Overbank sediment: a representative sample medium for regional geochemical mapping

Ottesen, Rolf Tore; Bogen, Jim; Bölviken, B.; Volden, Tore

doi:10.1016/0375-6742(89)90061-7

Cited by 142 publications

(58 citation statements)

References 11 publications

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“…Floodplain sediments have been widely used in geochemical surveys (the main aim of the present sampling exercise) because they are representative of the average regolith composition in a catchment (Ottesen et al 1989). Although this holds true for most geochemical compositional parameters of the sediments, inherited from the original lithologies from which they are derived through weathering and transport, a property such as soil pH is not expected to be influenced by provenance to such an extent.…”

Section: Background Methodologymentioning

confidence: 99%

The pH of Australian soils: field results from a national survey

2011

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Abstract. The pH is one of the fundamental soil properties governing nutrient availability, metal mobility, elemental toxicity, microbial activity, and plant growth. The field pH of topsoil (0-0.10 m depth) and subsoil (~0.60-0.80 m depth) was measured on floodplain soils collected near the outlet of 1186 catchments covering >6 Mkm 2 (6 Â10 12 m 2 ) or~80% of Australia. Field pH duplicate data, obtained at 124 randomly selected sites, indicate a precision of 0.5 pH unit (or 7%), and mapped pH patterns are consistent and meaningful. The median topsoil pH is 6.5, while the subsoil pH has a median of 7 but is strongly bimodal (6-6.5 and 8-8.5). In most cases (64%) the topsoil and subsoil pH values are similar; among the sites exhibiting a pH contrast, those with more acidic topsoils are more common (28%) than those with more alkaline topsoils (7%). The distribution of soil pH at the national scale indicates the strong controls exerted by precipitation and ensuing leaching (e.g. low pH along the coastal fringe, high pH in the dry centre), aridity (e.g. high pH where calcrete is common in the regolith), vegetation (e.g. low pH reflecting abundant soil organic matter), and subsurface lithology (e.g. high pH over limestone bedrock). The new data, together with existing soil pH datasets, can support regional-scale decision-making relating to agricultural, environmental, infrastructural, and mineral exploration decisions.

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Section: Background Methodologymentioning

confidence: 99%

The pH of Australian soils: field results from a national survey

2011

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“…Overbank sediments have been shown to be more representative of the geochemical composition of the catchment than stream sediments (Ottesen et al 1989). This is because the suspended sediment load in a flood event, from which the overbank or floodplain sediments are primarily derived, is sourced from a greater area than the sediments within the stream channel, which are typically derived from local point sources.…”

Section: Present Workmentioning

confidence: 99%

Catchment-based gold prospectivity analysis combining geochemical, geophysical and geological data across northern Australia

Cracknell

Caritat

2017

GEEA

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Abstract:The results of a pilot study into the application of an unsupervised clustering approach to the analysis of catchmentbased National Geochemical Survey of Australia (NGSA) geochemical data combined with geophysical and geological data across northern Australia are documented. NGSA Mobile Metal Ion® (MMI) element concentrations and first and second order statistical summaries across catchments of geophysical data and geological data are integrated and analysed using Self-Organizing Maps (SOM). Input features that contribute significantly to the separation of catchment clusters are objectively identified and assessed.A case study of the application of SOM for assessing the spatial relationships between Au mines and mineral occurrences in catchment clusters is presented. Catchments with high mean Au code-vector concentrations are found downstream of areas known to host Au mineralization. This knowledge is used to identify upstream catchments exhibiting geophysical and geological features that indicate likely Au mineralization. The approach documented here suggests that catchment-based geochemical data and summaries of geophysical and geological data can be combined to highlight areas that potentially host previously unrecognised Au mineralization.

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“…Stream sediments reflect rock structure of the catchment area, its geochemical characteristics and possible recent contamination upstream of the sampling point (OTTESEN et al, 1989). Snow represents natural collector and ideal medium for observation of dry or wet deposited atmospheric constituents, such as aerosol particles, which are well preserved in the snowcover as long as no melting occurs (SCHÖNER et al, 1997).…”

Section: Sample Preparation and Sem/eds Analysesmentioning

confidence: 99%

Application of SEM/EDS to environmental geochemistry of heavy metals

Gosar¹,

Miler²

2009

Geologija

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Heavy metals represent a ubiquitous constituent of the near-surface environment, present in widely varying concentrations that typically have little impact on human behaviour and health. However, the mining of metals and use of these metals in industrial processes has produced significant anthropogenic inputs of metals to both local and global environments. As such, a rigorous overview of the current accumulation of heavy metals and knowledge of mineralogy of heavy metal-bearing phases is important for understanding their stability, solubility, mobility, bioavailability and toxicity. These data are of fundamental importance for environmental risk assessment and evaluation of future scenarios. Since conventional geochemical analyses provide limited information, other analytical methods have to be utilized for the characterisation of heavy metal-bearing phases. Significant analytical method for identification and characterisation of heavy metals in environmental media is a scanning electron microscope coupled with energy dispersive X-ray spectrometer (SEM/EDS), an apparatus for qualitative and semi-quantitative chemical analysis at microne level, newly introduced to Geological Survey of Slovenia. Use of SEM/EDS was already introduced to environmental studies world-wide. In Slovenia, SEM/EDS analyses of environmental media were firstly carried out on the Meža River stream sediments and snow deposits from Ljubljana urban area.Heavy metal-bearing phases in the Meža River stream sediments were apportioned to three source areas: Mežica mining/smelting area (geogenic-technogenic origin), Ravne ironworks area (technogenic origin) and the Meža River catchment area (geogenic origin), which corresponds to data obtained by conventional geochemical and multivariate statistical methods.Airborne particles, identified in urban snow deposits, were interpreted as geogenic particles, represented by fragments of heavy metal-bearing minerals, and technogenic particles that originate from combustion of solid and liquid fuels, iron and steel melting processes and road traffic emissions.SEM/EDS proved to be a very useful analytical method for the study of heavy metal-bearing phases and characterisation according to their sources and genesis. Izvle~ekTežke kovine predstavljajo naravno navzo~e sestavine v Zemljini skorji in na njeni povr{ini, prisotne v zelo razli~nih koncentracijah. V splo{nem imajo majhen vpliv na zdravje ~loveka. Rudarjenje teh kovin in njihova uporaba v industriji pomembno prispevajo k antropogenemu vnosu kovin v okolje. Natan~en pregled obstoje~ih nakopi~enj težkih kovin v naravnih okoljih in poznavanje mineralnih faz, ki vsebujejo težke kovine je zatorej bistvenega pomena za opredelitev njihove stabilnosti, topnosti, mobilnosti, dostopnosti za živa bitja in toksi~nosti ter za oceno tveganja in napoved možnih scenarijev v prihodnosti. Ker obi~ajne geokemi~ne metode nudijo le omejene informacije, je potrebno za opredelitev faz težkih kovin uporabiti druge analiti~ne metode. Pomembna metoda za prepoznavanje in ...

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Overbank sediment: a representative sample medium for regional geochemical mapping

Cited by 142 publications

References 11 publications

The pH of Australian soils: field results from a national survey

The pH of Australian soils: field results from a national survey

Catchment-based gold prospectivity analysis combining geochemical, geophysical and geological data across northern Australia

Application of SEM/EDS to environmental geochemistry of heavy metals

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