Dieldrin accumulation, distribution in plant parts and phytoextraction potential for several plant species and Cucurbita pepo varieties

Dieldrin, an organochlorine pesticide (OCP) widely used for crop protection in the second half of the 20th century till the 70's, is worldwide still present in arable soils. It can be transferred to crops, notably cucurbits, depending on plant species and cultivars. Finding strategies to decrease OCP bioavailability in soil is therefore a main concern. Phytomanagement strategies could provide (i) ready-to-use short term solution for maintaining the production of edible plant parts with dieldrin concentrations below the Maximum Residue Limits (MRL) and (ii) long-term solution for dieldrin phytoextraction reducing progressively its bioavailability in the soil. This field study aimed at determining dieldrin accumulation capacities and allocation pattern in 17 non-Cucurbitaceae species and 10 Cucurbita pepo varieties, and assessing the dieldrin phytoextraction potential of these plant species when grown to maturity in a historically dieldrin-contaminated soil. Out of the non-Cucurbitaceae species, vetiver was the only one able to accumulate significant amounts of dieldrin, which mainly remained in its roots. All C. pepo varieties were able to uptake and translocate high dieldrin amounts into the shoots, leading to the highest phytoextraction potential. Despite the intraspecific variability in dieldrin concentration in zucchini plant parts, mainly in the reproductive organs, the phytoextraction capacity for shoots and fruits was high for all tested varieties (147 to 275 μg dieldrin plant-1, corresponding to 5.6 % of the n-heptane extractable soil dieldrin), even for the one with low fruit dieldrin concentration. Both food safety and phytoextraction could be achieved by selecting productive zucchini varieties displaying low dieldrin concentration in fruits and high one in shoots.

Recycling composted human feces as biofertilizer for crop production: Assessment of soil and lettuce plant tissue contamination by Escherichia coli and human adenovirus

Using waste from sewage systems, particularly human excreta, could save resources and increase soil fertility, contributing to nutrient management. However, because of the pathogenic content in human feces, this resource can pose health risks to farmers and consumers. Therefore, this work analyzed the behavior of the microorganisms: Escherichia coli ATCC13706 and human adenovirus (HAdV-2) in the soil and the internal part of the plant tissue during the vegetative stage after applying spiked composted human feces as biofertilizer. In a greenhouse, we simulated the application of the biofertilizer in lettuce cultivation by spiking three concentrations of E. coli (6.58, 7.31, and 8.01 log10 CFU.g-1) and HAdV-2 (3.81, 3.97, and 5.92 log10 PFU.g-1). As a result, we achieved faster decay in soil at higher concentrations of E. coli. We estimated linear decay rates of -0.07279, -0.09092, and -0.115 days, corresponding to T90s of 13.7, 11.0, and 8.6 days from higher to smaller concentrations of E. coli, respectively. The estimated periods for the inactivation of 4 logarithmic units of E. coli bacteria in soil are longer than the cultivation period of lettuce for all concentrations studied. Concerning the bacterial contamination in plants, we found E. coli in the internal part of the leaves at the highest concentration tested during the first three weeks of the experiment. Furthermore, HAdV-2 was found in roots at a stable concentration of 2-2.3 log10 PFU.g-1 in five of the six samples analyzed. Therefore, bacterial infection could pose a risk, even if fresh greens are washed before consumption, especially for short-term cultures. Regarding viral infection, a positive result in the roots after disinfection may pose a risk to root and tubercule vegetables. These discoveries highlight the importance of conducting comprehensive evaluations of hygiene practices in incorporating organic amendments in crops, explicitly aiming to minimize the risk of post-contamination.

Numerical modeling of PFAS movement through the vadose zone: Influence of plant water uptake and soil organic carbon distribution

In this study, we investigated the effects of soil organic carbon (SOC) distribution and water uptake by plant roots on PFAS movement in the vadose zone with a deep groundwater table under temperate, humid climate conditions. Two series of numerical simulations were performed with the HYDRUS computer code, representing the leaching of historical PFOS contamination and the infiltration of water contaminated with PFOA, respectively. We considered soil profiles with three distributions of SOC (no SOC, realistic SOC distribution decreasing with depth, and uniform SOC equal to the content measured in topsoil), three root distributions (bare soil, grassland, and forest), and three soil textures (sand, sandy loam, and loam). The SOC distribution had a profound impact on the velocity of PFOS movement. The apparent retardation factor for realistic SOC distribution was twice as large as for the scenario with no SOC and more than three times smaller than for the scenario with uniformly high SOC content. We also showed that the root distribution in soil profoundly impacts the simulations of PFAS migration through soil. Including the root zone significantly slows down the movement of PFAS, primarily due to increased evapotranspiration and reduced downward water flux. Another effect of water uptake by plant roots is an increase of PFAS concentrations in soil water (evapo-concentration). The evapo-concentration and the slowdown of PFAS movement due to root water uptake are more significant in fine-textured soils than in sand.

Determination of threshold values and heavy metal pollution assessment of soils in an industrial area in Ghana

Industrial activities have the potential to pollute soils with a wide variety of heavy metals (HMs). In Ghana, however, assessment of HM pollution of soils in industrial areas remains limited. Accordingly, HM soil pollution in one of the industrial areas in Accra, Ghana was assessed. Soil samples were taken and analysed for HMs, including Fe, Zr, Zn, Ti, Sr, Rb, Mn, Pb, Cu, and Co, using X-Ray Fluorescence (XRF). HM geochemical threshold values (GTVs) were determined to establish soil HM pollution levels and identify areas needing remediation. Furthermore, risk assessments were conducted to evaluate the potential ecological and human health risks associated with these metals. The mean concentrations of Fe, Zn, Rb, Sr, Zr, Ti, Mn, Co, Cu, and Pb in the soils were: 27133.83, 147.72, 16.30, 95.95, 307.11, 4663.66, 289.85, 418.54, 44.97, and 112.88 mg/kg, respectively. Generally, the concentrations of HMs decreased with depth, although some lower layers exhibited elevated HM levels. Soil pollution levels were categorized as low for Fe, Rb, Zr, Ti, Mn, Co, and Cu; moderate for Sr and Zn; and considerable for Pb. Notably, the northwestern part of the study area displayed a considerable to very high degree of HM contamination. While HMs in the soils posed low ecological risk, the human health risk assessment indicated potential health effects from Co, particularly in children. The presence of HMs in the soils was noted to originate from both natural geological phenomena and human activities, including industrial operations, agricultural practices, landfill activities, and vehicular emissions.

Recent trends in the phytoremediation of radionuclide contamination of soil by cesium and strontium: Sources, mechanisms and methods: A comprehensive review

This comprehensive review examines recent trends in phytoremediation strategies to address soil radionuclide contamination by cesium (Cs) and strontium (Sr). Radionuclide contamination, resulting from natural processes and nuclear-related activities such as accidents and the operation of nuclear facilities, poses significant risks to the environment and human health. Cs and Sr, prominent radionuclides involved in nuclear accidents, exhibit chemical properties that contribute to their toxicity, including easy uptake, high solubility, and long half-lives. Phytoremediation is emerging as a promising and environmentally friendly approach to mitigate radionuclide contamination by exploiting the ability of plants to extract toxic elements from soil and water. This review focuses specifically on the removal of 90Sr and 137Cs, addressing their health risks and environmental implications. Understanding the mechanisms governing plant uptake of radionuclides is critical and is influenced by factors such as plant species, soil texture, and physicochemical properties. Phytoremediation not only addresses immediate contamination challenges but also provides long-term benefits for ecosystem restoration and sustainable development. By improving soil health, biodiversity, and ecosystem resilience, phytoremediation is in line with global sustainability goals and environmental protection initiatives. This review aims to provide insights into effective strategies for mitigating environmental hazards associated with radionuclide contamination and to highlight the importance of phytoremediation in environmental remediation efforts.

Remediation potential of an immobilized microbial consortium with corn straw as a carrier in polycyclic aromatic hydrocarbons contaminated soil

Polycyclic aromatic hydrocarbons (PAHs) are widespread in soils and threaten human health seriously. The immobilized microorganisms (IM) technique is an effective and environmentally sound approach for remediating PAH-contaminated soil. However, the knowledge of the remedial efficiency and the way IM operates using natural organic materials as carriers in complex soil environments is limited. In this study, we loaded a functional microbial consortium on corn straw to analyze the effect of IM on PAH concentration and explore the potential remediation mechanisms of IM in PAH-contaminated soil. The findings revealed that the removal rate of total PAHs in the soil was 88.25% with the application of IM after 20 days, which was 39.25% higher than the control treatment, suggesting that IM could more easily degrade PAHs in soil. The findings from high-throughput sequencing and quantitative PCR revealed that the addition of IM altered the bacterial community structure and key components of the bacterial network, enhanced cooperative relationships among bacteria, and increased the abundance of bacteria and functional gene copies such as nidA and nahAc in the soil, ultimately facilitating the degradation of PAHs in the soil. This study enhances our understanding of the potential applications of IM for the treatment of PAH-contaminated soil.

Polycyclic aromatic hydrocarbons and their halogenated derivatives in soil from Yellow River Delta: Distribution, source apportionment, and risk assessment

The distribution of polycyclic aromatic hydrocarbons (PAHs) and halogenated PAHs (HPAHs) in surface soils from the petroleum industrial area of the Yellow River Delta (YRD) in China were investigated. The total concentrations of 16 PAHs ranged from 19.6 to 1560 ng/g, while 22 HPAHs ranged from 2.44 to 14.9 ng/g. Moreover, a high degree of spatial distribution heterogeneity was observed for both PAHs and HPAHs, which is likely attributed to the distinct industrial activities in studied area. The combustion of biomass and petroleum were identified as primary sources of soil PAHs and HPAHs in the YRD. Furthermore, benzo[b]fluoranthene, benzo[k]fluoranthene, and benzo[g,h,i]perylene exhibited high ecological risks (with risk quotients of 1.47, 1.44, and 1.02, respectively) in specific sites within the YRD. Considering the high toxicity of HPAHs and their potential joint environmental effects with PAHs, continuous attention should be directed towards the environmental risks associated with both PAHs and HPAHs.

Soil pollution indices and health risk assessment of metal(loid)s in the agricultural soil of pistachio orchards

Elevated levels of metal(loid)s in soil may pose potential threats to the ecosystem and can be harmful for human health. The concentrations of As, Cd, Pb, Cr and Ni were determined in agricultural soil collected from 45 pistachio orchards around Feizabad city, Khorasan Razavi province, Iran using ICP-OES. Also, soil pollution indices including contamination factor (CF), pollution load index (PLI) and geo-accumulation index (Igeo) were evaluated. In addition, non-carcinogenic and carcinogenic risk indices were estimated. The mean concentrations of metal(loid)s were in the order of Ni = 466.256 > Cr = 120.848 > Pb = 12.009 > As = 5.486 > Cd = 0.394 mg/kg. Concentrations of As, Cd and Pb in the soil samples were within their respective permissible limits set by World Health Organization (WHO). But concentrations of Cr and Ni in 84.4 and 100% of the samples, respectively exceeded the WHO allowable limits. The CF, PLI and Igeo showed that soil of some of the pistachio orchards was contaminated with some metals. The possible sources of the metals in the soil are application of pesticides, chemical fertilizers, manures as well as irrigation water. Hazard quotient (HQ) ad Hazard index (HI) values from soil of all the orchards were found to be well below the respective threshold limit (1), suggesting that there is no immediate non-cancer threat arising from the contamination at all the orchards with metal(loid)s for children and adults. The highest cancer risk values (1.13E-02 for children and 1.25E-03 for adults) were estimated for Ni in the soil. Collectively, this study provides valuable information to improve the soil in the pistachio orchards to reduce metal(loid)s contamination and minimize the associated health risks to the population in the area.

Phytoremediation by trees as a nature-based solution for mitigating metal contamination in urban soils

Trace metals in the environment are important pollutants affecting human health, particularly in urban areas worldwide. Phytoremediation as a nature-based solution (NBS) and environmentally friendly technology may decrease high concentrations of trace metals in urban soils, protecting public health (especially children) and contributing to urban sustainability. This study examined trace metal contamination of urban soils and trees in six cities in the Republic of Srpska (RS), Bosnia and Herzegovina (BiH) and investigated the potential of selected tree species for phytoremediation as a NBS for metal-polluted urban soils. Contamination of urban soils was assessed by quantifying the concentrations of 11 trace metals (B, Ba, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, and Zn). To estimate phytoremediation potential of urban tree species, concentration and bioconcentration factor of the 11 metals were quantified in leaves of three common and abundant tree species: Aesculus hippocastanum L. (horse chestnut), Platanus acerifolia Willd. (plane), and Tilia sp. (lime). The results showed that trace metal concentrations in leaf samples did not exceed toxicity threshold guideline values. Further assessments are needed to establish the true potential of the three species as NBS for urban soils.

First national reference of microplastic contamination of French soils

The recent emergence of studies on plastic contamination of terrestrial environments has revealed the presence of microplastics (MP) in a variety of soil types, from the most densely populated areas to the most remote ones. However, the concentrations and chemical natures of MP in soils vary between studies, and only a few ones have focused on this issue in France. The MICROSOF project aimed to establish the first national references for French soil contamination by microplastics. 33 soil samples randomly chosen on the French soil quality-monitoring network were analyzed. The study collected data on the abundance of microplastics in the [315-5000] μm range, their chemical nature and size, as well as mass abundance estimates and other relevant information. Results demonstrated that 76 % of the soil samples contained microplastics, in concentrations ranging from <6.7 to 80 MP.kg-1 (dry soil). Most samples from croplands, grasslands and vineyards and orchards were contaminated, whereas only one sample from forest contained MP, suggesting an increased risk of microplastic contamination in soils exposed to agricultural practices. The MP abundances are not statistically different from similar studies, indicating an intermediate level of contamination in French soils. Despite intervention reports and surveys, the sources remain unclear at this stage. For the first time, an overview of the state of soil contamination in France, as well as the potential risks is provided.

Characteristics, source analysis, and health risk assessment of potentially toxic elements pollution in soil of dense molybdenum tailing ponds area in central China

The issue of potentially toxic elements (PTEs) contamination of regional soil caused by mining activities and tailings accumulation has attracted wide attention all over the world. The East Qinling is one of the three main molybdenum mines in the world, and the concentration of PTEs such as Hg, Pb and Cu in the slag is high. Quantifying the amount of PTEs contamination in soil and identifying potential sources of contamination is vital for soil environmental management. In the present investigation, the pollution levels of 8 PTEs in the Qinling molybdenum tailings intensive area were quantitatively identified. Additionally, an integrated source-risk method was adopted for resource allocation and risk assessment based on the PMF model, the ecological risk, and the health risk assessment model. The mean concentrations of Cu, Ni, Pb, Cd, Cr, Zn, As, and Hg in the 80 topsoil samples ranged from 0.80 to 13.38 times the corresponding background values; notably high levels were observed for Pb and Hg. The source partitioning results showed that PTEs were mainly affected by four pollution sources: natural and agricultural sources, coal-burning sources, combined transport and mining industry sources, and mining and smelting sources. The health risk assessment results revealed that the risks of soil PTEs for adults are acceptable, while the risks for children exceeded the limit values. The obtained results will help policymakers to obtain the sources of PTEs of tailing ponds intensive area. Moreover, it provides priorities for the governance of subsequent pollution sources and ecological restoration.

Insights into the biogeochemical transformation, environmental impacts and biochar-based soil decontamination of antimony

Every year, a significant amount of antimony (Sb) enters the environment from natural and anthropogenic sources like mining, smelting, industrial operations, ore processing, vehicle emissions, shooting activities, and coal power plants. Humans, plants, animals, and aquatic life are heavily exposed to hazardous Sb or antimonide by either direct consumption or indirect exposure to Sb in the environment. This review summarizes the current knowledge about Sb global occurrence, its fate, distribution, speciation, associated health hazards, and advanced biochar composites studies used for the remediation of soil contaminated with Sb to lessen Sb bioavailability and toxicity in soil. Anionic metal(loid) like Sb in the soil is significantly immobilized by pristine biochar and its composites, reducing their bioavailability. However, a comprehensive review of the impacts of biochar-based composites on soil Sb remediation is needed. Therefore, the current review focuses on (1) the fundamental aspects of Sb global occurrence, global soil Sb contamination, its transformation in soil, and associated health hazards, (2) the role of different biochar-based composites in the immobilization of Sb from soil to increase biochar applicability toward Sb decontamination. The review aids in developing advanced, efficient, and effective engineered biochar composites for Sb remediation by evaluating novel materials and techniques and through sustainable management of Sb-contaminated soil, ultimately reducing its environmental and health risks.

Effect of biological sewage sludge and its derived biochar on accumulation of potentially toxic elements by corn (Zea mays L.)

The land application of sewage sludge can cause different environmental problems due to the high content of potentially toxic elements (PTEs). The objective of this study was to compare the effect of urban biological sewage sludge (i.e. the waste of activated sludge process) and its derived biochar as the soil amendments on the bioavailability of PTEs and their bioaccumulation by corn (Zea mays L.) under two months of greenhouse conditions. The soil was treated by adding biochar samples at 0 (control), 1, 3, 5% w/w. The diethylenetriamine pentaacetic acid (DTPA)-extractable concentrations of PTEs including Zn, Pb, Cd, Cr, Ni, Fe, and Cu in soil and their accumulation by plant shoot and root were measured. Conversion of the biological sewage sludge into the biochar led to decrease the PTEs bioavailability and consequently decreased their contents in plant tissues. The DTPA extractable metal concentrations of produced biochar in comparison to the biological sewage sludge reduced 75% (Cd), 65% (Cr), 79% (Ni and Pb), 76% (Zn), 91% (Cu) and 88% (Fe). Therefore, the content of Ni, Fe, Zn and Cd in corn shoot was decreased 61, 32, 18 and 17% respectively in application of 5% biochar than of raw sewage sludge. Furthermore, the application of 5% biochar enhanced the physiological parameters of the plants including shoot dry weight (twice) and wet weight (2.25 times), stem diameter (1.70 times), chlorophyll content (1.03 times) in comparison to using 5% raw sewage sludge. The results of the study highlight that application of the biochar derived from urban biological sewage sludge in soil could decrease the risk of PTEs to the plant.

Geochemical distribution and environmental assessment of potentially toxic elements in farmland soils, sediments, and tailings from phosphate industrial area (NE Algeria)

This study investigates the extent and spatial distribution of Potentially Toxic Elements (PTEs) in the Djebel Onk phosphate mine area in south-eastern Algeria, as well as the associated risks to human health. Various scales are considered and sampled, including tailing waste (n = 8), surrounding farmland soil (n = 21), and sediments (n = 5). The samples were mineralogically and chemically analyzed using XRD, FTIR, XRF, and ICP-MS techniques. Principal Component Analysis (PCA) was applied after transforming the raw data into centered-log ratios (clr) to identify the dominant factors controlling the distribution of PTEs. Furthermore, pollution assessment was conducted using several indices, including geo-accumulation, pollution load, contamination security indices, and enrichment and contamination factors. The results reveal that the analyzed samples are mostly P-enriched in the mine tailings, farmland soil, and sediments, with P2O5 concentrations ranging from 13.37 wt% to 26.17 wt%, 0.91-21.70 wt%, and 17.04-29.41 wt%, respectively. The spatial distribution of PTEs exhibits clearly a decrease in the contents of CaO, P2O5, Cr, Sr, Cd, and U with increasing distance from the mine discharge site, while other oxides, such as MgO, Al2O3, SiO2, K2O, and Fe2O3, and associated elements (Cu, Co, Pb, and Zn), show an increase. PCA confirms the influence of minerals such as, apatite, dolomite, and silicates on the distribution PTEs. It denoted that the highest contamination level of all PTEs in soils and sediments was observed in the southern part of the plant and mine tailings compared to the northern part. In terms of human health risks, the assessment reveals that the hazard index (HI) values for both non-carcinogenic and carcinogenic risks associated with PTEs in the study area are below 1, suggesting no significant risk. However, regardless of the sample type, the lifetime cancer risk (LCR) values vary from 1.69E-05-2.11E-03 and from 1.03E-04-2.27E-04 for Cr, Ni, As (children) and Cd (adults), respectively, exceeding the safe levels recommended by the United States Environmental Protection Agency. The study highlights that oral ingestion poses the greatest risk, followed by dermal contact and particle inhalation. Importantly, all these indices decrease with increasing distance from the sampling site to the waste discharge point and the factory, which indicates that the phosphate mining activity had caused some extent risks. These findings provide valuable insights for mitigating the adverse health impacts and guiding environmental management efforts.

Evaluating a mass balance model for soil trace metals using the historical data from the King's Kitchen Garden (Versailles, France)

The mass balance of reconstituted Cd, Cu, Pb and Zn fluxes from 1683 to 2021 was compared to the current levels of the soil used only for vegetable production in the King's Kitchen Garden in Versailles (France). This comparison was made on the basis of 4 scenarios of organic matter application in the 18th and 19th centuries and by an uncertainty analysis over the entire period. The topsoil contamination falls within that of French kitchen gardens. Modelling of past fluxes predicted the correct trend (an increase) and order of magnitude of the soil metal contents. It produced a relatively accurate evaluation of the Cu and Zn contents. The model underestimated the Pb contents by about 80%, revealing a large and unknown source of soil contamination by this metal. The calculation overestimated the current Cd levels by about 100%, probably due to various biases, for example on atmospheric fallout or the composition of organic amendments. This assessment shows that modelling the mass balance of trace metal fluxes can be used to predict the long-term trend in the levels of these elements in cultivated soils, providing the input data are chosen according to realistic scenarios.

Modeling arsenic in European topsoils with a coupled semiparametric (GAMLSS-RF) model for censored data

Arsenic (As) is a versatile heavy metalloid trace element extensively used in industrial applications. As is carcinogen, poses health risks through both inhalation and ingestion, and is associated with an increased risk of liver, kidney, lung, and bladder tumors. In the agricultural context, the repeated application of arsenical products leads to elevated soil concentrations, which are also affected by environmental and management variables. Since exposure to As poses risks, effective assessment tools to support environmental and health policies are needed. However, the most comprehensive soil As data available, the Land Use/Cover Area frame statistical Survey (LUCAS) database, contains severe limitations due to high detection limits. Although within International Organization for Standardization standards, the detection limits preclude the adoption of standard methodologies for data analysis. The present work focused on developing a new method to model As contamination in European soils using LUCAS soil samples. We introduce the GAMLSS-RF model, a novel approach that couples Random Forests with Generalized Additive Models for Location, Scale, and Shape. The semiparametric model can capture non-linear interactions among input variables while accommodating censored and non-censored observations and can be calibrated to include information from other campaign databases. After fitting and validating a spatial model, we produced European-scale As concentration maps at a 250 m spatial resolution and evaluated the patterns against reference values (i.e., two action levels and a background concentration). We found a significant variability of As concentration across the continent, with lower concentrations in Northern countries and higher concentrations in Portugal, Spain, Austria, France and Belgium. By overcoming limitations in existing databases and methodologies, the present approach provides an alternative way to handle highly censored data. The model also consists of a valuable probabilistic tool for assessing As contamination risks in soils, contributing to informed policy-making for environmental and health protection.

Heavy metals prediction in coastal marine sediments using hybridized machine learning models with metaheuristic optimization algorithm

This study proposes different standalone models viz: Elman neural network (ENN), Boosted Tree algorithm (BTA), and f relevance vector machine (RVM) for modeling arsenic (As (mg/kg)) and zinc (Zn (mg/kg)) in marine sediments owing to anthropogenic activities. A heuristic algorithm based on the potential of RVM and a flower pollination algorithm (RVM-FPA) was developed to improve the prediction performance. Several evaluation indicators and graphical methods coupled with visualized cumulative probability function (CDF) were used to evaluate the accuracy of the models. Akaike (AIC) and Schwarz (SCI) information criteria based on Dickey-Fuller (ADF) and Philip Perron (PP) tests were introduced to check the reliability and stationarity of the data. The prediction performance in the verification phase indicated that RVM-M2 (PBAIS = -o.0465, MAE = 0.0335) and ENN-M2 (PBAIS = 0.0043, MAE = 0.0322) emerged as the best model for As (mg/kg) and Zn (mg/kg), respectively. In contrast with the standalone approaches, the simulated hybrid RVM-FPA proved merit and the most reliable, with a 5 % and 18 % predictive increase for As (mg/kg) and Zn (mg/kg), respectively. The study's findings validated the potential for estimating complex HMs through intelligent data-driven models and heuristic optimization. The study also generated valuable insights that can inform the decision-makers and stockholders for environmental management strategies.

Evaluation of different QuEChERS-based methods for the extraction of 48 wastewater-derived organic contaminants from soil and lettuce root using high-resolution LC-QTOF with MRMHR and SWATH acquisition modes

The reuse of treated wastewater in agriculture is an important route of introducing a large number of organic contaminants into the agroecosystem. In this study, a modified QuEChERS-based approach was developed for rapid, simple, and simultaneous extraction of 48 organic wastewater-derived contaminants from soil and lettuce root. Twenty-two different (modification) scenarios of the known (or original) QuEChERS method have been tested, in order to obtain best and well-compromised recoveries for all target compounds for soil and roots. Finally, a common method was chosen for both matrices consisting of a single extraction step using EDTA-Mcllvaine buffer and the unbuffered Original QuEChERS salts. Method performance was accomplished by liquid chromatography coupled with high-resolution mass spectrometry on a QToF-MS system using two different acquisition modes, the ultra-fast high-resolution multiple reaction monitoring (MRMHR) mode and the innovative Sequential Window Acquisition of All Theoretical Fragment-Ion (SWATH) mode. Performance characterization was evaluated in terms of recovery, linearity, intra-day precision, method detection limits (MDLs), method quantification limits (MQLs), and matrix effect (ME). Recoveries in MRMHR mode ranged from 63 to 111% and 54 to 104% for lettuce root and soil, respectively, for most of compounds in MRMHR mode and from 56 to 121% and 54 to 104% for lettuce root and soil, respectively, for most of compounds in SWATH. Whereas, MQLs ranged from 0.03 to 0.92 ng g-1 in MRMHR and from 0.03 to 82 ng g-1 in SWATH for lettuce root, and from 0.02 to 0.44 ng g-1 in MRMHR and 0.02 to 0.14 ng g-1 in SWATH for soil. The method was then applied to follow the target compounds in soil and lettuce root, where the system lettuce-soil was irrigated with treated wastewater under real greenhouse conditions. Five and 17 compounds were detected in lettuce root and soil, respectively.

Biodegradable chelating agents for enhancing phytoremediation: Mechanisms, market feasibility, and future studies

Heavy metals in soil significantly threaten human health, and their remediation is essential. Among the various techniques used, phytoremediation is one of the safest, most innovative, and effective. In recent years, the use of biodegradable chelators to assist plants in improving their remediation efficiency has gained popularity. These biodegradable chelators aid in the transformation of metal ions or metalloids, thereby facilitating their mobilization and uptake by plants. Developed countries are increasingly adopting biodegradable chelators for phytoremediation, with a growing emphasis on green manufacturing and technological innovation in the chelating agent market. Therefore, it is crucial to gain a comprehensive understanding of the mechanisms and market prospects of biodegradable chelators for phytoremediation. This review focuses on elucidating the uptake, translocation, and detoxification mechanisms of chelators in plants. In this study, we focused on the effects of biodegradable chelators on the growth and environmental development of plants treated with phytoremediation agents. Finally, the potential risks associated with biodegradable chelator-assisted phytoremediation are presented in terms of their availability and application prospects in the market. This study provides a valuable reference for future research in this field.

Unveiling the presence of endocrine disrupting chemicals in northern French soils: Land cover variability and implications

Endocrine disrupting chemicals (EDCs) are chemicals that can be found in the environment and have adverse effects on human health by mimicking, perturbing and blocking the function of hormones. They are commonly studied in water surfaces, rarely in soils, although it can be an important source of their presence in the environment. Their detection in soils is analytically challenging to quantify, hence the lack of known background concentrations found in the literature. This scientific research aimed to detect EDCs in soils by analyzing 240 soil samples using an optimized protocol of double extraction and analysis using liquid chromatography coupled to mass spectrometry. The optimized protocol allowed for very sensitive detection of the targeted compounds. The results showed a high concentration of 29.391 ng/g of 17β-estradiol in soils and 47.16 ng/g for 17α-ethinylestradiol. Testosterone and Progesterone were detected at a highest of 1.02 and 6.58 ng/g, respectively. The ∑EDCs which included estrogens, progesterone, testosterone and Bisphenol A was found at an average of 22.72 ± 35.46 ng/g in the study area. The results of this campaign showed a heterogeneous geographic distribution of the EDCs compounds in the different zones of study. Additionally, the study conducted a comparison of the concentration of EDCs in different land covers including urban areas, agricultural lands, grasslands and forests. We observed a significant difference between forests and other land covers (p < 0.0001) for 17α-ethinylestradiol, estriol, and progesterone. This presence of EDCs in forest lands is not yet understood and requires further studies concerning its origins, its fate and its effect on human health. This study is the first large-scale sampling campaign targeting EDCs in soils in Europe and the second in the world. It is also the first to assess the concentrations of these compounds based on different land covers.

Cadmium in topsoils of the European Union - An analysis based on LUCAS topsoil database

Cadmium (Cd) is a naturally occurring element that can accumulate in the soil through the application of fertilisers containing cadmium and as a waste of industrial processes. Cadmium inputs in the soil have increased significantly (+50 %) during the 20th century as a result of the application of fertilisers and sewage sludge, and also due to local contamination (e.g. waste dumping, mining) and industrial emissions (e.g. zinc smelters). Using the 21,682 soil samples from the LUCAS soil survey, we aim to estimate the spatial distribution of the concentration of Cd in the European Union (EU) and UK topsoil. Out of the total, 72.6 % of the samples have Cd values <0.07 mg kg-1, 21.6 % in the range 0.07-1 mg kg-1 and the remaining 5.5 % higher than the threshold of 1 mg kg-1, which is generally considered the limit for risk assessment. The mean Cd value in the EU topsoils is 0.20 mg kg-1, slightly higher in grasslands (0.24 mg kg-1) compared to croplands (0.17 mg kg-1). Applying an ensemble of machine learning models supported by a variety of environmental descriptors, we created maps of Cd distribution at a resolution of 100 m. The ensemble approach included five models and increased the prediction accuracy to R2 of 0.45 (an increase of 0.1 compared to best single model performance). The approach used resulted in a high predictive power for the general Cd distribution, while also identifying hotspots of Cd contamination. Natural factors influencing Cd levels include soil properties (pH, clay), topography, soil erosion, and leaching. As anthropogenic factors, we identified phosphorus inputs to agricultural lands as the most important for Cd levels. The application of the EU Fertiliser Directive should further limit Cd inputs and potentially the Cd content in soils.

Interactive impacts of microplastics and arsenic on agricultural soil and plant traits

The ability of microplastics (MPs) to interact with environmental pollutants is currently of great concern due to the increasing use of plastic. Agricultural soils are sinks for multipollutants and the safety of biodegradable MPs in field conditions is questioned. However, still few studies have investigated the interactive effects between MPs and metals on the soil-plant system with agricultural soil and testing crops for human consumption. In this work, we tested the effect on soil and plant parameters of two common MPs, non-degradable plastic low-density polyethylene and biodegradable polymer polylactic acid at two different sizes (<250 μm and 250-300 μm) in association with arsenic (As). Lettuce (Lactuca sativa L.) was used as a model plant in a small-scale experiment lasting 60 days. Microplastics and As explained 12 % and 47 % of total variance, respectively, while their interaction explained 21 %, suggesting a higher toxic impact of As than MPs. Plant growth was promoted by MPs alone, especially when biodegradable MPs were added (+22 %). However, MPs did not affect nutrient concentrations in roots and leaves. The effect of MPs on enzyme activities was variable depending on the time of exposure (with larger effects immediately after exposure), the type and size of the MPs. On the contrary, the co-application of MP and As, although it did not change the amount of bioavailable As in soil in the short and medium term, it resulted in a significant decrease in lettuce biomass (-19 %) and root nutrient concentrations, especially when polylactic acid was applied. Generally, MPs in association with As determined the plant-soil toxicity. This work provides insights into the risk of copollution of MPs and As in agricultural soil and its phytotoxic effect for agricultural crops. However, the mechanisms of the joint effect of MP and As on plant toxicity need further investigation, especially under field conditions and in long-term experiments.

Honey Bees and Associated Matrices as Biomonitors of Soil Trace Elements: Assessment of their Sensitivity in a Regional Rural Environment

Honey bees (Apis mellifera L.) represent a random biosampler integrating pollutants over space and time. An effective biomonitor for trace element (TE) pollution should provide a linear response to TE levels in the environment. However, uncertainties in detecting TEs originating in soil limit their use. To address this, nine experimental sites with multiple apiaries were established in the Upper Palatine Forest, Czech Republic. The soils surrounding the hives were characterized by estimations of the pseudototal and (bio)available pools of TEs. Our study aimed to (1) quantify the linear relationships between soil TE indices and TE contents in bees, bee bread, honey, and wax, and (2) verify the biobarrier function protecting honey from TE contamination. Lead (0.046-0.140 µg g-1 ) and nickel (0.12-4.30 µg g-1 ) contents in bees showed strong linear correlations with (bio)available Pb (0.012-0.254 µg g-1 ) and pseudototal Ni (17.1-36.4 µg g-1 ) in soil (Pearson's r = 0.95 and 0.88, p < 0.005), providing high spatial resolution. A weaker, insignificant correlation was observed for chromium (Cr; r = 0.65) and vanadium (V; 0.44), while no correlation was found for cadmium (Cd). However, the lack of associations for Cr, V, and Cd may result from the low soil TE levels in the region, negligible differences among the majority of sites, and temporal concerns related to different time scales of the biomonitors, impacting the linear model's sensitivity. Biochemical traits in bees, such as the biobarrier function, and different bioavailability of TEs from ingested matter may affect the matrix-to-matrix transfer of TEs in an element-dependent manner. Consequently, the linear response of bee-related biomonitors to TE levels in the environment may significantly deteriorate. Environ Toxicol Chem 2024;43:288-298. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Comprehensive study on the spatial distribution of heavy metals and their environmental risks in high-sulfur coal gangue dumps in China

The accumulation of coal gangue (CG) from coal mining is an important source of heavy metals (HMs) in soil. Its spatial distribution and environment risk assessment are extremely important for the management and remediation of HMs. Eighty soil samples were collected from the high-sulfur CG site in northern China and analyzed for six HMs. The results showed that the soil was heavily contaminated by Mn, Cr and Ni based on the Nemerow index, and posed seriously ecological risk depended on the geo-accumulation index, potential ecological risk index and risk assessment code. The semi-variogram model and ordinary kriging interpolation accurately portrayed the spatial distribution of HMs. Fe, Mn, and Cr were distributed by band diffusion, Ni was distributed by core, the distribution of Cu had obvious patchiness and Zn was more uniform. The spatial autocorrelation indicated that all HMs had strong spatial heterogeneity. The BCR sequential extraction was employed to qualify the geochemical fractions of HMs. The data indicated that Fe and Cr were dominated by residual fraction; Cu, Ni and Zn were dominated by reducible and oxidizable fractions; Mn was dominated by reducible and acid-extractable (25.38%-44.67%) fractions. Pearson correlation analysis showed that pH was the main control factor affecting the non-residue fractions of HMs. Therefore, acid production from high sulfur CG reduced soil pH by 2-3, which indirectly promoted the activity of HMs. Finally, the conceptual model of HMs contamination at the CG site was proposed, which can be useful for the development of ecological remediation strategies.

Accumulation of copper and lead in ruminants grazing on a contaminated shooting range in Nordland County, Norway

Shooting ranges contain copper (Cu) and lead (Pb) contamination, which can be a risk for grazing ruminants. This study examines the accumulation of lead and copper in blood of lambs and calves, as well as in the liver of lambs. It compares these results with those of a previous study, which calculated the ingested dose of copper and lead based on soil ingestion and concentration in soil and plants. Blood samples were collected both before and after the grazing period that lasted from late May to mid-September. Liver samples were obtained during the slaughter of the lambs in the fall. Out of 61 liver samples, only one (3.7 mg Pb/kg dw) exceeding the presumed normal level in lamb liver of 3 mg/kg (dw). Copper concentrations exceeding the normal (300 mg/kg dw) concentration was found in 14 of the liver samples (341-1877 mg Cu/kg dw). Among these, two liver samples (1069 and 1877 mg Cu/kg dw) exceeded the level at which sheep are poisoned (1000 mg/kg dw). There was no statistically significant difference in the copper and lead concentration in liver of lambs that did and did not have the shooting range as part of their pasture. The average concentration of copper (lamb: 1.1 ± 0.37 µg Cu/g, calves: 0.6 ± 0.16 µg Cu/g) and lead (lamb: 0.010 ± 0.008 µg Pb/g calves: 0.01 ± 0.014 µg Pb/g) in the blood samples collected from the lambs and calves did not exceed the upper limit of what is considered normal (sheep: 1.35 mg Cu/kg and 0.3 mg Pb/kg, cattle: 1.7 mg Cu/kg and 0.35 mg Pb/kg). Copper concentration in the blood was notably higher in samples collected from the sheep before (1.3 ± 0.35 µg Cu/g) compared to after (0.8 ± 0.22 µg Cu/g) the grazing period. No statistically significant difference was found in lead and copper concentrations in the blood of lambs and calves grazing inside (lamb: 0.7 ± 0.21 µg Cu/g and 0.01 ± 0.008 µg Pb/g, calves: 0.6 ± 0.16 µg Cu/g and 0.02 ± 0.020 µg Pb/g) and outside (lamb: 0.9 ± 0.21 µg Cu/g and 0.13 ± 0.008 µg Pb/g, calves: 0.6 ± 0.17 µg Cu/g and 0.009 µg Pb/g) the shooting range. Grazing on areas contaminated by shooting activity did not appear to have any major implications for the accumulation of copper and lead in blood of cattle and sheep, as well as in the liver of sheep. The findings from this study indicate that employing site specific risk assessments for ruminants incorporating soil ingestion represents a viable approach.

Technological and economic analysis of electrokinetic remediation of contaminated soil: A global perspective and its application in Indian scenario

Globally million hectares of land annually is getting contaminated by heavy metalloids like As, Cd, Cr, Hg, Pb, Co, Cu, Ni, Zn, and Se, with current concentrations in soil above geo-baseline or regulatory standards. The heavy metals are highly toxic, mobile, and persistent and hence require immediate and effective mitigation. There are many available remediation techniques like surface capping, encapsulation, landfilling, soil flushing, soil washing, electrokinetic extraction, stabilization, solidification, vitrification, phytoremediation, and bioremediation which have been evolved to clean up heavy metal-contaminated sites. Nevertheless, all of the technologies have some applicability and limitations making the soil remediation initiative unsustainable. Among the available technologies, electrokinetic remediation (EKR) has been comparatively recognized to mitigate contaminated sites via both in-situ and ex-situ approaches due to its efficiency, suitability for use in low permeability soil, and requirement of low potential gradient. The work critically analyzes the EKR concerning techno, economic, and sustainability aspect for evaluating its application on various substrates and environmental conditions. The current soil contamination status in India is presented and the application of EKR for the heavy metal remediation from soil has been evaluated. The present work summaries a comprehensive and exhaustive review on EKR technology proving its effectiveness for a country like India where the huge amount of waste generated could not be treated due to lack of infrastructure, technology, and economic constraints.

Impacts of long-term irrigation with coalmine effluent contaminated water on trace metal contamination of topsoil and potato tubers in Dinajpur area, Bangladesh

Rapid depletion of groundwater and climate change mediated shifting precipitation pattern is forcing farmers to look for alternative irrigation options like wastewater. However, routine irrigation with trace metal contaminated wastewaters could potentially pollute soil as well as cause health risks through the consumption of food products grown in contaminated soil. Thus, the present study aimed to investigate the trace metals build-up status in topsoil and potato (Solanum tuberosum L.) tubers upon continuous irrigation with coalmine effluent contaminated wastewater compared to irrigation with groundwater and surface water over three consecutive years. Soil pollution status and human health risk associated with consumption of potato tubers grown on wastewater-irrigated soil was also assessed in this study. Three separate experimental sites differing in irrigation source (groundwater, surface water, and coalmine wastewater) were selected near Barapukuria Coal Mining Company Limited located at Parbatipur upazilla of Dinajpur district, Bangladesh. Nine trace metals namely arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn) were estimated. Results showed significantly higher trace metal content in both soil and potato tubers due to wastewater irrigation. Wastewater suitability for irrigation regarding Cd, Cr, Cu, Fe, Ni and Pb were off the permissible level although the soil contamination with trace metals and their levels in potato tubers remained within the safety limit. Health risk assessment revealed that, consumption of potato tubers grown in wastewater-irrigated soil remained safe although health risk associated with Cr was almost at the border. The study exclusively highlighted the core massage that, trace metal contamination of both soil and potatoes cultivated in them was increasing alarmingly due to three years of wastewater-irrigation. Although the extent of contamination was below critical limit, it can potentially become hazardous in years to come unless wastewater-irrigation is checked. This study was successful to provide valuable insights regarding the potential environmental and human health threats that might arise due to unmindful irrigation of contaminated coalmine wastewater. Besides, this study should prove useful in strategizing safety measures for cropping under trace metal contaminated soils and for planning industrial effluent disposal to avoid agricultural soil contamination.

Heavy metals contamination and ecological risks in agricultural soils of Uşak, western Türkiye: a geostatistical and multivariate analysis

This research aimed to determine and evaluate the concentrations of As, Cu, Hg, Ni, and Pb, and the physicochemical properties of 48 agricultural soil samples, to identify potential ecological risks and their sources associated with heavy metals contamination in Usak, western Türkiye. Various methods were used to assess ecological risks, including geoaccumulation index (Igeo), enrichment factor (EF), degree of contamination (Cdeg), potential ecological risk (RI), and pollution load index (PLI). The heavy metals concentrations ranged from 4 to 61 mg/kg for As, 8-48 mg/kg for Cu, 0.01-0.06 mg/kg for Hg, 30-813 mg/kg for Ni, and 4-30 mg/kg for Pb. The mean As and Ni concentrations were much greater than Earth's crustal average, the world's mean values, and mean values from many other emerging countries. Igeo and EF values for As, Ni, and Pb indicate various degrees of contamination. Cdeg values show that 96% of the study area is affected to some degree by contamination. For RI values, 38% indicate ecological risks ranging from moderate to considerable degrees. PLI values show that 75% of the agricultural soils are moderately polluted. Spatial distribution maps of Cdeg, RI, and PLI show that the northeastern and southwestern parts of the study area have been polluted to different levels by As, Ni, and Pb. Industrial activities and excessive use of fertilizers, pesticides, fungicides, and herbicides were identified as major sources of heavy metals contamination in the agricultural soils of Uşak.

Liquid crystal monomers in soils near the e-waste recycling site and liquid crystal display manufacturer: Exponential decrease with distance

Liquid crystal monomers (LCMs) have been recognized as contaminants of emerging concerns. E-waste recycling sites and liquid crystal displays (LCDs) manufacturers are supposed to be critical sources. However, information regarding LCM contaminations in soils surrounding these sites are currently unavailable. In this study, soil samples were collected from two distinct areas in South China: e-waste recycling area (n = 36) and LCD manufacturer (n = 41), and 60 target LCMs (including 13 biphenyl and analogs (BAs), 10 cyanobiphenyl and analogs (CBAs), and 37 fluorinated biphenyl and analogs (FBAs)) were determined. The concentrations of LCMs in the soils from near the e-waste recycling area (0.32-18 ng/g, average: 4.2 ng/g) were higher than those surrounding the LCD manufacturer (ND - 7.2 ng/g, average: 1.5 ng/g). The compositional profiles of LCMs in soil samples from these two typical point sources were considerably different. The concentrations of FBAs exponentially decreased with distance from the e-waste recycling park, by >90 % within 2 km. The levels of BAs exhibited a similar exponential decrease with distance from the LCD manufacturer. The inventories of LCMs were estimated to be 21.0 kg in the e-waste recycling area and 10.8 kg in the LCD manufacturer area. Remarkably, the inventory of LCMs in soils from e-waste recycling area was one order of magnitude larger than that of hexabromocyclododecanes (HBCDs) in the same region, and 0.2 to 20 times the annual global emissions of LCMs from discarded LCD panels. More studies are required to elucidate the environmental occurrence, behavior, and fate of LCMs in multimedia environment surrounding typical point sources.

Deciphering survival strategies: Oxidative stress and microbial interplay in Eisenia fetida under tetracycline contamination

Soil contamination resulting from residual antibiotics presents a pressing need to understand the survival mechanisms of soil organisms in polluted environments. This study focused on Eisenia fetida, and tetracycline stress experiments were conducted in a controlled environment using sterile artificial soil. The stress concentration ranged from 0 to 600 mg/kg, and stress cycles lasted either 10 or 30 days. The objective of this study was to assess the effects of oxidative stress and the changes in microbial communities both within and outside the earthworms. A comprehensive mathematical model was developed to elucidate the responses of organisms following exposure to stress utilizing factor analysis, grey relational analysis, and hierarchical entropy weight analysis. Under tetracycline stress, the initial stage (1-3 days) exhibited a coordinated regulation of oxidative stress and microbial communities in the soil with the assistance of CAT and GPX enzymes. The subsequent stage (4-5 days) further emphasized the influence of soil microbial communities. A notable "feedback regulation" of soil microbial communities on oxidative stress was observed during the third stage (6-8 days). Earthworms maintained a metabolic balance in the fourth stage (9-10 days). In the long term, the stress-induced a self-detoxification mechanism within soil microbial communities, which collaborated with GPX to respond to oxidative stress.

Research progress on remediation of organochlorine pesticide contamination in soil

Deteriorated soil pollution has grown into a worldwide environmental concern over the years. Organochlorine pesticide (OCP) residues, featured with ubiquity, persistence and refractoriness, are one of the main pollution sources, causing soil degradation, fertility decline and nutritional imbalance, and severely impacting soil ecology. Furthermore, residual OCPs in soil may enter the human body along with food chain accumulation and pose a serious health threat. To date, many remediation technologies including physicochemical and biological ways for organochlorine pollution have been developed at home and abroad, but none of them is a panacea suitable for all occasions. Rational selection and scientific decision-making are grounded in in-depth knowledge of various restoration techniques. However, soil pollution treatment often encounters the interference of multiple factors (climate, soil properties, cost, restoration efficiency, etc.) in complex environments, and there is still a lack of systematic summary and comparative analysis of different soil OCP removal methods. Thus, to better guide the remediation of contaminated soil, this review summarized the most commonly used strategies for OCP removal, evaluated their merits and limitations and discussed the application scenarios of different methods. It will facilitate the development of efficient, inexpensive and environmentally friendly soil remediation strategies for sustainable agricultural and ecological development.

Evidence for the accumulation of toxic metal(loid)s in agricultural soils impacted from long-term application of phosphate fertilizer

Phosphate fertilizers may contain elevated concentrations of toxic metals and metalloids and therefore, their excessive application can result in the accumulation of both phosphorus (P) and metal(loid)s in agricultural soils. This study aims to investigate the occurrence, distribution, and potential plant-availability of metal(loid)s originating from phosphate fertilizer in a long-term experimental field at the Tidewater Research Station in North Carolina, where topsoil (10-20 cm deep) and subsoil (up to 150 cm deep) samples were collected from five plots with consistent and individually different application rates of P-fertilizer since 1966. We conducted systematic analyses of P and metal(loid)s in bulk soils, in the plant available fraction, and in four sequentially extracted soil fractions (exchangeable, reducible, oxidizable, and residual). The results show that P content in topsoils were directly associated with the rate of P-fertilizer application (ρ = 1, p < 0.05). Furthermore, P concentrations were highly correlated with concentrations of Cd, U, Cr, V, and As in the bulk topsoil (ρ > 0.58, p < 0.05), as well as the potential plant-available fraction (ρ > 0.67, p < 0.01), indicating the accumulation of the fertilizer-derived toxic metal(loid)s in the topsoil. Significant correlations (p < 0.001) of metal(loid)s concentrations between the bulk soil and the potential plant-available fraction raises the possibility that P-fertilizer application could increase the accumulation of toxic metal(loid)s in plants, which could increase human exposure. Results from sequential leaching experiments revealed that large portions of the trace elements, in particular Cd, occur in the soluble (exchangeable and reducing) fractions of topsoil with higher P-fertilizer input, whereas the levels of redox-sensitive elements (As, V, U, Cr) were higher in the reducible and oxidizable fractions of the soils. Overall, the data presented in this study demonstrate the effect of long-term P-fertilizer application on the occurrence and accumulation of a wide range of toxic metal(loid)s in agricultural topsoil.

Assessing potential soil pollution from plant waste disposal: A modeling analysis of pesticide contamination

Pesticide residues can be taken up by plants after pesticide application, potentially resulting in soil pollution following the disposal of plant wastes at harvest. Currently, there is a lack of simple and efficient methods that can conduct high-throughput simulations to explore this problem across various chemicals and plant species. We present a modeling approach to simulating pesticide residue concentrations in soil as a result of plant waste disposal to assess the impact of plant wastes on agricultural soil pollution with respect to pesticide residues. This modeling approach employs well-established plant uptake models, providing versatility in evaluating different chemicals and plant species. The simulation process was tabulated in the spreadsheet interface, providing users with the flexibility to adjust input values for specific chemicals, plant species, and regions. The simulation results revealed that pesticides with relatively low lipophilicity (i.e., log KOW < 2) had low simulated residue concentrations in the soil as a result of plant waste disposal at harvest, whereas soil concentrations for lipophilic pesticides dramatically rose. This indicated that disposal of plant waste in agricultural soils will not pose significant ecological concerns to pesticides with low lipophilicity. The variability analysis showed that for certain pesticides, environmental factors (such as temperature and humidity) had a significant impact on the simulated residue concentrations in the soil as a result of plant waste disposal, which aided in the assessment of regional ecological risk as well as plant disposal management. Although some modeling aspects such as plant decomposition process, advanced plant uptake models, heterological distribution of residue concentrations in the soil, and plant waste stacking patterns require further research, the proposed approach can be used to assist in managing soil pesticides from plant waste disposal in preliminary stages.

Toxicity assessment of perfluorooctanesulfonic acid (PFOS) on a spontaneous plant, velvetleaf (Abutilon theophrasti), via metabolomics

Spontaneous plants often play important ecological roles in terrestrial environments, but impacts of contaminants on spontaneous plants are seldom investigated. Per- and polyfluoroalkyl substances (PFAS), such as perfluorooctanesulfonic acid (PFOS) are ubiquitous in rural and urban soils. In this study, we assessed the effects of PFOS on a spontaneous plant, velvetleaf (Abutilon theophrasti), using endpoints such as plant growth, stress defense, PFOS uptake, and elemental and metabolite profile. We observed stunted growth in plants grown in PFOS-contaminated soils, with PFOS accumulating in their shoots by up to 3000 times more than the control plants. The other endpoints (decreased chlorophyll a synthesis, elevated oxidative stress, reduced shoot Mg concentration, and reduced biomass production) also explained the stunted growth of velvetleaf exposed to elevated PFOS concentrations. We found that 56 metabolites involved in 13 metabolic pathways were dysregulated. The synthesis of important antioxidants such as ascorbic acid, hydroxycinnamic acids (coumaric, caffeic, ferulic, and sinapic acids), and tocopherols decreased, resulting in loss of plant's defense to stress. PFOS also reduced the levels of growth-related and stress-coping metabolites including squalene, serotonin, noradrenalin, putrescine, and indole-3-propionic acid, which further corroborated the restricted growth of velvetleaf exposed to elevated PFOS. These findings provide insights on phytotoxicity of PFOS to velvetleaf, a resilient terrestrial spontaneous plant.

Mitigating cadmium accumulation in dicotyledonous vegetables by iron fertilizer through inhibiting Fe transporter IRT1-mediated Cd uptake

The solubility of cadmium (Cd) in soil and its transfer to plants are influenced by soil pH. While increasing soil pH reduces Cd solubility and accumulation in rice plants grown in acidic soils, its effect on Cd accumulation in vegetables remains inconclusive. Here, we investigated the impact of soil pH on Cd accumulation in dicotyledonous vegetables and elucidated the underlying molecular mechanisms. Soils collected from various locations were supplemented with varying quantities of lime to achieve soil pH values of around 5.0, 6.0, 7.0, and 8.0. Raising soil pH from around 5.0 to 8.0 markedly decreased extractable Cd. However, increasing soil pH tended to promote shoot Cd accumulation in dicotyledonous vegetable species including lettuce, pakchoi, and Chinese cabbage, and the model dicotyledonous plant Arabidopsis thaliana. Conversely, soil pH increase resulted in a monotonic decrease in rice Cd accumulation. In our hydroponic experiments, we discovered that iron (Fe) deficiency substantially increased Cd uptake and accumulation in dicotyledonous plants but not in rice. Increasing soil pH reduced soil Fe availability and induced the Fe transporter gene IRT1 expression in dicotyledonous vegetables roots, which led to an increase in IRT1-mediated Cd uptake and subsequently increased Cd accumulation as soil pH increases. A comprehensive model incorporating extractable Cd and root IRT1 expression better explained Cd accumulation in vegetable shoots. The application of 50 mg/kg of Fe fertilizer in neutral or alkaline soils resulted in a significant reduction in Cd accumulation by 34-58% in dicotyledonous vegetables. These findings reveal that increasing soil pH has two opposite effects, decreasing soil Cd availability while promoting Cd uptake through IRT1 upregulation, reconciling the inconsistency in its effect on Cd accumulation in dicotyledonous plants. Our findings provide important insights for understanding the factors affecting Cd uptake in plants and offer a practical solution to mitigate Cd contamination in vegetables.

Environmental effects from petroleum product transportation spillage in Nigeria: a critical review

Nigeria has struggled to meet sustainable development goals (SDGs) on environmental sustainability, transportation, and petroleum product distribution for decades, endangering human and ecological health. Petroleum product spills contaminate soil, water, and air, harming humans, aquatic life, and biodiversity. The oil and gas industry contributes to environmental sustainability and scientific and technological advancement through its supply chain activities in the transport and logistics sectors. This paper reviewed the effects of petroleum product transportation at three accident hotspots on Nigeria highway, where traffic and accident records are alarming due to the road axis connecting the southern and northern regions of the country. The preliminary data was statistically analysed to optimise the review process and reduce risk factors through ongoing data monitoring. Studies on Nigeria's petroleum product transportation spills and environmental impacts between the years 2013 and 2023 were critically analysed to generate updated information. The searches include Scopus, PubMed, and Google Scholar. Five hundred and forty peer-reviewed studies were analysed, and recommendations were established through the conclusions. The findings show that petroleum product transport causes heavy metal deposition in the environment as heavy metals damage aquatic life and build up in the food chain, posing a health risk to humans. The study revealed that petroleum product spills have far-reaching environmental repercussions and, therefore, recommended that petroleum product spills must be mitigated immediately. Furthermore, the study revealed that better spill response and stricter legislation are needed to reduce spills, while remediation is necessary to lessen the effects of spills on environmental and human health.

Assessment of potentially hazardous elements in soils of the Boyacá industrial corridor (Colombia) using GIS, multivariate statistical analysis, and geochemical indexes

In the industrial corridor of Boyacá, Colombia, population growth is accompanied by anthropogenic activities such as industrial operations, vehicle exhaust fumes, mining, smelting, atmospheric deposition, and excessive use of chemical products to promote crop growth. These activities are known to have a significant impact on urban and rural soils, contributing significantly to elevated concentrations of potentially hazardous elements in the environment. This industrial corridor is an area of economic and social development that needs to provide reference information that will allow us to know the state of soil quality to preserve and manage the public and geoenvironmental health of this region. Anthropogenic activities have contributed to the accumulation of potentially hazardous elements in the environment, affecting various levels of life and creating risks with economic and social implications. However, igneous activity or detrital deposition also enriches soils and creates geochemical anomalies in specific locations. In these cases, the identification of potentially hazardous elements involves the determination of likely sources of contamination and their relationship to the geological setting. In this study, the concentrations of As, Cd, Pb, Mn, Fe, Zn, Hg, Cu and Ni were determined in eighty-one soil samples from the Boyacá industrial corridor (Colombia). The sequential trend of the concentrations of potentially hazardous elements was as follows: Fe > Mn > Zn > Ni > Cu> Pb > As > Cd > Hg. Furthermore, the application of spatial analysis criteria in GIS software with multivariate statistical tools and geochemical indices allowed the identification of anthropogenic and geogenic sources. Most of the potentially hazardous elements were found in soils exposed to industrial and agricultural activities, except for iron. This element showed low variability in all samples, regardless of the geological formations. Due to the lack of reference values for potentially hazardous elements in Colombia, the concentrations were compared with the environmental standards of the Environmental Protection Agency (EPA) and the Ecuadorian Ministry of Environment, Water and Ecological Transition (MAE). The results demonstrate the complexity of the soil and represent the first exploratory study of potentially hazardous elements in this industrial corridor. These results are the starting point for the establishment of geochemical background lines in Colombia and for inspection policies for areas where productive activities converge.

Further Limitations of Synthetic Fungicide Use and Expansion of Organic Agriculture in Europe Will Increase the Environmental and Health Risks of Chemical Crop Protection Caused by Copper-Containing Fungicides

Copper-containing fungicides have been used in agriculture since 1885. The divalent copper ion is a nonbiodegradable multisite inhibitor that has a strictly protective, nonsystemic effect on plants. Copper-containing plant protection products currently approved in Germany contain copper oxychloride, copper hydroxide, and tribasic copper sulfate. Copper is primarily used to control oomycete pathogens in grapevine, hop, potato, and fungal diseases in fruit production. In the environment, copper is highly persistent and toxic to nontarget organisms. The latter applies for terrestric and aquatic organisms such as earthworms, insects, birds, fish, Daphnia, and algae. Hence, copper fungicides are currently classified in the European Union as candidates for substitution. Pertinently, copper also exhibits significant mammalian toxicity (median lethal dose oral = 300-2500 mg/kg body wt in rats). To date, organic production still profoundly relies on the use of copper fungicides. Attempts to reduce doses of copper applications and the search for copper substitutes have not been successful. Copper compounds compared with modern synthetic fungicides with similar areas of use display significantly higher risks for honey bees (3- to 20-fold), beneficial insects (6- to 2000-fold), birds (2- to 13-fold), and mammals (up to 17-fold). These data contradict current views that crop protection in organic farming is associated with lower environmental or health risks. Further limitations in the range and use of modern single-site fungicides may force conventional production to fill the gaps with copper fungicides to counteract fungicide resistance. In contrast to the European Union Green Deal goals, the intended expansion of organic farming in Europe would further enhance the use of copper fungicides and hence increase the overall risks of chemical crop protection in Europe. Environ Toxicol Chem 2024;43:19-30. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Integrated environmental assessment of iron ore tailings in floodplain soils and plants after the Fundão Dam disaster in Brazil

Previous studies of the Doce River basin (Brazil) seem to be contradictory regarding the contamination of soils with potentially harmful elements (PHE). This research aimed to perform an integrated assessment of PHE in the soil-plant-tailing system from the area most affected by the iron waste after the Fundão Dam disaster in 2015. Different fractions of PHE (exchangeable, nonexchangeable, reducible, and pseudo-total) were determined on deposited iron waste (DIW), soil waste mixture (SWM), and control soil (CS) samples. Total contents of PHE in Poaceae were also determined, and Allium cepa bioassays were performed to determine DIW and CS cytotoxicity and/or genotoxicity to plants. The Fe and Mn contaminations were the only ones related to the deposition of DIW on floodplains, and other harmful element content (such as As, Hg, Ni, Cd, Cr, and Pb) was not found above baseline values for soils. In addition, a significant part of the Fe and Mn in DIW is readily available or subject to acidification and prolonged flood reduction processes. The high available content of Fe favored its excessive accumulation by Brachiaria. The DIW chemical conditions reduced biological functions of A. cepa under a controlled environment. However, more drastic effects, such as genetic damage, were not seen. The postdisaster action of covering DIW with CS resulted in undesirable enrichment of Pb on the floodplain soils. The integrated results allow the conclusion that the iron waste is not a time bomb for PHE contamination of soils between the Fundão and Risoleta Neves Hydroelectric Dam (~100 km away from Fundão). Integr Environ Assess Manag 2024;20:117-132. © 2023 SETAC.

Assessment of heavy metal distribution and bioaccumulation in soil and plants near coal mining areas: implications for environmental pollution and health risks

Monitoring heavy metals (HMs) across source distance and depth distribution near coal mining sites is essential for preventing environmental pollution and health risks. This study investigated the distribution of selected HMs, cadmium (Cd2+), chromium (Cr2+), copper (Cu2+), manganese (Mn2+), nickel (Ni2+), lead (Pb2+), and zinc (Zn2+), in soil samples collected from ten sites (S-1-S-10) at two different depths (0-15 and 15-30 cm) and distances of 50, 100, and 200 m from a mining source. Additionally, three plant species, Prosopis spp., Justicia spp., and wheat, were collected to assess HM bioavailability and leaf accumulation. Coal mine activities' impact on soil properties and their HM associations were also explored. Results reveal HM concentrations except for Cr2+ exceeding World Health Organization (WHO) limits. In surface soil, Cd2+ (58%), Cu2+ (93%), Mn2+ (68%), Ni2+ (80%), Pb2+ (35%), and Zn2+ (88%) surpassed permissible limits. Subsurface soil also exhibited elevated Cd2+ (53%), Cu2+ (83%), Mn2+ (60%), Ni2+ (80%), Pb2+ (35%), and Zn2+ (77%). Plant species displayed varying HM levels, exceeding permissible limits, with average concentrations of 1.4, 1.34, 1.42, 4.1, 2.74, 2.0, and 1.98 mg kg-1 for Cd2+, Pb2+, Cr2+, Cu2+, Mn2+, Ni2+, and Zn2+, respectively. Bioaccumulation factors were highest in wheat, Prosopis spp., and Justicia spp. Source distance and depth distribution significantly influenced soil pH, electrical conductivity (EC), and soil organic carbon (SOC). Soil pH and EC increased with an increase in soil depth, while SOC decreased. Pearson correlation analysis revealed varying relationships between soil properties and HMs, showing a considerably negative correlation. Concentrations of HMs decreased with increasing depth and distance from mining activities, validated by regression analysis. Findings suggest crops from these soils may pose health risks for consumption.

Remediation of spent engine oil-contaminated soil through biostimulation and bioaugmentation with sodium dodecyl sulphate (SDS) and indigenous hydrocarbonoclastic bacterial isolates

Pollution caused by spent engine oil has become a major global ecological concern as it constitutes a big threat to plants, animals, microorganisms and the soil ecosystem. This study was undertaken to examine the remediation of spent engine oil-contaminated soil through biostimulation and bioaugmentation with sodium dodecyl sulphate and indigenous hydrocarbonoclastic bacterial isolates. Twelve mesocosms were organized into four groups designated G1, G2, G3 and G4 and each filled with 2.5 kg of soil samples. Each group was composed of three mesocosms to produce a triplicate setup. G1 contained pristine soil which served as a positive control. G2 contained a total petroleum hydrocarbon (TPH) of 913.333 mg/kg in the untreated oil-polluted soil which served as a negative control. G3 contained a TPH of 913.333 mg/kg in the polluted soil inoculated with indigenous hydrocarbonoclastic bacterial isolates. G4 contained a TPH of 913.333 mg/kg in the polluted soil mixed with bacterial consortium and sodium dodecyl sulphate. The level of pollution was 36.5% in the triplicate setup G2, G3 and G4. Fourier Transform Infrared spectroscopy was used to determine the degree of hydrocarbon degradation. The initial TPH value of 913.33 mg/kg was reduced by 84.44% (142 mg/kg) in soil inoculated with indigenous hydrocarbonoclastic bacterial isolates and by 88.28% (106.66 mg/kg) in biostimulated soil. Result of this study show that soil stimulation involving bacterial consortium and sodium dodecyl sulphate was more efficient than bioaugmentation strategy alone used in the remediation of spent engine oil-polluted soil.

Terrestrial Isopods Generate Microplastics from Low-Density Polyethylene Without Effects on Survival

With concern growing regarding the impact of microplastics (MPs) on terrestrial ecosystems, it is important to assess the role invertebrates may play in the fate of MPs within these ecosystems. Commonly, MPs enter these environments through improperly discarded waste or the application of treated biosolids and/or wastewater on agricultural soils. The present study investigated whether three species of terrestrial isopod (Porcellio scaber, Porcellio laevis, and Porcellionides pruinosus) ingest plastic debris and generate MPs during exposures varying from 24 h to 14 days and whether this may have an adverse effect on their health. Test vessels were designed to expose isopods to plastic fragments in the form of polyethylene plastic foam. Isopods were exposed to plastic that was either (1) pristine, or (2) weathered in a soil and water solution prior to incorporation in test vessels. When exposed to weathered polyethylene, all three species generated MPs (minimum-maximum size values for all durations inclusive: P. laevis = 114-1673 µm, P. scaber = 99-1635 µm, P. pruinosus = 85-1113 µm) through the consumption of macroplastic fragments with no observed impact on their health. In the shorter-duration exposures, the number of MPs generated by the isopod species in the present study was highly variable between experimental vessels (minimum-maximum generated MPs for 14-day exposure: P. laevis = 25-420, P. scaber = 50-583, P. pruinosus = 48-311). However, as the exposure durations increased, there was a clear trend of increasing MP generation, indicating that the isopods continued to consume the plastic fragments as long as the surface was weathered. A significant difference in the size of generated MPs was observed as well, with smaller isopod species generating smaller MP fragments on average. The results of the present study confirm that certain species of isopod can contribute to the generation of MPs, which constitutes an additional pathway of MP exposure to soil ecosystems. Environ Toxicol Chem 2024;00:1-9. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Characterizing the Microplastic Content of Biosolids in Southern Ontario, Canada

The application of biosolids to agricultural land has been identified as a major pathway of microplastic (MP) pollution to the environment. Very little research, however, has been done on the MP content of biosolids within Canada. Fifteen biosolid samples from different treatment processes (liquid, dewatered, pelletized, and alkali-stabilized) were collected from 11 sources across southern Ontario to quantify and characterize the MP load within them. All samples exhibited MP concentrations ranging from 188 200 (±24 161) to 512 000 (±28 571) MPs/kg dry weight and from 4122 (±231) to 453 746 (±38 194) MPs/kg wet weight. Field amendment of these biosolids can introduce up to 3.73 × 106 to 4.12 × 108 MP/ha of agricultural soil. There was no significant difference in the MP concentrations of liquid, dewatered, and pelletized samples; but a reduction in MP content was observed in alkali-stabilized biosolids. Fragments composed 57.6% of the MPs identified, while 36.7% were fibers. In addition, MPs showed an exponential increase in abundance with decreasing size. Characterization of MPs confirmed that polyester was the most abundant, while polyethylene, polypropylene, polyamide, polyacrylamide, and polyurethane were present across the majority of biosolid samples. The results of the present study provide an estimate of the potential extent of MP contamination to agricultural fields through the amendment of biosolids. Environ Toxicol Chem 2024;00:1-14. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Can antimony contamination in soil undermine the ecological contributions of earthworms?

As antimony (Sb) has been increasingly used in manufacturing industries (e.g., alloy, polymer and electronics industries), Sb contamination in the soil environment becomes widely reported and has drawn growing attention due to the toxicity of Sb to living organisms. Whether soil-dwelling organisms can tolerate Sb toxicity and maintain their ecological functions remains poorly understood. Using a cosmopolitan, ecologically important earthworm species (Eisenia fetida) as an ideal model organism, we examine the effects of Sb on the physiological, molecular and behavioural responses of earthworms to different levels of Sb contamination in soil (0, 10, 50, 100, 250 and 500 mg/kg). We found that earthworms could tolerate heavy Sb contamination (100 mg/kg) by boosting their antioxidant defence (POD and GST) and immune systems (ACP) so that their body weight and survival rate were sustained (c.f. control). However, these systems were compromised under extreme Sb contamination (500 mg/kg), leading to mortality. As such, earthworms exhibited avoidance behaviour to escape from the Sb-contaminated soil, implying the loss of their ecological contributions to the environment (e.g., increase in soil aeration and maintenance of soil structure). By measuring various types of biomarkers along a concentration gradient, this study provides a mechanistic understanding of how earthworms resist or succumb to Sb toxicity. Since extreme Sb contamination in soil (>100 mg/kg) is rarely found in nature, we are optimistic that the health and performance of earthworms are not influenced by Sb in most circumstances, but regular monitoring of Sb in soil is recommended to ensure the integrity and functioning of soil environment. Further studies are recommended to evaluate the long-term impact of Sb in the soil ecosystem through bioaccumulation and trophic transfer among soil-dwelling organisms.

Application of apatite particles for remediation of contaminated soil and groundwater: A review and perspectives

With rapid industrial development and population growth, the pollution of soil and groundwater has become a critical concern all over the world. Yet, remediation of contaminated soil and water remains a major challenge. In recent years, apatite has gained a surging interest in environmental remediation because of its high treatment efficiency, low cost, and environmental benignity. This review summarizes recent advances in: (1) natural apatite of phosphate ores and biological source; (2) synthesis of engineered apatite particles (including stabilized or surface-modified apatite nanoparticles); (3) treatment effectiveness of apatite towards various environmental pollutants in soil and groundwater, including heavy metals (e.g., Pb, Zn, Cu, Cd, and Ni), inorganic anions (e.g., As oxyanions and F-), radionuclides (e.g., thorium (Th), strontium (Sr), and uranium (U)), and organic pollutants (e.g., antibiotics, dyes, and pesticides); and (4) the removal and/or interaction mechanisms of apatite towards the different contaminants. Lastly, the knowledge or technology gaps are identified and future research needs are proposed.

Electrokinetic remediation for the removal of heavy metals in soil: Limitations, solutions and prospection

Electrokinetic remediation (EKR) technology is a promising method to remove heavy metals from low permeability soil, because it is environmentally friendly, efficient and economical, and can realize in-situ remediation. In this paper, the basic principles and related physical and chemical phenomena of EKR are systematically summarized, and three limiting problems of EKR technology are put forward: the weak ability of dissolving metals, focusing effect, and energy consumption. There are many methods to solve these technical problems, but there is a lack of systematic summary of the causes of problems and solutions. Based on various enhanced EKR technologies, this paper summarizes the main ideas to solve the limiting problems. The advantages and disadvantages of each technology are compared, which has guiding significance for the development of new technology in the future. This paper also discusses the dissolution of residual heavy metals, which is rare in other articles. The energy consumption of EKR and the remediation effect are equally important, and both can be used as indicators for evaluating the feasibility of new technologies. This paper reviews the influence of various electric field conditions on power consumption, such as renewable energy supply, new electrode materials and electrode configurations, suitable voltage values and functional electrolytes. In addition, a variety of energy consumption calculation methods are also introduced, which are suitable for ohmic heat loss, energy distribution when there is non-target ion competition, and power consumption of specific ions in various metal ions. Researchers can make selective reference according to their actual situations. This paper also systematically introduces the engineering design and cost calculation of EKR, lists the research progress of some engineering cases and pilot-scale tests, analyzes the reasons why it is difficult to apply EKR technology in large-scale engineering at present, and puts forward the future research direction.

Assessment of mercury bioavailability in garden soils around a former nonferrous metal mining area using DGT, accumulation in vegetables, and implications for health risk

Mercury (Hg) is a toxic, non-essential element for living organisms, frequently present in high concentrations in soils from industrial areas. The total, dissolved, and labile Hg concentrations in garden soils and their accumulation in edible vegetables (onion, garlic, lettuce, and parsley) grown on contaminated soils in localities situated a former mining area were evaluated. The labile Hg fraction was estimated by diffusive gradient in thin films (DGT). The soil-to-vegetable transfer factors, as well as the health risk by exposure to Hg, were calculated based on the labile Hg concentration in soil. The total Hg concentration in soil varied widely (0.11-3.77 mg kg-1), Hg in soil solution ranged between 2.14 and 20.2 μg L-1 and labile Hg between 1.13 and 18.6 μg L-1. About 36-96% (84% on average) of the Hg concentration in soil solution was found in labile form. Multivariate analysis revealed significant correlations between the labile Hg concentration in soil and Hg accumulated in vegetables. The hazard indices showed that, although the study area is affected by legacy pollution, exposure to soil and consumption of locally grown vegetables do not pose health risks.

Mycorrhizal fungal communities associated with three metal accumulator plants growing in an abandoned Pb smelting factory

Plants associated with mycorrhizal fungi has the ability to establish on metal-contaminated soils playing an important role in phytoremediation programs. The objective of this study was to examine the presence of arbuscular mycorrhizal fungi (AMF) (spores density, diversity, indicator species, and root colonization) and dark septate endophytic fungi (DSE fungal root colonization) in three metal accumulator plants (Sorghum halepense, Bidens pilosa, and Tagetes minuta) growing in soils with high Pb content. The Pb content in AMF spores and plant biomass were also assessed. Rhizosphere soil samples were taken from the three dominant plant species at six study sites surrounding the abandoned Pb smelter and one uncontaminated site. The three studied plants were colonized by AMF and DSE fungi. A total of 24 AMF morphospecies were present in the Pb-contaminated areas. The AMF indicator species in the control site (non-contaminated area) was Funneliformis mosseae and in the most contaminated site were Gigaspora decipiens and Denticustata biornata. There was an increase in mycorrhizal variables such as the number of AMF vesicles, spore number, Pb content in AMF spores and plant biomass and DSE colonization (in Sorghum) with increasing soil Pb contamination, but a decrease in AMF diversity and richness was found. For upcoming soil restoration projects, it is crucial to understand the mycorrhizal fungi as well as the plant community that has adapted to the highly contaminated environment.

Designing soil contamination monitoring network in petroleum refineries by XGBoost weighting and geostatistical facility allocation methods

Petroleum refineries are deemed strategic industrial sectors that can release toxic materials to the environment and cause potential hazards. In this regard, designing and installation of soil contamination monitoring networks at petroleum refineries is a necessity. In this research, we designed an optimal monitoring network with maximum coverage and minimum number of monitoring boreholes. The main regarded parameters are the groundwater contamination history, the location of effective structures, the location of flare stacks and the soil texture. In addition, the soil contamination was calculated based on previous contamination of the soil at the sampling points by the Entropy Weighting Model. It was employed with other parameters to estimate the soil contamination across the site. The Machine Learning method of XGBoost was implemented for estimating and assigning priority for every point of the site. To achieve the optimal network in the optimization program, four parameters were regarded including (a) the optimal value of the optimization program's objective function, (b) the number of Advance Zero-half cuts of the Cut Generation algorithm, (c) the consumed time, and (d) the optimal boreholes number of the network corresponding with different effective contamination detection radius. The network was designed by generalized Maximal Covering Location Problem and for optimizing it, the advantages of Mixed-Integer Linear Programming method were used. To evaluate the applicability of the method, it has been developed and implemented in a refinery in the south of Iran. 92.84% of XGBoost estimation accuracy, the optimal number of 113 and the effective contamination detection radius of 160 m were obtained for boreholes of the network. To investigate the efficiency of the model, a new Regret function has been defined. Furthermore, sensitivity analysis of the parameters and feature importance analysis of XGBoost both showed that the main parameter of the model was the location of effective structures.

Development of a highly tolerant bacterial consortium for asphaltene biodegradation in soils

Asphaltenes are the most polar and heavy fraction of petroleum, and their complex structure and toxicity make them resistant to biodegradation. The ability to tolerate high asphaltene concentrations is crucial to reducing the toxicity-related inhibition of microbial growth and improving their capacity for adaptation, survival, and biodegradation in soils highly contaminated with asphaltenes. This study developed a highly tolerant consortium for efficient asphaltene biodegradation in soils from 22 bacterial isolates obtained from heavy-crude oil-contaminated soils. Isolates corresponded to the Rhodococcus, Bacillus, Stutzerimonas, Cellulosimicrobium, Pseudomonas, and Paenibacillus genera, among others, and used pure asphaltenes and heavy crude oil as the only carbon sources. Surface plate assays were used to evaluate the tolerance of individual isolates to asphaltenes, and the results showed variations in the extension and inhibition rates with maximum tolerance levels at 60,000 mg asphaltenes l-1. Inhibition assays were used to select non-antagonistic bacterial isolates among those showing the highest tolerance levels to asphaltenes. A consortium made up of the five most tolerant and non-antagonistic bacterial isolates was able to degrade up to 83 wt.% out of 10,000 mg asphaltenes kg-1 in the soil after 52 days. Due to its biological compatibility, high asphaltene tolerance, and ability to utilise it as a source of energy, the degrading consortium developed in this work has shown a high potential for soil bioremediation and is a promising candidate for the treatment of aged soil areas contaminated with heavy and extra-heavy crude oil. This would be the first research to assess and consider extreme bacterial tolerance and microbial antagonism between individual degrading microbes, leading to the development of an improved consortium capable of efficiently degrading high amounts of asphaltenes in soil.