bluuebunny/crossref_metadata_2025 huggingface dataset:
Behavioral responses of the parasitoid Psyllaephagus pistaciae (Hymenoptera: Encyrtidae) to host plant volatiles and honeydew
Authors: MEHRNEJAD M. Reza , COPLAND Michael J. W.
Published: March 2006

The behavioral responses of the parasitoid Psyllaephagus pistaciae, the major biocontrol agent of the common pistachio psylla, Agonoscena pistaciae, to volatiles emanating from its host plant and host honeydew, were examined using a four‐arm airflow olfactometer. In addition, the arrestment behavior of this parasitoid on clean and honeydew‐treated leaves of the pistachio, Pistacia vera, was monitored. The infested pistachio leaves were the most favored source of the volatile attracting the parasitoids. The parasitoid clearly distinguished and responded to infochemicals emitted by psyllid honeydew but at a lower level than to the volatiles from infested host plants. However, the searching time, locomotory behavior, antennal drumming and ovipositor probing were all affected when they encountered honeydew‐contaminated zones on pistachio leaves. These findings suggest that the psyllid honeydew releases kairomones that stimulate the parasitoids to greater searching activity, as well as providing a directional cue. The intensive searching activities in the presence of the volatiles tested were very similar to responses by the parasitoid females when encountering patches treated with psyllid honeydew. Such behavior could retain the parasitoid in a favorable area, thereby increasing the probability of additional host encounters.
Review of the North American Tarphiota Casey, with a description of a new seashore‐inhabiting Atheta species exhibiting convergent characteristics (Coleoptera: Staphylinidae: Aleocharinae)
Authors: KLIMASZEWSKI Jan , MAJKA Christopher G. , LANGOR David
Published: March 2006

A review of the North American species of the genus Tarphiota Casey is presented. Three species are recognized: T. densa (Moore), T. fucicola (Mäklin), and T. geniculata (Mäklin). They occur on the sandy beaches of the Pacific coast. A new coastal species of Atheta, found on the seashore and exhibiting certain convergent characteristics to Tarphiota, is described from the Atlantic coast: A. novaescotiae Klimaszewski and Majka, sp. nov. All Canadian species are provided with diagnoses, genitalic illustrations and digital photos of their habitus in dorsal and lateral view. A key is presented to distinguish the species. New data on the natural history of A. novaescotiae are presented and briefly discussed.
Vespidae (Hymenoptera) of Vietnam 3: Synoptic key to Vietnamese species of the polistine genus Ropalidia, with notes on taxonomy and distribution
Authors: NGUYEN Lien T. P. , KOJIMA Jun‐ichi , SAITO Fuki , CARPENTER James M.
Published: March 2006

Nineteen species of the paper wasp genus Ropalidia are recorded from Vietnam, of which three are new records for Vietnam. A key to all of the species, distribution records and taxonomic remarks are given. New synonymies proposed are: Ropalidia bicolorata parvula van der Vecht, 1962, under R. bicolorata van der Vecht, 1962; R. hongkongensis juncta van der Vecht, 1941, under R. hongkongensis (de Saussure, 1854); Icaria jucunda Cameron, 1898, and R. marginata sundaica van der Vecht, 1941, under R. marginata (Lepeletier, 1836); R. rufocollaris atrata van der Vecht, 1941, under R. rufocollaris (Cameron, 1900); and R. stigma rufa van der Vecht, 1941 and R. stigma nigrolineata van der Vecht, 1962, under R. stigma (Smith, 1858).
Structure, mechanism and mechanical properties of pupal attachment in Greta oto (Lepidoptera: Nymphalidae: Ithomiinae)
Authors: INGRAM Abigail L. , PARKER Andrew R.
Published: March 2006

The structure and mechanism of pupal attachment are described for the nymphalid Greta oto using electron microscopy, and high‐speed and time‐lapse photography. The cremaster is composed of a 3‐D array of hooked setae that engage with silk fibers spun into layers in a pad on the lower leaf surface. Each seta comprises a shaft terminating in a strongly curved hook, tipped with two lateral barbs. These hook into the silk pad, which is densely laid and built‐up in the central portion, flattening out peripherally. Time‐lapse photography showed that silk pad construction by fifth instar larvae is completed in four distinct spinning movements, producing a random fiber arrangement. It is proposed that such a fiber arrangement provides isotropic strength, giving greater flexibility to the attachment. The cremaster is attached to the silk pad by a series of lateral movements of the pupa's posterior abdomen. This movement, together with the shape of the setal hooks, is thought to be integral to the attachment process. Tensile loading tests showed that attachment failure is due to the breakage of the silk pad, which undergoes gradual destruction before releasing the cremaster. The attachment was found to have high tensile strength and fracture toughness, both of which suggest that it has evolved for the dual purpose of preventing the pupa being pulled from the leaf by a predator and preventing the attachment being weakened by wind, which causes the pupa to swing.
Drosophila subpulchrella, a new species of the Drosophila suzukii species subgroup from Japan and China (Diptera: Drosophilidae)
Authors: TAKAMORI Hisaki , WATABE Hide‐aki , FUYAMA Yoshiaki , ZHANG Ya‐ping , AOTSUKA Tadashi
Published: March 2006

Drosophila (Sophophora) subpulchrella Takamori and Watabe, sp. nov., of the D. suzukii subgroup in the D. melanogaster species group, is described from Japan and southern China, and compared with its sibling species, D. pulchrella Tan et al. distributed in the Yun‐Gui Highland, south‐western China. The results of cross‐experiments show a complete pre‐mating isolation between D. subpulchrella and D. pulchrella.
Serial Reevaluation for ARVD/C Is Indicated in Patients Presenting with Left Bundle Branch Block Ventricular Tachycardia and Minor ECG Abnormalities
Authors: KIÈS PHILIPPINE , BOOTSMA MARIANNE , BAX JEROEN J. , ZEPPENFELD KATJA , Van ERVEN LIESELOT , WIJFFELS MAURITS C. , Van Der WALL ERNST E. , SCHALIJ MARTIN J.
Published: March 2006

Introduction: Diagnosis of arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is based on a set of criteria proposed by the International Task Force (TF) for Cardiomyopathies in 1994. To fulfill these criteria, presence of both electrocardiographic and anatomical abnormalities must be assessed with ECG and imaging techniques, respectively. This may be difficult in patients with early/mild forms of the disease as detectable structural abnormalities may still be absent. We evaluated in which patients presenting with right ventricular tachycardia (VT) serial reevaluation for ARVD/C is indicated.

Methods and Results: Sixty consecutive patients (41 men, mean age 40±15 years) were evaluated by the TF criteria for possible ARVD/C because of presentation with a left bundle branch block (LBBB) VT, representing 1 minor criterion. The presence on the ECG of a T‐wave inversion beyond lead V2 (1 minor), right precordial QRS prolongation (1 major), or an epsilon wave (1 major) was assessed together with the visualization of severe regional/global right ventricle dysfunction (1 major) or mild segmental dilatation/regional hypokinesia (1 minor) by standard imaging techniques. Initially, 22 (37%) patients were diagnosed as having ARVD/C. After 47±39 (range 6–146) months, 23 initially TF‐negative patients were reevaluated because of recurrent symptoms, with 12 (52%) additional patients now meeting the TF criteria. Eleven of these 12 (92%) patients presented initially with ECG abnormalities only, but developed structural abnormalities on imaging at follow‐up.

Conclusion: ECG abnormalities may precede structural abnormalities warranting serial reevaluation for ARVD/C in initially TF‐negative patients presenting with LBBB VT with only ECG abnormalities.
An Unusual Form of Bundle Branch Reentrant Tachycardia
Authors: SARKOZY ANDREA , BOUSSY TIM , CHIERCHIA GIAN‐BATTISTA , GEELEN PETER , BRUGADA PEDRO
Published: March 2006

Introduction: We report the case of a 36‐year‐old patient with a longstanding history of paroxysmal tachycardia.

Methods and Results: During the electrophysiological study, the H‐V interval was prolonged in sinus rhythm, and a second potential (H″) with distal to proximal activation pattern was recorded in the region of the proximal His‐Purkinje system. Two wide QRS complex tachycardias were induced, both with V‐A dissociation. One application of radiofrequency energy at the site with earliest and largest H″ potential during sinus rhythm cured both tachycardias. The right and left bundle branch block morphology tachycardias were diagnosed as clockwise and counterclockwise bundle branch reentrant tachycardia. The H″ potential represented the retrograde right bundle potential during sinus rhythm and bundle branch block reentrant tachycardia.
Performance of six bone collectors designed for dental implant surgery
Authors: Kainulainen Vesa T. , Kainulainen Tiina J. , Oikarinen Kyösti S. , Carmichael Robert P. , Sàndor George K. B.
Published: March 2006

Objectives: The aim of this study was to perform an in vitro comparison of six bone collectors for harvesting of particulate bone.

Material and methods: Four commercially available bone collectors (Frios®, Osseous Coagulum Trap®, ACE Autografter®, Bone Trap®) and two custom‐designed models were tested. Three different in vitro tests were performed to determine the harvesting capabilities of the collectors. In test I, a bovine mandible was drilled and the bone collectors were used to collect bone chips. The harvested bone volumes and dry weights were measured after harvesting. In test II, three dental implant sites were prepared in a bovine mandible. The bones from the implant osteotomies were collected, and bone volumes and dry weights were measured. In test III, 1 ml of bone chips was mixed with water, and suctioned through the bone collectors. The volumes of the bone chips retained were measured to determine the efficiency of each collector.

Results: The Osseous Coagulum Trap® and the custom‐made collectors were the most effective instruments in test I. The mean volumes ranged from 0.17 to 0.38 ml. In test II, the difference between the collectors was small and the bone volume ranged from 0.28 to 0.37 ml. In test III, the Bone Trap® became blocked before the other collectors, and its bone procurement was therefore limited.

Conclusion: Comparison of six different bone collectors in this in vitro study showed that all collectors are usable in clinical situations but their effectiveness varies.
Oral myofunctional and vocal characteristics in subjects subjected to oral rehabilitation with osseointegrated implants
Authors: Sansone Karilla Matteo , Filho Hugo Nary , Berretin‐Félix Giédre , Brasolotto Alcione Ghedini
Published: March 2006

Purpose: The aim of this study was to evaluate the effect of oral rehabilitation using immediately loaded fixed implant‐supported mandibular prostheses, considering chewing, swallowing, speech and voice aspects.

Material and methods: Fourteen patients subjected to this treatment were evaluated by a clinical examination of the stomatognathic system and perceptual evaluation of voice quality before oral rehabilitation, as well as after 1 and 4 months.

Results: After oral rehabilitation, the results showed that there were no significant modifications in the aspects investigated.

Conclusion: Thus, implant‐supported prosthetic rehabilitation, despite providing a more satisfactory occlusal standard, did not yield changes in the functional patterns of individuals in this study.
Recombinant purple acid phosphatase isoform 3 from sweet potato is an enzyme with a diiron metal center
Authors: Waratrujiwong Teerawit , Krebs Bernt , Spener Friedrich , Visoottiviseth Pornsawan
Published: March 2006

Purple acid phosphatases (PAPs) from sweet potato (sp) have been classified on the basis of their primary structure and the dinuclear metal center into isoforms spPAP1 [Fe(III)–Zn(II)] and spPAP2 [Fe(III)–Mn(II)]; for spPAP3 only the cDNA is known. With the aim of unraveling the character of the dinuclear metal center we report here the characterization of this isoform at the protein level. We cloned spPAP3 cDNA in a baculovirus and overexpressed this enzyme in Sf9 insect cells. Preparation of recombinant spPAP3 in two steps afforded pure enzyme with yields of 4.5 mg·L−1 culture medium. This enzyme is a dimeric, disulfide‐linked PAP of 110 kDa, similar to known PAP isoforms from higher plants. Enzymatic studies and spectroscopic properties (max. absorption at 550–565 nm) indicated a diiron enzyme; quantitative and semiquantitative metal analysis using ICP‐OES and TOF‐SIMS, respectively, revealed the presence of only iron in purified spPAP3. Metal replacement in the second metal‐binding site upon preparation of the semiapo‐enzyme with Fe(II), Zn(II), or Mn(II) showed highest activities with Fe(II). The data show that recombinant spPAP3 has a diiron metal center. Site‐directed mutagenesis was conducted to check catalytic efficiency at the atomic level. Tyr291 at the substrate‐binding site in spPAP3 was mutated to His and Ala, the respective residues found in spPAP1 and spPAP2. Kinetic analysis showed that conversion of Tyr291 to His further optimized the performance of this protein as a diiron enzyme, whereas the Ala mutation weakened the catalytic efficiency regardless of the metal present in the second binding site.
Puroindoline‐a and α1‐purothionin form ion channels in giant liposomes but exert different toxic actions on murine cells
Authors: Llanos Paola , Henriquez Mauricio , Minic Jasmina , Elmorjani Khalil , Marion Didier , Riquelme Gloria , Molgó Jordi , Benoit Evelyne
Published: March 2006

Puroindoline‐a (PIN‐a) and α1‐purothionin (α1‐PTH), isolated from wheat endosperm of Triticum aestivum sp., have been suggested to play a role in plant defence mechanisms against phytopathogenic organisms. We investigated their ability to form pores when incorporated into giant liposomes using the patch‐clamp technique. PIN‐a formed cationic channels (≈ 15 pS) with the following selectivity K+ > Na+ ≫ Cl–. Also, α1‐PTH formed channels of ≈ 46 pS and 125 pS at +100 mV, the selectivity of which was Ca2+ > Na+ ≈ K+ ≫ Cl– and Cl– ≫ Na+, respectively. In isolated mouse neuromuscular preparations, α1‐PTH induced muscle membrane depolarization, leading to blockade of synaptic transmission and directly elicited muscle twitches. Also, α1‐PTH caused swelling of differentiated neuroblastoma NG108‐15 cells, membrane bleb formation, and disorganization of F‐actin. In contrast, similar concentrations of PIN‐a had no detectable effects. The cytotoxic actions of α1‐PTH on mammalian cells may be explained by its ability to induce cationic‐selective channels.
Sulfatide with short fatty acid dominates in astrocytes and neurons
Authors: Isaac Giorgis , Pernber Zarah , Gieselmann Volkmar , Hansson Elisabeth , Bergquist Jonas , Månsson Jan‐Eric
Published: March 2006

Glycosphingolipids are located in cell membranes and the brain is especially enriched. We speculated that the subcellular location of glycosphingolipids depends on their fatty acid chain length because their sugar residues are constant, whereas fatty acid chain length can vary within the same molecule. To test this hypothesis we analysed the glycosphingolipid sulfatide, which is highly abundant in myelin and has mostly long fatty acids. We used a negative ion electrospray tandem mass spectrometry precursor ion scan to analyse the molecular species of sulfatide in cultured astrocytes and a mouse model of the human disease metachromatic leukodystrophy. In these arylsulfatase A (ASA)‐deficient mice sulfatide accumulates intracellularly in neurons and astrocytes. Immunocytochemistry was also performed on cultured astrocytes and analysed using confocal laser scanning microscopy. Analyses of the molecular species showed that cultured astrocytes contained sulfatide with a predominance of stearic acid (C18), which was located in large intracellular vesicles throughout the cell body and along the processes. The same was seen in ASA‐deficient mice, which accumulated a higher proportion (15 mol% compared with 8 mol% in control mice) of sulfatide with stearic acid. We conclude that the major fatty acid composition of sulfatide differs between white and grey matter, with neurons and astrocytes containing mostly short‐chain fatty acids with an emphasis on stearic acid. Based on our results, we speculate that the fatty acid chain length of sulfatide might determine its intracellular (short chain) or extracellular (long chain) location and thereby its functions.
SAMPLE SIZE IN CONSUMER TEST AND DESCRIPTIVE ANALYSIS
Authors: GACULA MAXIMO , RUTENBECK SHERI
Published: March 2006

This article deals with sample size (n) estimation by computer simulation using the variance of consumer and in‐house sensory tests. The current sample size used in descriptive analysis was also examined. The sample size ranging from 20 to 200 was used to detect a difference ranging from 0.0 to 1.0 on a 9‐point hedonic scale. For the simulated consumer data, significant difference was first observed at a difference of 0.60 when n = 40. Increasing the difference to above 0.60, the first significance likewise appeared when n = 40. Based on the variability used in the study, these results support the commonly cited sample size of 40–100. Thus, the role of the difference to be detected is very important in determining the sample size (base size). The variance can be obtained from historical data. In this study, the difference ranging from 0.60 to 1.00 is critical and can be used by the research and sensory analysts as a guide. Therefore, the analysts must have an idea of the size of hedonic differences among formula or products to be compared in determining the appropriate sample size. The power of the test for various sample sizes is provided through plots of power versus n. For descriptive analysis, the results showed that the recommended minimum is n = 5, noting that in most cases, judges differed by 1 unit on a 15‐point rating scale. The power of the test is also reported for n ranging from 5 to 14 judges.
FLAVOR PROPERTIES OF PLAIN SOYMILK*
Authors: CHAMBERS EDGAR , JENKINS ALICIA , MCGUIRE BRUCE H.
Published: March 2006

A trained sensory panel was used to (1) establish terminology for describing flavor attributes of a wide range of “fresh” and processed soymilks (SMs); and (2) test the lexicon and describe the flavor properties of a wide range (n = 32) of plain SM samples. Twenty‐eight attributes were identified in the SMs studied. However, findings indicate that the main differences are a consequence largely of the presence of certain attributes that are either infrequently present or unique to a specific product. Thus, sensory evaluation of SM needs to include a review of samples to ensure that all attributes are documented prior to evaluation, or use a method that allows the addition of attributes during testing.
USING THE INTERNET FOR DESCRIPTIVE SENSORY ANALYSIS: FORMATION, TRAINING AND FOLLOW‐UP OF A TASTE‐TEST PANEL OVER THE WEB
Authors: NOGUEIRA‐TERRONES H. , TINET C. , CURT C. , TRYSTRAM G. , HOSSENLOPP J.
Published: March 2006

A remote descriptive analysis panel was formed and trained over the Internet. This article outlines the steps involved in this method: (1) creation of Web sensory sessions; (2) recruitment and selection of assessors; (3) generation of descriptors; (4) training using generated descriptors; and (5) check‐up sessions. A reference panel was formed and trained conventionally: it aimed, on the one hand, at providing the necessary reference points for training the Internet panel and on the other hand, at validating the proposed method by the comparison of the results assessed on the same product by both panels. We applied our methodology to a dry sausage. Sixteen assessors carried out the complete training on 10 descriptors during 10 sessions. The results of the analysis of variance with (panel–product) interactions considering each attribute separately showed that product classification is the same for the two panels on the basis of seven descriptors out of 10. The results concerned with the performance of individual assessors showed that training duration seemed to be the most important feature in determining the level of performance of assessors remotely trained over the Internet.
VANILLA FLAVOR EVALUATION BY SENSORY AND ELECTRONIC NOSE TECHNIQUES
Authors: HARIOM  , SHYAMALA B.N. , PRAKASH M. , BHAT K.K.
Published: March 2006

Aroma analyses using electronic nose (E‐nose) and sensory techniques with a trained panel were conducted for vanilla extracts from four samples of vanilla pods, namely, T1 (Bourbon method), T2 (Improved T1), M1 (Mexican method) and M2 (Improved M1). The E‐nose pattern matching complemented sensory threshold results, odor profiling and flavor profile results. T2 and M2 differed from the rest of the samples by showing discrimination in flavor quality between four extracts and a blank (BL). Threshold values of the extracts were in the range of 3.7 to 4.1 and 3.6 to 4.0 mg/L when prepared in water and milk mediums, respectively. The descriptive sensory profiling of the flavor of vanilla extract in different media using quantitative descriptive analysis (QDA) has indicated that milk was an optimum carrier or medium for the clear perception of characteristic vanilla attributes. T2 and M2 extracts had higher intensities of impact‐making attributes, namely, vanilla, floral and sweet notes. The intensity ratings were 8.0, 8.8 and 12.1, 11.0 for the vanilla and sweet notes of M2 and T2 extracts, respectively, when flavor profiling of vanilla extracts were prepared in milk as the medium. The odor profiling of vanilla extracts also showed similar results.
Variability of Isotope and Major Ion Chemistry in the Allequash Basin, Wisconsin
Authors: Walker John F. , Hunt Randall J. , Bullen Thomas D. , Krabbenhoft David P. , Kendall Carol
Published: March 2006

As part of ongoing research conducted at one of the U.S. Geological Survey's Water, Energy, and Biogeochem‐ical Budgets sites, work was undertaken to describe the spatial and temporal variability of stream and ground water isotopic composition and cation chemistry in the Trout Lake watershed, to relate the variability to the watershed flow system, and to identify the linkages of geochemical evolution and source of water in the watershed. The results are based on periodic sampling of sites at two scales along Allequash Creek, a small headwater stream in northern Wisconsin. Based on this sampling, there are distinct water isotopic and geochemical differences observed at a smaller hillslope scale and the larger Allequash Creek scale. The variability was larger than expected for this simple watershed, and is likely to be seen in more complex basins. Based on evidence from multiple isotopes and stream chemistry, the flow system arises from three main source waters (terrestrial‐, lake‐, or wetland‐derived recharge) that can be identified along any flowpath using water isotopes together with geochemical characteristics such as iron concentrations. The ground water chemistry demonstrates considerable spatial variability that depends mainly on the flow‐path length and water mobility through the aquifer. Calcium concentrations increase with increasing flowpath length, whereas strontium isotope ratios increase with increasing extent of stagnation in either the unsaturated or saturated zones as waters move from source to sink. The flowpath distribution we identify provides important constraints on the calibration of ground water flow models such as that undertaken by Pint et al. (this issue).
Flowpath Delineation and Ground Water Age, Allequash Basin, Wisconsin
Authors: Pint Christine D. , Hunt Randall J. , Anderson Mary P.
Published: March 2006

An analysis of ground water flowpaths to a lake and creek in northern Wisconsin shows the flow system in a geologically simple basin dominated by lakes can be surprisingly complex. Differences in source area, i.e., lakes or terrestrial, combined with the presence of intervening lakes, which may or may not capture underflowing ground water as water moves downgradient from recharge areas, contribute to a complex mix of flowpaths. The result is water of different chemistry and vastly different ages may discharge in close proximity. Flowpaths, travel times, and capture zones in the Allequash Basin in northern Wisconsin were delineated using particle tracking based on a calibrated steady‐state ground water flow model. The flowpath analysis supports the conclusions of Walker et al. (2003) who made inferences about flowpath characteristics from isotope and major ion chemistry. Simulated particle tracking agreed with Walker et al.'s measurements of water source (lake or terrestrial recharge) in the stream subsurface and also supported their assertion that ground water with a high calcium concentration in the lower basin of Allequash Lake is derived from long flowpaths. Numerical simulations show that ground water discharging in this area originates more than 5 km away in a source area located upgradient of Big Muskellunge Lake, which is upgradient of Allequash Lake. These results graphically illustrate that in settings with multiple sources of water with different age characteristics and converging flowlines (like the Allequash Basin) it may be difficult to obtain accurate estimates of ground water age by chemical analyses of ground water.
Ground Water Storage Effect on Streamflow for a Southeastern Coastal Plain Watershed
Authors: Bosch David D. , Lowrance R. Richard , Sheridan Joseph M. , Williams Randall G.
Published: March 2006

Ground water is known to substantially affect streamflow in regions where the two are interconnected. Likewise, streamflow can rapidly recharge surficial aquifers. Because of this interaction, accurate predictions of streamflow require accurate data on the relationships between streamflow and shallow aquifer conditions. Ground water levels in the surficial aquifer and streamflow were examined for a six‐year period for two small watersheds in south‐central Georgia within the Coastal Plain Physiographic region of the United States. Precipitation for the six‐year period was below average. The shallow water table was elevated during average precipitation conditions, but receded as precipitation decreased. During the three‐year period from 2000 through 2002, the riparian buffer was fully saturated approximately 40% of the time. Lower available aquifer storage was observed for late winter and early spring due to higher rainfall and lower evapotranspiration (ET). During recharge periods, which generally coincided with the period from December to March, the ground water gradient from the upland to the stream was approximately equal to the 3% land surface slope. During other times of the year, the gradient fluctuated dramatically as a response to individual precipitation events, streamflow, and focused recharge. Based on ground water discharging to the stream for 40% of the year, ground water discharge accounted for approximately 4% of the annual precipitation for the period from 2000 through 2002. Aquifer saturation, the fraction of the available aquifer storage filled by ground water, was found to have a substantial effect upon streamflow. During periods when the aquifer was fully saturated, observed storm‐generated streamflow peak rates were greater and of shorter duration. Comparison of similar magnitude events occurring in 1998 indicated that peak discharge was up to three times greater under saturated aquifer conditions than under nonsaturated conditions. Watersheds with substantial pond acreage appear to extend storm‐flow over longer durations. These data indicate the impact of aquifer and pond storage on peak and total discharge in coastal plain watersheds.
The Geochemical Evolution of Riparian Ground Water in a Forested Piedmont Catchment
Authors: Burns Douglas A. , Plummer L. Niel , McDonnell Jeffrey J. , Busenberg Eurybiades , Casile Gerolamo C. , Kendall Carol , Hooper Richard P. , Freer James E. , Peters Norman E. , Beven Keith , Schlosser Peter
Published: March 2006

The principal weathering reactions and their rates in riparian ground water were determined at the Panola Mountain Research Watershed (PMRW) near Atlanta, Georgia. Concentrations of major solutes were measured in ground water samples from 19 shallow wells completed in the riparian (saprolite) aquifer and in one borehole completed in granite, and the apparent age of each sample was calculated from chloroflourocarbons and tritium/helium‐3 data. Concentrations of SiO2, Na+, and Ca2+ generally increased downvalley and were highest in the borehole near the watershed outlet. Strong positive correlations were found between the concentrations of these solutes and the apparent age of ground water that was modern (zero to one year) in the headwaters, six to seven years midway down the valley, and 26 to 27 years in the borehole, located ∼500 m downstream from the headwaters. Mass‐balance modeling of chemical evolution showed that the downstream changes in ground water chemistry could be largely explained by weathering of plagioclase to kaolinite, with possible contributions from weathering of K‐feldspar, biotite, hornblende, and calcite. The in situ rates of weathering reactions were estimated by combining the ground water age dates with geochemical mass‐balance modeling results. The weathering rate was highest for plagioclase (∼6.4 μmol/L/year), but could not be easily compared with most other published results for feldspar weathering at PMRW and elsewhere because the mineral‐surface area to which ground water was exposed during geochemical evolution could not be estimated. However, a preliminary estimate of the mineral‐surface area that would have contacted the ground water to provide the observed solute concentrations suggests that the plagioclase weathering rate calculated in this study is similar to the rate calculated in a previous study at PMRW, and three to four orders of magnitude slower than those published in previous laboratory studies of feldspar weathering. An accurate model of the geochemical evolution of riparian ground water is necessary to accurately model the geochemical evolution of stream water at PMRW.
Mixing of Hillslope, River, and Alluvial Ground Waters in Lowland Floodplains
Authors: Claxton Amanda J. , Bates Paul D. , Cloke Hannah L.
Published: March 2006

In this paper, we develop and apply a two‐dimensional flow and transport model to simulate the mixing of variously sourced water within a fluvial floodplain during one in‐bank and one out‐of‐bank flood event. The model is applied to two 120 m long transects through the floodplain of the River Severn, Shropshire, United Kingdom, which run to the river from the hillslope bordering the floodplain. For this site, hourly piezometric, river stage, and rainfall data are used to parameterize and validate the flow component of the model. Simulation of the movement of hypothetical conservative tracers driven by these hydrodynamic conditions is then undertaken to confirm and refine an evolving conceptual model of floodplain hydrology. This is based on the bank storage concept, and extended to include the impact of hillslope contributions to the floodplain/riparian zone and the impact of out‐of‐bank inundation on subsurface flow processes. The paper demonstrates that the role of the unsaturated zone has been underestimated in our previous investigations at this site and, in addition, that there is a potentially high residence time for solutes which remain in the unsaturated zone at the end of the flood event. In general, flood events in lowland plain systems are shown to be times of great hydrological and chemical activity. Lastly, the results confirm the complexity of interactions between surface and ground water flows in lowland plain settings and highlight the need for correct treatment of both dynamic boundary conditions and unsaturated zone processes.
The Significance of Ground Water to the Accumulation of Iron and Manganese in the Sediments of Two Hydrologically Distinct Lakes in North‐Central Minnesota: A Geological Perspective
Authors: Dean Walter E. , Neff Brian P. , Rosenberry Donald O. , Winter Thomas C. , Parkhurst Renee
Published: March 2006

Williams and Shingobee lakes are at opposite ends of the local ground water flow system in the Shingobee River Headwaters Area (SRHA) in north‐central Minnesota. Williams Lake, situated near the highest point in the flow system, has no surface inlet or outlet, and ground water and precipitation are the only sources of water. Shingobee Lake, situated at the lowest point in the flow system, has the Shingobee River as an inlet and outlet. Ground water directly contributes an estimated one‐fourth of the water input to Shingobee Lake. The Shingobee River also receives large amounts of ground water discharge along its reach to Shingobee Lake providing a large, indirect source of ground water to the lake. Differences in nutrient concentrations reflect the residence times and nutrient supplies of these two lakes. The average phosphorus content of Shingobee Lake is about twice that of Williams Lake. Consequently, phy‐toplankton productivity in Shingobee Lake is much higher than in Williams Lake, leading to an oxygen‐deficient (<1 ppm dissolved oxygen) hypolimnion within a month after overturn in both the spring and fall. Because of the extreme reducing conditions in the hypolimnion of Shingobee Lake, high concentrations of dissolved iron and manganese are present there during summer stratification. In some years, the manganese concentration in the hypolimnion of Shingobee Lake remains high throughout the year. Precipitation of iron and manganese minerals, presumed to be X‐ray amorphous oxyhydroxides, at periods of fall and spring overturn result in concentrations of iron and manganese in surface sediments of Shingobee Lake that are seven times and 27 times higher, respectively, than can be explained by contributions of iron and manganese from detrital aluminosilicates. These findings indicate that the source and amounts of this excess iron and manganese found in the sediments are correlated to the amount of iron‐ and manganese‐rich ground water discharging to Shingobee Lake. Because iron and manganese oxyhydroxides are efficient adsorbers of phosphorus, concentrations of phosphorus are also high in the sediments of Shingobee Lake. Without this sequestration of phosphorus, the productivity of Shingobee Lake would probably be much higher.
Shallow Water Table Fluctuations in Relation to Soil Penetration Resistance
Authors: Shanley James B. , Hjerdt K. Niclas , McDonnell Jeffrey J. , Kendall Carol
Published: March 2006

Hydrologic modeling of catchments is frequently hampered by lack of information on subsurface stratigraphy and zones of preferred flow. We evaluated the usefulness of soil penetration resistance, easily measured by a dynamic cone penetrometer, together with measurements of ground water level fluctuations, as a cost‐effective means to infer subsurface flow patterns. At our field site at Sleepers River, Vermont, penetration resistance was lowest in the surfi‐cial 10 to 30 cm, then typically increased to a local maximum at 60 to 80 cm, which we interpreted as the soil/till interface. Below this depth usually lies a zone of decreased resistance in the till, giving way to either a gradual or abrupt increase in resistance toward the bedrock surface at 1 to 4.5 m depth. Penetration resistance had a weak but significant negative correlation with saturated hydraulic conductivity determined by bail tests (r2= 0.25, p < 0.05). At many wells, monthly ground water levels tended to cluster at or just above the resistant zone near the soil/till interface. Chemical and isotopic dynamics in nested wells finished above and below the resistant zone suggest that the zone may temporarily isolate the deeper ground water reservoir from meltwater inputs, which were clearly identified by low δ18O values. In ground water discharge zones, δ18O values tended to converge throughout the profile. In contrast, dissolved organic carbon (DOC) maintained a gradient of increasing concentration toward land surface, even in otherwise well‐mixed waters, reflecting its rapid release from organic horizons. Understanding the effect of soil penetration resistance on ground water behavior may be useful in future catchment modeling efforts.
Estimating Ground Water Yield in Small Research Basins
Authors: Verry Elon S.
Published: March 2006

An analysis of ground water recharge in 32 small research watersheds shows the average flow of ground water out of the watershed (deep seepage) is 45% of streamflow and ranges from 8 to 350 mm/year when apportioned over the watershed area. It is time to meld ground water and small watershed science. The use of well networks and the evaluation of ground water well hydrographs or the use of ground water models to estimate deep seepage from small research basins is highly recommended. Future investigators are now armed with better tools necessary to estimate all the water and nutrients and have no need to quietly assume deep seepage is zero.
Ecological Consequences of Ground Water Discharge to Delaware Bay, United States
Authors: Miller Douglas C. , Ullman William J.
Published: March 2006

Submarine ground water discharge to the ocean has the potential to create estuarine conditions near the point of discharge, thereby dramatically altering local benthic habitats and ecology. Aerial thermal infrared imaging along the southwestern margin of Delaware Bay indicated abundant discharge at Cape Henlopen, Delaware, adjacent to the Atlantic Ocean. On the sandflat there, we have documented low salinity in sedimentary pore waters within 20 m of the beachface that are associated with dense assemblages (in thousands per square meter) of a deep, burrow‐dwelling polychaete worm, Marenzelleria viridis, otherwise regarded as a species characteristic of fresher, oligohaline conditions. Where present, M. viridis is a numerical and biomass dominant in a benthic community strikingly different from that in nearby nonseep locations. At Cape Henlopen, the ecological role of the ground water discharge appears to be a multifaceted one. Seeps are localized regions of significantly reduced salinity, stabilized temperature, increased nutrient flux, high microalgal abundance, and enhanced sediment stability. M. viridis feeds on sediment diatoms and may provide an important trophic linkage between microalgal growth fueled by nutrients associated with the discharging ground water and worm‐feeding predators such as bottom fish or shorebirds common on the Cape Henlopen sandflat. Calculations based on our sampling suggest that nutrients supplied by the ground water substantially exceed what is needed to support benthic biomass and productivity estimated for this site.
Tidal Effects on Ground Water Discharge Through a Sandy Marine Beach
Authors: Urish Daniel W. , McKenna Thomas E.
Published: March 2006

Tidal fluctuations along the salt water boundary of a sandy beach affect the magnitude, location, timing, and salinity of both subaerial and submarine ground water discharge. Detailed studies of shoreline discharge from an unconfined aquifer at two sites in an embayment on the Cape Cod, Massachusetts, coastline provide insight into the highly dynamic spatial and temporal nature of discharge along sandy beaches affected by the tide. The constantly moving tidal boundary over a sloping beach results in a shoreline‐perpendicular discharge zone of 10 to 20 m, with ∼35% to 55% of the discharge being submarine discharge. The distribution of fresh ground water through a beach face varies greatly, depending primarily on the tidal cycle and range, the heterogeneous characteristics of the beach sediments, and the beach geometry. The estimated relative volume of discharge varies temporally with tidal fluctuations, with the greatest discharge occurring during early to mid ebbing tide and location of greatest estimated discharge moving seaward during ebbing tide. This is determined using net hydraulic head calculations in monitoring wells set in a shoreline‐perpendicular transect in the beach. The salinity of discharge varies temporally from near fresh water values of 1 part per thousand (ppt) to near coastal salt water values of 30 ppt, being saltiest at the start of discharge as the tide ebbs and freshest during a low tide period of ∼2 h. Of the discharge volume, ∼65% to 85% is estimated to be from salt water that infiltrates during high tide episodes. This study highlights the complexity of the dynamic coastal ground water discharge phenomenon and provides insight into the hydraulic mechanisms involved. While there is a general pattern to sandy beach discharge, comparison of results from beaches studied at Cape Cod indicates that the temporal and spatial details of the discharge is very site‐specific.
Submarine Ground Water Discharge and Salt Penetration Across the Sea Floor
Authors: Bokuniewicz Henry , Pollock Meagen , Blum John , Wilson Robert
Published: March 2006

Fresh ground water entering an estuary can be mixed with salt water in the upper few decimeters of the sediment. As a result, net measured discharge rates at the sediment‐water interface can be equal to the volume discharge of fresh ground water, although the salinity of the escaping water is high. Benthic chambers, vented to a collection bag, were used to measure specific volume discharge rates over ∼5 cm/day near the shoreline of a wide, shallow lagoon—Great South Bay, New York—situated at the surface of a coastal plain aquifer. These rates decreased to 1.5 cm/day at a distance of 100 m from shore. Although the flow rate is expected to be inversely correlated to the tidal water level elevation, and has been shown to be so modulated at other sites, no consistent variation in discharge with tidal phase was found; the tidal range (25 cm) may have been too small to have a measurable effect. Water collected at a particular location freshened over time from 30 to 23 ppt in 12 hours. Piezometers recorded vertical hydraulic gradients (at ambient salinity) between 0.08 and 0.02 in the upper meter of the sediment and the vertical hydraulic conductivity was measured by a falling head test to be between 1 and 20 m/day. The discharge rates calculated by Darcy's law decreased offshore from dozens of cm/day within 10 m of shore to 1.8 cm/day at a distance of 100 m, consistent with measured seepage rates. Conductivity measurements imply that pore water salinity decreases from ambient bay values at the sea floor to near fresh water values at a depth of 0.6 m into the sediment. The vertical downward dispersion coefficient for salt was estimated to be 0.02 m2/day. This could be due to the superposition of water wave‐induced dispersion in the sediment with gravitational convection (salt fingering).
Tidal Load and Salt Water Influences on Submarine Ground Water Discharge
Authors: Paulsen Ronald J. , O'Rourke Daniel , Smith Christopher F. , Wong Teng‐Fong
Published: March 2006

Field measurements were conducted to characterize the influences of salt water and tidal loading on submarine ground water discharge (SGD) into West Neck Bay on Shelter Island, New York. SGD was continuously recorded at three sites using an ultrasonic ground water seepage meter, and the spatial extents of the terrestrially derived SGD and the salt water/fresh water mixing zone were inferred from electrical conductivity profiling. While SGD increases with increasing hydraulic gradient in the far field of the coastal aquifer, shorter temporal variations of SGD were inversely correlated with tidal stage. SGD and hydraulic heads in the onshore unconfined aquifer near the coast responded asymmetrically to tidal loading, with discharge and head increasing faster than decreasing. A time lag of ∼1 h was observed between the tidal load and responses in onshore head and SGD. This lag represents a manifestation of the travel time required for tidal influences to propagate landward before the hydraulic gradient adjusts and influences seepage. The spatial extent of the fresh water component of SGD determined by electrical conductivity profiles, seepage velocity, and the time lag between tide and SGD amplitudes are in reasonable agreement with analytic estimates.
Ground Water Beneath Coastal Bays of the Delmarva Peninsula: Ages and Nutrients
Authors: Bratton John F. , Böhlke John Karl , Manheim Frank T. , Krantz David E.
Published: March 2006

To complement a large‐scale geophysical investigation of occurrence and discharge of fresh water beneath Delaware, Maryland, and Virginia (Delmarva) coastal bays, we measured (1) salinity and nutrient concentrations in ground water samples from several offshore coring sites and (2) a suite of chemical and isotopic parameters, including age tracers, in ground water samples from a Delaware site. Samples were collected in a variety of Holocene and Plio‐Pleistocene sediments in nearshore and offshore areas of the bays. Ground waters that were significantly fresher than overlying waters were found in plumes up to at least 15 m thick extending to more than 500 m offshore in some areas. Steep salinity and nutrient gradients occur within a few meters of the sediment surface in most locations studied. The zone of transition from deeper fresher waters to shallower brackish waters is generally thin near shore, but thickens and becomes more gradual offshore. Ground water ages at the Delaware site were mostly < 50 yr in both fresh waters and brackish waters up to 22 m below the bay bottom. Water chemistry and age data indicate that fresh water plumes beneath the estuary are active extensions of the surficial aquifer carrying nitrate from recharge areas on land, whereas brackish ground water surrounding the fresh water plumes is recharged beneath the estuary and contains ammonium and phosphate released by diagenesis of shallow estuarine sediments. Denitrification affects some of the fresh water nitrate before it mixes with brackish ground water or discharges to surface water.
Septic Tank Impacts on Ground Water Quality and Nearshore Sediment Nutrient Flux
Authors: Reay William G.
Published: March 2006

Field studies were conducted at three coastal plain sites to characterize inorganic nutrient and fecal coliform bacteria ground water quality and intertidal sediment nutrient fluxes under the influence of residential septic tank effluent. Mean drainfield DIP (dissolved inorganic phosphorus) and DIN (dissolved inorganic nitrogen) concentrations varied between 294 to 336 and 4494 to 5391 μmol/L, respectively, with mean fecal coliform bacteria densities ranging from 105.04 to 106.29 MPN (most probable number) /100 mL. DIP and fecal coliform bacteria exhibited a high degree of attenuation with shoreline concentrations at or near background levels. In contrast, septic tank nitrogen loadings to shallow ground water were significant and resulted in mean shoreline DIN concentrations ∼50 to 100 times greater than adjacent surface water concentrations. Mean site sediment DIP and DIN flux to surface waters varied from 1.1 to 1.6 and 52 to 135 μmol/m2/hr, respectively. Whereas DIP sediment fluxes were similar to reported values for sites adjacent to forested and agricultural lands, DIN fluxes were elevated compared to forested lands and near the lower end of the range reported for agricultural lands within the southern Chesapeake Bay region. Maximum measured sediment DIN flux was 1514 μmol/m2/hr. Estimated waste water nitrogen loading to shallow ground water (5.7 to 10.7 kg/household/yr) was significant and with 0.5 to 1 acre lot sizes, comparable to water table nitrogen loadings from dominant row‐crop land use in the mid‐Atlantic Coastal Plain. Given the trends in population growth in the Chesapeake Bay watershed and other coastal regions, nitrogen loads from septic tanks to these systems should also be expected to increase.