Soil Cadmium Pollution Research Articles

Effects of Acid Modified Mineral Materials on Soil Cadmium Pollution and Plant Remediation

In response to the problem of soil heavy metal pollution, acid modified mineral materials were used to study the changes in adsorption performance, surface charge, and other indicators of four clay mineral materials, vermiculite, arsenic sandstone, shale, and zeolite, under acid modified conditions. The changes in soil physicochemical properties, heavy metal content, and plant growth before and after remediation were analyzed. The study showed that the introduction of acid modified adsorption materials increased the specific surface area and cation exchange capacity, enhanced adsorption performance, and provided theoretical reference for the mechanism and effect of remediation of cadmium contaminated soil. To optimize the application amount of remediation materials and develop cheap, effective, and scalable heavy metal remediation materials, it has important practical significance. Bangladesh J. Bot. 53(3): 803-809, 2024 (September) Special

The Combination of Biochar and Phosphorus-Containing Materials Can Effectively Enhance the Remediation Capacity of Amaranth on Cadmium-Contaminated Soil and Improve the Structure of Microbial Communities

Cadmium (Cd) pollution in soil has become a huge problem for agricultural production in China and even the world. Passivation and phytoremediation are two important remediation technologies for Cd pollution. In this study, the cadmium-contaminated and phosphorus-poor farmland soil around a mining area in Huainan was taken as the research object, and the remediation effect of biochar and phosphorus-containing materials on soil cadmium pollution was discussed. The results showed that the combined application of biochar and phosphorus-containing materials significantly reduced the pH of non-rhizosphere soil and rhizosphere soil, and increased the content of soil dissolved organic carbon (DOC). The combined application of biochar and phosphorus-containing materials significantly reduced soil pore water Cd and soil available Cd. In addition, both a single application of biochar and synergistic application of biochar and phosphorus-containing materials significantly increased the biomass of aboveground and underground parts of amaranth and soil urease and catalase activities. Phosphorus application reduced the bioavailability of Cd in soil. With the increase in phosphorus application, the content of available Cd in soil decreased significantly, and there was a certain negative correlation between Cd content and phosphorus content in plants. The abundance of beneficial microorganisms such as Ochrobactrum, Anaerolinea, Achromobacter, and Cellvibrio in soil was significantly increased after the synergistic application of biochar and phosphorus-containing materials.

Development and optimization of an Artificial Neural Network (ANN) model for predicting the cadmium fixation efficiency of biochar in soil

This study addresses the issue of soil cadmium pollution and the common problem of data missing during the training of artificial neural network models. A substantial amount of characteristic data regarding the immobilization of cadmium in soil through biochar was collected from the literature. Subsequently, data was organized and analyzed using correlation matrix analysis and feature importance analysis. The results revealed that the feature importance of biochar (52%) was relatively significant. A novel approach is introduced, involving a non-deterministic optimization technique based on linear interpolation to supplement the missing data within the dataset. The completed dataset effectively preserves the distributional characteristics of the original data, thereby enhancing the training performance of the neural network model. Through three phases, namely data incompleteness, data supplementation, and genetic algorithm optimization, the neural network model was progressively refined. The outcome of this iterative process is a high-performance artificial neural network model capable of predicting the efficiency of biochar in immobilizing cadmium in soil. The significance of these findings lies in their potential to advance the application of machine learning in environmental science, particularly in addressing complex pollution scenarios.

Understanding the role of pig manure, rice straw, and calcium carbonate on the cadmium pollution in soil–wheat system

Understanding the role of pig manure, rice straw, and calcium carbonate on the cadmium pollution in soil–wheat system

Characteristics of different types of nano-biochar and their effects on remediation of cadmium pollution in soil

Characteristics of different types of nano-biochar and their effects on remediation of cadmium pollution in soil

Research And Impact of Bioremediation on Soil Cadmium

There are many studies on the interaction between Cd pollution and bioremediation at home and abroad, mainly local and short-term toxicological effects, and there is a lack of systematic reviews. The purpose of this report is to provide a summary of the research on several bioremediation methods through specific experiments and mechanisms. and a summary and report on the principles and mechanisms of phytoremediation technology and animal remediation technology. In the future, bioremediation technology should focus on further exploration in the treatment cycle and final treatment of materials, avoid secondary pollution, strengthen the prevention and control of soil cadmium pollution, master more scientific soil cadmium pollution prevention and control technology, and expand more experiments and research on bioremediation If necessary, researchers can comprehensively apply and match a variety of different control technologies to enhance the control effect of soil cadmium pollution. It is also hoped that more attention will be paid to some potential future research on remediation methods for soil cadmium pollution, and that bioremediation is not only for the further exploration and discovery of cadmium and other heavy metal pollution in soil.

Effect of plant growth regulators on rice plants (Oryza sativa L.) growth under cadmium stress

In numerous developing countries, including Kazakhstan, the issue of soil contamination with cadmium is prominent due to the expansion of the mining and metallurgical sectors. A significant contributor to cadmium pollution in soil is the widespread application of phosphorus-based fertilizers and pesticides that contain cadmium. Even trace amounts of cadmium, accumulating in the soil, can decrease crop yields, impede plant growth, and disrupt various physiological and biochemical processes. Consequently, this study aimed to identify cadmium-resistant rice varieties and explore methods to mitigate cadmium toxicity using growth regulators. The investigation examined the effects of growth-stimulating substances, such as “Epin-Extra” (an epibrassinolide alcohol solution), “Cyrcon” (a hydroxycinnamic acid solution), and “Beres-4 universal” (potassium humate), under cadmium-induced stress. Additionally, the research aimed to elucidate how the structural components of these substances relate to reducing cadmium’s toxic impact on rice plants. The findings suggest that these growth-stimulating substances could be beneficial in ameliorating the adverse effects of cadmium on plants.

Exploring the remediation potential of Hydrangea macrophylla (Thunb.) Ser. in cadmium-contaminated soil by comparing cultivars and seedling age

The current situation regarding soil cadmium pollution in China is far from optimistic, necessitating the exploration of more viable Cd pollution-remediating plants. Several studies have shown that ornamental plants have excellent potential for application in soil pollution remediation. However, research on the Cd tolerance capacity of Hydrangea remains scarce, and the effects of plant age on heavy metal tolerance has not been thoroughly investigated. In this study, greenhouse pot experiments were conducted with artificially prepared Cd-polluted soil at various concentrations (0–240 mg·kg−1). Two cultivars of H.macrophylla, “Endless Summer” (H.'ES') and “Classic Rood” (H.'CR'), were cultivated in different Cd-contaminated soil levels for 60 d, after which the growth response, physiological changes, mineral element absorption, and Cd concentration of different plant parts were measured. The effect of plant age on the heavy metal absorption capacity of H. macrophylla was also explored. The results showed that under Cd stress, the antioxidant activity and penetration-regulating substance content of H. macrophylla increased, and the absorption of Mg, Mn, and Zn changed. Under all Cd treatments, Cd concentrations in the roots were higher than those in the shoots of the cultivars, with a bioconcentration factor of > 1 and a translocation factor of < 1. The tolerance to Cd of the H.'CR' was stronger than that of the H.'ES'. The Cd tolerance of H. macrophylla increased with seedling age. This study indicated that H. macrophylla is a suitable candidate for Cd phytostabilization and the remediation of Cd-polluted soils to limit harm caused by Cd flow in the ecosystem.

Soil cadmium pollution facilitated the invasion of alligator weed through enhanced herbivore resistance and competitive ability over a congeneric species.

A number of invasive plant species, such as Alternanthera philoxeroides, have been documented to be able to accumulate trace metal elements in their tissues. Since metal accumulation in plants can serve as a defence against herbivores, we hypothesized that metal pollution will increase herbivore resistance of metal-accumulating invasive plant species and such a benefit will grant them a competitive advantage over local co-occurring plants. In this study, we compared the differences in plant growth and herbivore feeding preference between A. philoxeroides and its native congener Alternanthera sessilis in single and mixed cultures with and without soil cadmium (Cd) pollution. The results showed that A. philoxeroides plants were more tolerant to Cd stress and accumulated more Cd in the leaves than A. sessilis. Cd exposure increased the resistance of A. philoxeroides against a specialist and a generalist herbivore compared withA. sessilis. Competition experiments indicated that Cd stress largely increased the competitive advantage of A. philoxeroides over A. sessilis with or without herbivore pressures. The differences in herbivore resistance between the two plant species under soil Cd stress are most likely due to the deterring effect of Cd accumulation and Cd-enhanced mechanical defences rather than changes in leaf specialized metabolites.

Two cadmium-resistant strains of agricultural soil effective in remediating soil cadmium pollution

Cadmium (Cd) contamination in soil is particularly serious and its remediation is particularly important. Microbial passivation or immobilization is a feasible means for remediation of heavy metal contamination. In order to enrich the options for microbial remediation of soil Cd contamination and provide the possibility of efficient remediation, this study screened two Cd-tolerant strains (Bacterium IRHB1–74 and Microbacterium sp. SW615), examined their Cd removal performance, and application effects in potting experiments, and discussed the remediation mechanism from the level of microbial communities. The results revealed that the minimum inhibitory concentrations of the two strains were 100 and 50 mg·L-1, respectively. Scanning electron microscope, Energy dispersive spectrometry and Fourier transform infrared analyses of the two strains indicated that surface complexation and electrostatic attraction were the main mechanisms employed for Cd biosorption. The use of the two strains caused significant changes in the number of soil microbial community operational taxonomic units and in the abundance of Firmicutes, Verrucomicrobia, Patescibacteria, Bacteroidetes, and Acidobacteria in the soil, which in turn increased the soil pH, organic matter, available potassium content, and enhanced the urease, alkaline phosphatase, and catalase activities. The two strains effectively reduced the available Cd content in the rhizosphere soil of rape by 32.98%− 60.54%, and reduced the Cd content in the roots and stems of rape by 50.94%− 60.53% and 27.38%− 40.61% Cd, and it was confirmed by plant malondialdehyde content, superoxide dismutase activity and other physiological indicators.

Transcriptome studies on cadmium tolerance and biochar mitigating cadmium stress in muskmelon

Cadmium pollution in agricultural soil is a great threat to crop growth and human health. In this research, with 1%, 3% and 5% biochar applied to control soil cadmium pollution, melon was selected to be the experimental object for physiological detection and transcriptome analysis, through which we explored the mechanism of cadmium tolerance and biochar mitigating cadmium stress in muskmelon. Three set concentrations of biochar have a mitigative effect on muskmelon cadmium stress, and 5% biochar and 3% biochar respectively have the best and the worst alleviative effect. The alleviation of biochar to cadmium stress on muskmelon is primarily in the manner of inhibiting cadmium transfer, while the resistance of muskmelon to cadmium stress is through activating phenylpropanoid pathway and overexpressing stress related genes. Under cadmium treatment, 11 genes of the phenylpropane pathway and 19 stress-related genes including cytochrome P450 family protein genes and WRKY transcription factor genes were up-regulated, while 1%, 3%, 5% biochar addition significantly downregulated 3, 0, 7 phenylpropane pathway genes and 17, 5, 16 stress-related genes, respectively. Genes such as cytochrome P450 protein family genes, WRKY transcription factor genes, and annexin genes may play a key role in muskmelon's resistance to cadmium stress. The results show the key pathways and genes of cadmium stress resistance and the effect of different concentrations of biochar in alleviating cadmium stress, which provide a reference for the research of cadmium stress resistance in crops and the application of biochar in cadmium pollution in agricultural soil.

Effect of Thermal Activation Temperature of Nanoscale Phosphate and Silicate on the Morphological Transformation Characteristics of Cd in Heavy Metal Contaminated Soils

Purpose. The problem of heavy metal Cd pollution in the soil is still very serious. The widely used treatment measure is in situ passivation chemical remediation technology. Some studies have shown that the single application of phosphate or silicate can control soil cadmium pollution, but few studies have been conducted on the effect of the thermal activation temperature of nano phosphate and silicate-combined application on the transformation of Cd form in the soil. Materials and methods. Cadmium-contaminated soil was indoor-simulated, after which the 2.0% soil-weight dose of potassium dihydrogen phosphate was mixed with thermal activation nano serpentine or nano zeolite (potassium dihydrogen phosphate: thermal activation nano serpentine or nano zeolite = 1:2) at different temperatures (0, 350, 550, 700, 850 °C) and compared with the simulated cadmium-contaminated soil without adding a mixture of phosphate and silicate; cadmium content in soil was determined by Tessier five-step continuous extraction method after incubating for 0, 7, 14, 28, and 56 d in jars in the constant-temperature box. Results and discussion. Thermal activation temperature of nano phosphate and silicate could reduce the amount of exchangeable Cd content in the soil to a different degree; the content of Cd in carbonate-bound form, Fe–Mn–oxide-bound form, organically-bound form, and residual form increased. The order of effect of nanoscale potassium dihydrogen phosphate and serpentine or zeolite thermal activation temperature on remediation of Cd contaminated soil is nPS700-2.0 &gt; nPS550-2.0 &gt; nPS850-2.0 &gt; nPS350-2.0 &gt; nPS0-2.0, nPF700-2.0 &gt; nPF550-2.0 &gt; nPF850-2.0 &gt; nPF350-2.0 &gt; nPF0-2.0 (n, P, S, and F represent nanometer, KH2PO4, serpentine, and zeolite, respectively; 0, 350, 550, 700, and 850 represent different activation temperatures T); 700 °C treatments performed better than other thermal activation temperature treatments, and nPS700-2.0 was better than nPF700-2.0. Conclusion. Thermal activation temperature of nano phosphate and silicate-combined application can stabilize heavy metal Cd to some extent and promote the transition of Cd from a bioavailable state to a biounavailable state. The results showed that the combined application of thermal activation temperature of nano phosphate and silicate has a certain potential to control soil cadmium pollution.

Challenges and opportunities for improving the environmental quality of cadmium-contaminated soil in China

Considering the soil cadmium pollution problem, the Chinese government proposed to estimate the costs and practicality "to completely improve the soil quality by the middle of this century". This study analyzed the challenges in achieving this goal using biophysical data from 10 typical demonstration soil phytoextraction projects. The current annual phytoextraction efficiency was determined as 14.8–490 g ha−1 a−1 at 319 RMB g−1 cadmium. A total of 798 billion RMB and 5 years were required for remediation of cadmium contamination, which was 22 times the investment in soil remediation during 2016–2022. The break-even point of phytoextraction projects was 29 years. The heavy financial burden was considered the primary challenge in improving the environmental quality of such soil. The cost could be reduced by 5.5–35.3 % through optimization measures such as resourcefulness of hyperaccumulator harvests, large-scale breeding, and mechanized management. The break-even point could be shortened to 6–15 years by intercropping/rotating crops, contributing to the goal. Active exploration of phytoextraction efficiency—more efficient accumulators, optimized agronomic measures—is worth practicing.

Carbonate mineral controls the transport of Cd from tailings to surrounding soils: An example from Cd-rich Niujiaotang Zn mine in Guizhou Province, Southwest China

Heavy metal pollution derived from the oxidation of sulfides in Pb-Zn mine tailings has been a common public concern. Although the oxidative dissolution of sphalerite will release cadmium into the soil environment, it is still unclear whether other minerals contain a large amount of cadmium and how much these minerals contribute to the surrounding environmental media. In this paper, XRD, particle size analyzer, SEM-EDS and improved BCR sequential extraction method were used to analyze cadmium rich zinc mine tailing and adjacent farmland soil in Duyun, Guizhou Province. The results show that the average contents of Pb, Zn, and Cd in tailing are 214 ± 71 mg/kg, 2668 ± 773 mg/kg, and 37.5 ± 9.97 mg/kg respectively. While in the surrounding soil, they were 519 ± 280 mg/kg, 3,779 ± 2614 mg/kg, and 30.8 ± 14.4 mg/kg respectively. The mineralogical composition of tailing is mainly dolomite and less pyrite. Cadmium in tailing is mainly in weak acid extractable state, indicating that cadmium mainly exists in dolomite of tailing. Pyrite in tailing generates acid through oxidation, which accelerates the dissolution of dolomite, thus releasing Cd from minerals and migrating to surrounding farmland, resulting in soil cadmium pollution. This study reveals an important process that has been neglected. Carbonate minerals play an important role in the migration of cadmium in the tailing of the Mississippi Valley-type (MVT) lead-zinc mine and the soils affected by the tailing.

Efficient Remediation of Cadmium Contamination in Soil by Functionalized Biochar: Recent Advances, Challenges, and Future Prospects

Heavy metal pollution in soil seriously harms human health and animal and plant growth. Among them, cadmium pollution is one of the most serious issues. As a promising remediation material for cadmium pollution in soil, functionalized biochar has attracted wide attention in the last decade. This paper summarizes the preparation technology of biochar, the existing forms of heavy metals in soil, the remediation mechanism of biochar for remediating cadmium contamination in soil, and the factors affecting the remediation process, and discusses the latest research advances of functionalized biochar for remediating cadmium contamination in soil. Finally, the challenges encountered by the implementation of biochar for remediating Cd contamination in soil are summarized, and the prospects in this field are highlighted for its expected industrial large-scale implementation.

Knowledge Mapping of the Phytoremediation of Cadmium-Contaminated Soil: A Bibliometric Analysis from 1994 to 2021.

Cadmium pollution of soil threatens the environmental quality and human health. Phytoremediation of cadmium-contaminated soil has attracted global attention in recent decades. This study aimed to conduct a comprehensive and systematic review of the literature on phytoremediation of cadmium-contaminated soil based on bibliometric analysis. A total of 5494 articles published between 1994 and 2021 were retrieved from the Web of Science Core Collection. Our knowledge mapping presented the authors, journals, countries, institutions, and other basic information to understand the development status of phytoremediation of cadmium-contaminated soil. Based on a keyword cluster analysis, the identified major research domains were “biochar”, “Thlaspi caerulescens”, “endophytic bacteria”, “oxidative stress”, “EDTA”, and “bioconcentration factor”. Overall, this study provided a detailed summary of research trends and hotspots. Based on the keyword co-occurrence and burst analysis, the core concepts and basic theories of this field were completed in 2011. However, the pace of theoretical development has been relatively slow. Finally, future research trends/frontiers were proposed, such as biochar addition, rhizosphere bacterial community manipulation, cadmium subcellular distribution, and health risk assessment.

Planning of ecologically suitable areas for Ligusticum chuanxiong under background of soil cadmium pollution

Chuanxiong Rhizoma is a traditional Chinese medicinal material mainly produced in Sichuan and Chongqing of China. In recent years, the cadmium content in Chuanxiong Rhizoma produced in most of the genuine producing areas has exceeded the standard, which makes Chuanxiong Rhizoma difficult to be exported. To solve the problem of excessive cadmium content in soil, this study employed the MaxEnt model to simulate the potential geographic distribution of Ligusticum chuanxiong and evaluate important environmental factors, and re-plan its ecologically suitable areas based on the mineral distribution characteristics and soil cadmium pollution status. The results showed that the places suitable for L. chuanxiong growing covered an area of 335 523.69 km~2, mainly in central and eastern Sichuan, southern Shaanxi and most parts of Chongqing. Among them, the highly suitable areas of L. chuanxiong were mainly concentrated in Chengdu, Ya'an, Deyang, and Mianyang. Solar radiation, annual precipitation, and annual range of temperature were evaluated as important variables affecting the distribution of L. chuanxiong, with the contribution rates of 62.3%, 13.3%, and 6.8%, respectively. In addition, Qionglai county, Chongqing county, Mianyang city(Youxian district and Fucheng district), Qingchuan county, and Xinjin county were classified into the first-class ecologically suitable zone, covering a total area of 2 768.87 km~2. The se-cond-class ecologically suitable zone was even wider, involving such counties as Tongjiang county, Renshou county, Jianyang county, and Nanjiang county, and the total area reached 43 616.92 km~2. The re-planning of the ecologically suitable areas for L. chuanxiong has provided strong data support for the cultivation and resource development of L. chuanxiong and also new ideas for solving the problem of excessive cadmium content in L. chuanxiong.

Soil contamination with cadmium and potential risk around various mines in China during 2000–2020

Cadmium (Cd) pollution in mining areas is the most important challenge for soil environment management in China. Assessing the actual Cd pollution risk in various mining areas and identifying the core areas requiring supervision can provide a basis for government departments and industries to carry out detailed further investigations in key areas. In this study, we collated published data on metal mine circumjacent soil contaminated by Cd in China from 2002 to 2020 to conduct a comprehensive study on soil cadmium pollution and ecological and health risks in mining areas. The temporal and spatial variations of Cd concentrations and the pollution source were investigated. Results indicated that the Cd concentration in soil was strongly associated with the types of mining area. The Cd pollution in the circumjacent soil of lead-zinc and tungsten mines with high heavy metal pollution discharging coefficient was more serious than the soil around other mines. Identification of temporal and spatial variations for soil Cd in China indicated that the high Cd concentrations were found in the central, southern, and southwestern regions of China, and the distribution of mining activities in these regions are relatively concentrated. Meanwhile, a temporal turning point in the mean soil Cd concentration occurred in these regions in 2012, which indicated that the heavy metal control management policy implemented by the government was effective. The ecological risk of soil Cd pollution around mining areas was moderate to high. Health risk assessment showed that some regions adjacent mining areas had a high non-carcinogenic risk, notably, lead-zinc and tungsten mining areas were more serious. Supervision should focus on reducing ecological risks and protecting the safety of agricultural products rather than concentrating on health risks. The research results provide a reference for the priority management of contaminated soil in mining areas.

Remediation of soil cadmium pollution by biomineralization using microbial-induced precipitation: a review.

In recent years, with industrial pollution and the application of agricultural fertilizers with high cadmium (Cd) content, soil Cd pollution has become increasingly serious. A large amount of Cd is discharged into the environment, greatly endangering the stability of the ecological environment and human health. The use of microorganisms to induce Cd precipitation and mineralization is an important bioremediation method. Itis highly efficient, has a low cost, enables environmental protection, and convenient to operate. This article summarizes the pollution status, pollution source, biological toxicity and existing forms of Cd, as well as the biomineralization mechanism of microbial induced Cd(II) precipitation, mainly including microbial-induced carbonate precipitation, microbial-induced phosphate precipitation and microbial-induced sulfide precipitation. Factors affecting the bioremediation of Cd, such as pH, coexisting ions, and temperature, are introduced. Finally, the key points and difficulties of future microbe-induced Cd(II) biomineralization research are highlighted, providing a scientific basis and theoretical guidance for the application of microbe-induced Cd(II) immobilization in soil.

The Mechanism of Plant Resistance to Cadmium in Soil

In recent years, soil heavy metal pollution has caused serious harm to human beings and the environment. Phytoremediation has become the main means of soil remediation because of its advantages such as low cost, obvious effect and low secondary pollution. In this paper, the status quo and harm of soil cadmium pollution in China and the mechanism of phytoremediation of cadmium were summarized.