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Water Sampling (water + sampling)
Selected AbstractsEvaluation of acute copper toxicity to larval fathead minnows (Pimephales promelas) in soft surface watersENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2005Eric J. Van Genderen Abstract The hardness-based regulatory approach for Cu prescribes an extrapolation of the toxicity-versus-hardness relationship to low hardness (,50 mg/L as CaCO3). Hence, the objective of the present research was to evaluate the influences of water quality on acute Cu toxicity to larval fathead minnow (Pimephales promelas) in low-hardness surface waters. Seasonal water sampling was conducted at 24 sites throughout South Carolina, USA, to determine the site-specific influences of soft surface-water conditions on acute Cu toxicity. Concurrent toxicity tests in laboratory water, matched for hardness and alkalinity (modified method), also were conducted to allow calculation of water-effect ratios (WERs). In addition, tests were conducted at recommended hardness levels (recommended method) for comparison of WER methodology in soft water. Surface-water conditions (average ± standard deviation, n = 53) were hardness of 16 ± 8 mg/L as CaCO3, alkalinity of 18 ± 11 mg/L as CaCO3, and dissolved organic carbon of 6 ± 4 mg/L. Dissolved Cu 48-h median lethal concentration (LC50) values varied nearly 45-fold across the dataset and greater than four-fold at individual sites. Spatial (p < 0.0001) and seasonal (p = 0.026) differences among LC50 values were determined for eight sites that had multiple toxicity results for one year. All modified WERs were greater than 1.0, suggesting that the site waters were more protective of Cu toxicity than the matched laboratory water. Some WERs generated using recommended methods were less than 1.0, suggesting limited site-specific protection. Based on these observations, extrapolation of the hardness-based equation for Cu at 50 mg/L or less as CaCO3 would adequately protect fathead minnow populations in soft surface waters. The WER results presented here demonstrate the inconsistency between hardness-based criteria and the methodology for deriving site-specific water-quality criteria in low-hardness waters. [source] Geothermal prognoses for tunnels in the Andes / . Geothermische Prognose für AndentunnelGEOMECHANICS AND TUNNELLING, Issue 5 2010Mag. Giorgio Höfer-Öllinger Geothermal energy - Geothermie; Reconnaissance - Baugrunderkundung; Hydrology - Hydrologie; Geology - Geologie Abstract Geothermal prognoses were carried out for two tunnel projects in the Andes, each running between Argentina and Chile. Different methods were applied in accordance with the different project phases. For the feasibility study of a 52 km long railway tunnel, hydrogeological mapping and hydrochemical analyses were carried out as well as isotope analyses on a thermal spring. An attempt to use silica and ionic solute geothermometers produced different results. For the central section of the tunnel temperatures are assumed to reach 50 to 70 °C and further investigations are recommended. The second tunnel project is now in the design phase. Two investigation phases have been completed including geological/ hydrogeological mapping, water sampling and analysis and core drilling. The geothermal gradient is well known from borehole temperature measurements. The thermal conductivity of the rocks was determined from core samples in a laboratory, and an average heat flow of approximately 100 mW/m2 was calculated. During the driving of the tunnel, temperatures of just over 50 °C are expected. Für zwei Tunnelvorhaben in den Anden, jeweils zwischen Argentinien und Chile, wurden geothermische Prognosen durchgeführt. Für verschiedene Projektphasen kamen entsprechend unterschiedliche Methoden zur Anwendung: Für eine Machbarkeitsstudie eines 52 km langen Eisenbahntunnels wurde eine Quellkartierung mit Probennahme durchgeführt sowie Isotopenanalytik an einer Thermalquelle. Ein Versuch, Geothermometer anhand der Lösungsfracht des Quellwassers zu verwenden, scheiterte. Für den zentralen Bereich des Tunnels werden Temperaturen von 50 bis 70 °C vermutet, weitere Erkundungen wurden empfohlen. Das zweite Tunnelvorhaben ist in der Planungsphase deutlich weiter. Neben Kartierungen liegen zwei Erkundungsphasen mit Kernbohrungen vor. Aus Bohrlochmessungen ist der geothermische Gradient bekannt, die Wärmeleitfähigkeit der Gesteine wurde anhand von Bohrkernen im Labor ermittelt. Es konnte ein durchschnittlicher Wärmefluss von etwa 100 mW/m2 errechnet werden, für den Tunnelvortrieb werden Gebirgstemperaturen von maximal knapp über 50 °C erwartet. [source] Identifying migratory contingents of fish by combining otolith Sr:Ca with temporal collections of ambient Sr:Ca concentrationsJOURNAL OF FISH BIOLOGY, Issue 3 2006T. S. Elsdon Ambient strontium:calcium (Sr:Ca) concentrations were determined at the temporal scales of months, weeks and days, in summer and winter at two estuarine sites, and experimentally derived correlations between ambient and otolith Sr:Ca were used to estimate the otolith Sr:Ca concentrations of ,resident' black bream Acanthopagrus butcheri. Wild black bream were collected in summer and winter at the end of the temporal water sampling, and their otolith Sr:Ca concentrations were examined. Wild fish were classified as ,resident' if their otolith Sr:Ca matched the predicted concentrations of resident fish, and ,migrant' if this did not occur. In winter, all fish were classified as resident. In summer, all fish were classified as migrants, with fish spending an average of only 16·8% (estuary 1) and 61·1% (estuary 2) of their time at each estuarine location. [source] Non-disturbing characterization of natural organic matter (NOM) contained in clay rock pore water by mass spectrometry using electrospray and atmospheric pressure chemical ionization modesRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 2 2010Sandrine Huclier-Markai We have investigated the composition of the mobile natural organic matter (NOM) present in Callovo-Oxfodian pore water using electrospray ionization mass spectrometry (ESI-MS), atmospheric pressure chemical ionization mass spectrometry (APCI-MS) and emission-excitation matrix (EEM) spectroscopy. The generation of knowledge of the composition, structure and size of mobile NOM is necessary if one wants to understand the interactions of these compounds with heavy metals/radionuclides, in the context of environmental studies, and particularly how the mobility of these trace elements is affected by mobile NOM. The proposed methodology is very sensitive in unambiguously identifying the in situ composition of dissolved NOM in water even at very low NOM concentration, due to innovative non-disturbing water sampling and ionization (ESI/APCI-MS) techniques. It was possible to analyze a quite exhaustive inventory of the small organic compounds of clay pore water without proceeding to any chemical treatment at naturally occurring concentration levels. The structural features observed were mainly acidic compounds and fatty acids as well as aldehydes and amino acids. Copyright © 2009 John Wiley & Sons, Ltd. [source] The effect of the introduction of Nile tilapia (Oreochromis niloticus, L.) on small indigenous fish species (mola, Amblypharyngodon mola, Hamilton; chela, Chela cachius, Hamilton; punti, Puntius sophore, Hamilton)AQUACULTURE RESEARCH, Issue 6 2010Sultanul Arafin Shemeen Ahmad Abstract This is the first controlled experiment to quantify the effect of introduced tilapia on indigenous species. This experiment was conducted in small earthen ponds (100 m2) to assess the impact of mixed-sex or all-male Nile tilapia (Oreochromis niloticus) on small indigenous species (SIS) commonly found in south Asia, mola (Amblypharyngodon mola), chela (Chela cachius) and punti (Puntius sophore). Ponds were fertilized, then stocked with 0.56 fish m,2 of water surface area in the mixed-sex and all-male tilapia treatments and 0.42 fish m,2 in the treatment without tilapia. No additional nutritional inputs were applied after stocking. Treatments were: mixed-sex tilapia with SIS, mono-sex male tilapia with SIS and SIS without tilapia (control). All treatments were stocked with 14 fish per species. All species reproduced during the 21-month culture duration. The number of recruits varied by species, Tilapia reproduced in greater numbers than SIS. Tilapia numbers at harvest were the highest (451 ± 25/100 m2) in the mixed-sex treatment compared with mola (221 ± 22/100 m2), chela (94 ± 8/100 m2) and punti (100 ± 7/100 m2). The number of mola was higher (399 ± 33/100 m2) in the all-male tilapia treatment. There was reduction in the number of mola and chela in the treatment containing mixed-sex tilapia. Gut content analysis combined with water sampling revealed that all fish species fed selectively. Significant interspecies dietary overlap was found between Nile tilapia and SIS and among SIS. Thus, there is potential for tilapia to compete with indigenous fish species when space and other resources are limiting, but a longer duration study with varying level of management is needed to determine how successfully tilapia competes with locally adapted SIS. [source] | ||||||||||