Radioisotope‐induced EDXRF investigation of elemental uptake in cauliflower grown at MSW‐contaminated site

Abstract

A 109 Cd radioisotope-induced energy dispersive X-ray fluorescence (EDXRF) study has been performed on samples of cauliflower consisting of the flower, the leaves and the associated root soil. The cauliflowers are collected from farms near the main dumping site of municipal solid waste (MSW) in the city of Kolkata, India, and also from uncontaminated farms about 50 km away from the city. The systematic investigation is primarily aimed at achieving two correlated objectives. Firstly, a unified calibration approach is undertaken for the study tool viz., EDXRF spectrometer, through the use of same instrumental scattering constants for quantification in widely differing matrices like soil and plant. Quality control was done by quantitative reproduction of National Institute of Standards and Technology-Standard Reference Materials (NIST-SRMs). Subsequently, the second objective is to comparatively study elemental uptake in the cauliflower samples from contaminated and uncontaminated farms using the same calibration. This study suggests that the elemental concentrations in the root soils and leaves of the samples vary from farm to farm, whereby the concentrations of Cu, Zn and Pb in root soils of MSW-contaminated farms are higher by almost an order of magnitude compared to uncontaminated farms. But the most notable feature of this study is the strikingly similar elemental concentrations in the edible flower part of all samples irrespective of the soil type. Plots of the ratio of concentrations of elements in leaf to soil and in flower to leaf, observed from the present EDXRF study suggests that a preferential uptake of elements takes place at different stages.

Nondestructive Characterization of Municipal-Solid-Waste-Contaminated Surface Soil by Energy-Dispersive X-ray Fluorescence and Low-Z (Atomic Number) Particle Electron Probe X-ray Microanalysis

“…36,39 Investigations regarding the elemental phytoavailability and uptake pattern by different vegetable species grown on this site have already been performed. [12][13][14] A full understanding of the sources of heavy metals in MSW and the evolution process of this so-called anthropogenic soil will require a further detailed time scale study. 2,5 Soil remedial measures for removal or immobilization of the heavy metals have to be considered.…”

“…The source holder with a graded collimator, the sample holding plate, and the graded collimator on the detector side are mounted in a mechanical arrangement with a definite geometry. 14 The angles subtended by the incident and emergent radiations with respect to the sample surface were determined experimentally to be nearly 45 each, as described in detail elsewhere. 14,26 The detection medium was air with an X-ray detection range of 3-20 keV.…”

“…14 The angles subtended by the incident and emergent radiations with respect to the sample surface were determined experimentally to be nearly 45 each, as described in detail elsewhere. 14,26 The detection medium was air with an X-ray detection range of 3-20 keV. All the spectra for the soil samples and SRM-2586 were taken with a preset time of 60,000 sec.…”

“…In the BFP method, 23 the ratio of coherent to incoherent scattered radiation intensities are used to find the dark matrix. 29,30 The required fluorescent instrumental constants were estimated by irradiating different standard elemental foils, 14 pellets of pure compounds, and/or thin films of pure elements on Mylar substrates. 11 Scattering constants (coherent and incoherent) were obtained by measurement of the characteristic scattered peaks generated by irradiating standard pellets of the compounds (of mostly low-Z elements with known stoichiometry) that have similar thicknesses to the samples.…”

“…The toxic elements may accumulate in the food chain, primarily through the vegetables grown on these garbage farms at Dhapa. [12][13][14] The toxic elements could also propagate further underground through leaching. A thorough survey of the elemental and chemical species constituting the topsoil is needed to understand the ecological implications and thereby facilitate remedial measures.…”