Indicator of Bioavailability of Heavy Metals in Phyto-Stabilized ...

Morariu F. et. al./Scientific Papers: Animal Science and Biotechnologies, 2011, 44 (1)Indicator of Bioavailability of Heavy Metals inPhyto-Stabilized Processes of Fly Ash DepositsFlorica Morariu 1 , Smaranda Mâsu 2 , Neculai Dragomir 1 , Valeria Rus 2 , Ligia Demetrovici 2 ,Stela Uruioc 3 , Dumitru Popescu 1 , Adela Jurjescu 11Banat University of Agricultural Sciences and Veterinary Medicine, 300645 - Timisoara, Calea Aradului 119,Romania2National R & D Institute for Industrial Ecology Branch of Timisoara, 300004 – Timisoara, Regina Maria Street 1,Romania3West University of Timisoara, 300251 - Timisoara, Pestalozzi Street no. 16, RomaniaAbstractThe study refers to the assessment of the effectiveness of treatments of topsoil of fly ash from a fresh deposit.Bioavailability reduction of metals: chromium, copper and lead from soil to the plant tissue, for a healthy vegetationcover of a leguminous plant species is aimed. The modification of metal mobility in the top layer of fly ash throughthe use of biosolids (municipal sludge) as organic fertilizers alone or mixed with pillared indigenous tuff is indicatedby a bioavailability index of metal accumulation in plant tissue. This indicator of bioavailability of heavy metals iscalled transfer factor (TF) and is the ratio of metal content in plant tissue Q P mg/kg DM of total metal content in flyash treated or untreated site Q S mg/kg DM TF = Q P /Q S . Transfer factor from soil to plant tissue for chromium andcopper decreases from 0.11 – 0.18 to 0.06 – 0.08 and from 0.28 to 0.03 for lead when treating the top layer of fly ashwith biosolids mixed with pillared indigenous tuff.Keywords: biosolids, fly ash, heavy metals, pillared indigenous tuff, transfer factor.1. Introduction All heavy metals are toxic to plants when presentin soil in larger quantities than those considerednormal. A high concentration of metals can causeoxidative stress, when a series of metabolicprocesses are disrupted. As consequence plantweight and crop are reduced. If plants can toleratehigh amounts of metals in soil and accumulatethese metals in their tissues, these can reach thefood chains where it in turn can cause dysfunctionin organism. If the amount of metals in soil is nottoxic to plants, we can obtain important crops, butthe extent of metal transfer from soil to plantcomes to be toxic to higher organisms. Examplesof such metals are lead, chromium, copper, zinc,and cadmium [1-5]. * Corresponding author: Florica Morariu,0256/277206, florica.morariu@animalsci-tm.roTransfer factor (TF) of metals from soil to plantscan be an indicator of metal accumulation in planttissue. TF defined by J. Freytag, 1986, as the ratioof metal content in plant tissue Q P mg/kg DM tothe total content of metal in treated or untreatedfly ash topsoil Q S mg/kg DM TF = Q P /Q S [6].There was a big difference between the values oftransfer factors for different metals such as Cd,Zn, Pb, etc., of the same plant. Transfer factor forcadmium species of maize was assessed for theentire plant to 0.3. For zinc transfer factor is 0.68for the entire plant, and for lead is a factor of 0.01[7]. The use of organic fertilizers such biosolids,compost, manure and inorganic amendments suchas zeolite type, red mud etc. used to modify soilcharacteristics have demonstrated their ability tochange the bioavailability of metals from soil intoplants [3-4,8].The study aims to assess the influence of biosolidstype fertilizers, amendments of indigenous493

Morariu F. et. al./Scientific Papers: Animal Science and Biotechnologies, 2011, 44 (1)volcanic tuff based on clinoptilolite, and biosolidsmixed with zeolite (indigenous tuff) regarding thedegree of transfer of copper, chromium and leadfrom the fly ash topsoil planted with Onobrychisviciifolia leguminous species. Study of metaltransfer from soil to plant tissue is performed inthe period of plant maturity.deposits of coal combustion in thermal powerplant.The study is carried out in the summer of 2010.Transfer factor is analyzed for metals Cu, Cr, Pband Zn from plant tissues harvested during themature phenophase. Soil sample analysis wasdone to determine copper, chromium, lead andzinc concentrations according to the analysis2. Materials and methodsmethod of ISO 1,1047/99. Soil samplespreparation for analysis was done in accordanceExperimental parcels include: C as a controlparcels, untreated fly ash, C + B fly ash parcelsfertilized with municipal sludge 25t/ha DM(biosolids), C + Ts fly ash parcels treated withpillared tuff, tuff-Aln, in a quantity of 2% andexperimental parcel C + B +Ts fly ash fertilizedwith bio-fertilizer kind organic-zeolite, 25t/haDM. The biosolids used had the followingcharacteristics: total nitrogen 0.53%, 0.75%phosphorus and pH 6.5. Pillared tuff, tuff- Aln isprepared as native volcanic tuff at ECOINDBranch Timisoara according to a patent [9]. Thewith ISO 11,464/98. Heavy metals were extractedfrom the soil samples by heating with Aqua Regiafor 2hrs, at reflux. After interrupting the heat, thesystem was left in stand-by for 16 hrs. Then thesamples were diluted in a flask with deionizedwater to exactly 50 ml. Plant sampling was donein agreement with the standardized methodologyPlant tissues were thoroughly washed withdeionized water to remove any soil particlesattached to plant surfaces. The tissues were dried(105°C) to a constant weight. Plant samples withprecise weight are then brought to 550°C; to thenative volcanic tuff contains up to 70% residual materials 5ml of concentratedclinoptilolite and comes from the Mirsid quarry, hydrochloric acid are added, samples areRomania. The organic-zeolite fertilizer is maintained 30 minutes on the dry sand bath. Aftercomposed of mixed biosolids with pillared tuff,tuff-Aln, 2%.filtering those in a paper filter with small porosity,were taken to a calibrated flask with hydrochloricThe cultivated species is the leguminous acid 1:1 solution. Plant and soil extracts analysisOnobrychis viciifolia species. Experimental plotarea was 3 m 2 (1.5m x 2 m) and width of the alleybetween the experimental variants was 1 m. Theexperimental location was situated on fly ashwas done using a spectrophotometer, VarianSpectra AASIn Table 1, metal concentrations are presented inthe top layer of untreated and treated experimentalparcels were seeded with plants.Table 1. Metal concentrations in the top layer of untreated and treated experimental parcels sownOnobrychis viciifolia speciesNo.Experimental parcelsContent on heavy metals mg/kgDMCu Cr Pb Zn1 C 77.6 93.5 7.4 54.74 C+B 74.1 77.9 9.0 70.93 C+ Ts 71.6 74.4 7.6 60.06 C+B+Ts 81.6 103.1 7.7 70.6The amount of Cr and Cu from the topsoil parcelsranges between the alert threshold values for lesssensitive soil, and the amount of Pb and Zn is inthe range of concentrations for normal soils,according to the Romanian Order 756/1997.3. Results and discussionIn Figure 1 are shown the levels of accumulationof metals: Cr, Cu, Pb, and Zn by transfer factorsexpressed in the plant tissue of Onobrychisviciifolia species.494

Morariu F. et. al./Scientific Papers: Animal Science and Biotechnologies, 2011, 44 (1)0.14Chromium0.4CopperTransfer factor soil-plant0.120.10.080.060.040.02Transfer factor soil-plant0.350.30.250.20.150.10.050C C+B C+T C+B+TExperimental varantsa)0C C+B C+T C+B+TExperimental variantsb)Transfer factor soil-plant0.30.250.20.150.10.050LeadC C+B C+T C+B+TExperimental varintsc)1.81.61.41.210.80.60.40.20ZincC C+B C+T C+B+TExperimental variantsFigure 1. Accumulation of metals expressed by transfer factors of soil-plant tissue in Onobrychis viciifolia species:a) Chromium, b) Copper, c) Lead, and d) Zinc.Transfer factor soil-plantd)The figure shows that the transfer factor isdependent on the metal species and topsoiltreatment:1. The organic fertilizer determines the followingchanges in bioavailability:- Transfer factor increases, as well as thebioavailability of metals such as copper;- Reduces the transfer factor and bioavailability ofsome metals with 70-90%, such being the case ofPb or Zn.2. Inorganic amendment determines the followingchanges in bioavailability:- Transfer factor increases, as well as thebioavailability of metals such as chromium;- Reduces the transfer factor and bioavailability ofsome metals with 50% such being the case for Znand 100% for Pb.3. The organic-zeolite fertilizer determineschanges in bioavailability:- It is the most effective treatment, showingsynergistic effects of bioavailability reduction upto 45-65% for Cu and Cr;- At the same time, the influence of pillaredvolcanic tuff to decrease bioavailability of Pb andZn in soil exceeds the organic matter and biosolidstendency to make available these metals, so thateventually the transfer factor values be minimal.4. ConclusionsThe use organic fertilizers of the biosolids type, ofsome inorganic amendments such as indigenousvolcanic tuff based on clinoptilolite (as a pillaredtuff-Aln) and organic-zeolite fertilizers based onbiosolids mixed with pillared tuff demonstratedtheir ability to change the bioavailability of metalsfrom the fly ash layer covered with Onobrychisviciifolia plants.From the treatment variants, the most effectiveone was the organic-zeolite fertilizer because itshows synergistic effects to reduce thebioavailability of up to 45-65% for copper andchromium.At the same time, the influence of pillaredvolcanic tuff to decrease the bioavailability of leadand zinc in soil exceeds the organic matter andbiosolids tendency to make bioavailable thesemetals, so that eventually the transfer factor valuesbe minimal.495

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