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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 34 (1996), S. 0 
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Vertical profiles of tritium and nitrate pore-water concentrations were determined to ∼8 m depth across two loess hillslopes. Mean recharge fluxes, estimated from chloride mass balance, are 5–10 times larger at the mid- and toe-slope positions than at the top-slope; the magnitudes of the values compare reasonably with results from other methods. The tritium and nitrate profiles exhibit multiple peaks which indicate that piston flow is not the sole flow process in this system. Results of a simple 1-D mixing model suggest that infiltration-exfiltration cycles in zones of plant root activity explain the shallow tritium peaks. Deeper peaks result from preferential vertical and/or lateral flow. The importance of these dispersive processes is underlined by great dilution of observed tritium concentrations, relative to expected concentrations assuming piston flow. In this setting, chloride is useful as a recharge estimator while tritium and nitrate serve as tracers of landscape-scale water movement.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 364 (1993), S. 223-225 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] For biogenesis of CO2 to drive chemical weathering, there must be a respiring biological community and nutrients, particularly fixed (organic) carbon. Recent work suggests that respiration, and accompanying charging of percolating runoff with CO2 and major elements, commonly occurs in ...
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0428
    Keywords: Insulin-dependent diabetes mellitus ; blood pressure ; salt sensitivity ; plasma renin activity ; atrial natriuretic factor ; circadian blood pressure profile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In insulin-dependent diabetes mellitus (IDDM) elevated exchangeable sodium (Na) levels are found even in the absence of hypertension, but it is not known whether this is associated with increased sensitivity of blood pressure to sodium level. To clarify this issue we compared 30 patients with IDDM (19 without and 11 with microalbuminuria, i.e. more than 30 mg albumin/day) and 30 control subjects matched for age, gender and body mass index. The subjects were studied on the 4th day of a low-salt diet (20 mmol/day) under in-patient conditions and were subsequently changed to the same diet with a high-salt supplement, yielding a total daily intake of 220 mmol Na/day. Circadian blood pressure, plasma renin activity (PRA), plasma atrial natriuretic factor (p-ANF), plasma cyclic guanosine 5′-phosphate (p-cGMP) and urinary albumin were measured. The proportion of salt-sensitive subjects, i.e. showing increment of mean arterial pressure ≥ 3 mmHg on high-salt diet, was 43% in diabetic patients (50% of diabetic patients with and 37% without microalbuminuria) and 17% in control subjects (p〈0.05). Lying and standing PRA levels on low- or high-salt diet were significantly lower in diabetic patients than in control subjects. Salt-sensitive diabetic patients had significantly higher lying ANF on high-salt (38.7±4.2 pmol/l vs 20.1±2.3 pmol/l, p〈0.005) than on low-salt diet. The results suggest that (i) the prevalence of sodium sensitivity is high in IDDM (ii) sodium sensitivity is found even in the absence of nephropathy as indicated by albuminuria.
    Type of Medium: Electronic Resource
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