To reveal the distribution patterns of pollutants in the elementary landscape-geochemical systems (ELGS) (top-slope-closing depression), the .sup.137Cs distribution was studied in detail in the ...soil-moss cover of the test site, which characterizes undisturbed forest landscapes subjected to the fallout of technogenic radionuclides during the Chernobyl accident. Over the thirty years after the primary contamination, no unidirectional .sup.137Cs migration from top to the closing depression was found in the ELGS. In contrast, all studied ELGS show the well expressed .sup.137Cs cyclical variation, which is traced both in the soil and in the vegetation (moss) cover. The pattern of .sup.137Cs variability in the moss cover is generally similar to the surface soil contamination, but in some cases demonstrates specific features. At present, the top 8-cm soil layer contains from 70 to 96% of total .sup.137Cs content of soil cover, while 0-20-cm layer hosts 89-99% .sup.137Cs. Such vertical distribution makes it possible to apply field spectrometry technique for study of the spatial structure of .sup.137Cs contamination field. The .sup.137Cs content in the photosynthesizing part of the moss best correlates with its reserve in the 2-4 cm soil layer (r.sub.0.01 = 0.747, n = 15). The revealed structural heterogeneity results from secondary redistribution of the radionuclide in ELGS and, in our opinion, reflects the general regularities of element migration in such systems.
The aim of this study was to determine the effect of copper soil contamination on the trace element content of sunflower aerial parts and in roots. Another aim was to assess whether the introduction ...of selected neutralizing substances (molecular sieve, halloysite, sepiolite and expanded clay) into the soil could reduce the impact of copper on the chemical composition of sunflower plants. Copper soil contamination with 150 mg Cusup.2+ kgsup.−1 of soil and 10 g of each adsorbent per kg of soil were used. Soil contamination with copper caused a significant increase in the content of this element in the aerial parts (by 37%) and roots (by 144%) of sunflower. Enriching the soil with the mineral substances reduced the amount of copper in the aerial parts of sunflower. Halloysite had the greatest effect (35%), while expanded clay had the smallest effect (10%). An opposite relationship was found in the roots of this plant. In copper-contaminated objects, a decrease in the content of cadmium and iron and an increase in the concentrations of nickel, lead and cobalt in the aerial parts and roots of sunflower were observed. The applied materials reduced the content of the remaining trace elements more strongly in the aerial organs than in the roots of sunflower. Molecular sieve had the greatest reducing effect on the content of trace elements in sunflower aerial organs, followed by sepiolite, while expanded clay had the least impact. The molecular sieve also reduced the content of iron, nickel, cadmium, chromium, zinc and, especially, manganese, whereas sepiolite reduced the content of zinc, iron, cobalt, manganese and chromium in sunflower aerial parts. Molecular sieve contributed to a slight increase in the content of cobalt, while sepiolite had the same effect on the content of nickel, lead and cadmium in the aerial parts of sunflower. All materials decreased the content of chromium in sunflower roots, molecular sieve-zinc, halloysite-manganese, and sepiolite-manganese and nickel. The materials used in the experiment, especially the molecular sieve and to a lesser extent sepiolite, can be used effectively to reduce the content of copper and some other trace elements, particularly in the aerial parts of sunflower.
In recent years, soil pollution is a major global concern drawing worldwide attention. Earthworms can resist high concentrations of soil pollutants and play a vital role in removing them effectively. ...Vermiremediation, using earthworms to remove contaminants from soil or help to degrade non-recyclable chemicals, is proved to be an alternative, low-cost technology for treating contaminated soil. However, knowledge about the mechanisms and framework of the vermiremediation various organic and inorganic contaminants is still limited. Therefore, we reviewed the research progress of effects of soil contaminants on earthworms and potential of earthworm used for remediation soil contaminated with heavy metals, polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs), pesticides, as well as crude oil. Especially, the possible processes, mechanisms, advantages and limitations, and how to boost the efficiency of vermiremediation are well addressed in this review. Finally, future prospects of vermiremediation soil contamination are listed to promote further studies and application of vermiremediation in contaminated soils.
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•Earthworms are useful for the removal of heavy metals and organic contaminants from soil.•Vermiremediation consist of accumulation, transformation, and degradation of the contaminants.•Remediation can be boosted by the addition of surfactants, biochar and co-application with phytoremediation.
At least 300 Mio t of plastic are produced annually, from which large parts end up in the environment, where it persists over decades, harms biota and enters the food chain. Yet, almost nothing is ...known about plastic pollution of soil; hence, the aims of this work are to review current knowledge on i) available methods for the quantification and identification of plastic in soil, ii) the quantity and possible input pathways of plastic into soil, (including first preliminary screening of plastic in compost), and iii) its fate in soil. Methods for plastic analyses in sediments can potentially be adjusted for application to soil; yet, the applicability of these methods for soil needs to be tested. Consequently, the current data base on soil pollution with plastic is still poor. Soils may receive plastic inputs via plastic mulching or the application of plastic containing soil amendments. In compost up to 2.38–1200mg plastic kg−1 have been found so far; the plastic concentration of sewage sludge varies between 1000 and 24,000 plastic items kg−1. Also irrigation with untreated and treated wastewater (1000–627,000 and 0–125,000 plastic items m−3, respectively) as well as flooding with lake water (0.82–4.42 plastic items m−3) or river water (0–13,751 items km−2) can provide major input pathways for plastic into soil. Additional sources comprise littering along roads and trails, illegal waste dumping, road runoff as well as atmospheric input. With these input pathways, plastic concentrations in soil might reach the per mill range of soil organic carbon. Most of plastic (especially >1μm) will presumably be retained in soil, where it persists for decades or longer. Accordingly, further research on the prevalence and fate of such synthetic polymers in soils is urgently warranted.
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•Analytical methods and possible input pathways of plastic in soil were discussed.•Organic matter challenges plastic quantification in soil.•Soil amendments and irrigation are likely major plastic sources in agricultural soils.•Flooding, atmospheric input and littering can potentially pollute even remote soil.•Leaching of small plastics from soil into groundwater cannot be excluded.
In recent years, environmental pollution is a major global concern and adversely affecting human health and the economy. The environmental properties of soil are exceptionally complex, which makes ...the remediation and treatment more challenging and expensive. In this aspect, sustainable materials (biomaterials, biochar, and composites) present an effective and efficient remediation solution. Exactly, biochar and its relative composites can achieve novel properties with addition of metal oxides, surface agents, and nano-material. The present review study provides quantitative analysis and addresses the advantages of using biochar composites relative with pure biochar. The synthesis of Nano-metal assisted biochar, properties and utilization in improving soil properties as well as heavy metal removal are reviewed. Specific attention has been paid to the impacts of biochar and its composite on soil fundamental properties such as pH, cation exchange efficiency, bulk density, porosity, water retention capability, soil organic matter (SOM) and redox reactions. Significant emphasis is focused on soil remediation, in particular, the elimination of heavy metals utilizing biochar-based composites. Further research is urged to verify the proposed mechanisms involved biochar composites-microbial interactions and heavy metal remediation considering short term and long term efficiency for improvement.
Highlights
Progress in development, synthesis methods, and application of biochar-based composites in the soil are studied.
The impact mechanisms of biochar composites on essential soil properties have been studied.
Biochar-based composites have a significant effect on bulk density and water retention capacity.
Biochar-based composites were found to be better than pristine biochar in soil heavy metal remediation.
The potential use of biochar-based composites in different soil heavy metal remediation prospected.
Source apportionment can be an effective tool in mitigating soil pollution but its efficacy is often limited by a lack of information on the factors that influence the accumulation of pollutants at a ...site. In response to this limitation and focusing on a suite of heavy metals identified as priorities for pollution control, the study established a comprehensive pollution control framework using factor identification coupled with spatial agglomeration for agricultural soils in an industrialized part of Zhejiang Province, China. In addition to elucidating the key role of industrial and traffic activities on heavy metal accumulation through implementing a receptor model, specific influencing factors were identified using a random forest model. The distance from the soil sample location to the nearest likely industrial source was the most important factor in determining cadmium and copper concentrations, while distance to the nearest road was more important for lead and zinc pollution. Soil parent materials, pH, organic matter, and clay particle size were the key factors influencing accumulation of arsenic, chromium, and nickel. Spatial auto-correlation between levels of soil metal pollution and industrial agglomeration can enable a more targeted approach to pollution control measures. Overall, the approach and results provide a basis for improved accuracy in source apportionment, and thus improved soil pollution control, at the regional scale.
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•Provision of a framework that links heavy metals in soils with their source.•Identification of environmental influence over heavy metal contamination of soils.•Spatially integrated industrial agglomerations and heavy metal-contaminated soils.•Basis for targeted measures aimed at mitigating pollution and health risks.
Mercury (Hg) is a potentially harmful trace element in the environment and one of the World Health Organization's foremost chemicals of concern. The threat posed by Hg contaminated soils to humans is ...pervasive, with an estimated 86 Gg of anthropogenic Hg pollution accumulated in surface soils worldwide. This review critically examines both recent advances and remaining knowledge gaps with respect to cycling of mercury in the soil environment, to aid the assessment and management of risks caused by Hg contamination. Included in this review are factors affecting Hg release from soil to the atmosphere, including how rainfall events drive gaseous elemental mercury (GEM) flux from soils of low Hg content, and how ambient conditions such as atmospheric O3 concentration play a significant role. Mercury contaminated soils constitute complex systems where many interdependent factors, including the amount and composition of soil organic matter and clays, oxidized minerals (e.g. Fe oxides), reduced elements (e.g. S2−), as well as soil pH and redox conditions affect Hg forms and transformation. Speciation influences the extent and rate of Hg subsurface transportation, which has often been assumed insignificant. Nano-sized Hg particles as well as soluble Hg complexes play important roles in soil Hg mobility, availability, and methylation. Finally, implications for human health and suggested research directions are put forward, where there is significant potential to improve remedial actions by accounting for Hg speciation and transportation factors.
•Mercury contaminated soils constitute complex systems with many interdependent factors.•Speciation, complexation and particle size play important roles in subsurface transport.•Rainfall events and atmospheric ozone levels influence Hg flux to the atmosphere.•Implications for human health and suggested research directions are put forward.
The accurate spatial mapping of heavy metal levels in agricultural soils is crucial for environmental management and food security. However, the inherent limitations of traditional interpolation ...methods and emerging machine-learning techniques restrict their spatial prediction accuracy. This study aimed to refine the spatial prediction of heavy metal distributions in Guangxi, China, by integrating machine learning models and spatial regionalization indices (SRIs). The results demonstrated that random forest (RF) models incorporating SRIs outperformed artificial neural network and support vector regression models, achieving R2 values exceeding 0.96 for eight heavy metals on the test data. Hierarchical clustering for feature selection further improved the model performance. The optimized RF models accurately predicted the heavy metal distributions in agricultural soils across the province, revealing higher levels in the central-western regions and lower levels in the north and south. Notably, the models identified that 25.78 % of agricultural soils constitute hotspots with multiple co-occurring heavy metals, and over 6.41 million people are exposed to excessive soil heavy metal levels. Our findings provide valuable insights for the development of targeted strategies for soil pollution control and agricultural soil management to safeguard food security and public health.
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•SRIs compensate for the absent spatial information.•Random forest incorporating SRIs outperformed other models.•Refined spatial distribution of soil heavy metals identified pollution hotspots.•Ecological and human health risks of heavy metal contamination are determined.
Emerging contaminants (ECs) are gaining attention due to their prevalence and potential negative impacts on the environment and human health. This paper provides a comprehensive review of the status ...and trends of soil pollution caused by ECs, focusing on their sources, migration pathways, and environmental implications. Significant ECs, including plastics, synthetic polymers, pharmaceuticals, personal care products, plasticizers, and flame retardants, are identified due to their widespread use and toxicity. Their presence in soil is attributed to agricultural activities, urban waste, and wastewater irrigation. The review explores both horizontal and vertical migration pathways, with factors such as soil type, organic matter content, and moisture levels influencing their distribution. Understanding the behavior of ECs in soil is critical to mitigating their long-term risks and developing effective soil remediation strategies. The paper also examines the advantages and disadvantages of in situ and ex situ treatment approaches for ECs, highlighting optimal physical, chemical, and biological treatment conditions. These findings provide a fundamental basis for addressing the challenges and governance of soil pollution induced by ECs.
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•The research status of ECs on soil have been reviewed.•A possible interaction mechanism between soil and ECs has been proposed.•The distribution and migration pathways of ECs in soil have been described.•Promising future directions have been proposed for mitigating the contamination of soil by ECs.
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