Research progress on the environmental risk assessment and remediation technologies of heavy metal pollution in agricultural soil.

Controlling heavy metal pollution in agricultural soil has been a significant challenge. These heavy metals seriously threaten the surrounding ecological environment and human health. The effective assessment and remediation of heavy metals in agricultural soils are crucial. These two aspects support each other, forming a close and complete decision-making chain. Therefore, this review systematically summarizes the distribution characteristics of soil heavy metal pollution, the correlation between soil and crop heavy metal contents, the presence pattern and migration and transformation mode of heavy metals in the soil-crop system. The advantages and disadvantages of the risk evaluation tools and models of heavy metal pollution in farmland are further outlined, which provides important guidance for an in-depth understanding of the characteristics of heavy metal pollution in farmland soils and the assessment of the environmental risk. Soil remediation strategies involve multiple physical, chemical, biological and even combined technologies, and this paper compares the potential and effect of the above current remediation technologies in heavy metal polluted farmland soils. Finally, the main problems and possible research directions of future heavy metal risk assessment and remediation technologies in agricultural soils are prospected. This review provides new ideas for effective assessment and selection of remediation technologies based on the characterization of soil heavy metals.

Unveiling heavy metal pollution dynamics in sediments of river Ulhas, Maharashtra, India: a comprehensive analysis of anthropogenic influence, pollution indices, and health risk assessment.

Metals and metalloids tainting sediments is an eminent issue, predominantly in megacities like Mumbai and Navi Mumbai, requiring an exhaustive examination to identify metal levels in river bodies that serve various populations. Thus, utilising pollution indices, multivariate analysis, and health risk assessment studies, we propose a novel investigation to examine the metal content in the Ulhas River sediments, a prominent agricultural and drinking water supply (320 million-litre per day) near Mumbai in Maharashtra, India. The eleven metals and metalloids (As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, and Zn) were examined monthly from 10 stations totaling 120 sediment specimens from October 2022 to September 2023. Investigations revealed that average values of Cr, Cu, Hg, and Ni exceeded Australian and New Zealand Environment and Conservation Council and Agriculture and Resource Management Council values, while all metals exceeded World surface rock average limits except As. Various pollution indices showed that upstream sites had none to low level contamination, whereas downstream locations had moderate to considerable contamination, suggesting anthropogenic influences. Furthermore, multivariate analysis including correlation, cluster, and principal component analysis identified that sediment pollution was mostly caused by anthropogenic activities. Lastly, health risk assessment indicated Fe was non-carcinogenic to children, whereas Cr and Ni were carcinogenic to children and adults, with children being more susceptible. Thus, from the findings of the study it is clear that, despite low to moderate pollution levels, metals may have significant repercussions, thus requiring long-term planning, frequent monitoring, and metal abatement strategies to mitigate river contamination.

BioMOF@PAN Mixed Matrix Membranes as Fast and Efficient Adsorbing Materials for Multiple Heavy Metals' Removal.

Heavy metal ions are a common source of water pollution. In this study, two novel membranes with biobased metal-organic frameworks (BioMOFs) embedded in a polyacrylonitrile matrix with tailored porosity were prepared via nonsolvent induced phase separation methods and designed to efficiently adsorb heavy metal ions from oligomineral water. Under optimized preparation conditions, stable membranes with high MOF loading up to 50 wt % and a cocontinuous sponge-like morphology and a high water permeability of 50-60 L m-2 h-1 bar-1 were obtained. The tortuous flow path in combination with a low water flow rate guarantees maximum contact time between the fluid and the MOFs, and thus a high heavy metal capture efficiency in a single pass. The performances of these BioMOF@PAN membranes were investigated in the dynamic regime for the simultaneous removal of Pb2+, Cd2+, and Hg2+ heavy metals from aqueous environments in the presence of common interfering ions. The new composite adsorbing membranes are capable of reducing the concentration of heavy metal pollutants in a single pass and at much higher efficiency than previously reported membranes. The enhanced performance of the mixed matrix membranes is attributed to the presence of multiple recognition sites which densely decorate the BioMOF channels: (i) the thioether groups, deriving from the S-methyl-l-cysteine and (S)-methionine amino acid residues, able to recognize and capture Pb2+ and Hg2+ ions and (ii) the oxygen atoms of the oxamate moieties, which preferentially interact with Cd2+ ions, as revealed by single crystal X-ray diffraction. The flexibility of the pore environments allows these sites to work synergically for the simultaneous capture of different metal ions. The stability of the membranes for a potential regeneration process, a key-factor for the effective feasibility of the process in real life applications, was also evaluated and confirmed less than 1% capacity loss in each cycle.

Nitric oxide and ascorbic acid confer cadmium (Cd) tolerance by improving plant terpenoid metabolism and epigenetically modifying DNA methylation.

This study investigated the efficacy of incorporating nitric oxide (NO; 10 µM) and ascorbic acid (Asc; 10 µM) into the culture medium to confer cadmium (Cd; 5 µM) tolerance in thyme (Zataria multiflora). The phytotoxicity of Cd resulted in a decrease in shoot biomass, which NO or Asc mitigated. Adding Asc and NO to the culture medium was associated with substantial DNA hypomethylation. The NO + Cd and Asc + Cd treatments were accompanied by an increase in the unmethylation percentages, about 3-fold higher than the control. The hemi-methylation percentages in the Asc-supplemented seedlings also displayed an upward trend. The transcriptional upregulation in the γ-terpinene synthase (TPS) gene resulted from the applied elicitors, especially NO. In response to the NO and Asc treatments, the transcription of two cytochrome P450 monooxygenase genes (CYP71D178 and CYP71D180) went up. Incorporating Asc or NO into the culture medium enhanced the concentrations of proline, carvacrol, and thymol metabolites. Employing NO or Asc mitigated the 43% decrease in protein content due to the Cd cytotoxicity. The NO and Asc applications improved the activity of the phenylalanine ammonia-lyase (PAL) enzyme. NO and Asc utilization increased the accumulation of flavonoids. NO and Asc also up-regulated the activities of two enzymatic antioxidants (catalase and peroxidase). Collectively, this study provided novel insight into how Asc or NO confers Cd tolerance by epigenetically remodeling DNA methylation, transcriptionally up-regulating terpenoid and phenylpropanoid metabolism, increasing proline concentration, and improving antioxidants.

Assessing soil remediation effect of Cr and Pb based on bioavailability using DGT, BCR and standardized determination method.

In the field of soil remediation, the importance of bioavailability of pollutants has not received adequate attention, leading to the excessive application of remediation measures. Therefore, to ensure the safe use of farmland soil, a scientific method is needed to assess labile contaminants and their translocation in plants. To evaluate soil remediation effect based on bioavailability, the concentrations of these heavy metals in soil were analyzed using by the method for total metal content, the Community Bureau of Reference (BCR) extraction, and the diffusive gradients in thin films (DGT) technique. The results reveal that the correlation coefficients between metal concentrations measured by DGT and those accumulated in rice grains are the highest (Cr-R2 = 0.8966, Pb-R2 = 0.9045). However, the capability of method for total metal content to evaluate the remediation effect of heavy metals is very limited. In contrast, although Cr and Pb measured by BCR show a high correlation with HMs in rice plants, the method still falls short in precisely assessing bioavailability. Significantly, DGT proves to be more effective, successfully distinguishing the remediation effects of different treatments. Generally, DGT offers a more accurate and simpler assessment method, underscoring its practical significance for monitoring soil remediation and environmental management.

Development of nanocomposite-selenium filter for water disinfection and bioremediation of wastewater from Hg and AgNPs.

Selenium nanoparticles (SeNPs) are used in several sectors as antitumor, antimicrobial, and environmental adsorbents. Thus, the present research objective was the production of bacterial-SeNPs as an active and environmentally-friendly antibacterial and adsorbent agents and application into novel nanocomposite filter. From a total of 25 samples (soil, wastewater, and water) obtained from different locations in Egypt, 60 selenium-resistant bacterial isolates were obtained (on a mineral salt medium supplemented with selenium ions). After screening (based on the conversion of selenium from ionic form to nanoform), a superior bacterial isolate for SeNPs formation was obtained and molecular identified as Bacillus pumilus isolate OR431753. The high yield of SeNPs was noted after optimization (glucose as carbon source, pH 9 at 30 °C). The produced SeNPs were characterized as approximately 15 nm-diameter spherical nanoparticles, in addition to the presence of organic substances around these particles like polysaccharides and aromatic amines (protein residues). Also, they have antibacterial activity increased after formation of nanocomposite with nano-chitosan (SeNPs/NCh) against several pathogens. The antibacterial activity (expressed as a diameter of the inhibitory zone) averaged between 2.1 and 4.3, 2.7 and 4.8 cm for SeNPs and SeNPs/NCh, respectively compared with 1.1 to 1.8 cm for Amoxicillin. The produced nanoselenium/chitosan was used as a biofilter to remove mercury (Hg) and AgNPs as model chemicals with serious toxicity and potential pollutant for water bodies in many industries. The new SeNPs/NCh biofilter has proven highly effective in individually removing mercury and AgNPs from their synthetic wastewaters, with an efficiency of up to 99%. Moreover, the removal efficiency of AgNPs stabilized at 99% after treating them with the syringe filter-Se nanocomposite for 4 cycles of treatment (5 min each).

Trace elements in liver and muscle tissues from wild waterfowls in Australia: Risk associated with human consumption in a global context.

Trace elements in game meats remain a point of concern for both the public and policymakers alike due to the human health implications if levels present are above guideline limits. This study aimed to: (1) determine trace element concentrations (As, Cd, Hg, Pb Cr, Cu, Se, Zn) in edible portions (breast meat and liver) of the four most frequently hunted duck Anatidae species inhabiting wetlands in Victoria, Australia, to identify the risk to human health from consumption; (2) investigate landscape-scale variables that may influence the detected concentrations and; (3) review the studies available (n = 41) in duck liver and muscle tissues from the 1970s to 2024, to contextualise the detected concentrations found on a global scale. Our study shows that ducks in Victoria had trace element concentrations below tolerable daily intake (TDI) guidelines for human health with one exception: notably high Hg in a filter-feeding specialist, the Pink-eared duck (Malacorhynchus membranaceus). Yet, the only trace element concentrations that were influenced by proximity to populated centres, were As and Zn. Compared to international reports, Pb concentrations in livers and muscle of Victorian waterfowl were lower, however, Pink-eared ducks had higher Hg than other duck (Anas spp.) species. Review of the worldwide data indicate that Pb concentrations in liver tissues from all Anas species have declined from the 1970s to 2024. This is the first study to identify this trend at a global scale. International movements towards Pb-shot bans, along with phasing out of Pb in gasoline and paint are the most likely cause of declining concentrations in tissues of wild waterfowl. These findings strongly underscore the importance of legislative efforts to limit trace elements entering the environment.

Risk assessment and origin of metals in chicken meat and its organs from a commercial poultry farm in Akwa Ibom state, Nigeria.

Contamination of chicken with metals is on the increase, despite its known attendant health risks to human consumers. The study aimed to evaluate the concentration of some metals in various organs of chicken, their sources, and the health risks they pose to human consumers. Samples of liver, meat, gizzard, borehole water, soil, diets, and droppings were investigated for the presence of some metals (Cr, Co, Mn, Zn, Al, As, Cd, Ni, and Hg), and their sources using principal component analysis (PCA). In addition, health risk assessment was manually computed using estimated daily intake (EDI), target hazard quotient (THQ), hazard index (HI), and carcinogenic risk (CR) parameters. Cr, Mn, Co, and Zn accumulated more in the liver, while Cd and Ni were only observed in the gizzard. The starter diet recorded higher levels of all the metals compared to the grower and finisher diets except for As. All the metals were detected in the poultry surrounding soil and the drinking water of the birds except for Hg. Furthermore, PCA implicated the soil, water, and diets of the birds as the sources of these metals. The THQ, HI, and CR due to the dietary intake of the gizzard indicate a risk of cancer in children and adults. There is a need to ensure that the identified sources of these metals (soil, water, and diets) are routinely monitored to ensure compliance with safety guidelines.

Adsorptive removal of toxic heavy metals from wastewater using water hyacinth and its biochar: A review.

Heavy metal contamination in aquatic ecosystems worsens due to rapid industrial expansion. Biochar, an efficient and economical adsorbent, has attracted much interest in environmental science, particularly in removing heavy metals (HMs). The paper covers basic details on biochar, its preparation, and potential chemical and inorganic modifications. Possible adsorption mechanisms of HMs on biochar, which include electrostatic attraction, ion exchange, surface complexation, chemical precipitation, and hydrogen bonding, are also discussed. These mechanisms are affected by the type of biochar used and the species of HMs present. Research findings suggest that while biochar effectively removes HMs, modifications to the carbon-rich hybrid can enhance surface properties such as surface area, pore size, functional groups, etc., and magnetic properties in a few cases, making them more efficient in HM removal. The choice of feedstock materials is one of the key parameters influencing the sorption capacity of biochars. This review aims to investigate the use of various forms of water hyacinth (WH), including aquatic plants, biomass, biochar, and modified biochar, as effective adsorbents for removing HMs from aqueous solutions and industrial effluents through a comparative analysis of their adsorption processes. However, further studies on the diverse effects of functional groups of modified biochar on HMs adsorption are necessary for future research.

The human health risks assessment posed by the presence of heavy metals in the rice varieties available in the Neyshabur market.

The present study was designed to determine the levels of heavy metals (Cu, Pb, Ni, Cr, Zn, Mn, Cd, and Co), Mn, and As in Iranian-grown rice and imported rice consumed in Neyshabur City. For this research, 90 samples from 30 different brands widely consumed in this city were collected. The content of heavy metals and the health risks associated with their use were then studied. The study found that Zn (14.21 mg kg-1) had the highest content in Iranian and imported rice varieties, whereas Cd (0.02 mg kg-1) had the lowest value. The health risk assessment was also done in three scenarios and separately for two types of rice. The results showed that the total hazard quotient (i.e., THQ) was measured for all metals and all three scenarios, and for both types of rice, it is THQ > 1, which indicates the risk of non-carcinogenic in rice. The cancer risk for three scenarios and two types of imported and Iranian rice is in the unsafe range for As (8.80 × 10-4 to 7.00 × 10-3), Ni (4.60 × 10-4 to 3.60 × 10-3) and Cr (2.20 × 10-4 to 1.90 × 10-3) and negligible for Pb (1.09 × 10-6 to 1.49 × 10-5) and Cd (7.83 × 10-6 to 8.20 × 10-5).

Impact of arsenic on male and female reproductive function: a review of the pathophysiology and potential therapeutic strategies.

Arsenic is a ubiquitous metalloid and heavy metal that contributes to the global decline in human fertility. Humans are constantly exposed to arsenic through biotic and abiotic sources, especially ingestion of arsenic-contaminated food and water. Its exposure is associated with several adverse health challenges, including reproductive toxicity. In spite of its reported adverse effects, arsenic exposure remains a global challenge. Hence, this study provides a comprehensive review of the literature on the impact and mechanism of arsenic on male and female reproductive function. Additionally, a review of the potential therapeutic strategies is presented. Evidence from the literature reveals that arsenic upregulates reactive oxygen species (ROS) generation which mediates arsenic-induced suppression of the hypothalamic-pituitary-gonadal axis and inactivation of 3ß-HSD and 17ß-HSD activities, leading to reduced gonadal steroidogenesis. Through several oxidative stress-dependent signaling, arsenic induces the apoptosis of the germ cells, thus contributing to the development of infertility. At the moment, there is no specific treatment for arsenic-induced reproductive toxicity. However, increasing data form the scientific literature reveals the benefits of antioxidants in ameliorating arsenic-induced reproductive toxicity. These molecules suppress ROS generation and maintain optimal activities of the hypothalamic-pituitary-gonadal axis, leading to optimal steroidogenesis and gametogenesis as well as improved germ cells. Overall, this study revealed the impact and associated mechanism of arsenic-induced reproductive toxicity. It also provides evidence from the literature demonstrating potential therapeutic measures in managing arsenic-induced reproductive toxicity.

An Overview of Hexavalent Chromium-Induced Necroptosis, Pyroptosis, and Ferroptosis.

Heavy metals are common environmental industrial pollutants. Due to anthropogenic activity, chromium, especially its hexavalent form [Cr(VI)], is a widespread environmental contaminant that poses a threat to human health. In this review paper, we summarize the currently reported molecular mechanisms involved in chromium toxicity with a focus on the induction of pro-inflammatory non-apoptotic cell death pathways such as necroptosis, pyroptosis, and ferroptosis. The review highlights the ability of chromium to induce necroptosis, pyroptosis, and ferroptosis revealing the signaling pathways involved. Cr(VI) can induce RIPK1/RIPK3-dependent necroptosis both in vitro and in vivo. Chromium toxicity is associated with pyroptotic NLRP3 inflammasome/caspase-1/gasdermin D-dependent secretion of IL-1ß and IL-18. Furthermore, this review emphasizes the role of redox imbalance and intracellular iron accumulation in Cr(VI)-induced ferroptosis. Of note, the crosstalk between the investigated lethal subroutines in chromium-induced toxicity is primarily mediated by reactive oxygen species (ROS), which are suggested to act as a rheostat determining the cell death pathway in cells exposed to chromium. The current study provides novel insights into the pro-inflammatory effects of chromium, since necroptosis, pyroptosis, and ferroptosis affect inflammation owing to their immunogenic properties linked primarily with damage-associated molecular patterns. Inhibition of these non-apoptotic lethal subroutines can be considered a therapeutic strategy to reduce the toxicity of heavy metals, including chromium.

Investigation of radioactivity and heavy metal levels in soil samples from neutral and vegetation land of Punjab, India.

In this work, radioactivity investigations of soil samples from neutral and agricultural sites in Punjab (India) have been carried out to study the impact of land use patterns. Analyzing soil samples radiological, mineralogical, and physicochemical attributes has employed state-of-the-art techniques. The mean activity concentration of 238U/226Ra, 232Th, 40K, 235U, and 137Cs, measured using a carbon fiber endcap p-type HPGe detector, in neutral land was observed as 58.03, 83.95, 445.18, 2.83, and 1.16 Bq kg-1, respectively. However, in vegetation land, it was found to be 40.07, 64.68, 596.74, 2.26, and 1.90 Bq kg-1, respectively. In the detailed activity analysis, radium equivalent (Raeq) radioactivity is in the safe prescribed limit of 370 Bq kg-1 for all investigated soil samples. However, the dosimetric investigations revealed that the outdoor absorbed gamma dose rate (96.08 nGy h-1) and consequent annual effective dose rate (0.12 mSv y-1) for neutral land and the gamma dose rate (82.46 nGy h-1) and subsequent annual effective dose rate (0.10 mSv y-1) for vegetation land marginally exceeded the global average. The soil's physicochemical parameters (pH, EC, and porosity) from both sites were measured, and their correlations with radionuclides were analyzed. Various heavy metals of health concern, namely, chromium (Cr), arsenic (As), copper (Cu), cobalt (Co), cadmium (Cd), lead (Pb), mercury (Hg), selenium (Se), and zinc (Zn), were also evaluated in soil samples using Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS). Pollution Load Index (PLI) and Ecological Risk Index (RI) revealed that vegetation land was more anthropogenically contaminated than neutral land, with maximum contamination from Hg and As.

Agricultural waste-based biochars for sustainable removal of heavy metals from stabilized landfill leachate.

In this work, biochars were used as adsorbents to remove Cu, Cd, and Zn ions in a real stabilized leachate from a controlled landfill. Oak fruit shells biochar (OFSBC) and date palm fibers biochar (DPFBC) were obtained by pyrolysis of oak fruit shells and date palm fibers at 700 °C and 400 °C, respectively. OFSBC and DPFBC showed well-developed structures and high specific surface areas (520.16 m2/g and 470.46 m2/g, respectively). Equilibrium adsorption of heavy metal ions on DPFBC and OFSBC occurred after 4 h and 2 h of stirring. The removal efficiencies of Cu, Cd, and Zn ions were 97.01%, 94.40%, and 80.59% with DPFBC and 90.10%, 88.33%, and 76.16% using OFSBC, respectively. The Avrami fractional order model was appropriate for describing kinetic adsorption. Increasing the dose of adsorbent improves heavy metal ion retention. Thermodynamic tests have proven the spontaneous and endothermic adsorption of these heavy metals. The electrostatic attraction, ion exchange, complexation, metal-π bending, and surface precipitation and pore filling were regarded as the most predominant heavy metal retention mechanisms from the landfill leachate onto the biochar surface. Separately, the DPFBC showed the best performance than OFSBC regarding the improvement of leachate quality. Chemical oxygen demand (COD), biological oxygen demand (BOD5), ammoniacal nitrogen (NH3-N), and phosphorus (P) were respectively removed at an efficiency of 53.57%, 29.17%, 36.07%, and 37.5%, respectively. Thus, the results allow highlighting that the adsorption on DPFBC and OFSBC can be an effective alternative in the practice of landfill leachate treatment.

A Comparative Study to Explore the Variability of Heavy Metal Concentration in the Teeth of Residents of Non-gated Versus Gated Societies.

Human populations face increasing exposure to heavy metals, which pose significant health risks. Dental tissues, such as dentin and enamel, provide a reliable biomarker for assessing long-term heavy metal exposure due to their stable nature. This study aims to explore the variability of heavy metal concentrations in the teeth dentine of residents living in gated versus non-gated societies near the Yamuna River around the Jamia Millia Islamia, New Delhi, India. Sixty-nine participants were enrolled, 27 from gated societies and 42 from non-gated societies. Participants underwent elective dental extraction, following which heavy metal concentrations were measured in extracted tooth dentine using atomic absorption spectrophotometry. Demographic data including age, gender, tooth types, and drinking water sources were recorded. Statistical analysis included Mann-Whitney's test, Spearman correlation heatmap, and principal component analysis (PCA). Residents of non-gated societies exhibited significantly (p < 0.005) higher mean concentrations of heavy metals compared to gated societies except for cadmium (p = 0.495). Subgroup analysis based on drinking water sources revealed significant (p < 0.001) variations in heavy metal concentrations, suggesting the influence of water quality on environmental exposure. PCA provided insights into underlying trends and correlations among heavy metal variables. This study provides valuable insights into heavy metal contamination among residents living near the Yamuna River, highlighting disparities in exposure based on residential environment and drinking water sources. Participants from non-gated societies exhibited higher mean concentrations of heavy metals compared to those from gated societies, emphasizing the influence of socio-economic factors, urban infrastructure and environmental management practices on heavy metal accumulation. The study's findings underscore the need for targeted interventions to address heavy metal exposure across diverse population groups, improve water quality standards, and enhance access to safe drinking water.

Metals and other trace elements in plasma and feathers of seabirds breeding in Svalbard.

We assessed the concentrations of metals and other trace elements in two of the most common seabird species breeding on Svalbard, the black-legged kittiwake (Rissa tridactyla) and the Brünnich's guillemot (Uria lomvia). Both of these species feed mostly on fish and crustaceans but have different foraging strategies, kittiwakes being surface feeders while guillemots are divers. We investigated the concentrations of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), lead (Pb), selenium (Se) and zinc (Zn) in the plasma and body feathers of black-legged kittiwakes (n = 17), as well as in the body feathers of Brünnich's guillemots (n = 13). Samples were collected from adult birds at two time points, one week apart during July 2017 in Kongsfjorden, Svalbard. Of the non-essential trace elements, As was found at the highest median concentration at both the first (56.23 ng/g ww) and second (39.99 ng/g ww) sampling timepoints in the kittiwake plasma. When separating for the sexes, as well as sampling time, males sampled at the first sampling time point had significantly higher concentrations of As (median at 0.087 ng/g versus 0.039 ng/g) and Se (median 0.26 ng/g versus 0.16 ng/g) compared to males sampled at the second time point. There was no significant difference in plasma concentrations between females at first and second sampling time points. Kittiwake feathers contained significantly higher concentrations of As, Cd and Hg than guillemot feathers, while guillemot feathers had significantly higher concentrations of Cu, Pb and Zn. However, of the non-essential elements in both kittiwake and guillemot feathers Hg was found with the highest median concentrations at 5160 and 1080 ng/g, respectively, thus in kittiwakes exceeding the level of 5000 ng/g associated with adverse effect (e.g., impaired reproduction). Levels of Hg and Se found in the kittiwake feathers were higher than previous studies on seabirds in the Arctic.

Mastering granular activated carbon filtration to remove organic micropollutants, antibiotic resistance and metals for municipal wastewater reuse.

GAC filtration of municipal wastewater was optimized and intensified, making its implementation and operation directly after secondary clarification possible and relevant. GAC was first selected based on laboratory tests. Performances on organic micropollutants were linked to the repartition of BET surface between micropores and meso/macropores. At pilot scale, in order to limit the impact of head loss, downflow declogging sequences (DCS) were implemented and upflow filtration tested. 6 to 12 DCS per day led to a 4.7-5.5-fold increase of particles retention capacity between backwashes (cycle duration of 20-120 h), and upflow operations improved head loss evolution profile with only a slight GAC (<15 %) expansion. DCS allows backwash frequency reduction, enabling significant water savings. Both adaptations maintained high organic micropollutants removals compared to a review of 16 GAC studies at pilot or full-scale, results being in the upper range. A specific dose of 2.0-2.5 g GAC/gC was necessary to obtain an average removal of pharmaceuticals and benzotriazole of 80 % at 20 min contact time, which is comparable to PAC and low granulometry GAC. Higher doses are needed for PFAS but >80 % removals are achievable. Particles, TKN, particulate phosphorus and organic matter are well removed by GAC filtration in both configurations. Biological activity is observed through nitrogen transformation in the GAC bed. Heavy metals are greatly removed in GAC filtration, in particular Cd, Cu, Ni and Pb, probably through biosorption onto the biofilm, developed within the GAC bed. For wastewater reuse applications, GAC filtration has an added value through physicochemical quality improvement and fecal contamination indicators removal of 1 log, facilitating the implementation and optimizing the design of a post-disinfection. Antibiotic resistant bacteria and antibiotic resistance genes are also partially retained in GAC filtration. Finally, biological wastewater treatments combined to GAC filtration is a good solution to effectively treat organic micropollutants together with heavy metals and preparing post-disinfection for reuse.

Assessing impact of elevated CO2 on heavy metal accumulation in crops: meta-analysis and implications for food security.

Human activities led to elevation in carbon dioxide (CO2) concentrations in atmosphere. While such increase per se may be beneficial for the growth of some crops, it comes with a caveat of affecting crop nutritional status. Here, we present a comprehensive analysis of changes in concentration of essential (Cu, Fe, Mn, Zn, Mo, Ni) and non-essential (Ba, Cd, Cr, Hg, Pb, and Sr) heavy metals in response to elevated CO2, drawing on a meta-analysis of 1216 paired observations. The major findings are as follows: (1) Elevated CO2 leads to reduced concentrations of Cu, Fe, Mn, and Zn in crops; (2) the extent of above reduction varies among plants species and is most pronounced in cereals and then in legumes and vegetables; (3) reduction in accumulation of non-essential (toxic) metals is less pronounced, potentially leading to an unfavorable essential/non-essential metal ratio in plants; (4) the above effects will come with significant implication to human health, exacerbating effects of the "hidden hunger" caused by the lack of Fe and Zn in the human diets. The paper also analyses the mechanistic basis of nutrient acquisition (both at physiological and molecular levels) and calls for the changes in the governmental policies to increase efforts of plant breeders to create genotypes with improved nutrient use efficiency for essential micronutrients while uncoupling their transport from non-essential (toxic) heavy metals.

Contamination of toxic elements in the sediments, water, and igneous rocks of the Sefid-rud River in Northern Iran using contamination indicators, with a specific focus on Ti-rich coastal sediments.

The Sefid-rud River is a significant river on the southern coast of the Caspian Sea in Iran. In this study, we collected 28 samples of surface sediments and water to assess the level of metal contamination. Chemical analysis revealed that the average concentrations of heavy metals in both sediments and water increase from upstream to downstream. There is no clear significant relationship observed between changes in the values of investigated elements in sediments and water. The levels of these elements in the sediments, exceed toxic response thresholds. In the water samples, As, Ni and V concentrations exceed the WHO standard values. According to the Igeo, EF and PLI indices, the sediments at most stations are not contaminated by any of the elements. The CF and Dc indices suggest low contamination levels at all stations. The NIPI and ecological risk indices (Er and RI) indicate non-polluted conditions at all stations except SF22, SF20, SF11, and SF6. The MI and HEI indices indicate pollution in all water samples of the Sefid-rud, but critical values are only observed at SF5 and SF15. The other stations show no contamination. The Cf index indicates high pollution levels for all elements except Cu, Zn, and Pb. The upstream area poses a relatively high and considerable ecological risk according to the PERI index. In conclusion, the sediments of the Sefid-rud River have a higher potential for the exchange of toxic substances compared to the aquatic environment.

Assisted Phytoremediation between Biochar and Crotalaria pumila to Phytostabilize Heavy Metals in Mine Tailings.

The increasing demand for mineral resources has generated mine tailings with heavy metals (HM) that negatively impact human and ecosystem health. Therefore, it is necessary to implement strategies that promote the immobilization or elimination of HM, like phytoremediation. However, the toxic effect of metals may affect plant establishment, growth, and fitness, reducing phytoremediation efficiency. Therefore, adding organic amendments to mine tailings, such as biochar, can favor the establishment of plants, reducing the bioavailability of HM and its subsequent incorporation into the food chain. Here, we evaluated HM bioaccumulation, biomass, morphological characters, chlorophyll content, and genotoxic damage in the herbaceous Crotalaria pumila to assess its potential for phytostabilization of HM in mine tailings. The study was carried out for 100 days on plants developed under greenhouse conditions under two treatments (tailing substrate and 75% tailing/25% coconut fiber biochar substrate); every 25 days, 12 plants were selected per treatment. C. pumila registered the following bioaccumulation patterns: Pb > Zn > Cu > Cd in root and in leaf tissues. Furthermore, the results showed that individuals that grew on mine tailing substrate bioaccumulated many times more metals (Zn: 2.1, Cu: 1.8, Cd: 5.0, Pb: 3.0) and showed higher genetic damage levels (1.5 times higher) compared to individuals grown on mine tailing substrate with biochar. In contrast, individuals grown on mine tailing substrate with biochar documented higher chlorophyll a and b content (1.1 times more, for both), as well as higher biomass (1.5 times more). Therefore, adding coconut fiber biochar to mine tailing has a positive effect on the establishment and development of C. pumila individuals with the potential to phytoextract and phytostabilize HM from polluted soils. Our results suggest that the binomial hyperaccumulator plant in combination with this particular biochar is an excellent system to phytostabilize soils contaminated with HM.