phytoremediation of arsenic chloride by indian mustard - CIBTech

Indian Journal of Fundamental and Applied Life Sciences ISSN: 2231-6345 (Online)An Online International Journal Available at http://www.cibtech.org/jls.htm2013 Vol. 3 (1) January-March, pp.184-191/Selvaraj et al.Research ArticlePHYTOREMEDIATION OF ARSENIC CHLORIDE BY INDIANMUSTARD (BRASSICA JUNCEA)K. Selvaraj, R. Sevugaperumal and * V. Ramasubramanian*Department of Botany, Ayya Nadar Janaki Ammal College (Autonomous), Sivakasi* Author for CorrespondenceABSTRACTGrowth performance, Arsenic chloride (AsCl 2 ) accumulation, translocation and mobility of Arsenicchloride form soil to root and leaves were studied in co-cultivated hyperaccumulator (Brassica juncea Hk.F. & T.) and hypoaccumulator (Abelmuscus esculentus L.) at various levels of Ascl 2 treatments (2mM,4mM, 6mM, 8mM and 10mM). B.juncea accumulated fourfold and fivefold Ascl 2 in roots, shoots andleaves, respectively than Abelmuscus esculentus. A.esculentus seedlings when cultivated alone were seensensitive to Ascl 2 with decrease growth, poor values of Accumulation factor, translocation factor andmobility of metal. But the same plant when co-cultivated with Brassica juncea there is no toxicitysymptoms and reduction of growth, values of Accumulation factor, translocation factor and mobility ofmetal. This is well understand that Brassica juncea showing higher accumulation of As, moretranslocation of As from root to shoot and good mobility of Ascl 2 was increased form level 1 to level 3, Itwas revealed that the accumulation of Ascl 2 was more in root and shoot of B.juncea than A.esculentus. Itis inferred from the present study that A.esculentus is a hypoaccumulator and is sensitive to Arsenicchloride. When co-cultivated with Brassica juncea. Showing less of metal toxicity because Brassicajuncea being hyperaccumulator of Arsenic chloride, accumulate more metal and save Abelmuscusesculentus.Key Words: Hyperacumulator, Arsenic Stress, Accumulation Factor, Translocation Factor, MobilityIndexINTRODUCTIONPhytoremediation is the use of plants to treat/clean contaminated sites (Schnoor et al., 1995; Salt et al.,1998; Meagher 2000; Suresh and Ravishankar 2004 and Lal and Srivastava, 2010) and it can be definedas the use of green plants to remove pollutants from the environment or to render them harmless (Bertiand Cunningham, 2000). It is also referred to as green technology and can be applied to both organic andinorganic pollutants present in soil (solid substrate), water (liquid substrate) or the air (Gratao et al.,2005). Phytoremediation takes advantage of the natural ability of plants to extract chemicals from water,soil and air using energy from sunlight. It’s some of the advantages are that it is less expensive, is passiveand solar driven, has high public acceptance, retains topsoil, and has less secondary waste generation. Inthis respect, plants can be compared to solar driven pumps capable of extracting and concentrating certainelements from their environment (Salt et al., 1995). This technology is being considered as a new highlypromising technology for the remediation of polluted sites.Arsenic (As) is an ubiquitous trace metalloid found in all environmental media. Its presence at elevatedconcentrations in soils derives from both anthropogenic and natural inputs. Arsenic-contaminated soils,sediments, and sludge are the major sources of arsenic contamination of the food chain, surface water,groundwater, and drinking water (Frankenberger and Arshad, 2002). Arsenic is a non-essential element inplants and animals, but it has an affinity for biological material, and can be detected in trace amounts invirtually all living organisms at low concentrations as is tolerated by most organisms.Current remediation strategies of heavy metals is primarily based on physicochemical technologies whichare meant primarily for intensive in situ or ex situ treatment of relatively highly polluted sites, and thusare not very suitable for the remediation of vast, diffusely polluted areas where pollutants only occur at184

Indian Journal of Fundamental and Applied Life Sciences ISSN: 2231-6345 (Online)An Online International Journal Available at http://www.cibtech.org/jls.htm2013 Vol. 3 (1) January-March, pp.184-191/Selvaraj et al.Research Articlerelatively low concentrations and superficially (Rulkens et al., 1998). Phytoremediation appears as a validoption since it is best suited for the remediation of these diffusely polluted areas and at much lower coststhan other methods (Kumar et al., 1995). The idea of using plants to remove metals from soils came fromthe discovery of different wild plants, often endemic to naturally mineralized soils that accumulate highconcentrations of metals in their foliage (Baker, 1987; Raskin et al., 1997).In the present study it is aimed to analyse the impact of arsenic chloride on the growth and metalconcentrations of Abelmoschus esculentus, L. (hypoaccumulator) and hyperaccumulator plants Brassicajuncea, Hk. F. and T. it was aimed to analyse the role of hyperaccumulator in metal stressed condition.MATERIALS AND METHODSSeeds of Abelmoschus esculentus, L. Brassica juncea, Hk. F. & T. were procured from local seed centre,Sivakasi. Abelmoschus esculentus, L. Var. S7 (Family Malvaceae) was chosen as experimental plant,whereas the Brassica juncea, Hk. F. & T. (Family Brassicaceae) was chosen as hyperaccumulator plantsfor this study. The effect of various concentrations of arsenic chloride on the morphometric characters,accumulation factor, translocation factor and mobility index were analyzed on the selected plants.Phytoremediation TreatmentHeavy metals stress on hypoaccumulatorTreatment with heavy metal arsenic was given separately for the experimental plants withdifferent concentration as 2mM, 4mM, 6mM, 8mM and 10mM (w/v) in five replicates. The aqueoussolutions of heavy metal were applied in the soil at the time the first pair of leaves developed. Then theplants were watered with the respective concentration of metals on alternate days. A set of plants withoutheavy metal treatment were also maintained as control. Ten surface sterilized seeds of Abelmoschusesculentus, L. were sown uniformly in all pots for the experimental purpose. Morphometric charactersand metal concentration in plants such as accumulation factor, translocation factor and mobility indexwere analysed on the 35 th day after planting (DAP).Co-cultivate the hypoaccumulator and hyperaccumulatorTen surface sterilized seeds of both Abelmoschus esculentus, L. (hypoaccumulator) and Brassica juncea,Hk. F. & T. (hyperaccumulator) were sown uniformly in all pots. Treatment with heavy metal arsenic wasgiven separately for the experimental plants with different concentration as 2mM, 4mM, 6mM, 8mM and10mM (w/v) in five replicates. Morphometric characters and metal concentration in plants such asaccumulation factor, translocation factor and mobility index were analysed on the 35 th day after planting(DAP).Morphometric ParametersFor all the morphometric characteristics, the seedlings numbering ten have been taken from bothexperimental and control sets and the results indicate the average of ten seedlings along with theirstandard error.Accumulation Factor (AF)The Accumulation Factor (AF) was considered to determine the quantity of heavy metalsabsorbed by the plant from soil. This is an index of the plant to accumulate a particular metalwith respect to its concentration in the soil and is calculated using the formula (Ghosh and Singh,2005 and Yoon et al., 2006):MetalConcentrationintissueofwhole plantAccumulation Factor (AF) =Initialconcentrationofmetal in substrate(soil)Translocation Factor (TF)To evaluate the potential of plant species for phytoextraction, the Translocation Factor (TF) wasconsidered. This ratio is an indication of the ability of the plant to translocate metals from theroots to the aerial parts of the plant (Mellem et al., 2009). It is represented by the ratio:185

Indian Journal of Fundamental and Applied Life Sciences ISSN: 2231-6345 (Online)An Online International Journal Available at http://www.cibtech.org/jls.htm2013 Vol. 3 (1) January-March, pp.184-191/Selvaraj et al.Research ArticleTranslocation Factor (TF) = Metalconcentrationin stems leavesMetelconcentration in rootsMobility Index (MI)Mobility Index (MI) was considered to determine the biomobility and transport of heavy metalsin different plant parts. The whole experiment was divided into three categories: Level 1 (Soil –Roots), Level 2 (Roots – Stems) and Level 3 (Stems – leaves). It was calculated by the methodsof Nirmal Kumar et al., (2009)Mobility Index (MI) = Concentrat ionof metalinthereceivinglevelConcentrationofmetalinthesourcelevelRESULTS AND DISCUSSIONThe results on the effect of arsenic chloride on the morphometric characters of co-cultivatedhypoaccumulator Abelmoschus esculentus, L. with hyperaccumulators Brassica juncea, Hk. F. & T. hasbeen presented in the Figure 1. To evaluate the heavy metal accumulation in the plant tissue, to find outthe potential of plant species for phytoextraction and for transport of heavy metals for soil to leaf werefound out through the accumulation factor (AF), translocation factor (TF) and mobility index (MI) on theeffect of arsenic chloride on co-cultivately grown Abelmoschus esculentus, L., with Brassica juncea, aretabulated in tables 1 and 2.Phytoextraction is a soil remediation technology that makes use of plant species to extract metals fromcontaminated soils. When using non-hyperaccumulators as phytoextractors, one of the greatest factorslimiting the success of this technology is the solubility of metals in the soil solution. Since plants canonly accumulate metals in the labile fraction of the soil, the success of phytoextractionwould be restricted by the unavailability of soil metals. However, some plants can survive and evengrow well when they accumulate high concentration of toxic elements, as is the case of thehyperaccumulator plants. So, the co-cultivation of hypoaccumulator with hyperaccumulator has beenanalysed in this study. Results on the co-cultivation of hypoaccumulator Abelmoschus esculentus, L. withhyperaccumulator Brassica juncea, Hk.F.&T. under the various concentration of arsenic chloride beingdiscussed below.In the present investigation, arsenic chloride has caused considerable reduction on the seedling length andleaf area of hyperaccumulators Brassica. However, was not much reduction in the hypoaccumulatorAbelmoschus compared with plant treated with metal alone. Inhibition of the root and shoot lengths athigher concentration of the metals is due to the high levels of toxicity present in arsenic chloride, whichinterfered and inhibited the uptake of other essential elements like potassium, calcium, phosphorus andmagnesium by the plants (Clarkson, 1985). Lunackova et al., (2003) reported that, the retardation of plantgrowth was due to excess quantities of micronutrients and other toxic chemicals. However, no suchreduction of root and shoot growth was observed in the hypoaccumulator (Abelmoschus). According toKochian et al., (2002) the reduction of root and shoot length may be due to possibly binding andsequestering of metals in their vacuole.The observed pronounced inhibition of shoot and root growth and leaf area is the main cause for thedecrease in fresh weight and dry weight of seedlings. In plants, uptake of metals occurs primarily throughthe roots, so this is the primary site for regulating their accumulation (Rahman et al., 2005). The biomassaccumulation represents overall growth of the plants. In the present investigation the total fresh weight ofhyperaccumulator was gradually reduced with the increase in concentration of metal, but in thehypoaccumulator no reduction was found and the plants were as like as control plants. This may be due tothe removal of metal toxicity by the hyperaccumulator. Similar observation was reported by Quartacci etal., (2005) in phytoextraction of cadmium by the Indian mustard.186

Indian Journal of Fundamental and Applied Life Sciences ISSN: 2231-6345 (Online)An Online International Journal Available at http://www.cibtech.org/jls.htm2013 Vol. 3 (1) January-March, pp.184-191/Selvaraj et al.Research ArticleEFigure 1: Impact of arsenic on the morphometric characteristics after co-cultivation with Brassicajuncea, Hk.F.&T.187

Indian Journal of Fundamental and Applied Life Sciences ISSN: 2231-6345 (Online)An Online International Journal Available at http://www.cibtech.org/jls.htm2013 Vol. 3 (1) January-March, pp.184-191/Selvaraj et al.Research ArticleTable 1: Impact of arsenic chloride concentration in hyperaccumulator (Brassica juncea, Hk.F.&T.) and hypoaccumulator (Abelmoschus esculentus, L.)Accumulation Factor (AF)Translocation Factor (TF)Metal ConcentrationArsenic Stress on After Co–Cultivation Arsenic Stress on After Co–CultivationAbelmoschusAbelmoschusBrassica juncea, AbelmoschusAbelmoschusBrassica juncea,esculentus, L.esculentus, L.Hk.F.&T. esculentus, L.esculentus, L.Hk.F.&T.Control BDL BDL BDL BDL BDL BDL2mM 0.400 ± 0.0027 BDL 1.123 ± 0.0076 0.163 ± 0.0086 BDL 1.096 ± 0.00094mM 0.344 ± 0.0035a * BDL 1.230 ± 0.0034a * 0.162 ± 0.0041a * BDL 1.150 ± 0.0046a *6mM 0.332 ± 0.0076a * 0.021 ± 0.0037a # 1.264 ± 0.0018a * 0.153 ± 0.0018a * 0.090 ± 0.0051a # 1.188 ± 0.0017a *8mM 0.327 ± 0.0016a * 0.016 ± 0.0019a # 1.324 ± 0.0049a * 0.146 ± 0.0033a * 0.076 ± 0.0020a # 1.293 ± 0.0038a *10mM 0.303 ± 0.0013a * 0.014 ± 0.0045a # 1.618 ± 0.0010a * 0.141 ± 0.0074 a * 0.062 ± 0.0032a # 1.428 ± 0.0067a *Values are an average of three observations. Mean ± SE, a – 4mM to 10mM Concentrations compared with 2mM, * Significant (P ≤ 0.05 – Turkey test). # not significantBDL – Below Detectable Level, S – R: Soil to Root, R – S: Root to Stem, S – L: Stem to LeafTable 2: Impact of arsenic chloride concentration in hyperaccumulator (Brassica juncea, Hk.F.&T.) and hypoaccumulator (Abelmoschus esculentus, L.)Mobility Index (MI)MetalConcentrationArsenic Stress onAbelmoschusesculentus, L.Level 1 (Soil to Root) Level 2 (Root to Stem) Level 3 (Stem to Root)After Co–CultivationAbelmoschusesculentus, L.Brassica juncea,Hk.F.&T.Arsenic Stresson Abelmoschusesculentus, L.After Co–CultivationAbelmoschusesculentus, L.Brassica juncea,Hk.F.&T.Arsenic Stress onAbelmoschusesculentus, L.After Co–CultivationAbelmoschusesculentus, L.Control BDL BDL BDL BDL BDL BDL BDL BDL BDL2mM 0.344 ± 0.0073 BDL 0.536 ± 0.0082 0.072 ± 0.0021 BDL 0.448 ± 0.0007 1.673 ± 0.0075 BDL4mM 0.296 ± 0.0086 a * BDL 0.545 ± 0.0049a * 0.069 ± 0.0016 a * BDL 0.479 ± 0.0035a * 1.499 ± 0.0018a * BDL6mM 0.289 ± 0.0011 a * 0.019 ± 0.0034a # 0.551 ±0.0027a * 0.065 ± 0.0007a * 0.073 ± 0.0060a # 0.576 ± 0.0080a * 1.286 ± 0.0046 a * 0.325± 0.0010a * 1.089 ±8mM 0.286 ± 0.0033 a * 0.015 ± 0.0068 a # 0.572 ± 0.0083a * 0.062 ± 0.0075 a * 0.051 ± 0.0029a # 0.630 ± 0.0029a * 1.268 ± 0.0052 a * b * 0.233 ± 0.0012a * 1.398 ±10mM 0.263 ± 0.0074 a * 0.013 ± 0.0046a # 0.740 ±0.0020a * 0.057 ± 0.0012 a * 0.058 ± 0.0087a # 0.684 ± 0.0044a * 1.117 ± 0.007 a * 0.214 ± 0.0018a * 1.446 ±Values are an average of three observations. Mean ± SE, a – 4mM to 10mM Concentrations compared with 2mM, * Significant (P ≤ 0.05 – Turkey test). # not significantBDL – Below Detectable Level, S – R: Soil to Root, R – S: Root to Stem, S – L: Stem to LeafBrassicajuncea,Hk.F.&T.1.053 ±0.00391.062 ±0.0090a *0.0062a *0.0019a *0.0018a *188

Indian Journal of Fundamental and Applied Life Sciences ISSN: 2231-6345 (Online)An Online International Journal Available at http://www.cibtech.org/jls.htm2013 Vol. 3 (1) January-March, pp.184-191/Selvaraj et al.Research ArticleThe accumulation factor and translocation factor of arsenic chloride show a gradual increase in thehyperaccumulator plant with increasing concentration of arsenic chloride but in the hypoaccumulator theaccumulation factor (AF) and translocation factor (TF) were very less even in 4mM concentration ofmetal treatment. Both factors were below detectable level, and coincide with the findings of Ma et al.,(2001). Comparatively low TF values of chromium and high TF values shown by mercury reveal verylow and high translocation of these metals indicating that translocation potential of Brassica diffusa(Raskin et al., 1994).More or less similar results have been reported in the accumulation pattern of heavy metals in Amarantus(Mellem et al., 2012). Those authors suggested that accumulation potential of plants towards heavy metaldepends on the availability of the metals in the soil/ growth media as well as on the plant genotype. But inthe present study, the accumulation factor and translocation factor were less in the hypoaccumulator(Abelmoschus). This may be due to the hyperaccumulator accumulating more metals and leavehypoaccumulator free from metal toxicity.If the accumulation factor (AF) and translocation factor (TF) values are above one, the plant is suitablefor phytoremediation (Reevas and Baker 2000; Yoon et al., 2006) in the present investigation bothaccumulation factor (AF) and translocation factor (TF) values are above one, in the hyperaccumulator(Brassica), it is suggested that they are best suited for phytoextraction of arsenic toxicity.The mobility index (MI) of the studied in Brassica is higher than one for Level 3, and in Levels 1 and 2,the mobility index was more than 0.6, indicates the moderate rate of mobility of metals form soil to roots,higher mobility rate in stem to leaves, and low from roots to stem. Thus, the present results are wellcorroborated with the observations of Hunter et al., (1987a, 1987b, 1987c). In contrary, in thehypoaccumulator (Abelmoschus) These Levels are not noticed, because the hyperaccumulator plantabsorbed the metals freed the hypoaccumulator Abelmoschus. Similar finding were reported by NirmalKumar et al., (2008).Thus, from the above findings it is clear that, the plants Brassica juncea, Hk.F.&T. chosen for the study,are acting as hyperaccumulator. This is proved by the results obtained on accumulation factor (AF),translocation factor (TF) and mobility index (MI) studies. Because of the phytoextraction capability thesehyperaccumulator, the Abelmoschus esculentus, L. (hypoaccumulator) plant could grow well in arsenicstressed environment when it is co-cultivated.Based on the result obtained on accumulation factor (AF), translocation factor (TF) and mobility index(MI), it is suggested that Brassica juncea, Hk.F.&T. is best suited for remediating arsenic contamination.REFERENCESBaker AJM (1987). Metal Tolerance. New Phytologist 106 93-111.Berti W and Cunningham SD (2000). Phytostabilization of metals. In: Phytoremediation of toxicmetals: using plants to clean-up the environment. Editions Raskin I and EnsleY BD John Wiley & SonsNew York.Clarkson DT (1985). Factors affecting mineral nutrient acquisition by plants. Annual Review PlantPhysiolology 36-77.Frankenberger WTJR and Arshad M (2002). Volatilisation of arsenic. In: Frankenberger JR, WT(Edition) Environmental chemistry of arsenic New York: Marcel Dekker 363-380.Ghosh M and Singh SP (2005). A review on phytoremediation of heavy metals and utilization of itsbyproducts. Applied Ecology and Environmental Research 3 1-18.Gratao PL, Prasad MNV, Cardoso PF, Lea PJ and Azevedo RA (2005). Phytoremediaion: greentechnology for the clean-up of toxic metals in the environment. Brazile Journal of Plant Physiolology 1753-64.189

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