Nabin Kumar Dhal

Phytoremediation: A Novel Approach for Utilization of Iron-ore Wastes

Large quantities of iron-ore tailings are being generated annually in the world from mining and processing of iron ores. It has been estimated that around 10-15% of the iron ore mined in India has remained unutilized and discarded as slimes during mining and subsequent processing. Soil contamination resulting from mining activities affects surrounding flora and fauna and presents a large clean-up challenge to the mining industry. Innovative new methodologies have been proposed and among the most promising are those that rely on new phytoremediation technology. In this paper we address and review the status of phytoremediation as a technology to reduce and control contaminated mine wastes. Several different approaches and different plant species are used to remove environmentally toxic metals from mine waste sites. Such approaches have the objective of restoring mining waste sites to human and animal use, or at least, to curtail or eliminate the off-site movement of toxic entities that potentially could reach humans. How well phytoremediation performs as an alternative soil restoration technology depends on several factors, including the composition of soil, toxicity level of the contaminant, degree to which plant species fit natural local growth patterns and type of concentration of metal/contaminant in such plants. Phytoremediation has opened prospects for less costly, yet practicable approaches to clean-up contaminated waste sites, particularly those associated with mineral extraction mining. We discuss several plant species that are capable of phytoextracting and/or phytostabilizing harmful elements from contaminated soil and water; such processes are prospectively effective for addressing waste problems that derive from mining and processing activities, as well as those that derive from mitigating the threat posed by waste that surrounds mining sites. Unfortunately, phytoremediation is still in the embryonic stage, and more research is needed to find the plant species that will be most effective for addressing different mining waste scenarios. Such plants must be able to survive and even thrive in heavily contaminated soil and be able to mitigate the pollutants that exist in the soil in which these plants will grow.

Effects of iron ore tailings on growth and physiological activities of Tagetes patula L.

PurposeOrnamentals can beautify the environment and resolve heavy metal pollution at the same time. Thus, the present study aimed at studying the growth and physiological response of Tagetes patula on iron ore tailings.Materials and methodsPot-culture experiments were conducted to investigate the effect of iron ore tailings both individually as well as in combination with soil (at different proportions) on the growth, pigment production as well as accumulation and translocation of various heavy metals from the tailings.Results and discussionThe results suggested an increase in growth, chlorophyll content, as well as metal accumulation capacity of T. patula with increasing proportion of tailings in the soil. Furthermore, an increase in antioxidant activities in plants grown on tailings as compared to control was observed which suggests plant efficiency to overcome any stress generated due to excess of heavy metals. The order of accumulation of various heavy metals in the plant parts was observed to be Fe > Cr > Zn > Cu > Pb > Ni > Cd. Both bioaccumulation and translocation values were maximum for Fe and minimum for Ni and Cd, respectively.ConclusionsThe overall study clearly suggests plant ability to grow well on the tailings and survive excess of heavy metals present in the tailings. Thus, the plant qualifies well as a potential tool for phytostabilization of iron ore tailings and probably a source of income generation from wasteland owing to its multiple commercial values.

Differences in tree species diversity and soil nutrient status in a tropical sacred forest ecosystem on Niyamgiri hill range, Eastern Ghats, India

We have quantitatively analyzed the tree species diversity with respect to soil nutrient status in three sites of a sacred forest ecosystem of Niyamgiri hill range, Eastern Ghats, India. Extensive field surveys and sampling were conducted in 3 sites of the hill range: Site 1 Pterocarpus dominated forest (PTF) (19°40′02.2″ N and 83°21′23.1″ E), Site 2 Mangifera dominated forest (MAF) (19°40′02.8″ N and 83°21′40.8″ E) and Site 3 Mixed forest (MIF) (19°36′47.1″ N and 83°21′02.7″ E). A total of 28 families, 42 genera, 46 tree species, and 286 individual trees were recorded on an area of 0.6 ha. Tree density varied between 470 and 490 individuals ha−1 and average basal area between 3.16 and 10.04 m2 ha−1. Shannon Index (H′) ranged from 2.34 to 4.53, Simpson’s Index ranged from 0.07 to 0.09, and equitability Index ranged from 0.7 to 1.34. The number of individuals was highest in the girth at breast height (GBH) class of 50–70 cm. The soil nutrient status of the three forest types was related to tree species diversity. The soil pH value of the three sites reflected the slightly acidic nature of the area. Species diversity was positively correlated with organic carbon and phosphorus and negatively with nitrogen, EC and pH. The results of the current study may be helpful to further develop a conservation plan for tree species in tropical sacred forest ecosystems.

PHYTOSTABILIZATION OF IRON ORE TAILINGS THROUGH CALOPHYLLUM INOPHYLLUM L.

The phytostabilization of waste material generated during mining and processing of iron ore through Calophyllum inophyllum L. have been investigated. Iron ore tailings and its varying composition with garden soil were taken to study plant growth, chlorophyll content and metal uptake pattern of Calophyllum inophyllum L. These studies indicate that 100% survival of plant species was noted in all the treatments without any toxicity symptoms. The increase in growth parameters and chlorophyll content along with the high metal accumulation in plant tissues suggests that Calophyllum inophyllum L. may be a potential tool for phytoremediation. The accumulation of Pb (1662 μgm/gm) and Fe (2313 μgm/gm) was observed to be maximum in the plant tissues followed by Cu, Zn, Cr, and Ni. The TF values for most of the heavy metals was observed to be > 1 which indicates that the plant can efficiently translocate these toxic metals to its above ground parts. Removal of more than 30% of the most of the heavy metal like Fe, Pb, and Cu & Zn has been observed in all the treatments during one year of observation. The overall study clearly suggests that the plant can be used as an efficient tool for restoration of mining wastes and other similarly contaminated sites.

Comparative phytoremediation potential of Calophyllum inophyllum L., Bixa orellana L. and Schleichera oleosa (lour.) Oken on iron ore tailings

The present study focused on the comparison of three economically important tree species Calophyllum inophyllum L., Bixa orellana L. and Schleichera oleosa (lour.) Oken, regarding their phyto-stabilisation potential in the presence of iron ore tailings (IOT). Results indicated that Calophyllum showed the best growth on IOT as compared to Bixa and Schleichera. A continuous increase in chlorophyll a, b and total chlorophyll was observed in Callophyllum and Bixa, while in Schleichera it was greater in the freshly treated plants but went on decreasing later. The catalase enzyme activity was observed to be greater in the treated plants compared to their controls in all the three plants. Metal accumulation rate was observed to be maximised in Calophyllum; it accumulated maximum amount of lead (Pb) and copper (Cu) while zinc (Zn) and nickel (Ni) accumulation was maximum in Bixa. Interestingly, both Calophyllum and Bixa accumulated similar and greater amounts of chromium (Cr) than Schleichera. The study revealed that Calophyllum has the most potential for phyto-stabilisation than Bixa and Schleichera.

A REVIEW ON GREEN SYNTHESIS OF GOLD NANOPARTICLES

Nanoparticle technology plays a key role in providing opportunities and possibilities for the development of a new generation of sensing tools. Nanoparticles can be integrated with ligands, imaginable and therapeutic agents and other functionalities for site specific drug delivery and cellular uptake. A simple, green method was developed for the synthesis of gold nanoparticles (GNPs) by reducing chloroauric acid (HAuCl4) with different plant extracts and microbes (such as fungus, bacteria). Gold nanoparticles can be functionalized with protein, peptides and nucleic acidwhich have a great application in drug, gene and protein delivery. The review provides a brief description of green synthesis of gold nanoparticles and its applications.

Enhancement of toxic Cr (VI), Fe, and other heavy metals phytoremediation by the synergistic combination of native Bacillus cereus strain and Vetiveria zizanioides L

ABSTRACT Bioremediation of Cr (VI), Fe, and other heavy metals (HMs) through plant–microbes interaction is one of the efficient strategies due to its high efficiency, low cost, and ecofriendly nature. The aim of the study was to isolate, characterize, and assess the potential of rhizospheric bacteria to enhance growth and metal accumulation by the chromium hyperaccumulator Vetiveria zizanoides. The bacterial strain isolated from mine tailings was identified to be Bacillus cereus (T1B3) strain exhibited plant growth-promoting traits including, 1-aminocyclopropane-1-carboxylate deaminase, indole acetic acid, and siderophores production, nitrogen fixation, and P solubilization. Removal capacity (mg L−1) of T1B3 strain was 82% for Cr+6 (100), 92% for Fe (100), 67% for Mn(50), 36% for Zn (50), 31% for Cd (30), 25% for Cu (30), and 43% for Ni (50) during the active growth cycle in HM-amended, extract medium. Results indicate that inoculating the native V. zizanioides with T1B3 strain improves its phytoremediation efficiency of HMs. The mineralogical characteristics of chromite ore tailings and soil were also confirmed by X-ray diffraction, Fourier Transform Infrared, scanning electron microscope–energy dispersive spectroscopy analysis.

EDTA and citric acid-mediated phytoextraction of heavy metals from iron ore tailings using Andrographis paniculata: a comparative study

An experiment was conducted in the greenhouse to compare the effect of a synthetic chelator, ethylenediaminetetraacetic acid (EDTA), with that of a natural low molecular weight organic acid i.e. citric acid (CA) in enhancing the heavy metal extraction potential of Andrographis paniculata (Burm.f.) Wall. ex Nees from iron ore tailings (IOT). The chelator treatments were applied at doses of 0.05, 0.10 and 1.5 mmol kg−1dry tailings. IOT without any additives were used as control. The effect of IOT (both with and without additives) on growth, photosynthetic pigments (chlorophyll, pheophytins and carotenoids), antioxidant activity, as well as uptake and accumulation of various heavy metals (Fe, Cu, Zn, Ni, Cr, Cd and Pb) were analysed for four months. Results indicated that the total uptake (mass removal from tailings) of metals by A. paniculata was enhanced by the addition of chelators. The heavy metal concentrations in the parts of A. paniculata under all chelator treatments were significantly (p < 0.05) higher than those for the control, as the total concentration of Fe, Cu, Zn, Ni, Cr, Cd and Pb increased from 175.34, 118.72, 110.51, 2.5, 21.9, 1.026 and 10.2 μg g−1, respectively, to 184.17, 161.94, 157.69, 4.41, 26.17, 1.79 and 20.79 μg g−1 in the presence of CA, and 187.04, 176.12, 172.85, 5.44, 28.46, 2.254 and 22.14 μg g−1 with EDTA application even at the lowest dose of 0.05 mmol kg−1. By increasing the doses of EDTA and CA that were applied, we achieved further increased mobilisation of the targeted heavy metals from tailings to the plant roots. Though EDTA was more efficient in mobilising metals from tailings to the plant parts than CA, yet the reduction of plant biomass caused by it (EDTA) also exceeds that caused by the CA. Therefore, (low molecular weight organic acid such as) CA should be preferred during assisted phytoextraction over the synthetic chelator like EDTA which has unacceptable percolation risks associated with it.

Addition of Low-Grade Phosphate Rock for Improvement of Soil Fertility on Plant Models: A Preliminary Case Study

To sustain food production in the course of time and for efficient utilization of available resources, it is essential to approach improved methodologies and techniques for enhancing crop productivity. Commercial agricultural production has achieved this through the external application of synthetic inorganic fertilizers which has some detrimental effects on the soil structure, composition, microflora and additional characteristic properties of soil. The mining and industrial waste is an unwanted by-product of mining. Reusing and recycling of these wastes is possible therefore recovery and recycling is the most excellent environmental resolution to save raw resources and to diminish the number of industrialized waste materials produced, and also control the contamination of the environment. In the present study, an attempt has been made to utilize low-grade phosphate rock as a fertilizer and its effects on soil fertility. The raw phosphate rock samples are subjected to physicochemical test followed by elemental analysis by EDXRF (Energy Dispersive X-ray Fluorescence). The tests confirmed that it is possible to use this raw phosphate rock as fertilizer for plant growth in a simple process. Different soil and plant parameters were measured. Data on pot experiment revealed higher plant growth is in PR amended soil than normal soil. The greatest positive effect on growth was recorded in the treatments that received phosphate rock (8g) per kg of soil. Thus, observations indicated that direct application of this PR could be an alternative, promising technology for simultaneous waste minimization, waste utilization, and improved resource-use efficiency. Article History Received: 17 August 2017 Accepted:12 October 2017

Effects of Chromium Ore Tailings on Growth and Physiological Activities of Mesua ferrea L.

ABSTRACT A greenhouse pot experiment was conducted to evaluate the feasibility of using a native ornamental plant, Mesua ferrea L. as phytostabilizer for chromium ore tailings (COT) and to assess the metal accumulation capacity. Different ratios of soil and COT were taken in pots and sowed with seeds of M. ferrea. Plants were harvested at various intervals and separated into roots and shoots for analysis of metal concentrations and physiological characteristics of the plants. The study revealed that the plant has great tolerance and stronger ability to accumulate Cr. The results suggested an increase in growth, chlorophyll content, antioxidant activities, as well as metal accumulation capacity of M. ferrea with increasing proportion of COT in the soil. This indicates the plants efficiency to overcome any stress generated due to excess of chromium as well as other heavy metals. The order of accumulation of heavy metals was observed to be Fe>Cr>Ni>Cd>Co. The accumulation of Cr was higher in root compared to that in shoot. M. ferrea has found to be potential as a native species candidate for phytostabilization of chromium mine tailings.