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Cadmium (Cd) contamination is a widespread environmental issue. There is a lack of knowledge about the impacts of applying arbuscular mycorrhizal fungi (AMF) and biochar, either alone or in their combination, on alleviating Cd phytotoxicity in Ligustrum lucidum. Therefore, a pot experiment was conducted in a greenhouse, where L. lucidum seedlings were randomly subjected to four regimes of AMF treatments (inoculation with sterilized AMF, with Rhizophagus irregularis, Diversispora versiformis, alone or a mixture of these two fungi), and two regimes of biochar treatments (with or without rice-husk biochar), as well as three regimes of Cd treatments (0, 15, and 150 mg kg -1 ), to examine the responses of growth, photosynthetic capabilities, soil enzymatic activities, nutritional concentrations, and Cd absorption of L. lucidum plants to the interactive effects of AMF, biochar, and Cd. The results demonstrated that under Cd contaminations, AMF alone significantly increased plant total dry weight, soil pH, and plant nitrogen (N) concentration by 84%, 3.2%, and 13.2%, respectively, and inhibited soil Cd transferring to plant shoot by 42.2%; biochar alone significantly enhanced net photosynthetic rate, soil pH, and soil catalase of non-mycorrhizal plants by 16.4%, 9%, and 11.9%, respectively, and reduced the soil Cd transferring to plant shoot by 44.7%; the additive effect between AMF and biochar greatly enhanced plant total dry weight by 101.9%, and reduced the soil Cd transferring to plant shoot by 51.6%. Furthermore, dual inoculation with D. versiformis and R. irregularis conferred more benefits on plants than the single fungal species did. Accordingly, amending Cd-contaminated soil with the combination of mixed-fungi inoculation and biochar application performed the best than either AMF or biochar alone. These responses may have been attributed to higher mycorrhizal colonization, soil pH, biomass accumulation, and biomass allocation to the roots, as well as photosynthetic capabilities. In conclusion, the combined use of mixed-fungi involving D. versiformis and R. irregularis and biochar addition had significant synergistic effects on enhancing plant performance and reducing Cd uptake of L. lucidum plants in Cd-contaminated soil., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Nutrients are vital ingredients to boost plant health. The availability of nutrients is limited in fly ash (FA) waste to properly implement phytoremediation. The research explored the integration of microbes and treated wastewater irrigation in phytoremediation to provide the necessary nutrients for plant growth in fly ash-amended soils. The Box-Behnken method was used to design the experimental layout for the pot study. Response surface methodology (RSM) was applied as the optimization approach to model predictions for nutrient accumulation. The implemented pot study attained the highest morphological indicators with a plastochron index of 33.40, an absolute growth rate of 2.63 cm/day, and a leaf area of 2681.68 cm 2 and attained maximum biomass of 24.91 g for the treatments that included a mid-range of the variables. The combination of FA 14.98%, microbial dose 4.07 mL, and treated wastewater as the irrigation source was found to be the optimized combination for nitrogen and phosphorus accumulation of 212.4 and 8.867 mg/L., (© 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.)

Industrial development and the associated generation of waste requires attention for their management, treatment, and reduction without further degrading the quality of life. Microbes and plant-based bioremediation approaches are some of the sustainable strategies for the biodegradation of harmful pollutants instead of chemical-based treatment. Bioaugmentation is one such approach where microbial strains with the ability to degrade the targeted pollutant are introduced in a polluted environment. Harnessing of microbes from various locations, especially from the site of contamination (indigenous microbes), followed by optimization of the strains, inoculum size, media, and genetic engineering of the microbes along with a combination of strategies such as bio stimulation, phytoremediation is being applied to increase the efficiency of bioaugmentation. Further, bioaugmentation is influenced by various factors such as temperature, the composition of the pollutant, and microbial inoculum which needs to be considered for maximum efficiency of the treatment process. It has numerous advantages such as low cost, sustainability, and easy handling of the contaminants however, the major limitation of bioaugmentation is to increase the survival rate of the microbes involved in remediation for a longer duration in such a highly toxic environment. The review discusses these various aspects of bioaugmentation in brief for its large-scale implementation to address the global issue of pollution and environment management., (© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)

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.)