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  • 1
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: The growth of cultivation (strawberries and citrus fruits) in the coastal region of the Huelva province of Spain in the last 10 years has meant an increase in the demand of water from the Ayamonte-Huelva aquifer system. It has also meant the introduction of an excess of nitrogen via fertilizers from farming.The system now has two problems: salt-water intrusion in the southern sector (González and Romero, 1991; González, 1992); and a general increase in the nitrate content in the saturated zone. This second problem has led to average concentrations of nitrates in the aquifer above potable limits (50 ppm), reaching local values near to 400 ppm of NO3-(González and Romero, 1991; Grande et al., 1993).This paper delineates the sphere of influence of the two factors being considered (salt-water intrusion and agricultural contamination) on the different variables studied. The proximity between both factors is justified for each of the contaminating processes.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 439-447 
    ISSN: 0268-2605
    Keywords: high-performance liquid chromatography ; hydride generation ; atomic fluorescence spectrometry ; photo-oxidation ; arsenic speciation ; human urine ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The potential of coupling anion-exchange high-performance liquid chromatography, hydride generation and atomic fluorescence spectrometry (HPLC-HG-AFS) for arsenic speciation is considered. The effects of hydrochloric acid and sodium tetrahydroborate concentrations on signal-to-background ratio, as well as argon and hydrogen flow rates, were investigated. Detection limits for arsenite, dimethylarsinic acid (DMA), monomethylarsonic acid (MMA) and arsenate were 0.17, 0.45, 0.30 and 0.38 μg l-1, respectively, using a 20-μl loop. Linearity ranges were 0.1-500 ng for As(III) and MMA (as arsenic), and 0.1-800 ng for DMA and As(V) (as arsenic). Arsenobetaine (AsB) was also determined by introducing an on-line photo-oxidation step after the chromatographic separation. In this case the limits of detection and linear ranges for the different species studied were similar to the values obtained previously for As(V). The technique was tested with a human urine reference material and a volunteer's sample. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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