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  • kriging  (5)
  • pH  (5)
  • Springer  (10)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of bioenergetics and biomembranes 20 (1988), S. 571-584 
    ISSN: 1573-6881
    Keywords: (Na+ + K+)-ATPase ; 3-O-methylfluorescein phosphate ; nitrophenyl phosphate ; dimenthyl sulfoxide ; Pi ; pH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract With 3-O-methylfluorescein phosphate (3-OMFP) as substrate for the phosphatase reaction catalyzed by the (Na+ + K+)-ATPase, a number of properties of that reaction differ from those with the common substratep-nitrophenyl phosphate (NPP): theK m is 2 orders of magnitude less and the Vmax is two times greater, and dimethyl sulfoxide (Me2SO) inhibits rather than stimulates. In addition, reducing the incubation pH decreases both theK m and Vmax for K+-activated 3-OMFP hydrolysis as well as theK 0.5 for K+ activation. However, reducing the incubation pH increases inhibition by Pi and the Vmax for 3-OMFP hydrolysis in the absence of K+. When choline chloride is varied reciprocally with NaCl to maintain the ionic strength constant, NaCl inhibits K+-activated 3-OMFP hydrolysis modestly with 10 mM KCl, but stimulates (in the range 5–30 mM NaCl) with suboptimal (0.35 mM) KCl. In the absence of K+, however, NaCl stimulates increasingly over the range 5–100 mM when the ionic strength is held constant. These observations are interpreted in terms of (a) differential effects of the ligands on enzyme conformations; (b) alternative reaction pathways in the absence of Na+, with a faster, phosphorylating pathway more readily available to 3-OMFP than to NPP; and (c) a (Na+ + K+)-phosphatase pathway, most apparent at suboptimal K+ concentrations, that is also more readily available to 3-OMFP.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of paleolimnology 12 (1994), S. 103-154 
    ISSN: 1573-0417
    Keywords: acidification ; alkalization ; pH ; alkalinity ; diatoms ; sediment chemistry ; New England ; catchment effects ; land use ; logging ; acidic deposition ; air pollutants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Studies of sediment cores from 12 acidic lakes in granitic, forested and uninhabited catchments in northern New England, U.S.A. produced diatom-inferred pH (IpH) 5.2 to 5.8 and alkalinity (Ialk) −12 to 31 µeq l−1, with slowly declining values at some lakes, for one to four centuries prior to logging. Increases of IpH (Δ0.05 to 0.60) and Ialk (Δ5 to 40 µeq l−1) correlate with logging in the catchments in the early-1800s to early-1900s. Recovery to pre-logging IpH and Ialk correlates with forest succession toward conifers, and is completed in the late-1800s to mid-1900s. Beginning at 1915–1920 (4 lakes), 1930–1950 (4 lakes) and 1965–1970 (4 lakes), IpH and Ialk start decreasing below pre-logging values due to atmospheric acidic deposition, leading to respective total decreases of 0.10 to 0.45 (X=0.25) and 5 to 25 µeq l−1 (X=15). Inputs of anthropogenic Pb, Zn, V, polycyclic aromatic hydrocarbons, and soot from the atmosphere are first detectable in early- to late-1800s sediment, and Cu in late-1800s sediment, increase rapidly in the late-1800s to mid-1900s, and level off or decrease since the 1960s — partly due to emission controls. Decreasing Ca, Mn, and possibly Zn relative to other metals and normalized to organic content, and increasing flux of Fe to the lakes, indicate soil and water acidification after 1900.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 126 (1990), S. 237-246 
    ISSN: 1573-5036
    Keywords: Al3+ ; Ca2+ ; Mg2+ ; NH4 + ; NO3 − ; SO4 2− ; Al toxicity ; forest dieback ; Fagus sylvatica ; Nothofagus ; pH ; Picea abies ; soil solution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Concentrations of ions were measured in soil solutions from beech (Nothofagus) forests in remote areas of New Zealand and in solutions from beech (Fagus sylvatica) and Norway spruce (Picea abies) forests in North-East Bavaria, West Germany, to compare the chemistry of soil solutions which are unaffected by acid deposition (New Zealand) with those that are affected (West Germany). In New Zealand, soil solution SO4 2− concentrations ranged between 〈2 and 58 μmol L−1, and NO3 − concentrations ranged between 〈1 and 3 μmol L−1. In West Germany, SO4 2− concentrations ranged between 80 and 700 μmol L−1, and NO3 − concentrations at three of six sites ranged between 39 and 3750 μmol L−1, but was not detected at the remaining three sites. At all sites in New Zealand, and at sites where the soil base status was moderately high in West Germany, pH levels increased, and total Al (Alt) and inorganic monomeric Al (Ali) levels decreased rapidly with increasing soil depth. In contrast, at sites on soils of low base status in West Germany, pH levels increased only slightly, and Al levels did not decline with increasing soil depth. Under a high-elevation Norway spruce stand showing severe Mg deficiency and dieback symptoms in West Germany, soil solution Mg2+ levels ranged between 20 and 60 μmol L−, and were only half those under a healthy stand. Alt and Ali levels were substantially higher the healthy stand than under the unhealthy stand, indicating that Al toxicity was not the main cause of spruce decline.
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  • 4
    ISSN: 1573-5117
    Keywords: pH ; alkalinity ; indicators
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A series of laboratory and field studies were conducted to evaluate the reliability of colorimetric pH indicators in dilute, acidic surface waters in New England. Laboratory studies consisted of comparing colorimetric and electrometric pH results in synthetic solutions with a range of ionic strength and buffering capacity. Field studies involved simultaneous colorimetric and electrometric pH determinations in 52 New England lakes with differing water chemistry. Colorimetric indicators deviated from electrometric pH results at low alkalinities and near the end of their operating range. They agreed with electrometric values, within 0.2 unit, at alkalinities of 20 µeq 1-1 and greater, or near the center of their operating range. Changing ionic strength without changing buffering capacity did not affect results. When indicators were selected that bracketed sample pH, colorimetric determinations of pH in New England lakes agreed well with electrometric determinations.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 120 (1985), S. 69-87 
    ISSN: 1573-5117
    Keywords: diatoms ; lake acidification ; acidic precipitation ; paleolimnology ; pH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The pH history of lakes can be inferred from diatom remains in dated sediment cores. To derive transfer functions for pH inference in acidic lakes, we counted diatoms in surface-sediment from 31 soft-water lakes in n. New England (NE) and 36 in Norway (N), covering pH 4.4–7.1. Cluster analysis of each data set indicates that pH 6 is an upper limit for a group of similar diatom assemblages. For each set, we developed multiple linear regressions to relate three versions of the diatom data to pH of surface-waters: (1) relative frequencies of selected diatom taxa, (2) the first principal component (1 PC) of these frequencies, and (3) the frequencies of Hustedt pH groups. Also, simple linear regressions were developed for two versions: (1) Index B and (2) Index Alpha, both based on pH groups. Regressions were run separately for lakes with pH ≤ 6; these are most relevant for pH inference in acidic lakes. The best regressions (N: taxa & 1 PC taxa) have r2 0.69–0.91 and Se 0.24–0.31 pH units, the worst (NE: log alpha) have r2 0.27–0.57 and Se 0.51. In all cases, errors for NE are greater than N, partly due to greater diversity of NE lakes. Regressions based on pH groups (directly & by indices) have smaller r2 and larger Se than those based on taxa and 1 taxa. The Index Alpha is least useful because its requirement for alkaline diatom units is unsatisfied at many acidic lakes. Regressions based on taxa may give erratic pH inferences due to sensitivity to unusual frequencies of individual taxa; this effect is reduced by using 1 PC taxa. Four regressions based on pH ≤ 6 lakes were used for inferring pH in a 210Pb dated core from Nedre Målmesvatn, N (now pH 4.6). There is good agreement among three of the four (not for the regression based directly on taxa) that there has been a decrease of ca. 0.6 pH units starting in the late 1800's.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical geology 25 (1993), S. 925-936 
    ISSN: 1573-8868
    Keywords: basin analysis ; sedimentary basin ; hydrocarbon exploration ; probability ; multivariate classification ; kriging ; regionalization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract To estimate the undiscovered hydrocarbon potential of sedimentary basins, quantitative play assessments specific for each location in a region may be obtained using geostatistical methods combined with the theory of classification of geological objects, a methodology referred to as regionalization. The technique relies on process modeling and measured borehole data as well as probabilistic methods to exploit the relationship between geology (the “predictor”) and known hydrocarbon productivity (the “target”) to define prospective stratigraphic intervals within a basin. It is demonstrated in case studies from the oil-producing region of the western Kansas Pennsylvanian Shelf and the gas-bearing Rotliegend sediments of the Northeast German Basin.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical geology 27 (1995), S. 105-127 
    ISSN: 1573-8868
    Keywords: closed data ; log-ratio ; basis method ; oil field ; kriging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract A regionalized composition is a random vector function whose components are positive and sum to a constant at every point of the sampling region. Consequently, the components of a regionalized composition are necessarily spatially correlated. This spatial dependence—induced by the constant sum constraint—is a spurious spatial correlation and may lead to misinterpretations of statistical analyses. Furthermore, the cross-covariance matrices of the regionalized composition are singular, as is the coefficient matrix of the cokriging system of equations. Three methods of performing estimation or prediction of a regionalized composition at unsampled points are discussed: (1) the direct approach of estimating each variable separately; (2) the basis method, which is applicable only when a random function is available that can he regarded as the size of the regionalized composition under study; (3) the logratio approach, using the additive-log-ratio transformation proposed by J. Aitchison, which allows statistical analysis of compositional data. We present a brief theoretical review of these three methods and compare them using compositional data from the Lyons West Oil Field in Kansas (USA). It is shown that, although there are no important numerical differences, the direct approach leads to invalid results, whereas the basis method and the additive-log-ratio approach are comparable.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical geology 19 (1987), S. 91-98 
    ISSN: 1573-8868
    Keywords: geostatistics ; kriging ; conditional simulation ; fast Fourier transform
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract This paper reviews the turning band method and fast Fourier transform method of producing a nonconditional simulation of a multinormal random function with a given covariance structure. A review of the two common methods of conditioning the simulation to honor the data shows that they are formally equivalent. Another method for directly pondering a conditional simulation based on the LU triangular decomposition of the covariance matrix is presented. Computational and implementation difficulties are discussed.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical geology 16 (1984), S. 249-265 
    ISSN: 1573-8868
    Keywords: kriging ; moving neighborhood ; global neighborhood ; geostatistics ; automatic contouring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract The kriging estimator is usually computed in a moving neighborhood; only the data near the point to be estimated are used. This moving neighborhood approach creates discontinuities in mapping applications. An alternative approach is presented here, whereby all points are estimated using all the available data. To solve the resulting large linear system the kriging estimator is expressed in terms of the inverse of the covariance matrix. The covariance matrix has the advantage of being positive definite and the size of system which can be solved without encountering numerical instability is substantially increased. Because the kriging matrix does not change, the estimator can be written in terms of scalar products, thus avoiding the more time-consuming matrix multiplications of the standard approach. In the particular case of a covariance which is zero for distances greater than a fixed value (the range), the resulting banded structure of the covariance matrix is shown to lead to substantial computational savings in both run time and storage space. In this case the calculation time for the kriging variance is also substantially reduced. The present method is extended to the nonstationary case.
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  • 10
    ISSN: 1573-8868
    Keywords: linear equations ; kriging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract In mineral deposit evaluation, the estimation of block values can involve the solution of as many as 100,000 systems of linear equations. To minimize computing costs it is important that the program to solve the linear systems be as efficient as possible. Standard library routines tend to contain very general stable methods using pivoting and iteration to ensure high accuracy solutions. Here, a particular method has been developed that gives a substantial improvement in run time at the occasional expense of accuracy and stability. The method is not new—just a simple application of Gaussian elimination in the symmetric case.
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