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Metal pollution in water, soil, and vegetation is an emerging environmental issue. Therefore, this study investigated the abundance of heavy metals (HMs) within roots and shoots of native plant species i.e., Bromus pectinatus, Cynodon dactylon, Poa annua, Euphorbia heliscopa, Anagallis arvensis, and Stellaria media grown in the adjoining area of municipal wastewater channels of a Pakistani city of Abbottabad. HMs concentrations (mg L -1 ) in municipal wastewater were: chromium (Cr) (0.55) > nickel (Ni) (0.09) > lead (Pb) (0.07) > cadmium (Cd) (0.03). Accumulation of HMs in both roots and shoots of plant species varied as B. pectinatus > C. dactylon > P. annua > E. heliscopa > A. arvensis > S. media. Irrespective of the plant species, roots exhibited higher concentrations of HMs than shoots. Higher amount of Cr (131.70 mg kg -1 ) was detected in the roots of B. pectinatus and the lowest amount (81 mg kg -1 ) in A. arvensis, Highest Cd concentration was found in the shoot of B. pectinatus and the lowest in the E. heliscopa. The highest concentration of Ni was found in the roots of S. media (37.40 mg kg -1 ) and the shoot of C. dactylon (15.70 mg kg -1 ) whereas the lowest Ni concentration was achieved in the roots of A. arvensis (12.10 mg kg -1 ) and the shoot of E. heliscopa (5.90 mg kg -1 ). The concentration of HMs in individual plant species was less than 1000 mg kg -1 . Considering the higher values (> 1) of biological concentration factor (BCF), biological accumulation co-efficient (BAC), and translocation factor (TF), B. pectinatus and S. media species showed greater potential for HMs accumulation than other species. Therefore, these plants might be helpful for the remediation of HM-contaminated soil., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

This study assessed the physicochemical properties of soils and their levels of heavy metal contents in soils along the Enyigba mining site in Ikwo, Ebonyi State, Nigeria. A total of 96 samples of soil were taken at depths of 0 to 20 cm using a soil auger and core sampler at a horizontal spacing of 100 m between each location and examined using standard laboratory techniques. The control soil samples were taken from the Alex Ekwueme Federal University Experimental and Research Farm in Ebonyi State, at a distance of 50 m from each spot at a depth of 0 to 20 cm. The results obtained from this study showed significant variations in the physicochemical properties and heavy metal levels of the soil from the Enyigba mining site, indicating that the mining activities have contaminated the soil. The result also indicated that mining operations may be responsible for the increase in sand and the decrease in silt and clay particles. The mining site's pH was typically low, indicating that the soil is naturally acidic. The contamination indices showed that lead recorded very high contamination factor of 27.068, while iron, nickel and zinc were low. The observed high concentration factor of lead had an impact on the soil's bulk density, saturated hydraulic conductivity, total porosity, calcium, potassium ion, magnesium ion, total nitrogen, organic carbon, cation exchange capacity, phosphorus and base saturation contents. It is recommended that the government's Ministry of Environment, at all levels, take a proactive stance in managing the excessive and subpar mining operations in the study area., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

The research aimed to determine the influence of endophytic fungi on tolerance, growth and phytoremediation ability of Prosopis juliflora in heavy metal-polluted landfill soil. A consortium of 13 fungal isolates as well as Prosopis juliflora Sw. DC was used to decontaminate heavy metal-polluted landfill soil. Enhanced plant growth (biomass and root and shoot lengths) and production of carotenoids, chlorophyll and amino acids L-phenylalanine and L-leucine that are known to enhance growth were found in the treated P. juliflora. Better accumulations of heavy metals were observed in fungi-treated P. juliflora over the untreated one. An upregulated activity of peroxidase, catalase and ascorbate peroxidase was recorded in fungi-treated P. juliflora. Additionally, other metabolites, such as glutathione, 3,5,7,2',5'-pentahydroxyflavone, 5,2'-dihydroxyflavone and 5,7,2',3'-tetrahydroxyflavone, and small peptides, which include Lys Gln Ile, Ser Arg Ala, Asp Arg Gly, Arg Ser Ser, His His Arg, Arg Thr Glu, Thr Arg Asp and Ser Pro Arg, were also detected. These provide defence supports to P. juliflora against toxic metals. Inoculating the plant with the fungi improved its growth, metal accumulation as well as tolerance against heavy metal toxicity. Such a combination can be used as an effective strategy for the bioremediation of metal-polluted soil., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

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., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Chromium (Cr), total arsenic (As), inorganic arsenic (iAs), cadmium (Cd), mercury (Hg), methylmercury (MeHg), and lead (Pb) were analyzed in in Agaricus blazei, Tricholoma matsutake, Pholiota nameko, agrocybe aegirit, Boletus edulis, Auricularia auricula, and Lentinus edodes collected from online supermarket in China from 2015 to 2017. The order of mean concentrations for the five heavy metals in edible mushrooms was As > Cd > Cr > Pb > Hg. No positive correlation was found between total As and iAs, nor between total Hg and MeHg. The contents of iAs were at a low level except for A. blazei samples. The contents of MeHg were at a low level in all test mushroom samples. And Cr, Cd, and Pb pollution were common problems in the test mushroom samples. The comprehensive factor pollution index was between 0.569 (A. auricula) and 3.056 (B. edulis). The THQ values for the five heavy metals from P. nameko, A. auricula, A. aegirit, and L. edodes samples were less than 1. The hazard index (HI) values of A. blazei, T. matsutake, and B. edulis samples for adults and children were greater than 1, indicating significant health hazard to the adults and children consumers. The cancer risk (CR) values for iAs ranged from 3.82 × 10 - 6 (T. matsutake) to 8.61 × 10 - 5 (A. blazei), indicating no potential carcinogenic risk to the consumers. The order for carcinogenic risk of each edible mushroom species was A. blazei > L. edodes > P. nameko > A. aegirit > A. auricula > B. edulis > T. matsutake., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Biochar (BC) and biodegradable mulch film (BMF) are both commonly used means of production in agriculture. In recent years, most studies have focused on the effects of BC or BMF on soil heavy metal pollution, while they have neglected the combined effects. In this study, a pot experiment was conducted to examine the impacts of BMF, BC, and combined BMF and BC (CMB) on the mobility of chromium (Cr) and the agronomic characteristics of flue-cured tobacco. Compared with the control, BMF, BC, and CMB significantly reduced the concentrations of diethylenetriamine pentaacetic acid (DTPA) extractable Cr in soils by 29.07-29.75%, 45.35-48.54%, and 34.21-37.92%, respectively. In comparison to the application of BMF and BC alone, co-application reduced the availability of Cr in soil via increasing the adsorption of soil Cr and soil enzyme activity, which resulted in the decrease of Cr content and bioconcentration factor and in plants. Moreover, the combined application increased the plant height, stem diameter, leaf area, total root area, root tip number, and root activity of tobacco, which leaded to increase in leaf and root biomass by 11.40-67.01% and 23.91-50.74%, respectively. Therefore, the application of CMB can reduce the heavy metal residues in tobacco leaves and improve tobacco yield and quality., (© 2024. The Author(s).)

The closure or relocation of many industrial enterprises has resulted in a significant number of abandoned polluted sites enriched in heavy metals to various degrees, causing a slew of environmental problems. Therefore, it is essential to conduct research on heavy metal contamination in the soil of industrial abandoned sites. In this study, soils at different depths were collected in a smelting site located in Hunan Province, China, to understand the Cr distribution, speciation and possible risks. The results revealed that the high-content Cr and Cr(VI) contamination centers were mainly concentrated near S1 (Sample site 1) and S5. The longitudinal migration law of chromium was relatively complex, not showing a simply uniform trend of decreasing gradually with depth but presenting a certain volatility. The vertical distribution characteristics of chromium and Cr(VI) pollution suggest the need for attention to the pollution from chromium slag in groundwater and deep soil layers. The results of different speciation of Cr extracted by the modified European Community Bureau of Reference (BCR) method showed that Cr existed primarily in the residual state (F4), with a relatively low content in the weak acid extraction state (F1). The correlation analysis indicated that Cr was affected by total Cr, pH, organic matter and total carbon during the longitudinal migration process. The RSP results revealed that the smelting site as a whole had a moderate level of pollution. Soil at depths of 2-5 m was more polluted than other soil layers. Consequently, it is necessary to treat the site soil as a whole, especially the subsoil layer (2-5 m). Health risk assessment demonstrated that the soil chromium pollution was hazardous to both adults and children, and the probability of carcinogenic and non-carcinogenic risk was relatively high in the latter group. As a result, children should be a group of special concern regarding the assessment and remediation of soil contaminated with Cr. This study can provide some insight into the contamination characteristics, ecological and health risks of chromium in contaminated soils and offer a scientific basis for the prevention and control of chromium pollution at abandoned smelting sites., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

The aging process can affect the physical and chemical properties as well as adsorption capacity of biochar. This study focuses on the heavy metal cadmium (Cd) as the research object, and artificially ages biochar prepared from rice straw and corn straw through accelerated freeze-thaw cycles, alternating dry wet cycles, and ultraviolet light treatment, in order to evaluate the effects of different aging conditions on the physical and chemical properties of the two different types of biochar and on their adsorption capacities for Cd. After aging, the pH of rice and corn biochar decreased to varying degrees, respectively. The surface structure was ruptured, the average pore diameter was decreased, and the specific surface area was increased by 27.3%, 21.9%, and 9.8% (rice) and 95.4%, 27.7%, and 13.4% (corn). Ultraviolet light aging has the most significant impact on the elemental content of biochar, and the C content was decreased by 12.4% (rice) and 9.3% (corn). The O content was increased by 11.2% (rice) and 44.1% (corn), and the numbers of O/C, H/C, (O + N)/C, and oxygen-containing functional groups were increased. These results demonstrate that the aging process reduces the degree of aromatization of biochar, while enhancing its polarity and Cd adsorption capacity. Rice straw biochar (RSB) has a greater ability to adsorb Cd than corn straw biochar (CSB). In addition, ultraviolet light aging is particularly effective in increasing heavy metal adsorption., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Phytoremediation is a cost-effective and eco-friendly plant-based approach promising technique to repair heavy metal-contaminated soils. However, a significant quantity of plant residues needs to be properly treated and utilized. Pyrolysis is an effective technology for converting residues to biochar, which can solve the problem and avoid secondary contamination. This paper reviews the generation, and physicochemical properties of biochar from phytoremediation residues, and its application in soil improvement, environmental remediation, and carbon sequestration. In spite of this, it is important to be aware of the potential toxicity of heavy metals in biochar and the environmental risks of biochar before applying it to practical applications. Future challenges in the production and application of residue-derived biochar include the rational selection of pyrolysis parameters and proper handling of potentially hazardous components in the biochar., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

A total of 30 samples from the downwind direction of a certain electroplating company in Jiaxing were collected in layers to analyze their heavy metal content. The soil risk assessment was conducted from the perspective of ecological and human health risks using the ground accumulation index method and human health risk assessment method. The results showed that in all samples, cadmium and arsenic far exceeded the soil background values, with an average exceeding multiple of 14.31 and 64.42, respectively, and a exceeding rate of 100%. After evaluation by the ground accumulation index, among these six heavy metals, arsenic and cadmium belong to extremely serious pollution levels. The human health risk assessment of electroplating plants found that in the exposure risk assessment, the ingestion value was much greater than the harm caused by breathing and skin, and the maximum exposure damage value of arsenic to children and adults was 4.17 × 10 -3 , among the carcinogenic risks, the risk brought by consumption is much greater than the respiratory and skin carcinogenic risk index, with the highest value score of 3.37 for cadmium, arsenic, and zinc carcinogenic risks 3.37 × 10 -6 , 2.42 × 10 -3 , 1.10 × 10 -4 ., (© 2024. The Author(s).)