Limit Of Contamination Research Articles

Chromium removal via coprecipitation with carbonates and iron oxyhydroxides minerals: The effect of organic complexing agents.

With the recent review of the European Environmental Regulations for Water Quality, which plan to reduce contaminant concentration limits in drinking and surface waters by 2036, an increasing demand for wastewater depollution arises. Metastable amorphous nanoprecursors of iron oxyhydroxides (IOH) and calcium carbonates (CC) interact with various pollutants in natural systems via processes such as coprecipitation and adsorption. In this research, ferrihydrite (FHY) and calcium carbonates were testes for Cr (VI) retention to cover acidic to neutral environments and neutral to basic media, respectively. An original and novel approach is proposed for investigating Cr uptake capacity and mechanisms as well as minerals transformation in the presence of Cr (VI) and two biodegradable organic compounds (EDTA - ethylenediaminotetraacetic acid and EDDS - ethylenediamine-N,N'-disuccinic acid). Geochemical modelling of Cr coprecipitated species was also considered. TCLP (toxicity characteristic leaching procedure) experiments revealed that Cr remains fixed in FHY structure under near neutral conditions. One year old ferrite's stability in the presence of Cr and organic compounds was examined and showed that the addition of organics and Cr slowed FHY transformation into crystalline polymorphs. Cr (VI) sequestration by ferrites also occurred as reduced Cr (III) - its less toxic specie. Quantitatively, higher amount of Cr (VI) was removed by coprecipitation (up to 97.65mg/g) then adsorption (ca. 33.76mg/g). These findings provide insight into the uptake processes that influence Cr (bio)availability and mobility, that affect the elemental cycle, including transition across the trophic chain as well as at contaminated environments (i.e., mining sites and acid mine drainage) were ferrihydrite form naturally.

Assessment of environmental impacts of heavy metal pollution in rice in Nanning, China

Nowadays rice has become one of the world’s staple foods. Rice in southern China is also a staple food for everyone, however, with the development of China’s industrialization model, many industrial areas may be contaminated by heavy metals, leading to contamination of the agricultural areas. With the development of recent years, Nanning has become a heavily industrial development area, and rice is also a favourite staple food. Therefore, it is a matter of concern to detect whether heavy metals contaminate rice in Nanning due to environmental factors. Five administrative villages were selected from 12 districts, and 20% of the natural villages were randomly selected for soil and water sample taking using probability distribution points and making the number of samples in each village evenly distributed. The single gene index pollution method and Nemerow composite pollution index method was used to evaluate whether heavy metals polluted the crops. Rice was evaluated through the national standard of Food Safety and Food Contaminant Limits. The survey shows that the heavy metal pollution of rice is moderate, especially cadmium pollution is more serious, but the risk of environmental factors in the Nanning area has a small impact on the overall safety and quality of rice, which is still within the controllable range. The total exceedance rate of heavy metals in the surveyed local rice was 20.95%, and the exceedance rate of paddy rice was 33.33%. The exceedance rates of lead, cadmium, inorganic arsenic, and total mercury in rice were 2.23%, 17.88%, 0.56%, and 0.84% respectively. Cadmium was identified as the primary heavy metal contaminant in local rice, with the highest detected concentration reaching 1.23 mg/kg, which is 6.15 times above the limit set by national health standards. This study shows that the concentration of heavy metals in the environment of Nanning Province is low, and the risk caused by environmental factors has relatively little impact on the safety and quality of rice. However, since the pollution of heavy metals will continue to enrich the food chain with time, long-term use will also cause harm to the human body. Therefore, it is necessary to raise the attention of local governments in rice-producing areas to food safety, and then take effective measures to improve local heavy metal detection technology, improve crop quality, and protect people’s food safety.

Promise and Peril: Stellar Contamination and Strict Limits on the Atmosphere Composition of TRAPPIST-1 c from JWST NIRISS Transmission Spectra

Abstract Attempts to probe the atmospheres of rocky planets around M dwarfs present both promise and peril. While their favorable planet-to-star radius ratios enable searches for even thin secondary atmospheres, their high activity levels and high-energy outputs threaten atmosphere survival. Here we present the 0.6–2.85 μm transmission spectrum of the 1.1 R ⊕, ∼ 340 K rocky planet TRAPPIST-1 c obtained over two JWST NIRISS/SOSS transit observations. Each of the two spectra displays 100–500 ppm signatures of stellar contamination. Despite being separated by 367 days, the retrieved spot and facula properties are consistent between the two visits, resulting in nearly identical transmission spectra. Jointly retrieving for stellar contamination and a planetary atmosphere reveals that our spectrum can rule out hydrogen-dominated, ≲300× solar metallicity atmospheres with effective surface pressures down to 10 mbar at the 3σ level. For high mean molecular weight atmospheres, where O2 or N2 is the background gas, our spectrum disfavors partial pressures of more than ∼10 mbar for H2O, CO, NH3, and CH4 at the 2σ level. Similarly, under the assumption of a 100% H2O, NH3, CO, or CH4 atmosphere, our spectrum disfavors thick, >1-bar atmospheres at the 2σ level. These nondetections of spectral features are in line with predictions that even heavier, CO2-rich atmospheres would be efficiently lost on TRAPPIST-1 c given the cumulative high-energy irradiation experienced by the planet. Our results further stress the importance of robustly accounting for stellar contamination when analyzing JWST observations of exo-Earths around M dwarfs, as well as the need for high-fidelity stellar models to search for the potential signals of thin secondary atmospheres.

Study on Factors Influencing the Migration of Heavy Metals from Soil to Vegetables in a Heavy Industry City

A comprehensive investigation into sustainable agriculture and environmental health was conducted in the Baotou region, encompassing analyses of 90 vegetable samples across 12 varieties and their corresponding rhizosphere soil samples. The physical and chemical properties of the soil, along with the content and chemical speciations of heavy metals, were studied. Results indicated that the study area soil is alkaline to strongly alkaline, with significant heterogeneity in the organic carbon and phosphorus contents, affecting the uptake of heavy metals by these vegetables. The balance of Ca, K, Mg, and P is crucial for soil nutrient equilibrium and reducing heavy metal uptake. The heavy metal contents in the twelve vegetables were below the national food contaminant limit values, with notable accumulations of Cd, Zn, Cu, and Hg. There was a curvilinear correlation between the rhizosphere soil and vegetable contents of Cd and Hg, but differences in uptake were observed. Cd, Zn, Cu, and Hg contents in vegetables were significant, correlating curvilinearly with soil heavy metal content. Soil chemical forms influenced bioavailability, with Cd exhibiting the highest bioactivity. Thus, element migration variations in vegetables reflect the combined influence of the soil’s physical and chemical properties, heavy metal content, and chemical forms. This study validates food safety protocols and soil management practices. Results demonstrate key relationships between soil properties, metal behavior, and plant uptake, enabling targeted solutions for heavy metal contamination and soil remediation. Findings advance sustainable agriculture while protecting ecosystems and food security.

Assessing mold growth severity on various textiles: comparative analysis of inoculum densities and fungal strains

Abstract Mold growth on textiles during overseas shipping poses significant economic and health risks, necessitating a comprehensive understanding of fungal contamination dynamics. This study evaluated textile susceptibility to fungal contamination during transit by examining growth patterns, onset times, and determining minimum fungal densities for visible mold growth. Inoculations of six fungal strains (individual and pooled) were conducted at inoculum densities ranging from 102 to 106 spores/ml on various textile materials. The study comprised two phases: pilot growth (PG, with glucose) and Simulated Shipping Conditions (SSC, without glucose). PG yielded mycelial mats on textiles for all fungal strains except Penicillium citrinum and Stachybotrys chartarum. SSC exhibited variable susceptibilities, with cotton and suede highly susceptible and polyester, imitation suede, and polyurethane notably resistant to mycelial growth. Minimum fungal densities for visible mold growth were established for each textile based on SSC. The findings reveal distinct fungal susceptibilities among textiles, influenced by material composition and structure. Consistent growth on certain textiles at lower fungal densities highlights the need for targeted preventive measures. This research provides crucial insights for the manufacturing and shipping industries, guiding the development of effective mold prevention strategies and establishment of contamination limits during overseas transport.

The Effect of Recycled Geogrid Fibres on Asphalt Concrete Performance: A Case Study from Poland.

This study articulates findings from research pertaining to the utilisation of recycled geogrid in asphalt concrete. The issue of contamination of reclaimed waste with geosynthetic materials persists as a significant concern that warrants attention. In Poland, the allowable quantity of geogrid contaminants within the mineral-asphalt composition is 0.1% w/w. The preliminary evaluation of the validity of the research topic was conducted based on an analysis of correspondence and survey outcomes. The fundamental material research was executed employing elements of experimental design theory. The experimental domain considered two qualitative factors: the type of bituminous mixture for the binding layer (AC16W and AC22W) and the type of geogrid material (glass, carbon), in addition to two quantitative factors: the length of the recycled geogrid fibres ranging from 1 cm to 5 cm, and the quantity of recycled geogrid fibres varying from 0.2% to 1%. A generalised linear model was employed for the analysis, enabling the consideration of dependent qualitative factors in forecasting characteristics. The qualitative evaluation of the resultant solution was conducted using multi-criteria optimisation via the Harrington function. Consequently, recycled carbon mesh fibres demonstrated a notably positive impact, enhancing the material's quality by 22%. Regarding glass mesh, the fibre content should not exceed 0.2% in the AC22W mixture, whereas it can be increased to 1% in the AC16W mixture. Comparing all evaluated mixtures, it was ascertained that surpassing the allowable contamination limit of 0.1% in geogrid form does not result in a significant reduction in the quality of asphalt concrete compared to the reference mix.

Multivariate analysis of organic contaminants in groundwater of an endorheic basin draining to a salt lagoon – Fuente de Piedra (Southern Spain)

Forthcoming EU environmental requirements on water resources quality are likely to include concentration limits of certain contaminants of emerging concern, such as pharmaceuticals and personal care products. However, understanding the occurrence of organic contaminants, including contaminants of emerging concern, in hydro(geo)logical media remains challenging. This study is based on a comprehensive screening of OCs in groundwater of the unique and complex Fuente de Piedra Lagoon endorheic basin system using hydrochemistry and isotopic tools. The basin includes interconnected aquifers of various types (detrital, carbonate and evaporitic). Groundwater recharges the hypersaline lagoon, which holds significant ecological value, but is heavily impacted by anthropogenic activities such as water exploitation for urban supply and irrigation, soil fertilization for agricultural activities and urban wastewater discharges. Out of 185 analyzed compounds, 32 were detected, including 6 personal care products, 10 antibiotics and 11 pharmaceuticals. Concentrations ranged from 0.1 ng/L to 974 ng/L. Notably, the pesticide aldrin was detected with a maximum concentration of 668 ng/L. Two main processes are suggested as potentially affecting the occurrence of different groups of organic contaminants: (i) re-concentration of the more mobile compounds due to irrigation return flows in the unconfined detrital aquifer and (ii) accumulation of certain contaminants in the deep, saline underground media within the evaporitic aquifer, which forms the geologic basement of the detrital and carbonate aquifers of the basin. This study highlights the difficulty in understanding the occurrence of organic contaminants in complex systems and underscores the challenge of meeting the forthcoming environmental requirements.

Perhitungan Angka Lempeng Total Bakteri Jamu Kunyit Asam di Kayuringin Jaya Kota Bekasi

Jamu gendong is not only popular on the island of Java but can also be found on various other islands in Indonesia. Jamu gendong is a trditional medicine favored by the community. Although jamu gendong is not required to have distribution permit, the hygiene of its production process needs to be considered to ensure it is safe for consumption. Kunyit Asam is one of the most popular types among residents. The aim of this study is to determine the Total Plate Count (TPC) of bacteria in kunyit asam in RT 004 RW 012 Kayuringin Jaya, Bekasi City. Samples were taken from three sellers: seller 1, seller 2, and seller 3. The research stages included sample collection, sample preparation, and the total plate count bacterial test. The results of this study showed that for sample 1 and 2, the bacterial count was no more than 105 CFU/ml, while sample 3 had 2x105 CFU/ml. Based on these results, all three of jamu gendong samples meet the quality standards as per the Indonesian Food and Drug Authorithy Regulation Number 12 of 2014 for brewed herbs, with microbial contamination limits (TPC) ≤ 106 colonies/g.

Bioactivity-maximized herbal tea formulation from banana leaf and other Musa acuminata AAA by-products using D-optimal mixture design

Banana leaf, being non-toxic, is often used in traditional cooking and medicine. However, its full potential is still largely unexplored. The current work aimed to screen for biological active compounds in banana leaf, and to establish an optimal formulation of tea using banana leaf and other banana by-products via a mixture design methodology. Obtained results show that banana leaf contains bioactive compounds (polyphenols, flavonoids, tannins, terpenoids), suitable for tea production. Using d-optimal-mixture-design, the optimal formulation (53% banana leaf, 30% peel, 16% corm, 1% sweet grass) was chosen for maximizing achieved total phenolic content, DPPH-inhibition and customers’ acceptance. Predicted and observed values were found to be in good agreement, pointing to the good-quality of the model. Additionally, the product met WHO-recommended limits for heavy metals and microbial contamination, assuring product safety. These findings indicate that Musa acuminata AAA by-products possess great potential as alternative sources of antioxidants for tea production.

Extremely high levels of PBDEs in children’s toys from European markets: causes and implications for the circular economy

BackgroundWith the high influx of low-cost plastic toys on the market, there is growing concern about the safety of such toys. Some of these plastic toys contains hazardous chemicals like polybrominated diphenyl ethers (PBDEs) due to the use of recycled plastics in new toy manufacturing. Here, we investigated if toys marketed in Europe are compliant with EU directives to assess the safety of currently used children's toys and identify implications of PBDE content in toys.ResultsEighty-four toys purchased from international toy retailers were screened for bromine using X-ray fluorescence (XRF), and 11 of those with bromine content higher than 500 µg/g were analyzed for ten PBDEs using GC–HRMS. PBDEs were detected in all 11 toys. Ʃ10PBDE concentrations ranged up to 23.5 mg/g (with a median concentration of 8.61 mg/g), with BDE-209 being the most abundant compound (4.40 mg/g). Eight samples exceeded the EU’s Low POP Content Limit (LPCL) of 500 µg/g for the Ʃ10PBDEs by 6–47 times and the Unintentional Trace Contaminant (UTC) limits of 10 µg/g for Deca-BDE by 12–800 times.ConclusionsPBDEs were up to percent levels, suggesting direct recycling of flame retarded plastic, e.g., e-waste plastics, into toy components. This is a call for concern and requires intervention from all stakeholders involved in the toy market. Overall, the occurrence of non-compliant toys in the EU market, as indicated in this study is primarily attributed to gaps in regulations, inadequate legislation for recycled plastics, the rise of online sales, complexities in global and national supply chains, and economic challenges. Failure to address these issues will hinder the efforts of the plastics industry to transition into a circular economy. This suggests that more actions are needed to address gaps in cross-border enforcement, and stricter sanctions are required for toy manufacturers who fail to adhere to regulations and safety standards.

Invited Perspective: Is It Time to Revisit the Allowable Maximum Contaminant Limit for Arsenic in Public Drinking Water?

Invited Perspective: Is It Time to Revisit the Allowable Maximum Contaminant Limit for Arsenic in Public Drinking Water?

Status of microbial contamination in edible ice in Dak Lak province in 2022-2023

A study conducted in 2022 and 2023 assessed the microbial contamination levels in edible ice. The findings indicated that 67.6% of samples exceeded permissible contamination limits, with 63.0% of samples contaminated in 2022 and 70.7% in 2023. The prevalent microbial indicators detected included total coliforms (55.9%), Pseudomonas aeruginosa (10.3%), Escherichia coli (19.1%), Streptococci feacal (intestinal enterococci) (33.8%), and sulfite-reducing anaerobic bacterial spores (30.9%). Notably, 14.7% of samples showed contamination with two microbial indicators, 17.6% with three indicators, and 10.3% with four indicators, emphasizing the need for enhanced food safety and quality control measures. Additionally, the study revealed seasonal variations in microbial contamination rates, with higher rates observed during the dry season (72.7%) compared to the rainy season (62.9%). These findings suggest that more stringent control measures are necessary, particularly during the dry season, to mitigate the risk of microbial contamination.

Dual synergistic function of pyrite modified biochar synthesized with chelating agent for mediating arsenic removal process: Reactive site identification and pathway mechanism exploration

Arsenic (As) contamination is widespread around the world, particularly the As(III) with highly toxic and carcinogenic posing huge threats to the biosphere. The secondary pollution and high energy consumption caused by the current method prompt the need for economically feasible and sustainable scheme to achieve As removal. In this study, the pyrite (FeS2) modified biochar (IP-BC) was synthesized with assistance of N-(1,2-dicarboxyethyl)-D, L-aspartic acid (IDHA) achieving uniform distribution of Fe components and S configuration on biochar surface. These improved characteristics enable IP-BC to have excellent catalytic and adsorption capacity in coupled peroxydisulfate (PDS) system with 11.3- and 11.8- times higher removal efficiency of total As than pristine biochar and FeS2, respectively. The reactive oxidizing substances dominated by •OH are responsible for As(III) oxidation, which could be produced by IP-BC regarding the structural Fe(II), phenolic hydroxyl and carboxyl group as possible reactive sites. S22−, Sn2− and hydroxyl of IP-BC could act as electron donors involving in Fe(II)/Fe(III) cycle, promoting the oxidation of As(III) to As(V). The final immobilization mechanism of arsenic by IP-BC was dominated by hydrogen bonding in individual system, while it transformed into the complexation and co-precipitation related with structural Fe of IP-BC in PDS coupled system. Results confirmed the prominent performance of IP-BC/PDS system that total As concentration decreased to < 10 µg/L (maximum contaminant limit) within 60 min in different water matrix. Therefore, this work provides potential insights to guide the synthesis of functional and green biochar converting from solid wastes of mining and forestry to reach the goal of efficient arsenic removal.

Solar-Driven Evaporator With "Starburst Turbine" Design Featuring Directional Salt Crystallization, Antibacterial, and Catalytic Multifunctionality for Efficient Water Purification.

Facing the global challenge of water scarcity, solar-driven desalination is considered a sustainable technology for obtaining freshwater from seawater. However, issues such as uncontrolled salt crystallization and bacterial contamination limit its efficiency and practicality. This study proposes an innovative solar-driven evaporator designed to address these challenges using optimized shape design and advanced photothermal materials. Based on finite element analyses, cylindrical evaporators with a "Starburst Turbine" shape are designed and fabricated, achieving directional salt crystallization and a record-breaking water collection rate of 3.56kg m-2 h-1 and an evaporation rate of 4.57kg m-2 h-1 under one sun illumination. During continuous 60-h illumination tests, the evaporator maintained a stable evaporation rate, attributed to its excellent directional salt crystallization capability. Additionally, the evaporator demonstrates superior photodynamic antibacterial performance and photocatalytic degradation of organic pollutants. Under one sun illumination for 1 h, it achieves 100% sterilization of S. aureus and E. coli, and a 95.4% degradation of methylene blue (MB), demonstrating its potential to purify various wastewater types. These findings underscore the significant scientific and practical value of integrating antibacterial and photocatalytic functions into solar water purification materials, providing a sustainable solution to global water scarcity challenges and environmental protection.

High Performance and Selective Sequestration of Cd(II) from Water by Layered Thiophosphate.

The extensive use of toxic cadmium (Cd) in energy conversion and industrial applications ranging from solar cells and battery appliances to paints and pigments contaminates water bodies. However, the upper limit of Cd contamination in drinking water is to be only 3 ppb by the WHO and 5 ppb by the USA-EPA, which underscores the need for cost-effective, efficient, and ppb level capture of Cd from contaminated water. Leveraging the selectivity due to Lewis's hard-soft acid-base (HSAB) theory, we have achieved swift and highly selective capture of Cd(II) ions from aqueous mediums using layered potassium manganese thiophosphate (K-MnPS3). K-MnPS3 effectively removes Cd(II) ions from extremely dilute aqueous solutions (ppb levels), achieving a maximum sorption capacity of 405.43 mg/g and a removal rate exceeding 97% within 20 min. Even in the presence of competing ions such as Na+, Mg2+, Ca2+, and Pb2+, K-MnPS3 remains selective. Additionally, it operates efficiently across a wide pH range (1.78-11.19) with a high distribution coefficient (∼104 mL/g). Breakthrough experiments using a 1 wt % K-MnPS3 and 99 wt % sand column showed complete breakthrough of Cd(II) after 62 h, leading K-MnPS3 as a promising candidate for Cd(II) removal from industrial effluents.

Improvement of the Chemical Quality of Cachaça

The objective of this study was to determine the chemical composition of sugarcane spirits and commercial Cachaças, comparing them with the limits established by national legislation and with studies conducted in previous periods. Previous studies have shown that 50% of the samples of this distillate were above the contaminant limits allowed by national legislation, constituting one of the main factors responsible for the low volume of exports. In this research, 531 Cachaça samples were analyzed in order to verify whether they complied with the limits of contaminants and volatile compounds required by Brazilian legislation. The results obtained indicate that Brazilian producers have adapted to the use of good manufacturing practices during the production process, ensuring the standardization of this distilled beverage and consequent compliance with legislation.

Influence of Sodium Chloride and Potassium Fluoride on Electrochemical Properties of Aluminum Copper Interdigital Structures

This paper evaluates the electrochemical properties of aluminum (0.5 w%) copper alloy metallized test chip surfaces with interdigital structures and distances between 3 and 20 μm, regarding sodium chloride and potassium fluoride contamination in the range of 1011–1016 ions per cm2 at high humidity (85%) and high temperature (85 °C). These accelerated tests result in leakage currents and impedance values which show a significant change above a contamination limit value of 1014 ions per cm2 for both salts i.e., the leakage current starts to increase well above a few pico amperes, and the impedance decreases significantly. This contamination level can be seen as a turning point, after which devices can undergo for example signal shifts or corroded metal tracks over lifetime. But not only the start point of an increase in leakage current decides about the harmfulness of the contamination, other important influences are deliquescence and how high the leakage current gets at its maximum. Therefore, even with the same starting point, the risk evaluation is not the same for sodium chloride and potassium fluoride.

Development of cost-effective inorganic arsenic extraction method for resource-limited regions: Analysis of efficiency and regulatory implications

This study evaluated the effectiveness of coke and lemonade extraction methods compared to the standard 1 % v/v HNO3 method for determining inorganic arsenic (iAs) concentrations in rice bran samples using a field-deployable method (Arsenator field kit). The limit of detection (LOD) for the methods was 45 μg kg−1, comparable to existing literature. The extraction efficiencies were assessed by comparing iAs recovery rates, with coke extraction yielding the highest recovery of 127.4 %, followed by lemonade at 116.2 %, and HNO3 at 100 %. Statistical analysis indicated strong correlations between the extraction methods, particularly between HNO3 and coke (Pearson correlation coefficient, 0.990), suggesting that coke extraction is a reliable alternative to the traditional HNO3 method. However, lemonade extraction showed a lower correlation (0.940) and higher false negative rates, indicating potential limitations for regulatory compliance. Notably, at the maximum contaminant limit (MCL) of 0.100 mg kg−1, coke extraction produced an 8 % false positive rate with no false negatives, while lemonade extraction had an 8 % false positive rate and a 17 % false negative rate. This study underscores the potential of coke extraction as a cost-effective and efficient alternative for assessing iAs levels in rice products, especially in resource-limited settings. Recommendations include the standardization of coke extraction protocols and the development of robust monitoring programs to ensure food safety and public health protection against arsenic contamination. Overall, the findings contribute valuable insights for improving arsenic detection methods and regulatory compliance in food safety practices.

Removal of heavy metals from mine water using a hybrid electrocoagulation-ceramic membrane filtration process

Mining operations must account for increasingly stringent wastewater discharge limits for various contaminants, such as heavy metals and suspended solids. In the treatment of metal-bearing wastes, electrochemical processes, including electrocoagulation (EC), are gaining popularity. At large scales, EC processes can be hindered by considerable amounts of flocculants and by sedimentation tank sizes required to properly operate. This work sought to address these concerns by evaluating EC in mine water treatment using a pilot system coupled with ceramic membrane microfiltration (MF) and ultrafiltration (UF). The use of MF and UF after EC allows for the removal of suspended solids without needing a flocculation-sedimentation process. EC evaluation was performed using field samples of mine water from a North American concentrator. Under optimal conditions, EC removed over 95 % of Cr, Co, Cu, Fe, Mn, Ni, Pb, Ti and Zn from the mine water. Effluent from EC was used as feed in MF and UF processes with ceramic membranes. The tested membranes rejected 100 % of suspended solids from the EC effluent. Permeate from the membranes was free of solids and possessed turbidities of 0.05–0.15 NTU. Filtrate from the hybrid process satisfied environmental regulations for heavy metal concentrations, offering new opportunities for reuse or discharge. The hybrid process applied in this work can thus be used in mining operations to safely discharge their water, and/or to increase their water recirculation due to environmental concerns and water shortage.

Metal(loid) uptake and physiological response of Coix lacryma-jobi L. to soil potentially toxic elements in a polluted metal-mining area

Coix lacryma-jobi L. is a traditional medicinal plant in east Asia and is an important crop in Guizhou province, southwest China, where there are elevated levels of soil mercury and arsenic (As). Exposure to multiple potentially toxic elements (PTEs) may affect plant accumulation of metal(loid)s and food safety in regions with high geological metal concentrations. Field experiments were conducted to study the effects of PTEs on metal(loid) accumulation and physiological response of C. lacryma in different plant parts at three pollution levels. Total root length, number of root tips, number of branches, and number of root crosses increased with increasing pollution level, with increases in highly polluted areas of 44.2, 57.0, 79.6, and 97.2%, respectively, compared to lightly polluted areas. Under multi-element stress the activity of C. lacryma antioxidant oxidase showed an increase at low and medium PTE concentrations and inhibition at high concentrations. The As contents were all below the maximum limit of cereal food contaminants in China (GB 2762-2022, As < 0.5 mg kg−1). The stems had high Tl bioconcentration factors but the translocation factors from stem to grain were very low, indicating that the stems may be a key plant part restricting Tl transport to the grains. C. lacryma increased root retention and reduced the transport effect, thus reducing metal accumulation in the grains. C. lacryma adapted to PTE stress through root remodeling and enhanced antioxidant enzyme activities.