Our study found that sediment heavy metal content is the primary factor influencing heavy metal uptake by emergent macrophyte species. This research aimed to quantify the concentrations of heavy metals and metalloids (As, Cd, Cu, Pb, Si, and Zn) in emergent macrophytes-Lysimachia thyrsiflora, Sagittaria sagittifolia, Phragmites australis, Glyceria fluitans, Carex nigra, Equisetum fluviatile, and Juncus effusus-as well as in the corresponding water and sediment samples from Orrefors, Läen, and Emmaboda, to assess their net accumulation and translocation capacity for application in phytoremediation management. Our results revealed that the sediment As concentration at the Emmaboda site was 23 times higher than the Swedish Environmental Protection Agency (Swe EPA) guideline value. At the Orrefors and Läen sites, the concentrations of heavy metals and the metalloid in water followed the descending order: Zn > Pb > Cu > As > Cd. Among the studied species, L. thyrsiflora was the most abundant across locations and exhibited the highest As accumulation (1,603 mg/kg) in its roots, with minimal translocation to its shoots. Si and Zn showed relatively high translocation to the shoots in most of the surveyed emergent macrophytes, regardless of location. This preliminary study indicates the substantial heavy metal accumulation in L. thyrsiflora and J. effusus. In combination with their limited translocation to the shoots, this underscores their strong potential for phytoremediation-based management of contaminated glasswork sites.

Purpose: The aim of this study was to determine how organic and inorganic fertilisers influence the accumulation of metal contaminants in lettuce grown in mine-affected soils, and to identify the soil properties that govern metal uptake and how fertilisation alters these conditions.

Materials and methods: Lettuce was grown in mine-affected soils treated with NPK or organic fertilisers. Soil and plant samples were analysed for metal concentrations, pH, SOM, CEC and texture, and bioconcentration factors (BCFs) were calculated as indicators of soil-to-crop metal transfer. Linear mixed models were used to assess fertilisation effects on BCF. Soil variables influencing metal uptake identified using a Least Absolute Shrinkage and Selection Operator (LASSO) approach, to enable variable selection within the hierarchical design.

Results and discussion: The overall treatment effects on BCF was significant for Cu, Pb and Zn (p = 0.006, 0.007 and 0.003, respectively), while close to significant for Cd (p = 0.052). Organic fertilisation significantly reduced the soil-to-crop transfer of Cu and Zn, compared to inorganic NPK fertilisation (p = 0.008 and 0.002, respectively). Key predictors of metal uptake included soil concentrations of metals, pH, SOM, K, P, Mg, clay content, and exchangeable Mgt+. Fertilisation significantly affected pH, SOM, K, P, and exchangeable Mg²⁺, which in turn influenced metal phytoavailability. The effect of fertilisation varied by soil type, with site-specific geochemical properties playing a dominant role. When modelling uptake with the LASSO regression approach, Pb was less predictable (R²_adj = 0.42) than Cd, Cu, and Zn (0.79, 0.60 and 0.72, respectively), reflecting its complex behaviour in soil matrices. Overall, fertilisation altered both metal uptake and the geochemical conditions controlling it.

Conclusion: Fertilisation affected both soil-to-crop metal transfer and the controlling soil properties, indicating that organic fertilisers may be more suitable than inorganic fertilisers in contaminated environments, where tailored fertilisation is essential because it can either increase or reduce metal transfer to crops. The findings supports safer cultivation practices in areas with legacy pollution.

The increasing use of Technology-critical elements (TCEs) in modern technologies is expected to raise their concentrations in soils of many areas, prompting concerns about their mobility and entry into the food chain. This study examines pore water availability and plant uptake of gallium (Ga), thallium (Tl), and the rare earth elements gadolinium (Gd), neodymium (Nd), and ytterbium (Yb). Lettuce (Lactuca sativa) was grown under controlled greenhouse conditions in a native agricultural soil from Sweden, both at the baseline concentrations of the elements and after spiking in a concentration series in which the highest level corresponded to a 40-fold enrichment of the original concentrations. Our findings indicate that Tl poses the greatest risk among the investigated TCEs, as it was readily taken up by lettuce even at moderate concentrations in the soil, with a clear dose-dependent increase in accumulation (Bioconcentration factor, BCF = 0.084-1.5). Gallium demonstrated a low concentration in pore water and limited accumulation in lettuce (BCF = 0.00010-0.00066), suggesting a low immediate concern. However, the Ga uptake increased substantially at the highest contamination level, indicating a potential risk threshold. Relative to Ga and Tl, the REEs demonstrated intermediate levels of both pore water availability and lettuce uptake, although the uptake increased with rising soil concentrations (BCF = 0.0013-0.0071, 0.0013-0.012, and 0.0011-0.0020, for Gd, Nd, and Yb respectively). Notably, Nd was also found to negatively affect seed germination, suggesting a possible risk to crop productivity. Together, our findings highlight the need for targeted risk assessments of specific TCEs, as these elements may increasingly find their way onto our plates through soil-to-plant transfer under potential future soil contamination.

This study provides a baseline analysis of sediment pollution in Kalmar Guest Harbor, Sweden, focusing on metals and microplastics. The study site, a bustling coastal area, was chosen to investigate the connections between anthropogenic activities, bioturbation, and environmental contaminants. The results revealed that the pollution extends beyond 30 cm of depth below the seafloor, with elevated levels of copper (Cu), tungsten (W), cadmium (Cd), zinc (Zn), lead (Pb), and microplastics. Significantly, there is no previous publication alarming the W contamination in the Baltic Sea sediment, and therefore, our findings highlight the need for further investigation into tungsten contamination in the region. Furthermore, we explored the distribution patterns, potential sources and relationships of different contaminants. The K-means cluster analysis revealed that bioturbation is speculated to influences the depth concentration of pollutants, particularly at shallow depths (0‬–18 cm). Metal contaminants do not appear to be predominantly bound to MP particles. 

Microplastics (MPs) are a significant environmental concern due to their abundance, widespread occurrence, slow degradation rate, and toxicity. Although MPs have been found in various environments and organisms (including humans), few studies have investigated their historical accumulation in marine settings. Here we present the first chronological accumulation of MPs in Baltic Sea sediments over time. The high sediment accumulation rates (ca. 1 cm yr^-1) and anoxic bottom conditions in the study area allowed for an exceptionally well-preserved record of MPs in sediment over the last 50 years. Despite potential biases and limitations associated with the methodologies (e.g., visual identification), our results suggest that MP accumulation began in the 1970s-1980s and has continued to increase until present-day, with up to 4450 particles per kg of dry sediment. The temporal distribution of MPs in sediment is consistent with local population growth in catchment areas and global plastic production rates, highlighting the impact of human activities on MP pollution in the region.

Technology-critical elements (TCEs), essential in emerging technologies, are increasingly finding their way into our environment, raising concerns about their sparsely studied behavior and toxicity. To contribute insights into the toxicological aspects, we employed in vitro bioassays to investigate the possible cytotoxic effects in four representative cell lines (AR-EcoScreen GR-KO-M1, DR-EcoScreen, MCF7AREc32, VM7Luc4E2) and the potential to induce oxidative stress via the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway for a number of these elements. Nine TCEs, three rare-earth elements (REEs: Gd, Nd, Yb) and six less-studied TCEs (LSTCEs: Ga, Ge, In, Ta, Te, Tl), were selected for this study, along with three well-studied traditional metal contaminants (TMCs: As, Cd, Pb) for comparison. Among the 12 studied elements, nine showed signs of inducing cytotoxicity: As, Cd, Ga, Nd, and Te in three out of the four studied cell lines and Gd, Ta, Tl, and Yb in one to two cell lines. Tellurium repeatedly exhibited the highest potency. The TCEs Ga and In, similar to As and Cd, also demonstrated the potential to induce oxidative stress. The results of this study suggest that some TCEs may potentially cause adverse health effects similar to As and Cd, thus prompting further investigations.

The legacy of post-industrial contamination often limits the safe use of urban soils for food production without pre-treatment to reduce metal(loid) solubility and uptake in crops. In this study, a seed residue biochar was applied at two doses (1% and 5%) to six circumneutral urban allotment soils from Denmark and the UK, all exhibiting elevated concentrations of As, Cd, Pb and Zn. Soil pore water was sampled to assess metal(loid) solubility and soil:solution partitioning, and lettuce was grown to determine metal(loid) uptake. Biochar application had varying effects on metal(loid) solubility. For As and Pb, solubility generally increased, particularly at the higher dose. For Zn and Cd, solubility tended to decline. Metal(loid) uptake in lettuce also varied, with no consistent change between control and treatments for As and Pb, despite their increased solubility. However, a clear reduction in Zn and Cd uptake was observed, especially at the 5% application rate. For Cd, this resulted in a marked decrease in the proportion of samples exceeding health-based guideline values, indicating a tangible reduction in dietary risk. These findings show that even in circumneutral soils, biochar can significantly influence metal(loid) behaviour, with the greatest benefit observed for reducing Cd accumulation in edible crops. However, the observed increase in As and Pb solubility underscores the importance of considering potential risks associated with leaching and water contamination.

While vegetable uptake of traditional metal contaminants is a well-studied pathway to human exposure and risk, a paucity of information exists on the uptake of emerging metal contaminants. This study evaluated the uptake of the Technology-critical elements (TCEs) gallium (Ga), germanium (Ge), niobium (Nb), tantalum (Ta), thallium (Tl), and rare earth elements (REEs) into lettuce cultivated in 21 European urban soils. For comparison, the uptake of cadmium (Cd) was also analysed. First, the uptake was predicted by multiplying soil concentrations with previously established bioconcentration factors (BCFs). Subsequently, multiple regression models incorporating geochemical variables as predictors were used to determine whether prediction accuracy could be improved. A “3-predictor model” incorporated soil TCE concentration, pH, and organic matter (OM), and a “7-predictor model” added data on clay content and the soil concentrations of Fe, Al, and Mn as well. With the exception of Cd, Ge, and Tl, the BCF approach provided unsatisfactory predictions (R2 < 0.5), while the 7-predictor models yielded the best predictions, even when accounting for the greater number of predictors. While the most important predictors of uptake varied somewhat between the TCEs, the concentrations of TCEs in the soil generally explained the largest proportion of the variation. The least influential predictors in our dataset were [Mnsoil], [Fesoil], and soil OM. Incorporating geochemical data generally improved the predictions of uptake by lettuce, and these findings underscore the need for more detailed characterisations of the uptake potential of TCEs by food plants and subsequent consequences for human health.

Partial Least Squares Regression (PLS-R) was introduced as a method for modeling the uptake of six potentially toxic elements (PTEs)- Ba, Cd, Cu, Ni, Pb, and Zn- by lettuce, chard, and carrot. Data were obtained from a pot experiment where these crops were cultivated in urban soils of various characteristics. The models consider soil concentrations of PTE, Al, Ca, Fe, K, Mg, Mn, Na, P, S and pH, SOM, CEC, and soil texture as predictors. Initially, eighteen metal- and crop-specific models with all predictors were developed, using selectivity ratios (SRi) to identify influential variables for predicting PTE soil-to-crop transfer. Reduced models were then created using only predictors with high SRi. Key variables for predicting PTE soil-to-crop transfer included soil PTE concentration, pH, Fe and Mn soil concentrations, and soil texture. Out of eighteen models, sixteen were suitable for predicting correlations and assessing PTE accumulation in crops, while eight were accurate for quantitative predictions. This study shows that PLS-R is a robust method for modeling soil-to-crop transfer of metal contaminants, even with multicollinear predictors. PLS-R also helps identify key variables, providing insights into the mechanisms of PTE accumulation in crops, which is crucial for effective risk assessments.

Recognising the need for robust models in predicting groundwater contamination risks from metal(loid)s in contaminated topsoil, this study focuses on the geochemical behaviour of As, Cd, Cu, Pb, Sb and Zn in one of Sweden’s most heavily contaminated areas. Samples were collected from the waste zone and underlying subsoil down to 5 meters and batch experiments were carried out to assess pH-dependent solubility. The results indicate that Cd, Cu, Pb and Zn are efficiently immobilized in the waste zone, while As(V) and Sb(V) are more easily leached. With the exception of Pb and Cu at high pH, the mobilized metals appear to be predominantly in a truly dissolved state, as confirmed by ultrafiltration at 10 kDa.

Speciation modelling using Visual MINTEQ did not suggest a significant role of precipitates such as Zn or Pb arsenates and phosphates, although their involvement could not be ruled out. To better understand sorption/desorption patterns, a multi-surface geochemical model was established, drawing on the Stockholm Humic and CD-MUSIC models for organic matter and Fe/Al (hydr)oxide sorption. However, when default parameters were used, the model consistently overestimated the solubility of Cd, Cu, Pb and Zn in both the waste zone and the uncontaminated subsoil. In contrast, As(V) solubility was generally underestimated, also when the reactive surface area of the Fe- and Al (hydr)oxides was decreased in the model. The model's performance was better for Sb(V), though not without imperfections. When the parameters for organic matter were adjusted such that 100% of the solid-phase organic matter was active with respect to ion binding, but only 25% of the dissolved organic matter, the model description improved considerably for Pb and Cu in the upper soil layers. The model revealed distinct differences in the adsorption behaviour of the metal cations, with Pb being sorbed mostly to Fe/Al (hydroxides), whereas a considerable part of Cu was sorbed to organic matter, particularly in the waste zone.

Possibly, the dissolution of easily weatherable metal-containing mineral phases may have contributed to the poor model performance for Cd, Zn and for Cu in the deeper soil layers, although other factors, such as a contribution of hydrous SiO2 or Mn oxides to metal binding, could not be ruled out. Metal sorption to carbonate phases may also have been a contributing factor in the waste zone. Lastly, the reactivity of Fe- and Al (hydr)oxides may have been overestimated by oxalate extraction when default parameters for high-surface-area ferrihydrite were applied. 

These findings provide valuable insights for environmental management and underscore the need for a more detailed characterization of metal(loid) sorption in contaminated soils, as well as the development of improved modelling strategies to enhance solubility predictions.