Elemental and radionuclide concentrations for several vegetation species from a site in Extremadura, Spain

Mediterranean plants (n=30, listed below), seeds from selected species (n=6, identified by*) and soil (n=3) samples were collected in June 2014 from along a transect located in the Monfragüe National Park which is within the province of Cáceres, western Spain (transect start: N 33° 49' 47.2'', W 006° 0 01' 55.4'', transect end: N 390 49' 46.8'', W 0060 02' 05.1'' (WG 884)). Species collected were: Agrostis pourretii; Campanula rapunculus; Taraxacum sp.; Taraxacum officinale; Rumex scutatus; Hypericum perforatum; Schoenoplectus pungens; Erica umbellata; Phillyrea angustifolia; *Myrtus communis.; Cytisus sp.; Vitis vinifera subsp. Sylvestris; *Crataegus monogyna; Daphne gnidium; Quercus ilex; Ruscus aculeatus; Olea europaea subsp. Europaea; Hordeum murinum; *Pistacia terebinthus; Acer monspessulanum; Ficus carica; *Cistus ladanifer; Eryngium campestre; Carlina vulgaris; Asparagus acutifolius; *Viburnum tinus; Tamarix gallica; Jasminum fruticans; Rubia peregrine and Trifolium campestre. \nSamples were stored as cool as possible prior to immediate transport to the UK where, on arrival, they were freeze-dried, weighed and then finely ground using a Christian-Norris vegetation mill. Sub-samples were then taken for gamma analysis from plant samples of larger mass (n=16) and the three soil samples. All the remaining ground soil and plant material was then re-weighed and digested using an aqua regia reagent (fresh 3:1 mixture of concentrated HNO3 and HCl ‘Aristar’ grade acids) at 175°C for 12 minutes using a microwave oven (CEM, MarsXpress). Analysis of the digests was then conducted by ICPMS (Perkin Elmer, NeXION 300D) or ICPOES (Perkin Elmer, Optima 7300 DV).\nICPMS and ICPOES measurements were made using two types of instrument operation, either semi-quantitative or quantitative or (using Perkin Elmer Total Quant software). The semi-quantitative measurements were made using the ICPMS instrument operating in kinetic energy discrimination (KED) mode with the addition of helium gas. The quantitative measurements were made using external calibration after spiking the digests with 10 µg l-1 Ga, In and Re as internal standards to compensate for instrumental drift and matrix effects. The semi-quantitative and quantitative modes differed as the former used an element concentration to intensity response curve to extrapolate concentrations over a wide mass range. ICPMS and ICPOES instrument limits of detection (LOD) were calculated by using the mean and three standard deviation measurements for the digestion reagent blank. For some elements determined using the semi-quantitative ICPMS method it was not possible to determine instrument LODs from the analysis of a digestion reagent blank and in these cases the instrument LODs were estimated from an assessment of instrument sensitivity and assigned a value of 0.001 µg l-1 (assumed to be equivalent to a mean method LOD of 0.001 mg kg-1). Total method LODs for each element were then calculated to take account the sample mass and the dilution arising from the digestion procedure. \nTo determine the activity concentration of Be-7, K-40 and Cs-137, soil and plant samples of sufficient mass, were analysed on hyper-pure germanium detectors for four days using an efficiency calibration suited to their sample density. The detectors were calibrated for efficiency using a mixed radionuclide standard which covered an energy range of approximately 59 -1850 keV and resultant spectra were analysed using the Canberra Apex software. The detectors were calibrated against standards of various density and volume, and the laboratory regularly participates in proficiency testing schemes. Minimum detectable activity (MDA) concentrations differ on a sample by sample basis dependant on detector, count time, sample type and sample mass/volume. \nElemental concentrations are reported as milligrams per kilogram dry mass. Radionuclide activity concentrations are reported as becquerel per kilogram dry mass. Concentrations at or below the LOD or MDA are preceded by a <.

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TRansfer - Exposure - Effects (TREE) Integrating the science needed to underpin radioactivity assessments for humans and wildlife