Quantitative Limits to Qualitative Engagements: GIS,Its Critics,and the Philosophical Divide∗

Heated exchanges between critical theorists and GIScientists over geographic information systems (GIS) in 1990s geography gave rise to calls for increased communication between critics and practitioners of the technology and most recently for “hybrid” qualitative–quantitative GIS practices. Although GIS scholars have successfully addressed mid-1990s critiques of the technology by developing a series of critical GIS practices that involve nuanced and reflexive deployments of GIS and assessments of its visual products, theoretical critiques of GIS remain fixated on the epistemological deficiencies of the technology. Despite references to loosening metaphysical tensions across the discipline, this difference in assessments reveals the discourses of critical-theoretic geography and GIScience to remain separated by a trenchant philosophical divide, across which ontological and epistemological commitments are inviolable. The inability to fully reconcile a critical–theoretic epistemology with the explicitly ontological metaphysics of GIS further complicates qualitative engagements with the technology by addressing a series of inconsistencies into GIS praxis arising from the quantitative limits to representation encountered in the formal universe of computing. The persistence of metaphysical tensions in critical engagements with the technology questions the degree to which qualitative methods can be seamlessly hybridized with the quantitative architectures of GIS.     

Wind-wave variability in a shallow tidal sea—Spectral modelling combined with neural network methods

In this paper the wind-wave variability in the tidal basins of the German Wadden Sea is modelled with combined numerical and neural-network (NN) methods. First, the wave propagation and transformation in the study area are modelled with the state-of-the-art third-generation spectral wave model SWAN. The ability of SWAN to accurately reproduce the phenomena of interest in nonstationary conditions governed by highly variable winds, water levels and currents is shown by comparisons of the modelled and measured mean wave parameters at four stations. The principal component analysis of the SWAN results is then used to reveal the dominating spatial patterns in the data and to reduce their dimensionality, thus enabling an efficient and relatively straightforward NN modelling of mean wave parameters in the whole study area. It is shown that the data produced with the approach developed in this work have statistical properties (discrete probability distributions of the mean wave parameters etc.) very close to the properties of the data obtained with SWAN, thus proving that this approach can be used as a reliable tool for wind wave simulation in coastal areas, complementary to (often computationally demanding) spectral wave models.     

A review of geochemical background concepts and an example using data from Poland

One of the most crucial issues of recent environmental sciences is the topic of background concentrations of elements and organic compounds in various abiotic and biotic systems. The relationship between natural and anthropogenically altered concentrations of chemical species is a question that involves many implications in the geosciences, environmental and biological sciences, toxicology, and other related disciplines. This is especially important when interpreting geochemical and biogeochemical anomalies of toxic elements and/or organic compounds in various media. To better understand the potential impact of hazardous substances in the environment, we must become more familiar with their spatial and temporal distribution and with their behavior under different physico-chemical and biotic conditions. This review presents an assessment of the geochemical background concept as used by various authors. Different assumptions and approaches to this topic are presented, including direct, statistical, and integrated methods. Based on the results derived from geochemical and biogeochemical studies performed in selected forest ecosystems of Poland, an integrated method is presented. As a consequence of data processing, a normal distribution of data points was obtained using an iterative 2σ-technique. This method of estimating geochemical background is feasible and can be used for setting environmental quality standards or for studying the impact of anthropogenic pollution sources on the environment.     

Rapid migration of heavy metals and <Superscript>137</Superscript>Cs in alluvial sediments,Upper Odra River valley,Poland

The studies presented explore post-depositional changes of zinc, cadmium, lead, manganese and ¹³⁷Cs distribution in alluvial sediments accumulated in the upper Odra River valley in southern Poland. The rate of these changes was estimated by comparing metal and ¹³⁷Cs distributions in four vertical alluvial profiles with a history of river pollution and sediment deposition. The untypical ¹³⁷Cs distribution with peaks in the surface 40–60 cm and lower down, even at a depth of 2.5 m in strata deposited before the beginning of nuclear tests in 1954, indicates rapid post-depositional migration of this isotope from the surface and its retention in lower, less permeable layers. Moreover, the highest concentrations of lead, zinc and cadmium were found at a depth of 4 m in sediments accumulated in the mid-nineteenth century in spite of the growth of industrialization and the pollution of the Odra River with heavy metals until the end of the twentieth century. The post-depositional changes in heavy metals and ¹³⁷Cs are rapid in comparison with the slow element migration usually observed in uninundated soils. This difference is explained by the frequent and easy infiltration of polluted river water into the gravelly and sandy sediments present in the profiles.     

Proton microprobe for chemical dating of monazite

Although quantitative chemical analysis by proton microprobe has become an established technique, it has been rarely applied to problems in the earth sciences. The method, having lower detection limit (better than 10 ppm for U, Th and Pb) and higher spatial resolution than electron microprobe (typically 1 μm vs 3 μm), can be successfully used in geology. Here, we present a procedure for the chemical dating of monazite, (REE)PO₄, by proton microprobe. The procedure is compared with electron probe microanalysis technique (EPMA).     

Provenance implications of Th–U–Pb electron microprobe ages from detrital monazite in the Carboniferous Upper Silesia Coal Basin, Poland

This paper reports the results of CHIME (chemical Th–U–Pb isochron method) dating of detrital monazites from Carboniferous sandstones in the Upper Silesia Coal Basin (USCB). A total of 4739 spots on 863 monazite grains were analyzed from samples of sandstone derived from six stratigraphic units in the sedimentary sequence. Age distributions were identified in detrital monazites from the USCB sequence and correlated with specific dated domains in potential source areas. Most monazites in all samples yielded ca. 300–320 Ma (Variscan) ages; however, eo-Variscan, Caledonian and Cadomian ages were also obtained. The predominant ages are comparable to reported ages of certain tectonostratigraphic domains in the polyorogenic Bohemian Massif (BM), which suggests that various crystalline lithologies in the BM were the dominant sources of USCB sediments.