scholarly journals Heavy metals in contaminated soil: source, accumulation, health risk and remediation process

2021 ◽  
Vol 14 (1) ◽  
pp. 1-12
Author(s):  
A. Abdullahi ◽  
M. A. Lawal ◽  
A. M. Salisu

Heavy metals contamination of soil is an issue of global concern that ultimately results in toxicity and diseases in humans and animals through consumption of food crops from contaminated soil. The toxic effects of these metals, even though they do not have any biological role, remain present in some or the other form harmful for the human body and its proper functioning. Heavy metals in the soil refers to some significant heavy metals of biological toxicity, including Cobalt (Co), Cadmium (Cd), Lead (Pb), Chromium (Cr), and Arsenic (As) etc. With the development of the global economy, both type and content of heavy metals in the soil caused by indiscriminate use for human purposes has altered their geochemical cycles and biochemical balance. There are many known sources of harmful metals, including the earth, which releases them into food, air, and water, and anthropogenic activities, such as the application of fertilizer in agriculture, the use of pesticides and herbicides, and irrigation. Other sources are automobile emissions, paints, cigarette smoking, industries, and sewage and waste disposal. This review gives details about some heavy metals their toxicity, bioaccumulation, biodegradation, mobility and solubility in contaminated soil along with their health effects. Remediation of heavy metal in contaminated soils is necessary to reduce the associated risks, make the available soil safe for agricultural production, enhance food security and scale down land tenure problems arising from changes in the land use pattern the review recommends regular monitoring of heavy metals in soil, vegetables and foodstuffs to prevent excessive accrual in food chain.

ISRN Ecology ◽  
2011 ◽  
Vol 2011 ◽  
pp. 1-20 ◽  
Author(s):  
Raymond A. Wuana ◽  
Felix E. Okieimen

Scattered literature is harnessed to critically review the possible sources, chemistry, potential biohazards and best available remedial strategies for a number of heavy metals (lead, chromium, arsenic, zinc, cadmium, copper, mercury and nickel) commonly found in contaminated soils. The principles, advantages and disadvantages of immobilization, soil washing and phytoremediation techniques which are frequently listed among the best demonstrated available technologies for cleaning up heavy metal contaminated sites are presented. Remediation of heavy metal contaminated soils is necessary to reduce the associated risks, make the land resource available for agricultural production, enhance food security and scale down land tenure problems arising from changes in the land use pattern.


Biomolecules ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 448
Author(s):  
Mahrous Awad ◽  
Zhongzhen Liu ◽  
Milan Skalicky ◽  
Eldessoky S. Dessoky ◽  
Marian Brestic ◽  
...  

Heavy metals (HMs) toxicity represents a global problem depending on the soil environment’s geochemical forms. Biochar addition safely reduces HMs mobile forms, thus, reducing their toxicity to plants. While several studies have shown that biochar could significantly stabilize HMs in contaminated soils, the study of the relationship of soil properties to potential mechanisms still needs further clarification; hence the importance of assessing a naturally contaminated soil amended, in this case with Paulownia biochar (PB) and Bamboo biochar (BB) to fractionate Pb, Cd, Zn, and Cu using short sequential fractionation plans. The relationship of soil pH and organic matter and its effect on the redistribution of these metals were estimated. The results indicated that the acid-soluble metals decreased while the fraction bound to organic matter increased compared to untreated pots. The increase in the organic matter metal-bound was mostly at the expense of the decrease in the acid extractable and Fe/Mn bound ones. The highest application of PB increased the organically bound fraction of Pb, Cd, Zn, and Cu (62, 61, 34, and 61%, respectively), while the BB increased them (61, 49, 42, and 22%, respectively) over the control. Meanwhile, Fe/Mn oxides bound represents the large portion associated with zinc and copper. Concerning soil organic matter (SOM) and soil pH, as potential tools to reduce the risk of the target metals, a significant positive correlation was observed with acid-soluble extractable metal, while a negative correlation was obtained with organic matter-bound metal. The principal component analysis (PCA) shows that the total variance represents 89.7% for the TCPL-extractable and HMs forms and their relation to pH and SOM, which confirms the positive effect of the pH and SOM under PB and BB treatments on reducing the risk of the studied metals. The mobility and bioavailability of these metals and their geochemical forms widely varied according to pH, soil organic matter, biochar types, and application rates. As an environmentally friendly and economical material, biochar emphasizes its importance as a tool that makes the soil more suitable for safe cultivation in the short term and its long-term sustainability. This study proves that it reduces the mobility of HMs, their environmental risks and contributes to food safety. It also confirms that performing more controlled experiments, such as a pot, is a disciplined and effective way to assess the suitability of different types of biochar as soil modifications to restore HMs contaminated soil via controlling the mobilization of these minerals.


2019 ◽  
Vol 112 ◽  
pp. 03020
Author(s):  
Mihaela Niţu ◽  
Augustina Pruteanu ◽  
Despina Maria Bordean ◽  
Carmen Popescu ◽  
Gyorghy Deak ◽  
...  

Heavy metals in contaminated soils have benefited from a considerable attention due to the possible risks for the human body. The current study has investigated the accumulation and transfer coefficient for three heavy metals (Cu, Pb, Zn) found in the contaminated soil with three concentrations (c1=1.5%, c2=3.0%, c3=4.5%, c4=6.0%), obtained by mixing the three metals, in the tomato fruit. The highest accumulation in the tomato fruits was recorded for zinc, then copper and the smallest for lead, for all four concentrations used. The transfer coefficient decreases as the concentration of heavy metals increases, so that for high heavy metals concentrations, the values of the transfer coefficient are very low, and for small heavy metals concentrations in the soil, the values for the transfer coefficient are higher. The assessment of accumulation and transfer of heavy metals in the fruits of tomatoes grown in the contaminated soil has concluded that all concentrations of the copper, lead and zinc mix have shown a low risk for human consumption.


Author(s):  
Kanghee Cho ◽  
Eunji Myung ◽  
Hyunsoo Kim ◽  
Cheonyoung Park ◽  
Nagchoul Choi ◽  
...  

In this study, we investigated the feasibility of using a solution of sulfuric acid and phosphoric acid as an extraction method for soil-washing to remove Cu, Pb, Zn, and As from contaminated soil. We treated various soil particles, including seven fraction sizes, using sulfuric acid. In addition, to improve Cu, Pb, Zn, and As removal efficiencies, washing agents were compared through batch experiments. The results showed that each agent behaved differently when reacting with heavy metals (Cu, Pb, and Zn) and As. Sulfuric acid was more effective in extracting heavy metals than in extracting As. However, phosphoric acid was not effective in extracting heavy metals. Compared with each inorganic acid, As removal from soil by washing agents increased in the order of sulfuric acid (35.81%) < phosphoric acid (62.96%). Therefore, an enhanced mixture solution using sulfuric acid and phosphoric acid to simultaneously remove heavy metals and As from contaminated soils was investigated. Sulfuric acid at 0.6 M was adopted to combine with 0.6 M phosphoric acid to obtain the mixture solution (1:1) that was used to determine the effect for the simultaneous removal of both heavy metals and As from the contaminated soil. The removal efficiencies of As, Cu, Pb, and Zn were 70.5%, 79.6%, 80.1%, and 71.2%, respectively. The combination of sulfuric acid with phosphoric acid increased the overall As and heavy metal extraction efficiencies from the contaminated soil samples. With the combined effect of dissolving oxides and ion exchange under combined washings, the removal efficiencies of heavy metals and As were higher than those of single washings.


2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Chen-Yao Chu ◽  
Tzu-Hsing Ko

Heavy metal-contaminated soils were leached with various acid reagents, and a series of treatments was assessed to understand soil fertility after acid leaching. Aqua regia digestion and a five-step sequential extraction procedure were applied to determine heavy metal distribution. The average total concentrations of Zn, Cd, Cu, and Pb for contaminated soil were 1334, 25, 263, and 525 mg·kg−1 based on the ICP/AES quantitative analysis. Other than Pb extracted by H2SO4, over 50% removal efficiency of other heavy metals was achieved. A five-step sequential extraction revealed that the bound-to-carbonate and bound-to-Fe-Mn oxides were the major forms of the heavy metals in the soil. The addition of organic manure considerably promoted soil fertility and increased soil pH after acid leaching. Seed germination experiments demonstrated that after acid leaching, the soil distinctly inhibited plant growth and the addition of manure enhanced seed germination rate from 35% to 84%. Furthermore, the procedure of soil turnover after acid leaching and manure addition greatly increased seed germination rate by 61% and shortened the initial germination time. Seed germination in untreated soil was superior to that in acid-leached soil, illustrating that the phytotoxic effect of acid leaching is more serious than that of heavy metals.


2021 ◽  
Vol 2 (4) ◽  
pp. 53-58
Author(s):  
Hasnain Raza ◽  

As anthropogenic activities rise over the world, representing an environmental threat, soil contamination and treatment of polluted areas have become a worldwide concern. Bioremediation is a sustainable technique that could be a cost-effective mitigating solution for heavy metal-polluted soil regeneration. Due to the difficulties in determining the optimum bioremediation methodology for each type of pollutant and the lack of literature on soil bioremediation, we reviewed the main in-situ type, their current properties, applications, and techniques, plants, and microbe’s efficiency for treatment of contaminated soil. In this review, we describe the deeper knowledge of the in-situ types of bioremediation and their different pollutant accumulation mechanisms.


2020 ◽  
Vol 166 ◽  
pp. 01007
Author(s):  
Vasyl Savosko ◽  
Aleksandr Podolyak ◽  
Irina Komarova ◽  
Aleksey Karpenko

Object of research: to systematize (taking into account the possible consequences to biosphere) the known technologies for ecological restoration of soils contaminated by heavy metals and radionuclides. Only a healing technology should be recognized as one possible methodology for solving any soil problems. For soils contaminated by heavy metals and radionuclides healing patterns is conceptually ordered into the following levels: mission, strategy, technology. The mission of healthy soil should be aimed at maintaining the chemical elements content within the optimum interval. The strategy of healthy soil involves the regulation of individual elements content in the soil. Ex-situ a soil healing technology is implemented outside the original pollution site. In-situ, a soil healing technology is carried out directly on the original pollution site. Excavation of the contaminated soil layer is the first stage for ex-situ soil restoration. In the future it will be possible: 1) storage of contaminated soil at special landfills, 2) treatment of contaminated soil at a special reactor. All technologies for in-situ healthy of heavy metals contaminated soils can be ordered as: 1) localization, 2) deconcentration, 3) inactivation, 4) extraction.


2019 ◽  
Vol 7 (9) ◽  
pp. 357 ◽  
Author(s):  
Moonsuk Hur ◽  
Soo-Je Park

Heavy metal pollution is a serious environmental problem as it adversely affects crop production and human activity. In addition, the microbial community structure and composition are altered in heavy-metal-contaminated soils. In this study, using full-length 16S rRNA gene sequences obtained by a PacBio RS II system, we determined the microbial diversity and community structure in heavy-metal-contaminated soil. Furthermore, we investigated the microbial distribution, inferred their putative functional traits, and analyzed the environmental effects on the microbial compositions. The soil samples selected in this study were heavily and continuously contaminated with various heavy metals due to closed mines. We found that certain microorganisms (e.g., sulfur or iron oxidizers) play an important role in the biogeochemical cycle. Using phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) analysis, we predicted Kyoto Encyclopedia of Genes and Genomes (KEGG) functional categories from abundances of microbial communities and revealed a high proportion belonging to transport, energy metabolism, and xenobiotic degradation in the studied sites. In addition, through full-length analysis, Conexibacter-like sequences, commonly identified by environmental metagenomics among the rare biosphere, were detected. In addition to microbial composition, we confirmed that environmental factors, including heavy metals, affect the microbial communities. Unexpectedly, among these environmental parameters, electrical conductivity (EC) might have more importance than other factors in a community description analysis.


Author(s):  
Archana ◽  
Ajai Kumar Jaitly

Heavy metals especially lead, nickel, cadmium, copper, cobalt, chromium and mercury are more toxic and chief contaminants of the environment. Agricultural soils in many parts of the world are slightly to moderately polluted with heavy metals due to increase in geologic and anthropogenic activities (use of phosphate fertilizers, sewage sludge application, dust from smelters, industrial waste). Plants growing on these contaminated soils showed toxicity symptoms that results in reduce growth and activity which declined the productivity and posing threats to agro-ecosystems. They put plants under stress and affect their physiology. In this chapter, we have summarized the effects of heavy metals on plants including both symptoms and productivity.


Solid Earth ◽  
2014 ◽  
Vol 5 (1) ◽  
pp. 65-75 ◽  
Author(s):  
J. Paz-Ferreiro ◽  
H. Lu ◽  
S. Fu ◽  
A. Méndez ◽  
G. Gascó

Abstract. Anthropogenic activities are resulting in an increase of the use and extraction of heavy metals. Heavy metals cannot be degraded and hence accumulate in the environment, having the potential to contaminate the food chain. This pollution threatens soil quality, plant survival and human health. The remediation of heavy metals deserves attention, but it is impaired by the cost of these processes. Phytoremediation and biochar are two sound environmental technologies which could be at the forefront to mitigate soil pollution. This review provides an overview of the state of the art of the scientific research on phytoremediation and biochar application to remediate heavy-metal-contaminated soils. Research to date has attempted only in a limited number of occasions to combine both techniques, however we discuss the potential advantages of combining both, and the potential mechanisms involved in the interaction between phytoremediators and biochar. We identified specific research needs to ensure a sustainable use of phytoremediation and biochar as remediation tools.


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