Effect of ammonium sulfate combined with aqueous bio-chelator on Cd uptake by Cd-hyperaccumulator Solanum nigrum L.

The efficacy of using plants to phytoremediate heavy metal (HM) contaminated soils can be improved using soil amendments. These amendments may both increase plant biomasses and HMs uptake. We aimed to determine the composite effect of ammonium sulfate ((NH4)2SO4) combined with the application of an aqueous stem-extracted bio-chelator (Bidens tripartita L) on the plant biomasses and cadmium (Cd) phytoextraction by Solanum nigrum L. The constant (NH4)2SO4 application mode plus bio-chelator additives collectively enhanced the shoot Cd extraction ability owing to the increased plant biomass and shoot Cd concentration by S. nigrum. The shoot Cd extraction and the soil Cd decreased concentration confirmed the optimal Cd phytoextraction pattern in K8 and K9 treatments (co-application of (NH4)2SO4 and twofold/threefold bio-chelators). Accordingly, Cd contamination risk in the soil (2 mg kg-1) could be completely eradicated (<0.2 mg kg-1) after three rounds of phytoremediation by S.nigrum based on K8 and K9 treatments through calculating soil Cd depletion. The microorganism counts and enzyme activities in rhizosphere soils at treatments with the combined soil additives apparently advanced. In general, co-application mode of (NH4)2SO4 and aqueous bio-chelator was likely to be a perfect substitute for conventional scavenger agents on account of its environmental friendliness and cost saving for field Cd contamination phytoremediation by S. nigrum.

Chemical elements in Elaeis guineensis materials and derived oil.

The production of oil palm (Elaeis guineensis) in Southeast Asia is vital to the economies of Indonesia and Malaysia. Both fertilisers and pesticides used in palm production can contain elevated concentrations of Trace Elements (TEs) which may accumulate in soils and leaf tissues of plants. We hypothesised that leaves from oil palms may be deficient in essential elements, while containing elevated concentrations of non-essential TEs commonly found in agrichemicals. Samples of plant materials (leaves and fruitlets) were collected from active and former plantations in Sumatra, Indonesia, and analysed for essential and non-essential elements. Indonesian palm oil samples were sourced in New Zealand and their elemental concentrations determined. Leaf materials from both active and abandoned production sites were deficient in N, K, S and Mo, while leaf materials from abandoned sites were deficient in P. These deficiencies may have been a contributing factor to the abandonment of production at these sites. Concentrations of non-essential elements were below or comparable to average plant concentrations and no evidence of contamination was found in plant tissues. Palm oil contained low concentrations of TEs, which did not pose any toxicity risks. However, Na and Al were present in concentrations of 1198 and 159 mg kg-1 respectively, which were higher than have been previously reported. Tropical oil palm production could benefit from the determination of bioaccumulation factors for fertiliser contaminants in E. guineensis, to limit the transfer of contaminants to plants and products if increased fertiliser applications were used to correct nutrient deficiencies.

The Uptake of Rare Trace Elements by Perennial Ryegrass (Lolium perenne L.).

Technological development has increased the use of chemical elements that have hitherto received scant scientific attention as environmental contaminants. Successful management of these rare trace elements (RTEs) requires elucidation of their mobility in the soil-plant system. We aimed to determine the capacity of Lolium perenne (a common pasture species) to tolerate and accumulate the RTEs Be, Ga, In, La, Ce, Nd, and Gd in a fluvial recent soil. Cadmium was used as a reference as a well-studied contaminant that is relatively mobile in the soil-plant system. Soil was spiked with 2.5-283 mg kg-1 of RTE or Cd salts, representing five, 10, 20, and 40 times their background concentrations in soil. For Be, Ce, In, and La, there was no growth reduction, even at the highest soil concentrations (76, 1132, 10.2, and 874 mg kg-1, respectively), which resulted in foliar concentrations of 7.1, 12, 0.11, and 50 mg kg-1, respectively. The maximum no-biomass reduction foliar concentrations for Cd, Gd, Nd, and Ga were 0.061, 0.1, 7.1, and 11 mg kg-1, respectively. Bioaccumulation coefficients ranged from 0.0030-0.95, and increased Ce < In < Nd ≅ Gd < La ≅ Be ≅ Ga < Cd. Beryllium and La were the RTEs most at risk of entering the food chain via L. perenne, as their toxicity thresholds were not reached in the ranges tested, and the bioaccumulation coefficient (plant/soil concentration quotient) trends indicated that uptake would continue to increase at higher soil concentrations. In contrast, In and Ce were the elements least likely to enter the food chain. Further research should repeat the experiments in different soil types or with different plant species to test the robustness of the findings.

The Potential of Myrtaceae Species for the Phytomanagement of Treated Municipal Wastewater.

The use of native plants in land application systems for treated municipal wastewater (TMW) can contribute to ecological restoration. However, research on the potential of native species to manage the nutrients and contaminants contained in TMW is scarce. At a 10-hectare field site irrigated with TMW at >4000 mm yr-1, we investigated the distribution of nutrients and trace elements in the soil-plant system, comparing the New Zealand native Myrtaceae species Leptosperum scoparium and Kunzea robusta with pasture. The results showed that plant growth did not correlate with TMW irrigation rates. L. scoparium and K. robusta had higher foliar trace element concentrations than pasture, but these were not correlated with TMW irrigation rates. The pasture accumulated more N and P (68 kg of N ha-1 yr-1 and 11 kg of P ha-1 yr-1) than the Myrtaceae species (0.6-17 kg of N ha-1 yr-1 and 0.06-1.8 kg of P ha-1 yr-1). Regular harvesting of the pasture would likely remove more N and P from the site than the Myrtaceae species. The results highlight the importance of adjusting TMW application rates to the soil-plant capacity, in which case, native plants could provide ecological or economic value to TMW-irrigated land.

Trace Element Uptake by Willows Used for the Phytoremediation of Biosolids.

The land application of biosolids can result in the unacceptable accumulation of Trace Elements (TEs) in agricultural soil and potentially introduce xenobiotics and pathogens into the food chain. Phytoremediation of biosolids aims to minimize this risk, while producing valuable biomass. Willows, well known to accumulate zinc (Zn), are used extensively in farming systems for soil conservation, shelter and as feed supplements with demonstrable health benefits. Potentially, biosolids phytoremediation could occur on marginal lands adjacent to farmlands where willows are grown for supplementary fodder. We aimed to determine the uptake and distribution of Zn and other TEs in willows grown on soils amended with biosolids and biosolids blended with biochar, with a view to their use as stock fodder. In the Canterbury Region, New Zealand, we grew Salix 'tangaio' (S. matsudana X S. alba) in a greenhouse trial and field study. The biomass production of the willows was unaffected by biosolids and increased by the biosolids+biochar mixture. The addition of 4% biosolids (w/w) to the soil resulted in a foliar Zn concentration of 600-1000 mg kg-1, some 25 times higher than the average New Zealand pasture. Zinc concentrations were highest in the bottom leaves and increased throughout the season. Biosolids addition doubled the copper (Cu) concentration to 10 mg kg-1. Adding biochar to the system reduced the plant uptake of Cu and to a lesser extent Zn, while cadmium (Cd) uptake was unaffected. For Cd, Cu, and Zn, plant uptake was a function of the Ca(NO3)2-extractable concentration, both in greenhouse experiments and the field trial. Future work should determine the changes in plant TE uptake over several growing seasons.

An Assessment of the Feasibility of Phytoextraction for the Stripping of Bioavailable Metals from Contaminated Soils.

Phytoextraction has been proposed in many papers as a low-cost method for remediating contaminated soil. However, if national regulation is based on total metal(loid) concentrations in soil, phytoextraction is generally infeasible because of the long time required for remediation. Assessing phytoextraction requires determination of the dynamic rate of metal removal from soil. Phytoextraction may be feasible if the main goal is to reduce the soluble fraction of the metal(loid) with the goal of reducing bioavailability. However, it has been reported that there is a large mass balance mismatch between the reduction of the soluble metal fraction in contaminated soil and metal uptake by plants. Several studies report that the decrease of soluble fraction of metals in soil is higher than can be accounted for by plant uptake. In other words, studies generally overestimate the feasibility of bioavailable contaminant stripping. Therefore, a more rigorous approach is advisable to ensure that papers on bioavailable contaminant stripping include relevant information on mass balances. Furthermore, to implement the concept of bioavailable contaminant stripping, regulations must distinguish between the bioavailable fraction and the total metal concentration in soil. Environ Toxicol Chem 2023;42:558-565. © 2022 SETAC.

Grasses procure key soil nutrients for clovers.

Rhizobial nitrogen fixation in legumes provides spillover benefits to neighbouring plants such as pasture grasses. Generally, it is understood to be unidirectional between plant functional groups, providing a benefit from legumes to grasses. We question whether bidirectional complementarity also exists in terms of exploiting the wider soil nutrient pool. We test this hypothesis using soil cores with their component vegetation assemblages sampled from a hill country pasture in South Island, New Zealand. The soil was deficient in key essential elements: P, S, B, Mo and Ni. Facilitation from grasses to clovers was evident; legume-grass mixtures procured more nutrients from the soil than when either species was growing alone. When grasses and clover grow together in unfertilized grassland, more nitrogen is procured by the plant community, and other limiting plant nutrients in the soil are better exploited. Coexistence with grasses is favourable to clovers in terms of soil biogeochemistry.

The Phytomanagement of PFAS-Contaminated Land.

Globally, several hundred thousand hectares of both agricultural and urban land have become contaminated with per- and polyfluoroalkyl substances (PFAS). PFAS compounds are resistant to degradation and are mobile in soil compared to other common contaminants. Many compounds have KD values (matrix/solution concentration quotients) of <10. PFAS compounds endanger the health of humans and ecosystems by leaching into groundwater, exposure via dust, and, to a lesser extent, through plant uptake. This review aims to determine the feasibility of phytomanagement, the use of plants, and the use of soil conditioners to minimize environmental risk whilst also providing an economic return in the management of PFAS-contaminated land. For most sites, PFAS combinations render phytoextraction, the use of plants to remove PFAS from soil, inviable. In contrast, low Bioaccumulation Coefficients (BAC; plant and soil concentration quotients) timber species or native vegetation may be usefully employed for phytomanagement to limit human/food chain exposure to PFAS. Even with a low BAC, PFAS uptake by crop plants may still exceed food safety standards, and therefore, edible crop plants should be avoided. Despite this limitation, phytomanagement may be the only economically viable option to manage most of this land. Plant species and soil amendments should be chosen with the goal of reducing water flux through the soil, as well as increasing the hydrophobic components in soil that may bind the C-F-dominated tails of PFAS compounds. Soil conditioners such as biochar, with significant hydrophobic components, may mitigate the leaching of PFAS into receiving waters. Future work should focus on the interactions of PFAS with soil microbiota; secondary metabolites such as glomalin may immobilize PFAS in soil.

Plant Species Complementarity in Low-Fertility Degraded Soil.

The aim of this study was to investigate the compatibility of plants with contrasting root systems, in terms of procurement of limiting soil nutrients. Paired combinations of species of proteas and grasses were grown in a pot experiment using soil from a site with impoverished vegetation and degraded soil. The soil contained sufficient N but was low to deficient in P, Mn, S, Fe, and B. The uptake of chemical elements into the foliage differed significantly according to whether the plants were growing as single or mixed species. When two species of Grevillea and grasses with evolutionary origins in low fertility soils were growing together, there was an enhanced uptake of P and Mn, in one or both species, in addition to other elements that were in low concentrations in the experimental soil. In contrast to this, Protea neriifolia that probably originated from a more fertile soil procured lesser amounts of the six elements from the soil when growing together with grasses. Two grasses tolerant of less fertile soils (Dactylis glomerata and Poa cita) obtained more nutrients when they grew together with proteas; this was a much stronger neighbour effect than was measured in Lolium perenne which is better adapted to high fertility soils. The findings illustrate both the functional compatibility and competition for plant nutrients in mixed-species rhizospheres. Species combinations substantially increased the acquisition of key elements from the soil nutrient pool.

From mine to mind and mobiles - Lithium contamination and its risk management.

With the ever-increasing demand for lithium (Li) for portable energy storage devices, there is a global concern associated with environmental contamination of Li, via the production, use, and disposal of Li-containing products, including mobile phones and mood-stabilizing drugs. While geogenic Li is sparingly soluble, Li added to soil is one of the most mobile cations in soil, which can leach to groundwater and reach surface water through runoff. Lithium is readily taken up by plants and has relatively high plant accumulation coefficient, albeit the underlying mechanisms have not been well described. Therefore, soil contamination with Li could reach the food chain due to its mobility in surface- and ground-waters and uptake into plants. High environmental Li levels adversely affect the health of humans, animals, and plants. Lithium toxicity can be considerably managed through various remediation approaches such as immobilization using clay-like amendments and/or chelate-enhanced phytoremediation. This review integrates fundamental aspects of Li distribution and behaviour in terrestrial and aquatic environments in an effort to efficiently remediate Li-contaminated ecosystems. As research to date has not provided a clear picture of how the increased production and disposal of Li-based products adversely impact human and ecosystem health, there is an urgent need for further studies on this field.

Chemical Elements and the Quality of Manuka (Leptospermum scoparium) Honey.

Soil properties in the foraging range of honeybees influence honey composition. We aimed to determine relationships between the antimicrobial properties of New Zealand manuka (Leptospermum scoparium) honey and elemental concentrations in the honey, plants, and soils. We analyzed soils, plants, and fresh manuka honey samples from the Wairarapa region of New Zealand for the chemical elements and the antimicrobial activity of the honey as indicated by methylglyoxal (MGO) and dihydroxyacetone (DHA). There were significant negative correlations between honey MGO and the concentrations of Mn, Cu, Mg, S, Na, Ba, K, Zn, and Al. These elements may provide a low-cost means of assessing manuka honey quality. For individual elements, except for K, there were no correlations between the honeys, plants, and soils. Soil nitrate concentrations were negatively correlated with concentrations of MGO and DHA in the honey, which implies that soil fertility may be a determiner of manuka honey quality.

Phytomanagement of a metal(loid)-contaminated agricultural site using aromatic and medicinal plants to produce essential oils: analysis of the metal(loid) fate in the value chain.

Phytomanagement uses plants and soil conditioners to create value on contaminated land while minimizing environmental risk. This work was carried out on a metal(loid)-contaminated site and aimed at assessing the suitability of Salvia sclarea L. (sage) and Coriandrum sativum L. (coriander) combined with an arbuscular mycorrhizal fungus (AMF) inoculant to immobilize metal(loid)s and produce essential oils (EO). The effect of the inoculant on the transfer of metal(loid)s (ML, i.e., Cd, Cu, Pb, Zn, As, Ni, and Sb) to plants and the ML soil mobility were investigated. The ML concentrations in EO from both plant species and the valorization options for the distillation residues (soil conditioner, animal fodder, and anaerobic digestion) were studied. Sage was a suitable candidate for this value chain because it presents an excluder phenotype and the residues of oil extraction could be used as a soil conditioner. The metal concentrations in the sage EO were similar to those obtained from plants cultivated on an uncontaminated soil. These results indicate the suitability of sage harvested on the contaminated soil according to the ML fate in the whole value chain. Like the EO of sage, ML concentrations in the coriander EO did not differ from those in the commercial EO that were obtained from plants grown on uncontaminated soil. However, the use of distillation residues of coriander was limited by their relatively elevated Cd concentrations. The use of a mycorrhizal inoculum did not decrease the Cd mobility in soil for the coriander.

A risk-based approach for the safety analysis of eight trace elements in Chinese flowering cabbage (Brassica parachinensis L.) in China.

BACKGROUND: Most countries set regulatory values for the total trace element (TE) concentrations in soil, although there is growing interest in using a risk-based approach to evaluate the bioavailable TE using dilute salt extractants or other soil parameters, including pH and organic carbon. The present study compares the current regulatory system (based on total TEs and pH) and a risk-based approach using 0.01 mol L-1 CaCl2 to estimate the bioavailable fraction. RESULTS: In total, 150 paired samples of Chinese flowering cabbages (Brassica parachinensis) and their growth soils were collected, and the total and extractable concentrations of chromium (Cr), cadmium (Cd), lead (Pb), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As) and mercury (Hg), as well as soil pH and organic matter content, were measured. No more than 3.33% of the edible parts exceeded Chinese food safety standards, even when growing in soils exceeding the current regulatory thresholds by over 50%. The total soil Cd (1.5 mg kg-1 ), as well as the extractable concentrations of Cd (0.1 mg kg-1 ), Ni (0.03 mg kg-1 ) and Zn (0.1 mg kg-1 ), are the key factors affecting the TE concentrations in B. parachinensis. CONCLUSION: Our findings suggest that the current soil regulatory guidelines for safe production of B. parachinensis are overly strict and conservative. A risk-based approach based on the extractable TE concentrations would provide a better indication for plant uptake of soil TEs and avoid the waste of farmlands that can still produce safe vegetables. Future research should focus on providing crop-specific available TE concentration guidelines to promote effective utilization of farmlands. © 2021 Society of Chemical Industry.

Soil cadmium mobilisation by dissolved organic matter from soil amendments.

Dissolved organic matter (DOM) release from Cd contaminated soils been linked to mobilisation of the metal as Cd-DOM complexes and this may be exacerbated by organic matter-rich soil amendments. The quantity and quality of the DOM can determine the proportion of dissolved Cd that partitions to mobile complexes and their stability and, thus, the potential for Cd transport from contaminated soils. The aim of this work was to examine differences in Cd mobilisation from soils to which different types of soil amendments/conditioners have been applied and the importance of DOM characteristics in determining the extent to which this can happen. Three soils were spiked with Cd to 2 mg kg-1, allowed to equilibrate and then treated with compost and peat. These soils and an untreated subsample of each soil were then adjusted to three different pHs: 5.6, 6.4 and 7.4, using lime. The amount of Cd mobilised from each soil was tested using a column leaching experiment. Ultrafiltration and speciation modelling were used to determine amounts of Cd as DOM-complexed, "truly" dissolved (<5 kDa) and colloidal species, while DOM quality was assessed using UV-Vis and fluorescence spectroscopy. Most colloidal Cd was mobilised from the compost treated soils (50%-60%), followed by the peat treated soils (20-44%). The relationships between colloidal Cd, DOC concentration and soil pH, together with the spectroscopic and modelling results showed that structural properties of DOM are an important factor in mobilising Cd from contaminated soils.

Pesticides in aquatic environments and their removal by adsorption methods.

Although pesticides are widely used in agriculture, industry and households, they pose a risk to human health and ecosystems. Based on target organisms, the main types of pesticides are herbicides, insecticides and fungicides, of which herbicides accounted for 46% of the total pesticide usage worldwide. The movement of pesticides into water bodies occurs through run-off, spray drift, leaching, and sub-surface drainage, all of which have negative impacts on aquatic environments and humans. We sought to define the critical factors affecting the fluxes of contaminants into receiving waters. We also aimed to specify the feasibility of using sorbents to remove pesticides from waterways. In Karun River in Iran (1.21 × 105 ng/L), pesticide concentrations are above regulatory limits. The concentration of pesticides in fish can reach 26.1 × 103 µg/kg, specifically methoxychlor herbicide in Perca fluviatilis in Lithuania. During the last years, research has focused on elimination of organic pollutants, such as pesticides, from aqueous solution. Pesticide adsorption onto low-cost materials can effectively remediate contaminated waters. In particular, nanoparticle adsorbents and carbon-based adsorbents exhibit high performance (nearly 100%) in removing pesticides from water bodies.

Antioxidant Enzyme Activity and Lipid Peroxidation in Aporrectodea caliginosa Earthworms Exposed to Silver Nanoparticles and Silver Nitrate in Spiked Soil.

Silver nanoparticles (AgNPs) from industrial use, discharged via the land application of sewage sludge, are interacting with soil biota, including earthworms. In affected organisms, excessive production of reactive oxygen species can result in lipid peroxidation, shifting the balance between oxidants and antioxidants to cause oxidative stress. We determined selected lower-tier biomarkers such as antioxidant responses and lipid peroxidation in Aporrectodea caliginosa earthworms exposed to soils spiked with AgNPs or silver nitrate (AgNO3 ). Aporrectodea caliginosa were exposed to AgNPs at 0 (control), 0.3, 3, 30, and 300 mg/kg or Ag+ (as AgNO3 ) at 0, 0.03, 0.3, 3, and 10 mg/kg in soil for 4 wk. At 1, 2, 3, and 4 wk, the activity of the antioxidant enzymes superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase, as well as lipid peroxidation (malondialdehyde content), increased as a function of concentration, with a much larger response for Ag+ than AgNPs. Given the likelihood of ever-increasing AgNP concentrations in soil, where AgNPs can transform to ionic Ag (Ag+ ), our findings of antioxidant response to oxidative stress in a common indicator organism even at an environmentally realistic exposure concentration of 0.03 mg/kg demonstrate that AgNPs may affect soil fertility and, thus, agricultural production. Evaluating selected lower-tier biomarkers offers a meaningful assessment of AgNPs and Ag+ effects on terrestrial earthworms. Environ Toxicol Chem 2020;39:1257-1266. © 2020 SETAC.

Investigating arsenic impact of ACC treated timbers in compost production (A case study in Christchurch, New Zealand).

The arsenic concentration is an important issue in compost production. The main inputs of a compost factory, including kerbsides, green wastes, food industry wastes, and river weeds are investigated in this study. Also, this study investigated how treated timbers, ashes, and other contamination can impact arsenic concentration in compost production. The results showed that most treated timbers and all ashes of treated and untreated timbers contained significant amounts of arsenic. These results revealed that the presence of a small amount of treated timber ashes can significantly increase the arsenic concentration in composts. The results of the study show the arsenic concentration in compost increase during cold months, and it dropped during summer, which would be mostly because of high arsenic concentration in ashes of log burners. This study shows ashes of burning timbers can impact arsenic contamination mostly because of using Copper-Chrome-Arsenic wood preservatives (CCA). Also, the lab results show the arsenic level even in ashes of untreated timber is around 96 ppm. The ashes of H3, H4, and H5 treated timbers contain approximately 133,000, 155,000, and 179,000 ppm of arsenic, which one kg of them can increase arsenic concentration around 10 ppm in 13.3, 15.5 and 17.9 tons of dry compost products. The main problem is many people look at ashes and treated timber as organic materials; however, ashes of treated and untreated timbers contained high concentrations of arsenic. Therefore, it was necessary to warn people about the dangers of putting any ashes in organic waste bins.

Young adolescents' responsiveness to sexual communication with their mother: Distinguishing diverse intentions.

INTRODUCTION: It is unlikely that parents can have effective sexuality discussions with their adolescent if the adolescent is not responsive to their efforts. We evaluated young adolescents' intentions of being responsive to sexual communication with their mother and whether youths who were likely, ambivalent, or unlikely to be responsive differed on their characteristics, features of previous sexual communication, and features of the mother-adolescent relationship. METHODS: Participants were 259 Canadian adolescents (12-14 years; 53% girls) who received and returned a survey by mail. They completed measures of responsiveness intentions, expected outcomes of sexual communication, extent of past sexual communication, the frequency with which mothers encouraged questions and provided information about sexuality topics, open communication, and mothers' provision of warmth, structure, and autonomy support. RESULTS: We found that 37% of adolescents were likely to be responsive to sexual communication with their mother, 34% were ambivalent, and 29% were unlikely to be responsive. Youths' responsiveness intentions were general rather than topic-specific. A discriminant analysis showed that only features of previous sexual communication separated all three groups whereas specific mother-adolescent relationship features (open communication and structure) and one adolescent characteristic (expected outcomes) separated the unlikely group from the other groups. CONCLUSIONS: Young adolescents' intentions of being responsive to sexual communication from their mother are diverse yet general in nature. Mothers' engagement in sexual communication appears essential for youths' openness to these discussions. Enhancing specific mother-adolescent relationship features and youths' outcome expectations may shift adolescents who are resistant to sexuality discussions to being more sure.

Environmental and edaphic factors affecting soil cadmium uptake by spinach, potatoes, onion and wheat.

The relative ease with which cadmium (Cd) in agricultural soils can transfer to crop plants can pose a potential health risk to consumers. However, efforts to predict and mitigate these risks are often confounded by the various factors that influence metal accumulation in the edible plant parts. The aim of this work was to identify key drivers that determine Cd concentrations in spinach leaves, potato tubers, onion bulbs and wheat grain grown in commercial horticultural operations across New Zealand (NZ). Paired soil and plant samples (n = 147) were collected from farms across different NZ growing regions. Cadmium concentrations in the edible parts were measured and four different tests were used to examine the potential bioavailability of soil Cd: pseudo-total and porewater concentrations, 0.05 M Ca(NO3)2-extraction and diffusive gradients in thin-films (DGT). Information on a range of soil and climatic variables was also collected. The methods' ability to represent Cd concentrations in the plant parts was assessed through single and multiple regression analysis that considered the different variables and the farm locations. Soil Cd concentrations determined by the different tests were positively related to plant concentrations and there were clear regional differences between these relationships. The Ca(NO3)2 extraction predicted over 76% of the variability in Cd concentrations in onion bulbs and spinach leaves, while DGT and porewater Cd provided the best estimates for potato tubers and wheat grains, respectively, once regional differences were considered, along with certain environmental and soil variables. The results show that certain soil and environmental factors can be a key influence for determining Cd accumulation in the edible parts of some plants and that regional differences are important for modulating the extent to which this occurs. These effects should be considered when trying to mitigate the potential risks arising from Cd in agricultural soils.