Orals: Thu, 1 May | Room 0.51
Several anthropogenic activities, such as agricultural practices, industrial activities and urbanisation, release pollutants that pose a significant threat to ecosystems and living organisms and compromise soil health and related ecosystem services. Among these pollutants, metals like arsenic (As), cadmium (Cd), chromium (Cr), lead (Pb), copper (Cu), and nickel (Ni) are widely present in the soil as toxic and long-term persistent elements. Currently, 2.8 million sites are potentially contaminated, with many more suspected to be at risk. Even the effects of climate change, associated with global warming and extreme events, can also alter the physical, chemical and biological properties of soils, with implications for the redistribution and transformation of metals. Phytoremediation offers a sustainable, in-situ, and eco-friendly solution by using plants to remove or immobilize contaminants. While the primary focus of this technique is soil reclamation using common (hyper)accumulator plants, aspects such as aesthetics and social acceptance are often overlooked. Ornamental plants with phytoremediation potential could be a promising alternative, as they not only clean metal-contaminated soils and reduce biomagnification risks but also deliver multiple ecosystem services. The remediation capacity of these plants and their exploitation in polluted areas is poorly documented. For this reason, the aim of the study is to perform a systematic review on ornamental or hyperaccumulator plants with the ability to accumulate metals from soil. A total of 83 articles were checked using selected keywords (e.g., phytoremediation, polluted soil, ornamental plants), and 130 taxa were analysed in terms of metal accumulated, physico-chemical strategies adopted by the plants, type of soil tested, invasiveness, geographical distribution, and aesthetic value. In general, plants are exposed to moderate to high metal concentrations in soils, often largely exceeding the law limits. Responses to metals are generally species-specific, with some exceptions concerning the accumulation of multiple metals by a single plant. For Cd uptake, Zinnia elegans Jacq. (129,18 mg/kg in root, 109,89 mg/kg in shoot) and Calendula officinalis L. (1084 mg/kg in root, 383 mg/kg in leaves) are utilized. In contrast, for Pb remediation, Dianthus barbatus L. (80–580 mg/kg in root, 414,3–843 mg/kg in shoot) and Rubus ulmifolius Schott. (248–1178 mg/kg in root, 25–49 mg/kg in leaves) show accumulation abilities for that metal. These species have been tested under various experimental conditions and soil concentrations, while their geographical distribution and ability to grow in different biomes make them suitable for different environmental conditions. Although these plants show potential for use in polluted areas, would be useful to carry out further studies that examine their ability to synergistically accumulate metals in multi-contaminated sites in different environmental contexts.
How to cite: Conte, C. and Roccotiello, E.: Can we exploit ornamental plants for phytoremediation purposes? , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19032, https://doi.org/10.5194/egusphere-egu25-19032, 2025.
This study highlights the potential of safflower (Carthamus tinctorius) to achieve robust growth and biodiesel production under extreme heavy metal contamination. A 90-day pot experiment was conducted under greenhouse conditions using multi metal-contaminated soil sourced from former metal mines in Lavrio, Greece, a globally renowned site for its metal extraction history. Treatments included a non-contaminated control, a 1:2 mix of non-contaminated and contaminated soil, a 2:1 mix of the same soils, and a treatment with contaminated soil only. The concentrations of heavy metals in the soil were as high as: Ag (0.44–41.2 mg kg⁻¹), As (7.46–10,886 mg kg⁻¹), Cd (0.56–301.7 mg kg⁻¹), Cu (9.47–1,352 mg kg⁻¹), Zn (62.2–56,834 mg kg⁻¹), Pb (46.1–41,731 mg kg⁻¹), and Sb (0.99–322.33 mg kg⁻¹). Remarkably, safflower did not exhibit significant reductions in biomass or growth across treatments, as evidenced by growth indices such as absolute growth rate and growth ratio. The plant also accumulated significant amounts of metals, surpassing hyperaccumulation thresholds for Zn, Cd, and Pb. Light microscopy examination revealed no notable changes in root morphology or cell structure. Furthermore, negligible amounts of metals were detected in the derived seed oil. These findings demonstrate that safflower is a highly promising candidate for cultivation in heavy metal-contaminated soils, producing substantial biomass under harsh conditions and delivering a safe, biodiesel-compatible end product.
How to cite: Kikis, C., Giannoulis, K., and Antoniadis, V.: Phytomanagement capabilities of safflower (Carthamus tinctorius) after morphological examination and cultivation in multi metal-contaminated soil from former mines in Lavrio, Greece., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5162, https://doi.org/10.5194/egusphere-egu25-5162, 2025.
Cadmium (Cd) contamination in agricultural soils raises concerns due to its toxicity and mobility in the soil-plant system. A recent soil incubation study found that future climate conditions may further increase Cd mobility in soil [1], but the resulting consequences for its transfer to plants and the human food chain remain unknown.
Here, we investigate the impact of climate change on Cd accumulation by spinach (Spinacia oleracea), chosen as a model plant for leafy crops. Spinach is recognized as a significant source of essential micronutrients yet it also accumulates Cd, even up to toxic levels in edible parts. Four spinach varieties were cultivated in soils with diverse geochemistry and Cd levels under ambient climatic conditions (20°C daytime temperature, ambient atmospheric CO2 and 50% water holding capacity) and anticipated future climatic conditions (+2.25°C, +290 ppmv CO2, and 7% less gravimetric water content, [2]).
Three out of four spinach varieties produced significantly higher edible biomass under future climatic conditions than under current conditions. This biomass increase was accompanied by significantly elevated Cd concentrations in the edible parts of all spinach varieties. Transfer factors (soil-to-root and root-to-shoot) indicate that the higher shoot Cd levels were primarily driven by enhanced Cd movement across the soil-root interface, coupled with an increase in the mobile Cd fraction in the soil. Metabolite profiling of the rhizosphere revealed elevated levels of organic acids and metal chelators under future conditions, which mobilized Cd through pH modifications and chelation. Increased plant-derived metabolites, particularly carbon sources, coupled with higher temperatures, promoted microbial growth, as indicated by higher microbial 16S rRNA transcript levels and elevated Krebs cycle metabolites in the soil. This rise in soil microbial metabolism may enhance soil turnover and decomposition, ultimately increasing Cd mobility in soil.
Our findings provide insights into problematic future Cd accumulation in spinach, with potential relevance to other leafy vegetables. This highlights the critical need to address soil contaminants in assessing the impact of climate change on food safety.
[1] Drabesch et al. (2024). Climate-induced microbiome alterations increase cadmium bioavailability in agricultural soils with pH below 7. Communications Earth & Environment.
[2] IPCC (2021). Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report.
How to cite: Pieńkowska, A., Glöckle, A., Sánchez, N., Khadela, S., Richter, P.-G., Merbach, I., Herzberg, M., Prada Salcedo, L. D., Reitz, T., and Muehe, E. M.: Climate change-induced cadmium accumulation in spinach., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13116, https://doi.org/10.5194/egusphere-egu25-13116, 2025.
Limited soil moisture negatively affects the zinc (Zn) bioavailability to roots by impacting Zn diffusion (mobility) which may severely diminish Zn accumulation in edible parts of plants such as grains. Therefore, soil moisture drought poses a critical threat to Zn nutrition of plants and agronomic Zn biofortification strategies that aim at enhancing grain Zn concentrations. Foliar Zn application represents an alternative solution by bypassing adverse soil conditions and increasing grain Zn concentrations. While foliar Zn application has been shown to enhance grain Zn concentration under drought stress, it remains unclear how soil moisture drought influences foliar Zn uptake and translocation processes in crops. Furthermore, although the agronomic effectiveness of foliar-applied Zn has been well-studied using isotope tracers, similar investigations under soil moisture drought are lacking. Addressing this gap will contribute to optimization of foliar Zn application strategies, especially under stressful environmental conditions.
This ongoing study aims to quantify the agronomic effectiveness of foliar-applied Zn in wheat (Triticum aestivum) under conditions with and without soil moisture drought using stable isotope tracing. A pot experiment was conducted by using two wheat cultivars, Katya and Diavel, differing in drought stress tolerance. Plants were subjected to soil moisture drought in a controlled greenhouse environment, and a 66Zn labeled Zn sulfate fertilizer was applied to the flag leaves at flowering stage. In this study, yield parameters were already determined, and Zn concentrations in different plant tissues will be measured in ICP-OES. Leaf properties, such as trichome and stomatal density, were also analyzed using a scanning electron microscope. By measuring 66Zn: 64Zn isotope ratios in different bulk plant tissues using a high resolution ICP-MS, we precisely quantified the transfer of foliar-applied Zn to grains and other plant parts. Additionally, 66Zn: 64Zn isotope ratios within the flag leaves were mapped using laser ablation (LA)-ICP- time-of-flight mass spectrometry (TOFMS), providing detailed insights into the fate of foliar applied Zn at the microscale.
Preliminary results indicate distinct responses to drought stress between the two cultivars. Under drought stress, Katya exhibited higher drought tolerance than Diavel, evidenced by its lower leaf water potential. Traits of Katya such as greater root biomass, shorter leaf length, higher trichome density, and lower stomatal density than Diavel further supported this observation LA-ICP-TOFMS results revealed that drought increased the transfer of foliar-applied Zn within the flag leaves in Diavel. In contrast, drought reduced the transfer of Zn within the flag leaves in Katya. Moreover, source tracing with stable isotopes revealed that drought reduced the transfer of foliar applied Zn to grains, particularly in Katya. These preliminary findings suggest that drought stress modifies the mobility and partitioning of foliar-applied Zn, with cultivar-specific traits playing a crucial role. At the conference, we will present the complete dataset and discuss the implications of our findings for improving Zn biofortification strategies in wheat under drought stress.
How to cite: Wang, L., Becker, P., Archer, C., Cakmak, I., Günther, D., Frossard, E., and Wiggenhauser, M.: Isotope tracing and microscale mapping to investigate the fate of foliar applied zinc in wheat under drought stress, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8858, https://doi.org/10.5194/egusphere-egu25-8858, 2025.
A nutritious and healthy diet relies on consuming cereals with sufficient micronutrient content, making the production of nutrient-rich crops a crucial agricultural goal. Identifying key strategies for plant micronutrient acquisition is essential, and this is especially critical for regions where calcareous or nutrient-deficient soils limit micronutrient bioavailability.
Plants can enhance nutrient uptake by increasing exploration of the soil volume through root growth or by releasing root exudates that facilitate nutrient mining. Barley, along with other gramineous plants, employs an efficient strategy to mobilize micronutrients which is based on chelating agents called phytosiderophores (PS). While the role of these compounds in iron acquisition is well known, their function in zinc (Zn) nutrition is unclear. Furthermore, root-associated microorganisms are also known to interplay on the plant's micronutrient status either by enhancing the general plant health or directly making micronutrients bioavailable.
This study aimed to identify key root traits for an efficient Zn acquisition in barley. Sixteen barley genotypes with diverse genetic backgrounds were grown in a Zn-deficient soil. Total carbon and nitrogen exudation were measured, and PS quantification as well as characterization was performed. To investigate the root-associated microbiome, amplicon sequencing of the 16S rRNA gene and the ITS2 region was conducted. PS exudation showed a positive correlation with barley Zn shoot concentration highlighting its potential role in plant Zn nutrition. While root-associated microorganisms were influenced by the plant’s micronutrient status, we didn´t see clear evidence of their role in plant Zn nutrition. These findings provide valuable insights about plant-soil-microbe interaction for nutrient-efficient crop production.
How to cite: Otxandoregi-Ieregi, U., Spiridon, A., Aleksza, D., Escudero-Martinez, C., Woebken, D., George, T. S., Russell, J., Causon, T., Hann, S., Stanetty, C., Kratena, N., and Oburger, E.: Unraveling zinc acquisition strategies in barley: the role of phytosiderophore exudation and root-associated microbiome, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19741, https://doi.org/10.5194/egusphere-egu25-19741, 2025.
Micronutrient (MN) deficiencies, particularly of iron (Fe), zinc (Zn), and copper (Cu), are major constraints to crop productivity in arid and semi-arid regions characterized by high-pH calcareous soils. Effective strategies for acquiring MN are essential to ensure high yields on nutrient-depleted soils and produce MN-rich crops. In the case of iron, grass species (Poaceae) increase Fe phytoavailability by releasing root exudates called phytosiderophores (PS), which have the capability to chelate and mobilize Fe from the soil, thereby facilitating its uptake by plants. So far, eight naturally occurring PS compounds have been identified among the Poaceae: mugineic acid (MA), 3"-hydroxymugineic acid (HMA), 3"-epi-hydroxymugineic acid (epi-HMA), hydroxyavenic acid (HAVA), deoxymugineic acid (DMA), 3"-hydroxydeoxymugineic acid (HDMA), 3"-epi-hydroxydeoxymugineic acid (epi-HDMA) and avenic acid (AVA). Given the commercial unavailability of all eight PS, research until now has largely focused on DMA and, occasionally, MA, primarily in relation to Fe acquisition, with much of the research conducted under artificial conditions like hydroponics. These limitations restrict our understanding of the PS-MN acquisition mechanisms involving other PS types, the diversity of PS released by different grasses, and their molecular responses. Additionally, it remains unclear how these findings translate to natural soil conditions or what happens to PS once released into the soil.
With access to the full set of chemically synthesized PS, we conducted experiments to explore PS biosynthesis and exudation across grass species (e.g., barley, rye, oat, sorghum) under Fe, Zn, or Cu deficiency in both hydroponic and soil systems. We assessed the efficiency of each PS in mobilizing these MNs through soil interaction experiments conducted in MN-deficient soils.
Our findings indicate that PS biosynthesis and exudation exhibit species-specific and genotype-dependent variations. Focusing on barley and supported by root gene expression data (RNAseq), we found a stronger PS pathway response in a MN efficient genotype compared to an inefficient line. Additionally, our soil-PS interaction experiments revealed that PS-aided metal mobilization is specific to soil type. Despite the structural similarities among the eight PS, we observed differences in their metal mobilization efficiencies, which were both time and PS-concentration dependent. Our findings offer valuable insights into the complex dynamics of the PS-mediated MN acquisition mechanism. These novel insights into plant MN nutrition can serve as a foundation for future studies as well as to develop breeding programs tailored to thrive in MN-deficient soils.
How to cite: Spiridon, A., Aleksza, D., Causon, T., Hann, S., Kratena, N., Stanetty, C., and Oburger, E.: Wanted: Micronutrients – Exploring the phytosiderophore pathway for micronutrient acquisition in plant-soil systems, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10032, https://doi.org/10.5194/egusphere-egu25-10032, 2025.
Natural soil colloids can play a substantial role in the mobility and bioavailability of trace metals. However, the understanding of their role as carrier is hampered by sampling artefacts of these colloids in traditional soil solution sampling methods, including changes in the in situ soil environment by extraction or centrifugation. To overcome this, a method based on the Diffusive Gradients in Thin films (DGT) technique is being developed to enable in situ sampling of colloids in undisturbed soil. Spatially resolved analysis of a DGT binding layer with laser ablation-ICP-MS will allow high-resolution mapping of free and colloid-associated metal distributions in soil. Different new types of DGT binding gels were synthesised and tested for their ability to accumulate organomineral colloids of iron (Fe) oxides associated with natural organic matter (NOM). These Fe-NOM colloids are expected to adsorb onto metal oxide binding gels used for anionic species in DGT, via interactions with negatively charged carboxylic and phenolic hydroxyl reactive groups of the NOM. Colloids experience slow diffusion due to their size and might be outcompeted for sorption by oxyanions, e.g. phosphate (PO4). Therefore, a high colloid binding capacity is required to ensure sufficient colloid detection on the binding gel. Sorption tests showed that Fe-NOM colloids can be accumulated by the in situ precipitated zirconium oxide (ZrO2) binding gel based on the ZrOCl2 precursor that is currently being used in PO4 DGTs. With respect to this binding layer, the increase of the ZrO2 concentration was found to have the most remarkable effect on the general binding capacity, as the total PO4 sorption capacity increased linearly with increasing Zr content in the gel. A novel approach, the in situ precipitation of metal oxides from Zr, titanium (Ti) and niobium (Nb) chloride and n-butoxide precursors instead of ZrOCl2, did not significantly enhance either the general capacity or the affinity for Fe-NOM colloids of binding gels. In addition, the Fe-NOM colloid sorption was not significantly enhanced by adaptation of the agarose derivative-crosslinked polyacrylamide (APA) hydrogel by mixing the non-ionic adsorbent polyvinylpyrrolidone (PVP) within the matrix. Moreover, hydrogels based on agarose instead of APA did not promote sorption of larger-sized Fe oxide colloids (50 nm) to a significant extent, despite the larger pore sizes in agarose compared to APA hydrogels. Finally, the in situ precipitated 0.1 M ZrO2 binding gel showed a linear uptake of small Fe-NOM colloids in time and concentration. This gel is, therefore, a promising DGT binding layer for high-resolution imaging of NOM-based Fe oxide colloids with associated trace metals in soil.
How to cite: Ceulemans, J., Moens, C., and Smolders, E.: Novel DGT binding layer for organomineral colloids to identify their role in trace metal mobility in soil, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10944, https://doi.org/10.5194/egusphere-egu25-10944, 2025.
Mobile colloids of clay, oxides and organic matter can play a major role in nutrient and contaminant mobility in soil, though their true role remains unclear due to biases in sampling methods. Sampling colloids in soil is challenging because current methods disrupt the soil structure, colloids are retained in sampling devices and/or extraction methods change the in situ environment.
The Diffusive Gradients in Thin Films (DGT) method allows in situ sampling of solutes in soil. The DGT consists of a hydrogel diffusive layer for controlled diffusion to an analyte-specific binding layer that accumulates solutes when applied in soil. Analyzing the binding layer with a spatially-resolved method, like Laser Ablation (LA)-ICP-MS, reveals the 2D distribution of solutes in soil solution at micrometre resolution.
This study aims to develop the imaging DGT technique to sample not only solutes, but also mobile colloids, in undisturbed soils. We speculate that this method will improve our understanding of the migration of compounds in soil compared to established methods because it visualizes local colloid and solute concentrations at sub-mm scale. This was tested in the plough pan of soil from a long-term field trial with manure application where we anticipated identifying hotspots of colloidal phosphorus (P) release associated with anaerobic microsites, in line with previous research. The DGT setup consisted of a 9 µm thick membrane, which provides a short diffusion length to increase the sensitivity for colloids, which have slow diffusion rates. The large membrane pore size cutoff of 1 µm allows unrestricted passage of colloids (< 200 nm), which we showed are retained in hydrogel diffusive layers. The DGT used a zirconium oxide-based binding layer previously developed for phosphate, which we identified as the best-performing binding layer for organomineral iron (Fe) colloids.
Sampling was done in winter 2023-2024 when the annual drainage was at a record high due to high rainfall and low evapotranspiration. We unexpectedly detected mobile clay mineral colloids on the DGT by using advanced LA-Time-Of Flight (TOF)-MS. This fast non-target elemental analysis allowed us to identify clay colloids from the co-localisation of Al, Si, Rb and Cs (and not P) and is the first image of mobile colloids in soil. The presence of clay colloids is underpinned by colloid analysis of pore water extracted from the same soil using Field Flow Fractionation analysis. The low Ca concentration (< 1 mM) in soil solution related to prolonged winter rainfall, not the presence of anaerobic microsites, likely explained the nature of these mobile colloids.
Further experiments are currently being undertaken to understand clay colloid uptake on the DGT binding layer. The DGTs are deployed in suspensions with purified native clay colloids and pore water colloids from the plough layer at various deployment times to assess clay colloid accumulation and the method’s suitability for measuring mobile clay colloids in soil.
How to cite: Moens, C., Payne, J., Doolette, C., Lombi, E., and Smolders, E.: Visualization of local concentrations of mobile soil colloids: advancing the Diffusive Gradients in Thin Films Method, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13078, https://doi.org/10.5194/egusphere-egu25-13078, 2025.
Zinc (Zn) is an essential micronutrient, while cadmium (Cd) is a highly toxic pollutant. Due to their chemical similarity, both metals are absorbed by plants through the same pathways, including membrane proteins and vascular tissues. Plants mitigate Cd toxicity by chelating Cd with thiol-rich organic ligands and proteins, such as metallothioneins (MTs). Recent studies have shown that Zn and Cd isotopes are inversely fractionated in cereals like wheat and rice, with grains accumulating light Zn and heavy Cd isotopes. As Cd-thiol complexes are more stable than Zn-thiol complexes, we hypothesize that thiols separate Cd from Zn in living organisms, reflected in the ‘isotope fingerprint’ of these metals.
To test this hypothesis, we analyzed in a first step the Cd and Zn isotope composition in chickpea metallothionein (cicMT2). This is a model metallothionein and thiol for in vitro studies. To this end, cicMT2 was recombinantly expressed in E. coli cells with a GST tag for purification purposes, which was subsequently cleaved to obtain the native protein sequence. Metal-free cicMT2 was incubated with Cd(II) and Zn(II) ions for different equilibration times. After separating the unbound metal ions using size exclusion chromatography, the protein samples were measured for Cd and Zn isotope composition using a multi-collector ICP-MS. The isotope fractionation between the free and complexed metals at isotope equilibrium was Δ114/110Cdfree-MT = 0.56 ± 0.21‰, reached after 8 h of incubation, and Δ66/64Znfree-MT = 0.87 ± 0.41‰ within the first 10 min of incubation. Our findings indicate that cicMT2 significantly fractionates Cd and Zn isotopes, showing a preference for lighter Cd and Zn isotopes in the cicMT2 complex.
In a second step, we recombinantly expressed cicMT2 in the living model organism E. coli and compared the growth and metal uptake with a wild-type (non-producing MT) strain under different Cd and Zn concentrations. E. coli expressing cicMT2 accumulated over four times more Cd and Zn than the wild-type strain without reducing the growth rate. At high Cd concentrations, the separation of Zn and Cd in E. coli with cicMT2 (Zn:Cd = 1.04) is 19% more pronounced when compared to the wild-type (Zn:Cd = 0.88). This first data suggests that the model thiol cicMT2 plays a role in separating Zn from Cd in a living organism. Until the conference, the isotope composition of Zn and Cd in E. coli will be determined to further elucidate the role of cicMT2 to separate Zn from Cd.
How to cite: Gomes Brito, F. A., Marquez Espinoza, A., Freisinger, E., Sarret, G., and Wiggenhauser, M.: The Role of a Plant Metallothionein (MT) in Separating Cadmium (Cd) and Zinc (Zn) in E.Coli Using Isotope Process Tracing , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16208, https://doi.org/10.5194/egusphere-egu25-16208, 2025.
A sound evaluation of the cadmium (Cd) mass balance in agricultural soils needs accurate data of Cd leaching. Reported Cd concentrations from in situ studies are often one order of magnitude lower than predicted by empirical models, which were calibrated to pore water data from stored soils. It is hypothesized that this discrepancy is related to the preferential flow of water (non-equilibrium) in the field and/or artefacts caused by drying and rewetting soils prior to pore water analysis. These hypotheses were tested on multiple soils (n=27) with contrasting properties. Pore waters were collected by soil centrifugation from field fresh soil samples and also after incubating the same soils (28 days, 20°C), following two drying-rewetting cycles, the idea being that chemical equilibrium in the soil is reached after incubation. Incubation increased pore water Cd by a factor 4, on average, and up to a factor 16. That increase was statistically related to the decrease of pore water pH and the increase of nitrate, both mainly related to incubation-induced nitrification. After correcting for both factors, the Cd rise was also highest at higher pore water Ca. This suggests that higher Ca in soil enlarges Cd concentration gradients among pore classes in field fresh soils, possibly because high Ca promotes soil aggregation and separation of mobile from immobile water. Several empirical models were used to predict pore water Cd. Predictions exceeded observations up to a factor of 30 for the fresh pore waters but matched well with those of incubated soils; again, deviations from the 1:1 line in field fresh soils were largest in high Ca (>0.8 mM) soils, suggesting that local equilibrium conditions in field fresh soils are not found at higher Ca. Our results demonstrate that empirical models need recalibration with field fresh pore water data to make accurate soil Cd mass balances in risk assessments.
How to cite: Bergen, B., Moens, C., and Smolders, E.: Soil incubation can artificially increase cadmium concentrations in pore waters and deviate from field conditions, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17318, https://doi.org/10.5194/egusphere-egu25-17318, 2025.
Posters on site: Thu, 1 May, 10:45–12:30 | Hall X3
Sewage, animal feces, heavy metals, pathogenic microbes, and other pollutants can contaminate floodwater. Fresh vegetables that have been submerged in floodwater or that might have been exposed to contaminated water are not safe to consume. Pollutants may enter plant tissues in addition to being on the outside of fruits and vegetables. In autumn of 2024, there were great floods in central Bosnia and Herzegovina. The aim of this study was to determine the effect of floods on heavy metals and microbe content in the soil and plant tissue. 20 samples of soil and sludge were prepared by extraction with agua regia and DTPA, for measurement of pseudo-total and available amounts of metals. Samples of chard were taken from flooded area and from area outside of floods (controls). The chard samples were divided to roots stems and leafs. The quantity of seven heavy metals (Cu, Zn, Ni, Co, Pb, Cd, Fe, Cr and Mn) were measured by means of Atomic Absorption Spectroscopy with flame atomization (FAAS). The total bacterial count was determined using R2A agar, while the Most Probable Number (MPN) method was applied for quantifying total coliforms and spore-forming bacteria. CN analyzer measured total content of C and N. The average concentrations of metals followed the sequence Cd<Co<Cr <Cu<Ni<Zn <Pb<Mn<Fe. The sludge mostly was not higher in heavy metals than soil, but it had higher amounts of C, N, Ni and Co. Soil samples showed high background concentrations of Pb and Cd and in some cases concentrations were higher than permissible amounts. In plants, highest concentrations of heavy metals were found in roots and leafs. Zn, Mn and Co had positive (root/shoot) translocation factor in all cases. The highest total bacterial count, exceeding log 8, was observed in three soil samples. In contrast, two samples of sludge exhibited a significantly lower bacterial abundance, falling below log 3. In some cases, chard had amounts of Cd higher than permissible, but it is not a consequence of flooding. Flooding increased C, N, Ni and Co and decreased bacterial count.
How to cite: Jurković, J., Sijahović, E., Alkić-Subašić, M., Čivić, H., and Bašić, F.: Heavy metals and microbiological assessment of soil-plant system of flooded areas applied on the chard (Beta vulgaris), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9402, https://doi.org/10.5194/egusphere-egu25-9402, 2025.
The majority of traditional soil analyses disrupt the soil structure to diagnose soil quality, toxicity or nutrient requirements. They are based on batch extractions on dried, sieved and homogenized samples. However, opening up the soil structure overestimates the reactive surface that controls nutrient and contaminant availability. It is unclear if soil structure needs to be accounted for in bioavailability assessment. This study was set up to quantify the effects of soil structure on the mobility and the plant availability of five different trace metals, thereby using soils that are either or not disturbed by sieving and using both added metals and metals naturally present in soil. Maize was grown in 7.4 L soil columns spiked with 62Ni, 65Cu, 70Zn, 108Cd and 204Pb isotopes added to the soils as spike solutions with 2.2 mm initial irrigation. Five different types of soil and three degrees of disturbance were used: intact soil columns, soil sieved at 8 mm, and soil sieved at 2 mm. Soil analyses showed deeper and more variable penetration of metal isotopes in undisturbed than in sieved soils, logically related to macropores in the former. Maize plants grown on intact soils contained higher concentrations of spiked metal than those grown on sieved soil, with mean differences (among soils) ranging between 1.5 (Ni) and 3.8 (Cu). This indicates an increased availability of freshly added metal in the intact soils compared to sieved soils due to the higher reactive surfaces in the latter and due to the colocalization of the spike with the roots in macropores. Conversely, for the native metal, the trend was reversed; more native metal was taken up in the sieved treatments, and differences were highest (almost factor 2) for Cd. The second effect can be explained by an increased contact area between roots and soil due to sieving, thereby reducing the diffusion limitation of the native metals from soil to roots. This study shows that soil structure affects trace metal bioavailability and suggests that soil testing for bioavailability may need to be revisited to account for this effect.
How to cite: Garcia, S., van Dael, T., and Smolders, E.: The effect of soil structure on the bioavailability of trace metals, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11512, https://doi.org/10.5194/egusphere-egu25-11512, 2025.
Due to increasing interest in lithium, and before a possible era of more intense use, a compilation of respective data from multi-element datasets of the author seems to be needed. All data have been obtained from ICP-OES, run against matrix-matched calibrants. Average global abundances of 22 mg/kg in the Upper crust, 13 mg/kg in the Lower crust and 18 mg/kg in the Continental crust rely on total decomposition digests. After weathering, Li is quickly removed from solution by clay minerals and Fe-oxides, but hardly by organics. Total digestion data of 24432 stream sediment of Slovakia showed an elevated occurrence of Li in the High and Lower Tatra mountains and in the Beskides (34-70 mg/kg), whereas in the Lowlands it ranged largely within 22-29 mg/kg. Similarly in Austria, stream sediments in the Pre-alpine Lowland ranged within 16-26 mg/kg, and in the limestone Alps within 5-16 mg/kg.
In soils, however, aqua regia digestion or alternatively, pressure digestion with K-chlorate in dilute nitric acid, is commonly used, which resulted in a median recovery of 57 % (range 44-100%) in apple orchard soils, and of about 54% in a calcareous fluvisol, which had been treated by various fertilization regimes. In these digests, Li is positively correlated with K, Sc, Y, Al, La, Ni, Cr and Tl, but negative or independent versus Ca, Sr, Ba and organic carbon. In profiles of wood soils from the South of Carinthia, both increase and decrease of aqua regia soluble Li was noted versus depth.
In urban soils and road dusts, Li had been detected within the range of arable soils, no enrichments had occurred.
In mobile soil fractions, Li mobility is quite low. Data obtained from various extracts like CAL (Ca-acetate-lactate), dilute acetic acid or ammonium acetate will be compared: In CAL, released Li corresponds with Na, while it is largely independent from Mg, Sr and Ba. In orchard soils, just 0,52% of total (range 0,12-1,17%) were released by 0,16M acetic acid, and in subsequent oxalate extract pH 3 just 1,38% (range 0,41-6,27%) as medians, and in the carbonaceous fluvisol, the acetic acid released even only 0,36%, and subsequent oxalate 0,20% of total.,
In fertilizers, based on NH4, K and Mg salts, median occurrence of Li is below 0,5 mg/kg. in NPK fertilizers about 1 mg/kg, and in composts 14 mg/kg. Thus, there is no significant Li input into soils from fertilization. Median inputs for 100 kg N/ha or 100 kg P/ha increase from mineral fertilizers to commercial organics, to manures and dungs, to composts. Slight but insignificant changes between different geological locations appeared among the composts.
Addition of NPK fertilizer leads to mobilization of Li by ion exchange. From columns of chernozem soils, a Li peak occurred after passage of one pore volume of eluting water.
Animal feedstuffs contain Li within the same concentration ranges as mineral fertilizers, with medians from 0,6 to 2,0 mg/kg. The concentration ranges are largely overlapping with respect to target animals, both for composite and supplementary feeds. The stomach-contents of wild ducks shot in 4 areas of Austria, contained Li within the same range as commercial feedstuffs for chicken or turkeys. Because basic feeds like grass-silage may contain higher Li-levels, concentrations in manures, dungs and composts may be also higher.
Li levels in meat and vegetables have been found largely overlapping at about 10-70 µg/kg of dry mass, which means about 1- 7 µg/kg in wet weight. Higher levels can be (but need not be) met in processed cheese, as well as in horse meat and deer. Like for most elements, honey contains the presumably lowest Li level, at a median of 3,5 µg/kg (range <0,1 - 30 µg/kg), at almost dry weight.
Data from cereals, potatoes, tomatoes, carrots, milk, cheese, various kinds of meat, and honey will be presented.
How to cite: Sager, M.: Lithium in agriculture, environment and food, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4881, https://doi.org/10.5194/egusphere-egu25-4881, 2025.
Arsenic (As) and mercury (Hg) contamination in the Asturias region, northern Spain, represents a significant environmental issue that has been extensively studied in recent decades. Mining and industrial activities, particularly those associated with Hg mining, as well as coal mining and iron or zinc metallurgical industries, have profoundly impacted the environment, as evidenced by paleoenvironmental records such as peat bogs. These pollution phenomena affect various environmental compartments, including soil. To mitigate the negative impact of these two highly toxic and carcinogenic pollutants in soils, phytoremediation technology has been developed using Betula pubescens (birch), including field experiments in different polluted sites along the region.
In recent years various activities in the region have also led to the release of another type of contaminant classified as emerging: microplastics. Studies conducted in the area have revealed their presence in several environmental compartments, including marine sediments. Notably, microplastics are increasingly detected in soils, but their implications remain unclear. In fact, their interaction with other contaminants in complex mixtures is even less understood.
This study aimed to evaluate the impact of polyvinyl chloride (PVC) microplastics on soils contaminated with As and Hg. PVC, one of the most abundant polymers, poses a potential risk of interaction with Hg due to its Cl content. To this end, an experimental plot was established in a polluted soil under controlled conditions, and a dose of 1% of PVC microplastics was added. Phytoremediation of the soil was then performed using birch, with a control plot set up without the presence of microplastics. After two and eight months, sampling of the roots, leaves, and soil was conducted. The samples were analyzed to determine their As and Hg content, assessing the differences in pollutants accumulation in plants. Significant differences were observed between treatments, indicating that the presence of microplastics influenced the accumulation of As and Hg in plants. The presence of Cl in PVC microplastics may be a key factor in their interaction with Hg, thus, to elucidate this interaction, thermal programmed desorption of Hg (Hg-TPD) coupled with microscopic analysis of microplastics extracted from the soil will be employed, enabling a better understanding of the interactions between these two contaminants. This information is critical for evaluating their effects on the soil-plant system and the implications for the feasibility of phytoremediation techniques.
This work was supported by the Ministerio de Economía y Competitividad (MINECO, Spain) under the project I+D+i PID2020-113558RB-C43 (MCIN/AEI/10.13039/501100011033).
How to cite: Baragaño, D., Sánchez, S., Berrezueta, E., Rodríguez, E., González, A., Kovacs, T., and López-Antón, M. A.: Impact of PVC microplastics on phytoremediation of As and Hg polluted soils using Betula pubescens, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18350, https://doi.org/10.5194/egusphere-egu25-18350, 2025.
Mitigating potentially toxic elements (PTEs) contamination in post-mining land is essential for restoring the environmental health of post mining ecosystems. A comprehensive understanding of how post-mining topography and vegetation impact PTEs distribution can help devise targeted reclamation strategies to reduce PTEs toxicity.
This study investigated the influence of topographical regions of a post-mining overburden heap (top, middle, and bottom) and selected tree species (Azadirachta indica, Senna siamea, and Leucaena leucocephala) on the total and bioavailable fractions of PTEs in reclaimed coal mine soil from Eastern India.
The total concentration revealed that chromium (Cr: 226–354 mg/kg), cadmium (Cd: 1.37–1.92 mg/kg), mercury (Hg: 0.11–0.45 mg/kg), and zinc (Zn: 104–213 mg/kg) pose a significant potential risk across the site. These risks were supported by high geo-accumulation index values (Igeo > 1.0 for Cd, Cr, and Hg) and contamination factors (Cf). Despite this, bioavailable fractions of PTEs remained below 25%, with values for Cd (2.92–11.46%), Cr (0.10–0.22%), and Zn (5.15–22.4%), indicating reduced immediate ecological risk.
While topography did not significantly affect the pollution load index (PLI), tree species played a crucial role. Among the tree species studied, L. leucocephala exhibited the lowest PLI (0.95) and effectively reduced the bioavailable concentration of Cd under its canopy. These findings position L. leucocephala as a promising candidate for the revegetation of post-mining landscapes.
This study highlights the critical role of vegetation in regulating the concentration and bioavailability of potentially toxic elements (PTEs) in reclaimed mining soils, offering essential insights for developing sustainable strategies for post-mining land restoration and ecosystem rehabilitation
Keywords: slope, plant species, post-mining, landscape, toxic elements.
How to cite: Maurya, P., Masto, R. E., Agarwalla, H., Lamb, D., and Ferreiro, J. P.: Spatial Distribution of Potentially Toxic Elements in Reclaimed Post-Mining Soils: Impact of Topography and Tree Species, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8042, https://doi.org/10.5194/egusphere-egu25-8042, 2025.
Heavy metal pollution is a major challenge for the environment. It affects more than 30% of global freshwater systems and threatens biodiversity and human well-being. This study presents a comprehensive, interdisciplinary framework that integrates advanced geochemical and mineralogical methods to address this urgent problem and provide scalable solutions with global applicability.
Focusing on Aligudarz County in Iran's geologically active Zagros Mountains, 110 sediment samples were analyzed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and X-ray Diffraction (XRD). Results revealed the pivotal role of fine-grained silts and clays, particularly Illite and montmorillonite with high adsorption capacities, in heavy metal transport. Pollution indices, including the geo-accumulation index and the enrichment factor, indicate moderate to severe pollution by molybdenum, lead, cadmium and copper. Of particular concern are the traces of cadmium and lead, which pose an acute threat to ecosystems and human health and require immediate action.
This study presents a novel method for assessing heavy metal exposure by combining state-of-the-art analytical tools with robust statistical approaches. The results not only provide a basis for targeted mitigation strategies, but also serve as a model for shaping global environmental policy and improving international efforts to protect natural and human systems.
How to cite: joukar, A., Abbasi, S., Darvishi-Khatooni, J., and Pourmorad, S.: Integrated geochemical and mineralogical analysis of heavy metal pollution: A scalable model for global environmental challenges, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-623, https://doi.org/10.5194/egusphere-egu25-623, 2025.
Copper (Cu) is one of the seven essential micronutrients for plants, but its intensive use as a pesticide in agriculture, especially in organic and integrated production systems, has led to its progressive accumulation in European soils. This phenomenon poses a serious threat to soil biodiversity, water quality, and human health. Despite EU regulations limiting copper inputs to a maximum of 28 kg/ha over seven years (an average of 4 kg/ha/year), a significant amount of copper-based pesticides is still widely used, as they remain essential for controlling numerous fungal and bacterial diseases. However, their accumulation in soils and sediments has become an unsustainable environmental issue, particularly in Italy, Greece, France, and Spain, where agricultural land contamination is particularly high. The LIFE MICROFIGHTER project proposes an innovative solution to reduce or replace copper-based pesticides by demonstrating the efficacy of a new Zeo-Biopesticide, applied as a foliar treatment, composed of natural Italian zeolites (potassium chabazite) and a specific biocontrol microorganism (Pseudomonas sp. DLS65). The goal is to control major pathogens of grapevine, tomato, and olive (including downy mildew, bacterial speck, bacterial spot, olive knot, and peacock spot), exploiting Zeo-Biopesticide and hence reducing or avoiding the use of copper in organic and integrated agricultural systems. The efficacy of the method will be demonstrated with field trials (2-3 years duration) in Italy, Croatia, and Spain (a total of 9 fields).
The specific objectives of the project includes: i) reducing copper inputs in agricultural soils from an average of 4 kg/ha/year to 2 kg/ha/year without compromising crop yield and quality, with the potential for complete copper replacement; ii) demonstrating a reduction in total soil copper concentration while promoting increased soil biodiversity; iii) raising awareness among farmers, policymakers, and other stakeholders about the environmental and health risks associated with copper-based pesticides, and promoting the adoption of the Zeo-Biopesticide as an effective and sustainable alternative; iv) conducting environmental monitoring campaigns, life cycle analysis (LCA), and developing a business plan to assess the economic and environmental sustainability of the new technology.
To evaluate the effect of the zeo-biopesticide on copper reduction, copper concentrations in soils, both bioavailable and total, are determined in the first and third years of sampling through ICP-MS analysis. Additionally, other soil physico-chemical parameters, such as organic matter content, pH, electrical conductivity, and cation exchange capacity, will be measured to assess their correlation with copper concentrations. For better data visualization, distribution maps of total and bioavailable copper concentrations will be created for the different experimental fields. Currently, after one year of the project, the baseline has been established, and the corresponding distribution maps have been prepared. These data will be compared with those obtained after the second sampling to evaluate the actual reduction in copper and, consequently, the effectiveness of the zeo-biopesticide.
How to cite: Alberghini, M., Ferretti, G., Galamini, G., Botezatu, C., Faccini, B., Pignoni, E., and Coltorti, M.: Innovative Solutions for Reducing Copper-Based Pesticides in Sustainable Agriculture: The LIFE MICROFIGHTER Project, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5890, https://doi.org/10.5194/egusphere-egu25-5890, 2025.
Climate change is project to greatly affect food systems, including yield and quality of staple crops such as wheat. One key determinant of wheat grain quality is the concentration of metal micronutrients (e.g., Fe, Zn, Cu) and toxic elements (e.g., Cd, Pb). However, it is not yet known whether and to which degree climate change conditions will affect micronutrient and toxic element concentrations in wheat grains. We performed a wheat-growth pot experiment (Spring-Summer 2024) to determine the effect of future climatic conditions (approximately +4°C relative to ambient, decreased soil moisture) on wheat, Triticum aestivum L., grain quality and yield. To expand the applicability of our results, we used three agricultural soils with a wide range of chemical properties (soil texture, elemental composition) and two spring wheat and one winter wheat cultivar. To evaluate the potential availability of soil metals for uptake by the wheat, we measured soil pH and water-extractable metal concentrations at four time points throughout the experiment. Preliminary results showed that future climatic conditions led to faster wheat development, including a shorter time needed to reach full maturity. In pot soil, future climatic conditions led to slightly increased pH and had no effect on dissolved organic carbon (DOC). While this experiment is ongoing, our results will demonstrate how underlying plant and soil processes relate to wheat uptake of micronutrients and toxic elements. Overall, this study will provide insights whether the combined impacts of future climatic conditions and soil contamination will give cause to an additional threat to food security and balanced nutrition.
How to cite: Bachelder, J., Kaesler, J. M., and Muehe, E. M.: The effect of future change conditions on metal concentrations in wheat crops , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11007, https://doi.org/10.5194/egusphere-egu25-11007, 2025.
Soil cadmium (Cd) contamination is a widespread problem in Europe, disrupting plant growth, impairing microbial activity, and threatening human health. Phytoextraction using metal hyperaccumulating plants, like Arabidopsis halleri, offers a sustainable approach to mitigate Cd pollution in soils. However, the supply of essential nutrients for plant growth and metal hyperaccumulation is crucial for an efficient application of phytoremediation. Nitrogen (N), a key nutrient undergoing diverse microbially driven transformations in soil, is critical in this context. In addition to Cd contamination, climate change poses an emerging challenge to ecosystem nutrient cycling. While the individual effects of climate change and Cd on soil N-cycling have been studied before, their coupled impacts remain largely unexplored. Thus, this study aims to evaluate the coupled impacts of Cd and climate change on N-cycling in soils under phytoremediation with the metal hyperaccumulating plant A. halleri.
A controlled greenhouse pot experiment was conducted with A. halleri grown in three soils varying naturally in Cd levels under current and future climate conditions, simulated through elevated carbon dioxide concentrations and temperatures reflecting the IPCC SSP3-7 scenario (+3.5 ºC and +400 ppmv CO2 predicted to 2100 vs. preindustrial times). Rhizosphere and bulk soil samples were analyzed for metal concentrations, N-pools, and N-cycling functional gene abundances (nifH, chiA, amoA, nirK, nirS, nosZ).
No significant climate effects were found on N-dynamics, with Cd being the dominant factor influencing changes in soil N-cycling. Thus, Cd effects overrode climate effects on soil N-cycling. By stimulating N-mineralization and nitrification but decreasing the denitrification capacity, Cd shifted soil N-cycling towards nitrate. This shift may reflect an increased plant and microbial N-demand for metal detoxification. Furthermore, the higher abundance of the amoA gene of ammonia-oxidizing archaea (AOA) compared to ammonia-oxidizing bacteria (AOB) under Cd stress suggests that archaea, rather than bacteria, dominate nitrification in contaminated soils. A shift in gene abundances in NO2- reduction (nirK vs. nirS) was also observed, suggesting a selective advantage for nirK-carrying microorganisms under metal stress. Redundancy analysis revealed that the abundances of N-cycling functional genes were primarily driven by leucine aminopeptidase activity, microbial biomass N, and dissolved organic N, emphasizing the role of soil organic matter degradation and N-mineralization in microbial N-cycling. Understanding the complex interactions between plants, microbes, and N-cycling process under metal stress is crucial for optimizing phytoremediation strategies and promoting sustainable soil management.
How to cite: Hamm, J., Muehe, E. M., Kümmel, S., and Vergara Cid, C.: Climate change vs. Cd: Which one has a stronger impact on nitrogen cycling in soils under phytoremediation?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-21381, https://doi.org/10.5194/egusphere-egu25-21381, 2025.
A key property of thiols (R-SH) is their higher affinity for soft metals over less soft metals. They can therefore act as a filter in plants to separate the micronutrient zinc (Zn, less soft metal) from the ubiquitous pollutant cadmium (Cd, soft metal). Thiols are also present in oxic soils where they may play an important role in trace metal speciation. However, the role of thiols in oxic soils on the trace metal phytoavailability remains largely unexplored. We hypothesize that thiols in soils, similar as in plants, could act as filters to separate Zn from Cd.
The main reason for this knowledge gap is the lack of data on the thiol content in soils. This data paucity is caused by the analytical challenges associated with thiol quantification, including: (i) the sensitivity of thiols to oxidation, (ii) the structural heterogeneity of thiol molecules, and (iii) their lack of distinctive spectral characteristics. Thiols have previously been quantified in natural water using a monobromo(trimethylammonio)bimane -labeling protocol (qBBr). This molecule can bind thiols with high affinity and selectivity for them. The quantification of the non-reacted qBBr by combined chromatography-mass spectroscopy (LC-ESI-MS/MS) methods after derivatization time allows to overcome the aforementioned difficulties and to quantify thiol concentration in environmental samples, including soil pore water samples. However, this method, as it has been implemented until now, presents some limitations. Firstly, the qBBr-labeling was performed at near-neutral pH where most of the thiols are protonated, thereby limiting the qBBr-derivation yield. Secondly, the protocol allowed only for quantification of free thiols although a significant fraction of thiols may be complexed with metals in soils. These limitations likely resulted in an underestimation of thiols. Finally, the matrix of the natural samples may interfere with the quantification procedure (i.e. the binding of qBBr to thiols), a concern that is particularly relevant in soil samples due to the complex matrix.
In this study, we seek to refine the qBBr-labeling protocol to quantify for the first time free and complexed thiols in soil water extracts. We will test the effects of pH on the capacity of qBBr to bind thiols in order to maximize the derivation yield. Additionally, we will use the synthetic chelator EDTA to decomplex metals that are bound to thiols for the quantification of thiols that are complexed with metals. Finally, we will minimize matrix interferences using a control sample with the same matrix and cadmium-saturated thiol binding sites. Developing a thiol quantification method for soils is essential to improve our understanding of the role of thiols on the phytoavailability of essential and non-essential trace metals.
How to cite: Pellegri, G., Wiggenhauser, M., Winkel, L., Björn, E., and Bakour, I.: Quantification of thiols free and complexed with trace metals in oxic soils: a modified qBBr-labeling method, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10804, https://doi.org/10.5194/egusphere-egu25-10804, 2025.
Strontium has been considered an excellent proxy for some important geological processes and it is considered a key marker to understand the provenance, mobility and diet habits in disciplines such as archaeology, paleoecology, and environmental sciences or forensics among others. Besides, whereas Sr is not considered as an essential micronutrient, it shares similar mobility than other cations like radium, barium or calcium and thus could be used as biotracer.
Combining isotopic ratios with trace element analysis offers significant advantages due to its simplicity and precision. Recent studies have highlighted the utility of bees as biosamplers of local geochemical signatures, with honey emerging as a promising biomonitor for trace elements and isotopic geochemistry.
In this work, a green analytical chemistry methodology has been applied to prepare the honeybee samples to be measured by ICP-MS: for major and trace element composition, 1 gram of honey only was mixed with 0.5 M HNO3, and warmed-up to 50oC during 10 min to facilitate homogenization. Previously, 100 µL of bismuth as internal standard was included in the mixture. Finally, an aliquot was diluted in 0.5M HNO3 in order to obtain around 1 mg.L-1 of potassium. The instrumental analysis comprised i) ICP-OES quantification of the main elements, ii) HR-ICP-MS quantification of the trace elements, including the strontium. To explore the strontium isotope ratios an additional aliquot was processed by the common strontium crown-ether separation and purification. In this stage, the HR-ICP-MS was used to measure the isotopic variations in order to test the sample processing performance. For this purpose, a sample of honeybee was isotopically strengthened with a certain amount of NIST-SRM strontium carbonate isotopic standard.
The method was applied to some organic and completely characterized honeybee from four different locations in north Spain, sampled during the same season. Initial results reveal (a) no significant differences between the standard acid digestion methods and the simple dilution approach; (b) results obtained confirm the biogeochemical behavior found when the physical-chemical properties of the honey were considered; and (c) whereas the results are promising still some methodological improvements have to been applied in order to obtain highly precise isotope ratio values by HR-ICP-MS.
Further research will include crosschecking the isotope honeybee signature with the bioavailable strontium in the corresponding soil.
How to cite: Jimenez - Barredo, F., Madrid-Salinas, E., Domínguez-Renedo, O., Alonso-Olmillo, M. A., and Hasozbek, A.: Green Analytical Techniques for Strontium Elemental & Isotope Analysis in Honey: Advancing Sustainable Sample Preparation with HR-ICP-MS, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6570, https://doi.org/10.5194/egusphere-egu25-6570, 2025.
Magnesium (Mg) is an essential nutrient for plant growth, particularly because of its important role in photosynthesis. Thus, Mg availability plays a crucial role in ecosystem development on freshly deposited material such as glacial debris. Gaining insight into the processes that drive vegetation succession is essential for addressing the challenges posed by the rapidly expanding glacier retreat areas worldwide. The subtropical Hailuogou glacial retreat area (approximately 3000 m a.s.l., 1950 mm precipitation, mean annual temperature 4.2 °C), southwest China, with its rapid development from bare soil to a full conifer-dominated mixed forest in <80 years, provides an ideal environment to study the biogeochemical cycling of Mg in the early stage of soil and vegetation development. The quantification of Mg fluxes together with the interpretation of changing Mg isotope ratios (δ26Mg values) in soil and plants provide a promising approach to investigate the development of the Mg cycle during vegetation succession.
Along the Hailuogou chronosequence, 33% of the initial Mg stock in the uppermost 10 cm of the debris was lost within 37 years of soil development, which was attributable to leaching of exchangeable Mg and dissolution of chlorite. In spite of this loss, the δ26Mg values of the organic layer, which developed simultaneously with the vegetation succession, were not correlated with site age and remained mostly unchanged at an average of -0.34±0.10 ‰ (SD, n=15). The δ26Mg values in the organic layer resembled those of the tree leaves (-0.33±0.20 ‰, n=9) and were higher than those in 3 yr-old (-1.16±0.26 ‰, n=15) and 1 yr-old (-0.57±0.21, n=15) needles. The fact that the needles were isotopically lighter than the soil organic layer suggests that there is a Mg-isotopically heavy component in the litter of the conifer-dominated forest, such as woody components and/or seeds and fruits. Mg remobilization from older to younger plant compartments primarily occurs as organo-complexes, where Mg2+ forms strong covalent bonds. At chemical equilibrium, organo-Mg complexes tend to favor the heavy 26Mg over 24Mg, which accumulates in the free cytosolic Mg2+. The higher δ26Mg value of leaves than of the 1 yr-old needles might indicate that most of the comparatively high Mg demand of the leaves of deciduous trees is covered by Mg that was re-translocated prior to leaf abscission and reused by the following generation of leaves, while less Mg was taken up from the exchangeable soil pool (−0.86 ± 0.13 ‰, n = 5). Tree roots were Mg-isotopically heavier than the exchangeable Mg pool, supporting previous findings that plants prefer to incorporate 26Mg relative to 24Mg, mainly because of the equilibrium fractionation by Mg binding to the root surfaces. With increasing ecosystem age, the roots increasingly accumulated isotopically heavy Mg.
Our results reveal that Mg is quickly incorporated into biotic cycles as vegetation succession progresses at the scale of years to decades resulting in a decoupling from soil processes such as weathering and leaching. As a consequence, the Mg isotope ratios in plant compartments are more dominated by plant-internal processes than by soil-plant transfer.
How to cite: Basdedios, N., Wu, Y., and Wilcke, W.: Do stable Mg isotope ratios in ecosystem compartments reflect the increasing incorporation of Mg into biotic cycles as vegetation succession advances?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1008, https://doi.org/10.5194/egusphere-egu25-1008, 2025.
