The effect of manure, zeolite and soil ageing in the dynamics of hexavalent chromium in Cichorium spinosum

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1 The effet of mnure, zeolite nd soil geing in the dynmis of hexvlent hromium in Cihorium spinosum V. Antonidis, T. Polyzois, S. Petropoulos, E.E. Goli nd A. Dimirkou Deprtment of Agriulture Crop Prodution nd Rurl Environment, University of Thessly, Fytokou Street, Volos, GR , Greee Astrt Hexvlent hromium is toxi nioni speies, found in soils minly due to nthropogeni tivities. In this experiment we studied the effet of dded Cr(VI) to Cihorium spinosum, suspeted tolernt wild edile vegetle. We dded mnure so tht redution of Cr(VI) to the inert speies Cr(III) my e indued; this ws ompred with two other tretments representing possile mitigtion tehniques: ddition of nturl zeolite nd soil geing. Our im ws to ompre these three Cr(VI) methods of deresing Cr(VI) iovilility. In 6-dy pot experiment we hd tretments replited times, s follows: Unmended ontrol (tretment C), soil dded with 1 mg kg -1 Cr(VI) (tretment S), soil with 1% zeolite plus 1 mg kg -1 Cr(VI) (tretment Z), soil with 1% mnure plus 1 mg kg -1 Cr(VI), nd soil dded with 1 mg kg -1 Cr(VI) one yer efore the experiment (tretment AS, for ged soil ). We found tht t Z Cr(III) ws the highest mong the other tretments; Cr(VI) ws the highest t S, while Z, M nd AS hd signifintly lower onentrtions thn S (ut higher thn the ontrol). In plnt, t Z, S, nd AS Cr(VI) onentrtions were high nd without differenes, while t M Cr(VI) ws signifintly lower. Similr were the findings for plnt Cr(III). This indites tht dded mnure did not derese Cr(VI) vilility to C. spinosum due to redution to Cr(III), ut rther due to the formtion of orgnometlli omplexes. We onlude tht dded mnure ws the est prtie for mitigting Cr(VI) iovilility. Keywords: Biovilility, iomss, Cihorium spinosum 1. Introdution Hexvlent hromium is highly toxi nd esily moilised tre element. In soil solution it is found in the nioni form of CrO - 4 or HCrO - 4. Due to the ft tht the most importnt soil olloids er negtive hrge on their surfes, Cr(VI) is not ple of eing retined y soil onstituents. Thus it is highly moile in the soil environment, nd redily sored y plnts [1]. Although Cr(VI) my e of nturl origin, high onentrtions re usully ssoited with 1

2 nthropogeni inputs. The plin of Assopos river, South Greee, is suspeted of hving high onentrtions of Cr(VI) due to the deposition of wstes of ertin industril plnts situted in tht re []. In tht sme re, grden vegetles re ultivted nd trded; thus fers of introdution of Cr(VI) into the humn food hin re not unsustntil. It is well known tht Cr(VI), when dded to soil, is eventully redued over time to its trivlent form [3]. Cr(III) is tioni speies, found s Cr 3+ in the soil solution; for this reson it is strongly retined y soil olloids, nd is thus very slow in eing sored y plnts. Thus possile Cr(VI) mitigtion prtie would e to llow suffiient soil geing time fter Cr(VI) ddition to soil. This pplies to sitution where Cr(VI) is not dded ontinuously to soil. On the other hnd, orgni mtter is known to hve positive effet in reduing Cr(VI) to Cr(III) in soil [4]. Thus nother tehnique to mitigte Cr(VI) ontmintion would e to dd orgni mterils (e.g., mnure). Another wy to derese Cr(VI) to soil my lso e the ddition of positive-hrge surfes to soil. Suh mterils ould ttrt Cr(VI) from the soil solution, deresing thus their tivity nd their uptke y plnts. Vrious mterils hve een suggested, with surfe-modified zeolite eing the most widely used []. However, there is mrked disdvntge in using modified zeolites: they re wter-repellent nd thus rete hydrophoi films in soil tht use wter stress to plnts. Thus modified zeolite hve rrely een used in growth experiments. Alterntively, nturl zeolites ould e used, despite the ft tht it is negtive-hrged [6]. Although Cr(VI) is found in soil solution s n nion, pplition of zeolite to soil my retin Cr(VI) through physil entrpment in its pores. To our knowledge, there is no work tht would ompre those three Cr(VI) mitigtion prties (soil geing, ddition of mnure nd ddition of zeolite) to vegetles. Our test plnt ws Cihorium spinosum, vegetle never tested efore in similr study. C. spinosum is wild speies tht tolerte hrsh environmentl onditions. It is thus suspeted tht it ould serve s n lterntive ultivtion in res ffeted y Cr(VI) ontmintion. We thus wnted to test its tolerne to Cr(VI) exposure. The im of this work ws to test ddition of mnure, the ddition of zeolite, nd soil geing s Cr(VI) mitigtion prties in deresing Cr(VI) ontmintion in soil ultivted with C. spinosum.. Mterils nd Methods We studied soil with orgni C 1.3% nd slightly lkline (ph 7.). We hd the following tretments: () Tretment C: Control soil, with no dditions

3 Soil Cr(ΙΙΙ) (mg kḡ 1 ) Soil Cr(VI) (mg kḡ 1 ) () Tretment S: Soil dded with 1 mg Cr(VI) kg -1 () Tretment Z: Soil dded with 1 mg Cr(VI) kg -1 nd 1% w/w zeolite (d) Tretment M: Soil dded with 1 mg Cr(VI) kg -1 nd 1% dry frmyrd mnure (e) Tretment AS: The sme soil, mended one yer efore this experiment with 1 mg Cr(VI) kg -1 ws used (nmed AS for ged soil ). These tretments were replited times. We pled these tretments into 1-L pity pots, where we put 1 kg of eh of the tretments, nd C. spinosum ws sowed; the pots were wtered regulrly. We hrvested the plnts 6 dys fter sowing. After hrvesting, soil smples were tken, extrted nd nlysed for Cr(III) (with CCl -DTPA) nd Cr(VI) (with.1 M KH PO 4 ). Aeril iomss ws lso hrvested, dried in fored-drught oven until no further weight loss ws reorded, weighed, dry shed, extrted with ml % HCl nd nlysed for Cr(III) nd Cr(VI). For soil, DTPA-extrted Cr(III) ws nlysed with tomi sorption spetrometry (AAS), nd Cr(VI) olourimetrilly with dithenyl-rzide in spetrophotometer t 4 nm. For plnt, we nlysed the plnt extrts with AAS for the determintion Cr(III) + Cr(VI), nd lso olourimetrilly in spetrophotometer for the determintion of Cr(VI). The onentrtion of Cr(III) ws then lulted s he differene etween AAS-nlysed Cr(III)+Cr(VI) nd spetrophotometer-nlysed Cr(VI). The dt were nlysed for sttistil signifine with one-wy ANOVA; we used the sttistil pkge IBM SPSS Sttistis v.1. for Windows (IBM orp.). 3. Results nd Disussion () () Fig. 1. Soil onentrtions of () Cr(III) nd () Cr(VI). Although we did not find ny Cr(VI) nd Cr(III) in the unmended soil, the ddition of the metl resulted in signifint inrese in soil Cr(III) levels. This inrese ws signifint for tretment Z (Fig. 1). On the other hnd, Cr(VI) inresed signifintly ompred to the ontrol in ll Cr(VI)-dded tretments, with S hving signifintly higher onentrtions ompred to Z, M, nd AS (Fig. 1). Bering in mind tht we dded only Cr(VI) t rte of 1 mg Cr(VI) kg -1 soil, ll Cr(III) we found ws the result of the redution of dded Cr(VI)

4 Biomss (g pot -1 ) Plnt Cr(III) (mg kḡ 1 ) Plnt Cr(VI) (mg kḡ 1 ) () 1 1 () Fig.. Plnt onentrtions of () Cr(III) nd () Cr(VI), s well s () eril iomss. Tretment Z seems to hve indued more Cr redution from vleny VI to III thn the other tretments. This my e ssoited with the porosity of zeolite; it is possile tht formed Cr(III) t Z ws trpped into the zeolite pores nd relesed slowly, so tht it ws proteted from eing tken up y the test plnt. On the other hnd, Cr(VI) in S ws similr to tht initilly dded, inditing tht no redution to Cr(III) took ple (unlike the findings y [7]); it lso shows tht it ws the mendments of zeolite nd mnure long with geing tht used the redution of Cr(VI) in the Z, M, nd AS tretments, respetively. In the tretments where we tested the three mitigtion tehniques, Cr(VI) levels were similr nd without signifint differenes mong them. While low Cr(VI) levels t M nd AS were not unexpeted, it is interesting tht even t Z Cr(VI) ws omprtively low. Added zeolite seems to hve used the redution to Cr(III) nd the derese of Cr(VI) soil levels. In plnt, Cr(III) ws deteted t ontrol in very low onentrtions (< mg kg -1 ), nd the levels t C were similr to those t M. The other 3 tretments (Z, A nd AS) hd signifintly higher Cr(III) onentrtions, ut they were similr when ompred mong them (Fig. ). Cr(VI) ws zero t C; mong the Cr(VI)-dded tretments, M hd signifintly lower onentrtion ompred to the others, while Z, S, nd AS hd no differenes mong them (Fig. ). This shows tht in ll Cr(VI)-dded tretments, uptke ws similr mong tretments, despite the differenes in soil Cr(III) levels; exeption ws tretment M, whih ws lower. Likewise, irrespetive of soil Cr(VI) levels, plnt uptke ws sustntil t Z nd AS, similr to tht t S. This mens tht t plnt level, zeolite nd soil geing did little to derese Cr(VI) uptke ompred to the unproteted soil (tretment S). Our results, if soil nd plnt dt re tken into ()

5 Biomss Cr(VI)-plnt Cr(III)-plnt () () y =.138x R =.443** p = Cr(III)-soil y =.16x R =.67*** p = Cr(VI)-soil () 4 y = Ln(x) R =.941*** p < Cr(VI)-plnt Fig. 3. Correltion etween () Cr(III) in soil nd plnt, () Cr(VI) in soil nd plnt, () Cr9VI) nd iomss, nd (d) orgni C nd % Cr(III)-over-Cr(VI) rtio in soil. onsidertion, suggest tht zeolite enhned the evolution of Cr(III) (s indited in Fig. 1), ut it ould not ind the remining Cr(VI), whih ws redily sored y plnt. On the other hnd, soil geing resulted in lower soil Cr(VI) levels (Fig. 1), ut it seems tht the remining Cr(VI) ws still highly ville to plnt nd suffiient to umulte t high onentrtions in plnt [8]. The tretment tht hd the est effiieny in reduing plnt uptke ws M. At M plnt Cr(VI) ws the lowest, exluding C, similr to soil Cr(VI) (lthough in soil the differene of M ompred Z nd AS ws not signifint). Mnure seems to hve ffeted Cr(VI) in positive wy. There two min mehnisms this my hve ourred: () the elerted redution of dded Cr(VI) to Cr(III), nd () the formtion of orgnometlli omplexes unle

6 to e sored y the plnt. If the first mehnism ws dominnt, soil Cr(III) t M should e higher thn t other tretments. Alterntively, the rtio of Cr(III)/Cr(VI) should e higher t M ompred to other tretments, euse higher rtio would indite higher evolution of Cr(III) ompred to Cr(VI) in soil. However, the Cr(III)-over-Cr(VI) rtio ws similr ross tretments (dt not shown). Thus the possile reson is mehnism (). Orgnometlli omplexes, if of suffiiently high moleulr weight, re inple of eing sored y plnt, nd this uses redution in Cr(VI) uptke. Indeed suh omplexes re reported to inrese in soils where Cr(VI) nd orgni mtter hve een dded [9]. Dry plnt iomss indites Cr(VI)-indued toxiity (Fig. ): in ll tretments plnt weight deresed signifintly ompred to the ontrol. Moreover, no differenes mong Z, M, S, nd AS were found. In order to further investigte the vrious effets of dded Cr(VI) to soil, we performed orreltion nlyses. As expeted, soil Cr(III) ws signifintly orrelted with plnt Cr(III) (Fig. 3), nd so ws Cr(VI) (Fig. 3). Correltion nlysis onfirmed the dverse effet dded Cr(VI) hd on plnt iomss: it showed tht dded Cr(VI) signifintly redued plnt iomss. 4. Conlusions We onlude tht the ddition of mnure is the est prtie to minimize the toxi effets of dded Cr(VI) to C. spinosum. Referenes 1. Lttnzi, P., Aquilnti, G., Brdelli, F., Ideol, A., Rosellini, I., Tssi, E., Pezzross, B., Petruzzelli, G.: Spetrosopi evidene of Cr(VI) redution in ontminted soil y in situ tretm,ent with whey. Agrohimmi 9, 18-3 (1).. Eonomou-Eliopoulos, M., Megremi, I., Vsiltos, C.: Ftors ontrolling the heterogenous distriution of Cr(VI) in soil, plnts nd groundwter: Evidene from the Assopos sin, Greee. Chem. Erde 71, 39- (11). 3. Xio, W., Zhng, Y., Li, T., Chen, B., Wng, H., He, Z., Yng, X.: Redution kinetis of hexvlent hromium in soils nd its orreltion with soil properties. J. Environ. Qul. 41, (1). 6

7 Brjs-Aeves, M., Coron-Hernndez, J., Rodriguez-Vsquez, R.: Chromium frtiontion in semi-rid soils mended with hromium nd tnnery sludge. J. Hzrd. Mter. 146, (7).. Dng, H., Zhng, Y., Du, P.: Enhned removl of solule Cr(VI) y using zero-vlent iron omposite supported y surftnt-modified zeolites. Wter Si. Tehnol. 7, (14). 6. Wyszkowski, M., Rdziemsk, M.: Assessment of tri- nd hexvlent hromium phytotoxiity on ots (Aven stiv L.) iomss nd ontent of nitrogen ompunds. Wter Air Soil Pollut. 4, 1619 (13). 7. Xio, W., Yng, X., He, Z., Rfiq, M.T., Hou, D., Li, T.: Model for evlution of the phytovilility of hromium (Cr) to rie (Oryz stiv L.) in representtive Chinese soils. J. Agr. Food Chem. 61, 9-93 (13). 8. Moll, K., Dimirkou, A., Antonidis, V.: hexvlent hromium dynmis nd uptke in mnure-dded soil. Wter Air Soil Pollut. 3, (1). 9. Rendin, A., Brros, M.J., De Iorio, A.F.: Chnges in the speition, prtitioning nd phytovilility of hromium indued y orgni soil mendments. Chem. Spe. Biovil. 3, 3-6 (11). 7