundwater heads, but is mainly generated by points scale extremes i.e. extreme low permeability, extreme high groundwater heads or extreme low surface elevations, all leading to catchment discharge. We focused on describing the spatial extremes in point scale storages and this led to a simple and measurable expression that governs the non-linear groundwater surface water interaction. We will present the analysis of the field site data to demonstrate the potential of nested-scale, high frequency observations. The distributed hydrological model results will be used to show transient catchment scale relations between groundwater levels and discharges. These analyses lead to a simple expression that can describe catchment scale groundwater surface water interactions.

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.

Anthropogenic carbon in the ocean—Surface to interior connections

NASA Astrophysics Data System (ADS)

Groeskamp, Sjoerd; Lenton, Andrew; Matear, Richard; Sloyan, Bernadette M.; Langlais, Clothilde

2016-11-01

Quantifying the surface to interior transport of anthropogenic carbon (CA) is critical for projecting future carbon uptake and for improved understanding of the role of the oceans in the global carbon cycle. Here we develop and apply a diagnostic tool that provides a volumetric stream function in (CA,σ0) coordinates to calculate the total diapycnal CA transport in the ocean, where σ0 is the surface referenced potential density anomaly. We combine this with air-sea fluxes of CA to infer the internal ocean mixing of CA to obtain a closed globally integrated budget analyses of the ocean's CA transport. This diagnostic separates the contribution from the mean flow, seasonal cycles, trend, surface fluxes, and mixing in the distribution and the accumulation of CA in the ocean. We find that the redistribution of CA from the surface to the interior of the ocean is due to an interplay between circulation and mixing. The circulation component is dominated by the mean flow; however, effects due to seasonal cycles are significant for the CA redistribution. The two most important pathways for CA subduction are through the transformation of thermocline water (TW) into subantarctic mode water and by transformation of Circumpolar Deep Water (CDW) into lighter Antarctic Intermediate Water. The results suggest that an accurate representation of intermediate and mode water formation, deep water formation, and spatial and temporal distribution of ocean mixing in ocean models is essential to simulate and project the oceanic uptake of CA.

Large- to submesoscale surface circulation and its implications on biogeochemical/biological horizontal distributions during the OUTPACE cruise (southwest Pacific)

NASA Astrophysics Data System (ADS)

Rousselet, Louise; de Verneil, Alain; Doglioli, Andrea M.; Petrenko, Anne A.; Duhamel, Solange; Maes, Christophe; Blanke, Bruno

2018-04-01

The patterns of the large-scale, meso- and submesoscale surface circulation on biogeochemical and biological distributions are examined in the western tropical South Pacific (WTSP) in the context of the OUTPACE cruise (February-April 2015). Multi-disciplinary original in situ observations were achieved along a zonal transect through the WTSP and their analysis was coupled with satellite data. The use of Lagrangian diagnostics allows for the identification of water mass pathways, mesoscale structures, and submesoscale features such as fronts. In particular, we confirmed the existence of a global wind-driven southward circulation of surface waters in the entire WTSP, using a new high-resolution altimetry-derived product, validated by in situ drifters, that includes cyclogeostrophy and Ekman components with geostrophy. The mesoscale activity is shown to be responsible for counter-intuitive water mass trajectories in two subregions: (i) the Coral Sea, with surface exchanges between the North Vanuatu Jet and the North Caledonian Jet, and (ii) around 170° W, with an eastward pathway, whereas a westward general direction dominates. Fronts and small-scale features, detected with finite-size Lyapunov exponents (FSLEs), are correlated with 25 % of surface tracer gradients, which reveals the significance of such structures in the generation of submesoscale surface gradients. Additionally, two high-frequency sampling transects of biogeochemical parameters and microorganism abundances demonstrate the influence of fronts in controlling the spatial distribution of bacteria and phytoplankton, and as a consequence the microbial community structure. All circulation scales play an important role that has to be taken into account not only when analysing the data from OUTPACE but also, more generally, for understanding the global distribution of biogeochemical components.

Investigation of pollution characteristics of polychlorinated biphenyls in the typical drinking water sources in Jiangsu Province, China.

PubMed

Hong, Ye; Chunhong, Zhou; Xiaoxiong, Zeng

2009-11-01

Concentration and composition of polychlorinated biphenyls (PCBs) in the typical drinking water sources in Jiangsu Province were studied by scene investigation and physical and chemical analyses as well. Total amount of PCBs in some surface water and surface microlayers exceeded the standard (20 ng/l) in the "Environmental Quality Standard of Surface Water". There were less PCBs in suspended substances and bottom mud. It reflected that there was less PCB pollution in drinking water sources in Jiangsu Province for quite a long period. The main kind of PCBs in the typical drinking water sources was dichlorobiphenyl. Monochlorobiphenyl and trichlorobiphenyl ranked next to dichlorobiphenyl. In the study of PCB distribution in drinking water sources, it was found that the concentration of PCBs in surface microlayer was higher than that in deep water. The concentration of PCBs along the Yangtze River bank was more than that in the middle of Yangtze River. PCBs in the typical drinking water sources mostly came from by-products in industrial production.

Reactive wetting properties of TiO2 nanoparticles predicted by ab initio molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Brandt, Erik G.; Agosta, Lorenzo; Lyubartsev, Alexander P.

2016-07-01

Small-sized wet TiO2 nanoparticles have been investigated by ab initio molecular dynamics simulations. Chemical and physical adsorption of water on the TiO2-water interface was studied as a function of water content, ranging from dry nanoparticles to wet nanoparticles with monolayer coverage of water. The surface reactivity was shown to be a concave function of water content and driven by surface defects. The local coordination number at the defect was identified as the key factor to decide whether water adsorption proceeds through dissociation or physisorption on the surface. A consistent picture of TiO2 nanoparticle wetting at the microscopic level emerges, which corroborates existing experimental data and gives further insight into the molecular mechanisms behind nanoparticle wetting. These calculations will facilitate the engineering of metal oxide nanoparticles with a controlled catalytic water activity.Small-sized wet TiO2 nanoparticles have been investigated by ab initio molecular dynamics simulations. Chemical and physical adsorption of water on the TiO2-water interface was studied as a function of water content, ranging from dry nanoparticles to wet nanoparticles with monolayer coverage of water. The surface reactivity was shown to be a concave function of water content and driven by surface defects. The local coordination number at the defect was identified as the key factor to decide whether water adsorption proceeds through dissociation or physisorption on the surface. A consistent picture of TiO2 nanoparticle wetting at the microscopic level emerges, which corroborates existing experimental data and gives further insight into the molecular mechanisms behind nanoparticle wetting. These calculations will facilitate the engineering of metal oxide nanoparticles with a controlled catalytic water activity. Electronic supplementary information (ESI) available: Simulation data on equilibration of energies and structures (root-mean-square-deviations and coordination numbers); radial distribution functions for all O-Ti pairs over the entire data domain; comparison of coordination number distributions for dry and wet nanoparticles; dynamics of water reactivity; high-resolution electron density for the rutile NP. A movie of the simulation trajectory for the rutile (TiO2)24.30H2O system. See DOI: 10.1039/C6NR02791A

Thermal desorption of formamide and methylamine from graphite and amorphous water ice surfaces

NASA Astrophysics Data System (ADS)

Chaabouni, H.; Diana, S.; Nguyen, T.; Dulieu, F.

2018-04-01

Context. Formamide (NH2CHO) and methylamine (CH3NH2) are known to be the most abundant amine-containing molecules in many astrophysical environments. The presence of these molecules in the gas phase may result from thermal desorption of interstellar ices. Aims: The aim of this work is to determine the values of the desorption energies of formamide and methylamine from analogues of interstellar dust grain surfaces and to understand their interaction with water ice. Methods: Temperature programmed desorption (TPD) experiments of formamide and methylamine ices were performed in the sub-monolayer and monolayer regimes on graphite (HOPG) and non-porous amorphous solid water (np-ASW) ice surfaces at temperatures 40-240 K. The desorption energy distributions of these two molecules were calculated from TPD measurements using a set of independent Polanyi-Wigner equations. Results: The maximum of the desorption of formamide from both graphite and ASW ice surfaces occurs at 176 K after the desorption of H2O molecules, whereas the desorption profile of methylamine depends strongly on the substrate. Solid methylamine starts to desorb below 100 K from the graphite surface. Its desorption from the water ice surface occurs after 120 K and stops during the water ice sublimation around 150 K. It continues to desorb from the graphite surface at temperatures higher than160 K. Conclusions: More than 95% of solid NH2CHO diffuses through the np-ASW ice surface towards the graphitic substrate and is released into the gas phase with a desorption energy distribution Edes = 7460-9380 K, which is measured with the best-fit pre-exponential factor A = 1018 s-1. However, the desorption energy distribution of methylamine from the np-ASW ice surface (Edes = 3850-8420 K) is measured with the best-fit pre-exponential factor A = 1012 s-1. A fraction of solid methylamine monolayer of roughly 0.15 diffuses through the water ice surface towards the HOPG substrate. This small amount of methylamine desorbs later with higher binding energies (5050-8420 K) that exceed that of the crystalline water ice (Edes = 4930 K), which is calculated with the same pre-exponential factor A = 1012 s-1. The best wetting ability of methylamine compared to H2O molecules makes CH3NH2 molecules a refractory species for low coverage. Other binding energies of astrophysical relevant molecules are gathered and compared, but we could not link the chemical functional groups (amino, methyl, hydroxyl, and carbonyl) with the binding energy properties. Implications of these high binding energies are discussed.

[Spatial-temporal distributions of dissolved inorganic carbon and its affecting factors in the Yellow River estuary].

PubMed

Guo, Xing-Sen; Lü, Ying-Chun; Sun, Zhi-Gao; Wang, Chuan-Yuan; Zhao, Quan-Sheng

2015-02-01

Estuary is an important area contributing to the global carbon cycle. In order to analyze the spatial-temporal distribution characteristics of the dissolved inorganic carbon (DIC) in the surface water of Yellow River estuary. Samples were collected in spring, summer, fall, winter of 2013, and discussed the correlation between the content of DIC and environmental factors. The results show that, the DIC concentration of the surface water in Yellow River estuary is in a range of 26.34-39.43 mg x L(-1), and the DIC concentration in freshwater side is higher than that in the sea side. In some areas where the salinity is less than 15 per thousand, the DIC concentration appears significant losses-the maximum loss is 20.46%. Seasonal distribution of performance in descending order is spring, fall, winter, summer. Through principal component analysis, it shows that water temperature, suspended solids, salinity and chlorophyll a are the main factors affecting the variation of the DIC concentration in surface water, their contribution rate is as high as 83% , and alkalinity, pH, dissolved organic carbon, dissolved oxygen and other factors can not be ignored. The loss of DIC in the low area is due to the calcium carbonate sedimentation. DIC presents a gradually increasing trend, which is mainly due to the effects of water retention time, temperature, outside input and environmental conditions.

[Residue Concentration and Distribution Characteristics of Perfluorinated Compounds in Surface Water from Qiantang River in Hangzhou Section].

PubMed

Zhang, Ming; Tang, Fang-liang; Yu, Ya-yun; Xu, Jian-fen; Li, Hua; Wu, Min-hua; Zhang, Wei; Pan, Jian-yang

2015-12-01

This study studied the pollution characteristics of perfluorinated compounds (PFCs) in Qiantang River in Hangzhou section (QR). Surface water samples, collected in July 2014 and January 2015 from 14 sites in QR were analyzed for 16 PFCs. All samples were prepared by solid-phase extraction with Oasis WAX cartridges and analyzed using the ultra performance liquid chromatography interfaced to tandem mass spectrometry ( UPLC-MS/MS). The results showed that 8 medium-and short-chain PFCs including C₄ and C₈ perfluorinated sulfonates (PFSAs) and C₄-C₉ perfluorinated carboxylic acids (PFCAs) were detected in the surface waters. The total concentrations of PFCs ranged from 0.98 to 609 ng · L⁻¹, while perfluorooctanoic acid (PFOA) dominated, with range of 0.59-538 ng L⁻¹, and perfluorooctane sulfonate (PFOS) was detected at lower levels, ranging from 0 to 2.48 ng · L⁻¹. The spatial distribution of PFCs varied, and the pollutant concentrations at the sampling sites located in upstream of the river such as Lanjiangkou and Jiangjunyan were relatively high, PFCs concentration showed a decreasing trend from the upstream to the downstream. According to the ratio of feature components, PFCs in surface water of QR originated largely from the input of direct sewage emissions. Taken together, the PFCs pollution was highly correlated with the upstream of Qiantang River valley's industry distribution, and most of the mass load in the investigated river was attributed to upstream running water with a minor influence from the wastewater discharges along the river basin. Overall, the results presented here indicated that greater attention should be given to the contamination of PFCs, especially for PFOA in water body of QR.

The response of inorganic carbon distributions and dynamics to upwelling-favorable winds on the northern Gulf of Mexico during summer

NASA Astrophysics Data System (ADS)

Huang, W.-J.; Cai, W.-J.; Wang, Y.; Hu, X.; Chen, B.; Lohrenz, S. E.; Chakraborty, S.; He, R.; Brandes, J.; Hopkinson, C. S.

2015-12-01

Upwelling-favorable winds and an offshore-distributed Mississippi and Atchafalaya River plume trajectory were observed in summer 2009 in contrast to the mean conditions from 2002 to 2010 (upwelling-unfavorable winds and an alongshore river plume trajectory), a set of conditions which was also observed in summer 2007. The responses of dissolved inorganic carbon (DIC) distributions and dynamics to upwelling-favorable winds are studied by comparing the contrasting conditions between summer 2009 and summer 2007 on the northern Gulf of Mexico. Patterns of surface water partial pressure of CO2 (pCO2), DIC, δ13C in DIC, and total alkalinity (TA) determined in July 2009 and August 2007 were strongly related to river plume trajectories, and differed between the two summers. The slope of the relationship between dissolved oxygen (DO) and DIC in summer 2007 was comparable to the Redfield O/C ratio of 1.3, which was attributed to respiration of organic matter in the bottom water. The slope of the DO and DIC relationship and δ13CDIC values in bottom waters during July 2009 were clearly affected by mixing since their salinities were <35. A three end-member mixing model was used to remove mixing effects in (1) δ13CDIC, to estimate the organic source of respiration, and (2) in DIC concentrations, to calculate DIC removal and release. δ13CDIC results in both summers were consistent with an apparent release of DIC in hypoxic waters (DO less than 2 mg L-1) associated with respiration of surface organic matter. The area-weighted surface DIC removal (i.e., biological production) was lower in 2009 than in 2007 on the shelf, as the plume was distributed offshore. The release of DIC in bottom waters was higher over the shelf in 2009 and was surmised to be related to stronger mixing, which was favorable for the DO supply for respiration. Overall, surface waters on the continental shelf in the region of study in July 2009 acted as a weak CO2 source to the atmosphere, but a weak CO2 sink in August 2007. We contend that the inorganic carbon distribution and concentrations on the shelf were related to regional wind forcing, through its influence on the distribution of coastal currents and plume trajectories and their subsequent impact on biogeochemical processes.

Morphological and physicochemical characteristics of iron corrosion scales formed under different water source histories in a drinking water distribution system.

PubMed

Yang, Fan; Shi, Baoyou; Gu, Junnong; Wang, Dongsheng; Yang, Min

2012-10-15

The corrosion scales on iron pipes could have great impact on the water quality in drinking water distribution systems (DWDS). Unstable and less protective corrosion scale is one of the main factors causing "discolored water" issues when quality of water entering into distribution system changed significantly. The morphological and physicochemical characteristics of corrosion scales formed under different source water histories in duration of about two decades were systematically investigated in this work. Thick corrosion scales or densely distributed corrosion tubercles were mostly found in pipes transporting surface water, but thin corrosion scales and hollow tubercles were mostly discovered in pipes transporting groundwater. Magnetite and goethite were main constituents of iron corrosion products, but the mass ratio of magnetite/goethite (M/G) was significantly different depending on the corrosion scale structure and water source conditions. Thick corrosion scales and hard shell of tubercles had much higher M/G ratio (>1.0), while the thin corrosion scales had no magnetite detected or with much lower M/G ratio. The M/G ratio could be used to identify the characteristics and evaluate the performances of corrosion scales formed under different water conditions. Compared with the pipes transporting ground water, the pipes transporting surface water were more seriously corroded and could be in a relatively more active corrosion status all the time, which was implicated by relatively higher siderite, green rust and total iron contents in their corrosion scales. Higher content of unstable ferric components such as γ-FeOOH, β-FeOOH and amorphous iron oxide existed in corrosion scales of pipes receiving groundwater which was less corroded. Corrosion scales on groundwater pipes with low magnetite content had higher surface area and thus possibly higher sorption capacity. The primary trace inorganic elements in corrosion products were Br and heavy metals. Corrosion products obtained from pipes transporting groundwater had higher levels of Br, Ti, Ba, Cu, Sr, V, Cr, La, Pb and As. Copyright © 2012 Elsevier Ltd. All rights reserved.

Water quality monitoring: A comparative case study of municipal and Curtin Sarawak's lake samples

NASA Astrophysics Data System (ADS)

Anand Kumar, A.; Jaison, J.; Prabakaran, K.; Nagarajan, R.; Chan, Y. S.

2016-03-01

In this study, particle size distribution and zeta potential of the suspended particles in municipal water and lake surface water of Curtin Sarawak's lake were compared and the samples were analysed using dynamic light scattering method. High concentration of suspended particles affects the water quality as well as suppresses the aquatic photosynthetic systems. A new approach has been carried out in the current work to determine the particle size distribution and zeta potential of the suspended particles present in the water samples. The results for the lake samples showed that the particle size ranges from 180nm to 1345nm and the zeta potential values ranges from -8.58 mV to -26.1 mV. High zeta potential value was observed in the surface water samples of Curtin Sarawak's lake compared to the municipal water. The zeta potential values represent that the suspended particles are stable and chances of agglomeration is lower in lake water samples. Moreover, the effects of physico-chemical parameters on zeta potential of the water samples were also discussed.

Temporal changes in the vertical distribution of flow and chloride in deep wells.

PubMed

Izbicki, John A; Christensen, Allen H; Newhouse, Mark W; Smith, Gregory A; Hanson, Randall T

2005-01-01

The combination of flowmeter and depth-dependent water-quality data was used to evaluate the quantity and source of high-chloride water yielded from different depths to eight production wells in the Pleasant Valley area of southern California. The wells were screened from 117 to 437 m below land surface, and in most cases, flow from the aquifer into the wells was not uniformly distributed throughout the well screen. Wells having as little as 6 m of screen in the overlying upper aquifer system yielded as much as 50% of their water from the upper system during drought periods, while the deeper parts of the well screens yielded 15% or less of the total yield of the wells. Mixing of water within wells during pumping degraded higher-quality water with poorer-quality water from deeper depths, and in some cases with poorer-quality water from the overlying upper aquifer system. Changes in the mixture of water within a well, resulting from changes in the distribution of flow into the well, changed the quality of water from the surface discharge of wells over time. The combination of flowmeter and depth-dependent water quality data yielded information about sources of high-chloride water to wells that was not available on the basis of samples collected from nearby observation wells. Changing well design to eliminate small quantities of poor-quality water from deeper parts of the well may improve the quality of water from some wells without greatly reducing well yield.

Remote Sensing of Energy Distribution Characteristics over the Tibet

NASA Astrophysics Data System (ADS)

Shi, J.; Husi, L.; Wang, T.

2017-12-01

The overall objective of our study is to quantify the spatiotemporal characteristics and changes of typical factors dominating water and energy cycles in the Tibet region. Especially, we focus on variables of clouds optical & microphysical parameters, surface shortwave and longwave radiation. Clouds play a key role in the Tibetan region's water and energy cycles. They seriously impact the precipitation, temperature and surface energy distribution. Considering that proper cloud products with relatively higher spatial and temporal sampling and with satisfactory accuracy are serious lacking in the Tibet region, except cloud optical thickness, cloud effective radius and liquid/ice water content, the cloud coverage dynamics at hourly scales also analyzed jointly based on measurements of Himawari-8, and MODIS. Surface radiation, as an important energy source in perturbating the Tibet's evapotranspiration, snow and glacier melting, is a controlling factor in energy balance in the Tibet region. All currently available radiation products in this area are not suitable for regional scale study of water and energy exchange and snow/glacier melting due to their coarse resolution and low accuracies because of cloud and topography. A strategy for deriving land surface upward and downward radiation by fusing optical and microwave remote sensing data is proposed. At the same time, the big topographic effect on the surface radiation are also modelled and analyzed over the Tibet region.

Quantitatively identifying the roles of interfacial water and solid surface in governing peptide adsorption.

PubMed

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

2018-06-11

Understanding the molecular mechanism of protein adsorption on solids is critical to their applications in materials synthesis and tissue engineering. Though the water phase at the surface/water interface has been recognized as three types: free water in the bulk region, intermediate water phase and surface-bound water layers adjacent to the surface, the roles of the water and surface in determining the protein adsorption are not clearly identified, particularly at the quantitative level. Herein, we provide a methodology involving the combination of microsecond strengthen sampling simulation and force integration to quantitatively characterize the water-induced contribution and the peptide-surface interactions into the adsorption free energy. Using hydroxyapatite and graphene surfaces as examples, we demonstrate how the distinct interfacial features dominate the delicate force balance between these two thermodynamics parameters, leading to surface preference/resistance to peptide adsorption. Specifically, the water layer provides sustained repelling force against peptide adsorption, as indicated by a monotonic increase in the water-induced free energy profile, whereas the contribution to the free energy from the surface effect is thermodynamically favorable, thus acting as the dominant driving force for peptide adsorptions. More importantly, the revealed adsorption mechanism is critically dictated by the distribution of water phase at the solid/water interface, which plays a crucial role in establishing the force balance between the interactions of the peptide with the water layer and the surface. For the HAP surface, the charged peptide exhibits strong binding affinity to the surface, which is ascribed to the controlling contribution of peptide-surface interaction in the intermediate water phase and the surface-bound water layers are observed as the origin of bioresistance of solid surfaces towards the adsorption of charge-neutral peptides. The preferred peptide adsorption on the graphene, however, is dominated by the surface-induced component at the water layers adjacent to the surface. Our results further elucidate that the intermediate water phase significantly shortens the effective range of the surface dispersion force to guide the diffusion of the peptide to the interface, in sharp contrast to the observation in interfacial systems involving the strong water-surface interaction.

Increasing sea surface temperature and range shifts of intertidal gastropods along the Iberian Peninsula

NASA Astrophysics Data System (ADS)

Rubal, Marcos; Veiga, Puri; Cacabelos, Eva; Moreira, Juan; Sousa-Pinto, Isabel

2013-03-01

There are well-documented changes in abundance and geographical range of intertidal invertebrates related to climate change at north Europe. However, the effect of sea surface warming on intertidal invertebrates has been poorly studied at lower latitudes. Here we analyze potential changes in the abundance patterns and distribution range of rocky intertidal gastropods related to climate change along the Iberian Peninsula. To achieve this aim, the spatial distribution and range of sub-tropical, warm- and cold-water species of intertidal gastropods was explored by a fully hierarchical sampling design considering four different spatial scales, i.e. from region (100 s of km apart) to quadrats (ms apart). Variability on their patterns of abundance was explored by analysis of variance, changes on their distribution ranges were detected by comparing with previous records and their relationship with sea water temperature was explored by rank correlation analyses. Mean values of sea surface temperature along the Iberian coast, between 1949 and 2010, were obtained from in situ data compiled for three different grid squares: south Portugal, north Portugal, and Galicia. Lusitanian species did not show significant correlation with sea water temperature or changes on their distributional range or abundance, along the temperature gradient considered. The sub-tropical species Siphonaria pectinata has, however, increased its distribution range while boreal cold-water species showed the opposite pattern. The latter was more evident for Littorina littorea that was almost absent from the studied rocky shores of the Iberian Peninsula. Sub-tropical and boreal species showed significant but opposite correlation with sea water temperature. We hypothesized that the energetic cost of frequent exposures to sub-lethal temperatures might be responsible for these shifts. Therefore, intertidal gastropods at the Atlantic Iberian Peninsula coast are responding to the effect of global warming as it is happening at higher latitudes. However, the identity of the species showing changes in their range of distribution was different.

A preliminary study of the tropical water cycle and its sensitivity to surface warming

NASA Technical Reports Server (NTRS)

Lau, K. M.; Sui, C. H.; Tao, W. K.

1993-01-01

The Goddard Cumulus Ensemble Model (GCEM) has been used to demonstrate that cumulus-scale dynamics and microphysics play a major role in determining the vertical distribution of water vapor and clouds in the tropical atmosphere. The GCEM is described and is the basic structure of cumulus convection. The long-term equilibrium response to tropical convection to surface warming is examined. A picture of the water cycle within tropical cumulus clusters is developed.

Data Summary Report for teh Remedial Investigation of Hanford Site Releases to the Columbia River, Hanford Site, Washington

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

Hulstrom, L.

2011-02-07

This data summary report summarizes the investigation results to evaluate the nature and distribution of Hanford Site-related contaminants present in the Columbia River. As detailed in DOE/RL-2008-11, more than 2,000 environmental samples were collected from the Columbia River between 2008 and 2010. These samples consisted of island soil, sediment, surface water, groundwater upwelling (pore water, surface water, and sediment), and fish tissue.

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.

Spatial distribution and migration of nonylphenol in groundwater following long-term wastewater irrigation.

PubMed

Wang, Shiyu; Wu, Wenyong; Liu, Fei; Yin, Shiyang; Bao, Zhe; Liu, Honglu

2015-01-01

Seen as a solution to water shortages, wastewater reuse for crop irrigation does however poses a risk owing to the potential release of organic contaminants into soil and water. The frequency of detection (FOD), concentration, and migration of nonylphenol (NP) isomers in reclaimed water (FODRW), surface water (FODSW), and groundwater (FODGW) were investigated in a long-term wastewater irrigation area in Beijing. The FODRW, FODSW and FODGW of any or all of 12 NP isomers were 66.7% to 100%, 76.9% to 100% and 13.3% to 60%, respectively. The mean (±standard deviation) NP concentrations of the reclaimed water, surface water, and groundwater (NPRW, NPSW, NPGW, repectively) were 469.4±73.4 ng L(-1), 694.6±248.7 ng(-1) and 244.4±230.8 ng(-1), respectively. The existence of external pollution sources during water transmission and distribution resulted in NPSW exceeding NPRW. NP distribution in groundwater was related to the duration and quantity of wastewater irrigation, the sources of aquifer recharge, and was seen to decrease with increasing aquifer depth. Higher riverside infiltration rate nearby leads to higher FODGW values. The migration rate of NP isomers was classified as high, moderate or low. Copyright © 2015 Elsevier B.V. All rights reserved.

Earthquake hazards to domestic water distribution systems in Salt Lake County, Utah

USGS Publications Warehouse

Highland, Lynn M.

1985-01-01

A magnitude-7. 5 earthquake occurring along the central portion of the Wasatch Fault, Utah, may cause significant damage to Salt Lake County's domestic water system. This system is composed of water treatment plants, aqueducts, distribution mains, and other facilities that are vulnerable to ground shaking, liquefaction, fault movement, and slope failures. Recent investigations into surface faulting, landslide potential, and earthquake intensity provide basic data for evaluating the potential earthquake hazards to water-distribution systems in the event of a large earthquake. Water supply system components may be vulnerable to one or more earthquake-related effects, depending on site geology and topography. Case studies of water-system damage by recent large earthquakes in Utah and in other regions of the United States offer valuable insights in evaluating water system vulnerability to earthquakes.

Interactions of infectious F-specific RNA bacteriophages with suspended matter and sediment: Towards an understanding of FRNAPH distribution in a river water system.

PubMed

Fauvel, Blandine; Ogorzaly, Leslie; Cauchie, Henry-Michel; Gantzer, Christophe

2017-01-01

The association of viruses with settling particles is certainly a major process controlling the spread of viral pollution in surface water and sediment. To better understand the viral distribution in a river system, the behavior of F-specific RNA bacteriophages (FRNAPHs) was investigated in relationship with the suspended solids and sediment. The partitioning of phage particles (free or associated with solids) in surface water and the attachment capabilities of eight distinct strains of phages to sediment were studied in lab experiments. In situ observations were also performed with the genotyping of 166 individual plaques of FRNAPHs isolated from surface water and sediment. The results reported here demonstrate a variation of the status of infectious phages as a function of the hydro-climatological conditions. Phage-solid association seems to mainly occur during the peak of rainfall-runoff events but also to a certain extent during the recession phase compared to low flow conditions. The transfer of phages from the water column to sediment may occur at this time. Furthermore, the ability of FRNAPHs to interact with sediment was established for six strains out of eight, belonging to genogroups II, III and IV. A similar dynamic was observed for strains within a same genogroup despite different intensity of attachment and inactivation rates for strains of genogroups III and IV. The latter results match the in situ observations in the water and sediment compartments of the studied area. Infectious FRNAPH genogroup II was more abundant in sediment than in surface water. Its capability to sorb to sediment and its higher persistence in the environment compared to genogroups III and IV were the two main explanations. Together, lab and in situ experiments produce an overall vision of the mechanisms governing FRNAPH distribution among the water column and riverbed sediment. Copyright © 2016 Office national des forêts. Published by Elsevier B.V. All rights reserved.

[Spatial Distribution Characteristics of Different Species Mercury in Water Body of Changshou Lake in Three Gorges Reservoir Region].

PubMed

Bai, Wei-yang; Zhang, Cheng; Zhao, Zheng; Tang, Zhen-ya; Wang, Ding-yong

2015-08-01

An investigation on the concentrations and the spatial distribution characteristics of different species of mercury in the water body of Changshou Lake in Three Gorges Reservoir region was carried out based on the AreGIS statistics module. The results showed that the concentration of the total mercury in Changshou Lake surface water ranged from 0.50 to 3.78 ng x L(-1), with an average of 1.51 ng x L(-1); the concentration of the total MeHg (methylmercury) ranged from 0.10 to 0.75 ng x L(-1), with an average of 0.23 ng x L(-1). The nugget effect value of total mercury in surface water (50.65%), dissolved mercury (49.80%), particulate mercury (29.94%) and the activity mercury (26.95%) were moderate spatial autocorrelation. It indicated that the autocorrelation was impacted by the intrinsic properties of sediments (such as parent materials and rocks, geological mineral and terrain), and on the other hand it was also disturbed by the exogenous input factors (such as aquaculture, industrial activities, farming etc). The nugget effect value of dissolved methylmercury (DMeHg) in Changshou lake surface water (3.49%) was less than 25%, showing significant strong spatial autocorrelation. The distribution was mainly controlled by environmental factors in water. The proportion of total MeHg in total Hg in Changshou Lake water reached 30% which was the maximum ratio of the total MeHg to total Hg in freshwater lakes and rivers. It implied that mercury was easily methylated in the environment of Chanashou Lake.

THE ACCUMULATION AND RELEASE OF CONTAMINANTS FROM DISTRIBUTION SYSTEM SOLIDS

EPA Science Inventory

The recently promulgated Arsenic Rule will require that many new drinking water systems treat their water to remove arsenic. Iron based treatment technologies including iron removal and iron coagulation are effective at reducing arsenic in water because iron surfaces have a stron...

43 CFR 418.35 - Efficiencies.

Code of Federal Regulations, 2011 CFR

2011-10-01

... of entitlement water actually delivered at the headgates. Since most of the distribution system losses such as evaporation and seepage do not change significantly with the amount of water delivered (i.e., these losses are principally a function of water surface area and the wetted perimeter of the...

43 CFR 418.35 - Efficiencies.

Code of Federal Regulations, 2010 CFR

2010-10-01

... of entitlement water actually delivered at the headgates. Since most of the distribution system losses such as evaporation and seepage do not change significantly with the amount of water delivered (i.e., these losses are principally a function of water surface area and the wetted perimeter of the...

43 CFR 418.35 - Efficiencies.

Code of Federal Regulations, 2012 CFR

2012-10-01

... of entitlement water actually delivered at the headgates. Since most of the distribution system losses such as evaporation and seepage do not change significantly with the amount of water delivered (i.e., these losses are principally a function of water surface area and the wetted perimeter of the...

43 CFR 418.35 - Efficiencies.

Code of Federal Regulations, 2014 CFR

2014-10-01

... of entitlement water actually delivered at the headgates. Since most of the distribution system losses such as evaporation and seepage do not change significantly with the amount of water delivered (i.e., these losses are principally a function of water surface area and the wetted perimeter of the...

43 CFR 418.35 - Efficiencies.

Code of Federal Regulations, 2013 CFR

2013-10-01

... of entitlement water actually delivered at the headgates. Since most of the distribution system losses such as evaporation and seepage do not change significantly with the amount of water delivered (i.e., these losses are principally a function of water surface area and the wetted perimeter of the...

Molecular dynamics simulation of sodium aluminosilicate glass structures and glass surface-water reactions using the reactive force field (ReaxFF)

NASA Astrophysics Data System (ADS)

Dongol, R.; Wang, L.; Cormack, A. N.; Sundaram, S. K.

2018-05-01

Reactive potentials are increasingly used to study the properties of glasses and glass water reactions in a reactive molecular dynamics (MD) framework. In this study, we have simulated a ternary sodium aluminosilicate glass and investigated the initial stages of the glass surface-water reactions at 300 K using reactive force field (ReaxFF). On comparison of the simulated glass structures generated using ReaxFF and classical Buckingham potentials, our results show that the atomic density profiles calculated for the surface glass structures indicate a bond-angle distribution dependency. The atomic density profiles also show higher concentrations of non-bridging oxygens (NBOs) and sodium ions at the glass surface. Additionally, we present our results of formation of silanol species and the diffusion of water molecules at the glass surface using ReaxFF.

Spatial heterogeneity of mobilization processes and input pathways of herbicides into a brook in a small agricultural catchment

NASA Astrophysics Data System (ADS)

Doppler, Tobias; Lück, Alfred; Popow, Gabriel; Strahm, Ivo; Winiger, Luca; Gaj, Marcel; Singer, Heinz; Stamm, Christian

2010-05-01

Soil applied herbicides can be transported from their point of application (agricultural field) to surface waters during rain events. There they can have harmful effects on aquatic species. Since the spatial distribution of mobilization and transport processes is very heterogeneous, the contributions of different fields to the total load in a surface water body may differ considerably. The localization of especially critical areas (contributing areas) can help to efficiently minimize herbicide inputs to surface waters. An agricultural field becomes a contributing area when three conditions are met: 1) herbicides are applied, 2) herbicides are mobilized on the field and 3) the mobilized herbicides are transported rapidly to the surface water. In spring 2009, a controlled herbicide application was performed on corn fields in a small (ca 1 km2) catchment with intensive crop production in the Swiss plateau. Subsequently water samples were taken at different locations in the catchment with a high temporal resolution during rain events. We observed both saturation excess and hortonian overland flow during the field campaign. Both can be important mobilization processes depending on the intensity and quantity of the rain. This can lead to different contributing areas during different types of rain events. We will show data on the spatial distribution of herbicide loads during different types of rain events. Also the connectivity of the fields with the brook is spatially heterogeneous. Most of the fields are disconnected from the brook by internal sinks in the catchment, which prevents surface runoff from entering the brook directly. Surface runoff from these disconnected areas can only enter the brook rapidly via macropore-flow into tile drains beneath the internal sinks or via direct shortcuts to the drainage system (maintenance manholes, farmyard or road drains). We will show spatially distributed data on herbicide concentration in purely subsurface systems which shows how important such input pathways can be.

Surface speciation of phosphate on goethite as seen by InfraRed Surface Titrations (IRST)

NASA Astrophysics Data System (ADS)

Arroyave, Jeison Manuel; Puccia, Virginia; Zanini, Graciela P.; Avena, Marcelo J.

2018-06-01

Phosphate adsorption at the metal oxide-water interface has been intensely studied, and the system phosphate-goethite in aqueous media is normally used as a model system with abundant information regarding adsorption-desorption under very different conditions. In spite of this, there is still discussion on whether the main inner-sphere surface complexes that phosphate forms on goethite are monodentate or bidentate. A new spectroscopic technique, InfraRed Surface Titration (IRST), is presented here and used to systematically explore the surface speciation of phosphate on goethite in the pH range 4.5-9.5 at different surface coverages. IRST enabled to construct distribution curves of surface species and distribution curves of dissolved phosphate species. In combination with the CD-MUSIC surface complexation model it was possible to conclude that surface complexes are monodentate. Very accurate distribution curves were obtained, showing a crossing point at pH 5.5 at a surface coverage of 2.0 μmol m-2, with a mononuclear monoprotonated species predominating at pH > 5.5 and a mononuclear diprotonated species prevailing at pH < 5.5. On the contrary, at the low surface coverage of 0.7 μmol m-2 there is no crossing point, with the mononuclear monoprotonated species prevailing at all pH. IRST can become a powerful technique to investigate structure, properties and reactions of any IR-active surface complex at the solid-water interface.

Low Concentration of Salmonella enterica and Generic Escherichia coli in Farm Ponds and Irrigation Distribution Systems Used for Mixed Produce Production in Southern Georgia.

PubMed

Antaki, Elizabeth M; Vellidis, George; Harris, Casey; Aminabadi, Peiman; Levy, Karen; Jay-Russell, Michele T

2016-10-01

Studies have shown that irrigation water can be a vector for pathogenic bacteria. Due to this, the Food Safety Modernization Act's (FSMA) produce safety rule requires that agricultural water directly applied to produce be safe and of adequate sanitary quality for use, which may pose a challenge for some farmers. The purpose of this research was to assess the presence and concentration of Salmonella and generic Escherichia coli in irrigation water from distribution systems in a mixed produce production region of southern Georgia. Water samples were collected during three growing seasons at three farms irrigating crops with surface water (Pond 1, Pond 2) or groundwater (Well) during 2012-2013. Salmonella and generic E. coli populations were monitored by culture and Most Probable Number (MPN). Confirmed isolates were characterized by pulsed-field gel electrophoresis and serotyping. In Pond 1, Salmonella was detected in 2/21 surface, 5/26 subsurface, 10/50 center pivot, and 0/16 solid set sprinkler head water samples. In Pond 2, Salmonella was detected in 2/18 surface, 1/18 subsurface, 6/36 drip line start, and 8/36 drip line end water samples. Twenty-six well pumps and 64 associated drip line water samples were negative. The overall mean Salmonella concentration for positive water samples was 0.03 MPN/100 mL (range <0.0011-1.8 MPN/100 mL). Nine Salmonella serovars comprising 22 pulsotypes were identified. Identical serovars and subtypes were found three times on the same day and location: Pond 1-Pivot-Cantaloupe (serovar Rubislaw), Pond 1-Pivot-Peanut (serovar Saintpaul), and Pond 2-Drip Line Start-Drip Line End-Yellow Squash (serovar III_16z10:e,n,x,z15). Generic E. coli was detected in water from both farm ponds and irrigation distribution systems, but the concentrations met FSMA microbial water quality criteria. The results from this study will allow producers in southern Georgia to better understand how potential pathogens move through irrigation distribution systems.

Environmental DNA reflects spatial and temporal jellyfish distribution

PubMed Central

Fukuda, Miho; Katsuhara, Koki R.; Fujiwara, Ayaka; Hidaka, Shunsuke; Yamamoto, Satoshi; Takahashi, Kohji; Masuda, Reiji

2017-01-01

Recent development of environmental DNA (eDNA) analysis allows us to survey underwater macro-organisms easily and cost effectively; however, there have been no reports on eDNA detection or quantification for jellyfish. Here we present the first report on an eDNA analysis of marine jellyfish using Japanese sea nettle (Chrysaora pacifica) as a model species by combining a tank experiment with spatial and temporal distribution surveys. We performed a tank experiment monitoring eDNA concentrations over a range of time intervals after the introduction of jellyfish, and quantified the eDNA concentrations by quantitative real-time PCR. The eDNA concentrations peaked twice, at 1 and 8 h after the beginning of the experiment, and became stable within 48 h. The estimated release rates of the eDNA in jellyfish were higher than the rates previously reported in fishes. A spatial survey was conducted in June 2014 in Maizuru Bay, Kyoto, in which eDNA was collected from surface water and sea floor water samples at 47 sites while jellyfish near surface water were counted on board by eye. The distribution of eDNA in the bay corresponded with the distribution of jellyfish inferred by visual observation, and the eDNA concentration in the bay was ~13 times higher on the sea floor than on the surface. The temporal survey was conducted from March to November 2014, in which jellyfish were counted by eye every morning while eDNA was collected from surface and sea floor water at three sampling points along a pier once a month. The temporal fluctuation pattern of the eDNA concentrations and the numbers of observed individuals were well correlated. We conclude that an eDNA approach is applicable for jellyfish species in the ocean. PMID:28245277

A Web Application for Validating and Disseminating Surface Energy Balance Evapotranspiration Estimates for Hydrologic Modeling Applications

NASA Astrophysics Data System (ADS)

Schneider, C. A.; Aggett, G. R.; Nevo, A.; Babel, N. C.; Hattendorf, M. J.

2008-12-01

The western United States face an increasing threat from drought - and the social, economic, and environmental impacts that come with it. The combination of diminished water supplies along with increasing demand for urban and other uses is rapidly depleting surface and ground water reserves traditionally allocated for agricultural use. Quantification of water consumptive use is increasingly important as water resources are placed under growing tension by increased users and interests. Scarce water supplies can be managed more efficiently through use of information and prediction tools accessible via the internet. METRIC (Mapping ET at high Resolution with Internalized Calibration) represents a maturing technology for deriving a remote sensing-based surface energy balance for estimating ET from the earth's surface. This technology has the potential to become widely adopted and used by water resources communities providing critical support to a host of water decision support tools. ET images created using METRIC or similar remote- sensing based processing systems could be routinely used as input to operational and planning models for water demand forecasting, reservoir operations, ground-water management, irrigation water supply planning, water rights regulation, and for the improvement, validation, and use of hydrological models. The ET modeling and subsequent validation and distribution of results via the web presented here provides a vehicle through which METRIC ET parameters can be made more accessible to hydrologic modelers. It will enable users of the data to assess the results of the spatially distributed ET modeling and compare with results from conventional ET estimation methods prior to assimilation in surface and ground water models. In addition, this ET-Server application will provide rapid and transparent access to the data enabling quantification of uncertainties due to errors in temporal sampling and METRIC modeling, while the GIS-based analytical tools will facilitate quality assessments associated with the selected spatio-temporal scale of interest.

Origin of the Valley Networks On Mars: A Hydrological Perspective

NASA Technical Reports Server (NTRS)

Gulick, Virginia C.

2000-01-01

The geomorphology of the Martian valley networks is examined from a hydrological perspective for their compatibility with an origin by rainfall, globally higher heat flow, and localized hydrothermal systems. Comparison of morphology and spatial distribution of valleys on geologic surfaces with terrestrial fluvial valleys suggests that most Martian valleys are probably not indicative of a rainfall origin, nor are they indicative of formation by an early global uniformly higher heat flow. In general, valleys are not uniformly distributed within geologic surface units as are terrestrial fluvial valleys. Valleys tend to form either as isolated systems or in clusters on a geologic surface unit leaving large expanses of the unit virtually untouched by erosion. With the exception of fluvial valleys on some volcanoes, most Martian valleys exhibit a sapping morphology and do not appear to have formed along with those that exhibit a runoff morphology. In contrast, terrestrial sapping valleys form from and along with runoff valleys. The isolated or clustered distribution of valleys suggests localized water sources were important in drainage development. Persistent ground-water outflow driven by localized, but vigorous hydrothermal circulation associated with magmatism, volcanism, impacts, or tectonism is, however, consistent with valley morphology and distribution. Snowfall from sublimating ice-covered lakes or seas may have provided an atmospheric water source for the formation of some valleys in regions where the surface is easily eroded and where localized geothermal/hydrothermal activity is sufficient to melt accumulated snowpacks.

Selected field and analytical methods and analytical results in the Dutch Flats area, western Nebraska, 1995-99

USGS Publications Warehouse

Verstraeten, Ingrid M.; Steele, G.V.; Cannia, J.C.; Bohlke, J.K.; Kraemer, T.E.; Hitch, D.E.; Wilson, K.E.; Carnes, A.E.

2001-01-01

A study of the water resources of the Dutch Flats area in the western part of the North Platte Natural Resources District, western Nebraska, was conducted from 1995 through 1999 to describe the surface water and hydrogeology, the spatial distribution of selected water-quality constituents in surface and ground water, and the surface-water/ground-water interaction in selected areas. This report describes the selected field and analytical methods used in the study and selected analytical results from the study not previously published. Specifically, dissolved gases, age-dating data, and other isotopes collected as part of an intensive sampling effort in August and November 1998 and all uranium and uranium isotope data collected through the course of this study are included in the report.

Direct numerical solution of the Ornstein-Zernike integral equation and spatial distribution of water around hydrophobic molecules

NASA Astrophysics Data System (ADS)

Ikeguchi, Mitsunori; Doi, Junta

1995-09-01

The Ornstein-Zernike integral equation (OZ equation) has been used to evaluate the distribution function of solvents around solutes, but its numerical solution is difficult for molecules with a complicated shape. This paper proposes a numerical method to directly solve the OZ equation by introducing the 3D lattice. The method employs no approximation the reference interaction site model (RISM) equation employed. The method enables one to obtain the spatial distribution of spherical solvents around solutes with an arbitrary shape. Numerical accuracy is sufficient when the grid-spacing is less than 0.5 Å for solvent water. The spatial water distribution around a propane molecule is demonstrated as an example of a nonspherical hydrophobic molecule using iso-value surfaces. The water model proposed by Pratt and Chandler is used. The distribution agrees with the molecular dynamics simulation. The distribution increases offshore molecular concavities. The spatial distribution of water around 5α-cholest-2-ene (C27H46) is visualized using computer graphics techniques and a similar trend is observed.

How Properties of Solid Surfaces Modulate the Nucleation of Gas Hydrate

PubMed Central

Bai, Dongsheng; Chen, Guangjin; Zhang, Xianren; Sum, Amadeu K.; Wang, Wenchuan

2015-01-01

Molecular dynamics simulations were performed for CO2 dissolved in water near silica surfaces to investigate how the hydrophilicity and crystallinity of solid surfaces modulate the local structure of adjacent molecules and the nucleation of CO2 hydrates. Our simulations reveal that the hydrophilicity of solid surfaces can change the local structure of water molecules and gas distribution near liquid-solid interfaces, and thus alter the mechanism and dynamics of gas hydrate nucleation. Interestingly, we find that hydrate nucleation tends to occur more easily on relatively less hydrophilic surfaces. Different from surface hydrophilicity, surface crystallinity shows a weak effect on the local structure of adjacent water molecules and on gas hydrate nucleation. At the initial stage of gas hydrate growth, however, the structuring of molecules induced by crystalline surfaces are more ordered than that induced by amorphous solid surfaces. PMID:26227239

78 FR 4165 - Notice of Availability of the Draft Environmental Impact Statement for the Arturo Mine Project...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-18

... office, substation and associated power transmission lines, water wells, water distribution and sewer...; access; discharges to surface water; air quality (including mercury); and impacts to stream drainages... which may impact water resources, and the Elko County Board of Commissioners have raised concerns about...

40 CFR 141.63 - Maximum contaminant levels (MCLs) for microbiological contaminants.

Code of Federal Regulations, 2013 CFR

2013-07-01

... parts of the distribution system; (4) Filtration and/or disinfection of surface water, as described in subparts H, P, T, and W of this part, or disinfection of ground water, as described in subpart S of this... (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS National Primary Drinking...

40 CFR 141.63 - Maximum contaminant levels (MCLs) for microbiological contaminants.

Code of Federal Regulations, 2014 CFR

2014-07-01

... parts of the distribution system; (4) Filtration and/or disinfection of surface water, as described in subparts H, P, T, and W of this part, or disinfection of ground water, as described in subpart S of this... (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS National Primary Drinking...

Occurrence and fate of the angiotensin II receptor antagonist transformation product valsartan acid in the water cycle--a comparative study with selected β-blockers and the persistent anthropogenic wastewater indicators carbamazepine and acesulfame.

PubMed

Nödler, Karsten; Hillebrand, Olav; Idzik, Krzysztof; Strathmann, Martin; Schiperski, Ferry; Zirlewagen, Johannes; Licha, Tobias

2013-11-01

The substantial transformation of the angiotensin II receptor antagonist valsartan to the transformation product 2'-(2H-tetrazol-5-yl)-[1,1'-biphenyl]-4-carboxylic acid (referred to as valsartan acid) during the activated sludge process was demonstrated in the literature and confirmed in the here presented study. However, there was a severe lack of knowledge regarding the occurrence and fate of this compound in surface water and its behavior during drinking water treatment. In this work a comparative study on the occurrence and persistency of valsartan acid, three frequently used β-blockers (metoprolol, atenolol, and sotalol), atenolol acid (one significant transformation product of atenolol and metoprolol), and the two widely distributed persistent anthropogenic wastewater indicators carbamazepine and acesulfame in raw sewage, treated wastewater, surface water, groundwater, and tap water is presented. Median concentrations of valsartan acid in the analyzed matrices were 101, 1,310, 69, <1.0, and 65 ng L(-1), respectively. Treated effluents from wastewater treatment plants were confirmed as significant source. Regarding concentration levels of pharmaceutical residues in surface waters valsartan acid was found just as relevant as the analyzed β-blockers and the anticonvulsant carbamazepine. Regarding its persistency in surface waters it was comparable to carbamazepine and acesulfame. Furthermore, removal of valsartan acid during bank filtration was poor, which demonstrated the relevance of this compound for drinking water suppliers. Regarding drinking water treatment (Muelheim Process) the compound was resistant to ozonation but effectively eliminated (≥90%) by subsequent activated carbon filtration. However, without applying activated carbon filtration the compound may enter the drinking water distribution system as it was demonstrated for Berlin tap water. Copyright © 2013 Elsevier Ltd. All rights reserved.

Longitudinal and Source-to-Tap New Orleans, LA, U.S.A. Drinking Water Microbiology.

PubMed

Hull, Natalie M; Holinger, Eric P; Ross, Kimberly A; Robertson, Charles E; Harris, J Kirk; Stevens, Mark J; Pace, Norman R

2017-04-18

The two municipal drinking water systems of New Orleans, LA, U.S.A. were sampled to compare the microbiology of independent systems that treat the same surface water from the Mississippi River. To better understand temporal trends and sources of microbiology delivered to taps, these treatment plants and distribution systems were subjected to source-to-tap sampling over four years. Both plants employ traditional treatment by chloramination, applied during or after settling, followed by filtration before distribution in a warm, low water age system. Longitudinal samples indicated microbiology to have stability both spatially and temporally, and between treatment plants and distribution systems. Disinfection had the greatest impact on microbial composition, which was further refined by filtration and influenced by distribution and premise plumbing. Actinobacteria spp. exhibited trends with treatment. In particular, Mycobacterium spp., very low in finished waters, occurred idiosyncratically at high levels in some tap waters, indicating distribution and/or premise plumbing as main contributors of mycobacteria. Legionella spp., another genus containing potential opportunistic pathogens, also occurred ubiquitously. Source water microbiology was most divergent from tap water, and each step of treatment brought samples more closely similar to tap waters.

Analysis of water application efficiency and emission uniformity of drip irrigation systems based on space-time analysis of soil moisture patterns in soils

NASA Astrophysics Data System (ADS)

Shabeeb, Ahmeed; Taha, Uday; dragonetti, giovanna; Lamaddalena, Nicola; Coppola, Antonio

2016-04-01

In order to evaluate how efficiently and uniformly drip irrigation systems can deliver water to emitters distributed around a field, we need some methods for measuring/calculating water application efficiency (WAE) and emission uniformity (EU). In general, the calculation of the WAE and of other efficiency indices requires the measurement of the water stored in the root zone. Measuring water storage in soils allows directly saying how much water a given location of the field retains having received a given amount of irrigation water. And yet, due to the difficulties of measuring water content variability under an irrigation system at field scale, it is quite common using EU as a proxy indicator of the irrigation performance. This implicitly means assuming that the uniformity of water application is immediately reflected in an uniformity of water stored in the root zone. In other words, that if a site receive more water it will store more water. Nevertheless, due to the heterogeneity of soil hydrological properties the same EU may correspond to very different distributions of water stored in the soil root zone. 1) In the case of isolated drippers, the storages measured in the soil root zone layer shortly after an irrigation event may be or not different from the water height applied at the surface depending on the vertical/horizontal development of the wetted bulbs. Specifically, in the case of dominant horizontal spreading the water storage is expected to reflect the distribution of water applied at the surface. To the contrary, in the case of relatively significant vertical spreading, deep percolation fluxes (fluxes leaving the root zone) may well induce water storages in the root zone significantly different from the water applied at the surface. 2) The drippers and laterals are close enough that the wetted bulbs below adjacent drippers may interact. In this case, lateral fluxes in the soil may well induce water storages in the root zone which may be significantly uncorrelated with the uniformity of the water applied at the surface. In both the cases, the size of lateral fluxes compared to the vertical ones throughout the rooting zone depends, besides the soil hydraulic properties, on the amount of water delivered to the soil. Larger water applications produce greater spreading, but in both the horizontal and vertical directions. Increased vertical spreading may be undesirable because water moving below the active root zone can result in wasted water, loss of nutrients, and groundwater pollution.

Spatial Distribution of Triclosan in Sediments and Water of an Urbanized Estuarine Embayment

EPA Science Inventory

Triclosan (TCS) is a broad spectrum anti-microbial compound found in many consumer and personal care products. TCS enters water bodies primarily through wastewater treatment plant (WWTP) effluent and may also be introduced by combined sewer overflows or surface water runoff. TC...

SENSITIVITY OF DIFFERENT AEROMONAS SPECIES TO COPPER AND SILVER

EPA Science Inventory

Aeromonas bacteria are common flora in surface and ground waters and are considered to be human pathogens. They can also be found in municipally treated drinking water, likely as a component of biofilms, as found in distribution system pipes and point of use water filters. It ...

Coadsorption of Human Milk Lactoferrin into the Dipalmitoylglycerolphosphatidylcholine Phospholipid Monolayer Spread at the Air/Water Interface

PubMed Central

Miano, Fausto; Zhao, Xiubo; Lu, Jian R.; Penfold, Jeff

2007-01-01

The coadsorption of human milk lactoferrin into a spread monolayer of dipalmitoylglycerol phosphatidylcholine (DPPC) at the air/water interface has been studied by neutron reflection. The system is a good model of the preocular tear film outer interface, which was the motivation for the study. The association of the protein with the surface was indicated by an increase of the surface pressure exerted by the DPPC monolayer. The extent of lactoferrin coadsorption was found to decrease with increasing surface pressure in the lipid monolayer, a trend consistent with the observation reported for other proteins, such as lysozyme and β-lactoglobulin. The neutron reflectivity measurements were subsequently carried out at the three surface pressures of 8, 15, and 35 mN/m to examine the structure and composition of lactoferrin coadsorbed at the interface. Whereas the DPPC monolayer effectively prevented lactoferrin insertion at the high surface pressure, a measurable amount of lactoferrin was found at the air/water interface at the two lower surface pressures. At 15 mN/m it was difficult to identify the distribution of lactoferrin with respect to the DPPC monolayer, due to its relatively low adsorbed amount and much broader distribution. At the lowest surface pressure of 8 mN/m, the lactoferrin coadsorption was found to increase with time over the first few hours. After 5 h the distribution of the lactoferrin layer became similar to, though quantitatively lower than, that adsorbed in the absence of the DPPC monolayer. It is characterized by a top dense sublayer of 15 Å with a bottom diffuse sublayer of 60 Å, indicating structural unfolding induced by surface adsorption under these conditions. PMID:17114223

Effects of Acids, Bases, and Heteroatoms on Proximal Radial Distribution Functions for Proteins

PubMed Central

Nguyen, Bao Linh; Pettitt, B. Montgomery

2015-01-01

The proximal distribution of water around proteins is a convenient method of quantifying solvation. We consider the effect of charged and sulfur-containing amino acid side-chain atoms on the proximal radial distribution function (pRDF) of water molecules around proteins using side-chain analogs. The pRDF represents the relative probability of finding any solvent molecule at a distance from the closest or surface perpendicular protein atom. We consider the near-neighbor distribution. Previously, pRDFs were shown to be universal descriptors of the water molecules around C, N, and O atom types across hundreds of globular proteins. Using averaged pRDFs, a solvent density around any globular protein can be reconstructed with controllable relative error. Solvent reconstruction using the additional information from charged amino acid side-chain atom types from both small models and protein averages reveals the effects of surface charge distribution on solvent density and improves the reconstruction errors relative to simulation. Solvent density reconstructions from the small-molecule models are as effective and less computationally demanding than reconstructions from full macromolecular models in reproducing preferred hydration sites and solvent density fluctuations. PMID:26388706

Distribution of living radiolarians and its response on the environments in spring from the section South China Sea

NASA Astrophysics Data System (ADS)

Zhang, L.; Hu, W.; Chen, M.; Zeng, L.; Xiang, R.; Zhou, W.

2013-12-01

The composition and spatial (horizontal and vertical) distribution of living radiolarians in spring was firstly studied in the section (18°N and 113°E) South China Sea. Vertical plankton tows were collected at depth-intervals from 0 to 300 m in spring using a closing-type net with 62 um mesh size. And we distinguished the living specimens by staining with Rose Bengal. It dominated by tropical-subtropical warm species in spring from the studied areas. The abundance of nassellarians was the almost same as that of spumellarians in the upper-surface waters (0-25m). In the below-surface waters (25-50m), nassellarian abundance was the almost twice that of spumellarians. And the abundances generally decreased with depth (more than 50m), but nasselarian abundance reduced more quickly. The results showed that the horizontal and vertical distribution patterns of living radiolarians were closely related to the mesoscale eddies. The horizontal distributions of radiolarian abundance were uneven and pachy, which may be related to the complicated mecoscale eddies during the sampling period. That is, there were comparatively high abundances in the upper-surface waters where had the cold eddies development. But in the cold eddies of Meigong River mouth, radiolarian abundance was low due to the large input of fresh water, suggesting that low salinity had more important influence than the nutrient on the radiolarian development and reproduction. Vertically, the highest abundances occurred at the mixed layer in the cold eddies, and gradually decreased with depth. However, in the warm eddies, the maximum abundances were in the thermocline layers, where had an abundant supply of nutrients for radiolarians. This study showed that Didymocyrtis tetrathalamus tetrathalamus mostly occurred at the mixed layer, which should be closely related to the cold eddies and rich nutrition and be limited by the fresh water. Based on the distribution of Didymocyrtis tetrathalamus tetrathalamus, we concluded that the influence of west Pacific waters was obviously weak on the northwestern Luzon Island during the sampling period. As a tropical surface warm species, Tetrapyle octacantha was also found to be indicator of tropical upwelling eutrophication water. Acanthodesmia vinculata was mainly living in the mixed layer, and had a good response to the cold eddies far away the continental shelf. Besides, we also concluded that Siphonosphaera polysiphonia should be tropical surface warm species, having a gregarious life, which had a closely related to the warm eddies. Interestingly, the typical deep-dwellers (Cornutella profunda and Cyrtopera laguncula) occurred in the different depth intervals, even in the upper-surface waters, which suggested that the temperature might not be the mostly one of factors to control their living-depth. This study was funded by the following research programs: the National Natural Science Foundation of China (Nos. 41276051, 91228207, 40906030).

Surface restructuring behavior of various types of poly(dimethylsiloxane) in water detected by SFG.

PubMed

Chen, Chunyan; Wang, Jie; Chen, Zhan

2004-11-09

Surface structures of several different poly(dimethylsiloxane) (PDMS) materials, tetraethoxysilane-cured hydroxy-terminated PDMS (TEOS-PDMS), platinum-cured vinyl-terminated PDMS (Pt-PDMS), platinum-cured vinyl-terminated poly(diphenylsiloxane)-co-poly(dimethylsiloxane) (PDPS-co-PDMS), and PDMS-co-polystyrene (PDMS-co-PS) copolymer in air and water have been investigated by sum frequency generation (SFG) vibrational spectroscopy. The SFG spectra collected from all PDMS surfaces in both air and water are dominated by methyl group stretches, indicating that all the surfaces are mainly covered by methyl groups. Other than surface-dominating methyl groups, some -Si-CH2-CH2- moieties on the Pt-PDMS surface have also been detected in air, which are present at cross-linking points. Information about the average orientation angle and angle distribution of the methyl groups on the PDMS surface has been evaluated. Surface restructuring of the methyl groups has been observed for all PDMS surfaces in water. Upon contacting water, the methyl groups on all PDMS surfaces tilt more toward the surface. The detailed restructuring behaviors of several PDMS surfaces in water and the effects of molecular weight on restructuring behaviors have been investigated. For comparison, in addition to air and water, surface structures of PDMS materials mentioned above in a nonpolar solvent, FC-75, have also been studied. By comparing the different response of phenyl groups to water on both PDPS-co-PDMS and PS-co-PDMS surfaces, we have demonstrated how the restructuring behaviors of surface phenyl groups are affected by the structural flexibility of the molecular chains where they are attached.

Spatial characteristics of net methylmercury production hot spots in peatlands

Treesearch

Carl P.J. Mitchell; Brian A. Branfireun; Randall K. Kolka

2008-01-01

Many wetlands are sources of methylmercury (MeHg) to surface waters, yet little information exists about the distribution of MeHg within wetlands. Total mercury (THg) and MeHg in peat pore waters were studied in four peatlands in spring, summer, and fall 2005. Marked spatial variability in the distribution of MeHg, and %MeHg as a proxy for net MeHg production, was...

The water-filled versus air-filled status of vessels cut open in air: the 'Scholander assumption' revisited

Treesearch

M.T. Tyree; H. Cochard; P. Cruziat

2003-01-01

When petioles of transpiring leaves are cut in the air, according to the 'Scholander assumption', the vessels cut open should fill with air as the water is drained away by continued transpiration, The distribution of air-filled vessels versus distance from the cut surface should match the distribution of lengths of 'open vessels', i.e. vessels cut...

Selected investigations and statistical summary of surface-water quality in the Rio Grande and the Rio Chama, north-central New Mexico, during water years 1985-2007

USGS Publications Warehouse

Falk, Sarah E.; Anderholm, Scott K.; Engdahl, Nicholas B.

2011-01-01

The Albuquerque Bernalillo County Water Utility Authority (ABCWUA) is supplementing the municipal water supply for Albuquerque, New Mexico, and the surrounding area with water diverted from the Rio Grande. The distribution of surface water for municipal supply has raised questions about the quality of water in the Rio Grande and the possibility of contaminants in the water. The U.S. Geological Survey (USGS), in cooperation with ABCWUA, has compiled existing water-quality data collected on the Rio Grande and its main tributary, the Rio Chama, by various Federal and State agencies to provide a comprehensive overview of water quality in the Rio Grande basin upstream from Albuquerque. This report describes selected water-quality investigations conducted by various Federal and State agencies and 2007 USGS surface-water-quality investigations and data-collection activities and presents a statistical summary of selected water-quality data collected on the Rio Grande and the Rio Chama in central and northern New Mexico

Combined point and distributed techniques for multidimensional estimation of spatial groundwater-stream water exchange in a heterogeneous sand bed-stream.

NASA Astrophysics Data System (ADS)

Gaona Garcia, J.; Lewandowski, J.; Bellin, A.

2017-12-01

Groundwater-stream water interactions in rivers determine water balances, but also chemical and biological processes in the streambed at different spatial and temporal scales. Due to the difficult identification and quantification of gaining, neutral and losing conditions, it is necessary to combine techniques with complementary capabilities and scale ranges. We applied this concept to a study site at the River Schlaube, East Brandenburg-Germany, a sand bed stream with intense sediment heterogeneity and complex environmental conditions. In our approach, point techniques such as temperature profiles of the streambed together with vertical hydraulic gradients provide data for the estimation of fluxes between groundwater and surface water with the numerical model 1DTempPro. On behalf of distributed techniques, fiber optic distributed temperature sensing identifies the spatial patterns of neutral, down- and up-welling areas by analysis of the changes in the thermal patterns at the streambed interface under certain flow. The study finally links point and surface temperatures to provide a method for upscaling of fluxes. Point techniques provide point flux estimates with essential depth detail to infer streambed structures while the results hardly represent the spatial distribution of fluxes caused by the heterogeneity of streambed properties. Fiber optics proved capable of providing spatial thermal patterns with enough resolution to observe distinct hyporheic thermal footprints at multiple scales. The relation of thermal footprint patterns and temporal behavior with flux results from point techniques enabled the use of methods for spatial flux estimates. The lack of detailed information of the physical driver's spatial distribution restricts the spatial flux estimation to the application of the T-proxy method, whose highly uncertain results mainly provide coarse spatial flux estimates. The study concludes that the upscaling of groundwater-stream water interactions using thermal measurements with combined point and distributed techniques requires the integration of physical drivers because of the heterogeneity of the flux patterns. Combined experimental and modeling approaches may help to obtain more reliable understanding of groundwater-surface water interactions at multiple scales.

Distribution of Different Biogeographical Tintinnids in Yellow Sea and Bohai Sea

NASA Astrophysics Data System (ADS)

Chen, Xue; Li, Haibo; Zhao, Yuan; Zhao, Li; Dong, Yi; Zhang, Wuchang; Xiao, Tian

2018-04-01

There were different biogeographical tintinnids in the oceans. Knowledge of their distribution pattern and mixing was important to the understanding of ecosystem functions. Yellow Sea (YS) and Bohai Sea (BS) were semi-enclosed seas influenced by warm water intrusion and YS cold bottom water. The occurrence of tintinnids in YS and BS during two cruises (summer and winter) were investigated to find out: i) whether warm-water tintinnids appeared in YS and BS; ii) whether boreal tintinnids appeared in high summer; iii) the core area of neritic tintinnids and iv) how these different biogeographical tintinnids mixed. Our results showed that tintinnid community was dominated by neritic tintinnid. We confirmed the occurrence of warm-water tintinnids in summer and winter. In summer, they intruded into BS and mainly distributed in the upper 20 m where Yellow Sea Surface Warm Water (YSSWW) developed. In winter, they were limited in the surface water of central deep region (bottom depth >50 m) of YS where were affected by Yellow Sea Warm Water (YSWW). Boreal tintinnids occurred in YS in high summer (August) and in winter, while they were not observed in BS. In summer, the highest abundance of boreal tintinnids occurred in Yellow Sea Bottom Cold Water, indicating the presence of an oversummering stock. In winter, they were concentrated in the north of YSWW. Vertically, neritic tintinnids abundance was high in the bottom layers. Horizontally, high neritic tintinnids abundance in bottom layers occurred along the 50 m isobath coinciding with the position of front systems. Front systems were the core distribution area of neritic tintinnids. High abundance areas of warm-water and boreal tintinnids were clearly separated vertically in summer, and horizontally in winter. High abundance of neritic tintinnids rarely overlapped with that of warm-water or boreal tintinnids.

Using a spatially-distributed hydrologic biogeochemistry model with nitrogen transport to study the spatial variation of carbon stocks and fluxes in a Critical Zone Observatory

NASA Astrophysics Data System (ADS)

Shi, Y.; Eissenstat, D. M.; He, Y.; Davis, K. J.

2017-12-01

Most current biogeochemical models are 1-D and represent one point in space. Therefore, they cannot resolve topographically driven land surface heterogeneity (e.g., lateral water flow, soil moisture, soil temperature, solar radiation) or the spatial pattern of nutrient availability. A spatially distributed forest biogeochemical model with nitrogen transport, Flux-PIHM-BGC, has been developed by coupling a 1-D mechanistic biogeochemical model Biome-BGC (BBGC) with a spatially distributed land surface hydrologic model, Flux-PIHM, and adding an advection dominated nitrogen transport module. Flux-PIHM is a coupled physically based model, which incorporates a land-surface scheme into the Penn State Integrated Hydrologic Model (PIHM). The land surface scheme is adapted from the Noah land surface model, and is augmented by adding a topographic solar radiation module. Flux-PIHM is able to represent the link between groundwater and the surface energy balance, as well as land surface heterogeneities caused by topography. In the coupled Flux-PIHM-BGC model, each Flux-PIHM model grid couples a 1-D BBGC model, while nitrogen is transported among model grids via surface and subsurface water flow. In each grid, Flux-PIHM provides BBGC with soil moisture, soil temperature, and solar radiation, while BBGC provides Flux-PIHM with spatially-distributed leaf area index. The coupled Flux-PIHM-BGC model has been implemented at the Susquehanna/Shale Hills Critical Zone Observatory. The model-predicted aboveground vegetation carbon and soil carbon distributions generally agree with the macro patterns observed within the watershed. The importance of abiotic variables (including soil moisture, soil temperature, solar radiation, and soil mineral nitrogen) in predicting aboveground carbon distribution is calculated using a random forest. The result suggests that the spatial pattern of aboveground carbon is controlled by the distribution of soil mineral nitrogen. A Flux-PIHM-BGC simulation without the nitrogen transport module is also executed. The model without nitrogen transport fails in predicting the spatial patterns of vegetation carbon, which indicates the importance of having a nitrogen transport module in spatially distributed ecohydrologic modeling.

Temporal changes in the vertical distribution of flow and chloride in deep wells

USGS Publications Warehouse

Izbicki, John A.; Christensen, Allen H.; Newhouse, Mark W.; Smith, Gregory A.; Hanson, Randall T.

2005-01-01

The combination of flowmeter and depth-dependent water-quality data was used to evaluate the quantity and source of high-chloride water yielded from different depths to eight production wells in the Pleasant Valley area of southern California. The wells were screened from 117 to 437 m below land surface, and in most cases, flow from the aquifer into the wells was not uniformly distributed throughout the well screen. Wells having as little as 6 m of screen in the overlying upper aquifer system yielded as much as 50% of their water from the upper system during drought periods, while the deeper parts of the well screens yielded 15% or less of the total yield of the wells. Mixing of water within wells during pumping degraded higher-quality water with poorer-quality water from deeper depths, and in some cases with poorer-quality water from the overlying upper aquifer system. Changes in the mixture of water within a well, resulting from changes in the distribution of flow into the well, changed the quality of water from the surface discharge of wells over time. The combination of flowmeter and depth-dependent water quality data yielded information about sources of high-chloride water to wells that was not available on the basis of samples collected from nearby observation wells. Changing well design to eliminate small quantities of poor-quality water from deeper parts of the well may improve the quality of water from some wells without greatly reducing well yield. Copyright ?? 2005 National Ground Water Association.

Water quality in Atlantic rainforest mountain rivers (South America): quality indices assessment, nutrients distribution, and consumption effect.

PubMed

Avigliano, Esteban; Schenone, Nahuel

2016-08-01

The South American Atlantic rainforest is a one-of-a-kind ecosystem considered as a biodiversity hotspot; however, in the last decades, it was intensively reduced to 7 % of its original surface. Water resources and water quality are one of the main goods and services this system provides to people. For monitoring and management recommendations, the present study is focused on (1) determining the nutrient content (nitrate, nitrite, ammonium, and phosphate) and physiochemical parameters (temperature, pH, electrical conductivity, turbidity, dissolved oxygen, and total dissolved solids) in surface water from 24 rainforest mountain rivers in Argentina, (2) analyzing the human health risk, (3) assessing the environmental distribution of the determined pollutants, and (4) analyzing water quality indices (WQIobj and WQImin). In addition, for total coliform bacteria, a dataset was used from literature. Turbidity, total dissolved solids, and nitrite (NO2 (-)) exceeded the guideline value recommended by national or international guidelines in several sampling stations. The spatial distribution pattern was analyzed by Principal Component Analysis and Factor Analysis (PCA/FA) showing well-defined groups of rivers. Both WQI showed good adjustment (R (2) = 0.89) and rated water quality as good or excellent in all sampling sites (WQI > 71). Therefore, this study suggests the use of the WQImin for monitoring water quality in the region and also the water treatment of coliform, total dissolved solids, and turbidity.

Water on the surface of the Moon as seen by the Moon Mineralogy Mapper: Distribution, abundance, and origins

PubMed Central

Li, Shuai; Milliken, Ralph E.

2017-01-01

A new thermal correction model and experimentally validated relationships between absorption strength and water content have been used to construct the first global quantitative maps of lunar surface water derived from the Moon Mineralogy Mapper near-infrared reflectance data. We find that OH abundance increases as a function of latitude, approaching values of ~500 to 750 parts per million (ppm). Water content also increases with the degree of space weathering, consistent with the preferential retention of water originating from solar wind implantation during agglutinate formation. Anomalously high water contents indicative of interior magmatic sources are observed in several locations, but there is no global correlation between surface composition and water content. Surface water abundance can vary by ~200 ppm over a lunar day, and the upper meter of regolith may contain a total of ~1.2 × 1014 g of water averaged over the globe. Formation and migration of water toward cold traps may thus be a continuous process on the Moon and other airless bodies. PMID:28924612

Soil Moisture: The Hydrologic Interface Between Surface and Ground Waters

NASA Technical Reports Server (NTRS)

Engman, Edwin T.

1997-01-01

A hypothesis is presented that many hydrologic processes display a unique signature that is detectable with microwave remote sensing. These signatures are in the form of the spatial and temporal distributions of surface soil moisture. The specific hydrologic processes that may be detected include groundwater recharge and discharge zones, storm runoff contributing areas, regions of potential and less than potential evapotranspiration (ET), and information about the hydrologic properties of soils. In basin and hillslope hydrology, soil moisture is the interface between surface and ground waters.

Waterworks Operator Training Manual.

ERIC Educational Resources Information Center

Missouri Univ., Columbia. Instructional Materials Lab.

Sixteen self-study waterworks operators training modules are provided. Module titles are the following: basic mathematics, basic chemistry, analysis procedures, microbiology, basic electricity, hydraulics, chlorination, plant operation, surface water, ground water, pumps, cross connections, distribution systems, safety, public relations, and…

A Review of Surface Water Quality Models

PubMed Central

Li, Shibei; Jia, Peng; Qi, Changjun; Ding, Feng

2013-01-01

Surface water quality models can be useful tools to simulate and predict the levels, distributions, and risks of chemical pollutants in a given water body. The modeling results from these models under different pollution scenarios are very important components of environmental impact assessment and can provide a basis and technique support for environmental management agencies to make right decisions. Whether the model results are right or not can impact the reasonability and scientificity of the authorized construct projects and the availability of pollution control measures. We reviewed the development of surface water quality models at three stages and analyzed the suitability, precisions, and methods among different models. Standardization of water quality models can help environmental management agencies guarantee the consistency in application of water quality models for regulatory purposes. We concluded the status of standardization of these models in developed countries and put forward available measures for the standardization of these surface water quality models, especially in developing countries. PMID:23853533

On the methane paradox: Transport from shallow water zones rather than in situ methanogenesis is the major source of CH4 in the open surface water of lakes

NASA Astrophysics Data System (ADS)

Encinas Fernández, Jorge; Peeters, Frank; Hofmann, Hilmar

2016-10-01

Estimates of global methane (CH4) emissions from lakes and the contributions of different pathways are currently under debate. In situ methanogenesis linked to algae growth was recently suggested to be the major source of CH4 fluxes from aquatic systems. However, based on our very large data set on CH4 distributions within lakes, we demonstrate here that methane-enriched water from shallow water zones is the most likely source of the basin-wide mean CH4 concentrations in the surface water of lakes. Consistently, the mean surface CH4 concentrations are significantly correlated with the ratio between the surface area of the shallow water zone and the entire lake, fA,s/t, but not with the total surface area. The categorization of CH4 fluxes according to fA,s/t may therefore improve global estimates of CH4 emissions from lakes. Furthermore, CH4 concentrations increase substantially with water temperature, indicating that seasonally resolved data are required to accurately estimate annual CH4 emissions.

Biofilm monitoring coupon system and method of use

NASA Technical Reports Server (NTRS)

Sauer, Richard L. (Inventor); Flanagan, David T. (Inventor)

1991-01-01

An apparatus and method is disclosed for biofilm monitoring of a water distribution system which includes the mounting of at least one fitting in a wall port of a manifold in the water distribution system with a passage through the fitting in communication. The insertion of a biofilm sampling member is through the fitting with planar sampling surfaces of different surface treatment provided on linearly arrayed sample coupons of the sampling member disposed in the flow stream in edge-on parallel relation to the direction of the flow stream of the manifold under fluid-tight sealed conditions. The sampling member is adapted to be aseptically removed from or inserted in the fitting and manifold under a positive pressure condition and the fitting passage sealed immediately thereafter by appropriate closure means so as to preclude contamination of the water distribution system through the fitting. The apparatus includes means for clamping the sampling member and for establishing electrical continuity between the sampling surfaces and the system for minimizing electropotential effects. The apparatus may also include a plurality of fittings and sampling members mounted on the manifold to permit extraction of the sampling members in a timed sequence throughout the monitoring period.

Pore-scale water dynamics during drying and the impacts of structure and surface wettability

NASA Astrophysics Data System (ADS)

Cruz, Brian C.; Furrer, Jessica M.; Guo, Yi-Syuan; Dougherty, Daniel; Hinestroza, Hector F.; Hernandez, Jhoan S.; Gage, Daniel J.; Cho, Yong Ku; Shor, Leslie M.

2017-07-01

Plants and microbes secrete mucilage into soil during dry conditions, which can alter soil structure and increase contact angle. Structured soils exhibit a broad pore size distribution with many small and many large pores, and strong capillary forces in narrow pores can retain moisture in soil aggregates. Meanwhile, contact angle determines the water repellency of soils, which can result in suppressed evaporation rates. Although they are often studied independently, both structure and contact angle influence water movement, distribution, and retention in soils. Here drying experiments were conducted using soil micromodels patterned to emulate different aggregation states of a sandy loam soil. Micromodels were treated to exhibit contact angles representative of those in bulk soil (8.4° ± 1.9°) and the rhizosphere (65° ± 9.2°). Drying was simulated using a lattice Boltzmann single-component, multiphase model. In our experiments, micromodels with higher contact angle surfaces took 4 times longer to completely dry versus micromodels with lower contact angle surfaces. Microstructure influenced drying rate as a function of saturation and controlled the spatial distribution of moisture within micromodels. Lattice Boltzmann simulations accurately predicted pore-scale moisture retention patterns within micromodels with different structures and contact angles.

Regional Mapping of Coupled Fluxes of Carbon and Water Using Multi-Sensor Fusion Techniques

NASA Astrophysics Data System (ADS)

Schull, M. A.; Anderson, M. C.; Semmens, K. A.; Yang, Y.; Gao, F.; Hain, C.; Houborg, R.

2014-12-01

In an ever-changing climate there is an increasing need to measure the fluxes of water, energy and carbon for decision makers to implement policies that will help mitigate the effects of climate change. In an effort to improve drought monitoring, water resource management and agriculture assessment capabilities, a multi-scale and multi-sensor framework for routine mapping of land-surface fluxes of water and energy at field to regional scales has been established. The framework uses the ALEXI (Atmosphere Land Exchange Inverse)/DisALEXI (Disaggregated ALEXI) suite of land-surface models forced by remotely sensed data from Landsat, MODIS (MODerate resolution Imaging Spectroradiometer), and GOES (Geostationary Operational Environmental Satellite). Land-surface temperature (LST) can be an effective substitute for in-situ surface moisture observations and a valuable metric for constraining land-surface fluxes at sub-field scales. The adopted multi-scale thermal-based land surface modeling framework facilitates regional to local downscaling of water and energy fluxes by using a combination of shortwave reflective and thermal infrared (TIR) imagery from GOES (4-10 km; hourly), MODIS (1 km; daily), and Landsat (30-100 m; bi-weekly). In this research the ALEXI/DisALEXI modeling suite is modified to incorporate carbon fluxes using a stomatal resistance module, which replaces the Priestley-Taylor latent heat approximation. In the module, canopy level nominal light-use-efficiency (βn) is the parameter that modulates the flux of water and carbon in and out of the canopy. Leaf chlorophyll (Chl) is a key parameter for quantifying variability in photosynthetic efficiency to facilitate the spatial distribution of coupled carbon and water retrievals. Spatial distribution of Chl are retrieved from Landsat (30 m) using a surface reflectance dataset as input to the REGularized canopy reFLECtance (REGFLEC) tool. The modified ALEXI/DisALEXI suite is applied to regions of rain fed and irrigated soybean and maize agricultural landscapes within the continental U.S. and flux estimates are compared with flux tower observations.

Surface-water-quality assessment of the Yakima River basin in Washington; spatial and temporal distribution of trace elements in water, sediment, and aquatic biota, 1987-91; with a section on geology

USGS Publications Warehouse

Fuhrer, Gregory J.; Cain, Daniel J.; McKenzie, Stuart W.; Rinella, Joseph F.; Crawford, J. Kent; Skach, Kenneth A.; Hornberger, Michelle I.; Gannett, Marshall W.

1999-01-01

The report describes the distribution of trace elements in sediment, water, and aquatic biota in the Yakima River basin, Washington. Trace elements were determined from streambed sediment, suspended sediment, filtered and unfiltered water samples, aquatic insects, clams, fish livers, and fish fillets between 1987 and 1991. The distribution of trace elements in these media was related to local geology and anthropogenic sources. Additionally, annual and instantaneous loads were estimated for trace elements associated with suspended sediment and trace elements in filtered water samples. Trace elements also were screened against U.S. Environmental Protection Agency guidelines established for the protection of human health and aquatic life.

Effect of glycosylation on hydration behavior at the ice-binding surface of the Ocean Pout type III antifreeze protein: a molecular dynamics simulation.

PubMed

Halder, Swagata; Mukhopadhyay, Chaitali

2017-12-01

Antifreeze proteins (AFPs), found in certain vertebrates, plants, fungi and bacteria have the ability to permit their survival in subzero environments by thermal hysteresis mechanism. However, the exact mechanism of ice growth inhibition is still not clearly understood. Here, four long explicit molecular dynamics (MD) simulations have been carried out at two different temperatures (277 and 298 K) with and without glycan to study the conformational rigidity of the Ocean pout type III antifreeze protein in aqueous medium and the structural arrangements of water molecules hydrating its ice-binding surface. It is found that irrespective of the temperature the ice-binding surface (IBS) of the protein is relatively more rigid than its non ice-binding surface (NonIBS) in its native and glycosylated form. Hydrophilic residues N14, T18 and Q44 are essential to antifreeze activity. Radial distribution, density distribution function and nearest neighbor orientation plots with respect to individual two surfaces confirm that density of water molecule near these binding surface in native and glycosylated form are relatively more than the nonbinding surface. The glycosylated form shows a strong peak than the native one. From rotational auto correlation function of water molecules around ice-binding sites, it is prominent that with increase in temperature, strong interaction between the water oxygen and the hydrogen bond acceptor group on the protein-binding surface decreases. This provides a possible molecular reason behind the ice-binding activity of ocean pout at the prism plane of ice.

Integration of Palmer Drought Severity Index and remote sensing data to simulate wetland water surface from 1910 to 2009 in Cottonwood Lake area, North Dakota

USGS Publications Warehouse

Huang, Shengli; Dahal, Devendra; Young, Claudia; Chander, Gyanesh; Liu, Shuguang

2011-01-01

Spatiotemporal variations of wetland water in the Prairie Pothole Region are controlled by many factors; two of them are temperature and precipitation that form the basis of the Palmer Drought Severity Index (PDSI). Taking the 196 km2 Cottonwood Lake area in North Dakota as our pilot study site, we integrated PDSI, Landsat images, and aerial photography records to simulate monthly water surface. First, we developed a new Wetland Water Area Index (WWAI) from PDSI to predict water surface area. Second, we developed a water allocation model to simulate the spatial distribution of water bodies at a resolution of 30 m. Third, we used an additional procedure to model the small wetlands (less than 0.8 ha) that could not be detected by Landsat. Our results showed that i) WWAI was highly correlated with water area with an R2 of 0.90, resulting in a simple regression prediction of monthly water area to capture the intra- and inter-annual water change from 1910 to 2009; ii) the spatial distribution of water bodies modeled from our approach agreed well with the water locations visually identified from the aerial photography records; and iii) the R2 between our modeled water bodies (including both large and small wetlands) and those from aerial photography records could be up to 0.83 with a mean average error of 0.64 km2 within the study area where the modeled wetland water areas ranged from about 2 to 14 km2. These results indicate that our approach holds great potential to simulate major changes in wetland water surface for ecosystem service; however, our products could capture neither the short-term water change caused by intensive rainstorm events nor the wetland change caused by human activities.

Probabilistic modeling of the flows and environmental risks of nano-silica.

PubMed

Wang, Yan; Kalinina, Anna; Sun, Tianyin; Nowack, Bernd

2016-03-01

Nano-silica, the engineered nanomaterial with one of the largest production volumes, has a wide range of applications in consumer products and industry. This study aimed to quantify the exposure of nano-silica to the environment and to assess its risk to surface waters. Concentrations were calculated for four environmental (air, soil, surface water, sediments) and two technical compartments (wastewater, solid waste) for the EU and Switzerland using probabilistic material flow modeling. The corresponding median concentration in surface water is predicted to be 0.12 μg/l in the EU (0.053-3.3 μg/l, 15/85% quantiles). The concentrations in sediments in the complete sedimentation scenario were found to be the largest among all environmental compartments, with a median annual increase of 0.43 mg/kg · y in the EU (0.19-12 mg/kg · y, 15/85% quantiles). Moreover, probabilistic species sensitivity distributions (PSSD) were computed and the risk of nano-silica in surface waters was quantified by comparing the predicted environmental concentration (PEC) with the predicted no-effect concentration (PNEC) distribution, which was derived from the cumulative PSSD. This assessment suggests that nano-silica currently poses no risk to aquatic organisms in surface waters. Further investigations are needed to assess the risk of nano-silica in other environmental compartments, which is currently not possible due to a lack of ecotoxicological data. Copyright © 2015 Elsevier B.V. All rights reserved.

Improved simulation of river water and groundwater exchange in an alluvial plain using the SWAT model

USDA-ARS?s Scientific Manuscript database

Hydrological interaction between surface and subsurface water systems has a significant impact on water quality, ecosystems and biogeochemistry cycling of both systems. Distributed models have been developed to simulate this function, but they require detailed spatial inputs and extensive computati...

The Accumulation Of Radium And Other Radionuclides In Drinking Water Distribution Systems

EPA Science Inventory

The tendency for iron solid surfaces to adsorb trace contaminants such as arsenic is well known and has become the basis for several drinking water treatment approaches. It is reasonable to assume that iron-based solids, such as corrosion deposits present in drinking water distr...

Integrated Data Fusion and Mining Techniques for Monitoring Total Organic Carbon Concentrations in a Lake

EPA Science Inventory

Total organic carbon (TOC) in surface waters, markedly of seasonal variations, is a known precursor of disinfection byproducts such as Total Trihalomethanes (TTHM) in drinking water treatment. Real-time knowledge of TOC distribution in source water can help treatment operation to...

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.

Patterns and Drivers of Vertical Distribution of the Ciliate Community from the Surface to the Abyssopelagic Zone in the Western Pacific Ocean.

PubMed

Zhao, Feng; Filker, Sabine; Xu, Kuidong; Huang, Pingping; Zheng, Shan

2017-01-01

The deep sea is one of the largest but least understood ecosystems on earth. Knowledge about the diversity and distribution patterns as well as drivers of microbial eukaryote (including ciliates) along the water column, particularly below the photic zone, is scarce. In this study, we investigated the diversity of pelagic ciliates, the main group of marine microeukaryotes, their vertical distribution from the surface to the abyssopelagic zone, as well as their horizontal distribution over a distance of 1,300 km in the Western Pacific Ocean, using high-throughput DNA and cDNA (complementary DNA) sequencing. No distance-decay relationship could be detected along the horizontal scale; instead, a distinct vertical distribution within the ciliate communities was revealed. The alpha diversity of the ciliate communities in the deep chlorophyll maximum (DCM) and the 200 m layer turned out to be significantly higher compared with the other water layers. The ciliate communities in the 200 m water layer appeared to be more similar to those in deeper layers from 1,000 m to about 5,000 m than to the surface and DCM ciliate communities. Dominant species in the bathypelagic and abyssopelagic zone, particularly some parasites, were also detected in the 200 m layer, but were almost absent in the surface layer. The 200 m layer, therefore, seems to be an important "species bank" for deep ocean layers. Statistical analyses further revealed significant effects of temperature and chlorophyll a on the partitioning of ciliate diversity, indicating that environmental factors are a stronger force in shaping marine pelagic ciliate communities than the geographic distance.

Distribution of Archaeal Communities along the Coast of the Gulf of Finland and Their Response to Oil Contamination

PubMed Central

Yan, Lijuan; Yu, Dan; Hui, Nan; Naanuri, Eve; Viggor, Signe; Gafarov, Arslan; Sokolov, Sergei L.; Heinaru, Ain; Romantschuk, Martin

2018-01-01

The Baltic Sea is vulnerable to environmental changes. With the increasing shipping activities, the risk of oil spills remains high. Archaea are widely distributed in many environments. However, the distribution and the response of archaeal communities to oil contamination have rarely been investigated in brackish habitats. Hence, we conducted a survey to investigate the distribution, diversity, composition, and species interactions of indigenous archaeal communities at oil-contaminated sites along the coast of the Gulf of Finland (GoF) using high-throughput sequencing. Surface water and littoral sediment samples were collected at presumably oil-contaminated (oil distribution facilities) and clean sites along the coastline of the GoF in the winter 2015 and the summer 2016. Another three samples of open sea surface water were taken as offshore references. Of Archaea, Euryarchaeota dominated in the surface water and the littoral sediment of the coast of the GoF, followed by Crenarchaeota (including Thaumarchaeota, Thermoprotei, and Korarchaeota based on the Greengenes database used). The unclassified sequences accounted for 5.62% of the total archaeal sequences. Our study revealed a strong dependence of the archaeal community composition on environmental variables (e.g., salinity, pH, oil concentration, TOM, electrical conductivity, and total DNA concentration) in both littoral sediment and coastal water in the GoF. The composition of archaeal communities was season and ecosystem dependent. Archaea was highly diverse in the three ecosystems (littoral sediment, coastal water, and open sea water). Littoral sediment harbored the highest diversity of archaea. Oil was often detected in the littoral sediment but rarely detected in water at those presumably contaminated sites. Although the composition of archaeal community in the littoral sediment was sensitive to low-input oil contamination, the unchanged putative functional profiles and increased interconnectivity of the archaeal core species network plausibly revealed resilience and the potential for oil degradation. Halobacteriaceae and putative cytochrome P450 pathways were significantly enriched in the oil-contaminated littoral sediment. The archaeal taxa formed highly interconnected and interactive networks, in which Halobacteriaceae, Thermococcus, and methanogens were the main components, implying a potential relevant trophic connection between hydrocarbon degradation, methanogenesis, sulfate reduction, and/or fermentative growth. PMID:29410652

Effects of spatially distributed sectoral water management on the redistribution of water resources in an integrated water model

NASA Astrophysics Data System (ADS)

Voisin, Nathalie; Hejazi, Mohamad I.; Leung, L. Ruby; Liu, Lu; Huang, Maoyi; Li, Hong-Yi; Tesfa, Teklu

2017-05-01

Realistic representations of sectoral water withdrawals and consumptive demands and their allocation to surface and groundwater sources are important for improving modeling of the integrated water cycle. To inform future model development, we enhance the representation of water management in a regional Earth system (ES) model with a spatially distributed allocation of sectoral water demands simulated by a regional integrated assessment (IA) model to surface and groundwater systems. The integrated modeling framework (IA-ES) is evaluated by analyzing the simulated regulated flow and sectoral supply deficit in major hydrologic regions of the conterminous U.S, which differ from ES studies looking at water storage variations. Decreases in historical supply deficit are used as metrics to evaluate IA-ES model improvement in representating the complex sectoral human activities for assessing future adaptation and mitigation strategies. We also assess the spatial changes in both regulated flow and unmet demands, for irrigation and nonirrigation sectors, resulting from the individual and combined additions of groundwater and return flow modules. Results show that groundwater use has a pronounced regional and sectoral effect by reducing water supply deficit. The effects of sectoral return flow exhibit a clear east-west contrast in the hydrologic patterns, so the return flow component combined with the IA sectoral demands is a major driver for spatial redistribution of water resources and water deficits in the US. Our analysis highlights the need for spatially distributed sectoral representation of water management to capture the regional differences in interbasin redistribution of water resources and deficits.

Characterizing heterogeneous dynamics at hydrated electrode surfaces.

PubMed

Willard, Adam P; Limmer, David T; Madden, Paul A; Chandler, David

2013-05-14

In models of Pt 111 and Pt 100 surfaces in water, motions of molecules in the first hydration layer are spatially and temporally correlated. To interpret these collective motions, we apply quantitative measures of dynamic heterogeneity that are standard tools for considering glassy systems. Specifically, we carry out an analysis in terms of mobility fields and distributions of persistence times and exchange times. In so doing, we show that dynamics in these systems is facilitated by transient disorder in frustrated two-dimensional hydrogen bonding networks. The frustration is the result of unfavorable geometry imposed by strong metal-water bonding. The geometry depends upon the structure of the underlying metal surface. Dynamic heterogeneity of water on the Pt 111 surface is therefore qualitatively different than that for water on the Pt 100 surface. In both cases, statistics of this ad-layer dynamic heterogeneity responds asymmetrically to applied voltage.

Characterizing heterogeneous dynamics at hydrated electrode surfaces

NASA Astrophysics Data System (ADS)

Willard, Adam P.; Limmer, David T.; Madden, Paul A.; Chandler, David

2013-05-01

In models of Pt 111 and Pt 100 surfaces in water, motions of molecules in the first hydration layer are spatially and temporally correlated. To interpret these collective motions, we apply quantitative measures of dynamic heterogeneity that are standard tools for considering glassy systems. Specifically, we carry out an analysis in terms of mobility fields and distributions of persistence times and exchange times. In so doing, we show that dynamics in these systems is facilitated by transient disorder in frustrated two-dimensional hydrogen bonding networks. The frustration is the result of unfavorable geometry imposed by strong metal-water bonding. The geometry depends upon the structure of the underlying metal surface. Dynamic heterogeneity of water on the Pt 111 surface is therefore qualitatively different than that for water on the Pt 100 surface. In both cases, statistics of this ad-layer dynamic heterogeneity responds asymmetrically to applied voltage.

Effects of glacial meltwater inflows and moat freezing on mixing in an ice-covered antarctic lake as interpreted from stable isotope and tritium distributions

USGS Publications Warehouse

Miller, L.G.; Aiken, G.R.

1996-01-01

Perennially ice-covered lakes in the McMurdo Dry Valleys have risen several meters over the past two decades due to climatic warming and increased glacial meltwater inflow. To elucidate the hydrologic responses to changing climate and the effects on lake mixing processes we measured the stable isotope (??18O and ??D) and tritium concentrations of water and ice samples collected in the Lake Fryxell watershed from 1987 through 1990. Stable isotope enrichment resulted from evaporation in stream and moat samples and from sublimation in surface lake-ice samples. Tritium enrichment resulted from exchange with the postnuclear atmosphere in stream and moat samples. Rapid injection of tritiated water into the upper water column of the make and incorporation of this water into the ice cover resulted in uniformly elevated tritium contents (> 3.0 TU) in these reservoirs. Tritium was also present in deep water, suggesting that a component of bottom water was recently at the surface. During summer, melted lake ice and stream water forms the moat. Water excluded from ice formation during fall moat freezing (enriched in solutes and tritium, and depleted in 18O and 2H relative to water below 15-m depth) may sink as density currents to the bottom of the lake. Seasonal lake circulation, in response to climate-driven surface inflow, is therefore responsible for the distribution of both water isotopes and dissolved solutes in Lake Fryxell.

Impact of war, precipitation, and water management on quantity of water resources in the Tigris/Euphrates area

NASA Astrophysics Data System (ADS)

Hasan, Mejs; Moody, Aaron

2017-04-01

The fast-paced conflicts in the Middle East have the potential to disrupt management and supply of water resources in the region. In this research, we use the normalized difference water index (NDWI) in order to monitor changes in the extent of various water bodies over the time span of the Landsat 4, 5, 7, and 8 satellites (1984-present). We focused on Mosul and Haditha dam lakes, located on the Tigris and Euphrates Rivers, respectively, each of which has experienced changes in sovereignty over the last few years of conflict. We established two areas, one land and one water, on each image, plotted the distributions of all NDWI values for each area, and used the number of standard deviations between the two distributions in order to set a dynamic NDWI threshold for each image. Using this threshold, we determined water pixels and lake surface area, and computed daily percent change in lake extent between images. Furthermore, we took account of explanatory water resource variables, such as upstream dam management (via surface extent of upstream Turkish dams), precipitation (via globally-compiled databases), evaporation (based on surface area decreases during non-rainy months), and irrigation withdrawals (based on MODIS Enhanced Vegetation Indices). We used these explanatory variables in order to build a general model of expected dam lake surface extent, and we looked to see if anomalies from expected surface area corresponded with periods of conflict. We found that the recent years of conflict do not appear to have had as much impact on the Mosul and Haditha dam lakes as did the conflicts related to the earlier Gulf Wars. The dam lakes have recorded an overall decrease in surface area simultaneous to increases of upstream dams. A strong seasonal signal driven by springtime Turkish snowmelt and summer evaporation is also evident.

Residues of organochlorine pesticides in surface water of a megacity in central China: seasonal-spatial distribution and fate in Wuhan.

PubMed

Cui, Lili; Wei, Liangfu; Wang, Jun

2017-01-01

Surface water quality closely correlating with human health suffered increasing organochlorine pesticide (OCP) pollution due to the intensive anthropogenic activities in megacities. In the present study, 112 water samples collected from 14 lakes and 11 drinking water source sites in Wuhan were detected for the residues of OCPs in November 2013 and July 2014, respectively. The ΣOCPs ranged from 5.61 to 13.62 ng L -1 in summer with the maximum value in Yezhi Lake and 3.18 to 7.73 ng L -1 in winter with the highest concentration in Yandong Lake. Except dichlorodiphenyltrichloroethanes (DDTs), OCP concentrations in summer were significantly higher than those in winter mostly due to the non-point source pollution including land runoff in summer. Source apportionment of hexachlorocyclohexanes (HCHs) and DDTs revealed the historical use of technical HCH and lindane and the new input of DDT, respectively. The spatial distribution of OCPs was not uniform in the surface water of Wuhan because of the significant influence of land development and fishery. The risk assessments showed the heptachlor, and heptachlor epoxide in most sampling sites exceeded the threshold set by the European Union, indicating the possible adverse effects for aquatic lives. Negligible non-carcinogenic risks for drinking and bathing as well as carcinogenic risks for bathing were found in the surface water. However, the total carcinogenic risks of all OCPs (∑Rs) caused by drinking in summer were higher than the safe level of 10 -7 in all sampling sites. It was implied that the surface water in Wuhan was not safe for directly drinking without effective purification.

Microwave Investigation of the Mars Atmosphere and Surface

NASA Technical Reports Server (NTRS)

Gulkis, S.; Forget, F.; Janssen, M.; Riley, A. L.; Hartogh, P.; Clancy, T.; Allen, M.; Frerking, M.

2000-01-01

The Microwave Investigation of the Mars Atmosphere and Surface Experiment (MIMAS) is designed to address two major scientific goals: 1) To understand the three dimensional general circulation of the Martian atmosphere, and 2) To understand the hydrologic cycle of water on Mars, including the time-variable sources, sinks, and atmospheric transport of water vapor. The proposed instrument is a submillimeter wave, heterodyne receiver, with both continuum and very high spectral resolution capability. A small reflector antenna will be used to feed the receiver. Instrument heritage comes from the MIRO receiver, currently under design for the ESA Rosetta Mission, and from SWAS, a NASA astrophysics mission. The instrument will be able to measure atmospheric spectral lines from both water and carbon monoxide and use these lines as tracers of atmospheric winds. Measurement objectives of MIMAS are to measure surface temperature, atmospheric temperature from the surface up to an altitude of 60 km or more, the distribution of CO and H2O in the atmosphere, and certain wind fields (zonal and meridional). The global distribution of CO, as well as temperature distributions, will be used as input data for GCMs (general circulation models). Water vapor profiles will be used to understand the sources and sinks of water on Mars and to understand how it is transported globally by the general circulation. Zonal and meridional wind fields will provide further tests of the GCMs. An important aspect of this experiment is that the temperature and humidity measurements are insensitive to dust and ice condensates thereby making the measurement capability independent of the presence of dust clouds and ice particles. Temperature measurements derived from the data can be used in conjunction with infrared measurements to determine dust profiles.

Assessment of surface water chloride and conductivity trends in areas of unconventional oil and gas development-Why existing national data sets cannot tell us what we would like to know

USGS Publications Warehouse

Bowen, Zachary H.; Oelsner, Gretchen P.; Cade, Brian S.; Gallegos, Tanya J.; Farag, Aïda M.; Mott, David N.; Potter, Christopher J.; Cinotto, Peter J.; Clark, Melanie L.; Kappel, William M.; Kresse, Timothy M.; Melcher, Cynthia P.; Paschke, Suzanne; Susong, David D.; Varela, Brian A.

2015-01-01

Heightened concern regarding the potential effects of unconventional oil and gas development on regional water quality has emerged, but the few studies on this topic are limited in geographic scope. Here we evaluate the potential utility of national and publicly available water-quality data sets for addressing questions regarding unconventional oil and gas development. We used existing U.S. Geological Survey and U.S. Environmental Protection Agency data sets to increase understanding of the spatial distribution of unconventional oil and gas development in the U.S. and broadly assess surface water quality trends in these areas. Based on sample size limitations, we were able to estimate trends in specific conductance (SC) and chloride (Cl-) from 1970 to 2010 in 16% (n=155) of the watersheds with unconventional oil and gas resources. We assessed these trends relative to spatiotemporal distributions of hydraulically fractured wells. Results from this limited analysis suggest no consistent and widespread trends in surface water quality for SC and Cl- in areas with increasing unconventional oil and gas development and highlight limitations of existing national databases for addressing questions regarding unconventional oil and gas development and water quality.

Combining Methods to Describe Important Marine Habitats for Top Predators: Application to Identify Biological Hotspots in Tropical Waters.

PubMed

Thiers, Laurie; Louzao, Maite; Ridoux, Vincent; Le Corre, Matthieu; Jaquemet, Sébastien; Weimerskirch, Henri

2014-01-01

In tropical waters resources are usually scarce and patchy, and predatory species generally show specific adaptations for foraging. Tropical seabirds often forage in association with sub-surface predators that create feeding opportunities by bringing prey close to the surface, and the birds often aggregate in large multispecific flocks. Here we hypothesize that frigatebirds, a tropical seabird adapted to foraging with low energetic costs, could be a good predictor of the distribution of their associated predatory species, including other seabirds (e.g. boobies, terns) and subsurface predators (e.g., dolphins, tunas). To test this hypothesis, we compared distribution patterns of marine predators in the Mozambique Channel based on a long-term dataset of both vessel- and aerial surveys, as well as tracking data of frigatebirds. By developing species distribution models (SDMs), we identified key marine areas for tropical predators in relation to contemporaneous oceanographic features to investigate multi-species spatial overlap areas and identify predator hotspots in the Mozambique Channel. SDMs reasonably matched observed patterns and both static (e.g. bathymetry) and dynamic (e.g. Chlorophyll a concentration and sea surface temperature) factors were important explaining predator distribution patterns. We found that the distribution of frigatebirds included the distributions of the associated species. The central part of the channel appeared to be the best habitat for the four groups of species considered in this study (frigatebirds, brown terns, boobies and sub-surface predators).

Coherent Structures and Evolution of Vorticity in Short-Crested Breaking Surface Waves

NASA Astrophysics Data System (ADS)

Kirby, James; Derakhti, Morteza

2017-11-01

We employ a multi-phase LES/VOF code to study turbulence and coherent structures generated during breaking of short-crested surface water waves. We examine the evolution of coherent vortex structures evolving at the scale of the width of the breaking event, and their long-time interaction with smaller vortex loops formed by the local instability of the breaking crest. Long-time results are often characterized by the detachment of the larger scale vortex loop from the surface and formation of a closed vortex ring. The evolution of circulation for the vortical flow field is examined. The initial concentration of forcing close to the free surface leads to spatial distributions of both span-wise and vertical vorticity distributions which are concentrated close to the surface. This result, which persists into shallow water, is at odds with the basic simplicity of the Peregrine mechanism, suggesting that even shallow flows such as the surf zone should be regarded as being forced (in dissipative situations) by a wave-induced surface stress rather than a uniform-over-depth body force. The localized forcing leads to the development of a complex pattern of stream-wise vorticity, comparable in strength to the vertical and span-wise components, and also persist into shallow water. NSF OCE-1435147.

Distributions of dissolved monosaccharides and polysaccharides in the surface microlayer and surface water of the Jiaozhou Bay and its adjacent area

NASA Astrophysics Data System (ADS)

Zhang, Yan-Ping; Yang, Gui-Peng; Lu, Xiao-Lan; Ding, Hai-Bing; Zhang, Hong-Hai

2013-07-01

Sea surface microlayer (SML) samples and corresponding bulk surface water (SW) samples were collected in the Jiaozhou Bay and its adjacent area in July and November 2008. The average concentrations of dissolved monosaccharides (MCHO) and polysaccharides (PCHO) revealed similar temporal variability, with higher concentrations during the green-tide period (in July) than during the non-green-tide period (in November). Average enrichment factors (EF) of MCHO and PCHO, defined as the ratio of the concentration in the SML to that in the SW, were 1.3 and 1.4 in July, respectively, while those values in November were 1.9 and 1.6. Our data also showed that the concentrations of MCHO and PCHO in the SML were strongly correlated with those in the SW, indicating that most of the organic materials in the SML came from the SW. The total dissolved carbohydrate concentrations (TDCHO) in the bulk surface water were closely correlated with salinity during the cruises (July: r=-0.580, n=18, P=0.01; November: r=-0.679, n=26, P<0.001), suggesting that riverine input had an important effect on the distribution of TDCHO in surface seawater of the study area.

Air-Water Exchange of Legacy and Emerging Organic Pollutants across the Great Lakes

NASA Astrophysics Data System (ADS)

Lohmann, R.; Ruge, Z.; Khairy, M.; Muir, D.; Helm, P.

2014-12-01

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) are transported to great water bodies via long-range atmospheric transport and released from the surface water as air concentrations continue to diminish. As the largest fresh water bodies in North America, the Great Lakes have both the potential to accumulate and serve as a secondary source of persistent bioaccumulative toxins. OCP and PCB concentrations were sampled at 30+ sites across Lake Superior, Ontario and Erie in the summer of 2011. Polyethylene passive samplers (PEs) were simultaneously deployed in surface water and near surface atmosphere to determine air-water gaseous exchange of OCPs and PCBs. In Lake Superior, surface water and atmospheric concentrations were dominated by α-HCH (average 250 pg/L and 4.2 pg/m3, respectively), followed by HCB (average 17 pg/L and 89 pg/m3, respectively). Air-water exchange varied greatly between sites and individual OCPs, however α-endosulfan was consistently deposited into the surface water (average 19 pg/m2/day). PCBs in the air and water were characterized by penta- and hexachlorobiphenyls with distribution along the coast correlated with proximity to developed areas. Air-water exchange gradients generally yielded net volatilization of PCBs out of Lake Superior. Gaseous concentrations of hexachlorobenzene, dieldrin and chlordanes were significantly higher (p < 0.05) at Lake Erie than Lake Ontario. A multiple linear regression that incorporated meteorological, landuse and population data was used to explain variability in the atmospheric concentrations. Results indicated that landuse (urban and/or cropland) greatly explained the variability in the data. Freely dissolved concentrations of OCPs (

Formation of biofilms in drinking water distribution networks, a case study in two cities in Finland and Latvia.

PubMed

Lehtola, Markku J; Juhna, Tālis; Miettinen, Ilkka T; Vartiainen, Terttu; Martikainen, Pertti J

2004-12-01

The formation of biofilms in drinking water distribution networks is a significant technical, aesthetic and hygienic problem. In this study, the effects of assimilable organic carbon, microbially available phosphorus (MAP), residual chlorine, temperature and corrosion products on the formation of biofilms were studied in two full-scale water supply systems in Finland and Latvia. Biofilm collectors consisting of polyvinyl chloride pipes were installed in several waterworks and distribution networks, which were supplied with chemically precipitated surface waters and groundwater from different sources. During a 1-year study, the biofilm density was measured by heterotrophic plate counts on R2A-agar, acridine orange direct counting and ATP-analyses. A moderate level of residual chlorine decreased biofilm density, whereas an increase of MAP in water and accumulated cast iron corrosion products significantly increased biofilm density. This work confirms, in a full-scale distribution system in Finland and Latvia, our earlier in vitro finding that biofilm formation is affected by the availability of phosphorus in drinking water.

An analytical two-flow model to simulate the distribution of irradiance in coastal waters with a wind-roughed surface and bottom reflectance

NASA Astrophysics Data System (ADS)

Ma, Wei-Ming

1997-06-01

An analytical two-flow model is derived from the radiative transfer equation to simulate the distribution of irradiance in coastal waters with a wind-roughed surface and bottom reflectance. The model utilizes unique boundary conditions, including the surface slope of the downwelling and upwelling irradiance as well as the influence of wind and bottom reflectance on simulated surface reflectance. The developed model provides a simple mathematical concept for understanding the irradiant light flux and associated processes in coastal or fresh water as well as turbid estuarine waters. The model is applied to data from the Banana River and coastal Atlantic Ocean water off the east coast of central Florida, USA. The two-flow irradiance model is capable of simulating realistic above-surface reflectance signatures under wind-roughened air-water surface given realistic input parameters including a specular flux conversion coefficient, absorption coefficient, backscattering coefficient, atmospheric visibility, bottom reflectance, and water depth. The root-mean-squared error of the calculated above-surface reflectances is approximately 3% in the Banana River and is less than 15% in coastal Atlantic Ocean off the east of Florida. Result of the subsurface reflectance sensitivity analysis indicates that the specular conversion coefficient is the most sensitive parameter in the model, followed by the beam attenuation coefficient, absorption coefficient, water depth, backscattering coefficient, specular irradiance, diffuse irradiance, bottom reflectance, and wind speed. On the other hand, result of the above-surface reflectance sensitivity analysis indicates that the wind speed is the most important parameter, followed by bottom reflectance, attenuation coefficient, water depth, conversion coefficient, specular irradiance, downwelling irradiance, absorption coefficient, and backscattering coefficient. Model results depend on the accuracy of these parameters to a large degree and more important the water depth and value of the bottom reflectance. The results of this work indicates little change of subsurface or in-water reflectances, due to variations of wind speed and observation angle. Simulations of the wind effect on the total downwelling irradiance from the two- flow model indicates that the total downwelling irradiance just below a wind-roughened water surface increases to about 1% of the total downwelling irradiance on a calm water surface when the sun is near zenith and increases to about 3% when the sun is near the horizon. This analytically based model, solved or developed utilizing the unique boundary conditions, can be applied to remote sensing of oceanic upper mixed layer dynamics, plant canopies, primary production, and shallow water environments with different bottom type reflectances. Future applications may include determining effects of sediment resuspension of bottom sediments in the bottom boundary layer on remotely sensed data.

Water surface temperature estimation from Landsat 7 ETM+ thermal infrared data using the generalized single-channel method: Case study of Embalse del Río Tercero (Córdoba, Argentina)

NASA Astrophysics Data System (ADS)

Lamaro, Anabel Alejandra; Mariñelarena, Alejandro; Torrusio, Sandra Edith; Sala, Silvia Estela

2013-02-01

Monitoring of warm distribution in water is fundamental to understand the performance and functioning of reservoirs and lakes. Surface water temperature is a key parameter in the physics of aquatic systems processes since it is closely related to the energy fluxes through the water-atmosphere interface. Remote sensing applied to water quality studies in inland waterbodies is a powerful tool that can provide additional information difficult to achieve by other means. The combination of good real-time coverage, spatial resolution and free availability of data makes Landsat system a proper alternative. Many papers have developed algorithms to retrieve surface temperature (principally, land surface temperature) from at-sensor and surface emissivity data. The aim of this study is to apply the single-channel generalized method (SCGM) developed by Jiménez-Muñoz and Sobrino (2003) for the estimation of water surface temperature from Landsat 7 ETM+ thermal bands. We consider a constant water emissivity value (0.9885) and we compare the results with radiative transfer classic method (RTM). We choose Embalse del Río Tercero (Córdoba, Argentina) as case study because it is a reservoir affected by the outlet of the cooling system of a nuclear power plant, whose thermal plume could influence the biota's distribution and biodiversity. These characteristics and the existence of long term studies make it an adequate place to test the methodology. Values of estimated and observed water surface temperatures obtained by the two compared methods were correlated applying a simple regression model. Correlation coefficients were significant (R2: 0.9498 for SCGM method and R2: 0.9584 for RTM method) while their standard errors were acceptable in both cases (SCGM method: RMS = 1.2250 and RTM method: RMS = 1.0426). Nevertheless, SCGM could estimate rather small differences in temperature between sites consistently with the results obtained in field measurements. Besides, it has the advantage that it only uses values of atmospheric water vapor and it can be applied to different thermal sensors using the same equation and coefficients.

Laboratory evaluation of airborne particulate control treatments for simulated aircraft crash recovery operations involving carbon fiber composite materials.

PubMed

Ferreri, Matthew; Slagley, Jeremy; Felker, Daniel

2015-01-01

This study compared four treatment protocols to reduce airborne composite fiber particulates during simulated aircraft crash recovery operations. Four different treatments were applied to determine effectiveness in reducing airborne composite fiber particulates as compared to a "no treatment" protocol. Both "gold standard" gravimetric methods and real-time instruments were used to describe mass per volume concentration, particle size distribution, and surface area. The treatment protocols were applying water, wetted water, wax, or aqueous film-forming foam (AFFF) to both burnt and intact tickets of aircraft composite skin panels. The tickets were then cut using a small high-speed rotary tool to simulate crash recovery operations. Aerosol test chamber. None. Airborne particulate control treatments. Measures included concentration units of milligrams per cubic meter of air, particle size distribution as described by both count median diameter and mass median diameter and geometric standard deviation of particles in micrometers, and surface area concentration in units of square micrometers per cubic centimeter. Finally, a Monte Carlo simulation was run on the particle size distribution results. Comparison was made via one-way analysis of variance. A significant difference (p < 0.0001) in idealized particle size distribution was found between the water and wetted water treatments as compared to the other treatments for burnt tickets. Emergency crash recovery operations should include a treatment of the debris with water or wetted water. The resulting increase in particle size will make respiratory protection more effective in protecting the response crews.

Laboratory evaluation of airborne particulate control treatments for simulated aircraft crash recovery operations involving carbon fiber composite materials.

PubMed

Ferreri, Matthew; Slagley, Jeremy; Felker, Daniel

2015-01-01

This study compared four treatment protocols to reduce airborne composite fiber particulates during simulated aircraft crash recovery operations. Four different treatments were applied to determine effectiveness in reducing airborne composite fiber particulates as compared to a "no treatment" protocol. Both "gold standard" gravimetric methods and real-time instruments were used to describe mass per volume concentration, particle size distribution, and surface area. The treatment protocols were applying water, wetted water, wax, or aqueous film-forming foam (AFFF) to both burnt and intact tickets of aircraft composite skin panels. The tickets were then cut using a small high-speed rotary tool to simulate crash recovery operations. Aerosol test chamber. None. Airborne particulate control treatments. Measures included concentration units of milligrams per cubic meter of air, particle size distribution as described by both count median diameter and mass median diameter and geometric standard deviation of particles in micrometers, and surface area concentration in units of square micrometers per cubic centimeter. Finally, a Monte Carlo simulation was run on the particle size distribution results. Comparison was made via one-way analysis of variance. A significant difference (p<0.0001) in idealized particle size distribution was found between the water and wetted water treatments as compared to the other treatments for burnt tickets. Emergency crash recovery operations should include a treatment of the debris with water or wetted water. The resulting increase in particle size will make respiratory protection more effective in protecting the response crews.

Coupling Stable Water Isotopes in Vapor and Precipitation to Raindrop Size Distributions at a Mid-latitude Tall-tower Site to Evaluate the Role of Rain Evaporation in Boundary Layer Moisture Recycling

NASA Astrophysics Data System (ADS)

Kaushik, A.; Noone, D.

2016-12-01

The continental boundary layer moisture balance plays an important role in regulating water and energy exchange between the surface and the atmosphere, yet the mechanisms associated with moistening and drying are both poorly observed and modeled. Stable water isotope ratio measurements can provide insights into air mass origins, convection dynamics and mechanisms dominating atmosphere-land surface water fluxes. Profiles can be exploited to improve estimates of boundary layer moistening associated with evaporation of falling precipitation and contributions from surface evapotranspiration. We present two years of in situ tower-based measurements of isotope ratios of water vapor and precipitation (δD and δ18O) and raindrop size distributions from the Boulder Atmospheric Observatory (BAO) tall-tower site in Erie, Colorado. Isotope vapor measurements were made at 1 Hz with a full cycle from the surface to 300 meters recorded every 80 minutes. At the surface and 300m, water samples were collected during precipitation events and raindrop sizes were measured continuously using Parsivel instruments. We use this unique suite of measurements and, in particular, exploit the differences between the surface and 300m observations to constrain the surface layer hydrological mass balance during and after rain events, and evaluate parameterization choices for rain evaporation and moisture recycling in current isotope-enabled climate models. Aggregate raindrop size measurements showed shifts from populations of smaller raindrops at 300m to larger raindrops at the surface, contrary to what is expected for rain evaporation. Convective storms resulted in more uniform signatures between the surface and 300m, as well as longer isotope equilibration and adjustment time scales, whereas low Dexcess signatures (<9 to negative) during stratiform drizzle events were indicative of a greater degree of rain evaporation. Our observational results suggest that water vapor-rain equilibration is rarely achieved, and modification of the kinetic fractionation factor is necessary to better capture drop-size related isotope changes. This has implications not only for refining current global climate models, but also for interpreting proxy records connected to rainfall signatures that aid in understanding past hydrology.

Genomes of surface isolates of Alteromonas macleodii: the life of a widespread marine opportunistic copiotroph

PubMed Central

López-Pérez, Mario; Gonzaga, Aitor; Martin-Cuadrado, Ana-Belen; Onyshchenko, Olga; Ghavidel, Akbar; Ghai, Rohit; Rodriguez-Valera, Francisco

2012-01-01

Alteromonas macleodii is a marine gammaproteobacterium with widespread distribution in temperate or tropical waters. We describe three genomes of isolates from surface waters around Europe (Atlantic, Mediterranean and Black Sea) and compare them with a previously described deep Mediterranean isolate (AltDE) that belongs to a widely divergent clade. The surface isolates are quite similar, the most divergent being the Black Sea (BS11) isolate. The genomes contain several genomic islands with different gene content. The recruitment of very similar genomic fragments from metagenomes in different locations indicates that the surface clade is globally abundant with little effect of geography, even the AltDE and the BS11 genomes recruiting from surface samples in open ocean locations. The finding of CRISPR protospacers of AltDE in a lysogenic phage in the Atlantic (English Channel) isolate illustrates a flow of genetic material among these clades and a remarkably wide distribution of this phage. PMID:23019517

Aqueous or solvent based surface modification: The influence of the combination solvent - organic functional group on the surface characteristics of titanium dioxide grafted with organophosphonic acids

NASA Astrophysics Data System (ADS)

Roevens, Annelore; Van Dijck, Jeroen G.; Geldof, Davy; Blockhuys, Frank; Prelot, Benedicte; Zajac, Jerzy; Meynen, Vera

2017-09-01

To alter the versatility of interactions at its surface, TiO2 is modified with organophosphonic acids (PA). A thorough understanding of the role of all synthesis conditions is necessary to achieve controlled functionalization. This study reports on the effect of using water, toluene and their mixtures when performing the modification of TiO2 with PA. Sorption and calorimetry measurements of surface interactions with various probing species clearly indicate that, by grafting PA in water, clear differences appear in the distribution of organic groups on the surface. Also the functional group of the PA determines the impact of using water as solvent. Modification in toluene results in a higher modification degree for propylphosphonic acid (3PA), as the solvent-solute interaction may hinder the grafting with phenylphosphonic acid (PhPA) in toluene. Water is preferred as solvent for PhPA modification as stabilizing π-OH interactions enhance surface grafting overcoming the competitive interaction of water at the surface as observed with 3PA. By using water in toluene mixtures for the functionalization of TiO2 with 3PA, the degree of functionalization is higher than when only water or toluene is used. Furthermore, adding small amounts of water leads to the formation of titanium propylphosphonates, next to surface grafting.

COST EFFECTIVE SEAWATER DESALINATION WITH FICP ELEMENT ARRAYS - PHASE II

EPA Science Inventory

Lack of fresh water hinders economic development, devastates human health, leads to environmental degradation and foments political instability. We obtain our water from limited and unevenly distributed surface and underground freshwater sources. Over withdrawal from these ...

Effective water surface mapping in macrophyte-covered reservoirs in NE Brazil based on TerraSAR-X time series

NASA Astrophysics Data System (ADS)

Zhang, Shuping; Foerster, Saskia; Medeiros, Pedro; de Araújo, José Carlos; Waske, Bjoern

2018-07-01

Water supplies in northeastern Brazil strongly depend on the numerous surface water reservoirs of various sizes there. However, the seasonal and long-term water surface dynamics of these reservoirs, particularly the large number of small ones, remain inadequately known. Remote sensing techniques have shown great potentials in water bodies mapping. Yet, the widespread presence of macrophytes in most of the reservoirs often impedes the delineation of the effective water surfaces. Knowledge of the dynamics of the effective water surfaces in the reservoirs is essential for understanding, managing, and modelling the local and regional water resources. In this study, a two-year time series of TerraSAR-X (TSX) satellite data was used to monitor the effective water surface areas in nine reservoirs in NE Brazil. Calm open water surfaces were obtained by segmenting the backscattering coefficients of TSX images with minimum error thresholding. Linear unmixing was implemented on the distributions of gray-level co-occurrence matrix (GLCM) variance in the reservoirs to quantify the proportions of sub-populations dominated by different types of scattering along the TSX time series. By referring to the statistics and the seasonal proportions of the GLCM variance sub-populations the GLCM variance was segmented to map the vegetated water surfaces. The effective water surface areas that include the vegetation-covered waters as well as calm open water in the reservoirs were mapped with accuracies >77%. The temporal and spatial change patterns of water surfaces in the nine reservoirs over a period of two consecutive dry and wet seasons were derived. Precipitation-related soil moisture changes, topography and the dense macrophyte canopies are the main sources of errors in the such-derived effective water surfaces. Independent from in-situ data, the approach employed in this study shows great potential in monitoring water surfaces of different complexity and macrophyte coverage. The effective water surface areas obtained for the reservoirs can provide valuable input for efficient water management and improve the hydrological modelling in this region.

Tuning the pore composition by two simultaneous interfacial self-assembly processes: breath figures and coffee stain.

PubMed

de León, Alberto S; del Campo, Adolfo; Fernández-García, Marta; Rodríguez-Hernández, Juan; Muñoz-Bonilla, Alexandra

2014-06-03

In the current paper, we prepared microstructured porous films by the breath figures approach using polymer blends consisting of polystyrene as the major component and an amphiphilic additive, either a synthetic block copolymer {two different polystyrene-b-poly[poly(ethylene glycol) methyl ether methacrylate] copolymers} or a series of commercial surfactants. Tetrahydrofuran was employed as the solvent. Confocal micro-Raman spectroscopy demonstrated the preferential location of the amphiphilic additives in the cavities of the film as a consequence of the breath figures mechanism. However, the distribution of the copolymer within the cavities varies depending upon the structure and, more precisely, the surface properties of the additives, leading to three different situations. First of all, the copolymer with a larger polystyrene segment, insoluble in the condensed water droplets, is homogeneously distributed along the whole surface of the cavities. On the contrary, when the copolymer is soluble in water (shorter polystyrene segment), it migrates inside the droplet and a coffee-stain phenomenon takes place during the water droplet evaporation, conducting to a ring-like deposition on the top edge of the cavities. Finally, when a water-soluble surfactant with high surface activity is used, the surfactant is solubilized inside the water droplets, which provokes a decrease on the surface tension and the coffee-ring effect is modified. In this situation, the copolymer covers the bottom of the pore.

Global Distribution of Outbreaks of Water-Associated Infectious Diseases

PubMed Central

Yang, Kun; LeJeune, Jeffrey; Alsdorf, Doug; Lu, Bo; Shum, C. K.; Liang, Song

2012-01-01

Background Water plays an important role in the transmission of many infectious diseases, which pose a great burden on global public health. However, the global distribution of these water-associated infectious diseases and underlying factors remain largely unexplored. Methods and Findings Based on the Global Infectious Disease and Epidemiology Network (GIDEON), a global database including water-associated pathogens and diseases was developed. In this study, reported outbreak events associated with corresponding water-associated infectious diseases from 1991 to 2008 were extracted from the database. The location of each reported outbreak event was identified and geocoded into a GIS database. Also collected in the GIS database included geo-referenced socio-environmental information including population density (2000), annual accumulated temperature, surface water area, and average annual precipitation. Poisson models with Bayesian inference were developed to explore the association between these socio-environmental factors and distribution of the reported outbreak events. Based on model predictions a global relative risk map was generated. A total of 1,428 reported outbreak events were retrieved from the database. The analysis suggested that outbreaks of water-associated diseases are significantly correlated with socio-environmental factors. Population density is a significant risk factor for all categories of reported outbreaks of water-associated diseases; water-related diseases (e.g., vector-borne diseases) are associated with accumulated temperature; water-washed diseases (e.g., conjunctivitis) are inversely related to surface water area; both water-borne and water-related diseases are inversely related to average annual rainfall. Based on the model predictions, “hotspots” of risks for all categories of water-associated diseases were explored. Conclusions At the global scale, water-associated infectious diseases are significantly correlated with socio-environmental factors, impacting all regions which are affected disproportionately by different categories of water-associated infectious diseases. PMID:22348158

Global Patterns of Bacterial Beta-Diversity in Seafloor and Seawater Ecosystems

PubMed Central

Zinger, Lucie; Amaral-Zettler, Linda A.; Fuhrman, Jed A.; Horner-Devine, M. Claire; Huse, Susan M.; Welch, David B. Mark; Martiny, Jennifer B. H.; Sogin, Mitchell; Boetius, Antje; Ramette, Alban

2011-01-01

Background Marine microbial communities have been essential contributors to global biomass, nutrient cycling, and biodiversity since the early history of Earth, but so far their community distribution patterns remain unknown in most marine ecosystems. Methodology/Principal Findings The synthesis of 9.6 million bacterial V6-rRNA amplicons for 509 samples that span the global ocean's surface to the deep-sea floor shows that pelagic and benthic communities greatly differ, at all taxonomic levels, and share <10% bacterial types defined at 3% sequence similarity level. Surface and deep water, coastal and open ocean, and anoxic and oxic ecosystems host distinct communities that reflect productivity, land influences and other environmental constraints such as oxygen availability. The high variability of bacterial community composition specific to vent and coastal ecosystems reflects the heterogeneity and dynamic nature of these habitats. Both pelagic and benthic bacterial community distributions correlate with surface water productivity, reflecting the coupling between both realms by particle export. Also, differences in physical mixing may play a fundamental role in the distribution patterns of marine bacteria, as benthic communities showed a higher dissimilarity with increasing distance than pelagic communities. Conclusions/Significance This first synthesis of global bacterial distribution across different ecosystems of the World's oceans shows remarkable horizontal and vertical large-scale patterns in bacterial communities. This opens interesting perspectives for the definition of biogeographical biomes for bacteria of ocean waters and the seabed. PMID:21931760

Interaction between surface water areas and groundwater in Hanoi city, Viet Nam

NASA Astrophysics Data System (ADS)

Hayashi, T.; Kuroda, K.; Do Thuan, A.; Tran Thi Viet, N.; Takizawa, S.

2012-12-01

Hanoi is the capital of Viet Nam and the second largest city in this country (population: 6.45 million in 2009). Hanoi city has developed along the Red River and has many lakes, ponds and canals. However, recent rapid urbanization of this city has reduced number of natural water areas such as ponds and lakes by reclamation not only in the central area but the suburban area. Canals also have been reclaimed or cut into pieces. Contrary, number of artificial water areas such as fish cultivation pond has rapidly increased. On the other hand, various kind of waste water flows into these natural and artificial water areas and induces pollution and eutrophication. These waste waters also have possibility of pollution of groundwater that is one of major water resources in this city. In addition, groundwater in this area has high concentrations of Arsenic, Fe and NH4. Thus, groundwater use may causes re-circulation of Arsenic. However, studies on the interaction between surface water areas and groundwater and on the role of surface water areas for solute transport with water cycle are a few. Therefore, we focused on these points and took water samples of river, pond and groundwater from four communities in suburban areas: two communities are located near the Red River and other two are far from the River. Also, columnar sediment samples of these ponds were taken and pore water was abstracted. Major dissolved ions, metals and stable isotopes of oxygen and hydrogen of water samples were analyzed. As for water cycle, from the correlation between δ18O and δD, the Red River water (after GNIR) were distributed along the LMWL (δD=8.2δ18O+14.1, calculated from precipitation (after GNIP)). On the other hand, although the pond waters in rainy season were distributed along the LMWL, that in dry season were distributed along the local evaporation line (LEL, slope=5.6). The LEL crossed with the LMWL at around the point of weighted mean values of precipitation in rainy season and of the Red river. Groundwater samples were also distributed along the LEL and there was no seasonal change. Thus, groundwater in these communities was mainly recharged by mixing of precipitation/the Red River and evaporated water bodies. Considering the land use in these communities, evaporated water bodies were considered to be not only ponds but also paddy fields. As for solute transport, concentration of dissolved Arsenic (filtered by 0.45μm) of the pond water (3 - 10 μg/L) was slightly higher than the Red River (~ 3 μg/L) and was much lower than that of groundwater (~ 60 μg/L). On the other hand, concentration of dissolved Arsenic in the pore water of sediments (10 - 85 μg/L) was close to groundwater. Also, other metal elements showed the same trend. Therefore, Arsenic and other metal elements recharged to these ponds were considered to be adsorbed by sediments (including organic matters). That is, pond sediments played an important role as a filter of metal elements. The results of this study strongly suggested that the surface water areas such as ponds and paddy fields are one of main groundwater sources. Also, ponds play important role for solute transport of metal elements. Therefore, management of these surface water areas is important to conserve groundwater environment.

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.

Stability of ice on the Moon with rough topography

NASA Astrophysics Data System (ADS)

Rubanenko, Lior; Aharonson, Oded

2017-11-01

The heat flux incident upon the surface of an airless planetary body is dominated by solar radiation during the day, and by thermal emission from topography at night. Motivated by the close relationship between this heat flux, the surface temperatures, and the stability of volatiles, we consider the effect of the slope distribution on the temperature distribution and hence prevalence of cold-traps, where volatiles may accumulate over geologic time. We develop a thermophysical model accounting for insolation, reflected and emitted radiation, and subsurface conduction, and use it to examine several idealized representations of rough topography. We show how subsurface conduction alters the temperature distribution of bowl-shaped craters compared to predictions given by past analytic models. We model the dependence of cold-traps on crater geometry and quantify the effect that while deeper depressions cast more persistent shadows, they are often too warm to trap water ice due to the smaller sky fraction and increased reflected and reemitted radiation from the walls. In order to calculate the temperature distribution outside craters, we consider rough random surfaces with a Gaussian slope distribution. Using their derived temperatures and additional volatile stability models, we estimate the potential area fraction of stable water ice on Earth's Moon. For example, surfaces with slope RMS ∼15° (corresponding to length-scales ∼10 m on the lunar surface) located near the poles are found to have a ∼10% exposed cold-trap area fraction. In the subsurface, the diffusion barrier created by the overlaying regolith increases this area fraction to ∼40%. Additionally, some buried water ice is shown to remain stable even beneath temporarily illuminated slopes, making it more readily accessible to future lunar excavation missions. Finally, due to the exponential dependence of stability of ice on temperature, we are able to constrain the maximum thickness of the unstable layer to a few decimeters.

Models and observations of foam coverage and bubble content in the surf zone

NASA Astrophysics Data System (ADS)

Kirby, J. T.; Shi, F.; Holman, R. A.

2010-12-01

Optical and acoustical observations and communications are hampered in the nearshore by the presence of bubbles and foam generated by breaking waves. Bubble clouds in the water column provide a highly variable (both spatially and temporally) obstacle to direct acoustic and optical paths. Persistent foam riding on the water surface creates a primary occlusion of optical penetration into the water column. In an effort to better understand and predict the level of bubble and foam content in the surfzone, we have been pursuing the development of a detailed phase resolved model of fluid and gaseous components of the water column, using a Navier-Stokes/VOF formulation extended to include a multiphase description of polydisperse bubble populations. This sort of modeling provides a detailed description of large scale turbulent structures and associated bubble transport mechanisms under breaking wave crests. The modeling technique is too computationally intensive, however, to provide a wider-scale description of large surfzone regions. In order to approach the larger scale problem, we are developing a model for spatial and temporal distribution of foam and bubbles within the framework of a Boussinesq model. The basic numerical framework for the code is described by Shi et al (2010, this conference). Bubble effects are incorporated both in the mass and momentum balances for weakly dispersive, fully nonlinear waves, with spatial and temporal bubble distributions parameterized based on the VOF modeling and measurements and tied to the computed rate of dissipation of energy during breaking. A model of a foam layer on the water surface is specified using a shallow water formulation. Foam mass conservation includes source and sink terms representing outgassing of the water column, direct foam generation due to surface agitation, and erosion due to bubble bursting. The foam layer motion in the plane of the water surface arises due to a balance of drag forces due to wind and water column motion. Preliminary steps to calibrate and verify the resulting models will be taken based on results to be collected during the Surf Zone Optics experiment at Duck, NC in September 2010. Initial efforts will focus on an examination of breaking wave patterns and persistent foam distributions, using ARGUS imagery.

Physics of greenhouse effect and convection in warm oceans

NASA Technical Reports Server (NTRS)

Inamdar, A. K.; Ramanathan, V.

1994-01-01

Sea surface temperature (SST) in roughly 50% of the tropical Pacific Ocean is warm enough (SST greater than 300 K) to permit deep convection. This paper examines the effects of deep convection on the climatological mean vertical distributions of water vapor and its greenhouse effect over such warm oceans. The study, which uses a combination of satellite radiation budget observations, atmospheric soundings deployed from ships, and radiation model calculations, also examines the link between SST, vertical distribution of water vapor, and its greenhouse effect in the tropical oceans. Since the focus of the study is on the radiative effects of water vapor, the radiation model calculations do not include the effects of clouds. The data are grouped into nonconvective and convective categories using SST as an index for convective activity. On average, convective regions are more humid, trap significantly more longwave radiation, and emit more radiation to the sea surface. The greenhouse effect in regions of convection operates as per classical ideas, that is, as the SST increases, the atmosphere traps the excess longwave energy emitted by the surface and reradiates it locally back to the ocean surface. The important departure from the classical picture is that the net (up minus down) fluxes at the surface and at the top of the atmosphere decrease with an increase in SST; that is, the surface and the surface-troposphere column lose the ability to radiate the excess energy to space. The cause of this super greenhouse effect at the surface is the rapid increase in the lower-troposphere humidity with SST; that of the column is due to a combination of increase in humidity in the entire column and increase in the lapse rate within the lower troposphere. The increase in the vertical distribution of humidity far exceeds that which can be attributed to the temperature dependence of saturation vapor pressure; that is, the tropospheric relative humidity is larger in convective regions. The positive coupling between SST and the radiative warming of the surface by the water vapor greenhouse effect is also shown to exist on interannual time scales.

A Probabilistic Analysis of Surface Water Flood Risk in London.

PubMed

Jenkins, Katie; Hall, Jim; Glenis, Vassilis; Kilsby, Chris

2018-06-01

Flooding in urban areas during heavy rainfall, often characterized by short duration and high-intensity events, is known as "surface water flooding." Analyzing surface water flood risk is complex as it requires understanding of biophysical and human factors, such as the localized scale and nature of heavy precipitation events, characteristics of the urban area affected (including detailed topography and drainage networks), and the spatial distribution of economic and social vulnerability. Climate change is recognized as having the potential to enhance the intensity and frequency of heavy rainfall events. This study develops a methodology to link high spatial resolution probabilistic projections of hourly precipitation with detailed surface water flood depth maps and characterization of urban vulnerability to estimate surface water flood risk. It incorporates probabilistic information on the range of uncertainties in future precipitation in a changing climate. The method is applied to a case study of Greater London and highlights that both the frequency and spatial extent of surface water flood events are set to increase under future climate change. The expected annual damage from surface water flooding is estimated to be to be £171 million, £343 million, and £390 million/year under the baseline, 2030 high, and 2050 high climate change scenarios, respectively. © 2017 Society for Risk Analysis.

Morphology and mechanism of the very large dunes in the tidal reach of the Yangtze River, China

NASA Astrophysics Data System (ADS)

Shuwei, Zheng; Heqin, Cheng; Shuaihu, Wu; Shengyu, Shi; Wei, Xu; Quanping, Zhou; Yuehua, Jiang

2017-05-01

High-resolution multibeam data was used to interpret the surface morphology of very large dunes (VLDs) in the tidal reach of the Yangtze River, China. These VLDs can be divided into three categories according to their surface morphological characteristics. (1) VLDs-I: those with a smooth surface and cross-section; (2) VLDs-II: those accompanied by secondary dunes; (3) VLDs-III: those accompanied by secondary dunes and numerous elliptical pits. Parameters and spatial distribution of VLDs, and bed surface sediment were analyzed in the laboratory. Overall, channel morphology is an important factor affecting the development of VLDs, and channels with narrow and straight and certain water surface slope are facilitating the development of VLDs by constraining stream power. Meanwhile, distribution density of VLDs depicts a decreasing trend from Chizhou towards the estuary, are probably influenced by channel morphology and width. Associated pits in VLDs-III change the 3D dune morphology by distributing in secondary dunes as beads. The Three Gorges Dam project (TGP) leads to the bed surface sediment activity frequently and leads to the riverbed surface sediment coarsens, which promotes the further development of dunes. Moreover, other human activities, such as river regulation project, sand mining and Deep Water Channel Regulation Project have changed the regional river boundary conditions and hydrodynamic conditions are influential on the development of VLDs.

Spaceborne Microwave Imagers

NASA Technical Reports Server (NTRS)

Stacey, J. M.

1991-01-01

Monograph presents comprehensive overview of science and technology of spaceborne microwave-imaging systems. Microwave images used as versatile orbiting, remote-sensing systems to investigate atmospheres and surfaces of planets. Detect surface objects through canopies of clouds, measure distributions of raindrops in clouds that their views penetrate, find meandering rivers in rain forests and underground water in arid regions, and provide information on ocean currents, wakes, ice/water boundaries, aircraft, ships, buoys, and bridges.

Size effects in MgO cube dissolution.

PubMed

Baumann, Stefan O; Schneider, Johannes; Sternig, Andreas; Thomele, Daniel; Stankic, Slavica; Berger, Thomas; Grönbeck, Henrik; Diwald, Oliver

2015-03-10

Stability parameters and dissolution behavior of engineered nanomaterials in aqueous systems are critical to assess their functionality and fate under environmental conditions. Using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction, we investigated the stability of cubic MgO particles in water. MgO dissolution proceeding via water dissociation at the oxide surface, disintegration of Mg(2+)-O(2-) surface elements, and their subsequent solvation ultimately leads to precipitation of Mg(OH)2 nanosheets. At a pH ≥ 10, MgO nanocubes with a size distribution below 10 nm quantitatively dissolve within few minutes and convert into Mg(OH)2 nanosheets. This effect is different from MgO cubes originating from magnesium combustion in air. With a size distribution in the range 10 nm ≤ d ≤ 1000 nm they dissolve with a significantly smaller dissolution rate in water. On these particles water induced etching generates (110) faces which, above a certain face area, dissolve at a rate equal to that of (100) planes.1 The delayed solubility of microcrystalline MgO is attributed to surface hydroxide induced self-inhibition effects occurring at the (100) and (110) microplanes. The present work underlines the importance of morphology evolution and surface faceting of engineered nanomaterials particles during their dissolution.

Do we understand the temperature profile of air-water interface?

NASA Astrophysics Data System (ADS)

Solcerova, A.; van Emmerik, T. H. M.; Uittenbogaard, R.; van de Ven, F. H. M.; Van De Giesen, N.

2017-12-01

Lakes and reservoirs exchange energy with the atmosphere through long-wave radiation and turbulent heat fluxes. Calculation of those fluxes often depend on the surface temperature. Several recent studies used high resolution Distributed Temperature Sensing (DTS) to measure the temperature of air-water interface. We present results of three of such studies conducted on three different locations with three different climates (Ghana, Israel, The Netherland). Measurements from all presented studies show a distinct temperature drop close to the water surface during daytime. We provide several possible explanations for existence of such deviation of temperature, and discuss the plausibility of each. Explaining the measured temperature drop is crucial for a better understanding of the energy balance of lake surface, and estimation of the surface energy balance.

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).

Temperature dependency of long-chain alkenone distributions in recent to fossil limnic sediments and in lake waters 1

NASA Astrophysics Data System (ADS)

Zink, Klaus-G.; Leythaeuser, Detlev; Melkonian, Michael; Schwark, Lorenz

2001-01-01

Distribution patterns of C 37 and C 38 polyunsaturated long-chain alkenones (LCAs) serve as proxies for the determination of paleotemperatures for marine surface waters. We studied Recent/Subrecent and Late Glacial/Holocene sediments from Germany, Austria, Russia, and the U.S. to test for a correspondence between LCA distribution and surface water temperature in limnic systems. Previously, reports of LCA occurrence were restricted to sediments of 6 wide distributed freshwater and alkaline lakes. In this study 13 of 27 investigated lakes contained LCAs in surface sediments with concentrations varying between 12 to 205 μg/g TOC. Late Glacial to Holocene sediment sequences from Lake Steisslingen and Lake Wummsee, (Germany), Lake Pichozero (Russia), and Brush Lake (U.S.A.) contained abundant LCAs with averaged concentrations of 33 to 7536 μg/g TOC. For the first time we observed the occurrence of LCAs within in the water column of oligotrophic Lake Stechlin (NE-Germany). Alkenones were restricted to the zone of maximum chlorophyll concentration within the water column indicating that LCAs have a biosynthetic origin and can be attributed to phototrophic (micro)algae. Attempts to identify the producing organism, however, were not successful. Culture experiments allow various phytoplankton to be excluded as producers. Alkenone-producing algae are evidently of small size, hindering microscopical identification. LCAs commonly occur in high concentrations in Late Glacial sediments, mainly during the cold period of the Younger Dryas, whereas the Holocene usually is devoid of polyunsaturated alkenones. The episodic occurrence of LCAs restricts their utility as proxies for continuous geological records. Furthermore, lack of microscopical verification and the episodic distribution allow for different producers of unsaturated alkenones in Recent and Late Glacial sediments. An empirical relationship between LCA distribution and temperature was observed. In fossil sediments from Lake Steisslingen, there is a good correspondence between Uk37 and the temperature-controlled δ 18O isotope ratio of lake chalk. Comparison of LCA patterns obtained from the uppermost centimetres of lake sediments with averaged summer surface water temperatures of the lakes studied, demonstrates a trend of covariance ( r2: Uk'37 = 0.90, Uk37 = 0.67; n = 9). Hence, the same mechanism that causes temperature-dependence of LCA patterns in marine systems might be effective in limnic settings. Identification of alkenone producers and their culture under controlled temperature are still mandatory before LCAs can be routinely applied as paleotemperature proxy in limnic systems.

Modelling urban rainfall-runoff responses using an experimental, two-tiered physical modelling environment

NASA Astrophysics Data System (ADS)

Green, Daniel; Pattison, Ian; Yu, Dapeng

2016-04-01

Surface water (pluvial) flooding occurs when rainwater from intense precipitation events is unable to infiltrate into the subsurface or drain via natural or artificial drainage channels. Surface water flooding poses a serious hazard to urban areas across the world, with the UK's perceived risk appearing to have increased in recent years due to surface water flood events seeming more severe and frequent. Surface water flood risk currently accounts for 1/3 of all UK flood risk, with approximately two million people living in urban areas at risk of a 1 in 200-year flood event. Research often focuses upon using numerical modelling techniques to understand the extent, depth and severity of actual or hypothetical flood scenarios. Although much research has been conducted using numerical modelling, field data available for model calibration and validation is limited due to the complexities associated with data collection in surface water flood conditions. Ultimately, the data which numerical models are based upon is often erroneous and inconclusive. Physical models offer a novel, alternative and innovative environment to collect data within, creating a controlled, closed system where independent variables can be altered independently to investigate cause and effect relationships. A physical modelling environment provides a suitable platform to investigate rainfall-runoff processes occurring within an urban catchment. Despite this, physical modelling approaches are seldom used in surface water flooding research. Scaled laboratory experiments using a 9m2, two-tiered 1:100 physical model consisting of: (i) a low-cost rainfall simulator component able to simulate consistent, uniformly distributed (>75% CUC) rainfall events of varying intensity, and; (ii) a fully interchangeable, modular plot surface have been conducted to investigate and quantify the influence of a number of terrestrial and meteorological factors on overland flow and rainfall-runoff patterns within a modelled urban setting. Terrestrial factors investigated include altering the physical model's catchment slope (0°- 20°), as well as simulating a number of spatially-varied impermeability and building density/configuration scenarios. Additionally, the influence of different storm dynamics and intensities were investigated. Preliminary results demonstrate that rainfall-runoff responses in the physical modelling environment are highly sensitive to slight increases in catchment gradient and rainfall intensity and that more densely distributed building layouts significantly increase peak flows recorded at the physical model outflow when compared to sparsely distributed building layouts under comparable simulated rainfall conditions.

Modeling and Optimization for Management of Intermittent Water Supply

NASA Astrophysics Data System (ADS)

Lieb, A. M.; Wilkening, J.; Rycroft, C.

2014-12-01

In many urban areas, piped water is supplied only intermittently, as valves direct water to different parts of the water distribution system at different times. The flow is transient, and may transition between free-surface and pressurized, resulting in complex dynamical features with important consequences for water suppliers and users. These consequences include degradation of distribution system components, compromised water quality, and inequitable water availability. The goal of this work is to model the important dynamics and identify operating conditions that mitigate certain negative effects of intermittent water supply. Specifically, we will look at controlling valve parameters occurring as boundary conditions in a network model of transient, transition flow through closed pipes. Gradient-based optimization will be used to find boundary values to minimize pressure gradients and ensure equitable water availability at system endpoints.

Optimal Dynamics of Intermittent Water Supply

NASA Astrophysics Data System (ADS)

Lieb, Anna; Wilkening, Jon; Rycroft, Chris

2014-11-01

In many urban areas of the developing world, piped water is supplied only intermittently, as valves direct water to different parts of the water distribution system at different times. The flow is transient, and may transition between free-surface and pressurized, resulting in complex dynamical features with important consequences for water suppliers and users. These consequences include degradation of distribution system components, compromised water quality, and inequitable water availability. The goal of this work is to model the important dynamics and identify operating conditions that mitigate certain negative effects of intermittent water supply. Specifically, we will look at valve parameters occurring as boundary conditions in a network model of transient, transition flow through closed pipes. Optimization will be used to find boundary values to minimize pressure gradients and ensure equitable water availability.

An index for plant water deficit based on root-weighted soil water content

NASA Astrophysics Data System (ADS)

Shi, Jianchu; Li, Sen; Zuo, Qiang; Ben-Gal, Alon

2015-03-01

Governed by atmospheric demand, soil water conditions and plant characteristics, plant water status is dynamic, complex, and fundamental to efficient agricultural water management. To explore a centralized signal for the evaluation of plant water status based on soil water status, two greenhouse experiments investigating the effect of the relative distribution between soil water and roots on wheat and rice were conducted. Due to the significant offset between the distributions of soil water and roots, wheat receiving subsurface irrigation suffered more from drought than wheat under surface irrigation, even when the arithmetic averaged soil water content (SWC) in the root zone was higher. A significant relationship was found between the plant water deficit index (PWDI) and the root-weighted (rather than the arithmetic) average SWC over root zone. The traditional soil-based approach for the estimation of PWDI was improved by replacing the arithmetic averaged SWC with the root-weighted SWC to take the effect of the relative distribution between soil water and roots into consideration. These results should be beneficial for scheduling irrigation, as well as for evaluating plant water consumption and root density profile.

Geochemical Composition of Surface Water in the Mineralized Lom Basin, East Cameroon: Natural and Anthropogenic Sources.

NASA Astrophysics Data System (ADS)

Mimba, M. E.; Ohba, T.; Nguemhe Fils, S. C.; Wirmvem, M. J.

2016-12-01

Thousands of people in East Cameroon depend on surface water for consumption and domestic purposes. The Lom basin, north of the region, is heavily mineralized especially in gold owing to its regional geological setting. Although research has been done regarding the rock type, age, formation history and reconnaissance gold surveys, surface water investigation in the area has received limited attention. Thus, this study appraises the first regional hydrogeochemical program for environmental assessment of the mineralized Lom basin. Fifty-two representative stream water samples were collected under base flow conditions and analysed for major cations (Ca2+, Mg2+, Na+, K+ ), major anions (HCO3-, F-, Cl-, NO2-, NO3-, Br-, PO43-, SO42- ) and stable isotopes (δD and δ18O). Calcium and HCO3- were the dominant ions. The chemical facies were CaHCO3 and NaHCO3 indicating surface water draining igneous/metamorphic rocks in hot and humid equatorial climate, resulting in the discordant dissolution of primary silicate minerals. From the isotopic evaluation, the stream water is of meteoric origin, shows negligible evaporation effect and has a common recharge source. The major ion geochemistry demonstrated the potential to discriminate between natural and anthropogenic origins. Distribution trends of Ca2+, Mg2+, Na+, K+, HCO3- and SO42- showed a correlation with the lithology and the occurrence of sulphide minerals associated with hydrothermal gold mineralization in the area. The distribution patterns of NO3- and Cl- reflect pollution from settlement. Overall, the chemistry of stream water in the Lom basin is mainly controlled by rock weathering compared to anthropogenic influence. Surface water quality is easily influenced by anthropogenic activities, and stream sediment collects effectively trace metals resulting from such activities. Hence, geochemical mapping incorporating stream water and stream sediment is of considerable value in future investigations within the Lom basin.

Spatial Variability of Factors Influencing the Distribution of Triclosan in Sediments and Water of an Urbanized Estuarine Embayment

EPA Science Inventory

Triclosan (TCS) is a broad spectrum anti-microbial compound added to many consumer and personal care products. TCS enters water bodies primarily through wastewater treatment plant (WWTP) effluent and may be introduced by combined sewer overflows or surface water runoff. In estu...

Public water-supply systems and associated water use in Tennessee, 2005

USGS Publications Warehouse

Robinson, John A.; Brooks, Jaala M.

2010-01-01

Public water-supply systems in Tennessee provide water to for domestic, industrial, and commercial uses, and municipal services. In 2005, more than 569 public water-supply systems distributed about 920 million gallons per day (Mgal/d) of non-purchased surface water and groundwater to a population of nearly 6 million in Tennessee. Surface-water sources provided 64 percent (about 591 Mgal/d) of the State's water supplies. Groundwater produced from wells and springs in Middle and East Tennessee and from wells in West Tennessee provided 36 percent (about 329 Mgal/d) of the public water supplies. Gross per capita water use for Tennessee in 2005 was about 171 gallons per day. Water withdrawals by public water-supply systems in Tennessee have increased from 250 Mgal/d in 1955 to 920 Mgal/d in 2005. Tennessee public water-supply systems withdraw less groundwater than surface water, and surface-water use has increased at a faster rate than groundwater use. However, 34 systems reported increased groundwater withdrawals during 2000–2005, and 15 of these 34 systems reported increases of 1 Mgal/d or more. The county with the largest surface-water withdrawal rate (130 Mgal/d) was Davidson County. Each of Tennessee's 95 counties was served by at least one public water-supply system in 2005. The largest groundwater withdrawal rate (about 167 Mgal/d) by a single public water-supply system was reported by Memphis Light, Gas and Water, which served 654,267 people in Shelby County in 2005.

Increasing chloride in rivers of the conterminous U.S. and linkages to potential corrosivity and lead action level exceedances in drinking water.

PubMed

Stets, E G; Lee, C J; Lytle, D A; Schock, M R

2018-02-01

Corrosion in water-distribution systems is a costly problem and controlling corrosion is a primary focus of efforts to reduce lead (Pb) and copper (Cu) in tap water. High chloride concentrations can increase the tendency of water to cause corrosion in distribution systems. The effects of chloride are also expressed in several indices commonly used to describe the potential corrosivity of water, the chloride-sulfate mass ratio (CSMR) and the Larson Ratio (LR). Elevated CSMR has been linked to the galvanic corrosion of Pb whereas LR is indicative of the corrosivity of water to iron and steel. Despite the known importance of chloride, CSMR, and LR to the potential corrosivity of water, monitoring of seasonal and interannual changes in these parameters is not common among water purveyors. We analyzed long-term trends (1992-2012) and the current status (2010-2015) of chloride, CSMR, and LR in order to investigate the short and long-term temporal variability in potential corrosivity of US streams and rivers. Among all sites in the trend analyses, chloride, CSMR, and LR increased slightly, with median changes of 0.9mgL -1 , 0.08, and 0.01, respectively. However, urban-dominated sites had much larger increases, 46.9mgL -1 , 2.50, and 0.53, respectively. Median CSMR and LR in urban streams (4.01 and 1.34, respectively) greatly exceeded thresholds found to cause corrosion in water distribution systems (0.5 and 0.3, respectively). Urbanization was strongly correlated with elevated chloride, CSMR, and LR, especially in the most snow-affected areas in the study, which are most likely to use road salt. The probability of Pb action-level exceedances (ALEs) in drinking water facilities increased along with raw surface water CSMR, indicating a statistical connection between surface water chemistry and corrosion in drinking water facilities. Optimal corrosion control will require monitoring of critical constituents reflecting the potential corrosivity in surface waters. Published by Elsevier B.V.

STS-55 Earth observation of the Timor Sea

NASA Technical Reports Server (NTRS)

1993-01-01

STS-55 Earth observation taken from Columbia, Orbiter Vehicle (OV) 102, shows the Timor Sea along the south coast of Timor. The sunglint pattern shows a sharp boundary in sea surface temperature, with cooler water along the coast and warmer water offshore. The sunglint brightness reveals water surface roughness with bright indicating smooth water and dark representing rough water. Cooler water is smoother because it acts to stabilize the atmospheric boundary layer, while the warm water acts to destabilize the atmosphere. Another indication of water temperature is the cloud pattern. Advection within the atmosphere as a result of warming at the sea surface forms low-level clouds with the small, popcorn-like appearance seen in upper right corner of the photograph. The cool water, on the other hand, is relatively free of the popcorn-like clouds. The distribution of the clouds indicates that the wind is blowing toward the upper right corner of the photograph. Also note the line of low-level

Water Hydrogen-Bonding Network Structure and Dynamics at Phospholipid Multibilayer Surface: Femtosecond Mid-IR Pump-Probe Spectroscopy.

PubMed

Kundu, Achintya; Błasiak, Bartosz; Lim, Joon-Hyung; Kwak, Kyungwon; Cho, Minhaeng

2016-03-03

The water hydrogen-bonding network at a lipid bilayer surface is crucial to understanding membrane structures and its functional activities. With a phospholipid multibilayer mimicking a biological membrane, we study the temperature dependence of water hydrogen-bonding structure, distribution, and dynamics at a lipid multibilayer surface using femtosecond mid-IR pump-probe spectroscopy. We observe two distinguished vibrational lifetime components. The fast component (0.6 ps) is associated with water interacting with a phosphate part, whereas the slow component (1.9 ps) is with bulk-like choline-associated water. With increasing temperature, the vibrational lifetime of phosphate-associated water remains constant though its relative fraction dramatically increases. The OD stretch vibrational lifetime of choline-bound water slows down in a sigmoidal fashion with respect to temperature, indicating a noticeable change of the water environment upon the phase transition. The water structure and dynamics are thus shown to be in quantitative correlation with the structural change of liquid multibilayer upon the gel-to-liquid crystal phase transition.

Antibiotics in the surface water of the Yangtze Estuary: occurrence, distribution and risk assessment.

PubMed

Yan, Caixia; Yang, Yi; Zhou, Junliang; Liu, Min; Nie, Minghua; Shi, Hao; Gu, Lijun

2013-04-01

The occurrence and distribution of five groups of antibiotics were investigated in the surface water of Yangtze Estuary over four seasons. Of the 20 antibiotics, only sulfamerazine was not detected at all sampling sites, indicating widespread occurrence of antibiotic residues in the study area. Detection frequencies and concentrations of antibiotics were generally higher in January, indicating that low flow conditions and low temperature might enhance the persistence of antibiotics in water. Antibiotic levels varied with location, with the highest concentrations being observed around river discharge and sewage outfall. Furthermore, a positive correlation between total antibiotic and DOC concentrations revealed the significant role played by DOC. Risk assessment based on single compound exposure showed that sulfapyridine and sulfamethoxazole could cause medium risk to daphnid in the Yangtze Estuary. Copyright © 2012 Elsevier Ltd. All rights reserved.

Identifying the underlying causes of biological instability in a full-scale drinking water supply system.

PubMed

Nescerecka, Alina; Juhna, Talis; Hammes, Frederik

2018-05-15

Changes in bacterial concentration and composition in drinking water during distribution are often attributed to biological (in)stability. Here we assessed temporal biological stability in a full-scale distribution network (DN) supplied with different types of source water: treated and chlorinated surface water and chlorinated groundwater produced at three water treatment plants (WTP). Monitoring was performed weekly during 12 months in two locations in the DN. Flow cytometric total and intact cell concentration (ICC) measurements showed considerable seasonal fluctuations, which were different for two locations. ICC varied between 0.1-3.75 × 10 5  cells mL -1 and 0.69-4.37 × 10 5  cells mL -1 at two locations respectively, with ICC increases attributed to temperature-dependent bacterial growth during distribution. Chlorinated water from the different WTP was further analysed with a modified growth potential method, identifying primary and secondary growth limiting compounds. It was observed that bacterial growth in the surface water sample after chlorination was primarily inhibited by phosphorus limitation and secondly by organic carbon limitation, while carbon was limiting in the chlorinated groundwater samples. However, the ratio of available nutrients changed during distribution, and together with disinfection residual decay, this resulted in higher bacterial growth potential detected in the DN than at the WTP. In this study, bacterial growth was found to be higher (i) at higher water temperatures, (ii) in samples with lower chlorine residuals and (iii) in samples with less nutrient (carbon, phosphorus, nitrogen, iron) limitation, while this was significantly different between the samples of different origin. Thus drinking water microbiological quality and biological stability could change during different seasons, and the extent of these changes depends on water temperature, the water source and treatment. Furthermore, differences in primary growth limiting nutrients in different water sources could contribute to biological instability in the network, where mixing occurs. Copyright © 2018 Elsevier Ltd. All rights reserved.

Total Water-Vapor Distribution in the Summer Cloudless Atmosphere over the South of Western Siberia

NASA Astrophysics Data System (ADS)

Troshkin, D. N.; Bezuglova, N. N.; Kabanov, M. V.; Pavlov, V. E.; Sokolov, K. I.; Sukovatov, K. Yu.

2017-12-01

The spatial distribution of the total water vapor in different climatic zones of the south of Western Siberia in summer of 2008-2011 is studied on the basis of Envisat data. The correlation analysis of the water-vapor time series from the Envisat data W and radiosonde observations w for the territory of Omsk aerological station show that the absolute values of W and w are linearly correlated with a coefficient of 0.77 (significance level p < 0.05). The distribution functions of the total water vapor are calculated based on the number of its measurements by Envisat for a cloudless sky of three zones with different physical properties of the underlying surface, in particular, steppes to the south of the Vasyugan Swamp and forests to the northeast of the Swamp. The distribution functions are bimodal; each mode follows the lognormal law. The parameters of these functions are given.

Temperature Distribution Measurement of The Wing Surface under Icing Conditions

NASA Astrophysics Data System (ADS)

Isokawa, Hiroshi; Miyazaki, Takeshi; Kimura, Shigeo; Sakaue, Hirotaka; Morita, Katsuaki; Japan Aerospace Exploration Agency Collaboration; Univ of Notre Dame Collaboration; Kanagawa Institute of Technology Collaboration; Univ of Electro-(UEC) Team, Comm

2016-11-01

De- or anti-icing system of an aircraft is necessary for a safe flight operation. Icing is a phenomenon which is caused by a collision of supercooled water frozen to an object. For the in-flight icing, it may cause a change in the wing cross section that causes stall, and in the worst case, the aircraft would fall. Therefore it is important to know the surface temperature of the wing for de- or anti-icing system. In aerospace field, temperature-sensitive paint (TSP) has been widely used for obtaining the surface temperature distribution on a testing article. The luminescent image from the TSP can be related to the temperature distribution. (TSP measurement system) In icing wind tunnel, we measured the surface temperature distribution of the wing model using the TSP measurement system. The effect of icing conditions on the TSP measurement system is discussed.

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.

Computer program for simulation of variable recharge with the U. S. Geological Survey modular finite-difference ground-water flow model (MODFLOW)

USGS Publications Warehouse

Kontis, A.L.

2001-01-01

The Variable-Recharge Package is a computerized method designed for use with the U.S. Geological Survey three-dimensional finitedifference ground-water flow model (MODFLOW-88) to simulate areal recharge to an aquifer. It is suitable for simulations of aquifers in which the relation between ground-water levels and land surface can affect the amount and distribution of recharge. The method is based on the premise that recharge to an aquifer cannot occur where the water level is at or above land surface. Consequently, recharge will vary spatially in simulations in which the Variable- Recharge Package is applied, if the water levels are sufficiently high. The input data required by the program for each model cell that can potentially receive recharge includes the average land-surface elevation and a quantity termed ?water available for recharge,? which is equal to precipitation minus evapotranspiration. The Variable-Recharge Package also can be used to simulate recharge to a valley-fill aquifer in which the valley fill and the adjoining uplands are explicitly simulated. Valley-fill aquifers, which are the most common type of aquifer in the glaciated northeastern United States, receive much of their recharge from upland sources as channeled and(or) unchanneled surface runoff and as lateral ground-water flow. Surface runoff in the uplands is generated in the model when the applied water available for recharge is rejected because simulated water levels are at or above land surface. The surface runoff can be distributed to other parts of the model by (1) applying the amount of the surface runoff that flows to upland streams (channeled runoff) to explicitly simulated streams that flow onto the valley floor, and(or) (2) applying the amount that flows downslope toward the valley- fill aquifer (unchanneled runoff) to specified model cells, typically those near the valley wall. An example model of an idealized valley- fill aquifer is presented to demonstrate application of the method and the type of information that can be derived from its use. Documentation of the Variable-Recharge Package is provided in the appendixes and includes listings of model code and of program variables. Comment statements in the program listings provide a narrative of the code. Input-data instructions and printed model output for the package are included.

Hydroclimatic regimes: a distributed water-balance framework for hydrologic assessment, classification, and management

USGS Publications Warehouse

Weiskel, Peter K.; Wolock, David M.; Zarriello, Phillip J.; Vogel, Richard M.; Levin, Sara B.; Lent, Robert M.

2014-01-01

Runoff-based indicators of terrestrial water availability are appropriate for humid regions, but have tended to limit our basic hydrologic understanding of drylands – the dry-subhumid, semiarid, and arid regions which presently cover nearly half of the global land surface. In response, we introduce an indicator framework that gives equal weight to humid and dryland regions, accounting fully for both vertical (precipitation + evapotranspiration) and horizontal (groundwater + surface-water) components of the hydrologic cycle in any given location – as well as fluxes into and out of landscape storage. We apply the framework to a diverse hydroclimatic region (the conterminous USA) using a distributed water-balance model consisting of 53 400 networked landscape hydrologic units. Our model simulations indicate that about 21% of the conterminous USA either generated no runoff or consumed runoff from upgradient sources on a mean-annual basis during the 20th century. Vertical fluxes exceeded horizontal fluxes across 76% of the conterminous area. Long-term-average total water availability (TWA) during the 20th century, defined here as the total influx to a landscape hydrologic unit from precipitation, groundwater, and surface water, varied spatially by about 400 000-fold, a range of variation ~100 times larger than that for mean-annual runoff across the same area. The framework includes but is not limited to classical, runoff-based approaches to water-resource assessment. It also incorporates and reinterprets the green- and blue-water perspective now gaining international acceptance. Implications of the new framework for several areas of contemporary hydrology are explored, and the data requirements of the approach are discussed in relation to the increasing availability of gridded global climate, land-surface, and hydrologic data sets.

Analysis of the In-Water and Sky Radiance Distribution Data Acquired During the Radyo Project

DTIC Science & Technology

2013-09-30

radiative transfer to model the BRDF of particulate surfaces. OBJECTIVES The major objective of this research is to understand the downwelling...of image and radiative transfer models used in the ocean. My near term ocean optics objectives have been: 1) to improve the measurement capability...directional Reflectance Distribution Function ( BRDF ) of benthic surfaces in the ocean, and 4) to understand the capabilities and limitations of using

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

Not Available

The following appendices to volume I are presented: biomass of dominant microzooplankton; biomass of zooplankton in surface waters of Jobos Bay; comparison of zooplankton caught during day and night; variations in surface temperature and salinity at collection sites; distance, depth, and temperature related to dominant vegetation and sea grass; total biomass of Thalassia testudium; photosynthetic pigment diversity; invertebrate species and frequency of occurrence; distribution of macrobenthic organisms; species found on mangrove roots; distribution of fish species; and seasonal occurrence of fish species. (HLW)

Potentiometric Surface of the Ozark Aquifer in Northern Arkansas, 2007

USGS Publications Warehouse

Pugh, Aaron L.

2008-01-01

The Ozark aquifer in northern Arkansas is composed of dolomite, limestone, sandstone, and shale of Late Cambrian to Middle Devonian age, and ranges in thickness from approximately 1,100 feet to more than 4,000 feet. Hydrologically, the aquifer is complex, characterized by discrete and discontinuous flow components with large variations in permeability. The potentiometric-surface map, based on 58 well and 5 spring water-level measurements collected in 2007 in Arkansas and Missouri, has a maximum water-level altitude measurement of 1,169 feet in Carroll County and a minimum water-level altitude measurement of 118 feet in Randolph County. Regionally, the flow within the aquifer is to the south and southeast in the eastern and central part of the study area and to the west, northwest, and north in the western part of the study area. Comparing the 2007 potentiometric-surface map with a predevelopment potentiometric-surface map indicates general agreement between the two surfaces except in the northwestern part of the study area. Potentiometric-surface differences can be attributed to withdrawals related to increasing population, changes in public-supply sources, processes or water withdrawals outside the study area, or differences in data-collection or map-construction methods. The rapidly increasing population within the study area appears to have some effect on ground-water levels. Although, the effect appears to have been minimized by the development and use of surface-water distribution infrastructure, suggesting most of the incoming populations are fulfilling their water needs from surface-water sources. The conversion of some users from ground water to surface water may be allowing water levels in wells to recover (rise) or decline at a slower rate, such as in Benton, Carroll, and Washington Counties.

Distributions and Changes of Carbonate Parameters Along the U.S. East Coast

NASA Astrophysics Data System (ADS)

Xu, Y. Y.; Cai, W. J.; Wanninkhof, R. H.; Salisbury, J., II

2017-12-01

On top of anthropogenic climate change, upwelling, eutrophication, river discharge, and interactions with the open ocean have affected carbonate chemistry in coastal waters. In this study, we present the large-scale variations of carbonate parameters along the U.S. east coast using in situ observations obtained during an East Coast Ocean Acidification (ECOA) cruise in summer 2015. Compare with previous large-scale cruises along the east coast, the ECOA cruise increases spatial coverage in the Gulf of Marine region and has more offshore stations for a better understanding of carbon dynamics in coastal waters and their interactions with open ocean waters. Our results show that the spatial distribution of water mass properties set up the large-scale advection of salt and heat and the distribution of total alkalinity (TA). However, dissolved inorganic carbon (DIC) shows a distinct pattern. Coastal water pH displays high variability in the Gulf of Maine and the Mid-Atlantic Bight (MAB). But it is relatively homogeneous in the South Atlantic Bight (SAB). In contrast, the distribution of aragonite saturation state (Ω) has an increase pattern from north to south similar to those of TA, SST, and SSS. A mechanistic discussion will be presented to understand the controls on Ω in eastern coastal waters. A comparison with previous cruises also suggests very different changes of pH and Ω in the MAB and SAB. Preliminary analysis suggests an overall increase in surface pH and Ω in the MAB. In contrast, pH and Ω in the SAB surface waters decrease over the past two decades. This work serves as a platform for the monitoring of large-scale carbon cycling in the U.S. east coast. It is also important to identify the physical and biogeochemical processes that affect these distributions and changes over time for a better understanding of carbon cycling and ocean acidification in coastal waters.

Distribution of Vibrio alginolyticus-like species in Shenzhen coastal waters, China

PubMed Central

Chen, Ming-Xia; Li, He-Yang; Li, Gang; Zheng, Tian-Ling

2011-01-01

We investigated the distribution of vibrios in Shenzhen coastal waters in order to obtain valuable information for the aquaculture industry and a health warning system. Quantities of vibrios from surface waters ranged from 0 to 4.40×104 CFUs mL-1 in April (spring), while from 0 to 2.57×103 CFUs mL-1 in September (autumn); the abundance of V. alginolyticus-like species from surface water ranged from 0 to 6.72×103 CFUs mL-1 in April (spring) and from 0 to 1.28×103 CFUs mL-1 in September (autumn); higher counts were observed in spring. The V. alginolyticus-like species was dominant in Shenzhen coastal waters, with the highest abundance in the clean region (stations YMK001 and GDN064) in April, suggesting that Vibrio spp. were naturally occurring bacteria in marine environments. The correlation between the abundance of vibrios (including V. alginolyticus-like species) and environmental factors varied in different regions and different seasons. There were no vibrios detected when the salinity was less than 11.15‰ in the Zhujiang River estuary, which indicated that salinity played a key role in the distribution of vibrios and V. alginolyticus-like species. PMID:24031704

THE EVOLUTION OF SYNTHETICALLY PRECIPITATED COPPER SOLIDS

EPA Science Inventory

The objective of this study was to explore the effect of water quality, particularly chloride and sulfate, on copper mineral formation. Copper-sulfate and chloride compounds are often found on the surface of copper pipes in drinking water distribution systems. When attempting to ...

ISOTOPIC EVIDENCE FOR NATURALLY OCCURRING SULFATE PONDS IN THE KANKAKEE RIVER BASIN, ILLINOIS-INDIANA

EPA Science Inventory

Design of constructed wetlands in the Kankakee watershed, Indiana, include pumping and distribution ditches leaving former channelized river levees intact. Resultant changes in shallow ground water - surface water interactions may be contributing elevated sulfate to wetland ponds...

Modern benthic foraminifer distribution in the Amerasian Basin, Arctic Ocean

USGS Publications Warehouse

Ishman, S.E.; Foley, K.M.

1996-01-01

A total of 38 box cores were collected from the Amerasian Basin, Arctic Ocean during the U.S. Geological Survey 1992 (PI92-AR) and 1993 (PI93-AR) Arctic Cruises aboard the U.S. Coast Guard Icebreaker Polar Star. In addition, the cruises collected geophysical data, piston cores and hydrographic data to address the geologic and oceanographic history of the western Arctic Ocean. This paper reports the results of the quantitative analyses of benthic foraminifer distribution data of the total (live + dead) assemblages derived from 22 box core-top samples. The results show that a distinct depth distribution of three dominant benthic foraminifer assemblages, the Textularia spp. - Spiroplectammina biformis, Cassidulina teretis and Oridorsalis tener - Eponides tumidulus Biofacies are strongly controlled by the dominant water masses within the Canada Basin: the Arctic Surface Water, Arctic Intermediate Water and Canada Basin Deep Water. The faunal distributions and their oceanographic associations in the Canada Basin are consistent with observations of benthic foraminifer distributions from other regions within the Arctic Ocean.

Pharmaceuticals as indictors of sewage-influenced groundwater

NASA Astrophysics Data System (ADS)

Müller, Beate; Scheytt, Traugott; Asbrand, Martin; de Casas, Andrea Mross

2012-09-01

A set of human pharmaceuticals enables identification of groundwater that is influenced by sewage and provides information on the time of recharge. As the consumption rates of the investigated pharmaceuticals have changed over time, so too has the composition of the sewage. At the study area, south of Berlin (Germany), irrigation was performed as a method of wastewater clean-up at sewage irrigation farms until the early 1990s. Today, treated wastewater is discharged into the surface-water-stream Nuthegraben. Groundwater and surface-water samples were analyzed for the pharmaceutical substances clofibric acid, bezafibrate, diclofenac, carbamazepine and primidone, the main ions and organic carbon. The pharmaceutical substances were detected at concentrations up to microgram-per-liter level in groundwater and surface-water samples from the Nuthegraben Lowland area and from the former irrigation farms. Concentrations detected in groundwater are generally much lower than in surface water and there is significant variation in the distribution of pharmaceutical concentrations in groundwater. Groundwater influenced by the irrigation of sewage water shows higher primidone and clofibric-acid concentrations. Groundwater influenced by recent discharge of treated sewage water into the surface water shows high carbamazepine concentrations while concentrations of primidone and clofibric acid are low.

Studies of a subarctic coastal marsh. III. Modelling the subsurface water fluxes and chloride distribution

NASA Astrophysics Data System (ADS)

Price, Jonathan S.; Woo, Ming-Ko

1990-12-01

A two-dimensional advection dispersion model of solute transport is used to simulate the long-term changes in the chloride distribution of the young isostatically raised beach ridge and depression sequences in a James Bay coastal marsh. The USGS-SUTRA model reproduces the hydraulic conditions in the wetland, causing recharge of freshwater to the ridges and discharge of saline water to the inter-ridge depressions, demonstrating the importance of vertical water fluxes of water and chloride. Even though water velocities are very low, molecular diffusion alone cannot explain the observed chloride distribution. Imposing the characteristics of a frozen surface during winter eliminated the vertical fluxes, and doubled the time required for the simulated chloride distribution to match the field data. The model correctly predicts the observed pattern of suppressed salinity beneath the ridges and a general decrease of salinity with distance inland. The results are useful in understanding the processes which operate in the first 100 years of marsh development.

Diurnal vertical migration of Cochlodinium polykrikoides during the red tide in Korean coastal sea waters.

PubMed

Kim, Young Sug; Jeong, Chang Su; Seong, Gi Tak; Han, In Sung; Lee, Young Sik

2010-09-01

The diurnal vertical migration of Cochlodinium polykrikoides (C. polykrikoides), which caused a red tide in the Korean coastal waters of the East Sea/Sea of Japan in September 2003, was examined by determining the time-dependent changes in the density of living cells in relation to the depth of the water column. The ascent of this species into the surface layer (depth of water 2 m) occurred during 1400-1500. The descent started at 1600 and a high distribution rate (86%) at 15-20 m was observed at 0300. During the ascent, the cells were widely distributed at each depth level from 0600 hr and at 0800-1100, the cells were primarily distributed in the middle layer (0-6 m). The concentration of dissolved inorganic nitrogen was generally < or = 2.86 micromol l(-1), but at 1400-1500, the concentration in the surface layer reduced to < or = 0.14 micromol l(-1). Moreover, the concentration gradually increased as the depth increased to > or = 5 m. These results showed that the nutrient-consumption rate associated with the proliferation of C. polykrikoides during a red tide is more influenced by the inorganic-nitrogen resources ratherthan the inorganic-phosphorus compounds.

Analysis of water surface and flow distribution for the design flood at a proposed highway crossing of the Sabine River near Tatum, Texas

USGS Publications Warehouse

Gilbert, J.J.; Myers, D.R.

1989-01-01

The simulations of the proposed and alternate designs indicate a lateral component of the water-surface slope at the embankment. Redistribution of flow across the floodplain also is indicated in both simulations. Some of the differences in the response between the two designs are affected by geometric features of the floodplain other than the embankment-opening geometry.

The Nature of The Propagation of Sea Breeze Fronts in Central California

DTIC Science & Technology

1990-09-01

propagation vector % ith stations in the southern portion of Monterey Bay shows that the front is curved on the mesoscale. 20 Distribution Availabilit of...solar radiation warms the land more than the adjacent water . The resulting temperature contrast produces a slight variation in pressure. The isobaric...surfaces bend upward over the land, producing an upper-level high. The upper-level air flows seaward increasing the surface pressure over the water . The

An easy and environmentally-friendly approach to superamphiphobicity of aluminum surfaces

NASA Astrophysics Data System (ADS)

Deng, R.; Hu, Y. M.; Wang, L.; Li, Zh. H.; Shen, T.; Zhu, Y.; Xiang, J. Zh.

2017-04-01

Superamphiphobic Al surfaces were achieved via an easy and environmentally-friendly approach. Aqueous mixed solution of 0.7 M CuSO4 and 1 M NaCl was used to etch polished Al surfaces to fabricate a rough morphology distributed with microscale step-like pits. The uniformly distributed nanoscale petals covered on the microscale pits were obtained by subsequent 96 °C hot deionized water bathing for 13 min. Thus, the hierarchical micro/nanometer scale roughness was formed which provided the structural basic of superamphiphobic Al surfaces. By 1H, 1H, 2H, 2H-Perfluorodecyl-triethoxysilane (PFDTS) derivatization, desirable superamphiphobic Al surfaces were achieved with the highest static contact angles of 162° for water, 156° for peanut oil, respectively. Meanwhile, the sliding angles were lower than 10° for both water and peanut oil droplets. The as-prepared Al surfaces were investigated by field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and optical contact angle measurements. The FE-SEM images of as-prepared Al surfaces showed a hierarchical micro/nanometer scale morphology. XPS analyses demonstrated the PFDTS derivitization on Al surfaces. The superamphiphobic Al surfaces presented good mechanical durability and chemical stability which have a wide range of applications in fields such as self-cleaning, anti-icing, anti-corrosion, oil transportation, energy harvesting, microfluidics, and so forth. The approach reported in this paper may easily realize the industrial production of superamphiphobic Al surfaces owing to the advantage of facile, low cost and environmentally-friendly.

Rare earth element distributions in the West Pacific: Trace element sources and conservative vs. non-conservative behavior

NASA Astrophysics Data System (ADS)

Behrens, Melanie K.; Pahnke, Katharina; Paffrath, Ronja; Schnetger, Bernhard; Brumsack, Hans-Jürgen

2018-03-01

Recent studies suggest that transport and water mass mixing may play a dominant role in controlling the distribution of dissolved rare earth element concentrations ([REE]) at least in parts of the North and South Atlantic and the Pacific Southern Ocean. Here we report vertically and spatially high-resolution profiles of dissolved REE concentrations ([REE]) along a NW-SE transect in the West Pacific and examine the processes affecting the [REE] distributions in this area. Surface water REE patterns reveal sources of trace element (TE) input near South Korea and in the tropical equatorial West Pacific. Positive europium anomalies and middle REE enrichments in surface and subsurface waters are indicative of TE input from volcanic islands and fingerprint in detail small-scale equatorial zonal eastward transport of TEs to the iron-limited tropical East Pacific. The low [REE] of North and South Pacific Tropical Waters and Antarctic Intermediate Water are a long-range (i.e., preformed) laterally advected signal, whereas increasing [REE] with depth within North Pacific Intermediate Water result from release from particles. Optimum multiparameter analysis of deep to bottom waters indicates a dominant control of lateral transport and mixing on [REE] at the depth of Lower Circumpolar Deep Water (≥3000 m water depth; ∼75-100% explained by water mass mixing), allowing the northward tracing of LCDW to ∼28°N in the Northwest Pacific. In contrast, scavenging in the hydrothermal plumes of the Lau Basin and Tonga-Fiji area at 1500-2000 m water depth leads to [REE] deficits (∼40-60% removal) and marked REE fractionation in the tropical West Pacific. Overall, our data provide evidence for active trace element input both near South Korea and Papua New Guinea, and for a strong lateral transport component in the distribution of dissolved REEs in large parts of the West Pacific.

Effect of Surface Oxidation on Interfacial Water Structure at a Pyrite (100) Surface as Studied by Molecular Dynamics Simulation

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

Jin, Jiaqi; Miller, Jan D.; Dang, Liem X.

2015-06-01

In the first part of this paper, a Scanning Electron Microscopy and contact angle study of a pyrite surface (100) is reported describing the relationship between surface oxidation and the hydrophilic surface state. In addition to these experimental results, the following simulated surface states were examined using Molecular Dynamics Simulation (MDS): fresh unoxidized (100) surface; polysulfide at the (100) surface; elemental sulfur at the (100) surface. Crystal structures for the polysulfide and elemental sulfur at the (100) surface were simulated using Density Functional Theory (DFT) quantum chemical calculations. The well known oxidation mechanism which involves formation of a metal deficientmore » layer was also described with DFT. Our MDS results of the behavior of interfacial water at the fresh and oxidized pyrite (100) surfaces without/with the presence of ferric hydroxide include simulated contact angles, number density distribution for water, water dipole orientation, water residence time, and hydrogen-bonding considerations. The significance of the formation of ferric hydroxide islands in accounting for the corresponding hydrophilic surface state is revealed not only from experimental contact angle measurements but also from simulated contact angle measurements using MDS. The hydrophilic surface state developed at oxidized pyrite surfaces has been described by MDS, on which basis the surface state is explained based on interfacial water structure. The Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences (BES), of the DOE funded work performed by Liem X. Dang. Battelle operates the Pacific Northwest National Laboratory for DOE. The calculations were carried out using computer resources provided by BES.« less

Adsorption and solvation of ethanol at the water liquid-vapor interface: a molecular dynamics study

NASA Technical Reports Server (NTRS)

Wilson, M. A.; Pohorille, A.

1997-01-01

The free energy profiles of methanol and ethanol at the water liquid-vapor interface at 310K were calculated using molecular dynamics computer simulations. Both alcohols exhibit a pronounced free energy minimum at the interface and, therefore, have positive adsorption at this interface. The surface excess was computed from the Gibbs adsorption isotherm and was found to be in good agreement with experimental results. Neither compound exhibits a free energy barrier between the bulk and the surface adsorbed state. Scattering calculations of ethanol molecules from a gas phase thermal distribution indicate that the mass accommodation coefficient is 0.98, and the molecules become thermalized within 10 ps of striking the interface. It was determined that the formation of the solvation structure around the ethanol molecule at the interface is not the rate-determining step in its uptake into water droplets. The motion of an ethanol molecule in a water lamella was followed for 30 ns. The time evolution of the probability distribution of finding an ethanol molecule that was initially located at the interface is very well described by the diffusion equation on the free energy surface.

A new perspective on origin of the East Sea Intermediate Water: Observations of Argo floats

NASA Astrophysics Data System (ADS)

Park, JongJin; Lim, Byunghwan

2018-01-01

The East Sea Intermediate Water (ESIW), defined as the salinity minimum in the East Sea (hereafter ES) (Sea of Japan), is examined with respect to its overall characteristics and its low salinity origin using historical Argo float data from 1999 to 2015. Our findings suggest that the ESIW is formed in the western Japan Basin (40-42°N, 130-133°E), especially west of the North Korean front in North Korean waters, where strong negative surface wind stress curl resides in wintertime. The core ESIW near the formation site has temperatures of 3-4 °C and less than 33.98 psu salinity, warmer and fresher than that in the southern part of the ES. In order to trace the origin of the warmer and fresher water at the sea surface in winter, we analyzed the data in three different ways: (1) spatial distribution of surface water properties using monthly climatology from the Argo float data, (2) seasonal variation of heat and salt contents at the formation site, and (3) backtracking of surface drifter trajectories. Based on these analyses, it is likely that the warmer and fresher surface water properties found in the ESIW formation site are attributed to the low-salinity surface water advected from the southern part of the ES in autumn.

Calculation of distribution coefficients in the SAMPL5 challenge from atomic solvation parameters and surface areas.

PubMed

Santos-Martins, Diogo; Fernandes, Pedro Alexandrino; Ramos, Maria João

2016-11-01

In the context of SAMPL5, we submitted blind predictions of the cyclohexane/water distribution coefficient (D) for a series of 53 drug-like molecules. Our method is purely empirical and based on the additive contribution of each solute atom to the free energy of solvation in water and in cyclohexane. The contribution of each atom depends on the atom type and on the exposed surface area. Comparatively to similar methods in the literature, we used a very small set of atomic parameters: only 10 for solvation in water and 1 for solvation in cyclohexane. As a result, the method is protected from overfitting and the error in the blind predictions could be reasonably estimated. Moreover, this approach is fast: it takes only 0.5 s to predict the distribution coefficient for all 53 SAMPL5 compounds, allowing its application in virtual screening campaigns. The performance of our approach (submission 49) is modest but satisfactory in view of its efficiency: the root mean square error (RMSE) was 3.3 log D units for the 53 compounds, while the RMSE of the best performing method (using COSMO-RS) was 2.1 (submission 16). Our method is implemented as a Python script available at https://github.com/diogomart/SAMPL5-DC-surface-empirical .

Depth distribution of benthic dinoflagellates in the Caribbean Sea

NASA Astrophysics Data System (ADS)

Boisnoir, Aurélie; Pascal, Pierre-Yves; Cordonnier, Sébastien; Lemée, Rodolophe

2018-05-01

Monitoring of benthic dinoflagellates is usually conducted between sub-surface and 5 m depth, where these organisms are supposed to be in highest abundances. However, only few studies have focused on the small-scale depth distribution of benthic dinoflagellates. In the present study, abundances of dinoflagellates were evaluated on an invasive macrophyte Halophila stipulacea in two coastal sites in Guadeloupe (Caribbean Sea) along a depth gradient from sub-surface to 3 m at Gosier and until 20 m at Rivière Sens during the tropical wet and dry seasons. Species of genus Ostreopsis and Prorocentrum were the most abundant. Depth did not influence total dinoflagellate abundance but several genera showed particular depth-distribution preferences. The highest abundances of Ostreopsis and Gambierdiscus species were estimated preferentially in surface waters, whereas Coolia spp. were found in the same proportions but in deeper waters. Halophila stipulacea biomass was positively correlated with Ostreopsis spp. abundance. Our study suggests that sampling of benthic dinoflagellates should be conducted at different water depths taking into account the presence of the macroalgal substrate as well. In the Caribbean area, special attention should be addressed to the presence of H. stipulacea which tends to homogenize the marine landscape and represents a substrate for hosting dinoflagellate growth.

Polyethylene oxide hydration in grafted layers

NASA Astrophysics Data System (ADS)

Dormidontova, Elena; Wang, Zilu

Hydration of water soluble polymers is one of the key-factors defining their conformation and properties, similar to biopolymers. Polyethylene oxide (PEO) is one of the most important biomedical-applications polymers and is known for its reverse temperature solubility due to hydrogen bonding with water. As in many practical applications PEO chains are grafted to surfaces, e.g. of nanoparticles or planar surfaces, it is important to understand PEO hydration in such grafted layers. Using atomistic molecular dynamic simulations we investigate the details of molecular conformation and hydration of PEO end-grafted to gold surfaces. We analyze polymer and water density distribution as a function of distance from the surface for different grafting densities. Based on a detailed analysis of hydrogen bonding between polymer and water in grafted PEO layers, we will discuss the extent of PEO hydration and its implication for polymer conformation, mobility and layer properties. This research is supported by NSF (DMR-1410928).

Comparison of Euphausia superba, Euphausia crystallorophias, Pleuragramma antarcticum and Environmental Distributions in the Western Ross Sea

NASA Astrophysics Data System (ADS)

Davis, L.; Hofmann, E. E.; Klinck, J. M., II; Dinniman, M.; Pinones, M. A.

2016-02-01

Distributions of Antarctic krill (Euphausia superba), crystal krill (Euphausia crystallorophias), and Antarctic silverfish (Pleuragramma antarcticum) were constructed using observations collected in the western Ross Sea from 1988-2004. Distributions of mixed layer depth (MLD), water temperature below 200 m (an indicator for Circumpolar Deep Water, CDW), and surface speed were obtained from a Ross Sea circulation model; surface chlorophyll and percent sea ice coverage were obtained from satellite observations. The species and environmental distributions were analyzed to determine patterns and correlations. Statistical analyses of the distributions show that the three species are concentrated in specific regions and that their habitats have limited overlap. Antarctic krill are concentrated along the shelf break near Cape Adare and are associated with temperatures >0.5°C and -2°C to -0.75°C, 19-32% sea ice coverage, and high surface flow speeds. Crystal krill are concentrated in Terra Nova Bay in areas with depths of 400-600 m, temperatures < -1.3°, 50% or more sea ice coverage, shallow MLDs (2-36 m), moderate concentrations of chlorophyll (0.44 μg m-3) and low surface speeds (0.08 m s-1). Similarly, Antarctic silverfish are concentrated in Terra Nova Bay and are also found over the continental shelf in areas with depths of 500 m and temperatures of -2°C to -1°C. Additional statistical analyses provide insights into the relative contribution of the different environmental features to producing the distributions of the three species.

Shift in the microbial community composition of surface water and sediment along an urban river.

PubMed

Wang, Lan; Zhang, Jing; Li, Huilin; Yang, Hong; Peng, Chao; Peng, Zhengsong; Lu, Lu

2018-06-15

Urban rivers represent a unique ecosystem in which pollution occurs regularly, leading to significantly altered of chemical and biological characteristics of the surface water and sediments. However, the impact of urbanization on the diversity and structure of the river microbial community has not been well documented. As a major tributary of the Yangtze River, the Jialing River flows through many cities. Here, a comprehensive analysis of the spatial microbial distribution in the surface water and sediments in the Nanchong section of Jialing River and its two urban branches was conducted using 16S rRNA gene-based Illumina MiSeq sequencing. The results revealed distinct differences in surface water bacterial composition along the river with a differential distribution of Proteobacteria, Cyanobacteria, Actinobacteria, Bacteroidetes and Acidobacteria (P < 0.05). The bacterial diversity in sediments was significantly higher than their corresponding water samples. Additionally, archaeal communities showed obvious spatial variability in the surface water. The construction of the hydropower station resulted in increased Cyanobacteria abundance in the upstream (32.2%) compared to its downstream (10.3%). Several taxonomic groups of potential fecal indicator bacteria, like Flavobacteria and Bacteroidia, showed an increasing trend in the urban water. PICRUSt metabolic inference analysis revealed a growing number of genes associated with xenobiotic metabolism and nitrogen metabolism in the urban water, indicating that urban discharges might act as the dominant selective force to alter the microbial communities. Redundancy analysis suggested that the microbial community structure was influenced by several environmental factors. TP (P < 0.01) and NO 3 - (P < 0.05), and metals (Zn, Fe) (P < 0.05) were the most significant drivers determining the microbial community composition in the urban river. These results highlight that river microbial communities exhibit spatial variation in urban areas due to the joint influence of chemical variables associated with sewage discharging and construction of hydropower stations. Copyright © 2018 Elsevier B.V. All rights reserved.

Quality of volatile organic compound data from groundwater and surface water for the National Water-Quality Assessment Program, October 1996–December 2008

USGS Publications Warehouse

Bender, David A.; Zogorski, John S.; Mueller, David K.; Rose, Donna L.; Martin, Jeffrey D.; Brenner, Cassandra K.

2011-01-01

This report describes the quality of volatile organic compound (VOC) data collected from October 1996 to December 2008 from groundwater and surface-water sites for the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program. The VOC data described were collected for three NAWQA site types: (1) domestic and public-supply wells, (2) monitoring wells, and (3) surface-water sites. Contamination bias, based on the 90-percent upper confidence limit (UCL) for the 90th percentile of concentrations in field blanks, was determined for VOC samples from the three site types. A way to express this bias is that there is 90-percent confidence that this amount of contamination would be exceeded in no more than 10 percent of all samples (including environmental samples) that were collected, processed, shipped, and analyzed in the same manner as the blank samples. This report also describes how important native water rinsing may be in decreasing carryover contamination, which could be affecting field blanks. The VOCs can be classified into four contamination categories on the basis of the 90-percent upper confidence limit (90-percent UCL) concentration distribution in field blanks. Contamination category 1 includes compounds that were not detected in any field blanks. Contamination category 2 includes VOCs that have a 90-percent UCL concentration distribution in field blanks that is about an order of magnitude lower than the concentration distribution of the environmental samples. Contamination category 3 includes VOCs that have a 90-percent UCL concentration distribution in field blanks that is within an order of magnitude of the distribution in environmental samples. Contamination category 4 includes VOCs that have a 90-percent UCL concentration distribution in field blanks that is at least an order of magnitude larger than the concentration distribution of the environmental samples. Fifty-four of the 87 VOCs analyzed in samples from domestic and public-supply wells were not detected in field blanks (contamination category 1), and 33 VOC were detected in field blanks. Ten of the 33 VOCs had a 90-percent UCL concentration distribution in field blanks that was at least an order of magnitude lower than the concentration distribution in environmental samples (contamination category 2). These 10 VOCs may have had some contamination bias associated with the environmental samples, but the potential contamination bias was negligible in comparison to the environmental data; therefore, the field blanks were assumed to be representative of the sources of contamination bias affecting the environmental samples for these 10 VOCs. Seven VOCs had a 90-percent UCL concentration distribution of the field blanks that was within an order of magnitude of the concentration distribution of the environmental samples (contamination category 3). Sixteen VOCs had a 90-percent UCL concentration distribution in the field blanks that was at least an order of magnitude greater than the concentration distribution of the environmental samples (contamination category 4). Field blanks for these 16 VOCs appear to be nonrepresentative of the sources of contamination bias affecting the environmental samples because of the larger concentration distributions (and sometimes higher frequency of detection) in field blanks than in environmental samples. Forty-three of the 87 VOCs analyzed in samples from monitoring wells were not detected in field blanks (contamination category 1), and 44 VOCs were detected in field blanks. Eight of the 44 VOCs had a 90-percent UCL concentration distribution in field blanks that was at least an order of magnitude lower than concentrations in environmental samples (contamination category 2). These eight VOCs may have had some contamination bias associated with the environmental samples, but the potential contamination bias was negligible in comparison to the environmental data; therefore, the field blanks were assumed to be representative. Seven VOCs had a 90-percent UCL concentration distribution in field blanks that was of the same order of magnitude as the concentration distribution of the environmental samples (contamination category 3). Twenty-nine VOCs had a 90-percent UCL concentration distribution in the field blanks that was an order of magnitude greater than the distribution of the environmental samples (contamination category 4). Field blanks for these 29 VOCs appear to be nonrepresentative of the sources of contamination bias to the environmental samples. Fifty-four of the 87 VOCs analyzed in surface-water samples were not detected in field blanks (category 1), and 33 VOC were detected in field blanks. Sixteen of the 33 VOCs had a 90-percent UCL concentration distribution in field blanks that was at least an order of magnitude lower than the concentration distribution in environmental samples (contamination category 2). These 16 VOCs may have had some contamination bias associated with the environmental samples, but the potential contamination bias was negligible in comparison to the environmental data; therefore, the field blanks were assumed to be representative. Ten VOCs had a 90-percent UCL concentration distribution in field blanks that was similar to the concentration distribution of environmental samples (contamination category 3). Seven VOCs had a 90-percent UCL concentration distribution in the field blanks that was greater than the concentration distribution in environmental samples (contamination category 4). Field-blank samples for these seven VOCs appear to be nonrepresentative of the sources of contamination bias to the environmental samples. The relation between the detection of a compound in field blanks and the detection in subsequent environmental samples appears to be minimal. The median minimum percent effectiveness of native water rinsing is about 79 percent for the 19 VOCs detected in more than 5 percent of field blanks from all three site types. The minimum percent effectiveness of native water rinsing (10 percent) was for toluene in surface-water samples, likely because of the large detection frequency of toluene in surface-water samples (about 79 percent) and in the associated field-blank samples (46.5 percent). The VOCs that were not detected in field blanks (contamination category 1) from the three site types can be considered free of contamination bias, and various interpretations for environmental samples, such as VOC detection frequency at multiple assessment levels and comparisons of concentrations to benchmarks, are not limited for these VOCs. A censoring level for making comparisons at different assessment levels among environmental samples could be applied to concentrations of 9 VOCs in samples from domestic and public-supply wells, 16 VOCs in samples from monitoring wells, and 9 VOCs in surface-water samples to account for potential low-level contamination bias associated with these selected VOCs. Bracketing the potential contamination by comparing the detection and concentration statistics with no censoring applied to the potential for contamination bias on the basis of the 90-percent UCL for the 90th-percentile concentrations in field blanks may be useful when comparisons to benchmarks are done in a study. The VOCs that were not detected in field blanks (contamination category 1) from the three site types can be considered free of contamination bias, and various interpretations for environmental samples, such as VOC detection frequency at multiple assessment levels and comparisons of concentrations to benchmarks, are not limited for these VOCs. A censoring level for making comparisons at different assessment levels among environmental samples could be applied to concentrations of 9 VOCs in samples from domestic and public-supply wells, 16 VOCs in samples from monitoring wells, and 9 VOCs in surface-water samples to account for potential low-level contamination bias associated with these selected VOCs. Bracketing the potential contamination by comparing the detection and concentration statistics with no censoring applied to the potential for contamination bias on the basis of the 90-percent UCL for the 90th-percentile concentrations in field blanks may be useful when comparisons to benchmarks are done in a study.

Exploring the differences of antibiotic resistance genes profiles between river surface water and sediments using metagenomic approach.

PubMed

Jiang, Haoyu; Zhou, Renjun; Zhang, Mengdi; Cheng, Zhineng; Li, Jun; Zhang, Gan; Chen, Baowei; Zou, Shichun; Yang, Ying

2018-05-30

To better understand the potential genic communication and dissemination of antibiotic resistance genes (ARGs) in different environmental matrices, the differences of ARG profiles between river surface water and sediments were explored. Metagenomic analysis was applied to investigate the comprehensive ARG profiles in water and sediment samples collected from the highly human-impacted catchment of the Beijiang River and its river source. A total of 135 ARG subtypes belonging to 18 ARG types were identified. Generally, ARGs in surface water were more diverse and abundant than those in sediments. ARG profiles in the surface water and sediment samples were distinct from each other, but some ARGs were shared by the surface water and sediments. Results revealed that multidrug and bacitracin resistance genes were the predominant ARGs types in both surface water (0.30, 0.17 copies/cell) and sediments (0.19, 0.15 copies/cell). 73 ARG subtypes were shared by the water and sediment samples and had taken over 90% of the total detected ARG abundance. Most of the shared ARGs are resistant to the clinically relevant antibiotics. Furthermore, significant correlations between the ARGs and 21 shared genera or mobile genetic elements (MGEs) (plasmids and integrons) were found in surface water and sediments, suggesting the important role of genera or MGEs in shaping ARGs profiles, propagation and distribution. These findings provide deeper insight into mitigating the propagation of ARGs and the associated risks to public health. Copyright © 2018 Elsevier Inc. All rights reserved.

Soil-soil solution distribution coefficient of soil organic matter is a key factor for that of radioiodide in surface and subsurface soils.

PubMed

Unno, Yusuke; Tsukada, Hirofumi; Takeda, Akira; Takaku, Yuichi; Hisamatsu, Shun'ichi

2017-04-01

We investigated the vertical distribution of the soil-soil-solution distribution coefficients (K d ) of 125 I, 137 Cs, and 85 Sr in organic-rich surface soil and organic-poor subsurface soil of a pasture and an urban forest near a spent-nuclear-fuel reprocessing plant in Rokkasho, Japan. K d of 137 Cs was highly correlated with water-extractable K + . K d of 85 Sr was highly correlated with water-extractable Ca 2+ and SOC. K d of 125 I - was low in organic-rich surface soil, high slightly below the surface, and lowest in the deepest soil. This kinked distribution pattern differed from the gradual decrease of the other radionuclides. The thickness of the high- 125 I - K d middle layer (i.e., with high radioiodide retention ability) differed between sites. K d of 125 I - was significantly correlated with K d of soil organic carbon. Our results also showed that the layer thickness is controlled by the ratio of K d -OC between surface and subsurface soils. This finding suggests that the addition of SOC might prevent further radioiodide migration down the soil profile. As far as we know, this is the first report to show a strong correlation of a soil characteristic with K d of 125 I - . Further study is needed to clarify how radioiodide is retained and migrates in soil. Copyright © 2017 Elsevier Ltd. All rights reserved.

Ground-water quality in the Santa Rita, Buellton, and Los Olivos hydrologic subareas of the Santa Ynez River basin, Santa Barbara County, California

USGS Publications Warehouse

Hamlin, S.N.

1985-01-01

Groundwater quality in the upper Santa Ynez River Valley in Santa Barbara County has degraded due to both natural and anthropogenic causes. The semiarid climate and uneven distribution of rainfall has limited freshwater recharge and caused salt buildup in water supplies. Tertiary rocks supply mineralized water. Agricultural activities (irrigation return flow containing fertilizers and pesticides, cultivation, feedlot waste disposal) are a primary cause of water quality degradation. Urban development, which also causes water quality degradation (introduced contaminants, wastewater disposal, septic system discharge, and land fill disposal of waste), has imposed stricter requirements on water supply quality. A well network was designed to monitor changes in groundwater quality related to anthropogenic activities. Information from this network may aid in efficient management of the groundwater basins as public water supplies, centered around three basic goals. First is to increase freshwater recharge to the basins by conjunctive surface/groundwater use and surface-spreading techniques. Second is to optimize groundwater discharge by efficient timing and spacing of pumping. Third is to control and reduce sources of groundwater contamination by regulating wastewater quality and distribution and, preferably, by exporting wastewaters from the basin. (USGS)

Impact of plunging breaking waves on a partially submerged cube

NASA Astrophysics Data System (ADS)

Wang, A.; Ikeda, C.; Duncan, J. H.

2013-11-01

The impact of a deep-water plunging breaking wave on a partially submerged cube is studied experimentally in a tank that is 14.8 m long and 1.2 m wide with a water depth of 0.91 m. The breakers are created from dispersively focused wave packets generated by a programmable wave maker. The water surface profile in the vertical center plane of the cube is measured using a cinematic laser-induced fluorescence technique with movie frame rates ranging from 300 to 4,500 Hz. The pressure distribution on the front face of the cube is measured with 24 fast-response sensors simultaneously with the wave profile measurements. The cube is positioned vertically at three heights relative to the mean water level and horizontally at a distance from the wave maker where a strong vertical water jet is formed. The portion of the water surface between the contact point on the front face of the cube and the wave crest is fitted with a circular arc and the radius and vertical position of the fitted circle is tracked during the impact. The vertical acceleration of the contact point reaches more than 50 times the acceleration of gravity and the pressure distribution just below the free surface shows a localized high-pressure region with a very high vertical pressure gradient. This work is supported by the Office of Naval Research under grant N000141110095.

Environmental DNA as a ‘Snapshot’ of Fish Distribution: A Case Study of Japanese Jack Mackerel in Maizuru Bay, Sea of Japan

PubMed Central

Takahashi, Kohji; Sawada, Hideki; Murakami, Hiroaki; Tsuji, Satsuki; Hashizume, Hiroki; Kubonaga, Shou; Horiuchi, Tomoya; Hongo, Masamichi; Nishida, Jo; Okugawa, Yuta; Fujiwara, Ayaka; Fukuda, Miho; Hidaka, Shunsuke; Suzuki, Keita W.; Miya, Masaki; Araki, Hitoshi; Yamanaka, Hiroki; Maruyama, Atsushi; Miyashita, Kazushi; Masuda, Reiji; Minamoto, Toshifumi; Kondoh, Michio

2016-01-01

Recent studies in streams and ponds have demonstrated that the distribution and biomass of aquatic organisms can be estimated by detection and quantification of environmental DNA (eDNA). In more open systems such as seas, it is not evident whether eDNA can represent the distribution and biomass of aquatic organisms because various environmental factors (e.g., water flow) are expected to affect eDNA distribution and concentration. To test the relationships between the distribution of fish and eDNA, we conducted a grid survey in Maizuru Bay, Sea of Japan, and sampled surface and bottom waters while monitoring biomass of the Japanese jack mackerel (Trachurus japonicus) using echo sounder technology. A linear model showed a high R2 value (0.665) without outlier data points, and the association between estimated eDNA concentrations from the surface water samples and echo intensity was significantly positive, suggesting that the estimated spatial variation in eDNA concentration can reflect the local biomass of the jack mackerel. We also found that a best-fit model included echo intensity obtained within 10–150 m from water sampling sites, indicating that the estimated eDNA concentration most likely reflects fish biomass within 150 m in the bay. Although eDNA from a wholesale fish market partially affected eDNA concentration, we conclude that eDNA generally provides a ‘snapshot’ of fish distribution and biomass in a large area. Further studies in which dynamics of eDNA under field conditions (e.g., patterns of release, degradation, and diffusion of eDNA) are taken into account will provide a better estimate of fish distribution and biomass based on eDNA. PMID:26933889

Simulation of ground-water flow, surface-water flow, and a deep sewer tunnel system in the Menomonee Valley, Milwaukee, Wisconsin

USGS Publications Warehouse

Dunning, C.P.; Feinstein, D.T.; Hunt, R.J.; Krohelski, J.T.

2004-01-01

Numerical models were constructed for simulation of ground-water flow in the Menomonee Valley Brownfield, in Milwaukee, Wisconsin. An understanding of ground-water flow is necessary to develop an efficient program to sample ground water for contaminants. Models were constructed in a stepwise fashion, beginning with a regional, single-layer, analytic-element model (GFLOW code) that provided boundary conditions for a local, eight layer, finite-difference model (MODFLOW code) centered on the Menomonee Valley Brownfield. The primary source of ground water to the models is recharge over the model domains; primary sinks for ground water within the models are surface-water features and the Milwaukee Metropolitan Sewerage District Inline Storage System (ISS). Calibration targets were hydraulic heads, surface-water fluxes, vertical gradients, and ground-water infiltration to the ISS. Simulation of ground-water flow by use of the MODFLOW model indicates that about 73 percent of recharge within the MODFLOW domain circulates to the ISS and 27 percent discharges to gaining surface-water bodies. In addition, infiltration to the ISS comes from the following sources: 36 percent from recharge within the model domain, 45 percent from lateral flow into the domain, 15 percent from Lake Michigan, and 4 percent from other surface-water bodies. Particle tracking reveals that the median traveltime from the recharge point to surface-water features is 8 years; the median time to the ISS is 255 years. The traveltimes to the ISS are least over the northern part of the valley, where dolomite is near the land surface. The distribution of traveltimes in the MODFLOW simulation is greatly influenced by the effective porosity values assigned to the various lithologies.

Concentration data for anthropogenic organic compounds in groundwater, surface water, and finished water of selected community water systems in the United States, 2002-10

USGS Publications Warehouse

Carter, Janet M.; Kingsbury, James A.; Hopple, Jessica A.; Delzer, Gregory C.

2010-01-01

The National Water-Quality Assessment Program of the U.S. Geological Survey began implementing Source Water-Quality Assessments (SWQAs) in 2001 that focus on characterizing the quality of source water and finished water of aquifers and major rivers used by some of the larger community water systems in the United States. As used in SWQA studies, source water is the raw (ambient) water collected at the supply well before water treatment (for groundwater) or the raw (ambient) water collected from the river near the intake (for surface water), and finished water is the water that has been treated and is ready to be delivered to consumers. Finished-water samples are collected before the water enters the distribution system. The primary objective of SWQAs is to determine the occurrence of more than 250 anthropogenic organic compounds in source water used by community water systems, many of which currently are unregulated in drinking water by the U.S. Environmental Protection Agency. A secondary objective is to understand recurrence patterns in source water and determine if these patterns also occur in finished water before distribution. SWQA studies were conducted in two phases for most studies completed by 2005, and in one phase for most studies completed since 2005. Analytical results are reported for a total of 295 different anthropogenic organic compounds monitored in source-water and finished-water samples collected during 2002-10. The 295 compounds were classified according to the following 13 primary use or source groups: (1) disinfection by-products; (2) fumigant-related compounds; (3) fungicides; (4) gasoline hydrocarbons, oxygenates, and oxygenate degradates; (5) herbicides and herbicide degradates; (6) insecticides and insecticide degradates; (7) manufacturing additives; (8) organic synthesis compounds; (9) pavement- and combustion-derived compounds; (10) personal-care and domestic-use products; (11) plant- or animal-derived biochemicals; (12) refrigerants and propellants; and (13) solvents. This report presents the analytical results of source- water samples from 448 community water system wells and 21 surface-water sites. This report also presents the analytical results of finished-water samples from 285 wells and 20 surface-water sites from community water systems. Results of quality-assurance/quality-control samples also are presented including data for equipment blanks, field blanks, source solution blanks, and replicate samples.

The Global Enery and Water Cycle Experiment Science Strategy

NASA Technical Reports Server (NTRS)

Chahine, M. T.

1997-01-01

The distribution of water in the atmosphere and at the surface of the Earth is the most influential factor regulating our environment, not only because water is essential for life but also because through phase transitions it is the main energy source that control clouds and radiation and drives the global circulation of the atmosphere.

On the sources of vegetation activity variation, and their relation with water balance in Mexico

Treesearch

F. Mora; L.R. Iverson

1998-01-01

Natural landscape surface processes are largely controlled by the relationship between climate and vegetation. Water balance integrates the effects of climate on patterns of vegetation distribution and productivity, and for that season, functional relationships can be established using water balance variables as predictors of vegetation response. In this study, we...

Synopsis of ground-water and surface-water resources of North Dakota

USGS Publications Warehouse

Winter, T.C.; Benson, R.D.; Engberg, R.A.; Wiche, G.J.; Emerson, D.G.; Crosby, O.A.; Miller, J.E.

1984-01-01

This report describes the surface- and ground-water resources of North Dakota and the limitations of our understanding of these resources. Ground water and surface water are actually one resource, because they are often hydraulically interconnected. They are discussed separately for convenience. In general, the surface-water resources of the mainstem of the Missouri river are abundant and suitable for most uses. Other rivers may be important locally as water-supply sources, but the quantities of flow are small, quite variable in time, and generally of an unsuitable quality for most uses. Streamflow characteristics of North Dakota reflect its arid to semiarid climate (annual precipitation varies from 13 to 20 inches from west to east across the State), cold winters (usually including a significant snowpack available for spring snowmelt runoff), and the seasonal distribution of annual precipitation (almost 50 percent falls from Nky to July).Significant volumes of shallow ground water, of variable quality are found in the glacial-drift aquifers in parts of central, northern, and eastern North Dakota. Existing information provides only a limited capability to assess the long-term reliability of these scattered aquifers. There are significant indications, however, of water-quality problems related to sustained production of wells if long-term utilization of these aquifers is planned. A summary of the general suitability for use of surface water and ground water is given in Table E1.

Distribution of Genetic Marker Concentrations for Fecal Indicator Bacteria in Sewage and Animal Feces

EPA Science Inventory

The application of quantitative real-time PCR (qPCR) methods for the identification of fecal microorganisms in surface waters has the potential to revolutionize water quality monitoring worldwide. Unlike traditional cultivation methods, qPCR estimates the concentration of gen...

Evaluation of several methods of applying sewage effluent to forested soils in the winter.

Treesearch

Alfred Ray Harris

1978-01-01

Surface application methods result in heat loss, deep soil frost, and surface ice accumulations; subsurface methods decrease heat loss and produce shallower frost. Distribution of effluent within the frozen soil is a function of surface application methods, piping due to macropores and biopores, and water movement due to temperature gradients. Nitrate is not...

Hydrodynamically-driven distribution of lanternfish larvae in the Southeast Brazilian Bight

NASA Astrophysics Data System (ADS)

Namiki, Cláudia; Katsuragawa, Mario; Napolitano, Dante Campagnoli; Zani-Teixeira, Maria de Lourdes; Mattos, Rafael Augusto de; Silveira, Ilson Carlos Almeida da

2017-06-01

This study analyzes the influence of the Brazil Current and Ekman transport on the distribution of lanternfish larvae in the Southeast Brazilian Bight during summer and winter. Larvae of 19 taxa of lanternfish were identified, and Diaphus spp. and M. affine were the most abundant. Three water masses were present in the area: Coastal Water, Tropical Water and South Atlantic Central Water. Lanternfish larvae were associated with the Tropical Water in both seasons. During summer, species of Lampanyctinae were associated with the shallowest layers and Myctophinae in the deepest layers. In winter most species of both subfamilies were associated with intermediate depths, probably because greater mixing of water masses occurred at the surface and 100 m depth, limiting their distribution. During both cruises, the presence of lanternfish larvae in the continental shelf was related to the pattern of Tropical Water intrusion, which was mostly driven by the mesoscale activity of the Brazil Current and its interaction with the continental shelf.

Quantitative photography of intermittency in surface wave turbulence

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

Wright, W.; Budakian, R.; Putterman, S.J.

1997-12-31

At high amplitudes of excitation surface waves on water distribute their energy according to a Kolmogorov type of turbulent power spectrum. We have used diffusing light photography to measure the power spectrum and to quantify the presence of large structures in the turbulent state.

Spatially complex distribution of dissolved manganese in a fjord as revealed by high-resolution in situ sensing using the autonomous underwater vehicle Autosub.

PubMed

Statham, P J; Connelly, D P; German, C R; Brand, T; Overnell, J O; Bulukin, E; Millard, N; McPhail, S; Pebody, M; Perrett, J; Squire, M; Stevenson, P; Webb, A

2005-12-15

Loch Etive is a fjordic system on the west coast of Scotland. The deep waters of the upper basin are periodically isolated, and during these periods oxygen is lost through benthic respiration and concentrations of dissolved manganese increase. In April 2000 the autonomous underwater vehicle (AUV) Autosub was fitted with an in situ dissolved manganese analyzer and was used to study the spatial variability of this element together with oxygen, salinity, and temperature throughout the basin. Six along-loch transects were completed at either constant height above the seafloor or at constant depth below the surface. The ca. 4000 in situ 10-s-average dissolved Mn (Mnd) data points obtained provide a new quasi-synoptic and highly detailed view of the distribution of manganese in this fjordic environment not possible using conventional (water bottle) sampling. There is substantial variability in concentrations (<25 to >600 nM) and distributions of Mnd. Surface waters are characteristically low in Mnd reflecting mixing of riverine and marine end-member waters, both of which are low in Mnd. The deeper waters are enriched in Mnd, and as the water column always contains some oxygen, this must reflect primarily benthic inputs of reduced dissolved Mn. However, this enrichment of Mnd is spatially very variable, presumably as a result of variability in release of Mn coupled with mixing of water in the loch and removal processes. This work demonstrates how AUVs coupled with chemical sensors can reveal substantial small-scale variability of distributions of chemical species in coastal environments that would not be resolved by conventional sampling approaches. Such information is essential if we are to improve our understanding of the nature and significance of the underlying processes leading to this variability.

The statistical characteristics of rain-generated stalks on water surface

NASA Astrophysics Data System (ADS)

Liu, Xinan; Liu, Ren; Duncan, James H.

2017-11-01

Laboratory measurements of the stalks generated by the impact of raindrops are performed in a 1.22-m-by-1.22-m water pool with a water depth of 0.3 m. Simulated raindrops are generated by an array of 22-gauge hypodermic needles that are attached to the bottom of an open-surface rain tank. The raindrop diameter is about 2.6 mm and the height of the rain tank above the water surface of the pool is varied from 1 m to 4.5 m to provide different impact velocities. A number of parameters, including the diameter, height and initial upward velocity of the center jets (stalks) are measured with a cinematic laser-induced- fluorescence technique. It is found that the maximum potential energy of the stalk and the joint distribution of stalk height and diameter are strongly correlated to the impact velocities of raindrops. Comparisons between the rain experiments and single drop impacts on a quiescent water surface are also shown.

Spatial and temporal variability of soil temperature, moisture and surface soil properties

NASA Technical Reports Server (NTRS)

Hajek, B. F.; Dane, J. H.

1993-01-01

The overall objectives of this research were to: (l) Relate in-situ measured soil-water content and temperature profiles to remotely sensed surface soil-water and temperature conditions; to model simultaneous heat and water movement for spatially and temporally changing soil conditions; (2) Determine the spatial and temporal variability of surface soil properties affecting emissivity, reflectance, and material and energy flux across the soil surface. This will include physical, chemical, and mineralogical characteristics of primary soil components and aggregate systems; and (3) Develop surface soil classes of naturally occurring and distributed soil property assemblages and group classes to be tested with respect to water content, emissivity and reflectivity. This document is a report of studies conducted during the period funded by NASA grants. The project was designed to be conducted over a five year period. Since funding was discontinued after three years, some of the research started was not completed. Additional publications are planned whenever funding can be obtained to finalize data analysis for both the arid and humid locations.

A Stochastic Multi-Media Model of Microbial Transport in Watersheds

NASA Astrophysics Data System (ADS)

Yeghiazarian, L.; Safwat, A.; Whiteaker, T.; Teklitz, A.; Nietch, C.; Maidment, D. R.; Best, E. P.

2012-12-01

Fecal contamination is the leading cause of surface-water impairment in the US, and fecal pathogens are capable of triggering massive outbreaks of gastrointestinal disease. The difficulty in prediction of water contamination has its roots in the stochastic variability of fecal pathogens in the environment, and in the complexity of microbial dynamics and interactions on the soil surface and in water. To address these challenges, we have developed a stochastic model whereby the transport of microorganisms in watersheds is considered in two broad categories: microorganisms that are attached to mineral or organic substrates in suspended sediment; and unattached microorganisms suspended in overland flow. The interactions of microorganisms with soil particles on the soil surface and in the overland flow lead to transitions of microorganisms between solid and aqueous media. The strength of attachment of microorganisms to soil particles is determined by the chemical characteristics of soils which are highly correlated with the particle size. The particle size class distribution in the suspended sediment is predicted by the Water Erosion Prediction Project (WEPP). The model is integrated with ArcGIS, resulting in a general transport-modeling framework applicable to a variety of biological and chemical surface water contaminants. Simulations are carried out for a case study of contaminant transport in the East Fork Little Miami River Watershed in Ohio. Model results include the spatial probability distribution of microbes in the watershed and can be used for assessment of (1) mechanisms dominating microbial transport, and (2) time and location of highest likelihood of microbial occurrence, thus yielding information on best water sampling strategies.

Sensitivity of stream water age to climatic variability and land use change: implications for water quality

NASA Astrophysics Data System (ADS)

Soulsby, Chris; Birkel, Christian; Geris, Josie; Tetzlaff, Doerthe

2016-04-01

Advances in the use of hydrological tracers and their integration into rainfall runoff models is facilitating improved quantification of stream water age distributions. This is of fundamental importance to understanding water quality dynamics over both short- and long-time scales, particularly as water quality parameters are often associated with water sources of markedly different ages. For example, legacy nitrate pollution may reflect deeper waters that have resided in catchments for decades, whilst more dynamics parameters from anthropogenic sources (e.g. P, pathogens etc) are mobilised by very young (<1 day) near-surface water sources. It is increasingly recognised that water age distributions of stream water is non-stationary in both the short (i.e. event dynamics) and longer-term (i.e. in relation to hydroclimatic variability). This provides a crucial context for interpreting water quality time series. Here, we will use longer-term (>5 year), high resolution (daily) isotope time series in modelling studies for different catchments to show how variable stream water age distributions can be a result of hydroclimatic variability and the implications for understanding water quality. We will also use examples from catchments undergoing rapid urbanisation, how the resulting age distributions of stream water change in a predictable way as a result of modified flow paths. The implication for the management of water quality in urban catchments will be discussed.

Distribution characteristics of organochlorine pesticide in the water environment in Lanzhou section of Yellow River

NASA Astrophysics Data System (ADS)

Yang, L.; Zhao, X.; Shen, J. M.; Chen, Z. L.; Wang, X. C.; Qiu, H. R.

2017-04-01

Surface water, surface sediments and suspended particles in the Lanzhou section of Yellow River were collected. After the samples were lyophilised, extracted, concentrated, purified and separated, organochlorine pesticides in the samples were analysed by GC-MS. Results showed that organochlorine pesticide contents in surface water, surface sediments and suspended particles ranged from 28.63 ng/L to 123.2 ng/L, from 0.86 ng/g to 4.51 ng/g and from 23.29 ng/g to 126.14 ng/g, respectively. HCHs, DDTs and HCB were high; among these contents, HCH contents ranged from 1.49 ng/L to 18.1 ng/L, from 0.04ng/g to 1.53 ng/g and from 2.74ng/g to 25.64 ng/g, respectively. DDT contents ranged from 1.49 ng/Lto 18.1 ng/L, from 0.04 ng/g to 1.53 ng/g and from 2.74 ng/g to 25.64 ng/g, respectively. Component analysis results showed that organochlorine pesticide in the Lanzhou section of Yellow River was mainly from early residues or soil after pesticides were applied and long-term weathering occurred. Correlation analysis results showed that total organic carbon was an important factor affecting the distribution of organochlorine pesticide in sediments. Moderate organochlorine pesticide contents were detected in surface water in Lanzhou section of Yellow River compared with other rivers in our country and in other countries. Furthermore, the ecological risk of organochlorine pesticide in surface sediments was low.

Aquifer Vulnerability Assessment Based on Sequence Stratigraphic and ³⁹Ar Transport Modeling.

PubMed

Sonnenborg, Torben O; Scharling, Peter B; Hinsby, Klaus; Rasmussen, Erik S; Engesgaard, Peter

2016-03-01

A large-scale groundwater flow and transport model is developed for a deep-seated (100 to 300 m below ground surface) sedimentary aquifer system. The model is based on a three-dimensional (3D) hydrostratigraphic model, building on a sequence stratigraphic approach. The flow model is calibrated against observations of hydraulic head and stream discharge while the credibility of the transport model is evaluated against measurements of (39)Ar from deep wells using alternative parameterizations of dispersivity and effective porosity. The directly simulated 3D mean age distributions and vertical fluxes are used to visualize the two-dimensional (2D)/3D age and flux distribution along transects and at the top plane of individual aquifers. The simulation results are used to assess the vulnerability of the aquifer system that generally has been assumed to be protected by thick overlaying clayey units and therefore proposed as future reservoirs for drinking water supply. The results indicate that on a regional scale these deep-seated aquifers are not as protected from modern surface water contamination as expected because significant leakage to the deeper aquifers occurs. The complex distribution of local and intermediate groundwater flow systems controlled by the distribution of the river network as well as the topographical variation (Tóth 1963) provides the possibility for modern water to be found in even the deepest aquifers. © 2015, National Ground Water Association.

Contamination of ground water, surface water, and soil, and evaluation of selected ground-water pumping alternatives in the Canal Creek area of Aberdeen Proving Ground, Maryland

USGS Publications Warehouse

Lorah, Michelle M.; Clark, Jeffrey S.

1996-01-01

Chemical manufacturing, munitions filling, and other military-support activities have resulted in the contamination of ground water, surface water, and soil in the Canal Creek area of Aberdeen Proving Ground, Maryland. Chlorinated volatile organic compounds, including 1,1,2,2-tetrachloroethane and trichloroethylene, are widespread ground-water contaminants in two aquifers that are composed of unconsolidated sand and gravel. Distribution and fate of chlorinated organic compounds in the ground water has been affected by the movement and dissolution of solvents in their dense immiscible phase and by microbial degradation under anaerobic conditions. Detection of volatile organic contaminants in adjacent surface water indicates that shallow contaminated ground water discharges to surface water. Semivolatile organic compounds, especially polycyclic aromatic hydrocarbons, are the most prevalent organic contaminants in soils. Various trace elements, such as arsenic, cadmium, lead, and zinc, were found in elevated concentrations in ground water, surface water, and soil. Simulations with a ground-water-flow model and particle tracker postprocessor show that, without remedial pumpage, the contaminants will eventually migrate to Canal Creek and Gunpowder River. Simulations indicate that remedial pumpage of 2.0 million gallons per day from existing wells is needed to capture all particles originating in the contaminant plumes. Simulated pumpage from offsite wells screened in a lower confined aquifer does not affect the flow of contaminated ground water in the Canal Creek area.

The Distribution of Road Salt in Private Drinking Water Wells in a Southeastern New York Suburban Township.

PubMed

Kelly, Victoria R; Cunningham, Mary Ann; Curri, Neil; Findlay, Stuart E; Carroll, Sean M

2018-05-01

We used a GIS analysis of sodium and chloride concentrations in private water wells in a southeastern New York township to describe the pattern of distribution of road salt in aquifers tapped for drinking water. The primary source of road salt was sodium chloride, and sodium and chloride concentrations were significantly correlated ( = 0.80, < 0.01). Chloride concentrations in wells increased as the percentage of impervious surface cover (ISC) within a 250-m radius around wells increased ( = 0.87, < 0.01) and declined with increasing distance to the nearest road ( = 0.76, < 0.01). Wells that were located lower in elevation than the nearest road had higher concentrations of chloride than wells that were higher than the nearest road, but this occurred only when the nearest road was >30 m from the wells ( < 0.01). Chloride concentrations were not affected by well depth or adjacent road type (major or minor roads). Surface geology and hydrologic soil class had significant effects ( < 0.01) on chloride concentrations in wells, with porous surface geology types and well-drained soils having higher concentrations; these effects may be confounded by the fact that ISC was more likely to occur on these permeable surface geology and soil types. Hot and cold spot analysis revealed substantial unevenness in chloride concentrations. Results for sodium were similar to those for chloride. Overall, these results indicate that road salt contamination of groundwater is unevenly distributed and is affected by landscape factors that can be used to guide well testing and best management practices of deicing salt distribution. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Gold core@silver semishell Janus nanoparticles prepared by interfacial etching

NASA Astrophysics Data System (ADS)

Chen, Limei; Deming, Christopher P.; Peng, Yi; Hu, Peiguang; Stofan, Jake; Chen, Shaowei

2016-07-01

Gold core@silver semishell Janus nanoparticles were prepared by chemical etching of Au@Ag core-shell nanoparticles at the air/water interface. Au@Ag core-shell nanoparticles were synthesized by chemical deposition of a silver shell onto gold seed colloids followed by the self-assembly of 1-dodecanethiol onto the nanoparticle surface. The nanoparticles then formed a monolayer on the water surface of a Langmuir-Blodgett trough, and part of the silver shell was selectively etched away by the mixture of hydrogen peroxide and ammonia in the water subphase, where the etching was limited to the side of the nanoparticles that was in direct contact with water. The resulting Janus nanoparticles exhibited an asymmetrical distribution of silver on the surface of the gold cores, as manifested in transmission electron microscopy, UV-vis absorption, and X-ray photoelectron spectroscopy measurements. Interestingly, the Au@Ag semishell Janus nanoparticles exhibited enhanced electrocatalytic activity in oxygen reduction reactions, as compared to their Au@Ag and Ag@Au core-shell counterparts, likely due to a synergistic effect between the gold cores and silver semishells that optimized oxygen binding to the nanoparticle surface.Gold core@silver semishell Janus nanoparticles were prepared by chemical etching of Au@Ag core-shell nanoparticles at the air/water interface. Au@Ag core-shell nanoparticles were synthesized by chemical deposition of a silver shell onto gold seed colloids followed by the self-assembly of 1-dodecanethiol onto the nanoparticle surface. The nanoparticles then formed a monolayer on the water surface of a Langmuir-Blodgett trough, and part of the silver shell was selectively etched away by the mixture of hydrogen peroxide and ammonia in the water subphase, where the etching was limited to the side of the nanoparticles that was in direct contact with water. The resulting Janus nanoparticles exhibited an asymmetrical distribution of silver on the surface of the gold cores, as manifested in transmission electron microscopy, UV-vis absorption, and X-ray photoelectron spectroscopy measurements. Interestingly, the Au@Ag semishell Janus nanoparticles exhibited enhanced electrocatalytic activity in oxygen reduction reactions, as compared to their Au@Ag and Ag@Au core-shell counterparts, likely due to a synergistic effect between the gold cores and silver semishells that optimized oxygen binding to the nanoparticle surface. Electronic supplementary information (ESI) available: Additional TEM, UV-vis, XPS, and electrochemical data. See DOI: 10.1039/c6nr03368g

Volume and surface area size distribution, water mass and model fitting of GCE/CASE/WATOX marine aerosols

NASA Astrophysics Data System (ADS)

Kim, Y.; Sievering, H.; Boatman, J.

1990-06-01

As a part of the Global Change Expedition/Coordinated Air-Sea Experiment/Western Atlantic Ocean Experiment (GCE/CASE/WATOX), size distributions of marine aerosols were measured at two altitudes of about 2750 and 150 m above sea level (asl) over the size range 0.1 ˜ 32 μm. Lognormal fitting was applied to the corrected aerosol size spectra to determine the volume and surface area size distributions of the CASE-WATOX marine aerosols. Each aerosol size distribution was fitted with three lognormal distributions representing fine-, large-, and giant-particle modes. Water volume fraction and dry particle size of each aerosol size distribution were also calculated using empirical formulas for particle size as a function of relative humidity and particle type. Because of the increased influence from anthropogenic sources in the continental United States, higher aerosol volume concentrations were observed in the fine-particle mode near-shore off the east coast; 2.11 and 3.63 μm3 cm-3 for free troposphere (FT) and marine boundary layer (MBL), compared with the open-sea Bermuda area values; 0.13 and 0.74 μm3 cm-3 for FT and MBL. The large-particle mode exhibits the least variations in volume distributions between the east coast and open-sea Bermuda area, having a volume geometric median diameter (VGMD) between 1.4 and 1.6 μm and a geometric standard deviation between 1.57 and 1.68. For the giant-particle mode, larger VGMD and volume concentrations were observed for marine aerosols nearshore off the east coast than in the open-sea Bermuda area because of higher relative humidity and higher surface wind speed conditions. Wet VGMD and aerosol water volume concentrations at 15 m asl ship level were determined by extrapolating from those obtained by analysis of the CASE-WATOX aircraft aerosol data. Abundance of aerosol water in the MBL serves as an important pathway for heterogeneous conversion of SO2 in sea salt aerosol particles.

Overview of DAN/MSL water and chlorine measurements acquired in Gale area for four years of surface observations

NASA Astrophysics Data System (ADS)

Litvak, Maxim

2017-04-01

During more than 4 years MSL Curiosity rover (landed in Gale crater in August 2012) is traveling toward sedimentary layered mound deposited with phyllosilicates and hematite hydrated minerals. Curiosity already traversed more than 14 km and identified lacustrine deposits left from ancient lakes filled Gale area in early history of Mars. Along the traverse the Curiosity rover discovered unique signatures regarding how the Mars environment changed from ancient warm and wet conditions and probably habitable environment to the modern cold and dry climate. We have summarized numerous measurements from the Dynamic Albedo of Neutron (DAN) instrument on Curiosity rover to overview variations of subsurface bound water distribution from the wet to the dry locations, compared it with other MSL measurements and with possible distribution of hydrated minerals and sequence of geological units travelled by Curiosity. We have also performed joint analysis of water and chlorine distributions and compared bulk (down to 0.5 m depth) equivalent chlorine concentrations measured by DAN throughout the Gale area and APXS observations of corresponding local surface targets and drill fines.

Pan-Arctic distributions of continental runoff in the Arctic Ocean.

PubMed

Fichot, Cédric G; Kaiser, Karl; Hooker, Stanford B; Amon, Rainer M W; Babin, Marcel; Bélanger, Simon; Walker, Sally A; Benner, Ronald

2013-01-01

Continental runoff is a major source of freshwater, nutrients and terrigenous material to the Arctic Ocean. As such, it influences water column stratification, light attenuation, surface heating, gas exchange, biological productivity and carbon sequestration. Increasing river discharge and thawing permafrost suggest that the impacts of continental runoff on these processes are changing. Here, a new optical proxy was developed and implemented with remote sensing to determine the first pan-Arctic distribution of terrigenous dissolved organic matter (tDOM) and continental runoff in the surface Arctic Ocean. Retrospective analyses revealed connections between the routing of North American runoff and the recent freshening of the Canada Basin, and indicated a correspondence between climate-driven changes in river discharge and tDOM inventories in the Kara Sea. By facilitating the real-time, synoptic monitoring of tDOM and freshwater runoff in surface polar waters, this novel approach will help understand the manifestations of climate change in this remote region.

Defining surfaces for skewed, highly variable data

USGS Publications Warehouse

Helsel, D.R.; Ryker, S.J.

2002-01-01

Skewness of environmental data is often caused by more than simply a handful of outliers in an otherwise normal distribution. Statistical procedures for such datasets must be sufficiently robust to deal with distributions that are strongly non-normal, containing both a large proportion of outliers and a skewed main body of data. In the field of water quality, skewness is commonly associated with large variation over short distances. Spatial analysis of such data generally requires either considerable effort at modeling or the use of robust procedures not strongly affected by skewness and local variability. Using a skewed dataset of 675 nitrate measurements in ground water, commonly used methods for defining a surface (least-squares regression and kriging) are compared to a more robust method (loess). Three choices are critical in defining a surface: (i) is the surface to be a central mean or median surface? (ii) is either a well-fitting transformation or a robust and scale-independent measure of center used? (iii) does local spatial autocorrelation assist in or detract from addressing objectives? Published in 2002 by John Wiley & Sons, Ltd.

Hydrochemical and environmental isotope analysis of groundwater and surface water in a dry mountain region in Northern Chile.

PubMed

Zang, Carina; Dame, Juliane; Nüsser, Marcus

2018-05-08

This case study examines the geological imprint and land use practices on water quality in the arid Huasco Valley against the backdrop of ongoing water conflicts surrounding competing demands for agriculture and mining. The study is based on a detailed analysis of spatial and temporal variations of monthly surface and bi-monthly groundwater quality samples measured during the Chilean summer of 2015/16. Additional information on source regions and river-groundwater interactions were collected using stable water isotopes. Regarding the geological impact on water quality, high concentrations of Ca 2+ , SO 4 2- and HCO 3 - indicate a strong influence of magmatic rocks, which constitute this high mountain basin, on the hydrochemistry. Piper and Gibbs-diagrams revealed that all samples show a homogenous distribution dominated by rock-water interactions. Measured NO 3 - concentrations in surface water are generally low. However, groundwater aquifers exhibit higher concentrations. Mn is the only heavy metal with elevated concentrations in surface water, which are possibly related to mining activities. The results illustrate that both surface and groundwater can be classified as suitable for irrigation. In addition, groundwater has been found to be suitable as drinking water. High similarities in isotopic signatures indicate a strong connection between surface and groundwater. Isotopic analyses suggest a strong influence of evaporation. This combined approach of hydrogeochemical and isotopic analysis proved to be a helpful tool in characterizing the catchment and can serve as a basis for future sustainable water management.

Risk Assessment in Relation to the Effect of Climate Change on Water Shortage in the Taichung Area

NASA Astrophysics Data System (ADS)

Hsiao, J.; Chang, L.; Ho, C.; Niu, M.

2010-12-01

Rapid economic development has stimulated a worldwide greenhouse effect and induced global climate change. Global climate change has increased the range of variation in the quantity of regional river flows between wet and dry seasons, which effects the management of regional water resources. Consequently, the influence of climate change has become an important issue in the management of regional water resources. In this study, the Monte Carlo simulation method was applied to risk analysis of shortage of water supply in the Taichung area. This study proposed a simulation model that integrated three models: weather generator model, surface runoff model, and water distribution model. The proposed model was used to evaluate the efficiency of the current water supply system and the potential effectiveness of two additional plans for water supply: the “artificial lakes” plan and the “cross-basin water transport” plan. A first-order Markov Chain method and two probability distribution models, exponential distribution and normal distribution, were used in the weather generator model. In the surface runoff model, researchers selected the Generalized Watershed Loading Function model (GWLF) to simulate the relationship between quantity of rainfall and basin outflow. A system dynamics model (SD) was applied to the water distribution model. Results of the simulation indicated that climate change could increase the annual quantity of river flow in the Dachia River and Daan River basins. However, climate change could also increase the difference in the quantity of river flow between wet and dry seasons. Simulation results showed that in current system case or in the additional plan cases, shortage status of water for both public and agricultural uses with conditions of climate change will be mostly worse than that without conditions of climate change except for the shortage status for the public use in the current system case. With or without considering the effect of climate change, the additional plans, especially the “cross-basin water transport” plan, for water supply could significantly increase the supply of water for public use. The proposed simulation model and results of analysis in this study could provide valuable reference for decision-makers in regards to risk analysis of regional water supply.

Time resolved analysis of water drainage in porous asphalt concrete using neutron radiography.

PubMed

Poulikakos, L D; Sedighi Gilani, M; Derome, D; Jerjen, I; Vontobel, P

2013-07-01

Porous asphalt as a road surface layer controls aquaplaning as rain water can drain through its highly porous structure. The process of water drainage through this permeable layer is studied using neutron radiography. Time-resolved water configuration and distribution within the porous structure are reported. It is shown that radiography depicts the process of liquid water transport within the complex geometry of porous asphalt, capturing water films, filled dead end pores and water islands. Copyright © 2013 Elsevier Ltd. All rights reserved.

Partition of nonionic organic compounds in aquatic systems

USGS Publications Warehouse

Smith, James A.; Witkowski, Patrick J.; Chiou, Cary T.

1988-01-01

In aqueous systems, the distribution of many nonionic organic solutes in soil-sediment, aquatic organisms, and dissolved organic matter can be explained in terms of a partition model. The nonionic organic solute is distributed between water and different organic phases that behave as bulk solvents. Factors such as polarity, composition, and molecular size of the solute and organic phase determine the relative importance of partition to the environmental distribution of the solute. This chapter reviews these factors in the context of a partition model and also examines several environmental applications of the partition model for surface- and ground-water systems.

Safety of packaged water distribution limited by household recontamination in rural Cambodia.

PubMed

Holman, Emily J; Brown, Joe

2014-06-01

Packaged water treatment schemes represent a growing model for providing safer water in low-income settings, yet post-distribution recontamination of treated water may limit this approach. This study evaluates drinking water quality and household water handling practices in a floating village in Tonlé Sap Lake, Cambodia, through a pilot cross-sectional study of 108 households, approximately half of which used packaged water as the main household drinking water source. We hypothesized that households purchasing drinking water from local packaged water treatment plants would have microbiologically improved drinking water at the point of consumption. We found no meaningful difference in microbiological drinking water quality between households using packaged, treated water and those collecting water from other sources, including untreated surface water, however. Households' water storage and handling practices and home hygiene may have contributed to recontamination of drinking water. Further measures to protect water quality at the point-of-use may be required even if water is treated and packaged in narrow-mouthed containers.

Occurrence and distribution of psychoactive compounds and their metabolites in the urban water cycle of Berlin (Germany).

PubMed

Hass, Ulrike; Duennbier, Uwe; Massmann, Gudrun

2012-11-15

The occurrence and distribution of six psychoactive compounds (primidone, phenobarbital, oxazepam, diazepam, meprobamate, and pyrithyldione) and a metabolite of primidone (phenylethylmalonamide) were investigated in wastewater treatment plant (WWTP) effluents, surface water, groundwater of a bank filtration site, raw and final drinking water, and in groundwater affected by former sewage irrigation. Primidone and its metabolite phenylethylmalonamide were found to be ubiquitous in environmental water samples in Berlin. Maximum concentrations of 0.87 and 0.42 μg/L, respectively, were encountered in WWTP effluents. Both compounds are apparently not removed when passaging through the different compartments of the water cycle and concentrations are only reduced by dilution. Phenobarbital was present at nearly every stage of the Berlin water cycle with the exception of raw and final drinking water. The highest concentrations of phenobarbital (up to 0.96 μg/L) were measured in groundwater influenced by former sewage irrigation. Oxazepam was only present in WWTP effluents and surface waters (up to 0.18 μg/L), while diazepam was not detected in any matrix. Due to their withdrawal from the German market years ago, the pharmaceuticals meprobamate and pyrithyldione were only found in sewage farm groundwater (up to 0.50 and 0.04 μg/L, respectively) and, in case of meprobamate, also in decade old bank filtrate (0.03 μg/L). Our results indicate a high persistence of some of the investigated compounds in the aquatic system. As a consequence, these pollutants may potentially reach drinking water resources via bank filtration if present in WWTP effluents and/or surface waters in partly closed water cycles such as Berlin's. Copyright © 2012 Elsevier Ltd. All rights reserved.

Ground-water/surface-water responses to global climate simulations, Santa Clara-Calleguas basin, Ventura County, California, 1950-93

USGS Publications Warehouse

Hanson, Randall T.; Dettinger, Michael D.

2005-01-01

Climate variations can play an important, if not always crucial, role in successful conjunctive management of ground water and surface water resources. This will require accurate accounting of the links between variations in climate, recharge, and withdrawal from the resource systems, accurate projection or predictions of the climate variations, and accurate simulation of the responses of the resource systems. To assess linkages and predictability of climate influences on conjunctive management, global climate model (GCM) simulated precipitation rates were used to estimate inflows and outflows from a regional ground water model (RGWM) of the coastal aquifers of the Santa Clara-Calleguas Basin at Ventura, California, for 1950 to 1993. Interannual to interdecadal time scales of the El Niño Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) climate variations are imparted to simulated precipitation variations in the Southern California area and are realistically imparted to the simulated ground water level variations through the climate-driven recharge (and discharge) variations. For example, the simulated average ground water level response at a key observation well in the basin to ENSO variations of tropical Pacific sea surface temperatures is 1.2 m/°C, compared to 0.9 m/°C in observations. This close agreement shows that the GCM-RGWM combination can translate global scale climate variations into realistic local ground water responses. Probability distributions of simulated ground water level excursions above a local water level threshold for potential seawater intrusion compare well to the corresponding distributions from observations and historical RGWM simulations, demonstrating the combination's potential usefulness for water management and planning. Thus the GCM-RGWM combination could be used for planning purposes and — when the GCM forecast skills are adequate — for near term predictions.

Ground water/surface water responses to global climate simulations, Santa Clara-Calleguas Basin, Ventura, California

USGS Publications Warehouse

Hanson, R.T.; Dettinger, M.D.

2005-01-01

Climate variations can play an important, if not always crucial, role in successful conjunctive management of ground water and surface water resources. This will require accurate accounting of the links between variations in climate, recharge, and withdrawal from the resource systems, accurate projection or predictions of the climate variations, and accurate simulation of the responses of the resource systems. To assess linkages and predictability of climate influences on conjunctive management, global climate model (GCM) simulated precipitation rates were used to estimate inflows and outflows from a regional ground water model (RGWM) of the coastal aquifers of the Santa ClaraCalleguas Basin at Ventura, California, for 1950 to 1993. Interannual to interdecadal time scales of the El Nin??o Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) climate variations are imparted to simulated precipitation variations in the Southern California area and are realistically imparted to the simulated ground water level variations through the climate-driven recharge (and discharge) variations. For example, the simulated average ground water level response at a key observation well in the basin to ENSO variations of tropical Pacific sea surface temperatures is 1.2 m/??C, compared to 0.9 m/??C in observations. This close agreement shows that the GCM-RGWM combination can translate global scale climate variations into realistic local ground water responses. Probability distributions of simulated ground water level excursions above a local water level threshold for potential seawater intrusion compare well to the corresponding distributions from observations and historical RGWM simulations, demonstrating the combination's potential usefulness for water management and planning. Thus the GCM-RGWM combination could be used for planning purposes and - when the GCM forecast skills are adequate - for near term predictions.

Desktop Techniques for Analyzing Surface-Ground Water Interactions. The Reelfoot Lake Case Study

DTIC Science & Technology

1988-05-01

Reelfoot Lake Case Study DTlCSELECTE JUN 13 M Research Document No. 28 May 1988 Approved for Public Release. Distribution Unlimited. 86 , l~ g DESKTOP...TECHNIQUES FOR ANALYZING SURFACE-GROUND WATER INTERACTIONS The Reelfoot Lake Case Study Prepared by Dennis B. McLaughlin ’ Ia Prepared for The...Engineers became involved in a study of Reelfoot Lake , a large natural lake in northwestern Tennessee. Although modeling studies of the lake and its

Vertical Distribution of Water at Phoenix

NASA Technical Reports Server (NTRS)

Tamppari, L. K.; Lemmon, M. T.

2011-01-01

Phoenix results, combined with coordinated observations from the Mars Reconnaissance Orbiter of the Phoenix lander site, indicate that the water vapor is nonuniform (i.e., not well mixed) up to a calculated cloud condensation level. It is important to understand the mixing profile of water vapor because (a) the assumption of a well-mixed atmosphere up to a cloud condensation level is common in retrievals of column water abundances which are in turn used to understand the seasonal and interannual behavior of water, (b) there is a long history of observations and modeling that conclude both that water vapor is and is not well-mixed, and some studies indicate that the water vapor vertical mixing profile may, in fact, change with season and location, (c) the water vapor in the lowest part of the atmosphere is the reservoir that can exchange with the regolith and higher amounts may have an impact on the surface chemistry, and (d) greater water vapor abundances close to the surface may enhance surface exchange thereby reducing regional transport, which in turn has implications to the net transport of water vapor over seasonal and annual timescales.

Distribution of a pelagic tunicate, Salpa fusiformis in warm surface current of the eastern Korean waters and its impingement on cooling water intakes of Uljin nuclear power plant.

PubMed

Chae, Jinho; Choi, Hyun Woo; Lee, Woo Jin; Kim, Dongsung; Lee, Jae Hac

2008-07-01

Impingement of a large amount of gelatinous plankton, Salpa fusiformis on the seawater intake system-screens in a nuclear power plant at Uljin was firstly recorded on 18th June 2003. Whole amount of the clogged animals was estimated were presumptively at 295 tons and the shortage of cooling seawater supply by the animal clogging caused 38% of decrease in generation capability of the power plant. Zooplankton collection with a multiple towing net during the day and at night from 5 to 6 June 2003 included various gelatinous zooplanktons known to be warm water species such as salps and siphonophores. Comparatively larger species, Salpa fusiformis occupied 25.4% in individual density among the gelatinous plankton and showed surface distribution in the depth shallower than thermocline, performing little diel vertical migration. Temperature, salinity and satellite data also showed warm surface current predominated over the southern coastal region near the power plant in June. The results suggested that warm surface current occasionally extended into the neritic region may transfer S. fusiformis, to the waters off the power plant. The environmental factors and their relation to ecobiology of the large quantity of salpa population that are being sucked into the intake channel of the power plant are discussed.

Fine-Scale Spatial Heterogeneity in the Distribution of Waterborne Protozoa in a Drinking Water Reservoir.

PubMed

Burnet, Jean-Baptiste; Ogorzaly, Leslie; Penny, Christian; Cauchie, Henry-Michel

2015-09-23

The occurrence of faecal pathogens in drinking water resources constitutes a threat to the supply of safe drinking water, even in industrialized nations. To efficiently assess and monitor the risk posed by these pathogens, sampling deserves careful design, based on preliminary knowledge on their distribution dynamics in water. For the protozoan pathogens Cryptosporidium and Giardia, only little is known about their spatial distribution within drinking water supplies, especially at fine scale. Two-dimensional distribution maps were generated by sampling cross-sections at meter resolution in two different zones of a drinking water reservoir. Samples were analysed for protozoan pathogens as well as for E. coli, turbidity and physico-chemical parameters. Parasites displayed heterogeneous distribution patterns, as reflected by significant (oo)cyst density gradients along reservoir depth. Spatial correlations between parasites and E. coli were observed near the reservoir inlet but were absent in the downstream lacustrine zone. Measurements of surface and subsurface flow velocities suggest a role of local hydrodynamics on these spatial patterns. This fine-scale spatial study emphasizes the importance of sampling design (site, depth and position on the reservoir) for the acquisition of representative parasite data and for optimization of microbial risk assessment and monitoring. Such spatial information should prove useful to the modelling of pathogen transport dynamics in drinking water supplies.

Estimating the spatial distribution of artificial groundwater recharge using multiple tracers.

PubMed

Moeck, Christian; Radny, Dirk; Auckenthaler, Adrian; Berg, Michael; Hollender, Juliane; Schirmer, Mario

2017-10-01

Stable isotopes of water, organic micropollutants and hydrochemistry data are powerful tools for identifying different water types in areas where knowledge of the spatial distribution of different groundwater is critical for water resource management. An important question is how the assessments change if only one or a subset of these tracers is used. In this study, we estimate spatial artificial infiltration along an infiltration system with stage-discharge relationships and classify different water types based on the mentioned hydrochemistry data for a drinking water production area in Switzerland. Managed aquifer recharge via surface water that feeds into the aquifer creates a hydraulic barrier between contaminated groundwater and drinking water wells. We systematically compare the information from the aforementioned tracers and illustrate differences in distribution and mixing ratios. Despite uncertainties in the mixing ratios, we found that the overall spatial distribution of artificial infiltration is very similar for all the tracers. The highest infiltration occurred in the eastern part of the infiltration system, whereas infiltration in the western part was the lowest. More balanced infiltration within the infiltration system could cause the elevated groundwater mound to be distributed more evenly, preventing the natural inflow of contaminated groundwater. Dedicated to Professor Peter Fritz on the occasion of his 80th birthday.

Using a spatially-distributed hydrologic biogeochemistry model to study the spatial variation of carbon processes in a Critical Zone Observatory

NASA Astrophysics Data System (ADS)

Shi, Y.; Eissenstat, D. M.; Davis, K. J.; He, Y.

2016-12-01

Forest carbon processes are affected by, among other factors, soil moisture, soil temperature, soil nutrients and solar radiation. Most of the current biogeochemical models are 1-D and represent one point in space. Therefore, they cannot resolve the topographically driven hill-slope land surface heterogeneity or the spatial pattern of nutrient availability. A spatially distributed forest ecosystem model, Flux-PIHM-BGC, has been developed by coupling a 1-D mechanistic biogeochemical model Biome-BGC (BBGC) with a spatially distributed land surface hydrologic model, Flux-PIHM. Flux-PIHM is a coupled physically based model, which incorporates a land-surface scheme into the Penn State Integrated Hydrologic Model (PIHM). The land surface scheme is adapted from the Noah land surface model. Flux-PIHM is able to represent the link between groundwater and the surface energy balance, as well as the land surface heterogeneities caused by topography. In the coupled Flux-PIHM-BGC model, each Flux-PIHM model grid couples a 1-D BBGC model, while soil nitrogen is transported among model grids via subsurface water flow. In each grid, Flux-PIHM provides BBGC with soil moisture, soil temperature, and solar radiation information, while BBGC provides Flux-PIHM with leaf area index. The coupled Flux-PIHM-BGC model has been implemented at the Susquehanna/Shale Hills critical zone observatory (SSHCZO). Model results suggest that the vegetation and soil carbon distribution is primarily constrained by nitorgen availability (affected by nitorgen transport via topographically driven subsurface flow), and also constrained by solar radiation and root zone soil moisture. The predicted vegetation and soil carbon distribution generally agrees with the macro pattern observed within the watershed. The coupled ecosystem-hydrologic model provides an important tool to study the impact of topography on watershed carbon processes, as well as the impact of climate change on water resources.

Evaluation of SCS-CN method using a fully distributed physically based coupled surface-subsurface flow model

NASA Astrophysics Data System (ADS)

Shokri, Ali

2017-04-01

The hydrological cycle contains a wide range of linked surface and subsurface flow processes. In spite of natural connections between surface water and groundwater, historically, these processes have been studied separately. The current trend in hydrological distributed physically based model development is to combine distributed surface water models with distributed subsurface flow models. This combination results in a better estimation of the temporal and spatial variability of the interaction between surface and subsurface flow. On the other hand, simple lumped models such as the Soil Conservation Service Curve Number (SCS-CN) are still quite common because of their simplicity. In spite of the popularity of the SCS-CN method, there have always been concerns about the ambiguity of the SCS-CN method in explaining physical mechanism of rainfall-runoff processes. The aim of this study is to minimize these ambiguity by establishing a method to find an equivalence of the SCS-CN solution to the DrainFlow model, which is a fully distributed physically based coupled surface-subsurface flow model. In this paper, two hypothetical v-catchment tests are designed and the direct runoff from a storm event are calculated by both SCS-CN and DrainFlow models. To find a comparable solution to runoff prediction through the SCS-CN and DrainFlow, the variance between runoff predictions by the two models are minimized by changing Curve Number (CN) and initial abstraction (Ia) values. Results of this study have led to a set of lumped model parameters (CN and Ia) for each catchment that is comparable to a set of physically based parameters including hydraulic conductivity, Manning roughness coefficient, ground surface slope, and specific storage. Considering the lack of physical interpretation in CN and Ia is often argued as a weakness of SCS-CN method, the novel method in this paper gives a physical explanation to CN and Ia.

Investigations into Drinking Water Distribution System Nitrification: EPA Microelectrode Research

EPA Science Inventory

Because of the Stage 1 and Stage 2 Disinfectants and Disinfection Byproduct Rules, chloramination for secondary disinfection in the United States is predicted to increase to 57% of all surface and 7% of all ground water treatment systems. Chloramination comes with the risk of di...

Modeling runoff generation in a small snow-dominated mountainous catchment

USDA-ARS?s Scientific Manuscript database

Snowmelt in mountainous areas is an important contributor to river water flows in the western United States. We developed a distributed model that calculates solar radiation, canopy energy balance, surface energy balance, snow pack dynamics, soil water flow, snow–soil–bedrock heat exchange, soil wat...

Constraining Water Vapor Abundance on Mars using a Coupled Heat-Water Transport Model and Seasonal Frost Observations

NASA Astrophysics Data System (ADS)

Bapst, J.; Byrne, S.

2016-12-01

The stability of water ice on Mars' surface is determined by its temperature and the density of water vapor at the bottom of the atmosphere. Multiple orbiting instruments have been used to study column-integrated water abundance in the martian atmosphere, resolving the global annual water cycle. However, poor knowledge of the vertical distribution of water makes constraining its abundance near the surface difficult. One must assume a mixing regime to produce surface vapor density estimates. More indirectly, one can use the appearance and disappearance of seasonal water frost, along with ice stability models, to estimate this value. Here, we use derived temperature and surface reflectance data from MGS TES to constrain a 1-D thermal diffusion model, which is coupled to an atmospheric water transport model. TES temperatures are used to constrain thermal properties of our modeled subsurface, while changes in TES albedo can be used to determine the timing of water frost. We tune the density of water vapor in the atmospheric model to match the observed seasonal water frost timing in the northern hemisphere, poleward of 45°N. Thus, we produce a new estimate for the water abundance in the lower atmosphere of Mars and how it varies seasonally and geographically. The timing of water frost can be ambiguous in TES data, especially at lower latitudes where the albedo contrast between frosted and unfrosted surfaces is lower (presumably due to lesser areal coverage of water frost). The uncertainty in frost timing with our approach is <20° LS ( 40 sols), and will be used to define upper and lower bounds in our estimate of vapor density. The implications of our derived vapor densities on the stability of surface and subsurface water ice will be discussed.

Water inventories on Earth and Mars: Clues to atmosphere formation

NASA Technical Reports Server (NTRS)

Carr, M. H.

1992-01-01

Water is distributed differently on Earth and on Mars and the differences may have implications for the accretion of the two planets and the formation of their atmospheres. The Earth's mantle appears to contain at least several times the water content of the Martian mantle even accounting for differences in plate tectonics. One explanation is that the Earth's surface melted during accretion, as a result of development of a steam atmosphere, thereby allowing impact-devolitalized water at the surface to dissolve into the Earth's interior. In contrast, because of Mars' smaller size and greater distance from the Sun, the Martian surface may not have melted, so that the devolatilized water could not dissolve into the surface. A second possibility is suggested by the siderophile elements in the Earth's mantle, which indicates the Earth acquired a volatile-rich veneer after the core formed. Mars may have acquired a late volatile-rich veneer, but it did not get folded into the interior as with the Earth, but instead remained as a water rich veneer. This perception of Mars with a wet surface but dry interior is consistent with our knowledge of Mars' geologic history.

Copepod communities from surface and ground waters in the everglades, south Florida

USGS Publications Warehouse

Bruno, M.C.; Cunningham, K.J.; Perry, S.A.

2003-01-01

We studied species composition and individual abundance of copepods in the surficial aquifer northeast of Everglades National Park. We identified the spatial distribution of subsurface habitats by assessing the depth of the high porosity layers in the limestone along a canal system, and we used copepods to assess the exchange between surface water and ground water along canal banks, at levels in the wells where high porosity connections to the canals exist. Surface- and ground-water taxa were defined, and species composition was related to areal position, sampling depth, and time. Subsurface copepod communities were dominated by surface copepods that disperse into the aquifer following the groundwater seepage along canal L-31N. The similarities in species composition between wells along canal reaches, suggest that copepods mainly enter ground water horizontally along canals via active and passive dispersal. Thus, the copepod populations indicate continuous connections between surface- and ground waters. The most abundant species were Orthocyclops modestus, Arctodiaptomus floridanus, Mesocyclops edax, and Thermocyclops parvus, all known in literature from surface habitats; however, these species have been collected in ground water in ENP. Only two stygophiles were collected: Diacylcops nearcticus and Diacyclops crassicaudis brachycercus. Restoration of the Everglades ecosystem requires a mosaic of data to reveal a complete picture of this complex system. The use of copepods as indicators of seepage could be a tool in helping to assess the direction and the duration of surface and ground water exchange.

Distribution of icy particles across Enceladus' surface as derived from Cassini-VIMS measurements

USGS Publications Warehouse

Jaumann, R.; Stephan, K.; Hansen, G.B.; Clark, R.N.; Buratti, B.J.; Brown, R.H.; Baines, K.H.; Newman, S.F.; Bellucci, G.; Filacchione, G.; Coradini, A.; Cruikshank, D.P.; Griffith, C.A.; Hibbitts, C.A.; McCord, T.B.; Nelson, R.M.; Nicholson, P.D.; Sotin, Christophe; Wagner, R.

2008-01-01

The surface of Enceladus consists almost completely of water ice. As the band depths of water ice absorptions are sensitive to the size of particles, absorptions can be used to map variations of icy particles across the surface. The Visual and Infrared Mapping Spectrometer (VIMS) observed Enceladus with a high spatial resolution during three Cassini flybys in 2005 (orbits EN 003, EN 004 and EN 011). Based on these data we measured the band depths of water ice absorptions at 1.04, 1.25, 1.5, and 2 ??m. These band depths were compared to water ice models that represent theoretically calculated reflectance spectra for a range of particle diameters between 2 ??m and 1 mm. The agreement between the experimental (VIMS) and model values supports the assumption that pure water ice characterizes the surface of Enceladus and therefore that variations in band depth correspond to variations in water ice particle diameters. Our measurements show that the particle diameter of water ice increases toward younger tectonically altered surface units with the largest particles exposed in relatively "fresh" surface material. The smallest particles were generally found in old densely cratered terrains. The largest particles (???0.2 mm) are concentrated in the so called "tiger stripes" at the south pole. In general, the particle diameters are strongly correlated with geologic features and surface ages, indicating a stratigraphic evolution of the surface that is caused by cryovolcanic resurfacing and impact gardening. ?? 2007 Elsevier Inc. All rights reserved.

A WATERSHED-LEVEL APPROACH TO STUDY THE PUTATIVE RELATIONSHIPS BETWEEN LANDUSE CHANGE AND SURFACE WATER FLOW ALTERATION

EPA Science Inventory

Inter-generationally prudent management of watershed resources will require attention to the interdependence between shifting landuse distributions and their effects on watershed hydrology. Development and increased proportion of impervious surface area has been found to alte lan...

Roles for Cell Wall Glycopeptidolipid in Surface Adherence and Planktonic Dispersal of Mycobacterium avium

EPA Science Inventory

The opportunistic pathogen Mycobacterium avium is a significant inhabitant of biofilms in drinking water distribution systems. M. avium expresses on its cell surface serovar-specific glycopeptidolipids (ssGPLs). Studies have implicated the core GPL in biofilm formation by M. aviu...

Quantifying the Consumptive Landscape in the Potomac Watershed Upstream From Washington DC

NASA Astrophysics Data System (ADS)

Kearns, M.; Zegre, N.; Fernandez, R.

2017-12-01

Some of the largest and fastest-growing eastern cities depend upon Appalachian headwaters for their fresh water. Today's relative abundance of water may be at risk: changes in climate and land use could alter the availability of surface water and human consumption could increase to meet the needs of a growing population and economy. Neither the supply of surface water nor the various withdrawals that support our population, irrigation, energy, and industry are distributed uniformly throughout our watersheds. This study correlates surface water withdrawals, consumptive use coefficients, and land-use/land-cover datasets to create a model for quantifying anthropogenic water consumption. The model suggests a method for downscaling and redistributing USGS county-level surface water withdrawals to 30 meter cells. Initially completed for the Potomac River watershed upstream from Washington DC's public supply intake, this approach could easily scale regionally or nationally. When combined with runoff estimates over the same landscape, the net-production or net-consumption of an area of interest may be calculated at high resolution. By better understanding the spatial relationship between hydrologic supply and demand, we can seek to improve the efficiency and security of our water resources.

Pharmaceuticals and personal care products (PPCPs) and artificial sweeteners (ASs) in surface and ground waters and their application as indication of wastewater contamination.

PubMed

Yang, Yuan-Yuan; Zhao, Jian-Liang; Liu, You-Sheng; Liu, Wang-Rong; Zhang, Qian-Qian; Yao, Li; Hu, Li-Xin; Zhang, Jin-Na; Jiang, Yu-Xia; Ying, Guang-Guo

2018-03-01

We systematically investigated the occurrence and distribution of 93 pharmaceuticals and personal care products (PPCPs) and 5 artificial sweeteners (ASs) in surface water and groundwater of Dongjiang River basin in south China. In surface water, 52 compounds were detected with median concentrations ranging from 0.06ng/L to 504ng/L, while in groundwater, 33 compounds were detected with concentrations up to 4580ng/L for acesulfame. PPCPs and ASs were widely detected in the surface water and groundwater samples, which indicated contamination by domestic wastewater in the surface water and groundwater of Dongjiang River basin. Temporal and spatial variations of the detected chemicals were observed in surface water. Acesulfame, sucralose and cyclamate can be used as wastewater indicators to imply contamination in groundwater caused by domestic wastewater due to their hydrophilicity, anthropogenic sources and ubiquity in groundwater. Moreover, the detection of the readily degradable ASs, cyclamate, was a strong indication of untreated wastewater in groundwater. Sucralose was found to be a suitable wastewater indicator to reflect domestic wastewater contamination in surface water and groundwater qualitatively and quantitatively, and it can be used to evaluate wastewater burden in surface water and groundwater of Dongjiang River basin. The wastewater burden data from this survey implied serious contamination in surface water and groundwater by domestic wastewater at Shima River, a tributary of the Dongjiang River. The findings from this study suggest that the selected labile and conservative chemicals can be used as indication of wastewater contamination for aquatic environments qualitatively and quantitatively. Copyright © 2017 Elsevier B.V. All rights reserved.

Water Contact Angle Dependence with Hydroxyl Functional Groups on Silica Surfaces under CO2 Sequestration Conditions.

PubMed

Chen, Cong; Zhang, Ning; Li, Weizhong; Song, Yongchen

2015-12-15

Functional groups on silica surfaces under CO2 sequestration conditions are complex due to reactions among supercritical CO2, brine and silica. Molecular dynamics simulations have been performed to investigate the effects of hydroxyl functional groups on wettability. It has been found that wettability shows a strong dependence on functional groups on silica surfaces: silanol number density, space distribution, and deprotonation/protonation degree. For neutral silica surfaces with crystalline structure (Q(3), Q(3)/Q(4), Q(4)), as silanol number density decreases, contact angle increases from 33.5° to 146.7° at 10.5 MPa and 318 K. When Q(3) surface changes to an amorphous structure, water contact angle increases 20°. Water contact angle decreases about 12° when 9% of silanol groups on Q(3) surface are deprotonated. When the deprotonation degree increases to 50%, water contact angle decreases to 0. The dependence of wettability on silica surface functional groups was used to analyze contact angle measurement ambiguity in literature. The composition of silica surfaces is complicated under CO2 sequestration conditions, the results found in this study may help to better understand wettability of CO2/brine/silica system.

Thermodynamic properties of water solvating biomolecular surfaces

NASA Astrophysics Data System (ADS)

Heyden, Matthias

Changes in the potential energy and entropy of water molecules hydrating biomolecular interfaces play a significant role for biomolecular solubility and association. Free energy perturbation and thermodynamic integration methods allow calculations of free energy differences between two states from simulations. However, these methods are computationally demanding and do not provide insights into individual thermodynamic contributions, i.e. changes in the solvent energy or entropy. Here, we employ methods to spatially resolve distributions of hydration water thermodynamic properties in the vicinity of biomolecular surfaces. This allows direct insights into thermodynamic signatures of the hydration of hydrophobic and hydrophilic solvent accessible sites of proteins and small molecules and comparisons to ideal model surfaces. We correlate dynamic properties of hydration water molecules, i.e. translational and rotational mobility, to their thermodynamics. The latter can be used as a guide to extract thermodynamic information from experimental measurements of site-resolved water dynamics. Further, we study energy-entropy compensations of water at different hydration sites of biomolecular surfaces. This work is supported by the Cluster of Excellence RESOLV (EXC 1069) funded by the Deutsche Forschungsgemeinschaft.

Involving regional expertise in nationwide modeling for adequate prediction of climate change effects on different demands for fresh water

NASA Astrophysics Data System (ADS)

de Lange, Wim; Prinsen, Geert.; Hoogewoud, Jacco; Veldhuizen, Ab; Ruijgh, Erik; Kroon, Timo

2013-04-01

Nationwide modeling aims to produce a balanced distribution of climate change effects (e.g. harm on crops) and possible compensation (e.g. volume fresh water) based on consistent calculation. The present work is based on the Netherlands Hydrological Instrument (NHI, www.nhi.nu), which is a national, integrated, hydrological model that simulates distribution, flow and storage of all water in the surface water and groundwater systems. The instrument is developed to assess the impact on water use on land-surface (sprinkling crops, drinking water) and in surface water (navigation, cooling). The regional expertise involved in the development of NHI come from all parties involved in the use, production and management of water, such as waterboards, drinking water supply companies, provinces, ngo's, and so on. Adequate prediction implies that the model computes changes in the order of magnitude that is relevant to the effects. In scenarios related to drought, adequate prediction applies to the water demand and the hydrological effects during average, dry, very dry and extremely dry periods. The NHI acts as a part of the so-called Deltamodel (www.deltamodel.nl), which aims to predict effects and compensating measures of climate change both on safety against flooding and on water shortage during drought. To assess the effects, a limited number of well-defined scenarios is used within the Deltamodel. The effects on demand of fresh water consist of an increase of the demand e.g. for surface water level control to prevent dike burst, for flushing salt in ditches, for sprinkling of crops, for preserving wet nature and so on. Many of the effects are dealt with? by regional and local parties. Therefore, these parties have large interest in the outcome of the scenario analyses. They are participating in the assessment of the NHI previous to the start of the analyses. Regional expertise is welcomed in the calibration phase of NHI. It aims to reduce uncertainties by improving the rules for manmade re-direction of surface water, schematizations & parameters included in the model. This is carried out in workshops and in one-to-one expert meetings on regional models & the NHI. All results of NHI are presented on the internet and any expert may suggest improvements to the model. The final goal of the involvement of regional parties is the acceptation by decision impact receiving authorities

Surface-water investigations at Barrow, Alaska

USGS Publications Warehouse

Jones, Stanley H.

1972-01-01

The U.S. Public Health Service is currently developing plans for a long-term water supply and sewage treatment system for the village of Barrow, Alaska. To assist in planning, the U.S. Geological Survey was requested to initiate a cooperative streamflow data-collection program with the U.S. Public Health Service in June 1972 to determine the availability of surface water and the areal distribution of runoff in the Barrow area. This basic-data report summarizes the streamflow data collected from June 1 through July 10, 1972, at three gaging stations in the Barrow area (fig. 1) and discusses the future data-collection program.

Humidity-Induced Charge Leakage and Field Attenuation in Electric Field Microsensors

PubMed Central

Zhang, Haiyan; Fang, Dongming; Yang, Pengfei; Peng, Chunrong; Wen, Xiaolong; Xia, Shanhong

2012-01-01

The steady-state zero output of static electric field measuring systems often fluctuates, which is caused mainly by the finite leakage resistance of the water film on the surface of the electric field microsensor package. The water adsorption has been calculated using the Boltzmann distribution equation at various relative humidities for borosilicate glass and polytetrafluoroethylene surfaces. At various humidities, water film thickness has been calculated, and the induced charge leakage and field attenuation have been theoretically investigated. Experiments have been performed with microsensors to verify the theoretical predictions and the results are in good agreement. PMID:22666077

Occurrence, distribution and risk assessment of organophosphate esters in surface water and sediment from a shallow freshwater Lake, China.

PubMed

Xing, Liqun; Zhang, Qin; Sun, Xu; Zhu, Hongxia; Zhang, Shenghu; Xu, Huaizhou

2018-04-30

Organophosphate esters (OPEs) are ubiquitous in the environment and pose a potential threat to ecosystem and human health. This study investigated the concentrations, distributions and risk of 12 OPEs in surface water and sediment from Luoma Lake, Fangting River and Yi River. Solid-phase extraction (SPE) method were used to extract OPEs from water samples, ultrasonic process and SPE method were used to extract OPEs from sediment samples, and the extracts were finally analyzed using the HPLC-MS/MS. The results revealed that the median and maximum concentrations of ΣOPEs were 73.9 and 1066 ng/L in surface water, and were 28.7 and 35.9 ng/g in sediment, respectively. Tris(2-chloroethyl) phosphate (TCEP) and trimethyl phosphate (TMP) were the most abundant OPEs in the surface water with median concentrations of 24.3 and 16.4 ng/L in Luoma Lake, respectively. Triethyl phosphate (TEP) was the most abundant OPE in the sediment with a median concentrations of 28.9 ng/g. However, tricresyl phosphate (TCrP) and ethylhexyl diphenyl phosphate (EHDPP) predominantly contributed to the ecological risk with respective median risk quotients 0.07 and 0.01 for surface water in Luoma Lake. TEP and TCrP were the most significant contributors to the ecological risk with respective median risk quotients of 6.4 × 10 -4 and 5.6 × 10 -4 for sediment. It was also found that inflowing Fangting River could be the major pollution source to Luoma Lake. The no-cancer and carcinogenic risks of OPEs were lower than the theoretical threshold of risk. The study found that the ecological and human health risks due to the exposure to OPEs were currently acceptable. In other words, the Luoma Lake was relatively safer to use as a drinking water source in urban areas in the context of OPEs pollution. Copyright © 2018 Elsevier B.V. All rights reserved.

A Study on Water Surface Profiles of Rivers with Constriction

NASA Astrophysics Data System (ADS)

Qian, Chaochao; Yamada, Tadashi

2013-04-01

Water surface profile of rivers with constrictions is precious in both classic hydraulics and river management practice. This study was conducted to clarify the essences of the water surface profiles. 3 cases of experiments and 1D numerical calculations with different discharges were made in the study and analysis solutions of the non-linear basic equation of surface profile in varied flow without considering friction were derived. The manning's number was kept in the same in each case by using crosspiece roughness. We found a new type of water surface profile of varied flow from the results of 1D numerical calculation and that of experiments and named it as Mc curve because of its mild condition with constriction segment. This kind of curves appears as a nature phenomenon ubiquitously. The process of water surface forming is dynamic and bore occurs at the upper side of constriction during increasing discharge before the surface profile formed. As a theoretical work, 3 analysis solutions were derived included 2 physical-meaning solutions in the study by using Man-Machine system. One of the derived physical-meaning solutions was confirmed that it is validity by comparing to the results of 1D numerical calculation and that of experiments. The solution represents a flow profile from under critical condition at the upper side to super critical condition at the down side of constriction segment. The other derived physical-meaning solution represents a flow profile from super critical condition at the upper side to under critical condition at the down side of constriction segment. These two kinds of flow profiles exist in the nature but no theoretical solution can express the phenomenon. We find the depth distribution only concerned with unit width discharge distribution and critical depth under a constant discharge from the derived solutions. Therefor, the profile can be gained simply and precisely by using the theoretical solutions instead of numerical calculation even in practice.

Enhancement of the natural organic matter removal from drinking water by nanofiltration.

PubMed

Matilainen, A; Liikanen, R; Nyström, M; Lindqvist, N; Tuhkanen, T

2004-03-01

Finnish surface waters are abundant in natural organic matter. Natural organic matter can be removed from drinking water in a water treatment process by coagulation and filtration. The standard treatment operations are not able to remove the smallest molar mass fraction of organic matter and the intermediate molar mass matter is only partly removed. The removal of residual natural organic matter from drinking water by nanofiltration was evalueted in this study. Three different nanofiltration membranes were compared in filtering six pre-treated surface waters. The total organic carbon content of the feed waters varied from 2.0 to 4.2 mg l(-1). Other water quality parameters measured were conductivity, alkalinity, hardness, UV-absorbance, SUVA, E2/E3 value and molecular size distribution by high-performance size-exclusion chromatography. The natural organic matter removal efficiencies of the membranes were good and varied between 100% and 49%, and between 85% and 47% according to molecular size distribution and total organic carbon measurements, respectively. Removal of different molecular size fractions varied from 100% to 56%, 100% to 54% and 88% to 19%, regarding high molar mass, intermediate molar mass and low molar mass organic matter, respectively. The Desal-5 DL membrane produced the highest natural organic matter removals.

Origin and spatial-temporal distribution of faecal bacteria in a bay of Lake Geneva, Switzerland.

PubMed

Poté, John; Goldscheider, Nico; Haller, Laurence; Zopfi, Jakob; Khajehnouri, Fereidoun; Wildi, Walter

2009-07-01

The origin and distribution of microbial contamination in Lake Geneva's most polluted bay were assessed using faecal indicator bacteria (FIB). The lake is used as drinking water, for recreation and fishing. During 1 year, water samples were taken at 23 points in the bay and three contamination sources: a wastewater treatment plant (WWTP), a river and a storm water outlet. Analyses included Escherichia coli, enterococci (ENT), total coliforms (TC), and heterotrophic plate counts (HPC). E. coli input flux rates from the WWTP can reach 2.5 x 10(10) CFU/s; those from the river are one to three orders of magnitude lower. Different pathogenic Salmonella serotypes were identified in water from these sources. FIB levels in the bay are highly variable. Results demonstrate that (1) the WWTP outlet at 30 m depth impacts near-surface water quality during holomixis in winter; (2) when the lake is stratified, the effluent water is generally trapped below the thermocline; (3) during major floods, upwelling across the thermocline may occur; (4) the river permanently contributes to contamination, mainly near the river mouth and during floods, when the storm water outlet contributes additionally; (5) the lowest FIB levels in the near-surface water occur during low-flow periods in the bathing season.

Surface composition of Europa based on VLT observations

NASA Astrophysics Data System (ADS)

Ligier, N.; Poulet, F.; Carter, J.

2016-12-01

Jupiter's moon Europa may harbor a global salty ocean under an 80-170 km thick outer layer consisting of an icy crust (Anderson et al. 1998). Meanwhile, the 10-50 My old surface, dated by cratering rates (Pappalardo et al. 1999) implies rapid surface recycling and reprocessing that could result in tectonic activity (Kattenhorn et al. 2014) and plumes (Roth et al. 2014). The surface could thus exhibit fingerprints of chemical species, as minerals characteristics of an ocean-mantle interaction and/or organics of exobiological interest, directly originating from the subglacial ocean. In order to re-investigate the composition of Europa's surface, a global mapping campaign of the satellite was performed with the near-infrared integral field spectrograph SINFONI on the Very Large Telescope (VLT) in Chile. The high spectral binning of this instrument (0.5 nm) and large signal noise ratio in comparison to previous observations are adequate to detect sharp absorptions in the wavelength range 1.45-2.45 μm. In addition, the spatially resolved spectra we obtained over five epochs nearly cover the entire surface of Europa with a pixel scale of 12.5 by 25 m.a.s ( 35 by 70 km on Europa's surface), thus permitting a global scale study. Several icy and non-icy compounds were detected and mapped at <100 km resolution. They are unevenly distributed on the moon's surface. Amorphous and crystalline water ice are both present and, in spite of a particularly strong amorphization process likely engendered by the Io plasma torus, the crystalline form is found to be approximately twice as abundant as the amorphous ice based on the analysis of the 1.65 μm band. If the surface is dominated by small and mid-sized water ice grains (25-200 μm), crystalline water-ice grains exhibit spatial inhomogeneities in their distribution. The sulfuric acid hydrate distribution exhibits the typical "bullseye" feature on the trailing hemisphere. The presence of Mg-bearing chlorinated salts (chloride, chlorate, and perchlorate) is supported by linear spectral modeling of the data, while the presence of sulfate salts is challenged. The distribution of some of these species is inconsistent with exogenic processes mainly impacting the trailing orbital hemisphere. These species may be traces of endogenous processes occurring on Europa.

Water-quality assessment of part of the Upper Mississippi River basin, Minnesota and Wisconsin, environmental setting and study design

USGS Publications Warehouse

Stark, J.R.; Andrews, W.J.; Fallon, J.D.; Fong, A.L.; Goldstein, R.M.; Hanson, P.E.; Kroening, S.E.; Lee, K.E.

1996-01-01

Environmental stratification consists of dividing the study unit into subareas with homogeneous characteristics to assess natural and anthropogenic factors affecting water quality. The assessment of water quality in streams and in aquifers is based on the sampling design that compares water quality within homogeneous subareas defined by subbasins or aquifer boundaries. The study unit is stratified at four levels for the surface-water component: glacial deposit composition, surficial geology, general land use and land cover, and secondary land use. Ground-water studies emphasize shallow ground water where quality is most likely influenced by overlying land use and land cover. Stratification for ground-water sampling is superimposed on the distribution of shallow aquifers. For each aquifer and surface-water basin this stratification forms the basis for the proposed sampling design used in the Upper Mississippi River Basin National Water-Quality Assessment.

Users manual for the NASA Lewis three-dimensional ice accretion code (LEWICE 3D)

NASA Technical Reports Server (NTRS)

Bidwell, Colin S.; Potapczuk, Mark G.

1993-01-01

A description of the methodology, the algorithms, and the input and output data along with an example case for the NASA Lewis 3D ice accretion code (LEWICE3D) has been produced. The manual has been designed to help the user understand the capabilities, the methodologies, and the use of the code. The LEWICE3D code is a conglomeration of several codes for the purpose of calculating ice shapes on three-dimensional external surfaces. A three-dimensional external flow panel code is incorporated which has the capability of calculating flow about arbitrary 3D lifting and nonlifting bodies with external flow. A fourth order Runge-Kutta integration scheme is used to calculate arbitrary streamlines. An Adams type predictor-corrector trajectory integration scheme has been included to calculate arbitrary trajectories. Schemes for calculating tangent trajectories, collection efficiencies, and concentration factors for arbitrary regions of interest for single droplets or droplet distributions have been incorporated. A LEWICE 2D based heat transfer algorithm can be used to calculate ice accretions along surface streamlines. A geometry modification scheme is incorporated which calculates the new geometry based on the ice accretions generated at each section of interest. The three-dimensional ice accretion calculation is based on the LEWICE 2D calculation. Both codes calculate the flow, pressure distribution, and collection efficiency distribution along surface streamlines. For both codes the heat transfer calculation is divided into two regions, one above the stagnation point and one below the stagnation point, and solved for each region assuming a flat plate with pressure distribution. Water is assumed to follow the surface streamlines, hence starting at the stagnation zone any water that is not frozen out at a control volume is assumed to run back into the next control volume. After the amount of frozen water at each control volume has been calculated the geometry is modified by adding the ice at each control volume in the surface normal direction.

The influence of small mammal burrowing activity on water storage at the Hanford Site

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

Landeen, D.S.

The amount and rate at which water may penetrate a protective barrier and come into contact with buried radioactive waste is a major concern. Because burrowing animals eventually will reside on the surface of any protective barrier, the effect these burrow systems may have on the loss or retention of water needs to be determined. The first section of this document summarizes the known literature relative to small mammals and the effects that burrowing activities have on water distribution, infiltration, and the overall impact of burrows on the ecosystem. Topics that are summarized include burrow air pressures, airflow, burrow humidity,more » microtopography, mounding, infiltration, climate, soil evaporation, and discussions of large pores relative to water distribution. The second section of this document provides the results of the study that was conducted at the Hanford Site to determine what effect small mammal burrows have on water storage. This Biointrusion task is identified in the Permanent Isolation Surface Barrier Development Plan in support of protective barriers. This particular animal intrusion task is one part of the overall animal intrusion task identified in Animal Intrusion Test Plan.« less

Water balance model for mean annual hydrogen and oxygen isotope distributions in surface waters of the contiguous United States

NASA Astrophysics Data System (ADS)

Bowen, Gabriel J.; Kennedy, Casey D.; Liu, Zhongfang; Stalker, Jeremy

2011-12-01

The stable H and O isotope composition of river and stream water records information on runoff sources and land-atmosphere water fluxes within the catchment and is a potentially powerful tool for network-based monitoring of ecohydrological systems. Process-based hydrological models, however, have thus far shown limited power to replicate observed large-scale variation in U.S. surface water isotope ratios. Here we develop a geographic information system-based model to predict long-term annual average surface water isotope ratios across the contiguous United States. We use elevation-explicit, gridded precipitation isotope maps as model input and data from a U.S. Geological Survey monitoring program for validation. We find that models incorporating monthly variation in precipitation-evapotranspiration (P-E) amounts account for the majority (>89%) of isotopic variation and have reduced regional bias relative to models that do not consider intra-annual P-E effects on catchment water balance. Residuals from the water balance model exhibit strong spatial patterning and correlations that suggest model residuals isolate additional hydrological signal. We use interpolated model residuals to generate optimized prediction maps for U.S. surface water δ2H and δ18O values. We show that the modeled surface water values represent a relatively accurate and unbiased proxy for drinking water isotope ratios across the United States, making these data products useful in ecological and criminal forensics applications that require estimates of the local environmental water isotope variation across large geographic regions.

Assessing the occurrence and distribution of pyrethroids in water and suspended sediments

USGS Publications Warehouse

Hladik, M.L.; Kuivila, K.M.

2009-01-01

The distribution of pyrethroid insecticides in the environment was assessed by separately measuring concentrations in the dissolved and suspended sediment phases of surface water samples. Filtered water was extracted by HLB solid-phase extraction cartridges, while the sediment on the filter was sonicated and cleaned up using carbon and aluminum cartridges. Detection limits for the 13 pyrethroids analyzed by gas chromatography-tandem mass spectrometry were 0.5 to 1 ng L-1 for water and 2 to 6 ng g for the suspended sediments. Seven pyrethroids were detected in six water samples collected from either urban or agricultural creeks, with bifenthrin detected the most frequently and at the highest concentrations. In spiked water samples and field samples, the majority of the pyrethroids were associated with the suspended sediments.

Distribution of borates around point source injections in wood members exposed outside

Treesearch

Rodney C. De Groot; Colin C. Felton; Douglas M. Crawford

2000-01-01

In bridge timbers, wood decay is usually found where water has accessed the end-grain surfaces. In preservative-treated members, end-grain surfaces are most likely to be those resulting from on-site framing cuts or borings. Because these at-risk surfaces are easy to see, it seems feasible to establish a program where diffusible preservatives are repetitively inserted...

Bacterial community structure in the drinking water microbiome is governed by filtration processes.

PubMed

Pinto, Ameet J; Xi, Chuanwu; Raskin, Lutgarde

2012-08-21

The bacterial community structure of a drinking water microbiome was characterized over three seasons using 16S rRNA gene based pyrosequencing of samples obtained from source water (a mix of a groundwater and a surface water), different points in a drinking water plant operated to treat this source water, and in the associated drinking water distribution system. Even though the source water was shown to seed the drinking water microbiome, treatment process operations limit the source water's influence on the distribution system bacterial community. Rather, in this plant, filtration by dual media rapid sand filters played a primary role in shaping the distribution system bacterial community over seasonal time scales as the filters harbored a stable bacterial community that seeded the water treatment processes past filtration. Bacterial taxa that colonized the filter and sloughed off in the filter effluent were able to persist in the distribution system despite disinfection of finished water by chloramination and filter backwashing with chloraminated backwash water. Thus, filter colonization presents a possible ecological survival strategy for bacterial communities in drinking water systems, which presents an opportunity to control the drinking water microbiome by manipulating the filter microbial community. Grouping bacterial taxa based on their association with the filter helped to elucidate relationships between the abundance of bacterial groups and water quality parameters and showed that pH was the strongest regulator of the bacterial community in the sampled drinking water system.

Occurrence survey and spatial distribution of perfluoroalkyl and polyfluoroalkyl surfactants in groundwater, surface water, and sediments from tropical environments.

PubMed

Munoz, Gabriel; Labadie, Pierre; Botta, Fabrizio; Lestremau, François; Lopez, Benjamin; Geneste, Emmanuel; Pardon, Patrick; Dévier, Marie-Hélène; Budzinski, Hélène

2017-12-31

The occurrence and spatial distribution of 22 selected perfluoroalkyl and polyfluoroalkyl substances (PFASs) in surface water (n=75), groundwater (n=80) and surficial sediment (n=15) were investigated for the first time in the tropical areas constituted by the French Overseas Territories (French Guiana, Guadeloupe, Martinique, Mayotte and Reunion). Descriptive statistics and correlations between PFASs were evaluated through the use of specific statistical treatments to handle left-censored data ("non-detects"). PFASs were ubiquitous in these samples and detection frequencies as high as 79% for perfluorooctane sulfonate (PFOS) and 65% for perfluorooctanoate (PFOA) were reported in surface waters. ∑PFASs was in the range

Probing the water distribution in porous model sands with two immiscible fluids: A nuclear magnetic resonance micro-imaging study

NASA Astrophysics Data System (ADS)

Lee, Bum Han; Lee, Sung Keun

2017-10-01

The effect of the structural heterogeneity of porous networks on the water distribution in porous media, initially saturated with immiscible fluid followed by increasing durations of water injection, remains one of the important problems in hydrology. The relationship among convergence rates (i.e., the rate of fluid saturation with varying injection time) and the macroscopic properties and structural parameters of porous media have been anticipated. Here, we used nuclear magnetic resonance (NMR) micro-imaging to obtain images (down to ∼50 μm resolution) of the distribution of water injected for varying durations into porous networks that were initially saturated with silicone oil. We then established the relationships among the convergence rates, structural parameters, and transport properties of porous networks. The volume fraction of the water phase increases as the water injection duration increases. The 3D images of the water distributions for silica gel samples are similar to those of the glass bead samples. The changes in water saturation (and the accompanying removal of silicone oil) and the variations in the volume fraction, specific surface area, and cube-counting fractal dimension of the water phase fit well with the single-exponential recovery function { f (t) = a [ 1 -exp (- λt) ] } . The asymptotic values (a, i.e., saturated value) of the properties of the volume fraction, specific surface area, and cube-counting fractal dimension of the glass bead samples were greater than those for the silica gel samples primarily because of the intrinsic differences in the porous networks and local distribution of the pore size and connectivity. The convergence rates of all of the properties are inversely proportional to the entropy length and permeability. Despite limitations of the current study, such as insufficient resolution and uncertainty for the estimated parameters due to sparsely selected short injection times, the observed trends highlight the first analyses of the cube-counting fractal dimension (and other structural properties) and convergence rates in porous networks consisting of two fluid components. These results indicate that the convergence rates correlate with the geometric factor that characterizes the porous networks and transport property of the porous networks.

Determination of Large-Scale Cloud Ice Water Concentration by Combining Surface Radar and Satellite Data in Support of ARM SCM Activities

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

Liu, Guosheng

2013-03-15

Single-column modeling (SCM) is one of the key elements of Atmospheric Radiation Measurement (ARM) research initiatives for the development and testing of various physical parameterizations to be used in general circulation models (GCMs). The data required for use with an SCM include observed vertical profiles of temperature, water vapor, and condensed water, as well as the large-scale vertical motion and tendencies of temperature, water vapor, and condensed water due to horizontal advection. Surface-based measurements operated at ARM sites and upper-air sounding networks supply most of the required variables for model inputs, but do not provide the horizontal advection term ofmore » condensed water. Since surface cloud radar and microwave radiometer observations at ARM sites are single-point measurements, they can provide the amount of condensed water at the location of observation sites, but not a horizontal distribution of condensed water contents. Consequently, observational data for the large-scale advection tendencies of condensed water have not been available to the ARM cloud modeling community based on surface observations alone. This lack of advection data of water condensate could cause large uncertainties in SCM simulations. Additionally, to evaluate GCMs cloud physical parameterization, we need to compare GCM results with observed cloud water amounts over a scale that is large enough to be comparable to what a GCM grid represents. To this end, the point-measurements at ARM surface sites are again not adequate. Therefore, cloud water observations over a large area are needed. The main goal of this project is to retrieve ice water contents over an area of 10 x 10 deg. surrounding the ARM sites by combining surface and satellite observations. Built on the progress made during previous ARM research, we have conducted the retrievals of 3-dimensional ice water content by combining surface radar/radiometer and satellite measurements, and have produced 3-D cloud ice water contents in support of cloud modeling activities. The approach of the study is to expand a (surface) point measurement to an (satellite) area measurement. That is, the study takes the advantage of the high quality cloud measurements (particularly cloud radar and microwave radiometer measurements) at the point of the ARM sites. We use the cloud ice water characteristics derived from the point measurement to guide/constrain a satellite retrieval algorithm, then use the satellite algorithm to derive the 3-D cloud ice water distributions within an 10° (latitude) x 10° (longitude) area. During the research period, we have developed, validated and improved our cloud ice water retrievals, and have produced and archived at ARM website as a PI-product of the 3-D cloud ice water contents using combined satellite high-frequency microwave and surface radar observations for SGP March 2000 IOP and TWP-ICE 2006 IOP over 10 deg. x 10 deg. area centered at ARM SGP central facility and Darwin sites. We have also worked on validation of the 3-D ice water product by CloudSat data, synergy with visible/infrared cloud ice water retrievals for better results at low ice water conditions, and created a long-term (several years) of ice water climatology in 10 x 10 deg. area of ARM SGP and TWP sites and then compared it with GCMs.« less

Water mass circulation and weathering inputs in the Labrador Sea based on coupled Hf-Nd isotope compositions and rare earth element distributions

NASA Astrophysics Data System (ADS)

Filippova, Alexandra; Frank, Martin; Kienast, Markus; Rickli, Jörg; Hathorne, Ed; Yashayaev, Igor M.; Pahnke, Katharina

2017-02-01

The Labrador Sea is one of the key areas for deep water formation driving the Atlantic thermohaline circulation and thus plays an important role in Northern Hemisphere climatic fluctuations. In order to better constrain the overturning processes and the origins of the distinct water masses, combined dissolved Hf-Nd isotopic compositions and rare earth element (REE) distribution patterns were obtained from four water depth profiles along a section across the Labrador Sea. These were complemented by one surface sample off the southern tip of Greenland, three shallow water samples off the coast of Newfoundland, and two deep water samples off Nova Scotia. Although light REEs are markedly enriched in the surface waters off the coast of Newfoundland compared to north Atlantic waters, the REE concentration profiles are essentially invariant throughout the water column across the Labrador Sea. The hafnium concentrations of surface waters exhibit a narrow range between 0.6 and 1 pmol/kg but are not significantly higher than at depth. Neodymium isotope signatures (ɛNd) vary from unradiogenic values between -16.8 and -14.9 at the surface to more radiogenic values near -11.0 at the bottom of the Labrador Sea mainly reflecting the advection of the Denmark Strait Overflow Water and North East Atlantic Deep Water, the signatures of which are influenced by weathering contributions from Icelandic basalts. Unlike Nd, water column radiogenic Hf isotope signatures (ɛHf) are more variable representing diverse weathering inputs from the surrounding landmasses. The least radiogenic seawater ɛHf signatures (up to -11.7) are found in surface waters close to Greenland and near the Canadian margin. This reflects the influence of recirculating Irminger Current Waters, which are affected by highly unradiogenic inputs from Greenland. A three to four ɛHf unit difference is observed between Denmark Strait Overflow Water (ɛHf ∼ -4) and North East Atlantic Deep Water (ɛHf ∼ -0.1), although their source waters have essentially the same ɛNd signature. This most likely reflects different weathering signals of hafnium delivered to Denmark Strait Overflow Water and North East Atlantic Deep Water (incongruent weathering of old rocks from Greenland versus basaltic rocks from Iceland). In addition, the ɛHf data resolve two layers within the main body of Labrador Sea Water not visible in the ɛNd distribution, which are shallow Labrador Sea Water (ɛHf ∼ -2) and deep Labrador Sea Water (ɛHf ∼ -4.5). The latter layer was formed between the late 1980's and mid 1990's during the last cold state of the Labrador Sea and underwent substantial modification since its formation through the admixture of Irminger Water, Iceland Slope Water and North East Atlantic Deep Water, which is reflected in its less radiogenic ɛHf signature. The overall behavior of Hf in the water column suggests its higher sensitivity to local changes in weathering inputs on annual to decadal timescales. Although application of Hf isotopes as a tracer for global water mass mixing is complicated by their susceptibility to incongruent weathering inputs they are a promising tracer of local processes in restricted basins such as the Labrador Sea.

Water security-National and global issues

USGS Publications Warehouse

Tindall, James A.; Campbell, Andrew A.

2010-01-01

Potable or clean freshwater availability is crucial to life and economic, environmental, and social systems. The amount of freshwater is finite and makes up approximately 2.5 percent of all water on the Earth. Freshwater supplies are small and randomly distributed, so water resources can become points of conflict. Freshwater availability depends upon precipitation patterns, changing climate, and whether the source of consumed water comes directly from desalination, precipitation, or surface and (or) groundwater. At local to national levels, difficulties in securing potable water sources increase with growing populations and economies. Available water improves living standards and drives urbanization, which increases average water consumption per capita. Commonly, disruptions in sustainable supplies and distribution of potable water and conflicts over water resources become major security issues for Government officials. Disruptions are often influenced by land use, human population, use patterns, technological advances, environmental impacts, management processes and decisions, transnational boundaries, and so forth.

Statistical approaches used to assess and redesign surface water-quality-monitoring networks.

PubMed

Khalil, B; Ouarda, T B M J

2009-11-01

An up-to-date review of the statistical approaches utilized for the assessment and redesign of surface water quality monitoring (WQM) networks is presented. The main technical aspects of network design are covered in four sections, addressing monitoring objectives, water quality variables, sampling frequency and spatial distribution of sampling locations. This paper discusses various monitoring objectives and related procedures used for the assessment and redesign of long-term surface WQM networks. The appropriateness of each approach for the design, contraction or expansion of monitoring networks is also discussed. For each statistical approach, its advantages and disadvantages are examined from a network design perspective. Possible methods to overcome disadvantages and deficiencies in the statistical approaches that are currently in use are recommended.

Water interaction with hydrophobic and hydrophilic soot particles.

PubMed

Popovicheva, Olga; Persiantseva, Natalia M; Shonija, Natalia K; DeMott, Paul; Koehler, Kirsten; Petters, Markus; Kreidenweis, Sonia; Tishkova, Victoria; Demirdjian, Benjamin; Suzanne, Jean

2008-05-07

The interaction of water with laboratory soots possessing a range of properties relevant for atmospheric studies is examined by two complementary methods: gravimetrical measurement of water uptake coupled with chemical composition and porosity analysis and HTDMA (humidified tandem differential mobility analyzer) inference of water uptake accompanied by separate TEM (transmission electron microscopy) analysis of single particles. The first method clarifies the mechanism of water uptake for bulk soot and allows the classification of soot with respect to its hygroscopicity. The second method highlights the dependence of the soot aerosol growth factor on relative humidity (RH) for quasi-monodisperse particles. Hydrophobic and hydrophilic soot are qualitatively defined by their water uptake and surface polarity: laboratory soot particles are thus classified from very hydrophobic to very hydrophilic. Thermal soot particles produced from natural gas combustion are classified as hydrophobic with a surface of low polarity since water is found to cover only half of the surface. Graphitized thermal soot particles are proposed for comparison as extremely hydrophobic and of very low surface polarity. Soot particles produced from laboratory flame of TC1 aviation kerosene are less hydrophobic, with their entire surface being available for statistical monolayer water coverage at RH approximately 10%. Porosity measurements suggest that, initially, much of this surface water resides within micropores. Consequently, the growth factor increase of these particles to 1.07 at RH > 80% is attributed to irreversible swelling that accompanies water uptake. Hysteresis of adsorption/desorption cycles strongly supports this conclusion. In contrast, aircraft engine soot, produced from burning TC1 kerosene in a gas turbine engine combustor, has an extremely hydrophilic surface of high polarity. Due to the presence of water soluble organic and inorganic material it can be covered by many water layers even below water saturation conditions. This soot demonstrates a gradual diameter growth factor (D(wet)/D(dry)) increase up to 1.22 at 93% relative humidity, most likely due to the presence of single particles with water soluble material heterogeneously distributed over their surface.

Surface Characterization on Corrosion By-products on Cu in Drinking Water Pipes

EPA Science Inventory

Copper is widely used in house-hold plumbing due to its anti-corrosion property. However, as water travels within the distribution system into corroded copper pipes, copper may be released into consumer’s tap causing major problems. In an attempt to understand the mechanism and...

Identifying riparian zones appropriate for installation of saturated buffers: A multi-watershed assessment

USDA-ARS?s Scientific Manuscript database

Saturated riparian buffers are a new type of conservation practice that divert a portion of subsurface tile drainage from discharge to surface water into distribution pipes that discharge tile water into riparian soils. This enables natural processes of biological uptake and denitrification to decre...

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...

The mixing of rain with near-surface water

Treesearch

Dennis F. Houk

1976-01-01

Rain experiments were run with various temperature differences between the warm rain and the cool receiving water. The rain intensities were uniform and the raindrop sizes were usually uniform (2.2 mm, 3.6 mm, and 5.5 mm diameter drops). Two drop size distributions were also used.

Water resources by orbital remote sensing: Examples of applications

NASA Technical Reports Server (NTRS)

Martini, P. R. (Principal Investigator)

1984-01-01

Selected applications of orbital remote sensing to water resources undertaken by INPE are described. General specifications of Earth application satellites and technical characteristics of LANDSAT 1, 2, 3, and 4 subsystems are described. Spatial, temporal and spectral image attributes of water as well as methods of image analysis for applications to water resources are discussed. Selected examples are referred to flood monitoring, analysis of water suspended sediments, spatial distribution of pollutants, inventory of surface water bodies and mapping of alluvial aquifers.

Synoptic Sampling to Determine Distributed Groundwater-Surface Water Nitrate Loading and Removal Potential Along a Lowland River

NASA Astrophysics Data System (ADS)

Pai, Henry; Villamizar, Sandra R.; Harmon, Thomas C.

2017-11-01

Delineating pollutant reactive transport pathways that connect local land use patterns to surface water is an important goal. This work illustrates high-resolution river mapping of salinity or specific conductance (SC) and nitrate (NO3-) as a potential part of achieving this goal. We observed longitudinal river SC and nitrate distributions using high-resolution synoptic in situ sensing along the lower Merced River (38 river km) in Central California (USA) from 2010 to 2012. We calibrated a distributed groundwater-surface water (GW-SW) discharge model for a conservative solute using 13 synoptic SC sampling events at flows ranging from 1.3 to 31.6 m3 s-1. Nitrogen loads ranged from 0.3 to 1.6 kg N d-1 and were greater following an extended high flow period during a wet winter. Applying the distributed GW-SW discharge estimates to a simplistic reactive nitrate transport model, the model reproduced observed river nitrate distribution well (RRMSE = 5-21%), with dimensionless watershed-averaged nitrate removal (kt) ranging from 0 to 0.43. Estimates were uncertain due to GW nitrate data variability, but the resulting range was consistent with prior removal estimates. At the segment scale, estimated GW-SW nitrate loading ranged from 0 to 17 g NO3- s-1 km-1. Local loading peaked near the middle of the study reach, a location that coincides with a shallow clay lens and with confined animal feed operations in close proximity to the river. Overall, the results demonstrate the potential for high-resolution synoptic monitoring to support GW-SW modeling efforts aimed at understanding and managing nonpoint source pollution.

Role of subsurface physics in the assimilation of surface soil moisture observations

USDA-ARS?s Scientific Manuscript database

Soil moisture controls the exchange of water and energy between the land surface and the atmosphere and exhibits memory that may be useful for climate prediction at monthly time scales. Though spatially distributed observations of soil moisture are increasingly becoming available from remotely sense...

Hydrology team

NASA Technical Reports Server (NTRS)

Ragan, R.

1982-01-01

General problems faced by hydrologists when using historical records, real time data, statistical analysis, and system simulation in providing quantitative information on the temporal and spatial distribution of water are related to the limitations of these data. Major problem areas requiring multispectral imaging-based research to improve hydrology models involve: evapotranspiration rates and soil moisture dynamics for large areas; the three dimensional characteristics of bodies of water; flooding in wetlands; snow water equivalents; runoff and sediment yield from ungaged watersheds; storm rainfall; fluorescence and polarization of water and its contained substances; discriminating between sediment and chlorophyll in water; role of barrier island dynamics in coastal zone processes; the relationship between remotely measured surface roughness and hydraulic roughness of land surfaces and stream networks; and modeling the runoff process.

Complete velocity distribution in river cross-sections measured by acoustic instruments

USGS Publications Warehouse

Cheng, R.T.; Gartner, J.W.; ,

2003-01-01

To fully understand the hydraulic properties of natural rivers, velocity distribution in the river cross-section should be studied in detail. The measurement task is not straightforward because there is not an instrument that can measure the velocity distribution covering the entire cross-section. Particularly, the velocities in regions near the free surface and in the bottom boundary layer are difficult to measure, and yet the velocity properties in these regions play the most significant role in characterizing the hydraulic properties. To further characterize river hydraulics, two acoustic instruments, namely, an acoustic Doppler current profiler (ADCP), and a "BoogieDopp" (BD) were used on fixed platforms to measure the detailed velocity profiles across the river. Typically, 20 to 25 stations were used to represent a river cross-section. At each station, water velocity profiles were measured independently and/or concurrently by an ADCP and a BD. The measured velocity properties were compared and used in computation of river discharge. In a tow-tank evaluation of a BD, it has been confirmed that BD is capable of measuring water velocity at about 11 cm below the free-surface. Therefore, the surface velocity distribution across the river was extracted from the BD velocity measurements and used to compute the river discharge. These detailed velocity profiles and the composite velocity distribution were used to assess the validity of the classic theories of velocity distributions, conventional river discharge measurement methods, and for estimates of channel bottom roughness.

[Characteristics of water and heat fluxes and its footprint climatology on farmland in low hilly region of red soil].

PubMed

Li, Yang; Jing, Yuan Shu; Qin, Ben Ben

2017-01-01

The analysis of the characteristics and footprint climatology of farmland water and heat fluxes has great significance to strengthen regional climate resource management and improve the hydrothermal resource utilization in the region of red soil. Based on quality controlled data from large aperture scintillometer and automatic meteorological station in hilly region of red soil, this paper analyzed in detail the characteristics of farmland water and heat fluxes at different temporal scales and the corresponding source area distribution of flux measurement in the non-rainy season and crop growth period in hilly region of red soil. The results showed that the diurnal variation of water and heat fluxes showed a unimodal trend, but compared with the sunny day, the diurnal variation curves fluctuated more complicatedly on cloudy day. In the whole, either ten-day periods or month scale, the water and heat fluxes were greater in August than in September, while the net radiation flux was more distributed to latent heat exchange. The proportion of net radiation to latent heat flux decreased in September compared to August, but the sensible heat flux was vice versa. With combined effects of weather conditions (particularly wind), stability, and surface condition, the source areas of flux measurement at different temporal scales showed different distribution characteristics. Combined with the underlying surface crops, the source areas at different temporal scales also had different contribution sources.

Modeling hydrological controls on vegetation distribution across topography in Seward Peninsula, Alaska

NASA Astrophysics Data System (ADS)

Mekonnen, Z. A.; Riley, W. J.; Grant, R. F.; Salmon, V. G.; Iversen, C. M.; Biraud, S.; Breen, A. L.

2017-12-01

Observed changes in vegetation affect carbon and nutrient cycles in diverse landscapes of northern ecosystems. These changes can be affected by topography and landscape hydrology. We applied a coupled transect version of the ecosystem model ecosys in a landscape underlain by impermeable permafrost at Kougarok, Alaska to examine hydrological controls on watershed-scale vegetation distributions. Our preliminary results indicate strong relationships between vegetation distribution and soil physical and hydraulic properties that control water, nutrients, and energy flows across the hillslope. Modeled differences in aboveground biomass across the Kougarok hillslope had a good agreement (R2 0.80) with preliminary biomass measurements from the NGEE-Arctic project in summer 2016. Low soil water content from shallower soil depth and lateral flow of water and nutrients in the upper slope position of the hillslope resulted in water stress and low N mineralization for plants with deeper roots. The middle slope position had intermediate soil moisture from deeper soil and higher N mineralization that favoured fast-growing and deep-rooted plants. The gentle slope and deeper soil in the lower slope position resulted in saturated soil, thus reduced O2 for microbes, hence favouring plants with higher root porosity. Earth system models that do not account for the underlying mechanisms of surface and sub-surface flows of water, nutrients, and energy may not predict these types of dynamics in Arctic ecosystems.

ArcNLET: A GIS-based software to simulate groundwater nitrate load from septic systems to surface water bodies

NASA Astrophysics Data System (ADS)

Rios, J. Fernando; Ye, Ming; Wang, Liying; Lee, Paul Z.; Davis, Hal; Hicks, Rick

2013-03-01

Onsite wastewater treatment systems (OWTS), or septic systems, can be a significant source of nitrates in groundwater and surface water. The adverse effects that nitrates have on human and environmental health have given rise to the need to estimate the actual or potential level of nitrate contamination. With the goal of reducing data collection and preparation costs, and decreasing the time required to produce an estimate compared to complex nitrate modeling tools, we developed the ArcGIS-based Nitrate Load Estimation Toolkit (ArcNLET) software. Leveraging the power of geographic information systems (GIS), ArcNLET is an easy-to-use software capable of simulating nitrate transport in groundwater and estimating long-term nitrate loads from groundwater to surface water bodies. Data requirements are reduced by using simplified models of groundwater flow and nitrate transport which consider nitrate attenuation mechanisms (subsurface dispersion and denitrification) as well as spatial variability in the hydraulic parameters and septic tank distribution. ArcNLET provides a spatial distribution of nitrate plumes from multiple septic systems and a load estimate to water bodies. ArcNLET's conceptual model is divided into three sub-models: a groundwater flow model, a nitrate transport and fate model, and a load estimation model which are implemented as an extension to ArcGIS. The groundwater flow model uses a map of topography in order to generate a steady-state approximation of the water table. In a validation study, this approximation was found to correlate well with a water table produced by a calibrated numerical model although it was found that the degree to which the water table resembles the topography can vary greatly across the modeling domain. The transport model uses a semi-analytical solution to estimate the distribution of nitrate within groundwater, which is then used to estimate a nitrate load using a mass balance argument. The estimates given by ArcNLET are suitable for a screening-level analysis.

Using surface water application to reduce 1,3-dichloropropene emission from soil fumigation.

PubMed

Gao, Suduan; Trout, Thomas J

2006-01-01

High emissions from soil fumigants increase the risk of detrimental impact on workers, bystanders, and the environment, and jeopardize future availability of fumigants. Efficient and cost-effective approaches to minimize emissions are needed. This study evaluated the potential of surface water application (or water seal) to reduce 1,3-dichloropropene (1,3-D) emissions from soil (Hanford sandy loam) columns. Treatments included dry soil (control), initial water application (8 mm of water just before fumigant application), initial plus a second water application (2.6 mm) at 12 h, initial plus two water applications (2.6 mm each time) at 12 and 24 h, standard high density polyethylene (HDPE) tarp, initial water application plus HDPE tarp, and virtually impermeable film (VIF) tarp. Emissions from the soil surface and distribution of 1,3-D in the soil-gas phase were monitored for 2 wk. Each water application abruptly reduced 1,3-D emission flux, which rebounded over a few hours. Peak emission rates were substantially reduced, but total emission reduction was small. Total fumigant emission was 51% of applied for the control, 46% for initial water application only, and 41% for the three intermittent water applications with the remaining water treatment intermediate. The HDPE tarp alone resulted in 45% emission, while initial water application plus HDPE tarp resulted in 38% emission. The most effective soil surface treatment was VIF tarp (10% emission). Surface water application can be as effective, and less expensive than, standard HDPE tarp. Frequent water application is required to substantially reduce emissions.

Salinity surveys using an airborne microwave radiometer

NASA Technical Reports Server (NTRS)

Paris, J. F.; Droppleman, J. D.; Evans, D. E.

1972-01-01

The Barnes PRT-5 infrared radiometer and L-band channel of the multifrequency microwave radiometer are used to survey the distribution of surface water temperature and salinity. These remote sensors were flown repetitively in November 1971 over the outflow of the Mississippi River into the Gulf of Mexico. Data reduction parameters were determined through the use of flight data obtained over a known water area. With these parameters, the measured infrared and microwave radiances were analyzed in terms of the surface temperature and salinity.

CHANGES IN BACTERIAL COMPOSITION OF BIOFILM IN A ...

EPA Pesticide Factsheets

This study examined the development of bacterial biofilms within a metropolitan distribution system. The distribution system is fed with different source water (i.e., groundwater, GW and surface water, SW) and undergoes different treatment processes in separate facilities. The biofilm community was characterized using 16S rRNA gene clone libraries and functional potential analysis, generated from total DNA extracted from coupons in biofilm annular reactors fed with onsite drinking water for up to eighteen months. Significant differences in the bacterial community structure were observed between GW and SW. Representatives that explained the dissimilarity between service areas were associated with Betaproteobacteria, Alphaproteobacteria, Actinobacteria, Gammaproteobacteria, and Firmicutes. After nine months the biofilm bacterial community from both areas were dominated by Mycobacterium species. The distribution of the dominant OTU (Mycobacterium) positively correlated with the drinking water distribution system (DWDS) temperature, but no clear relationship was seen with free chlorine residual, pH, turbidity or total organic carbon (TOC). The results suggest that biofilm microbial communities harbor distinct and diverse bacterial communities, and that source water, treatment processes and environmental conditions may play an important role in shaping the bacterial community in the distribution system. On the other hand, several bacterial groups were present i

Non-Rayleigh control of upper-ocean Cd isotope fractionation in the western South Atlantic

NASA Astrophysics Data System (ADS)

Xie, Ruifang C.; Galer, Stephen J. G.; Abouchami, Wafa; Rijkenberg, Micha J. A.; de Baar, Hein J. W.; De Jong, Jeroen; Andreae, Meinrat O.

2017-08-01

We present seawater Cd isotopic compositions in five depth profiles and a continuous surface water transect, from 50°S to the Equator, in the western South Atlantic, sampled during GEOTRACES cruise 74JC057 (GA02 section, Leg 3), and investigate the mechanisms governing Cd isotope cycling in the upper and deep ocean. The depth profiles generally display high ε 112 / 110Cd at the surface and decrease with increasing depth toward values typical of Antarctic Bottom Water (AABW). However, at stations north of the Subantarctic Front, the decrease in ε 112 / 110Cd is interrupted by a shift to values intermediate between those of surface and bottom waters, which occurs at depths occupied by North Atlantic Deep Water (NADW). This pattern is associated with variations in Cd concentration from low surface values to a maximum at mid-depths and is attributed to preferential utilization of light Cd by phytoplankton in the surface ocean. Our new results show that in this region Cd-deficient waters do not display the extreme, highly fractionated ε 112 / 110Cd reported in some earlier studies from other oceanic regions. Instead, in the surface and subsurface southwest (SW) Atlantic, when [Cd] drops below 0.1 nmol kg-1, ε 112 / 110Cd are relatively homogeneous and cluster around a value of +3.7, in agreement with the mean value of 3.8 ± 3.3 (2SD, n = 164) obtained from a statistical evaluation of the global ocean Cd isotope dataset. We suggest that Cd-deficient surface waters may acquire their Cd isotope signature via sorption of Cd onto organic ligands, colloids or bacterial/picoplankton extracellular functional groups. Alternatively, we show that an open system, steady-state model is in good accord with the observed Cd isotope systematics in the upper ocean north of the Southern Ocean. The distribution of ε 112 / 110Cd in intermediate and deep waters is consistent with the water mass distribution, with the north-south variations reflecting changes in the mixing proportion of NADW and either AABW or AAIW depending on the depth. Overall, the SW Atlantic Cd isotope dataset demonstrates that the large-scale ocean circulation exerts the primary control on ε 112 / 110Cd cycling in the global deep ocean.

Hydrogeologic setting and the potentiometric surfaces of regional aquifers in the Hollandale Embayment, southeastern Minnesota, 1970-80

USGS Publications Warehouse

Delin, G.N.; Woodward, D.G.

1984-01-01

Potentiometric-surface maps for each aquifer indicate that movement of ground water is predominantly toward the major rivers. The St. Croix, Minnesota, and Mississippi Rivers constitute regional discharge boundaries for ground-water flow. A major ground-water divide in the St. Peter, Prairie du Chien-Jordan, Ironton-Galesville, and Mount Simon-Hinckley aquifers in the south-central part of the Hollandale embayment separates ground-water flow northward toward the Twin Cities area and southward toward Iowa. The St. Peter and Prairie du Chien-Jordan aquifers in the southeastern part of the embayment contain ground-water mounds as high as 90 ft above the regional potentiometric surface. The mounds occur as a result of increased recharge where the Decorah-Platteville-Glenwood confining bed has been removed by erosion and the aquifers subcrop beneath drift that is about 20 ft thick. This head distribution produces a locally complex pattern of flow in which ground water moves southwesterly toward Iowa instead of directly toward the Mississippi River.

Distribution of decapod larvae in the surface layer of an isolated equatorial oceanic archipelago: the cases of benthic Grapsus grapsus (Brachyura: Grapsidae) and pelagic Sergestes edwardsi (Dendrobranchiata: Sergestidae)

NASA Astrophysics Data System (ADS)

Brandão, Manoela Costa; Koettker, Andréa Green; Freire, Andrea Santarosa

2013-03-01

Two different decapod larval assemblages inhabit the marine environment of Saint Paul's Rocks, differentiating the inlet from the surrounding oceanic waters. Larvae of the crab Grapsus grapsus and of the holopelagic shrimp Sergestes edwardsi are abundant in superficial waters of the archipelago and have previously been shown to be good indicators of the inlet and adjacent oceanic waters, respectively. We investigated the horizontal, diel and temporal distribution of these species at Saint Paul's Rocks. Horizontal surface hauls were conducted from 2003 to 2005, in the inlet and at four increasing distances from the archipelago, in the morning and at night, using a 200-μm mesh net. Larvae of G. grapsus were identified in samples from all expeditions and abundance was found significantly higher at night in the inlet site. Only larvae in the first zoeal stage were found in samples, highlighting the importance of the area for this species reproduction. On the contrary, the distribution of larvae of S. edwardsi was typical of a holopelagic species, which are permanent residents of the water column and spawn in oceanic areas, indicating that the islands are of little influence to them.

The global abundance and size distribution of lakes, ponds, and impoundments

USGS Publications Warehouse

Downing, J.A.; Prairie, Y.T.; Cole, J.J.; Duarte, C.M.; Tranvik, L.J.; Striegl, Robert G.; McDowell, W.H.; Kortelainen, Pirkko; Caraco, N.F.; Melack, J.M.; Middelburg, J.J.

2006-01-01

One of the major impediments to the integration of lentic ecosystems into global environmental analyses has been fragmentary data on the extent and size distribution of lakes, ponds, and impoundments. We use new data sources, enhanced spatial resolution, and new analytical approaches to provide new estimates of the global abundance of surface-water bodies. A global model based on the Pareto distribution shows that the global extent of natural lakes is twice as large as previously known (304 million lakes; 4.2 million km 2 in area) and is dominated in area by millions of water bodies smaller than 1 km2. Similar analyses of impoundments based on inventories of large, engineered dams show that impounded waters cover approximately 0.26 million km2. However, construction of low-tech farm impoundments is estimated to be between 0.1 % and 6% of farm area worldwide, dependent upon precipitation, and represents >77,000 km 2 globally, at present. Overall, about 4.6 million km2 of the earth's continental "land" surface (>3%) is covered by water. These analyses underscore the importance of explicitly considering lakes, ponds, and impoundments, especially small ones, in global analyses of rates and processes. ?? 2006, by the American Society of Limnology and Oceanography, Inc.

A global, 30-m resolution land-surface water body dataset for 2000

NASA Astrophysics Data System (ADS)

Feng, M.; Sexton, J. O.; Huang, C.; Song, D. X.; Song, X. P.; Channan, S.; Townshend, J. R.

2014-12-01

Inland surface water is essential to terrestrial ecosystems and human civilization. The distribution of surface water in space and its change over time are related to many agricultural, environmental and ecological issues, and are important factors that must be considered in human socioeconomic development. Accurate mapping of surface water is essential for both scientific research and policy-driven applications. Satellite-based remote sensing provides snapshots of Earth's surface and can be used as the main input for water mapping, especially in large areas. Global water areas have been mapped with coarse resolution remotely sensed data (e.g., the Moderate Resolution Imaging Spectroradiometer (MODIS)). However, most inland rivers and water bodies, as well as their changes, are too small to map at such coarse resolutions. Landsat TM (Thematic Mapper) and ETM+ (Enhanced Thematic Mapper Plus) imagery has a 30m spatial resolution and provides decades of records (~40 years). Since 2008, the opening of the Landsat archive, coupled with relatively lower costs associated with computing and data storage, has made comprehensive study of the dynamic changes of surface water over large even global areas more feasible. Although Landsat images have been used for regional and even global water mapping, the method can hardly be automated due to the difficulties on distinguishing inland surface water with variant degrees of impurities and mixing of soil background with only Landsat data. The spectral similarities to other land cover types, e.g., shadow and glacier remnants, also cause misidentification. We have developed a probabilistic based automatic approach for mapping inland surface water bodies. Landsat surface reflectance in multiple bands, derived water indices, and data from other sources are integrated to maximize the ability of identifying water without human interference. The approach has been implemented with open-source libraries to facilitate processing large amounts of Landsat images on high-performance computing machines. It has been applied to the ~9,000 Landsat scenes of the Global Land Survey (GLS) 2000 data collection to produce a global, 30m resolution inland surface water body data set, which will be made available on the Global Land Cover Facility (GLCF) website (http://www.landcover.org).

The influence of shelf processes in delivering dissolved iron to the HNLC waters of the Drake Passage, Antarctica

NASA Astrophysics Data System (ADS)

Measures, C. I.; Brown, M. T.; Selph, K. E.; Apprill, A.; Zhou, M.; Hatta, M.; Hiscock, W. T.

2013-06-01

Dissolved trace element distributions near Elephant Island in the Drake Passage show extremely high levels of dissolved Fe and Mn in waters above the shelf. The entrainment of this enriched shelf water by the Fe-poor Antarctic Circumpolar Current (ACC) as it passes through the Shackleton Gap delivers an estimated 2.8×106 mol yr-1 dissolved Fe to the offshore waters of the Drake Passage. The magnitude and spatial distribution of dissolved Fe, Mn and Al over the shelf are consistent with a diagenetically produced sedimentary source, but are inconsistent with eolian or upwelling sources. The systematics of the Mn and Fe concentrations suggest that there are two distinct sources of dissolved Fe to the surface waters of this region. The highest Fe concentrations are associated with Bransfield Strait water, which can be identified by its characteristic temperature and salinity (T/S) properties both inside the Bransfield Strait and in the Bransfield Current outflow between Elephant and Clarence Islands. Most of the shelf area is dominated by a second water type with T/S properties that are typical of modified Antarctic Surface Water, which while also enriched has a lower Fe:Mn ratio. The predominantly linear relationships between the Fe and Mn concentrations at the stations in each of these water mass types suggest that the distribution of these elements is largely controlled by physical mixing processes and that biological removal of Fe on the shelf, while certainly occurring, is limited, perhaps as a result of rapid physical flushing processes and relatively slow biological growth rates. The consequent export of large quantities of this shelf-derived Fe into the ACC is likely responsible for the extensive regions of enhanced primary production seen in satellite imagery downstream of the Drake Passage.

Storage dynamics in hydropedological units control hillslope connectivity, runoff generation, and the evolution of catchment transit time distributions

PubMed Central

Tetzlaff, D; Birkel, C; Dick, J; Geris, J; Soulsby, C

2014-01-01

We examined the storage dynamics and isotopic composition of soil water over 12 months in three hydropedological units in order to understand runoff generation in a montane catchment. The units form classic catena sequences from freely draining podzols on steep upper hillslopes through peaty gleys in shallower lower slopes to deeper peats in the riparian zone. The peaty gleys and peats remained saturated throughout the year, while the podzols showed distinct wetting and drying cycles. In this region, most precipitation events are <10 mm in magnitude, and storm runoff is mainly generated from the peats and peaty gleys, with runoff coefficients (RCs) typically <10%. In larger events the podzolic soils become strongly connected to the saturated areas, and RCs can exceed 40%. Isotopic variations in precipitation are significantly damped in the organic-rich soil surface horizons due to mixing with larger volumes of stored water. This damping is accentuated in the deeper soil profile and groundwater. Consequently, the isotopic composition of stream water is also damped, but the dynamics strongly reflect those of the near-surface waters in the riparian peats. “pre-event” water typically accounts for >80% of flow, even in large events, reflecting the displacement of water from the riparian soils that has been stored in the catchment for >2 years. These riparian areas are the key zone where different source waters mix. Our study is novel in showing that they act as “isostats,” not only regulating the isotopic composition of stream water, but also integrating the transit time distribution for the catchment. Key Points Hillslope connectivity is controlled by small storage changes in soil units Different catchment source waters mix in large riparian wetland storage Isotopes show riparian wetlands set the catchment transit time distribution PMID:25506098

Storage dynamics in hydropedological units control hillslope connectivity, runoff generation, and the evolution of catchment transit time distributions.

PubMed

Tetzlaff, D; Birkel, C; Dick, J; Geris, J; Soulsby, C

2014-02-01

We examined the storage dynamics and isotopic composition of soil water over 12 months in three hydropedological units in order to understand runoff generation in a montane catchment. The units form classic catena sequences from freely draining podzols on steep upper hillslopes through peaty gleys in shallower lower slopes to deeper peats in the riparian zone. The peaty gleys and peats remained saturated throughout the year, while the podzols showed distinct wetting and drying cycles. In this region, most precipitation events are <10 mm in magnitude, and storm runoff is mainly generated from the peats and peaty gleys, with runoff coefficients (RCs) typically <10%. In larger events the podzolic soils become strongly connected to the saturated areas, and RCs can exceed 40%. Isotopic variations in precipitation are significantly damped in the organic-rich soil surface horizons due to mixing with larger volumes of stored water. This damping is accentuated in the deeper soil profile and groundwater. Consequently, the isotopic composition of stream water is also damped, but the dynamics strongly reflect those of the near-surface waters in the riparian peats. "pre-event" water typically accounts for >80% of flow, even in large events, reflecting the displacement of water from the riparian soils that has been stored in the catchment for >2 years. These riparian areas are the key zone where different source waters mix. Our study is novel in showing that they act as "isostats," not only regulating the isotopic composition of stream water, but also integrating the transit time distribution for the catchment. Hillslope connectivity is controlled by small storage changes in soil unitsDifferent catchment source waters mix in large riparian wetland storageIsotopes show riparian wetlands set the catchment transit time distribution.

Water-quality assessment of south-central Texas: Occurrence and distribution of volatile organic compounds in surface water and ground water, 1983-94, and implications for future monitoring

USGS Publications Warehouse

Ging, P.B.; Judd, L.J.; Wynn, K.H.

1997-01-01

The study area of the South-Central Texas study unit of the National Water-Quality Assessment Program comprises the Edwards aquifer in the San Antonio region and its catchment area. The first phase of the assessment includes evaluation of existing water-quality data for surface water and ground water, including volatile organic compounds, to determine the scope of planned monitoring. Most analyses of volatile organic compounds in surface water are from the National Pollutant Discharge Elimination System sites in San Antonio, Texas. Nine volatile organic compounds were detected at the six sites. The three compounds with the most detections at National Pollutant Discharge Elimination System sites are 1,2,4-trimethylbenzene, toluene, and xylene. Analysis of volatile organic compounds in ground water was limited to Edwards aquifer wells. Twenty-eight volatile organic compounds were detected in samples from 89 wells. The five most commonly detected compounds in samples from wells, in descending order, are tetrachloroethene, trichloroethene, bromoform, chloroform, and dibromochloromethane. Detections of volatile organic compounds in surface water and ground water within the South-Central Texas study area are limited to site-specific sources associated with development; therefore, planned monitoring for possible detections of volatile organic compounds as part of the National Water-Quality Assessment Program will emphasize areas of expanding population and development. Monitoring of volatile organic compounds is planned at National Pollutant Discharge Elimination System sites, at basic fixed surface-water sites, and in the ground-water study-unit surveys.

The regional abundance and size distribution of lakes and reservoirs in the United States and implication for estimates of global lake extent

USGS Publications Warehouse

McDonald, Cory P.; Rover, Jennifer; Stets, Edward G.; Striegl, Robert G.

2012-01-01

We analyzed complete geospatial data for the 3.5 million lakes and reservoirs larger than 0.001 km2, with a combined surface area of 131,000 km2, in the contiguous United States (excluding the Laurentian Great Lakes) and identified their regional distribution characteristics. For Alaska, we also analyzed (1) incomplete data that suggest that the state contains 1–2.5 million lakes larger than 0.001 km2 covering over 50,000 km2 and (2) localized high-resolution (5 m) data that suggest that the number of very small water bodies (< 0.001 km2) may be comparable with the number of lakes > 0.001 km2 in some areas. The Pareto distribution cannot accurately describe the lake abundance-size relationship across the entire size spectrum, and extrapolation of this density function to small size classes has likely resulted in the overestimation of the number of small lakes in the world. While small water bodies dominate in terms of numbers, they are not numerous enough to dominate in terms of surface area, as has been previously suggested. Extending our results to the global scale suggests that there are on the order of 64 million water bodies larger than 0.001 km2 in the world, with a total surface area of approximately 3.8 million km2.

Effect of sulfate on the transformation of corrosion scale composition and bacterial community in cast iron water distribution pipes.

PubMed

Yang, Fan; Shi, Baoyou; Bai, Yaohui; Sun, Huifang; Lytle, Darren A; Wang, Dongsheng

2014-08-01

The chemical stability of iron corrosion scales and the microbial community of biofilm in drinking water distribution system (DWDS) can have great impact on the iron corrosion and corrosion product release, which may result in "red water" issues, particularly under the situation of source water switch. In this work, experimental pipe loops were set up to investigate the effect of sulfate on the dynamical transformation characteristics of iron corrosion products and bacterial community in old cast iron distribution pipes. All the test pipes were excavated from existing DWDS with different source water supply histories, and the test water sulfate concentration was in the range of 50-350 mg/L. Pyrosequencing of 16S rRNA was used for bacterial community analysis. The results showed that iron release increased markedly and even "red water" occurred for pipes with groundwater supply history when feed water sulfate elevated abruptly. However, the iron release of pipes with only surface water supply history changed slightly without noticeable color even the feed water sulfate increased multiply. The thick-layered corrosion scales (or densely distributed tubercles) on pipes with surface water supply history possessed much higher stability due to the larger proportion of stable constituents (mainly Fe3O4) in their top shell layer; instead, the rather thin and uniform non-layered corrosion scales on pipes with groundwater supply history contained relatively higher proportion of less stable iron oxides (e.g. β-FeOOH, FeCO3 and green rust). The less stable corrosion scales tended to be more stable with sulfate increase, which was evidenced by the gradually decreased iron release and the increased stable iron oxides. Bacterial community analysis indicated that when switching to high sulfate water, iron reducing bacteria (IRB) maintained dominant for pipes with stable corrosion scales, while significant increase of sulfur oxidizing bacteria (SOB), sulfate reducing bacteria (SRB) and iron oxidizing bacteria (IOB) was observed for pipes with less stable corrosion scales. Copyright © 2014 Elsevier Ltd. All rights reserved.

A relationship between three-dimensional surface hydration structures and force distribution measured by atomic force microscopy.

PubMed

Miyazawa, Keisuke; Kobayashi, Naritaka; Watkins, Matthew; Shluger, Alexander L; Amano, Ken-ichi; Fukuma, Takeshi

2016-04-07

Hydration plays important roles in various solid-liquid interfacial phenomena. Very recently, three-dimensional scanning force microscopy (3D-SFM) has been proposed as a tool to visualise solvated surfaces and their hydration structures with lateral and vertical (sub) molecular resolution. However, the relationship between the 3D force map obtained and the equilibrium water density, ρ(r), distribution above the surface remains an open question. Here, we investigate this relationship at an interface of an inorganic mineral, fluorite, and water. The force maps measured in pure water are directly compared to force maps generated using the solvent tip approximation (STA) model and from explicit molecular dynamics simulations. The results show that the simulated STA force map describes the major features of the experimentally obtained force image. The agreement between the STA data and the experiment establishes the correspondence between the water density used as an input to the STA model and the experimental hydration structure and thus provides a tool to bridge the experimental force data and atomistic solvation structures. Further applications of this method should improve the accuracy and reliability of both interpretation of 3D-SFM force maps and atomistic simulations in a wide range of solid-liquid interfacial phenomena.

Correlations of water quality parameters with mutagenicity of chlorinated drinking water samples.

PubMed

Schenck, Kathleen M; Sivaganesan, Mano; Rice, Glenn E

2009-01-01

Adverse health effects that may result from chronic exposure to mixtures of disinfection by-products (DBPs) present in drinking waters may be linked to both the types and concentrations of DBPs present. Depending on the characteristics of the source water and treatment processes used, both types and concentrations of DBPs found in drinking waters vary substantially. The composition of a drinking-water mixture also may change during distribution. This study evaluated the relationships between mutagenicity, using the Ames assay, and water quality parameters. The study included information on treatment, mutagenicity data, and water quality data for source waters, finished waters, and distribution samples collected from five full-scale drinking water treatment plants, which used chlorine exclusively for disinfection. Four of the plants used surface water sources and the fifth plant used groundwater. Correlations between mutagenicity and water quality parameters are presented. The highest correlation was observed between mutagenicity and the total organic halide concentrations in the treated samples.

On the unsteady gravity-capillary wave pattern found behind a slow moving localized pressure distribution

NASA Astrophysics Data System (ADS)

Masnadi, N.; Duncan, J. H.

2013-11-01

The non-linear response of a water surface to a slow-moving pressure distribution is studied experimentally using a vertically oriented carriage-mounted air-jet tube that is set to translate over the water surface in a long tank. The free surface deformation pattern is measured with a full-field refraction-based method that utilizes a vertically oriented digital movie camera (under the tank) and a random dot pattern (above the water surface). At towing speeds just below the minimum phase speed of gravity-capillary waves (cmin ~ 23 cm/s), an unsteady V-shaped pattern is formed behind the pressure source. Localized depressions are generated near the source and propagate in pairs along the two arms of the V-shaped pattern. These depressions are eventually shed from the tips of the pattern at a frequency of about 1 Hz. It is found that the shape and phase speeds of the first depressions shed in each run are quantitatively similar to the freely-propagating gravity-capillary lumps from potential flow calculations. In the experiments, the amplitudes of the depressions decrease by approximately 60 percent while travelling 12 wavelengths. The depressions shed later in each run behave in a less consistent manner, probably due to their interaction with neighboring depressions.

Dropwise condensation on hydrophobic bumps and dimples

NASA Astrophysics Data System (ADS)

Yao, Yuehan; Aizenberg, Joanna; Park, Kyoo-Chul

2018-04-01

Surface topography plays an important role in promoting or suppressing localized condensation. In this work, we study the growth of water droplets on hydrophobic convex surface textures such as bumps and concave surface textures such as dimples with a millimeter scale radius of curvature. We analyze the spatio-temporal droplet size distribution under a supersaturation condition created by keeping the uniform surface temperature below the dew point and show its relationship with the sign and magnitude of the surface curvature. In particular, in contrast to the well-known capillary condensation effect, we report an unexpectedly less favorable condensation on smaller, millimeter-scale dimples where the capillary condensation effect is negligible. To explain these experimental results, we numerically calculated the diffusion flux of water vapor around the surface textures, showing that its magnitude is higher on bumps and lower on dimples compared to a flat surface. We envision that our understanding of millimetric surface topography can be applied to improve the energy efficiency of condensation in applications such as water harvesting, heating, ventilation, and air conditioning systems for buildings and transportation, heat exchangers, thermal desalination plants, and fuel processing systems.

Evaluating scale and roughness effects in urban flood modelling using terrestrial LIDAR data

NASA Astrophysics Data System (ADS)

Ozdemir, H.; Sampson, C. C.; de Almeida, G. A. M.; Bates, P. D.

2013-10-01

This paper evaluates the results of benchmark testing a new inertial formulation of the St. Venant equations, implemented within the LISFLOOD-FP hydraulic model, using different high resolution terrestrial LiDAR data (10 cm, 50 cm and 1 m) and roughness conditions (distributed and composite) in an urban area. To examine these effects, the model is applied to a hypothetical flooding scenario in Alcester, UK, which experienced surface water flooding during summer 2007. The sensitivities of simulated water depth, extent, arrival time and velocity to grid resolutions and different roughness conditions are analysed. The results indicate that increasing the terrain resolution from 1 m to 10 cm significantly affects modelled water depth, extent, arrival time and velocity. This is because hydraulically relevant small scale topography that is accurately captured by the terrestrial LIDAR system, such as road cambers and street kerbs, is better represented on the higher resolution DEM. It is shown that altering surface friction values within a wide range has only a limited effect and is not sufficient to recover the results of the 10 cm simulation at 1 m resolution. Alternating between a uniform composite surface friction value (n = 0.013) or a variable distributed value based on land use has a greater effect on flow velocities and arrival times than on water depths and inundation extent. We conclude that the use of extra detail inherent in terrestrial laser scanning data compared to airborne sensors will be advantageous for urban flood modelling related to surface water, risk analysis and planning for Sustainable Urban Drainage Systems (SUDS) to attenuate flow.

Evaluating scale and roughness effects in urban flood modelling using terrestrial LIDAR data

NASA Astrophysics Data System (ADS)

Ozdemir, H.; Sampson, C. C.; de Almeida, G. A. M.; Bates, P. D.

2013-05-01

This paper evaluates the results of benchmark testing a new inertial formulation of the de St. Venant equations, implemented within the LISFLOOD-FP hydraulic model, using different high resolution terrestrial LiDAR data (10 cm, 50 cm and 1 m) and roughness conditions (distributed and composite) in an urban area. To examine these effects, the model is applied to a hypothetical flooding scenario in Alcester, UK, which experienced surface water flooding during summer 2007. The sensitivities of simulated water depth, extent, arrival time and velocity to grid resolutions and different roughness conditions are analysed. The results indicate that increasing the terrain resolution from 1 m to 10 cm significantly affects modelled water depth, extent, arrival time and velocity. This is because hydraulically relevant small scale topography that is accurately captured by the terrestrial LIDAR system, such as road cambers and street kerbs, is better represented on the higher resolution DEM. It is shown that altering surface friction values within a wide range has only a limited effect and is not sufficient to recover the results of the 10 cm simulation at 1 m resolution. Alternating between a uniform composite surface friction value (n = 0.013) or a variable distributed value based on land use has a greater effect on flow velocities and arrival times than on water depths and inundation extent. We conclude that the use of extra detail inherent in terrestrial laser scanning data compared to airborne sensors will be advantageous for urban flood modelling related to surface water, risk analysis and planning for Sustainable Urban Drainage Systems (SUDS) to attenuate flow.

Integration of altimetric lake levels and GRACE gravimetry over Africa: Inferences for terrestrial water storage change 2003-2011

NASA Astrophysics Data System (ADS)

Moore, P.; Williams, S. D. P.

2014-12-01

Terrestrial water storage (TWS) change for 2003-2011 is estimated over Africa from GRACE gravimetric data. The signatures from change in water of the major lakes are removed by utilizing kernel functions with lake heights recovered from retracked ENVISAT satellite altimetry. In addition, the contribution of gravimetric change due to soil moisture and biomass is removed from the total GRACE signal by utilizing the GLDAS land surface model. The residual TWS time series, namely groundwater and the surface waters in rivers, wetlands, and small lakes, are investigated for trends and the seasonal cycle using linear regression. Typically, such analyses assume that the data are temporally uncorrelated but this has been shown to lead to erroneous inferences in related studies concerning the linear rate and acceleration. In this study, we utilize autocorrelation and investigate the appropriate stochastic model. The results show the proper distribution of TWS change and identify the spatial distribution of significant rates and accelerations. The effect of surface water in the major lakes is shown to contribute significantly to the trend and seasonal variation in TWS in the lake basin. Lake Volta, a managed reservoir in Ghana, is seen to have a contribution to the linear trend that is a factor of three greater than that of Lake Victoria despite having a surface area one-eighth of that of Lake Victoria. Analysis also shows the confidence levels of the deterministic trend and acceleration identifying areas where the signatures are most likely due to a physical deterministic cause and not simply stochastic variations.

Characteristics of the horizontal and vertical distributions of dimethyl sulfide throughout the Amundsen Sea Polynya.

PubMed

Kim, Intae; Hahm, Doshik; Park, Keyhong; Lee, Youngju; Choi, Jung-Ok; Zhang, Miming; Chen, Liqi; Kim, Hyun-Cheol; Lee, SangHoon

2017-04-15

We investigated horizontal and vertical distributions of DMS in the upper water column of the Amundsen Sea Polynya and Pine Island Polynya during the austral summer (January-February) of 2016 using a membrane inlet mass spectrometer (MIMS) onboard the Korean icebreaker R/V Araon. The surface water concentrations of DMS varied from <1 to 400nM. The highest DMS (up to 300nM) were observed in sea ice-polynya transition zones and near the Getz ice shelf, where both the first local ice melting and high plankton productivity were observed. In other regions, high DMS concentration was generally accompanied by higher chlorophyll and ΔO 2 /Ar. The large spatial variability of DMS and primary productivity in the surface water of the Amundsen Sea seems to be attributed to melting conditions of sea ice, relative dominance of Phaeocystis Antarctica as a DMS producer, and timing differences between bloom and subsequent DMS productions. The depth profiles of DMS and ΔO 2 /Ar were consistent with the horizontal surface data, showing noticeable spatial variability. However, despite the large spatial variability, in contrast to the previous results from 2009, DMS concentrations and ΔO 2 /Ar in the surface water were indistinct between the two major domains: the sea ice zone and polynya region. The discrepancy may be associated with inter-annual variations of phytoplankton assemblages superimposed on differences in sea-ice conditions, blooming period, and spatial coverage along the vast surface area of the Amundsen Sea. Copyright © 2017 Elsevier B.V. All rights reserved.

Water balance-based estimation of groundwater recharge in the Lake Chad Basin

NASA Astrophysics Data System (ADS)

Babamaaji, R. A.; Lee, J.

2012-12-01

Lake Chad Basin (LCB) has experienced drastic changes of land cover and poor water management practices during the last 50 years. The successive droughts in the 1970s and 1980s resulted in the shortage of surface water and groundwater resources. This problem of drought and shortage of water has a devastating implication on the natural resources of the Basin with great consequence on food security, poverty reduction and quality of life of the inhabitants in the LCB. Therefore, understanding the change of land use and its characteristics must be a first step to find how such changes disturb the water cycle especially the groundwater in the LCB. The abundance of groundwater is affected by the climate change through the interaction with surface water, such as lakes and rivers, and vertical recharge through an infiltration process. Quantifying the impact of climate change on the groundwater resource requires not only reliable forecasting of changes in the major climatic variables, but also accurate estimation of groundwater recharge. Spatial variations in the land use/land cover, soil texture, topographic slope, and meteorological conditions should be accounted for in the recharge estimation. In this study, we employed a spatially distributed water balance model WetSpass to simulate a long-term average change of groundwater recharge in the LCB of Africa. WetSpass is a water balance-based model to estimate seasonal average spatial distribution of surface runoff, evapotranspiration, and groundwater recharge. The model is especially suitable for studying the effect of land use/land cover change on the water regime in the LCB. The present study describes the concept of the model and its application to the development of recharge map of the LCB.

Occurrence and distribution of pesticide compounds in surface water of the Santa Ana basin, California, 1998-2001

USGS Publications Warehouse

Kent, Robert; Belitz, Kenneth; Altmann, Andrea J.; Wright, Michael T.; Mendez, Gregory O.

2005-01-01

A study of the occurrence and distribution of pesticide compounds in surface water of the highly urbanized Santa Ana Basin, California, was done as part of the U.S. Geological Survey's National Water-Quality Assessment Program (NAWQA). One-hundred and forty-eight samples were collected from 23 sites, and analyzed for pesticide compounds during the study period from November 1998 to September 2001. Sixty-six different pesticide compounds were detected at varying frequencies and concentrations, and one or more pesticides were detected in 92 percent of the samples. All pesticide concentrations were below maximum levels permitted in drinking water. However, two compounds-diazinon and diuron-exceeded nonenforceable drinking water health-advisory levels in at least one stream sample, and five compounds exceeded guidelines to protect aquatic life-carbaryl, chlorpyrifos, diazinon, lindane, and malathion. Twenty-two pesticide compounds were detected in at least 25 percent of the samples collected from any one fixed site. These are identified as 'major' pesticide compounds and are emphasized in this report. The degree to which pesticides were used in the basin, as well as their physical-chemical properties, are important explanatory factors in stream pesticide occurrence, and most pesticides probably enter streams with urban runoff. Stormflow substantially increases urban runoff, and storm effects on stream pesticide concentrations sometimes persist for several days or weeks after the storm. Water sources other than urban runoff also deliver pesticide compounds to surface water in the basin. For example, atrazine may enter streams in gaining reaches where ground water carries high loads as a result of historical use in the basin. Also, the data suggest that lindane, and perhaps bromacil, are present in treated wastewater, the predominant source of water to streams in the Santa Ana Basin.

A Computational Study of Vocal Fold Dehydration During Phonation.

PubMed

Wu, Liang; Zhang, Zhaoyan

2017-12-01

While vocal fold dehydration is often considered an important factor contributing to vocal fatigue, it still remains unclear whether vocal fold vibration alone is able to induce severe dehydration that has a noticeable effect on phonation and perceived vocal effort. A three-dimensional model was developed to investigate vocal fold systemic dehydration and surface dehydration during phonation. Based on the linear poroelastic theory, the model considered water resupply from blood vessels through the lateral boundary, water movement within the vocal folds, water exchange between the vocal folds and the surface liquid layer through the epithelium, and surface fluid accumulation and discharge to the glottal airway. Parametric studies were conducted to investigate water loss within the vocal folds and from the surface after a 5-min sustained phonation under different permeability and vibration conditions. The results showed that the dehydration generally increased with increasing vibration amplitude, increasing epithelial permeability, and reduced water resupply. With adequate water resupply, a large-amplitude vibration can induce an overall systemic dehydration as high as 3%. The distribution of water loss within the vocal folds was non-uniform, and a local dehydration higher than 5% was observed even under conditions of a low overall systemic dehydration (<1%). Such high level of water loss may severely affect tissue properties, muscular functions, and phonations characteristics. In contrast, water loss of the surface liquid layer was generally an order of magnitude higher than water loss inside the vocal folds, indicating that the surface dehydration level is likely not a good indicator of the systemic dehydration.

Impact of micro-porous layer on liquid water distribution at the catalyst layer interface and cell performance in a polymer electrolyte membrane fuel cell

NASA Astrophysics Data System (ADS)

Tabe, Yutaka; Aoyama, Yusuke; Kadowaki, Kazumasa; Suzuki, Kengo; Chikahisa, Takemi

2015-08-01

In polymer electrolyte membrane fuel cells, a gas diffusion layer (GDL) with a micro-porous layer (MPL) gives better anti-flooding performance than GDLs without an MPL. To investigate the function and mechanism of the MPL to suppress water flooding, the liquid water distribution at the cathode catalyst layer (CL) surface are observed by a freezing method; in the method liquid water is immobilized in ice form by rapid freezing, followed by disassembling the cell for observations. The ice covered area is quantified by image processing and cells with and without an MPL are compared. The results show that the MPL suppresses water accumulation at the interface due to smaller pore size and finer contact with the CL, and this results in less water flooding. Investigation of ice formed after -10 °C cold start shutdowns and the temporary performance deterioration at ordinary temperatures also indicates a significant influence of the liquid water accumulating at the interface. The importance of the fine contact between CL and MPL, the relative absence of gaps, is demonstrated by a gas diffusion electrode (GDE) which is directly coated with catalyst ink on the surface of the MPL achieving finer contact of the layers.

Annual subsurface transport of a red tide dinoflagellate to its bloom area: Water circulation patterns and organism distributions in the Chesapeake Bay

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

Tyler, M.A.; Seliger, H.H.

1978-03-01

An annual, long range, subsurface transport of Prorocentrum mariae-lebouriae, from the mouth of the Chesapeake Bay to its bloom area in the upper bay, a distance of 240 km, is described and completely documented. Prorocentrum in surface outflowing waters at the mouth of the bay is recruited in late winter into more dense inflowing coastal waters. Strong stratification produced by late winter--early spring surface runoff results in the development of a stable pycnocline. Prorocentrum, now in northward-flowing bottom waters, is retained in these bottom waters. It accumulates in a subsurface concentration maximum below the pycnocline and is transported northward tomore » reach its bloom area in the Patapsco River and north of the Bay Bridge by late spring. The rapidly decreasing depth of the upper bay causes the pycnocline to rise, mixing the previously light-limited Prorocentrum and its nutrient-rich bottom waters to the surface, where rapid growth ensues. Once the dinoflagellate is in surface waters, positive phototaxis, combined with both wind- and tide-driven surface convergences, produce dense surface patches or red tides. Prorocentrum is effectively retained in the bay until late winter by sequential inoculation into the tributary estuaries on the western shore, which exchange relatively slowly with bay waters. By late winter the annual cycle is complete. Prorocentrum is again in surface waters at the mouth of the bay where it is reintroduced into northward-flowing bottom waters. The mechanisms described provide a key to understanding the origins of subsurface chlorophyll maxima and the delivery of toxic dinoflagellates to coastal bloom areas.« less

Ground-water-level monitoring, basin boundaries, and potentiometric surfaces of the aquifer system at Edwards Air Force Base, California, 1992

USGS Publications Warehouse

Rewis, D.L.

1995-01-01

A ground-water-level monitoring program was implemented at Edwards Air Force Base, California, from January through December 1992 to monitor spatial and temporal changes in poten-tiometric surfaces that largely are affected by ground-water pumping. Potentiometric-surface maps are needed to determine the correlation between declining ground- water levels and the distribution of land subsidence. The monitoring program focused on areas of the base where pumping has occurred, especially near Rogers Lake, and involved three phases of data collection: (1) well canvassing and selection, (2) geodetic surveys, and (3) monthly ground-water-level measurements. Construction and historical water- level data were compiled for 118 wells and pi-ezometers on or near the base, and monthly ground-water-level measurements were made in 82 wells and piezometers on the base. The compiled water-level data were used in conjunction with previously collected geologic data to identify three types of no-flow boundaries in the aquifer system: structural boundaries, a principal-aquifer boundary, and ground-water divides. Heads were computed from ground-water-level measurements and land-surface altitudes and then were used to map seasonal potentiometric surfaces for the principal and deep aquifers underlying the base. Pumping has created a regional depression in the potentiometric surface of the deep aquifer in the South Track, South Base, and Branch Park well-field area. A 15-foot decline in the potentiometric surface from April to September 1992 and 20- to 30-foot drawdowns in the three production wells in the South Track well field caused locally unconfined conditions in the deep aquifer.

Evidence for a Heterogeneous Distribution of Water in the Martian Interior

NASA Technical Reports Server (NTRS)

McCubbin, Francis; Boyce, Jeremy W.; Srinvasan, Poorna; Santos, Alison R.; Elardo, Stephen M.; Filiberto, Justin; Steele, Andrew; Shearer, Charles K.

2016-01-01

The abundance and distribution of H2O within the terrestrial planets, as well as its timing of delivery, is a topic of vital importance for understanding the chemical and physical evolution of planets and their potential for hosting habitable environments. Analysis of planetary materials from Mars, the Moon, and the eucrite parent body (i.e., asteroid 4Vesta) have confirmed the presence of H2O within their interiors. Moreover, H and N isotopic data from these planetary materials suggests H2O was delivered to the inner solar system very early from a common source, similar in composition to the carbonaceous chondrites. Despite the ubiquity of H2O in the inner Solar System, the only destination with any prospects for past or present habitable environments at this time, outside of the Earth, is Mars. Although the presence of H2O within the martian interior has been confirmed, very little is known regarding its abundance and distribution within the martian interior and how the martian water inventory has changed over time. By combining new analyses of martian apatites within a large number of martian meteorite types with previously published volatile data and recently determined mineral-melt partition coefficients for apatite, we report new insights into the abundance and distribution of volatiles in the martian crust and mantle. Using the subset of samples that did not exhibit crustal contamination, we determined that the enriched shergottite mantle source has 36-73 ppm H2O and the depleted shergottite mantle source has 14-23 ppm H2O. This result is consistent with other observed geochemical differences between enriched and depleted shergottites and supports the idea that there are at least two geochemically distinct reservoirs in the martian mantle. We also estimated the H2O content of the martian crust using the revised mantle H2O abundances and known crust-mantle distributions of incompatible lithophile elements. We determined that the bulk martian crust has approximately 1400 ppm H2O, which is likely distributed toward the martian surface. This crustal water abundance would equate to a global equivalent layer (GEL) of water at a depth of-229 m, which can account for at least some of the surface features on Mars attributed to flowing water and may be sufficient to support the past presence of a shallow sea on Mars' surface.

A frequency quantum interpretation of the surface renewal model of mass transfer

PubMed Central

Mondal, Chanchal

2017-01-01

The surface of a turbulent liquid is visualized as consisting of a large number of chaotic eddies or liquid elements. Assuming that surface elements of a particular age have renewal frequencies that are integral multiples of a fundamental frequency quantum, and further assuming that the renewal frequency distribution is of the Boltzmann type, performing a population balance for these elements leads to the Danckwerts surface age distribution. The basic quantum is what has been traditionally called the rate of surface renewal. The Higbie surface age distribution follows if the renewal frequency distribution of such elements is assumed to be continuous. Four age distributions, which reflect different start-up conditions of the absorption process, are then used to analyse transient physical gas absorption into a large volume of liquid, assuming negligible gas-side mass-transfer resistance. The first two are different versions of the Danckwerts model, the third one is based on the uniform and Higbie distributions, while the fourth one is a mixed distribution. For the four cases, theoretical expressions are derived for the rates of gas absorption and dissolved-gas transfer to the bulk liquid. Under transient conditions, these two rates are not equal and have an inverse relationship. However, with the progress of absorption towards steady state, they approach one another. Assuming steady-state conditions, the conventional one-parameter Danckwerts age distribution is generalized to a two-parameter age distribution. Like the two-parameter logarithmic normal distribution, this distribution can also capture the bell-shaped nature of the distribution of the ages of surface elements observed experimentally in air–sea gas and heat exchange. Estimates of the liquid-side mass-transfer coefficient made using these two distributions for the absorption of hydrogen and oxygen in water are very close to one another and are comparable to experimental values reported in the literature. PMID:28791137

Temporal and spatial variabilities in the surface moisture content of a fine-grained beach

NASA Astrophysics Data System (ADS)

Namikas, S. L.; Edwards, B. L.; Bitton, M. C. A.; Booth, J. L.; Zhu, Y.

2010-01-01

This study examined spatial and temporal variations in the surface moisture content of a fine-grained beach at Padre Island, Texas, USA. Surface moisture measurements were collected on a 27 × 24 m grid that extended from the dune toe to the upper foreshore. The grid was surveyed at 2 to 4 h intervals for two tidal cycles, generating 17 maps of the spatial distribution of surface moisture. Simultaneous measurements of air temperature and humidity, wind speed and direction, tidal elevation, and water table elevation were used to interpret observed changes in surface moisture. It was found that the spatial distribution of surface moisture was broadly characterized by a cross-shore gradient of high to low content moving landward from the swash zone. The distribution of surface moisture was conceptualized in terms of three zones: saturated (> 25%), intermediate or transitional (5-25%), and dry (< 5%). The position of the saturated zone corresponded to the uppermost swash zone and therefore shifted in accordance with tidal elevation. Moisture contents in the intermediate and dry zones were primarily related to variation in water table depth (which was in turn controlled by tidal elevation) and to a lesser extent by evaporation. Signals associated with atmospheric processes such as evaporation were muted by the minimal degree of variation in atmospheric parameters experienced during most of the study period, but were apparent for the last few hours. The observed spatial and temporal variations in moisture content correspond reasonably well with observations of key controlling processes, but more work is needed to fully characterize this process suite.

Quantifying Water Stress Using Total Water Volumes and GRACE

NASA Astrophysics Data System (ADS)

Richey, A. S.; Famiglietti, J. S.; Druffel-Rodriguez, R.

2011-12-01

Water will follow oil as the next critical resource leading to unrest and uprisings globally. To better manage this threat, an improved understanding of the distribution of water stress is required today. This study builds upon previous efforts to characterize water stress by improving both the quantification of human water use and the definition of water availability. Current statistics on human water use are often outdated or inaccurately reported nationally, especially for groundwater. This study improves these estimates by defining human water use in two ways. First, we use NASA's Gravity Recovery and Climate Experiment (GRACE) to isolate the anthropogenic signal in water storage anomalies, which we equate to water use. Second, we quantify an ideal water demand by using average water requirements for the domestic, industrial, and agricultural water use sectors. Water availability has traditionally been limited to "renewable" water, which ignores large, stored water sources that humans use. We compare water stress estimates derived using either renewable water or the total volume of water globally. We use the best-available data to quantify total aquifer and surface water volumes, as compared to groundwater recharge and surface water runoff from land-surface models. The work presented here should provide a more realistic image of water stress by explicitly quantifying groundwater, defining water availability as total water supply, and using GRACE to more accurately quantify water use.

Biogeography of top predators - seabirds and cetaceans - along four latitudinal transects in the Atlantic Ocean

NASA Astrophysics Data System (ADS)

Jungblut, Simon; Nachtsheim, Dominik A.; Boos, Karin; Joiris, Claude R.

2017-07-01

The distribution, abundance, and species assemblage of top predators - seabirds and cetaceans - can be correlated to water masses as defined by hydrological parameters. In comparison to other oceans, information about the structuring effects of water masses on top predators in the Atlantic Ocean is limited. The present study aims 1) to provide baseline distributional data of top predators for future comparisons, for instance in the course of climate change, and 2) to test how water masses and seasons affect distributional patterns of seabirds and cetaceans in the temperate and tropical Atlantic. During four trans-equatorial expeditions of the RV Polarstern between 2011 and 2014, at-sea observation data of seabirds, cetaceans and other megafauna were collected. Counts of top predators were generally low in the surveyed regions. Statistical analyses for the eight most abundant seabird species and the pooled number of cetaceans revealed water masses and seasons to account for differences in counts and thus also distribution. In most cases, borders between water masses were not very distinct due to gradual changes in surface water properties. Thus, top predator counts were correlated to water masses but, in contrast to polar waters, not strongly linked to borders between water masses. Additional factors, e.g. distance to locally productive areas (upwelling), competition effects, and seabird associations to prey-accumulating subsurface predators may be similarly important in shaping distributional patterns of top predators in the tropical and temperate Atlantic, but could not be specifically tested for here.

Water ice cloud property retrievals at Mars with OMEGA:Spatial distribution and column mass

NASA Astrophysics Data System (ADS)

Olsen, Kevin S.; Madeleine, Jean-Baptiste; Szantai, Andre; Audouard, Joachim; Geminale, Anna; Altieri, Francesca; Bellucci, Giancarlo; Montabone, Luca; Wolff, Michael J.; Forget, Francois

2017-04-01

Spectral images of Mars recorded by OMEGA (Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité) on Mars Express can be used to deduce the mean effective radius (r_eff) and optical depth (τ_i) of water ice particles in clouds. Using new data sets for a priori surface temperature, vertical profiles of atmospheric temperature, dust opacity, and multi-spectral surface albedo, we have analyzed over 40 OMEGA image cubes over the Tharsis, Arabia, and Syrtis Major quadrangles, and mapped the spatial distribution of r_eff, τ_i, and water ice column mass. We also explored the parameter space of r_eff and τ_i, which are inversely proportional, and the ice cloud index (ICI), which is the ratio of the reflectance at 3.4 and 3.52 μm, and indicates the thickness of water ice clouds. We found that the ICI, trivial to calculate for OMEGA image cubes, can be a proxy for column mass, which is very expensive to compute, requiring accurate retrievals of surface albedo, r_eff, and τ_i. Observing the spatial distribution, we find that within each cloud system, r_eff varies about a mean of 2.1 μm, that τi is closely related to r_eff, and that the values allowed for τ_i, given r_eff, are related to the ICI. We also observe areas where our retrieval detects very thin clouds made of very large particles (mean of 12.5 μm), which are still under investigation.

Estimating Travel Time in Bank Filtration Systems from a Numerical Model Based on DTS Measurements.

PubMed

des Tombe, Bas F; Bakker, Mark; Schaars, Frans; van der Made, Kees-Jan

2018-03-01

An approach is presented to determine the seasonal variations in travel time in a bank filtration system using a passive heat tracer test. The temperature in the aquifer varies seasonally because of temperature variations of the infiltrating surface water and at the soil surface. Temperature was measured with distributed temperature sensing along fiber optic cables that were inserted vertically into the aquifer with direct push equipment. The approach was applied to a bank filtration system consisting of a sequence of alternating, elongated recharge basins and rows of recovery wells. A SEAWAT model was developed to simulate coupled flow and heat transport. The model of a two-dimensional vertical cross section is able to simulate the temperature of the water at the well and the measured vertical temperature profiles reasonably well. MODPATH was used to compute flowpaths and the travel time distribution. At the study site, temporal variation of the pumping discharge was the dominant factor influencing the travel time distribution. For an equivalent system with a constant pumping rate, variations in the travel time distribution are caused by variations in the temperature-dependent viscosity. As a result, travel times increase in the winter, when a larger fraction of the water travels through the warmer, lower part of the aquifer, and decrease in the summer, when the upper part of the aquifer is warmer. © 2017 The Authors. Groundwater published by Wiley Periodicals, Inc. on behalf of National Ground Water Association.

The negligible chondritic contribution in the lunar soils water.

PubMed

Stephant, Alice; Robert, François

2014-10-21

Recent data from Apollo samples demonstrate the presence of water in the lunar interior and at the surface, challenging previous assumption that the Moon was free of water. However, the source(s) of this water remains enigmatic. The external flux of particles and solid materials that reach the surface of the airless Moon constitute a hydrogen (H) surface reservoir that can be converted to water (or OH) during proton implantation in rocks or remobilization during magmatic events. Our original goal was thus to quantify the relative contributions to this H surface reservoir. To this end, we report NanoSIMS measurements of D/H and (7)Li/(6)Li ratios on agglutinates, volcanic glasses, and plagioclase grains from the Apollo sample collection. Clear correlations emerge between cosmogenic D and (6)Li revealing that almost all D is produced by spallation reactions both on the surface and in the interior of the grains. In grain interiors, no evidence of chondritic water has been found. This observation allows us to constrain the H isotopic ratio of hypothetical juvenile lunar water to δD ≤ -550‰. On the grain surface, the hydroxyl concentrations are significant and the D/H ratios indicate that they originate from solar wind implantation. The scattering distribution of the data around the theoretical D vs. (6)Li spallation correlation is compatible with a chondritic contribution <15%. In conclusion, (i) solar wind implantation is the major mechanism responsible for hydroxyls on the lunar surface, and (ii) the postulated chondritic lunar water is not retained in the regolith.

Fluorescent probes for understanding soil water repellency: the novel application of a chemist's tool to soil science

NASA Astrophysics Data System (ADS)

Balshaw, Helen M.; Davies, Matthew L.; Doerr, Stefan H.; Douglas, Peter

2015-04-01

Food security and production is one of the key global issues faced by society. It has become essential to work the land efficiently, through better soil management and agronomy whilst protecting the environment from air and water pollution. The failure of soil to absorb water - soil water repellency can lead to major environmental problems such as increased overland flow and soil erosion, poor uptake of agricultural chemicals, and increased risk of groundwater pollution due to the rapid transfer of contaminants and nutrient leaching through uneven wetting and preferential flow pathways. Understanding the causes of soil hydrophobicity is essential for the development of effective methods for its amelioration, supporting environmental stability and food security. Organic compounds deposited on soil mineral or aggregate surfaces have long been recognised as a major factor in causing soil water repellency. It is widely accepted that the main groups of compounds responsible are long-chain acids, alkanes and other organic compounds with hydrophobic properties. However, when reapplied to sands and soils, the degree of water repellency induced by these compounds and mixtures varied widely with compound type, amount, and mixture, in a seemingly unpredictable way. Fluorescent and phosphorescent probes are widely used in chemistry and biochemistry due to their sensitive response to their physical and chemical environment, such as polarity, and viscosity. However, they have to-date not been used to study soil water repellency. Here we present preliminary work on the evaluation of fluorescent probes as tools to study two poorly understood features that determine the degree of wettability for water repellent soils: (i) the distribution of organics on soils; (ii) the changes in polarity at soil surfaces required for water drops to infiltrate. In our initial work we have examined probes adsorbed onto model soils, prepared by adsorption of specific organics onto acid washed sand. Studies using steady-state and μs time-resolved emission spectroscopy, together with fluorescence microscopy and image analysis, of probe lifetime, spectra, and spatial distribution have been used to 'map' the emission characteristics of probes when adsorbed, and also to examine how the distribution of hydrophobic compounds changes during contact with materials used for treating hydrophobic soils (e.g. clays, biochar). Furthermore, while it has been suggested that during soil wetting the water droplet induces changes in conformation, orientation and arrangement of a hydrophobic layer of organics adsorbed to the soil surfaces, there is little direct evidence for this, and so we are also exploring the use of fluorescent/phosphorescent probes adsorbed on the soil surface to determine any changes in environment polarity, viscosity or hydrophobicity at the soil surface during the wetting process.

Atrazine distribution measured in soil and leachate following infiltration conditions.

PubMed

Neurath, Susan K; Sadeghi, Ali M; Shirmohammadi, Adel; Isensee, Allan R; Torrents, Alba

2004-01-01

Atrazine transport through packed 10 cm soil columns representative of the 0-10 cm soil horizon was observed by measuring the atrazine recovery in the total leachate volume, and upper and lower soil layers following infiltration of 7.5 cm water using a mechanical vacuum extractor (MVE). Measured recoveries were analyzed to understand the influence of infiltration rate and delay time on atrazine transport and distribution in the column. Four time periods (0.28, 0.8, 1.8, and 5.5 h) representing very high to moderate infiltration rates (26.8, 9.4, 4.2, and 1.4 cm/h) were used. Replicate soil columns were tested immediately and following a 2-d delay after atrazine application. Results indicate atrazine recovery in leachate was independent of infiltration rate, but significantly lower for infiltration following a 2-d delay. Atrazine distribution in the 0-1 and 9-10 cm soil layers was affected by both infiltration rate and delay. These results are in contrast with previous field and laboratory studies that suggest that atrazine recovery in the leachate increases with increasing infiltration rate. It appears that the difference in atrazine recovery measured using the MVE and other leaching experiments using intact soil cores from this field site and the rain simulation equipment probably illustrates the effect of infiltrating water interacting with the atrazine present on the soil surface. This work suggests that atrazine mobilization from the soil surface is also dependent on interactions of the infiltrating water with the soil surface, in addition to the rate of infiltration through the surface soil.

Properties of the surface snow in Princess Elizabeth Land, East Antarctica - climate and non-climate dependent variability of the surface mass balance and stable water isotopic composition

NASA Astrophysics Data System (ADS)

Vladimirova, D.; Ekaykin, A.; Lipenkov, V.; Popov, S. V.; Petit, J. R.; Masson-Delmotte, V.

2017-12-01

Glaciological and meteorological observations conducted during the past four decades in Princess Elizabeth Land, East Antarctica, are compiled. The database is used to investigate spatial patterns of surface snow isotopic composition and surface mass balance, including detailed information near subglacial lake Vostok. We show diverse relationships between snow isotopic composition and surface temperature. In the most inland part (elevation 3200-3400 m a.s.l.), surface snow isotopic composition varies independently from surface temperature, and is closely related to the distance to the open water source (with a slope of 0.98±0.17 ‰ per 100 km). Surface mass balance values are higher along the ice sheet slope, and relatively evenly distributed inland. The minimum values of snow isotopic composition and surface mass balance are identified in an area XX km southwestward from Vostok station. The spatial distribution of deuterium excess delineates regions influenced by the Indian Ocean and Pacific Ocean air masses, with Vostok area being situated close to their boundary. Anomalously high deuterium excess values are observed near Dome A, suggesting high kinetic fractionation for its moisture source, or specifically high post-deposition artifacts. The dataset is available for further studies such as the assessment of skills of general circulation or regional atmospheric models, and the search for the oldest ice.

A sensor-based energy balance method for the distributed estimation of evaporation over the North American Great Lakes

NASA Astrophysics Data System (ADS)

Fries, K. J.; Kerkez, B.; Gronewold, A.; Lenters, J. D.

2014-12-01

We introduce a novel energy balance method to estimate evaporation across large lakes using real-time data from moored buoys and mobile, satellite-tracked drifters. Our work is motivated by the need to improve our understanding of the water balance of the Laurentian Great Lakes basin, a complex hydrologic system that comprises 90% of the United States' and 20% of the world's fresh surface water. Recently, the lakes experienced record-setting water level drops despite above-average precipitation, and given that lake surface area comprises nearly one third of the entire basin, evaporation is suspected to be the primary driver behind the decrease in water levels. There has historically been a need to measure evaporation over the Great Lakes, and recent hydrological phenomena (including not only record low levels, but also extreme changes in ice cover and surface water temperatures) underscore the urgency of addressing that need. Our method tracks the energy fluxes of the lake system - namely net radiation, heat storage and advection, and Bowen ratio. By measuring each of these energy budget terms and combining the results with mass-transfer based estimates, we can calculate real-time evaporation rates on sub-hourly timescales. To mitigate the cost prohibitive nature of large-scale, distributed energy flux measurements, we present a novel approach in which we leverage existing investments in seasonal buoys (which, while providing intensive, high quality data, are costly and sparsely distributed across the surface of the Great Lakes) and then integrate data from less costly satellite-tracked drifter data. The result is an unprecedented, hierarchical sensor and modeling architecture that can be used to derive estimates of evaporation in real-time through cloud-based computing. We discuss recent deployments of sensor-equipped buoys and drifters, which are beginning to provide us with some of the first in situ measurements of overlake evaporation from Earth's largest lake system, opening up the potential for improved and integrated monitoring and modeling of the Great Lakes water budget.