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Summary • The influence of phylogeny on shoot heavy metal content in plants was investigated and the hypothesis tested that traits impacting on the accumulation of cadmium, chromium, copper, nickel, lead and zinc in plant shoots are associated. • Data suitable for comparative analyses were generated from a literature survey, using a residual maximum likelihood (REML) procedure. Both pair-wise regressions and principal components analyses (PCA) were performed on independent contrasts of shoot metal content. • Significant variation in shoot metal content occurred at the classification level of order and above, suggesting an ancient evolution of traits. Traits impacting on the accumulation of metals in plant shoots were associated. • This information can be used to improve predictions of soil-to-plant metal transfer, to formulate hypotheses on the origins of metal-accumulating phenotypes and to inform the exploitation of plant genetic resources for nutritional improvement and phytoremediation.

Global food supplies currently depend on producing inorganic P fertilisers from a finite reserve of rock phosphate (RP). P fertilisers are themselves significant pollutants but their production from RP also leaves a phosphogypsum (PG) by-product that is sufficiently radioactive that its reuse is restricted. PG is mostly accumulated in open 'stacks' that make up a significant proportion of all Technologically Enhanced Naturally-Occurring Radioactive Material (TENORM) waste. Using lower and upper estimates of current RP reserves, historic production, and Hubbert's logistic function-based 'peak theory', lower and upper boundaries for possible RP production were predicted to the year 2100. The 'low' boundary scenario had a production peak of c.350 Mt/a RP in c.2050 followed by a steep decline. The 'high' boundary scenario had a production peak of c.1200 Mt/a RP in about 2090. Future trends in P demand for food production were used to predict a possible, demand-driven, RP production scenario until 2100 which peaked at a demand of c.620 Mt/a RP and was within possible production boundaries. An RP:P ratio of 5.62:1 and PG:P fertiliser ratio of 4:1 was used to calculate that this predicted demand-driven scenario would ultimately produce nearly 350 Mt/a of PG and a cumulative total of c.30 Gt by 2100. Average PG activity concentrations of

The effects of ionising radiation (IR) on plants are important for environmental protection but also in agriculture, horticulture, space science, and plant stress biology. Much current understanding of the effects of IR on plants derives from acute high-dose studies but exposure to IR in the environment frequently occurs at chronic low dose rates. Chronic low dose-rate studies have primarily been field based and examined genetic or cytogenetic endpoints. Here we report research that investigated developmental, morphological and physiological effects of IR on Arabidopsis thaliana grown over 7 generations and exposed for five generations to chronic low doses of either 137Cs (at a dose rate of c. 40 μGy/h from β/γ emissions) or 10 μM CdCl2. In some generations there were significant differences between treatments in the timing of key developmental phases and in leaf area or symmetry but there were, on the basis of the chosen endpoints, no long-term effects of the different treatments. Occasional measurements also detected no effects on root growth, seed germination rates or redox poise but in the generation in which it was measured exposure to IR did decrease DNA-methylation significantly. The results are consistent with the suggestion that chronic exposure to c. 40 μGy/h can have some effects on some traits but that this does not affect function across multiple generations at the population level. This is explained by the redundancy and/or degeneracy between biological levels of organization in plants that produces a relatively loose association between genotype and phenotype. The importance of this explanation to understanding plant responses to stressors such as IR is discussed. We suggest that the data reported here provide increased confidence in the Derived Consideration Reference Levels (DCRLs) recommended by the International Commission for Radiological Protection (ICRP) by providing data from controlled conditions and helping to contextualize effects reported from field studies. The differing sensitivity of plants to IR is not well understood and further investigation of it would likely improve the use of DCRLs for radiological protection.

Statement paper following discussions in March 2019 between the TREE (Transfer-Exposure-Effects) project participants and members of the European Radioecology ALLIANCE working group on ‘transgenerational effects and species radiosensitivity'.

Predicting soil-to-plant transfer of radionuclides is restricted by the range of species for which concentration ratios (CRs) have been measured. Here the radioecological utility of meta-analyses of phylogenetic effects on alkali earth metals will be explored for applications such as ‘gap-filling’ of CRs, the identification of sentinel biomonitor plants and the selection of taxa for phytoremediation of radionuclide contaminated soils. REML modelling of extensive CR/concentration datasets shows that the concentrations in plants of Ca, Mg and Sr are significantly influenced by phylogeny. Phylogenetic effects of these elements are shown here to be similar. Ratios of Ca/Mg and Ca/Sr are known to be quite stable in plants so, assuming that Sr/Ra ratios are stable, phylogenetic effects and estimated mean CRs are used to predict Ra CRs for groups of plants with few measured data. Overall, there are well quantified plant variables that could contribute significantly to improving predictions of the fate radioisotopes in the soil-plant system.

We will never have data to populate all of the potential radioecological modelling parameters required for wildlife assessments. Therefore, we need robust extrapolation approaches which allow us to make best use of our available knowledge. This paper reviews and, in some cases, develops, tests and validates some of the suggested extrapolation approaches.\ud \ud The concentration ratio (CRproduct-diet or CRwo-diet) is shown to be a generic (trans-species) parameter which should enable the more abundant data for farm animals to be applied to wild species.\ud \ud An allometric model for predicting the biological half-life of radionuclides in vertebrates is further tested and generally shown to perform acceptably. However, to fully exploit allometry we need to understand why some elements do not scale to expected values.\ud \ud For aquatic ecosystems, the relationship between log10(a) (a parameter from the allometric relationship for the organism-water concentration ratio) and log(Kd) presents a potential opportunity to estimate concentration ratios using Kd values.\ud \ud An alternative approach to the CRwo-media model proposed for estimating the transfer of radionuclides to freshwater fish is used to satisfactorily predict activity concentrations in fish of different species from three lakes. We recommend that this approach (REML modelling) be further investigated and developed for other radionuclides and across a wider range of organisms and ecosystems.\ud \ud Ecological stoichiometry shows potential as an extrapolation method in radioecology, either from one element to another or from one species to another.\ud \ud Although some of the approaches considered require further development and testing, we demonstrate the potential to significantly improve predictions of radionuclide transfer to wildlife by making better use of available data.

Genomic and proteomic techniques provide the opportunity to investigate plant response to ionising radiation in unprecedented detail. Understanding plant molecular responses to ionising radiation might be useful for radioprotection but also for understanding plant stress responses. This is because radioactivity was a primordial stressor to cells and many stress responses are highly conserved through evolution. DNA microarrays for Arabidopsis plants exposed to 40 µGy h -1 through a hydroponic solution revealed that, after 14 days, there are changes in gene expression primarily in roots. The genes that change are not associated with DNA repair, and correlations with responses to other stressors in public databases suggest that there are elements of plant stress response being activated. The number of genes and their fold changes are lower than those reported for many other stressors but have particular overlaps with oxidative stress responses. Proteomic analyses form similar experiments are ongoing but similarly show no change of abundance in proteins associated with DNA repair and more changes in roots than shoots at these exposures.

There is current interest in managing and manipulating 137Cs transfer from soil to plants. We hypothesized that N source might affect Cs uptake by plants and report experiments that confirm this. Uptake experiments using hydroponics with a variety of species in the Poaceae, Asteraceae and Caryophyllid clade grown in a variety of N regimes with excess N and then acutely exposed to Cs showed that N nutrition could affect Cs uptake rates, total amounts of Cs taken up and root:shoot ratios of Cs. In general, the Caryophyllids tested produced significantly less shoot and root biomass but had higher Cs uptake rates when grown on NH4+ rather than NO3−, whilst species from the Poaceae and Asteraceae almost always produced similar shoot and root biomass and had similar Cs uptake on NH4+, NO3− or glycine as N sources. This is the first time that plants grown on an organic-N source have been demonstrated to take up Cs. Physiological experiments using N-starvation and the N-metabolism inhibitor methionine sulfoxamine (MSX) demonstrated that Cs transport into the root was inversely related to NH4+ transport, i.e. NH4+-grown plants had higher Cs uptake rates if there is no NH4+ present during uptake but lower Cs uptake rates if NH4+ is present. It is suggested that taking account of N ecophysiology might help refine predictions of soil-to-plant transfer of 137Cs and, in some instances, be useful for managing or manipulating it. It is noted that there is much recent research into N nutrition in plants that might be useful in achieving this.

A Residual Maximum Likelihood (REML) procedure was used to compile Sr concentrations in 103 plant species from experiments with Sr concentrations in 66 plant species from the literature. There were 14 species in common between experiments and the literature. The REML procedure loge-transformed data and removed absolute differences in Sr concentrations arising from soil factors and exposure times to estimate mean relative Sr concentrations for 155 species. One hundred and forty-two species formed a group with a normal frequency distribution in mean relative Sr concentration. A nested hierarchical analysis of variance (ANOVA) based on the most recent molecular phylogeny of the angiosperms showed that plant species do not behave independently for Sr concentration but that there is a significant phylogenetic effect on mean relative Sr concentrations. Concentrations of Sr in non-Eudicots were significantly less than in Eudicots and there were significant effects on Sr concentrations in the dataset down the phylogenetic hierarchy to the family level. Of the orders in the dataset the Cucurbitales, Lamiales, Saxifragales and Ranunculales had particularly high Sr concentrations and the Liliales, Poales, Myrtales and Fabales particularly low Sr concentrations. Mean relative Sr concentrations in 60 plant species correlated with those reported elsewhere for Ca in the same species, and the frequency distribution and some phylogenetic effects on Sr concentration in plants were similar to those reported for Ca. This analysis of mean relative Sr concentrations in 155 plant species across the angiosperm phylogeny might be helpful for modelling 90Sr in food chains, predicting radiological doses to flora, and selecting species for phytomonitoring and phytoremediation of 90Sr.

Ruthenium-106 is of potential radioecological importance but soil-to-plant Transfer Factors for it are available only for few plant species. A Residual Maximum Likelihood (REML) procedure was used to construct a database of relative 103/106 Ru concentrations in 114 species of flowering plants including 106 species from experiments and 12 species from the literature (with 4 species in both). An Analysis of Variance (ANOVA), coded using a recent phylogeny for flowering plants, was used to identify a significant phylogenetic effect on relative mean 103/106 Ru concentrations in flowering plants. There were differences of 2465-fold in the concentration to which plant species took up 103/106 Ru. Thirty-nine percent of the variance in inter-species differences could be ascribed to the taxonomic level of Order or above. Plants in the Orders Geraniales and Asterales had notably high uptake of 103/106 Ru compared to other plant groups. Plants on the Commelinoid monocot clades, and especially the Poaceae, had notably low uptake of 103/106 Ru. These data demonstrate that plant species are not independent units for 103/106 Ru concentrations but are linked through phylogeny. It is concluded that models of soil-to-plant transfer of 103/106 Ru should assume that; neither soil variables alone affect transfer nor plant species are independent units, and taking account of plant phylogeny might aid predictions of soil-to-plant transfer of 103/106 Ru, especially for species for which Transfer Factors are not available.

There is much current interest in managing and manipulating radionuclide transfer from soils to plants, either for 'safe' crops or for phytoextraction of radionuclide contaminated soils. Potentially there is biodiversity in plant uptake that might aid these efforts. We have established the effects of phylogeny (evolutionary history) on the uptake of numerous heavy metal and nutrient elements. Here, using the same Residual Maximum Likelihood techniques, we report phylogenetic effects on radionuclide uptake by plants derived from databases of several hundred species of plants we have collated over recent years. There are differences of at least two orders of magnitude in the concentration to which plants take up isotopes of Cs, Sr, Cl, Ru, S, and I. When analysed using hierarchical Analysis of Variance coded using a recent molecular phylogeny of flowering plants it is clear that for no radionuclide is all the variation inter-specific. Rather, for all radionuclides some of the inter-taxa variation is associated with higher taxonomic levels. In general, therefore, groups of plants with high and low uptake of radionuclides, and that might be useful for managing or manipulating radionuclide uptake, can be delineated. Here we discuss some of these groups and how they might be useful.

Caesium (Cs) is an alkali metal with chemical properties similar to potassium (K). It has no known role in plant nutrition and it is not toxic to plants at the micromolar concentrations occurring naturally in soil solutions. However, two radioisotopes of Cs (134Cs and 137Cs) are of environmental concern due to their relatively long half-lives, emissions of β and γ radiation during decay, and rapid incorporation into biological systems. There is considerable interest in remediating sites contaminated by these isotopes using phytoextraction and, since the produce from radiocaesium-contaminated areas may enter the food chain, the introduction of `safe' crops that do not accumulate Cs. This article reviews the molecular mechanisms of Cs uptake by plants, and provides a perspective on strategies to develop: (1) plants that extract Cs efficiently from soils (for the phytoremediation of land), or (2) `safe' crops that minimise the entry of radiocaesium directly into the human food chain.

This study investigated the uptake of 134Cs by Lactuca sativaL., Silybum marianumGaertn., Centaurea cyanusL., Carthamus tinctorius L. from the Asteraceae, and Beta vulgaris L. var. `Lutiancai' and Beta vulgaris L. var. `Hongtiancai' from the Chenopodiaceae grown in two widely-distributed soils (a paddy soil and a red soil) in South China. The results showed that the plants growing on the paddy soil had a relatively high yield and low [134Cs] while those growing on the red soil showed the opposite trend. The accumulation of 134Cs was dependent on plant species and soil types. For the paddy soil, mean values for [134Cs] were higher for the species of the Asteraceae (ranging from 165 to 185 Bq g−1) than for those of the Chenopodiaceae (less than 140 Bq g−1). For the red soil, S. marianumand C. cyanus of the Asteraceae had high average concentrations of 134Cs ranging from 340 to 400 Bq g−1 but L. sativa and C. tinctorius from the same family had low concentrations of 134Cs ranging from 115 to 200 Bq g−1 on a dry weight basis. B. vulgaris L. var. `Lutiancai' and Beta vulgaris L. var. `Hongtiancai' accumulated from 120 to 231 Bq 134Cs g−1 of plant shoot. The transfer factor values of 134Cs for the studied species were in general higher in red soil than in paddy soil except C. tinctorius. All plant species from the Asteraceae family growing on the paddy soil had higher transfer factors than the B. vulgaris species. S. marianum, and C. cyanus growing on the red soil had TFs >1, being much higher than the B. vulgaris species. The results therefore showed that the plant species from the Asteraceae could accumulate higher concentrations of radiocesium than the Beta vulgaristhat has previously been suggested as a candidate for phytoremediation of radiocesium contaminated soils.

The fission yield of 99Tc from 239Pu and 235U is similar to that of 137Cs or 90Sr and it is therefore an important component of nuclear weapons fall-out, nuclear waste and releases from nuclear facilities. There is particular current interest in 99Tc transfer from soil to plants for: (a) environmental impact assessments for terrestrial nuclear waste repositories, and (b) assessments of the potential for phytoextraction of radionuclides from contaminated effluent and soil. Vascular plants have a high 99Tc uptake capacity, a strong tendency to transport it to shoot material and accumulate it in vegetative rather than reproductive structures. The mechanisms that control 99Tc entry to plants have not been identified and there has been little discussion of the potential for phytoextraction of 99Tc contaminated effluents or soil. Here we review soil availability, plant uptake mechanisms and soil to plant transfer of 99Tc in the light of recent advances in soil science, plant molecular biology and phytoextraction technologies. We conclude that 99Tc might not be highly available in the long term from up to 50% of soils worldwide, and that no single mechanism that might be easily targeted by recombinant DNA technologies controls 99Tc uptake by plants. Overall, we suggest that Tc might be less available in terrestrial ecosystems than is often assumed but that nevertheless the potential of phytoextraction as a decontamination strategy is probably greater for 99Tc than for any other nuclide of radioecological interest.

Our understanding of the evolutionary relationships (phytogenies) between flowering plants has been transformed in the last yen years. As a result, new phylogenies for flowering plants have been developed specifically for comparative biological studies. Researchers have used these new phylogenies to help explain variation in a number of plant characteristics. We have used them to help explain soil to plant transfer of heavy metal ions and have recently finished applying them to studies of soil to plant transfer of radionuclides.

The Michaelis–Menten kinetic parameters ( I max , K m and Cmin) of Cs uptake were estimated using a solution-depletion method, after 0, 1 and 4 d K-starvation in eight mature grass species of different relative growth rates (Bromus sterilis L., Elymus repens (L.) Gould, Poa annua L., Lolium perenne L. var. ‘Taya’, Anthoxanthum odoratum L., Festuca gigantea (L.) Vill., Festuca ovina L. and Nardus stricta L.). There were species differences in Imax and Cmin, a positive relationship between Km and RGR (r2=0.53; p=0.03), and a negative relationship between Cmin and RGR (r2=0.89; p=0.001) in 0 d K starved plants. In general, Imax increased with K starvation, as previously reported for K uptake kinetics. Km increased with K starvation, contrasting with reported studies on K, and Cmin decreased, although all species did not respond similarly.

The application of the concentration ratio (CR) to predict radionuclide activity concentrations in wildlife from those in soil or water has become the widely accepted approach for environmental assessments. Recently both the ICRP and IAEA have produced compilations of CR values for application in environmental assessment. However, the CR approach has many limitations, most notably, that the transfer of most radionuclides is largely determined by site-specific factors (e.g. water or soil chemistry). Furthermore, there are few, if any, CR values for many radionuclide-organism combinations. In this paper, we propose an alternative approach and, as an example, demonstrate and test this for caesium and freshwater fish. Using a Residual Maximum Likelihood (REML) mixed-model regression we analysed a dataset comprising 597 entries for 53 freshwater fish species from 67 sites. The REML analysis generated a mean value for each species on a common scale after REML adjustment taking account of the effect of the inter-site variation. Using an independent dataset, we subsequently test the hypothesis that the REML model outputs can be used to predict radionuclide, in this case radiocaesium, activity concentrations in unknown species from the results of a species which has been sampled at a specific site. The outputs of the REML analysis accurately predicted (137)Cs activity concentrations in different species of fish from 27 Finnish lakes; these data had not been used in our initial analyses. We recommend that this alternative approach be further investigated for other radionuclides and ecosystems.

It has been hypothesized that radiation-induced oxidative stress is the mechanism for a wide range of negative impacts on biota living in radioactively contaminated areas around Chernobyl. The present study tests this hypothesis mechanistically, for the first time, by modelling the impacts of radiolysis products within the cell resulting from radiations (low linear energy transfer β and γ), and dose rates appropriate to current contamination types and densities in the Chernobyl exclusion zone and at Fukushima. At 417 µGy h −1 (illustrative of the most contaminated areas at Chernobyl), generation of radiolysis products did not significantly impact cellular concentrations of reactive oxygen species, or cellular redox potential. This study does not support the hypothesis that direct oxidizing stress is a mechanism for damage to organisms exposed to chronic radiation at dose rates typical of contaminated environments.

Assessments of the behaviour of 99Tc in terrestrial environments necessitate predicting soil-to-plant transfer. An experiment with 116 plant taxa showed that 99Tc transfer to plants was positively related to plant dry weight but negatively related to % dry matter and age at exposure. Activities of 99Tc analysed by hierarchical ANOVA coded with an angiosperm phylogeny revealed significant effects, with 55% of the variance between species explained at the Ordinal level and above. Monocots had significantly lower transfer of 99Tc than Eudicots, within which Caryophyllales > Solanales > Malvales > Brassicales > Asterales > Fabales. There was a significant phylogenetic signal in soil-to-plant transfer of 99Tc. This phylogenetic signal is used to suggest that, for example, a nominal Tc Transfer Factor of 5 could be adjusted to 2.3 for Monocots and 5.3 for Eudicots.

An extensive literature reports that Cs(+), an environmental contaminant, enters plant cells through K(+) transport systems. Several recently identified plant K(+) transport systems are permeable to Cs(+). Permeation models indicate that most Cs(+) uptake into plant roots under typical soil ionic conditions will be mediated by voltage-insensitive cation (VIC) channels in the plasma membrane and not by the inward rectifying K(+) (KIR) channels implicated in plant K nutrition. Cation fluxes through KIR channels are blocked by Cs(+). This paper tests directly the hypothesis that the dominant KIR channel in plant roots (AKT1) does not contribute significantly to Cs(+) uptake by comparing Cs(+) uptake into wild-type and the akt1 knockout mutant of Arabidopsis thaliana (L.) Heynh. Wild-type and akt1 plants were grown to comparable size and K(+) content on agar containing 10 mM K(+). Both Cs(+) influx to roots of intact plants and Cs(+) accumulation in roots and shoots were identical in wild-type and akt1 plants. These data indicate that AKT1 is unlikely to contribute significantly to Cs(+) uptake by wild-type Arabidopsis from 'single-salt' solutions. The influx of Cs(+) to roots of intact wild-type and akt1 plants was inhibited by 1 mM Ba(2+), Ca(2+) and La(3+), but not by 10 microM Br-cAMP. This pharmacology resembles that of VIC channels and is consistent with the hypothesis that VIC channels mediate most Cs(+) influx under 'single-salt' conditions.

A method was developed to obtain relative shoot caesium (Cs) concentration data from the literature and assess the influence of plant taxonomy on these values. A residual maximum likelihood (REML) analysis was performed on data from 14 published studies, after these data were log-transformed to adjust for between-study differences in means and variances. There were two orders of magnitude difference between the lowest and highest relative shoot Cs concentration of the 136 taxa. Hierarchical nested analysis of variance revealed more than 40% of the variation in relative shoot Cs concentration was at the level of family or above. Dicotyledons (Magnoliopsida) had three-fold higher mean relative shoot Cs concentrations than monocotyledons (Liliopsida) whilst differences were also observed at lower taxonomic levels. The Caryophyllidae had the highest mean relative shoot Cs concentration among superorders; this group of plants contains many halophyte taxa and crop derivatives (e.g. beets, quinoas, buckwheats and amaranths). This method could inform soil-to-plant Cs transfer models and identify taxa with high Cs accumulation patterns that may have phytoremediation potential. The method reported could be used to study the accumulation of other elements in plants.

The concentration of Cs was measured in the shoots of 30 taxa of plants after exposing the roots for 6 h to 0.1 microg radiolabelled Cs g(-1) soil. There were maximum differences between Chenopodium quinoa and Koeleria macrantha of 20-fold in Cs concentration and 100-fold in total Cs accumulated. There was a weak relationship between Rb (K) and Cs concentration across the 30 taxa, but a strong relationship within the Gramineae and Chenopodiaceae. Taxa in the Chenopodiaceae discriminated approximately nine times less between Rb and Cs during uptake than did those in the Gramineae. The lowest Cs concentrations occurred in slow growing Gramineae and the highest in fast growing Chenopodiaceae. If radiocaesium uptake by the Chenopodiaceae during chronic exposures shows similar patterns to those reported here after acute exposure, then the food contamination implications and the potential for phytoremediation of radiocaesium contaminated soils using plants in this family may be worth investigating.

Six plant species in the family Gramineae were used to investigate the relationship between Cs uptake, nutrient regime and plant growth strategy sensu Grime (1979: Plant Growth Strategies and Vegetation Processes, John Wiley). The roots of 66 day old Elymus repens (L.) Gould., Bromus sterilis L., Agrostis stolonifera L., Anthoxanthum odoratum L., Festuca ovina L. and Nardus stricta L. plants grown in acid-washed sand at high and low nutrient levels were exposed to a 96 h pulse of stable Cs at 0.05 mm, 0.15 mm, 0.3 mm, 1.0 mm and 3.0 mm concentrations. Different nutrient regimes induced large differences in dry wt in E. repens, B. sterilis and A. stolonifera plants but only small differences in N. stricta and F. ovina plants. At high nutrient concentrations, A. stolonifera, A. odoratum, F. ovina and N. stricta shoots showed significantly greater increases in internal Cs concentration with rising external Cs concentrations than did E. repens and B. sterilis shoots. The relationship between increases in shoot and external Cs concentrations was statistically indistinguishable between species in plants grown at the low nutrient concentration. These patterns of Cs uptake ensured that with long-term high K concentrations the more competitive plants (E. repens and B. sterilis) accumulated higher concentrations of Cs from low external concentrations than did non-competitive plants or competitive plants grown at low nutrient levels. It is suggested that the relationship between plant growth strategy sensu Grime (1979) and Cs accumulation patterns may help to explain the different concentrations to which species accumulate radiocaesium from the soil.

Radionuclide activity concentrations in food crops and wildlife are most often predicted using empirical concentration ratios (CRs). The CR approach is simple to apply and some data exist with which to parameterise models. However, the parameter is highly variable leading to considerable uncertainty in predictions. Furthermore, for both crops and wildlife we have no, or few, data for many radionuclides and realistically, we are never going to have specific data for every radionuclide - wildlife/crop combination. In this paper, we present an alternative approach using residual maximum likelihood (REML) fitting of a linear mixed effects model; the model output is an estimate of the rank-order of relative values. This methodology gives a less uncertain approach than the CR approach, as it takes into account the effect of site; it also gives a scientifically based extrapolation approach. We demonstrate the approach using the examples of Cs for plants and Pb for terrestrial wildlife. This is the first published application of the REML approach to terrestrial wildlife (previous applications being limited to the consideration of plants). The model presented gives reasonable predictions for a blind test dataset.