Note: This page contains sample records for the topic surface water snail from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

Water snails  

NSDL National Science Digital Library

Water snails have a shell for protection. They have two tentacles, a foot, and a head and a tail region. Water snails have eyes at the base of their sensory stalks. The stalks are used to smell and feel around the snail's environment.

Scott Bauer (USDA;ARS)

2005-08-03

2

Apple Snail: a Bio Cleaner of the Water Free Surface  

Microsoft Academic Search

Oil spills from tankers represent a threat for shorelines and marine life. Despite continuing research, there has been little change in the fundamental technology for dealing with oil spills. An experimental investigation of the feeding strategy of Apple snails from the water free surface, called surface film feeding, is being studied motivated by the need to develop new techniques to

Golnaz Bassiri

2005-01-01

3

The microstructures of biomineralized surfaces: a spectroscopic study on the exoskeletons of fresh water (Apple) snail, Pila globosa  

NASA Astrophysics Data System (ADS)

In view of the importance in understanding biomineralization processes in different molluskan species, the common fresh water apple snail Pila globosa in Indian origin was taken to explore its mineralized exoskeleton structures. The detailed structural studies of the exoskeletons of P. globosa have been undertaken. The isolated layers present in these shells were studied by electron paramagnetic resonance (EPR), optical absorption, and infrared spectral techniques. The EPR spectra of the organic protein layer periostracum show the characteristic signals corresponding to Fe 3+ ions at g=4.1 and 2.0. The EPR spectra of the ostracum (middle) layer at room temperature gives a complicated spectrum consisting of a number of Mn 2+ signals of at least three sets due to the aragonite nature of the material. The results indicate the presence of the multivalent manganese ions, which undergo the redox mechanisms. The thermal variation of the EPR spectra show marked effect on these samples both in g-values and the basic spectral pattern.

Prasuna, C. P. Lakshmi; Narasimhulu, K. V.; Gopal, N. O.; Rao, J. Lakshmana; Rao, T. V. R. K.

2004-08-01

4

Treatment Of Waste Water From Food Industry Using Snail Shell  

Microsoft Academic Search

Waste water from a food- factory was characterized and treated using snail shell. The aim was to find out the effectiveness of snail shell as a coagulant in waste water treatment. The result of the parameter studied before and after treatment, shows a change in color from dark brown before treatment to light brown after treatment, there was reduction in

E. O Jatto; I. O Asia; E. E Egbon; J. O Otutu; M. E Chukwuedo; C. J Ewansiha

2010-01-01

5

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

PubMed

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

2012-05-31

6

Wet Adhesion and Adhesive Locomotion of Snails on Anti-Adhesive Non-Wetting Surfaces  

PubMed Central

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.

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

2012-01-01

7

Exploring the Temporal Effects of Seasonal Water Availability on the Snail Kite of Florida  

Microsoft Academic Search

The Florida snail kite (Rostrhamus sociabilis) is an endangered raptor that occurs as an isolated population, currently of about 2,000 birds, in the wetlands of southern\\u000a and central Florida, USA. Its exclusive prey species, the apple snail (Pomacea paludosa) is strongly influenced by seasonal changes in water abundance. Droughts during the snail kite breeding season have a direct\\u000a negative effect

WOLF M. MOOIJ; JULIEN MARTIN; WILEY KITCHENS; DONALD DEANGELIS

2007-01-01

8

Surface Water  

NSDL National Science Digital Library

Surface Water: This is the USGS Water Science for School's page and the topic is surface water. Explained are surface water use, importance, rivers and streams. Also answers the questions of what is runoff, how is the flow of a stream measured, how does stream height relate to flow and much, much more.

2008-06-05

9

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

PubMed

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

2002-08-01

10

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

2008-01-01

11

[Causation of Oncomelania snail recurrence in water-net areas of Jiaxing City].  

PubMed

From 2004 to 2012, fourteen Oncomelania snail remaining spots with an area of 31.954 hm2 were found in the historical snail areas of Xiuzhou District, Jiaxing City. The recurrence time of snails was 5-39 years. These spots were mainly distributed in the complex breeding environments, such as paddy fields (37.15%), nursery stock fields (36.93%), mulberry fields (16.09%), and ditches (6.82%). A total of 8 370 snails were dissected and no infected ones were found. It suggests that the nursery stock fields should be included in the key points for snail surveillance in water-net areas where schistosomiasis transmission has been interrupted. PMID:23593854

Xu, Hui-Qing; Zhu, Pei-Hua; Mo, Gen-Qiang

2012-12-01

12

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.

2003-01-01

13

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.

2003-01-01

14

Susceptibility of Iraqi fresh water snails to infection with Schistosoma haematobium and Schistosoma mansoni Egyptian strains.  

PubMed

A great number of Egyptian workers and farmers are seeking settlement in Iraq and some of them proved to have either Schistosoma Haematobium (S.h.) or Schistosoma mansoni (S.m) or even mixed infection. Besides, there is the possibility that some of the Iraqi fresh water snails may prove to be susceptible to infection by one or both of the Schistosoma Egyptian strains. The present study deals with investigations on the susceptibility of Iraqi B. truncatus, Gyranaulus ehrenbergi, Physa c.f. fontinalis, Lymnea lagetis, Melanoides tuberculata and Melanopsis nodes by these parasites. Egyptian S. haematobium but not Egyptian S. mansoni infect Iraqi B. truncatus and both proved to be unable to infect any of the other snails included in the study. Yet, the number of cercariae shedded by B. truncatus snails infected with the Egyptian S. haematobium strain, was much less that the number of cercariae shedded by these snails when infected with the Iraqi S. Haematobium strain. PMID:555668

Wajdi, N A; Hussain, W I; El-Hawary, M F

1979-01-01

15

Effects of acidic water on freshwater snails: results from a study of 1000 lakes throughout Norway.  

PubMed

This paper summarizes some results from a monograph which focused on ecological and biogeographical aspects of the biota in Norwegian lakes and rivers with particular reference to the snail fauna. Field studies were made in the course of 20 summers within the period of 1953-1987. Acidic water is the main reason why snails are absent from some 4000 lakes in a low-calcium area in southern Norway ('Acid south'). This area is heavily influenced by acidic precipitation. Snails were not detected in lakes with pH below 5.2. In one lake, three snail species disappeared in parallel with acidification from pH 5.2 to 4.2. The calcium level modified the effect of low pH. PMID:15091938

Økland, J

1992-01-01

16

The Molluscicidal Activity of Melia azadirchta on The Fresh water snail Physa acuta ( Draparnaud , 1805 ) A snail Associated with habitat of Lymnaea auricularia ( L )  

Microsoft Academic Search

The molluscicidal effect of Melia azadirachta was evaluated against the fresh water snail Physa acuta at juvenile freshly hatched stage. Calculating values of different concentrations ( Lc50 - Lc90 ) showed that melia was toxic against juvenile stage . The use of Melia azadirchta fruit extract was considered as an effective control method for Physa acuta in Mosul area .

Talib Hussen Ali; Azhar Abul; Jabbar Hamed

17

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

PubMed

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

2005-12-01

18

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

PubMed

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

2009-04-01

19

Fecal bacterial contamination in natural water reservoirs as an indicator of seasonal infection by Opisthorchis viverrini in snail intermediate hosts.  

PubMed

Opisthorchis viverrini, a carcinogenic liver fluke, requires Bithynia snails as the first intermediate host, which release cercariae after ingesting fluke eggs from contaminated water. Fecal bacterial contamination and O. viverrini-infected Bithynia snails were investigated in samples collected from natural water reservoirs in Ban Phai, Chonnabot and Muang Districts (Ban Lerngpeuy) in Khon Kaen Province, northeast Thailand, where there is a high incidence of cholangiocarcinoma. Water was sampled and examined six times (February, April, June, August, October and December 2006). The most probable number (MPN) index and coliform counts were utilized to evaluate fecal contamination; the cercarial shedding method was conducted for detecting infected snails. The data revealed that all water samples had a high MPN index number, and fecal coliform levels above the WHO standard. This indicated that water in these reservoirs was contaminated with feces or manure constituents. Water sampling from Ban Lerngpeuy showed full-scale bacterial contamination (>1609 MPN index) throughout the year. This finding was correlated with the highest prevalence of O. viverrini-infected snails, which were found nearly all year round in this area. Slightly lower fecal contamination levels were detected in water samples from Chonnabot and Ban Phai, with high MPN index numbers and coliform counts from April to October. This corresponded with the higher recovery of infected snails in June and August, but with relatively lower prevalence than those found in Ban Lerngpeuy. Among the sampling sites, the people in Ban Lerngpeuy live nearer to the reservoir than do those in Ban Phai and Chonnabot. These results indicate that fecal bacterial contamination in natural water reservoirs is an important indicator of seasonal transmission of O. viverrini eggs to snail intermediate hosts. Sanitation improvement is essential and future investigations on the sources of contamination are needed. PMID:21871971

Kaewkes, Wanlop; Kaewkes, Sasithorn; Tesana, Smarn; Laha, Thewarach; Sripa, Banchob

2011-08-17

20

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

1993-01-01

21

Impact of Invasive Water Hyacinth ( Eichhornia crassipes ) on Snail Hosts of Schistosomiasis in Lake Victoria, East Africa  

Microsoft Academic Search

Invasive plants may change ecologic conditions to contribute to transmission of human diseases. This study examined whether water hyacinth (Eichhornia crassipes) had an effect on the snails Biomphalaria sudanica and B. choanomphala, hosts of the disease organism Schistosoma mansoni in Lake Victoria, East Africa. Eight 16-m2 enclosures were established in shallow shoreline areas and were paired for water depth, substrate,

Mary L. Plummer

2005-01-01

22

High quantitative and no molecular differentiation of a freshwater snail (Galba truncatula) between temporary and permanent water habitats  

Microsoft Academic Search

We investigate the variation in quantitative and molecular traits in the freshwater snail Galba truncatula, from permanent and temporary water habitats. Using a common garden experiment, we measured 20 quantitative traits and molecular variation using seven microsatellites in 17 populations belonging to these two habitats. We estimated trait means in each habitat. We also estimated the distributions of overall genetic

ELODIE CHAPUIS; SANDRINE TROUVE; BENOIT FACON; LOÏC DEGEN; JEROME GOUDET

2007-01-01

23

Mineral contents of tissues and body fluids and heavy metal contaminants of four predominant snail species in the Niger Delta  

Microsoft Academic Search

Mineral contents and heavy metal contaminants of four predominant snail species in the Niger Delta: African giant land snail (Archachatina marginata), African land snail (Achatina fulica), water snail (Pila ovata) and garden snail (Limicolaria aurora) were evaluated. Snail tissues and body fluids were harvested having cracked the tail-end of the shell. Triplicate samples of macerated snail tissues and body fluids

H. D. Mepba; C. U. Ogunka-Nnoka

24

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

2009-01-01

25

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

2013-01-01

26

Water surface is acidic  

PubMed Central

Water autoionization reaction 2H2O ? H3O? + OH? is a textbook process of basic importance, resulting in pH = 7 for pure water. However, pH of pure water surface is shown to be significantly lower, the reduction being caused by proton stabilization at the surface. The evidence presented here includes ab initio and classical molecular dynamics simulations of water slabs with solvated H3O+ and OH? ions, density functional studies of (H2O)48H+ clusters, and spectroscopic isotopic-exchange data for D2O substitutional impurities at the surface and in the interior of ice nanocrystals. Because H3O+ does, but OH? does not, display preference for surface sites, the H2O surface is predicted to be acidic with pH < 4.8. For similar reasons, the strength of some weak acids, such as carbonic acid, is expected to increase at the surface. Enhanced surface acidity can have a significant impact on aqueous surface chemistry, e.g., in the atmosphere.

Buch, Victoria; Milet, Anne; Vacha, Robert; Jungwirth, Pavel; Devlin, J. Paul

2007-01-01

27

Surface Water Pathway Analysis  

Microsoft Academic Search

\\u000a When surface water pathway exposure and health effects are of concern, the transformation and transport analysis may include\\u000a several aquatic environments such as impoundments, rivers, streams, reservoirs, wetlands, lakes, estuaries and open oceans.\\u000a Among these, fresh water aquatic environments are of significant importance since they are the primary drinking water source\\u000a for many communities. Estuaries and oceans may be of

Mustafa M. Aral

28

Snail Trails  

ERIC Educational Resources Information Center

|The slime trails of snails lead the author's students to a better understanding of science as inquiry and the processes of science. During this five-day activity, students get up close and personal with one of her favorite creatures, the land snail. Students begin by observing the organism and recording their observations. After making initial…

Galus, Pamela

2002-01-01

29

O-Glycosylation of snails.  

PubMed

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

2012-05-12

30

Selected enzymatic activities in fresh water snails, specific intermediate host for human schistosomiasis.  

PubMed

The activities of aspartate aminotransferase (AST) (EC.2.6.1.1.) I, alanine aminotransferase (ALT) (EC.2.6.1.2) II and lactate dehydrogenase (LD) (EC.1.1.1.27) III have been measured in tissue homogenate and in haemolymph of Biomphalaria alexandrina snails, the specific intermediate host for the human parasitic disease schistosomiasis due to Schistosoma mansoni. PMID:2499422

Nabih, I; el-Dardire, Z; el-Ansary, A

1989-01-01

31

High quantitative and no molecular differentiation of a freshwater snail (Galba truncatula) between temporary and permanent water habitats.  

PubMed

We investigate the variation in quantitative and molecular traits in the freshwater snail Galba truncatula, from permanent and temporary water habitats. Using a common garden experiment, we measured 20 quantitative traits and molecular variation using seven microsatellites in 17 populations belonging to these two habitats. We estimated trait means in each habitat. We also estimated the distributions of overall genetic quantitative variation (QST), and of molecular variation (FST), within and between habitats. Overall, we observed a lack of association between molecular and quantitative variance. Among habitats, we found QST>FST, an indication of selection for different optima. Individuals from temporary water habitat matured older, at a larger size and were less fecund than individuals from permanent water habitat. We discuss these findings in the light of several theories for life-history traits evolution. PMID:17688547

Chapuis, Elodie; Trouve, Sandrine; Facon, Benoit; Degen, Loïc; Goudet, Jerome

2007-08-01

32

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

PubMed

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

2005-04-01

33

HPTLC Determination of Amino Acids in Snail-Conditioned Water From Biomphalaria glabrata, Two Strains of Helisoma trivolvis, and Lymnaea elodes  

Microsoft Academic Search

High performance thin-layer chromatography (HPTLC) was used to analyze amino acids in water conditioned by Biomphalaria glabrata, a Pennsylvania and Colorado strain of Helisoma trivolvis, and Lymnaea elodes. The snail-conditioned water (SCW) samples were dried with air and reconstituted in 10% n-propanol and then applied to cellulose HPTLC plates and developed with n-propanol-water (7:3). Amino acids were detected with ninhydrin

R. A. Steiner; B. Fried; J. Sherma

1998-01-01

34

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

PubMed

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

2005-12-01

35

Impact of changing water levels and weather on Oncomelania hupensis hupensis populations, the snail host of Schistosoma japonicum, downstream of the Three Gorges Dam.  

PubMed

Increasing evidence indicates that dams impact riverine ecosystems and human diseases. Poyang Lake, one of the largest schistosomiasis endemic environments in China, will change due to the construction of the Yangtze River Three Gorges Dam. We assess changes in Oncomelania hupensis hupensis, the snail host for Schistosoma japonicum, in response to changing water levels and weather from 1998 to 2002. In the 5 years following the major flooding of Poyang Lake in 1998, seasonal water levels have gradually decreased, concomitant with decreases in mean and variance of fall snail densities. Nonlinear relationships suggest that the highest spring density is associated with current, 2-, and 3-month prior temperatures of 18 degrees, 9.1 degrees, and 5.8 degrees C, while the highest fall density is associated with 2- and 3-month prior water levels of 17 and 18 m, respectively. This suggests that lower, more stable water levels downstream of the dam may result in a reduction in mean fall densities and their variance. However, additional data are needed to determine whether snail populations that are typically destroyed by seasonal floods may live longer in more stable environments created by the dam. PMID:18787918

Seto, Edmund Y W; Wu, Weiping; Liu, Hong-Yun; Chen, Hong-Gen; Hubbard, Alan; Holt, Ashley; Davis, George M

2008-05-06

36

Molluscicidal activity of crude water and hexane extracts of Hypericum species to snails (Radix peregra).  

PubMed

In spite of intense research on both chemical constituency and biological activity of Hypericum species, potential applications of their active components for pest control have been less well investigated. In the present study, Hypericum androsaemum (tutsan), Hypericum foliosum (malfurada), and Hypericum undulatum (wavy St. John's wort) aqueous and hexane extracts were studied for their molluscicidal and ovicidal activities against Radix peregra. The molluscicidal activity of the aqueous extracts was low, except for H. androsaemum infusion (median lethal concentration [LC50](adults) ?=?317.1 ppm; LC50(juveniles) ?=?415 ppm), and less important compared with the toxicity of all three hexane extracts tested: H. androsaemum (LC50(adults) ?=?30.47 ppm; LC50(juveniles) ?=?73.25 ppm), H. undulatum (LC50(adults) ?=?30.55 ppm; LC50(juveniles) ?=?60.54 ppm), and H. foliosum (LC50(adults) ?=?48.61 ppm; LC50(juveniles) ?=?38.81 ppm). An ovicidal effect was observed only with H. androsaemum infusion (1.85% of hatching at 500 ppm) and H. foliosum hexane extract (0.0% of hatching at 100 ppm). A preliminary phytochemical investigation of the lipophylic extracts from these Hypericum sp. revealed a different chemical profile and confirmed the presence of ursolic acid only in H. undulatum as the main compound. The present study indicates that products from hexane extracts of the Hypericum sp. analyzed may be used as potential molluscicides to control snails responsible for transmitting fasciolosis. PMID:22170085

Teixeira, Tânia; Rainha, Nuno; Rosa, José Silvino; Lima, Elisabete; Baptista, José

2012-02-24

37

Impact of Changing Water Levels and Weather on Oncomelania hupensis hupensis Populations, the Snail Host of Schistosoma japonicum , Downstream of the Three Gorges Dam  

Microsoft Academic Search

Increasing evidence indicates that dams impact riverine ecosystems and human diseases. Poyang Lake, one of the largest schistosomiasis\\u000a endemic environments in China, will change due to the construction of the Yangtze River Three Gorges Dam. We assess changes\\u000a in Oncomelania hupensis hupensis, the snail host for Schistosoma japonicum, in response to changing water levels and weather from 1998 to 2002.

Edmund Y. W. Seto; Weiping Wu; Hong-Yun Liu; Hong-Gen Chen; Alan Hubbard; Ashley Holt; George M. Davis

2008-01-01

38

CONNECTICUT SURFACE WATER QUALITY CLASSIFICATIONS  

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...

39

Succinate-DCPIP and NADH-fumarate oxidoreductases in fresh water snails susceptible and non susceptible to schistosoma infection.  

PubMed

The activities of succinate-DCPIP oxidoreductase (SO) and NADH-fumarate oxidoreductase (FR) were determined in tissue homogenate of Biomphalaria alexandrina and Bulinus truncatus, the snail vectors of Schistosomiasia. A parallel study was done on Lymnea truncatula snails which are not susceptible to Schistosoma infection. The Michaelis constant (Km) and maximum velocities (Vmax) for fumarate reduction and succinate oxidation by the tissue homogenates from the three species were determined. The results obtained showed that both susceptible species are aerobic and lactate is the sole end product of anaerobic glycolysis. Lymnea truncatula snails are facultative anaerobic producing succinate as a major end product in the glycolytic pathway. PMID:1571942

Nabih, I; el-Ansary, A

1992-04-01

40

Octopamine boosts snail locomotion: behavioural and cellular analysis  

Microsoft Academic Search

We measured the reduction in locomotion of unrestrained pond snails, Lymnaea stagnalis, subsequent to transdermal application of two selective octopamine antagonists, epinastine and phentolamine. After 3 h in fresh standard snail water following treatment with 4 mM epinastine or 3.5 mM phentolamine, the snails’ speed was reduced to 25 and 56% of the controls (P P = 0.02, respectively). The snails’ speed decreased as the drug

Jennifer C. Ormshaw; Christopher J. H. Elliott

2006-01-01

41

Dynamic surface properties of water: surface tension and surface potential  

SciTech Connect

The dynamic surface tension and surface potential of water have been measured for the surface ages from 0.8 to 7.0 msec. In both cases, the time of establishing the equilibrium values is found to be about 3 msec. The value +0.1 V for the equilibrium surface potential has been obtained by extrapolation. The structure of the surface layer has been discussed. 34 references.

Kochurova, N.N.; Rusanov, A.I.

1981-06-01

42

Surface Water Response Modeling  

EPA Science Inventory

During response to spills, or for facility planning, the vulnerability of downstream water resources is a major concern. How long and at what concentration do spilled contaminants reach downstream receptors? Models have the potential to answer these questions, but only if they ...

43

USGS Surface Water Information Pages  

NSDL National Science Digital Library

The Office of Surface Water (OSW) provides leadership in development and application of new techniques and tools for the collection, analysis, and interpretation of surface-water and sediment data. Programs discussed include national flood frequency, streamgaging, hydroclimatology, and river system management. Techniques for data collection are discussed, which include modeling, instrumentation, and collection of bridge scour data. Links to data about real-time streamflow and historical streamflow, as well as historical sediment suspension are provided for further information.

44

Foraging and refuge use by a pond snail: Effects of physiological state, predators, and resources  

NASA Astrophysics Data System (ADS)

The costs and benefits of anti-predator behavioral responses should be functions of the actual risk of predation, the availability of the prey's resources, and the physiological state of the prey. For example, a food-stressed individual risks starvation when hiding from predators, while a well-fed organism can better afford to hide (and pay the cost of not foraging). Similarly, the benefits of resource acquisition are probably highest for the prey in the poorest state, while there may be diminishing returns for prey nearing satiation. Empirical studies of state-dependent behavior are only beginning, however, and few studies have investigated interactions between all three potentially important factors. Here I present the results of a laboratory experiment where I manipulated the physiological state of pond snails ( Physa gyrina), the abundance of algal resources, and predation cues ( Belostoma flumineum waterbugs consuming snails) in a full factorial design to assess their direct effects on snail behavior and indirect effects on algal biomass. On average, snails foraged more when resources were abundant, and when predators were absent. Snails also foraged more when previously exposed to physiological stress. Snails spent more time at the water's surface (a refuging behavior) in the presence of predation cues on average, but predation, resource levels, and prey state had interactive effects on refuge use. There was a consistent positive trait-mediated indirect effect of predators on algal biomass, across all resource levels and prey states.

Wojdak, Jeremy M.

2009-09-01

45

Development and validation of a satellites based geographic information system (GIS) model for epidemiology of Schistosoma risk assessment on snail level in Kafr El-Sheikh Governorate.  

PubMed

The aim of the present study was to test the accuracy of Advanced Very High Resolution Radiometer (AVHRR) satellite derived temperature difference (dT) maps as a guide for the suitability of the environment for local snail hosts and Schistosoma development-transmission at the village level. The study provided field validation data from 13 villages in Kafr El Sheikh in the Nile Delta that sites present in wet zones of low dT value have more abundant snail populations than that present in the drier zones with high dT values. Results suggest that lower dT values were associated with wetter hydrologic regimes related to the level of underground water table and that this is reflected in the abundance of snail populations and Schistosoma snail infection rates at the village level. Water quality parameters on pH salinity and dissolved oxygen were not correlated with presence of Schistosoma infected snails. Results indicate that abundance of snails and S. mansoni prevalence are related to thermal-hydrology domains associated with surface water, that habitat suitability is related to depth to water table and that regional hydrology characteristics that affect snail host habitat suitability (ie. wet, moist, dry or very dry) can be evaluated using AVHRR dT maps. PMID:9257969

Abdel-Rahman, M S; el-Bahy, M M; el-Bahy, N M; Malone, J B

1997-08-01

46

Influence of Age and Body Size on Alarm Responses in a Freshwater Snail Pomacea canaliculata  

Microsoft Academic Search

A hypothesis that size selection of prey by predators elicits size-specific responses from prey was examined. Freshwater snails, Pomacea canaliculata, ages 1, 3, 7, 15, 30, or 60 days, were given an extract of 3-day-old snails, and 3-day-old snails were given extracts of snails of the other ages or eggs. Snails 15 days or younger crawled out of the water

Katsuya Ichinose

2002-01-01

47

Measuring surface water from space  

NASA Astrophysics Data System (ADS)

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 issues, such as the susceptibility of life to flood hazards, cannot be answered with the current global, in situ networks designed to observe river discharge at points but not flood events. The measurements required to answer these hydrologic questions are surface water area, the elevation of the water surface (h), its slope (?h/?x), and temporal change (?h/?t). Advances in remote sensing hydrology, particularly over the past 10 years and even more recently, have demonstrated that these hydraulic variables can be measured reliably from orbiting platforms. Measurements of inundated area have been used to varying degrees of accuracy as proxies for discharge but are successful only when in situ data are available for calibration; they fail to indicate the dynamic topography of water surfaces. Radar altimeters have a rich, multidecadal history of successfully measuring elevations of the ocean surface and are now also accepted as capable tools for measuring h along orbital profiles crossing freshwater bodies. However, altimeters are profiling tools, which, because of their orbital spacings, miss too many freshwater bodies to be useful hydrologically. High spatial resolution images of ?h/?t have been observed with interferometric synthetic aperture radar, but the method requires emergent vegetation to scatter radar pulses back to the receiving antenna. Essentially, existing spaceborne methods have been used to measure components of surface water hydraulics, but none of the technologies can singularly supply the water volume and hydraulic measurements that are needed to accurately model the water cycle and to guide water management practices. Instead, a combined imaging and elevation-measuring approach is ideal as demonstrated by the Shuttle Radar Topography Mission (SRTM), which collected images of h at a high spatial resolution (˜90 m) thus permitting the calculation of ?h/?x. We suggest that a future satellite concept, the Water and Terrestrial Elevation Recovery mission, will improve upon the SRTM design to permit multitemporal mappings of h across the world's wetlands, floodplains, lakes, reservoirs, and rivers.

Alsdorf, Douglas E.; RodríGuez, Ernesto; Lettenmaier, Dennis P.

2007-06-01

48

Kinetic potentials of certain scavenger enzymes in fresh water snails susceptible and non-susceptible to Schistosoma infection.  

PubMed

The activities of catalase (H2O2-oxidoreductase EC 1.11.1.6)- and glutathione reductase (EC 1.6.4.2) as two important scavenger enzymes, were measured in tissue homogenates of Biomphalaria alexandrina and Bulinus truncatus, the snail vectors of Schistosomiasis. A parallel study was done on Lymnea truncatula snails which are not susceptible to Schistosoma infection. The apparent Michaelis constant (Km) for both anzymes were determined in tissue homogenates of the three studied species. The results obtained showed that both susceptible species have higher affinity to hydrogen peroxide (H2O2) and oxidized glutathione (GSSG) than the non-susceptible one. PMID:8329984

Nabih, I; el Ansary, A

1993-06-01

49

Is the interspecific variation of body size of land snails correlated with rainfall in Israel and Palestine?  

NASA Astrophysics Data System (ADS)

The hypothesis that body size of land snail species increases with aridity in Israel and Palestine because large snails lose relatively less water due to their lower surface to volume ratio has been investigated. Data on rainfall amplitudes of 84 land snail species in Israel and Palestine and on their body sizes were used to test for interspecific correlations between body size and rainfall. Four methods, means of body sizes in rainfall categories, the midpoint method, the across-species method, and a phylogenetically controlled analysis (CAIC) showed that there is no significant correlation between body size of land snail species and their rainfall amplitude in Israel and Palestine. The lack of an interspecific correlation between body size and rainfall amplitude may be the result of conflicting selective forces on body size.

Hausdorf, Bernhard

2006-11-01

50

Persisting Water Droplets on Water Surfaces  

PubMed Central

Droplets of various liquids may float on the respective surfaces for extended periods of time prior to coalescence. We explored the features of delayed coalescence in highly purified water. Droplets several millimeters in diameter were released from a nozzle onto a water surface. Results showed that droplets had float times up to hundreds of milliseconds. When the droplets did coalesce, they did so in stepwise fashion, with periods of quiescence interspersed between periods of coalescence. Up to six steps were noted before the droplet finally vanished. Droplets were released in a series, which allowed the detection of unexpected abrupt float-time changes throughout the duration of the series. Factors such as electrostatic charge, droplet size, and sideways motion had considerable effect on droplet lifetime, as did reduction of pressure, which also diminished the number of steps needed for coalescence. On the basis of present observations and recent reports, a possible mechanism for noncoalescence is considered.

Klyuzhin, Ivan S.; Ienna, Federico; Roeder, Brandon; Wexler, Adam; Pollack, Gerald H.

2011-01-01

51

First record of a wild population of the tropical snail Melanoides tuberculata in New Zealand natural waters  

Microsoft Academic Search

The thiarid snail Melanoides tuberculata (Müller, 1774), native to the Middle East and East Africa, is recorded from the wild in New Zealand for the first time from a geothermally influenced stream at Golden Springs, near Taupo. Introduction was most likely the result of one or more releases from tropical aquaria, although the timing of release is uncertain. Specimens were

I. C. Duggan

2002-01-01

52

Bioaccumulation of heavy metals in water, sediments, aquatic plant and histopathological effects on the golden apple snail in Beung Boraphet reservoir, Thailand.  

PubMed

Changes in the seasonal concentrations of heavy metals (Cu, Mn, Fe, Zn, Pb and Cd) were determined in water, sediments, snails (Pomacea canaliculata) and aquatic plants (Ipomoea aquatica) in three selected tributaries of the Beung Boraphet reservoir, Nakhon Sawan Province, central Thailand. Only Fe, Cu, Mn and Zn were detected by FAAS in all samples collected. The water quality of Beung Boraphet was medium clean with Fe, Mn, Cu and Zn concentrations well below internationally accepted limits. According to the criteria proposed for sediments by the EPA Region V, Zn and Mn concentrations were within the non-polluted range while Fe and Cu (wet season) concentrations fell into the class of severely polluted sediment. Both P. canaliculata and I. aquatica bioconcentrated more Mn in their tissues than were found in sediments, especially in the wet season. The results of Pearson correlation study and BCF values also indicated similar findings. Only Mn showed the importance of sediment-to-snail concentration and high BCF values in both snails and plants. P. canaliculata exposed to contaminated sediment for two months, showed higher accumulation of metals (Fe, Mn, Cu and Zn) in the digestive tracts and digestive glands than in the foot muscles. Histopathological changes included alterations in the epithelial lining of the digestive tracts, digestive glands and the gills. Loss of cilia and increase in mucous cells were observed in the digestive tracts and gills, while the digestive glands exhibited an increase of dark granules and basophilic cells, and dilation of digestive cells. The results indicated that both P. canaliculata and I. aquatica could be used as biomonitors of sedimentary metal contamination for the Beung Boraphet reservoir. PMID:23079739

Dummee, Vipawee; Kruatrachue, Maleeya; Trinachartvanit, Wachareeporn; Tanhan, Phanwimol; Pokethitiyook, Prayad; Damrongphol, Praneet

2012-10-15

53

Ground and Surface Water Concepts  

NSDL National Science Digital Library

This section of the Digital Atlas of Idaho contains an extensive collection of information about hydrology. Topics include surface water/groundwater interaction, runoff, stream gauging, hydrographs, aquifer types, groundwater movement, aquifer response to pumping, and more. The information is suitable for an upper level college audience.

Welhan, John; Mcnamara, Jim; Project, The D.

54

Human pharmaceuticals in surface waters  

Microsoft Academic Search

Human pharmaceuticals are widely used and can reach surface waters, where they have the potential to exert biological effects on aquatic non-target organisms. Due to the high number of pharmaceutical drugs used in human medicine throughout the world, it is necessary to select the pharmaceuticals to search for, prior to implementing any environmental measurements and any extensive environmental risk assessment

Jean-Philippe Besse; Jeanne Garric

2008-01-01

55

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.

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

2010-01-01

56

Effects of Synthetics molluscicide Niclosamide and plant extracts ( Euphorbia and Melia ) Molluscicide against The different developmental stages of the fresh-water snail physa acuta , the (Draparnaud )vector of trematod parasite in Mosul area North Iraq  

Microsoft Academic Search

The effect of synthetic molluscicide ( Niclosamide) and some botanical molluscicide ( Euphorbia heliscop (EE) and Melia azedirachta (MA)) , of different concentrations on fecundity, survival and embryonic hatchability of the fresh water snails, Physa acuta (Draparnaud) Lymnea auricularia(L)- (pulmonats) and Melanopsis praemorsa (Linnaeus)- (Prosobranchates) in Mosul area were investigated. There are variable lethal effects of different Niclosamide concentrations on

Talib Hussen Ali

57

Sulfate deposition to surface waters  

SciTech Connect

Critical loads are the highest deposition of strong acid anions in surface waters that will not cause harmful biological effects on populations, such as declines in or extinctions of fish. Our analysis focuses on sulfate deposition because in glaciated regions sulfate is conservative in soils, whereas nitrate in biologically cycled. Sulfate also is the dominant anion in acidic deposition and in most acidic lakes. This analysis, represents the first evaluation of certain data available from Norway and the eastern United States, with an emphasis on the data from Scandinavia. The concept of dose-response is widely used in connection with water pollution. Any lake system subjected to an external dose of pollutants will have an internal resistance (or buffer capacity) to the change. The response of the lake system will depend on the relative magnitudes of the dose and the resistance parameters.

Henriksen, A.; Brakke, D.F.

1988-01-01

58

Changes in the surface pH of voltage-clamped snail neurones apparently caused by H+ fluxes through a channel.  

PubMed Central

1. The surface and intracellular pH of snail neurones was recorded with microelectrodes while the membrane potential was reduced in 10 mV steps for a few seconds each or to positive values for periods of several minutes. 2. Depolarizations to positive membrane potentials caused rapid falls in surface pH (pHs) which varied from cell to cell and from one point to another on the surface of the same cell. 3. When pHi was normal or alkaline, the first few 10 mV steps of depolarization often caused a small pHs increase which changed to a decrease as the depolarization increased. The threshold potential at which the pHs increase changed to a decrease varied with pHi in a linear manner, so that at acid pHi values the threshold potential approached the normal resting potential. There was good agreement between the threshold and H+ equilibrium potentials calculated from pHi and pHs. 4. The size of the pHs decrease observed at a given pHi and depolarization depended on extracellular buffering power in a non-linear manner. Solutions buffered with 20 mM-NaHCO3 had similar surface buffering power to CO2-free solutions buffered with only 1-2 mM-HEPES, pH 7.5. 5. In 1 mM-HEPES pHs changes were larger, and pHi increases slower, than those seen in cells depolarized to the same potential in 20 mM-HEPES. The slowing of the rate of pHi increase suggests that the pHs changes occur all over the cell surface, and not only at the recording site. 6. With long-lasting depolarizations the size of the pHs decrease was proportional to the rate of pHi increase and thus, assuming a constant intracellular buffering power, to the rate of efflux of H+. 7. The results provide further evidence that snail neurones possess a channel permeable to H+ which is opened on depolarization. H+ efflux through this channel could cause rapid acidification of a confined extracellular space.

Thomas, R C

1988-01-01

59

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

2003-01-01

60

Surface water discharges from onshore stripper wells.  

SciTech Connect

Under current US Environmental Protection Agency (EPA) rules, small onshore oil producers are allowed to discharge produced water to surface waters with approval from state agencies; but small onshore gas producers, however, are prohibited from discharging produced water to surface waters. The purpose of this report is to identify those states that allow surface water discharges from small onshore oil operations and to summarize the types of permitting controls they use. It is intended that the findings of this report will serve as a rationale to encourage the EPA to revise its rules and to remove the prohibition on surface water discharges from small gas operations.

Veil, J. A.

1998-01-16

61

Heavy metal concentrations in common freshwater snails of Azraq Oasis, Jordan  

Microsoft Academic Search

Heavy metal concentrations in three freshwater snails, an aquatic plant, sediment, and water from Azraq Oasis pools in the Jordanian desert were measured by atomic absorption spectrophotometry. There were significant differences in metal accumulation among snail species. These snails are ranked according to their metal accumulation capacity in the order: Melanoides tuberculata > Melanopsis praemorsa > Theodoxus jordani. Although there

Khaled M. Swaileh; Mohamed N. Mesmar; Naim S. Ismail

1994-01-01

62

Groundwater–Surface Water Management With Stochastic Surface Water Supplies: A Simulation Optimization Approach  

Microsoft Academic Search

A new simulation optimization model for groundwater–surface water management identifies efficient strategies for meeting water demand and controlling a regional water quality problem, while accounting for varying availability of surface water supplies. Optimal values of model variables are computed for ranges of surface water availability. Expected groundwater levels are computed using a response function approach, which incorporates a probability for

Eric G. Reichard

1995-01-01

63

Groundwater-surface water management with stochastic surface water supplies: A simulation optimization approach  

Microsoft Academic Search

A new simulation optimization model for groundwater-surface water management identifies efficient strategies for meeting water demand and controlling a regional water quality problem, while accounting for varying availability of surface water supplies. Optimal values of model variables are computed for ranges of surface water availability. Expected groundwater levels are computed using a response function approach, which incorporates a probability for

Eric G. Reichard

1995-01-01

64

The Classroom Animal: Snails.  

ERIC Educational Resources Information Center

|Points out that snails are interesting and easily-managed classroom animals. One advantage of this animal is that it requires no special attention over weekends or holidays. Background information, anatomy, reproduction, and feeding are discussed, along with suggestions for housing aquatic and/or land snails. (DH)|

Kramer, David S.

1985-01-01

65

Snail Shell Science.  

ERIC Educational Resources Information Center

|Presents three inquiry-based lessons to develop the science process skills of observation, identification, and classification. Activities use whelk eggs and snail shells as the focus of the students' inquiries. Provides a list of 19 facts about whelks and snails. (MDH)|

Matthews, Catherine

1992-01-01

66

Long-term sensitization and environmental conditioning in terrestrial snails  

Microsoft Academic Search

The hypothesis that a long-term increase of behavioural responses in snails (over a period of days) might be due to environmental conditioning was examined. Training consisted of delivering electric shocks non-contingently with test stimuli twice per day for 5 days to freely moving snails on a ball floating in water. After training, a significant difference in amplitude of a withdrawal

P. Balaban; N. Bravarenko

1993-01-01

67

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

PubMed

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

2001-04-01

68

Ground water and surface water; a single resource  

USGS Publications Warehouse

The importance of considering ground water and surface water as a single resource has become increasingly evident. Issues related to water supply, water quality, and degradation of aquatic environments are reported on frequently. The interaction of ground water and surface water has been shown to be a significant concern in many of these issues. Contaminated aquifers that discharge to streams can result in long-term contamination of surface water; conversely, streams can be a major source of contamination to aquifers. Surface water commonly is hydraulically connected to ground water, but the interactions are difficult to observe and measure. The purpose of this report is to present our current understanding of these processes and activities as well as limitations in our knowledge and ability to characterize them.

Winter, Thomas C.; Harvey, Judson W.; Franke, O. Lehn; Alley, William M.

1998-01-01

69

Mutagens in surface waters: a review  

Microsoft Academic Search

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

Takeshi Ohe; Tetsushi Watanabe; Keiji Wakabayashi

2004-01-01

70

Interaction between water and defective silica surfaces.  

PubMed

We use the density functional theory method to study dry (1 × 1) ?-quartz (0001) surfaces that have Frenkel-like defects such as oxygen vacancy and oxygen displacement. These defects have distinctively different effects on the water-silica interface depending on whether the adsorbent is a single water molecule, a cluster, or a thin film. The adsorption energies, bonding energies, and charge transfer or redistributions are analyzed, from which we find that the existence of a defect enhances the water molecule and cluster surface interaction by a large amount, but has little or even negative effect on water thin film-silica surface interaction. The origin of the weakening in film-surface systems is the collective hydrogen bonding that compromises the water-surface interaction in the process of optimizing the total energy. For clusters on surfaces, the lowest total energy states lower both the bonding energy and the adsorption energy. PMID:21428652

Chen, Yun-Wen; Cheng, Hai-Ping

2011-03-21

71

Trematode infections in freshwater snails and cattle from the Kafue wetlands of Zambia during a period of highest cattle-water contact.  

PubMed

A total of 984 snails, comprising nine species, were collected from six areas in the Kafue wetlands between August and October 2003 to assess larval trematode infections. Of these, 135 (13.7%) were positive. Most trematode infections were recorded from Lymnaea natalensis (42.8%), which harboured four of the five morphologically different cercariae found. No trematodes were recovered from Bellamya capillata, Biomphalaria pfeifferi, Melanoides tuberculata, Physa acuta and Cleopatra nswendweensis. One snail (0.2%) of 416 Bulinus snails shed brevifurcate-apharyngeate distome cercariae while three (0.7%) shed amphistomes. Gymnocephalous and longifurcate-pharyngeate distome were the commonest types of cercariae recorded while xiphidiocercaria was the least common. The highest prevalence rates of F. gigantica (68.8%) and amphistomes (50.0%) in cattle (n = 101) were in Chiyasa while those in Kaleya had the lowest (9.1 and 18.2%, respectively). In most habitats, infections were recorded in both cattle and snails. Critical determinants of infection may have been the distance of settlements and/or cattle kraals, the number of animals in nearby homesteads and the presence of susceptible host snails. This study suggests that fascioliasis and amphistomiasis could be major constraints of cattle production in the Kafue wetlands because favourable factors were available to introduce and maintain the infections. It further provides a starting point for some comprehensive studies on snail-related aspects of transmission and snail host ecology in Zambia. PMID:17381873

Phiri, A M; Phiri, I K; Chota, A; Monrad, J

2007-03-01

72

Surface Water Supplies and Health  

Microsoft Academic Search

Rivers, streams, lakes, and reservoirs have long been important sources of drinking water. In the past, these sources were often heavily contaminated by sewage discharges and, unfortunately, were also important in the transmission of communicable diseases such as typhoid and cholera. With improvements in sewage disposal practices, development and protection of water sources, and water treatment, outbreaks of waterborne disease

Gunther F. Craun

1988-01-01

73

Dragonfly predators influence biomass and density of pond snails.  

PubMed

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

2007-04-25

74

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.

Usgs

75

Polarimetric thermal emission from periodic water surfaces  

Microsoft Academic Search

In this paper, experimental results and theoretical calculations are presented to study the polarimetric emission from water surfaces with directional features. It is observed that the measured Stokes parameters of corrugated fiberglass-covered water surfaces are functions of azimuth angles and agree very well with theoretical calculations. The theory, after being verified by the experimental data, was then used to calculate

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

1994-01-01

76

Two dimensional mixtures at water surface  

NASA Astrophysics Data System (ADS)

Thiol capped gold nanoparticles (Au NPs) form a simple two dimensional (2D) liquid on water surface but this thin film is unstable under compression. Amphiphilic stearic acid (StA) molecules on water surface, on the other hand, form a complex and more stable 2D liquid. We have initiated a study on a mixture of StA and Au NPs in a monolayer through Surface Pressure (?) - Specific Molecular Area (A) isotherms and Brewster Angle Microscopy (BAM). A mixture of Stearic Acid and Au nanoparticles (10% by weight) produces a monolayer on water surface that acts as a 2D liquid with phases that are completely reversible with negligible hysteresis.

Choudhuri, Madhumita; Datta, Alokmay

2013-02-01

77

Aquatic Snails, Passive Hosts of Mycobacterium ulcerans  

PubMed Central

Accumulative indirect evidence of the epidemiology of Mycobacterium ulcerans infections causing chronic skin ulcers (i.e., Buruli ulcer disease) suggests that the development of this pathogen and its transmission to humans are related predominantly to aquatic environments. We report that snails could transitorily harbor M. ulcerans without offering favorable conditions for its growth and replication. A novel intermediate link in the transmission chain of M. ulcerans becomes likely with predator aquatic insects in addition to phytophage insects. Water bugs, such as Naucoris cimicoides, a potential vector of M. ulcerans, were shown to be infected specifically by this bacterium after feeding on snails experimentally exposed to M. ulcerans.

Marsollier, Laurent; Severin, Tchibozo; Aubry, Jacques; Merritt, Richard W.; Saint Andre, Jean-Paul; Legras, Pierre; Manceau, Anne-Lise; Chauty, Annick; Carbonnelle, Bernard; Cole, Stewart T.

2004-01-01

78

Component Software Systems for Surface Water Simulation  

Microsoft Academic Search

The simulation of the behaviour of surface water is a complicated activity, dealing with waves, water flow, transport of substances,\\u000a water quality, ecology and morphology. These processes have their own characteristic time scales from seconds for surface\\u000a waves through years for ecology and decades for morphology. These processes also have their own spatial scales and requirements\\u000a for local refinement and

L. Postma; P. M. A. Boderie; J. A. G. Van Gils; J. K. L. Van Beek

2003-01-01

79

Surface structure of water and ice  

Microsoft Academic Search

The state of molecular orientation in a pure water surface is examined and it is concluded that the surface molecules are almost completely oriented with their negative vertices outward. Because of inter-molecular bonding this orientation decays approximately exponentially beneath the surface, the depth of orientation being about ten molecular layers. The driving energy for this orientation is supplied by the

N. H. Fletcher

1962-01-01

80

Adhesion under water: surface energy considerations  

Microsoft Academic Search

Contact angles for a set of probe liquids on solid surfaces have been used to determine the components of the solid surface energies. By the use of suitable combining rules, such data have then been used to calculate the work of adhesion of oil onto various solid surfaces under water. A surprising outcome of such studies is that the order

John H. Clint; Amanda C. Wicks

2001-01-01

81

Prediction of surface pressures during water impact  

Microsoft Academic Search

A potential flow model was developed to predict pressures and loads during the oblique water impact of axisymmetric bodies. The free surface is replaced by an effective planar surface which is positioned using experimental information. At each depth, the flow field solution is determined using a distribution of sources on the model surface. Pressures, calculated by Bernoulli's equation, are integrated

A. B. Wardlaw Jr.; P. M. Aronson

1977-01-01

82

Surface Water Treatment Workshop Manual.  

ERIC Educational Resources Information Center

|This manual was developed for use at workshops designed to increase the knowledge of experienced water treatment plant operators. Each of the fourteen lessons in this document has clearly stated behavioral objectives to tell the trainee what he should know or do after completing that topic. Areas covered in this manual include: basic water

Ontario Ministry of the Environment, Toronto.

83

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

PubMed

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

2011-05-12

84

Vertical migrations of the mangrove snail Cerithidea decollata (L.) (Potamididae) through a synodic month  

NASA Astrophysics Data System (ADS)

The vertical migration on mangrove trunks of the gastropod Cerithidea decollata was followed for 5 weeks, in a Kenyan mangrove. Most of the times, snails forage on the mud surface, during low tide, and climb back on trees well before the incoming tide. As soon as the sea retreats, the downward migration takes place and the snails spread again on the ground. The migratory behaviour of snails can vary widely, depending on the relative tide intensity, and different strategies can be exhibited. Individuals can spend several days on trees without migrating to the ground, around Spring Tides, or else, they might remain on the ground without bothering to migrate upwards, during Neap Tides, when the study area is not reached by the water. These irregular animal behaviours, relating to the complicated tide succession, can hardly be explained by the sole presence of an internal clock, and direct cues seem necessary to switch between different strategies, tuning the snails migratory behaviour to the actual local sea conditions.

Vannini, Marco; Coffa, Cecilia; Lori, Elisabetta; Fratini, Sara

2008-07-01

85

Modelling global fresh surface water temperature  

Microsoft Academic Search

Temperature directly determines a range of water physical properties including vapour pressure, surface tension,\\u000adensity and viscosity, and the solubility of oxygen and other gases. Indirectly water temperature acts as a strong\\u000acontrol on fresh water biogeochemistry, influencing sediment concentration and transport, water quality parameters\\u000a(e.g. pH, nitrogen, phosphor, dissolved oxygen), chemical reaction rates, phytoplankton and zooplankton\\u000acomposition and the

L. P. H. van Beek; T. Eikelboom; M. T. H. van Vliet; M. F. P. Bierkens

2011-01-01

86

IDENTIFYING VULNERABLE SURFACE WATER UTILITIES  

EPA Science Inventory

This study was conducted to provide a mechanism and framework with which utility managers could analyze the effects of upstream discharges on source waters. Specific components of the project included selection, implementation, and demonstration of a microcomputer-based commerci...

87

Water vapor retrieval over many surface types  

SciTech Connect

In this paper we present a study of of the water vapor retrieval for many natural surface types which would be valuable for multi-spectral instruments using the existing Continuum Interpolated Band Ratio (CIBR) for the 940 nm water vapor absorption feature. An atmospheric code (6S) and 562 spectra were used to compute the top of the atmosphere radiance near the 940 nm water vapor absorption feature in steps of 2.5 nm as a function of precipitable water (PW). We derive a novel technique called ``Atmospheric Pre-corrected Differential Absorption`` (APDA) and show that APDA performs better than the CIBR over many surface types.

Borel, C.C.; Clodius, W.C.; Johnson, J.

1996-04-01

88

USGS Surface Water Information Pages  

NSDL National Science Digital Library

This website provides maps and streamflow data for all monitored streams in the US. Links to USGS fact sheets and reports, data sets, publications, facilities, programs and techniques are also included. The site is helpful for designing activities on flooding and water rights.

Water, Office O.; Usgs

89

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...

90

Groundwater travel times and surface water quality  

NASA Astrophysics Data System (ADS)

Surface water quality measurements in The Netherlands are scattered in time and space. Therefore, water quality status and its variations and trends are difficult to determine. In order to reach the water quality goals according to the European Water Framework Directive, we need to improve our understanding of the dynamics of surface water quality and the processes that affect it. Surface water solute concentrations are often analyzed using travel time distributions of water passing through the saturated and unsaturated soil of the contributing catchment, representing the contact time during which sorption, desorption and degradation takes place. However, travel time distributions are strongly influenced by processes like tube drain flow, overland flow and the dynamics of draining ditches and streams and therefore show strong daily and seasonal variations. The study we will present is situated in the 6.6 square km Hupsel brook catchment in The Netherlands, which is a predominantly agricultural, gently sloping catchment with mostly sandy soils. Many fields have tube drains discharging into a dense ditch network that feeds into the brook and its subsidiaries. This catchment has been intensively monitored for the past 20 years and therefore a comparison between model results and concentration measurements is possible. An explorative groundwater model study (Modflow) with a detailed spatial and temporal resolution, combined with a transient particle tracking approach is performed to evaluate the transient behaviour of the surface water network and its effect on travel time distributions. The dynamics in travel time distributions are used to describe surface water chloride and nitrate concentrations to point out the importance of using transient travel time distributions for surface water concentration and load calculations.

van der Velde, Y.; de Rooij, G. H.

2009-04-01

91

Line on the Surface of Water  

Microsoft Academic Search

I WAS interested in Prof. W. Schmidt's letter in NATURE of May 9, as nearly thirty years ago I noticed the `line' he describes and have often seen it since, but not previously in print. I first noticed it on the surface of water in a stone drinking-trough at a farm-house in Hayfield, near Stockport. Water came into the trough

Herbert Stansfield

1936-01-01

92

SURFACE WATER INTAKES, NEUSE RIVER WATERSHED, NC  

EPA Science Inventory

The North Carolina Department of Environment, Health, and Natural Resources, Division of Water Quality, in cooperation with the NC Center for Geographic Information and Analysis, developed the Surface Water Intakes digital data to enhance planning, siting and impact analysis in a...

93

Interaction of Water with Clay Surfaces: Discussion  

Microsoft Academic Search

In clay suspensions and gels water molecules are distributed between two populations in fast exchange. The physical meaning of this distribution is discussed here. From the molecular dynamics point of view it is shown that the surface force fields perturb the rotational motion on a distance z* extending to approximately 10-9 m. The product z* times the surface area available

J. J. Fripiat; M. Letellier; P. Levitz; J. M. Thomas

1984-01-01

94

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.

2011-01-01

95

Lichen endozoochory by snails.  

PubMed

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; Rüetschi, Jörg; Fischer, Markus

2011-04-13

96

TREMATODE INFECTIONS OF THE FRESHWATER SNAIL FAMILY THIARIDAE IN THE KHEK RIVER, THAILAND  

Microsoft Academic Search

The freshwater snail family Thiaridae was studied at five different locations: water sources for the Khek River, Thailand. Snail samples were collected by hand using counts per unit of time sampling method between December 2004 and October 2005. The physico-chemi- cal quality of the water changed with the seasons and affected the sampling areas during both the dry season and

Wivitchuta Dechruksa; Duangduen Krailas; Suluck Ukong; Wasin Inkapatanakul; Tunyarut Koonchornboon

97

The Effect of Aquatic Plant Abundance on Shell Crushing Resistance in a Freshwater Snail  

PubMed Central

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.

Chaves-Campos, Johel; Coghill, Lyndon M.; Garcia de Leon, Francisco J.; Johnson, Steven G.

2012-01-01

98

Surface water records of New Mexico, water year 1961  

USGS Publications Warehouse

The surface-water records for the 1961 water year for gaging stations, partial-record stations, and miscellaneous sites within the State of New Mexico are given in this report. For convenience there are also included for a few pertinent gaging stations in bordering States. The records were collected and computed by the Water Resources Division of the U. S. Geological Survey, under the direction of W. L. Heckler, district engineer, Surface Water Branch. This report marks the beginning of a new method of presenting, annually, basic data on surface-water records by States. Through September 30, 1960, the records of discharge and stage of streams and contents and stage of lakes or reservoirs were published in an annual series of U. S. Geological Survey water supply papers entitled "Surface Water Supply of the United States." Since 1951 there has been 20 volumes in the series; each volume covered an area whose boundaries coincided with those of certain natural drainage areas. The records in New Mexico were contained in Parts 7, 8, and 9 of that series. Beginning with the 1961 water year, streamflow records and related data will be released by the Geological Survey in annual reports On a State-boundary basis. Distribution of these basic-data reports will be limited and primarily for local needs. The records later will be published in Geological Survey watersupply paper at 5-year intervals. These 5-year water-supply papers will show daily discharge and will be compiled on the same geographical areas previously used for the annual series; however, some of the 14 parts of conterminous United States will be further subdivided.

U.S. Geological Survey

1962-01-01

99

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

2006-01-01

100

Rare and Endemic Snails of Selected Springs Within the St. Johns River Water Management District. Special Publication SJ2006-SP17.  

National Technical Information Service (NTIS)

This report produced a literature-based inventory of rare and endemic snail species and their degree of imperilment for Alexander, Apopka, Bugg, DeLeon, Gemini, Green, Rock, Silver, Silver Glen and Wekiwa spring boils and spring runs. Additionally, (1) th...

D. N. Shelton

2005-01-01

101

Analysis of Discontinuous Finite Element Methods for Ground Water\\/Surface Water Coupling  

Microsoft Academic Search

We derive and analyze new numerical approaches for modeling coupled ground water\\/surface water flow. In this coupled model, surface water flow is described by the depth- averaged shallow water equations, while ground water is modeled by saturated Darcy flow. The coupling between the two models assumes continuity of pressure and water flux across the ground water\\/surface water interface. The coupled

Clint Dawson

2006-01-01

102

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

1997-01-01

103

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.

2006-04-01

104

Inquiry, Land Snails, and Environmental Factors.  

ERIC Educational Resources Information Center

|Introduces land snails for use in inquiry-based science activities. Describes common characteristics and safety considerations while introducing students to land snails. Explains procedures for inquiry-based use of land snails in classrooms. (YDS)|

Barrow, Lloyd H.; Krantz, Patrick D.

2002-01-01

105

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.  

PubMed

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

2013-05-28

106

Surface water clarification using M. oleifera seeds  

Microsoft Academic Search

Turbid surface water was treated using a pilot scale water treatment plant comprising coagulation, flocculation, sedimentation and rapid gravity filtration, using Moringa oleifera seeds\\/alum as coagulants. Turbidity removal of M. oleifera, alum, and the mixture of both M. oleifera\\/alum were compared, and results obtained were 7.2, 4.2 and 3.2 NTU, respectively. The turbidity achieved using M. oleifera\\/alum mixture and alum

A. G. Liew; M. J. M. M. Noor; S. A. Muyibi; A. M. S. Fugara; T. A. Muhammed; S. E. Iyuke

2006-01-01

107

United States: The Allocation of Surface Waters  

Microsoft Academic Search

The English settlers in North America brought with them the common law, which, while well developed in many respects, had\\u000a little to say about the allocation of surface waters. With courts generally, but not always, taking the lead, the states of\\u000a the United States developed over three centuries three very different legal regimes for the allocation of water: riparian\\u000a rights

Joseph W. Dellapenna

108

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

PubMed

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

2002-03-01

109

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.

Bdir, Sami; Adwan, Ghaleb

2011-01-01

110

Global modeling of fresh surface water temperature  

NASA Astrophysics Data System (ADS)

Temperature determines a range of water physical properties, the solubility of oxygen and other gases and acts as a strong control on fresh water biogeochemistry, influencing chemical reaction rates, phytoplankton and zooplankton composition and the presence or absence of pathogens. Thus, in freshwater ecosystems the thermal regime affects the geographical distribution of aquatic species through their growth and metabolism, tolerance to parasites, diseases and pollution and life history. Compared to statistical approaches, physically-based models of surface water temperature have the advantage that they are robust in light of changes in flow regime, river morphology, radiation balance and upstream hydrology. Such models are therefore better suited for projecting the effects of global change on water temperature. Till now, physically-based models have only been applied to well-defined fresh water bodies of limited size (e.g., lakes or stream segments), where the numerous parameters can be measured or otherwise established, whereas attempts to model water temperature over larger scales has thus far been limited to regression type of models. Here, we present a first attempt to apply a physically-based model of global fresh surface water temperature. The model adds a surface water energy balance to river discharge modelled by the global hydrological model PCR-GLOBWB. In addition to advection of energy from direct precipitation, runoff and lateral exchange along the drainage network, energy is exchanged between the water body and the atmosphere by short and long-wave radiation and sensible and latent heat fluxes. Also included are ice-formation and its effect on heat storage and river hydraulics. We used the coupled surface water and energy balance model to simulate global fresh surface water temperature at daily time steps on a 0.5x0.5 degree grid for the period 1970-2000. Meteorological forcing was obtained from the CRU data set, downscaled to daily values with ECMWF ERA40 re-analysis data. We compared our simulation results with daily temperature data from rivers and lakes (USGS, limited to the USA) and compared mean monthly temperatures with those recorded in the GEMS data set. Results show that the model is able to capture well the mean monthly surface temperature for the majority of the GEMS stations both in time as well as in space, while the inter-annual variability as derived from the USGS data was captured reasonably well. Results are poorest for the arctic rivers, possibly because the timing of ice-breakup is predicted too late in the year due to the lack of including a mechanical break-up mechanism. The spatio-temporal variation of water temperature reveals large temperature differences between water and atmosphere for the higher latitudes, while considerable lateral transport of heat can be observed for rivers crossing hydroclimatic zones such as the Nile, the Mississippi and the large rivers flowing into the Arctic. Overall, our model results show great promise for future projection of global fresh surface water temperature under global change.

Bierkens, M. F.; Eikelboom, T.; van Vliet, M. T.; Van Beek, L. P.

2011-12-01

111

Electrolysis of water on (oxidized) metal surfaces  

NASA Astrophysics Data System (ADS)

Density functional theory calculations are used as the basis for an analysis of the electrochemical process, where by water is split to form molecular oxygen and hydrogen. We develop a method for obtaining the thermochemistry of the electrochemical water splitting process as a function of the bias directly from the electronic structure calculations. We consider electrodes of Pt(1 1 1) and Au(1 1 1) in detail and then discuss trends for a series of different metals. We show that the difficult step in the water splitting process is the formation of superoxy-type (OOH) species on the surface by the splitting of a water molecule on top an adsorbed oxygen atom. One conclusion is that this is only possible on metal surfaces that are (partly) oxidized. We show that the binding energies of the different intermediates are linearly correlated for a number of metals. In a simple analysis, where the linear relations are assumed to be obeyed exactly, this leads to a universal relationship between the catalytic rate and the oxygen binding energy. Finally, we conclude that for systems obeying these relations, there is a limit to how good a water splitting catalyst an oxidized metal surface can become.

Rossmeisl, J.; Logadottir, A.; Nørskov, J. K.

2005-12-01

112

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

1998-01-01

113

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

2012-09-01

114

Protonation and Deprotonation on Water's Surface  

NASA Astrophysics Data System (ADS)

How the acidity of bulk water (pHbulk) regulates the degree of protonation of Brönsted acids and bases on water surfaces facing hydrophobic media is a key unresolved issue in chemistry and biology. We addressed experimentally the important case of the air/water interface and report the strikingly dissimilar pHbulk-dependences of the protonation/deprotonation of aqueous versus gaseous n-hexanoic acid (HxOH) determined on the surface of aqueous microjets by online electrospray mass spectrometry. We confirm that HxOH(aq) is deprotonated at pHbulk > pKa(HxOH) = 4.8, but find that the deprotonation of HxOH(g) into interfacial HxO-(s) displays two equivalence points at pHbulk ~ 2.5 and ~ 10.0. The weak base HxOH(aq) (pKa(HxOH2+) < - 4) is barely protonated at pHbulk > 1, whereas HxOH(g) is significantly protonated to HxOH2+(s) on pHbulk < 4 water, as expected from the proton affinities PA(HxOH) > PA(H2O) of gas-phase species. The exceptionally large kinetic isotope effect for the protonation of HxOH(g) on D2O/H2O: KIE = HxOH2+/HxODH+ ~ 100, is ascribed to a desolvated transition state. Since ion creation at the interface via proton transfer between H2O itself and neutral species is thermodynamically disallowed i.e., HxOH(g) is actually deprotonated by interfacial OH-(s), whereas Me3N(g) is hardly protonated by H3O+(s) on pHbulk ~ 4 - 8 water (Enami et al., J. Phys. Chem. Lett. 2010, 1, 1599) we conclude that [OH-(s)] > [H3O+(s)] above pHbulk ~ 4, at variance with inferences drawn from spectroscopic signatures or model calculations of water’s surface.

Colussi, A. J.; Enami, S.; Stewart, L.; Hoffmann, M. R.

2010-12-01

115

Surface water records of New Mexico, water year 1963  

USGS Publications Warehouse

This report is the third in a series presenting, annually, basic data on surface-water records by States. Through September 30, 1960, the records of discharge and stage of streams and contents and stage of lakes or reservoirs were published in an annual series of U. S. Geological Survey water-supply papers entitled "Surface Water Supply of the United States". Since 1951 there have been 20 volumes in the series; each volume covered an area whose boundaries coincided with those of certain natural drainage areas. The records in New Mexico were contained in Parts 7, 8, and 9 of that series. Beginning with the 1961 water year, streamflow records and related data will be released by the Geological Survey in annual reports on a State-boundary basis. Distribution of these basic-data reports will be limited and primarily for local needs. The records later will be published in Geological Survey water-supply papers at 5- year intervals. These 5-year water-supply papers will show daily discharge and will be compiled on the same geographical areas previously used for the annual series; however, some of the 14 parts of conterminous United States will be further subdivided.

U.S. Geological Survey

1964-01-01

116

Mutagens in surface waters: a review.  

PubMed

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

2004-11-01

117

Proceedings of the Ground-Water Surface-Water Interactions Workshop.  

National Technical Information Service (NTIS)

Contents: Executive Summary; Presentation Abstracts (A Federal Statutory/Regulatory/Policy Perspective on Remedial Decision-making with Respect to Ground-Water/Surface-Water Interaction, Interaction of Ground Water and Surface Water, Hydrogeology and Bige...

2000-01-01

118

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.

2003-12-01

119

Water quality analysis of surface water: a Web approach.  

PubMed

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

2012-12-14

120

A molecular phylogeography approach to biological invasions of the New World by parthenogenetic Thiarid snails  

Microsoft Academic Search

The parthenogenetic snail Melanoides tuberculata , present in tropical fresh waters of most of the Old World before 1950, has now invaded the Neotropical area. The phylogeography of this snail was studied to evaluate the pathways and number of such invasions. Because of parthenogenetic reproduction, individuals are structured into genetical clones. Within populations from both the original and invaded areas,

B. FACON; J.-P. POINTIER; M. GLAUBRECHT; C. POUX; P. JARNE; P. DAVID

2003-01-01

121

Factors Affecting the Distribution and Abundance of Two Prosobranch Snails in a Thermal Spring  

Microsoft Academic Search

We studied the distribuiton and abundance of two prosobranch snails (Melanopsis praemorsa and Melanoides tuberculata) in a thermal spring (27°C) in southeast Morocco. Of the physicochemical and ecological parameters measured, food availability and water velocity appeared to be the main factors affecting the spatial distribution of these snails.

Hammou Laamrani; Khalid Khallayoune; Bernard Delay; Jean-Pierre Pointier

1997-01-01

122

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

GLENN R. WEBB

123

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

1999-01-01

124

Herbivory on aquatic vascular plants by the introduced golden apple snail ( Pomacea canaliculata ) in Lao PDR  

Microsoft Academic Search

The effect of naturally found densities of the exotic and herbivorous golden apple snail (Pomacea canaliculata) on three dominant aquatic plants – duckweed (Lemna minor), water hyacinth (Eichhornia crassipes) and morning glory (Ipomoea aquatica) – was assessed in a wetland survey and quantified in a field experiment in Laos in southeast Asia. Snail grazing reduced plant biomass, but plant species

Nils O. L. Carlsson; Jean O. Lacoursière

2005-01-01

125

Sex expression of an immobile coral-inhabiting snail, Quoyula monodonta  

Microsoft Academic Search

To test the hypotheses explaining the sex expression of the immobile snail Quoyula monodonta, which inhabits the surfaces of the branching coral, Pocillopora eydouxi, the size, sex, gonad development, penis length and the composition of neighboring individuals were investigated between November 1994 and August 1995 in southern Taiwan. Although the snails often aggregated and formed patches, more than 50% were

Keryea Soong; Ming-Hui Chen

2003-01-01

126

Sediment copper bioavailability to freshwater snails in south Florida: risk implications for the Everglade snail kite (Rostrhamus sociabilis plumbeus).  

PubMed

Many properties being acquired as part of the Comprehensive Everglades Restoration Plan (CERP) are heavily contaminated with copper. Estimated copper bioaccumulation in the Florida apple snail (Pomacea paludosa) has led to the prediction of risk to the Everglade snail kite (Rostrhamus sociabilis plumbeus) at some CERP projects. Field study results presented in this paper examine the relationship between copper levels in sediments, snails, and other biota. Copper concentrations in all biota (snails, aquatic vascular plants, and periphyton) were strongly correlated with those in sediments. No correlation with water copper concentrations was evident. Mean copper concentrations in snails ranged from 23.9 mg/kg at the reference site to 732 mg/kg at a high copper site. Calculated biota-sediment accumulation factors (BSAFs) ranged from 36.7 to 7.0 over the range of copper levels in sediments. BSAFs were highest at low copper levels in sediments and declined sharply as copper levels in sediment increased. Risk for the snail kite is discussed in light of the results of this study. PMID:18679796

Frakes, Robert A; Bargar, Timothy A; Bauer, Emily A

2008-08-05

127

Electrolysis of water on oxide surfaces  

Microsoft Academic Search

In this paper, density functional theory (DFT) calculations are performed to analyze the electrochemical water-splitting process producing molecular oxygen (O2) and hydrogen (H2). We investigate the trends in the electro-catalytic properties of (110) surfaces of three rutile-type oxides (RuO2, IrO2, and TiO2). The two first of these oxide anodes show lower O2-evolving over-potentials than metal anodes, due to weak O

J. Rossmeisl; Z.-W. Qu; H. Zhu; G.-J. Kroes; J. K. Nørskov

2007-01-01

128

How Stress Alters Memory in 'Smart' Snails  

PubMed Central

Cognitive ability varies within species, but whether this variation alters the manner in which memory formation is affected by environmental stress is unclear. The great pond snail, Lymnaea stagnalis, is commonly used as model species in studies of learning and memory. The majority of those studies used a single laboratory strain (i.e. the Dutch strain) originating from a wild population in the Netherlands. However, our recent work has identified natural populations that demonstrate significantly enhanced long-term memory (LTM) formation relative to the Dutch strain following operant conditioning of aerial respiratory behaviour. Here we assess how two populations with enhanced memory formation (i.e. ‘smart’ snails), one from Canada (Trans Canada 1: TC1) and one from the U.K. (Chilton Moor: CM) respond to ecologically relevant stressors. In control conditions the Dutch strain forms memory lasting 1–3 h following a single 0.5 h training session in our standard calcium pond water (80 mg/l [Ca2+]), whereas the TC1 and CM populations formed LTM lasting 5+ days following this training regime. Exposure to low environmental calcium pond water (20 mg/l [Ca2+]), which blocks LTM in the Dutch strain, reduced LTM retention to 24 h in the TC1 and CM populations. Crowding (20 snails in 100 ml) immediately prior to training blocks LTM in the Dutch strain, and also did so in TC1 and CM populations. Therefore, snails with enhanced cognitive ability respond to these ecologically relevant stressors in a similar manner to the Dutch strain, but are more robust at forming LTM in a low calcium environment. Despite the two populations (CM and TC1) originating from different continents, LTM formation was indistinguishable in both control and stressed conditions. This indicates that the underlying mechanisms controlling cognitive differences among populations may be highly conserved in L. stagnalis.

Dalesman, Sarah; Lukowiak, Ken

2012-01-01

129

Phase diagram of water between hydrophobic surfaces.  

PubMed

Molecular dynamics simulations demonstrate that there are at least two classes of quasi-two-dimensional solid water into which liquid water confined between hydrophobic surfaces freezes spontaneously and whose hydrogen-bond networks are as fully connected as those of bulk ice. One of them is the monolayer ice and the other is the bilayer solid which takes either a crystalline or an amorphous form. Here we present the phase transformations among liquid, bilayer amorphous (or crystalline) ice, and monolayer ice phases at various thermodynamic conditions, then determine curves of melting, freezing, and solid-solid structural change on the isostress planes where temperature and intersurface distance are variable, and finally we propose a phase diagram of the confined water in the temperature-pressure-distance space. PMID:15836349

Koga, Kenichiro; Tanaka, Hideki

2005-03-01

130

Surface waters monitoring by satellite altimetry  

NASA Astrophysics Data System (ADS)

Water level measurement by satellite altimetry has been developed and optimized for open oceans. Nevertheless, the technique is now applied to obtain water levels of extensive inland seas, lakes, rivers, floodplains and wetlands. Several satellite altimetry missions have been launched since the early 1990s : ERS-1 (1991-1996), Topex/Poseidon (1992- ), ERS-2 (1995- ), GFO (2000- ), Jason-1 (2001- ) and ENVISAT (2002- ). We have developed a global data base of water level time series over lakes and rivers based on satellite altimetry. Most of the water level time series of the data base are constructed using the Topex/Poseidon GDRs data, but a number of lakes water levels are based on ERS, GFO and Envisat data. To construct water level time series on rivers, we need to define virtual stations corresponding to the intersection of the satellite track with the river. For that purpose, we select a rectangular window taking in all available along track 10Hz (for T/P) altimetry data over the river area corresponding to at least one orbital cycle. The coordinate of the virtual station is defined as the barycenter of the selected data within the window. After rigourous data editing, all available 10 Hz data of a given cycle are combined into a single measurement through simple numerical averaging. At the time of writing, about 50 lakes and 50 virtual stations on rivers worldwide are available. The data base will be regularly fed by new rivers and lakes water level time series. In addition to revealing the spatial and temporal signature of climate variability on water levels, systematic use of satellite altimetry in large river basins might support initialization and verification of models used in forecasts of hydrological variability, and, possibly, estimates of river discharge where rating curves can be established by surface-based methods.

Gennero, M.; Cretaux, J.; Cazenave, A.

2004-12-01

131

Acidic deposition and surface water chemistry  

NASA Astrophysics Data System (ADS)

A pair of back-to-back (morning and afternoon) hydrology sessions, held December 10, 1987, at the AGU Fall Meeting in San Francisco, Calif., covered “Predicting the Effects of Acidic Deposition on Surface Water Chemistry.” The combined sessions included four invited papers, 12 contributed papers, and a panel discussion at its conclusion. The gathering dealt with questions on a variety of aspects of modeling the effects of acidic deposition on surface water chemistry.Contributed papers included discussions on the representation of processes in models as well as limiting assumptions in model application (V. S. Tripathi et al., Oak Ridge National Laboratory, Oak Ridge, Tenn., and E. C. Krug, Illinois State Water Survey, Champaign), along with problems in estimating depositional inputs to catchments and thus inputs to be used in the simulation of catchment response (M. M. Reddy et al., U.S. Geological Survey, Lakewood, Colo.; and E. A. McBean, University of Waterloo, Waterloo, Canada). L. A. Baker et al. (University of Minnesota, Minneapolis) dealt with the problem of modeling seepage lake systems, an exceedingly important portion of the aquatic resources in Florida and parts of the upper U.S. Midwest. J. A. Hau and Y. Eckstein (Kent State University, Kent, Ohio) considered equilibrium modeling of two northern Ohio watersheds that receive very different loads of acidic deposition but are highly similar in other respects.

Church, M. R.

132

Faecal pollution of surface waters in Jakarta.  

PubMed

Profuse numbers of Enterobacteriaceae were found in samples of surface waters from the Ciliwung River and adjoining canals which criss-cross metropolitan Jakarta and are used widely for domestic purposes by the poorer sections of its population. 15 of the 20 specimens gres E. coli, Klebsiella were isolated from seven and Citrobacter from four. Using enrichment culture procedures, Salmonella sp. were grown from 10 (48%) of 21 water samples examined, and 12 (63%) of aquatic sediments collected at the same sites. Altogether 14 serotypes and 37 Salmonella isolations were recorded. This high degree of faecal contamination of the environment is a major cause of the immense problem of gastro-intestinal infections in that city and probably in many similar cities in developing countries in the tropics. PMID:473327

Gracey, M; Ostergaard, P; Adnan, S W; Iveson, J B

1979-01-01

133

Water evaporation on highly viscoelastic polymer surfaces.  

PubMed

Results are reported for a study on the evaporation of water droplets from a highly viscoelastic acrylic polymer surface. These are contrasted with those collected for the same measurements carried out on polydimethylsiloxane (PDMS). For PDMS, the evaporation process involves the expected multistep process including constant drop area, constant contact angle, and finally a combination of these steps until the liquid is gone. In contrast, water evaporation from the acrylic polymer shows a constant drop area mode throughout. Furthermore, during the evaporation process, the drop area actually expands on the acrylic polymer. The single mode evaporation process is consistent with formation of wetting structures, which cannot be propagated by the capillary forces. Expansion of the drop area is attributed to the influence of the drop capillary pressure. Furthermore, the rate of drop area expansion is shown to be dependent on the thickness of the polymer film. PMID:22647193

Pu, Gang; Severtson, Steven J

2012-06-19

134

Water resources data for New Mexico, water year 1969; Part 1. Surface water records  

USGS Publications Warehouse

Beginning with the 1961 water year, surface-water records have been released by the Geological Survey in annual reports on a State-boundary basis. Distribution of these reports is limited; they are designed primarily for rapid release of data shortly after the end of the water year to meet local needs. The discharge and reservoir storage records for 1961-65 also will be published in a Geological Survey water-supply paper series entitled "Surface Water Supply of the United States 1961-65."

U.S. Geological Survey

1970-01-01

135

Water resources data for New Mexico, water year 1973; Part 1. Surface water records  

USGS Publications Warehouse

Surface-water records for the 1973 calendar year for New Mexico, including records of streamflow or reservoir storage at gaging stations, partial-record stations, and miscellaneous sites, are given in this report and their locations shown in figures 1, 2. Records for a 'few pertinent gaging stations in bordering States also are included. The records were collected and computed by the Water Resources Division of the US. Geological Survey under the direction of W. E. Hale, district chief. These data represent that portion of the National Water Data System collected by the U.S. Geological Survey and cooperating State and Federal agencies in New Mexico. Through September 30, 1960, the records of discharge and stage of streams and canals and contents and stage of lakes or reservoirs were published in an annual series of U.S. Geological Survey water supply papers entitled "Surface Water Supply of the United States" Beginning with the 1961 water year, surface-water records have been released by the Geological Survey in annual reports on a State boundary basis. Distribution of these reports is limited; they are designed primarily for rapid release of data shortly after the end of the water year to meet local needs. The discharge and reservoir storage records for 1961-65 also are published in a Geological Survey water supply paper series entitled "Surface Water Supply of the United States 1961-65." There will be a similar series of water-supply papers for the water years 1966-70.

U.S. Geological Survey

1974-01-01

136

Lawrence Livermore National Laboratory Surface Water Protection: A Watershed Approach  

Microsoft Academic Search

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

Coty

2009-01-01

137

Ground Water / Surface Water Exchange: Streambed Versus a Channel Bar  

NASA Astrophysics Data System (ADS)

The streambed is important in controlling exchange of water, solutes, and heat between streams and ground water. Processes such as sedimentation, erosion, and fluctuations in diurnal temperatures can have significant effects on the streambed hydraulic conductivity, which in turn affects fluid velocities across the streambed. The objectives of this study are to quantify the difference in flux magnitude and direction within and around a channel bar. The focus of this presentation is to compare fluxes in channel bar sediments with fluxes in the streambed to determine the effect of the upper boundary conditions on sediment fluxes. A network of piezometers was installed on and around a channel bar located within the Truckee River, a dense 6th order river network, located primarily in northwest Nevada. Instruments used were temperature loggers, pressure transducers, and stage recorders. Several methods were simultaneously utilized to quantify water and heat fluxes and to interpret the hydrodynamic processes through the streambed sediments. Numerical simulations are being completed to quantify the spatial and temporal fluid flux and heat transport in relation to varied hydraulic parameters such as variable river stage, geometry, and hydraulic conductivity. In general, we have found that surface water exchange to the streambed occurs at the upstream portion of bed features and streambed discharge dominates at the downstream bed feature. This exchange is evidenced at the channel bar as well as localized riffles and point bars adjacent to the channel bar. We found that at least two separate hydraulic conditions are evident during our study. The range in water levels between the piezometers was altered from approximately 1.25 m to a minimum of 0.10 m and the mean potentiometric surface increased by 1 m. These variations are geomorphic responses due to a flood event, inundating the channel bar, and a channel restoration project both upstream and downstream of the study area. These alterations have caused a reversal in the vertical head gradient (VHG) in some locations by up to 0.14. There also appears to be a critical stage height that alters the flux direction or magnitude. In conclusion, stage boundary conditions coupled with streambed features significantly contribute to the exchange direction. Sedimentation and erosion from restoration activities and streambed evolution also impacted fluid flux patterns due to their impact on streambed surface hydraulic conductivity patterns.

Shope, C. L.; Constantz, J. E.; Cooper, C. A.; McKay, W. A.

2007-12-01

138

Impact of surface lignite mining on surface- and ground-water quality in Texas. Final report  

Microsoft Academic Search

The impact of surface mining of Texas lignites on surface- and ground-water systems has been investigated. Surface-water and\\/or hydrogeologic analyses were conducted at two active and three proposed mines in the Texas lignite belt. Field studies supplemented by laboratory studies measured the infiltration characteristics of surface-mined land, determined the quality of surface-water runoff, and analyzed the hydrogeologic impacts of surface

C. C. Mathewson; K. W. Brown; L. E. Deuel; D. G. Kersey

1982-01-01

139

Water resources data for New Mexico, water year 1974; Part 1, Surface water records  

USGS Publications Warehouse

Surface-water records for the 1974 calendar year for New Mexico, including records of streamflow or reservoir storage at gaging stations, partial-record stations, and miscellaneous sites, are given in this report and their locations shown in figures 1, 2. Records for a few pertinent gaging stations in bordering States also are included. The records were collected and computed by the Water Resources Division of the U.S, Geological Survey under the direction of W. E. Hale, district chief. These data represent that portion of the National Water Data System collected by the U.S. Geological Survey and cooperating State and Federal agencies in New Mexico. Records of discharge and stage of streams, and contents and stage of lakes and reservoirs are published in a series of U.S. Geological Survey water-supply papers entitled, "Surface Water Supply of the United States." Through September 30, 1960, these water-supply papers were in an annual series, and since then, are in a 5-year series. More information is given under heading, "Publications" on page 8. Beginning with the 1961 water year, surface-water records have been released by the Geological Survey in annual reports on a State boundary basis. Distribution of these reports is limited; they are designed primarily for rapid release of data shortly after the end of the water year to meet local needs. Beginning with the 1971 calendar year, surface water records have been released on a calendar year basis.

Geological Survey (U.S.)

1975-01-01

140

Bubble bouncing at a clean water surface.  

PubMed

Experiments on the coalescence time of submillimeter bubbles colliding with a distilled water/air interface either being at rest (undisturbed) or vibrating vertically (with controlled amplitude and frequency) were carried out. It was found that the outcome of the bubble collision (coalescence or bounce) depends on impact velocity and size of the bubble, i.e. the parameters determining the bubble deformation degree. With the surface at rest, when the deformation of the bubble was sufficiently high, bubble bouncing was observed. It was caused by the fact that the radius of the intervening liquid film formed between the colliding bubble and water/air interface was large enough to prevent the liquid layer from reaching its thickness of rupture within the time of bubble-interface contact. Coalescence occurred in a consecutive collision if the bubble deformation was below a threshold value, as a result of dissipation of the kinetic energy associated with the bubble motion. The hypothesis about the crucial role of the bubble deformation and size of the liquid film formed in the bouncing mechanism was confirmed in a series of experiments where the bubble collided with a vibrating water/air interface. It was shown that when the kinetic energy was properly re-supplied from an external source (interface vibrations), the spectacular phenomenon of "immortal" bubbles, dancing indefinitely at the water/air interface, was achieved. It was shown that "immortal" bubble formation is a consequence of a similarly high degree of the bubble shape deformation and consequently a large enough radius of the liquid film formed. PMID:24022507

Zawala, Jan; Dorbolo, Stéphane; Vandewalle, Nicolas; Malysa, Kazimierz

2013-09-25

141

Europa: Divining Water from Surface Geology  

NASA Astrophysics Data System (ADS)

Europa's surface geology as viewed by Galileo imaging suggests a thin brittle lithosphere above a warm (potentially salt-rich) ice layer that is at least in part convecting, in turn situated above a liquid water ocean. This configuration is consistent with thermal and geochemical modeling, and with Galileo magnetometer and NIMS results, which suggest that Europa may have a salty global-scale subsurface ocean at relatively shallow depths (~20-30 km). Dynamical modeling and visible crater density suggests a surface age of ~50 million years, implying that Europa is probably still geologically active today. Large shallow craters and even larger multi-ringed structures imply impact into low-viscosity (warm) subsurface material. The satellite's bright plains are criss-crossed by narrow troughs and enigmatic double ridges (paired ridges separated by a medial trough); a morphological sequence (and implied evolutionary sequence) exists from isolated troughs to doublet ridges to wider and more complex ridge morphologies. Troughs are inferred as widened fractures formed though tensile and shear failure in response to global stressing of the ice shell above liquid water. Several models exist to explain ridges, but the most likely is one in which localized shear heating triggers upwelling of warm ice along fracture zones. Triple bands are ridges with diffuse ruddy margins that may have formed through thermal alteration and/or partial melting of briny ice. Wider pull-apart bands represent complete separation and spreading of the icy lithosphere, in a manner broadly analogous to terrestrial sea-floor spreading. Europa's global lineament pattern implies that nonsynchronous rotation and orbital flexing ("diurnal" stressing) have worked in tandem to deform the surface. Diurnal stressing can explain Europa's extremely enigmatic cycloid ridge and fracture patterns, and may drive rapid strike-slip faulting along ridges. Because significant tidal amplitude is necessary to produce significant diurnal stressing, this argues strongly for a subsurface liquid layer, but does not constrain its depth. Extremely slow nonsynchronous rotation of the ice shell may drive shear failure in equatorial regions, and may have opened the satellite's pull-apart bands. Mottled terrain consists of pits, domes, dark spots, patches of smooth plains, and regions of chaos terrain. Chaos is characterized by fragmented blocks of the preexisting surface, some of which have translated a few kilometers from their original positions, in a dark hummocky matrix. Mottled terrain landforms suggest vertical deformation and disruption of the surface along with localized partial melting. Their formation has been interpreted as due to diapiric upwelling--the expression of solid-state convection of warm subsurface ice--predicted to occur within an ice shell tens of kilometers thick above liquid water. Warm ice diapirs can circulate material between Europa's ocean and shallow levels within the ice shell, and can trigger local partial melting of briny ice, potentially creating near-surface biological niches. Europa's astonishing geology and its biological potential makes the satellite a high priority for future orbital and landed exploration.

Pappalardo, R. T.

2001-12-01

142

Interference with Fasciola hepatica snail finding by various aquatic organisms.  

PubMed

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

1977-06-01

143

Remote sensing analysis of surface water in a mining area  

NASA Astrophysics Data System (ADS)

The exploitation of the coal has brought about pollution on the surface water. That was seriously harmful to environment. Thinking of the Feicheng mining area as research area, authors tested the reflectance spectrum of waters and analyzed these curves. The paper made the computer image processing by TM computer compatible tape. Combining routine monitoring methods and TM images, the surface water of mining area was comprehensively analyzed furthermore. This paper provided a rapidly and economical method of monitoring mining area surface water.

Han, Zhen; Yang, Fengjie; Feng, Xianghua; Liu, Jiwei; Li, Yong Qing; Lei, Liqing

1999-05-01

144

Surface-water availability, Tuscaloosa County, Alabama  

USGS Publications Warehouse

The average annual runoff, about 1,270 mgd (million gallons per day), originating in Tuscaloosa County is equivalent to 20 inches or 0.95 mgd per square mile. The Black Warrior and Sipsey Rivers, the largest streams in the county, have average flows of 5,230 mgd and 580 mgd, respectively, where they leave the county, and median annual 7-day low flows in excess of 150 mgd and 35 mgd, respectively. North River, Big Sandy Creek, and Hurricane Creek have average flows in excess of 100 mgd and median annual 7-day low flows in excess of 2 mgd. Surface water generally contains less than 100 mg/l (milligrams per liter) dissolved solids, less than 10 mg/l chloride, and is soft to moderately hard. Streams having the higher hardness and the higher dissolved-solids content are in eastern Tuscaloosa County.

Knight, Alfred L.; Davis, Marvin E.

1975-01-01

145

Understanding the Surface Potential of Water  

SciTech Connect

We have resolved the apparent inconsistency in quantifying the electrochemical surface potential at the liquid-vapor interface when using explicit ab initio electronic charge density and effective atomic partial charge models of liquid water. It is shown that regions of space must be excluded for the evaluation of the electric potential from a charge distribution to be useful in the interpretation of electrochemical measurements. This is not the case for work functions, electron diffraction or electron holography measurements. We find that the resulting electric potentials from partial charge models and ab initio charge distributions are quite different except for those regions of space between the molecules where the electron density is nearly zero. We compare our computed ab initio surface potential with high-energy electron diffraction and holography measurements and find good agreement. This work was supported by the US Department of Energy Basic Energy Sciences' Chemical Sciences, Geosciences & Biosciences Division. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

Kathmann, Shawn M.; Kuo, I-F W.; Mundy, Christopher J.; Schenter, Gregory K.

2011-04-21

146

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.

2013-01-01

147

Water Resources Data for New Jersey, Water Year 1994. Volume 1. Surface-Water Data.  

National Technical Information Service (NTIS)

Volume 1 contains discharge records for 103 gaging stations; tide summaries for 9 stations; stage-only at 5 gaging stations; stage and contents for 37 lakes and reservoirs; and water quality for 95 surface-water sites. Also included are data for 70 crest-...

C. E. Gurney E. W. Moshinsky W. R. Bauersfeld

1995-01-01

148

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.

ROGER S. WOTTON and TERENCE M. PRESTON (;)

2005-02-01

149

Models for Water Outgassing from Metal Surfaces  

NASA Astrophysics Data System (ADS)

In this study, the outgassing rate from an electropolished stainless steel surface following exposures to H _2O vapor under various conditions was measured. The results of the experiments showed that the outgassing rate is proportional to p_0^{n} , where p_0 is the H _2O exposure pressure and n is about 0.25. The outgassing rate is not as strongly dependent on the system temperature as one would expect if the temperature is kept the same during exposure and pump-down. The outgassing rate is also a function of the exposure time for the first several hours of exposure, indicating that the adsorption saturation time is on the order of hours. The pump-down time of a vacuum system can be reduced significantly by reducing the moisture content of venting gases. The time taken to achieve an outgassing rate of 10^ {-10} Torr l/cm ^2 s following dry N_2 venting is about one hour in comparison to one day if the system was vented to ambient air. In the second part of this study, the effect on the water outgassing of dc glow discharge cleaning fueled by common gases was studied. It is shown that the water outgassing rate following a typical air vent can be reduced by a factor of 13 when the surface is exposed to a He glow discharge at a dose of 0.8 coulomb/cm^2 for two hours. To explain the 1/t power law obeyed by the outgassing rate and other experimental results, diffusion-type outgassing models were proposed. Initially, non-uniform H _2O concentrations throughout the oxide layer were assumed and the outgassing rate expressions were derived without taking into account the oxide layer microstructure. A more comprehensive model starts with a simplified microstructure of a porous oxide layer, which consists of cylindrical pores with a pore length distribution inversely proportional to the square of pore length. This model predicts the 1/t time dependence for the outgassing rate under saturation conditions where the coverage on the inner surfaces of the pores is uniform. It also explains the observation that the quantity of adsorbed H_2O is a linear function of the logarithm of the exposure time.

Li, Minxu

150

Water resources data, Maryland and Delaware, water year 1998, volume 1. surface-water data  

USGS Publications Warehouse

Water resources data for the 1998 water year for Maryland and Delaware consist of records of stage, discharge, and water quality of streams; stage and contents of lakes and reservoirs. This volume (Volume 1. Surface-Water Data) contains records for water discharge at 105 gaging stations; stage and contents of 1 reservoir; and water quality at 16 gaging stations. Also included are stage and discharge for 3 creststage partial-record stations, discharge only for 9 low-flow partial-record stations, and stage only for 5 tidal crest-stage partial-record stations. Additional water data were collected at various sites not involved in the systematic data-collection program and are published as miscellaneous measurements. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State, local, and Federal agencies in Maryland and Delaware.

James, Robert W., Jr.; Saffer, Richard W.; Tallman, Anthony

1999-01-01

151

Water resources data, Maryland and Delaware, water year 2001, volume 1. surface-water data  

USGS Publications Warehouse

Water resources data for the 2001 water year for Maryland and Delaware consist of records of stage, discharge, and water quality of streams; stage and contents of lakes and reservoirs. This volume (Volume 1. Surface-Water Data) contains records for water discharge at 128 gaging stations; stage and contents of 1 reservoir; and water quality at 20 gaging stations. Also included are stage and discharge for 3 creststage partial-record stations and stage only for 10 tidal crest-stage partial-record stations. Additional water data were collected at various sites not involved in the systematic data-collection program and are published as miscellaneous measurements. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State, local, and Federal agencies in Maryland and Delaware.

James, Robert W.; Saffer, Richard W.; Pentz, Robert H.; Tallman, Anthony J.

2002-01-01

152

Water resources data, Maryland and Delaware, water year 1999, Volume 1. surface-water data  

USGS Publications Warehouse

Water resources data for the 1999 water year for Maryland and Delaware consist of records of stage, discharge, and water quality of streams; stage and contents of lakes and reservoirs. This volume (Volume 1. Surface-Water Data) contains records for water discharge at 111 gaging stations; stage and contents of 1 reservoir; and water quality at 17 gaging stations. Also included are stage and discharge for 3 creststage partial-record stations, discharge only for 27 low-flow partial-record stations, and stage only for 5 tidal crest-stage partial-record stations. Additional water data were collected at various sites not involved in the systematic data-collection program and are published as miscellaneous measurements. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State, local, and Federal agencies in Maryland and Delaware.

James, Robert W.; Saffer, Richard W.; Tallman, Anthony J.

2000-01-01

153

Surface and Subsurface Water Quality Hydrology in Surface Mined Watersheds. Part I: Text.  

National Technical Information Service (NTIS)

Surface mining disturbs the natural sequence of geologic strata, and, therefore, potentially modifies the quantity and quality of water on a watershed disturbed by surface mining. Such a watershed disturbed by surface mining was monitored in Colorado. In ...

D. B. McWhorter J. W. Rowe M. W. Van Liew R. L. Chandler R. K. Skogerboe

1979-01-01

154

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

PubMed

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

2012-09-06

155

Characterization of Roughness Elements on a Water Surface  

Microsoft Academic Search

Air-water exchanges of momentum, heat and water vapor were investigated through measurements of surface fluxes and wind generated waves from a tower located 15 m offshore where water depth and fetch were about 4 m and 7 km, respectively. For the conditions of light winds and nonneutral atmospheric stratification encountered, turbulence statistics could not provide an estimate of the surface

Serhad Sabri Atakturk

1991-01-01

156

Floating Vegetated Mats For Improving Surface Water Quality  

Technology Transfer Automated Retrieval System (TEKTRAN)

Contamination of surface and ground waters is an environmental concern. Pollution from both point and nonpoint sources can render water unsuitable for use. Surface waters of concern include streams, rivers, ponds, lakes, canals, and wastewater lagoons. Lagooned wastewater from confined animal feedi...

157

Pesticide monitoring in surface water and groundwater using passive samplers  

Microsoft Academic Search

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

V. Kodes; R. Grabic

2009-01-01

158

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

1898-01-01

159

40 CFR 258.27 - Surface water requirements.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Surface water requirements. 258.27 Section 258...Operating Criteria § 258.27 Surface water requirements. MSWLF units shall not: (a) Cause a discharge of pollutants into waters of the United States, including...

2011-07-01

160

Breakdown between water drops on wet polymer surfaces  

Microsoft Academic Search

This paper describes the results of experiments made to examine the nature of discharge phenomena between water drops on polymer surfaces. Small samples of high temperature vulcanised silicone rubber were subjected to electric stress and exposed to clean and salt fog. The resulting surface activity was observed with a high-speed video camera. Water drops on the surface were found to

A. Krivda; D. Birtwhistle

2001-01-01

161

Water resources data for Florida, water year 1993. Volume 2A. South Florida surface water. Water-data report (Annual)  

Microsoft Academic Search

The data for South Florida included continuous or daily discharge for 75 streams, continuous or daily stage for 54 streams, peak stage discharge for 1 stream, continuous elevation for 1 lake; continuous ground-water levels for 203 wells, periodic ground-water levels for 299 wells and miscellaneous water-level measurements for 462 well; quality-of-water for 3 surface-water sites and 545 wells.

C. Price; M. Murray; E. Patino

1994-01-01

162

Water resources data for Florida water year 2004volume 1A. northeast Florida surface water  

USGS Publications Warehouse

Water resources data for the 2004 water year in Florida consist of continuous or daily discharge for 405 streams, periodic discharge for 12 streams, continuous or daily stage for 159 streams, periodic stage for 19 streams, peak stage and discharge for 30 streams; continuous or daily elevations for 14 lakes, periodic elevations for 23 lakes; continuous ground-water levels for 408 wells, periodic ground-water levels for 1,157 wells; quality-of-water data for 140 surface-water sites and 239 wells. The data for northeast Florida include continuous or daily discharge for 140 streams, periodic discharge for 4 streams, continuous or daily stage for 58 streams, periodic stage for 3 streams; peak stage and discharge for 0 streams; continuous or daily elevations for 10 lakes, periodic elevations for 20 lakes; continuous ground water levels for 50 wells, periodic ground-water levels for 522 wells; quality-of-water data for 40 surface-water sites and 66 wells. These data represent the National Water Data System records collected by the U.S. Geological Survey and cooperating local, State and Federal agencies in Florida.

Herrett, Thomas A.; Hess, Glen W.; House, Jon G.; Ruppert, Gregory P.; Courts, Mary-Lorraine

2005-01-01

163

Malacological survey and geographical distribution of vector snails for schistosomiasis within informal settlements of Kisumu City, western Kenya  

PubMed Central

Background Although schistosomiasis is generally considered a rural phenomenon, infections have been reported within urban settings. Based on observations of high prevalence of Schistosoma mansoni infection in schools within the informal settlements of Kisumu City, a follow-up malacological survey incorporating 81 sites within 6 informal settlements of the City was conducted to determine the presence of intermediate host snails and ascertain whether active transmission was occurring within these areas. Methods Surveyed sites were mapped using a geographical information system. Cercaria shedding was determined from snails and species of snails identified based on shell morphology. Vegetation cover and presence of algal mass at the sites was recorded, and the physico-chemical characteristics of the water including pH and temperature were determined using a pH meter with a glass electrode and a temperature probe. Results Out of 1,059 snails collected, 407 (38.4%) were putatively identified as Biomphalaria sudanica, 425 (40.1%) as Biomphalaria pfeifferi and 227 (21.5%) as Bulinus globosus. The spatial distribution of snails was clustered, with few sites accounting for most of the snails. The highest snail abundance was recorded in Nyamasaria (543 snails) followed by Nyalenda B (313 snails). As expected, the mean snail abundance was higher along the lakeshore (18 ± 12 snails) compared to inland sites (dams, rivers and springs) (11 ± 32 snails) (F1, 79 = 38.8, P < 0.0001). Overall, 19 (1.8%) of the snails collected shed schistosome cercariae. Interestingly, the proportion of infected Biomphalaria snails was higher in the inland (2.7%) compared to the lakeshore sites (0.3%) (P = 0.0109). B. sudanica was more abundant in sites along the lakeshore whereas B. pfeifferi and B. globosus were more abundant in the inland sites. Biomphalaria and Bulinus snails were found at 16 and 11 out of the 56 inland sites, respectively. Conclusions The high abundance of Biomphalaria and Bulinus spp. as well as observation of field-caught snails shedding cercariae confirmed that besides Lake Victoria, the local risk for schistosomiasis transmission exists within the informal settlements of Kisumu City. Prospective control interventions in these areas need to incorporate focal snail control to complement chemotherapy in reducing transmission.

2011-01-01

164

Paleo-environmental implication of clumped isotopes in land snail shells  

NASA Astrophysics Data System (ADS)

Clumped isotopes analyses in modern land snail shells are reported and used to interpret shell oxygen isotopes within the context of terrestrial paleo-climatology. Carbonate clumped isotopes thermometry is a new technique for estimating the temperature of formation of carbonate minerals. It is most powerful as an indicator of environmental parameters in combination with ? 18O, allowing the partitioning of the ? 18O signal into its temperature and water components. Results indicate that snail shell calcification temperatures are typically higher than either the mean annual or the snail activity season ambient temperatures. Small inter- and intra-snail variability suggests that shell aragonite forms at isotopic equilibrium so that the derived temperatures are an eco-physiological parameter reflecting snail body temperature at the time of calcification. We attribute these higher body temperatures to snail eco-physiological adaptations through shell color, morphology, and behavior. In combination with shell oxygen isotope composition, these temperatures allow us to calculate snail body water composition, which is in turn interpreted as a paleo-hydrological indicator, reflecting isotopic composition of local precipitation modified by local evaporation.

Zaarur, Shikma; Olack, Gerard; Affek, Hagit P.

2011-11-01

165

Ecology of Freshwater Snails in Opa Reservoir and Research Farm Ponds at Obafemi Awolowo University Ile-Ife, Nigeria  

Microsoft Academic Search

In a 12 month study, the ecology of freshwater snails in Opa Reservoir (OR) and Research Farm Ponds (RFPs), in Obafemi Awolowo University, Ile-Ife, Nigeria, was studied. During each monthly visit, eleven sites (seven sites in OR and four sites in RFPs) were sampled for relative snail density, vegetation cover and physicochemical properties of the water bodies. The data were

O. J. Owojori; S. O. Asaolu; I. E. Ofoezie

2006-01-01

166

Influence of salt concentrations on survival, body weight and blood chloride of the freshwater snail, Indoplanorbis exustus (Deshyes)  

Microsoft Academic Search

A study was made on I. exustus to observe the survival and osmotic regulation following transfer of snails from freshwater to different salt concentrations. The lethal salinity was found at 0.5% salt concentration. It was observed that there was loss of chloride ions in distilled water whereas the snails gained chloride in different salt concentrations. The gain of chloride ions

D. P. Vaidya; R. Nagabhushanam

1979-01-01

167

USING ARTIFICIAL NEURAL NETWORK MODELS TO INTEGRATE HYDROLOGIC AND ECOLOGICAL STUDIES OF THE SNAIL KITE IN THE EVERGLADES, USA  

Microsoft Academic Search

Hydrologists and ecologists have been working in the Everglades on integrating a long- term hydrologic data network and a short-term ecological database to support ecological models of the habitat of the snail kite, a threatened and endangered bird. Data mining techniques, including artificial neural network (ANN) models, were applied to simulate the hydrology of snail kite habitat in the Water

PAUL A. CONRADS; EDWIN ROEHL; RUBY DAAMEN; WILEY M. KITCHENS

168

Regulation of carbohydrate metabolism by the optic tentacles of the garden snail Cryptozona ligulata (Gastropoda-Stylommatophora)  

Microsoft Academic Search

Summary The presence of a hyperglycemic factor in the optic tentacles of the snailC. ligulata is reported here. A preliminary characterization based on crude extracts indicates the factor to be water-soluble, heat labile and to be an albumin. The ablation of optic tentacles and injection of optic tentacle extract into operated and normal snails caused a rise in blood sugar,

O. V. Subramanyam

1985-01-01

169

Water Resources Data - New Jersey, Water Year 1998, Volume 1, Surface-Water Data  

USGS Publications Warehouse

This volume of the annual hydrologic data report of New Jersey is one of a series of annual reports that document hydrologic data gathered from the U.S. Geological Survey's surface- and ground-water data-collection networks in each State, Puerto Rico, and the Trust Territories. These records of streamflow, ground-water levels, and water quality provide the hydrologic information needed by state, local and federal agencies, and the private sector for developing and managing our Nation's land and water resources.

Reed, T.J.; Centinaro, G.L.; Dudek, J.F.; Corcino, V.; Stekroadt, G.C.; McTigure, R.C.

1999-01-01

170

Effects of Surface Water on the Adsorption of Inert Gases.  

National Technical Information Service (NTIS)

Molecular water on mildly outgassed open oxide surfaces can, under special circumstances, significantly reduce the monolayer capacity for inert gas molecules. Non-porous thoria and cubic europia are two examples. The special proviso is that the surface be...

R. B. Gammage H. F. Holmes

1976-01-01

171

SURFACE WATER MONITORING SYSTEM INSTALLED ON BOARD THE ICEBREAKER SHIRASE  

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

Mitsuo FUKUCHI; Hiroshi HATTORI

172

Characterisation and stability of hydrophobic surfaces in water  

NASA Astrophysics Data System (ADS)

The stability of four different hydrophobic surfaces in contact with water is assessed and discussed: H-terminated silicon, hexamethyldisilazane (HMDS) coated silicon, silicon surfaces covered with self-assembled monolayers (SAMs) of octadecyltrichlorosilane (OTS) and gold surfaces modified with SAMs of alkanethiols. Changes in hydrophobicity and surface oxidation were determined by contact angle measurements, X-ray photoelectron spectroscopy and AFM.

Maccarini, M.; Himmelhaus, M.; Stoycheva, S.; Grunze, M.

2005-12-01

173

Floating Vegetated Mats for Improving Surface Water Quality  

Microsoft Academic Search

\\u000a Contamination of surface and ground waters is an environmental concern. Pollution from both point and nonpoint sources can\\u000a render water unsuitable for use. Surface waters of concern include streams, rivers, ponds, lakes, canals, and wastewater lagoons.\\u000a Lagooned wastewater from confined animal feeding operations (CAFOs) represents an extreme in water quality problems. Wastewater\\u000a lagoons are used for primary treatment which includes

Robert K. Hubbard

174

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

Microsoft Academic Search

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

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

2010-01-01

175

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

2010-01-01

176

Effects of Washing Produce Contaminated with the Snail and Slug Hosts of Angiostrongylus cantonensis with Three Common Household Solutions  

PubMed Central

The emerging infectious disease angiostrongyliasis (rat lungworm disease) is caused by ingesting snails and slugs infected by the nematode Angiostrongylus cantonensis. The definitive hosts of A. cantonensis are rats and the obligatory intermediate hosts are slugs and snails. Many cases result from accidentally ingesting infected snails or slugs on produce (eg, lettuce). This study assessed three readily available household products as washing solutions for removing snails and slugs from produce (romaine lettuce) to lower the probability of accidentally ingesting them. The solutions were acetic acid (vinegar), sodium hypochlorite (bleach), and sodium chloride (domestic salt). Snail and slug species known to be intermediate hosts and that are common in the Hawaiian Islands were used in the experiments: the alien snail Succinea tenella, the alien semi-slug Parmarion martensi, and the alien slugs Veronicella cubensis and Deroceras laeve. None of the products was any more effective than washing and rinsing with tap water alone. Most snails and slugs were removed after treatment but some remained on the lettuce even after washing and rinsing the produce. Only washing, rinsing, and then rinsing each leaf individually resulted in complete removal of all snails and slugs. The study did not address removal of any remaining slime left by the snails and slugs, nor did it address killing of worms.

Yeung, Norine W; Hayes, Kenneth A

2013-01-01

177

Water resources data for New Mexico, water year 1965; Part 1. Surface water records  

USGS Publications Warehouse

The surface-water records for the 1965 water year for gaging stations, partial-record stations, and miscellaneous sites within the State of New Mexico are given in this report. For convenience there are also Included records for a few pertinent gaging stations in bordering States. The records were collected and computed by the Water Resources Division of the U.S. Geological Survey, under the direction of W. E. Hale, District Chief, Water Resources Division. This report is the fifth In a series presenting, annually, basic data on surface-water records by States. Through September 30, 1960, the records of discharge and stage of streams and contents and stage of lakes or reservoirs were published in an annual series of U. S. Geological Survey water-supply papers entitled Surface Water Supply of the United States. Since 1951 there have been 20 volumes in the series; each volume covered an area whose boundaries coincided with those of certain natural drainage areas. The records in New Mexico were contained in Parts 7, 8 and 9 of that series. Beginning with the 1961 water year, streamflow records and related data will be released by the Geological Survey in annual reports on a State-boundary basis. Distribution of these basic-data reports will be limited and primarily for local needs. The records later will be published in Geological Survey water-supply papers at 5~year intervals. These 5-year water-supply papers will show daily discharge and will be compi led On the same geographical areas previously used for the annual series; however, some of the 14 parts of conterminous United States will be further subdivided.

U.S. Geological Survey

1966-01-01

178

Water resources data for New Mexico, water year 1964; Part I. Surface water records  

USGS Publications Warehouse

The surface-water records for the 1964 water year for gaging stations, partialrecord stations, and miscellaneous sites within the State of New Mexico are given in this report. For convenience there are also included records for a few pertinent gaging stations in bordering States. The records were collected and computed by the Water Resources Division of the U. S. Geological Survey, under the direction of W. L. Heckler, district engineer, Surface Water Branch. This report is the fourth in a series presenting, annually, basic data on surfacewater records by States. Through September 30, 1960, the records of discharge and stage of streams and contents and stage of lakes or reservoirs were published in an annual series of U. S. Geological Survey water-supply papers entitled "Surface Water Supply of the United States." Since 1951 there have been 20 volumes in the series; each volume covered an area whose boundaries coincided with those of certain natural drainage areas. The records in New Mexico were contained in Parts 7, 8, and 9 of that series. Beginning with the 1961 water year, streamflow records and related data will be released by the Geological Survey in annual reports on a State-boundary basis. Distribution of these basic-data reports will be limited and primarily for local needs. The records later will be published in Geological Survey water-supply papers at 5-year intervals. These 5-year water-supply papers will show daily discharge and will be compiled on the same geographical areas previously used for the annual series; however, some of the 14 parts of conterminous United States will be further subdivided.

U.S. Geological Survey

1965-01-01

179

Empirical acousto-optic sonar performance versus water surface condition  

Microsoft Academic Search

Developments in underwater sound detection by laser sensors probing the air-water surface are presented and discussed. Experimental results are presented that demonstrate laser sensor performance on detecting underwater sound subject to various water surface conditions. The results are used for evaluating current laser sensor capabilities and lay the foundation for future hardware design

Lynn Antonelli; Ivan Kirsteins

2001-01-01

180

Water Adsorption and Surface Conductivity Measurements on Alumina Substrates  

Microsoft Academic Search

Water adsorption and surface conductivity on ceramic substrates are important parameters in the electrochemical corrosion of thin-film metallizations and the associated growth of dendrites in humid environments. The adsorption of water provides the necessary electrolyte through which ion migration and electrochemical corrosion is possible, and the surface conductivity of the adsorbed moisture layer is a direct measure of the ion

Ben-Da Yan; S. Meilink; G. Warren; P. Wynblatt

1987-01-01

181

Total Alkalinity of Surface Waters—A National Map  

Microsoft Academic Search

This map illustrates the regional patterns of mean annual alkalinity of surface water in the conterminous United States. As such, it affords a qualitative graphic overview to the sensitivity of surface waters to acidification. The map is based on data from approximately 2,500 streams and lakes and apparent spatial correlations between these data and macrowatershed characteristics, especially land use.

James M. Omernik; Charles F. Powers

1983-01-01

182

Assessment of seasonal variations in surface water quality  

Microsoft Academic Search

Assessment of seasonal changes in surface water quality is an important aspect for evaluating temporal variations of river pollution due to natural or anthropogenic inputs of point and non-point sources. In this study, surface water quality data for 16 physical and chemical parameters collected from 22 monitoring stations in a river during the years from 1998 to 2001 were analyzed.

Y. Ouyang; P. Nkedi-Kizza; Q. T. Wu; D. Shinde; C. H. Huang

2006-01-01

183

The Application of Electric Shock as a Novel Pest Control Method for Apple Snail, Pomacea canaliculata (Gastropoda: Ampullariidae)  

NASA Astrophysics Data System (ADS)

The apple snail, Pomacea canaliculata, brought to Japan from Taiwan for human consumption in the 1980s, has come to be considered as deleterious for rice cultivation. The snail is unable to injure young rice plants while receiving electric shock because the snail retracts its entire body into its shell and shuts its aperture with its operculum. Electric shock should be applied intermittently to reduce the amount of energy that is wasted when the snail is in its shell made of one of the insulator. The minimum electric shock required for controlling snails and the time required for movement after application of electric shock to determine the frequency of each electric shock were investigated using two methods; vertical and horizontal application of the electrical stimulation. The results showed that there is a strong correlation between the strength of electric shock and the reaction of the snails, and electric shock made snails inactive when it was applied 0.35 A/m2 in the horizontal direction and 0.45 A/m2 in the vertical direction with water of 11 mS/m. A positive correlation was also found between electric shock and the reaction of the snails and shell height. In comparison with larger snails, the smaller snails had higher threshold levels against electric current density because their shorter feet tended to have lower voltage dorp. Moreover, the frequency of electric shock should be chosen the minimum duration for the inactive condition, and it was approximately 10 seconds. Consequently the direction of electric current should be in the horizontal direction above 0.35 A/m2 and the frequency of electric shock should be less than 10 seconds for practical use. However, electric shock would have to be maintained at greater than 0.35 A/m2 because snails might become habituated to electric shock and water in paddy field would have high electric conductivity.

Yagyu, Yoshihito; Tsuji, Satoshi; Satoh, Saburoh; Yamabe, Chobei

184

CHARACTERIZING RAW SURFACE WATER AMENABLE TO MINIMAL WATER SUPPLY TREATMENT  

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...

185

Terrestrial snails use predator-diet to assess danger  

Microsoft Academic Search

Some aquatic snails are able to use chemical cues (kairomones) to differentiate between predators that have fed on snails and predators that have eaten other prey. However, it is unknown if terrestrial snails are able to differentiate between snail-fed predators and predators that have not recently consumed snails. Here we document diet-based chemical discrimination of a predator, the ground beetle

Hugh Lefcort; Frida Ben-Ami; Joseph Heller

2006-01-01

186

Modeling of water outgassing from metal surfaces (III)  

SciTech Connect

A model of water adsorption on metal oxide layers and water outgassing from metal surfaces has been developed. The oxide layer is assumed to have porous structure and a pore length (l) distribution of l/l{sup 2}. Numerical evaluation shows that the quantity of water adsorbed is logarithmic with time within a certain time range as experimentally observed. The outgassing rate from surfaces with adsorbed water distributed uniformly on the inner surfaces of individual pores is shown analytically to be inversely proportional to time. This result is consistent with frequently observed pumpdown curves.

Minxu Li; H. F. Dylla

1995-06-01

187

Modeling of water outgassing from metal surfaces (III)  

SciTech Connect

A model of water adsorption on metal oxide layers and water outgassing from metal surfaces has been developed. The oxide layer is assumed to have porous structure and a pore length ({ital l}) distribution of 1/{ital l}{sup 2}. Numerical evaluation shows that the quantity of water adsorbed is logarithmic with time within a certain time range as experimentally observed. The outgassing rate from surfaces with adsorbed water distributed uniformly on the inner surfaces of individual pores is shown analytically to be inversely proportional to time. This result is consistent with frequently observed pumpdown curves. {copyright} {ital 1995} {ital American} {ital Vacuum} {ital Society}

Li, M.; Dylla, H.F. [Department of Physics, College of William and Mary, Williamsburg, Virginia 23185 (United States)]|[Continuous Electron Beam Accelerator Facility, Newport News, Virginia 23606 (United States)

1995-07-01

188

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.

2011-01-01

189

Effects of light on the orientation of the snail Physa pomillia in a weak magnetic field  

Microsoft Academic Search

1.The orientation of fresh-water snails (Physa pomillia) in a symmetrical magnetic field was studied from February to March and from September to October, 1965, during the hours 8:30 to 17:30.2.The orientation of the snails was studied in an augmented magnetic field, 9 times that of the earth's field at Gainesville, Florida, with a bar magnet aligned parallel and at right

David G. Badman

1966-01-01

190

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

Microsoft Academic Search

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

Judson W. Harvey; Jessica T. Newlin; Steven L. Krupa

2006-01-01

191

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

Microsoft Academic Search

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 43,000ha 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

Judson W. Harvey; Jessica T. Newlin; Steven L. Krupa

2006-01-01

192

Traveling Waves in Deep Water with Gravity and Surface Tension  

Microsoft Academic Search

This paper is concerned with the simulation of traveling deep-water free-surface water waves under the influence of gravity and surface tension in two and three dimensions. A variety of techniques are utilized including the numerical simulation of a weakly nonlinear model, explicit solutions of low-order perturbation theories, and the direct numerical simulation of the full water wave equations. The weakly

Benjamin Akers; David P. Nicholls

2010-01-01

193

Surface Tensions and Densities of Sulfuric Acid + Dimethylamine + Water Solutions  

Microsoft Academic Search

The surface tensions and densities of aqueous solutions of dimethylamine, (CH3)2NH, and sulfuric acid, H2SO4, were measured at 24.2 °C. Mol fractions of dimethylamine were varied between 0 and 0.21 and of sulfuric acid between 0 and 0.48. The surface tension of the binary dimethylamine + water solution decreased exponentially as dimethylamine was added, from the surface tension of water

Heikki Lihavainen; Kaisa Hautio; Tomi Raatikainen; Ari Laaksonen; Yrjö Viisanen

2004-01-01

194

SURFACE AND SUBSURFACE WATER QUALITY HYDROLOGY IN SURFACE MINED WATERSHEDS. PART I: TEXT  

EPA Science Inventory

Surface mining disturbs the natural sequence of geologic strata, and, therefore, potentially modifies the quantity and quality of water on a watershed disturbed by surface mining. Such a watershed disturbed by surface mining was monitored in Colorado. In addition, surface runoff,...

195

Simulating continental surface waters: An application to Holocene northern Africa  

SciTech Connect

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{prime} {times} 5{prime} 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. 73 refs., 6 figs., 2 tabs.

Coe, M.T. [Univ. of Wisconsin, Madison, WI (United States)

1997-07-01

196

Substrate-dependent reactivity of water on metal carbide surfaces  

SciTech Connect

The interaction of water with two transition metal carbide (TiC) and vanadium carbide (VC), has been investigated. The adsorption, reaction, and desorption of water on the (100) face of single-crystal samples of these materials have been studied as a function of substrate temperature over the range 100--600 K. The adsorption state of water on these surfaces has been probed with high resolution electron energy loss spectroscopy (HREELS). The reactivity of water has been directly measured with HREELS and X-ray photoelectron spectroscopy (XPS). The desorption of molecular water and the products of surface reactions has been followed with temperature programmed desorption. Collectively, these measurements indicate that water adsorbs both molecularly and dissociatively on TiC and VC; however, a greater degree of reactivity at cryogenic temperatures is observed on TiC. Dissociation of water produces surface bound hydrogen and hydroxyl groups on both surfaces and a fully dissociated surface oxide on TiC. Furthermore, a greater participation of the surface carbon atoms in observed at the TiC surface through the evolution of CO{sub x} species at elevated temperatures. The differences in surface bonding and desorption profiles are discussed in terms of differences in electronic structure of the two metal carbides. Some possible implications of these studies for the use of TiC and VC as tribological materials are also discussed.

Didziulis, S.V.; Frantz, P.; Perry, S.S.; El-bjeirami, O.; Imaduddin, S.; Merrill, P.B.

1999-12-16

197

Diffuse pollution of surface water by pharmaceutical products  

Microsoft Academic Search

Pharmaceutical products for humans or animals, as well as their related metabolites (degradation products) end up in the aquatic environment after use. Recent investigations from abroad show that low concentrations of pharmaceuticals are detectable in municipal waste water, surface water, groundwater and even drinking water. Little is known about the effects, and with that the risk, of long term exposure

J. G. M. Derksen; G. B. J. Rijs; R. H. Jongbloed

2004-01-01

198

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

1995-01-01

199

Surface Water Quality Risk Assessment Through UV-Visible Spectrophotometer  

Microsoft Academic Search

2 Abstract: The present study is aimed at assessing the water quality index (WQI) for the surface and ground water in the study area of Attock City, Punjab, Pakistan. This has been determined by collecting 30 wate r samples each from boreholes, municipal water supply and Kabul River. For calculating the WQI, the following parameters have been considered: temperature, pH,

Muhammad Qasim; Abida K Khan; Rehana Rashid; Sadia Nasreen; Qaisar Mahmood; Jamil Khan

2009-01-01

200

Dust deposition to the surface waters of the western and central North Pacific inferred from surface water dissolved aluminum concentrations  

Microsoft Academic Search

Dissolved Al was determined on ?3500 surface water samples collected in the NW Pacific during the 2002 Intergovernmental Oceanographic Commission (IOC) Contaminant Baseline survey. In addition, dissolved Al was determined on samples collected at 9 vertical stations occupied along the cruise track. Surface water Al distributions, when converted to annual mineral dust deposition (Measures and Brown, 1996), imply extremely low

C. I. Measures; M. T. Brown; S. Vink

2005-01-01

201

Assessing nitrogen pressures on European surface water  

Microsoft Academic Search

The European environmental legislation on water, in particular the 2000 Water Framework Directive, requires the evaluation of nutrient pressures and the assessment of mitigation measures at the river basin scale. Models have been identified as tools that can contribute to fulfill these requirements. The objective of this research was the implementation of a modeling approach (Geospatial Regression Equation for European

B. Grizzetti; F. Bouraoui; G. De Marsily

2008-01-01

202

Water resources data for New Mexico, water year 1968; Part 1. Surface water records  

USGS Publications Warehouse

The surface-water records for the 1968 water year for gaging stations, partial record stations, and miscellaneous sites within the State of New Mexico are given in this report. For convenience there are also included records for a few pertinent gaging stations in bordering States. The records were collected and computed by the Water Resources Division of the U. S. Geological Survey, under the direction of W. E. Hale, District Chief, Water Resources Division. This report is the eighth in a series presenting, annually, basic data on surfacewater records by States. Through September 30, 1960, "the records of discharge and stage of streams and contents and stage of lakes or reservoirs were published in an annual series of U. S. Geological Survey water-supply papers entitled "Surface Water Supply of the United States.!! Since 1951 there have been 20 volumes in the series; each volume covered an area whose boundaries coincided with those of certain natural drainage areas. The records in New Mexico were contained in Parts 7, 8, and 9 of that series. Beginning with the 1961 water year, streamflow records and related data have been released by the Geological Survey in annual reports on a State-boundary basis. Distribution of these basic-data reports is limited and primarily for local needs. The records will be published in Geological Survey water-supply papers at 5-year intervals. These 5-year water-supply papers will show daily discharge and will be compiled on the same geographical areas previously used for the annual series; however, some of the 14 parts of conterminous United States will be further subdivided.

U.S. Geological Survey

1969-01-01

203

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

2010-05-01

204

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.

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

2011-01-01

205

Availability of Water In The Upper Martian Surface  

NASA Astrophysics Data System (ADS)

Availability of water in the upper Martian surface D. Möhlmann, DLR Institut für Raumsimulation51170, Köln,Germany Email:dirk.moehlmann@dlr.de It is the cur- rent opinion that at present water in the upper Martian surface is in the ice-phase. This ice can be found, if at all, at mid- and equatorial latitudes only in depths of decameters or deeper. Thus, water is expected to exist in the Martian surface far away from layers which are reached by the diurnal or seasonal solar radiation caused thermal wave. On the other side, morning fog indicates at some locations the existence of water in the upper surface layers, what are by definition those, which can be reached by the ther- mal wave. It is assumed since Viking (Jakosky et al., 1997) that this water has to be expected to be bound to the soil as adsorbate water in the upper surface l ayers above the ice in deeper layers. Model results are presented, which indicate for different soil parameters the possible amount of absorbate water in the upper Martian surface. It is expected that this adsorbate water may well be of biological importance.

Moehlmann, D.

206

Health Aspects of Surface Water Supplies.  

National Technical Information Service (NTIS)

Current EPA regulations are insufficient to prevent the waterborne transmission of disease, as waterborne outbreaks have occurred in systems which have not exceeded current regulation for coliforms and turbidity. Waterborne outbreaks reported in surface w...

G. F. Craun

1987-01-01

207

Multivariate analyses of water chemistry: surface and ground water interactions.  

PubMed

Multivariate statistical methods (MSMs) applied to ground water chemistry provide valuable insight into the main hydrochemical species, hydrochemical processes, and water flowpaths important to ground water evolution. The MSMs of principal component factor analysis (FA) and k-means cluster analysis (CA) were sequentially applied to major ion chemistry from 211 different ground water-sampling locations in the Amargosa Desert. The FA reduces the number of variables describing the system and finds relationships between major ions. The CA of the reduced system produced objective hydrochemical facies, which are independent of, but in good agreement with, lithological data. The derived factors and hydrochemical facies are innovatively presented on biplots, revealing composition of hydrochemical processes and facies, and overlaid on a digital elevation model, displaying flowpaths and interactions with geologic and topographic features in the region. In particular, a distinct ground water chemical signature is observed beneath and surrounding the extended flowpath of Fortymile Wash, presenting some contradiction to contemporary water levels along with potential interaction with a fault line. The signature surrounding the ephemeral Fortymile Wash is believed to represent the relic of water that infiltrated during past pluvial periods when the amount of runoff in the wash was significantly larger than during the current drier period. This hypothesis and aforementioned analyses are supported by the examination of available chloride, oxygen-18, hydrogen-2, and carbon-14 data from the region. PMID:18194324

Woocay, Arturo; Walton, John

2008-01-09

208

The interaction of water with environmentally relevant surfaces  

SciTech Connect

Probing the coverage and chemical speciation of molecules at surfaces are of fundamental interest in molecular environmental science. The concentration of water and its dissociation fragments at surfaces affect many highly important interfacial chemical processes and there exist no previous quantitative determinations of the coverage of water on clean metal surfaces at near ambient conditions. We have utilized Ambient Pressure Photoelectron Spectroscopy (AP-PES) to study the water/Cu(111) and Cu(110) systems at pressures up to 1 Torr in the temperature range 270-470 K.

Andersson, K.; Yamamoto, S.; Ketteler, G.; Starr, D.E.; Nilsson, A.; Salmeron, M.; Bluhm, H.

2006-04-05

209

Impact of Raw Water Ammonia on the Surface Water Treatment Processes and Its Removal by Nitrification  

Microsoft Academic Search

Impact of raw water ammonia on the treated water quality and removal of ammonia from surface water were studied. Raw water ammonia and physicochemical quality of treated water of Saidabad Water Treatment Plant were analyzed for the period of one year (January through December 2006). The monthly averages of maximum (7.55 mg\\/l) and minimum (0.34 mg\\/l) ammonia-N level of the

M Alamgir Hossain; ANM Fakhruddin; Sirajul Islam Khan

2007-01-01

210

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

2003-01-01

211

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

1997-01-01

212

A siphon gage for monitoring surface-water levels  

USGS Publications Warehouse

A device that uses a siphon tube to establish a hydraulic connection between the bottom of an onshore standpipe and a point at the bottom of a water body was designed and tested for monitoring surface-water levels. Water is added to the standpipe to a level sufficient to drive a complete slug of water through the siphoning tube and to flush all air out of the system. The water levels in the standpipe and the water body equilibrate and provide a measurable static water surface in the standpipe. The siphon gage was designed to allow quick and accurate year-round measurements with minimal maintenance. Currently available devices for monitoring surface-water levels commonly involve time-consuming and costly installation and surveying, and the movement of reference points and the presence of ice cover in cold regions cause discontinuity and inaccuracy in the data collected. Installation and field testing of a siphon gage using 0.75-in-diameter polyethylene tubing at Ashumet Pond in Falmouth, Massachusetts, demonstrated that the siphon gage can provide long-term data with a field effort and accuracy equivalent to measurement of ground-water levels at an observation well.A device that uses a siphon tube to establish a hydraulic connection between the bottom of an onshore standpipe and a point at the bottom of a water body was designed and tested for monitoring surface-water levels. Water is added to the standpipe to a level sufficient to drive a complete slug of water through the siphoning tube and to flush all air out of the system. The water levels in the standpipe and the water body equilibrate and provide a measurable static water surface in the standpipe. The siphon gage was designed to allow quick and accurate year-round measurements with minimal maintenance. Currently available devices for monitoring surface-water levels commonly involve time-consuming and costly installation and surveying, and the movement of reference points and the presence of ice cover in cold regions cause discontinuity and inaccuracy in the data collected. Installation and field testing of a siphon gage using 0.75-in-diameter polyethylene tubing at Ashumet Pond in Falmouth, Massachusetts, demonstrated that the siphon gage can provide long-term data with a field effort and accuracy equivalent to measurement of ground-water levels at an observation well.

McCobb, T. D.; LeBlanc, D. R.; Socolow, R. S.

1999-01-01

213

Remote surface water monitoring radio based telemetry system.  

National Technical Information Service (NTIS)

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 microelectronic...

W. L. Goodwin D. Baxter

1993-01-01

214

Remote Synoptic Surface Flow Measurements in Small Bodies of Water.  

National Technical Information Service (NTIS)

This thesis describes a novel approach to remote and synoptic surface flow measurements in small bodies of water; it also includes an investigation to determine the practicality of this technique. The approach is based on imaging monochromatic wavetrains,...

D. Sheres J. D. Isaacs

1980-01-01

215

Scale Variations in Groundwater-Surface Water Interactions.  

National Technical Information Service (NTIS)

The purpose of this research is to examine spatial and seasonal variations in the contributions of groundwater flow to streamflow and the infiltration of surface water to groundwater. The research was conducted in humid temperature watersheds in Wisconsin...

K. L. Prestegaard

1997-01-01

216

Assessment of Shallow Water Near Surface Response of Submersible Vehicles.  

National Technical Information Service (NTIS)

Vertical plane response of submersible vehicles in the proximity of a free surface in both deep and shallow waters is evaluated using a potential flow, strip theory solver. Three criteria, namely periscope submergence, sail broaching, and collision are us...

U. Toprak

1996-01-01

217

TRACE ORGANIC CONTAMINANTS IN ANTHROPOGENICALLY ACIDIFIED SURFACE WATERS  

EPA Science Inventory

The biological effects of trace organic contaminants in anthropogenically acidified surface waters are mediated by the nature of the association of trace organics with dissolved and particulate organic matter (DOC and POC). his paper (1) briefly reviews available deposition estim...

218

Second Inflection Point of the Surface Tension of Water  

NASA Astrophysics Data System (ADS)

The theme of a second inflection point of the temperature dependence of the surface tension of water remains a subject of controversy. Using data above 273 K, it is difficult to get a proof of existence of the second inflection point, because of experimental uncertainties. Data for the surface tension of supercooled water and results of a molecular dynamics study were included into the exploration of existence of an inflection point. A new term was included into the IAPWS equation to describe the surface tension in the supercooled water region. The new equation describes the surface tension values of ordinary water between 228 K and 647 K and leads to the inflection point value at a temperature of about 1.5 °C.

Kalova, Jana; Mares, Radim

2012-06-01

219

Adsorption of Water on Surface Acoustic Wave Gas Sensors.  

National Technical Information Service (NTIS)

Surface acoustic wave sensors (SAWS) respond to mass adsorbed onto chemically specific coatings put upon the acoustic wave transmission path. Target gas response is perturbed by naturally present atmospheric water vapor. This work measured the response of...

C. G. Fox J. F. Adler

1988-01-01

220

Rates, Constants, and Kinetics Formulations in Surface Water Quality Modeling.  

National Technical Information Service (NTIS)

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 (s...

C. W. Chen D. Deimer S. W. Zison W. B. Mills

1978-01-01

221

Unique water-water coordination tailored by a metal surface  

NASA Astrophysics Data System (ADS)

At low coverage of water on Cu(110), substrate-mediated electrostatics lead to zigzagging chains along [001] as observed with STM [T. Yamada, S. Tamamori, H. Okuyama, and T. Aruga, ``Anisotropic water chain growth on Cu(110) observed with scanning tunneling microscopy'' Phys. Rev. Lett. 96, 036105 (2006)]. Using x-ray absorption spectroscopy we find an anomalous low-energy resonance at ~533.1 eV which, based on density functional theory spectrum simulations, we assign to an unexpected configuration of water units whose uncoordinated O-H bonds directly face those of their neighbors; this interaction repeats over trough sites with enhanced electron density and is analogous to the case of a hydrated electron.

Schiros, T.; Andersson, K. J.; MacNaughton, J.; Gladh, J.; Matsuda, A.; Öström, H.; Takahashi, O.; Pettersson, L. G. M.; Nilsson, A.; Ogasawara, H.

2013-06-01

222

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

2002-01-01

223

Spiral-wound Module Nanofiltration of Surface River Water  

Microsoft Academic Search

The performance of the nanofiltration of surface water, using a spiral-wound module, was accessed for the particular case of the Tagus River surface water collected at ca. 40 km of Lisbon (Portugal). The nanofiltration experiments were performed in the nanofiltration laboratory unit with a spiral wound module with 2.6 m2 of membrane area (Filmtec NF270- 2540, DOW Chemical), for different

Vítor Geraldes; Maria Norberta de Pinho; Carlos Manuel Simões Fonseca; Elizabeth Duarte

224

Rutile fibers in surface waters of northern New Jersey  

Microsoft Academic Search

Transmission electron microscope (TEM) analyses of surface water samples from the northern New Jersey (USA) area indicate that rutile (TiO2) is a consistent contaminant, with fiber concentrations ranging from 0.2 to 1.5 million fibers per liter (MFL), and averaging 0.7 MFL. Concentrations of rutile fiber were comparable to or somewhat higher than asbestos concentrations in ambient surface water samples. Rutile

John H. Puffer; Mark Germine; Gerard P. Maresca

1987-01-01

225

Planktonic foraminifera as recorders of past surface-water stratification  

Microsoft Academic Search

The delta18O difference between shallow- and deep-living planktonic foraminifera is a proxy for the stratification of surface waters. In Holocene sediments from the Atlantic this difference increases from about 00\\/00 in subpolar regions to ˜30\\/00 in the tropics. The delta18O values of the shallow dwellers Globigerinoides sacculifer and Neogloboquadrina pachyderma mainly reflect surface-water conditions. The calcification depth of the deep-living

Stefan Mulitza; Anke Dürkoop; Walter Hale; Gerold Wefer; Hans Stefan Niebler

1997-01-01

226

Celss nutrition system utilizing snails  

NASA Astrophysics Data System (ADS)

At the 40th IAF Congress in Malaga, a nutrition system for a lunar base CELSS was presented. A lunar base with a total of eight crew members was envisaged. In this paper, four species of plants—rice, soybean, lettuce and strawberry—were introduced to the system. These plants were sufficient to satisfy fundamental nutritional needs of the crew members. The supply of nutrition from plants and the human nutritional requirements could almost be balanced. Our study revealed that the necessary plant cultivation area per crew member would be nearly 40 m 3 in the lunar base. The sources of nutrition considered in the study were energy, sugar, fat, amino acids, inorganic salt and vitamins; however, calcium, vitamin B 2, vitamin A and sodium were found to be lacking. Therefore, a subsystem to supply these elements is of considerable value. In this paper, we report on a study for breeding snails and utilizing meat as food. Nutrients supplied from snails are shown to compensate for the abovementioned lacking elements. We evaluate the snail breeder and the associated food supply system as a subsystem of closed ecological life support system.

Midorikawa, Y.; Fujii, T.; Ohira, A.; Nitta, K.

227

Fungal farming in a snail.  

PubMed

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

2003-12-04

228

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.

Silliman, Brian R.; Newell, Steven Y.

2003-01-01

229

Surface water records of New Mexico, water year 1962  

USGS Publications Warehouse

year intervals. These 5-year water-supply papers will show daily discharge and will be compiled on the same geographical areas previously used for the annual series; however, some of the 14 parts of conterminous United States will be further subdivided.

U.S. Geological Survey

1963-01-01

230

Landfill disposal of unused medicines reduces surface water releases.  

PubMed

The pharmaceutical industry is conducting research to evaluate the pathways and fate of active pharmaceutical ingredients from the consumer to surface waters. One potential pathway identified by the researchers is the disposal of unused pharmaceutical products that are discarded by consumers in household trash and disposed of in municipal solid waste landfills. This study was designed to evaluate relative amounts of surface water exposures through the landfill disposal pathway compared to patient use and flushing of unused medicine pathways. The estimated releases to surface water of 24 example active pharmaceutical ingredients (APIs) in landfill leachate were calculated for 3 assumed disposal scenarios: 5%, 10%, and 15% of the total annual quantity of API sold is discarded and unused. The estimated releases from landfills to surface waters, after treatment of the leachate, were compared to the total amount of each example API that would be released to surface waters from publicly owned treatment works, generated by patient use and excretion. This study indicates that the disposal of unused medications in municipal solid waste landfills effectively eliminates the unused medicine contribution of APIs to surface waters; greater than 99.9% of APIs disposed of in a landfill are permanently retained. PMID:22556107

Tischler, Lial; Buzby, Mary; Finan, Douglas S; Cunningham, Virginia L

2012-09-18

231

Dropwise condensation rate of water breath figures on polymer surfaces having similar surface free energies  

NASA Astrophysics Data System (ADS)

This study investigates the effect of surface roughness, wettability, water contact angle hysteresis (CAH) and wetting hysteresis (WH) of polymeric substrates to the water drop condensation rate. We used five polyolefin coatings whose surface free energies were in a close range of 30-37 mJ/m2 but having different surface roughness and CAH. The formation of water breath figures was monitored at a temperature just below the dew point. The initial number of the condensed droplets per unit area (N0) and droplet surface coverage were determined during the early stage of drop condensation where the droplet coalescence was negligible. It was found that the mean drop diameter of condensed droplets on these polymer surfaces grow according to a power law with exponent 1/3 of time, similar to the previous reports given in the literature. It was determined that surface roughness and corresponding CAH and WH properties of polymers have important effects on the number of nucleation sites and growth rate of the condensed water droplets. N0 values and the surface coverage increased with the increase in surface roughness, CAH and WH of the polymer surfaces. The total condensed water drop volume also increased with the increase in surface roughness in accordance with the increase of the number of nucleated droplets.

Ucar, Ikrime O.; Erbil, H. Yildirim

2012-10-01

232

Models for Water Outgassing from Metal Surfaces  

Microsoft Academic Search

In this study, the outgassing rate from an electropolished stainless steel surface following exposures to H _2O vapor under various conditions was measured. The results of the experiments showed that the outgassing rate is proportional to p_0^{n} , where p_0 is the H _2O exposure pressure and n is about 0.25. The outgassing rate is not as strongly dependent on

Minxu Li

1994-01-01

233

Perfluorinated Surfactants in Surface and Drinking Waters  

Microsoft Academic Search

Goal, Scope and Background. Perfluorinated surfactants (e.g. PFOS and PFOA) have shown different potentials for reproductory interfer- ence and carcinogenity in animal experiments as well as partly long half-lives in humans. They possess compound-dependent extreme re- calcitrance against microbiological and chemical degradation and, in addition, they show variable potentials for bioaccumulation in ani- mals and humans. Methods. Surface and drinking

Martin JW; Smithwick MM; Hoekstra PF; Muir DCG

234

Effect of humic acid on water chemistry, bioavailability and toxicity of aluminium in the freshwater snail, Lymnaea stagnalis, at neutral pH  

Microsoft Academic Search

The influence of humic acid on the water chemistry of environmentally relevant concentrations of Al at neutral pH was studied, together with its effect on the bioavailability and toxicity of Al in Lymnaea stagnalis. Humic acid significantly reduced the loss of Al from the water and increased the fraction of filterable Al, although this was a relatively small fraction of

A. Dobranskyte; R. Jugdaohsingh; C. R. McCrohan; E. Stuchlik; J. J. Powell; K. N. White

2006-01-01

235

SURFACE WATER QUALITY PARAMETERS FOR MONITORING OIL SHALE DEVELOPMENT  

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...

236

Tritium in surface waters of the Yenisei River basin.  

PubMed

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

2003-01-01

237

Melting characteristics of horizontal ice surfaces in cold saline water  

Microsoft Academic Search

The results of an experimental investigation of the buoyancy driven flow adjacent to and below a horizontal ice surface melting in cold water at near oceanic salinity are presented. This melting configuration is characteristic of circumistances encountered by sea ice, for example, by new ice and, also, on the bottom of tabular ice floes. Several ambient water temperatures t, are

Benjamin Gebhart; Bahgat Sammakia; Tore Audunson

1983-01-01

238

PESTICIDE CONCENTRATIONS IN SURFACE WATERS OF MISSISSIPPI LAKES AND RESERVOIRS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Surface water samples from lakes and reservoirs throughout Mississippi were collected and analyzed on a seasonal basis during 2002-2003 as part of a water quality survey. The purpose of the pesticide study was to produce a significant addition of baseline information to 1) ascertain current conditi...

239

Pilot Study on Treatment of Surface Water for Groundwater Injection  

Microsoft Academic Search

A groundwater recharge demonstration project sponsored by the US Bureau of Reclamation is being conducted by the Salt Lake County Water Conservancy District in Utah. Treated surface water will be injected in winter into the aquifer through injection wells and recovered through separate wells during the peak summer months. The conveyance capacity of the project will be 1,000 gpm (5.5

Eva C. Nieminski; Susan L. Fenhaus

1991-01-01

240

Iron in Surface and Subsurface Waters, Grizzly Bar, Southeastern Alaska.  

National Technical Information Service (NTIS)

Glacial sediment and outwash are common surface materials in Alaska, and they usually contain significant amounts of iron-bearing minerals. Surface and subsurface waters on and in these sediments have been observed to contain iron, and in places, some par...

C. M. Hoskin R. M. Slatt

1972-01-01

241

Structure Detection in Infrared Imagery of Water Surfaces  

Microsoft Academic Search

Various thresholding and edge detection algorithms have been implemented on a sequence of infrared (IR) imagery of water surfaces in attempt to detect surface structures indicative of natural convection heat transfer. Presented herein are the results from 1) Otsu's thresholding method as well as local entropy thresholding (LET) and 2) the Sobel, Prewitt, Roberts, Laplacian of Gaussian (LoG), and Canny

S. M. Bower

242

Dynamic surface tension of coal-water slurry fuels  

Microsoft Academic Search

Experiments were conducted to measure the dynamic surface tension of coal-water slurry (CWS) mixtures containing various types of surfactants and with different coal loadings. A maximum air bubble pressure technique measured the dynamic surface tension. The coal used for the CWS had 55 ?m volume mean diameter (VMD) and was mined from the Upper Elkhorn seam, Virginia. Five surfactants were

Ken D. Kihm; Paul Deignan

1995-01-01

243

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

2003-01-01

244

Electrostatic transportation of water droplets on superhydrophobic surfaces  

Microsoft Academic Search

This article reports electrostatic transportation of water droplets on superhydrophobic alkylketene dimer (AKD) and Teflon AFR surfaces. The actuation is based on electrostatic forces generated by metal electrodes placed underneath the surface. By switching the electrode voltages, the droplets moved stepwise along the electrode paths. The lowest voltage which resulted continuous movement was 124 VAC (rms) and the maximum speed

Altti Torkkeli; Jaakko Saarilahti; Ari Haara; Harri Harma; Tero Soukka; Pertti Tolonen

2001-01-01

245

Effect of water table dynamics on land surface hydrologic memory  

Microsoft Academic Search

The representation of groundwater dynamics in land surface models has received considerable attention in recent years. Most studies have found that soil moisture increases after adding a groundwater component because of the additional supply of water to the root zone. However, the effect of groundwater on land surface hydrologic memory (persistence) has not been explored thoroughly. In this study we

Min-Hui Lo; James S. Famiglietti

2010-01-01

246

Oil\\/Water separation with surface modified membranes  

Microsoft Academic Search

This study examines the feasibility of designing a membrane surface which would enhance the separation of oil from oil\\/water suspensions using crossflow filtration. The surface characteristics of both Ultrafiltration and microfiltration membranes were modified by adsorption with a surfactant, resulting in significant improvement in oil rejection.

G. K. Anderson; C. B. Saw; M. S. Le

1987-01-01

247

Langmuir circulation inhibits near-surface water turbulence  

NASA Astrophysics Data System (ADS)

In the surface ocean, breaking waves are a major source of air bubbles and turbulent kinetic energy. During the presence of a consistent surface wind, these wave-generated bubbles, along with other surface material like seaweed or foam, can be drawn into long rows along the surface. Driving this organization is Langmuir circulation, a phenomenon in which the wind and waves cause surface waters to rotate helically, moving like a wire wrapped around a pole in the windward direction. These spiral currents oscillate between clockwise and counterclockwise rotations, such that in some places the surface waters are pushed together and in others they are pulled apart. Researchers have previously found that at sites of convergence the bubbles produced by breaking waves are pushed to depths of 15 meters or more, with important implications for air-sea gas mixing and other processes.

Schultz, Colin

2012-07-01

248

Snail modulates cell metabolism in MDCK cells.  

PubMed

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(+)-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. PMID:23438434

Haraguchi, Misako; Indo, Hiroko P; Iwasaki, Yasumasa; Iwashita, Yoichiro; Fukushige, Tomoko; Majima, Hideyuki J; Izumo, Kimiko; Horiuchi, Masahisa; Kanekura, Takuro; Furukawa, Tatsuhiko; Ozawa, Masayuki

2013-02-21

249

Using water isotopes in the evaluation of land surface models  

NASA Astrophysics Data System (ADS)

Several studies show that uncertainties in the representation of land surface processes contribute significantly to the spread in projections for the hydrological cycle. Improvements in the evaluation of land surface models would therefore translate into more reliable predictions of future changes. The isotopic composition of water is affected by phase transitions and, for this reason, is a good tracer for the hydrological cycle. Particularly relevant for the assessment of land surface processes is the fact that bare soil evaporation and transpiration bear different isotopic signatures. Water isotopic measurement could thus be employed in the evaluation of the land surface hydrological budget. With this objective, isotopes have been implemented in the most recent version of the land surface model ORCHIDEE. This model has undergone considerable development in the past few years. In particular, a newly discretised (11 layers) hydrology aims at a more realistic representation of the soil water budget. In addition, biogeophysical processes, as, for instance, the dynamics of permafrost and of its interaction with snow and vegetation, have been included. This model version will allow us to better resolve vertical profiles of soil water isotopic composition and to more realistically simulate the land surface hydrological and isotopic budget in a broader range of climate zones. Model results have been evaluated against temperature profiles and isotopes measurements in soil and stem water at sites located in semi-arid (Yatir), temperate (Le Bray) and boreal (Labytnangi) regions. Seasonal cycles are reasonably well reproduced. Furthermore, a sensitivity analysis investigates to what extent water isotopic measurements in soil water can help constrain the representation of land surface processes, with a focus on the partitioning between evaporation and transpiration. In turn, improvements in the description of this partitioning may help reduce the uncertainties in the land surface hydrological response to climate change. The work is partly supported by the grant of Ministry of Education and Science of RF under the contract N^ 11.G34.31.0064.

Guglielmo, Francesca; Risi, Camille; Ottlé, Catherine; Bastrikov, Vladislav; Valdayskikh, Victor; Cattani, Olivier; Jouzel, Jean; Gribanov, Konstantin; Nekrasova, Olga; Zacharov, Vyacheslav; Ogée, Jérôme; Wingate, Lisa; Raz-Yaseef, Naama

2013-04-01

250

Effects of surface water on the adsorption of inert gases  

Microsoft Academic Search

Molecular water on mildly outgassed open oxide surfaces can, under special circumstances, significantly reduce the monolayer capacity for inert gas molecules. Non-porous thoria and cubic europia are two examples. The special proviso is that the surface be sufficiently uniform to permit the formation of a well structured, ice-like surface with non-polar character. This type of behavior reaches an extreme for

R. B. Gammage; H. F. Holmes

1976-01-01

251

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.

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

2013-01-01

252

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

PubMed

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

2013-10-23

253

Biological control of the snail intermediate hosts of Schistosoma mansoni in Martinique, French West Indies.  

PubMed

In Martinique water-cress beds constituted the last transmission sites for schistosomiasis. The competitor snail, Melanoides tuberculata, was introduced at the beginning of 1983 to a group of water-cress beds and eliminated the snail hosts, Biomphalaria glabrata and B. straminea, in less than two years. Following this first success, M. tuberculata was introduced to the other groups of beds which were inventoried at the beginning of the eighties. At the present time, B. glabrata and B. straminea have totally disappeared from eight sites and only a few individuals have been recorded from 12 sites. The two remaining water-cress beds have dried up and were abandoned. PMID:1519033

Pointier, J P; Guyard, A

1992-06-01

254

Drainage areas of selected surface-water sites in Florida  

USGS Publications Warehouse

Drainage areas for about 1,500 surface-water sites on streams and lakes in Florida are contained in this report. Sites are described in relation to a nearby city or town, and are located by county, by latitude-longitude, and by topographic map on which it is located. In addition, the surface areas of lakes are shown for the elevation given on the topographic map. These data were retrieved from the Surface Water Index developed and maintained by the Hydrologic Records Section of the Florida District office of the U.S. Geological Survey.

Foose, Donald W.

1980-01-01

255

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.

Barbosa, Frederico S.; Olivier, Louis

1958-01-01

256

Tensile testing of ultra-thin films on water surface  

NASA Astrophysics Data System (ADS)

The surface of water provides an excellent environment for gliding movement, in both nature and modern technology, from surface living animals such as the water strider, to Langmuir-Blodgett films. The high surface tension of water keeps the contacting objects afloat, and its low viscosity enables almost frictionless sliding on the surface. Here we utilize the water surface as a nearly ideal underlying support for free-standing ultra-thin films and develop a novel tensile testing method for the precise measurement of mechanical properties of the films. In this method, namely, the pseudo free-standing tensile test, all specimen preparation and testing procedures are performed on the water surface, resulting in easy handling and almost frictionless sliding without specimen damage or substrate effects. We further utilize van der Waals adhesion for the damage-free gripping of an ultra-thin film specimen. Our approach can potentially be used to explore the mechanical properties of emerging two-dimensional materials.

Kim, Jae-Han; Nizami, Adeel; Hwangbo, Yun; Jang, Bongkyun; Lee, Hak-Joo; Woo, Chang-Su; Hyun, Seungmin; Kim, Taek-Soo

2013-10-01

257

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

PubMed

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

2000-08-01

258

Circumnutation on the water surface: female flowers of Vallisneria.  

PubMed

Circumnutation, the helical movement of growing organ tips, is ubiquitous in land plants. The mechanisms underlying circumnutation have been debated since Darwin's time. Experiments in space and mutant analyses have revealed that internal oscillatory (tropism-independent) movement and gravitropic response are involved in circumnutation. Female flower buds of tape grass (Vallisneria asiatica var. biwaensis) circumnutate on the water surface. Our observations and experiments with an artificial model indicated that gravitropism is barely involved in circumnutation. Instead, we show that helical intercalary growth at the base of peduncle plays the primary role in all movements in Vallisneria. This growth pattern produces torsional bud rotation, and gravity and buoyancy forces have a physical effect on the direction of peduncle elongation, resulting in bud circumnutation on the water surface. In contrast to other water-pollinated hydrophilous plants, circumnutation in Vallisneria enables female flowers to actively collect male flowers from a larger surface area of water. PMID:23355948

Kosuge, Keiko; Iida, Satoko; Katou, Kiyoshi; Mimura, Tetsuro

2013-01-25

259

Surface Water Quality in Minnesota: The Translation of Goals and Policies into Results.  

National Technical Information Service (NTIS)

The study of focuses on problems of translating public policy goals relating to surface water quality into reality. Surface water pollution is seen as a result of economic incentives. Broad policy alternatives for addressing surface water pollution are ex...

J. J. Waelti

1975-01-01

260

SARAH2: A NEAR FIELD EXPOSURE ASSESSMENT MODEL FOR SURFACE WATER  

EPA Science Inventory

The near field surface water model (SARAH2) calculates maximum allowable hazardous waste concentrations, based on predicted exposure to humans or aquatic life from contaminated surface water. The surface water contamination pathways analyzed in SARAH2 include groundwater leachate...

261

Extreme ``water repellency'' on strong water-spreading surface without tilted degree actuation  

Microsoft Academic Search

We report the self-running off phenomenon of microdroplet on strong water-spreading surface without any tilted degree actuation. It is found that when water droplet is deposited continuously gently on the porous superhydrophilic surface, the first droplet can spread strongly out in not more than 350 ms, while the subsequent droplet will run rapidly off the surface in 60-120 ms, in

Yongmei Zheng; Lei Jiang; Jingxia Wang; Dong Han

2008-01-01

262

Inquiry, Land Snails, and Environmental Factors  

ERIC Educational Resources Information Center

|Land snails are common invertebrates that fascinate children. Unfortunately, they are seldom used for activities in the science classroom. Snails are inexpensive, take up little space in the classroom, and require only low maintenance, and their learning dividends can be enormous. For example, students can use them in inquiry-based activities…

Barrow, Lloyd H.; Krantz, Patrick D.

2005-01-01

263

DETECTION OF A GROUND-WATER/SURFACE-WATER INTERFACE WITH DIRECT-PUSH EQUIPMENT  

EPA Science Inventory

A ground-water/surface-water interface (GSI) was documented at the Thermo Chem CERCLA Site in Muskegon, MI via direct-push (DP) sampling. At that time, contaminated ground water flowed from the upland area of the site into the Black Creek floodplain. DP rods equipped with a 1.5...

264

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

2007-01-01

265

MONITORING OXIDATION-REDUCTION PROCESS DURING GROUND WATER-SURFACE WATER INTERACTIONS AT THE CHICKASAW NRA  

EPA Science Inventory

Mineralized ground waters at the Chickasaw National Recreational Area contain hydrogen sulfide, i.e., sulfur in the -2 valence state. As these mineralized ground waters discharge at the surface and mix with oxygen-rich waters a series of abiotic and biotic reactions occur that c...

266

Distribution patterns and cercarial shedding of Bulinus nasutus and other snails in the Msambweni area, Coast Province, Kenya.  

PubMed

In the Msambweni area of the Kwale District in Kenya, an area endemic for Schistosoma haematobium, potential intermediate-host snails were systematically surveyed in water bodies associated with human contact that were previously surveyed in the 1980s. Bulinus (africanus) nasutus, which accounted for 67% of the snails collected, was the only snail shedding S. haematobium cercariae. Lanistes purpureus was the second most common snail (25%); lower numbers of Bulinus forskalii and Melanoides tuberculata were also recovered. Infection with non-S. haematobium trematodes was found among all snail species. Rainfall was significantly associated with the temporal distribution of all snail species: high numbers of Bulinus nasutus developed after extensive rainfall, followed, in turn, by increased S. haematobium shedding. Spatial distribution of snails was significantly clustered over a range of up to 1 km, with peak clustering observed at a distance of 400 meters. Water lily (Nymphaea spp.) and several aquatic grass species appeared necessary for local colonization by B. nasutus or L. purpureus. PMID:15100463

Kariuki, H Curtis; Clennon, Julie A; Brady, Melinda S; Kitron, Uriel; Sturrock, Robert F; Ouma, John H; Ndzovu, Saidi Tosha Malick; Mungai, Peter; Hoffman, Orit; Hamburger, Joseph; Pellegrini, Cara; Muchiri, Eric M; King, Charles H

2004-04-01

267

Palaeoclimatic implications of isotopic data from modern and early Holocene shells of the freshwater snail Melanoides tuberculata, from lakes in the Ethiopian Rift Valley  

Microsoft Academic Search

Carbon and oxygen isotope ratios in the shells of the freshwater snail Melanoides tuberculata yield information on the isotopic composition of the water in which the shell was formed, which in turn relates to climatic conditions prevailing during the snails' life span. Melanoides is particularly important because it is widespread in Quaternary deposits throughout Africa and Asia and is ubiquitous

Melanie J. Leng; Angela L. Lamb; Henry F. Lamb; Richard J. Telford

1999-01-01

268

The Oxygen, Hydrogen and Carbon Isotope Compositions of Modern Freshwater and Terrestrial Snails, Pinery Provincial Park, Southern Great Lakes Area, Canada  

Microsoft Academic Search

We have compared the oxygen, hydrogen and carbon isotope compositions of several species of modern freshwater and terrestrial snails from a variety of ecosystems in Pinery Provincial Park, southwestern Ontario. The Park is located on the shore of Lake Huron, within a temperate-humid climatic regime. The aquatic snails have a range of oxygen and hydrogen isotope body-water compositions with a

J. Heidenheim; F. Longstaffe

2005-01-01

269

A Mechanism for Near-Surface Water Ice on Mars  

NASA Astrophysics Data System (ADS)

Recent findings (e.g., Byrne et al, 2009) indicate that water ice lies very close to the surface at mid-latitudes on Mars. Re-interpretation of neutron and gamma-ray data is consistent with water ice buried less than a meter or two below the surface. Hydrothermal convection of brines provides a mechanism for delivering water to the near-surface. Previous numerical and experimental studies with pure water have indicated that hydrothermal circulation of pore water should be possible, given reasonable estimates of geothermal heat flux and regolith permeability. For pure water convection, the upper limit of the liquid zone would lie at some depth, but in the case of salt solutions, the boundary between liquid and frozen pore water could reach virtually to the surface. The principal drivers for hydrothermal circulation are regolith permeability, geothermal heat flux, surface temperature and salt composition. Both the Clifford and the Hanna-Phillips models of Martian regolith permeability predict sufficiently high permeabilities to sustain hydrothermal convection. Salts in solution will concentrate in upwelling plumes as the cold surface is approached. As water ice is excluded upon freezing, the remaining solution becomes a more concentrated brine, reaching its eutectic concentration before freezing. Numerical simulations considering several salts (NaCl, CaCl2, MgSO4), and a range of heat fluxes (20 - 100 mW/m2) covering the range of estimated present day heat flux (20 to 40 mW/m2) to moderately elevated conditions (60 to 100 mW/m2) such as might exist in the vicinity of volcanoes and craters, all indicate the same qualitative behavior. A completely liquid, convective regime occurs at depth, overlain by a partially frozen "mushy" layer (but still convecting despite the increased viscosity), overlain by a thin frozen layer at the surface. The thicknesses of these layers depend on the heat flux, surface temperature and the salt. As heat flux increases, the mushy region lies closer and closer to the surface, and the frozen layer thins. At the higher heat fluxes (> 60 mW/m2), upwelling plumes can deliver liquid brine to within a few meters of the surface, even breaching it for the salts with very low eutectic points.

Travis, B. J.; Feldman, W. C.; Maurice, S.

2009-12-01

270

Can snails ever be effective and safe biocontrol agents?  

Microsoft Academic Search

The use of snails as biocontrol agents against other snails and against aquatic weeds is reviewed, evaluating their success and their impacts on non-target organisms. The predatory snail Euglandina rosea (and other species), although widely used against Achatina fulica (the giant African land snail) on Pacific and Indian Ocean islands, has not been shown to control A. fulica but has

Robert H. Cowie

2001-01-01

271

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

2009-03-16

272

Model for outgassing of water from metal surfaces  

SciTech Connect

Numerous measurements of outgassing from metal surfaces show that the outgassing obeys a power law of the form Q=Q{sub 10}t{sup -alpha}, where alpha is typically near unity. For unbaked systems, outgassing is dominated by water. This work demonstrates that alpha is a function of the water vapor exposure during venting of the system, and the physical properties of the passivation oxide layer on the surface. An analytic expression for the outgassing rate is derived based on the assumption that the rate of water diffusing through the passivation oxide layer to the surface governs the rate of its release into the vacuum. The source distribution function for the desorbing water is assumed to be a combination of a Gaussian distribution centered at the interior surface driven by atmospheric exposure, and a uniform concentration throughout the bulk. We have measured the outgassing rate from a clean stainless-steel (type 304) chamber as a function of water exposure to the chamber surface from <1 to 600 monolayers. The measured outgassing rate data show that alpha tends to 0.5 for low H{sub 2}O exposures and tends to 1.5 for high H{sub 2}O exposures as predicted by the model.

Minxu Li; Fred Dylla

1993-06-01

273

First-principles study of water on Cu (110) surface  

NASA Astrophysics Data System (ADS)

The persistent demand for cheaper and high efficient catalysts in industrial chemical synthesis, such as ammonia, and in novel energy applications, hydrogen generation and purification in fuel cells motivated us to study the fundamental interaction involved in water-Cu system, with an intension to examine Cu as a possible competitive candidate for cheaper catalysts. Water structure and dissociation kinetics on a model open metal surface: Cu (110), have been investigated in detail based on first-principles electronic structure calculations. We revealed that in both monomer and overlayer forms, water adsorbs molecularly, with a high tendency for diffusion and/or desorption rather than dissociation on clean surfaces at low temperature. With the increase of the water coverage on the Cu (110) surface, the H-bond pattern lowers the dissociation barrier efficiently. More importantly, if the water molecule is dissociated, the hydrogen atoms can diffuse freely along the [110] direction, which is very useful in the hydrogen collection. In addition, we extended to study water on other noble metal (110) surfaces. The result confirms that Cu (110) is the borderline between intact and dissociative adsorption, differing in energy by only 0.08 eV. This may lead to promising applications in hydrogen generation and fuel cells.

Ren, Jun; Meng, Sheng

2009-03-01

274

Combined effects of dissolved oxygen concentration and water temperature on embryonic development and larval shell secretion in the marine snail Chorus giganteus (Gastropoda: Muricidae)  

Microsoft Academic Search

The present study was undertaken to determine the effects of both extracapsular oxygen concentration and temperature on embryonic development in Chorus giganteus. In normoxia increasing water temperature from 12°C to 18°C reduced by 15 days the median time required for the capsules to hatch. Hypoxia (oxygen content at 50% of air saturation) generated a low development rate and totally prevented

J. M. Cancino; J. A. Gallardo; F. A. Torres

2003-01-01

275

Bacterial flora of the schistosome vector snail Biomphalaria glabrata.  

PubMed Central

The aerobic heterotrophic bacterial flora in over 200 individuals from 10 wild populations and 3 laboratory colonies of the schistosome vector snail Biomphalaria glabrata was examined. Internal bacterial densities were inversely proportional to snail size and were higher in stressed and laboratory-reared snails. The numerically predominant bacterial genera in individual snails included Pseudomonas, Acinetobacter, Aeromonas, Vibrio, and several members of the Enterobacteriaceae. Enterobacteriaceae seldom predominated in laboratory colonies. Our data suggest that Vibrio extorquens and a Pasteurella sp. tend to predominate in high-bacterial-density snails. These snails may be compromised and may harbor opportunistic snail pathogens.

Ducklow, H W; Boyle, P J; Maugel, P W; Strong, C; Mitchell, R

1979-01-01

276

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.

2010-12-01

277

Using surface tension data to predict differences in surface and bulk concentrations of nonelectrolytes in water  

PubMed Central

Recently, we developed a quantitative interpretation of surface tension increments (STI) of salts, acids, and bases in terms of the solute (or salt ion) partitioning model (SPM). Here, we obtain an analogous SPM-based interpretation of surface tension increments of nonelectrolytes, which yields local-bulk partition coefficients (Kp) quantifying the accumulation or exclusion of these solutes in the local region near the air-water surface, and the amount of water per unit area of that region (b1?). Sucrose exhibits the largest positive STI (approximately 1.4 ergs cm?2 Osm?1). Assuming that Kp = 0 for sucrose (i.e. that it is completely excluded from the surface of water), these STI provide a minimum estimate of b1? of 0.20 H2O/Å2, or a minimum thickness of the surface region of approximately two layers of water at bulk density. This is the same value as obtained previously from analysis of surface tension and hydrocarbon solubility increments of Na2SO4 and also for the interaction of glycine betaine with anionic carboxylate surface, indicating that this quantity is not a function of the type of solute or surface investigated and therefore that it may represent the molecular thickness of the region. Partition coefficients of other nonelectrolytes investigated range from moderately excluded (e.g urea) to moderately accumulated (e.g. glycerol, ethylene glycol); strongly accumulated surface active solutes (e.g. mono-substituted alcohols) were not included in this analysis. Partition coefficients for many salt ions obtained from STI and hydrocarbon solubility increments fall in a rank order which corresponds to the Hofmeister series for protein folding and protein solubility, indicating a common pattern of accumulation or exclusion of salt ions at the air-water surface and nonpolar surfaces of dissolved hydrocarbons and proteins; no such patterns are observed for nonelectrolytes.

Pegram, Laurel M.; Record, M. Thomas

2009-01-01

278

Ecology of Schistosome Dermatitis in Western and Northern Nevada Waters.  

National Technical Information Service (NTIS)

Human dermatitis caused by schistosome flukes has been periodically reported from Nevada waters. The dermatitis-causing schistosomes are parasites of some species of freshwater snails, and a survey of freshwater snails of western and northern Nevada was m...

R. L. Church

1969-01-01

279

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

2012-12-01

280

GROUND-WATER DRAINAGE TO SURFACE MINES REFINED.  

USGS Publications Warehouse

Changes in seepage flux and hydraulic head (ground-water level) resulting from ground-water drainage into the first and subsequent cuts of a surface coal mine can be estimated by a technique that considers drainage from the unsaturated zone and drainage effects of the advancing mine. A 'single-layer' technique is used, in which each layer of a stratified aquifer system is considered separately. Use of the technique requires knowledge of some aquifer characteristics at the proposed mining site and an estimate of the rate of approach of the advancing surface mine.

Weiss, Linda, S.

1985-01-01

281

Aluminum in acidic surface waters: chemistry, transport, and effects.  

PubMed Central

Ecologically significant concentrations of Al have been reported in surface waters draining "acid-sensitive" watersheds that are receiving elevated inputs of acidic deposition. It has been hypothesized that mineral acids from atmospheric deposition have remobilized Al previously precipitated within the soil during soil development. This Al is then thought to be transported to adjacent surface waters. Dissolved mononuclear Al occurs as aquo Al, as well as OH-, F-, SO4(2-), and organic complexes. Although past investigations have often ignored non-hydroxide complexes of Al, it appears that organic and F complexes are the predominant forms of Al in dilute (low ionic strength) acidic surface waters. The concentration of inorganic forms of Al increases exponentially with decreases in solution pH. This response is similar to the theoretical pH dependent solubility of Al mineral phases. The concentration of organic forms of Al, however, is strongly correlated with variations in organic carbon concentration of surface waters rather than pH. Elevated concentrations of Al in dilute acidic waters are of interest because: Al is an important pH buffer; Al may influence the cycling of important elements like P, organic carbon, and trace metals; and Al is potentially toxic to aquatic organisms. An understanding of the aqueous speciation of Al is essential for an evaluation of these processes.

Driscoll, C T

1985-01-01

282

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

283

Generation and dynamics of aerosols over water surface  

Microsoft Academic Search

The mechanisms of generation of aerosols at water surface and their dependences on the local state of the atmosphere and water\\u000a bodies, and also on the transport processes in the atmosphere have been studied. The possible disperse and chemical compositions\\u000a of aerosols and their main determining factors and also the role of aerosols in the interaction between the ocean and

N. A. Mishchuk; V. V. Goncharuk

2011-01-01

284

Cold Water Jets on a Hot Si surface  

Microsoft Academic Search

We are using a femtosecond pump-probe apparatus to study heat transfer when a pulsed jet of liquid water impinges on a hot Pt-coated Si surface (Leidenfrost Effect). The light source in the experiment is a 100 mW Er:fiber laser operating at a wavelength of lambda=1550 nm; the total volume of the pulsed water jet is ˜0.9 mm^3. The temperature change

Ji Yong Park; Chang-Ki Min; David Cahill; Steve Granick

2010-01-01

285

Hydrodynamic boundary condition of water on hydrophobic surfaces  

NASA Astrophysics Data System (ADS)

By combining total internal reflection fluorescence cross-correlation spectroscopy with Brownian dynamics simulations, we were able to measure the hydrodynamic boundary condition of water flowing over a smooth solid surface with exceptional accuracy. We analyzed the flow of aqueous electrolytes over glass coated with a layer of poly(dimethylsiloxane) (advancing contact angle ? = 108°) or perfluorosilane (? = 113°). Within an error of better than 10 nm the slip length was indistinguishable from zero on all surfaces.

Schaeffel, David; Yordanov, Stoyan; Schmelzeisen, Marcus; Yamamoto, Tetsuya; Kappl, Michael; Schmitz, Roman; Dünweg, Burkhard; Butt, Hans-Jürgen; Koynov, Kaloian

2013-05-01

286

The Surface Water and Ocean Topography Mission: a mission concept to study the world's oceans and fresh water  

Microsoft Academic Search

The Surface Water and Ocean Topography (SWOT) is a planned satellite mission to study the world's oceans and terrestrial surface water bodies. The SWOT mission concept has been proposed jointly by the global Hydrology and Oceanography science communities to make the first global survey of the Earth's surface water, observe the fine details of the ocean's surface topography, and measure

Parag Vaze; Vincent Albuys; Daniel Esteban-Fernandez; Thierry Lafon; Juliette Lambin; Alain Mallet; Ernesto Rodriguez

2010-01-01

287

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

PubMed

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

2012-11-21

288

Surface Water Data at Los Alamos National Laboratory 1998 Water Year  

SciTech Connect

The principal investigators collected and computed surface water discharge data from 19 stream-gaging stations that cover most of Los Alamos National Laboratory. Also included are discharge data from three springs that flow into Caiion de Vane.

D. A. Shaull; M. R. Alexander; R. P. Reynolds; C. T. McLean; R. P. Romero

1999-02-01

289

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

EPA Science Inventory

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

290

Hydration structure of water confined between mica surfaces  

NASA Astrophysics Data System (ADS)

We report further molecular dynamics simulations on the structure of bound hydration layers under extreme confinement between mica surfaces. We find that the liquid phase of water is maintained down to 2 monolayer (ML) thick, whereas the structure of the K+ ion hydration shell is close to the bulk structure even under D=0.92 nm confinement. Unexpectedly, the density of confined water remains approximately the bulk value or less, whereas the diffusion of water molecules decreases dramatically. Further increase in confinement leads to a transition to a bilayer ice, whose density is much less than that of ice Ih due to the formation of a specific hydrogen-bonding network.

Leng, Yongsheng; Cummings, Peter T.

2006-02-01

291

Surface properties of the polarizable Baranyai-Kiss water model.  

PubMed

The water surface properties using the Baranyai-Kiss (BK) model [A. Baranyai and P. T. Kiss, J. Chem. Phys. 133, 144109 (2010)] are studied by molecular dynamics simulation, and compared to popular rigid water potentials, namely to the extended simple point charge (SPC/E) and the transferable interaction potential with 4 points (TIP4P) models. The BK potential is a polarizable model of water with three Gaussian charges. The negative charge is connected to its field-free position by a classical harmonic spring, and mechanical equilibrium is established between this spring force and the force due to the charge distribution of the system. The aim of this study is, on the one hand, to test the surface properties of the new model, and on the other hand, to identify differences between the models listed above. The obtained results reveal that the BK model reproduces very well a number of properties corresponding to liquid-vapor equilibrium, such as the coexisting liquid and vapor densities, saturated vapor pressure or surface tension. Further, this model reproduces excellently the critical point of water even in comparison with a large number of widely used polarizable and nonpolarizable models. The structural properties of the liquid surface of BK water turns out to be very similar to that of the SPC/E model, while the surface of TIP4P water is found to be somewhat less ordered. This finding is related to the fact that the critical temperature of the TIP4P model is lower than that of either SPC/E or BK. PMID:22443789

Kiss, Péter; Darvas, Mária; Baranyai, András; Jedlovszky, Pál

2012-03-21

292

The effects of endosulfan on the great ramshorn snail Planorbarius corneus (Gastropoda, Pulmonata): a histopathological study.  

PubMed

In this study the great ramshorn snail (Planorbarius corneus), one of the most abundant gastropod of Turkish limnic systems, was investigated to determine the histopathological effects of endosulfan on the digestive gland, foot and mantle under laboratory conditions. Samples were collected from small artificial pools in Karaot at Gelendost-Isparta (southwest of Turkey), where agricultural activities are widespread. The snails were exposed to two sublethal concentrations of endosulfan (0.4 and 0.8 mg/l) for periods of 10, 20 and 30 days. Fifteen snails were kept in 2.5 l glass jars containing dechlorinated tap water and exposed under semi-static test (daily exchange of test water). All the testing was carried out on adult specimens, and snails were maintained on a photothermal period with 16 light hours at 22 +/- 2 degrees C. The histopathological examinations revealed the following changes: amoebocytes infiltration, dilatation in hemolymphatic spaces between the tubules, degeneration of cells, abnormal lumen, necrosis of cells and atrophy in the connective tissue of digestive gland; desquamation of the epithelium cells, changes in the number of mucocytes and protein gland cells, lipid vacuolus and atrophy of the columnar muscle fibers of the foot and mantle tissues. Pycnotic state of cells was also seen in the mantle tissues. Endosulfan caused significant histopathological alterations in the digestive gland, foot and mantle tissues of the snail, irrespective of concentrations of the pesticide and its exposure periods. The results are discussed, particularly in comparison to those of other aquatic organisms. PMID:15234168

Otludil, Birgül; Cengiz, Elif Ipek; Yildirim, M Zeki; Unver, Ozkan; Unlü, Erhan

2004-08-01

293

Water loss through evaporation from water surfaces of lakes and reservoirs in Turkey  

Microsoft Academic Search

The objective of this study2 was to estimate the amount of evaporative loss from fresh water lake and reservoir surfaces in Turkey and to compare it with supplied water in Turkey. In this study 129 lakes and 223 reservoirs were subjected to evaporation estimates. The total surface area was 3213.97 km2 and 4026.16 km2 for the lakes and the reservoirs,

Ferhat Gökbulak; Süleyman Özhan

2006-01-01

294

Spring and surface water quality of the Cyprus ophiolites  

NASA Astrophysics Data System (ADS)

A survey of surface, spring and borehole waters associated with the ophiolite rocks of Cyprus shows five broad water types (1) Mg-HCO3, (2) Na-SO4-Cl-HCO3, (3) Na-Ca-Cl-SO4-OH-CO3, (4) Na-Cl-SO4 and (5) Ca-SO4. The waters represent a progression in chemical reactivity from surface waters that evolve within a groundwater setting due to hydrolysis of the basic/ultrabasic rock as modified by CO2-weathering. An increase in salinity is also observed which is due to mixing with a saline end-member (modified sea-water) and dissolution of gypsum/anhydrite. In some cases, the waters have pH values greater than 11. Such high values are associated with low temperature serpentinisation reactions. The system is a net sink for CO2. This feature is related not only to the hydrolysis of the primary minerals in the rock, but also to CaCO3 or Ca-Mg-CO3 solubility controls. Under hyperalkaline conditions, virtually all the carbon dioxide is lost from the water due to the sufficiently high calcium levels and carbonate buffering is then insignificant. Calcium sulphate solubility controls may also be operative when calcium and sulphate concentrations are particularly high.

Neal, C.; Shand, P.

295

Nanostructures increase water droplet adhesion on hierarchically rough superhydrophobic surfaces.  

PubMed

Hierarchical roughness is known to effectively reduce the liquid-solid contact area and water droplet adhesion on superhydrophobic surfaces, which can be seen for example in the combination of submicrometer and micrometer scale structures on the lotus leaf. The submicrometer scale fine structures, which are often referred to as nanostructures in the literature, have an important role in the phenomenon of superhydrophobicity and low water droplet adhesion. Although the fine structures are generally termed as nanostructures, their actual dimensions are often at the submicrometer scale of hundreds of nanometers. Here we demonstrate that small nanometric structures can have very different effect on surface wetting compared to the large submicrometer scale structures. Hierarchically rough superhydrophobic TiO(2) nanoparticle surfaces generated by the liquid flame spray (LFS) on board and paper substrates revealed that the nanoscale surface structures have the opposite effect on the droplet adhesion compared to the larger submicrometer and micrometer scale structures. Variation in the hierarchical structure of the nanoparticle surfaces contributed to varying droplet adhesion between the high- and low-adhesive superhydrophobic states. Nanoscale structures did not contribute to superhydrophobicity, and there was no evidence of the formation of the liquid-solid-air composite interface around the nanostructures. Therefore, larger submicrometer and micrometer scale structures were needed to decrease the liquid-solid contact area and to cause the superhydrophobicity. Our study suggests that a drastic wetting transition occurs on superhydrophobic surfaces at the nanometre scale; i.e., the transition between the Cassie-Baxter and Wenzel wetting states will occur as the liquid-solid-air composite interface collapses around nanoscale structures. Consequently, water adheres tightly to the surface by penetrating into the nanostructure. The droplet adhesion mechanism presented in this paper gives valuable insight into a phenomenon of simultaneous superhydrophobicity and high water droplet adhesion and contributes to a more detailed comprehension of superhydrophobicity overall. PMID:22263866

Teisala, Hannu; Tuominen, Mikko; Aromaa, Mikko; Stepien, Milena; Mäkelä, Jyrki M; Saarinen, Jarkko J; Toivakka, Martti; Kuusipalo, Jurkka

2012-02-03

296

Geochemical characterization of surface water and spring water in SE Kashmir Valley, western Himalaya: Implications to water-rock interaction  

NASA Astrophysics Data System (ADS)

Water samples from precipitation, glacier melt, snow melt, glacial lake, streams and karst springs were collected across SE of Kashmir Valley, to understand the hydrogeochemical processes governing the evolution of the water in a natural and non-industrial area of western Himalayas. The time series data on solute chemistry suggest that the hydrochemical processes controlling the chemistry of spring waters is more complex than the surface water. This is attributed to more time available for infiltrating water to interact with the diverse host lithology. Total dissolved solids (TDS), in general, increases with decrease in altitude. However, high TDS of some streams at higher altitudes and low TDS of some springs at lower altitudes indicated contribution of high TDS waters from glacial lakes and low TDS waters from streams, respectively. The results show that some karst springs are recharged by surface water; Achabalnag by the Bringi stream and Andernag and Martandnag by the Liddar stream. Calcite dissolution, dedolomitization and silicate weathering were found to be the main processes controlling the chemistry of the spring waters and calcite dissolution as the dominant process in controlling the chemistry of the surface waters. The spring waters were undersaturated with respect to calcite and dolomite in most of the seasons except in November, which is attributed to the replenishment of the CO2 by recharging waters during most of the seasons.

Jeelani, Gh; Bhat, Nadeem A.; Shivanna, K.; Bhat, M. Y.

2011-10-01

297

Water Resources Data for New Mexico; Part 1, Surface Water Records  

USGS Publications Warehouse

Surface-water records for the 1970 water year for New Mexico, including records of streamflow or reservoir storage at gaging stations, partial-record stations, and miscellaneous sites, are given in this report and their locations shown in figures 1, 2. Records for a few pertinent gaging stations in bordering States also are included. The records were collected arid computed by the Water Resources Division of the U.S. Geological Survey under the direction of W. E. Hale, district chief. These data represent that portion of the National Water Data System collected by the U.S. Geological Survey and cooperating State and Federal agencies in New Mexico. Through September 30, 1960, the records of discharge and stage of streams and canals and contents and stage of lakes or reservoirs were published in an annual series of U.S. Geological Survey water-supply papers entitled II Surface Water Supply of the United States." Beginning with the 1961 water year, surface-water records have been released by the Geological Survey in annual reports on a State-boundary basis. Distribution of these reports is limited; they are designed primarily for rapid release of data shortly after the end of the water year to meet local needs. The discharge and reservoir storage records for 1961-65 also are published in a Geological Survey water-supply paper series entitled "Surface Water Supply of the United States 1961-65." There will be a similar series of water-supply papers for the water years 1966-70.

U.S. Geological Survey

1971-01-01

298

LASER SPECTROSCOPY OF MINERAL OILS ON THE WATER SURFACE  

Microsoft Academic Search

The spectral properties of oil films ranging from sub-micrometer thickness up to an optically thick layer on the water surface are studied under controlled laboratory conditions. LIDAR systems operating at excita- tion wavelengths of 308 and 355 nm were used in these experiments. Measurements of the fluorescence lifetime were performed for different mineral oils. It was found that the decay

S. Patsayeva; V. Yuzhakov; V. Varlamov; R. Barbini; R. Fantoni

2000-01-01

299

Observation of water condensate on hydrophobic micro textured surfaces  

NASA Astrophysics Data System (ADS)

We visually observed that a dropwise condensation occurred initially and later changed into a filmwise condensation on hydrophobic textured surface at atmosphere pressure condition. It was observed that the condensate nucleated on the pillar side walls of the micro structure and the bottom wall adhered to the walls and would not be lifted to form a spherical water droplet using environmental scanning electron microscope.

Kim, Ki Wook; Do, Sang Cheol; Ko, Jong Soo; Jeong, Ji Hwan

2013-07-01

300

RATES, CONSTANTS, AND KINETICS FORMULATIONS IN SURFACE WATER QUALITY MODELING  

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...

301

Monitoring of endocrine disrupting chemicals in surface water  

Microsoft Academic Search

Environmentally prevalent endocrine disrupting chemicals (EDCs) may interfere with the bodies' complex and carefully regulated hormonal messenger system (endocrine system). They can mimic or block chemicals naturally found in the body, alter hormonal levels, and thus, affect functions that these hormones control. Potential EDCs can be found among pesticides, plasticizers, pharmaceuticals, cosmetic ingredients, household products and industrial chemicals. Surface waters

S. Govender; W. T. Williams; P. Swart

302

Assessment of the surface water quality in Northern Greece  

Microsoft Academic Search

The application of different multivariate statistical approaches for the interpretation of a large and complex data matrix obtained during a monitoring program of surface waters in Northern Greece is presented in this study. The dataset consists of analytical results from a 3-yr survey conducted in the major river systems (Aliakmon, Axios, Gallikos, Loudias and Strymon) as well as streams, tributaries

V. Simeonov; J. A. Stratis; C. Samara; G. Zachariadis; D. Voutsa; A. Anthemidis; M. Sofoniou; Th. Kouimtzis

2003-01-01

303

Modeling the relationship between land use and surface water quality  

Microsoft Academic Search

It is widely known that watershed hydrology is dependent on many factors, including land use, climate, and soil conditions. But the relative impacts of different types of land use on the surface water are yet to be ascertained and quantified. This research attempted to use a comprehensive approach to examine the hydrologic effects of land use at both a regional

Susanna T. Y. Tong; Wenli Chen

2002-01-01

304

REMOTE MONITORING OF ORGANIC CARBON IN SURFACE WATERS  

EPA Science Inventory

This study shows that the intensity of the Raman normalized fluorescence emission induced in surface waters by ultraviolet radiation can be used to provide a unique remote sensing capability for airborne monitoring the concentration of dissolved organic carbon (DOC). Trace concen...

305

CONTROLLING STORM WATER RUNOFF WITH TRADABLE CREDITS FOR IMPERVIOUS SURFACES  

EPA Science Inventory

Storm water flow off impervious surface in a watershed can lead to stream degradation, habitat alteration, low base flows and toxic leading. We show that a properly designed tradable runoff credit (TRC) system creates economic incentives for landowners to employ best management p...

306

Seasonal melting of surface water ice condensing in martian gullies  

Microsoft Academic Search

In this work we consider when and how much liquid water during present climate is possible within the gullies observed on the surface of Mars. These features are usually found on poleward directed slopes. We analyse the conditions for melting of H2O ice, which seasonally condenses within the gullies. We follow full annual cycle of condensation and sublimation of atmospheric

Konrad J. Kossacki; Wojciech J. Markiewicz

2004-01-01

307

PHOTOREACTIONS IN SURFACE WATERS AND THEIR ROLE IN BIOGEOCHEMICAL CYCLES  

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...

308

Evaluating Surface-Soil Water Content by Measuring Reflectance  

Microsoft Academic Search

Water's property to absorb certain wavelengths in the near infrared was the basis for developing a reflectometer to measure reflectance of near-infrared radiation from a soil surface. The reflectometer's essential elements include: source of infrared radiation, optical system, integrating sphere, detector, light chopper, amplifier, and meter system. The radiation from an incandescent lamp was filtered with narrow-band pass filter, chopped

E. L. SKIDMORE; J. D. DICKERSON; H. SCHIMMELPFENNIG

1974-01-01

309

Investigating the Interface of Superhydrophobic Surfaces in Contact With Water.  

National Technical Information Service (NTIS)

Neutron reflectivity (NR) is used to probe the solid, liquid, vapor interface of a porous superhydrophobic (SH) surface submerged in water. A low-temperature, low-pressure technique was used to prepare a rough, highly porous organosilica aerogel-like film...

A. P. Malanoski D. A. Doshi E. D. Branson P. B. Shah S. Singh

2005-01-01

310

Federalism and the surface-water program. Technical report  

Microsoft Academic Search

This report is part of the National Network for Environmental Management Studies (NNEMS) under the auspices of the Office of Cooperative Environmental Management of the U.S. Environmental Protection Agency. The report presents the results of a study of the impact of federalism on state surface-water programs. The study focuses on the historical pattern of federal funding and the impact of

Hill

1988-01-01

311

Partition Coefficients for Metals in Surface Water, Soil, and Waste.  

National Technical Information Service (NTIS)

This report presents metal partition coefficients for the surface water pathway and for the source model used in the Multimedia, Multi-pathway, Multi-receptor Exposure and Risk Assessment (3MRA) technology under development by the U.S. Environmental Prote...

J. D. Allison T. L. Allison

2005-01-01

312

The hydrochemical framework of surface water basins in southern Ghana  

NASA Astrophysics Data System (ADS)

Surface water resources play a crucial role in the domestic water delivery system in Ghana. In addition, sustainable food production is based on the quality and quantity of water resources available for irrigation purposes to supplement rain-fed agricultural activities in the country. The objective of this research was to determine the main controls on the hydrochemistry of surface water resources in the southern part of Ghana and assess the quality of water from these basins for irrigation activities in the area. R-mode factor and cluster analyses were applied to 625 data points from 6 river basins in southern Ghana after the data had been log transformed and standardized for homogeneity. This study finds that surface water chemistry in the south is controlled by the chemistry of silicate mineral weathering, chemistry of rainfall, fertilizers from agricultural activities in the area, as well as the weathering of carbonate minerals. A Gibb’s diagram plotted with total dissolved solids (TDS) on the vertical axis against (Na+ + K+)/(Ca2+ + K+ + Na+) on the horizontal axis indicates that rock weathering plays a significant role in the hydrochemistry. Activity diagrams for the CaO-Na2O-Al2O-SiO2-H2O and CaO-MgO-Al2O3-SiO2-H2O systems suggest that kaolinite is the most stable clay mineral phase in the system. In addition, an assessment of the irrigation quality of water from these basins suggests that the basins are largely low sodium—low to medium salinity basins, delivering water of acceptable quality for irrigation purposes.

Yidana, Sandow Mark

2009-04-01

313

Thin water films driven by air through surface roughness  

NASA Astrophysics Data System (ADS)

The interaction between thin films and roughness surfaces has been studied when the thin viscosity-dominated films are driven by the air shear stress in the context of a high Reynolds number boundary layer theory. A number of properties of this model are examined, such as transport and pooling of water in a roughness field, heat transfer of film/roughness combinations, and rivulet formation. For rivulet formation due to the instability of two-dimensional film fronts, a general formula for the largest unstable wavelength, the fastest temporal growth rate, and the neutral wavelength has been developed from the linear instability analysis. This formula is validated using experimental data for film fronts on flat surfaces which are driven by constant surface tension gradients. This formula is also validated using numerical simulations of film fronts moving through various roughened surfaces. To describe a water bead on a precursor film, a new disjoining pressure model is developed from a modified classical long-distance disjoining pressure model. This model satisfies the requirement that the disjoining pressure on the precursor film is larger than zero. Another advantage of this modified model is that an effective distance used in classical long-distance disjoining pressure models is avoided even when a water bead is on a dry surface. This model is validated using experimental data from aircraft icing tests.

Wang, Guoqing

314

Field Evaluation Of Arsenic Speciation In Sediments At The Ground Water/Surface Water Interface  

EPA Science Inventory

The speciation and mineralogy of sediments contaminated with arsenic at the ground water/surface water interface of the Ft. Devens Super Fund Site in Ft. Devens, MA were determined using X-ray absorption fine structure and X-ray diffraction spectroscopy. Speciation and mineralog...

315

Surface Water Data at Los Alamos National Laboratory: 1999 Water Year  

SciTech Connect

The principal investigators collected and computed surface water discharge data from 22 stream-gaging stations that cover most of Los Alamos National Laboratory with one at Bandelier National Monument. Also included are discharge data from three springs that flow into Canon de Valle and nine partial-record storm water stations.

D. A. Shaull; M. R. Alexander; R. P. Reynolds; C. T. McLean; R. P. Romero

2000-04-01

316

Surface Water Data at Los Alamos National Laboratory 2006 Water Year  

SciTech Connect

The principal investigators collected and computed surface water discharge data from 44 stream-gaging stations that cover most of Los Alamos National Laboratory and one at Bandelier National Monument. Also included are discharge data from three springs--two that flow into Canon de Valle and one that flows into Water Canyon--and peak flow data for 44 stations.

R.P. Romero, D. Ortiz, G. Kuyumjian

2007-08-01

317

Effects of Surface-Water Diversions on Habitat Availability for Native Macrofauna, Northeast Maui, Hawaii  

USGS Publications Warehouse

Effects of surface-water diversions on habitat availability for native stream fauna (fish, shrimp, and snails) are described for 21 streams in northeast Maui, Hawaii. Five streams (Waikamoi, Honomanu, Wailuanui, Kopiliula, and Hanawi Streams) were chosen as representative streams for intensive study. On each of the five streams, three representative reaches were selected: (1) immediately upstream of major surface-water diversions, (2) midway to the coast, and (3) near the coast. This study focused on five amphidromous native aquatic species (alamoo, nopili, nakea, opae, and hihiwai) that are abundant in the study area. The Physical Habitat Simulation (PHABSIM) System, which incorporates hydrology, stream morphology and microhabitat preferences to explore relations between streamflow and habitat availability, was used to simulate habitat/discharge relations for various species and life stages, and to provide quantitative habitat comparisons at different streamflows of interest. Hydrologic data, collected over a range of low-flow discharges, were used to calibrate hydraulic models of selected transects across the streams. The models were then used to predict water depth and velocity (expressed as a Froude number) over a range of discharges up to estimates of natural median streamflow. The biological importance of the stream hydraulic attributes was then assessed with the statistically derived suitability criteria for each native species and life stage that were developed as part of this study to produce a relation between discharge and habitat availability. The final output was expressed as a weighted habitat area of streambed for a representative stream reach. PHABSIM model results are presented to show the area of estimated usable bed habitat over a range of streamflows relative to natural conditions. In general, the models show a continuous decrease in habitat for all modeled species as streamflow is decreased from natural conditions. The PHABSIM modeling results from the intensively studied streams were normalized to develop relations between the relative amount of diversion from a stream and the resulting relative change in habitat in the stream. These relations can be used to estimate changes in habitat for diverted streams in the study area that were not intensively studied. The relations indicate that the addition of even a small amount of water to a dry stream has a significant effect on the amount of habitat available. Equations relating stream base-flow changes to habitat changes can be used to provide an estimate of the relative habitat change in the study area streams for which estimates of diverted and natural median base flow have been determined but for which detailed habitat models were not developed. Stream water temperatures, which could have an effect on stream ecology and taro cultivation, were measured in five streams in the study area. In general, the stream temperatures measured at any of the monitoring sites were not elevated enough, based on currently available information, to adversely effect the growth or mortality of native aquatic macrofauna or to cause wetland taro to be susceptible to fungi and associated rotting diseases.

Gingerich, Stephen B.; Wolff, Reuben H.

2005-01-01

318

Detection of Water Pollutant Using Surface-Polarity Controlled Sensor  

NASA Astrophysics Data System (ADS)

Aldehyde and carboxylic acid compounds are known as volatile substances with bad smell. It is also said to cause bad smell of tap water. In this study, we tried to detect and analyse aldehyde and carboxylic acid dissolved in water, using a surface-polarity controlled sensor. The sensor measures electrochemical impedance of the electrode surface whose electric potential is dynamically controlled. Adsorption and desorption of target chemicals cause changes in impedance which has constant phase element (CPE) characteristics. The impedance changes depending on the electrode potential are used as a chemical sensor output. As a result, we could detect and distinguish many kinds of aldehyde and carboxylic acids. Furthermore various water pollutant can be detected with high sensitivity. The results suggest that a simple and multi-purposed sensor can be constructed for environmental analysis using the proposed method.

Hayashi, Kenshi; Tanaka, Hiroki; Hayama, Kosuke; Izumi, Ryosuke; Toko, Kiyoshi

319

Water-mediated proton hopping on an iron oxide surface.  

PubMed

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

2012-05-18

320

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

2012-05-18

321

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

PubMed

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

2011-12-01

322

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

NASA Astrophysics Data System (ADS)

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 effect of wetland hydrology on water quality. In this study, the development of a general comprehensive wetland model Wetland Solute Transport Dynamics (WETSAND) that has both surface flow and solute transport components is presented. The model incorporates surface water/groundwater interactions and accounts for upstream contributions from urbanized areas. The effect of restored wetlands on storm water runoff is also investigated by routing the overland flow through the wetland area, collecting the runoff within the stream, and transporting it to the receiving water using diffusion wave routing techniques. The computed velocity profiles are subsequently used to obtain water quality concentration distributions in wetland areas. The water quality component solves the advection-dispersion equation for several nitrogen and phosphorus constituents, and it also incorporates the surface water/groundwater interactions by including the incoming/outgoing mass due to the groundwater recharge/discharge. In addition, output from the Storm Water Management Model (SWMM5) is incorporated into this conceptual wetland model to simulate the runoff quantity and quality flowing into a wetland area from upstream urban sources. Additionally, the model can simulate a water control structure using storage routing principles and known stage-discharge spillway relationships.

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

2007-04-01

323

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

2006-01-01

324

A Study on Water Surface Profiles of Rivers with Constriction  

NASA Astrophysics Data System (ADS)

Water surface profile of rivers with constrictions is precious in both classic hydraulics and river management practice. This study was conducted to clarify the essences of the water surface profiles. 3 cases of experiments and 1D numerical calculations with different discharges were made in the study and analysis solutions of the non-linear basic equation of surface profile in varied flow without considering friction were derived. The manning's number was kept in the same in each case by using crosspiece roughness. We found a new type of water surface profile of varied flow from the results of 1D numerical calculation and that of experiments and named it as Mc curve because of its mild condition with constriction segment. This kind of curves appears as a nature phenomenon ubiquitously. The process of water surface forming is dynamic and bore occurs at the upper side of constriction during increasing discharge before the surface profile formed. As a theoretical work, 3 analysis solutions were derived included 2 physical-meaning solutions in the study by using Man-Machine system. One of the derived physical-meaning solutions was confirmed that it is validity by comparing to the results of 1D numerical calculation and that of experiments. The solution represents a flow profile from under critical condition at the upper side to super critical condition at the down side of constriction segment. The other derived physical-meaning solution represents a flow profile from super critical condition at the upper side to under critical condition at the down side of constriction segment. These two kinds of flow profiles exist in the nature but no theoretical solution can express the phenomenon. We find the depth distribution only concerned with unit width discharge distribution and critical depth under a constant discharge from the derived solutions. Therefor, the profile can be gained simply and precisely by using the theoretical solutions instead of numerical calculation even in practice.

Qian, Chaochao; Yamada, Tadashi

2013-04-01

325

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

1992-10-01

326

Optimizing Nanopore Surface Properties for High-Efficiency Water Desalination  

NASA Astrophysics Data System (ADS)

As water resources worldwide become rapidly scarcer, it is becoming increasingly important to devise new techniques to obtain clean water from seawater. At present, water purification technologies are limited by costly energy requirements relative to the theoretical thermodynamic limit and by insufficient understanding of the physical processes underlying ion filtration and fluid transport at the molecular scale. New advances in computational materials science offer a promising way to deepen our understanding of these physical phenomena. In this presentation, we describe a new approach for high-efficiency water desalination based on surface-engineered porous materials. This approach is especially relevant for promising technologies such as nanofiltration and membrane distillation, which offers promising advantages over traditional desalination technologies using mesoporous membranes that are only permeable to pure water vapor. More accurate molecular modeling of mesoporous and nanoporous materials represents a key step towards efficient large-scale treatment of seawater. Results regarding the effect of pore properties (surface texture, morphology, density, tortuosity) on desired performance characteristics such as ion selectivity, maximal water flux and energy requirements will be presented.

Cohen-Tanugi, David; Grossman, Jeffrey

2011-03-01

327

A Liquid Water Model That Explains the Variation of Surface Tension of Water with Temperaure  

NASA Astrophysics Data System (ADS)

A model is presented that explains the variation of surface tension of liquid water with temperature. The presence of non H-bonding H (NHB H) atoms (defining surface of assumed clusters) together with H-bonding atoms, is considered in this treatment. A good agreement between the experimental and computed values suggests the validity of this model. The change in the number of NHB H atoms and density account for the variation of surface tension with temperature. Previously, the same model was applied to explain the anomalous variation of density of liquid water with temperature [A. Khan et.al.: Chem. Phys. Lett. 266 (1997) 473].

Khan, Arshad; Khan, M. Rezwan; Khan, M. Ferdouse; Khanam, Fahima

2001-03-01

328

Distribution patterns of polychlorinated biphenyl congeners in water, sediment and biota from Midway Atoll (North Pacific Ocean)  

Microsoft Academic Search

To increase our understanding of critical pathways of polychlorinated biphenyl (PCB) transfer from abiotic media into marine organisms, this study quantified 20 PCB congeners in surface water, sediment and tissues of marine biota (macrophytes, snails, urchins, bivalves, sea cucumbers, fishes) taken from Midway Atoll. PCBs 138, 153, 170, 180 and 187 were the most abundant congeners in all samples analysed.

Bruce Hope; Susan Scatolini; Eric Titus; Jeff Cotter

1997-01-01

329

Investigating surface water-well interaction using stable isotope ratios of water  

USGS Publications Warehouse

Because surface water can be a source of undesirable water quality in a drinking water well, an understanding of the amount of surface water and its travel time to the well is needed to assess a well's vulnerability. Stable isotope ratios of oxygen in river water at the City of La Crosse, Wisconsin, show peak-to-peak seasonal variation greater than 4??? in 2001 and 2002. This seasonal signal was identified in 7 of 13 city municipal wells, indicating that these 7 wells have appreciable surface water contributions and are potentially vulnerable to contaminants in the surface water. When looking at wells with more than 6 sampling events, a larger variation in ??18O compositions correlated with a larger fraction of surface water, suggesting that samples collected for oxygen isotopic composition over time may be useful for identifying the vulnerability to surface water influence even if a local meteoric water line is not available. A time series of ??18O from one of the municipal wells and from a piezometer located between the river and the municipal well showed that the travel time of flood water to the municipal well was approximately 2 months; non-flood arrival times were on the order of 9 months. Four independent methods were also used to assess time of travel. Three methods (groundwater temperature arrival times at the intermediate piezometer, virus-culture results, and particle tracking using a numerical groundwater-flow model) yielded flood and non-flood travel times of less than 1 year for this site. Age dating of one groundwater sample using 3H-3He methods estimated an age longer than 1 year, but was likely confounded by deviations from piston flow as noted by others. Chlorofluorocarbons and SF6 analyses were not useful at this site due to degradation and contamination, respectively. This work illustrates the utility of stable hydrogen and oxygen isotope ratios of water to determine the contribution and travel time of surface water in groundwater, and demonstrates the importance of using multiple methods to improve estimates for time of travel of 1 year or less. ?? 2004 Elsevier B.V. All rights reserved.

Hunt, R. J.; Coplen, T. B.; Haas, N. L.; Saad, D. A.; Borchardt, M. A.

2005-01-01

330

[Immunity in parasite-vector snails].  

PubMed

Aquatic snails play a key role in the transmission of parasites such as the human blood or liver flukes (Schistosomes and Fasciola sp.). During the last decade, particular efforts have been made by a small number of scientists to progress in our understanding of the molecular mechanisms underlying snail immune responses and/or host parasite interactions. Complementary approaches using the gastropod snail Biomphalaria glabrata, an intermediate host of Schistosoma mansoni, have yielded a number of unexpected results such as the existence of highly diversified pathogen-binding proteins (FREPs), or potential immune regulators similar to mammalian cytokines. Although molecular immune processes largely remain to be elucidated, accumulating data support the idea that snail innate immunity is much more complex than originally thought. PMID:19409193

Coustau, Christine

2009-04-01

331

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.

1998-06-01

332

Searching for liquid water in Europa by using surface observatories.  

PubMed

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

2002-01-01

333

Intrusion of Pacific surface water into the South China Sea.  

NASA Astrophysics Data System (ADS)

Velocity measurements made in the surface mixed layer with SVP surface drifters between 1986 and 2002 provide evidence of seasonal currents entering the South China Sea from the Pacific Ocean through the Strait of Luzon. The drifters cross the strait westward only between October and January, during the early northeast monsoon, with mean velocities in excess of 0.5 m/s (and instantaneous velocities as high as 1.65 m/s). West of the Luzon Strait, eddies of both sign are observed during some intrusion events. Only few of the crossing drifters appear to travel within the Kuroshio. On the Pacific side of the strait the surface currents measured by the drifters are larger than the Ekman currents that would be produced by a 10 m/s monsoon wind, suggesting that a seasonal current system to the west is responsible for the intrusion of the surface Pacific water into the South China Sea.

Centurioni, L.; Niiler, P.; Lee, D.

2003-04-01

334

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.

1989-05-01

335

Assembled monolayers of hydrophilic particles on water surfaces.  

PubMed

A facile and quick approach to prepare self-assembled monolayers of water-dispersible particles on the water surface is presented. Particle suspensions in alcohols were dropped on a water reservoir to form long-range ordered monolayers of various particles, including spherical solid particles, soft hydrogel particles, metal nanoparticles, quantum dots, nanowires, single-wall carbon nanotubes (SWCNTs), nanoplates, and nanosheets. A systematic study was conducted on the variables affecting the monolayer assembly: the solubility parameter of spreading solvents, particle concentration, zeta potential of the particles in the suspension, surface tension of the water phase, hardness of the particles, and addition of a salt in the suspension. This method requires no hydrophobic surface treatment of the particles, which is useful to exploit these monolayer films without changing the native properties of the particles. The study highlights a quick 2D colloidal assembly without cracks in the wafer scale as well as transparent conductive thin films made of SWCNTs and graphenes. PMID:21962177

Moon, Geon Dae; Lee, Tae Il; Kim, Bongsoo; Chae, GeeSung; Kim, Jinook; Kim, SungHee; Myoung, Jae-Min; Jeong, Unyong

2011-10-06

336

Assessment of the surface water quality in Northern Greece.  

PubMed

The application of different multivariate statistical approaches for the interpretation of a large and complex data matrix obtained during a monitoring program of surface waters in Northern Greece is presented in this study. The dataset consists of analytical results from a 3-yr survey conducted in the major river systems (Aliakmon, Axios, Gallikos, Loudias and Strymon) as well as streams, tributaries and ditches. Twenty-seven parameters have been monitored on 25 key sampling sites on monthly basis (total of 22,350 observations). The dataset was treated using cluster analysis (CA), principal component analysis and multiple regression analysis on principal components. CA showed four different groups of similarity between the sampling sites reflecting the different physicochemical characteristics and pollution levels of the studied water systems. Six latent factors were identified as responsible for the data structure explaining 90% of the total variance of the dataset and are conditionally named organic, nutrient, physicochemical, weathering, soil-leaching and toxic-anthropogenic factors. A multivariate receptor model was also applied for source apportionment estimating the contribution of identified sources to the concentration of the physicochemical parameters. This study presents the necessity and usefulness of multivariate statistical assessment of large and complex databases in order to get better information about the quality of surface water, the design of sampling and analytical protocols and the effective pollution control/management of the surface waters. PMID:12946893

Simeonov, V; Stratis, J A; Samara, C; Zachariadis, G; Voutsa, D; Anthemidis, A; Sofoniou, M; Kouimtzis, Th

2003-10-01

337

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.

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

1998-01-01

338

The role of Snail in prostate cancer.  

PubMed

Prostate cancer is the second most frequently diagnosed cancer and the sixth leading cause of death from cancer in men. Epithelial-mesenchymal transition (EMT) is a process by which cancer cells invade and migrate, and is characterized by loss of cell-cell adhesion molecules such as E-cadherin and increased expression of mesenchymal proteins such as vimentin; EMT is also associated with resistance to therapy. Snail, a master regulator of EMT, has been extensively studied and reported in cancers such as breast and colon; however, its role in prostate cancer is not as widely reported. The purpose of this review is to put together recent facts that summarize Snail signaling in human prostate cancer. Snail is overexpressed in prostate cancer and its expression and activity is controlled via phosphorylation and growth factor signaling. Snail is involved in its canonical role of inducing EMT in prostate cancer cells; however, it plays a role in non-canonical pathways that do not involve EMT such regulation of bone turnover and neuroendocrine differentiation. Thus, studies indicate that Snail signaling contributes to prostate cancer progression and metastasis and therapeutic targeting of Snail in prostate cancer holds promise in future. PMID:23076049

Smith, Bethany N; Odero-Marah, Valerie A

2012-09-01

339

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.

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

2011-01-01

340

A "First Principles" Potential Energy Surface for Liquid Water from VRT Spectroscopy of Water Clusters  

SciTech Connect

We present results of gas phase cluster and liquid water simulations from the recently determined VRT(ASP-W)III water dimer potential energy surface. VRT(ASP-W)III is shown to not only be a model of high ''spectroscopic'' accuracy for the water dimer, but also makes accurate predictions of vibrational ground-state properties for clusters up through the hexamer. Results of ambient liquid water simulations from VRT(ASP-W)III are compared to those from ab initio Molecular Dynamics, other potentials of ''spectroscopic'' accuracy, and to experiment. The results herein represent the first time that a ''spectroscopic'' potential surface is able to correctly model condensed phase properties of water.

Goldman, N; Leforestier, C; Saykally, R J

2004-05-25

341

Nonlinear scaling of surface water diffusion with bulk water viscosity of crowded solutions.  

PubMed

The translational hydration dynamics within 0.5-1.5 nm of the surface of a DPPC liposome, a model biomacromolecular surface, is analyzed by the recently developed Overhauser dynamic nuclear polarization (ODNP) technique. We find that dramatic changes to the bulk solvent cause only weak changes in the surface hydration dynamics. Specifically, both a >10-fold increase in bulk viscosity and the restriction of diffusion by confinement on a multiple nm length-scale change the local translational diffusion coefficient of the surface water surrounding the lipid bilayer by <2.5-fold. By contrast, previous ODNP studies have shown that changes to the biomacromolecular surface induced by folding, binding, or aggregation can cause local hydration dynamics to vary by factors of up to 30. We suggest that the surface topology and chemistry at the ?1.5 nm scale, rather than the characteristics of the solvent, nearly exclusively determine the macromolecule's surface hydration dynamics. PMID:23347324

Franck, John M; Scott, John A; Han, Songi

2013-03-11

342

Water-soluble sacrificial layers for surface micromachining.  

PubMed

This manuscript describes the use of water-soluble polymers for use as sacrificial layers in surface micromachining. Water-soluble polymers have two attractive characteristics for this application: 1) They can be deposited conveniently by spin-coating, and the solvent removed at a low temperature (95-150 degrees C), and 2) the resulting layer can be dissolved in water; no corrosive reagents or organic solvents are required. This technique is therefore compatible with a number of fragile materials, such as organic polymers, metal oxides and metals-materials that might be damaged during typical surface micromachining processes. The carboxylic acid groups of one polymer-poly(acrylic acid) (PAA)-can be transformed by reversible ion-exchange from water-soluble (Na+ counterion) to water-insoluble (Ca2+ counterion) forms. The use of PAA and dextran polymers as sacrificial materials is a useful technique for the fabrication of microstructures: Examples include metallic structures formed by the electrodeposition of nickel, and freestanding, polymeric structures formed by photolithography. PMID:17193516

Linder, Vincent; Gates, Byron D; Ryan, Declan; Parviz, Babak A; Whitesides, George M

2005-07-01

343

Measuring the true height of water films on surfaces.  

PubMed

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

2011-10-25

344

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.

,

1981-04-01

345

Reverse transcription PCR to detect enteroviruses in surface water.  

PubMed Central

We have developed a simple, fast, and efficient procedure to detect enteroviruses in water samples. Aliquots of water are subjected to two-step filtration, with the second filter containing a positively charged nylon membrane that holds back virus particles. Viruses thus adsorbed are directly lysed, and RNA is isolated by hybridization to specific oligonucleotides bound to magnetic beads. The solution used contains guanidine thiocyanate, which lyses virus particles, inactivates enzymes, e.g., RNases, allows mild hybridization conditions, and does not influence biotin-streptavidin interaction on magnetic beads. Detection and specific identification are accomplished by reverse transcription PCR of the highly conserved noncoding region at the 5' end of virus RNA combined with Southern hybridization. The system was tested with tap water artificially spiked with poliovirus vaccine and yielded a detection limit of 20 50% tissue culture infective doses per liter. We used the same procedure to investigate the water quality of surface water at public beaches by rivers and lakes. Of 40 samples tested, 7 were positive for enteroviruses. A comparison with enterobacterial contamination determined by PCR and classical microbiological methods in parallel showed that enteroviruses were found only in samples also positive for Escherichia coli. In conclusion, this procedure can easily be adapted to test large water samples and is simple enough to be used for routine determinations of water quality in terms of virus contamination.

Gilgen, M; Wegmuller, B; Burkhalter, P; Buhler, H P; Muller, U; Luthy, J; Candrian, U

1995-01-01

346

Water resources data Maryland, Delaware, and Washington, D.C.,water year 2005, Volume 1. Surface-water data  

USGS Publications Warehouse

Water resources data for the 2005 water year for Maryland, Delaware, and Washington, D.C. consist of records of stage, discharge, and water quality of streams; stage and contents of lakes and reservoirs. This volume (Volume 1. Surface-Water Data) contains records for water discharge at 145 gaging stations; stage and contents of 1 reservoir; stage only for 2 tidal gaging station; and water quality at 19 gaging stations. Also included are stage only for 11 tidal crest-stage partial-record stations. Additional water data were collected at various sites not involved in the systematic data-collection program and are published as miscellaneous measurements. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State, local, and Federal agencies in Maryland, Delaware, and Washington, D.C.

Saffer, Richard W.; Pentz, Robert H.; Tallman, Anthony J.

2006-01-01

347

Water resources data for Maryland, Delaware, and Washington, D.C, water year 2002, Volume 1. surface-water data  

USGS Publications Warehouse

Water resources data for the 2002 water year for Maryland, Delaware, and Washington, D.C. consist of records of stage, discharge, and water quality of streams; stage and contents of lakes and reservoirs. This volume (Volume 1. Surface-Water Data) contains records for water discharge at 137 gaging stations; stage and contents of 1 reservoir; and water quality at 28 gaging stations. Also included are stage and discharge for 3 crest-stage partial-record stations and stage only for 8 tidal crest-stage partialrecord stations. Additional water data were collected at various sites not involved in the systematic data-collection program and are published as miscellaneous measurements. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State, local, and Federal agencies in Maryland, Delaware, and Washington, D.C.

James, Robert W., Jr.; Saffer, Richard W.; Pentz, Robert H.; Tallman, Anthony J.

2003-01-01

348

Water resources data for Maryland, Delaware, and Washington, D.C, water year 2003, volume 1. surface-water data  

USGS Publications Warehouse

Water resources data for the 2003 water year for Maryland, Delaware, and Washington, D.C. consist of records of stage, discharge, and water quality of streams; stage and contents of lakes and reservoirs. This volume (Volume 1. Surface-Water Data) contains records for water discharge at 140 gaging stations; stage and contents of 1 reservoir; and water quality at 17 gaging stations. Also included are stage and discharge for 3 crest-stage partial-record stations and stage only for 10 tidal crest-stage partial-record stations. Additional water data were collected at various sites not involved in the systematic data-collection program and are published as miscellaneous measurements. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State, local, and Federal agencies in Maryland, Delaware, and Washington, D.C.

James, Robert W., Jr.; Saffer, Richard W.; Pentz, Robert H.; Tallman, Anthony J.

2003-01-01

349

Water resources data, Maryland, Delaware, and Washington, D.C., water year 2000, volume 1. surface-water data  

USGS Publications Warehouse

Water resources data for the 2000 water year for Maryland and Delaware consist of records of stage, discharge, and water quality of streams; stage and contents of lakes and reservoirs. This volume (Volume 1. Surface-Water Data) contains records for water discharge at 121 gaging stations; stage and contents of 1 reservoir; and water quality at 21 gaging stations. Also included are stage and discharge for 3 creststage partial-record stations, discharge only for 27 low-flow partial-record stations, and stage only for 5 tidal crest-stage partial-record stations. Additional water data were collected at various sites not involved in the systematic data-collection program and are published as miscellaneous measurements. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State, local, and Federal agencies in Maryland and Delaware.

James, Robert W., Jr.; Saffer, Richard W.; Tallman, Anthony J.

2001-01-01

350

Shallow Alluvial Aquifer Ground Water System and Surface Water/Ground Water Interaction, Boulder Creek, Boulder, Colorado  

NASA Astrophysics Data System (ADS)

Water chemistry in Boulder Creek, Colorado, shows significant variation as the Creek flows through the City of Boulder [Barber et al., 2006]. This variation is partially due to ground water inputs, which are not quantitatively understood. The purpose of this study is (1) to understand ground water movement in a shallow alluvial aquifer system and (2) to assess surface water/ground water interaction. The study area, encompassing an area of 1 mi2, is located at the Sawhill and Walden Ponds area in Boulder. This area was reclaimed by the City of Boulder and Boulder County after gravel mining operations ceased in the 1970's. Consequently, ground water has filled in the numerous gravel pits allowing riparian vegetation regrowth and replanting. An integrated approach is used to examine the shallow ground water and surface water of the study area through field measurements, water table mapping, graphical data analysis, and numerical modeling. Collected field data suggest that lateral heterogeneity exists throughout the unconsolidated sediment. Alluvial hydraulic conductivities range from 1 to 24 ft/day and flow rates range from 0.01 to 2 ft/day. Preliminary data analysis suggests that ground water movement parallels surface topography and does not noticeably vary with season. Recharge via infiltrating precipitation is dependent on evapotranspiration (ET) demands and is influenced by preferential flow paths. During the growing season when ET demand exceeds precipitation rates, there is little recharge; however recharge occurs during cooler months when ET demand is insignificant. Preliminary data suggest that the Boulder Creek is gaining ground water as it traverses the study area. Stream flow influences the water table for distances up to 400 feet. The influence of stream flow is reflected in the zones relatively low total dissolved solids concentration. A modeling study is being conducted to synthesize aquifer test data, ground water levels, and stream flow data. The model will quantitatively assess the interaction between surface water and ground water, particularly the amount of exchange between the creek and ground water and to what extent these systems influence each other. Model sensitivity study will help identify important system parameters. A comprehensive model of the study area will serve as a tool for efficiently allocating water throughout the study area (from Boulder Creek). Water allocation is needed to prevent the eutrophication of the ponds, improve fishery management, and efficiently meet the water rights obligations in the watershed.

Babcock, K. P.; Ge, S.; Crifasi, R. R.

2006-12-01

351

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.

D. VAN DER KOOIJ

1977-01-01

352

An Evaluation of the Interactions Between Freshwater Pulmonate Snail Hosts of Human Schistosomes and Macrophytes  

Microsoft Academic Search

An account is given of a laboratory investigation designed to evaluate the extent to which the freshwater pulmonate snail Biomphalaria glabrata (Say) can utilize various species of aquatic plants, mainly macrophytes, when presented in the following forms over different time scales: (i) normal plants; (ii) dried plant material; (iii) homogenized plant material in calcium alginate matrices; (iv) water-soluble filtrates of

J. D. Thomas

1987-01-01

353

Aspects of ecology and conservation of sympatric, prosobranch snails in a large river  

Microsoft Academic Search

We examined factors influencing distribution of prosobranch snails with field surveys, lab substrate-choice and movement experiments, and outdoor artificial stream experiments manipulating current, substrate and temperature. Restriction of Lithasia obovata to shallow, isolated rock patches and the more continuous distribution of Pleurocera canaliculatum on diverse substrates (shallow to deep water) seem related to food availability, predator vulnerability, wave resistance and

Kimberly S. Greenwood; James H. Thorp

2001-01-01

354

MicroEvolution in a Polymorphic Prosobranch Snail (Clithon oualaniensis (Lesson))  

Microsoft Academic Search

The polymorphic brackish-water snail Clithon oualaniensis is widely spread in the Indo-Pacific Region. It has been studied in India and Ceylon, round the Malay Peninsula, and in Hong Kong; a smaller material from NE Queensland, Australia, has also been examined. The total is not far short of 100000 individuals. There are great geographical differences in gene frequencies. For instance, 'purple

H. Gruneberg

1978-01-01

355

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)

2009-07-15

356

Factors governing dry deposition of gases to surface water  

SciTech Connect

Rates of dry deposition of gases to surface water vary by orders of magnitude depending on the concentration of the gas in the surface water and on the solubility and aqueous-phase reaction kinetics of the depositing gas. For non-reactive gases the key property is the Henry's law solubility. For reactive gases the deposition flux can be quantitatively related to the chemical reaction rate for known mass-transport parameters and solubility and kinetic coefficients of the depositing gas. Interfacial resistance to mass transport does not seem to be significant based upon recent laboratory measurements of mass-accommodation coefficients. Readily applicable criteria to identify controlling processes are presented and applied to examination of SO{sub 2} (gas-phase mass-transport control), CO{sub 2} (liquid-phase mass-transport control), and formaldehyde and O{sub 3} (liquid-phase chemical-kinetic control) as examples. 23 refs., 2 figs., 1 tab.

Schwartz, S.E.

1991-04-01

357

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

2013-08-01

358

Behavioural responses of the snail Lymnaea acuminata to carbohydrates in snail-attractant pellets  

NASA Astrophysics Data System (ADS)

Snail control is one of the most important tools in the campaign to reduce the incidence of fascioliasis. In order to attain this objective, the method of bait formulation in order to contain an attractant and a molluscicide is an expedient approach to lure the target snail population to the molluscicide. This study identifies certain carbohydrates, namely sucrose, maltose, glucose, fructose and starch, for preparing such baits. These were tested on Lymnaea acuminata, an intermediate host of the digenean trematodes Fasciola hepatica and Fasciola gigantica. The behavioural responses of snails to these carbohydrates were examined. Significant variations in behavioural responses were observed in the snail even when the five carbohydrates were used in low concentrations in snail-attractant pellets. Starch emerged as the strongest attractant for Lymnaea acuminata, followed by maltose.

Tiwari, Farindra; Singh, D. K.

359

Water resources data, North Carolina, water year 2003. Volume 1A: Surface-water records  

USGS Publications Warehouse

Water-resources data for the 2003 water year for North Carolina consist of records of stage, discharge, water quality for streams; stage and contents for lakes and reservoirs; precipitation; and ground-water levels and water quality of ground water. Volume 1 contains discharge records for 213 gaging stations; stage for 61 gaging stations; and continuous precipitation at 118 sites. Volume 2 contains ground-water-level data from 143 observation wells and ground-water-quality data from 72 wells. The collection of water-resources data in North Carolina is a part of the National Water-Data System operated by the U.S. Geological Survey in cooperation with State, municipal, and Federal agencies.

Ragland, B. C.; Walters, D. A.; Cartano, G. D.; Taylor, J. E.

2004-01-01

360

Simulating piecewise-linear surface water and ground water interactions with MODFLOW.  

PubMed

The standard MODFLOW packages offer limited capabilities to model piecewise-linear boundary conditions to describe ground water-surface water interaction. Specifically, MODFLOW is incapable of representing a Cauchy-type boundary with different resistances for discharge or recharge conditions. Such a more sophisticated Cauchy boundary condition is needed to properly represent surface waters alternatively losing water through the bottom (high resistance) or gaining water mostly near the water surface (low resistance). One solution would be to create a new package for MODFLOW to accomplish this. However, it is also possible to combine multiple instances of standard packages in a single cell to the same effect. In this specific example, the general head boundary package is combined with the drain package to arrive at the desired piecewise-linear behavior. In doing so, the standard USGS MODFLOW version can be used without any modifications at the expense of a minor increase in preprocessing and postprocessing and computational effort. The extra preprocessing for creating the input and extra postprocessing to determine the water balance in terms of the physical entities from the MODFLOW cell fluxes per package can be taken care of by a user interface. PMID:19473274

Zaadnoordijk, Willem Jan

2009-05-18

361

Atrazine removal by ozonation processes in surface waters  

Microsoft Academic Search

Atrazine (6?chloro?N?ethyl?N'?isopropyl?1,3,5?triazinedyl?2,4?diamine) was treated with ozone alone and in combination with hydrogen peroxide or UV radiation in three surface waters. Experiments were carried out in two bubble reactors operated continously. Variables investigated were the ozone partial pressure, temperature, pH, mass flow ratio of oxidants fed: hydrogen peroxide and ozone and the type of oxidation including UV radiation alone. Residence time

Fernando J. Beltrán; Javier Rivas; Benito Acedo

1999-01-01

362

Modelling the effects of surface water flood pulses on groundwater  

Microsoft Academic Search

Flood pulses in wetlands steer ecosystem development directly through surface water processes and\\u000aindirectly through the effects of the flood pulse on groundwater. Direct effects on ecosystems are exerted by\\u000ae.g. inundation and deposition of sediments containing nutrients. Indirect effects include the rise of\\u000agroundwater levels and accompanying soil moisture contents following the flood pulse, and the transport of\\u000asolutes

P. P. Schot; M. J. Wassen

2010-01-01

363

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

2004-01-01

364

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

1995-01-01

365

Effective Modification of Particle Surface Properties Using Ultrasonic Water Mist  

Microsoft Academic Search

The goal of the present study was to design a new technique to modify particle surface properties and, through that, to improve\\u000a flowability of poorly flowing drug thiamine hydrochloride and pharmaceutical sugar lactose monohydrate of two different grades.\\u000a The powdered particles were supplied by a vibratory feeder and exposed to an instantaneous effect of water mist generated\\u000a from an ultrasound

Natalja Genina; Heikki Räikkönen; Jyrki Heinämäki; Osmo Antikainen; Simo Siiriä; Peep Veski; Jouko Yliruusi

2009-01-01

366

Macro-invertebrate decline in surface water polluted with imidacloprid.  

PubMed

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

2013-05-01

367

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.

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

2013-01-01

368

DEVELOPMENT OF GIARDIA C.T VALUES FOR THE SURFACE WATER TREATMENT RULE  

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...

369

Development of Giardia C · t values for the surface water treatment rule  

Microsoft Academic Search

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. In the Guidance Manual to the SWTR, the EPA recommends C·t values (product of disinfection concentration in milligrams per liter and

Robert M. Clark; Stig Regli

1993-01-01

370

Water oxidation at hematite photoelectrodes: the role of surface states.  

PubMed

Hematite (?-Fe(2)O(3)) constitutes one of the most promising semiconductor materials for the conversion of sunlight into chemical fuels by water splitting. Its inherent drawbacks related to the long penetration depth of light and poor charge carrier conductivity are being progressively overcome by employing nanostructuring strategies and improved catalysts. However, the physical-chemical mechanisms responsible for the photoelectrochemical performance of this material (J(V) response) are still poorly understood. In the present study we prepared thin film hematite electrodes by atomic layer deposition to study the photoelectrochemical properties of this material under water-splitting conditions. We employed impedance spectroscopy to determine the main steps involved in photocurrent production at different conditions of voltage, light intensity, and electrolyte pH. A general physical model is proposed, which includes the existence of a surface state at the semiconductor/liquid interface where holes accumulate. The strong correlation between the charging of this state with the charge transfer resistance and the photocurrent onset provides new evidence of the accumulation of holes in surface states at the semiconductor/electrolyte interface, which are responsible for water oxidation. The charging of this surface state under illumination is also related to the shift of the measured flat-band potential. These findings demonstrate the utility of impedance spectroscopy in investigations of hematite electrodes to provide key parameters of photoelectrodes with a relatively simple measurement. PMID:22303953

Klahr, Benjamin; Gimenez, Sixto; Fabregat-Santiago, Francisco; Hamann, Thomas; Bisquert, Juan

2012-02-23

371

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

PubMed

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

2009-09-01

372

Probing the hydration water diffusion of macromolecular surfaces and interfaces  

NASA Astrophysics Data System (ADS)

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 1H NMR signals of hydration water around a spin label that is attached to a molecular site of interest. The selective 1H NMR amplification within molecular length scales of a spin label is achieved by utilizing short-distance range (~r-3) magnetic dipolar interactions between the 1H spin of water and the electron spin of a nitroxide radical-based label. Key features include the fact that only minute quantities (<10 ?l) and dilute (>=100 ?M) sample concentrations are needed. There is no size limit on the macromolecule or molecular assembly to be analyzed. Hydration water with translational correlation times between 10 and 800 ps is measured within ~10 Å distance of the spin label, encompassing the typical thickness of a hydration layer with three water molecules across. The hydration water moving within this time scale has significant implications, as this is what is modulated whenever macromolecules or molecular assemblies undergo interactions, binding or conformational changes. We demonstrate, with the examples of polymer complexation, protein aggregation and lipid-polymer interaction, that the measurements of interfacial hydration dynamics can sensitively and site specifically probe macromolecular interactions.

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

2011-01-01

373

Input dynamics of pesticide transformation products into surface water  

NASA Astrophysics Data System (ADS)

Some pesticide transformation products have been observed to occur in higher concentrations and more frequently than the parent active pesticide in surface water and groundwater. These products are often more mobile and sometimes more stable than the parent pesticide. If they also represent the major product into which the parent substance is transformed, these transformation products may dominate observed pesticide occurrences in surface water and groundwater. Their potential contribution to the overall risk to the aquatic environment caused by the use of the parent pesticide should therefore not be neglected in chemical risk and water quality assessments. The same is true for transformation products of other compound classes that might reach the soil environment, such as veterinary pharmaceuticals. However, the fate and input pathways of transformation products of soil-applied chemicals into surface water are not yet well understood, which largely prevents their appropriate inclusion into chemical risk and water quality assessments. Here, we studied whether prioritization methods based on available environmental fate data from pesticide registration dossiers in combination with basic fate models could help identify transformation products which can be found in relevant concentrations in surface and groundwater and which should therefore be included into monitoring programs. A three-box steady state model containing air, soil, and surface water compartments was used to predict relative inputs of pesticide transformation products into surface waters based on their physico-chemical and environmental fate properties. The model predictions were compared to monitoring data from a small Swiss river located in an intensely agricultural catchment (90 km2) which was flow-proportionally sampled from May to October 2008 and screened for 74 pesticides as well as 50 corresponding transformation products. Sampling mainly occurred during high discharge, but additional samples during baseflow conditions were also taken. The analytical measurements included solid phase extraction, liquid chromatography and high resolution mass spectrometry (SPE-LC-HR-MS/MS). Quantification was achieved using reference standards and internal standards. Besides the well-known transformation products of triazine and chloroacetanilide herbicides, transformation products of other compound classes such as azoxystrobin acid (from azoxystrobin, strobilurin fungicide), chloridazon-desphenyl and chloridazon-methyl-desphenyl (from chloridazon, pyridazinone herbicide), and metamitron-desamino (from metamitron, triazinone herbicide) were analyzed in surface water. For a selection of widely used pesticides in the catchment, modelled ratios of transformation product versus parent pesticide concentrations were compared to the measured concentration ratios in the river for the application period and for two 2-month periods following application. Concentration ratios agreed within a factor of 10 for all pairs of parent pesticides and transformation products, and for all seasons, with a single exception. The ratio of chloridazon-desphenyl to chloridazon was under-predicted by a factor of approximately 20. The data revealed that chloridazon-desphenyl was also found in elevated concentrations in all baseflow samples, indicating its presence in the groundwater component of the catchment. The same was true for other transformation products (e.g., metamitron-desamino, chloridazon-methly-desphenyl, metolachlor-ESA), but to a lesser degree. Based on baseflow separation of the hydrograph, the concentration ratio estimation model was supplemented with an additional baseflow component. The concentrations in the baseflow component were estimated with a simple leaching relationship that was compared against measured baseflow concentrations and groundwater findings in Switzerland. The final model yielded good agreement for all compounds and is therefore deemed suitable for prioritization of transformation products with a relevant exposure potential. It also clearly indicated the contr

Kern, Susanne; Singer, Heinz; Hollender, Juliane; Schwarzenbach, René P.; Fenner, Kathrin

2010-05-01

374

Hydration structure of water confined between mica surfaces.  

PubMed

We report further molecular dynamics simulations on the structure of bound hydration layers under extreme confinement between mica surfaces. We find that the liquid phase of water is maintained down to 2 monolayer (ML) thick, whereas the structure of the K(+) ion hydration shell is close to the bulk structure even under D = 0.92 nm confinement. Unexpectedly, the density of confined water remains approximately the bulk value or less, whereas the diffusion of water molecules decreases dramatically. Further increase in confinement leads to a transition to a bilayer ice, whose density is much less than that of ice Ih due to the formation of a specific hydrogen-bonding network. PMID:16497074

Leng, Yongsheng; Cummings, Peter T

2006-02-21

375

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.

2011-12-01

376

The Martian surface radiation environment - Influence of higher atmospheric pressure and surface or sub-surface water  

NASA Astrophysics Data System (ADS)

The Noachian epoch (~4.5 - 3.5 billion years ago) is a promising era for a possible emergence of life on Mars. The presence of runoff channels in areas formed during the Noachian suggests that liquid water existed at least sporadically during that time, with liquid water being regarded as a prerequisite for life. To have sustained liquid water, the atmospheric pressure on Noachian Mars must have been significantly higher than in the present. When considering the possibility of life on Noachian Mars, one conceivable restriction is given by the ionizing radiation environment. Using PLANETOCOSMICS- and GEANT4-simulation codes, we calculate the radiation environment on the Martian surface and the resulting radiation exposure for different atmospheric conditions. Here, we present absorbed dose rates resulting from galactic-cosmic-proton and alpha-particle-induced radiation environments, as well as changes of these rates caused by an increase of atmospheric pressure. Furthermore, we analyze which influence the presence of liquid surface water or sub-surface water-ice would have on the radiation environment under these different atmospheric conditions.

Ehresmann, B.; Böhm, E.; Kohler, J.; Martin, C.; Wimmer-Schweingruber, R. F.; Reitz, G.; Hassler, D. M.; Zeitlin, C. J.

2011-12-01

377

Effects of Temperature on Growth and Reproduction of Aquatic Snails.  

National Technical Information Service (NTIS)

The effects of temperature on the following freshwater snails were studied: Lymnaea stagnalis, L. emarginata, Helisoma trivolvis, H. anceps, H. campanulatum and Physa gyrina -- all pulmonate 'pond' snails; one gill-breathing operculate (Amnicola limosa); ...

H. van der Schalie E. G. Berry D. I. Mount

1973-01-01

378

Organochlorine and organophosphorous pesticide residues in ground water and surface waters of Kanpur, Uttar Pradesh, India  

Microsoft Academic Search

A survey undertaken in Kanpur, northern India, has shown the presence of high concentrations of both organochlorine and organophosphorous pesticides in the surface and ground water samples. Liquid–liquid extraction followed by GC-ECD was used for the determination of these compounds. Among the various pesticides analyzed, high concentrations of ?-HCH (0.259 ?g\\/l) and malathion (2.618 ?g\\/l) were detected in the surface

Nalini Sankararamakrishnan; Ajit Kumar Sharma; Rashmi Sanghi

2005-01-01

379

Water resources data, North Carolina, water year 2002. Volume 1B: Surface-water records  

USGS Publications Warehouse

Water-resources data for the 2002 water year for North Carolina consist of records of stage, discharge, water quality for streams; stage and contents for lakes and reservoirs; precipitation; and ground-water levels and water quality of ground water. Volume 1 contains discharge records for 211 gaging stations; stage and contents for 62 lakes and reservoirs; stage for 20 gaging stations; water quality for 52 gaging stations and 7 miscellaneous sites, and continuous water quality for 30 sites; and continuous precipitation at 109 sites. Volume 2 contains ground-water-level data from 143 observation wells and ground-water-quality data from 72 wells. Additional water data were collected at 85 sites not involved in the systematic data-collection program, and are published as miscellaneous measurements in Volume 1. The collection of water-resources data in North Carolina is a part of the National Water-Data System operated by the U.S. Geological Survey in cooperation with State, municipal, and Federal agencies.

Ragland, B. C.; Barker, R. G.; Robinson, J. B.

2003-01-01

380

Organochlorine and organophosphorous pesticide residues in ground water and surface waters of Kanpur, Uttar Pradesh, India.  

PubMed

A survey undertaken in Kanpur, northern India, has shown the presence of high concentrations of both organochlorine and organophosphorous pesticides in the surface and ground water samples. Liquid-liquid extraction followed by GC-ECD was used for the determination of these compounds. Among the various pesticides analyzed, high concentrations of gamma-HCH (0.259 microg/l) and malathion (2.618 microg/l) were detected in the surface water samples collected from the River Ganges in Kanpur. In the ground water samples collected from the various hand pumps located in agricultural and industrial areas, apart from gamma-HCH and malathion, dieldrin was also detected. The maximum concentration values of gamma-HCH, malathion and dieldrin were 0.900, 29.835 and 16.227 microg/l, respectively. Especially, the concentration of malathion was found to be much higher than the EC water quality standards in the ground water samples from industrial area posing a high risk to the common people. Pesticides like DDE, DDT, aldrin, ethion, methyl parathion and endosulfan were not detected in both the surface and ground water samples. PMID:15607785

Sankararamakrishnan, Nalini; Kumar Sharma, Ajit; Sanghi, Rashmi

2005-01-01

381

Evaluation of NDWI as a Universal Index to Map Global Surface Water  

Microsoft Academic Search

A systematic assessment of surface water extent and variation is critical for us to understand the global water cycle. Satellite remote sensing provides a feasible tool to surface water mapping and monitoring. It is desirable to develop universal indices for water remote sensing at regional and global scales. Normalized difference water index (NDWI) is one of the indices being widely

J. Li; Y. Sheng

2008-01-01

382

Water resources data, North Carolina, water year 2001. Volume 1A: Surface-water records  

USGS Publications Warehouse

Water-resources data for the 2001 water year for North Carolina consist of records of stage, discharge, water-quality for streams; stage and contents for lakes and reservoirs; precipitation; and ground water levels and water-quality of ground-water. Volume 1 contains discharge records for 209 gaging stations; stage and contents for 62 lakes and reservoirs; stage for 52 gaging stations; water quality for 101 gaging stations and 91 miscellaneous sites; continuous daily tide stage at 4 sites; and continuous precipitation at 98 sites. Volume 2 contains ground-water-level data from 136 observation wells and ground-water-quality data from 68 wells. Additional water data were collected at 84 sites not involved in the systematic data-collection program, and are published as miscellaneous measurements in Volume 1. The collection of water-resources data in North Carolina is a part of the National Water-Data System operated by the U.S. Geological Survey in cooperation with State, municipal, and Federal agencies.

Ragland, B. C.; Walters, D. A.; Cartano, G. D.; Taylor, J. E.

2002-01-01

383

Incorporating groundwater-surface water interaction into river management models.  

PubMed

Accurate representation of groundwater-surface water interactions is critical to modeling low river flows in the semi-arid southwestern United States. Although a number of groundwater-surface water models exist, they are seldom integrated with river operation/management models. A link between the object-oriented river and reservoir operations model, RiverWare, and the groundwater model, MODFLOW, was developed to incorporate groundwater-surface water interaction processes, such as river seepage/gains, riparian evapotranspiration, and irrigation return flows, into a rule-based water allocations model. An explicit approach is used in which the two models run in tandem, exchanging data once in each computational time step. Because the MODFLOW grid is typically at a finer resolution than RiverWare objects, the linked model employs spatial interpolation and summation for compatible communication of exchanged variables. The performance of the linked model is illustrated through two applications in the Middle Rio Grande Basin in New Mexico where overappropriation impacts endangered species habitats. In one application, the linked model results are compared with historical data; the other illustrates use of the linked model for determining management strategies needed to attain an in-stream flow target. The flows predicted by the linked model at gauge locations are reasonably accurate except during a few very low flow periods when discrepancies may be attributable to stream gaging uncertainties or inaccurate documentation of diversions. The linked model accounted for complex diversions, releases, groundwater pumpage, irrigation return flows, and seepage between the groundwater system and canals/drains to achieve a schedule of releases that satisfied the in-stream target flow. PMID:20412319

Valerio, Allison; Rajaram, Harihar; Zagona, Edith

2010-04-15

384

The genotoxic hazards of domestic wastes in surface waters.  

PubMed

Despite the noteworthy genotoxic potency of many industrial wastewaters, the genotoxic hazard posed to the downstream ecosystem and its associated biota will be determined by genotoxic loading. Municipal wastewaters, although ranking low in potency, can achieve loading values that are several orders of magnitude greater than those of most industries. Although these wastewaters are generally mixtures of wastes from several different sources, the volumetric proportion of the daily discharge that is of industrial origin rarely exceeds 30%. Genotoxicity calculations for the Montreal Urban Community (MUC) municipal wastewater treatment facility indicate that over 90% of the genotoxic loading (31.1 kg benzo(a)pyrene equivalents per day) is nonindustrial in origin. Moreover, a mass balance of surface water genotoxicity for St. Lawrence river at Montreal indicates that over 85% of the total contributions from the Montreal region are nonindustrial in origin. Additional calculations for the Great Lakes, and other rivers throughout the world, provide further support of a strong relationship between surface water genotoxicity and population. Despite some information about physical/chemical properties, the identity of the putative genotoxins in municipal wastewaters and surface waters remains a mystery. Likely candidates include potent genotoxins, such as N-nitroso compounds and aromatic amines, known to be present in human sanitary wastes, as well as genotoxic PAHs known to be present in many municipal wastewaters. Calculations based on literature data indicate that human sanitary wastes may be able to account for a substantial fraction (4-70%) of the nonindustrial loading from municipal wastewaters. Similar calculations suggest that pyrogenic PAHs that enter municipal wastewaters via surface runoff can only account for a small fraction (<5%) of the genotoxic loading values discussed. PMID:9630643

White, P A; Rasmussen, J B

1998-06-01

385

Dynamic factor analysis of surface water management impacts on soil and bedrock water contents in Southern Florida Lowlands  

NASA Astrophysics Data System (ADS)

Canal stage fluctuations significantly affect temporal change in soil water content. Net recharge significantly affects soil water content near ground surface. Effect of water table evaporation on soil water content variation is nonsignificant. Proposed raises in C111 stage are predicted to result in negligible changes in soil water at low elevation sites.

Kisekka, I.; Migliaccio, K. W.; Muñoz-Carpena, R.; Schaffer, B.; Li, Y. C.

2013-04-01

386

Variations of surface water extent and water storage in large river basins: A comparison of different global data sources  

NASA Astrophysics Data System (ADS)

For the period 2003-2004 and for six large river basins, the present study compares monthly time series of multi-satellite-derived surface water extent with other independent global data sets related to land water dynamics, such as water mass variations monitored by GRACE, simulated surface and total water storage from WGHM, water levels from altimetry, and GPCP precipitation estimates. In general, the datasets show a strong agreement with each other at seasonal timescale. In particular, over the Amazon and the Ganges basins, analysis of seasonal phase differences and hysteresis behavior between surface water extent, water level and storage reveal the complex relations between water extent and storage variations and the different effects of water transport processes within large river basins. The results highlight the value of combining multi-satellite techniques for retrieving surface water storage dynamics.

Papa, F.; Güntner, A.; Frappart, F.; Prigent, C.; Rossow, W. B.

2008-06-01

387

Water Resources Data, New Jersey, Water Year 2002, Volume 1. Surface-Water Data  

USGS Publications Warehouse

Water-resources data for the 2002 Water Year for New Jersey are presented in three volumes, and consists of records of stage, discharge, and water quality of streams; stage and contents of lakes and reservoirs; and water levels and water quality of ground water. Volume 1 contains discharge records for 93 gaging stations; tide summaries at 31 gaging stations; and stage and contents at 39 lakes and reservoirs. Also included are stage and discharge for 104 crest-stage partial-record stations and stage-only at 31 tidal crest-stage gages. Locations of these sites are shown in figures 8-11. Additional water data were collected at various sites that are not part of the systematic data-collection program. Discharge measurements were made at 201 low-flow partial-record stations and 121 miscellaneous sites.

Reed, T. J.; White, B. T.; Centinaro, G. L.; Dudek, J. F.; Spehar, A. B.; Protz, A. R.; Shvanda, J. C.; Watson, A. F.; Holzer, G. K.

2003-01-01

388

Eosinophilic meningitis risk associated with raw Ampullarium canaliculatus snails consumption  

Microsoft Academic Search

In Taiwan, Angiostrongylus cantonensis infection has been reported in foreign laborers who had consumed raw Ampullarium canaliculatus snails. This study analyzed three foreign laborers who had contracted enzyme-linked immunosorbent assay-confirmed A cantonensis infection while working in Taiwan. All three workers had consumed either roasted snails or raw snails flavored with seasoning while drinking wine. This study investigated possible risk factors

Jiun-Jye Wang; Li-Yu Chung; Rong-Jyh Lin; June-Der Lee; Chaio-Wen Lin; Chuan-Min Yen

2011-01-01

389

Extinction or survival: partulid tree snails in American Samoa?  

Microsoft Academic Search

Four partulid tree snail species are known from American Samoa. In 1998, we surveyed the recently established National Park (units on three islands: Tutuila, Tau, Ofu) and neighboring areas for partulids. On Tutuila, Samoana abbreviata, previously considered probably extinct, was extremely rare (15 snails seen); Samoana conicawas more common (288 snails) but still rare; Eua zebrina was the most common

ROBERT H. COWIE; ROBERT P. COOK

2001-01-01

390

Larval trematodes: double infections in common mud-flat snail.  

PubMed

Larvae of the trematode Zoogonus lasius are involved in most double infections of Nassarius obsoleta. The two most common trematode parasites of this snail do not occur together in double infections. Double infections were found in 14 of 340 infected snails in a total sample of 5025 snails. PMID:5770621

Vernberg, W B; Vernberg, F J; Beckerdite, F W

1969-06-13

391

X-Ray Spectroscopy of the Liquid Water Surface  

NASA Astrophysics Data System (ADS)

We have developed a new experiment for probing molecular details of liquid-vapor interfaces of volatile substances and their solutions under equilibrium conditions. Electronic and geometric structures of interfacial molecules are probed by EXAFS and NEXAFS methods in the soft X-ray region, using the Advanced Light Source, Berkeley, CA. Liquids are introduced into a high vacuum environment through the use of liquid microjets, which have been characterized independently by Raman spectroscopy. Detection of ions and electrons produced by the Auger avalanche probe the bulk and surface regions of the microjet, respectively, as a result of their different escape depths. Our first efforts involved a comparative study of the interfaces of water and methanol, wherein we detailed the first observation of surface relaxation for a liquid. Analysis of EXAFS data yielded a 6distance at the water interface, whereas a 5was found for methanol. NEXAFS measurements, interpreted in terms of density functional theory simulations, indicate a large population of interfacial water molecules having two free OH bonds ("acceptor only molecules"). This complements the "single donor" species identified in sum frequency generation experiments. These results are supported by recent theoretical calculations. For methanol and other simple alcohols, the data indicate that free alkyl groups extend into the vapor part of the interface. Preliminary results for aqueous solutions, as well as for other pure liquids, have been obtained and are presently under analysis. REFERENCES 1. K.R. Wilson, R.D. Schaller, B.S. Rude, T. Catalano, D.T. Co, J.D. Bozek, and R.J. Saykally, "Surface relaxation in liquid water and methanol studied by X-ray absorption spectroscopy," J. Chem. Phys 117,7738(2002). 2. K.R. Wilson, M. Cavalleri, B.S. Rude, R.D. Schaller, A. Nilsson, L.G.M. Pettersson, N. Goldman, T. Catalano, J.D. Bozek, and R.J. Saykally, "Characterization of hydrogen bond acceptor molecules at the water surface using near-edge x-ray absorption fine-structure spectroscopy and density functional theory," J. Phys.: Condens. Matter 14, L221-L226 (2002).

Saykally, Richard

2004-03-01

392

Modeling surface water-groundwater interaction with MODFLOW: some considerations.  

PubMed

The accuracy with which MODFLOW simulates surface water-groundwater interaction is examined for connected and disconnected losing streams. We compare the effect of different vertical and horizontal discretization within MODFLOW and also compare MODFLOW simulations with those produced by HydroGeoSphere. HydroGeoSphere is able to simulate both saturated and unsaturated flow, as well as surface water, groundwater and the full coupling between them in a physical way, and so is used as a reference code to quantify the influence of some of the simplifying assumptions of MODFLOW. In particular, we show that (1) the inability to simulate negative pressures beneath disconnected streams in MODFLOW results in an underestimation of the infiltration flux; (2) a river in MODFLOW is either fully connected or fully disconnected, while in reality transitional stages between the two flow regimes exist; (3) limitations in the horizontal discretization of the river can cause a mismatch between river width and cell width, resulting in an error in the water table position under the river; and (4) because coarse vertical discretization of the aquifer is often used to avoid the drying out of cells, this may result in an error in simulating the height of the groundwater mound. Conditions under which these errors are significant are investigated. PMID:19891721

Brunner, Philip; Simmons, Craig T; Cook, Peter G; Therrien, René

2009-11-05

393

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.

1991-05-01

394

Reliability of Cyclic Surface and Groundwater Storage Systems for Water Supply: A Preliminary Assessment.  

National Technical Information Service (NTIS)

A simplified cyclic water resources system involving a single surface reservoir and an adjacent storage aquifer was modeled and evaluated both physically and economically. If fixed annual water demand cannot be met by annual inflows to the surface reservo...

D. P. Lettenmaier S. J. Burges

1979-01-01

395

Physically-based modeling of water exchange between surface water and groundwater : Conceptual and applied simulations (Invited)  

Microsoft Academic Search

There is an increasing need to characterize and manage groundwater and surface water as an integrated system, for example to address the sustainability of water resources for humans and ecosystems. Recent advances in the integrated simulation of surface and subsurface fluid flow and solute transport have allowed to investigate in greater detail water cycling at the watershed scale, in particular

R. Therrien; P. Brunner; C. Simmons; P. G. Cook

2009-01-01

396

Thin-films flows over microtextured surfaces: Polygonal water sheets  

NASA Astrophysics Data System (ADS)

We study water sheets and bells resulting from the impact of a water jet onto circular targets of comparable diameter. Depending on the physical properties of the target surface, which may or may not be covered with a roughness at the micron-scale, i.e. arrays of cylindrical micron-size posts arranged on regular lattices, we obtain a variety of stable shapes including circles and polygons such as hexagons, eight corner stars. We vary the topographic features (height of the posts, lattice distance and geometry) and the jet properties (size of the nozzle, flow rate) and we measure the size and shape of the liquid sheet. We rationalize our results by taking into account the additional friction induced by the lattice providing a fluid velocity that depends on the orientation of the lattice.

Delancy, Adrian P.; Dressaire, Emilie; Courbin, Laurent; Stone, Howard A.

2008-11-01

397

Pesticides in surface water of the Mid-Atlantic region  

USGS Publications Warehouse

Water-quality data from 463 surface-water sites were compiled and analyzed to document the occurrence and distribution of pesticides in surface water of the Mid-Atlantic region as part of the Mid-Atlantic Integrated Assessment program of the U.S. Environmental Protection Agency. Those data collected by the U.S. Geological Survey from October 1973 through March 1997 were used in the analyses. Data are available for a large part of the Mid-Atlantic region, but large spatial gaps in the data do exist. USGS data bases contained analyses of surface-water samples for 127 pesticide compounds, including 12 degradates, but only 16 of the compounds were commonly detected. Atrazine, metolachlor, simazine, prometon, alachlor, tebuthiuron, cyanazine, diazinon, carbaryl, chlorpyrifos, pendimethalin, 2,4-D, dieldrin, DCPA, metribuzin, and desethylatrazine (an atrazine degradate) were detected in more than 100 of the samples analyzed. At least one pesticide was detected in about 75 percent of the samples collected and at more than 90 percent of the sites sampled. Concentrations greater than the Federal Maximum Contaminant Level (MCL) for drinking water of 3 micrograms per liter (ug/L) for atrazine were found in 67 of 2,076 samples analyzed; concentrations greater than the MCL of 2ug/L for alachlor were found in 13 of 1,693 samples analyzed, and concentrations greater than the MCL of 4 ug/L for simazine were found in 17 of 1,995 samples analyzed. Concentrations of four pesticides were greater than Federal Health Advisory levels for drinking water, and concentrations of nine pesticides were greater than Federal Ambient Water-Quality Criteria for the Protection of Aquatic Organisms. Streams draining basins with different land uses tend to have different pesticide detection frequencies and median concentrations. Median concentrations of herbicides tend to be highest in streams draining basins in which the major land use is agriculture, whereas median concentrations of insecticides tend to be highest in streams draining extensively urbanized basins. Concentrations of both herbicides and insecticides are usually highest during the spring and summer, although many pesticides are present at low concentrations in surface water throughout the year. Pesticide concentrations vary greatly seasonally and over different hydrologic conditions, with overall variation sometimes exceeding four orders of magnitude. During periods of pesticide application (typically spring and summer), the occurrence of selected pesticides in some streams in the Mid-Atlantic region is related to streamflow. Correlations between concentrations of selected pesticides and streamflow are statistically significant during spring and summer for small (draining less than 55 square miles) streams. Concentrations of selected pesticides in small streams increase during high flows in the growing season, up to 30 times the concentrations present during low-flow conditions in the growing season. In small streams draining urban areas, concentrations of atrazine decrease during high-flow events but concentrations of the insecticides diazinon and chlorpyrifos increase. This may be due to the differences in the pesticides used in agricultural and urban areas and the amounts applied.

Ferrari, Matthew J.; Ator, Scott W.; Blomquist, Joel D.; Dysart, Joel E.

1997-01-01

398

Microbial Monitoring of Surface Water in South Africa: An Overview  

PubMed Central

Infrastructural problems force South African households to supplement their drinking water consumption from water resources of inadequate microbial quality. Microbial water quality monitoring is currently based on the Colilert®18 system which leads to rapidly available results. Using Escherichia coli as the indicator microorganism limits the influence of environmental sources on the reported results. The current system allows for understanding of long-term trends of microbial surface water quality and the related public health risks. However, rates of false positive for the Colilert®18-derived concentrations have been reported to range from 7.4% to 36.4%. At the same time, rates of false negative results vary from 3.5% to 12.5%; and the Colilert medium has been reported to provide for cultivation of only 56.8% of relevant strains. Identification of unknown sources of faecal contamination is not currently feasible. Based on literature review, calibration of the antibiotic-resistance spectra of Escherichia coli or the bifidobacterial tracking ratio should be investigated locally for potential implementation into the existing monitoring system. The current system could be too costly to implement in certain areas of South Africa where the modified H2S strip test might be used as a surrogate for the Colilert®18.

Luyt, Catherine D.; Tandlich, Roman; Muller, Wilhelmine J.; Wilhelmi, Brendan S.

2012-01-01

399

Collisions of two breathers at the surface of deep water  

NASA Astrophysics Data System (ADS)

We present results of numerical experiments on long time evolution and collisions of breathers (which correspond to envelope solitons in the NLSE approximation) at the surface of deep ideal fluid. The collision happens to be nonelastic. In the numerical experiment it can be observed only after many acts of interactions. This supports the hypothesis of "deep water nonintegrability". The experiments were performed in the framework of the new and refined version of the Zakharov equation free of nonessential terms in the quartic Hamiltonian. Simplification is possible due to exact cancellation of nonelastic four-wave interaction.

Dyachenko, A. I.; Kachulin, D. I.; Zakharov, V. E.

2013-06-01

400

Oxidation of a polycrystalline titanium surface by oxygen and water  

Microsoft Academic Search

Reactions of a well-characterized polycrystalline titanium surface with oxygen and water molecules at 150–850K were studied in UHV by X-ray photoelectron spectroscopy (XPS), thermal desorption spectroscopy (TDS) and Fourier transform reflectance–absorption infrared spectroscopy (FT-RAIRS). At 150K, O2 oxidizes Ti0 to TiIV, TiIII and TiII, but Ti exposure to H2O at this temperature produces only TiII species. At temperatures above 300K,

Gang Lu; Steven L. Bernasek; Jeffrey Schwartz

2000-01-01

401

Surface oxides produced during discharge in water ambient iron surface: A conversion electron Mössbauer spectroscopic study  

Microsoft Academic Search

Oxide layers are produced on iron surface, under discharge in water ambient, applying both anodic and cathodic potentials to iron foil. Non-stoichiometric Fe1-xO containing different ratios of Fe3+ and Fe2+ has been detected by using CEMS. Corrosion of these samples in 0.5 M H2SO4 shows that, cathodically discharge treated iron foil has higher corrosion resistance as compared to the anodically

N. R. Bulakh; S. V. Ghaisas; S. A. Kulkarni; S. M. Kanetkar; S. B. Ogale; S. K. Date

1988-01-01

402

Surface oxides produced during discharge in water ambient iron surface: A conversion electron Mössbauer spectroscopic study  

Microsoft Academic Search

Oxide layers are produced on iron surface, under discharge in water ambient, applying both anodic and cathodic potentials\\u000a to iron foil. Non-stoichiometric Fe1?xO containing different ratios of Fe3+ and Fe2+ has been detected by using CEMS. Corrosion of these samples in 0.5 M H2SO4 shows that, cathodically discharge treated iron foil has higher corrosion resistance as compared to the anodically

N. R. Bulakh; S. V. Ghaisas; S. A. Kulkarni; S. M. Kanetkar; S. B. Ogale; S. K. Date

1988-01-01

403

Research of the optical breakdown near the water surface  

NASA Astrophysics Data System (ADS)

Influence of pulse duration and focussing mode the first and second harmoics radiation Nd:YAG lasers on shock waves characteristics arising at optical breakdown near to a surface of water was investigated in the present work. The lasers with different parameters of radiation were applied to making the optical breakdwon. The first laser had pulse of duration 4 ns, energy 240 mJ, and wave length of radiation 1064 nm; the second laser had pulse of duration 18 ns, energy 400 mJ, and wave length of radiation 1064 nm; and the third laser had a uplse length 5 ns, energy 180 mJ, and wave length of radiation 532 nm. The laser pulse was focused by the lens (f=70mm) above a surface of a liquid, and then it was directed on surface and under surface of a liquid with the help of the microscrew. For each case, was carried out registration of optical breakdown and arising shock waves by the shadow camera. THe spectral complex "Flame Vision PRO System" with the time resolution about 3 ns was used to analyze the shadow images.

Nagorny, I. G.; Yarovenko, F. P.

2005-06-01

404

Survey of perfluorinated compounds (PFCs) in surface waters of Poland.  

PubMed

Perfluorochemicals (PFCs) are wide-spread contaminants on a global scale. There is an increasingly growing number of data on environmental occurrence, sources and risk of PFCs to humans and aquatic biota in highly industrialised countries but inadequate information exists for less industrialised regions. In the present study, concentrations and profiles of PFCs were examined in surface waters (rivers, lakes, streams, coastal region of the Baltic Sea) of Poland. PFOS was the dominant compound found in water at most of the sites surveyed and its concentration varied between < 0.5 and 150 ng/L and next was PFHxS with < 0.25 to 110 ng/L, while at much smaller concentration of < 0.5 to 18 ng/L occurred PFOA. The long-chain carboxylates (C11-C16) could be found only in water of a drainage ditch near to the Sarzyna site, i.e., PFUnDA occurred at 0.17 ng/L, PFTeDA of 0.06 ng/L, PFDoDA at 0.1 ng/L and PFHxDA at 0.12 ng/L. PFDA was found at several locations in the Gulf of Gdansk and its concentration varied between < 0.01 and 0.07 ng/L. The profile of PFCs in surface water at several sites of Poland with PFOS as a major compound, followed by PFOA is similar to that reported for other countries in Europe as well as for India, while this is different from that of Korea, Japan and the USA, where PFOA was the predominant contaminant. PMID:20183509

Rostkowski, P; Taniyasu, S; Yamashita, N; Falandysz, Jaromir J; Zegarowski, L; Chojnacka, A; Pazdro, K; Falandysz, J

2009-12-01

405

Revealing the spatial variability of water fluxes at the groundwater-surface water interface  

NASA Astrophysics Data System (ADS)

There is widespread recognition that the groundwater-surface water interface can have significant influence on the pattern and form of the transfer of nutrient-rich groundwater to rivers. Characterizing and quantifying this influence is critical for successful management of water resources in many catchments, particularly those threatened by rising nitrate levels in groundwater. Building on previous experimental investigations in one such catchment: the River Leith, UK, we report on a multimeasurement, multiscale program aimed at developing a conceptualization of groundwater-surface water flow pathways along a 200 m reach. Key to this conceptualization is the quantification of vertical and horizontal water fluxes, which is achieved through a series of Darcian flow estimates coupled with in-stream piezometer tracer dilution tests. These data, enhanced by multilevel measurements of chloride concentration in riverbed pore water and water-borne geophysical surveying, reveal a contrast in the contribution of flow components along the reach. In the upper section of the reach, a localized connectivity to regional groundwater, that appears to suppress the hyporheic zone, is identified. Further downstream, horizontal (lateral and longitudinal) flows appear to contribute more to the total subsurface flow at the groundwater-surface water interface. Although variation in hydraulic conductivity of the riverbed is observed, localized variation that can account for the spatial variability in flow pathways is not evident. The study provides a hydrological conceptualization for the site, which is essential for future studies which address biogeochemical processes, in relation to nitrogen retention/release. Such a conceptualization would not have been possible without a multiexperimental program.

Binley, Andrew; Ullah, Sami; Heathwaite, A. Louise; Heppell, Catherine; Byrne, Patrick; Lansdown, Katrina; Trimmer, Mark; Zhang, Hao

2013-07-01

406

The toxic activities of Arisaema erubescens and Nerium indicum mixed with Streptomycete against snails.  

PubMed

The comparative molluscicidal activities of Arisaema erubescens tuber extracts and Nerium indicum leaf extracts mixed with Streptomycete violacerruber dilution (SD) against the snail Oncomlania hupensis and the responses of the isozymes, esterase (EST) and superoxide dismutase (SOD) to the A. erubescens extracts and the mixtures were investigated. The molluscicidal activity of A. erubescens water extracts mixed with S. violacerruber dilution was 4-5 times higher than a single A. erubescens or S. violacerruber dilution after 24-h exposure, and is also higher than that of N. indicum leaf water extracts mixed with S. violacerruber dilution. At the end of exposure to the N-butanol extracts of A. erubescens tubers (NEAT), the EST activity in snail liver decreased and some enzyme bands (EST 1 and EST 3 in exposure to NEAT) disappeared but the activities of SOD 1 increased. The effect was more obvious in mixture treatment than in single NEAT or SD treatment. The results indicated that molluscicidal activities of plant and microorganism could be more effective than single plant. The decline of the detoxic ability in snail liver cells could be the reason of the snail dying. PMID:21783953

Zhang, Yi; Ke, Wenshan; Yang, Jinglian; Ma, Anning; Yu, Zhensen

2008-11-21

407

Transport of Lincomycin to Surface and Ground Water from Manure-amended Cropland  

Microsoft Academic Search

Livestock manure containing antimicrobials becomes a possible source of these compounds to surface and ground waters when applied to cropland as a nutrient source. Th e potential for transport of the veterinary antimicrobial lincomycin to surface waters via surface runoff and to leach to ground water was assessed by monitoring manure-amended soil, simulated rainfall runoff , snowmelt runoff , and

Sandra L. Kuchta; Allan J. Cessna; Jane A. Elliott; Kerry M. Peru; John V. Headley

2009-01-01

408

EFFECT OF SEDIMENT ON THE FATE OF METOLACHLOR AND ATRAZINE IN SURFACE WATER  

Technology Transfer Automated Retrieval System (TEKTRAN)

Experiments were conducted to determine the persistence of atrazine and metolachlor in surface water, and to evaluate the contribution of sediment to their dissipation from surface waters. Atrazine was more persistent than metolachlor in the sediment-free surface water systems. First-order 50% dissi...

409

Effect of Deicing Salt on Ion Conentrations in Urban Roadside Snow and Surface Water  

Microsoft Academic Search

The damaging effects of deicing salt on surface water have been suggested by a number of studies, but there is a lack of knowledge about these effects on urban roadside snow and surface water in northeastern China. The concentrations of K, Ca, Na, Mg, Cu, Cd, Pb, Zn, Cl - and SO4 2- in roadside snow and surface water in

Fayun Li; Ying Zhang; Zaiping Xiong; Tingting Sun

2011-01-01

410

Water resources data for Florida, water year 1994. Volume 2A. South Florida surface water. Water-data report (Annual), 1 October 1993-30 September 1994  

Microsoft Academic Search

The data for South Florida included continuous or daily discharge for 74 streams, continuous or daily stage for 59 streams, peak stage discharge for no streams, continuous elevation for 1 lake; continuous groundwater levels for 224 wells, periodic ground-water levels for 437 wells and no miscellaneous water-level measurements; quality-of-water for 9 surface-water sites and 247 wells.

C. Price; M. Murray; E. Patino

1995-01-01

411

The relationship between surface rainrate and water paths and its implications to satellite rainrate retrieval  

NASA Astrophysics Data System (ADS)

Since brightness temperature measured by a passive microwave radiometer reflects the integrated effects of water paths, not surface rainrate, the accuracy of surface rainrate retrieval based on brightness temperatures relies heavily on the natural correlation between surface rainrate and water paths. In this study, we investigate how the water paths are related to surface rainrates using satellite data. It is found that corresponding to a similar surface rainrate ice water path is larger over land than over ocean. In addition, on average, the correlation (R2) between surface rainrate and ice water path over land (0.36) is also larger than over ocean (0.25). Over ocean, the correlation between surface rainrate and ice water path is greatly reduced where shallow convections exist. The results also show that given a similar surface rainrate, greater values of total water path occur over arid regions than over other land areas while the correlation between surface rainrate and total water path over such regions is smaller. Furthermore, given a similar surface rainrate, over ocean, larger values of liquid water path are observed over the intertropical convergence zone and maritime regions while smaller values appear over regions dominated by shallow convections. The explanation of the above differences in correlations is attempted using the seasonal variability of water paths and the rainfall systems' vertical structures. It is expected that the low correlation between surface rainrate and water paths will be a major obstacle for surface rainrate retrieval using microwave observations. In addition, surface rainrate always possesses a better relationship to liquid water path over ocean (or total water path over land) than to ice water path. Therefore, for surface rainrate retrievals, channels or channel combinations that can capture liquid water signal over ocean (or total water signal over land) are preferable to those solely containing ice water information.

You, Yalei; Liu, Guosheng

2012-07-01

412

Image analysis for water surface and subsurface feature detection in shallow waters  

NASA Astrophysics Data System (ADS)

Carefully collected airborne imagery demonstrates the ability to see water surface features as well as shallow bottom features such as submerged vegetation and manmade targets. Traditional photogrammetric imagery and airborne digital imagery both suffer from a loss in image clarity due to a number of factors, including capillary and small gravity waves, the water column or in-situ constituents. The use of submerged as well as surface man-made calibration targets deployed during airborne or in-situ subsurface image acquisitions forms a preliminary basis for correcting imagery in order to improve subsurface and surface features and their detection. Methods presented as well as imagery at 490 nm, 532 nm and 698-700 nm clearly show subsurface features in shallow waters. The techniques utilized include the use of large frame cameras with photogrammetric films in combination of special filters, such as a Wratten # 70, in order to provide narrower spectral features near the vegetative "red edge" to be used to improve interpretation of hyperspectral push broom imagery. Combined imagery from several sensors and platforms, including autonomous underwater vehicles, form the basis of data fusion for surface and subsurface automatic feature extraction. Data presented from a new hyperspectral imaging system demonstrates the utility of sub-meter hyperspectral imagery for use in subsurface feature detection.

Bostater, Charles R., Jr.; Jones, James; Frystacky, Heather; Kovacs, Mate; Jozsa, Oszkar

2010-10-01

413

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

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

414

OCCURRENCE OF 'CRYPTOSPORIDIUM' OOCYSTS IN SEWAGE EFFLUENTS AND SELECTED SURFACE WATERS  

EPA Science Inventory

An existing method for the detection of Cryptosporidium oocysts in water was modified to investigate oocyst prevalence in large volumes of water. Surface waters and sewage effluents were filtered, eluted from the filter, and concentrated using centrifugation. The resultant pellet...

415

Quantitative assessment to the structural basis of water repellency in natural and technical surfaces  

Microsoft Academic Search

Many plant surfaces are water-repellent because of a complex 3-dimensional microstructure of the epider- mal cells (papillae) and a superimposed layer of hydrophobic wax crystals. Due to its surface tension, water does not spread on such surfaces but forms spherical droplets that lie only on the tips of the microstructures. Studying six species with heavily microstructured surfaces by a new

P. Wagner; R. Furstner; W. Barthlott; C. Neinhuis

2003-01-01

416

Snail bioaccumulation of triclocarban, triclosan, and methyltriclosan in a North Texas, USA, stream affected by wastewater treatment plant runoff.  

PubMed

Grazing by freshwater snails promotes nutrient turnover in algal communities. Grazed algal compartments may include antimicrobial agents and metabolites, such as triclocarban (TCC), triclosan (TCS), and methyltriclosan (MTCS), which are incompletely removed by wastewater treatment plant (WWTP) processing. The present study quantifies snail bioaccumulation factors (BAFs) for TCC, TCS, and MTCS at the outfall of Pecan Creek (TX, USA), the receiving stream for the city of Denton (TX, USA) WWTP. Helisoma trivolvis (Say) is ubiquitous and thrives under standard laboratory conditions, leading to its choice for this bioaccumulation study in conjunction with Cladophora spp. Along with providing substrate for epiphytic growth, Cladophora spp. provide a source of food and shelter for H. trivolvis. After being caged for two weeks, algae and snails were collected from the WWTP outfall, along with water-column samples, and analyzed by isotope dilution gas chromatography-mass spectrometry for TCS and MTCS and by liquid chromatography-mass spectrometry for TCC. Algal and snail samples were analyzed before exposure and found to be below practical quantitation limits for all antimicrobial agents. Triclocarban, TCS, and MTCS in water samples were at low-ppt concentrations (40-200 ng/L). Triclocarban, TCS, and MTCS were elevated to low-ppb concentrations (50-300 ng/g fresh wt) in caged snail samples and elevated to low-ppb concentrations (50-400 ng/g fresh wt) in caged algal samples. Resulting snail and algal BAFs were approximately three orders of magnitude, which supports rapid bioaccumulation among algae and adult caged snails at this receiving stream outfall. The results further support TCC, TCS, and MTCS as good candidate marker compounds for evaluation of environmental distribution of trace WWTP contaminants. PMID:18380516

Coogan, Melinda A; La Point, Thomas W

2008-08-01

417

Background phosphorus concentrations in Danish groundwater and surface water bodies  

NASA Astrophysics Data System (ADS)

Quantitative information on the background concentration and loading of phosphorus is important when establishing the pressure-impact pathway for Danish streams, lakes and estuaries The background phosphorus loading thus determines present day lowest phosphorus loadings without influence from point sources and agriculture. We have mapped the background concentration of phosphorus in Danish groundwater and streams based on monitoring in 3000 groundwater wells, 7 small streams draining undisturbed catchments (1990-2010) and 19 streams draining small undisturbed catchments being monitored during 2004-2005. The concentration particulate P (PP) was found to be nearly constant within eight major georegions of Denmark (0.018 mg ± 0.010 mg P L-1. On contrary, the concentration of total dissolved P (TDP) was found to vary between 0.011-0.071 mg P L-1 within the eight georegions. We have also time series of background total P concentrations from 7 small undisturbed catchments covering the period 1990-2010. No significant trends have been observed in total P concentrations from these streams during the period 1990-2010. The average annual background loss of total phosphorus amounts to 730 tonnes P or 29% of the total loading of phosphorus from the Danish land to sea during the period 2007-2011. The measured TDP concentration in groundwater was much higher under reduced conditions (median: 0.10-0.15 mg P L-1) than in oxidized groundwater (<0.02 mg P L-1). Clear links could be established between TDP concentrations in reduced groundwater and the geological formations where chalk aquifers have low TDP concentrations and interglacial marine clay deposits having high TDP concentrations. No significant relationship could, however, be established between TDP concentration in oxidized groundwater and in stream water within the catchment to the 19 streams draining uncultivated areas. A modelling of the potential discharge of TDP from deeper reduced groundwater to surface waters in Denmark was performed with the MIKE SHE having a grid size of 1x1 km The (DK-model) (Henriksen et al., 2003). The discharge of TDP is low on the Danish Islands (< 1 kg P km-2) but very high in the western part of Jutland (10-17 kg P km-2). The question that can be raised is if these large quantities of TDP from deeper groundwater actually reach surface water or how much of the modelled TPD flux is sorbed in river valley sediments before discharging to surface water? References Henriksen, H.J., Troldborg, L., Nyegaard, P., Sonnenborg, T.O., Refsgaard, J.C. and Madsen, B. (2003) Methodology for construction, calibration and validation of a national hydrological model for Denmark. Journal of Hydrology (280) 52-71.

Kronvang, Brian; Bøgestrand, Jens; Windolf, Jørgen; Ovesen, Niels; Troldborg, Lars

2013-04-01

418

Earthquake cycle modulation via the redistribution of surface water mass  

NASA Astrophysics Data System (ADS)

Surface water bodies, from individual lakes to the global ocean, change in extent and mass over timescales ranging from a single year to a Milankovich cycle. Stress changes within the solid earth as a result of the redistribution of water mass have the potential to affect the seismic cycle on nearby faults through a combination of mechanisms, including deformation from the weight of the load and changes to effective normal stress via pore pressure diffusion. We present a model that quantifies these effects and their roles in modulating the seismic cycle. 3-D stress change from rebound is calculated using a semi-analytic method for a two-layer model including a thick elastic plate overlying a viscoelastic halfspace. The computational efficiency of the semi-analytic solution allows the true shape of the surface load to be accounted for without simplification. Effective normal stress from pore pressure diffusion is constrained by the hydrostatic end member. Two case studies are considered: 1) eustatic sea level rise since the Last Glacial Maximum and its ability to influence fault slip-rate in coastal regions during the late Pleistocene and early Holocene; and 2) intermittent floods of ancient Lake Cahuilla over the last 1200 years and their influence on fault rupture along the southern terminus of the San Andreas Fault. The sensitivity of a particular fault to water loading is highly dependent on both its geometry and its earthquake recurrence interval. The stresses imposed by these loads are generally an order of magnitude smaller than the tectonic stress accumulation over the same time period, such that redistributed surface loads can affect the timing of fault rupture but do not alter the structural or tectonic setting of a region. However, by advancing or delaying fault rupture, surface loads are able to perturb the apparent fault slip rate over the timescale of the redistribution. In particular, the long-term seismic cycle of a fault is more likely to be affected when a nearby flooding event recurs over a time period similar to the earthquake recurrence interval. These models are therefore helpful for understanding observations of fault slip-rate variability on a variety of systems.

Luttrell, K. M.; Brothers, D. S.

2011-12-01

419

Transport and fate of nitrate at the ground-water/surface-water interface  

USGS Publications Warehouse

Although numerous studies of hyporheic exchange and denitrification have been conducted in pristine, high-gradient streams, few studies of this type have been conducted in nutrient-rich, low-gradient streams. This is a particularly important subject given the interest in nitrogen (N) inputs to the Gulf of Mexico and other eutrophic aquatic systems. A combination of hydrologic, mineralogical, chemical, dissolved gas, and isotopic data, were used to determine the processes controlling transport and fate of NO3- in streambeds at five sites across the USA. Water samples were collected from streambeds at depths ranging from 0.3 to 3 m at three to five points across the stream and in two to five separate transects. Residence times of water ranging from 0.28 to 34.7 d m-1 in the streambeds of N-rich watersheds played an important role in allowing denitrification to decrease NO3- concentrations. Where potential electron donors were limited and residence times were short, denitrification was limited. Consequently, in spite of reducing conditions at some sites, NO3- was transported into the stream. At two of the five study sites, NO3- in surface water infiltrated the streambeds and concentrations decreased, supporting current models that NO3- would be retained in N-rich streams. At the other three study sites, hydrogeologic controls limited or prevented infiltration of surface water into the streambed, and ground-water discharge contributed to NO 3- loads. Our results also show that in these low hydrologic-gradient systems, storm and other high-flow events can be important factors for increasing surface-water movement into streambeds. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

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

2008-01-01

420

FULLY-INTEGRATED SURFACE AND SUBSURFACE MODEL FOR CONJUNCTIVE ANALYSIS OF WATER SUPPLY RELIABILITY, WATER QUALITY AND ECOSYSTEM HEALTH  

Microsoft Academic Search

In water resource management, there is an increasing emphasis on problems that require conjunctive analyses of surface\\/subsurface hydrologic and water-quality processes. Major issues of concern to water managers include water supply reliability, water quality, ecosystem health, and impact of climate change on water resources. In California, the most popular planning model is CalSim-II. In its current form, CalSim-II is not

E. A. Sudicky; R. Therrien; S. M. Panday; R. G. McLaren

421

Presence and risk assessment of pharmaceuticals in surface water and drinking water.  

PubMed

Trace amounts of pharmaceuticals have been detected in surface waters in the nano- to microgram per liter range, and in drinking water in the nanogram/L range. The environmental risks of pharmaceuticals in surface waters have been evaluated and generally found to be low if the wastewater is treated before release to the environment. The human health risks of trace amounts of pharmaceuticals in drinking water have however not been evaluated in any great depth. Preliminary screening level assessments suggest risk to be low--but the public and decision-makers are concerned and would like the matter investigated more thoroughly, especially with regards to mixture effects, chronic long-term effects and sensitive sub-populations. The World Health Organization is currently evaluating the need for credible health based guidance associated with low concentrations of pharmaceuticals in drinking water. The aim of this paper is to summarize the state-of-the-science and the ongoing international debate on the topic. PMID:21977632

Sanderson, Hans

2011-01-01

422

RISK-BASED PROCEDURES USED TO SUPPORT REMEDIATION OF A GROUND WATER- SURFACE WATER TRANSITION ZONE CONTAMINATED WITH CHLOROBENZENES  

EPA Science Inventory

Risk-Based Procedures Used to Support Remediation of a Ground Water - Surface Water Transition Zone Contaminated with Chlorobenzenes (Eastland Woolen Mill Superfund Site, Corinna, ME) In-situ and laboratory toxicity, sediment-toxicity identification evaluation (SIE), benthic macr...

423

Water resources data for New Mexico, water year 1966; Part 1. Surface water records  

USGS Publications Warehouse

by the Geological Survey in annual reports on a State-boundary basis. Distribution of these basic-data reports is limited and primarily for local needs. The records will be published in Geological Survey water-supply papers at 5-year intervals. These 5-year water-supply papers will show daily discharge and will be compiled on the same geographical areas previously used for the annual series; however, some of the 14 parts of conterminous United States will be further subdivided.

U.S. Geological Survey

1967-01-01

424

Numerical study of surface water waves generated by mass movement  

NASA Astrophysics Data System (ADS)

In this paper waves generated by two-dimensional mass movement are simulated using a numerical model based on the full hydrodynamic coupling between rigid-body motion and ambient fluid flow. This approach has the capability to represent the dynamics of the moving rigid body, which avoids the need to prescribe the body velocity based on the data measurements. This model is implemented in the CFX code and uses the Reynolds average Navier-Stokes equations solver coupled to the recently developed immersed solid technique. The latter technique allows us to follow implicitly the motion of the solid block based on the rigid body solver. The volume-of-fluid method is used to track the free surface locations. The accuracy of the present model is firstly examined against the simple physical case of a freely falling rigid body into water reproducing Scott Russell's solitary waves. More complex and realistic simulations of aerial and submarine mass-movement, simulated by a rigid wedge sliding into water along a 45° slope, are then performed. Simulated results of the aerial mass movement show the complex flow patterns in terms of the velocity fields and free surface profiles. Results are in good agreement with the available experimental data. In addition, the physical processes associated with the generation of water wave by two-dimensional submarine mass-movement are explored. The effects of the initial submergence and specific gravity on the slide mass kinematics and maximum wave amplitude are investigated. The terminal velocity and initial acceleration of the slide mass are well predicted when compared to experimental results. It is found that the initial submergence did not have a significant effect on the initial acceleration of the slide block centre of mass. However, it depends nonlinearly\\vadjust{\

Ghozlani, Belgacem; Hafsia, Zouhaier; Maalel, Khlifa

2013-10-01

425

Microdroplet growth mechanism during water condensation on superhydrophobic surfaces.  

PubMed

By promoting dropwise condensation of water, nanostructured superhydrophobic coatings have the potential to dramatically increase the heat transfer rate during this phase change process. As a consequence, these coatings may be a facile method of enhancing the efficiency of power generation and water desalination systems. However, the microdroplet growth mechanism on surfaces which evince superhydrophobic characteristics during condensation is not well understood. In this work, the sub-10 ?m dynamics of droplet formation on nanostructured superhydrophobic surfaces are studied experimentally and theoretically. A quantitative model for droplet growth in the constant base (CB) area mode is developed. The model is validated using optimized environmental scanning electron microscopy (ESEM) imaging of microdroplet growth on a superhydrophobic surface consisting of immobilized alumina nanoparticles modified with a hydrophobic promoter. The optimized ESEM imaging procedure increases the image acquisition rate by a factor of 10-50 as compared to previous research. With the improved imaging temporal resolution, it is demonstrated that nucleating nanodroplets coalesce to create a wetted flat spot with a diameter of a few micrometers from which the microdroplet emerges in purely CB mode. After the droplet reaches a contact angle of 130-150°, its base diameter increases in a discrete steplike fashion. The droplet height does not change appreciably during this steplike base diameter increase, leading to a small decrease of the contact angle. Subsequently, the drop grows in CB mode until it again reaches the maximum contact angle and increases its base diameter in a steplike fashion. This microscopic stick-and-slip motion can occur up to four times prior to the droplet coalescence with neighboring drops. Lastly, the constant contact angle (CCA) and the CB growth models are used to show that modeling formation of a droplet with a 150° contact angle in the CCA mode rather than in the CB mode severely underpredicts both the drop formation time and the average heat transfer rate through the drop. PMID:22548441

Rykaczewski, Konrad

2012-05-10

426

Complex interactions among fish, snails and macrophytes: implications for biological control of an invasive snail  

Microsoft Academic Search

The golden apple snail (Pomacea canaliculata), a native of freshwater wetlands of South America, has invaded many Asian countries and grazed heavily in agricultural and\\u000a wild areas. Common carp (Cyprinus carpio) has been proposed as a biological control agent against this snail, but little is known about its impact on non-target aquatic\\u000a plants and animals. In a 8-week enclosure experiment,

Pak Ki Wong; King Lun Kwong; Jian-Wen Qiu

2009-01-01

427

Metals in the surface sediments of selected water reservoirs, Slovakia.  

PubMed

Ruzin and Velke Kozmalovce water reservoirs (Slovakia) receive potentially toxic elements through rivers draining catchment areas polluted with the former extensive mining of ore-bearing deposits. In this study, the concentrations and fractionation of metals (antimony, arsenic, cadmium, chromium, cobalt, copper, lead, mercury, molybdenum, nickel, vanadium and zinc) have been studied in the surface sediments of the two water reservoirs. Comparison of metal concentrations found in the sediments with the mean shale values revealed a significant anthropogenic enrichment mostly with antimony (22.7), copper (8.5), zinc (5.5), cadmium (4.7), mercury (4.7), arsenic (4.5) and lead (3.9), and antimony (9.8), cadmium (8.8), zinc (4.9), lead (3.3) and arsenic (3.1) in the Ruzin and Velke Kozmalovce reservoirs, respectively. The results of fractionation study showed that the major proportion of cadmium (44.9-52.6%), cobalt (35.7-58.3%) and zinc (27.8-48.7%) was found in labile fractions, i.e., water- and acid-soluble fractions, although copper and nickel exhibited also significant labile fractions. When the risk assessment code was applied to the fractionation study, cadmium and cobalt came under high and very high risk category for the environment, and therefore might cause adverse effect to aquatic life. PMID:20411242

Hiller, Edgar; Jurkovic, Lubomír; Sutriepka, Michal

2010-04-22

428

Ground-water, surface-water, and water-chemistry data, Black Mesa area, northeastern Arizona--2003-04  

USGS Publications Warehouse

The N aquifer is the major source of water in the 5,400-square-mile area of Black Mesa in northeastern Arizona. Availability of water is an important issue in this area because of continued industrial and municipal use, a growing population, and precipitation of about 6 to 14 inches per year. The monitoring program in the Black Mesa area has been operating since 1971 and is designed to determine the long-term effects of ground-water withdrawals from the N aquifer for industrial and municipal uses. The monitoring program includes measurements of (1) ground-water pumping, (2) ground-water levels, (3) spring discharge, (4) surface-water discharge, (5) ground-water chemistry, and (6) periodic testing of ground-water withdrawal meters. In 2003, total ground-water withdrawals were 7,240 acre-feet, industrial withdrawals were 4,450 acre-feet, and municipal withdrawals were 2,790 acre-feet. From 2002 to 2003, total withdrawals decreased by 10 percent, industrial withdrawals decreased by 4 percent, and municipal withdrawals decreased by 20 percent. Flowmeter testing was completed for 24 municipal wells in 2004. The median difference between pumping rates for the permanent meter and a test meter for all the sites tested was -2.9 percent. Values ranged from -10.9 percent at Forest Lake NTUA 1 to +7.8 percent at Rough Rock NTUA 2. From 2003 to 2004, water levels declined in 6 of 12 wells in the unconfined part of the aquifer, and the median change was -0.1 foot. Water levels declined in 7 of 11 wells in the confined part of the aquifer, and the median change was -2.7 feet. From the prestress period (prior to 1965) to 2003, the median water-level change for 26 wells was -23.2 feet. Median water-level change were -6.1 feet for 14 wells in the unconfined parts of the aquifer and and -72.1 feet for 12 wells in the confined part. Discharges were measured once in 2003 and once in 2004 at four springs. Discharge stayed the same at Pasture Canyon Spring, increased 9 percent at Moenkopi Spring, decreased 26 percent at an unnamed spring near Dennehotso, and decreased 50 percent at Burro Spring. For the past 12 years, discharges from the four springs have fluctuated; however, an increasing or decreasing trend is not apparent. Continuous records of surface-water discharge have been collected from 1976 to 2003 at Moenkopi Wash, 1996 to 2003 at Laguna Creek, 1993 to 2003 at Dinnebito Wash, and 1994 to 2003 at Polacca Wash. Median flows for November, December, January, and February of each water year were used as an index of ground-water discharge to those streams. Since 1995, the median winter flows have decreased for Moenkopi Wash, Dinnebito Wash, and Polacca Wash. Since the first continuous record of surface-water discharge in 1997, there is no consistent trend in the median winter flow for Laguna Creek. In 2004, water samples were collected from 12 wells and 4 springs and analyzed for selected chemical constituents. Dissolved-solids concentrations ranged from 100 to 649 milligrams per liter. Water samples from 11 of the wells and from all the springs had less than 500 milligrams per liter of dissolved solids. There are no appreciable time trends in the chemistry of water samples from 7 wells and 2 springs; increasing trends in dissolved-solids and chloride concentrations were evident from the more than 10 years of data for 2 springs.

Truini, Margot; Macy, Jamie P.; Porter, Thomas J.

2005-01-01

429

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

PubMed

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

2004-01-01

430

Groundwater/Surface-Water Interaction in the Context of South African Water Policy  

NASA Astrophysics Data System (ADS)

Groundwater/surface-water interaction is receiving increasing focus in Africa due to its importance to ecologic systems and sustainability. South Africa’s 1998 National Water Act (NWA) recognized water as a basic human right and its importance for ecological sustainability. Ecological integrity of water resources was considered an important component in redressing past social inequities, eliminating poverty, and encouraging economic development. Under the NWA, groundwater-use licenses are granted only after setting aside the groundwater Reserve, the amount of water needed to supply basic human needs and preserve a minimum degree of ecological integrity. One challenge to successful implementation of the NWA, therefore, is the accurate quantification of groundwater contributions to aquatic ecosystems. This is especially true considering that so many of South Africa’s aquifers are in highly heterogeneous and anisotropic fractured-rock settings. The most common approach taken in South Africa is estimation of average annual flux rates at the regional scale of quaternary catchments with baseflow separation techniques and then applying a water-budget approach, subtracting the groundwater discharge rate from the recharge rate. The water-balance approach might be a good first step, but it ignores spatial and temporal variability, potentially missing the local impacts associated with placement of production boreholes. Identification of discrete areas of groundwater discharge could be achieved with stable-isotopic and geochemical analyses and vegetative mapping. Groundwater-flow modeling should be used where possible as it holistically incorporates available data and can predict impacts of groundwater extraction and development based on the relative positions of boreholes and surface-water bodies. Sustainable development entails recognition of the trade-offs between preservation and development. There will always be scientific uncertainty associated with estimation and preservation of the groundwater reserve, the reduction of which will require the application of an adaptive management approach, iteratively applied to discrete locations chosen for their social, economic and ecological importance, a process that must begin and end with stakeholder participation. As South Africa’s NWA has already been emulated in many countries including Zambia, Zimbabwe and Kenya, the successes and failures of the South African experience dealing with the groundwater/surface-water interaction will be analyzed to guide future policy directions.

Levy, J.; Xu, Y.

2010-12-01

431

Density-dependent effects of snail grazing on the growth of a submerged macrophyte, Vallisneria spiralis  

Microsoft Academic Search

In order to better understand the role of herbivorous snails in freshwater ecosystems, we conducted experiments investigating food preference of the snail Radix swinhoei on leaves of the submerged plant Vallisneria spiralis with and without periphyton coverage. The effects of snail grazing on the growth of V. spiralis were assessed in a no-snail control and at three snail densities (80,

Kuan-Yi Li; Zheng-Wen Liu; Bin-He Gu

2009-01-01

432

Modeling surface-water flow and sediment mobility with the Multi-Dimensional Surface-Water Modeling System (MD_SWMS)  

USGS Publications Warehouse

The Multi-Dimensional Surface-Water Modeling System (MD_SWMS) is a Graphical User Interface for surface-water flow and sediment-transport models. The capabilities of MD_SWMS for developing models include: importing raw topography and other ancillary data; building the numerical grid and defining initial and boundary conditions; running simulations; visualizing results; and comparing results with measured data.

McDonald, Richard; Nelson, Jonathan; Kinzel, Paul; Conaway, Jeff

2006-01-01

433

DETERMINATION OF ESTIVATION-INDUCED CHANGES IN THE AMINO ACID CONTENT OF BIOMPHALARIA GLABRATA SNAILS BY HIGH PERFORMANCE THIN-LAYER CHROMATOGRAPHY-DENSITOMETRY  

Microsoft Academic Search

High performance thin-layer chromatography-densitometry (HPTLC-Dens) was used to determine changes in the amino acid content of the digestive-gland gonad complex (DGG) of Biomphalaria glabrata snails as a function of estivation. Amino acids were extracted in ethanol-water (70:30) from the DGG of B. glabrata snails estivated for 7 days, and determined on