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.     

Paleo-stratigraphic permeability anisotropy controls supergene mimetic martite goethite deposits

The Hamersley Basin in Western Australia is one of the world's largest iron ore-producing regions, hosting two types of ore in banded iron formations: the high-grade martite-microplaty haematite and the supergene martite-goethite ores. With the high-grade ores almost entirely mined in the last decade, the supergene ores have more recently become the dominant resource of interest. Consequently, understanding the genesis of these martite-goethite deposits is a critical step for exploration. Yet, although various models exist, there is still no consensus on how these mineral resources formed, complicating the prediction of resource volume and location. Here, we show that the paleo-stratigraphic permeability anisotropy (with higher permeability along strata than across) controls the supergene mimetic enrichment transport process and, subsequently, the mineralisation distribution. We introduce a flow model that implicitly represents strata with a potential function that orients the permeability tensor accurately. The numerical solver uses automatic mesh adaptivity to deliver robust solutions. By accurately reproducing the mineralisation patterns in specific deposits, we identify and quantify the paleo-water table level and permeability anisotropy ratio as the two main controlling parameters for the mineralisation distribution. These insights provide new timing constraints for the mineralisation and the physical process of iron enrichment, suggesting much more potential mineralisation volume in the paleo-reconstructed zones than previously anticipated. These flow models allow us to draw geological conclusions with few a priori assumptions required for the genetic model in which the transport component is dominant. The predictive power of this methodology will allow targeted drilling to narrow down the prospective areas and lower exploration costs. Furthermore, the methodology's generality applies to other commodities in sedimentary basins involving supergene processes and will improve our understanding of various genetic models.     

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.     

Twentieth century variability of surface humidity as the climate change indicator in Kraków (Southern Poland)

Air humidity is an element that plays an important role among meteorological processes within the atmosphere; however, the variety of humidity indices makes the global view of air moisture changes difficult. Long-term variability of air humidity in Kraków was examined by time-series (1901–2000) analysis of vapour pressure and saturation deficit values and their characteristic days with the background of temperature and saturated vapour pressure changes. Long-term variability of air humidity in Kraków has been visible above all in variations of saturation deficit. It should be connected with the contemporary temperature growth and the city development as the atmospheric water vapour content (described by vapour pressure) becomes relatively stable (with no significant tendencies). The parameter showed well-marked trends over the examined period. The growth of saturation deficit values predominated in the warm half of a year (above all in August: an increase in SD value by 3.0 hPa per century). Apart from atmospheric circulation variability, gradual rise in the number of inhabitants and higher development density contributed to the decline in the city’s air humidity; however, the causes of changes in air humidity should be also attributed to natural factors, mainly to variation of air circulation reinforced by the operation of anthropogenic factors. Using air humidity as the indicator, the results that confirm climatic fluctuations in central Europe in the twentieth century obtained earlier were verified and some new aspects of present climate change were given.     

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).     

Long-term inter-annual variability of a cyclonic gyre in the western Irish Sea

The western Irish Sea gyre (WISG) is a cyclonic baroclinic flow around a dome of stagnant water which develops each year during the heating season in the western Irish Sea. Research was carried out to determine long-term changes in the strength of stratification within WISG and associated changes in the gyre structure, circulation patterns and retentive properties. Model simulations were carried out for the 58-year period 1951-2008. The characteristics of the gyre were quantified by means of potential energy anomaly (PEA), measuring the strength of stratification, and total kinetic energy (KE), reflecting the strength of cyclonic circulation. Additionally, long-term changes in flushing rates within the gyre were assessed.Results show that stratification in the western Irish Sea consistently begins to develop in March, increases linearly from April till June, peaks at the beginning of July and remains at close to maximum level throughout the month of July, before a start of a sharp decline at the beginning of August. The strength of stratification is significantly correlated with averaged summer air temperatures and summer wind speeds. Trend analysis of PEA shows an increase in the stratification strength over the period considered; the increase of PEA peak value is accompanied by a shortening of the gyre duration and a delay in the timing of the peak value. There is also an increasing trend in the KE value, showing that the thermal stratification plays a crucial role in the hydrography of the region. Flushing analysis shows that the stronger the stratification the lower the residence time and thus the faster the removal of the material from the western Irish Sea. Residence time within WISG shortens on average by 8 days over the 58-year period.     

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.