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Water Data (water + data)
Selected AbstractsPelagic and benthic net production of dissolved inorganic carbon in an unproductive subarctic lakeFRESHWATER BIOLOGY, Issue 3 2007JAN ĹBERG Summary 1. Both the pelagic and benthic net dissolved inorganic carbon (DIC) productions were measured in situ on four occasions from June to September 2004, in the unproductive Lake Diktar-Erik in subarctic Sweden. The stable isotopic signal (,13C) of respired organic material was estimated from hypolimnion water data and data from a laboratory incubation using epilimnion water. 2. Both pelagic and benthic habitats were net heterotrophic during the study period, with a total net DIC production of 416 mg C m,2 day,1, of which the pelagic habitat contributed approximately 85%. The net DIC production decreased with depth both in the pelagic water and in the sediments, and most of the net DIC production occurred in the upper water column. 3. Temporal variations in both pelagic and benthic DIC production were small, although we observed a significant decrease in pelagic net DIC production after the autumn turnover. Water temperature was the single most important factor explaining temporal and vertical variations in pelagic DIC production. No single factor explained more than 10% of the benthic net DIC production, which probably was regulated by several interacting factors. 4. Pelagic DIC production, and thus most of the whole-lake net production of DIC, was mainly due to the respiration of allochthonous organic carbon. Stable isotope data inferred that nearly 100% of accumulated DIC in the hypolimnion water had an allochthonous carbon source. Similarly, in the laboratory incubation using epilimnion water, c. 85% of accumulated DIC was indicated to have an allochthonous organic carbon source. [source] Monitoring Subsurface Contamination Using Tree BranchesGROUND WATER MONITORING & REMEDIATION, Issue 1 2007Gayathri Gopalakrishnan This paper proposes a method of assessing the distribution of chlorinated solvents in soil and ground water using tree branches. Sampling branches is a potentially more cost-effective and easier method than sampling tree cores, with less risk of damage to the tree. This approach was tested at Argonne National Laboratory, where phytoremediation is being used to remove tetrachloroethene (PCE), trichloroethene (TCE), and carbon tetrachloride (CCl4) from soil and ground water. The phytoremediation system consists of shallow-rooted willows planted in an area with contaminated soil and deep-rooted poplars planted in an area with clean soil and contaminated ground water. Branch samples were collected from 126 willows and 120 poplars. Contaminant concentrations from 31 soil borings and six monitoring wells were compared to those from branches of adjacent trees. Regression equations with correlation coefficients of at least 0.89 were obtained, which were found to be chemical specific. Kriged profiles of TCE concentration based on soil and willow branch data were developed and showed good agreement. Profiles based on ground water data could not be developed due to lack of sufficient monitoring wells for a meaningful statistical analysis. An analytical model was used to simulate TCE concentrations in tree branches from soil concentrations; the diffusion coefficient for TCE in the tree was used as the fitting parameter and the best-fit value was two orders of magnitude greater than literature values. This work indicates that tree branch sampling is a useful approach to assess contaminant distribution and potentially to determine where to locate monitoring wells or perform detailed soil analysis. Further research is necessary prior to using this method as a quantitative monitoring tool for soil and ground water. [source] Holocene climate change in the eastern Mediterranean region: a comparison of stable isotope and pollen data from Lake Gölhisar, southwest Turkey,JOURNAL OF QUATERNARY SCIENCE, Issue 4 2007Warren J. Eastwood Abstract Stable isotope and pollen data from Gölhisar Gölü, a small intramontane lake located in southwest Turkey, provide complementary records of Holocene climate change. Modern oxygen and hydrogen isotope water data are used as a means of comparing present-day isotope composition of the lake water to the past oxygen isotope composition of the lake water as calculated from 18O/16O ratios in calcite precipitated in the summer months. Despite the lake system being chemically dilute, the modern isotope data clearly establish that the lake water is evaporated in relation to its spring input, suggesting that the palaeo data can be interpreted primarily in terms of changing precipitation/evaporation ratios. ,18O and ,13C values from authigenic calcite through the Holocene show predominantly negative values indicating climatic conditions wetter than today. Particularly notable are low (depleted) isotope values during the earliest Holocene (ca. 10,600,8800 cal. yr. BP), a period for which pollen data imply drier conditions than at present. This divergence between pollen-inferred and stable isotope palaeoclimate data is found in other east Mediterranean lake sediment records, and suggests that vegetation may have taken several millennia to reach climatic equilibrium at the start of the Holocene. Isotopic fluctuations during the early-to-mid Holocene (8800,5100 cal. yr. BP) suggest oscillations between aridity and humidity. Higher ,18O and ,13C values for the second half of the Holocene indicate generally drier conditions than during the period before ca.5100 cal. yr BP although there is some evidence for increased humidity coinciding with pollen evidence for increasing human impact and intensification of agriculture, notably during the so-called Bey,ehir Occupation Phase (Classical and early Byzantine periods). The modern trend towards aridity started about 1300 yr ago. Copyright © 2006 John Wiley & Sons, Ltd. [source] Surface water balance to evaluate the hydrological impacts of small instream diversions and application to the Russian River basin, California, USAAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 3 2009Matthew J. Deitch 1.Small streams are increasingly under pressure to meet water needs associated with expanding human development, but the hydrologic and ecological effects are not commonly described in scientific literature. 2.To evaluate the potential effects that surface water abstraction can have on flow regime, scientists and resource managers require tools that compare abstraction to stream flow at ecologically relevant time scales. 3.The classic water balance model was adapted to evaluate how small instream diversions can affect catchment stream-flow; the adapted model maintains the basic mass balance concept, but limits the parameters and considers surface water data at an appropriate timescale. 4.This surface water balance was applied to 20 Russian River tributaries in north-central California to evaluate how recognized diversions can affect stream flow throughout the region. 5.The model indicates that existing diversions have little capacity to influence peak or base flows during the rainy winter season, but may reduce stream flow during spring by 20% in one-third of all the study streams; and have the potential to accelerate summer intermittence in 80% of the streams included in this study. 6.The surface water balance model may be especially useful for guiding river restoration from a hydrologic perspective: it can distinguish among streams with high diversion regimes that may require more than just physical channel restoration to provide ecological benefits, and can illustrate the extent to which changing the diversion parameters of particular water users can affect the persistence of a natural flow regime. 7.As applied to Russian River tributaries, the surface water balances suggest that reducing demand for stream flow in summer may be as important as physical channel restoration to restoring anadromous salmonids in this region. Copyright © 2009 John Wiley & Sons, Ltd. [source] | ||||||||||