Appraisal of Metal(loids) in the Ecosystem

By Vinod Kumar

Heavy metal pollution is a serious threat to living organisms. Industrial development has aggravated multifaceted problems in the environment requiring a comprehensive solution. Appraisal of Metal(loids) in the Ecosystem addresses this need and provides a basic introduction of different heavy metals. Presented in a consistent and comprehensive manner, each chapter highlights the background level, occurrence, speciation, bioavailability, uptake detoxification mechanisms, and management of each metal in polluted soils. It provides the latest up-to-date information about different aspects of As, Hg, Si, Cu, Co, Ni, Mn, Cd, Cr, etc. in single source. This book provides scientists and researchers with the most current source of information on the topic. Written by a global and diverse group of experts, Appraisal of Metal(loids) in the Ecosystem also covers the many field applications associated with phytoremediation and extraction and provides guidance on decision making when selecting advanced techniques.

• Proposes strategies to mitigate metalloid toxicity and pollution in soils
• Covers various phytoremediation technique for appraisal of metalloids
• Includes case studies involving remediation of heavy metal contaminated soils using advanced technologies

• Language: English
• Publisher: Elsevier Science
• Release date: Aug 18, 2022
• ISBN: 9780323885508

Book preview

1

Overview of phytoremediation techniques for the assessment of metal(loid)s

Asma Javaida, and Nargis Nelofarb

a Department of BotanyGDC Udhampur (Boys), Udhampur, Jammu and ­Kashmir, India

b Department of ZoologyGCW Gandhinagar, Jammu, Jammu and Kashmir, India

1.1 Introduction

Soil is the backbone of our agricultural system and has greatly contributed in green revolution and food safety (Lichtfouse and Eglinton, 1995; Sivarajasekar and Baskerr, 2014a, b, c). Healthy soil produces healthy crops that in turn nourish people. Maintenance of healthy soil requires a lot of effort from agriculturalists (Bots and Benites, 2005). Agriculture plays an important role in our country’s Economy. In our country India, it contributes about 16% of total GDP and 10% of total exports (Goyal et al., 2016). However, during recent few years, pollution is posing a major threat to this growing agricultural development. It is caused due to rapid urbanization and industrialization; leading to contamination of agricultural lands with increasingly contaminated by organic, inorganic, and metallic pollutants (Pandey et al., 2019).

Heavy metal contaminated soil has become an environmental concern worldwide (Hasan et al., 2019). They are added from both natural as well as manmade sources. Natural sources include forest fire, volcanic eruption, wind erosion, and fossil fuels. Anthropogenic sources of heavy metals are thermal power plants, smelters, mines, refiners, foundries (Garty, 2001; Nagajyoti et al., 2010; Tangahu et al., 2011; Jaishankar et al., 2014a,b). These metals are not affected by any chemical method or microbial degradation and get accumulated for longer period of time, thus posing various risks to human health and environment (Bolan et al., 2014). Also, crop production is equally affected by heavy metal pollution (Bhat et al., 2019). Some of the toxic heavy metals include Aluminum (Al), Copper (Cu), Cadmium (Cd), Chromium (Cr), Lead (Pb), Manganese (Mn), Zinc (Zn) (Mahar et al., 2016; Bhat, 2019). These metals act as phytotoxins and affect various physiological and morphological processes of plants like photosynthetic rate, growth rate, nutrient imbalance, stomatal movement. Inclusion of these heavy metals into the food chain can risk the food chain contamination (Blaylock and Huang, 2000). To cope with this problem, various methods such as chemical amendments and bioremediation has been used in most sustainable ways. Bioremediation has acquired attention over recent years and has emerged as eco-friendly approach that uses natural abilities of living beings for restoration of polluted land (Vidali, 2001; Singh Ajay, 2004; Ramchandran et al., 2013; Vijayalakshmi et al., 2018). It is an umbrella term that includes phytoremediation, biodegration, bioventing, bioleaching.

1.2 Phytoremediation

The term phytoremediation was first used in 1983 (Ashraf et al., 2020). It is defined as application of plant-controlled interaction with groundwater and organic and inorganic molecules at contaminated sites to achieve site-specific remedial goals (Landermeyer, 2011). It is also called as botanoremediation, agroremediation, or green remediation (Mahar et al., 2016). It is a green approach for reducing the pollution load of environment in which plants absorb certain toxic metals and toxic chemicals through their roots and transport them in various plant parts in less toxic forms (Schnoor et al.,1995). Phytoremediation includes phytoextraction, phytostabilization, phytodegradation, rhizodegradation, and phytovoltization (Pandey et al., 2019). Among the various techniques of phytoremediation, phytostabilization, and phytoextraction are most preferable. The phenomenon of phytoremediation involves extraction of toxic elements from the soil in the plant body where they are converted into lesser toxic forms without contaminating the food chain (Pandey et al., 2019).

1.3 Mechanisms of phytoremediation

1.3.1 Phytoaccumulation

Phytoaccumulation, also known as phytoextraction or phytosequestration, involves absorption of the contaminants by plants from contaminated soils along with water and other mineral nutrients required for their growth (Muthusaravanan et al., 2018). The absorbed contaminants get accumulated in roots, leaves, shoots, and other parts of the plant without being destroyed (Rashid et al., 2014). These processes are being mostly used for radionuclide and metals (Hossner et al., 1998). Aquatic macrophytes have 1,00,000 times greater capacity for accumulating heavy metals than the quantity of the associated water. Aquatic plants such as Centella asiatica and Eichhornia crassipes have the potential to accumulate different amount of copper from the contaminated areas (Mokhtar et al., 2011). These plant species are preferably grown in wetlands due to their fast growth rate and phytoaccumulation properties (Rai, 2008a, b). Nearly 97.3% and 99.6% of Cu had been found to be removed by Eichhornia crassipes and Centella asiatica, respectively (Mokhtar et al., 2011).

1.3.2 Phytostabilization

It is a process where certain plants are used to restrict the contaminants on the surface of contaminated sites. The mobility of contaminants is restricted by roots and root hairs either by accumulation into root surface or within the rhizosphere (Berti and Cunningham, 2000; Munshower et al., 2003; Mendez and Maier, 2008). It involves the immobilization of the contaminants, restricts their entry into the food chain, and thus lessens their chance of availability to other life forms. Phytostabilization restricts the movement of contaminants within the rhizosphere of the plants and thus the aerial parts of plants are protected from the entry of any contaminants (Berti and Cunningham, 2000; Alkorta et al., 2010). It helps to re-establish growth of certain tolerant plant species at contaminated sites with high metal concentrations where the possibility of natural vegetative growth is not feasible (Regvar et al., 2006). In order to limit the relocation of various metal contaminants by rain, wind, and leaching into the groundwater, various metal-tolerant plant species are grown on the contaminated sites which act as phytostabilizers. In addition to phytostablizers, there is diversity of microbiota associated with these plant species which assists their metal tolerance efficiency and growth. They also lessen the metal absorption and their transportation to aerial parts of plants by restricting their movement in the root surface area of the plant (Muthusaravanam et al., 2018). The plant-associated microbiota uses different mechanisms to prevent the metal adsorption in plants (Rouch et al.,1995; Cabot et al., 2019). These microbes restrict the heavy metal uptake by the following mechanisms:

i. The permeability barrier present outside the cell prevents metal entry into the cell.

ii. By supporting to extracellular polymers.

iii. By detoxifying the heavy metals to chemically less active forms.

The soil microbes play a significant role in the amplification of phytostabilization. Some beneficial microbes such as Rhizobium and Endophytes help in phytoremediation process by restricting the movement and rate of accumulation of heavy metal (Ma et al., 2011).

1.3.3 Phytovoltilization

Phytovolatilization is the absorption of the contaminant by the plants and release the contaminant in less toxic gases form to the atmosphere (Moreno, 2004a). Phytovolatilization is a phytoremediation strategy in which certain plant species grown in the metal contaminated sites uptake the metal contaminants, convert them in less toxic volatile form, and then release into the atmosphere by the process of transpiration (Yan et al., 2020).This method can be used for detoxification of various organic pollutants and some heavy metals like As, Se, and Hg (Muthusaravanan et al., 2018). Once converted to gaseous form, there is least chance of these metal contaminants to get redeposited at or near the polluted sites. Hence this approach can be considered as permanent solution for the detoxification of toxic heavy metals (Prabha et al., 2007). Se being analog to S is converted to dimethyl selenide by plant enzymes. Dimethyl selenide being less toxic is vent out in the atmosphere in gaseous form (De Suza et al., 2000). As the phytovoltization involves conversion of contaminated heavy metals into volatile compounds, there is no trace of contaminants at any other parts of plant (Jabeen et al., 2009).

1.3.4 Phytodegradation

It is also called phytotransformation. Phytodegradation is the breakdown of contaminants absorbed by the plants either through the metabolic processes or through the action of enzymes produced within the plants (Muthusaravanan et al., 2018). During this process the contaminants are degraded into simpler forms which are used by the plant for its faster growth. Phytodegradation involves the breakdown of various organic and inorganic compounds, pesticides, and chlorinated solvents (Newman and Reynolds 2004). Phytodegradation brings about changes in plants. Phytodegradation capability of plants is affected by its pollutants uptake efficiency, concentration of pollutants in the soil and the water (Muthusaravanan et al., 2018). Some of the plants with greatest phytoremediation qualities are Myriophyllum aquaticum, Brassica juncea, Colocasia esculenta L. Schott, Canna glauca L., Arundo donax L., and Liliodendron tulipifera (Karennlampi et al., 2000; Rajkaruna et al., 2006; Jomjun et al., 2010; Mirza et al., 2011).Industrial wastewater pollutants can be treated economically by the process of phytodegradation by water hyacinth. This aquatic plant species can be used for the treatment and eventually degradation of industrial wastewater pollutants (Paz-Alberto and Sigua 2013). Ethion present in water hyacinth can be reduced by 75%–80% in roots and 50%–90% in stems when the plant is grown in ethion-free culture (Muthusaravanan et al., 2018).

1.3.5 Rhizodegradation

It is also called as phytostimulation. This process involves the degradation of toxic organic pollutants by the activity of microbes within the rhizosphere (Mukhopadhyay and Maiti, 2010). Rhizospere is defined as the area of soil (about 1 mm) that immediately surrounds the root and is inhibited by the rich diversity of microbes that are influenced by root secretions (Pilon-Smils, 2005). Within the rhizosphere, the activity of soil microbes is influenced in the following ways:

i. Root secretions contain different amino acids and sugars that provide important nutrients to indigenous microbes.

ii. Roots assure the oxygen supply in rhizosphere for the aerobic respiration of microorganisms.

iii. Roots biomass increases the amount of organic carbon in the soil as a source of food to the soil microbes.

iv. Mycorrhizal fungi associated with roots degrade some compounds. Degradation of such compounds cannot be achieved by bacteria.

v. Plants also furnish site for increasing microbial biomass and root microbial community (Yadav et al., 2010).

Numerous plant species have been used for the rhizodegradation strategies. Among them, legumes and grasses are known to have higher efficiency (Vazquez-Luna et al., 2015). Rhizosphere-associated microbes are also known to enhance the degradation of contaminants by a symbiotic relation with plants. Plants secrete various exudates such as flavonoids, carbohydrates, and amino acids that are known to promote the microbial activity by 10–100 times (Weller and Thomashow, 2007). In addition to these exudates, plants discharge certain enzymes in the soil that can degrade soil pollutants (Liu, 2013).

1.4 Selection of plant species for phytoremediation

Remediation of soil using plants has major future potential. This green approach of using plants for the treatment of various pollutants can be used for resettlement of contaminated sites that can further be used for agriculture. However, only those plants that have high tolerance for contaminants can be used for this purpose. Phytoremediation efficiency of plant species depends on the following factors:

a. They have the adaptability to the contaminated areas.

b. They have the ability to uptake and tolerate the contaminants in different plant parts.

c. They have the ability to extract the concerned pollutants and degrade the accumulated contaminants either in less toxic forms or in volatile gases. The later are released into the atmosphere by the process of transpiration via leaves.

d. Such plant species should be best adapted to the local climatic conditions.

e. The root system of plants should be deeply seated in the soil.

f. Growth rate of plants should be fast.

g. Plantation and maintenance of these plants should be easy and cost-effective.

Plants, which are selected for the process of Phytoremediation, have to be maintained properly. They need a good quality of fertilizers, replantation, pruning, harvesting, and frequent observations (Sas-Nowosielska et al., 2004). Plant species such as Alpine pennycress and alyssum act as hyper-accumulators and are usually used for remediation of metal contaminated soil (Prasad and De Oliveira Freitas, 2003). Remediation of surface soil can be achieved by certain Brassicaceae members such as alfalfa, mustard, and some grasses (Yanqun et al., 2005). Remediation of contaminants in groundwater can be achieved by woody species that have deep root system, faster growth rates, and rapid rate of transpiration, such as hybrid poplars, cottonwood and willows. They can also be used in hydraulic control (Nyer and Gatlif, 1996).

1.5 Metallophytes

Metallophytes are the plants that can withstand heavy metal contaminated soil (Sheoran et al., 2011). Majority of these plants belong to family Brassicaceae and can be group into three categories (McGrath et al., 2002; Bothe, 2011).

Metal excluders: This class include plants that can absorb heavy metals from the contaminated soil and accumulate into their roots. They prevent their transport to the aerial parts of plants (Malik and Biswad, 2012).

Metal indicators: Metal indicators uptake the contaminated metal from soil and accumulate into their above-ground parts (Sheoran et al., 2011)

Metal hyperaccumulators: They accumulate at the minimum 100 mg/kg Cd and As, 1000 mg/kg Co, Cu, Cr, Ni, and Pb and 1000 mg/kg Mn and Ni (Watanebe, 1997; Ravees and Bakr, 2000). They have a slow growth rate and less biomass production.

List of some plants involved in phytoremediation

Vetiver (Chrysopogon zizaniodes or Vetiveria zizanoides)

Family: Poaceae.

It is grown in wide ranges of salinity, acidity, and presence of heavy metals. It is used in the process of phytostabilization for sequestering Pb in roots (Xia, 2004). Formation of complexes between phytochelatins such as EDTA and Pb in Vetiver has been worked out by Andra et al. (2009). The complexes so formed make Vetiver a Lead tolerant species. Lead can also enhance the oil content of Vetiver (Rotkittikhum et al., 2010).

Lemongrass (Cymbopogon flexuosous or C. citrates)

Family: Poaceae.

Lemon grass uses Cadmium as inducer of Proline (Handique and Handique, 2009) and young leaves are major accumulators of proline. Lemongrass also help in photostabilization of toxic Cu tailings (Das and Maiti, 2009). It can also adsorb Pb (II) ions from aqueous solution (Sobh et al., 2014). Treatment of wastewater containing Pb(II) ions can be done by this low-cost and eco-friendly method. Factors such as translocation and bioconcentration proved that lemongrass acts as a phytostablizer of Cu, Fe, and Mn in roots and phytoaccumulator of Al, As, Cd, Cr, Pb, Ni, and Zn (Gautam et al., 2017).

Citronella (Cymbopogon winterianus Jowitt.)

Family: Poaceacae.

Citronella shows the highest accumulation of Cd in roots, followed by stem, leaf sheath. and leaves (Borunah et al., 2000). It can act as a potential phytostabilizer of heavy metals in contaminated area.

Palmarosa (C. martini)

Family: Poaceacae.

It shows phytostabilization potential in heavy metal rich sludge amended soil. Uptake of heavy metals is found in the following order Cr> Ni> Pb> Cd in both roots and shoots (Pandey et al., 2019).

Geranium (Pelargonium sps.)

Family: Geraniaceae.

Geranium can uptake high amount of lead in its biomass (Krishna Raj et al., 2001). Krishna Raj et al. registered a patent in which geranium was found as an effective hyper accumulator in multi-metal contaminated soil. The scented geranium can accumulate a greater amount of Cd and Ni because of different detoxification mechanisms (Dan et al., 2000) like keeping up a proficient photosystem II action, confining harm to photosynthetic mechanical assembly by metal particles, etc. However, it is vulnerable to toxicity of Cu followed by Cd, Ni, and Pb for herb, oil yield, and aggregation of metals in plant parts (Chand et al., 2016).

Mint (Mentha sps.)

Family: lamiaceae.

Menthe sps. Phytostablize the heavy metals when grown in contaminated areas and accumulated the respective toxic metal in roots with least transportation to the aerial plant parts (Pandey et al., 2019). It can survive on heavy metal contaminated soil without showing any toxicity symptoms by using of vermicompost or organic matter (Chand et al., 2012). It act as nonhyper accumulator of Cr and Pb (Prasad et al., 2010).

Basil (Ocimum sps.)

Family: Lamiaceae.

Although, it has good potential of phytoremediation, but the plants used should not be used for consumption to protect the food chain from contamination (Pandey et al., 2019). Due to hyperactivity of antioxidant defense system, it has tolerance to Chromium induced oxidation stress (Rai et al., 2004).

Lavender (Lavandula sps.)

Family: Lamiaceae.

It is a potential accumulator of Pb, Cd, and Zn (Angelora et al., 2015). A study done by Zheljazkov and Astatkie (2011) reported no metal contamination in lavender inflorescence or lavender oil, when grown in contaminated soil.

1.6 Advantages of phytoremediation

Some of the advantages of phytoremediation are:

1. It is widely accepted technique due to its practical application in the field (Marmiroli and McCutcheon, 2004; Watt, 2007).

2. It is the solar-driven process as it involves plant remediation of polluted soil. No extra energy is utilized during this process (Ali et al., 2013).

3. It is relatively low-cost and economical method and hence cost-effective (Cornish et al., 1995).

4. Although the contaminated plants are not fit for use, the ash formed from these plants contributes approximately 20–30 tons per 5000 tons soil (Ghosh and Singh, 2005).

5. Plantation of metal-tolerant species on the contaminated sites also prevents the water and wind erosion of soil (Cunningham et al., 1995).

6. Residues of these plants are metal-rich and is recyclable and can be used for various purposes.

7. It also helps in eradication of secondary water and air-born wastes (Lili and Hui, 2007).

1.7 Limitation of phytoremediation

Some of the limitations of this technique are:

1. Due to shorter root system, it can restore the polluted soil and groundwater only near the surface (Padmavthiamma and Li, 2007).

2. Phytovoltilization transfers soil and groundwater pollutants into the air (Sakakibara et al., 2010).

3. It results in contaminated plant and plant products, which are not edible (Mejare and Bullow, 2001).

4. There is incomplete removal of toxic substances from the bioremediated areas (Garisu et al., 2002).

5. There is a risk of food chain contamination (Arthur et al., 2000).

6. It is time-consuming and lengthy process, which takes several growing seasons to restore the contaminated area (Stomp et al., 1994).

1.8 Future prospects and conclusions

Development comes with the man-made hazards and degradation of natural resources. One of these natural resources is soil, which is degrading every day. Restoration of healthy soil is key factor for the survival of life on earth. However, the present soil protections are not sufficient to achieve the sustainable soil management. Remediation of environment from various toxic metals can be achieved by many ways including phytoremediation. Moreover, the phytoremediation is cost-effective and eco-friendly. Plant species surviving in the contaminated soil have endurance to the prevailing stress due to presence of heavy metals. Such plants can be used to fulfill the objectives of pollution attenuation and biomass productivity. The rehabilitation of the polluted sites can be achieved by increasing the number of metallophytes at the abandoned mining sites and contaminated soils. They act to remediate soils in future without using artificial treatments. The use of perennial and annual metallophytes can provide a sustainable amount of organic matter and nutrients recycling. The only requirement, in this case, is proper information about the plants growing on metal contaminated soils.

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2

Background level, occurrence, speciation, bioavailability, uptake detoxification mechanisms and management of Si-polluted soils

Deepi Dekaa, Bindu Yadavb, Chhayac, Pratibha Yadavd, and Om Prakash Narayane

a Biological Sciences Division, Branch Laboratory Itanagar, CSIR North-East Institute of Science and Technology, Naharlagun, India

b School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India

c Department of Civil and Environmental Engineering, Indian Institute of Technology, Patna, India

d Jaypee Institute of Information Technology (JIIT), Noida, Uttar Pradesh, India

e BME Department, Tufts University, Medford, MA, United States

2.1 Introduction

Silicon (Si) is the second most abundant element in the earth’s crust in the form of quartz, alkaline, and aluminum silicates that accounts for 28% in total. It occurs ubiquitously in all organisms including, plants, animals, humans, and the overall ecosystem and so-termed as multi-talented quasi-essential element. It is regarded as nonessential elements for plant nutrition, but plays a pivotal role in its growth and defense mechanisms when utilized in plant-available forms (PAF) like, silicic acid or mono silicic acid [Si(OH)4 or H4SiO4] (Vasanthi et al., 2012; Zargar et al., 2019; Guerriero et al., 2020). Both monocot and dicot plants utilize the available silcon through the roots using the different influx and efflux Si-transporters and get deposited on the epidermal layer, vascular bundles, bulliform cells, fused cells or prickle hairs in the form of phytoliths or plant opal (amorphous silica) in abundance during their reproductive period (Vasanthi et al., 2012; Babu Rao and Susmitha, 2017; Zargar et al., 2019). Plants show their defense mechanism against abiotic stress by creating a barrier in root uptake and immobilization of metalloids in the rhizosphere by silicon. This is followed by detention of elements in the apoplasm of roots that might provide further increased in resistance and vigor (Vaculík et al., 2020). The knowledge of the concentration of silicon present in the food items is limited. Presence of the bioactive benificiery element silicon in diary products provides value addition, provided camel milk to contain the highest amount of silicon followed by goat, cow, and buffalo milk. The concentration of silicon is found to be raised further in fermented products, like yoghurt compared to cheeses and raw milk (Ahmed et al., 2017). Common dietary sources of silicon includes-beer, red wine, raisins, green beans, high-bear cereal, whole grain bread, mineral water, and brown rice with husks (Price et al., 2013). Scientific studies regarding the biological importance of silicon have received increased attention in recent times. It is considered as the third most abundant trace element in the human body contributing in improving immune response, neuronal, and connective tissue health, as well as improving skin strength and elasticity, hair benefits, bone formation, and healing (Landsdown et al. 2007; Nielsen et al., 2014; Farooq and Dietz, 2015; de Araújo et al., 2016; Dong et al., 2016). When silicon combined with carbon, hydrogen, and oxygen, it plays a significant role in medical applications for the treatment of renal, cardiovascular, bone metabolism, and breast implants (Natarajan et al., 2017). Silicon stimulates the optimum synthesis of collagen Type 1 (COL-1) and osteocalcin in human osteoblast-like cells through the bone morphogenetic protein-2 (BMP 2)/Smad1/5/runt-related transcription factor 2 (RUNX2) signaling pathway (Dong et al., 2016). The application of silicon quantum dots (SiQDs) in biomedical research is worth mentioning. They are being explored in the field of disease diagnosis and therapy via imaging, biosensing, or drug delivery purposes as their sizes falls in the nano range of around 4 nm co-doped with boron and phosphorus (Belinova et al., 2018; Qui et al., 2019). The availability of silicon in the overall ecosystem is very crucial as its presence regulates the functioning of the ecosystem through the mechanism of silicon cycle (Schaller et al., 2021). Silicon retained by plants in the biogeochemical cycle during the time of ecosystem retrogression facilitates in sustaining the terrestrial cycle benefiting the plants with silicon in poor environmental conditions (Tombeur et al., 2020). In the plant ecosystem, the contribution of silicon is consistent and considered as an important element in the functional ecosystem in providing strength to the plant against biotic and abiotic stresses (Cooke et al., 2011; Narayan et al., 2017; Yadav et al., 2020; Yadav et al., 2021a; Yadav et al., 2021b). It was hypothesized that the silicon present in roots can potentially defend the belowground herbivores that paves the way for its agricultural and ecological implications (Hartley et al., 2016; Frew et al., 2016). Study on temperate forest ecosystem revealed that the involvement of biological processes including, fine roots of trees in the sulfur cycle is predominant than that of the geochemical processes (Turpault et al., 2018; Narayan et al., 2020; Narayan et al., 2021; Narayan et al., 2022). Multiple benefits of silicon in plants are summarized in Fig. 2.1, as a diagrammatic presentation.

Fig. 2.1 Diagram highlighting multiple benefits of Silicon in plants.

2.2 Background level of silicon

Silicon in soil occurs in different fractions, mainly as, solid, liquid, and adsorbed phases distributing in the rocks (23%–46.5%), petrocalcic horizon (~8%), and very less in highly weathered oxisols. In general, the silicon content of soil is between 50–400 g/kg of soil. While the exchangeable portion of silicon ranges from 16.05 to 36.89 mg/kg of soil, that is highly influenced by pH content (Szulc et al., 2015; Sirisuntornlak et al., 2020). Plant requires silicon in trace amounts for its proper functioning in the environment. Structural silicon aids in the growth and development of plant by protecting against both ­abiotic and biotic stresses providing the overall strength (Zellner et al., 2011; Meharg et al., 2015). Under saline conditions, the presence of silicon balances the physiological processes of plants by decreasing the transpirational bypass flow (Shi et al., 2013). Increase in the level of silicon facilitates to cope up with mineral deficiency as reported in soybean (Glycine max L.) plants (Pascual et al., 2016). In the Grey forest soil of Russia, it was found that 40–80 kg of silicon is removed ha−1 from the biological silicon cycle annually (Bocharnikova et al., 2012). The dynamics of silicon in the higher trophic levels is primarily regulated by soil–plant silicon cycle. In the soil–plant system, the original source of dissolved silicon (DSi), i.e., H4SiO4 is the weatherable lithogenic silicates (LSi). DSi can be absorbed by plants or other heterotrophs, leached out to the hydrosphere, or it may involve itself in the synthesis of secondary clay minerals or absorbed on oxide surfaces. Whereas plant silicon (PSi) or phytogenic silicon (PhSi) may in turn contribute in the formation of DSi pool (Cornelis et al., 2016). The overall biogenic silicon (BSi) present in the terrestrial ecosystem is about 85 Tmol of which around 35% is utilized by agricultural crops annually (Carey et al., 2016). acid takes place from lower to upper horizon by the process of adsorption by plants and returning back the phytoliths through the plant litter into the soil (Bocharnikova et al., 2012; Haynes, 2014; Singh et al., 2020). It has been recognized that phytogenic cycling of silica is the key determinant for the silicon concentrations in the soil (Haynes, 2014). Silicon cycle in the ecosystem provides valuable insights in the carbon sequestration process through the regulation of different biogeochemical cycles, including, phytoliths dynamics, root uptake, weathering and enhancing the organic carbon of soil (Song et al., 2014). In the different trophic levels from terrestrial to aquatic ecosystem the biogenic silicon acts as a linking factor of the global silicon and carbon cycle by controlling the silicon fluxes (Puppe,