Spatial Distribution Of As Research Articles

Heavy Metal Pollution of Surface Soil in the Thrace Region, Turkey

Samples of surface soil were collected at 73 sites in the Thrace region, northwest part of Turkey. Two complementary analytical techniques, epithermal neutron activation analysis (ENAA) and atomic absorption spectrometry (AAS) with flame and graphite furnace atomization were used to determine 35 elements in the soil samples. Concentrations of As, Cd, Co, Cu, Mn, Ni, Pb and Zn were determined using AAS and GF AAS, and ENAA was used for the remaining 27 elements. Results for As, Ba, Br, Ca, Cd, Ce, Co, Cr, Cs, Cu Eu, Fe, Hf, I, In, K, La, Mn, Mo, Na, Nd, Ni, Pb, Rb, Sb, Sc, Sm, Sr, Ta, Tb, Th, Ti, U, V and Zn are reported for the first time for soils from this region. The results show that concentrations of most elements were little affected by the industrial and other anthropogenic activities performed in region. Except for distinctly higher levels of Pb, Cu, Cd and Zn in Istanbul district than the median values for the Thrace region, the observed distributions seem to be mainly associated with lithogenic variations. Spatial distributions of As, Cd, Cr, Cu, Ni, Pb and Zn were plotted in relation to the concentration values in soil using Geographic Information System (GIS) technology.

Application of the micro-PIXE technique for analyzing arsenic in biomat and lower plants of lichen and mosses around an arsenic mine site, at Gunma, Japan

Microhabitats of bacteria (biomat) and lower plants, such as lichen and mosses, are known to accumulate hazardous elements. Since the concentration of hazardous elements in the environment is quite low, we have applied the in-air μ-PIXE (particle induced X-ray emission) system developed in the TIARA facility of JAERI, which has low concentration detection limit of ppm, to measure As, one of the hazardous elements, distributions in biomat, lichen and mosses observed around an abandoned As mine site in Gunma, Japan to elucidate the applicability of these biomat and lower plants as bio-indicators of As. Spatial distributions of As, Fe, Si and S in all biomat, lichen and moss collected within 3 m from the mine entrance indicate that As is localized, and is associated with silicate and Fe-containing compounds. In addition, the intensity ratio of peak area for As to Fe in μ-PIXE spectrum of the moss collected from the concrete wall at 3 m downstream of the mine water discharge position is different from those of the lower plants on the rock near the closed entrance, but is the same as that of biomat formed at the mine water discharge position. This indicates that As trapped by the moss on the concrete wall probably has the same origin as the biomat. It is concluded that application of μ-PIXE analysis to the measurement of As in the lower plants and biomat gives not only the distribution of the hazardous element of As, but also the information of the origin.

Strategies for the investigation of contaminated sites using field portable x‐ray fluorescence (FPXRF) techniques

The remediation of contaminated land is a potentially complex exercise and is one which requires a sound approach to achieve a degree of remediation which complies with existing legislative guidelines. Current guidelines for the assessment and management of contaminated sites include staged investigations (Qld DoE 1998), which relate to past uses of the site under investigation coupled with a detailed study of the total extent of chemical (and other) contamination. In performing these site investigations, it is important that a sound approach is developed to collect, for subsequent chemical analysis, a sufficient set of samples at suitable locations in order to provide relevant information on the degree and extent of the site contamination. In this study an FPXRF spectrometer (NITON, Bedford, USA) was evaluated to assess its value in the sampling, collection and geographic modeling on the extent of a range of contaminant elements including arsenic (As) arising from the operation of a now disused plunge dip. Contamination boundaries and spatial distributions of As were determined both in‐situ and ex‐situ using this portable technique over a number of locations in and around the disused plunge dip site. These values were compared with concentrations found for collected samples using standard USEPA protocols, including ICP‐OES (Inductively coupled plasma ‐ optical emission spectrometry. Spectro, Kleve, Germany) and ICP‐MS (Inductively coupled plasma ‐ mass spectrometry. VG PlasmaQuad, Winsford, UK). A comparative assessment of this approach is presented in terms of recommending an enhanced strategy for future investigations of contaminated sites using such field portable techniques.