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Crawling beneath the free surface: Water snail locomotion  

NASA Astrophysics Data System (ADS)

Land snails move via adhesive locomotion. Through muscular contraction and expansion of their foot, they transmit waves of shear stress through a thin layer of mucus onto a solid substrate. Since a free surface cannot support shear stress, adhesive locomotion is not a viable propulsion mechanism for water snails that travel inverted beneath the free surface. Nevertheless, the motion of the freshwater snail, Sorbeoconcha physidae, is reminiscent of that of its terrestrial counterparts, being generated by the undulation of the snail foot that is separated from the free surface by a thin layer of mucus. Here, a lubrication model is used to describe the mucus flow in the limit of small-amplitude interfacial deformations. By assuming the shape of the snail foot to be a traveling sine wave and the mucus to be Newtonian, an evolution equation for the interface shape is obtained and the resulting propulsive force on the snail is calculated. This propulsive force is found to be nonzero for moderate values of the capillary number but vanishes in the limits of high and low capillary number. Physically, this force arises because the snail's foot deforms the free surface, thereby generating curvature pressures and lubrication flows inside the mucus layer that couple to the topography of the foot.

Lee, Sungyon; Bush, John W. M.; Hosoi, A. E.; Lauga, Eric



Land and water snails  

NSDL National Science Digital Library

Land snails live on the land and water snails make water their habitat. Land snails have shells to protect them and so do water snails. Land snails have two sets of antennae, while water snails only have one set.

Olivia Worland (Purdue University;Biological Sciences)



Crawling beneath the free surface: Water snail locomotion Sungyon Lee,1  

E-print Network

2008; published online 26 August 2008 Land snails move via adhesive locomotion. Through muscular onto a solid substrate. Since a free surface cannot support shear stress, adhesive locomotion marine and freshwater snails. A significant effort has gone towards understanding pedal wave locomotion

Lauga, Eric


Immunotoxicity of surface waters contaminated by municipal effluents to the snail Lymnaea stagnalis.  


The immunotoxic effects of surface waters contaminated by a municipal effluent dispersion plume were examined in the snail Lymnaea stagnalis. Snails were exposed to surface waters where changes in hemocyte counts, viability, levels of reactive oxygen species (ROS), reduced thiols and phagocytic activity were tracked following exposure periods of 3h and 3 and 7d. Changes in mRNA expression of some genes in the hemocytes were also assessed after 7d of exposure, as follows: genes coding for catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GSR), selenium-dependent glutathione peroxidase (SeGPX), two isoforms of the nitric oxide synthetase (NOS1 and NOS2), molluscan defensive molecule (MDM), toll-like receptor 4 (TLR4), allograft inflammatory factor-1 (AIF), and heat-shock protein 70 (HSP70). At the sites closest to the discharge point, exposure led to impaired hemocyte viability and intracellular thiol levels and also an increase of hemocyte count, ROS levels and phagocytosis. Phagocytosis and ROS levels in hemocytes were correlated with heterotrophic bacterial counts in snails. We found four genes with increased mRNA expression as a response to exposure of municipal wastewaters: TLR4 (6-fold), HSP70 (2-fold), SeGPx (4-fold) and CAT (2-fold). Immunocompetence responses were analyzed by canonical analysis to seek out relationships with mRNA expression of the genes involved in stress, pattern recognition, cellular and humoral responses. The data revealed that genes involved in oxidative stress were strongly involved with immunocompetence and that the resulting immune responses were influenced both by the bacterial and pollutant loadings of the effluent. PMID:23021492

Gust, M; Fortier, M; Garric, J; Fournier, M; Gagné, F



Distribution and ecology of the fresh-water snails (gastropods) of Norway  

Microsoft Academic Search

The article is a preliminary report of some of the results arrived at in a study comprising the distribution, ecology and morphology of the fresh-water snails of Norway, including aspects of regional limnology. When finished, the study is expected to be printed in Folia Limnologica Scandinavica. Fresh-water snails and data on environmental factors have been collected in about 1350 lakes,




Wet adhesion and adhesive locomotion of snails on anti-adhesive non-wetting surfaces.  


Creating surfaces capable of resisting liquid-mediated adhesion is extremely difficult due to the strong capillary forces that exist between surfaces. Land snails use this to adhere to and traverse across almost any type of solid surface of any orientation (horizontal, vertical or inverted), texture (smooth, rough or granular) or wetting property (hydrophilic or hydrophobic) via a layer of mucus. However, the wetting properties that enable snails to generate strong temporary attachment and the effectiveness of this adhesive locomotion on modern super-slippy superhydrophobic surfaces are unclear. Here we report that snail adhesion overcomes a wide range of these microscale and nanoscale topographically structured non-stick surfaces. For the one surface which we found to be snail resistant, we show that the effect is correlated with the wetting response of the surface to a weak surfactant. Our results elucidate some critical wetting factors for the design of anti-adhesive and bio-adhesion resistant surfaces. PMID:22693563

Shirtcliffe, Neil J; McHale, Glen; Newton, Michael I



Incidence of Parastrongylus cantonensis larvae in different fresh water snails in Dakahlia Governorate.  


Samples of snails were collected from different water bodies in Dakahlia governorate to assess a survey on the naturally infected snails and their infection rate with the Parastrongylus cantonensis larvae. The nematode P. cantonensis is associated in the etiology of eosinophilic meningeoencephalitis of man. Lanistes carinatus showed the highest rate of infection with 19-400 larvae per snail. Biomphalaria alexandrina, B. glabrata, Bulinus truncatus, Lymnaea cailliaudi (natalensis), L. alexandrina, and Cleopatra cyclostomoides were found naturally infected with the larvae of P. cantonensis for the first time in Egypt. The number of larvae per infected snail varied depending on the snail type. The highest rate (39.2%) of infected snails was collected from the end canals at Tanneekh and the lowest in the river Nile (12.5%). PMID:12214935

el-Shazly, A M; el-Hamshary, Eman M; el-Shewy, Khalid M; Rifaat, Manal M A; el-Sharkawy, Iman M A



The effect of isolation on reproduction and growth of Pseudosuccinea columella (Pulmonata: Lymnaeidae): a snail-conditioned water experiment.  


A snail-conditioned water experiment was conducted in Pseudosuccinea columella to test the possible role of a chemical interaction between snails on the diminished growth and fecundity rates found for snails raised in pairs compared to those raised in complete isolation. The results permit to discard the hypothesis of an inhibition of growth and reproduction between snails due to factors released into the water. PMID:12386712

Gutiérrez, Alfredo; Yong, Mary; Wong, Lin; Sánchez, Jorge



Survival of the Faucet Snail after Chemical Disinfection, pH extremes, and Heated Water Bath Treatments  

Microsoft Academic Search

The faucet snail Bithynia tentaculata, a nonindigenous aquatic snail from Eurasia, was introduced into Lake Michigan in 1871 and has spread to the mid-Atlantic states, the Great Lakes region, Montana, and most recently, the Mississippi River. The faucet snail serves as intermediate host for several trematodes that have caused large-scale mortality among water birds, primarily in the Great Lakes region

Andrew J. Mitchell; Rebecca A. Cole



Supercharged Snails for Stream Ecology & Water-Quality Studies  

ERIC Educational Resources Information Center

Gill-breathing freshwater snails (Family "Pleuroceridae") are ecologically important, abundant in many streams in the United States, and easy to collect and maintain under classroom conditions. These snails can be used in classroom tests to demonstrate effects of pollutants on aquatic organisms. In more advanced classes, students can cage the…

Stewart, Arthur J.; Ryon, Michael G.



Effect of water plants and non-target snails on the infectivity of Bulinus truncatus with Schistosoma haematobium.  


The application of the water plant (Ceratophyllum demersum, Eichhornia crassipes and Lemna gibba) and/or non-target snails (Planorbis planorbis, Physa acuta and Melanoides tuberculata) gave a significant degree of reduction in the infection rate of B. truncatus subjected to S. haematobium miracidia. The data also indicated a reduction in mean total number of cercarial production/snail. However, no significant difference was detected in the prepatent period and duration of cercarial shedding of the parasite when compared with the control group. So, the results revealed that the snails exhibited a competitive ability against B. truncatus. Both survival rate and egg production of B. truncatus were greatly reduced when existed in mixed cultures with non-target snails and the magnitude of this reduction increased by increasing the number of the non-target snails. PMID:16333895

Bakry, Fayez A; Abd-el-Monem, Sayed



A study on biological control of six fresh water snails of medical and veterinary importance.  


This study evaluated the molluscicidal effect of Commiphora mnolmol oil extract (Myrrh), on control of six fresh water snails (Lymnaea natalensis, Bulinus truncatus, Biomphalaria alexandrina, Physa acuta, Melania tuberculata and Cleopatra bulimoides). Also, the extract effect on the egg masses of L. natalensis, B. truncatus, B. alexandrina and Ph. acuta was evaluated. Snails and egg masses were exposed at 16-20 degrees C to various concentrations (conc.). LD50 after 24 hours expo-sure were 264/132, 283/195, 230/252, 200/224, 241/246 & 241/246 ppm for young/adult of L. natalensis, B. truncatus, B. alexandrina, Ph. acuta, M. tuberculata and C. bulimnoides respectively. LDtoo after 24 hours exposure were 400/400 for L. natalensis, B. truncatus, B. alexandrina, M. tuberculata and C. bulimoides, and 300/300 for Ph. acuta. Also, complete mortality (100%) was achieved for the egg masses of L. natalensis, B. truncatus, B. alexandrina and Ph. acuta at concentrations of 300, 200, 300 & 400 ppm respectively. Lower concentrations gave the same results after longer exposure. LD100 of C. molmol oil extract (Myrrh) had a rapid lethal effect on the six snail species and their egg masses in high conc. of 300 & 400 ppm. Commiphora molmol is a promising plant to be included with the candidate plant molluscicides. The oil extract of this plant showed a remarkable molluscicidal activity against used snail species. PMID:19530615

Abd-Allah, Karim F; Negm-Eldin, Mohsen M; Saleh, Mohamed H; El-Hamshary, Azza M S; El-Gozamy, Bothina M R; Aly, Nagwa S M



Accumulation and distributions of 137Cs in fresh water snail Pila ampullacea  

NASA Astrophysics Data System (ADS)

Pila ampullacea are found in tropical freshwaters of Indonesia. This snail exhibit several characteristics of ideal indicator organisms in order to understand the bioaccumulation of 137Cs . Biokinetic experiment was performaced in aquaria system and under influenced of concentration K+ in water. The result of experiment shown that Under difference K+ concentration in water, Pila ampullacea have capability to accumulated 137Cs with CF value range 8.95 to 12.52 ml.g-1. Both uptake and depuration rate were influenced by concentration of K+ in water.

Suseno, Heny



INTRODUCTION Predator avoidance in aquatic snails is facilitated by surfacing and  

E-print Network

Lymnaea stagnalis (L.), exhibit emergence behavior to escape predation but when the predatory threat.010132 Fluid and osmolyte recovery in the common pond snail Lymnaea stagnalis following full pond snail Lymnaea stagnalis sacrifices 40­

Grosell, Martin


Snail Snooping.  

ERIC Educational Resources Information Center

Presents an activity in which students in grades 5-8 learn about snail reproduction by observing and charting the activities of land snails, freshwater snails, and slugs. Instructions to implement and extend the activity are provided. (MDH)

Miller, Dorothy



Implications of water hardness in ecotoxicological assessments for water quality regulatory purposes: a case study with the aquatic snail Biomphalaria glabrata (Say, 1818).  


Water hardness is a property depending on the presence of alkaline earth metals, mainly calcium and magnesium. Among the strategies for water quality monitoring, ecotoxicological assays are performed to minimize impacts and classify water bodies. For these laboratory evaluations parameters are previously defined in the guidelines, including water hardness for both cultivation and testing medium. The present work was performed to evaluate the effects of different levels of water hardness on the survival and reproduction of the freshwater snail Biomphalaria glabrata and discuss the influence of natural water hardness on the results of ecotoxicological tests with these environmental samples. Comparing the groups it was possible to observe that those maintained in waters with least hardness had lower reproductive success, while the groups maintained in highest hardness showed better reproduction. These data show that waters with low hardness make the reproduction of the snail B. glabrata unfeasible, and this reveal a problem for ecotoxicity assays using natural water samples. PMID:25055099

Oliveira-Filho, E C; Caixeta, N R; Simplício, N C S; Sousa, S R; Aragão, T P; Muniz, D H F




E-print Network

Mine Engineering Plan Surface Water Components Site Drainage Mine Site Dewatering (If covered Dewatering Open Pit Lake Drain site / Water Disposal Mine Site Runoff Dikes Seepage Underground Mine Rivers

Boisvert, Jeff


Martian Surface Water Reservoir  

NASA Astrophysics Data System (ADS)

We present a comprehensive study of the water-related 3µm absorption using OMEGA data. We quantify the surface water reservoir using laboratory studies and reveal the distribution of the amorphous hydrated component measured by Curiosity.

Audouard, J.; Poulet, F.; Vincendon, M.; Milliken, R. E.; Jouglet, D.; Bibring, J.-P.; Gondet, B.; Langevin, Y.



Use of Ice-Water and Salt Treatments to Eliminate an Exotic Snail, the Red-Rim Melania, from Small Immersible Fisheries Equipment  

Microsoft Academic Search

Ice-water and salt treatments were evaluated for disinfection of small immersible fisheries equipment contaminated with a nonindigenous tropical snail, the red-rim melania Melanoides tuberculatus. This introduced species can displace native snails and transmit trematodes directly to fish and indirectly to other animals, including humans. The red-rim melania has a well-developed operculum that protects it from desiccation and allows it to

Andrew J. Mitchell; Thomas M. Brandt



Survival and behavior of Chinese mystery snails (Bellamya chinensis) in response to simulated water body drawdowns and extended air exposure  

USGS Publications Warehouse

Nonnative invasive mollusks degrade aquatic ecosystems and induce economic losses worldwide. Extended air exposure through water body drawdown is one management action used for control. In North America, the Chinese mystery snail (Bellamya chinensis) is an invasive aquatic snail with an expanding range, but eradication methods for this species are not well documented. We assessed the ability of B. chinensis to survive different durations of air exposure, and observed behavioral responses prior to, during, and following desiccation events. Individual B. chinensis specimens survived air exposure in a laboratory setting for > 9 weeks, and survivorship was greater among adults than juveniles. Several B. chinensis specimens responded to desiccation by sealing their opercula and/or burrowing in mud substrate. Our results indicate that drawdowns alone may not be an effective means of eliminating B. chinensis. This study lays the groundwork for future management research that may determine the effectiveness of drawdowns when combined with factors such as extreme temperatures, predation, or molluscicides.

Unstad, Kody M.; Uden, Daniel R.; Allen, Craig R.; Chaine, Noelle M.; Haak, Danielle M.; Kill, Robert A.; Pope, Kevin L.; Stephen, Bruce J.; Wong, Alec



Does water chemistry affect the dietary uptake and toxicity of silver nanoparticles by the freshwater snail Lymnaea stagnalis?  

USGS Publications Warehouse

Silver nanoparticles (AgNPs) are widely used in many applications and likely released into the aquatic environment. There is increasing evidence that Ag is efficiently delivered to aquatic organisms from AgNPs after aqueous and dietary exposures. Accumulation of AgNPs through the diet can damage digestion and adversely affect growth. It is well recognized that aspects of water quality, such as hardness, affect the bioavailability and toxicity of waterborne Ag. However, the influence of water chemistry on the bioavailability and toxicity of dietborne AgNPs to aquatic invertebrates is largely unknown. Here we characterize for the first time the effects of water hardness and humic acids on the bioaccumulation and toxicity of AgNPs coated with polyvinyl pyrrolidone (PVP) to the freshwater snail Lymnaea stagnalis after dietary exposures. Our results indicate that bioaccumulation and toxicity of Ag from PVP-AgNPs ingested with food are not affected by water hardness and by humic acids, although both could affect interactions with the biological membrane and trigger nanoparticle transformations. Snails efficiently assimilated Ag from the PVP-AgNPs mixed with diatoms (Ag assimilation efficiencies ranged from 82 to 93%). Rate constants of Ag uptake from food were similar across the entire range of water hardness and humic acid concentrations. These results suggest that correcting regulations for water quality could be irrelevant and ineffective where dietary exposure is important.

López-Serrano Oliver, Ana; Croteau, Marie-Noële; Stoiber, Tasha L.; Tejamaya, Mila; Römer, Isabella; Lead, Jamie R.; Luoma, Samuel N.



Causes of Late Pleistocene water level change in Lake Victoria, Equatorial East Africa, derived from clumped isotopes of land snails and fresh water mollusks. (Invited)  

NASA Astrophysics Data System (ADS)

Carbonate clumped isotope thermometry is based on the dependence of 13C-18O bond abundance in the carbonate lattice (measured as ?47) on the carbonate formation temperature. Most marine and freshwater biogenic carbonates are found to be in agreement with the clumped isotopes - temperature calibration. Clumped isotope thermometry is particularly useful in terrestrial environments where the interpretation of carbonate ?18O is limited due to difficulty in estimating the paleo-water isotopic composition. Clumped isotope-derived temperatures from land snails are generally higher than the ambient environmental temperatures, but show no evidence for disequilibrium. We attribute these higher body temperatures to snail eco-physiological adaptations through shell color, morphology, and behavior. We use the clumped isotope-derived temperatures in combination with shell ?18O to calculate snail body water ?18O composition. This parameter is interpreted as a paleo-hydrological indicator that reflects the isotopic composition of local precipitation modified by local evaporation. Rusinga and Mfangano Islands in Lake Victoria provide a unique opportunity to compare extant species of modern and fossil freshwater mollusks and land snails from the same location to examine lake paleo-hydrology. This location is particularly interesting as Lake Victoria itself is the main source of rain-water in the region such that the isotopic composition of land snail body water can be related back to the source waters. We combine clumped isotope and oxygen isotope measurements of both freshwater mollusks and land snails to examine the water balance of the lake, testing hypotheses about the mechanism of a significant rise in lake level in Lake Victoria ~35 - 40 ka BP. Outcrops of paleo-beach deposits ~18 m above the modern day lake level indicate high water stands at ~35-40 ka BP. Based on water balance models for Lake Victoria, an increase in lake level of this magnitude could be driven by local mean annual precipitation that is significantly greater than modern. However, this is inconsistent with regional climate reconstructions. This suggests that either lake level was controlled by non-climatic factors, or that local climate in the Lake Victoria basin was different than regional patterns of climate across eastern Africa. We use oxygen and clumped isotopes of modern and fossil shells (Corbicula sp., Melanoides sp. and Bellamya unicolor) from this 18 m beach outcrop on Mfangano Island to (1) compare with modern lake water ?18O values and (2) calculate paleo-water compositions. We combine these results with calculated snail body water ?18O composition (using oxygen and clumped isotopes) of land snails (Limicoloria cf. martensiana) from Rusinga and Mfangano Islands, to study hydrological changes of Lake Victoria. We use these data to evaluate the relative importance of climate change and tectonics as mechanisms for the Late Pleistocene expansion of Lake Victoria.

Zaarur, S.; Affek, H. P.; Tryon, C.; Peppe, D. J.; Faith, J.



O-Glycosylation of snails.  


The glycosylation abilities of snails deserve attention, because snail species serve as intermediate hosts in the developmental cycles of some human and cattle parasites. In analogy to many other host-pathogen relations, the glycosylation of snail proteins may likewise contribute to these host-parasite interactions. Here we present an overview on the O-glycan structures of 8 different snails (land and water snails, with or without shell): Arion lusitanicus, Achatina fulica, Biomphalaria glabrata, Cepaea hortensis, Clea helena, Helix pomatia, Limax maximus and Planorbarius corneus. The O-glycans were released from the purified snail proteins by ?-elimination. Further analysis was carried out by liquid chromatography coupled to electrospray ionization mass spectrometry and - for the main structures - by gas chromatography/mass spectrometry. Snail O-glycans are built from the four monosaccharide constituents: N-acetylgalactosamine, galactose, mannose and fucose. An additional modification is a methylation of the hexoses. The common trisaccharide core structure was determined in Arion lusitanicus to be N-acetylgalactosamine linked to the protein elongated by two 4-O-methylated galactose residues. Further elongations by methylated and unmethylated galactose and mannose residues and/or fucose are present. The typical snail O-glycan structures are different to those so far described. Similar to snail N-glycan structures they display methylated hexose residues. PMID:22581130

Stepan, Herwig; Pabst, Martin; Altmann, Friedrich; Geyer, Hildegard; Geyer, Rudolf; Staudacher, Erika



Snails home  

NASA Astrophysics Data System (ADS)

Many gardeners and horticulturalists seek non-chemical methods to control populations of snails. It has frequently been reported that snails that are marked and removed from a garden are later found in the garden again. This phenomenon is often cited as evidence for a homing instinct. We report a systematic study of the snail population in a small suburban garden, in which large numbers of snails were marked and removed over a period of about 6 months. While many returned, inferring a homing instinct from this evidence requires statistical modelling. Monte Carlo techniques demonstrate that movements of snails are better explained by drift under the influence of a homing instinct than by random diffusion. Maximum likelihood techniques infer the existence of two groups of snails in the garden: members of a larger population that show little affinity to the garden itself, and core members of a local garden population that regularly return to their home if removed. The data are strongly suggestive of a homing instinct, but also reveal that snail-throwing can work as a pest management strategy.

Dunstan, D. J.; Hodgson, D. J.



The Effect of Simulating Different Intermediate Host Snail Species on the Link between Water Temperature and Schistosomiasis Risk  

PubMed Central

Introduction A number of studies have attempted to predict the effects of climate change on schistosomiasis risk. The importance of considering different species of intermediate host snails separately has never previously been explored. Methods An agent-based model of water temperature and Biomphalaria pfeifferi population dynamics and Schistosoma mansoni transmission was parameterised to two additional species of snail: B. glabrata and B. alexandrina. Results Simulated B. alexandrina populations had lower minimum and maximum temperatures for survival than B. pfeifferi populations (12.5–29.5°C vs. 14.0–31.5°C). B. glabrata populations survived over a smaller range of temperatures than either B. pfeifferi or B. alexandrina (17.0°C–29.5°C). Infection risk peaked at 16.5°C, 25.0°C and 19.0°C respectively when B. pfeifferi, B. glabrata and B. alexandrina were simulated. For all species, infection risk increased sharply once a minimum temperature was reached. Conclusions The results from all three species suggest that infection risk may increase dramatically with small increases in temperature in areas at or near the currents limits of schistosome transmission. The effect of small increases in temperature in areas where schistosomiasis is currently found will depend both on current temperatures and on the species of snail acting as intermediate host(s) in the area. In most areas where B. pfeifferi is the host, infection risk is likely to decrease. In cooler areas where B. glabrata is the host, infection risk may increase slightly. In cooler areas where B. alexandrina is the host, infection risk may more than double with only 2°C increase in temperature. Our results show that it is crucial to consider the species of intermediate host when attempting to predict the effects of climate change on schistosomiasis. PMID:24988377

McCreesh, Nicky; Booth, Mark



Spot light survey on fresh-water snails of medical importance in Al Fayoum Governorate, Egypt.  


In a survey carried out during Summer and Autumn of 2004, for snails of medical importance, nine species were recovered. These were Biomphalaria alexandrina, B. glabrata, B. pfeifferi, Bulinus truncatus, B. forskalii, Lymnaea natalensis, Bellamya (=Vivipara) unicolor, Physa acuta and Hydrobia musaensis. Parasitological examination revealed that B. alexandrina, B. glabrata and L. natalensis harboured immature stages of their concerned trematode parasites. Moreover, P. acuta harboured the immature stage of the nematode parasite Parastrongylus cantonensis. PMID:15880994

Abo-Madyan, Ahmed A; Morsy, Tosson A; Motawea, Saad M; El Garhy, Manal F; Massoud, Ahmed M A



[The water-cress pools in connection with cases of human fasciolasis in Limousin, France. Experimental studies of Trematode snails and their biological control (author's transl)].  


Experimental studies on 16 water-cress pools with cases of human fasciolasis in Limousin were undertaken. Two species of snails, Lymnaea glabra and L. truncatula are here trematode hosts. L. glabra alone lives in 5 pools. The introduction of Zonitoides nitidus -- predatory snail -- without vegetation modification produces a progressive elimination of Lymnaea in 3 years. The author insists on the use of determine the trematode host-aptitude of L. glabra and its limits when the two species -- L. glabra and L. truncatula -- live in the same habitats. PMID:754620

Rondelaud, D




EPA Science Inventory

The surface water component of the EPA Environmental Monitoring and Assessment Program (EMAP) Western Pilot is a five-year effort to assess the ecological condition of rivers and streams across 12 states in the western United States. EMAP is designed to monitor indicators of poll...


Surface Water and Groundwater  

NSDL National Science Digital Library

This site contains 25 questions on the topic of surface water and groundwater, which covers rivers and aquifers. This is part of the Principles of Earth Science course at the University of South Dakota. Users submit their answers and are provided immediate verification.

Heaton, Timothy


Impact of certain plants and synthetic molluscicides on some fresh water snails and fish.  


The LC50 (78, 85 ppm) and LC90 (88, 135 ppm) of Anagalis arvensis and Calendula micrantha respectively against Biomphalaria alexandrina were higher than those of the non-target snails, Physa acuta, Planorbis planorbis, Helisoma duryi and Melanoides tuberculata. In contrast, the LC50 of Niclosamide (0.11 ppm) and Copper sulphate (CuSO4) (0.42 ppm) against B. alexandrina were lower than those of the non-target snails. The mortalities percentage among non-target snails ranged between 0.0 & 20% when sublethal concentrations of CuSO4 against B. alexandrina mixed with those of C. micrantha and between 0.0 & 40% when mixed with A. arvensis. Mortalities ranged between 0.0 & 50% when Niclosamide was mixed with each of A. arvensis and C. micrantha. A. arvensis induced 100% mortality on Oreochromis niloticus after 48 hrs exposure and after 24 hrs for Gambusia affinis. C. micrantha was non-toxic to the fish. The survival rate of O. niloticus and G. affinis after 48 hrs exposure to 0.11 ppm of Niclosamide were 83.3% & 100% respectively. These rates were 91.7% & 93.3% respectively when each of the two fish species was exposed to 0.42 ppm of CuSO4. Mixture of sub-lethal concentrations of A. arvensis against B. alexandrina and those of Niclosamide or CuSO4 at ratios 10:40 & 25:25 induced 66.6% mortalities on O. niloticus and 83.3% at 40:10. These mixtures caused 100% mortalities on G. affinis at all ratios. A. arvensis CuSO4 mixtures at 10:40 induced 83.3% & 40% mortalities on O. niloticus and G. affinis respectively and 100% mortalities on both fish species at ratios 25:25 & 40:10. A mixture of sub-lethal concentrations of C. micrantha against B. alexandrina and of Niclosamide or CuSO4 caused mortalities of O. niloticus between 0.0 & 33.3% and between 5% & 35% of G. affinis. The residue of Cu in O. niloticus were 4.69, 19.06 & 25.37 mg/1kgm fish after 24, 48 & 72 hrs exposure to LC0 of CuSO4 against B. alexandrina respectively. PMID:16333905

Mosta-Fa, B B; el-Deeb, Fatma A; Ismail, Nahid M; el-Said, K M



Measuring Surface Water From Space  

Microsoft Academic Search

Surface fresh water is essential for life, yet we have surprisingly poor knowledge of the spatial and temporal dynamics of surface fresh water discharge and changes in storage globally. For example, we are unable to answer such basic questions as \\

J. Partsch; D. Alsdorf; E. Rodriguez; D. Lettenmaier; N. Mognard



Influence of an extreme high water event on survival, reproduction, and distribution of snail kites in Florida, USA  

USGS Publications Warehouse

Hydrology frequently has been reported as the environmental variable having the greatest influence on Florida snail kite (Rostrhamus sociabilis) populations. Although drought has received the most attention, high-water conditions also have been reported to affect kites. Years of high water generally have been reported to be favorable for nesting, although prolonged high water may be detrimental to sustaining suitable habitat. During 1994 and 1995, southern Florida experienced an extreme high water event. This event enabled us to compare survival, nesting success, number of young per successful nest, and spatial distribution of nesting before, during, and after the event. We found no evidence of an effect (either negative or positive) on survival of adult kites. In contrast, juvenile kites experienced the highest survival during the event, although our data suggest greater annual variability than can be explained by the event alone. We found no evidence of an effect of the high water event on nest success or number of young per successful nest. Nest success was highest during the event in the southern portion of the range but was quite similar to other years, both before and after the event. Our data do indicate a substantial shift in the spatial distribution of nesting birds. During the event, nesting activity shifted to higher elevations (i.e., shallower water) in the major nesting areas of the Everglades region. Nesting also occurred in Big Cypress National Preserve during the event, which is typically too dry to support nesting kites. Thus, our data indicate a potential short-term benefit of increased juvenile survival and an expansion of nesting habitat. However, the deterioration of habitat quality from prolonged high water precludes any recommendation for such conditions to be maintained for extended periods. ?? 2002, The Society of Wetland Scientists.

Bennetts, R.E.; Kitchens, W.M.; Dreitz, V.J.



Texas Surface Water Quality Standards  

E-print Network

1 Texas Surface Water Quality Standards 30 TAC Chapter 307 Lori Hamilton Water Quality Standards of the water quality standards for a water body will be conducted Types of UAAs Aquatic Life Use (ALU) UAAs 2 manager from the TMDL or NPS team (if applicable) Contact the TCEQ's Water Quality Standards Group


Histopathological effects of copper on selected epithelial tissues of snails  

SciTech Connect

The exposure of freshwater snails to copper sulfate has several harmful effects on the snails. These effects include several physiological disturbances as well as certain behavioral and histological changes. On the strength of these findings it was decided to investigate, by means of transmission electron microscopy, whether histological changes occur in the surface epithelium of the snail Bulinus tropicus after exposure to copper sulfate.

Wolmarans, C.T.; van Aardt, W.J.; Coetzee, J.



Measuring surface water from space  

Microsoft Academic Search

Surface fresh water is essential for life, yet we have surprisingly poor knowledge of the spatial and temporal dynamics of surface freshwater discharge and changes in storage globally. For example, we are unable to answer such basic questions as ``What is the spatial and temporal variability of water stored on and near the surface of all continents?'' Furthermore, key societal

Douglas E. Alsdorf; Ernesto Rodríguez; Dennis P. Lettenmaier



Measuring surface water from space  

Microsoft Academic Search

Surface fresh water is essential for life, yet we have surprisingly poor knowledge of the spatial and temporal dynamics of surface freshwater discharge and changes in storage globally. For example, we are unable to answer such basic questions as “What is the spatial and temporal variability of water stored on and near the surface of all continents?” Furthermore, key societal

Douglas E. Alsdorf; Ernesto Rodríguez; Dennis P. Lettenmaier



Surface Water Quality Standards  

E-print Network

of the water quali- ty standards, the overall process is expected to contin- ue into 2009.? For some, Texas? standards for contact recreation are not appropriate for many water bodies on the impaired list. Aaron Wendt, Texas State Soil and Water... of the water quali- ty standards, the overall process is expected to contin- ue into 2009.? For some, Texas? standards for contact recreation are not appropriate for many water bodies on the impaired list. Aaron Wendt, Texas State Soil and Water...

Wythe, Kathy



Sustaining dry surfaces under water  

E-print Network

Rough surfaces immersed under water remain practically dry if the liquid-solid contact is on roughness peaks, while the roughness valleys are filled with gas. Mechanisms that prevent water from invading the valleys are well studied. However, to remain practically dry under water, additional mechanisms need consideration. This is because trapped gas (e.g. air) in the roughness valleys can dissolve into the water pool, leading to invasion. Additionally, water vapor can also occupy the roughness valleys of immersed surfaces. If water vapor condenses, that too leads to invasion. These effects have not been investigated, and are critically important to maintain surfaces dry under water. In this work, we identify the critical roughness scale below which it is possible to sustain the vapor phase of water and/or trapped gases in roughness valleys - thus keeping the immersed surface dry. Theoretical predictions are consistent with molecular dynamics simulations and experiments.

Paul R. Jones; Xiuqing Hao; Eduardo R. Cruz-Chu; Konrad Rykaczewski; Krishanu Nandy; Thomas M. Schutzius; Kripa K. Varanasi; Constantine M. Megaridis; Jens H. Walther; Petros Koumoutsakos; Horacio D. Espinosa; Neelesh A. Patankar



To flee or not to flee? Risk assessment by a marine snail in multiple cue environments  

Microsoft Academic Search

Marine snails have two predator avoidance strategies: withdrawing into the refuge of their shells and fleeing by crawling away. Here we exposed the marine snail, Nucella ostrina, to water-borne cues from injured prey and a common predatory crab, singly and in combination. We determined whether snails avoided cues from the different cue sources and quantified how long snails spent in

Megan E. Mach; Paul E. Bourdeau



EPA Science Inventory

This is a 1:24,000-scale datalayer of Surface Water Quality Classifications for Connecticut. It is comprised of two 0Shapefiles with line and polygon features. Both Shapefiles must be used together with the Hydrography datalayer. The polygon Shapefile includes surface water qual...


Production of apple snail for space diet  

NASA Astrophysics Data System (ADS)

For food production in space at recycling bio-elements under closed environment, appropriate organisms should be chosen to drive the closed materials recycle loop. We propose a combination of green algae, photosynthetic protozoa, and aquatic plants such as Wolffia spp., for the primary producer fixing solar energy to chemical form in biomass, and apple snail, Pomacea bridgesii, which converts this biomass to animal meat. Because of high proliferation rate of green algae or protozoa compared to higher plants, and direct conversion of them to apple snail, the efficiency of food production in this combination is high, in terms of energy usage, space for rearing, and yield of edible biomass. Furthermore, green algae and apple snail can form a closed ecological system with exchanging bio-elements between two member, i.e. excreta of snail turn to fertilizer of algae, and grown algae become feed for snail. Since apple snail stays in water or on wet substrate, control of rearing is easy to make. Mass production technology of apple snail has been well established to utilize it as human food. Nutrients of apple snail are also listed in the standard tables of food composition in Japan. Nutrients for 100 g of apple snail canned in brine are energy 340 kJ, protein 16.5 g, lipid 1.0 g, cholesterol 240 mg, carbohydrate 0.8 g, Ca 400 mg, Fe 3.9 mg, Zn 1.5 mg. It is rich in minerals, especially Ca and Fe. Vitamin contents are quite low, but K 0.005 mg, B2 0.09 mg, B12 0.0006 mg, folate 0.001 mg, and E 0.6 mg. The amino acid score of apple snail could not be found in literature. Overall, apple snail provides rich protein and animal lipid such as cholesterol. It could be a good source of minerals. However, it does not give enough vitamin D and B12 , which are supposed to be supplemented by animal origin foods. In terms of acceptance in food culture, escargot is a gourmet menu in French dishes, and six to ten snail, roughly 50 g, are served for one person. Apple snail reaches to 30 g of body weight within two or three month from its egg. Several hundreds of egg are laid by one snail. It start egg laying after three months from hatching. In order to harvest 50 g for every day's meal, 3 m2 is required for rearing space. Eating apple snail and establishing its rearing system might save the food crisis on Earth.

Yamashita, Masamichi; Motoki, Shigeru; Space Agriculture Task Force, J.; Katayama, Naomi


Regulation of laboratory populations of snails (Biomphalaria and Bulinus spp.) by river prawns, Macrobrachium spp. (Decapoda, Palaemonidae): implications for control of schistosomiasis.  


Human schistosomiasis is a common parasitic disease endemic in many tropical and subtropical countries. One barrier to achieving long-term control of this disease has been re-infection of treated patients when they swim, bathe, or wade in surface fresh water infested with snails that harbor and release larval parasites. Because some snail species are obligate intermediate hosts of schistosome parasites, removing snails may reduce parasitic larvae in the water, reducing re-infection risk. Here, we evaluate the potential for snail control by predatory freshwater prawns, Macrobrachium rosenbergii and M. vollenhovenii, native to Asia and Africa, respectively. Both prawn species are high value, protein-rich human food commodities, suggesting their cultivation may be beneficial in resource-poor settings where few other disease control options exist. In a series of predation trials in laboratory aquaria, we found both species to be voracious predators of schistosome-susceptible snails, hatchlings, and eggs, even in the presence of alternative food, with sustained average consumption rates of 12% of their body weight per day. Prawns showed a weak preference for Bulinus truncatus over Biomphalaria glabrata snails. Consumption rates were highly predictable based on the ratio of prawn: snail body mass, suggesting satiation-limited predation. Even the smallest prawns tested (0.5-2g) caused snail recruitment failure, despite high snail fecundity. With the World Health Organization turning attention toward schistosomiasis elimination, native prawn cultivation may be a viable snail control strategy that offers a win-win for public health and economic development. PMID:24388955

Sokolow, Susanne H; Lafferty, Kevin D; Kuris, Armand M



Cercarial Dermatitis Transmitted by Exotic Marine Snail  

PubMed Central

Cercarial dermatitis (swimmer’s itch) is caused by the penetration of human skin by cercariae of schistosome parasites that develop in and are released from snail hosts. Cercarial dermatitis is frequently acquired in freshwater habitats, and less commonly in marine or estuarine waters. To investigate reports of a dermatitis outbreak in San Francisco Bay, California, we surveyed local snails for schistosome infections during 2005–2008. We found schistosomes only in Haminoea japonica, an Asian snail first reported in San Francisco Bay in 1999. Genetic markers place this schistosome within a large clade of avian schistosomes, but do not match any species for which there are genetic data. It is the second known schistosome species to cause dermatitis in western North American coastal waters; these species are transmitted by exotic snails. Introduction of exotic hosts can support unexpected emergence of an unknown parasite with serious medical or veterinary implications. PMID:20735918

Cohen, Andrew N.; James, David; Hui, Lucia; Hom, Albert; Loker, Eric S.



The toxicity and physiological effects of copper on the freshwater pulmonate snail, Lymnaea stagnalis  

E-print Network

Keywords: Gastropods Lymnaea stagnalis Copper Water quality criteria Ionoregulation Acid­base balance Several recent studies have demonstrated that the freshwater pulmonate snail Lymnaea stagnalisThe toxicity and physiological effects of copper on the freshwater pulmonate snail, Lymnaea

Grosell, Martin


Integrating Nonindigenous Aquatic Plant Control with Protection of Snail Kite Nests in Florida  

Microsoft Academic Search

The endangered snail kite (Rostrhamus sociabilis) feeds primarily on the freshwater apple snail (Pomacea paludosa) in Florida. The nonindigenous, floating water hyacinth (Eichhornia crassipes) and water lettuce (Pistia stratiotes) impede kites from finding snails. Effective control of these aquatic plants in the littoral zone of central and south Florida\\u000a lakes benefits kites by maintaining open foraging habitat. However, incidental herbicide




Biogeography: molecular trails from hitch-hiking snails.  


Darwin was fascinated by the transportation of land snails across great swathes of open ocean by birds--he even immersed snails in sea water to see how long they would survive. Here we follow a molecular phylogenetic trail that reveals the incredible transequatorial dispersal of the land snail Balea from Europe to the Azores and the Tristan da Cunha islands, and back again. This long-distance dispersal is unexpected for what are proverbially considered the most pedestrian of creatures. PMID:16437103

Gittenberger, Edmund; Groenenberg, Dick S J; Kokshoorn, Bas; Preece, Richard C



Sources of Water Surface water and groundwater are present throughout  

E-print Network

for agriculture, and 3,430 million gallons for cooling at thermoelectric power plants. � Surface water providesSources of Water Surface water and groundwater are present throughout Kentucky's 39,486 square miles. Surface water occurs as rivers, streams, ponds, lakes, and wetlands. Ground- water occurs

MacAdam, Keith


Models of Snail Locomotion  

NASA Astrophysics Data System (ADS)

All snails move over a thin layer of mucus using periodic deformations of their muscular foot. This unusual mode of locomotion can be modeled as a thin film of viscous fluid sandwiched between a flexible membrane and a rigid substrate. We present theoretical, numerical and experimental studies of locomotion via viscous stresses generated in thin films. Study of snail locomotion led us to design and construct several mechanical models: RoboSnail 1 which mimics snail locomotion incorrectly, but still proves to be a valid propulsion device over a thin viscous fluid layer and RoboSnail 2 which mimics land snails and uses forward-propagating compression waves on the base of the foot. Experimental results from the prototype machines are compared with long wavelength numerical and theoretical models.

Chan, Brian; Hosoi, Anette



Influence of snail feces and mucus on oviposition and larval behavior ofPherbellia cinerella (Diptera: Sciomyzidae).  


Larvae of the sciomyzid flyPherbellia cinerella are voracious predators of terrestrial helicid snails. Eggs are deposited in areas where snails occur and larvae hunt actively for their prey. Snail feces and mucus were tested to determine if they had any kairomone or stimulatory effects onP. cinerella. Adult flies oviposited more frequently on substrates containing fresh snail feces than on substrates containing snail mucus or water (control). However, mucus and feces both stimulated increased search behaviour in first instar larvae. These results are discussed in relation to snail biology, and the potential for augmentation of these flies in areas affected by pest snails. PMID:24227402

Coupland, J B



Predation Risk and Avoidance Behavior in Two Freshwater Snails  

Microsoft Academic Search

We examined the predator avoidance behav- iors of two common freshwater snails, Physella virgata and Planorbella trivolvis, to the crayfish Procambarus simulans. In response to crayfish predation, the snails crawled above the waterline for several hours, then re- turned to the water. A significant size-dependent rela- tionship existed between crawlout (vertical migration above the waterline) and vulnerability to predation. All




Surface Water Development in Texas.  

E-print Network

.................................. 14 Counties and Cities ............................... 14 Water Districts .................................... 14 State Water Agencies ................................. 15 Board of Water Engineers ......................... 15 Water Rights... Commission ......................... 15 Water Development Board ......................... 15 Federal Water Agencies ............................... 18 U.S. Army Corps of Engineers ...................... 18 Bureau of Reclamation...

McNeely, John G.; Lacewell, Ronald D.



The effect of ecological parameters on the distribution of snail vectors of schistosomiasis.  


The infestation of the water courses showed 32.5% for Biomphalaria alexandrina and 8.75% for Bulinus truncatus. Ecological parameters, showed non significant variations in the water courses harbouring snail vectors and those free from snails except for conductivity in the habitats harbouring B. truncatus. This variation was more highly significant (p<0.001). Of the examined sites, 11.25% were harbouring B. alexandrina and Lymnaea natalenesis living together and 5% of the sites were harbouring B. truncatus and Physa acuta snails. Snail vectors were distributed with different degrees with aquatic plants reflecting the degree of species preference plants for snails' life. PMID:12557938

Kader, A A



Source Water Assessment for the Las Vegas Valley Surface Waters  

Microsoft Academic Search

The 1996 amendment to the Safe Drinking Water Act of 1974 created the Source Water Assessment Program (SWAP) with an objective to evaluate potential sources of contamination to drinking water intakes. The development of a Source Water Assessment Plan for Las Vegas Valley surface water runoff into Lake Mead is important since it will guide future work on source water

S. P. Albuquerque; T. C. Piechota



Effective Watershed Management for Surface Water Supplies  

Microsoft Academic Search

Maintaining the best possible water quality is the goal of every surface water source protection program. Watershed management can play an important role in maintaining or enhancing water quality for both filtered and unfiltered systems. The AWWA Research Foundation recently published a study on effective watershed management for surface water supplies. This article presents results of this investigation, which was

Richard W. Robbins; Joseph L. Glicker; Douglas M. Bloem; Bruce M. Niss



Surface Water Storage on Annual Ryegrass  

Microsoft Academic Search

Surface water storage is the water held on plant surfaces after the application of artificial rain. It approximates the storage component in interception loss equations. Surface ratio was shown by Horton (1919) to be a factor in interception loss by evaporation during a storm. Surface ratio is shown here also to be a factor in the storage component of interception

Robert A. Merriam



Dragonfly predators influence biomass and density of pond snails.  


Studies in lakes show that fish and crayfish predators play an important role in determining the abundance of freshwater snails. In contrast, there are few studies of snails and their predators in shallow ponds and marshes. Ponds often lack fish and crayfish but have abundant insect populations. Here we present the results of field surveys, laboratory foraging trials, and an outdoor mesocosm experiment, testing the hypothesis that insects are important predators of pulmonate snails. In laboratory foraging trials, conducted with ten species of insects, most insect taxa consumed snails, and larval dragonflies were especially effective predators. The field surveys showed that dragonflies constitute the majority of the insect biomass in fishless ponds. More focused foraging trials evaluated the ability of the dragonflies Anax junius and Pantala hymenaea to prey upon different sizes and species of pulmonate snails (Helisoma trivolvis, Physa acuta, and Stagnicola elodes). Anax junius consumed all three species up to the maximum size tested. Pantala hymenaea consumed snails with a shell height of 3 mm and smaller, but did not kill larger snails. P. acuta were more vulnerable to predators than were H. trivolvis or S. elodes. In the mesocosm experiment, conducted with predator treatments of A. junius, P. hymenaea, and the hemipteran Belostoma flumineum, insect predators had a pronounced negative effect on snail biomass and density. A. junius and B. flumineum reduced biomass and density to a similar degree, and both reduced biomass more than did P. hymenaea. Predators did not have a strong effect on species composition. A model suggested that A. junius and P. hymenaea have the largest effects on snail biomass in the field. Given that both pulmonate snails and dragonfly nymphs are widespread and abundant in marshes and ponds, snail assemblages in these water bodies are likely regulated in large part by odonate predation. PMID:17457617

Turner, Andrew M; Chislock, Michael F




EPA Science Inventory

Numerous pesticides were monitored in surface waters in agricultural areas. Atrazine, alachlor, metolachlor, cyanazine, metribuzin, carbofuran, linuron, and simazine were found in the influent to three water treatment plants in storm runoff following their application. Studies at...


Atrazine does not affect algal biomass or snail populations in microcosm communities at environmentally relevant concentrations.  


The herbicide atrazine is a photosynthetic inhibitor used around the world in agricultural applications. Contamination of surface waters adjacent to treated areas can directly reduce growth of nontarget aquatic autotrophs, but the severity of impacts is highly dependent on species sensitivity and exposure concentration. Secondary effects resulting from macrophyte or phytoplankton decline may include an expansion of the more tolerant periphyton community. Recently, this shift in the autotrophic community has been proposed as a mechanism for increased rates of parasite infections in amphibians via augmented populations of aquatic snails which act as intermediate hosts to larval trematodes. To further clarify this relationship, an outdoor microcosm study was conducted to examine the effects of atrazine on primary production and snail populations over a range of environmentally relevant concentrations. In July 2009, 15 experimental ponds were treated to achieve initial concentrations of 0, 1, 10, 30, and 100 µg/L atrazine. Over a period of 73 d, measures were taken of macrophyte, phytoplankton, and periphyton biomass, growth, and fecundity of caged snails (Physella spp. and Stagnicola elodes) and free-living snails (Physella spp.). Except for declines in macrophyte biomass at the highest treatment level, no consistent relationships were found between atrazine concentration and any measured parameter. Comparison of these results with previous findings highlights the variability of responses to atrazine exposure between similarly constructed freshwater communities, even at concentrations up to 20 times higher than sustained environmental levels. PMID:21567448

Baxter, Leilan R; Moore, Dana L; Sibley, Paul K; Solomon, Keith R; Hanson, Mark L



USGS Surface Water Information: Flood Information  

NSDL National Science Digital Library

This site from the USGS Office of Surface Water provides access to many resources and data sets about current and past flooding events in the United States. There are links to maps showing current water conditions, 28 day National Weather Service forecasts, Water Science Centers in the various states, as well as national and local flooding resources. There are also links to other parts of the USGS Surface Water Information site which host a variety of data and information resources.

Water, Usgs O.


Water-Drop-Surface-Wave Interactions  

Microsoft Academic Search

Splashes of water drops on liquid surfaces are important phenomena in several fields, notably the geosciences where they determine some transport rates and atmospheric-electrification processes. Splashes on smooth liquid surfaces have been well described, but in actual field situations splashes usually oc'cur on disturbed surfaces. This report describes two new types of splashes that occur in the presence of surface

G. L. Siscoe; Zev Levin



Habitat-specific variation in life-history traits, clonal population structure and parasitism in a freshwater snail (Potamopyrgus antipodarum)  

Microsoft Academic Search

High risk of infection by parasites may select for early reproduction in natural host populations. In a previous study of a freshwater snail (Potamopyrgus antipodarum) we found (1) that different clones of the snail are associated with different depth-structured vegetation zones and (2) that snails in shallow water, where the age-specific risk of infection is highest, mature at a smaller




Modeling snail breeding in Bioregenerative Life Support System  

NASA Astrophysics Data System (ADS)

It is known that snail meat is a high quality food that is rich in protein. Hence, heliciculture or land snail farming spreads worldwide because it is a profitable business. The possibility to use the snails of Helix pomatia in Biological Life Support System (BLSS) was studied by Japanese Researches. In that study land snails were considered to be producers of animal protein. Also, snail breeding was an important part of waste processing, because snails were capable to eat the inedible plant biomass. As opposed to the agricultural snail farming, heliciculture in BLSS should be more carefully planned. The purpose of our work was to develop a model for snail breeding in BLSS that can predict mass flow rates in and out of snail facility. There are three linked parts in the model called “Stoichiometry”, “Population” and “Mass balance”, which are used in turn. Snail population is divided into 12 age groups from oviposition to one year. In the submodel “Stoichiometry” the individual snail growth and metabolism in each of 12 age groups are described with stoichiometry equations. Reactants are written on the left side of the equations, while products are written on the right side. Stoichiometry formulas of reactants and products consist of four chemical elements: C, H, O, N. The reactants are feed and oxygen, products are carbon dioxide, metabolic water, snail meat, shell, feces, slime and eggs. If formulas of substances in the stoichiometry equations are substituted with their molar masses, then stoichiometry equations are transformed to the equations of molar mass balance. To get the real mass balance of individual snail growth and metabolism one should multiply the value of each molar mass in the equations on the scale parameter, which is the ratio between mass of monthly consumed feed and molar mass of feed. Mass of monthly consumed feed and stoichiometry coefficients of formulas of meat, shell, feces, slime and eggs should be determined experimentally. An age structure and size of snail population are optimized on the base of individual growth and metabolic characteristics with the help of the second submodel "Population". In this simulation a daily amount of snail meat consumed by crewmembers is a guideline which specifies population productivity. Also, the daily amount of snail meat may have an optional value. Prescribed population characteristics are used in the third submodel "Mass balance" to equalize input and output mass flow rates of snail facility. In this submodel we add a water and ash to the organic masses of feed, meat, feces, shell and eggs. Moreover, masses of calcium carbonate and potable water are added to the left side of mass balance equations. Mass of calcium carbonate is distributed among shell, feces and eggs. Summarizing the twelve equations for each snail age, we get the mass balance equation for the snail facility. All simulations are performed by using Solver Add-In for Excel 2007.

Kovalev, Vladimir; Tikhomirov, Alexander A.; Nickolay Manukovsky, D..


Streaks Of Colored Water Indicate Surface Airflows  

NASA Technical Reports Server (NTRS)

Response faster and contamination less than in oil-flow technique. Flowing colored water provides accurate and clean way to reveal flows of air on surfaces of models in wind tunnels. Colored water flows from small orifices in model, forming streak lines under influence of air streaming over surface of model.

Wilcox, Floyd J., Jr.



Surface-Water Data for the Nation  

NSDL National Science Digital Library

This USGS site presents surface-water data. It includes detailed information from a number of sites around the nation. Real-time, recent, and streamflow data is included, as well as field measurements and a tutorial explaining how to perform a surface water retrieval and understand the results.



Gray solitons on the surface of water.  


The dynamics of surface gravity water waves can be described by the self-defocusing nonlinear Schrödinger equation. Recent observations of black solitons on the surface of water confirmed its validity for finite, below critical depth. The black soliton is a limiting case of a family of gray soliton solutions with finite amplitude depressions. Here, we report observations of gray solitons in water waves, thus, complementing our previous observations of black solitons. PMID:24580162

Chabchoub, A; Kimmoun, O; Branger, H; Kharif, C; Hoffmann, N; Onorato, M; Akhmediev, N



Anthropogenic impacts on continental surface water fluxes  

Microsoft Academic Search

Impacts of reservoirs and irrigation water withdrawals on continental surface water fluxes are studied within the framework of the Variable Infiltration Capacity (VIC) model for a part of North America, and for Asia. A reservoir model, designed for continental-scale simulations, is developed and implemented in the VIC model. The model successfully simulates irrigation water requirements, and captures the main effects

Ingjerd Haddeland; Thomas Skaugen; Dennis P. Lettenmaier



Phenolic compounds in surface water  

Microsoft Academic Search

The presence of phenols in a stream is undesired because of their strong action, their toxicity to fish and unpleasant tastes and odours produced when water containing phenols is chlorinated.The phenolic compounds in the water environment may have a natural, industrial, domestic or agricultural origin.The purpose of this paper is to determine the nature, origin and trend of phenolic compounds

Franco Gnudi



Small Snails, Enormous Elephants  

NSDL National Science Digital Library

This activity (located on page 2 of PDF) introduces learners to the real size of animals using nonstandard measurement. Learners use Unifix cubes and yarn lengths to measure a variety of animals (photos), from the very small like a snail to the very large like an elephant. As an extension, learners can use the cubes to create a bar graph depicting the animals' lengths.

Museum, Chicago C.



Lichen Endozoochory by Snails  

PubMed Central

Endozoochory plays a prominent role for the dispersal of seed plants. However, for most other plant taxa it is not known whether this mode of dispersal occurs at all. Among those other taxa, lichens as symbiotic associations of algae and fungi are peculiar as their successful dispersal requires movement of propagules that leaves the symbiosis functional. However, the potential for endozoochorous dispersal of lichen fragments has been completely overlooked. We fed sterile thalli of two foliose lichen species (Lobaria pulmonaria and Physcia adscendens) differing in habitat and air-quality requirements to nine snail species common in temperate Europe. We demonstrated morphologically that L. pulmonaria regenerated from 29.0% of all 379 fecal pellets, whereas P. adscendens regenerated from 40.9% of all 433 fecal pellets, showing that lichen fragments survived gut passage of all snail species. Moreover, molecular analysis of regenerated lichens confirmed the species identity for a subset of samples. Regeneration rates were higher for the generalist lichen species P. adscendens than for the specialist lichen species L. pulmonaria. Furthermore, lichen regeneration rates varied among snail species with higher rates after gut passage of heavier snail species. We suggest that gastropods generally grazing on lichen communities are important, but so far completely overlooked, as vectors for lichen dispersal. This opens new ecological perspectives and questions the traditional view of an entirely antagonistic relationship between gastropods and lichens. PMID:21533256

Boch, Steffen; Prati, Daniel; Werth, Silke; Ruetschi, Jorg; Fischer, Markus



A Review of Surface Water Quality Models  

PubMed Central

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

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



Evidence for water structuring forces between surfaces  

SciTech Connect

Structured water on apposing surfaces can generate significant energies due to reorganization and displacement as the surfaces encounter each other. Force measurements on a multitude of biological structures using the osmotic stress technique have elucidated commonalities that point toward an underlying hydration force. In this review, the forces of two contrasting systems are considered in detail: highly charged DNA and nonpolar, uncharged hydroxypropyl cellulose. Conditions for both net repulsion and attraction, along with the measured exclusion of chemically different solutes from these macromolecular surfaces, are explored and demonstrate features consistent with a hydration force origin. Specifically, the observed interaction forces can be reduced to the effects of perturbing structured surface water.

Stanley, Christopher B [ORNL; Rau, Dr. Donald [National Institutes of Health



Subsurface And Surface Water Flow Interactions  

EPA Science Inventory

In this chapter we present basic concepts and principles underlying the phenomena of groundwater and surface water interactions. Fundamental equations and analytical and numerical solutions describing stream-aquifer interactions are presented in hillslope and riparian aquifer en...


Assessing Phosphorous Loss to Protect Surface Water  

E-print Network

programs. It is an integrated approach that considers soil and landscape features in order tx H2O | pg. 10 Assessing Phosphorus Loss to Protect Surface Water to find appropriate phosphorus management practices by estimating phosphorus delivery... programs. It is an integrated approach that considers soil and landscape features in order tx H2O | pg. 10 Assessing Phosphorus Loss to Protect Surface Water to find appropriate phosphorus management practices by estimating phosphorus delivery...

Garcia, Raul



Eye to Eye With Garden Snails  

NSDL National Science Digital Library

This Snail Unit encourages students to explore the external characteristics and behavior of snails. It effectively gets students past the "ugh, slime" reaction to recognizing individual differences in snails and challenges students to learn enough about the snail to be able to predict their behavior under a variety of conditions. Detailed observations are requested as are preparation and testing of hypotheses. This unit works very well with all levels of students and with heterogeneously grouped students. This Snail Unit consists of six lessons: (1) Introduction to a Snail (2) How do snails move? How fast is a snail's pace? (3) What and how do snails eat? (4) Are snails attracted to, or repelled by particular substances? (5) Can snails be enticed to travel faster or in a certain direction? (6) How are snails like other animals? How are they different?

BEGIN:VCARD VERSION:2.1 FN:Kathy Liu N:Liu;Kathy ORG:Access Excellence REV:2005-04-19 END:VCARD



Predator-Induced Life-History Shifts in a Freshwater Snail  

Microsoft Academic Search

The snail Physella virgata virgata, a widely distributed freshwater pulmonate, was observed to change its life-history characteristics in the presence of the crayfish Orconectes virilis in spring-fed Oklahoma streams. These changes were apparently initiated by a water-borne cue released when crayfish fed on conspecific snails. In the presence of the cue, snails exhibited rapid growth rates and little reproduction until

Todd A. Crowl; Alan P. Covich



Predator avoidance by the freshwater snail Physella virgata in response to the crayfish Procambarus simulans  

Microsoft Academic Search

We examined predator avoidance behavior of the freshwater snailPhysella (=Physa) virgata in response to the crayfishProcambarus simulans. In both laboratory and field enclosure experiments snails crawled above the waterline for 2 h or longer, then returned to the water.Physella virgata react to chemical signals given off by crayfish actively foraging on conspecific snails; they do not react to inactive crayfish.

J. E. Alexander; A. P. Covich



Water desorption from nanostructured graphite surfaces.  


Water interaction with nanostructured graphite surfaces is strongly dependent on the surface morphology. In this work, temperature programmed desorption (TPD) in combination with quadrupole mass spectrometry (QMS) has been used to study water ice desorption from a nanostructured graphite surface. This model surface was fabricated by hole-mask colloidal lithography (HCL) along with oxygen plasma etching and consists of a rough carbon surface covered by well defined structures of highly oriented pyrolytic graphite (HOPG). The results are compared with those from pristine HOPG and a rough (oxygen plasma etched) carbon surface without graphite nanostructures. The samples were characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The TPD experiments were conducted for H2O coverages obtained after exposures between 0.2 and 55 langmuir (L) and reveal a complex desorption behaviour. The spectra from the nanostructured surface show additional, coverage dependent desorption peaks. They are assigned to water bound in two-dimensional (2D) and three-dimensional (3D) hydrogen-bonded networks, defect-bound water, and to water intercalated into the graphite structures. The intercalation is more pronounced for the nanostructured graphite surface in comparison to HOPG surfaces because of a higher concentration of intersheet openings. From the TPD spectra, the desorption energies for water bound in 2D and 3D (multilayer) networks were determined to be 0.32 ± 0.06 and 0.41 ± 0.03 eV per molecule, respectively. An upper limit for the desorption energy for defect-bound water was estimated to be 1 eV per molecule. PMID:24018989

Clemens, Anna; Hellberg, Lars; Grönbeck, Henrik; Chakarov, Dinko



Hierarchical contribution of river–ocean connectivity, water chemistry, hydraulics, and substrate to the distribution of diadromous snails in Puerto Rican streams  

Microsoft Academic Search

Diadromous faunas dominate most tropical coastal streams and rivers, but the factors controlling their distribution are not well understood. Our study documents abiotic variables controlling the distribution and abundance of the diadromous snail Neritina virginea (Gastropoda:Neritidae) in the Caribbean island of Puerto Rico. An intensive survey of N. virginea density and shell size, and channel substrate, velocity, and depth was

Juan F. Blanco; Frederick N. Scatena



Variation of snail's abundance in two water bodies harboring strains of Pseudosuccinea columella resistant and susceptible to Fasciola hepatica miracidial infection, in Pinar del Río Province, Cuba.  


The abundance of freshwater snails in two rural sites of Pinar del Río, Cuba, which harbor Pseudosuccinea columella susceptible and resistant to miracidia of Fasciola hepatica was followed for one year. Susceptible snails were found in the most anthropic site (IPA) whereas the resistant population inhabited the most preserved one (El Azufre). Only two snail species coexisted with P. columella at IPA site (Physa cubensis and Tarebia granifera) while five species were found at El Azufre, including an endemic from that province (Hemisinus cubanianus). Populations of both resistant and susceptible snails showed stable densities throughout the year, although the susceptible strain attained higher abundance. The highest densities were observed in April-May 2004 for the susceptible population whereas the resistant strain attained its highest abundance in January 2004. No record of Fossaria cubensis was made and the thiarid T. granifera occurred only at low densities. One of the sampled sites (IPA) meets all the conditions for the first report of P. columella naturally infected with larvae of F. hepatica. PMID:16410958

Gutiérrez, Alfredo; Hernandez, Dagmar F; Sánchez, Jorge



Use of Bayluscide (Bayer 73) for Snail Control in Fish Ponds  

Microsoft Academic Search

Bayluscide applied to ponds on two commercial fish farms at five rates (from L1 to 13.5 kilogram per surface hectare) effectively controlled aquatic snails. Laboratory toxicity tests confirmed susceptibility of three endemic species of aquatic snail—Melanoides tuberculatus, Physella hendersoni, and Planorbella duryi—to Bayluscide. Observed 24-h concentrations lethal to 50% of snails (LC50) ranged from 0.062 to 0.085 mg\\/L, and 24-h

Ruth Francis-Floyd; James Gildea; Peggy Reed; Ruthellen Klinger



Heavy metal concentrations in the freshwater snail Biomphalaria alexandrina uninfected or infected with cercariae of Schistosoma mansoni and/or Echinostoma liei in Egypt: the potential use of this snail as a bioindicator of pollution.  


In spite of using aquatic snails as bioindicators for water pollution, little attention has been paid to the effect of parasitism upon the concentration of heavy metals (Al, Cd, Cu, Fe, Mn, Pb and Zn) in these organisms. The present study therefore aimed to compare the concentrations of heavy metals in trematode-infected Biomphalaria alexandrina collected from Kafer Alsheikh and Menofia provinces, Egypt, with uninfected snails from the same sites, in order to assess the effect of parasitism on the use of these snails as bioindicators. The concentrations of heavy metals in the soft parts and shells of snails were measured by flame atomic absorption spectrometry. The results showed that the heavy metal profile in snails infected with Echinostoma liei was very different from that in snails infected with Schistosoma mansoni. The total concentration of heavy metals in E. liei-infected snails collected from Kafer Alsheikh or Menofia province was greater than in uninfected snails. In contrast, the total concentration of heavy metals in S. mansoni-infected snails was reduced compared with uninfected snails. In conclusion, the status of snails with respect to parasitic infection must be taken into consideration when these snails are used as bioindicators. PMID:23710821

Mostafa, O M S; Mossa, A-T H; El Einin, H M A



Nano-confined water on surfaces of metal oxide nanoparticles  

Microsoft Academic Search

Nanolayers of water interacting with metal oxide surfaces demonstrate physical properties that are significantly different from those of bulk water and ice. Our recent water adsorption experiments suggest that the entropy of surface water is lower than those of bulk water and ice implying restricted motion of the water on the surface. We have studied dynamics of water on nanoparticles

Andrey Levchenko; Juliana Boerio-Goates; Brian Woodfield; Alexander Kolesnikov; Nancy Ross; David Wesolowski; David Cole; Alexandra Navrotsky



What's So Special about Water: Surface Tension  

NSDL National Science Digital Library

In this three-part activity, learners play a game and conduct two simple experiments to explore water and surface tension. Learners will have fun discovering how water "sticks" together. This lesson guide includes instructions for three mini activities, key vocabulary words, extension ideas, helpful hints, and resources. Educators can also use this "sticking together" activity to emphasize the importance of empathy and listening.

Bowers, Sally



Physicochemical properties of concentrated Martian surface waters  

E-print Network

Physicochemical properties of concentrated Martian surface waters Nicholas J. Tosca,1 Scott M. Mc mineral deposits in the Valles Marineris region, and the possible role of saline waters in forming recent and allow more accurate predictions of thermal behavior and the diffusive transport of matter through


Water Adsorption on Lubricated Carbon Surface  

NASA Astrophysics Data System (ADS)

The fundamental properties of adsorption, i.e., molecular mobility and interaction energy between lubricants, water, and overcoats, are investigated for perfluorinated polyether (PFPE) lubricants on carbon surfaces in order to design mechanically reliable magnetic storage devices. The interaction between PFPE molecules and water molecules on carbon surfaces in dry and humid environments is analyzed using nuclear magnetic resonance (NMR). Two NMR spectrum peaks of water on carbon surfaces on which the PFPE diol is coated are observed when humid air of 90% relative humidity (RH) is introduced. One peak at a low chemical shift corresponds to the adsorbed water on the carbon surface. The other peak at a high chemical shift shows sorbed water molecules in the PFPE diol film. Minimum molecular mobility is observed for OH groups, i.e., adsorption sites, in dry air. However, the molecular mobility increases because of the lubricant desorption when humid air is introduced. The increased spin-lattice relaxation time (T1) for the proton in the OH group reveals the desorption phenomena. Adsorption energies between the adsorbates (lubricants and water) and the adsorbent (carbon powder) are measured using a flow micro-calorimeter. When water vapor is introduced, the negative heat of adsorption is observed, which indicates the lubricant desorption caused by the water molecules.

Yanagisawa, Masahiro



Water drop friction on superhydrophobic surfaces.  


To investigate water drop friction on superhydrophobic surfaces, the motion of water drops on three different superhydrophobic surfaces has been studied by allowing drops to slide down an incline and capturing their motion using high-speed video. Two surfaces were prepared using crystallization of an alkyl ketene dimer (AKD) wax, and the third surface was the leaf of a Lotus (Nelumbo Nucifera). The acceleration of the water droplets on these superhydrophobic surfaces was measured as a function of droplet size and inclination of the surface. For small capillary numbers, we propose that the energy dissipation is dominated by intermittent pinning-depinning transitions at microscopic pinning sites along the trailing contact line of the drop, while at capillary numbers exceeding a critical value, energy dissipation is dominated by circulatory flow in the vicinity of the contacting disc between the droplet and the surface. By combining the results of the droplet acceleration with a theoretical model based on energy dissipation, we have introduced a material-specific coefficient called the superhydrophobic sliding resistance, b(sh). Once determined, this parameter is sufficient for predicting the motion of water drops on superhydrophobic surfaces of a general macroscopic topography. This theory also infers the existence of an equilibrium sliding angle, ?(eq), at which the drop acceleration is zero. This angle is decreasing with the radius of the drop and is in quantitative agreement with the measured tilt angles required for a stationary drop to start sliding down an incline. PMID:23721176

Olin, Pontus; Lindström, Stefan B; Pettersson, Torbjörn; Wågberg, Lars



How Water Meets a Very Hydrophobic Surface  

NASA Astrophysics Data System (ADS)

Is there a low-density region (“gap”) between water and a hydrophobic surface? Previous x-ray and neutron reflectivity results have been inconsistent because the effect (if any) is subresolution for the surfaces studied. We have used x-ray reflectivity to probe the interface between water and more hydrophobic smooth surfaces. The depleted region width increases with contact angle and becomes larger than the resolution, allowing definitive measurements. Large fluctuations are predicted at this interface; however, we find that their contribution to the interface roughness is too small to measure.

Chattopadhyay, Sudeshna; Uysal, Ahmet; Stripe, Benjamin; Ha, Young-Geun; Marks, Tobin J.; Karapetrova, Evguenia A.; Dutta, Pulak



Baldomero Olivera: Cone Snail Peptides  

NSDL National Science Digital Library

Have you ever considered the venom of a snail? Most people think of snakes when they think of venom but overlook snails. There are, however, almost 10,000 species of venomous predatory snails according to this engaging lecture from Professor Baldomero Olivera. In his talk, Professor Olivera explores how these venoms have been used to understand the nervous system and develop new drugs. The lecture is divided into three different sections, and visitors shouldn't miss Part 2 ("How a Fish Hunting Snail Captures Its Prey"). Visitors are also welcome to download the entire lecture and the accompanying slides.

Olivera, Baldomero


Baldomero Olivera: Cone Snail Peptides  

NSDL National Science Digital Library

Have you ever considered the venom of a snail? Most people think of snakes when they think of venom but overlook snails. There are, however, almost 10,000 species of venomous predatory snails according to this engaging lecture from Professor Baldomero Olivera. In his talk, Professor Olivera explores how these venoms have been used to understand the nervous system and develop new drugs. The lecture is divided into three different sections, and visitors shouldn't miss Part 2 ("How a Fish Hunting Snail Captures Its Prey"). Visitors are also welcome to download the entire lecture and the accompanying slides.

Olivera, Baldomero



Larval stages of digenetic trematodes in Melanopsis praemorsa snails from freshwater bodies in Palestine  

PubMed Central

Objective To detect the species of larval trematodes (cercariae) in Melanopsis praemorsa snails from 5 different fresh water bodies in Palestine. Methods A total of 1 880 Melanopsis praemorsa snails were collected from different fresh water bodies in Palestine from October, 2008 to November, 2010. Cercariae in Melanopsis praemorsa snails were obtained by lighting and crushing methods. The behavior of cercariae was observed using a dissecting microscope. Results Three different species of larval trematodes were identified from Melanopsis praemorsa snails collected only from Al-Bathan fresh water body, while snails from other water bodies were not infected. These species were microcercous cercaria, xiphidiocercaria and brevifurcate lophocercous cercaria. These cercariae called Cercaria melanopsi palestinia I, Cercaria melanopsi palestinia II and Cercaria melanopsi palestinia III have not been described before from this snail in Palestine. The infection rate of Melanopsis praemorsa collected from Al-Bathan fresh water body was 5.7%, while the overall infection rate of snails collected from all fresh water bodies was 4.3%. Details are presented on the morphology and behavior of the cercariae as well as their development within the snail. Conclusions These results have been recorded for the first time and these cercariae may be of medical and veterinary importance. PMID:23569759

Bdir, Sami; Adwan, Ghaleb



Obtaining Ilyanassa snail embryos.  


The marine gastropod Ilyanassa obsoleta is a long-standing and very useful model for studies of embryonic development. It is an especially important model for spiralian development, and for studies of asymmetric cell division. The embryos are amenable to classic embryological manipulation techniques as well as a growing number of molecular approaches. Ilyanassa is also an important model for studies of metamorphosis, the ecology of parasitism, the effects of environmental contaminants on morphology and sexual function, and comparative neurobiology. Ilyanassa adults are readily obtainable and easy to keep in the laboratory. Although the normal spawning season for Ilyanassa is during early summer, they can produce high-quality embryos nearly year-round in the laboratory. Snails collected in the late fall, winter, or spring can be induced to deposit zygotes before the natural spawning season by warming them to room temperature, and snails collected before the natural spawning season can be made to postpone zygote deposition until needed (up to at least 6 mo) by maintaining them in tanks in a cold room at 4 degrees C-8 degrees C. This protocol describes how to induce embryo production in Ilyanassa snails, collect the embryos, and rear them to the stage required for study. PMID:20147126

Gharbiah, Maey; Cooley, James; Leise, Esther M; Nakamoto, Ayaki; Rabinowitz, Jeremy S; Lambert, J David; Nagy, Lisa M



Polarimetric thermal emission from periodic water surfaces  

NASA Technical Reports Server (NTRS)

Experimental results and theoretical calculations are presented to study the polarimetric emission from water surfaces with directional features. For our ground-based Ku-band radiometer measurements, a water pool was constructed on the roof of a building in the Jet Propulsion Laboratory, and a fiberglass surface with periodic corrugations in one direction was impressed on the top of the water surface to create a stationary water surface underneath it. It is observed that the measured Stokes parameters of corrugated fiberglass-covered water surfaces are functions of azimuth angles and agree very well with the theoretical calculations. The theory, after being verified by the experimental data, was then used to calculate the Stokes parameters of periodic surfaces without fiberglass surface layer and with rms height of the order of wind-generated water ripples. The magnitudes of the azimuthal variation of the calculated emissivities at horizontal and vertical polarizations corresponding to the first two Stokes parameters are found to be comparable to the values measured by airborne radiometers and SSM/I. In addition, the third Stokes parameter not shown in the literature is seen to have approximately twice the magnitude of the azimuth variation of either T(sub h) or T(sub v), which may make it more sensitive to the row direction, while less susceptive to noises because the atmospheric and system noises tend to be unpolarized and are expected to be cancelled out when the third Stokes parameter is derived as the difference of two or three power measurements, as indicated by another experiment carried out at a swimming pool with complicated surroundings. The results indicate that passive polarimetry is a potential technology in the remote sensing of ocean wind vector which is a crucial component in the understanding of global climate change. Issues related to the application of microwave passive polarimetry to ocean wind are also discussed.

Yueh, S. H.; Nghiem, S. V.; Kwok, R.; Wilson, W. J.; Li, F. K.; Johnson, J. T.; Kong, J. A.



Copper uptake and depuration by juvenile and adult Florida apple snails (Pomacea paludosa).  


The present study characterized copper (Cu) uptake and depuration by juvenile and adult Florida apple snails (Pomacea paludosa) from water, soil, and diet. During a 28-day uptake period, juvenile apple snails were exposed to aqueous Cu and adult apple snails were exposed to Cu-contaminated soil, water, and food. In the follow-up 14-day depuration period, both juvenile and adult apple snails were held in laboratory freshwater with background Cu concentrations<4 microg/l. For juvenile apple snails, whole body Cu concentrations increased with time and reached a plateau after 14 days. The data followed Michaelis-Menten kinetics rather than a one compartment first order kinetics model. The mean Cu bioconcentration factor (BCF) for juvenile apple snails was 1493 and the depuration half-life was 10.5-13.8 days. For adult snails, dietary uptake of Cu resulted in higher bioaccumulation factors (BAFs) compared to uptake from soil. Most of the accumulated Cu was located in soft tissue (about 60% in the viscera and 40% in the foot). The shell contained <1% of the total accumulated copper. Soft tissue is usually consumed by predators of the apple snail. Therefore, the results of the present study show that Cu transfer through the food chain to the apple snail may lead to potential risk to its predators. PMID:18642077

Hoang, Tham C; Rogevich, Emily C; Rand, Gary M; Frakes, Robert A



Histological and pharmacological investigations of the two symmetrically situated giant neurons, RPeNLN and LPeNLN, identified on the anterior surface of the pedal ganglia of an African giant snail (Achatina fulica Férussac).  


Morphological and pharmacological investigations were made of two giant neurons, RPeNLN (right pedal nerve large neuron) and LPeNLN (left pedal nerve large neuron), situated symmetrically on the anterior surface of the pedal ganglia of an African giant snail (Achatina fulica Férussac). The two neurons (about 250-300 microns in diameter) were the largest ones identified in the ganglia of the snail species. The axonal pathways of the two neurons were symmetrical; of their four main axonal branches, the three main branches innervated the ipsilateral pedal nerves, whereas the last main branch projected to the contralateral pedal nerves. The pharmacological features of the two neurons were very similar. Both were inhibited markedly by dopamine [minimum effective concentrations (MECs): 3 X 10(-6)-10(-5) M], DL-octopamine (MECs: 2 X 10(-6)-2 X 10(-5) M), 5-hydroxytryptamine (MEC: 3 X 10(-6) M), GABA (MEC: 3 X 10(-4) M), L-homocysteic acid (MECs: 3 X 10(-5)-10(-4) M) and erythro-beta-hydroxy-L-glutamic acid (MEC: 3 X 10(-5) M). Acetylcholine showed varied effects, either excitatory or inhibitory, on the two neurons examined. No substances were found to have any marked excitatory effects on the neurons. PMID:2877796

Yongsiri, A; Goto, T; Ku, B S; Takeuchi, H; Namba, M



Lanthanide concentrations in freshwater plants and molluscs, related to those in surface water, pore water and sediment. A case study in The Netherlands.  


Industrial emissions of lanthanides to aquatic ecosystems increase, but knowledge of the environmental fate of these metals is limited. Here we focus attention upon the distribution of lanthanides in freshwater ecosystems, describing lanthanide partitioning between sediment, water and biota. Since lanthanides are often used as oxidation-state analogues for actinides, their distribution can reflect long-term behaviour of the radioactive transuranics. Concentrations of all 14 naturally occurring lanthanides were measured by ICP-MS in Sago pondweed (Potamogeton pectinatus), common duckweed (Lemna minor), seven different mollusc species (tissue and shell), two sediment fractions (< 2 mm and < 63 microm), surface water and sediment pore water from five locations in The Netherlands. In all samples, the typical 'saw-tooth' lanthanide pattern was observed, which implies that lanthanides are transported as a coherent group through aquatic ecosystems. Typical deviations from this pattern were found for Ce and Eu and could be explained by their redox chemistry. The variation in concentrations in abiotic fractions was limited, i.e. within one order of magnitude. However, variations of up to three orders of magnitude were observed in biotic samples, suggesting different affinities among organisms for lanthanides as a group, with significant differences only among molluscs and pondweed samples in relation to sampling location. For P. pectinatus it was shown that pore water was the most important lanthanide source, and for snails, food (plants) seems to be the dominant lanthanide source. Lanthanides were not equally distributed between mollusc shell and tissue and the ratio of lanthanide concentrations in shell and tissue were dependent on the sampling location. Shells contained much lower concentrations and were relatively enriched in Eu, and to a lesser extent in Ce. Bioconcentration factors for lanthanides in plants and snails relative to surface water were typically between 10000 and 100000 l x kg(-1) dry matter, while sediment-water partition coefficients were between 100000 and 3000000 l x kg(-1) dry matter. There was a low extent of biomagnification in the plant-to-snail system, with a maximum biomagnification factor of 5.5. Many distribution coefficients displayed a slight decrease with atomic number. This can be attributed to the general increase in ligand stability constants with atomic number, keeping the heavier lanthanides preferentially in solution. PMID:11887873

Weltje, Lennart; Heidenreich, Heike; Zhu, Wangzhao; Wolterbeek, Hubert Th; Korhammer, Siegfried; de Goeij, Jeroen J M; Markert, Bernd



Camouflaged or tanned: plasticity in freshwater snail pigmentation  

PubMed Central

By having phenotypically plastic traits, many organisms optimize their fitness in response to fluctuating threats. Freshwater snails with translucent shells, e.g. snails from the Radix genus, differ considerably in their mantle pigmentation patterns, with snails from the same water body ranging from being completely dark pigmented to having only a few dark patterns. These pigmentation differences have previously been suggested to be genetically fixed, but we propose that this polymorphism is owing to phenotypic plasticity in response to a fluctuating environment. Hence, we here aimed to assess whether common stressors, including ultraviolet radiation (UVR) and predation, induce a plastic response in mantle pigmentation patterns of Radix balthica. We show, in contrast to previous studies, that snails are plastic in their expression of mantle pigmentation in response to changes in UVR and predator threats, i.e. differences among populations are not genetically fixed. When exposed to cues from visually hunting fish, R. balthica increased the proportion of their dark pigmentation, suggesting a crypsis strategy. Snails increased their pigmentation even further in response to UVR, but this also led to a reduction in pattern complexity. Furthermore, when exposed to UVR and fish simultaneously, snails responded in the same way as in the UVR treatment, suggesting a trade-off between photoprotection and crypsis. PMID:24046875

Ahlgren, Johan; Yang, Xi; Hansson, Lars-Anders; Bronmark, Christer



Camouflaged or tanned: plasticity in freshwater snail pigmentation.  


By having phenotypically plastic traits, many organisms optimize their fitness in response to fluctuating threats. Freshwater snails with translucent shells, e.g. snails from the Radix genus, differ considerably in their mantle pigmentation patterns, with snails from the same water body ranging from being completely dark pigmented to having only a few dark patterns. These pigmentation differences have previously been suggested to be genetically fixed, but we propose that this polymorphism is owing to phenotypic plasticity in response to a fluctuating environment. Hence, we here aimed to assess whether common stressors, including ultraviolet radiation (UVR) and predation, induce a plastic response in mantle pigmentation patterns of Radix balthica. We show, in contrast to previous studies, that snails are plastic in their expression of mantle pigmentation in response to changes in UVR and predator threats, i.e. differences among populations are not genetically fixed. When exposed to cues from visually hunting fish, R. balthica increased the proportion of their dark pigmentation, suggesting a crypsis strategy. Snails increased their pigmentation even further in response to UVR, but this also led to a reduction in pattern complexity. Furthermore, when exposed to UVR and fish simultaneously, snails responded in the same way as in the UVR treatment, suggesting a trade-off between photoprotection and crypsis. PMID:24046875

Ahlgren, Johan; Yang, Xi; Hansson, Lars-Anders; Brönmark, Christer



Water dynamics near solutes and surfaces  

NASA Astrophysics Data System (ADS)

The hydrogen bonding structure and dynamics of water are fundamentally important in a wide range of chemical, biological, geological, and industrial systems. Infrared spectroscopy of the OD stretch of dilute HOD in H2 O provides a sensitive probe of the hydrogen bonding network of water. Water forms a nominally tetrahedral hydrogen bonding network as a liquid but rapid hydrogen bond switching events lead to fast water reorientation. A mechanism for water reorientation that involves large amplitude angular jumps has recently been proposed to describe the long time orientational dynamics. At short times, water molecules quickly sample a restricted range of angular space within an intact hydrogen bonding configuration. The amplitude of this inertial reorientation depends on the strength of the local hydrogen bonding network. When hydrogen bonds are stronger, the water is restricted to a smaller angular range about the hydrogen bond axis. Weaker hydrogen bonds allow larger angular excursions. A simple model for the angular hydrogen bond potential energy surface is presented based on the experimental data. Water is rarely found as a pure liquid in real systems. Often it is in contact with a surface and its dynamics are modified near the surface. Reverse micelles formed using the surfactant Aerosol-OT (AOT), water, and isooctane, as well as AOT lamellar structures provide well-defined, tunable model systems to study the dynamics of water interacting with an interface. Reverse micelles are spherical water pools with radii that can be varied from less than one nanometer up to tens of nanometers. Lamellar structures are surfactant bilayers separated by thin sheets of water ranging in thickness from approximately one nanometer up to four nanometers. In large reverse micelles and lamellar structures, the confined water can be separated into two components, a core of bulk-like water and a shell of interfacial water. Polarization selective pump-probe spectroscopy of the OD stretch of dilute HOD in H2O confined in the reverse micelles provides a probe of the dynamics of the confined water. The characteristic vibrational lifetime and orientational correlation time of interfacial water are determined from a detailed investigation of the frequency dependence of the vibrational population relaxation and orientational anisotropy. The properties of interfacial water are independent of size and geometry for large reverse micelles and lamellar structures, indicating that it is the presence of an interface, not the geometry of the system or a specific confining length scale that affects the dynamics of interfacial water. As the reverse micelle size is decreased, the number of water molecules becomes small enough that the collective nature of water reorientation begins to cause the water away from the interface to be affected by the presence of the interface. One of the most fundamental water-solute interactions is the transport of ions by water. This process is governed by the exchange of water molecules in the solvation shell of the ion. Solvation shell exchange is studied using pump-probe and 2D-IR Chemical Exchange Spectroscopy of a mixture of water and sodium tetrafluoroborate (NaBF4). The timescale for solvation shell exchange is extracted by simultaneously fitting the chemical exchange data, the vibrational population relaxation and the orientational anisotropy data to a kinetic model. Anion solvation shell exchange occurs on a timescale of approximately seven picoseconds, allowing rapid ion transport in solution.

Moilanen, David Emil


Anthropogenic impacts on continental surface water fluxes  

NASA Astrophysics Data System (ADS)

Impacts of reservoirs and irrigation water withdrawals on continental surface water fluxes are studied within the framework of the Variable Infiltration Capacity (VIC) model for a part of North America, and for Asia. A reservoir model, designed for continental-scale simulations, is developed and implemented in the VIC model. The model successfully simulates irrigation water requirements, and captures the main effects of reservoir operations and irrigation water withdrawals on surface water fluxes, although consumptive irrigation water use is somewhat underestimated. For the North American region, simulated irrigation water requirements and consumptive irrigation water uses are 191 and 98 km3year-1, while the corresponding numbers for the Asian region are 810 and 509 km3year-1, respectively. The consumptive uses represent a decrease in river discharge of 4.2 percent for the North American region, and 2.8 percent for the Asian region. The largest monthly decrease is about 30 percent, for the area draining the Western USA in June. The maximum monthly increase in streamflow (28 percent) is in March for the Asian Arctic region.

Haddeland, Ingjerd; Skaugen, Thomas; Lettenmaier, Dennis P.



Proceedings of surface mining for water quality  

SciTech Connect

This conference presents papers on surface coal mining and methods to predict and prevent water quality degradation. Papers include discussion on how acid mine drainage (AMD) forms, how AMD can be predicted in overburden, and how to treat AMD after it forms. The conference also gives an outline of the proposed West Virginia Surface Mining Act. Individual papers have been abstracted for the Energy Data Base.

Not Available



Distribution of freshwater snails in the man-made Oyan Reservoir, Ogun State, Nigeria  

Microsoft Academic Search

The factors influencing patterns of snail distribution in Oyan Reservoir, a typically medium sized man-made reservoir in southwest Nigeria, were investigated once a month, for 28 months (August 1990-November 1992). During each monthly visit, seven stations were sampled for relative snail density, vegetation cover and physical and chemical properties of the lake water. Statistical analyses were performed to determine the

Ifeanyi Emmanuel Ofoezie



Additions to the Pulmonate Snails of Oklahoma (With Notes on Anatomical Techniques)  

Microsoft Academic Search

bottom. Using a common large pulmonate snail, a few trial experiments in dissection will soon permit one to devise a satisfactory method. If material is abundant, identifications should be based on the dissection of many specimens. Living snails to be dissected may be drowned or fixed for several minutes in boiling water, both methods being good for reo vealing particular



Pollution of surface water in Europe  

PubMed Central

This paper discusses pollution of surface water in 18 European countries. For each an account is given of its physical character, population, industries, and present condition of water supplies; the legal, administrative, and technical means of controlling pollution are then described, and an outline is given of current research on the difficulties peculiar to each country. A general discussion of various aspects common to the European problem of water pollution follows; standards of quality are suggested; some difficulties likely to arise in the near future are indicated, and international collaboration, primarily by the exchange of information, is recommended to check or forestall these trends. PMID:13374532

Key, A.



Evaporation over fresh and saline water surfaces  

NASA Astrophysics Data System (ADS)

Evaporation over large water bodies has a crucial role in the global hydrological cycle. Evaporation occurs whenever there is a vapor pressure deficit between a water surface and the atmosphere, and the available energy is sufficient. Salinity affects the density and latent heat of vaporization of the water body, which reflects on the evaporation rate. Different models have been developed to estimate the evaporation process over water surfaces using earth observation data. Most of these models are concerned with the atmospheric parameters. However these models do not take into account the influence of salinity on the evaporation rate; they do not consider the difference in the energy needed for vaporization. For this purpose an energy balance model is required. Several energy balance models that calculate daily evapotranspiration exist, such as the surface energy balance system (SEBS). They estimate the heat fluxes by integration of satellite data and hydro-meteorological field data. SEBS has the advantage that it can be applied over a large scale because it incorporates the physical state of the surface and the aerodynamic resistances in the daily evapotranspiration estimation. Nevertheless this model has not used over water surfaces. The goal of this research is to adapt SEBS to estimate the daily evaporation over fresh and saline water bodies. In particular, 1) water heat flux and roughness of momentum and heat transfer estimation need to be updated, 2) upscaling to daily evaporation needs to be investigated and finally 3) integration of the salinity factor to estimate the evaporation over saline water needs to be performed. Eddy covariance measurements over the Ijsselmeer Lake (The Netherlands) were used to estimate the roughness of momentum and heat transfer at respectively 0.0002 and 0.0001 m. Application of these values over Tana Lake (freshwater), in Ethiopia showed latent heat to be in a good agreement with the measurements, with RMSE of 35.5 Wm-2and rRMSE of 4.7 %. Afterwards the validity of salinity adapted model was tested over different study areas using ECMWF data. It was found that for the original SEBS model and salinity-adapted model over Great Salt Lake, the RMSE were 0.62 and 0.24 mm respectively and the rRMSE 19% and 24%. The evaporation reduction of the Great Salt Lake and the oceans are 27% and 1 %, respectively. In conclusion, SEBS model is adapted to calculate the daily evaporation over fresh water and salt water by integration the salinity factor in the model.

Abdelrady, Ahmed; Timmermans, Joris; Vekerdy, Zoltan



Natural Processes of Ground-Water and Surface-Water Interaction  

NSDL National Science Digital Library

This site explains the hydrologic cycle and interactions of ground water with surface water, streams, lakes, and wetlands. There are sections about chemical interactions of ground water and surface water; evolution of water chemistry in drainage basins; and interaction of ground water and surface water in different landscapes. Mountainous, riverine, coastal, glacial and dune, and karst terrain are examined.

Winter, Thomas; Harvey, Judson; Franke, O. L.; Alley, William



Ajuba LIM proteins are Snail/Slug corepressors required for neural crest development in Xenopus  

PubMed Central

Snail family transcriptional repressors regulate epithelial mesenchymal transitions during physiological and pathological processes. A conserved SNAG repression domain present in all vertebrate Snail proteins is necessary for repressor complex assembly. Here, we identify the Ajuba family of LIM proteins as functional corepressors of the Snail family via an interaction with the SNAG domain. Ajuba LIM proteins interact with Snail in the nucleus on endogenous E-cadherin promoters and contribute to Snail-dependent repression of E-cadherin. Using Xenopus neural crest as a model of in vivo Snail- or Slug-induced EMT, we demonstrate that Ajuba LIM proteins contribute to neural crest development as Snail/Slug corepressors and are required for in vivo Snail/Slug function. Because Ajuba LIM proteins are also components of adherens junction and contribute to their assembly or stability, their functional interaction with Snail proteins in the nucleus suggests that Ajuba LIM proteins are important regulators of epithelia dynamics communicating surface events with nuclear responses. PMID:18331720

Langer, Ellen M.; Feng, Yunfeng; Zhaoyuan, Hou; Rauscher, Frank J.; Kroll, Kristen L.; Longmore, Gregory D.




EPA Science Inventory

The foulant from pilot nanofiltration membrane elements fed conventionally-treated surface water for 15 months was analyzed for organic, inorganic, and biological parameters. The foulant responsible for flux loss was shown to be a film layer 20 to 80 um thick with the greatest de...


Groundwater and Surface Water: Understanding the Interaction  

NSDL National Science Digital Library

This site provides an introduction to groundwater-surface water interactions and how groundwater can be affected by land use. The page describes threats to groundwater, common contaminants, sources of contamination, and groundwater management approaches and tools. A short glossary and a groundwater quiz are also included.

Phillips, Nancy; Center, Conservation T.


Occurrence of Klebisiella pneumoniae in Surface Waters  

PubMed Central

The occurrence of Klebsiella pneumoniae in surface waters was not found to be ubiquitous. When it was isolated, Escherichia coli could also be found. The fecal coliform to fecal streptococci ratio suggest that its origin could be human animal, or mixed sources. PMID:1096815

Knittel, M. D.



Surface Water and Ocean Topography (SWOT) mission  

NASA Astrophysics Data System (ADS)

The Surface Water Ocean Topography (SWOT) mission was recommended in 2007 by the National Research Council's Decadal Survey, "Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond", for implementation by NASA. The SWOT mission is a partnership between two communities, the physical oceanography and the hydrology, to share high vertical accuracy and high spatial resolution topography data produced by the science payload, principally a Ka-band radar Interferometer (KaRIn). The SWOT payload also includes a precision orbit determination system consisting of GPS and DORIS receivers, a Laser Retro-reflector Assembly (LRA), a Jason-class nadir radar altimeter, and a JASON-class radiometer for tropospheric path delay corrections. The SWOT mission will provide large-scale data sets of ocean sea-surface height resolving scales of 15km and larger, allowing the characterization of ocean mesoscale and submesoscale circulation. The SWOT mission will also provide measurements of water storage changes in terrestrial surface water bodies and estimates of discharge in large (wider than 100m) rivers globally. The SWOT measurements will provide a key complement to other NASA spaceborne global measurements of the water cycle measurements by directly measuring the surface water (lakes, reservoirs, rivers, and wetlands) component of the water cycle. The SWOT mission is an international partnership between NASA and the Centre National d'Etudes Spatiales (CNES). The Canadian Space Agency (CSA) is also expected to contribute to the mission. SWOT is currently nearing entry to Formulation (Phase A). Its launch is targeted for October 2020.

Neeck, Steven P.; Lindstrom, Eric J.; Vaze, Parag V.; Fu, Lee-Lueng



Supercooling ability is surprisingly invariable in eggs of the land snail Cantareus aspersus.  


From an ontogenetic point of view, invertebrate eggs are generally the most freezing intolerant stage of a species. Development state, water content and acclimation may affect their supercooling ability. In this study, we measured fresh mass, water content and temperature of crystallisation (T(c)) of eggs of the edible land snail Cantareus aspersus, depending on its form ("aspersa"vs. "maxima"), incubation temperature (20, 12 and 7 degrees C) and physiological age (as part of the complete development). We also tested their tolerance to freezing. Despite a high number of individual observations (n=759) and significant differences of fresh mass and water content between both subspecies, no effect of origin, incubation temperature or development state has been found in this study. T(c) remained constant whatever the condition, with an overall mean of -5.40+/-0.24 degrees C (mean+/-SD). We suggest that fresh mass is important, a high water content and a constantly wet surface confer to land snail eggs a poor ability to supercool. Moreover, the presence of ice nucleating agents at the egg surface (microorganisms present in the soil, calcium carbonate crystals of the egg shell) might induce freezing. Thus, considering the present results, to delay hatching by cryopreservation of eggs does not seem possible. PMID:17189625

Ansart, Armelle; Madec, Luc; Vernon, Philippe



Silver speciation in wastewater effluent, surface waters, and pore waters  

SciTech Connect

Silver, inorganic sulfide, and thiol compounds were measured in municipal wastewater effluent, receiving waters, and pore waters from an anoxic lake sediment in order to predict silver speciation in these systems. The authors found submicromolar concentrations of inorganic sulfide even in fully oxic surface water. This inorganic sulfide is likely to exist in the form of colloidal metal sulfides, which have been shown to be stable under oxidizing conditions for periods of several hours. Inorganic sulfide in both the wastewater effluent and receiving waters was found to be 200 to 300 times in excess of silver concentrations, whereas inorganic sulfide in pore waters was 1,000 to 15,000 times in excess of silver concentrations. With sulfide in excess of silver, the authors predict silver sulfide complexes to dominate silver speciation. Thiols were present at low nanomolar levels in pore waters but were not detectable in wastewater effluent or receiving waters. Thiols do not appear to be important to silver speciation in these freshwater systems. Partitioning of silver into particular, colloidal, and dissolved size fractions showed that a significant proportion of silver is in the colloidal and dissolved phases. Dissolved phase concentrations were relatively constant in the treatment plant effluent and receiving waters, suggesting that silver in the <10-kDa size fraction is strongly complexed by ligands that are not significantly affected by aggregation or sorption processes.

Adams, N.W.H.; Kramer, J.R.



Mutagens in surface waters: a review.  


A review of the literature on the mutagenicity/genotoxicity of surface waters is presented in this article. Subheadings of this article include a description of sample concentration methods, mutagenic/genotoxic bioassay data, and suspected or identified mutagens in surface waters published in the literature since 1990. Much of the published surface water mutagenicity/genotoxicity studies employed the Salmonella/mutagenicity test with strains TA98 and/or TA100 with and/or without metabolic activation. Among all data analyzed, the percentage of positive samples toward TA98 was approximately 15%, both in the absence and the presence of S9 mix. Those positive toward TA100 were 7%, both with and without S9 mix. The percentage classified as highly mutagenic (2500-5000 revertants per liter) or extremely mutagenic (more than 5000 revertants per liter) was approximately 3-5% both towards TA98 and TA100, regardless of the absence or the presence of S9 mix. This analysis demonstrates that some rivers in the world, especially in Europe, Asia and South America, are contaminated with potent direct-acting and indirect-acting frameshift-type and base substitution-type mutagens. These rivers are reported to be contaminated by either partially treated or untreated discharges from chemical industries, petrochemical industries, oil refineries, oil spills, rolling steel mills, untreated domestic sludges and pesticides runoff. Aquatic organisms such as teleosts and bivalves have also been used as sentinels to monitor contamination of surface water with genotoxic chemicals. DNA modifications were analyzed for this purpose. Many studies indicate that the 32P-postlabeling assay, the single cell gel electrophoresis (comet) assay and the micronucleus test are sensitive enough to monitor genotoxic responses of indigenous aquatic organisms to environmental pollution. In order to efficiently assess the presence of mutagens in the water, in addition to the chemical analysis, mutagenicity/genotoxicity assays should be included as additional parameters in water quality monitoring programs. This is because according to this review they proved to be sensitive and reliable tools in the detection of mutagenic activity in aquatic environment. Many attempts to identify the chemicals responsible for the mutagenicity/genotoxicity of surface waters have been reported. Among these reports, researchers identified heavy metals, PAHs, heterocyclic amines, pesticides and so on. By combining the blue cotton hanging method as an adsorbent and the O-acetyltransferase-overproducing strain as a sensitive strain for aminoarenes, Japanese researchers identified two new type of potent frameshift-type mutagens, formed unintentionally, in several surface waters. One group has a 2-phenylbenzotriazole (PBTA) structure, and seven analogues, PBTA-type mutagens, were identified in surface waters collected at sites below textile dyeing factories and municipal wastewater treatment plants treating domestic wastes and effluents. The other one has a polychlorinated biphenyl (PCB) skelton with nitro and amino substitution group and it was revealed to be 4-amino-3,3'-dichloro-5,4'-dinitrobiphenyl derived from chemical plants treating polymers and dye intermediates. However, the identification of major putative mutagenic/genotoxic compounds in most surface waters with high mutagenic/genotoxic activity in the world have not been performed. Further efforts on chemical isolation and identification by bioassay-directed chemical analysis should be performed. PMID:15572284

Ohe, Takeshi; Watanabe, Tetsushi; Wakabayashi, Keiji



Theoretical characterization of water-surfaces interactions  

NASA Astrophysics Data System (ADS)

Much effort is being devoted to the understanding of water-substrate interactions at metallic or semiconducting surfaces with catalytic properties. Confined water represents a great interest for physicists and chemists interested in state-of-the-art technologies such as, fuel cells where the rates of proton have to be controlled, nano-sensors, heterogeneous catalysis, or nano-fluids. Creation of hydrogen gas from water dissociation, also remains an important challenge in order to complete the cycle of CO2 free green energies production. Photocatalytic processes, with semiconducting substrates such as GaN 101&barbelow;0 seem to represent strong candidates towards this achievement. This work focuses on the investigation of water-substrate interactions. It is mainly directed from first-principle calculations with molecular dynamics simulations. The nature of the hydrogen bond is broadly discussed and comparisons between water-water and water-substrate are proposed. Interesting features of spontaneous metal polarization are also put in evidence and electrochemical mechanisms are explained.

Poissier, Adrien


Source Water Assessment for the Las Vegas Valley Surface Waters  

NASA Astrophysics Data System (ADS)

The 1996 amendment to the Safe Drinking Water Act of 1974 created the Source Water Assessment Program (SWAP) with an objective to evaluate potential sources of contamination to drinking water intakes. The development of a Source Water Assessment Plan for Las Vegas Valley surface water runoff into Lake Mead is important since it will guide future work on source water protection of the main source of water. The first step was the identification of the watershed boundary and source water protection area. Two protection zones were delineated. Zone A extends 500 ft around water bodies, and Zone B extends 3000 ft from the boundaries of Zone A. These Zones extend upstream to the limits of dry weather flows in the storm channels within the Las Vegas Valley. After the protection areas were identified, the potential sources of contamination in the protection area were inventoried. Field work was conducted to identify possible sources of contamination. A GIS coverage obtained from local data sources was used to identify the septic tank locations. Finally, the National Pollutant Discharge Elimination System (NPDES) Permits were obtained from the State of Nevada, and included in the inventory. After the inventory was completed, a level of risk was assigned to each potential contaminating activity (PCA). The contaminants of concern were grouped into five categories: volatile organic compounds (VOCs), synthetic organic compounds (SOCs), inorganic compounds (IOCs), microbiological, and radionuclides. The vulnerability of the water intake to each of the PCAs was assigned based on these five categories, and also on three other factors: the physical barrier effectiveness, the risk potential, and the time of travel. The vulnerability analysis shows that the PCAs with the highest vulnerability rating include septic systems, golf courses/parks, storm channels, gas stations, auto repair shops, construction, and the wastewater treatment plant discharges. Based on the current water quality data (prior to treatment), the proximity of Las Vegas Wash to the intake, and the results of the vulnerability analysis of potential contaminating activities, it is determined that the drinking water intake is at a Moderate level of risk for VOC, SOC, and microbiological contaminants. The drinking water intake is at a High level of risk for IOC contaminants. Vulnerability to radiological contamination is Moderate. Source water protection in the Las Vegas Valley is strongly encouraged because of the documented influence of the Las Vegas Wash on the quality of the water at the intake.

Albuquerque, S. P.; Piechota, T. C.



Water quality analysis of surface water: a Web approach.  


The chemical, physical and biological characteristics of water with respect to its suitability describe its quality. Concentration of pesticides or fertilisers degrades the water quality and affects marine life. A comprehensive environmental data information system helps to perform and complete common tasks in less time with less effort for data verification, data calculations, graph generation, and proper monitoring, which helps in the further mitigation step. In this paper, focus is given to a web-based system developed to express the quality of water in the imprecise environment of monitoring data. Water samples were analyzed for eight different surface water parameters, in which four parameters such as pH, dissolved oxygen, biochemical oxygen demand, and fecal coliform were used for the water quality index calculation following MPCB Water Quality Standards of class A-II for best designated use. The analysis showed that river points in a particular year were in very bad category with certainty level of 0-38% which is unsuitable for drinking purposes; samples in bad category had certainty level that ranged from 38 to 50%; samples in medium to good category had certainty levels from 50 to 100%, and the remaining samples were in good to excellent category, suitable for drinking purposes, with certainty levels from 63 to 100%. PMID:23238782

Prasad, Poonam; Chaurasia, Meenal; Sohony, R A; Gupta, Indrani; Kumar, R



Field Techniques for Estimating Water Fluxes Between Surface Water and Ground Water  

USGS Publications Warehouse

This report focuses on measuring the flow of water across the interface between surface water and ground water, rather than the hydrogeological or geochemical processes that occur at or near this interface. The methods, however, that use hydrogeological and geochemical evidence to quantify water fluxes are described herein. This material is presented as a guide for those who have to examine the interaction of surface water and ground water. The intent here is that both the overview of the many available methods and the in-depth presentation of specific methods will enable the reader to choose those study approaches that will best meet the requirements of the environments and processes they are investigating, as well as to recognize the merits of using more than one approach. This report is designed to make the reader aware of the breadth of approaches available for the study of the exchange between surface and ground water. To accomplish this, the report is divided into four chapters. Chapter 1 describes many well-documented approaches for defining the flow between surface and ground waters. Subsequent chapters provide an in-depth presentation of particular methods. Chapter 2 focuses on three of the most commonly used methods to either calculate or directly measure flow of water between surface-water bodies and the ground-water domain: (1) measurement of water levels in well networks in combination with measurement of water level in nearby surface water to determine water-level gradients and flow; (2) use of portable piezometers (wells) or hydraulic potentiomanometers to measure hydraulic gradients; and (3) use of seepage meters to measure flow directly. Chapter 3 focuses on describing the techniques involved in conducting water-tracer tests using fluorescent dyes, a method commonly used in the hydrogeologic investigation and characterization of karst aquifers, and in the study of water fluxes in karst terranes. Chapter 4 focuses on heat as a tracer in hydrological investigations of the near-surface environment.

Rosenberry, Donald O.; LaBaugh, James W.



The effects of spatial habitat structure on the evolution of density-dependent growth and reproduction in freshwater snails  

Microsoft Academic Search

We examined the growth and reproductive rates of freshwater snails, Physa acuta, in two habitat types. In the Asabata habitat, snails lived in isolated water pools, which occasionally joined to form a single large pool; in the Kakegawa habitat, they lived in a slow-running water way. Genetic structure assessments using three microsatellite loci supports the idea that a stable panmictic

Masakado Kawata; Hiroshi Sawada; Jun Yokoyama; Lázaro M. Echenique-Díaz; Yasuyuki Ishibashi



Wave effect on microwave scattering at water surface  

Microsoft Academic Search

Microwave scattering at the water surface where a water surface wave coexisted with wind-waves was measured in an experimental water tank. Scattering characteristics, scattering coefficients and Doppler spectra of backscattering microwaves and the relation between scattering characteristics and physical properties of a water surface wave such as wave length, wave height, wave phase and orbital velocity have been investigated. The

C.-K. Rheem



Predator-induced life-history shifts in a freshwater snail.  


The snail Physella virgata virgata, a widely distributed freshwater pulmonate, was observed to change its life-history characteristics in the presence of the crayfish Orconectes virilis in spring-fed Oklahoma streams. These changes were apparently initiated by a water-borne cue released when crayfish fed on conspecific snails. In the presence of the cue, snails exhibited rapid growth rates and little reproduction until they reached a size of about 10 mm after 8 months. In the absence of the cue, snails typically grew to about 4 mm (3.5 months) and then began reproduction. The chemically inducible shift indicates that the life histories of these snails are phenotypically plastic. By increasing the variance associated with size and age of maturity, prey may increase the likelihood of coexisting with seasonal predators. PMID:17776452

Crowl, T A; Covich, A P



Proterometra macrostoma (Trematoda: Azygiidae): location of the redia and emergence path from the snail, Elimia semicarinata (Gastropoda: Pleuroceridae).  


The objectives of this study were to describe (1) the osmotic environment and precise location of the Proterometra macrostoma redia in its snail intermediate host, (2) where retraction of the distome body into the cercarial tail occurs, and (3) the subsequent emergence path of the cercaria out of the snail. Snails, Elimia semicarinata , were collected from North Elkhorn Creek in Scott County, Kentucky and screened daily for patent infections. Live rediae were extracted from infected snails in either artificial pond water (APW) or artificial snail water (ASW) and monitored for changes in morphology and movement every hour over 5 hr at 22 C. Infected and control snails were simultaneously fixed and decalcified in Cal-Ex II, prepared for routine paraffin sectioning, and serial sections subsequently analyzed for rediae and cercariae location. Significantly (?(2) = 42.45; 1 df; P = 0.0001) more rediae showed movement in ASW than in APW after 5 hr, suggesting a host compartment separate from the mantle cavity. Histological sections clearly showed rediae developing in close association with the snail digestive tract, within the peri-intestinal sinus of the snail, and isolated from the mantle cavity by a mantle membrane. Retraction of the distome body into the cercarial tail follows the emergence of the cercaria from the redia. Cercariae then enter the mantle cavity and emerge into fresh water through a siphon-like structure formed by the mantle collar of the snail. PMID:23343411

Rosen, Ronald; Berg, Ericka; Dolan, Julianna; King, Bailey; Martin, Michon; Mehmeti, Franceska



Purification and characterization of an antibacterial factor from snail mucus.  


The antibacterial factor from the body surface of the African giant snail, Achatina fulica Férussac, was isolated by DEAE-Toyopearl 650M ion exchange chromatography. The isolated preparation exhibited highly positive antibacterial activity both for the Gram-positive bacteria, Bacillus subtilis and Staphylococcus aureus and for the Gram-negative bacteria, Escherichia coli and Pseudomonas aeruginosa, but it lost such activity when heated at 75 degrees C for 5 min. The antibacterial factor of the snail mucus was a glycoprotein whose molecular weight (MW) was about 160,000. It was composed of two subunits of MW 70,000-80,000. PMID:2866907

Kubota, Y; Watanabe, Y; Otsuka, H; Tamiya, T; Tsuchiya, T; Matsumoto, J J



Interference with Fasciola hepatica snail finding by various aquatic organisms.  


Previous studies using radioactive miracidia have shown that a number of non-host snails and bivalves, interposed as 'decoys' in linear test channels, may interfere with the capacity of Fasciola hepatica miracidia to infect Lymnaea truncatula. Applying similar experimental principles, the role of several other potential interferents have been analysed in the present study. Daphnia pulex (Cladocera) and larvae of Corethra sp. (Diptera) exercised significant interfering effects by protecting 'target' snails from infection. Evidence suggested that this effect was a result of their normal predatory behaviour. Other organisms including Herpobdella testacea and Helobdella stagnalis (Hirudinea), Acellus aquaticus (Isopoda), Planaria lugubris (Turbellaria) and L. truncatula egg clusters failed to interfere with miracidial host-finding. Nor did P. lugubris and L. truncatula 'conditioned water' interfere with the capacity of the miracidia to infect their host snail. PMID:876683

Christensen, N O; Nansen, P; Frandsen, F



Chemical composition of Texas surface waters, 1949  

USGS Publications Warehouse

This report is the fifth the a series of publications by the Texas Board of Water Engineers giving chemical analyses of the surface waters in the State of Texas. The samples for which data are given were collected between October 1, 1948 and September 30, 1949. During the water year 25 daily sampling stations were maintained by the Geological Survey. Sampled were collected less frequently during the year at many other points. Quality of water records for previous years can be found in the following reports: "Chemical Composition of Texas Surface Waters, 1938-1945," by W. W. Hastings, and J. H. Rowley; "Chemical Composition of Texas Surface Waters, 1946," by W. W. Hastings and B. Irelan; "Chemical Composition of Texas Surface Waters, 1947," by B. Irelan and J. R. Avrett; "Chemical Composition of Texas Surface Waters, 1948," by B. Irelan, D. E. Weaver, and J. R. Avrett. These reports may be obtained from the Texas Board of Water Engineers and Geological Survey at Austin, Texas. Samples for chemical analysis were collected daily at or near points on streams where gaging stations are maintained for measurement of discharge. Most of the analyses were made of 10-day composites of daily samples collected for a year at each sampling point. Three composite samples were usually prepared each month by mixing together equal quantities of daily samples collected for the 1st to the 10th, from the 11th to the 20th, and during the remainder of the month. Monthly composites were made at a few stations where variation in daily conductance was small. For some streams that are subject to sudden large changes in chemical composition, composite samples were made for shorter periods on the basis of the concentration of dissolved solids as indicated by measurement of specific conductance of the daily samples. The mean discharge for the composite period is reported in second-feet. Specific conductance values are expressed as "micromhos, K x 10 at 25° C." Silica, calcium, magnesium, sodium, potassium, bicarbonate, sulfate, chloride, and nitrate are reported in parts per million. The quantity of dissolved solids is given in tons per acre-foot, tons per day (if discharge records are available), and parts per million. The total and non-carbonate hardness are reported as parts per million calcium carbonate (CaCO3). For those analyses where sodium and potassium are reported separately, "recent sodium" will include the equivalent quantity of sodium only. In analyses where sodium and potassium were calculated and reported as a combined value, the "percent sodium" will include the equivalent quantity of sodium and potassium. Weighted average analyses are given for most daily sampling stations. The weighted average analysis represent approximately the composition of water that would be found in a reservoir containing all the water passing a given station during the year after through mixing in the reservoir. Samples were analyzed according to method regularly used by the Geological Survey. These methods are essentially the same or are modifications of methods described in recognized authoritative publications for mineral analysis of water samples. These quality of water records have been collected as part of the cooperative investigations of the water resources of Texas conducted by the Geological Survey and the Texas Board of Water Engineers. Much of the work would have been impossible without the support of the following Federal State, and local agencies The United States Bureau of Reclamation, U. S. Corps of Engineers, Brazos River Conservation and Reclamation District, Lower Colorado River Authority, Red Bluff Water Power Control District, City of Amarillo, City of Abilene, and City of Forth Worth. The investigations were under the firection of Burdge Irelan, District Chemist, Austin, Texas. Analyses of water samples were made by Clara J. Carter, Lee J. Freeman, Homer D. Smith, Dorothy M. Suttle, DeForrest E. Weaver, and Clarence T. Welborn. Calculations of weighted averages were made by James R. Avrett, Burdge Irelan, Dorothy M. Suttle, and DeFor

Irelan, Burdge




Microsoft Academic Search

Summary Notaspid snails are known for their defensive skin secretion of sulfuric acid (pH 1-2) in response to noxious stimuli. We observed acid secretion and behavior in five notaspid species, and studied them in detail in Pleurobranchaea californica. All species secreted acid in response to skin abrasion or compression. Moreover, all species showed stereotypic avoidance behavior to acidified sea water




Relaxations and Interfacial Water Ordering at the Corundum (110) Surface  

SciTech Connect

In situ high resolution specular X-ray reflectivity measurements were used to examine relaxations and interfacial water ordering occurring at the corundum (110)-water interface. Sample preparation affected the resulting surface structure. Annealing in air at 1373 K produced a reconstructed surface formed through an apparently ordered aluminum vacancy. The effect of the reconstruction on in-plane periodicity was not determined. The remaining aluminum sites on the surface maintain full coordination by oxygen and the surface was coated with a layer of physically adsorbed water. Ordering of water further from the surface was not observed. Acid etching of this surface and preparing a surface through annealing at 723 K both produced an unreconstructed surface with identical relaxations and water ordering. Relaxations were confined primarily to the top {approx}4 {angstrom} of the surface and were dominated by an increased distribution width of the fully occupied surface aluminum site and outward relaxation of the oxygen surface functional groups. A layer of adsorbed water fully coated the surface and occurred in two distinct sites. Water above this showed signs of layering and indicated that water ordering extended 7-10 {angstrom} from the surface. Relaxations and the arrangement of interfacial water were nearly identical on both the unreconstructed corundum and isostructural hematite (110) surfaces. Comparison to corundum and hematite (012) suggests that the arrangement of interfacial water is primarily controlled by mineral surface structure.

Catalano, Jeffrey G. (WU)



Habitat preference of freshwater snails in relation to environmental factors and the presence of the competitor snail Melanoides tuberculatus (Müller, 1774).  


Our objective is to evaluate the habitat preference of freshwater snails in relation to environmental factors and the presence of the competitor snail Melanoides tuberculatus. In the first phase, snails was collected at 12 sites. This sampling sites presented a degree of organic input. In the second phase 33 sampling sites were chosen, covering a variety of lotic and lentic environments. The snail species found at Guapimirim, state of Rio de Janeiro, displayed a marked habitat preference, specially in relation to the physical characteristics of each environment. Other limiting factors for snail distribution at the studied lotic environments were the water current velocity and the amount of organic matter, mainly to Physa marmorata, M. tuberculatus, and Biomphalaria tenagophila. The absence of interactions between M. tuberculatus and another snails could be associated to the distinct spatial distribution of those species and the instability of habitats. This later factor may favor the coexistence of M. tuberculatus with B. glabrata by reduction of population density. In areas of schistosomiasis transmission some habitat modification may add to the instability of the environment, which would make room for the coexistence of M. tuberculatus and Biomphalaria spp. In this way, some of the usual measures for the control of snail hosts would prevent the extinction of populations of Biomphalaria spp. by M. tuberculatus in particular habitats. PMID:16021304

Giovanelli, Alexandre; da Silva, Cesar Luiz Pinto Ayres Coelho; Leal, Geórgia Borges Eccard; Baptista, Darcílio Fernandes



Charge Fluctuations on Membrane Surfaces in Water  

E-print Network

We generalize the predictions for attractions between over-all neutral surfaces induced by charge fluctuations/correlations to non-uniform systems that include dielectric discontinuities, as is the case for mixed charged lipid membranes in an aqueous solution. We show that the induced interactions depend in a non-trivial way on the dielectric constants of membrane and water and show different scaling with distance depending on these properties. The generality of the calculations also allows us to predict under which dielectric conditions the interaction will change sign and become repulsive.

Rebecca Menes; Philip Pincus; Bean Stein



On detecting surface and sub-surface bodies in water by virtue of their surface and water column wakes  

Microsoft Academic Search

This paper presents theoretical and experimental results of detection and parameterization of moving bodies and scuba divers based on their surface and water column signatures under Hudson River estuary conditions. (1) Theoretical and experimental (SIT DL Towing Tank) estimates of wake characteristics for bodies of interest are carried out. (2) The IR-images of ship wakes at the surface of the

A. Benilov; B. Bunin; G. Dardiere; A. Sutin; D. Zeng; R. Martini



The effect of aquatic plant abundance on shell crushing resistance in a freshwater snail.  


Most of the shell material in snails is composed of calcium carbonate but the organic shell matrix determines the properties of calcium carbonate crystals. It has been shown that the deposition of calcium carbonate is affected by the ingestion of organic compounds. We hypothesize that organic compounds not synthesized by the snails are important for shell strength and must be obtained from the diet. We tested this idea indirectly by evaluating whether the abundance of the organic matter that snails eat is related to the strength of their shells. We measured shell crushing resistance in the snail Mexipyrgus churinceanus and the abundance of the most common aquatic macrophyte, the water lily Nymphaea ampla, in ten bodies of water in the valley of Cuatro Ciénegas, Mexico. We used stable isotopes to test the assumption that these snails feed on water lily organic matter. We also measured other factors that can affect crushing resistance, such as the density of crushing predators, snail density, water pH, and the concentration of calcium and phosphorus in the water. The isotope analysis suggested that snails assimilate water lily organic matter that is metabolized by sediment bacteria. The variable that best explained the variation in crushing resistance found among sites was the local abundance of water lilies. We propose that the local amount of water lily organic matter provides organic compounds important in shell biomineralization, thus determining crushing resistance. Hence, we propose that a third trophic level could be important in the coevolution of snail defensive traits and predatory structures. PMID:22970206

Chaves-Campos, Johel; Coghill, Lyndon M; García de León, Francisco J; Johnson, Steven G



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

NASA Technical Reports Server (NTRS)

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

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



Emission of dimers from a free surface of heated water  

NASA Astrophysics Data System (ADS)

The emission rate of water dimers from a free surface and a wetted solid surface in various cases was calculated by a simplified Monte Carlo method with the use of the binding energy of water molecules. The binding energy of water molecules obtained numerically assuming equilibrium between the free surface of water and vapor in the temperature range of 298-438 K corresponds to the coordination number for liquid water equal to 4.956 and is close to the reference value. The calculation results show that as the water temperature increases, the free surface of water and the wetted solid surface become sources of free water dimers. At a temperature of 438 K, the proportion of dimers in the total flow of water molecules on its surface reaches 1%. It is found that in the film boiling mode, the emission rate of dimers decreases with decreasing saturation vapor. Two mechanisms of the emission are described.

Bochkarev, A. A.; Polyakova, V. I.



Moving Water Droplets on Aluminum and Copper Surfaces Using Surface Tension Gradients  

NASA Astrophysics Data System (ADS)

The behavior of water droplets on metal surfaces is very important for many applications, especially in heat exchangers in air conditioning and refrigeration. We use photolithography and/or shadow masks to create alternating hydrophobic/hydrophilic Cu micro-channels on an aluminum surface and to move water droplets on the surface. The contact angle that is formed between water droplets and the surface is clearly asymmetrical due to the different surface properties at the contact line between the droplets and the patterned surface. An HDFT self-assembled mono-layer allows for a large change in the water droplet contact angle on the copper, but seems to have no effect on the aluminum surface. We will show our results on the effect of the surface patterning and surface roughness on water droplet behavior. We also demonstrate that the engineered surface gradients cause water droplets to travel more than 1'' on a horizontal or upward tilted surface.

Alheshibri, Muidh; Rogers, Nathaniel; Sommers, Andrew; Eid, Khalid



Metolachlor and atrazine fate in surface water systems  

SciTech Connect

The detection of pesticides in surface water and ground water provokes concern involving human health risks associated with pesticide exposure. Monitoring studies of surface waters have detected concentrations of herbicides that exceed the U.S. Environmental Protection Agency proposed maximum contamination level (MCL) for drinking water. Conventional water treatment processes do not remove many herbicides. Tap water drawn from surface-water sources has been reported to contain levels of herbicides above the regulatory limits. There is current interest in the use of artificial wetlands and macrophyte-cultured ponds in waste-water-treatment systems. Aquatic plant-based water treatment systems improve waste water effluent by solid filtration and nutrient assimilation. Various aquatic plants have been shown to accumulate metals, absorb inorganic ions, and accelerate the biodegradation of complex organics. Our research evaluates the fate of metolachlor and atrazine in surface water, surface water/sediment, and surface water/aquatic plant incubation systems to study the influence of sediment and aquatic plants in the removal and biotransformation of herbicides from contaminated waters. Aquatic macrophyte systems may prove to be useful in the remediation of herbicide contaminated surface waters in water treatment facilities or in the reduction of herbicide concentrations from tile drain effluents prior to entering watersheds.

Rice, P.J.; Anderson, T.A.; Coats, J.R. [Iowa State Univ., Ames, IA (United States)



Northern range expansion and coastal occurrences of the New Zealand mud snail (Potamopyrgus antipodarum Gray, 1843) in the northeast Pacific  

Microsoft Academic Search

The New Zealand mud snail Potamopyrgus antipodarum (Gray, 1843) is a common invasive species in fresh and brackish water ecosystems in Europe, Australia, Japan, and North America. In some invaded habitats, P. antipodarum can reach high densities (over 500,000 snails m -2 ) and dominate the biomass of the benthos, leading to detrimental impacts to native biota and changes in

Timothy Davidson; Thaddeus K. Graczyk; Valance E. F. Brenneis; Catherine de Rivera; Robyn Draheim; Graham E. Gillespie



Structure and function of mitochondria in hepatopancreas cells from metabolically depressed snails.  


Mitochondria in cells isolated from the hepatopancreas of aestivating land snails (Helix aspersa) consume oxygen at 30% of the active control rate. The aim of this study was to investigate whether the lower respiration rate is caused by a decrease in the density of mitochondria or by intrinsic changes in the mitochondria. Mitochondria occupied 2% of cellular volume, and the mitochondrial inner membrane surface density was 17 microm(-1), in cells from active snails. These values were not different in cells from aestivating snails. The mitochondrial protein and mitochondrial phospholipid contents of cells were also similar. There was little difference in the phospholipid fatty acyl composition of mitochondria isolated from metabolically depressed or active snails, except for arachidonic acid, which was 18% higher in mitochondria from aestivating snails. However, the activities of citrate synthase and cytochrome c oxidase in mitochondria isolated from aestivating snails were 68% and 63% of control, respectively. Thus the lower mitochondrial respiration rate in hepatopancreas cells from aestivating snails was not caused by differences in mitochondrial volume or surface density but was associated with intrinsic changes in the mitochondria. PMID:12024289

Bishop, T; Ocloo, A; Brand, M D



The Surface Water and Ocean Topography Mission: Observing Terrestrial Surface Water and Oceanic Submesoscale Eddies  

Microsoft Academic Search

The elevation of the ocean surface has been measured for over two decades from spaceborne altimeters. However, existing altimeter measurements are not adequate to characterize the dynamic variations of most inland water bodies, nor of ocean eddies at scales of less than about 100 km, notwithstanding that such eddies play a key role in ocean circulation and climate change. For

Michael Durand; Lee-Lueng Fu; Dennis P. Lettenmaier; Douglas E. Alsdorf; Ernesto Rodriguez; Daniel Esteban-Fernandez



Miracidia of an Egyptian strain of Schistosoma mansoni differentiate between sympatric snail species.  


The host-finding behavior of miracidia of 2 strains of Schistosoma mansoni from Egypt and Brazil was studied by recording their responses to snail-conditioned water (SCW) from the Egyptian sympatric snails, Biomphalaria alexandrina, Physa acuta, Lymnaea cailliudi, and Balinus truncatus, as well as from Biomphalaria arabica and Biomphalaria glabrata. Miracidia of the Egyptian strain significantly preferred SCW from their compatible hosts B. alexandrina and B. arabica and showed no or a weak response to SCW from the other sympatric species, whereas miracidia of the Brazilian strain did not differentiate between SCW from different snail species. PMID:14740921

Hassan, A H M; Haberl, B; Hertel, J; Haas, W



Distribution and abundance of schistosomiasis and fascioliasis host snails along the Mara River in Kenya and Tanzania.  


We purposively selected 39 sampling sites along the Mara River and its two perennial tributaries of Amala and Nyangores and sampled snails. In addition, water physicochemical parameters (temperature, turbidity, dissolved oxygen, conductivity, alkalinity, salinity and pH) were taken to establish their influence on the snail abundance and habitat preference. Out of the 39 sites sampled, 10 (25.6%) had snails. The snail species encountered included Biomphalaria pfeifferi Krauss - the intermediate host of Schistosoma mansoni Sambon, Bulinus africanus - the intermediate host of Schistosoma haematobium, and Lymnaea natalensis Krauss - the intermediate host of both Fasciola gigantica and F. hepatica Cobbold. Ceratophallus spp., a non-vector snail was also encountered. Most (61.0%) of the snails were encountered in streamside pools. Schistosomiasis-transmitting host snails, B. pfeifferi and B. africanus, were fewer than fascioliasis-transmitting Lymnaea species. All the four different snail species were found to be attached to different aquatic weeds, with B. pfeifferi accounting for over half (61.1%) of the snails attached to the sedge, followed by B. africanus and Lymnaea spp., accounting for 22.2 and 16.7%, respectively. Ceratophallus spp. were non-existent in sedge. The results from this preliminary study show that snails intermediate hosts of schistosomiasis and fascioliasis exists in different habitats, in few areas along the Mara River, though their densities are still low to have any noticeable impacts on disease transmission in case they are infected. The mere presence of the vector snails in these focal regions calls for their immediate control and institution of proper regulations, management, and education among the locals that can help curtail the spread of the snails and also schistosomiasis and fascioliasis within the Mara River basin. PMID:25405008

Dida, Gabriel O; Gelder, Frank B; Anyona, Douglas N; Matano, Ally-Said; Abuom, Paul O; Adoka, Samson O; Ouma, Collins; Kanangire, Canisius K; Owuor, Phillip O; Ofulla, Ayub V O



Distribution and abundance of schistosomiasis and fascioliasis host snails along the Mara River in Kenya and Tanzania  

PubMed Central

We purposively selected 39 sampling sites along the Mara River and its two perennial tributaries of Amala and Nyangores and sampled snails. In addition, water physicochemical parameters (temperature, turbidity, dissolved oxygen, conductivity, alkalinity, salinity and pH) were taken to establish their influence on the snail abundance and habitat preference. Out of the 39 sites sampled, 10 (25.6%) had snails. The snail species encountered included Biomphalaria pfeifferi Krauss – the intermediate host of Schistosoma mansoni Sambon, Bulinus africanus – the intermediate host of Schistosoma haematobium, and Lymnaea natalensis Krauss – the intermediate host of both Fasciola gigantica and F. hepatica Cobbold. Ceratophallus spp., a non-vector snail was also encountered. Most (61.0%) of the snails were encountered in streamside pools. Schistosomiasis-transmitting host snails, B. pfeifferi and B. africanus, were fewer than fascioliasis-transmitting Lymnaea species. All the four different snail species were found to be attached to different aquatic weeds, with B. pfeifferi accounting for over half (61.1%) of the snails attached to the sedge, followed by B. africanus and Lymnaea spp., accounting for 22.2 and 16.7%, respectively. Ceratophallus spp. were non-existent in sedge. The results from this preliminary study show that snails intermediate hosts of schistosomiasis and fascioliasis exists in different habitats, in few areas along the Mara River, though their densities are still low to have any noticeable impacts on disease transmission in case they are infected. The mere presence of the vector snails in these focal regions calls for their immediate control and institution of proper regulations, management, and education among the locals that can help curtail the spread of the snails and also schistosomiasis and fascioliasis within the Mara River basin.

Dida, Gabriel O.; Gelder, Frank B.; Anyona, Douglas N.; Matano, Ally-Said; Abuom, Paul O.; Adoka, Samson O.; Ouma, Collins; Kanangire, Canisius K.; Owuor, Phillip O.; Ofulla, Ayub V. O.



Strain-related variation in the persistence of influenza A virus in three types of water: distilled water, filtered surface water, and intact surface water  

PubMed Central

Background The persistence of influenza A (IA) virus in aquatic habitats has been demonstrated to be a determinant for virus transmission dynamics in wild duck populations. In this study, we investigated virus strain-related variation in persistence in water for nine wild duck isolated IA viruses of three subtypes (H3N8, H4N6, and H8N4). Results We experimentally estimated the loss of infectivity over time in three different types of water: distilled, filtered surface water, and intact surface water. All viruses persisted longest in distilled water followed by filtered surface water with markedly reduced durations of persistence observed in the intact surface water. Strain-related variations were observed in distilled and filtered surface water but limited variation was observed in the intact surface water. Conclusions Our findings suggest that the role of surface water for long-term (between years) maintenance of AI viruses in the environment may be limited, and suggest that the physico-chemical characteristics of water, as well as microorganisms, may be of strong importance. Results also indicate that the extent of strain-related variation observed in distilled water may overestimate persistence abilities for IA viruses in the wild and supports the need to develop experiments that account for these effects to assess subtype, genotype, as well as spatial and temporal variation in the persistence of IA viruses in aquatic habitats. PMID:23289857



Surface Films: Areas of Water Bodies That Are Often Overlooked  

NSDL National Science Digital Library

This peer-reviewed article from BioScience is researching surface water. Material accumulates at the water-air interface of all natural water bodies to form a surface film. The interface is a dynamic environment, so surface films are altered by water movements, solar radiation, and biological processes. These films consist of a complex of organic matter and microorganisms, some of which are harmful. Researchers have often overlooked surface films when studying water bodies, and their importance is only now being recognized.




Instructions for measuring the rate of evaporation from water surfaces  

USGS Publications Warehouse

The ·rate of evaporation from water surfaces varies with the temperature of the water, the velocity of the wind at the water surface, and the dryness of the air. Consequently, the rate of evaporation from rivers, lakes, canals, or reservoirs varies widely in different localities and for the same locality in different seasons.

U.S. Geological Survey



Surface Science in the Richmond Lab: Vapor/Water Studies  

E-print Network

, and reactions of gaseous pollutants. These interactions are affected by organics at the water surface, as well interfacial water structure but have little affect on SO2(g) adsorption. Currently, we are investigating HClSurface Science in the Richmond Lab: Vapor/Water Studies Many of the Earth's important atmospheric

Richmond, Geraldine L.


Image-based Water Surface Reconstruction with Refractive Stereo  

E-print Network

Image-based Water Surface Reconstruction with Refractive Stereo by Nigel Jed Wesley Morris A thesis-based Water Surface Reconstruction with Refractive Stereo Nigel Jed Wesley Morris Master of Science Graduate surfaces using an indirect refractive stereo reconstruction method. Our work builds on previous work

Jepson, Allan D.


Male characteristics on female mud snails caused by antifouling bottom paints.  


This study continues an investigation of an anatomical abnormality, named 'imposex', which consists of a superimposition of male characteristics on to a functionally normal female reproductive anatomy of the dioecious snail Nassarius obsoletus Say. Imposex is prevalent in natural populations living near yacht basins and rarely found distant from them. In the current study caged snails were transferred between a yacht basin and a distant 'clean' locality where the natural population of snails was normal. Imposex was induced in some normal snails kept at the marina and suppressed, but not lost in abnormal snails kept at the clean locality. A similar positive result was obtained in the laboratory by exposing normal snails to organotin-containing antifouling paints and abnormal snails to clean sea water. Results were negative in parallel tests of various marina-associated materials which did not contain organotin. The laboratory studies have thus identified a causative factor for the anatomical abnormalities common near yacht basins in the natural environment. They also provide a rare, if not unique, example of a chemical agent which causes the appearance of superfluous anatomical features in an animal. PMID:7185870

Smith, B S



Acute combined exposure to heavy metals (Zn, Cd) blocks memory formation in a freshwater snail.  


The effect of heavy metals on species survival is well documented; however, sublethal effects on behaviour and physiology are receiving growing attention. Measurements of changes in activity and respiration are more sensitive to pollutants, and therefore a better early indicator of potentially harmful ecological impacts. We assessed the effect of acute exposure (48 h) to two heavy metals at concentrations below those allowable in municipal drinking water (Zn: 1,100 ?g/l; Cd: 3 ?g/l) on locomotion and respiration using the freshwater snail, Lymnaea stagnalis. In addition we used a novel assessment method, testing the ability of the snail to form memory in the presence of heavy metals in both intact snails, and also snails that had the osphradial nerve severed which connects a chemosensory organ, the osphradium, to the central nervous system. Aerial respiration and locomotion remained unchanged by acute exposure to heavy metals. There was also no effect on memory formation of these metals when administered alone. However, when snails were exposed to these metals in combination memory formation was blocked. Severing the osphradial nerve prevented the memory blocking effect of Zn and Cd, indicating that the snails are sensing these metals in their environment via the osphradium and responding to them as a stressor. Therefore, assessing the ability of this species to form memory is a more sensitive measure of heavy metal pollution than measures of activity, and indicates that the snails' ability to demonstrate behavioural plasticity may be compromised by the presence of these pollutants. PMID:22218978

Byzitter, Jovita; Lukowiak, Ken; Karnik, Vikram; Dalesman, Sarah



Epidemiology of cercarial stage of trematodes in freshwater snails from Chiang Mai province, Thailand  

PubMed Central

Objective To investigate the epidemiological situation of cercarial trematodes infection in freshwater snails from different water resources in Chiang Mai province, Thailand. Methods The snail specimens were collected from 13 districts of Chiang Mai province during April 2008 to February 2012. The prevalence of cercarial infection in snails was investigated using the crushing method. The drawing was done with the help of a camera lucida for the morphological study. Results A total of 2?479 snail individuals were collected and classified into 7 families, 11 genera, and 14 species, Among them, 8 snails species were found to be infected with an overall prevalence of 17.27% (428/2?479), which infected with nine groups of cercariae; gymnocephalous cercaria, strigea cercaria, megalurous cercaria, monostome cercaria, parapleurolophocercous cercaria (Haplorchis cercaria), pleurolophocercous cercaria, furcocercous cercaria (Transversotrema cercaria), xiphidiocercaria, and virgulate cercaria. The parapleurolophocercous cercaria was found to be the dominant type among the cercarial infection in the snails (64.25%). Conclusions The various species of snails found in the research location act as the intermediate hosts for the high prevalence of parasitic infection of many species of mammals. This work will provide new information on both the distribution and first intermediate host of trematodes. PMID:23620846

Chontananarth, Thapana; Wongsawad, Chalobol



Bioaccumulation of aluminium in the freshwater snail Lymnaea stagnalis at neutral pH  

Microsoft Academic Search

This study examined the accumulation of aluminium (Al) by the freshwater snail Lymnaea stagnalis at neutral pH, when most Al would be predicted to be in an insoluble form (Al(OH)3). Snails were exposed to a range of Al concentrations (38–285 ?g l?1) for 30 days, followed by 20 days in clean water. Aluminium was measured using atomic absorption spectroscopy.Significant accumulation

R. Elangovan; K. N. White; C. R. McCrohan



Analysis of snail genes in the crustacean Parhyale hawaiensis: insight into snail gene family evolution.  


The transcriptional repressor snail was first discovered in Drosophila melanogaster, where it initially plays a role in gastrulation and mesoderm formation, and later plays a role in neurogenesis. Among arthropods, this role of snail appears to be conserved in the insects Tribolium and Anopheles gambiae, but not in the chelicerates Cupiennius salei and Achaearanea tepidariorum, the myriapod Glomeris marginata, or the Branchiopod crustacean Daphnia magna. These data imply that within arthropoda, snail acquired its role in gastrulation and mesoderm formation in the insect lineage. However, crustaceans are a diverse group with several major taxa, making analysis of more crustaceans necessary to potentially understand the ancestral role of snail in Pancrustacea (crustaceans + insects) and thus in the ancestor of insects as well. To address these questions, we examined the snail family in the Malacostracan crustacean Parhyale hawaiensis. We found three snail homologs, Ph-snail1, Ph-snail2 and Ph-snail3, and one scratch homolog, Ph-scratch. Parhyale snail genes are expressed after gastrulation, during germband formation and elongation. Ph-snail1, Ph-snail2, and Ph-snail3 are expressed in distinct patterns in the neuroectoderm. Ph-snail1 is the only Parhyale snail gene expressed in the mesoderm, where its expression cycles in the mesodermal stem cells, called mesoteloblasts. The mesoteloblasts go through a series of cycles, where each cycle is composed of a migration phase and a division phase. Ph-snail1 is expressed during the migration phase, but not during the division phase. We found that as each mesoteloblast division produces one segment's worth of mesoderm, Ph-snail1 expression is linked to both the cell cycle and the segmental production of mesoderm. PMID:22466422

Hannibal, Roberta L; Price, Alivia L; Parchem, Ronald J; Patel, Nipam H



A longitudinal study of schistosome vector snail populations in Liberia.  


Seasonal changes in populations of Biomphalaria pfeifferi and Bulinus globosus were observed at 62 locations in Liberia, West Africa. All varieties of water in both urban and rural locations were sampled. A wet season decrease and dry season increase of B. globosus populations in both urban and rural locations, similar to that reported elsewhere in West Africa, was observed. Similar fluctuations of B. pfeifferi populations were noted. The prevalence of schistosome infected vector snails varied markedly between rural and urban locations. At rural sites parasite prevalence followed the appropriate vector snail prevalence. At urban sites a portion of the vector snail population appeared relatively unaffected by seasonal changes. This stable population harbors a reservoir of infected snails that sustain year round transmission. Human infection was sampled in school children in the study area and prevalence of approximately 50% was found for both Schistosoma mansoni and S. haematobium. Added to the malacologic information this suggests less than hyperendemic transmission. The data suggest that urban environments should receive priorities for control programs. PMID:572150

Sodeman, W A



Self-inhibition of water dissociation on magnesium oxide surfaces  

Microsoft Academic Search

Hydroxylated MgO surfaces have been prepared by exposure to water vapour of MgO crystals at room temperature. High hydroxyl coverages were achieved on freshly cleaved surfaces. However, upon adsorption–desorption cycles of the hydroxyl adlayer, the ability of the MgO surfaces to dissociate water was seen to be dramatically inhibited. Reduced reactivities have also been observed on both air- and water-exposed

D. Abriou; J. Jupille



Failure of transmission of low-pathogenic avian influenza virus between Mallards and freshwater snails: an experimental evaluation.  


In aquatic bird populations, the ability of avian influenza (AI) viruses to remain infectious in water for extended periods provides a mechanism that allows viral transmission to occur long after shedding birds have left the area. However, this also exposes other aquatic organisms, including freshwater invertebrates, to AI viruses. Previous researchers found that AI viral RNA can be sequestered in snail tissues. Using an experimental approach, we determined whether freshwater snails (Physa acuta and Physa gyrina) can infect waterfowl with AI viruses by serving as a means of transmission between infected and naïve waterfowl via ingestion. In our first experiment, we exposed 20 Physa spp. snails to an AI virus (H3N8) and inoculated embryonated specific pathogen-free (SPF) chicken eggs with the homogenized snail tissues. Sequestered AI viruses remain infectious in snail tissues; 10% of the exposed snail tissues infected SPF eggs. In a second experiment, we exposed snails to water contaminated with feces of AI virus-inoculated Mallards (Anas platyrhynchos) to evaluate whether ingestion of exposed freshwater snails was an alternate route of AI virus transmission to waterfowl. None of the immunologically naïve Mallards developed an infection, indicating that transmission via ingestion likely did not occur. Our results suggest that this particular trophic interaction may not play an important role in the transmission of AI viruses in aquatic habitats. PMID:24502718

Oesterle, Paul T; Huyvaert, Kathryn P; Orahood, Darcy; Mooers, Nicole; Sullivan, Heather; Franklin, Alan B; Root, J Jeffrey



Understanding of processes of surface water dynamics causing storm surge  

E-print Network

Understanding of processes of surface water dynamics causing storm surge and groundwater due to storm surges and SLR? ­ First, can we predict SLR or storm surges in open coastal water bodies? ­ How do we go about transla

Kirby, James T.


Surface cooling by an impinging water drop  

SciTech Connect

Widespread use of spray cooling in industrial applications such as cooling of turbine blades, fire suppression by sprinkler systems, and quenching of metal castings has motivated many experimental and analytical studies of droplets and sprays impinging on a hot surface. The authors studied, using both experiments and a numerical model, the impact of water droplets on a hot stainless steel surface. Initial substrate temperatures were varied from 50 C to 120 C (low enough to prevent boiling in the drop) and impact velocities from 0.5 m/s to 4 m/s. Fluid mechanics and heat transfer during droplet impact were modeled using a Volume-of-Fluid (VOF) code. Numerical calculations of droplet shape and substrate temperature during impact agreed well with experimental results. Both simulations and experiments show that increasing impact velocity enhances heat flux from the substrate by only a small amount. The principal effect of raising droplet velocity is that it makes the droplet spread more during impact, increasing the wetted area across which heat transfer takes place. The authors also developed a simple model of heat transfer into the droplet by one-dimensional conduction across a thin boundary layer which gives estimates of droplet cooling effectiveness that agree well with results from the numerical model. The analytical model predicts that for fixed Reynolds number (RE) cooling effectiveness increases with Weber number (WE). However, for large Weber numbers, when WE {much{underscore}gt} {radical}RE, cooling effectiveness is independent of droplet velocity or size and depends only on the Prandtl number.

Pasandideh-Fard, M.; Aziz, S.D.; Chandra, S.; Mostaghimi, J.



Impervious Areas: Examining the Undermining Effects on Surface Water Quality  

E-print Network

This study explored the relationship between increased proportions of imperviousness in a watershed on surface water quality and examined the effectiveness of using remote sensing to systematically and accurately determine impervious surfaces. A...

Young, De'Etra Jenra



Disinfection of surface and ground waters with polymeric ultrafiltration membranes  

Microsoft Academic Search

The paper is connected with the ultrafiltration of well and surface waters using polymeric membranes made of polyacrylonitrile and polysulfone. The efficiency of the process was determined by measuring water flux, as well as bacteriological and physicochemical analysis of raw water and permeates.It was state, that the best well water flux was obtained for the membrane made of mixture polyacrylonitrile\\/polysulfone

Krystyna Konieczny




E-print Network

. [1] Surface fresh water is essential for life, yet we have surprisingly poor knowledge of the spatial singularly supply the water volume and hydraulic measurements that are needed to accurately model the water societies' basic need for fresh water, perhaps the most important hydrologic observations that can be made

Howat, Ian M.



E-print Network

estimates of water content and the changes in water content over space and time using both groundwaveNEAR SURFACE WATER CONTENT ESTIMATION USING GPR DATA: INVESTIGATIONS WITHIN CALIFORNIA VINEYARDS S ( Detailed estimates of water content are necessary for variety of hydrogeological inves

Rubin, Yoram


Investigating surface waterwell interaction using stable isotope ratios of water*  

E-print Network

reserved. Keywords: Bank filtration; Hydrogen isotope ratio; Oxygen isotope ratio; Drinking water; Age water quality in a drinking water well, an understanding of the amount of surface water and its travel-floodtraveltimesoflessthan1yearforthissite.Agedatingofonegroundwatersampleusing3 H­3 Hemethods estimated an age longer than 1



Microsoft Academic Search

A surface water monitoring system was designed and installed on board the icebreaker SHIRASE. The system consists of sensors unit, navigation information terminal and control unit. Water pumped up from an intake of hull (8 m depth) is led into the sensors unit so as to measure flow rate of water, water temperature, conductivity, dissolved oxygen, fluorescence intensity, size com



Emerging contaminants in surface waters and their relevance for the production of drinking water in Europe  

Microsoft Academic Search

An increasing part of drinking water in Europe is prepared from surface water. At the same time, a growing number of emerging contaminants is being discovered in surface water. This review provides an overview of classes of emerging contaminants nowadays detected in the aquatic environment that are of relevance for drinking water production. These comprise e.g. endocrine disrupting compounds, such

Corine J. Houtman



Hydrological modelling of snail dispersal patterns in Msambweni, Kenya and potential resurgence of Schistosoma haematobium transmission.  


Urinary schistosomiasis is an important source of human morbidity in Msambweni, Kenya, where the intermediate host snail, Bulinus nasutus is found in ponds and water pools. In the past, aquatic habitats in the area have been studied separately; however, recent collections of B. nasutus snails and shells indicated that many of these ponds are in fact connected during and following sufficient rains. Satellite imagery and a geographical information system (GIS) were used to survey the main water courses and potential drainage routes, to locate potential source populations of snails and to determine probable snail dispersal routes. The 2 water bodies implicated as being the most important Schistosoma haematobium transmission foci in the area were found to differ in their degree of connectivity to other B. nasutus source habitats. One pond becomes connected even after normal rains, while the other pond requires prolonged rains or flooding to become connected with source habitats. Consequently, the transmission foci differ in their susceptibility to snail population control measures. Spatially explicit dispersal models that consider the spatial and temporal patterns of connectivity between aquatic habitats will contribute to improved snail surveillance and more focused control for urinary schistosomiasis at a local level. PMID:17156580

Clennon, J A; King, C H; Muchiri, E M; Kitron, U



Combined Visualization of Wind Waves and Water Surface Temperature  

E-print Network

Combined Visualization of Wind Waves and Water Surface Temperature Roland Rocholz1 , Sven Wanner1 comparison of the space-time evolution of the waves and the surface temperature distribution . The temperature images are mapped in false color onto that virtual surface. Shading, based on the surface slope

Jaehne, Bernd


Enhanced surface water treatment by ultrafiltration  

Microsoft Academic Search

For capacity extension of one of the drinking water production plants of Amsterdam Water Supply, four treatment schemes applying ultrafiltration (UF) are considered. The main purposes of the UF process are phosphate removal, removal of suspended solids and colloidal matter, and hygienic water quality improvement. In the pilot plant investigation, water from the Bethunepolder has been treated with UF. The

J. A. M. H. Hofman; M. M. Beumer; E. T. Baars; J. P. van der Hoek; H. M. M. Koppers



Activities affecting surface water resources: A general overview  

SciTech Connect

In November 1987, P.E.I. signed a federal/provincial work-sharing arrangement on water resource management focusing on groundwater pollution, surface water degradation and estuarine eutrophication. The surface water program was designed to identify current surface water uses and users within 12 major watersheds across the Island containing 26 individual rivers, as well as problems arising due to practices that degrade the quality of surface water and restricts its value to other user groups. This report presents a general overview of the program, covering the general characteristics of the Island; operations in agriculture, fish and wildlife, forestry, recreation, fisheries, and industry; alterations of natural features of waterways; wetlands; additional watershed activities such as hydrometric stations and subdivision development; and activities affecting surface water resources such as sedimentation sources, pollution point sources and instream obstructions.

Not Available



An ontology design pattern for surface water features  

USGS Publications Warehouse

Surface water is a primary concept of human experience but concepts are captured in cultures and languages in many different ways. Still, many commonalities exist due to the physical basis of many of the properties and categories. An abstract ontology of surface water features based only on those physical properties of landscape features has the best potential for serving as a foundational domain ontology for other more context-dependent ontologies. The Surface Water ontology design pattern was developed both for domain knowledge distillation and to serve as a conceptual building-block for more complex or specialized surface water ontologies. A fundamental distinction is made in this ontology between landscape features that act as containers (e.g., stream channels, basins) and the bodies of water (e.g., rivers, lakes) that occupy those containers. Concave (container) landforms semantics are specified in a Dry module and the semantics of contained bodies of water in a Wet module. The pattern is implemented in OWL, but Description Logic axioms and a detailed explanation is provided in this paper. The OWL ontology will be an important contribution to Semantic Web vocabulary for annotating surface water feature datasets. Also provided is a discussion of why there is a need to complement the pattern with other ontologies, especially the previously developed Surface Network pattern. Finally, the practical value of the pattern in semantic querying of surface water datasets is illustrated through an annotated geospatial dataset and sample queries using the classes of the Surface Water pattern.

Sinha, Gaurav; Mark, David; Kolas, Dave; Varanka, Dalia; Romero, Boleslo E.; Feng, Chen-Chieh; Usery, E. Lynn; Liebermann, Joshua; Sorokine, Alexandre



Particles in Surface Waters: Coagulation and Transport  

E-print Network

Conventional water quality assessment and simulation of particles in natural waters focus on bulk concentrations of the suspended solid phase. These analyses rely directly or indirectly on a linear, 'average particle' approach to describe processes...

Culkin, Gerald W.; Lawler, Desmond F.


Storage and incubation of Echinostoma revolutum eggs recovered from wild Branta canadensis, and their infectivity to Lymnaea tomentosa snails.  


Echinostoma revolutum eggs recovered from naturally infected wild Canada geese (Branta canadensis) were cold stored (4-6 degrees C) for up to 72 weeks. Successful hatching followed incubation for from 6 to 8 days at an optimum temperature of between 25 and 30 degrees C. A partial life cycle from adult worm to metacercarial encystment in Lymnaea tomentosa snails was completed in the laboratory. Snails were infected both by free miracidia and by ingestment of unhatched embryonated eggs. Infection was equally successful in environmental temperature ranges from 10 to 25 degrees C, and at challenge levels of 2, 5 or 10 embryonated eggs per snail. Exposure to 10 eggs was lethal. Ingestion by snails of embryonated eggs with successful infection at 10 degrees C suggests that embryonated eggs may be used to infect wild snails when the environmental water temperature has reached 10 degrees C. PMID:16336715

Davis, N E



Molecular dynamics studies of interfacial water at the alumina surface.  

SciTech Connect

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 at 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.

Argyris, Dr. Dimitrios [University of Oklahoma; Ho, Thomas [ORNL; Cole, David [Ohio State University



Integrating nonindigenous aquatic plant control with protection of snail kite nests in Florida.  


The endangered snail kite (Rostrhamus sociabilis) feeds primarily on the freshwater apple snail (Pomacea paludosa) in Florida. The nonindigenous, floating water hyacinth (Eichhornia crassipes) and water lettuce (Pistia stratiotes) impede kites from finding snails. Effective control of these aquatic plants in the littoral zone of central and south Florida lakes benefits kites by maintaining open foraging habitat. However, incidental herbicide spraying of nesting substrates result in nest collapse when kites breed in nonwoody, emergent plants [cattail (Typha spp.) and giant bulrush (Scirpus validus)] in the outer littoral zone during lower lake levels. Many endangered species recovery plans and their implementation have experienced problems due to inaction and/or noncooperation by various governmental agencies and their personnel. Herein, we describe the development and implementation of a buffer zone strategy to prevent secondary impacts from an aquatic plant control program to snail kites nesting on lakes in central and south Florida. A strategy was jointly developed by personnel of five state and federal agencies to control herbicide application near kite nesting areas during the normal breeding season. Although requiring various modifications during its implementation, this cooperative effort successfully integrated aquatic plant control objectives with snail kite conservation on Lake Okeechobee during 1988. The program was expanded the following year to lakes Kissimmee and Tohopekaliga. Since the implementation of the snail kite impact preclusion program, no nest loss was attributed to incidental herbicide applications on lakes Okeechobee, Kissimmee, and Tohopekaliga. PMID:11436998

Rodgers, J A; Smith, H T; Thayer, D D



Surface Curvature-Induced Directional Movement of Water Droplets  

E-print Network

Here we report a surface curvature-induced directional movement phenomenon, based on molecular dynamics simulations, that a nanoscale water droplet at the outer surface of a graphene cone always spontaneously moves toward the larger end of the cone, and at the inner surface toward the smaller end. The analysis on the van der Waals interaction potential between a single water molecule and a curved graphene surface reveals that the curvature with its gradient does generate the driving force resulting in the above directional motion. Furthermore, we found that the direction of the above movement is independent of the wettability, namely is regardless of either hydrophobic or hydrophilic of the surface. However, the latter surface is in general leading to higher motion speed than the former. The above results provide a basis for a better understanding of many reported observations, and helping design of curved surfaces with desired directional surface water transportation.

Lv, Cunjing; Yin, Yajun; Zheng, Quanshui



Surface Tension: The Ways of Water.  

ERIC Educational Resources Information Center

Describes activities which help students understand several basic scientific concepts regarding water. Outlines objectives, materials needed, procedures, and questions to ask about student observations. Investigations include working with the self-sealing property of water, talcum powder, paper clips, and making water wetter. (RT)

Donalson-Sams, Marilyn



Arizona has relatively limited water resources due to its arid climate and limited surface water.  

E-print Network

consumption. The life cycle water consumption was estimated for a range of potential low-carbon energy sources the general range of the potential impacts on water use. Life Cycle Water Use per Vehicle Mile 0.01 0.1 1 10Arizona has relatively limited water resources due to its arid climate and limited surface water

Fay, Noah


Investigation of surface water behavior during glaze ice accretion  

NASA Technical Reports Server (NTRS)

A series of experimental investigations that focused on isolating the primary factors that control the behavior of unfrozen surface water during glaze ice accretion were conducted. Detailed microvideo observations were made of glaze ice accretions on 2.54 cm diam cylinders in a closed-loop refrigerated wind tunnel. Distinct zones of surface water behavior were observed; a smooth wet zone in the stagnation region with a uniform water film, a rough zone where surface tension effects caused coalescence of surface water into stationary beads, and a zone where surface water ran back as rivulets. The location of the transition from the smooth to the rough zone was found to migrate towards the stagnation point with time. Comparative tests were conducted to study the effect of the substrate thermal and roughness properties on ice accretion. The importance of surface water behavior was evaluated by the addition of a surface tension reducing agent to the icing tunnel water supply, which significantly altered the accreted glaze ice shape. Measurements were made to determine the contact angle behavior of water droplets on ice. A simple multizone modification to current glaze ice accretion models was proposed to include the observed surface roughness behavior.

Hansman, R. John, Jr.; Turnock, Stephen R.



Mapping the Surface of Sheet Flow Water in the Everglades  

Microsoft Academic Search

University of Florida (UF) researchers used airborne laser swath mapping (ALSM) to map the height of vegetation, relative to the surface of sheet flow water, in the Everglades. In less than three hours of flying, ALSM provided sub-decimeter precision measurements of the height and slope of the water surface over an area greater than 50 square kilometers. The RMS scatter

William Carter; Ramesh Shrestha; Grady Tuell; David Bloomquist; Michael Sartori


Electrical Properties of Mineral Surfaces for Increasing Water Sorption  

E-print Network

Electrical Properties of Mineral Surfaces for Increasing Water Sorption Treavor A. Kendall. The role of water sorption is examined by carrying out experiments for increasing relative humidity (RH as the surface sorption of inorganic and organic components. Cell adhesion and subsequent biofilm formation can



EPA Science Inventory

The monitoring strategy must be sensitive to frequent and unpredictable fluctuations in water quality caused by major storm events and seasonal destratifications of the lake/impoundment. Therefore, daily monitoring of raw source water and the finished water quality entering distr...


Snail modulates cell metabolism in MDCK cells  

SciTech Connect

Highlights: ? MDCK/snail cells were more sensitive to glucose deprivation than MDCK/neo cells. ? MDCK/snail cells had decreased oxidative phosphorylation, O{sub 2} consumption and ATP content. ? TCA cycle enzyme activity, but not expression, was lower in MDCK/snail cells. ? MDCK/snail cells showed reduced PDH activity and increased PDK1 expression. ? MDCK/snail cells showed reduced expression of GLS2 and ACLY. -- Abstract: Snail, a repressor of E-cadherin gene transcription, induces epithelial-to-mesenchymal transition and is involved in tumor progression. Snail also mediates resistance to cell death induced by serum depletion. By contrast, we observed that snail-expressing MDCK (MDCK/snail) cells undergo cell death at a higher rate than control (MDCK/neo) cells in low-glucose medium. Therefore, we investigated whether snail expression influences cell metabolism in MDCK cells. Although gylcolysis was not affected in MDCK/snail cells, they did exhibit reduced pyruvate dehydrogenase (PDH) activity, which controls pyruvate entry into the tricarboxylic acid (TCA) cycle. Indeed, the activity of multiple enzymes involved in the TCA cycle was decreased in MDCK/snail cells, including that of mitochondrial NADP{sup +}-dependent isocitrate dehydrogenase (IDH2), succinate dehydrogenase (SDH), and electron transport Complex II and Complex IV. Consequently, lower ATP content, lower oxygen consumption and increased survival under hypoxic conditions was also observed in MDCK/snail cells compared to MDCK/neo cells. In addition, the expression and promoter activity of pyruvate dehydrogenase kinase 1 (PDK1), which phosphorylates and inhibits the activity of PDH, was increased in MDCK/snail cells, while expression levels of glutaminase 2 (GLS2) and ATP-citrate lyase (ACLY), which are involved in glutaminolysis and fatty acid synthesis, were decreased in MDCK/snail cells. These results suggest that snail modulates cell metabolism by altering the expression and activity of key enzymes. This results in enhanced glucose dependency and leads to cell death under low-glucose conditions. On the other hand, the reduced requirements for oxygen and nutrients from the surrounding environment, might confer the resistance to cell death induced by hypoxia and malnutrition.

Haraguchi, Misako, E-mail: [Department of Biochemistry and Molecular Biology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan)] [Department of Biochemistry and Molecular Biology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan); Indo, Hiroko P. [Department of Maxillofacial Radiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan)] [Department of Maxillofacial Radiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan); Iwasaki, Yasumasa [Health Care Center, Kochi University, Kochi 780-8520 (Japan)] [Health Care Center, Kochi University, Kochi 780-8520 (Japan); Iwashita, Yoichiro [Department of Maxillofacial Radiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan)] [Department of Maxillofacial Radiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan); Fukushige, Tomoko [Department of Dermatology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan)] [Department of Dermatology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan); Majima, Hideyuki J. [Department of Maxillofacial Radiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan)] [Department of Maxillofacial Radiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan); Izumo, Kimiko; Horiuchi, Masahisa [Department of Environmental Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan)] [Department of Environmental Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan); Kanekura, Takuro [Department of Dermatology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan)] [Department of Dermatology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan); Furukawa, Tatsuhiko [Department of Molecular Oncology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan)] [Department of Molecular Oncology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan); Ozawa, Masayuki [Department of Biochemistry and Molecular Biology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan)] [Department of Biochemistry and Molecular Biology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan)



Effect of Glyphosate on the Development of Pseudosuccinea columella Snails  

Microsoft Academic Search

.   Glyphosate (Roundup) is one of the most commonly used broad-spectrum herbicides with little to no hazard to animals, man,\\u000a or the environment. Due to its widespread use, there is continuous contamination of the environment in both soil and water\\u000a with this herbicide. There is a paucity of long-term exposure studies with sublethal concentrations of glyphosate on aquatic\\u000a snails. This

T. M. Tate; J. O. Spurlock; F. A. Christian



Sea-ice and surface water circulation, Alaskan continental shelf  

NASA Technical Reports Server (NTRS)

The author has identified the following significant results. Over 1500 water samples from surface and from standard hydrographic depths were collected during June and July 1973 from Bering Sea and Gulf of Alaska. The measurement of temperature, salinity, and productivity indicated that various distinct water masses cover the Bering Sea Shelf. The suspended load in surface waters will be correlated with the ERTS-1 imagery as it becomes available to delineate the surface water circulation. The movement of ice floes in the Bering Strait and Bering Sea indicated that movement of ice varies considerably and may depend on wind stress as well as ocean currents.

Wright, F. F.; Sharma, G. D.; Burns, J. J. (principal investigators)



Levity Through Tension: Fun with Water's Surface Tension  

NSDL National Science Digital Library

This experiment describes how to create a "dribble bottle" which only leaks water when the cap is unscrewed. The full water bottle has a small hole made with a push pin. The surface tension of water is strong enough to keep the small pin hole sealed. When the bottle is open, air can enter the bottle through the top, and air pressure overcomes the surface tension, pushing water out the small hole. In a related video, Mr. O and his assistants explore surface tension with a variety of similar experiments.

Houston, Children'S M.



Identification and pharmacological characteristics of the two giant neurons, v-RPLN and v-VNAN, on the ventral surface in the suboesophageal ganglia of the African giant snail (Achatina fulica Férussac).  


Two giant neurons, v- RPLN (ventral-right parietal large neuron) and v- VNAN (ventral-visceral noisy autoactive neuron), were identified on the ventral surface in the caudal part of the suboesophageal ganglia of the African giant snail (Achatina fulica F erussac ), and their pharmacological features to the common putative neurotransmitters and their related substances were examined. The giant neuron examined, v- RPLN , is situated in front of the exit of the right anterior pallial nerve in the right parietal ganglion. The neuron, which is 250-300 microns in diameter, one of the largest neurons in the ganglia, was usually silent without spontaneous firing. The neuron was excited by L-norepinephrine (L-NE), DL-octopamine (DL-OA), 5-hydroxytryptamine (5-HT), L-homocysteic acid (L-HCA) and erythro-beta-hydroxy-L-glutamic acid (erythro-L- BHGA ); and inhibited by dopamine (DA), GABA, acetylcholine (Ach) and its related substances. Another giant neuron examined, v- VNAN , is situated very close to the right side of the exit of the right posterior pallial nerve in the visceral ganglion. The neuron is elliptical and about 150 micron in diameter. It showed spontaneous firing highly modified by the synaptic influences. DA, 5-HT, glycine (Gly), GABA and its related substances, L-HCA, erythro-L- BHGA , and Ach and its related substances all had the direct (not via synaptic influences) excitatory effects on the neuromembrane examined. Some of them, for example, L-NE, 5-HT and Ach and its related substances caused transient excitation of the neuron, probably due to the synaptic influences, immediately after their application. No substance producing any inhibition of the neuron could be found in the present study. PMID:6144435

Ku, B S; Takeuchi, H



Herbicide Metabolites in Surface Water and Groundwater: Introduction and Overview  

USGS Publications Warehouse

Several future research topics for herbicide metabolites in surface and ground water are outlined in this chapter. They are herbicide usage, chemical analysis of metabolites, and fate and transport of metabolites in surface and ground water. These three ideas follow the themes in this book, which are the summary of a symposium of the American Chemical Society on herbicide metabolites in surface and ground water. First, geographic information systems allow the spatial distribution of herbicide-use data to be combined with geochemical information on fate and transport of herbicides. Next these two types of information are useful in predicting the kinds of metabolites present and their probable distribution in surface and ground water. Finally, methods development efforts may be focused on these specific target analytes. This chapter discusses these three concepts and provides an introduction to this book on the analysis, chemistry, and fate and transport of herbicide metabolites in surface and ground water.

Thurman, E. M.; Meyer, M. T.



Fungal farming in a snail  

PubMed Central

Mutualisms between fungi and fungus-growing animals are model systems for studying coevolution and complex interactions between species. Fungal growing behavior has enabled cultivating animals to rise to major ecological importance, but evolution of farming symbioses is thought to be restricted to three terrestrial insect lineages. Surveys along 2,000 km of North America's Atlantic coast documented that the marine snail Littoraria irrorata grazes fungus-infected wounds on live marsh grass throughout its range. Field experiments demonstrate a facultative, farming mutualism between Littoraria and intertidal fungi. Snails graze live grass primarily not to feed but to prepare substrate for fungal growth and consume invasive fungi. Fungal removal experiments show that snails and fungi act synergistically to suppress marsh grass production. These results provide a case of fungus farming in the marine environment and outside the class Insecta and reveal a previously undemonstrated ecological mechanism (i.e., facilitation of fungal invasion) by which grazers can exert top-down control of marine plant production. PMID:14657360

Silliman, Brian R.; Newell, Steven Y.



Water Adsorption on Wurtzite GaN Surfaces  

NASA Astrophysics Data System (ADS)

A solid solution of wurtzite GaN/ZnO absorbs light in the visible and can photosplit water.ootnotetextK. Maeda, K. Teramura, D. Lu, T. Takata, N. Saito, Y. Inoue, and K. Domen, Nature 440, 295 (2006) The water is oxidized by the photo-holes at the surface of the semiconductor alloy. However, microscopic details of the oxidation process are unknown. We present a first-principles study of water adsorption on wurtzite GaN. We study the structures and energetics of water adsorption, calculate the energy barrier for water dissociation, analyze the water-water interactions, and study the electronic structure. The results are compared with water adsorption on ZnO surface. We also study the behavior of the holes near the water-semiconductor interface.

Shen, Xiao; Allen, Philip B.; Hybertsen, Mark S.; Muckerman, James T.



Interfacial thermodynamics of confined water near molecularly rough surfaces.  


We study the effects of nanoscopic roughness on the interfacial free energy of water confined between solid surfaces. SPC/E water is simulated in confinement between two infinite planar surfaces that differ in their physical topology: one is smooth and the other one is physically rough on a sub-nanometre length scale. The two thermodynamic ensembles considered, with constant pressure either normal or parallel to the walls, correspond to different experimental conditions. We find that molecular-scale surface roughness significantly increases the solid-liquid interfacial free energy compared to the smooth surface. For our surfaces with a water-wall interaction energy minimum of -1.2 kcal mol(-1), we observe a transition from a hydrophilic surface to a hydrophobic surface at a roughness amplitude of about 3 angstroms and a wavelength of 11.6 angstroms, with the interfacial free energy changing sign from negative to positive. In agreement with previous studies of water near hydrophobic surfaces, we find an increase in the isothermal compressibility of water with increasing surface roughness. Interestingly, average measures of the water density and hydrogen-bond number do not contain distinct signatures of increased hydrophobicity. In contrast, a local analysis indicates transient dewetting of water in the valleys of the rough surface, together with a significant loss of hydrogen bonds, and a change in the dipole orientation toward the surface. These microscopic changes in the density, hydrogen bonding, and water orientation contribute to the large increase in the interfacial free energy, and the change from a hydrophilic to a hydrophobic character of the surface. PMID:21043431

Mittal, Jeetain; Hummer, Gerhard



Interfacial thermodynamics of confined water near molecularly rough surfaces  

PubMed Central

We study the effects of nanoscopic roughness on the interfacial free energy of water confined between solid surfaces. SPC/E water is simulated in confinement between two infinite planar surfaces that differ in their physical topology: one is smooth and the other one is physically rough on a nanometer length scale. The two thermodynamic ensembles considered, with constant pressure either normal or parallel to the walls, correspond to different experimental conditions. We find that molecular-scale surface roughness significantly increases the solid-liquid interfacial free energy compared to the smooth surface. For our surfaces with a water-wall interaction energy minimum of ?1.2 kcal/mol, we observe a transition from a hydrophilic surface to a hydrophobic surface at a roughness amplitude of about 3 Å and a wave length of 11.6 Å, with the interfacial free energy changing sign from negative to positive. In agreement with previous studies of water near hydrophobic surfaces, we find an increase in the isothermal compressibility of water with increasing surface roughness. Interestingly, average measures of the water density and hydrogen-bond number do not contain distinct signatures of increased hydrophobicity. In contrast, a local analysis indicates transient dewetting of water in the valleys of the rough surface, together with a significant loss of hydrogen bonds, and a change in the dipole orientation toward the surface. These microscopic changes in the density, hydrogen bonding, and water orientation contribute to the large increase in the interfacial free energy, and the change from a hydrophilic to a hydrophobic character of the surface. PMID:21043431

Mittal, Jeetain; Hummer, Gerhard



Coagulation of low turbidity surface waters with Moringa oleifera seeds  

Microsoft Academic Search

The use of Moringa oleifera seed extracts both as primary coagulant coagulant aid and its conjunctive use with alum in treating low turbidity waters was studied. The laboratory based studies used the natural polyelectrolyte to treat waters with turbidities between 23 and 90 ntu, obtained from three surface water sources in Kano, Nigeria. On the average, 50% turbidity removal was

Suleyman A. Muyibi; Charles A. Okuofu



Water Order Profiles on Phospholipid/Cholesterol Membrane Bilayer Surfaces  

E-print Network

Water Order Profiles on Phospholipid/Cholesterol Membrane Bilayer Surfaces DAVID ROBINSON,1 2011 in Wiley Online Library ( Abstract: Water is pivotal in the stabilization of macromolecular biological structures, although the dynamic en- semble structure of water near to molecular

O'Shea, Paul


First Principles Studies of Water and Ice on Oxide Surfaces  

E-print Network

the fundamental properties of water adsorption, dissociation, and proton transfer on oxide surfaces. These studies reveal that the water adsorption energy and the tendency to dissociate both increase as one moves down transfer within clusters of just two water molecules, made possible by facile dissociation

Alavi, Ali


Surface Science Letters Structures of adsorbed water layers  

E-print Network

methods) the consecutive ad- sorption of water molecules and found that, as the coverage increasedSurface Science Letters Structures of adsorbed water layers on MgO: an ab initio study R.M. Lynden density-functional method has been carried out for energy minima for a monolayer of water on MgO. Minima

Alavi, Ali


Simulating Continental Surface Waters: An Application to Holocene Northern Africa.  

NASA Astrophysics Data System (ADS)

A model (SWAM) to predict surface waters (lakes and wetlands) on the scale of atmospheric general circulation models is developed. SWAM is based on a linear reservoir hydrologic model and is driven by runoff, precipitation, evaporation, topography, and water transport directions.SWAM is applied to the modern climate using observed estimates of the hydrologic variables and a 5 × 5 digital terrain model to represent topography. It simulates the surface water area of northern Africa (about 1% of the land area) in reasonable agreement with observed estimates (0.65%). A middle Holocene (6000 yr BP) simulation using the results of the GENESIS atmospheric general circulation model (AGCM) illustrates the sensitivity of the simulated surface waters to climatic changes and the model's utility as a diagnostic tool for AGCMs. SWAM and GENESIS capture the general pattern of climate change 6000 yr BP. There is an increase in the simulated surface water area from about 1% to about 3% of the land area, including an increase in the area of Lake Chad by about five times and extensive surface water throughout northern Mali, consistent with observed patterns of surface water change during the Holocene. Limitations in the modeling of surface waters appear to result from the relatively coarse resolution of global elevation data.

Coe, Michael T.



Enhanced ordering of water at hydrophobic surfaces.  


We study the properties of water molecules adjacent to a hydrophobic molecular layer with vibrational sum-frequency generation spectroscopy. We find that the water molecules at D2O/hexane, D2O/heptane, and D2O/polydimethylsiloxane interfaces show an enhanced ordering and stronger hydrogen-bond interactions than the water molecules at a D2O/air interface. With increasing temperature (up to 80 °C) the water structure becomes significantly less ordered and the hydrogen bonds become weaker. PMID:24511972

Strazdaite, Simona; Versluis, Jan; Backus, Ellen H G; Bakker, Huib J



Biogeochemistry of DMS in Surface Waters  

NASA Technical Reports Server (NTRS)

Dimethylsulfide (DMS) is important in influencing the formation of aerosols in the troposphere over large areas of the world's oceans. Understanding the dynamics of aerosols is important to understanding the earth's radiation balance. In evaluating the factors controlling DMS in the troposphere it is vital to understand the dynamics of DMS in the surface ocean. The biogeochemical processes controlling DMS concentration in seawater are myriad; modeling and theoretical estimation are problematic. At the beginning of this project we believed that we were on the verge of simplifying the ship-track measurement of DMS, and we proposed to deploy such a system to develop a database relating high frequency DMS measurements to biological and physicochemical and optical properties of surface water that can be quantified by remote sensing techniques. We designed a system to measure DMS concomitantly with other basic chemical and biological data in a flow-through system. The project was collaborative between Woods Hole Oceanographic Institution (WHOI) and Bermuda Biological Station for Research (BBSR). The project on which we are reporting was budgeted for only one year with a one year no-cost extension. At WHOI our effort was directed towards designing traps which would be used to concentrate DMS from seawater and allow storage for subsequent analysis. At that time, GC systems were too large for easy long-term deployment on a research vessel like R/V Weatherbird, so we focused on simplifying the shipboard sampling procedure. Initial studies of sample recovery with high levels of DMS suggested that Carboxen 1000, a relatively new carbon molecular sieve, could be used as a stable storage medium. The affinity of Carboxen for DMS is several orders of magnitude higher than gold wool (another adsorbent used for DMS collection) on a weight or volume basis. Furthermore, Carboxen's affinity for DMS is also far less susceptible to humidity than gold wool. Unfortunately, further experiments with low level DMS indicated that recovery of DMS after storage was not quantitative. The material has proven to be completely acceptable for short term storage and has been incorporated into a micro-GC system. Since working on this project, we have collaborated with RVM Scientific in Santa Barbara in the design and construction of small portable micro-GC's that will make feasible at-sea measurement in moving ships, making rapid gas analysis and quantification feasible in a ship-track mode. Throughout this period at both WHOI and BBSR, we continued to analyze field data to understand that patterns of time and space variability in DMS and the processes that govern it. These insights will be crucial to determining the specifications for our automated sampling program. The data from this, the longest continuous sampling program for ocean DMS, provided insights into year to year and short-term variability.

Dacey, J. W. H.



Phytotoxicity Assessment Of Effluent Waters, Surface Water And Sediments  

Microsoft Academic Search

Bioassays are valuable tools for environmental risk assessment, because they respond to bioavailable fraction of pollutants\\u000a in water, sediments and soil. The phytotoxicity of water and sediments from Ignalina NPP area, Lithuania, industrial areas\\u000a in Lithuania and Sweden, and a municipal landfill, and its potential impacts on receiving water was determined by Lepidium sativum, Spirodela polyrrhiza and Tradescantia clone 02.

Danguol? Montvydien?; Danut? Mar?iulionien?; Vilmant? Karlavi?ien?; William Hogland


Interaction of surface and subsurface waters in the system  

NASA Astrophysics Data System (ADS)

Purpose of the study - to assess the influence of the Khibiny massif on the formation of the chemical composition of surface and subsurface waters, generated within its boundaries using physical-chemical modeling ("Selector" software package). Objects of monitoring - rivers with sources in the upper reaches of the Khibiny massif (surface waters), and boreholes, located in these rivers' valleys (subsurface waters) have been chosen as objects of monitoring. Processes of formation of surface and subsurface waters, generated within the boundaries of the Khibiny massif, have been considered within the framework of a unified system "water-rock-atmosphere-carbon". The initial data of the model: chemical compositions of the Khibiny massif rocks and chemical analyses of atmospheric and surface waters. Besides, there have been considered Clarke concentrations S, Cl, F, C, their influence on the formation of chemical composition of water solutions; geochemical mobility of chemical elements. The previously developed model has been improved with the purpose of assessment of the influence of organic substance, either liquid or solid, on the formation of the chemical composition of water. The record of the base model of the multisystem includes 24 independent components (Al-B-Br-Ar-He-Ne-C-Ca-Cl-F-K-Mg-Mn-N-Na-P-S-Si-Sr-Cu-Zn-H-O-e), 872 dependent components, including, in a water solution - 295, in a gas phase - 76, liquid hydrocarbons - 111, solid phases, organic and mineral substances - 390. The record of solid phases of multisystem is made with consideration of the mineral composition of the Khibiny massif. Using the created model, the physical-chemical modeling of surface and subsurface water generation has been carried out: 1. The system "water-rock-atmosphere" has been studied, depending on the interaction degree (ksi) of rock with water. A model like this allowed investigating the interactions of surface waters (rivers and lakes) with rocks that form the Khibiny massif. 2. The evolution of subsurface waters has been studied using reservoir dynamics. It was assumed that the generated surface waters react with rock, when getting down at a certain depth, which allows tracing the process of formation and change of waters in the underground space. A computer model of surface waters was compared with the results of clean water monitoring (2001), while the computer calculation of subsurface waters was compared to the data of monitoring of Vudjavrjok, Kunijok and Oleny Ruchey rivers deposits.

Mazukhina, Svetlana; Masloboev, Vladimir; Chudnenko, Konstantin; Bychinski, Valerii; Sandimirov, Sergey



Water Quality Indicators Guide [and Teacher's Handbook]: Surface Waters.  

ERIC Educational Resources Information Center

This guide aids in finding water quality solutions to problems from sediment, animal wastes, nutrients, pesticides, and salts. The guide allows users to learn the fundamental concepts of water quality assessment by extracting basic tenets from geology, hydrology, biology, ecology, and wastewater treatment. An introduction and eight chapters are…

Terrell, Charles R.; Perfetti, Patricia Bytnar


Liquid water can slip on a hydrophilic surface  

PubMed Central

Understanding and predicting the behavior of water, especially in contact with various surfaces, is a scientific challenge. Molecular-level understanding of hydrophobic effects and their macroscopic consequences, in particular, is critical to many applications. Macroscopically, a surface is classified as hydrophilic or hydrophobic depending on the contact angle formed by a water droplet. Because hydrophobic surfaces tend to cause water slip whereas hydrophilic ones do not, the former surfaces can yield self-cleaning garments and ice-repellent materials whereas the latter cannot. The results presented herein suggest that this dichotomy might be purely coincidental. Our simulation results demonstrate that hydrophilic surfaces can show features typically associated with hydrophobicity, namely liquid water slip. Further analysis provides details on the molecular mechanism responsible for this surprising result. PMID:21911406

Ho, Tuan Anh; Papavassiliou, Dimitrios V.; Lee, Lloyd L.; Striolo, Alberto



Studies of the snail vectors of bilharziasis mansoni in north-eastern Brazil  

PubMed Central

The authors describe the bilharziasis endemic areas in north-eastern Brazil, giving the rainfall and general characteristics of the climate. The life-cycles of the two snail vectors—Australorbis glabratus and Tropicorbis centimetralis—in Pernambuco are described. Considerable attention is given to the effects on the snails of the annual drought, which causes many of the habitats to dry up and seriously affects the snail life-cycles and survival patterns. The snails are able to populate habitats that are dry for 5-7 months every year. They survive during the dry season in the protection of debris, vegetation, etc. A. glabratus is more susceptible to infection with Schistosoma mansoni than is T. centimetralis, but the latter is an effective vector, nevertheless, probably because it often occurs in very large numbers. A. glabratus with mature infections die or lose their infections when removed from the water for 20-30 days. Immature parasites are not killed under the same conditions. Infection with S. mansoni injures the snails and may kill them. It also reduces the reproductive capacity of the vectors, but it does not permanently castrate them. The epidemiological significance of these findings and their meaning in terms of snail control are discussed. PMID:13573116

Barbosa, Frederico S.; Olivier, Louis



Deterministic assembly of land snail communities according to species size and diet.  


1. We investigated whether coexisting snail species in 145 treeless fen communities in the Western Carpathian Mountains differed more in size and diet than would be expected by chance, as predicted for traits commonly associated with competition and differential resource acquisition under limiting similarity theory. 2. Contrary to expectations, coexisting snail species were no more different in body size than expected by chance under a null model. However, variation in body size played a significant role in structuring snail communities: coexisting snail species were significantly more similar with respect to body size. 3. We developed two new test statistics to expand our investigation of limiting similarity to include diet, a nominal trait. We tested whether communities of snails were characterized by a greater richness of diet, and whether different diets were represented more or less evenly within communities. Communities of snails were significantly less evenly distributed than expected by chance, with detritivores being over-represented relative to predatory strategies. 4. We also examined the effect of water pH and conductivity, herbaceous cover, and bryophyte and vascular plant richness, on these trends by examining how the effect size of our tests varied across these gradients. Convergence in species size increased with increasing habitat pH. Specifically, smaller snail species were over-represented in fen communities in general, and this effect was accentuated in increasingly calcareous fens. 5. Theory predicts that traits related strongly to environmental conditions are more likely to be convergent. Our findings support this suggestion, as small snail species have an advantage in tolerating freezing conditions over winter when refuges are limited. 6. These results add to the growing body of literature demonstrating that variation in body size and diet play a strong role in structuring communities, although frequently in ways not predicted by limiting similarity theory. Finally, our results increase our understanding of how species are assembled non-randomly into communities with respect to important traits. PMID:20345504

Schamp, Brandon; Horsák, Michal; Hájek, Michal



Evaluation of environmental methods to control snails in an irrigation system in Central Morocco.  


The Moroccan Ministry of Public Health has launched a programme to eliminate schistosomiasis. One of the components in this process is the control of Bulinus truncatus, the intermediate host snail of Schistosoma haematobium. We evaluated three environmentally safe measures to control B. truncatus in siphon boxes, the main breeding sites for these snails in the Tessaout Amont irrigation system. The first method involved covering the siphon boxes to exclude light and reduce algal growth, the second consisted of increasing the frequency of emptying and cleaning the siphon boxes, and the third method increased water velocity to hinder the establishment of the intermediate hosts. The results showed that covering had a pronounced effect on snail and egg mass density, was accepted by the local community and prevented water contact. Cleaning the siphons three times during the irrigation season led to a reduction in snail density although it was not statistically significant and recolonization was rapid. Increasing water velocity by reducing the dimensions of siphon boxes delayed recolonization, but such a control measure can be applied only in specific situations where it does not pose hydraulic problems. The three interventions were selectively effective against B. truncatus, whereas other snails such as Physa acuta and Lymnaea peregra were hardly affected. Covering, the most promising control measure, could be useful in the Moroccan schistosomiasis eradication programme. However, further investigations are needed to assess its impact on water quality. PMID:10995096

Laamrani, H; Khallaayoune, K; Boelee, E; Laghroubi, M M; Madsen, H; Gryseels, B



Water Structuring over the Hydrophobic Surface of Cellulose.  


Many important biological solutes possess not only polar and hydrogen-bonding functionalities but also weakly hydrating, or hydrophobic, surfaces. While the aggregation of these hydrophobic surfaces has been shown to play an important role in the aggregation of individual chains of cellulose, it is not known whether the water structuring imposed by these hydrophobic surfaces more closely resembles that associated with small hydrophobic solutes like methane and fats or more closely resembles that associated with extended hydrophobic surfaces like mica or waxy planes. By using molecular dynamics simulations to characterize the water molecule orientations over different regions of the 100 surface of cellulose in contact with water, it was found that the hydrophobic strips of the cellulose crystal are sufficiently narrow that they hydrate like a fatty acid chain, rather than like a more extended surface, suggesting that their aggregation would be dominated by entropy rather than enthalpy. PMID:25365241

Miyamoto, Hitomi; Schnupf, Udo; Brady, John W



Water accounting for conjunctive groundwater/surface water management: case of the SingkarakOmbilin  

E-print Network

Water accounting for conjunctive groundwater/surface water management: case of the Singkarak University, 216 Riley-Robb Hall, Ithaca, NY 14853-5701, USA b International Water Management Institute, P 2003 Abstract Because water shortages limit development in many parts of the world, a systematic

Walter, M.Todd


Investigation of surface water behavior during glaze ice accretion  

NASA Technical Reports Server (NTRS)

Microvideo observations of glaze ice accretions on 1-in-diameter cylinders in a closed-loop refrigerated wind tunnel were obtained to study factors controlling the behavior of unfrozen surface water during glaze ice accretion. Three zones of surface water behavior were noted, each with a characteristic roughness. The effect of substrate thermal and roughness properties on ice accretions was also studied. The contact angle and hysteresis were found to increase sharply at temperatures just below 0 C, explaining the high resistance to motion of water beads observed on accreting glaze ice surfaces. Based on the results, a simple multizone modification to the current glaze ice accretion model is proposed.

Hansman, R. John, Jr.; Turnock, Stephen R.



Surface behaviour of bile salts and tetrahydrolipstatin at air\\/water and oil\\/water interfaces  

Microsoft Academic Search

The surface behaviour of two bile salts, sodium deoxycholate (NaDC) and sodium taurodeoxycholate (NaTDC), as well as that of tetrahydrolipstatin (THL), a potent gastrointestinal lipase inhibitor, was studied at air\\/water and oil\\/water interfaces, using interfacial tensiometry methods. The surface behaviour of NaDC and NaTDC was comparable at both oil\\/water and air\\/water interfaces. A fairly compact interfacial monolayer of bile salts

Ali Tiss; Stéphane Ransac; Hans Lengsfeld; Paul Hadvàry; Alain Cagna; Robert Verger



Ab initio study of water interaction with a Cu surface.  


We have performed a first principles investigation of water interaction with a Cu surface. The calculated surface energy of a Cu(100) slab is in reasonable agreement with experimental data. The energy of water dissociation is in agreement with experiment. The results of the ab initio calculations are compared to experimental data on hydrogen partial pressure. It is concluded that Cu(OH)(ads) is formed due to a reaction between Cu and anoxic water. The energy of the Cu(100) slab with OH and H adsorbed is lower than the energy of the same slab with an adsorbed water molecule. PMID:20804187

Belonoshko, A B; Rosengren, A



Evaluation of limestone neutralization of acidic Adirondack surface waters  

SciTech Connect

This research project evaluated the use of limestone in packed-bed reactors to neutralize acidified Adirondack surface waters (particularly streams). The project was composed of two phases; investigation of sediment-water interactions and evaluation of the kinetics of limestone packed-bed-reactor neutralization. Experimental results demonstrated that there is little sediment water interaction with regard to hydrogen ion in the Adirondack lakes and streams studied. The results also demonstrated that neutralization of acidified Adirondack surface water by limestone packed-bed reactors is feasible. A preliminary design procedure is presented to show this feasibility.

Bisogni, J.J. Jr.



Evaluation of the ERA40 Surface Water Budget and Surface Temperature for the Mackenzie River Basin  

Microsoft Academic Search

We assess the systematic biases in temp erature and precipitation, and the surface water budget of ERA-40 for the Mackenzie River basin by comparing monthly averages from ERA-40 with basin averages of surface observations of temperature, precipitation, evaporation and streamflow from the Mackenzie GEWEX (Global Energy and Water Cycle Experiment) Study (MAGS). The bias and spinup of precipitation in ERA-40

Alan K. Betts; John H. Ball; Pedro Viterbo



The Utility of Surface Temperature Measurements for the Remote Sensing of Surface Soil Water Status  

Microsoft Academic Search

Experiments carried out on an Avondale loam soil indicated that the thermal inertia concept of soil water content detection is reasonably sound. The volumetric water contents of surface soil layers between 2 and 4 cm thick were found to be linear functions of the amplitude of the diurnal surface soil temperature wave for clear day-night periods. They were also found

S. B. Idso; T. J. Schmugge; R. D. Jackson; R. J. Reginato



Discrete movements of foot epithelium during adhesive locomotion of a land snail.  


During the adhesive locomotion of land snails a series of short dark transverse bands, called pedal or foot waves, is visible ifa moving snail's ventral surface is observed through a sheet of glass. Moreover, the mucus secreted from the pedal glands and some pedal epithelial cells forms a thin layer which acts as a glue augmenting adherence, while also acting as a lubricant under the moving parts of the snail's foot. The relationships between velocity and the frequency of pedal waves as well as changes in the volume of small air bubbles under foot waves were analyzed by means of digital recordings made through a glass sheet on which the snails were moving. On the ventral surface of a moving snail foot, the adhering parts of the foot constituted about 80% of the total area, while several moving parts only about 20%. The single moving region of the foot (the pedal wave) amounted to about 3% of snail length. The epithelium in the region of the pedal wave was arched above the substrate and was also more wrinkled than the stationary epithelium, which enabled the forward motion of each specific point of epithelium during the passage of a pedal wave above it. The actual area of epithelium engaged by a pedal wave was at least 30% greater than the area of the epithelium as recorded through a glass sheet. In the region of the pedal wave, the tiny subepithelial muscles acting on the epithelium move it up in the front part of the wave, and then down at the end of the wave, operating vertically in relation to the substrate. In the middle part of the wave, the epithelium only moves forward. In summary, during the adhesive locomotion of snails, the horizontal movement of the ventral surface epithelium proceeds as temporally separate phases of upward, forward and downward movement. PMID:22428315

Tyrakowski, Tomasz; Kaczorowski, Piotr; Paw?owicz, Wojciech; Zió?kowski, Marcin; Smuszkiewicz, Piotr; Trojanowska, Iwona; Marsza?ek, Andrzej; Zebrowska, Ma?gorzata; Lutowska, Monika; Kopczy?ska, Ewa; Lampka, Magdalena; Ho?y?ska-Iwan, Iga; Piskorska, Elzbieta



Identifying and Mapping Seasonal Surface Water Frost with MGS TES  

NASA Astrophysics Data System (ADS)

The Thermal Emission Spectrometer (TES) visible/near-infrared and thermal infrared bolometers measured surface broadband albedo and temperature for more than three Mars years. As seasons progress on Mars, surface temperatures may fall below the frost point of volatiles in the atmosphere (namely, carbon dioxide and water). Systematic mapping of the spatial and temporal occurrence of these volatiles in the martian atmosphere, on the surface, and in the subsurface has shown their importance in understanding the climate of Mars. However, few studies have investigated seasonal surface water frost and its role in the global water cycle. We examine zonally-averaged TES daytime albedo, temperature, and water vapor abundance data [after Smith, 2004] to map the presence of surface water frost on Mars. Surface water frost occurs in the polar and mid latitudes, in regions with surface temperatures less than 220 K and above 150 K, and can significantly increase albedo relative to the bare surface. In the northern hemisphere water frost is most apparent in late fall/early winter, before the onset of carbon dioxide frost. Dust storms occurring near northern winter solstice affect albedo data and prevent us from putting a latitudinal lower limit on the water frost in the northern hemisphere. Regardless, seasonal water frost occurs at least as low as 48°N in Utopia Planitia, beginning at Ls=~230°, as observed by Viking Lander 2 [Svitek and Murray, 1990]. Daytime surface water frost was also observed at the Phoenix Lander site (68°N) beginning at Ls=~160° [Cull et al., 2010]. The timing of albedo variations observed by TES agree relatively well with lander observations of seasonal frost. Seasonal water frost is not detected during fall in the southern hemisphere. A potential explanation for this discrepancy, compared with frost detections in the north, is the disparity in atmospheric water vapor abundance between the two hemispheres. The frost point temperatures for water vapor in the southern hemisphere are ~5-10 K lower for the corresponding season and latitude in the north [Smith, 2004]. This inhibits the stability of water frost on the surface in the southern hemisphere and also lowers the maximum thickness of a water frost layer, potentially limiting its effect on surface albedo. Our work here shows that the seasonal progression in the northern hemisphere of Mars involves extensive deposition of water frost, similar in progression to the carbon dioxide seasonal ice cap. This behavior results in variation of surface albedo and therefore affects surface and subsurface temperatures, which could impact the distribution of ground ice. Surface frost and subsequent mixing of vapor back into the atmosphere likely plays an important role in the global water cycle. Mapping of water frost's geographical extent, timing, and impact on surface albedo can provide insight into the processes controlling the present Martian climate. References: Cull, S. et al. (2010) JGR, 115, E00E19. Smith, M. D. (2004) Icarus, 167, 148-165. Svitek, T. and Murray, B. (1990) JGR, 95(B2), 1495-1510.

Bapst, J.; Bandfield, J. L.; Wood, S. E.



Formation of Water on a Warm Amorphous Silicate Surface  

NASA Astrophysics Data System (ADS)

It is well established that reactions on interstellar dust grain surfaces are indispensable for water formation in space. Among all the intermediate products that lead to water formation, the OH radical is especially important because is a product of all the three main water formation surface routes, i.e., the hydrogenation of O, O2, and O3, and it also connects these three routes. The desorption energy of OH from dust grain surfaces, along with dust grain temperature, determines the availability OH for grain surface versus gas-phase reactions. We experimentally investigated water formation on the surface of a warm amorphous silicate via H+O3?OH+O2. The surface temperature was kept at 50 K so as to exclude the interference of O2. It is found that OH has a significant residence time at 50 K. The OH desorption energy from amorphous silicate surface is calculated to be at least 1680 K, and possibly as high as 4760 K. Water is formed efficiently via OH+H and OH+H2, and the product H2O stays on the surface upon formation. Deuterium has also been used in place of hydrogen to check isotopic effects. This work is supported by NSF, Astronomy & Astrophysics Division (Grants No. 0908108 and 1311958) and NASA (Grant No. NNX12AF38G). We thank Dr. J.Brucato of the Astrophysical Observatory of Arcetri for providing the samples used in these experiments.

Vidali, Gianfranco; He, Jiao



Tractor beam on the water surface  

E-print Network

Can one send a wave to bring an object from a distance? The general idea is inspired by the recent success in moving micro particles using light and the development of a tractor beam concept. For fluid surfaces, however, the only known paradigm is the Stokes drift model, where linear planar waves push particles in the direction of the wave propagation. Here we show how to fetch a macroscopic floater from a large distance by sending a surface wave towards it. We develop a new method of remote manipulation of floaters by forming inward and outward surface jets, stationary vortices, and other complex surface flows using nonlinear waves generated by a vertically oscillating plunger. The flows can be engineered by changing the geometry and the power of a wave maker, and the flow dissipation. The new method is robust and works both for long gravity and for short capillary waves. We use a novel method of visualising 3D particle trajectories on the surface. This letter introduces a new conceptual framework for unders...

Punzmann, Horst; Xia, Hua; Falkovich, Gregory; Shats, Michael




EPA Science Inventory

This document describes the Environmental Monitoring and Assessment program's (EMAP) vision of what is needed to evaluate the ecological condition of the surface waters of the United States. It describes the content and organization of the research plan....


Influence of low temperatures on the cercarial shedding of Paramphistomum daubneyi from the snail Lymnaea truncatula.  


Lymnaeids in nature are subjected to temperature fluctuations that may have an influence on the shedding of cercariae. Thus, experimental infections of Lymnaea truncatula by Paramphistomum daubneyi were performed to determine whether a sudden fall in temperature--daily dipping of infected snails into spring water at 14-15 degrees C, or at 6-8 degrees C--followed by its increase at 20 degrees C in the subsequent hour, had an influence on the characteristics of snail infection and cercarial production. The immersion of infected snails in cold water during a short period delayed the first cercarial shedding, at day 66 on average, in the 6-8 degrees C group vs at day 57 in the 14-15 degrees C group, or at day 49 in the 20 degrees C group. The percentage of cercaria-shedding snails was greater in the 6-8 degrees C group than in the 14-15 degrees C and the 20 degrees C ones: 41.8% vs 17.3% and 7.1%, respectively. The total number of cercariae given by each infected snail was also higher in the 6-8 degrees C group. A fall in the temperature of water during daily change, followed by its increase at 20 degrees C within the subsequent hour, stimulated the cercarial shedding of P. daubneyi. PMID:10229944

Abrous, M; Rondelaud, D; Dreyfuss, G



The biological impact of landfill leachate on nearby surface water  

SciTech Connect

Five landfill sites were evaluated for their potential to adversely impact the biotic community of surface waters. Acute and chronic aquatic toxicity tests were used to determine the toxicity of water samples collected from landfill monitoring wells and the nearest surface water. Four of the five landfill sites exhibited acute or chronic toxicity to Ceriodaphnia dubia, Daphnia magna, or Pimephales promelas. Toxicity identification procedures performed on water samples revealed toxic responses to metals and one toxic response to organic compounds. Surface water toxicity at an industrial landfill is most likely due to zinc from a tire production facility. Iron and a surfactant were determined to be the probable causes for toxicity at two municipal solid waste landfills.

Geis, S.W. [State Lab. of Hygiene, Madison, WI (United States). Biomonitoring Lab.




Microsoft Academic Search

In hydraulically well-connected groundwater and surface water systems, stream-aquifer interaction has been simulated using a MODFLOW model developed by USGS, which couples hydraulic behavior of groundwater and surface water subsystems. It assumes a constant stream-stage during each stress period, employing a stream flow routing module which is limited to steady flow in rectangular, prismatic channels. One of the challenges in



Intermolecular Casimir-Polder forces in water and near surfaces  

NASA Astrophysics Data System (ADS)

The Casimir-Polder force is an important long-range interaction involved in adsorption and desorption of molecules in fluids. We explore Casimir-Polder interactions between methane molecules in water, and between a molecule in water near SiO2 and hexane surfaces. Inclusion of the finite molecular size in the expression for the Casimir-Polder energy leads to estimates of the dispersion contribution to the binding energies between molecules and between one molecule and a planar surface.

Thiyam, Priyadarshini; Persson, Clas; Sernelius, Bo E.; Parsons, Drew F.; Malthe-Sørenssen, Anders; Boström, Mathias



Surface water connectivity dynamics of a large scale extreme flood  

NASA Astrophysics Data System (ADS)

Uses the MODIS surface water product observations of the 2011 Bangkok flood.A data gap filling method is developed to better preserve the dynamics of the event.We quantify surface water connectivity geostatistically to give new flood insights.There is a clear structure to the connectivity of the event through time and space.Changes and thresholds in the connectivity are linked to major flood mechanisms.

Trigg, Mark A.; Michaelides, Katerina; Neal, Jeffrey C.; Bates, Paul D.



MSINDO study of water adsorption on NiO surfaces  

Microsoft Academic Search

The dissociation of water adsorbed on the surface of NiO was investigated by using the semi-empirical SCF MO method MSINDO. Simulations were based on embedded cluster models representing the (100) surface, with and without a monatomic step. The angle formed between the metal adsorption site and the O–H bond associated with water has been found to be critical to the

D. J. Simpson; T. Bredow; A. R. Gerson



Miscellaneous surface-water data, Pecos River basin, New Mexico  

USGS Publications Warehouse

Miscellaneous surface-water data from the Pecos River basin of New Mexico are assembled into one table. Measurements and estimates of the discharge of streams, springs, and diversion canals and pumps that are not readily available to the public are given. The principal sources of information are published and unpublished reports and various records of the U.S. Geological Survey and the New Mexico State Engineer Office. Many thousands of surface-water discharge values are given. (USGS)

Cranston, C. Clare; Kues, Georgianna E.; Welder, G. E.



Intermolecular Casimir-Polder Forces in Water and near Surfaces  

E-print Network

The Casimir-Polder force is an important long range interaction involved in adsorption and desorption of molecules in fluids. We explore Casimir-Polder interactions between methane molecules in water, and between a molecule in water near SiO2 and hexane surfaces. Inclusion of the finite molecular size in the expression for the Casimir-Polder energy leads to estimates of the dispersion contribution to the binding energies between molecules and between one molecule and a planar surface.

Thiyam, Priyadarshini; Sernelius, Bo E; Parsons, Drew F; Malthe-Sørenssen, Anders; Boström, Mathias



Effects of ground water exchange on the hydrology and ecology of surface water.  


Ground water exchange affects the ecology of surface water by sustaining stream base flow and moderating water-level fluctuations of ground water-fed lakes. It also provides stable-temperature habitats and supplies nutrients and inorganic ions. Ground water input of nutrients can even determine the trophic status of lakes and the distribution of macrophytes. In streams the mixing of ground water and surface water in shallow channel and bankside sediments creates a unique environment called the hyporheic zone, an important component of the lotic ecosystem. Localized areas of high ground water discharge in streams provide thermal refugia for fish. Ground water also provides moisture to riparian vegetation, which in turn supplies organic matter to streams and enhances bank resistance to erosion. As hydrologists and ecologists interact to understand the impact of ground water on aquatic ecology, a new research field called "ecohydrology" is emerging. PMID:12019646

Hayashi, Masaki; Rosenberry, Donald O



Surface water (2.6) Deliberate human  

E-print Network

8 9 CAP deposition sampling sites 1 = Palo Verde ­ desert 2 = Duncan Family Farms ­ agriculture 3 of Arizona Dept. of Environmental Quality, Maricopa County, Lost Dutchman State Park, Duncan Family Farms of airborne particles · Estimate the rate of deposition to different surface types using modeling · Data

Hall, Sharon J.


Surface characterization of flax, hemp and cellulose fibers; Surface properties and the water uptake behavior  

Microsoft Academic Search

The surface characteristics of several natural fibers—flax, hemp and cellulose— were investigated using scanning electron microscopy, BET-surface area and zeta (? -) potential measurements. ? -Potential measurements using the streaming poten- tial method were performed in order to study the water uptake behavior as well as the surface properties of several natural fibers. The influence of different flax-fiber separation methods

Alexander Bismarck; Ibon Aranberri-Askargorta; Thomas Lampke; Bernhard Wielage; Artemis Stamboulis; Ilja Shenderovich; Hans-Heinrich Limbach



Reassigning the most stable surface of hydroxyapatite to the water resistant hydroxyl terminated (010) surface  

NASA Astrophysics Data System (ADS)

Understanding the surface stability and crystal growth morphology of hydroxyapatite is important to comprehend bone growth and repair processes and to engineer protein adsorption, cellular adhesion and biomineralization on calcium phosphate based bone grafts and implant coatings. It has generally been assumed from electronic structure calculations that the most stable hydroxyapatite surface is the (001) surface, terminated just above hydroxyl ions perpendicular to the {001} crystal plane. However, this is inconsistent with the known preferential growth direction of hydroxyapatite crystals and previous experimental work which indicates that, contrary to currently accepted theoretical predictions, it is actually the (010) surface that is preferentially exposed. The surface structure of the (010) face is still debated and needs reconciliation. In this work, we use a large set of density functional theory calculations to model the interaction of water with hydroxyapatite surfaces and probe the surface stability and resistance to hydrolytic remodeling of a range of surface faces including the (001) surface and the phosphate-exposed, calcium-exposed, and hydroxyl-exposed terminations of the (010) surface. For the (001) surface and the phosphate-exposed (010) surface, dissociative water adsorption is favorable. In contrast, the hydroxyl-terminated (010) surface will not split water and only molecular adsorption of water is possible. Our calculations show, overall, that the hydroxyl-terminated (010) surface is the most stable and thus should be the predominant form of the hydroxyapatite surface exposed in experiments. This finding reconciles discrepancies between the currently proposed surface terminations of hydroxyapatite and the experimentally observed crystal growth direction and surface stability, which may aid efforts to accelerate biomineralization and better control bone-repair processes on hydroxyapatite surfaces.

Zeglinski, Jacek; Nolan, Michael; Thompson, Damien; Tofail, Syed A. M.



Quality of surface water in Missouri, water year 2009  

USGS Publications Warehouse

The U.S. Geological Survey, in cooperation with the Missouri Department of Natural Resources, designs and operates a series of monitoring stations on streams throughout Missouri known as the Ambient Water-Quality Monitoring Network. During the 2009 water year (October 1, 2008, through September 30, 2009), data were collected at 75 stations-69 Ambient Water-Quality Monitoring Network stations, 2 U.S. Geological Survey National Stream Quality Accounting Network stations, 1 spring sampled in cooperation with the U.S. Forest Service, and 3 stations sampled in cooperation with the Elk River Watershed Improvement Association. Dissolved oxygen, specific conductance, water temperature, suspended solids, suspended sediment, fecal coliform bacteria, Escherichia coli bacteria, dissolved nitrate plus nitrite, total phosphorus, dissolved and total recoverable lead and zinc, and select pesticide compound summaries are presented for 72 of these stations. The stations primarily have been classified into groups corresponding to the physiography of the State, primary land use, or unique station types. In addition, a summary of hydrologic conditions in the State including peak discharges, monthly mean discharges, and seven-day low flow is presented.

Barr, Miya N.



Modeling Studies of Geothermal Systems with a Free Water Surface  

SciTech Connect

Numerical simulators developed for geothermal reservoir engineering applications generally only consider systems which are saturated with liquid water and/or steam. However, most geothermal fields are in hydraulic communicatino with shallow ground water aquifers having free surface (water level), so that production or injection operations will cause movement of the surface, and of the air in the pore spaces above the water level. In some geothermal fields the water level is located hundreds of meters below the surface (e.g. Olkaria, Kenya; Bjornsson, 1978), so that an extensive so that an extensive unsaturated zone is present. In other the caprock may be very leaky or nonexistent [e.g., Klamath Falls, oregon (Sammel, 1976)]; Cerro Prieto, Mexico; (Grant et al., 1984) in which case ther eis good hydraulic communication between the geothermal reservoir and the shallow unconfined aquifers. Thus, there is a need to explore the effect of shallow free-surface aquifers on reservoir behavior during production or injection operations. In a free-surface aquifer the water table moves depending upon the rate of recharge or discharge. This results in a high overall storativity; typically two orders of magnitude higher than that of compressed liquid systems, but one or two orders of magnitude lower than that for liquid-steam reservoirs. As a consequence, various data analysis methods developed for compressed liquid aquifers (such as conventional well test analysis methods) are not applicable to aquifer with a free surface.

Bodvarsson, Gudmundur S.; Pruess, K.



Surface Roughness of Carbides Produced by Abrasive Water Jet Machining  

Microsoft Academic Search

This study presents the effect of jet pressure, abrasive flow rate and work feed rate on smoothness of the surface produced by abrasive water jet machining of carbide of grade P25. Carbide of grade P25 is very hard and cannot be machined by conventional techniques. Cutting was performed on a water jet machine model WJ 4080. The abrasive used in

Ahsan Ali Khan; Mohd Efendee Bin Awang; Ahmad Azwari Bin Annuar



Impact of Surface Water Conditions on Preservative Leaching and  

E-print Network

assessments which indicated an elevated human health risk from arsenic (As) which could be ingested duringImpact of Surface Water Conditions on Preservative Leaching and Aquatic Toxicity from Treated Wood preservatives contain higher levels of copper (Cu) which can promote aquatic toxicity in natural water systems

Florida, University of


Statistical Analysis of Surface Water Quality Data of Eastern Massachusetts  

Microsoft Academic Search

We present a characterization of current state of surface water, changes in time and dependence on land use, precipitation regime, and possible other natural and human influences based on data from the USGS National Water Quality Assessment (NAWQA) Program for New England streams. Time series analysis is used to detect changes and relationship with discharge and precipitation regime. Statistical techniques

C. Andronache; R. Hon; N. Tedder; Q. Xian; B. Schaudt



ORIGINAL PAPER Seasonal progression of diatom assemblages in surface waters  

E-print Network

Diatoms Á Phytoplankton Á Seasonality Á Sea-ice Á Coastal Antarctic Á Proboscia inermis IntroductionORIGINAL PAPER Seasonal progression of diatom assemblages in surface waters of Ryder Bay and environmental conditions with algal speciation. Typical of near-shore Antarctic waters, biomass was dominated


Tritium in surface waters of the Yenisei River basin.  


This paper reports an investigation of the tritium content in the surface waters of the Yenisei River basin near the Mining and Chemical Combine (MCC). In 2001 the maximum tritium concentration in the Yenisei River did not exceed 4 +/- 1 Bq l(-1), which is consistent with the data of 1998-99. However, it has been found that there are surface waters containing enhanced tritium as compared with the background values for the Yenisei River. For instance, in the Ploskii Stream and the Shumikha River the maximum tritium concentrations amount to 168 and 81 Bq l(-1), respectively. The source of tritium in these surface waters is the last operating reactor at the MCC, which still uses the Yenisei water as coolant. In water and sediment samples of the Bolshaya Tel River (a tributary of the Yenisei River) the tritium content turned out to be at least 10 times higher than the background values for the Yenisei River. The measurements conducted at the RPA RADON (Moscow) revealed not only tritium but also the artificial radionuclide (14)C in the Bolshaya Tel samples. The data obtained suggest that the Bolshaya Tel River receives the major part of tritium from sediments rather than from the water catchment area. This allows the conclusion that there is water exchange between the surface waters and the radioactively contaminated underground horizons of the "Severny" testing site. PMID:12600760

Bolsunovsky, A Ya; Bondareva, L G




EPA Science Inventory

This report develops and recommends prioritized listings of chemical, physical, and biological parameters which can be used to assess the environmental impact of oil shale development on surface water resources. Each of the potential water-related problems is addressed in the con...



E-print Network

NUMERICAL SIMULATION OF SURFACE WATER WAVES ON THE SPHERE Panayotis Panayotaros Department for the numerical simulation of small amplitude water waves in spherical geometry. The method is based on a free simulation we consider such equations, and our numerical implementation preserves the Hamiltonian structure


Dynamics of ice nucleation on water repellent surfaces.  


Prevention of ice accretion and adhesion on surfaces is relevant to many applications, leading to improved operation safety, increased energy efficiency, and cost reduction. Development of passive nonicing coatings is highly desirable, since current antiicing strategies are energy and cost intensive. Superhydrophobicity has been proposed as a lead passive nonicing strategy, yet the exact mechanism of delayed icing on these surfaces is not clearly understood. In this work, we present an in-depth analysis of ice formation dynamics upon water droplet impact on surfaces with different wettabilities. We experimentally demonstrate that ice nucleation under low-humidity conditions can be delayed through control of surface chemistry and texture. Combining infrared (IR) thermometry and high-speed photography, we observe that the reduction of water-surface contact area on superhydrophobic surfaces plays a dual role in delaying nucleation: first by reducing heat transfer and second by reducing the probability of heterogeneous nucleation at the water-substrate interface. This work also includes an analysis (based on classical nucleation theory) to estimate various homogeneous and heterogeneous nucleation rates in icing situations. The key finding is that ice nucleation delay on superhydrophobic surfaces is more prominent at moderate degrees of supercooling, while closer to the homogeneous nucleation temperature, bulk and air-water interface nucleation effects become equally important. The study presented here offers a comprehensive perspective on the efficacy of textured surfaces for nonicing applications. PMID:22235939

Alizadeh, Azar; Yamada, Masako; Li, Ri; Shang, Wen; Otta, Shourya; Zhong, Sheng; Ge, Liehui; Dhinojwala, Ali; Conway, Ken R; Bahadur, Vaibhav; Vinciquerra, A Joseph; Stephens, Brian; Blohm, Margaret L



Dynamics of Ice Nucleation on Water Repellent Surfaces Azar Alizadeh,*,  

E-print Network

Dynamics of Ice Nucleation on Water Repellent Surfaces Azar Alizadeh,*, Masako Yamada, Ri Li, Wen of ice accretion and adhesion on surfaces is relevant to many applications, leading to improved operation has been proposed as a lead passive nonicing strategy, yet the exact mechanism of delayed icing

Dhinojwala, Ali


Tritium in surface waters of the Yenisei River basin  

Microsoft Academic Search

This paper reports an investigation of the tritium content in the surface waters of the Yenisei River basin near the Mining and Chemical Combine (MCC). In 2001 the maximum tritium concentration in the Yenisei River did not exceed 4 ± 1 Bq l–1, which is consistent with the data of 1998–99. However, it has been found that there are surface

A. Ya. Bolsunovsky; L. G. Bondareva



Evidence for the Exposure of Water Ice on Titan's Surface  

E-print Network

Evidence for the Exposure of Water Ice on Titan's Surface Caitlin A. Griffith,1 * Tobias Owen,2 Thomas R. Geballe,3 John Rayner,2 Pascal Rannou4 The smoggy stratosphere of Saturn's largest moon, Titan.0, 2.9, and 5.0 micrometers. We derived a spectrum of Titan's surface within these "windows

Griffith, Caitlin A.


241Americium in Mediterranean surface waters  

Microsoft Academic Search

LITTLE information is available to date on the occurrence of 241americium in sea water, except for data obtained in some special areas such as in the vicinity of a nuclear reprocessing plant (Windscale, UK)1 or in areas of close-in fallout from nuclear explosion tests (Bikini and Eniwetok Atolls, Pacific)2. So far, only a few data of 241Am obtained from one

R. Fukai; S. Ballestra; E. Holm



Mobility of Water on Oxide Surfaces Studied by QENS  

SciTech Connect

Although neutron scattering is often considered a bulk probe, we demonstrate that the mobility of surface water on oxide nano-powders can be investigated using quasielastic neutron scattering. We discuss how the reduced number of hydrogen bonds per water molecule associated with surface confinement leads to a qualitative modification of single-particle translational dynamics compared to bulk water. The mobility of surface water in zirconium oxide with two hydration layers present is discussed in detail. The outer hydration layer exhibits translational dynamics on the time scale of tens of picoseconds, and thus can be studied using time-of-flight neutron spectrometry. The translational dynamics of the inner hydration layer in the range of hundreds of picoseconds can be assessed with backscattering neutron spectrometry. Interestingly, despite being slower by two orders of magnitude, the translational motion of the molecules of the inner hydration layer may share more common traits with bulk water compared to the motion of the outer hydration layer, the dynamics of which is slower than that of bulk water by just one order of magnitude. Similar to bulk water, the temperature dependence of the residence time for the water molecules of the inner hydration layer is non-Arrhenius, and can be described by a Vogel-Fulcher-Tammann (VFT) law. On the other hand, the molecules of the outer hydration layer demonstrate Arrhenius-type temperature dependence indicative of thermally activated surface jump diffusion. Our recent study of surface water on cerium oxide, which exhibits faster dynamics compared to water on zirconium oxide, has ventured into the low-temperature region (down to 200 K). Below 215 K, we have found a deviation from the VFT temperature dependence for the residence time indicative of a surprise "fragile"-to-"strong" transition in the surface water. While "fragile"-to-"strong" transition has been predicted in supercooled bulk water, there has been no prediction of such a transition in surface water. We discuss the links between our results and recent work on hydration water in carbon nanotubes and proteins.

Mamontov, Eugene [ORNL



An Ontology Design Pattern for Surface Water Features  

SciTech Connect

Surface water is a primary concept of human experience but concepts are captured in cultures and languages in many different ways. Still, many commonalities can be found due to the physical basis of many of the properties and categories. An abstract ontology of surface water features based only on those physical properties of landscape features has the best potential for serving as a foundational domain ontology. It can then be used to systematically incor-porate concepts that are specific to a culture, language, or scientific domain. The Surface Water ontology design pattern was developed both for domain knowledge distillation and to serve as a conceptual building-block for more complex surface water ontologies. A fundamental distinction is made in this on-tology between landscape features that act as containers (e.g., stream channels, basins) and the bodies of water (e.g., rivers, lakes) that occupy those containers. Concave (container) landforms semantics are specified in a Dry module and the semantics of contained bodies of water in a Wet module. The pattern is imple-mented in OWL, but Description Logic axioms and a detailed explanation is provided. The OWL ontology will be an important contribution to Semantic Web vocabulary for annotating surface water feature datasets. A discussion about why there is a need to complement the pattern with other ontologies, es-pecially the previously developed Surface Network pattern is also provided. Fi-nally, the practical value of the pattern in semantic querying of surface water datasets is illustrated through a few queries and annotated geospatial datasets.

Sinha, Gaurav [Ohio University, Athens; Mark, David [University at Buffalo, NY; Kolas, Dave [Raytheon BBN Technologies; Varanka, Dalia [U.S. Geological Survey, Rolla, MO; Romero, Boleslo E [University of California, Santa Barbara; Feng, Chen-Chieh [National University of Singapore; Usery, Lynn [U.S. Geological Survey, Rolla, MO; Liebermann, Joshua [Tumbling Walls, LLC; Sorokine, Alexandre [ORNL



Tracer injection techniques in flowing surface water  

NASA Astrophysics Data System (ADS)

Residence time distributions for flowing water and reactive matter are commonly used integrated properties of the transport process for determining technical issues of water resource management and in eco-hydrological science. Two general issues for tracer techniques are that the concentration-vs-time relation following a tracer injection (the breakthrough curve) gives unique transport information in different parts of the curve and separation of hydromechanical and reactive mechanisms often require simultaneous tracer injections. This presentation discusses evaluation methods for simultaneous tracer injections based on examples of tracer experiments in small rivers, streams and wetlands. Tritiated water is used as a practically inert substance to reflect the actual hydrodynamics, but other involved tracers are Cr(III)-51, P-32 and N-15. Hydromechanical, in-stream dispersion is reflected as a symmetrical spreading of the spatial concentration distribution. This requires that the transport distance over water depth is larger than about five times the flow Peclet number. Transversal retention of both inert and reactive solutes is reflected in terms of the tail of the breakthrough curve. Especially, reactive solutes can have a substantial magnification of the tailing behaviour depending on reaction rates or partitioning coefficients. To accurately discriminate between the effects of reactions and hydromechanical mixing its is relevant to use simultaneous injections of inert and reactive tracers with a sequential or integrated evaluation procedure. As an example, the slope of the P-32 tailing is consistently smaller than that of a simultaneous tritium injection in Ekeby wetland, Eskilstuna. The same applies to N-15 injected in the same experiment, but nitrogen is affected also by a systematic loss due to denitrification. Uptake in stream-bed sediments can be caused by a pumping effect arising when a variable pressure field is created on the stream bottom due to bed irregularities. The so-called pumping model provided good estimates of the storage in the hyporheic zone under different stream discharges and stream flow conditions along streams. Evaluations Hobøl River, Norway, and Säva Brook, Sweden, at two occasions in both stream indicate that the relative residence time in the hyporheic zone is linearly proportional to the squared Froude Number. The residence time is scaled with water depth and hydraulic conductivity of the bed. The effect of such transient storage in e.g. the hyporheic zone gives rise to a tailing, but the breakthrough curve become increasingly symmetrical with Damköhler number. Such a symmetrical breakthrough can be erroneously taken as an effect of in-stream dispersion, even though this similarity is merely due to the physical analogy of various advection velocities over the transport cross-section, differential advection.

Wörman, A.



Seasonal variation in abiotic factors and ferulic acid toxicity in snail-attractant pellets against the intermediate host snail Lymnaea acuminata.  


Laboratory evaluation was made to access the seasonal variations in abiotic environmental factors temperature, pH, dissolved oxygen, carbon dioxide, electrical conductivity and ferulic acid toxicity in snail-attractant pellets (SAP) against the intermediate host snail Lymnaea acuminata in each month of the years 2010 and 2011. On the basis of a 24-h toxicity assay, it was noted that lethal concentration values of 4.03, 3.73% and 4.45% in SAP containing starch and 4.16, 4.23% and 4.29% in SAP containing proline during the months of May, June and September, respectively, were most effective in killing the snails, while SAP containing starch/proline?+?ferulic acid was least effective in the month of January/February (24-h lethal concentration value was 7.67%/7.63% in SAP). There was a significant positive correlation between lethal concentration value of ferulic acid containing SAP and levels of dissolved O2 /pH of water in corresponding months. On the contrary, a negative correlation was observed between lethal concentration value and dissolved CO2 /temperature of test water in the same months. To ascertain that such a relationship between toxicity and abiotic factors is not co-incidental, the nervous tissue of treated (40% and 80% of 24-h lethal concentration value) and control group of snails was assayed for the activity of acetylcholinesterase (AChE) in each of the 12?months of the same year. There was a maximum inhibition of 58.43% of AChE, in snails exposed to 80% of the 24-h lethal concentration value of ferulic acid?+?starch in the month of May. This work shows conclusively that the best time to control snail population with SAP containing ferulic acid is during the months of May, June and September. PMID:23170774

Agrahari, P; Singh, D K



Nucleate boiling of water from plain and structured surfaces  

SciTech Connect

Heat transfer from plain surface and from surfaces with distinct nucleation sites has been investigated under saturated pool boiling condition. Surfaces have been prepared with regular array of discrete nucleation sites formed by micro-drilling. Distilled water has been used as the boiling liquid. Out of various available correlations, Rohsenow correlation [W.M. Rohsenow, A method of correlating heat transfer data for surface boiling of liquids, Trans. ASME 74 (1952) 969-976] gives best agreement with the experimental data from plain surface at low degree of superheat. A mechanistic model also provides a good trend matching with the same experimental data. With the introduction of artificial nucleation sites substantial augmentation in heat transfer for distilled water compared to the plane surface has been noted. Continuous increase in nucleation site density increases the rate of heat transfer with a diminishing trend of enhancement. A correlation similar to that of Yamagata et al. [K. Yamagata, F. Hirano, K. Nishiwaka, H. Matsouka, Nucleate boiling of water on the horizontal heating surface, Mem. Fac. Eng. Kyushu 15 (1955) 98] has been developed to fit the experimental data of plane surface. Modification of the same correlation to take care of the nucleation site density has been developed and used to predict the experimental data from augmented surfaces. (author)

Das, A.K.; Das, P.K.; Saha, P. [Department of Mechanical Engineering, Indian Institute of Technology, Kharagpur 721302 (India)



Water transport mechanism through open capillaries analyzed by direct surface modifications on biological surfaces  

PubMed Central

Some small animals only use water transport mechanisms passively driven by surface energies. However, little is known about passive water transport mechanisms because it is difficult to measure the wettability of microstructures in small areas and determine the chemistry of biological surfaces. Herein, we developed to directly analyse the structural effects of wettability of chemically modified biological surfaces by using a nanoliter volume water droplet and a hi-speed video system. The wharf roach Ligia exotica transports water only by using open capillaries in its legs containing hair- and paddle-like microstructures. The structural effects of legs chemically modified with a self-assembled monolayer were analysed, so that the wharf roach has a smart water transport system passively driven by differences of wettability between the microstructures. We anticipate that this passive water transport mechanism may inspire novel biomimetic fluid manipulations with or without a gravitational field. PMID:24149467

Ishii, Daisuke; Horiguchi, Hiroko; Hirai, Yuji; Yabu, Hiroshi; Matsuo, Yasutaka; Ijiro, Kuniharu; Tsujii, Kaoru; Shimozawa, Tateo; Hariyama, Takahiko; Shimomura, Masatsugu



Pathogenic Leptospiras Isolated from Malaysian Surface Waters  

PubMed Central

Pathogenic leptospiras (1,424) isolated from natural waters and wet soils in Malaysia comprised 29 different serovars (synonym serotypes). All except two of the serovars had been found previously in Malaysia. The exceptional serovars were werrasingha, an Autumnalis serogroup member originally isolated in Ceylon, and a new serovar designated evansi. Serovar evansi had serological affinities with serovar ranarum which was isolated from the kidney of a frog in Iowa. The large variety of serovars found in jungle areas was consistent with similar previous findings of diverse serovar infections in troops who had operated in Malaysian jungles. PMID:1110490

Alexander, A. D.; Evans, L. B.; Baker, M. F.; Baker, H. J.; Ellison, D.; Marriapan, M.



Oxidation of graphite surface: the role of water  

E-print Network

Based on density functional calculations, we demonstrate a significant difference in oxidation patterns between graphene and graphite and the formation of defects after oxidation. Step-by-step modeling demonstrates that oxidation of 80% of the graphite surface is favorable. Oxidation above half of the graphite surface significantly decreases the energy costs of vacancy formation with CO2 production. The presence of water is crucial in the transformation of epoxy groups to hydroxyl, the intercalation with further bundle and exfoliation. In water-rich conditions, water intercalates graphite at the initial stages of oxidation and oxidation, which is similar to the oxidation process of free-standing graphene; in contrast, in water-free conditions, large molecules intercalate graphite only after oxidation occurs on more than half of the surface.

Boukhvalov, D W




EPA Science Inventory

One of the challenges in assessing the current impact of the discharge of arsenic contaminated ground water into a surface water body is differentiating the arsenic ground-water flux versus dissolution of in-place contaminated sediments. A field investigation has been carried ou...


A wetland hydrology and water quality model incorporating surface water\\/groundwater interactions  

Microsoft Academic Search

In the last two decades the beneficial aspects of constructed treatment wetlands have been studied extensively. However, the importance of restored wetlands as a best management practice to improve the water quality of storm water runoff has only recently been appreciated. Furthermore, investigating surface water\\/groundwater interactions within wetlands is now acknowledged to be essential in order to better understand the

Cevza Melek Kazezy?lmaz-Alhan; Miguel A. Medina; Curtis J. Richardson



Ground Water and Surface Water in the Haiku Area, East Maui, Hawaii.  

National Technical Information Service (NTIS)

The purpose of this report is to describe (1) the regional relation between surface water and ground water, (2) the conceptual model of ground-water occurrence, and (3) flow characteristics of individual streams in the Haiku area of northeastern Maui. Exi...

S. B. Gingerich



[Current status of surface water acidification in Northeast China].  


In order to evaluate the status of surface water acidification in Northeast China, chemical composition of 33 small streams was investigated in August, 2011. It was found that only a few waters located in Changbai Mountain had pH of lower than 6.0, and all waters had acid neutralizing capacity (ANC) of higher than 0.2 meq x L(-1). This indicated that surface water acidification was not a regional environmental issue in Northeast China. HCO3- was the major anion, with SO4(2-) concentration mostly below 150 microeq x L(-1) and even much lower NO3- concentration. Low concentration of SO4(2-) and NO3- means no serious acid deposition in this area. However, the distribution of acidic forest soils, with low base cation weathering rate, could only provide limited buffering capacity for surface water to acidification in Northeast China, and the potential risk of water acidification still existed. Currently, acid deposition in Northeast Asia could hardly cause severe acidification of surface water. The neighboring countries should therefore not amplify the environmental impact by transboundary air pollutants from China. PMID:23914517

Xu, Guang-yi; Kang, Rong-hua; Luo, Yao; Duan, Lei



Time dependence of forces between mica surfaces in water and its relation to the release of surface ions  

E-print Network

between purified water with no added salt conductivity water have been attributed to po- tassium (K ) ionsTime dependence of forces between mica surfaces in water and its relation to the release of surface between two smooth mica surfaces immersed in salt-free conductivity water. A long-ranged repulsion

Klein, Jacob


Occurrence and distribution of polycyclic aromatic hydrocarbons in reclaimed water and surface water of Tianjin, China.  


Persistent organic pollutants (POPs) such as polycyclic aromatic hydrocarbons (PAHs) are of great concern due to their persistence, bioaccumulation and toxic effects. In this work, 16 PAHs included in the US Environmental Protection Agency's (EPA) priority pollutant list were analyzed using solid-phase extraction-gas chromatography-mass spectrometry (SPE-GC-MS) with a selected ion monitoring (SIM) mode. Reclaimed water and surface water sampling was undertaken in Tianjin, northern China. Total PAH concentrations varied from 1800 to 35,000 ng/L in surface waters (main rivers, tributaries, ditches, etc.) with mean value of 14,000 ng/L and from 227 to 600 ng/L in reclaimed water with mean value of 352 ng/L, respectively. The PAH profiles were dominated by low molecular weight PAHs (two- and three-ring components) in reclaimed water samples and surface water samples. These indicated that PAHs in reclaimed water and surface water might origin from oil or sewage contamination (petrogenic input). To elucidate sources, molecular indices based on indices among phenanthrene versus anthracene and fluoranthene versus pyrene were used to evaluate the possible source (pyrogenic and petrogenic sources, respectively) of PAH contamination in reclaimed water and surface water. The collected data showed that petrogenic input was predominant at almost all the stations investigated. To discriminate pattern differences and similarities among samples, principal component analysis (PCA) was performed using a correlation matrix. PCA revealed the latent relationships among all the surface water stations investigated and confirmed our analytical results. The analysis results of the ratios and PCA in this study showed that the ratios and PCA could be applied to the surface water investigation to some extent. PMID:15943926

Cao, Zhonghong; Wang, Yuqiu; Ma, Yongmin; Xu, Ze; Shi, Guoliang; Zhuang, Yuanyi; Zhu, Tan



Surface water resources issues analysis: Wheeler Reservoir watershed region  

SciTech Connect

This report is one in a continuing series of periodic water resources issues analyses (WRIAs) conducted within the various local drainage basins that comprise the larger Tennessee River drainage basin. These analyses, based primarily upon existing information gathered from a variety of sources, perform several functions: document known or probable water quality issues that should be addressed by TVA or others; identify specific needs for additional information; guide routine surface water monitoring programs; and provide focus for planning and setting priorities for subsequent water quality assessments, mitigative activities, and resource management projects. 4 refs., 1 fig., 16 tabs.

Cox, J.P.



Origin of subdiffusion of water molecules on cell membrane surfaces  

NASA Astrophysics Data System (ADS)

Water molecules play an important role in providing unique environments for biological reactions on cell membranes. It is widely believed that water molecules form bridges that connect lipid molecules and stabilize cell membranes. Using all-atom molecular dynamics simulations, we show that translational and rotational diffusion of water molecules on lipid membrane surfaces exhibit subdiffusion and aging. Moreover, we provide evidence that both divergent mean trapping time (continuous-time random walk) and long-correlated noise (fractional Brownian motion) contribute to this subdiffusion. These results suggest that subdiffusion on cell membranes causes the water retardation, an enhancement of cell membrane stability, and a higher reaction efficiency.

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



Origin of subdiffusion of water molecules on cell membrane surfaces  

E-print Network

Water molecules play an important role in providing unique environments for biological reactions on cell membranes. It is widely believed that water molecules form bridges that connect lipid molecules and stabilize cell membranes. Using all-atom molecular dynamics simulations, we show that translational and rotational diffusion of water molecules on lipid membrane surfaces exhibit subdiffusion. Moreover, we provide evidence that both divergent mean trapping time (continuous-time random walk) and long-correlated noise (fractional Brownian motion) contribute to this subdiffusion. These results suggest that subdiffusion on cell membranes causes the water retardation, an enhancement of cell membrane stability, and a higher reaction efficiency.

Yamamoto, Eiji; Yasui, Masato; Yasuoka, Kenji



Experimental observation of dark solitons on the surface of water.  


We present the first ever observation of dark solitons on the surface of water. It takes the form of an amplitude drop of the carrier wave which does not change shape in propagation. The shape and width of the soliton depend on the water depth, carrier frequency, and the amplitude of the background wave. The experimental data taken in a water tank show an excellent agreement with the theory. These results may improve our understanding of the nonlinear dynamics of water waves at finite depths. PMID:25166807

Chabchoub, A; Kimmoun, O; Branger, H; Hoffmann, N; Proment, D; Onorato, M; Akhmediev, N



Habitat characteristics for different freshwater snail species as determined biologically through macroinvertebrate information.  


Macro-invertebrates including freshwater snails collected from 643 sites over 8 successive seasons among the River Nile, branches, main canals and certain drains in eight Egyptian Governorates. Thirteen snail species and one bivalve species were identified. The most distributed were Lanistus carinatus and Physa acuta while the most abundant were Cleopatra bulimoides and Physa acuta during the whole study. The sites that harbored each snail species in all the examined water-courses were grouped seasonally and their biological assessment was determined by their minimum and maximum total point similarity percentage to that of the corresponded reference site and mean of the total points. Habitats for most snail species attained minimum total point's similarity percentage less than 21% (very poor habitat) during autumn and winter then spring while during summer very poor habitat was harbored by only few snail species. P. acuta was the only survived snails in habitat which attained 0 as a minimum total point's similarity percentage during two seasons and L. carinatus and Succinea cleopatra during one season. With respect to medically important snails very poor sites constituted 23% of Biomphalaria alexandrina sites, 14% of Lymnaea natalensis and 9.4% of Bulinus truncatus sites. The studied macroinvertebrate matrices, total number of organisms, taxa richness, the Ephemeroptera, Plecoptera, and Trichoptera (EPT) index, ratio of EPT index to chironomidae, ratio of scraper to filtering collector, contribution of dominant macroinvertebrate major group, comparison revealed descending tolerances from B. alexanrina followed by L. natalensis then B. truncates, but Hilsenhoff Biotic Index (HBI) showed the same tolerance to organic pollution. PMID:22435158

El-Khayat, Hanaa M M; Mahmoud, Kadria M A; Mostafa, Bayomy B; Tantawy, Ahmad A; El-Deeb, Fatma A; Ragb, Fawzy M; Ismail, Nahed M; El-Said, Kalil M; Taleb, Hoda M Abu



Reaction of water vapor with a clean liquid uranium surface  

SciTech Connect

To study the reaction of water vapor with uranium, we have exposed clean liquid uranium surfaces to H/sub 2/O under UHV conditions. We have measured the surface concentration of oxygen as a function of exposure, and determined the maximum attainable surface oxygen concentration X/sub 0//sup s/ as a function of temperature. We have used these measurements to estimate, close to the melting point, the solubility of oxygen (X/sub 0//sup b/, < 10/sup -4/) and its surface segregation coefficient ..beta../sup s/(> 10/sup 3/). 8 refs., 5 figs., 1 tab.

Siekhaus, W.



Lawrence Livermore National Laboratory Surface Water Protection: A Watershed Approach  

SciTech Connect

This surface water protection plan (plan) provides an overview of the management efforts implemented at Lawrence Livermore National Laboratory (LLNL) that support a watershed approach to protect surface water. This plan fulfills a requirement in the Department of Energy (DOE) Order 450.1A to demonstrate a watershed approach for surface water protection that protects the environment and public health. This plan describes the use of a watershed approach within which the Laboratory's current surface water management and protections efforts have been structured and coordinated. With more than 800 million acres of land in the U.S. under federal management and stewardship, a unified approach across agencies provides enhanced resource protection and cost-effectiveness. The DOE adopted, along with other federal agencies, the Unified Federal Policy for a Watershed Approach to Federal Land and Resource Management (UFP) with a goal to protect water quality and aquatic ecosystems on federal lands. This policy intends to prevent and/or reduce water pollution from federal activities while fostering a cost-effective watershed approach to federal land and resource management. The UFP also intends to enhance the implementation of existing laws (e.g., the Clean Water Act [CWA] and National Environmental Policy Act [NEPA]) and regulations. In addition, this provides an opportunity for the federal government to serve as a model for water quality stewardship using a watershed approach for federal land and resource activities that potentially impact surface water and its uses. As a federal land manager, the Laboratory is responsible for a small but important part of those 800 million acres of land. Diverse land uses are required to support the Laboratory's mission and provide an appropriate work environment for its staff. The Laboratory comprises two sites: its main site in Livermore, California, and the Experimental Test Site (Site 300), near Tracy, California. The main site is largely developed yet its surface water system encompasses two arroyos, an engineered detention basin (Lake Haussmann), storm channels, and wetlands. Conversely, the more rural Site 300 includes approximately 7,000 acres of largely undeveloped land with many natural tributaries, riparian habitats, and wetland areas. These wetlands include vernal pools, perennial seeps, and emergent wetlands. The watersheds within which the Laboratory's sites lie provide local and community ecological functions and services which require protection. These functions and services include water supply, flood attenuation, groundwater recharge, water quality improvement, wildlife and aquatic habitats, erosion control, and (downstream) recreational opportunities. The Laboratory employs a watershed approach to protect these surface water systems. The intent of this approach, presented in this document, is to provide an integrated effort to eliminate or minimize any adverse environmental impacts of the Laboratory's operations and enhance the attributes of these surface water systems, as possible and when reasonable, to protect their value to the community and watershed. The Laboratory's watershed approach to surface water protection will use the U.S. Environmental Protection Agency's Watershed Framework and guiding principles of geographic focus, scientifically based management and partnerships1 as a foundation. While the Laboratory's unique site characteristics result in objectives and priorities that may differ from other industrial sites, these underlying guiding principles provide a structure for surface water protection to ensure the Laboratory's role in environmental stewardship and as a community partner in watershed protection. The approach includes pollution prevention, continual environmental improvement, and supporting, as possible, community objectives (e.g., protection of the San Francisco Bay watershed).

Coty, J



Properties of water surface discharge at different pulse repetition rates  

NASA Astrophysics Data System (ADS)

The properties of water surface discharge plasma for variety of pulse repetition rates are investigated. A magnetic pulse compression (MPC) pulsed power modulator able to deliver pulse repetition rates up to 1000 Hz, with 0.5 J per pulse energy output at 25 kV, was used as the pulsed power source. Positive pulse with a point-to-plane electrode configuration was used for the experiments. The concentration and production yield of hydrogen peroxide (H2O2) were quantitatively measured and orange II organic dye was treated, to evaluate the chemical properties of the discharge reactor. Experimental results show that the physical and chemical properties of water surface discharge are not influenced by pulse repetition rate, very different from those observed for under water discharge. The production yield of H2O2 and degradation rate per pulse of the dye did not significantly vary at different pulse repetition rates under a constant discharge mode on water surface. In addition, the solution temperature, pH, and conductivity for both water surface and underwater discharge reactors were measured to compare their plasma properties for different pulse repetition rates. The results confirm that surface discharge can be employed at high pulse repetition rates as a reliable and advantageous method for industrial and environmental decontamination applications.

Ruma, Hosseini, S. H. R.; Yoshihara, K.; Akiyama, M.; Sakugawa, T.; Lukeš, P.; Akiyama, H.



Modeling decadal timescale interactions between surface water and ground water in the central Everglades, Florida, USA  

USGS Publications Warehouse

Surface-water and ground-water flow are coupled in the central Everglades, although the remoteness of this system has hindered many previous attempts to quantify interactions between surface water and ground water. We modeled flow through a 43,000 ha basin in the central Everglades called Water Conservation Area 2A. The purpose of the model was to quantify recharge and discharge in the basin's vast interior areas. The presence and distribution of tritium in ground water was the principal constraint on the modeling, based on measurements in 25 research wells ranging in depth from 2 to 37 m. In addition to average characteristics of surface-water flow, the model parameters included depth of the layer of 'interactive' ground water that is actively exchanged with surface water, average residence time of interactive ground water, and the associated recharge and discharge fluxes across the wetland ground surface. Results indicated that only a relatively thin (8 m) layer of the 60 m deep surfical aquifer actively exchanges surface water and ground water on a decadal timescale. The calculated storage depth of interactive ground water was 3.1 m after adjustment for the porosity of peat and sandy limestone. Modeling of the tritium data yielded an average residence time of 90 years in interactive ground water, with associated recharge and discharge fluxes equal to 0.01 cm d -1. 3H/3He isotopic ratio measurements (which correct for effects of vertical mixing in the aquifer with deeper, tritium-dead water) were available from several wells, and these indicated an average residence time of 25 years, suggesting that residence time was overestimated using tritium measurements alone. Indeed, both residence time and storage depth would be expected to be overestimated due to vertical mixing. The estimate of recharge and discharge (0.01 cm d-1) that resulted from tritium modeling therefore is still considered reliable, because the ratio of residence time and storage depth (used to calculated recharge and discharge) is much less sensitive to vertical mixing compared with residence time alone. We conclude that a small but potentially significant component of flow through the Everglades is recharged to the aquifer and stored there for years to decades before discharged back to surface water. Long-term storage of water and solutes in the ground-water system beneath the wetlands has implications for restoration of Everglades water quality.

Harvey, J. W.; Newlin, J. T.; Krupa, S. L.



Integrating Evolution Algorithms with Linear Programming to the Conjunctive Use of Surface and Subsurface Water  

Microsoft Academic Search

Surface water resources are strongly influenced by hydrological conditions, and using only surface water resources as water supplies may have higher shortage risk than before because of the climate change caused by the global warming. Conjunctive use of surface and subsurface water is one of the most effective water resource practices to increase water supply reliability with minimal cost and

L. Chang; Y. Chen; C. Pan



Dynamic effects of bouncing water droplets on superhydrophobic surfaces.  


Superhydrophobic surfaces have considerable technological potential for various applications due to their extreme water repellent properties. Superhydrophobic surfaces may be generated by the use of hydrophobic coating, roughness, and air pockets between solid and liquid. Dynamic effects, such as the bouncing of a droplet, can destroy the composite solid-air-liquid interface. The relationship between the impact velocity of a droplet and the geometric parameters affects the transition from the solid-air-liquid interface to the solid-liquid interface. Therefore, it is necessary to study the dynamic effect of droplets under various impact velocities. We studied the dynamic impact behavior of water droplets on micropatterned silicon surfaces with pillars of two different diameters and heights and with varying pitch values. A criterion for the transition from the Cassie and Baxter regime to the Wenzel regime based on the relationship between the impact velocity and the parameter of patterned surfaces is proposed. The trends are explained based on the experimental data and the proposed transition criterion. For comparison, the dynamic impact behavior of water droplets on nanopatterned surfaces was investigated. The wetting behavior under various impact velocities on multiwalled nanotube arrays also was investigated. The physics of wetting phenomena for bouncing water droplet studies here is of fundamental importance in the geometrical design of superhydrophobic surfaces. PMID:18479153

Jung, Yong Chae; Bhushan, Bharat



The utility of surface temperature measurements for the remote sensing of surface soil water status  

NASA Technical Reports Server (NTRS)

Experiments carried out on an Avondale loam soil indicated that the thermal inertia concept of soil water content detection is reasonably sound. The volumetric water contents of surface soil layers between 2 and 4 cm thick were found to be linear functions of the amplitude of the diurnal surface soil temperature wave for clear day-night periods. They were also found to be linear functions of the daily maximum value of the surface soil-air-temperature differential. Tests on three additional soils ranging from sandy loam to clay indicated that the relations determined for Avondale loam could not be accurately applied to these other soil types. When the moisture characteristic curves of each soil were used to transform water contents into pressure potentials, however, it was found that soil water pressure potential could be determined without prior knowledge of soil type, and thus its value as a potential soil water status survey tool was significantly enhanced.

Idso, S. B.; Jackson, R. D.; Reginato, R. J.; Schmugge, T. J.



Infiltration of pesticides in surface water into nearby drinking water supply wells  

NASA Astrophysics Data System (ADS)

Drinking water wells are often placed near streams because streams often overly permeable sediments and the water table is near the surface in valleys, and so pumping costs are reduced. The lowering of the water table by pumping wells can reverse the natural flow from the groundwater to the stream, inducing infiltration of surface water to groundwater and consequently to the drinking water well. Many attenuation processes can take place in the riparian zone, mainly due to mixing, biodegradation and sorption. However, if the water travel time from the surface water to the pumping well is too short, or if the compounds are poorly degradable, contaminants can reach the drinking water well at high concentrations, jeopardizing drinking water quality. Here we developed a reactive transport model to evaluate the risk of contamination of drinking water wells by surface water pollution. The model was validated using data of a tracer experiment in a riparian zone. Three compounds were considered: an older pesticide MCPP (Mecoprop) which is mobile and persistent, glyphosate (Roundup), a new biodegradable and strongly sorbed pesticide, and its degradation product AMPA. Global sensitivity analysis using the method of Morris was employed to identify the dominant model parameters. Results showed that the presence of an aquitard and its characteristics (degree of fracturing and thickness), pollutant properties and well depth are the crucial factors affecting the risk of drinking water well contamination from surface water. Global sensitivity analysis results were compared with rank correlation statistics between pesticide concentrations and geological parameters derived from a comprehensive database of Danish drinking water wells. Aquitard thickness and well depth are the most critical parameters in both the model and observed data.

Malaguerra, F.; Albrechtsen, H.; Binning, P. J.



Methamphetamine enhances memory of operantly conditioned respiratory behavior in the snail Lymnaea stagnalis.  


Amphetamines have been used as cognitive enhancers to promote learning and memory. Amphetamines are also drugs of abuse that may promote the initiation of strong memories that ultimately lead to addiction. To understand how methamphetamine (Meth) may be augmenting learning and memory, we chose a relatively simple system, the pond snail, Lymnaea stagnalis. We studied the effects of Meth exposure on the long-term memory (LTM), extinction and reinstatement of operantly conditioned aerial respiratory behavior in Lymnaea. We first determined doses of Meth that would acutely alter respiratory behavior. Next, we measured the impact of training snails in Meth solution or water (control group) using a training procedure that produces LTM (>6 h) in control conditions. Meth exposure impaired the expression of LTM 21 h after two training sessions, but this appeared to be a context-dependent effect only. However, snails exposed to 3.3 mumol l(-1) Meth during training had a decreased rate of extinction of the operantly conditioned memory. We then tested whether this decreased ability of snails to extinguish memory was due to enhanced LTM or impaired extinction of that memory. Snails were operantly conditioned in water and exposed to Meth 16 h after their last trial but 4-5 h prior to extinction. Meth produced an increase rather than a decrease in extinction rate. Thus, Meth impaired extinction only when snails were exposed to Meth during training. Last, we tested the effect of Meth on the ability to form LTM using a single training procedure that is suboptimal for LTM formation. Control snails did not demonstrate LTM, as expected, but pre-exposure of snails to 3.3 micromol l(-1) Meth 24 h prior to the single training session produced LTM 24 h later, indicating that Meth pre-exposure primed snails for LTM formation. Taken together, our studies suggest that LTM is strengthened by Meth such that extinction training is less effective. Lymnaea provides a simple and useful model system to dissect the cellular and/or molecular mechanisms of how Meth may initiate the formation of stronger memories. PMID:20511519

Kennedy, Colin D; Houmes, Stephen W; Wyrick, Katherine L; Kammerzell, Samuel M; Lukowiak, Ken; Sorg, Barbara A



Schistosomes and snails: a molecular encounter.  


Biomphalaria glabrata snails play an integral role in the transmission of Schistosoma mansoni, the causative agent for human schistosomiasis in the Western hemisphere. For the past two decades, tremendous advances have been made in research aimed at elucidating the molecular basis of the snail/parasite interaction. The growing concern that there is no vaccine to prevent schistosomiasis and only one effective drug in existence provides the impetus to develop new control strategies based on eliminating schistosomes at the snail-stage of the life cycle. To elucidate why a given snail is not always compatible to each and every schistosome it encounters, B. glabrata that are either resistant or susceptible to a given strain of S. mansoni have been employed to track molecular mechanisms governing the snail/schistosome relationship. With such snails, genetic markers for resistance and susceptibility were identified. Additionally, differential gene expression studies have led to the identification of genes that underlie these phenotypes. Lately, the role of schistosomes in mediating non-random relocation of gene loci has been identified for the first time, making B. glabrata a model organism where chromatin regulation by changes in nuclear architecture, known as spatial epigenetics, orchestrated by a major human parasite can now be investigated. This review will highlight the progress that has been made in using molecular approaches to describe snail/schistosome compatibility issues. Uncovering the signaling networks triggered by schistosomes that provide the impulse to turn genes on and off in the snail host, thereby controlling the outcome of infection, could also yield new insights into anti-parasite mechanism(s) that operate in the human host as well. PMID:25101114

Knight, Matty; Arican-Goktas, Halime D; Ittiprasert, Wannaporn; Odoemelam, Edwin C; Miller, André N; Bridger, Joanna M



Schistosomes and snails: a molecular encounter  

PubMed Central

Biomphalaria glabrata snails play an integral role in the transmission of Schistosoma mansoni, the causative agent for human schistosomiasis in the Western hemisphere. For the past two decades, tremendous advances have been made in research aimed at elucidating the molecular basis of the snail/parasite interaction. The growing concern that there is no vaccine to prevent schistosomiasis and only one effective drug in existence provides the impetus to develop new control strategies based on eliminating schistosomes at the snail-stage of the life cycle. To elucidate why a given snail is not always compatible to each and every schistosome it encounters, B. glabrata that are either resistant or susceptible to a given strain of S. mansoni have been employed to track molecular mechanisms governing the snail/schistosome relationship. With such snails, genetic markers for resistance and susceptibility were identified. Additionally, differential gene expression studies have led to the identification of genes that underlie these phenotypes. Lately, the role of schistosomes in mediating non-random relocation of gene loci has been identified for the first time, making B. glabrata a model organism where chromatin regulation by changes in nuclear architecture, known as spatial epigenetics, orchestrated by a major human parasite can now be investigated. This review will highlight the progress that has been made in using molecular approaches to describe snail/schistosome compatibility issues. Uncovering the signaling networks triggered by schistosomes that provide the impulse to turn genes on and off in the snail host, thereby controlling the outcome of infection, could also yield new insights into anti-parasite mechanism(s) that operate in the human host as well. PMID:25101114

Knight, Matty; Arican-Goktas, Halime D.; Ittiprasert, Wannaporn; Odoemelam, Edwin C.; Miller, Andre N.; Bridger, Joanna M.



Modeling studies of geothermal systems with a free water surface  

SciTech Connect

A numerical simulator was developed for the modeling of air-steam-water systems. The simulator was applied to various problems involving injection into or production from a geothermal reservoir in hydraulic communication with a shallow free-surface aquifer. First, a one-dimensional column problem is considered and the water level movement during exploitation is studied using different capillary pressure functions. Second, a two-dimensional radial model is used to study and compare reservoir depletion for cases with and without a free-surface aquifer. Finally, the contamination of a shallow free-surface aquifer due to cold water injection is investigated. The primary aim of these studies is to obtain an understanding of the response of a reservoir in hydraulic communication with a unconfined aquifer during exploitation or injection and to determine under which circumstances conventional modeling techniques (fully saturated systems) can be applied to such systems.

Bodvarsson, G.S.; Pruess, K.



Salty Glycerol versus Salty Water Surface Organization: Bromide and Iodide Surface Propensities  

E-print Network

Salty Glycerol versus Salty Water Surface Organization: Bromide and Iodide Surface Propensities: Salty NaBr and NaI glycerol solution interfaces are examined in the OH stretching region using broadband to further understand the VSFG spectroscopic signature. The VSFG spectra of salty glycerol solutions reveal


Thin layer chromatographic analysis of glucose and maltose in estivated Biomphalaria glabrata snails and those infected with Schistosoma mansoni.  


Thin layer chromatography was used to analyze the glucose and maltose concentrations of the digestive gland-gonad complex (DGG) of uninfected-estivated Biomphalaria glabrata snails and estivated B. glabrata patently infected with Schistosoma mansoni. All snails were estivated in a most chamber at a relative humidity of 98+/-1% and a temperature of 23+/-1 degrees C for 14 days. Carbohydrates were extracted from the DGG with 70% aqueous ethanol, and extracts were analyzed on silica gel preadsorbent plates using ethyl acetate-glacial acetic acid-methanol-water (60:15:15:10) mobile phase, alpha-naphthol-sulfuric acid detection reagent, and quantification by densitometry. The concentrations of glucose and maltose were significantly reduced in both uninfected-estivated snails and infected-estivated snails. PMID:17010650

Jarusiewicz, Jamie A; Sherma, Joseph; Fried, Bernard



Detection of Ehrlichia risticii, the Agent of Potomac Horse Fever, in Freshwater Stream Snails (Pleuroceridae: Juga spp.) from Northern California  

PubMed Central

Ehrlichia DNA was identified by nested PCR in operculate snails (Pleuroceridae: Juga spp.) collected from stream water in a northern California pasture in which Potomac horse fever (PHF) is enzootic. Sequencing of PCR-amplified DNA from a suite of genes (the 16S rRNA, groESL heat shock operon, 51-kDa major antigen genes) indicated that the source organism closely resembled Ehrlichia risticii, the causative agent of PHF. The minimum percentage of Juga spp. harboring the organism in the population studied was 3.5% (2 of 57 snails). No ehrlichia DNA was found in tissues of 123 lymnaeid, physid, and planorbid snails collected at the same site. These data suggest that pleurocerid stream snails may play a role in the life cycle of E. risticii in northern California. PMID:9687446

Barlough, Jeffrey E.; Reubel, Gerhard H.; Madigan, John E.; Vredevoe, Larisa K.; Miller, Paul E.; Rikihisa, Yasuko



Microcystins in potable surface waters: toxic effects and removal strategies.  


In freshwater, harmful cyanobacterial blooms threaten to increase with global climate change and eutrophication of surface waters. In addition to the burden and necessity of removal of algal material during water treatment processes, bloom-forming cyanobacteria can produce a class of remarkably stable toxins, microcystins, difficult to remove from drinking water sources. A number of animal intoxications over the past 20 years have served as sentinels for widespread risk presented by microcystins. Cyanobacterial blooms have the potential to threaten severely both public health and the regional economy of affected communities, particularly those with limited infrastructure or resources. Our main objectives were to assess whether existing water treatment infrastructure provides sufficient protection against microcystin exposure, identify available options feasible to implement in resource-limited communities in bloom scenarios and to identify strategies for improved solutions. Finally, interventions at the watershed level aimed at bloom prevention and risk reduction for entry into potable water sources were outlined. We evaluated primary studies, reviews and reports for treatment options for microcystins in surface waters, potable water sources and treatment plants. Because of the difficulty of removal of microcystins, prevention is ideal; once in the public water supply, the coarse removal of cyanobacterial cells combined with secondary carbon filtration of dissolved toxins currently provides the greatest potential for protection of public health. Options for point of use filtration must be optimized to provide affordable and adequate protection for affected communities. PMID:24038121

Roegner, Amber F; Brena, Beatriz; González-Sapienza, Gualberto; Puschner, Birgit



Molecular dynamics studies of water deposition on hematite surfaces  

NASA Astrophysics Data System (ADS)

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.

Kvamme, Bjørn; Kuznetsova, Tatiana; Haynes, Martin



Parametrically excited water surface ripples as ensembles of oscillons  

E-print Network

We show that ripples on the surface of deep water which are driven parametrically by monochromatic vertical vibration represent ensembles of oscillating solitons, or quasi-particles, rather than waves. Horizontal mobility of oscillons determines the broadening of spectral lines and transitions from chaos to regular patterns. It is found that microscopic additions of proteins to water dramatically affect the oscillon mobility and drive transitions from chaos to order. The shape of the oscillons in physical space determines the shape of the frequency spectra of the surface ripple.

Shats, Michael; Punzmann, Horst



Regularity of traveling free surface water waves with vorticity  

E-print Network

We prove real analyticity of all the streamlines, including the free surface, of a gravity- or capillary-gravity-driven steady flow of water over a flat bed, with a H\\"{o}lder continuous vorticity function, provided that the propagating speed of the wave on the free surface exceeds the horizontal fluid velocity throughout the flow. Furthermore, if the vorticity possesses some Gevrey regularity of index $s$, then the stream function admits the same Gevrey regularity throughout the fluid domain; in particular if the Gevrey index $s$ equals to 1, then we obtain analyticity of the stream function. The regularity results hold for both periodic and solitary water waves.

Li, Wei-Xi



Activation of the immune defence of the freshwater snail Lymnaea stagnalis by different immune elicitors.  


Understanding the outcomes of host-parasite interactions in nature is in high demand as parasites and pathogens are important for several ecological and evolutionary processes. Ecological immunology (ecoimmunology) has a key role in reaching this goal because immune defence is the main physiological barrier against infections. To date, ecoimmunological studies largely lean on measuring constitutive immune defences (components of defence that are always active). However, understanding the role of inducible components of immune function is important as the immune system is largely an inducible defence. Measuring such defences can be complicated as different parasites may activate different immune cascades, and expression of different immune traits may not be independent. We examined the suitability of different immune activation techniques for the freshwater snail Lymnaea stagnalis. By experimentally challenging snails with different immune elicitors [injection with snail saline (i.e. wounding), lyophilized Escherichia coli cells, lyophilized Micrococcus lysodeikticus cells, healthy snail gonad, and trematode-infected snail gonad; maintenance in microorganism-enriched water] and measuring phenoloxidase-like and antibacterial activity of their haemolymph, we found increased immune activity against some immune elicitors, but also decreased activity. Our findings suggest potentially complicated relationships among immune traits, and propose suitable techniques for ecological studies in this study system. PMID:23842628

Seppälä, Otto; Leicht, Katja



Finding and recognition of the snail intermediate hosts by 3 species of echinostome cercariae.  


Finding and recognition of snail second intermediate hosts was studied in cercariae of 3 echinostome species. The cercariae of the 3 species accumulated in snail-conditioned water (SCW) with 2 types of orientation mechanisms and responded to different small molecular weight ( < 500 Da) components of SCW. Pseudechinoparyphium echinatum and Echinostoma revolutum cercariae returned by swimming an arc, when swimming in decreasing concentration gradients of SCW (turn-back swimming). The stimulating cues of SCW were identified as hydrophilic organic molecules, probably possessing amino groups. Amino acids contributed to the attractivity of SCW, at least in P. echinatum, but they could not account for the complete attractivity of SCW. Hypoderaeum conoideum were directed chemotactically and swam along increasing concentration gradients of small peptides within SCW, but in decreasing SCW gradients they showed no turn-back swimming. Chemotactic orientation in H. conoideum only started 1 h after emission, which may assist the cercariae to leave the immediate area of their first intermediate host snails and to disperse. Attachments occurred specifically to snail hosts in the 3 species and were stimulated by macromolecular mucus compounds, probably mainly by viscoelastic properties of the mucus. The results of this study show, that host-finding mechanisms and the stimulating host cues of snail invading echinostome cercariae differ considerably from those of schistosome miracidia. PMID:7885732

Haas, W; Körner, M; Hutterer, E; Wegner, M; Haberl, B



Using soil surface gray level to determine surface soil water content  

Microsoft Academic Search

How to determine surface soil water content (SWC) quickly and accurately is fundamental in studying eco-hydrological processes\\u000a and their modeling. Here we use laboratory experiments to determine surface SWC using soil surface gray level (SGL) values.\\u000a A negatively exponential relationship exists between SGL and SWC, i.e., SGL increases with the decrease of SWC. SGL can be\\u000a estimated based on initial

YuanJun Zhu; YunQiang Wang; MingAn Shao



Surface catalysis of water oxidation by the blue ruthenium dimer.  


Single-electron activation of multielectron catalysis has been shown to be viable in catalytic water oxidation with stepwise proton-coupled electron transfer, leading to high-energy catalytic precursors. For the blue dimer, cis,cis-[(bpy)(2)(H(2)O)Ru(III)ORu(III)(H(2)O)(bpy)(2)](4+), the first well-defined molecular catalyst for water oxidation, stepwise 4e(-)/4H(+) oxidation occurs to give the reactive precursor [(O)Ru(V)ORu(V)(O)](4+). This key intermediate is kinetically inaccessible at an unmodified metal oxide surface, where the only available redox pathway is electron transfer. We report here a remarkable surface activation of indium-tin oxide (In(2)O(3):Sn) electrodes toward catalytic water oxidation by the blue dimer at electrodes derivatized by surface phosphonate binding of [Ru(4,4'-((HO)(2)P(O)CH(2))(2)bpy)(2)(bpy)](2+). Surface binding dramatically improves the rate of surface oxidation of the blue dimer and induces water oxidation catalysis. PMID:20377256

Jurss, Jonah W; Concepcion, Javier C; Norris, Michael R; Templeton, Joseph L; Meyer, Thomas J



Surface charge of electrosprayed water nanodroplets: a molecular dynamics study.  


Aqueous nanodroplets that contain excess charge carriers play a central role during the electrospray ionization (ESI) process. An interesting question concerns the charge carrier location in these systems. In analogy to the behavior of metallic conductors, it is often assumed that excess ions are confined to a thin layer on the droplet surface. However, it is unclear whether simple electrostatic arguments adequately reflect the nanodroplet behavior. In particular, most ions tend to be heavily solvated, such that placing them at the liquid/vapor interface would be enthalpically unfavorable. In this work, molecular dynamics simulations are used to study the properties of Na(+)-containing water nanodroplets close to the Rayleigh limit. In apparent violation of the surface charge paradigm, it is found that the ions reside inside the droplet. Electrostatic mapping reveals that all of the excess charge is nonetheless located on the surface. This conundrum is resolved by considering the effects of orientational water polarization. Buried Na(+) ions cause large-scale dipole ordering that extends all the way to the droplet periphery. Here, the positive ends of water dipoles preferentially point into the vapor phase. These half-dipoles in the outermost droplet layers assume the role of surface charge, while solvation effectively neutralizes Na(+) ions in the interior. Overall, our data reaffirm the validity of the surface charge paradigm for ESI nanodroplets, albeit with the caveat that this paradigm does NOT require charge carriers (ions) to be located at the water/vapor interface. PMID:20698694

Ahadi, Elias; Konermann, Lars



Sensors and OBIA synergy for operational monitoring of surface water  

Microsoft Academic Search

This contribution will focus on combining Object Based Image Analysis (i.e. OBIA with e-Cognition 8) and recent sensors (i.e. Spot 5 XS, Pan and ALOS Prism, Avnir2, Palsar) to address the technical feasibility for an operational monitoring of surface water. Three cases of river meandering (India), flood mapping (Nepal) and dam's seasonal water level monitoring (Morocco) using recent sensors will

Eric Masson; Lucas Thenard



Diffuse Surface Water Pollution: Driving Factors for Different Geoclimatic Regions  

Microsoft Academic Search

The quantification of point and non-point losses of Nitrogen (N) and Phosphorus (P) to surface waters is currently a major\\u000a issue for the implementation of Environmental Directives, such as the Water Framework Directive in Europe. However, the drivers\\u000a behind nutrient pollution are location specific and are affected by regional hydroclimatic and geomorphological characteristics.\\u000a In this study the river basin model

Yiannis Panagopoulos; Christos Makropoulos; Maria Mimikou


Seasonal and artificially elevated temperatures influence bioenergetic allocation patterns in the common pond snail, Physella virgata.  


Allocation of organic carbon (OC) to primary energetic pathways was estimated under seasonal and artificially elevated ambient temperatures for a field population of a freshwater pulmonate snail, Physella virgata. Allocation to respiration increased with temperature. Snails allocated most assimilated OC to reproduction within their natural temperature range (15 degrees -35 degrees C), where assimilation efficiencies remained relatively stable at 25%-35%. However, in artificially heated waters exceeding 35 degrees C, declining assimilation rates and increasing respiratory demands inhibited allocation to reproduction and growth. At the species' 40 degrees C upper thermal limit, assimilation efficiencies fell below 10%, while average consumption levels more than doubled relative to snails unaffected by the thermal effluent. Ambient temperature substantially influenced OC allocation over P. virgata's natural temperature range and negatively affected growth and reproduction at temperatures approaching or exceeding maximum natural levels. PMID:15095239

Britton, David K; McMahon, Robert F



The ecology of vector snail habitats and mosquito breeding-places  

PubMed Central

The ecology of freshwater snails—in particular those which act as intermediate hosts of bilharziasis—is reviewed in the light of the much more extensive knowledge available on the breeding-places of anopheline mosquitos. Experimental ecological methods are recommended for the field and laboratory investigation of a number of common problems involved in the study of snail habitats and mosquito breeding-places. Among the environmental factors discussed are temperature, oxygen concentration, water movement, pollution and salinity. Sampling methods for estimating populations of both snails and mosquito larvae are also described. An attempt is made to show how malacologists and entomologists alike would benefit from improved facilities for keeping abreast of general developments in the wider field of freshwater ecology. PMID:13596888

Muirhead-Thomson, R. C.



Groundwater - surface water interactions in the Ayeyarwady river delta, Myanmar  

NASA Astrophysics Data System (ADS)

Groundwater is widely used as a water resource in the Ayeyarwady River delta. But, Groundwater has some chemical problem in part of the area. To use safety groundwater for health, it is important to make clear the actual conditions of physical and chemical characteristics of groundwater in this delta. Besides, Ayeyarwady River delta has remarkable wet and dry season. Surface water - groundwater interaction is also different in each season, and it is concerned that physical and chemical characteristics of groundwater is affected by the flood and high waves through cyclone or monsoon. So, it is necessary to research a good aquifer distribution for sustainable groundwater resource supply. The purposes of this study are evaluate to seasonal change of groundwater - surface water interactions, and to investigate the more safety aquifer to reduce the healthy risk. Water samples are collected at 49 measurement points of river and groundwater, and are analyzed dissolved major ions and oxygen and hydro-stable isotope compositions. There are some groundwater flow systems and these water qualities are different in each depth. These showed that physical and chemical characteristics of groundwater are closely related to climatological, geomorphogical, geological and land use conditions. At the upper Alluvium, groundwater quality changes to lower concentration in wet season, so Ayeyarwady River water is main recharge water at this layer in the wet season. Besides, in the dry season, water quality is high concentration by artificial activities. Shallower groundwater is affected by land surface conditions such as the river water and land use in this layer. At lower Alluvium, Arakan and Pegu mountains are main recharge area of good water quality aquifers. Oxygen18 value showed a little affected by river water infiltration in the wet season, but keep stable good water quality through the both seasons. In the wet season, the same groundwater exists and water quality changes through dry to wet season at the upper Irrawaddy formation which is distributed beneath the lower Alluvium. Local groundwater flow system which is not affected by river water in the wet season is distributed at the central delta. Land use changes from tropical forest to plantation at the Arakan mountains. So, it is necessary to monitor the physical and chemical characteristics change of groundwater.

Miyaoka, K.; Haruyama, S.; Kuzuha, Y.; Kay, T.



Water and Carbon Dioxide Adsorption at Olivine Surfaces  

SciTech Connect

Plane-wave density functional theory (DFT) calculations were performed to simulate water and carbon dioxide adsorption at the (010) surface of five olivine minerals, namely, forsterite (Mg2SiO4), calcio-olivine (Ca2SiO4), tephroite (Mn2SiO4), fayalite (Fe2SiO4), and Co-olivine (Co2SiO4). Adsorption energies per water molecule obtained from energy minimizations varied from -78 kJ mol-1 for fayalite to -128 kJ mol-1 for calcio-olivine at sub-monolayer coverage and became less exothermic as coverage increased. In contrast, carbon dioxide adsorption energies at sub-monolayer coverage ranged from -20 kJ mol-1 for fayalite to -59 kJ mol-1 for calcio-olivine. Therefore, the DFT calculations show a strong driving force for carbon dioxide displacement by water at the surface of all olivine minerals in a competitive adsorption scenario. Additionally, adsorption energies for both water and carbon dioxide were found to be more exothermic for the alkaline-earth (AE) olivines than for the transition-metal (TM) olivines and to not correlate with the solvation enthalpies of the corresponding divalent cations. However, a correlation was obtained with the charge of the surface divalent cation indicating that the more ionic character of the AE cations in the olivine structure relative to the TM cations leads to greater interactions with adsorbed water and carbon dioxide molecules at the surface and thus more exothermic adsorption energies for the AE olivines. For calcio-olivine, which exhibits the highest divalent cation charge of the five olivines, ab initio molecular dynamics simulations showed that this effect leads both water and carbon dioxide to react with the surface and form hydroxyl groups and a carbonate-like species, respectively.

Kerisit, Sebastien N.; Bylaska, Eric J.; Felmy, Andrew R.




Microsoft Academic Search

ABSTRACT During the spring of 2000 and 2001, the Blue Cypress Marsh Conservation Area and the Blue Cypress Water Management Area (collectively referred to as the BCM) within the watershed of the upper St. Johns River were surveyed to determine the breeding activity of Snail Kites (Rostrhamus sociabilis plumbeus). A total of six nests were located within this area in

Zachariah C. Welch; Wiley M. Kitchens



Roles of surface water areas for water and solute cycle in Hanoi city, Viet Nam  

NASA Astrophysics Data System (ADS)

Hanoi city, the capital of Viet Nam, has developed beside the Red river. Recent rapid urbanization of this city has reduced a large number of natural water areas such as lakes, ponds and canals not only in the central area but the suburban area. Contrary, the urbanization has increased artificial water areas such as pond for fish cultivation and landscaping. On the other hand, the urbanization has induced the inflow of waste water from households and various kinds of factories to these water areas because of delay of sewerage system development. Inflow of the waste water has induced eutrophication and pollution of these water areas. Also, there is a possibility of groundwater pollution by infiltration of polluted surface water. However, the role of these water areas for water cycle and solute transport is not clarified. Therefore, this study focuses on the interaction between surface water areas and groundwater in Hanoi city to evaluate appropriate land development and groundwater resource management. We are carrying out three approaches: a) understanding of geochemical characteristics of surface water and groundwater, b) monitoring of water levels of pond and groundwater, c) sampling of soil and pond sediment. Correlation between d18O and dD of precipitation (after GNIP), the Red River (after GNIR) and the water samples of this study showed that the groundwater is composed of precipitation, the Red River and surface water that has evaporation process. Contribution of the surface water with evaporation process was widely found in the study area. As for groundwater monitoring, the Holocene aquifers at two sites were in unconfined condition in dry season and the groundwater levels in the aquifer continued to increase through rainy season. The results of isotopic analysis and groundwater level monitoring showed that the surface water areas are one of the major groundwater sources. On the other hand, concentrations of dissolved Arsenic (filtered by 0.45um) in the pore water of the pond sediments were much higher than the pond water and closed to that of groundwater. Also, other metal elements showed the same trend. This result suggested that Arsenic and other metal elements recharged to these ponds is probably adsorbed and removed by sediments (including organic matters). That is, pond sediment plays an important role for solute transport as a filter of Arsenic and metal elements. The results of this study strongly suggest that the natural and artificial surface water areas have important roles for water cycle and solute transport in Hanoi city. Although the number of the natural water areas is decreasing, dredging of artificial water areas increases the infiltration from the surface to aquifers. Therefore, qualitative and quantitative preservation of the surface water areas is important for conservation of groundwater environment and contribute to sustainable groundwater management in Hanoi city.

Hayashi, Takeshi; Kuroda, Keisuke; Do Thuan, An; Tran Thi Viet, Nga; Takizawa, Satoshi



Theoretical Study of Sodium-Water Surface Reaction Mechanism  

NASA Astrophysics Data System (ADS)

Computational study of the sodium-water reaction at the gas (water) - liquid (sodium) interface has been carried out using the ab initio (first-principle) method. A possible reaction channel has been identified for the stepwise OH bond dissociations of a single water molecule. The energetics including the binding energy of a water molecule on the sodium surface, the activation energies of the bond cleavages, and the reaction energies, have been evaluated, and the rate constants of the first and second OH bond-breakings have been compared. It was found that the estimated rate constant of the former was much larger than the latter. The results are the basis for constructing the chemical reaction model used in a multi-dimensional sodium-water reaction code, SERAPHIM, being developed by Japan Atomic Energy Agency (JAEA) toward the safety assessment of the steam generator (SG) in a sodium-cooled fast reactor (SFR).

Kikuchi, Shin; Kurihara, Akikazu; Ohshima, Hiroyuki; Hashimoto, Kenro

294 The State Water Resources Control Board's Surface Water Ambient Monitoring  

E-print Network Overview The State Water Resources Control Board's Surface Water Fish The survey identified high concentrations of contaminants in a few areas, and widespread moderate Control Board threshold for methylmercury in tissue that is being used for identification of impaired



EPA Science Inventory

The National Water-Quality Assessment (NAWQA) Program is designed to describe the status and trends in the quality of the Nations ground- and surface-water resources and to provide a sound understanding of the natural and human factors that affect the quality of these resources. ...


Probing the hydration water diffusion of macromolecular surfaces and interfaces  

Microsoft Academic Search

We probe the translational dynamics of the hydration water surrounding the macromolecular surfaces of selected polyelectrolytes, lipid vesicles and intrinsically disordered proteins with site specificity in aqueous solutions. These measurements are made possible by the recent development of a new instrumental and methodological approach based on Overhauser dynamic nuclear polarization (DNP)-enhanced nuclear magnetic resonance (NMR) spectroscopy. This technique selectively amplifies

Julia H. Ortony; Chi-Yuan Cheng; John M. Franck; Ravinath Kausik; Anna Pavlova; Jasmine Hunt; Songi Han



Uranium in US surface, ground, and domestic waters  

SciTech Connect

The report Uranium in US Surface, Ground, and Domestic Waters comprises four volumes. Volumes 2, 3, and 4 contain data characterizing the location, sampling date, type, use, and uranium concentrations of 89,994 individual samples presented in tabular form. The tabular data in volumes 2, 3, and 4 are summarized in volume 1 in narrative form and with maps and histograms.

Drury, J.S.; Reynolds, S.; Owen, P.T.; Ross, R.H.; Ensminger, J.T.



Uranium in US surface, ground, and domestic waters  

SciTech Connect

The report Uranium in US Surface, Ground, and Domestic Waters, comprises four volumes. Volumes 2, 3, and 4 contain data characterizing the location, sampling date, type, use, and uranium concentrations of 89,994 individual samples presented in tabular form. The tabular data in volumes 2, 3, and 4 are summarized in volume 1 in narrative form and with maps and histograms.

Drury, J.S.; Reynolds, S.; Owen, P.T.; Ross, R.H.; Ensminger, J.T.



Model of surface water quality Valerian Antohe1  

E-print Network

and rarely realized. Mathematical model of the evolution of the Danube surface water quality parameters, the imagine of the complex system of Danube River which live like a human entity, permanently monitored, [1]. 2 Study area Study area is located in the terminal of the Danube river basin, in contact with Delta

Hinze, Thomas



EPA Science Inventory

During the past decade significant interest has developed in the influence of photochemical reactions on biogeochemical cycles in surface waters of lakes and the sea. A major portion of recent research on these photoreactions has focused on the colored component of dissolved org...



EPA Science Inventory

Recent studies are reviewed to provide a comprehensive volume on state-of-the-art formulations used in surface water quality modeling along with accepted values for rate constants and coefficients. Topics covered include system geometric representation (spatial and temporal), phy...


SWOT: The Surface Water & Ocean Topography Satellite Mission  

E-print Network

SWOT: The Surface Water & Ocean Topography Satellite Mission Doug Alsdorf Byrd Polar Research Arctic Lakes, Science, 2005 Arctic lakes are losing storage, despite a slight increase in precipitation of Oceans ECCO-2 MIT JPL ocean current model Although altimetry data have significantly advanced the study


The stability of glazed silicon surfaces to water attack  

Microsoft Academic Search

IBM has developed a glassing technology for the passivation of transistors and diodes. For effective surface protection, the glass should have long-term stability to ambient attack, particularly moisture attack. Since it is difficult to evaluate all glasses under moderate moisture conditions for extended periods, several accelerated tests for determining the stability of glasses to water and humidity were compared. Although

W. A. Pliskin




E-print Network

WATER-IMMERSION DEEP-SUBWAVELENGTH SURFACE PLASMON VIRTUAL PROBES QIAN WANG Optoelectronics is as small as 0=5:5. Such deep-subwavelength sized plasmonic virtual probe may lead to many potential plasmon polariton; virtual probe; deep-subwavelength. Journal of Molecular and Engineering Materials Vol

Zheludev, Nikolay


Groundwater-Surface Water Exchange as a Hydrologic and Water Quality Buffer  

Microsoft Academic Search

The complex interactions of surface water and groundwater are gaining increasing recognition as an outstanding research need. Specifically, the role of transition zones between alpine headwaters and valley bottom river\\/lake\\/wetland systems, common across mountain-valley landscapes, in controlling stream flow quantity, timing, and water quality are poorly understood. In many valleys, streams change in both space and time from gaining water

T. P. Covino; B. L. McGlynn; R. S. Sojda



Occurrence of pharmaceuticals and hormones in drinking water treated from surface waters  

Microsoft Academic Search

The levels of a wide variety of pharmaceuticals and hormones, in source and potable-water supplies of French drinking water\\u000a treatment plants, were assessed. In surface waters, 27 of the 51 target compounds were determined at least once. Paracetamol,\\u000a salicylic acid and carbamazepine were quantified in more than 80% of samples. The highest concentration of 71 ng\\/L was observed\\u000a for paracetamol. Twelve other substances

Emmanuelle Vulliet; Cécile Cren-Olivé; Marie-Florence Grenier-Loustalot



Transport and Fate of Nitrate at the Ground Water-Surface Water Interface  

Microsoft Academic Search

We investigated the transport and fate of nitrate within the ground water-surface water interface of 5 agriculturally dominated streams across the United States in Maryland, Indiana, Nebraska, California, and Washington. Water samples were collected from the streambed at depths ranging from 0.3 to 3 m, in 2-5 transects along the stream, and at 3-5 points across each transect. At 2

L. J. Puckett; H. I. Essaid; C. Zamora; J. T. Wilson; H. M. Johnson; J. R. Vogel



Reproduction and demography of the Florida Everglade (Snail) Kite  

USGS Publications Warehouse

An 18-year study of reproduction and survival of the Florida Everglade (Snail) Kite (Rostrhamus sociabilis plumbeus) has revealed the following: extremely poor nesting success (only 13.6% of nests found at the nest-building stage successful); extremely long breeding seasons (some reproductive activity in almost all months in good years); frequent multiple brooding and frequent multiple brooding and frequent renesting after failure; low egg hatchability (81%); high failure rates due to nest collapse, desertion, and predation; extremely high survival of juveniles and adults under good water conditions; and high vulnerability to drought due to near total dependency on a single species of drought-sensitive snail for food. Despite low nesting success, the species has increased rapidly under good conditions, mainly because of multiple nesting attempts within long breeding seasons and high survival rates of free-flying birds. Nesting success varied significantly between regions and nest substrates, but not as a function of seasons or solitary vs. colonial nesting. While nesting success was reduced in low water years, this effect was at least partly due to heavy use of poor nest substrates under such conditions. Clutch size and numbers of young per successful nest varied with regions, but not as a function of seasons or water levels. The effects of coloniality on clutch size and numbers of young were inconsistent. Significant effects of nest-substrate types on clutch size and numbers of young were apparently artifacts of substrate differences between regions.

Snyder, N.F.R.; Beissinger, S.R.; Chandler, R.E.



Phosphorus: a rate limiting nutrient in surface waters.  


Phosphorus is an essential element for all life forms. It is a mineral nutrient. Orthophosphate is the only form of P that autotrophs can assimilate. Extracellular enzymes hydrolyze organic forms of P to phosphate. Eutrophication is the over-enrichment of surface waters with mineral nutrients. The results are excessive production of autotrophs, especially algae and cyanobacteria. This high productivity leads to high bacterial populations and high respiration rates, leading to hypoxia or anoxia in poorly mixed bottom waters and at night in surface waters during calm, warm conditions. Low dissolved oxygen causes the loss of aquatic animals and the release of many materials normally bound to bottom sediments, including various forms of P. This release of P reinforces the eutrophication. Excessive concentrations of P is the most common cause of eutrophication in freshwater lakes, reservoirs, streams, and in the headwaters of estuarine systems. In the ocean, N is believed to usually be the key mineral nutrient controlling primary production. Estuaries and continental shelf waters are a transition zone, in which excessive P and N create problems. It is best to measure and regulate total P inputs to whole aquatic ecosystems, but for an easy assay it is best to measure total P concentrations, including particulate P, in surface waters or N:P atomic ratios in phytoplankton. PMID:10228963

Correll, D L



Numerical simulation of free water surface in pump intake  

NASA Astrophysics Data System (ADS)

The purpose of this paper is to verify the volume of fluid (VOF) method for simulating the free water surface flow in pump intake. With the increasing computer power, VOF method has been becoming a more flexible and accurate choice to replace the conventional fixed water surface method, because it does not require assumptions on the nature of air-water interface. Two examples are presented in this paper. The first example is presented for simulating the growth of air-entrained vortices. LES (Large Eddy Simulation) model, instead of RANS (Reynolds averaged Navier-Stokes) turbulence model, is used to capture the peak of circular velocity around the vortex core. Numerical result shows good agreement with the benchmark experiment carried by the Turbomachinery Society of Japan. The second example predicts the flow rate distribution in the pump intake consisting of one opened and two closed channels. VOF result is compared with the conventional fixed water surface method assuming free-slip boundary condition on the fluid interface. The difference of flow pattern in the opened channel indicates that numerical flow field is affected remarkably by the setup of boundary condition at air-water interface.

Zhao, L. J.; Nohmi, M.



Appearance of aldehydes in the surface layer of lake waters.  


The paper presents results concerning the changes in the content of aldehydes in samples of lake water collected near the lake surface. The study of lake waters was undertaken to explain which physicochemical parameters of the environment have the greatest influence on the level of aldehydes, which of the aldehydes are most often met in surface water and in what concentrations. We observed that formaldehyde, acetaldehyde, propanal, glyoxal, methylglyoxal and acetone were commonly present in surface water samples, while semi-volatile and poorly soluble aldehydes such as nonanal and decanal were observed seasonally. The contents of total aldehydes varied in a wide range, from 55 to 670 ?g/l, and the concentration of total organic carbon varied significantly from 3 to 18 mg /l, but there was no evident correlation between them in all of samples. The total content of aldehydes did not depend on the meteorological parameters such as air temperature, UV radiation and ozone concentration; however, it was noted that the level of carbonyl concentration is related to the period of intense precipitation: in the period of very low precipitations, the highest contents of total aldehydes were determined in all of the water samples, and in the periods of intense precipitations, the content of total aldehydes was drastically smaller. PMID:24671617

D?browska, Agata; Nawrocki, Jacek; Szel?g-Wasielewska, El?bieta



Snail1 Expression Is Required for Sarcomagenesis12  

PubMed Central

Snail1 transcriptional repressor is a major inducer of epithelial-to mesenchymal transition but is very limitedly expressed in adult animals. We have previously demonstrated that Snail1 is required for the maintenance of mesenchymal stem cells (MSCs), preventing their premature differentiation. Now, we show that Snail1 controls the tumorigenic properties of mesenchymal cells. Increased Snail1 expression provides tumorigenic capabilities to fibroblastic cells; on the contrary, Snail1 depletion decreases tumor growth. Genetic depletion of Snail1 in MSCs that are deficient in p53 tumor suppressor downregulates MSC markers and prevents the capability of these cells to originate sarcomas in immunodeficient SCID mice. Notably, an analysis of human sarcomas shows that, contrarily to epithelial tumors, these neoplasms display high Snail1 expression. This is particularly clear for undifferentiated tumors, which are associated with poor outcome. Together, our results indicate a role for Snail1 in the generation of sarcomas. PMID:24947186

Alba-Castellon, Lorena; Batlle, Raquel; Franci, Clara; Fernandez-Acenero, Maria J.; Mazzolini, Rocco; Pena, Raul; Loubat, Jordina; Alameda, Francesc; Rodriguez, Rufo; Curto, Josue; Albanell, Joan; Munoz, Alberto; Bonilla, Felix; Ignacio Casal, J.; Rojo, Federico; Garcia de Herreros, Antonio



INTRODUCTION Embryos of the freshwater common pond snail Lymnaea stagnalis  

E-print Network

4092 INTRODUCTION Embryos of the freshwater common pond snail Lymnaea stagnalis complete direct retention (Baldwin, 1935). Metamorphosis and shell formation have been observed for Lymnaea palustris (Morrill, 1982), L. stagnalis (Ebanks et al., 2010) and another freshwater pulmonate snail Biomphalaria

Grosell, Martin


Water-Mediated Proton Hopping on an Iron Oxide Surface  

SciTech Connect

The diffusion of hydrogen atoms across solid oxide surfaces is often assumed to be accelerated by the presence of water molecules. Here we present a high-resolution, high-speed scanning tunneling microscopy (STM) study of the diffusion of H atoms on an FeO thin film. STM movies directly reveal a water-mediated hydrogen diffusion mechanism on the oxide surface at temperatures between 100 and 300 kelvin. Density functional theory calculations and isotope-exchange experiments confirm the STM observations, and a proton-transfer mechanism that proceeds via an H3O+-like transition state is revealed. This mechanism differs from that observed previously for rutile TiO2(110), where water dissociation is a key step in proton diffusion.

Merte, L. R.; Peng, Guowen; Bechstein, Ralf; Rieboldt, Felix; Farberow, Carrie A.; Grabow, Lars C.; Kudernatsch, Wilhelmine; Wendt, Stefen; Laegsgaard, E.; Mavrikakis, Manos; Besenbacher, Fleming



Water-mediated proton hopping on an iron oxide surface.  


The diffusion of hydrogen atoms across solid oxide surfaces is often assumed to be accelerated by the presence of water molecules. Here we present a high-resolution, high-speed scanning tunneling microscopy (STM) study of the diffusion of H atoms on an FeO thin film. STM movies directly reveal a water-mediated hydrogen diffusion mechanism on the oxide surface at temperatures between 100 and 300 kelvin. Density functional theory calculations and isotope-exchange experiments confirm the STM observations, and a proton-transfer mechanism that proceeds via an H(3)O(+)-like transition state is revealed. This mechanism differs from that observed previously for rutile TiO(2)(110), where water dissociation is a key step in proton diffusion. PMID:22605771

Merte, Lindsay R; Peng, Guowen; Bechstein, Ralf; Rieboldt, Felix; Farberow, Carrie A; Grabow, Lars C; Kudernatsch, Wilhelmine; Wendt, Stefan; Lægsgaard, Erik; Mavrikakis, Manos; Besenbacher, Flemming



Relationship between landscape characteristics and surface water quality.  


The effects of landscape characteristics on surface water quality were evaluated in terms of land-use condition, soil type and slope. The case area, the Chichiawan stream in the Wulin catchment in Taiwan, is Formosan landlocked salmon's natural habitat. Due to the agriculture behavior and mankind's activities, the water and environmental quality has gradually worsened. This study applied WinVAST model to predict hydrological responses and non-point source pollution (NPSP) exports in the Wulin catchment. The land-use condition and the slope of land surface in a catchment are major effect factors for watershed responses, including flows and pollutant exports. This work discussed the possible variation of watershed responses induced by the change of land-use condition, soil type and slope, etc. The results show that hydrological responses are highly relative to the value of Curve Number (CN); Pollutant exports have large relation to the average slope of the land surface in the Wulin catchment. PMID:18185979

Chang, C L; Kuan, W H; Lui, P S; Hu, C Y



Flow boiling of water on nanocoated surfaces in a microchannel  

E-print Network

Experiments were performed to study the effects of surface wettability on flow boiling of water at atmospheric pressure. The test channel is a single rectangular channel 0.5 mm high, 5 mm wide and 180 mm long. The mass flux was set at 100 kg/m2 s and the base heat flux varied from 30 to 80 kW/m2. Water enters the test channel under subcooled conditions. The samples are silicone oxide (SiOx), titanium (Ti), diamond-like carbon (DLC) and carbon-doped silicon oxide (SiOC) surfaces with static contact angles of 26{\\deg}, 49{\\deg}, 63{\\deg} and 103{\\deg}, respectively. The results show significant impacts of surface wettability on heat transfer coefficient.

Phan, Hai Trieu; Marty, Philippe; Colasson, Stéphane; Gavillet, Jérôme



Cholesterol enhances surface water diffusion of phospholipid bilayers  

NASA Astrophysics Data System (ADS)

Elucidating the physical effect of cholesterol (Chol) on biological membranes is necessary towards rationalizing their structural and functional role in cell membranes. One of the debated questions is the role of hydration water in Chol-embedding lipid membranes, for which only little direct experimental data are available. Here, we study the hydration dynamics in a series of Chol-rich and depleted bilayer systems using an approach termed 1H Overhauser dynamic nuclear polarization (ODNP) NMR relaxometry that enables the sensitive and selective determination of water diffusion within 5-10 Å of a nitroxide-based spin label, positioned off the surface of the polar headgroups or within the nonpolar core of lipid membranes. The Chol-rich membrane systems were prepared from mixtures of Chol, dipalmitoyl phosphatidylcholine and/or dioctadecyl phosphatidylcholine lipid that are known to form liquid-ordered, raft-like, domains. Our data reveal that the translational diffusion of local water on the surface and within the hydrocarbon volume of the bilayer is significantly altered, but in opposite directions: accelerated on the membrane surface and dramatically slowed in the bilayer interior with increasing Chol content. Electron paramagnetic resonance (EPR) lineshape analysis shows looser packing of lipid headgroups and concurrently tighter packing in the bilayer core with increasing Chol content, with the effects peaking at lipid compositions reported to form lipid rafts. The complementary capability of ODNP and EPR to site-specifically probe the hydration dynamics and lipid ordering in lipid membrane systems extends the current understanding of how Chol may regulate biological processes. One possible role of Chol is the facilitation of interactions between biological constituents and the lipid membrane through the weakening or disruption of strong hydrogen-bond networks of the surface hydration layers that otherwise exert stronger repulsive forces, as reflected in faster surface water diffusivity. Another is the concurrent tightening of lipid packing that reduces passive, possibly unwanted, diffusion of ions and water across the bilayer.

Cheng, Chi-Yuan; Olijve, Luuk L. C.; Kausik, Ravinath; Han, Songi



Diminished Mercury Emission From Water Surfaces by Duckweed (Lemna minor)  

NASA Astrophysics Data System (ADS)

Aquatic plants of the family Lemnaceae (generally referred to as duckweeds) are a widely distributed type of floating vegetation in freshwater systems. Under suitable conditions, duckweeds form a dense vegetative mat on the water surface, which reduces light penetration into the water column and decreases the amount of exposed water surface. These two factors would be expected to reduce mercury emission by limiting a) direct photoreduction of Hg(II), b) indirect reduction via coupled DOC photooxidation-Hg(II) reduction, and c) gas diffusion across the water-air interface. Conversely, previous studies have demonstrated transpiration of Hg(0) by plants, so it is therefore possible that the floating vegetative mat would enhance emission via transpiration of mercury vapor. The purpose of this experiment was to determine whether duckweed limits mercury flux to the atmosphere by shading and the formation of a physical barrier to diffusion, or whether it enhances emission from aquatic systems via transpiration of Hg(0). Deionized water was amended with mercury to achieve a final concentration of approximately 35 ng/L and allowed to equilibrate prior to the experiment. Experiments were conducted in rectangular polystyrene flux chambers with measured UV-B transmittance greater than 60% (spectral cutoff approximately 290 nm). Light was able to penetrate the flux chamber from the sides as well as the top throughout the experiment, limiting the effect of shading by duckweed on the water surface. Flux chambers contained 8L of water with varying percent duckweed cover, and perforated plastic sheeting was used as an abiotic control. Exposures were conducted outside on days with little to no cloud cover. Real time mercury flux was measured using atomic absorption (Mercury Instruments UT-3000). Total solar and ultraviolet radiation, as well as a suite of meteorological parameters, were also measured. Results indicate that duckweed diminishes mercury emission from the water surface as compared to open water controls. Decreases in emission rate varied linearly with percent duckweed cover, with lower fluxes occurring at higher percent cover. Mercury flux in the duckweed treatments as compared to open water treatments decreased from 17% in the lowest percent cover treatment to 67% in the highest percent cover treatment. The observed decrease in mercury emission suggests that duckweed limits emission via the formation of a physical barrier to diffusion.

Wollenberg, J. L.; Peters, S. C.



Hydraulic exchange between a coral reef and surface sea water  

SciTech Connect

Hydraulic exchange between overlying sea water and the internal structure of a patch reef in Kaneohe Bay, Oahu, Hawaii, was studied with an array of wells, 1, 2, and 4 m deep. Two natural chemical tracers, radon, and salinity, were used to calculate the exchange rate between surface sea water and reef interstitial waters. Dissolved radon concentrations are substantially higher in interstitial waters than is surface water. The degree of radon enrichment is quantitatively related to the time elapsed since interstitial water had equilibrated with the atmosphere. Residence time estimates are 1-40 days, with deeper wells having slower exchange. The average residence time for 1-m-deep wells was 2.1 days. A rainstorm-induced dilution of the salinity of Kaneohe Bay provides the second tracer. Samples of surface and reef interstitial waters following this salinity perturbation are used to calculate an average residence time of 2.6 days at a depth of 1 m and 42 days at a depth of 2 m. Three types of physical forces thought to cause exchange between surface and interstitial water are considered by measurement of the forcing functions and reef permeability. Hydraulic conductivities are about 50 m/d, with lower values near the seaward side of the reef. Most exchange seems to be caused by high-frequency, wave-driven oscillatory pumping and by unidirectional hydraulic head gradients (of uncertain origin) that are stable for at least 3-4 days. Wave-driven mixing is probably more important shallower in the reef, whereas head-driven flow may dominate deeper in the reef. Tidal pumping does not seem to contribute to exchange. All methods indicate that exchange in the upper part of Checker Reef is primarily through vertical exchange. The best estimate for the residence time of water at a depth of 1 m is 2 days. Water at depths of 204 m probably has a residence time of weeks to months. 49 refs., 8 figs., 6 tabs.

Tribble, G.W.; Sansone, F.J.; Li, Yuan-Hui [Univ. of Hawaii, Honolulu, Hi (United States)] [and others] [Univ. of Hawaii, Honolulu, Hi (United States); and others



Sea, ice and surface water circulation, Alaskan Continental Shelf  

NASA Technical Reports Server (NTRS)

The author has identified the following significant results. Two cruises were conducted in Cook Inlet to obtain ground truth. Forty-seven stations during 22-23 August and 68 stations during 25-29 September 1972 were occupied and temperature, salinity, percent light transmission, and suspended load of surface waters obtained. Similar data at various depths was also obtained at selected stations. Cook Inlet is an estuary with complex mixing of river discharges and ocean water. The Upper Cook Inlet shows a gradual and systematic decrease in salinity, however, west of Kenai the mixing of waters is complex. The sediments in suspension originating at the head of the inlet generally settle out east of Kenai and Drift River. Sediment load in suspension decreased gradually from 1700 mg/1 near Anchorage to about 50 mg/1 in the Narrows. In the Lower Cook Inlet the suspended load varied between 1-10 mg/1. Surface waters with sediments in suspension and ocean water with relatively lower sediment concentration are clearly discernible in ERTS-1 images obtained during September 18, 1972 pass over Cook Inlet. The movement and mixing of these waters can also be delineated in the images.

Wright, F. F. (principal investigator); Sharma, G. D.



Changes in the expression of E-cadherin repressors, Snail, Slug, SIP1, and Twist, in the development and progression of ovarian carcinoma: the important role of Snail in ovarian tumorigenesis and progression.  


Changes in the expression of E-cadherin have been reported to be important in the tumorigenesis and progression of epithelial ovarian carcinoma. To further examine the mechanisms regulating E-cadherin expression in ovarian tumorigenesis, we investigated the immunohistochemical expression of transcriptional repressors for E-cadherin, such as Snail, Slug, SIP1, and Twist, in the ovarian surface epithelium (OSE) and 95 cases of epithelial ovarian tumors. OSE cells were negative for SIP1 and Slug, whereas weak expression of Snail and Twist was observed in 8 (73%) and 3 (27%) cases, respectively. Of 95 ovarian tumors, the expression of Snail, Slug, SIP1, and Twist increased stepwise in benign, borderline, and malignant tumors. Among them, the expression of Snail showed significantly inverse correlation with that of E-cadherin. Regarding the FIGO stage classification, the expressions of Snail and Twist were significantly increased in advanced cases. The prognosis of ovarian carcinoma patients positive for Snail expression was poorer than that of negative patients. Our results indicate that the expression of E-cadherin transcriptional repressors increased with malignancy in ovarian epithelial neoplasms and that the expression of E-cadherin and its negative regulators is altered during ovarian cancer development and peritoneal dissemination. PMID:19536615

Yoshida, Junko; Horiuchi, Akiko; Kikuchi, Norihiko; Hayashi, Akiko; Osada, Ryosuke; Ohira, Satoshi; Shiozawa, Tanri; Konishi, Ikuo



Water Resources Data for Florida, Water Year 1994. Volume 3A. Southwest Florida Surface Water.  

National Technical Information Service (NTIS)

The data for Southwest Florida include records of stage, discharge, and water quality of streams, contents, water quality of lakes and reservoirs, and water levels and water quality of ground-water wells. Volume 3A contains continuous or daily discharge f...

J. E. Coffin, W. L. Fletcher



Water Surface and Velocity Measurement-River and Flume  

NASA Astrophysics Data System (ADS)

Understanding the flow of water in natural watercourses has become increasingly important as climate change increases the incidence of extreme rainfall events which cause flooding. Vegetation in rivers and streams reduce water conveyance and natural vegetation plays a critical role in flood events which needs to be understood more fully. A funded project at Loughborough University is therefore examining the influence of vegetation upon water flow, requiring measurement of both the 3-D water surface and flow velocities. Experimental work therefore requires the measurement of water surface morphology and velocity (i.e. speed and direction) in a controlled laboratory environment using a flume but also needs to be adaptable to work in a real river. Measuring the 3D topographic characteristics and velocity field of a flowing water surface is difficult and the purpose of this paper is to describe recent experimental work to achieve this. After reviewing past work in this area, the use of close range digital photogrammetry for capturing both the 3D water surface and surface velocity is described. The selected approach uses either two or three synchronised digital SLR cameras in combination with PhotoModeler for data processing, a commercial close range photogrammetric package. One critical aspect is the selection and distribution of appropriate floating marker points, which are critical if automated and appropriate measurement methods are to be used. Two distinct targeting approaches are available: either large and distinct specific floating markers or some fine material capable of providing appropriate texture. Initial work described in this paper uses specific marker points, which also provide the potential measuring surface velocity. The paper demonstrates that a high degree of measurement and marking automation is possible in a flume environment, where lighting influences can be highly controlled. When applied to a real river it is apparent that only lower degrees of automation are practicable. The study has demonstrated that although some automation is possible for point measurement, point matching needs to be manually guided in a natural environment where lighting cannot be controlled.

Chandler, J. H.; Ferreira, E.; Wackrow, R.; Shiono, K.



Qualitative Uncertainty Assessment for Distributed Surface Water Quality Models  

NASA Astrophysics Data System (ADS)

Water quality models are often used to aid water quality regulators in the United States and around the world make critical decisions about how to improve water quality. Basin scale water quality models generally simplify spatial complexity to some degree. This problem is especially relevant in water quality modeling since the sources of pollution as well as the hydrologic drivers vary spatially across the landscape. The spatial complexity problem also presents specific challenges for estimating model predictive uncertainty. Questions of how to integrate multiple sources of stream water and water quality data at multiple locations are likely to be even more daunting than they are for surface water hydrologic models. At this time, given the complexity of water quality models and the general lack of data available, true statistical techniques of integrating, multiple data sources and calculating uncertainty bounds are probably not reasonable approaches. For this reason, we propose evaluation methods that are not based on statistics in order to evaluate the fit-to- purpose of particular model applications. Within SWAT2005, both a statistical method for uncertainty analysis, ParaSol, and an evaluation method, SUNGLASSES, have been incorporated. Additionally weighted averages of prediction errors are integrated into a global objective function and used to evaluate the reasonableness of model assumptions. This integration occurs across multiple objective functions and multiple locations. These methods have been applied in the context of a hypothetical water quality control problem in the San Jacinto watershed in southern California. The analysis includes an extension of the uncertainty analysis into its economic implications. The economic impact of the uncertainty methods proposed here are compared to more traditional uncertainty methods. The economic implications of uncertainty are shown to be important but only under circumstances where water quality targets are close to being met.

Meixner, T.; Bubb, K.; van Griensven, A.



The snail Potamopyrgus antipodarum grows faster and is more active in the shade, independent of food quality.  


Ecological stoichiometry has advanced food web ecology by emphasising the importance of food quality over food quantity for herbivores. Here, we focus on the effects of abiotic factors such as nutrients and light (known to influence food quality) on grazer growth rates. As model organism we used the mudsnail Potamopyrgus antipodarum that is native to New Zealand but invasive elsewhere. In a stream channel experiment in New Zealand, we manipulated light (two levels) and nutrients (four levels) to achieve a range of primary producer carbon: nutrient ratios and added mudsnails (3 densities + ungrazed control) to 128 periphyton covered stream channels in a 2 × 4 × 4 full factorial design. We measured snail growth rate and activity, food quality and nutritional imbalance, to test the predictions that (1) less light and more nutrients increase periphyton food quality and thus snail growth rates, and (2) less crowding leads to higher food availability and thus higher snail growth rates. We found that snail growth rates were higher under low light than under high light intensities and this difference increased with increasing nutrient addition. These changes in growth rate were not mediated by food quality in terms of periphyton nutrient ratios. Furthermore, experimental treatments strongly affected snail behaviour. Snails grazed more actively in the low light treatments, and thus it is more likely that snail growth rates were directly affected by light levels, maybe as a result of innate predator avoidance behaviour or as a reaction to high UV intensities. We conclude that in our stream channels snail growth rate was limited by factors other than food quality and quantity such as UV exposure, algal defences or the relatively low ambient water temperature. PMID:21437650

Liess, A; Lange, K



Snail–periphyton interactions in a prairie lacustrine wetland  

Microsoft Academic Search

This study examined the effects of nutrients and macrophytes on snail grazers and periphyton in a prairie wetland food web. Snails (Gyraulus circumstriatus) and periphyton in large enclosures in a lacustrine wetland, Delta Marsh, MB, Canada were subjected to two experimental treatments, nutrient addition (nitrogen, phosphorus) and macrophyte exclusion (using a porous geotextile carpet) during July and August. Snail biomass

B. J. Hann; C. J. Mundy; L. G. Goldsborough



Snail-periphyton interactions in a prairie lacustrine wetland  

Microsoft Academic Search

This study examined the effects of nutrients and macrophytes on snail grazers and periphyton in a prairie wetland food web. Snails (Gyraulus circumstriatus) and periphyton in large enclosures in a lacustrine wetland, Delta Marsh, MB, Canada were subjected to two experimental treatments, nutrient addition (nitrogen, phosphorus) and macrophyte exclusion (using a porous geotextile carpet) during July and August. Snail biomass

B. J. Hann; C. J. Mundy; L. G. Goldsborough



Evaluation of the Surface-Water Quantity, Surface-Water Quality, and Rainfall Data-Collection Programs in Hawaii, 1994  

USGS Publications Warehouse

This report documents the results of an evaluation of the surface-water quantity, surface-water quality, and rainfall data-collection programs in Hawaii. Fourteen specific issues and related goals were identified for the surface-water quantity program and a geographic information systems (GIS) data base was developed summarizing information for all surface-water stream gages that have been operated in Hawaii by the U.S. Geological Survey. Changes in status, which for some gages includes discontinuing operation, need to be considered at 42 sites where data are currently collected. The current surface-water quantity data base was determined to be adequate to address only two of the 14 specific issues and related goals. Alternatives were identified to address the areas where future issues and goals could not be adequately addressed. Options include new and expanded data collection, use of regional regression analyses, hydrologic and hydraulic modeling, and analysis and publication of existing data. A total of 47 streams were identified where additional stream-gaging stations are needed. Evaluation of the surface-water quality program was limited to a description of the U.S. Geological Survey's historical and existing programs and available analyses of data. Limitations of the program are described which primarily included lack of data regarding suspended sediment, land-use effects, quality of stream discharge to oceans, background water quality and nonpoint sources of contamination. Evaluation of the rainfall data program indicated that identified future goals could be discussed as either regional, systems related, current needs, forecasting, water quality, or trend analysis related. To address these goals, data from about 2,000 rain gages, 528 of which are active, are available. Data were found to only partially meet identified goals. Alternatives discussed to address the limitations include the need for more recording gages, primarily in areas of high rainfall. Another area of concern was the potential that many plantations will close and the effect these closings would have on continued operation of the important long-term gages they operate. Evaluation of data-collection programs in Hawaii needs to be an ongoing process. Equally important, data being collected need to be summarized and made available through data bases and published reports.

Fontaine, Richard A.



Searching for liquid water in Europa by using surface observatories.  


Liquid water, as far as we know, is an indispensable ingredient of life. Therefore, locating reservoirs of liquid water in extraterrestrial bodies is a necessary prerequisite to searching for life. Recent geological and geophysical observations from the Galileo spacecraft, though not unambiguous, hint at the possibility of a subsurface ocean in the Jovian moon Europa. After summarizing present evidence for liquid water in Europa, we show that electromagnetic and seismic observations made from as few as two surface observatories comprising a magnetometer and a seismometer offer the best hope of unambiguous characterization of the three-dimensional structure of the ocean and the deeper interior of this icy moon. The observatories would also help us infer the composition of the icy crust and the ocean water. PMID:12449858

Khurana, Krishan K; Kivelson, Margaret G; Russell, Christopher T



Trace-level mercury removal from surface water  

SciTech Connect

Many sorbents have been developed for the removal of mercury and heavy metals from waters; however, most of the data published thus far do not address the removal of mercury to the target levels represented in this project. The application to which these sorbents are targeted for use is the removal of mercury from microgram-per-liter levels to low nanogram-per-liter levels. Sorbents with thiouronium, thiol, amine, sulfur, and proprietary functional groups were selected for these studies. Mercury was successfully removed from surface water via adsorption onto Ionac SR-4 and Mersorb resins to levels below the target goal of 12 ng/L in batch studies. A thiol-based resin performed the best, indicating that over 200,000 volumes of water could be treated with one volume of resin. The cost of the resin is approximately $0.24 per 1,000 gal of water.

Klasson, K.T.; Bostick, D.T.



Expression and localization of transcription factors SNAIL and SLUG in mouse ovaries and pre-implantation embryos.  


SNAIL and SLUG are zinc-finger transcription factors that participate in the regulation of cell division, cell survival, mesoderm formation and epithelial-to-mesenchymal transition. We investigate the expression of SNAIL and SLUG during follicular maturation, ovulation and luteinization in the ovaries of both neonatal mice and gonadotropin-induced immature mice. Furthermore, we examine the expression and localization of these transcription factors during early embryonic cleavage. Our data demonstrate that both SNAIL and SLUG are present in the epithelial cells of the ovarian surface in immature mice. SNAIL is first evident in the interstitial cells and theca cells by postnatal day (PD) 6 and then appears in the oocytes by PD 8, remaining at a constant expression level for all stages studied thereafter. SLUG is expressed in oocytes as early as PD 1. Its expression also increases with the development of the follicles in theca and interstitial cells but not in granulosa cells. In gonadotropin-induced immature mice, both SNAIL and SLUG are expressed in the corpora lutea. During early embryo cleavage, SNAIL occurs in the nucleus and cytoplasm of the majority of the embryo, excluding the nucleolus from the germinal vesicle breakdown (GVBD) to the 8-cell stage and is then localized in the cytoplasm during the morula stage and in the nucleus during the blastocyst stage. SLUG has an identical expression pattern as SNAIL from GVBD until the morula stage, except that it is localized in the cytoplasm during the blastocyst stage. Taken together, these different localization patterns suggest that SNAIL and SLUG probably play important roles during follicular development, luteinization and early embryonic development. PMID:25092544

Guo, Cui; Meng, Xiaoqian; Bai, Jing; Chen, Cheng; Liu, Tao; Liu, Shuzhen; Zhang, Cong; Li, Wei-Ping



Bacteria and Surface Water Quality Standards Section 303(d) of the Clean Water Act requires that each state set  

E-print Network

physi- cal characteristics limit the potential for aquatic recreation and/or if the water body is neverBacteria and Surface Water Quality Standards Section 303(d) of the Clean Water Act requires that each state set water quality standards to ensure all uses of a water body have the ap- propriate water


Evaluation of Human Enteric Viruses in Surface Water and Drinking Water Resources in Southern Ghana  

PubMed Central

An estimated 884 million people worldwide do not have access to an improved drinking water source, and the microbial quality of these sources is often unknown. In this study, a combined tangential flow, hollow fiber ultrafiltration (UF), and real-time PCR method was applied to large volume (100 L) groundwater (N = 4), surface water (N = 9), and finished (i.e., receiving treatment) drinking water (N = 6) samples for the evaluation of human enteric viruses and bacterial indicators. Human enteric viruses including norovirus GI and GII, adenovirus, and polyomavirus were detected in five different samples including one groundwater, three surface water, and one drinking water sample. Total coliforms and Escherichia coli assessed for each sample before and after UF revealed a lack of correlation between bacterial indicators and the presence of human enteric viruses. PMID:21212196

Gibson, Kristen E.; Opryszko, Melissa C.; Schissler, James T.; Guo, Yayi; Schwab, Kellogg J.



Storm water contamination and its effect on the quality of urban surface waters.  


We studied the effect of storm water drained by the sewerage system and discharged into a river and a small reservoir, on the example of five catchments located within the boundaries of the city of Pozna? (Poland). These catchments differed both in terms of their surface area and land use (single- and multi-family housing, industrial areas). The aim of the analyses was to explain to what extent pollutants found in storm water runoff from the studied catchments affected the quality of surface waters and whether it threatened the aquatic organisms. Only some of the 14 studied variables and 22 chemical elements were important for the water quality of the river, i.e., pH, TSS, rain intensity, temperature, conductivity, dissolved oxygen, organic matter content, Al, Cu, Pb, Zn, Fe, Cd, Ni, Se, and Tl. The most serious threat to biota in the receiver came from the copper contamination of storm water runoff. Of all samples below the sewerage outflow, 74% exceeded the mean acute value for Daphnia species. Some of them exceeded safe concentrations for other aquatic organisms. Only the outlet from the industrial area with the highest impervious surface had a substantial influence on the water quality of the river. A reservoir situated in the river course had an important influence on the elimination of storm water pollution, despite the very short residence time of its water. PMID:24981877

Bara?kiewicz, Danuta; Chudzi?ska, Maria; Szpakowska, Barbara; ?wierk, Dariusz; Go?dyn, Ryszard; Dondajewska, Renata



Mitigation of acid deposition: Liming of surface waters. Final report  

SciTech Connect

In recent years acid deposition has become a serious concern internationally. Scientific literature has documented the acidification of numerous lakes and streams in North America and Scandinavia resulting in the depletion or total loss of fisheries and other aquatic biota. Liming represents the only common corrective practice aimed specifically at remediating an affected acid receptor. This report reviews a range of liming technologies and liming materials, as well as the effect of surface-water liming on water quality and aquatic biota. As background to the liming discussion, the hydrologic cycle and the factors that make surface waters sensitive to acid deposition are also discussed. Finally, a brief review of some of the liming projects that have been conducted, or are currently in operation is presented, giving special emphasis to mitigation efforts in Maryland. Liming has been effectively used to counteract surface-water acidification in parts of Scandinavia, Canada, and the U.S. To date, liming has generally been shown to improve physical and chemical conditions and enhance the biological recovery of aquatic ecosystems affected by acidification.

Bartoshesky, J.; Price, R.; DeMuro, J.



Linking land use with pesticides in Dutch surface waters.  


Compared with other European countries The Netherlands has a relatively high level of pesticide consumption, particularly in agriculture. Many of the compounds concerned end up in surface waters. Surface water quality is routinely monitored and numerous pesticides are found to be present in high concentrations, with various standards being regularly exceeded. Many standards-breaching pesticides exhibit regional patterns that can be traced back to land use. These patterns have been statistically analysed by correlating surface area per land use category with standards exceedance per pesticide, thereby identifying numerous significant correlations with respect to breaches of both the ecotoxicological standard (Maximum Tolerable Risk, MTR) and the drinking water standard. In the case of the MTR, greenhouse horticulture, floriculture and bulb-growing have the highest number as well as percentage of standard-breaching pesticides, despite these market segments being relatively small in terms of area cropped. Cereals, onions, vegetables, perennial border plants and pulses are also associated with many pesticides that exceed the drinking water standard. When a correction is made for cropped acreage, cereals and potatoes also prove to be a major contributor to monitoring sites where the MTR standard is exceeded. Over the period 1998-2006 the land-use categories with the most and highest percentage of standards-exceeding pesticides (greenhouse horticulture, bulb-growing and flower cultivation) showed an increase in the percentage of standards-exceeding compounds. PMID:23885409

Van't, Zelfde M T; Tamis, W L M; Vijver, M G; De Snoo, G R



Reduction of water surface tension significantly impacts gecko adhesion underwater.  


The gecko adhesive system is dependent on weak van der Waals interactions that are multiplied across thousands of fine hair-like structures (setae) on geckos' toe pads. Due to the requirements of van der Waals forces, we expect that any interruption between the setae and substrate, such as a water layer, will compromise adhesion. Our recent results suggest, however, that the air layer (plastron) surrounding the superhydrophobic toe pads aid in expelling water at the contact interface and create strong shear adhesion in water when in contact with hydrophobic surfaces. To test the function of the air plastron, we reduced the surface tension of water using two surfactants, a charged anionic surfactant and a neutral nonionic surfactant. We tested geckos on three substrates: hydrophilic glass and two hydrophobic surfaces, glass with a octadecyl trichlorosilane self-assembled monolayer (OTS-SAM) and polytetrafluoroethylene (PTFE). We found that the anionic surfactant inhibited the formation of the air plastron layer and significantly reduced shear adhesion to all three substrates. Interestingly, the air plastron was more stable in the nonionic surfactant treatments than the anionic surfactant treatments and we found that geckos adhered better in the nonionic surfactant than in the anionic surfactant on OTS-SAM and PTFE but not on glass. Our results have implications for the evolution of a superhydrophobic toe pad and highlight some of the challenges faced in designing synthetic adhesives that mimic geckos' toes. PMID:24944119

Stark, Alyssa Y; McClung, Brandon; Niewiarowski, Peter H; Dhinojwala, Ali



Pesticide monitoring in surface water and groundwater using passive samplers  

NASA Astrophysics Data System (ADS)

Passive samplers as screening devices have been used within a czech national water quality monitoring network since 2002 (SPMD and DGT samplers for non polar substances and metals). The passive sampler monitoring of surface water was extended to polar substances, in 2005. Pesticide and pharmaceutical POCIS samplers have been exposed in surface water at 21 locations and analysed for polar pesticides, perfluorinated compounds, personal care products and pharmaceuticals. Pesticide POCIS samplers in groundwater were exposed at 5 locations and analysed for polar pesticides. The following active substances of plant protection products were analyzed in surface water and groundwater using LC/MS/MS: 2,4,5-T, 2,4-D, Acetochlor, Alachlor, Atrazine, Atrazine_desethyl, Azoxystrobin, Bentazone, Bromacil, Bromoxynil, Carbofuran, Clopyralid, Cyanazin, Desmetryn, Diazinon, Dicamba, Dichlobenil, Dichlorprop, Dimethoat, Diuron, Ethofumesate, Fenarimol, Fenhexamid, Fipronil, Fluazifop-p-butyl, Hexazinone, Chlorbromuron, Chlorotoluron, Imazethapyr, Isoproturon, Kresoxim-methyl, Linuron, MCPA, MCPP, Metalaxyl, Metamitron, Methabenzthiazuron, Methamidophos, Methidathion, Metobromuron, Metolachlor, Metoxuron, Metribuzin, Monolinuron, Nicosulfuron, Phorate, Phosalone, Phosphamidon, Prometryn, Propiconazole, Propyzamide, Pyridate, Rimsulfuron, Simazine, Tebuconazole, Terbuthylazine, Terbutryn, Thifensulfuron-methyl, Thiophanate-methyl and Tri-allate. The POCIS samplers performed very well being able to provide better picture than grab samples. The results show that polar pesticides and also perfluorinated compounds, personal care products and pharmaceuticals as well occur in hydrosphere of the Czech republic. Acknowledgment: Authors acknowledge the financial support of grant No. 2B06095 by the Ministry of Education, Youth and Sports.

Kodes, V.; Grabic, R.



Determination of antibiotic residues in manure, soil, and surface waters  

USGS Publications Warehouse

In the last years more and more often detections of antimicrobially active compounds ("antibiotics") in surface waters have been reported. As a possible input pathway in most cases municipal sewage has been discussed. But as an input from the realm of agriculture is conceivable as well, in this study it should be investigated if an input can occur via the pathway application of liquid manure on fields with the subsequent mechanisms surface run-off/interflow, leaching, and drift. For this purpose a series of surface waters, soils, and liquid manures from North Rhine-Westphalia (Northwestern Germany) were sampled and analyzed for up to 29 compounds by HPLC-MS/MS. In each of the surface waters antibiotics could be detected. The highest concentrations were found in samples from spring (300 ng/L of erythromycin). Some of the substances detected (e.g., tylosin), as well as characteristics in the landscape suggest an input from agriculture in some particular cases. In the investigation of different liquid manure samples by a fast immunoassay method sulfadimidine could be detected in the range of 1...2 mg/kg. Soil that had been fertilized with this liquid manure showed a content of sulfadimidine extractable by accelerated solvent extraction (ASE) of 15 ??g/kg dry weight even 7 months after the application. This indicates the high stability of some antibiotics in manure and soil.

Christian, T.; Schneider, R.J.; Farber, H.A.; Skutlarek, D.; Meyer, M.T.; Goldbach, H.E.



The polarization patterns of skylight reflected off wave water surface.  


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. PMID:24514848

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



Identification of new omeprazole metabolites in wastewaters and surface waters.  


Omeprazole is one of the world-wide most consumed pharmaceuticals for treatment of gastric diseases. As opposed to other frequently used pharmaceuticals, omeprazole is scarcely detected in urban wastewaters and environmental waters. This was corroborated in a previous research, where parent omeprazole was not detected while four transformation products (TPs), mainly resulting from hydrolysis, were found in effluent wastewaters and surface waters. However, the low abundance of omeprazole TPs in the water samples together with the fact that omeprazole suffers an extensive metabolism, with a wide range of excretion rates (between 0.01 and 30%), suggests that human urinary metabolites should be investigated in the water environment. In this work, the results obtained in excretion tests after administration of a 40 mg omeprazole dose in three healthy volunteers are reported. Analysis by liquid chromatography coupled to hybrid quadrupole time-of-flight mass spectrometry (LC-QTOF MS) reported low concentrations of omeprazole in urine. Up to twenty-four omeprazole metabolites (OMs) were detected and tentatively elucidated. The most relevant OM was an omeprazole isomer, which obviously presented the same exact mass (m/z 346.1225), but also shared a major common fragment at m/z 198.0589. Subsequent analyses of surface water and effluent wastewater samples by both LC-QTOF MS and LC-MS/MS with triple quadrupole revealed that this metabolite (named as OM10) was the compound most frequently detected in water samples, followed by OM14a and OM14b. Up to our knowledge, OM10 had not been used before as urinary biomarker of omeprazole in waters. On the contrary, parent omeprazole was never detected in any of the water samples. After this research, it seems clear that monitoring the presence of omeprazole in the aquatic environment should be focused on the OMs suggested in this article instead of the parent compound. PMID:24061062

Boix, C; Ibáñez, M; Zamora, T; Sancho, J V; Niessen, W M A; Hernández, F



Dynamics in surface water solute concentrations and consequences for water quality monitoring  

NASA Astrophysics Data System (ADS)

For the evaluation of action programs to reduce surface water pollution, water authorities invest heavily in water quality monitoring. However, sampling frequencies are generally insufficient to capture the dynamical behavior of solute concentrations. This results in large uncertainties in the estimates of loads and average concentrations, which complicates water quality assessments. The main causes of dynamics in groundwater and surface water quality are variations in human land management, biochemical processes, and meteorological conditions. In this study, we focused on the short-term variations in water quality that are normally not captured with common monthly measurement intervals. Our multi-scale experimental research setup in The Netherlands revealed that weather induced variations are the major cause of short-term variations in water quality. During rainfall events, the relative contribution of different flow routes (groundwater, tile drain, overland flow) to the total surface water discharge changes. These different flow routes have different residence times in the subsurface and therefore different chemical compositions. For example, our continuous nitrate concentration measurements repetitively showed a lowering in stream water nitrate concentrations in response to rainfall events. This lowering was caused by a temporal dilution of nitrate-rich tile drain effluent with nitrate-poor rainwater. On the other hand, the continuously measured phosphorus concentrations peaked during rainfall events due to the resuspension of phosphorus-rich sediments. We will also present the following options to deal with the highly dynamic behavior of solute concentrations in surface water quality monitoring practice: (1) use modern equipment for continuous concentration measurements, (2) measure average concentrations using passive samplers, and (3) use the explanatory strength of generally available high-frequency data (e.g. precipitation and discharge records) to reconstruct concentration patterns between low-frequency concentration measurements.

Rozemeijer, J.; Van der Velde, Y.; Broers, H. P.; van Geer, F.



Sensors and OBIA synergy for operational monitoring of surface water  

NASA Astrophysics Data System (ADS)

This contribution will focus on combining Object Based Image Analysis (i.e. OBIA with e-Cognition 8) and recent sensors (i.e. Spot 5 XS, Pan and ALOS Prism, Avnir2, Palsar) to address the technical feasibility for an operational monitoring of surface water. Three cases of river meandering (India), flood mapping (Nepal) and dam's seasonal water level monitoring (Morocco) using recent sensors will present various application of surface water monitoring. The operational aspect will be demonstrated either by sensor properties (i.e. spatial resolution and bandwidth), data acquisition properties (i.e. multi sensor, return period and near real-time acquisition) but also with OBIA algorithms (i.e. fusion of multi sensors / multi resolution data and batch processes). In the first case of river meandering (India) we will address multi sensor and multi date satellite acquisition to monitor the river bed mobility within a floodplain using an ALOS dataset. It will demonstrate the possibility of an operational monitoring system that helps the geomorphologist in the analysis of fluvial dynamic and sediment budget for high energy rivers. In the second case of flood mapping (Nepal) we will address near real time Palsar data acquisition at high spatial resolution to monitor and to map a flood extension. This ALOS sensor takes benefit both from SAR and L band properties (i.e. atmospheric transparency, day/night acquisition, low sensibility to surface wind). It's a real achievement compared to optical imagery or even other high resolution SAR properties (i.e. acquisition swath, bandwidth and data price). These advantages meet the operational needs set by crisis management of hydrological disasters but also for the implementation of flood risk management plans. The last case of dam surface water monitoring (Morocco) will address an important issue of water resource management in countries affected by water scarcity. In such countries water users have to cope with over exploitation, frequent drought period and now with foreseen climate change impacts. This third case will demonstrate the efficiency of SPOT 5 programming in synergy with OBIA methodology to assess the evolution of dam surface water within a complete water cycle (i.e. 2008-09). In all those three cases image segmentation and classification algorithms developed with e-Cognition 8 software allow an easy to use implementation of simple to highly sophisticate OBIA rulsets fully operational in batch processes. Finally this contribution foresees the new opportunity of integration of Worldview 2 multispectral imagery (i.e. 8 bands) including its "coastal" band that will also find an application in continental surface water bathymetry. Worldview 2 is a recently launch satellite (e.g. October 2009) that starts to collect earth observation data since January 2010. It is therefore a promising new remote sensing tool to develop operational hydrology in combination high resolution SAR imagery and OBIA methodology. This contribution will conclude on the strong potential for operationalisation in hydrology and water resources management that recent and future sensors and image analysis methodologies are offering to water management and decision makers.

Masson, Eric; Thenard, Lucas



The occurrence of Pseudomonas spp. in surface water and in tap water as determined on citrate media  

Microsoft Academic Search

Citrate-utilizing bacteria were counted in 289 samples of tap water derived from either surface water or ground water and in 32 samples of raw or partially treated surface water by using media containing ferric ammonium citrate as the carbon and energy source.




Statistical Analysis of Surface Water Quality Data of Eastern Massachusetts  

NASA Astrophysics Data System (ADS)

We present a characterization of current state of surface water, changes in time and dependence on land use, precipitation regime, and possible other natural and human influences based on data from the USGS National Water Quality Assessment (NAWQA) Program for New England streams. Time series analysis is used to detect changes and relationship with discharge and precipitation regime. Statistical techniques are employed to analyze relationships among multiple chemical variable monitored. Analysis of ion concentrations reveals information about possible natural sources and processes, and anthropogenic influences. A notable example is the increase in salt concentration in ground and surface waters, with impact on drinking water quality. Salt concentration increase in water can be linked to road salt usage during winters with heavy snowfall and other factors. Road salt enters water supplies by percolation through soil into groundwater or runoff and drainage into reservoirs. After entering fast-flowing streams, rivers and lakes, salt runoff concentrations are rapidly diluted. Road salt infiltration is more common for groundwater-based supplies, such as wells, springs, and reservoirs that are recharged mainly by groundwater. We use principal component analysis and other statistical procedures to obtain a description of the dominant independent variables that influence the observed chemical compositional range. In most cases, over 85 percent of the total variation can be explained by 3 to 4 components. The overwhelming variation is attributed to a large compositional range of Na and Cl seen even if all data are combined into a single dataset. Na versus Cl correlation coefficients are commonly greater than 0.9. Second components are typically associated with dilutions by overland flows (non winter months) and/or increased concentrations due to evaporation (summer season) or overland flows (winter season) if a snow storm is followed by the application of deicers on road surfaces. The last two components reflect the relative dominance of the composition of the local bedrock on groundwater chemistry or the effect of nutrient cycling.

Andronache, C.; Hon, R.; Tedder, N.; Xian, Q.; Schaudt, B.



Contamination of surface, ground, and drinking water from pharmaceutical production.  


Low levels of pharmaceuticals are detected in surface, ground, and drinking water worldwide. Usage and incorrect disposal have been considered the major environmental sources of these microcontaminants. Recent publications, however, suggest that wastewater from drug production can potentially be a source of much higher concentrations in certain locations. The present study investigated the environmental fate of active pharmaceutical ingredients in a major production area for the global bulk drug market. Water samples were taken from a common effluent treatment plant near Hyderabad, India, which receives process water from approximately 90 bulk drug manufacturers. Surface water was analyzed from the recipient stream and from two lakes that are not contaminated by the treatment plant. Water samples were also taken from wells in six nearby villages. The samples were analyzed for the presence of 12 pharmaceuticals with liquid chromatography-mass spectrometry. All wells were determined to be contaminated with drugs. Ciprofloxacin, enoxacin, cetirizine, terbinafine, and citalopram were detected at more than 1 microg/L in several wells. Very high concentrations of ciprofloxacin (14 mg/L) and cetirizine (2.1 mg/L) were found in the effluent of the treatment plant, together with high concentrations of seven additional pharmaceuticals. Very high concentrations of ciprofloxacin (up to 6.5 mg/L), cetirizine (up to 1.2 mg/L), norfloxacin (up to 0.52 mg/L), and enoxacin (up to 0.16 mg/L) were also detected in the two lakes, which clearly shows that the investigated area has additional environmental sources of insufficiently treated industrial waste. Thus, insufficient wastewater management in one of the world's largest centers for bulk drug production leads to unprecedented drug contamination of surface, ground, and drinking water. This raises serious concerns regarding the development of antibiotic resistance, and it creates a major challenge for producers and regulatory agencies to improve the situation. PMID:19449981

Fick, Jerker; Söderström, Hanna; Lindberg, Richard H; Phan, Chau; Tysklind, Mats; Larsson, D G Joakim



Surface Water Quality Trends from EPA's LTM Network  

NASA Astrophysics Data System (ADS)

Surface water chemistry provides direct indicators of the potential effects of anthropogenic impacts, such as acid deposition and climate change, on the overall health of aquatic ecosystems. Long-term surface water monitoring networks provide a host of environmental data that can be used, in conjunction with other networks, to assess how water bodies respond to stressors and if they are potentially at risk (e.g., receiving pollutant deposition beyond its critical load). Two EPA-administered monitoring programs provide information on the effects of acidic deposition on headwater aquatic systems: the Long Term Monitoring (LTM) program and the Temporally Integrated Monitoring of Ecosystems (TIME) program, designed to track the effectiveness of the 1990 Clean Air Act Amendments (CAAA) in reducing the acidity of surface waters in acid sensitive ecoregions of the Northeast and Mid-Atlantic. Here we present regional variability of long term trends in surface water quality in response to substantial reductions in atmospheric deposition. Water quality trends at acid sensitive LTM sites exhibit decreasing concentrations of sulfate at 100% of monitored sites in the Adirondack Mountains and New England, 80% of Northern Appalachian Plateau sites, and yet only 15% of sites in the Ridge and Blue Ridge Provinces over the 1990-2011 period of record. Across all regions, most LTM sites exhibited constant or only slightly declining nitrate concentrations over the same time period. Acid Neutralizing Capacity (ANC) levels improved at 68% and 45% of LTM sites in the Adirondacks and Northern Appalachian Plateau, respectively, but few sites showed increases in New England or the Ridge and Blue Ridge Provinces due to lagging improvements in base cation concentration. The ANC of northeastern TIME lakes was also evaluated from 1991 to 1994 and 2008 to 2011. The percentage of lakes with ANC values below 50 ?eq/L, lakes of acute or elevated concern, dropped by about 7%, indicating improvement in all sensitivity classes. Information from long-term monitoring has shown that emission reductions have resulted in improved environmental conditions and increased ecosystem protection. However, despite some ecological recovery, lakes and streams in these regions remain at risk due to current acid deposition levels. The TIME/LTM programs, along with other monitoring networks, will continue to monitor surface water trends for effects of acid deposition and other anthropogenic impacts.

Funk, C.; Lynch, J. A.



Surface Water Monitoring: Brief History, Current State and Future Needs  

NASA Astrophysics Data System (ADS)

Surface water bodies represent the most important water resources to human society, and their accurate monitoring is essential for proper water management and resource allocation. Furthermore, river discharge is one of the most accurately measured components of the hydrological cycle, yet it is not fully utilized in Earth Systems sciences. The value of surface monitoring was recognized by ancient civilizations. Human expansion in the last two centuries were often followed by the establishment of discharge monitoring networks. The currently operating discharge gauges monitor over 50% of the continental land mass, capturing more than 70% of the freshwater discharge to the oceans. Approximately 30% of the continental land mass is arheic (i.e. do not contribute any freshwater to the oceans) and the remaining 20% non-monitored areas are primarily in small coastal basins that would be hard to fully instrument. Despite the reasonably good spatial coverage, the current monitoring network is inadequate in terms of spatial density and the availability of the monitored records. Information about the state of standing water bodies (lakes, reservoirs, wetlands and floodplains) is almost non-existent for global analysis. However, traditional surface water monitoring techniques are well established and highly accurate, but their operation is labor intensive (in particular, the calibrations that require intensive field surveys). Major improvement in surface water monitoring would require either substantial investment or a technological breakthrough. Remote sensing techniques (especially satellite borne sensors) have the potential to offer the much needed data about inland surface waters that would complement the existing monitoring network. The planned presentation will give a brief overview of the evolution of global discharge monitoring. It will demonstrate the temporal and spatial distribution of discharge records by geographic regions. The requirement of the adequate monitoring network for large scale applications will be discussed both in terms of network density and observation frequency. The potential of remote sensing will be assessed by evaluating various satellite sensors and platforms in the context of a virtual mission that allows the assessment of retrieved information as a function of orbital configurations and sensor characteristics.

Fekete, B. M.; Vorosmarty, C. J.



Global analysis of urban surface water supply vulnerability  

NASA Astrophysics Data System (ADS)

This study presents a global analysis of urban water supply vulnerability in 71 surface-water supplied cities, with populations exceeding 750 000 and lacking source water diversity. Vulnerability represents the failure of an urban supply-basin to simultaneously meet demands from human, environmental and agricultural users. We assess a baseline (2010) condition and a future scenario (2040) that considers increased demand from urban population growth and projected agricultural demand. We do not account for climate change, which can potentially exacerbate or reduce urban supply vulnerability. In 2010, 35% of large cities are vulnerable as they compete with agricultural users. By 2040, without additional measures 45% of cities are vulnerable due to increased agricultural and urban demands. Of the vulnerable cities in 2040, the majority are river-supplied with mean flows so low (1200 liters per person per day, l/p/d) that the cities experience ‘chronic water scarcity’ (1370 l/p/d). Reservoirs supply the majority of cities facing individual future threats, revealing that constructed storage potentially provides tenuous water security. In 2040, of the 32 vulnerable cities, 14 would reduce their vulnerability via reallocating water by reducing environmental flows, and 16 would similarly benefit by transferring water from irrigated agriculture. Approximately half remain vulnerable under either potential remedy.

Padowski, Julie C.; Gorelick, Steven M.



MAIC-2, a latitudinal model for the Martian surface temperature, atmospheric water transport and surface glaciation  

NASA Astrophysics Data System (ADS)

The Mars Atmosphere-Ice Coupler MAIC-2 is a simple, latitudinal model, which consists of a set of parameterisations for the surface temperature, the atmospheric water transport and the surface mass balance (condensation minus evaporation) of water ice. It is driven directly by the orbital parameters obliquity, eccentricity and solar longitude (Ls ) of perihelion. Surface temperature is described by the Local Insolation Temperature (LIT) scheme, which uses a daily and latitude-dependent radiation balance. The evaporation rate of water is calculated by an expression for free convection, driven by density differences between water vapor and ambient air, the condensation rate follows from the assumption that any water vapour which exceeds the local saturation pressure condenses instantly, and atmospheric transport of water vapour is approximated by instantaneous mixing. Glacial flow of ice deposits is neglected. Simulations with constant orbital parameters show that low obliquities favour deposition of ice in high latitudes and vice versa. A transient scenario driven by a computed history of orbital parameters over the last 10 million years produces essentially monotonically growing polar ice deposits during the most recent 4 million years, and a very good agreement with the observed present-day polar layered deposits. The thick polar deposits sometimes continue in thin ice deposits which extend far into the mid latitudes, which confirms the idea of "ice ages" at high obliquity.

Grieger, Bjoern; Greve, Ralf; Stenzel, Oliver


Mathematical Simulation of Sediment and Radionuclide Transport in Surface Waters  

SciTech Connect

The study objective of "The Mathematical Simulation of Sediment and Radionuclide Transport in Surface Waters" is to synthesize and test radionuclide transport models capable of realistically assessing radionuclide transport in various types of surface water bodies by including the sediment-radionuclide interactions. These interactions include radionuclide adsorption by sediment; desorption from sediment into water; and transport, deposition, and resuspension of sorbed radionuclides controlled by the sediment movements. During FY-1979, the modification of sediment and contaminant (radionuclide) transport model, FETRA, was completed to make it applicable to coastal waters. The model is an unsteady, two-dimensional (longitudinal and lateral) model that consists of three submodels (for sediment, dissolved-contaminant, and particulate-contaminant transport), coupled to include the sediment-contaminant interactions. In estuaries, flow phenomena and consequent sediment and radionuclide migration are often three-dimensional in nature mainly because of nonuniform channel cross-sections, salinity intrusion, and lateral-flow circulation. Thus, an unsteady, three-dimensional radionuclide transport model for estuaries is also being synthesized by combining and modifying a PNL unsteady hydrothermal model and FETRA. These two radionuclide transport models for coastal waters and estuaries will be applied to actual sites to examine the validity of the codes.




Measuring the true height of water films on surfaces.  


Measuring the level of hydrophilicity of heterogeneous surfaces and the true height of water layers that form on them in hydrated conditions has a myriad of applications in a wide range of scientific and technological fields. Here, we describe a true non-contact mode of operation of atomic force microscopy in ambient conditions and a method to establish the source of apparent height. A dependency of the measured water height on operational parameters is identified with water perturbations due to uncontrolled modes of imaging where intermittent contact with the water layer, or even the surface, might occur. In this paper we show how to (1) determine when the water is being perturbed and (2) distinguish between four different interaction regimes. Each of the four types of interaction produces measurements ranging from fractions of the true height in one extreme to values which are as large as four times the real height in the other. We show the dependence of apparent height on the interaction regime both theoretically and empirically. The agreement between theory and experiment on a BaF2(111) sample displaying wet and un-wet regions validates our results. PMID:22025083

Santos, Sergio; Verdaguer, Albert; Souier, Tewfic; Thomson, Neil H; Chiesa, Matteo



The Whitham Equation as a Model for Surface Water Waves  

E-print Network

The Whitham equation was proposed as an alternate model equation for the simplified description of uni-directional wave motion at the surface of an inviscid fluid. As the Whitham equation incorporates the full linear dispersion relation of the water wave problem, it is thought to provide a more faithful description of shorter waves of small amplitude than traditional long wave models such as the KdV equation. In this work, we identify a scaling regime in which the Whitham equation can be derived from the Hamiltonian theory of surface water waves. The Whitham equation is integrated numerically, and it is shown that the equation gives a close approximation of inviscid free surface dynamics as described by the Euler equations. The performance of the Whitham equation as a model for free surface dynamics is also compared to two standard free surface models: the KdV and the BBM equation. It is found that in a wide parameter range of amplitudes and wavelengths, the Whitham equation performs on par with or better than both the KdV and BBM equations.

Daulet Moldabayev; Henrik Kalisch; Denys Dutykh



The Whitham Equation as a Model for Surface Water Waves  

E-print Network

The Whitham equation was proposed as an alternate model equation for the simplified description of uni-directional wave motion at the surface of an inviscid fluid. As the Whitham equation incorporates the full linear dispersion relation of the water wave problem, it is thought to provide a more faithful description of shorter waves of small amplitude than traditional long wave models such as the KdV equation. In this work, we identify a scaling regime in which the Whitham equation can be derived from the Hamiltonian theory of surface water waves. The Whitham equation is integrated numerically, and it is shown that the equation gives a close approximation of inviscid free surface dynamics as described by the Euler equations. The performance of the Whitham equation as a model for free surface dynamics is also compared to two standard free surface models: the KdV and the BBM equation. It is found that in a wide parameter range of amplitudes and wavelengths, the Whitham equation performs on par with or better tha...

Moldabayev, Daulet; Dutykh, Denys



Occurrence of Glyphosate in Surface Waters of Southern Ontario  

Microsoft Academic Search

Glyphosate in surface waters of southern Ontario (Canada) was studied over a 2-year period. A small percentage of samples\\u000a exhibited glyphosate concentrations greater than the analytical limit of quantitation (17 ?g a.e.\\/L), and the maximum concentration\\u000a of glyphosate measured was 40.8 ?g\\/L. No samples of roughly 500 analyzed exceeded the Canadian Water Quality Guideline of\\u000a 65 ?g a.e.\\/L considered protective of aquatic life.

John Struger; Dean Thompson; Bozena Staznik; Pamela Martin; Tana McDaniel; Chris Marvin



Soil Moisture: The Hydrologic Interface Between Surface and Ground Waters  

NASA Technical Reports Server (NTRS)

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.

Engman, Edwin T.



Epigenetic Regulation of EMT: The Snail Story  

PubMed Central

While the epithelial-mesenchymal transition (EMT) plays a fundamental role during development, its deregulation can adversely promote tumor metastasis. The phenotypic and cellular plasticity of EMT indicates that it is subject to epigenetic regulation. In this review, we try to embrace recent findings on the mechanisms of the transcription factor Snail-mediated E-cadherin silencing, which is a hallmark of EMT. Our studies as well as those of others have clearly demonstrated that Snail can recruit multiple chromatin enzymes including LSD1, HDAC1/2, PRC2, G9a and Suv39H1 to the E-cadherin promoter. These enzymes function in a highly orchestrated fashion to generate heterochromatin and promote DNA methyltransferase (DNMT)-mediated DNA methylation at the promoter region. Disruption of the connection between Snail and these chromatin-modifying enzymes may represent an efficient strategy for the treatment of EMT-related diseases. PMID:23888971

Lin, Yiwei; Dong, Chenfang; Zhou, Binhua P.




EPA Science Inventory

As a consequence of the 1986 Amendments to the Safe Drinking Water Act (SDWA) the U.S. EPA has issued a Surface Water Treatment Rule (SWTR) for systems using surface and ground waters under the direct influence of surface water. n the Guidance Manual of the SWTR, the EPA recommen...



Microsoft Academic Search

This paper describes the development, installation, and performance testing of a surface water pump system at TVA's Douglas Dam. Surface water pumps move a large volume of highly oxygenated surface water down to a level where it is withdrawn through the hydropower intakes to improve the water quality of hydropower releases. TVA has tested several different arrangements and types of

Mark Mobley; Willola Tyson; Joe Webb; Gary Brock


Surface characterization of polymethylmetacrylate bombarded by charged water droplets  

SciTech Connect

The electrospray droplet impact (EDI), in which the charged electrospray water droplets are introduced in vacuum, accelerated, and allowed to impact the sample, is applied to polymethylmetacrylate (PMMA). The secondary ions generated were measured by an orthogonal time-of-flight mass spectrometer. In EDI mass spectra for PMMA, fragment ions originating from PMMA could not be detected. This is due to the fact that the proton affinities of fragments formed from PMMA are smaller than those from acetic acid contained in the charged droplet. The x-ray photoelectron spectroscopy spectra of PMMA irradiated by water droplets did not change with prolonged cluster irradiation, i.e., EDI is capable of shallow surface etching for PMMA with a little damage of the sample underneath the surface.

Hiraoka, Kenzo; Takaishi, Riou; Asakawa, Daiki; Sakai, Yuji; Iijima, Yoshitoki [Clean Energy Research Center, University of Yamanashi, Takeda-4, Kofu 400-8511 (Japan); Japan Science and Technology Agency, Naka-ku, Hamamatsu 432-8561 (Japan); Electron Optics Sales Division, JEOL Ltd., 2-8-3 Akebono, Tachikawa, Tokyo 190-0012 (Japan)



Regularity of Traveling Free Surface Water Waves with Vorticity  

NASA Astrophysics Data System (ADS)

We prove real analyticity of all the streamlines, including the free surface, of a gravity- or capillary-gravity-driven steady flow of water over a flat bed, with a Hölder continuous vorticity function, provided that the propagating speed of the wave on the free surface exceeds the horizontal fluid velocity throughout the flow. Furthermore, if the vorticity possesses some Gevrey regularity of index s, then the stream function of class C 2, ? admits the same Gevrey regularity throughout the fluid domain; in particular if the Gevrey index s equals 1, then we obtain analyticity of the stream function. The regularity results hold not only for periodic or solitary-water waves, but also for any solution to the hydrodynamic equations of class C 2, ? .

Chen, Hua; Li, Wei-Xi; Wang, Ling-Jun



How much surface water can gilgai microtopography capture?  

NASA Astrophysics Data System (ADS)

Gilgai microtopography is associated with landscapes of strongly shrinking-swelling soils (Vertisols) and affects spatial and temporal variability of runoff, and thus the generation of stream flow and plant-available water. However, no report is available on the amount of surface water that a landscape with gilgai depressions can retain. Our objective was to assess water capturing capacity of a typical Vertisol landscape with gilgai depressions in the Blackland Prairie Major Land Resource Area of Texas. The 45 by 40 m study site was located on a Vertisol with circular gilgai covered by improved pasture on a summit with slope of less than 3%. A digital elevation model (DEM) with 0.25 m2 cell size was created from elevation data acquired by using GPS. Water capturing capacity of gilgai depressions was estimated at 10 randomly selected local gilgai basins by analyzing spatial distribution of Topographic Wetness Index (TWI). Our findings indicate that the average circular gilgai depression can hold 0.78 m3 of water leading to an estimate of 0.024 m3 m-2 water capturing capacity in a circular gilgai landscape, assuming no infiltration. The gilgai could capture a maximum of 43.74 m3 of rain and runoff water at the 1800 m2 study site. Consequently, if the soil were saturated and not infiltrating any water, no runoff would be expected following a 24.3 mm m-2, 1 h precipitation, affecting estimates of streamflow (runoff) and plant available water (redistribution and infiltration) at the m to km scale.

Kishné, A. Sz.; Morgan, C. L. S.; Neely, H. L.



Impact of river restoration on groundwater - surface water - interactions  

NASA Astrophysics Data System (ADS)

Since the end of the 19th century, flood protection was increasingly based on the construction of impermeable dams and side walls (BWG, 2003). In spite of providing flood protection, these measures also limited the connectivity between the river and the land, restricted the area available for flooding, and hampered the natural flow dynamics of the river. Apart from the debilitating effect on riverine ecosystems due to loss of habitats, these measures also limited bank filtration, inhibited the infiltration of storm water, and affected groundwater-surface water-interactions. This in turn had a profound effect on ecosystem health, as a lack of groundwater-surface water interactions led to decreased cycling of pollutants and nutrients in the hyporheic zone and limited the moderation of the water temperature (EA, 2009). In recent decades, it has become apparent that further damages to riverine ecosystems must be prohibited, as the damages to ecology, economy and society surmount any benefits gained from exploiting them. Nowadays, the restoration of rivers is a globally accepted means to restore ecosystem functioning, protect water resources and amend flood protection (Andrea et al., 2012; Palmer et al., 2005; Wortley et al., 2013). In spite of huge efforts regarding the restoration of rivers over the last 30 years, the question of its effectiveness remains, as river restorations often reconstruct a naturally looking rather than a naturally functioning stream (EA, 2009). We therefore focussed our research on the effectiveness of river restorations, represented by the groundwater-surface water-interactions. Given a sufficiently high groundwater level, a lack of groundwater-surface water-interactions after restoration may indicate that the vertical connectivity in the stream was not fully restored. In order to investigate groundwater-surface water-interactions we determined the thermal signature on the stream bed and in +/- 40 cm depth by using Distributed Temperature Sensing (DTS), a fibre optical method for temperature determination over long distances (Selker et al., 2006). Thermal signatures were determined in a small urban stream before and after restoration and compared to streams in natural and near-natural settings. BWG BUNDESAMT FÜR WASSER UND GEOLOGIE, 2003. Die Geschichte des Hochwasserschutzes in der Schweiz. Bericht des BWG, Serie Wasser. Biel. 208 p. EA ENVIRONMENT AGENCY (UK), 2009. The Hyporheic Handbook: A handbook on the groundwater-surface water interface and hyporheic zone for environment managers. Bristol. 280 p. ANDREA, F., GSCHÖPF, C., BLASCHKE, A.P., WEIGELHOFER, G., AND RECKENDORFER, W., 2012. Ecological niche models for the evaluation of management options in urban floodplain - conservation vs. restoration purposes. Environ. Sci. Policy, PALMER, M.A., BERNHARDT, E.S., ALLAN, J.D., LAKE, P.S., ALEXANDER, G., BROOKS, S., CARR, J., CLAYTON, S., DAHM, C.N., FOLLSTAD SHAH, J., GALAT, D.L., LOSS, S.G., GOODWIN, P., HART, D.D., HASSETT, B., JENKINSON, R., KONDOLF, G.M., LAVE, R., MEYER, J.L., O`DONNELL, T.K., PAGANO, L. AND SUDDUTH, E., 2005. Standards for ecologically successful river restoration. Journal of Applied Ecology, 42, pp. 208 - 217. DOI 10.1111/j.1365-2664.2005.01004.x. WORTLEY, L., HERO, J-M., HOWES, M., 2013. Evaluating Ecological Restoration Success: A Review of the Literature. Restoration Ecology, 21 (5), pp. 537 - 543. DOI 10.1111/rec.12028. SELKER, J.S., THEVENAZ, L., HUWALD, H., MALLET, A., LUXEMBURG, W., VAN DE GIESEN, N., STEJSKAL, M., ZEMAN, J., WESTHOFF, M., AND PARLANGE, M.B., 2006. Distributed fibre-optic temperature sensing for hydrologic systems. Water Resources Research, 42(12), W12202.

Kurth, Anne-Marie; Schirmer, Mario



Host ploidy, parasitism and immune defence in a coevolutionary snail-trematode system.  


We studied the role of host ploidy and parasite exposure on immune defence allocation in a snail-trematode system (Potamopyrgus antipodarum-Microphallus sp.). In the field, haemocyte (the defence cell) concentration was lowest in deep-water habitats where infection is relatively low and highest in shallow-water habitats where infection is common. Because the frequency of asexual triploid snails is positively correlated with depth, we also experimentally studied the role of ploidy by exposing both diploid sexual and triploid asexual snails to Microphallus eggs. We found that triploid snails had lower haemocyte concentrations than did diploids in both parasite-addition and parasite-free treatments. We also found that both triploids and diploids increased their numbers of large granular haemocytes at similar rates after parasite exposure. Because triploid P. antipodarum have been shown to be more resistant to allopatric parasites than diploids, the current results suggest that the increased resistance of triploids is because of intrinsic genetic properties rather than to greater allocation to defence cells. This finding is consistent with recent theory on the advantages of increased ploidy for hosts combating coevolving parasites. PMID:16405575

Osnas, E E; Lively, C M



Pre-coagulation for microfiltration of an upland surface water  

Microsoft Academic Search

The effect of different coagulants on cake formation and hydraulic resistance in membrane filtration of strongly coloured (SUVA?4.8) upland surface water has been studied at bench-scale under constant pressure conditions. Coagulants used were aluminium sulphate, polyaluminium chloride, ferric chloride and ferric sulphate. Optimisation of coagulation parameters was carried by conventional jar testing. The R?c (specific cake resistance in m?2) values

A. T. Pikkarainen; S. J. Judd; J. Jokela; L. Gillberg



Perfluorinated Surfactants in Surface and Drinking Waters (9 pp)  

Microsoft Academic Search

Background, Aim and Scope  \\u000a In this paper recent results are provided of an investigation on the discovery of 12 perfluorinated surfactants (PS) in different\\u000a surface and drinking waters (Skutlarek et al. 2006 a, Skutlarek et al. 2006 b). In the last years, many studies have reported\\u000a ubiquitous distribution of this group of perfluorinated chemicals, especially perfluorooctane sulfonate (PFOS) and perfluorooctanoic

Martin Exner; Harald Färber



Allochthonous and autochthonous organic matter in surface waters in Karelia  

Microsoft Academic Search

A relationship between indirect chemical indices of organic matter content of surface waters and light absorption in the visible\\u000a and ultraviolet ranges is discussed. The allochthonous and autochthonous types of organic matter are found to essentially\\u000a differ in the rate of light absorption. Techniques are proposed for the calculation of the concentrations of allochthonous\\u000a and autochthonous organic matter by the

P. A. Lozovik; A. K. Morozov; M. B. Zobkov; T. A. Dukhovicheva; L. A. Osipova



Diagnostics of land surface spatial variability and water vapor flux  

Microsoft Academic Search

To assess the spatial variability of the water vapor (i.e., latent heat) flux LE, it is convenient to scale it with its equilibrium analog LEe. From an analysis of the data from the First International Satellite Land Surface Climatology Project (ISLSCP) Field Experiment, or FIFE, the spatial distribution of daily values of this dimensionless evaporation, alpha=LE\\/LEe, was found to be

Daoyi Chen; Wilfried Brutsaert



Perfluorooctanoate and Perfluorooctane Sulfonate Concentrations in Surface Water in Japan  

Microsoft Academic Search

Perfluorooctanoate and Perfluorooctane Sulfonate Concentrations in Surface Water in Japan: Norimitsu S AITO , et al. Institute for Environmental Sciences and Public Health of Iwate Prefecture—Perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) are synthetic surfactants used in Japan. An epidemiological study of workers exposed to PFOA revealed a significant increase in prostate cancer mortality. A cross-sectional study of PFOA-exposed workers showed

Norimitsu Saito; Kouji Harada; Kayoko Inoue; Kazuaki Sasaki; Takeo Yoshinaga; Akio Koizumi



The determination of vanadium in sea and surface waters  

Microsoft Academic Search

A simple and sensitive method for the determination of vanadium in sea and surface water is presented. The method is based\\u000a on preconcentration of vanadium on active charcoal at a pH 3.6±0.2, followed by instrumental neutron activation analysis of\\u000a the charcoal adsorbers and measurement of52V (T=3.71 m). The limit of the determination, which is set by the blank value of

H. A. van der Sloot; H. A. Das



Buoyant Surface Discharges into Water Bodies. II: Jet Integral Model  

Microsoft Academic Search

The near-field region of a buoyant surface discharge into water bodies often displays significant jet-like motions in form of free jets, shoreline-attached jets, and wall jets, respectively, as classified by the CORMIX3 expert system (see Part I). A new jet integral model CorSurf has been developed that addresses in a single formulation this entire spectrum of jet motions in both

Gerhard H. Jirka



Macro-Invertebrate Decline in Surface Water Polluted with Imidacloprid  

PubMed Central

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

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



Macro-invertebrate decline in surface water polluted with imidacloprid.  


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

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



Nitrate reducing activity pervades surface waters during upwelling  

NASA Astrophysics Data System (ADS)

Nitrate reducing activity (NRA) is known to be mediated by microaerophilic to anaerobic bacteria and generally occurs in the sub-surface waters. However, we hypothesize that NRA could become prominent in the surface waters during upwelling. Hence, we examined nitrification and nitrate reduction along with hydrographic and environmental parameters off Trivandrum and Kochi, south-west-India in June 2010. Shoaling isolines of temperature, density, and nutrients revealed the onset of upwelling off Trivandrum. Shoaling of these signatures was absent in the northern transect off Kochi. The degree of nutrient consumption (DNC) was low emphasizing the presence of newly upwelled water off Trivandrum. A significant increase in NRA (df = 1, p < 0.05) was observed off Trivandrum than at Kochi. Moreover, as hypothesized, NRA at Trivandrum was pronounced at the surface with a maximum rate of 0.85 (± 0.02) ?mol L1 h- 1 nearshore which was ~ 29 × higher than that at Kochi. Further, an inverse relationship between NRA and NO3- concentration (n = 34, r = - 0.415, p < 0.01) suggested transformation of the upwelled nutrient. Nitrification/NRA was ~ 10 × lower at 0.28 off Trivandrum indicating a discernible shift towards reduction. Such contribution from bacterial activity could be a response towards restoration of homeostasis.

Fernandes, Sheryl Oliveira; Halarnekar, Reena; Malik, Ashish; Vijayan, Vijitha; Varik, Sandesh; Kumari, Ritu; V. K., Jineesh; Gauns, Manguesh U.; Nair, Shanta; LokaBharathi, P. A.



ERTS imagery applied to Alaskan coastal problems. [surface water circulation  

NASA Technical Reports Server (NTRS)

Along the Alaska coast, surface water circulation is relatively easy to study with ERTS imagery. Highly turbid river water, sea ice, and fluvial ice have proven to be excellent tracers of the surface waters. Sea truth studies in the Gulf of Alaska, Cook Inlet, Bristol Bay, and the Bering Strait area have established the reliability of these tracers. ERTS imagery in the MSS 4 and 5 bands is particularly useful for observing lower concentrations of suspended sediment, while MSS 6 data is best for the most concentrated plumes. Ice features are most clearly seen on MSS 7 imagery; fracture patterns and the movement of specific floes can be used to map circulation in the winter when runoff is restricted, if appropriate allowance is made for wind influence. Current patterns interpreted from satellite data are only two-dimensional, but since most biological activity and pollution are concentrated near the surface, the information developed can be of direct utility. Details of Alaska inshore circulation of importance to coastal engineering, navigation, pollution studies, and fisheries development have been clarified with satellite data. ERTS has made possible the analysis of circulation in many parts of the Alaskan coast.

Wright, F. F.; Sharma, G. D.; Burbank, D. C.; Burns, J. J.



Remote surface water monitoring radio based telemetry system  

NASA Astrophysics Data System (ADS)

The Environmental Protection Department of EG&G Rocky Flats has designed and developed a unique Remote Surface Water Monitoring System using radio telemetry hardware and computer control software. The system is based on new technologies in microelectronics and environmental monitoring sensors. An engineering team, headed up by the Surface Water Division at EG&G, has proven that with careful evaluation of new technologies and hardware components, a reliable, cost effective and graphical user interface (GUI) system can be designed and installed. The network utilizes standard industrial control hardware and off-the-shelf components in order to meet several time requirements outlined by an Interagency Agreement (IAG) between the Department of Energy, the U.S. Environmental Protection Agency, and state and local authorities. In addition, the system had to meet tight environmental specifications and procedures. The Rocky Flats Plant is part of the U.S. Department of Energy Weapons Complex and is located near the Denver metropolitan area. The plant is required by law, and Interagency Agreement, to maintain strict environmental standards for surface water monitoring and discharge characteristics, including the requirement for utilization of best available technology.

Goodwin, W. L.; Baxter, D.



Capillary condensation of water between mica surfaces above and below zero-effect of surface ions.  


We have studied the capillary condensation of water from saturated vapor below 0 degrees C in the annular wedge-pore formed around two mica surfaces in contact in a surface force apparatus. The condensed water remains liquid down to at least -9 degrees C, and the measured condensate size is close to the predictions of a recent model for the dependence of the interfacial curvature of supercooled capillary condensates on temperature and surface tension. The small deviation observed may be accounted for by assuming that solute as K(2)CO(3) from the mica-condensate interface dissolves in the condensates and gives rise to an additional depression of the freezing point apart from that caused by the interface curvature. By contrast, measurements of the interface curvature at relative vapor pressures of 0.95-0.99 at 20 degrees C confirm a significantly larger deviation from the Kelvin equation. The magnitude of the deviation is in remarkable agreement with that calculated from the results of an earlier study of capillary condensation of water from a nonpolar liquid, also at T = 20 degrees C. Evidently, additional solute from the surrounding mica surface migrates into the condensates at room temperature. We conclude that the surface diffusion of ions on mica is much slower at subzero temperatures than at room temperature. PMID:19705887

Nowak, Dominika; Christenson, Hugo K



Surface-water data for Idaho, 1971-75  

USGS Publications Warehouse

Surface-water data collection began in Idaho in 1889 with the establishment of three gaging stations: Snake River at Eagle Rock (now Idaho Falls), Big Wood River near Hailey, and Bear River at Preston. Following passage of the National Reclamation Act of 1902, a notable increase in investigations of water resources began throughout the Western United States. Although Idaho enacted laws in 1903 to activate stream-gaging programs, it was no until 1909 that the State entered into a formal agreement with the U.S. Geological Survey from this work. Since that time, except for a hiatus from 1914-18, the Federal-State cooperative program of water-resources investigations has continued uninterrupted to the present.

Cordes, S.C.



Evaporating behaviors of water droplet on superhydrophobic surface  

NASA Astrophysics Data System (ADS)

We investigated the dynamic evaporating behaviors of water droplet on superhydrophobic surfaces with micropillars. Our experimental data showed that receding contact angles of the water droplet increased with the decreasing of the scale of the micropillars during evaporation, even though the solid area fractions of the microstructured substrates remained constant. We also experimentally found that the critical contact diameters of the transition between the Cassie-Baxter and Wenzel states are affected not only by the geometrical parameters of the microstructures, but also by the initial volume of the water droplet. The measured critical pressure is consistent with the theoretical model, which validated the pressure-induced impalement mechanism for the wetting state transition.

Hao, PengFei; Lv, CunJing; He, Feng



Urban areas impact on surface water quality during rainfall events  

NASA Astrophysics Data System (ADS)

Increasing population and welfare puts water management under stress, especially in what concerns water quality. Surface water properties are strongly linked with hydrological processes and are affected by stream flow variability. Changes in some chemical substances concentrations can be ascribed to different water sources. Runoff generated in urban areas is considered the main responsible for water quality degradation inside catchments. This poster presents the methodology and first results of a study that is being developed to assess the impact of urbanization on surface water quality, during rainfall events. It focuses on the Ribeira dos Covões catchment (620 ha) located in central Portugal. Due to its proximity to the Coimbra city in central region, the urban areas sprawled during the last decades. In 2008, urban areas represented 32% of the area. Recently a highway was constructed crossing the catchment and a technological industrial park is being build-up in the headwaters. Several water samples were collected at four different locations: the catchment outlet and in three sub-catchments with distinct urbanization patterns - Espírito Santo that represents a highly urbanized area (45%) located over sandstone, Porto do Bordalo with 30% of urbanized area located over limestone, and IParque, mainly forest and just downstream the disturbed technological industrial park construction area. The samples were collected at different times during rainfall events to monitor the variability along the hydrograph. Six monitoring campaigns were performed: two in April 2011, at the end of the winter period, and the others between October and November 2011, after the dry summer. The number of samples collected per monitoring campaign is variable according with rainfall pattern. Parameters such as pH, conductivity, turbidity and total suspended sediments were immediately analyzed. The samples were then preserved, after filtered (0.45µm), and later analyzed for dissolved chemical oxygen demand, total phosphorous, nitrogen (Kjeldahl, nitrate and ammonium), some cations and heavy metals, according with standard methods. In each monitored location there is a continuous-recording water-level that provides flow data. The rainfall data is monitored with a raingauge located at the catchment outlet. The results show that surface runoff affects stream water quality according with rainfall pattern. During rainfall events the rising limb flow is associated with an increase in suspended sediment concentration and turbidity, particularly at Iparque. In this sub-catchment, the deforestation and the topsoil removal associated with the technological industrial park construction, promotes suspended sediments growth ranging from 395% to 1645%, corresponding to peak concentrations of 1049mg/L and 3621mg/L, for similar rainfall amounts but with distinct intensities (0.4mm/5minutes and 1.2mm/5minutes, respectively). As regards to the monitored dissolved chemical properties, despite the variability, related with the hydrograph, the increase is much lower comparing with the suspended sediments. Generally, the values are higher at the catchment outlet, which can indicate that the contact time between rainfall and the surfaces before reach the water line affects water quality. This should be considered during urban planning to improve water quality and reduce environmental impacts with low investment.

Ferreira, C. S. S.; Soares, D.; Ferreira, A. J. D.; Costa, M. L.; Steenhuis, T. S.; Coelho, C. O. A.; Walsh, R. P. D.



Sea ice and surface water circulation, Alaskan continental shelf  

NASA Technical Reports Server (NTRS)

The author has identified the following significant results. Sediments contributed by the Copper River in the Gulf of Alaska are carried westward along the shore as a distinct plume. Oceanic water relatively poor in suspended material appears to intrude near Montague Island, and turbid water between Middleton Island and Kayak Island is the result of Ekman between transport. An anticlockwise surface water circulation is observed in this region. Ground truth data indicate striking similarity with ERTS-1 imagery obtained on October 12, 1972. Observations of ERTS-1 imagery reveal that various characteristics and distribution of sea ice in the Arctic Ocean can be easily studied. Formation of different types of sea ice and their movement is quite discrenible. Sea ice moves parallel to the cost in near shore areas and to the northerly direction away from the coast.

Wright, F. F. (principal investigator); Sharma, G. D.; Burns, J. J.



Sea, ice and surface water circulation, Alaskan continental shelf  

NASA Technical Reports Server (NTRS)

The author has identified the following significant results. ERTS-1 imagery has been extremely useful in understanding the tidal water movements in a large estuary such as Cook Inlet. As more imagery obtained during various tidal stages become available it appears that complex and fast changing micro-circulation patterns develop in various regions of Cook Inlet during each advancing and receding tide. More ERTS-1 synoptic imagery is needed to fully understand the effect of the approach of tidal front on the water movements in the various regions through the estuary. The conventional onboard ship data gathered during various cruises although revealed the overall circulation pattern in Cook Inlet but failed to show micro-subgyres which develop in various regions during each tide which are discernible on ther ERTS-1 imagery. Suspended load distribution in the Bering Sea during summer varies significantly. In areas of phytoplankton bloom and at the river mouths the suspended load is higher than the 1 mg/1 which is found over most areas. The influence of major rivers on temperature, salinity, and suspended load in surface water as well as at shallow depth is apparent. On the Bering shelf a strong pycnocline generally at depth 10-20 m is formed by surface fresh water flow which retains sediment in suspension over extended periods.

Sharma, G. D.; Wright, F. F.; Burns, J. J. (principal investigators)



Reconnaissance of selected PPCP compounds in Costa Rican surface waters.  


Eighty-six water samples were collected in early 2009 from Costa Rican surface water and coastal locations for the analysis of 34 pharmaceutical and personal care product compounds (PPCPs). Sampling sites included areas receiving treated and untreated wastewaters, and urban and rural runoff. PPCPs were analyzed using a combination of solid phase extraction and liquid chromatography tandem mass spectrometry. The five most frequently detected compounds were doxycycline (77%), sulfadimethoxine (43%), salicylic acid (41%), triclosan (34%) and caffeine (29%). Caffeine had the maximum concentration of 1.1 mg L(-1), possibly due to coffee bean production facilities upstream. Other compounds found in high concentrations include: doxycycline (74 ?g L(-1)), ibuprofen (37 ?g L(-1)), gemfibrozil (17 ?g L(-1)), acetominophen (13 ?g L(-1)) and ketoprofen (10 ?g L(-1)). The wastewater effluent collected from an oxidation pond had similar detection and concentrations of compounds compared to other studies reported in the literature. Waters receiving runoff from a nearby hospital showed higher concentrations than other areas for many PPCPs. Both caffeine and carbamazepine were found in low frequency compared to other studies, likely due to enhanced degradation and low usage, respectively. Overall concentrations of PPCPs in surface waters of Costa Rica are inline with currently reported occurrence data from around the world, with the exception of doxycycline. PMID:22048020

Spongberg, Alison L; Witter, Jason D; Acuña, Jenaro; Vargas, José; Murillo, Manuel; Umaña, Gerardo; Gómez, Eddy; Perez, Greivin



Effect of Radiant Energy on Near-Surface Water  

PubMed Central

While recent research on interfacial water has focused mainly on the few interfacial layers adjacent to the solid boundary, century-old studies have extensively shown that macroscopic domains of liquids near interfaces acquire features different from the bulk. Interest in these long-range effects has been rekindled by recent observations showing that colloidal and molecular solutes are excluded from extensive regions next to many hydrophilic surfaces [Zheng and Pollack Phys. Rev. E 2003, 68, 031408]. Studies of these aqueous “exclusion zones” reveal a more ordered phase than bulk water, with local charge separation between the exclusion zones and the regions beyond [Zheng et al. Colloid Interface Sci. 2006, 127, 19; Zheng and Pollack Water and the Cell: Solute exclusion and potential distribution near hydrophilic surfaces; Springer: Netherlands, 2006; pp 165–174], here confirmed using pH measurements. The main question, however, is where the energy for building these charged, low-entropy zones might come from. It is shown that radiant energy profoundly expands these zones in a reversible, wavelength-dependent manner. It appears that incident radiant energy may be stored in the water as entropy loss and charge separation. PMID:19827846

Chai, Binghua; Yoo, Hyok; Pollack, Gerald H.



Occurrence and distribution of polycyclic aromatic hydrocarbons in reclaimed water and surface water of Tianjin, China  

Microsoft Academic Search

Persistent organic pollutants (POPs) such as polycyclic aromatic hydrocarbons (PAHs) are of great concern due to their persistence, bioaccumulation and toxic effects. In this work, 16 PAHs included in the US Environmental Protection Agency's (EPA) priority pollutant list were analyzed using solid-phase extraction–gas chromatography–mass spectrometry (SPE–GC–MS) with a selected ion monitoring (SIM) mode. Reclaimed water and surface water sampling was

Zhonghong Cao; Yuqiu Wang; Yongmin Ma; Ze Xu; Guoliang Shi; Yuanyi Zhuang; Tan Zhu



Water-gas-shift reaction on metal nanoparticles and surfaces  

NASA Astrophysics Data System (ADS)

Density functional theory was employed to investigate the water-gas-shift reaction (WGS, CO +H2O?H2+CO2) on Au29 and Cu29 nanoparticles seen with scanning tunneling microscopy in model Au /CeO2(111) and Cu /CeO2(111) catalysts. Au(100) and Cu(100) surfaces were also included for comparison. According to the calculations of the authors, the WGS on these systems operate via either redox or associative carboxyl mechanism, while the rate-limiting step is the same, water dissociation. The WGS activity decreases in a sequence: Cu29>Cu(100)>Au29>Au(100), which agrees well with the experimental observations. Both nanoparticles are more active than their parent bulk surfaces. The nanoscale promotion on the WGS activity is associated with the low-coordinated corner and the edge sites as well as the fluxionality of the particles, which makes the nanoparticles more active than the flat surfaces for breaking the O-H bond. In addition, the role of the oxide support during the WGS was addressed by comparing the activity seen in the calculations of the authors for the Au29 and Cu29 nanoparticles and activity reported for X /CeO2(111) and X /ZnO(000?¯)(X =Cu or Au) surfaces.

Liu, Ping; Rodriguez, José A.



Organic acids enhance halogen activation on mildly acidic water surfaces  

NASA Astrophysics Data System (ADS)

Iodine species of marine origin are ubiquitous in the marine boundary layer (MBL). They are found over the open ocean (even in the absence of biogenic sources), the Antarctic coast, in rain, aerosols, ice, and snow, and participate in HOx/NOx cycles in the MBL. Surface-active organic acids coating the surface marine microlayer (SML) and marine aerosols could affect their chemical/physical properties. Recent field measurements show that organic acids represent ˜50% of the mass of fog waters collected in the US Gulf Coast. Here we report that I2(g) emissions from the heterogeneous reactions of O3(g) with I- (aq) are dramatically enhanced in the presence of surface-active organic acids under mildly acidic condition that are typical of fine marine aerosols. The amphiphilic weak carboxylic acids appear to promote I2(g) emissions by donating the interfacial protons more efficiently than water itself. We infer that the organic acids coating aerosol particles ejected from ocean's surface films could enhance I2(g) production in the MBL.

Hayase, S.; Enami, S.; Yabushita, A.; Kawasaki, M.; Hoffmann, M. R.; Colussi, A. J.



An integrable evolution equation for surface waves in deep water  

E-print Network

In order to describe the dynamics of monochromatic surface waves in deep water, we derive a nonlinear and dispersive system of equations for the free surface elevation and the free surface velocity from the Euler equations in infinite depth. From it, and using a multiscale perturbative methods, an asymptotic model for small-aspect-ratio waves is derived. The model is shown to be completely integrable. The Lax pair, the first conserved quantities as well as the symmetries are exhibited. Theoretical and numerical studies reveal that it supports periodic progressive Stokes waves which peak and break in finite time. Comparison between the limiting wave solution of the asymptotic model and classical irrotational results is performed.

R. Kraenkel; H. Leblond; M. A. Manna



Water budget and water-surface fluctuations, Great Salt Lake, Utah  

USGS Publications Warehouse

The water-budget equation for Great Salt Lakes is: Inflow = Outflow + or - Storage change. The average annual inflow for the period 1931-76 was about 2.9 million acre-feet; 1.9 million acre-feet from surface sources, about 900,000 acre-feet from direct precipitation, and about 75,000 acre-feet from ground water. The average annual outflow for the same period, all be evaportion, also was about 2.9 million acre-feet. Storage changes are computed on the basis of changes in the surface level of the lake. During the period of historic record, 1847-1978, the lake surface has fluctuated within a range of about 20 feet but has shown little overall change. The lake surface would have been about 5 feet higher in 1978 than it was in 1947 had there been no consumptive use of water caused by man 's activities in the lake basin. Since 1959 the lake has been divided into two parts by a railroad causeway, which has restricted the natural circulation. This has resulted in a difference of salinity and of surface level across the causeway. The difference in surface level between the two parts of the lake varies seasonally and annually and has been as much as 2.35 feet. (USGS)

Arnow, Ted



Surface and Ground Water Quality in Köprüören Basin (Kütahya), Turkey  

NASA Astrophysics Data System (ADS)

In this study, quality of the water resources in Köprüören Basin, located to the west of Kütahya city in western Anatolia, were investigated. The total catchment area of the basin is 275 km2 and it is located upstream of Kütahya and Eski?ehir plains. Therefore, besides 6,000 people residing in the basin, a much larger population will be impacted by the quality of surface and groundwater resources. Groundwater occurs under confined conditions in the limestones of Pliocene units. Groundwater flow is from north to south and south to north towards Kocasu stream, which flows to Enne Dam. The surface and ground water quality in this area are negatively affected by the mining activities. In the northern part of the area, there are coal deposits present in Miocene Tunçbilek formation. Ground waters in contact with the coal deposits contain low concentrations of arsenic (up to 30 µg/l). In the southern part, the only silver deposit of Turkey is present, which is developed in metamorphic basement rocks, Early Miocene volcanics and Pliocene units near Gümü?köy (Gümü? means silver, köy means village in Turkish). The amount of silver manufactured annually in this silver plant is huge and comprises about 1% of the World's Silver Production. The wastes, enriched in cyanide, arsenic, stibnite, lead and zinc, are stored in waste pools and there is extensive leakage of these heavy metals from these pools. Therefore, surface waters, soils and plants in the affected areas contain high concentrations of arsenic, stibnite and lead. The As, Sb, Pb and Zn concentrations are up to 733 µg/l, 158 µg/l, 48 µg/l, and 286 µg/l in surface waters (in dry season), 6180 ppm, 410 ppm, 4180 ppm, 9950 ppm in soils and 809 ppm, 399 ppm, 800 ppm, 2217 ppm in plants, respectively. Today, most of the As, Sb, Pb and Zn are absorbed by the soils and only a small part are dissolved in water. However, conditions might change in future leading to desorption of these contaminants. Therefore, necessary precautions should be undertaken immediately to protect the environment in the area.

Arslan, ?ebnem; Çelik, Mehmet; Erdem Dokuz, U?ur; Abadi Berhe, Berihu



Remote sensing of surface water for environmental flows  

NASA Astrophysics Data System (ADS)

Environmental flows represent water management activities that release flushes of water stored in dams on regulated rivers during dry periods. These flows aim to mimic natural flow and inundation regimes to maintain ecological health and function of rivers and wetlands. Assessment and understanding of the effectiveness of environmental flows requires quantification of temporal and spatial pattern of surface water and inundation dynamic in a synoptic yet detailed way and understanding dynamics of vegetation response to flooding. Here we focused on the on the entire Murray-Darling Basin (MDB) of Australia as a case study. The MDB is a large semi-arid region with scarce water resources, high hydroclimatic variability and competing water demands, impacted by climate change, altered flow regimes and land use changes. The basin covers 14% of the Australian continent and contains the nation's largest river system, important groundwater systems, and represents the most important agricultural area in the country. We used Landsat TM and ETM+ data time series to synoptically map the dynamic of surface water extent with an internally consistent algorithm over decades. Within the basin-wide study area we carried out a detailed investigation of the largest river red gum forest in the world, a key site for environmental flow and conservation management. Here we tracked the response of vegetation community condition to flooding across space and time. Results show high interannual variability in number and size of flooded areas. Vegetation community response to flooding varied in space and time and with vegetation types, densities and location relative to areas frequently inundated by environmental water release. Knowledge of the spatial and temporal dynamic of flooding and the response of vegetation communities to flooding is important for management of floodplain wetlands and vegetation communities and for investigating effectiveness of environmental flows and flow regimes in the MDB. Historic flood inundation extent mapped via remote sensing can be used to quantify spatially explicit changes in vegetation communities as outcomes of management scenarios and allow managers to evaluate landscape-scale changes in species distribution in response to water management decisions. This methodology is globally applicable and relevant to areas with competing water demands (e.g., Nile river basin in Northern Africa, Okavango River delta in southwest Africa, Mekong River Basin, Southeast Asia).

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




USGS Publications Warehouse

The US Geological Survey started, in a pilot phase, a program to provide nationally consistent information on the status and trends in the quality of the nation's fresh water. The program also intends to identify and describe the relationships between both the status and trends in water quality as they relate to natural factors, and the history of land-use, and land- and waste-management practices. The program is organized into hydrologically based study units and, for the study of surface water, involves a combination of fixed-station, synoptic and intensive study approaches. Network design considerations are discussed.

Hirsch, Robert M.



A new device for collecting time-integrated water samples from springs and surface water bodies  

USGS Publications Warehouse

A new device termed the 'seepage sampler' was developed to collect representative water samples from springs, streams, and other surface-water bodies. The sampler collects composite, time-integrated water samples over short (hours) or extended (weeks) periods without causing significant changes to the chemical composition of the samples. The water sample within the sampler remains at the ambient temperature of the water body and does not need to be cooled. Seepage samplers are inexpensive to construct and easy to use. A sampling program of numerous springs and/or streams can be designed at a relatively low cost through the use of these samplers. Transient solutes migrating through such flow systems, potentially unnoticed by periodic sampling, may be detected. In addition, the mass loading of solutes (e.g., agrichemicals) may be determined when seepage samplers are used in conjunction with discharge measurements.

Panno, S.V.; Krapac, I.G.; Keefer, D.A.



Epidemiology of Schistosoma mansoni infection and its relationship to snail distribution in a village at the Nile bank south to Cairo.  


The relationship between epidemiology of S. mansoni infection and snail distribution at a village, related to Guiza Governorate and lies south to Cairo, was investigated. A systematic random sample of houses was selected. All inhabitants of the houses were invited to share in the study. The Number examined was 704. Urine and stools were examined using Nucleopore filtration and standard Kato-Katz techniques, respectively. Snail collection was done from 35 sites along the water bodies related to the village. Snails collected were examined by cercariae shedding under light. Snail differentiation was done. The results showed that the prevalence of Schistosoma mansoni human infection was 25.1 % and GMEC was 2.4 +/- 5.5. Schistosoma haematobium infection was zero percent. Biomphlaria alexandrina snail infection rate was 3.7% with density equal 0.5 +/- 1.3. Bulinus truncatus snail infection rate was zero percent. The pattern of S. mansoni human infection was closely related to snail distribution and infection. Presence of a hybrid species of B. alexandrina and B. glabrata may explain the epidemiological pattern found in the studied village. PMID:16916052

Sayed, Hanan A; El-Ayyat, Afaf; Kader, Ahmed Abdel; Sabry, Hoda Y; Amer, Neimat M



Ground-water and surface-water flow and estimated water budget for Lake Seminole, southwestern Georgia and northwestern Florida  

USGS Publications Warehouse

Lake Seminole is a 37,600-acre impoundment formed at the confluence of the Flint and Chattahoochee Rivers along the Georgia?Florida State line. Outflow from Lake Seminole through Jim Woodruff Lock and Dam provides headwater to the Apalachicola River, which is a major supply of freshwater, nutrients, and detritus to ecosystems downstream. These rivers,together with their tributaries, are hydraulically connected to karst limestone units that constitute most of the Upper Floridan aquifer and to a chemically weathered residuum of undifferentiated overburden. The ground-water flow system near Lake Seminole consists of the Upper Floridan aquifer and undifferentiated overburden. The aquifer is confined below by low-permeability sediments of the Lisbon Formation and, generally, is semiconfined above by undifferentiated overburden. Ground-water flow within the Upper Floridan aquifer is unconfined or semiconfined and discharges at discrete points by springflow or diffuse leakage into streams and other surface-water bodies. The high degree of connectivity between the Upper Floridan aquifer and surface-water bodies is limited to the upper Eocene Ocala Limestone and younger units that are in contact with streams in the Lake Seminole area. The impoundment of Lake Seminole inundated natural stream channels and other low-lying areas near streams and raised the water-level altitude of the Upper Floridan aquifer near the lake to nearly that of the lake, about 77 feet. Surface-water inflow from the Chattahoochee and Flint Rivers and Spring Creek and outflow to the Apalachicola River through Jim Woodruff Lock and Dam dominate the water budget for Lake Seminole. About 81 percent of the total water-budget inflow consists of surface water; about 18 percent is ground water, and the remaining 1 percent is lake precipitation. Similarly, lake outflow consists of about 89 percent surface water, as flow to the Apalachicola River through Jim Woodruff Lock and Dam, about 4 percent ground water, and about 2 percent lake evaporation. Measurement error and uncertainty in flux calculations cause a flow imbalance of about 4 percent between inflow and outflow water-budget components. Most of this error can be attributed to errors in estimating ground-water discharge from the lake, which was calculated using a ground-water model calibrated to October 1986 conditions for the entire Apalachicola?Chattahoochee?Flint River Basin and not just the area around Lake Seminole. Evaporation rates were determined using the preferred, but mathematically complex, energy budget and five empirical equations: Priestley-Taylor, Penman, DeBruin-Keijman, Papadakis, and the Priestley-Taylor used by the Georgia Automated Environmental Monitoring Network. Empirical equations require a significant amount of data but are relatively easy to calculate and compare well to long-term average annual (April 2000?March 2001) pan evaporation, which is 65 inches. Calculated annual lake evaporation, for the study period, using the energy-budget method was 67.2 inches, which overestimated long-term average annual pan evaporation by 2.2 inches. The empirical equations did not compare well with the energy-budget method during the 18-month study period, with average differences in computed evaporation using each equation ranging from 8 to 26 percent. The empirical equations also compared poorly with long-term average annual pan evaporation, with average differences in evaporation ranging from 3 to 23 percent. Energy budget and long-term average annual pan evaporation estimates did compare well, with only a 3-percent difference between estimates. Monthly evaporation estimates using all methods ranged from 0.7 to 9.5 inches and were lowest during December 2000 and highest during May 2000. Although the energy budget is generally the preferred method, the dominance of surface water in the Lake Seminole water budget makes the method inaccurate and difficult to use, because surface water makes up m

Dalton, Melinda S.; Aulenbach, Brent T.; Torak, Lynn J.



Micro scale exchange processes between surface and subsurface water  

NASA Astrophysics Data System (ADS)

Data are presented of experiments with turbulent open channel flow over rough surfaces and large relative submergence, which are conducted in two series with different geometric boundary conditions. During the experiments an oscillating fluid motion in the uppermost filter layer is visualised by the injection of a tracer dye. It is shown that this oscillating fluid motion is driven by highly unsteady pressure gradients and contributes to in- and outflow at the interface between surface and subsurface flow, but its intensity decays rapidly with increasing filter depth. About 90% of the high frequency pressure fluctuations measured at the surface of the filter layer are damped at a filter depth of about 4-5 times the average gravel size of the surface of the bed. It is assumed that the considered high frequency oscillations originate from turbulent pressure fluctuations in the near bed layer. The exponential function that fits the decay of turbulent pressure fluctuations implies a length scale of about 12 times the geometric roughness height as dominant wavelength of a turbulent structure, which imposes a pressure fluctuation on a riverbed. The presented results reveal that micro scale advective transport between surface and subsurface flow occurs separate from diffusive effects and should be considered for the transfer of solutes like dissolved oxygen from fresh to subsurface water and its respiration in the uppermost sediment of aquatic beds.

Vollmer, Stefan; Ramos, Francisco de los Santos; Daebel, Helge; Kühn, Gregor



Digenean trematode infections of native freshwater snails and invasive Potamopyrgus antipodarum in the Grand Teton National Park/John D. Rockefeller Memorial Parkway Area.  


Outside its native range, the invasive New Zealand mud snail (NZMS), Potamopyrgus antipodarum, is rarely reported to harbor parasites. To test this observation, 7 sites along the Snake River and Polecat Creek in the Grand Teton National Park/John D Rockefeller Memorial Parkway area (Wyoming) were surveyed for native aquatic snails, NZMS, and associated digenean trematodes, in July 2005. At 6 sites, native snails harbored patent digenean infections; within 2 hr, < or =10% of lymnaeid snails shed furcocercariae or xiphidiocercariae, and < or =42% of physid snails released furcocercariae or echinostome cercariae. Partial 18S rDNA sequences were recovered from several furcocercariae. Potamopyrgus antipodarum was present at, and collected from, 5 sites. Polymerase chain reaction assays targeting digenean rDNA sequences in DNA extracted from pools of 150 NZMS snails did not detect parasites. The examination of 960 NZMS by overnight shedding yielded 1 occurrence of (surface-encysted) metacercariae of an unclassified notocotylid (based on 18S and 28S rDNA sequences). The dissection of 150 ethanol-fixed NZMS (30/site) revealed 2 types of digenean metacercariae encysted in tissues of 5 snails from Polecat Creek. Thus, invasive NZMS may serve as first and second intermediate host for digenean parasites. PMID:18576875

Adema, C M; Lun, C-M; Hanelt, B; Seville, R S



Allying with armored snails: the complete genome of gammaproteobacterial endosymbiont.  


Deep-sea vents harbor dense populations of various animals that have their specific symbiotic bacteria. Scaly-foot gastropods, which are snails with mineralized scales covering the sides of its foot, have a gammaproteobacterial endosymbiont in their enlarged esophageal glands and diverse epibionts on the surface of their scales. In this study, we report the complete genome sequencing of gammaproteobacterial endosymbiont. The endosymbiont genome displays features consistent with ongoing genome reduction such as large proportions of pseudogenes and insertion elements. The genome encodes functions commonly found in deep-sea vent chemoautotrophs such as sulfur oxidation and carbon fixation. Stable carbon isotope ((13)C)-labeling experiments confirmed the endosymbiont chemoautotrophy. The genome also includes an intact hydrogenase gene cluster that potentially has been horizontally transferred from phylogenetically distant bacteria. Notable findings include the presence and transcription of genes for flagellar assembly, through which proteins are potentially exported from bacterium to the host. Symbionts of snail individuals exhibited extreme genetic homogeneity, showing only two synonymous changes in 19 different genes (13?810 positions in total) determined for 32 individual gastropods collected from a single colony at one time. The extremely low genetic individuality in endosymbionts probably reflects that the stringent symbiont selection by host prevents the random genetic drift in the small population of horizontally transmitted symbiont. This study is the first complete genome analysis of gastropod endosymbiont and offers an opportunity to study genome evolution in a recently evolved endosymbiont. PMID:23924784

Nakagawa, Satoshi; Shimamura, Shigeru; Takaki, Yoshihiro; Suzuki, Yohey; Murakami, Shun-ichi; Watanabe, Tamaki; Fujiyoshi, So; Mino, Sayaka; Sawabe, Tomoo; Maeda, Takahiro; Makita, Hiroko; Nemoto, Suguru; Nishimura, Shin-Ichiro; Watanabe, Hiromi; Watsuji, Tomo-o; Takai, Ken



Mate desertion in the snail kite  

USGS Publications Warehouse

Mate desertion during the breeding cycle was documented at 28 of 36 (78%) snail kite, Rostrhamus sociabilis nests in Florida between 1979 and 1983. Offspring mortality occurred at only one deserted nest, however. Parents that were deserted by their mates continued to care for their young until independence (3?5 additional weeks) and provided snails at a rate similar to that of both parents combined before desertion. Males and females deserted with nearly equal frequency, except in 1982 when more females deserted. No desertion occurred during drought years, whereas desertion occurred at nearly every nest during favourable conditions. The occurrence of mate desertion was generally related to indirect measures of snail abundance: foraging range, snail delivery rates to the young and growth rates. Small broods were deserted more frequently by females than by males and tended to be deserted earlier than large ones. After desertion, deserters had the opportunity to re-mate and nest again since breeding seasons were commonly lengthy, but whether they did so was impossible to determine conclusively in most cases. The deserted bird sometimes incurred increased energetic costs and lost breeding opportunities during periods of monoparental care.

Beissinger, S.R.; Snyder, N.F.R.



Novel pharmacological targets from Indian cone snails.  


The oceans are a source of combinatorial library of unique natural products, 'not found in the terrestrial environment'. Marine invertebrates such as sponges, molluscs, bryozoans, tunicates (Urochordata) and their associated microorganisms are the major representatives of promising bioactive compounds. Among these, the predatory molluscan cone snails have evolved with highly structured small and complex array of peptides (more than 50,000) linked to their prey capture and defence. These peptides have become a valuable source of neuro pharmacological targets as many of them selectively modulate ion channels and transporters. A group of scientists from United States, Europe, Australia, Israel and China have been characterized drugs for neuropathic pain and pharmacological targets from the peptides of a few cone snail species. Several are now in Clinical and preclinical development. Less than 1% of the cono peptides are pharmacologically characterized. India has a diversity of 20-30% of total cone snail species distributed worldwide. A group of Indian Scientists have made promising drug discovery programs from Conus peptides. This review will focus on the Conus peptides from Indian cone snails species, their neuro pharmacological targets and future directions. PMID:21222583

Ramasamy, M Santhana; Manikandan, S



Surface Reactions of Ferritic Steel Particles Atomized with Water or Mixtures of Water-Additive  

NASA Astrophysics Data System (ADS)

The production of metallic powders has been a very important industrial activity for many years. In this work, the water or a mixture water-additive atomization process has been used. During the production of steel particles by water atomization these particles are coated with a surface oxide layer. With particles under these conditions it is very difficult to obtain final products with high mechanical properties, so that it is desirable to diminish the surface oxide as much as possible. Experimental tests to know if the use of additives as corrosion inhibitors, used to avoid steel oxidation at room temperature, could modify the properties of particles during the manufacture of an AISI C1115 steel by water atomization were carried out. In order to improve the knowledge of the chemical surface reactions, characterization of the powder surfaces and interfaces of metal matrix/oxide layer by means of Energy Dispersive Spectroscopy (EDS), Scanning Electron Microscopy (SEM), X-ray Diffraction and Auger Electron Spectroscopy (AES) was carried out.

Estrada, J. L.; Godinez, J.; Herrera, H.


Novel Americium Treatment Process for Surface Water and Dust Suppression Water  

Microsoft Academic Search

The Rocky Flats Environmental Technology Site (RFETS), a former nuclear weapons production plant, has been remediated under CERCLA and decommissioned to become a National Wildlife Refuge. The site conducted this cleanup effort under the Rocky Flats Cleanup Agreement (RFCA) that established limits for the discharge of surface and process waters from the site. At the end of 2004, while a

E. W. Tiepel; P. Pigeon; S. Nesta; J. Anderson



Surface water and ground-water thresholds for maintaining Populus– Salix forests, San Pedro River, Arizona  

Microsoft Academic Search

Ground-water and surface flow depletions are altering riparian ecosystems throughout the southwestern United States, and have contributed to the decline of forests of the pioneer trees Populus fremontii (Fremont cottonwood) and Salix gooddingii (Goodding willow). On some rivers, these forests have been replaced by shrublands of Tamarix ramosissima (tamarisk), a drought-tolerant species from Eurasia. The physiological response of these three

S. J. Lite; J. C. Stromberg



High prevalence of enteric viruses in untreated individual drinking water sources and surface water in Slovenia.  


Waterborne infections have been shown to be important in outbreaks of gastroenteritis throughout the world. Although improved sanitary conditions are being progressively applied, fecal contaminations remain an emerging problem also in developed countries. The aim of our study was to investigate the prevalence of fecal contaminated water sources in Slovenia, including surface waters and groundwater sources throughout the country. In total, 152 water samples were investigated, of which 72 samples represents groundwater from individual wells, 17 samples from public collection supplies and 63 samples from surface stream waters. Two liters of untreated water samples were collected and concentrated by the adsorption/elution technique with positively charged filters followed by an additional ultracentrifugation step. Group A rotaviruses, noroviruses (genogroups I and II) and astroviruses were detected with real-time RT-PCR method in 69 (45.4%) out of 152 samples collected, of which 31/89 (34.8%) drinking water and 38/63 (60.3%) surface water samples were positive for at least one virus tested. In 30.3% of drinking water samples group A rotaviruses were detected (27/89), followed by noroviruses GI (2.2%; 2/89) and astroviruses (2.2%; 2/89). In drinking groundwater samples group A rotaviruses were detected in 27 out of 72 tested samples (37.5%), genogroup I noroviruses in two (2.8%), and human astroviruses in one (1.4%) samples. In surface water samples norovirus genogroup GII was the most frequently detected (41.3%; 26/63), followed by norovirus GI (33.3%; 21/63), human astrovirus (27.0%; 17/63) and group A rotavirus (17.5%; 11/63). Our study demonstrates relatively high percentage of groundwater contamination in Slovenia and, suggests that raw groundwater used as individual drinking water supply may constitute a possible source of enteric virus infections. In the future, testing for enteric viruses should be applied for drinking water sources in waterborne outbreaks. PMID:21665537

Steyer, Andrej; Torkar, Karmen Godi?; Gutiérrez-Aguirre, Ion; Poljšak-Prijatelj, Mateja



Freak waves at the surface of deep water  

NASA Astrophysics Data System (ADS)

In the paper ([1]) authors applied canonical transformation to water wave equation not only to remove cubic nonlinear terms but to simplify drastically fourth order terms in Hamiltonian. After the transformation well-known but cumbersome Zakharov equation is drastically simplified and can be written in X-space in compact way. This new equation is very suitable for analytic study as well as for numerical simulation. At the same time one of the important issues concerning this system is the question of its integrability. The first part of the work is devoted to numerical and analytical study of the integrability of the equation obtained in ([1]). In the second part we present generalization of the improved Zakharov equation for the 'almost' 2-D water waves at the surface of deep water. When considering waves slightly inhomogeneous in transverse direction, one can think in the spirit of Kadomtsev-Petviashvili equation for Korteveg-de-Vries equation taking into account weak transverse diffraction. Equation can be written instead of classical variables ?(x,y,t) and ?(x,y,t) in terms of canonical normal variable b(x,y,t). This equation is very suitable for robust numerical simulation. Due to specific structure of nonlinearity in the Hamiltonian the equation can be effectively solved on the computer. It was applied for simulation of sea surface waving including freak waves appearing. References [1] A.I. Dyachenko and V.E. Zakharov, Europ. J. Mech. B 32, 17 (2012)

Kachulin, Dmitriy; Dyachenko, Alexander; Zakharov, Vladimir



Soil and water characteristics of a young surface mine wetland  

NASA Astrophysics Data System (ADS)

Coal companies are reluctant to include wetland development in reclamation plans partly due to a lack of information on the resulting characteristics of such sites. It is easier for coal companies to recreate terrestrial habitats than to attempt experimental methods and possibly face significant regulatory disapproval. Therefore, we studied a young (10 years) wetland on a reclaimed surface coal mine in southern Illinois so as to ascertain soil and water characteristics such that the site might serve as a model for wetland development on surface mines. Water pH was not measured because of equipment problems, but evidence (plant life, fish, herpetofauna) suggests suitable pH levels. Other water parameters (conductivity, salinity, alkalinity, chloride, copper, total hardness, iron, manganese, nitrate, nitrite, phosphate, and sulfate) were measured, and only copper was seen in potentially high concentrations (but with no obvious toxic effects). Soil variables measured included pH, nitrate, nitrite, ammonia, potassium, calcium, magnesium, manganese, aluminum, iron, sulfate, chloride, and percent organic matter. Soils were slightly alkaline and most parameters fell within levels reported for other studies on both natural and manmade wetlands. Aluminum was high, but this might be indicative more of large amounts complexed with soils and therefore unavailable, than amounts actually accessible to plants. Organic matter was moderate, somewhat surprising given the age of the system.

Andrew Cole, C.; Lefebvre, Eugene A.



Horizon effects with surface waves on moving water  

E-print Network

Surface waves on a stationary flow of water are considered, in a linear model that includes the surface tension of the fluid. The resulting gravity-capillary waves experience a rich array of horizon effects when propagating against the flow. In some cases three horizons (points where the group velocity of the wave reverses) exist for waves with a single laboratory frequency. Some of these effects are familiar in fluid mechanics under the name of wave blocking, but other aspects, in particular waves with negative co-moving frequency and the Hawking effect, were overlooked until surface waves were investigated as examples of analogue gravity [Sch\\"utzhold R and Unruh W G 2002 Phys. Rev. D 66 044019]. A comprehensive presentation of the various horizon effects for gravity-capillary waves is given, with emphasis on the deep water/short wavelength case kh>>1 where many analytical results can be derived. A similarity of the state space of the waves to that of a thermodynamic system is pointed out.

Germain Rousseaux; Philippe Maissa; Christian Mathis; Pierre Coullet; Thomas G. Philbin; Ulf Leonhardt



SWOT, The Surface Water and Ocean Topography Satellite Mission (Invited)  

NASA Astrophysics Data System (ADS)

Surface fresh water is essential for life, yet we have surprisingly poor knowledge of its variability in space and time. Similarly, ocean circulation fundamentally drives global climate variability, yet the ocean current and eddy field that affects ocean circulation and heat transport at the sub-mesoscale resolution and particularly near coastal and estuary regions, is poorly known. About 50% of the vertical exchange of water properties (nutrients, dissovled CO2, heat, etc) in the upper ocean is taking place at the sub-mesoscale. Measurements from the Surface Water and Ocean Topography satellite mission (SWOT) will make strides in understanding these processes and improving global ocean models for studying climate change. SWOT is a swath-based interferometric-altimeter designed to acquire elevations of ocean and terrestrial water surfaces at unprecedented spatial and temporal resolutions. The mission will provide measurements of storage changes in lakes, reservoirs, and wetlands as well as estimates of discharge in rivers. These measurements are important for global water and energy budgets, constraining hydrodynamic models of floods, carbon evasion through wetlands, and water management, especially in developing nations. Perhaps most importantly, SWOT measurements will provide a fundamental understanding of the spatial and temporal variations in global surface waters, which for many countries are the primary source of water. An on-going effort, the “virtual mission” (VM) is designed to help constrain the required height and slope accuracies, the spatial sampling (both pixels and orbital coverage), and the trade-offs in various temporal revisits. Example results include the following: (1) Ensemble Kalman filtering of VM simulations recover water depth and discharge, reducing the discharge RMSE from 23.2% to 10.0% over an 84-day simulation period, relative to a simulation without assimilation. (2) Ensemble-based data assimilation of SWOT like measurements yields bathymetric slope and depth to within 3.0 microradians and 50 cm, respectively. (3) SWOT measurements of storage changes in lakes larger than 1 km2 will have relative errors generally less than 5% whereas errors for one-hectare size lakes will be about 20%. (4) SWOT estimates of discharge compared to a one-year model-based “truth” data set suggest that instantaneous discharge estimates will have a median relative RMSE of 10.9% and that 86% of all instantaneous errors will be less than 25%. (5) Based on a global distribution of gauge-based discharge and candidate SWOT orbits with varying spatial and temporal sampling, SWOT errors in instantaneous discharge will be less than 25% for rivers wider than 50 m, whereas errors in monthly discharge will be less than 20% for rivers with drainage areas larger than 7000 km2. (6) We estimate that currently available satellite nadir altimetry data cannot monitor more than 15% of the global lake volume variation, whereas from 50% to more than 65% of the global lake volume variation will be observed by SWOT.

Alsdorf, D.; Andreadis, K.; Bates, P. D.; Biancamaria, S.; Clark, E.; Durand, M. T.; Fu, L.; Lee, H.; Lettenmaier, D. P.; Mognard, N. M.; Moller, D.; Morrow, R. A.; Rodriguez, E.; Shum, C.



Groundwater and surface water discharge from an abandoned tailings impoundment: Implications for watershed water quality  

NASA Astrophysics Data System (ADS)

Release of acid drainage from mine-waste disposal areas is a problem of international scale. Drainage from sulfide-rich waste can result in contaminated surface waters, directly through surface runoff and indirectly, from discharge of contaminated groundwater flow. Camp Lake, located in Northern Manitoba, receives both direct and indirect drainage from an abandoned tailings impoundment, which has severely affected the quality of the downstream watershed. Nearly a century of sulfide oxidation at this mine site has resulted in extremely high concentrations of oxidation products in the surface water and groundwater discharging from the two tailings impoundments, both of which flow into an adjacent semi-isolated shallow bay in Camp Lake. The incorporation of these aqueous effluents has altered the composition of the lake water, which in turn has modified the physical limnology of the lake. The various sources of water and solutes to the lake (surface inflows, perched water table, primary water table) contribute varying concentrations of metals to the overall contaminant loadings to the lake, and can be characterized by distinct 3H, ?18O, and ?2H compositions. Geochemical profiles of the water column indicate that, despite its shallow depth (6 m), the bay is stratified throughout the year. The greatest accumulation of dissolved metals and SO4 is in the lower portion of the water column, with concentrations up to 8500 mg/L Fe, 20,000 mg/L SO4, 30 mg/L Zn, and 100 mg/L Al, including elevated concentrations of Cu, Cd, Pb, and Ni. This stratification is mirrored in the ?18O, ?2H and d-excess profiles within the lake water column, with an evaporatively enriched surface layer overlying the isotopically lighter, higher d-excess hypolimnion. Despite meromictic conditions and very high solute concentrations being limited to the semi-isolated bay, the annual loadings of acid, sulfate, and metals from Camp Lake to the adjacent lake are extremely large, and fluctuate seasonally with freezing and thawing of the lake.

Moncur, M. C.; Ptacek, C. J.; Blowes, D. W.; Birks, S. J.



Cue reliability, risk sensitivity and inducible morphological defense in a marine snail.  


Reliable cues that communicate current or future environmental conditions are a requirement for the evolution of adaptive phenotypic plasticity, yet we often do not know which cues are responsible for the induction of particular plastic phenotypes. I examined the single and combined effects of cues from damaged prey and predator cues on the induction of plastic shell defenses and somatic growth in the marine snail Nucella lamellosa. Snails were exposed to chemical risk cues from a factorial combination of damaged prey presented in isolation or consumed by predatory crabs (Cancer productus). Water-borne cues from damaged conspecific and heterospecific snails did not affect plastic shell defenses (shell mass, shell thickness and apertural teeth) or somatic growth in N. lamellosa. Cues released by feeding crabs, independent of prey cue, had significant effects on shell mass and somatic growth, but only crabs consuming conspecific snails induced the full suite of plastic shell defenses in N. lamellosa and induced the greatest response in all shell traits and somatic growth. Thus the relationship between risk cue and inducible morphological defense is dependent on which cues and which morphological traits are examined. Results indicate that cues from damaged conspecifics alone do not trigger a response, but, in combination with predator cues, act to signal predation risk and trigger inducible defenses in this species. This ability to "label" predators as dangerous may decrease predator avoidance costs and highlights the importance of the feeding habits of predators on the expression of inducible defenses. PMID:19882173

Bourdeau, Paul E



Effects of 17?-methyltestosterone on the reproduction of the freshwater snail Biomphalaria glabrata.  


17-?-methyltestosterone (MT) is a synthetic hormone used in fish hatcheries to induce male monosex. Snails hold promise as possible test models to assess chemicals acting on the endocrine system. Biomphalaria glabrata is an aquatic gastropod mollusk (Pulmonata, Planorbidae) that can be easily maintained in aquaria, predisposing the species for use in ecotoxicological testing. This study evaluated the reproductive effects of MT on B. glabrata by examining histological changes and its reproductive performance. Ten snails per group were exposed for 4 weeks to different concentrations of MT (0.01, 0.1, and 1.0 mg/L). The total number of laid eggs, egg mass per group, size of type V oocytes, and production of spermatozoids were determined. Reproduction of B. glabrata was affected by MT. At the lowest concentration (0.01 mg/L), MT caused a statistically significant increase in the number of egg mass per snail compared with controls unexposed to MT. Histopathology analyses showed an increase in the sperm production at the higher MT concentrations of 0.1 and 1.0 mg/L. Chromatographic analyses of water samples showed that MT concentrations rapidly declined within a 96-h period. These results highlight the importance of giving more support to regulatory authorities, since MT is not registered for use on fish hatcheries in many countries around the world. Wastewater from fish farms discharged into aquatic ecosystems should be monitored for MT residues, since its presence could compromise the reproduction of other native snail species. PMID:24615026

Rivero-Wendt, C L G; Borges, A C; Oliveira-Filho, E C; Miranda-Vilela, A L; Ferreira, M F N; Grisolia, C K



Cold hardiness abilities vary with the size of the land snail Cornu aspersum.  


The land snail Cornu aspersum (syn. Helix aspersa) living in Brittany (France) can be considered partially freezing tolerant as it possesses a low ability to supercool and a limited capacity to bear freezing of its body tissues. The absence of a marked cold hardiness strategy permits the emphasis of the role of parameters such as individual size or water mass (W(M)) contained by the organism. Adult snails (shell diameter 30-32 mm) had a supercooling ability, about 1-1.5 degrees C lower than that of immatures (shell diameter 12-20 mm) and survived longer to an exposure to -5 degrees C, with an Lt(50) comprised between 6.0 and 9.8 h against 2.6 to 4.2 h for immature snails. This better ability to bear freezing was explained by the faster dynamic of body ice formation observed in small individuals, which attained ice lethal quantity more rapidly. At the species level, large snails will then tend to be more tolerant to freezing and small ones to be freezing avoidant, a statement also observable at the phylum level. PMID:15528169

Ansart, Armelle; Vernon, Philippe



Novel Americium Treatment Process for Surface Water and Dust Suppression Water  

SciTech Connect

The Rocky Flats Environmental Technology Site (RFETS), a former nuclear weapons production plant, has been remediated under CERCLA and decommissioned to become a National Wildlife Refuge. The site conducted this cleanup effort under the Rocky Flats Cleanup Agreement (RFCA) that established limits for the discharge of surface and process waters from the site. At the end of 2004, while a number of process buildings were undergoing decommissioning, routine monitoring of a discharge pond (Pond A-4) containing approximately 28 million gallons of water was discovered to have been contaminated with a trace amount of Americium-241 (Am-241). While the amount of Am-241 in the pond waters was very low (0.5 - 0.7 pCi/l), it was above the established Colorado stream standard of 0.15 pCi/l for release to off site drainage waters. The rapid successful treatment of these waters