Afr. J. Biomed. Res. Vol.19 (September, 2016);

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1 Afr. J. Biomed. Res. Vol.19 (September, 2016); Full Length Reserch Pper Soil Profile Qulity of Contminted Dumpsite in Ibdn, Nigeri *Oni, A. A 1, 2 nd Hssn, A.T. 2 1 Institute of Applied Ecology, 72, Wenhu Rod, , Shenyng, Chin. 2 Ecology/Environmentl Biology Unit, Deprtment of Zoology, University of Ibdn, Ibdn, Nigeri. ABSTRACT Solid wste disposl my result in soil pollution with implictions for groundwter qulity. The impct of wste disposl on soil qulity of the Ab-Eku dumpsite, Ibdn, Nigeri ws studied t five depths in the profile. Soil smples were collected bi-monthly over 21-month period t three sub-sites: - Wste Dump Are (WDA), Lechte Lgoon Are (LLA) 250m down-grdient of WDA; nd control (600m wy from WDA nd LLA); using n uger nd nlyzed for vrious physico-chemicl prmeters. Dt were nlyzed using Principl Component Anlysis (PCA) nd ANOVA. Contmintion fctors were lso computed using relevnt formuls. Seven, five nd four fctors were extrcted by PCA, explining 83%, 86% nd 80% vrition in WDA, LLA nd control respectively. Positive lodings for percent grvel (0.941) nd permebility (0.596) nd negtive lodings from percent snd (-0.912) on the first PC for WDA suggested increses in the corse frction nd decreses in the fine frction were ssocited with moderte increses in permebility t the site. Except iron nd potssium, other prmeters were significntly elevted (p<0.05) in WDA profiles compred to LLA nd control. Cdmium reduced significntly (p<0.05) with depth from 23.7±5.3; (0-15cm) to 12.7±3.0 mg/kg; (75-100cm) suggestive of grdul leching into groundwter. Zinc, copper nd cdmium hd contmintion fctors of 56.84, nd respectively in WDA which reduced to 3.28, 3.71 nd 1.09 in LLA downgrdient. Two plnts, Chromolen odort nd Pennisetum pupureum found between WDA nd LLA sites my hve contributed to contminnt reduction nd my be exploited for further remedition of the site. Keywords: Soil, contminnts, wstes, Ab-Eku, groundwter, phytoremedition *Author for correspondence: E-mil: deyoni2006@yhoo.co.uk; Tel: Received: Februry, 2016; Accepted: June, 2016 Abstrcted by: Bioline Interntionl, Africn Journls online (AJOL), Index Copernicus, Africn Index Medicus (WHO), Excerpt medic (EMBASE), CAB Abstrcts, SCOPUS, Globl Helth Abstrcts, Asin Science Index, Index Veterinrius INTRODUCTION Despite the complexity of wstes produced, the stndrds of lndfills in developing countries is still poor (Ismil nd Mnf, 2013). The expensive nture of snitry lndfills (Diz nd Svge, 2002) mkes mny developing countries to use unlined lndfills with ttendnt effects on soil nd underlying groundwter qulity. Soil qulity influences bsic functions such s nutrient storge nd cycling, buffering nd immobiliztion rections, contminnt filtrtion mongst other functions (Shukl et l, 2006). Soil nd groundwter pollution from lndfill lechte is mjor problem (Aluko et l., 2003; Yenigul et l, 2005; Rpti-Cputo nd Vccro, 2006; Adnn et l, 2013; Gworek et l, 2015). The Ab-Eku dumpsite is mjor municipl solid wste dumpsite in Ibdn, Nigeri. Inhbitnts within kilometer of the dumpsite rely on groundwter for their domestic needs. Considering the soil s bility to serve s contminnt sink, nd the implictions of this for underlying groundwter qulity, the impct of wste disposl on soil qulity t vrious depths in the profile will be vluble. This study therefore evluted the physico-chemicl qulity of the soil of the dumpsite t mximum of five depth levels in the profile. MATERIALS AND METHODS Study Are: The Ab-Eku dumpsite is locted in On-Ar locl government re of Oyo stte, Nigeri. Plnts in the vicinity of the study re were collected for identifiction t the Herbrium of the Deprtment of Botny, University of Ibdn, Ibdn, Nigeri.

2 Soil profile of contminted dumpsite Smples nd Smpling procedures: Soil smples were obtined bimonthly (every two months) using soil uger over 21-month period t the following depths: top-soils (0-15cm); sub-soils, 15-30cm; 30-60cm; 60-75cm; nd cm. However, it ws not lwys possible to go beyond 75cm. Two dditionl sites: (LLA) nd control (CON) pproximtely 600m wy from the WDA were locted using GPS 76 grnier model. Geogrphicl coordintes re shown in Fig. 1. The LLA is locted bout 250m down-grdient of the dumpsite. Ten cores were obtined from WDA, while five cores were obtined from LLA nd CON respectively. Core smples of similr depths within ech site were bulked to form composite t ech smpling period. The soil smples were collected in lbelled polyethylene bgs nd tken to the lbortory for processing nd nlysis. compred to LLA nd control except for the 15-30cm depth, which ws sttisticlly similr with LLA t this depth. Potssium nd iron showed predominnt declines down WDA profiles (Tble 1), with both elements showing the highest levels in LLA down-grdient of the dumpsite. Potssium ws significntly elevted (p<0.05) in LLA profiles, while iron levels were higher but not significnt t p<0.05, except t the 15-30cm depth in LLA. As expected, vlues for potssium nd iron in the control were the lowest nd differed sttisticlly from WDA nd LLA profiles except t the highest depths (Tbles 1-3).. Smple processing / Anlysis: Soil smples were ir-dried for hours in the lbortory pulverized using porcelin mortr nd sieved using 2mm sieve. ph nd Soil Orgnic Mtter (SOM) ws determined ccording to (ASTM, 1995) nd Lu, (1999) method. Ction Exchnge Cpcity (CEC) ws determined using the method of (Mdeir et l., 2003). Exchngeble ctions nd metls were determined on n ICP- OES Perkin Elmer Optim 3000 fter Hydrofluoricperchloric-nitric cid digestion (Lu, 1999). A metl stndrd (led) ws purchsed from the mnufcturer, digested nd nlyzed s bove. The recovery rte ws 94%. Grin size distribution ws determined ccording to Tucker (1991) t the Deprtment of Geology, University of Ibdn, Ibdn, Nigeri. Permebility ws estimted from the results of Grin size distribution using Hzen s empiricl formul (Odong, 2007). All nlyticl procedures, except for grin size nd permebility were crried out t the Shenyng Institute of Applied Ecology, Shenyng, Chin. Contmintion fctor for ech metl ws determined ccording to Hknson (1980) using the expression c i f = c i 0-1 / c i n where c i f = contmintion fctor, c i 0-1 = Men concentrtion of individul metl from top-soil of the test sites, nd c i n = bseline or bckground concentrtion of the individul metl from top-soils of the reference site. Anlysis of vrince (ANOVA) nd Principl Component Anlysis (PCA) ws used for dt nlysis RESULTS Results of the physicochemicl prmeters nd ANOVA for the three sites re summrized nd presented in Tbles 1-3. Except for top-soils of LLA, ph in WDA ws sttisticlly similr to tht of LLA but significntly higher thn control (p<0.05). Orgnic mtter, CEC, clcium, copper, zinc, led nd cdmium were significntly higher (p<0.05) in ll WDA profiles thn in profiles of both LLA nd control sites (Tbles 1-3). Orgnic mtter levels were highest in top-soils of LLA nd control, while WDA hd higher levels of SOM within the profile, compred to top-soil (Tbles 1-3). Mgnesium levels were significntly elevted (p<0.05) in WDA profiles Plte 1: Mp of the dumpsite showing the smpling points Mngnese ws significntly higher (p<0.05) in WDA profiles up to 30cm depth when compred to LLA nd control. Principl Component Anlysis for WDA extrcted seven fctors which explined 83% of the totl vrince. Principl components 1-7 explined 16%, 15%, 13%, 11%, 11%, 10% nd 8% of totl vrince respectively. Percent grvel, permebility nd percent snd contributed most to the vrince on principl components (PC) 1 for WDA nd PC 2 for LLA; with percent snd loding negtively on both PCs (Tbles 4-5). Clcium, mgnesium nd cdmium ccounted for most of the vrince on PC 2 in WDA; mngnese, zinc nd soil orgnic mtter on PC 3 in WDA; CEC nd potssium on PC 4; iron on PC 5; while ph nd led contributed most of the vrince on PC 6 with led showing negtive loding on this principl component. Copper contributed much of the vrince on PC 7 (Tble 4). 220 Afr. J. Biomed. Res. Vol. 19, No.3 (September) 2016 Oni nd Hssn

3 Tble 1: Summry of some physico-chemicl prmeters of WDA soils over the study period. SAMPLE ph SOM CEC C Mg K Fe Mn Cu Zn Pb Cd % % % K GRAVE SAND SILT/CL (PERM.) (%) (Cmol/kg) L AY Mx Men (9) 7.76b 7.44b b bc bc bc bd b b b 23.73d 46.40d 50.33c SD Mx Men (9) 7.63b 8.06b b c b c c bd b b b 15.13c 43.81df 52.96c SD Mx Men (8) 7.78b 8.24b b bc bc c de b b b 17.13c d 42.97df 54.31c SD Mx Men (2) 7.95b 8.76 b b b b ce f b b b c d 42.99df 54.35c SD Mx Men (2) 7.86 b 8.61 b b c c d c d c b b 12.72c 32.25f 59.79c 7.96b SD Mens with similr letters re not significntly different t p < 0.05

4 Soil profile of contminted dumpsite Tble 2: Summry of some physico-chemicl prmeters of LLA soils over the study period SAMPLE ph SOM CEC C Mg K Fe Mn Cu Zn Pb Cd % % % K (%) (Cmol/kg) GRAVEL SAND SILT/CLAY (PERM. ) Mx Men (9) d b bd ef 64.91bc SD Mx Men (9) 7.51b bd c b bd e 68.24c SD Mx Men (9) 7.63b d b d e f 59.91b SD Mx Men (3) 7.75b de f b de f e 67.65c SD Mens with similr letters re not significntly different t p < Afr. J. Biomed. Res. Vol. 19, No.3 (September) 2016 Oni nd Hssn

5 Tble 3: Summry of some physico-chemicl prmeters of Control (CON) soils over the study period. Smple ph SOM (%) CEC (Cmol/kg) C Mg K Fe Mn Cu Zn Pb Cd GRAVE L % SAN D % SILT/CLA Y K (PERM.) Mx Men (9) e 69.67c SD Mx Men (9) e 70.41c 3.42b SD Mx Men (8) e e e 65.59c 3.54b b SD Mx Men (3) e ef e f f 49.68d 2.49b b SD Mens with similr letters re not significntly different t p < 0.05

6 Tble 4: Principl Component Anlysis (PCA) for the Wste Dump Are (WDA) Rotted Component Mtrix for site WDA Principl Component ph som cec c mg k fe mn cu zn pb cd pctgrl pctsd pctsc perm % V. 16% 15% 13% 11% 11% 10% 8% CV. 16% 31% 43% 54% 65% 75% 83% Abbrevitions- SOM: Soil orgnic mtter; CEC: Ction exchnge cpcity; C: Clcium; Mg: Mgnesium; K: Potssium; Fe: Iron; Mn: Mngnese; Cu: Copper; Zn: Zinc; Pb: led; Cd: Cdmium; Ni: Nickel; Cr: Chromium; Pctgrvl: Percent grvel; Pctsd: Percent snd; Pctsc: Percent silt/cly; Perm: Permebility; % V: Percentge vrince; CV: Cumultive Vrince. Tble 5: Principl Component Anlysis (PCA) for the Lechte Lgoon Are (LLA) Rotted Component Mtrix for the Lechte Lgoon Are Principl Component ph som cec c mg k fe mn cu zn pb cd pctgvl pctsd pctsltcl perm %V. 37% 16% 15% 11% 7% CV. 37% 53% 68% 79% 86% Abbrevitions- SOM: Soil orgnic mtter; CEC: Ction exchnge cpcity; C: Clcium; Mg: Mgnesium; K: Potssium; Fe: Iron; Mn: Mngnese; Cu: Copper; Zn: Zinc; Pb: led; Cd: Cdmium; Ni: Nickel; Cr: Chromium; Pctgrvl: Percent grvel; Pctsd: Percent snd; Pctsc: Percent silt/cly; Perm: Permebility; % V. :Percentge Vrince; CV: Cumultive Vrince. Results of PCA for LLA showed tht five fctors were extrcted which explined 86% of the vrince. Principl Components 1-5 explined 37%, 16%, 15%, 11% nd 7% of the totl vrince respectively (Tble 5). Potssium, iron, zinc, led copper nd clcium contributed most to the vrince on PC 1 in LLA; percent grvel, percent snd nd permebility on PC 2; soil orgnic mtter, mngnese nd clcium on PC 3; ph, CEC nd copper on PC 4; while percent silt nd cly nd cdmium contributed most to the vrince on PC 5 in LLA (Tble 5). Four fctors were extrcted in control explining totl of 80% of totl vrince, with percentge contributions of 37%, 17%, 15% nd 11% on PC 1-4 respectively (Tble 6). Iron, mngnese, percent snd, percent grvel, copper nd cdmium contributed most of the vrince on PC 1 of the control, with percent snd nd cdmium loding negtively on tht PC. Clcium nd mgnesium, s well s led nd ph contributed much of the vrince on PC 2 of the control; while zinc, CEC nd potssium contributed most to the vrince on PC 3 nd soil orgnic mtter on PC 4 of the control (Tble 6). Tble 6: Principl Component Anlysis (PCA) for the Control Are (CON) Rotted Component Mtrix for CON Principl Component ph som cec c mg k fe mn cu zn pb cd pctgrvl pctsd pctsltcl perm %V. 37% 17% 15% 11% CV 37% 54% 69% 80% Abbrevitions- SOM: Soil orgnic mtter; CEC: Ction exchnge cpcity; C: Clcium; Mg: Mgnesium; K: Potssium; Fe: Iron; Mn: Mngnese; Cu: Copper; Zn: Zinc; Pb: led; Cd: Cdmium; Ni: Nickel; Cr: Chromium; Pctgrvl: Percent grvel; Pctsd: Percent snd; Pctsc: Percent silt/cly; Perm: Permebility; % V. :Percentge Vrince; CV: Cumultive Vrince. DISCUSSION The similrity in ph between WDA nd LLA shows trend of incresed lklinity in the dumpsite soil profile occsioned by lechte percoltion into it. The higher levels of Soil Orgnic Mtter (SOM) within WDA profiles compred to the top-soil (Tble 1) my be due to intense leching in WDA, which probbly resulted in the trnsloction of soluble orgnics nd subsequent loss of SOM from the surfce of the soil pedon (Dniels nd Glbrith, 2007). The incresed CEC vlues in WDA imply tht there will be incresed competition

7 t uptke sites on the soil surfce (Nhmni et l, 2007) which my reduce the mounts of metl ions tht my be bsorbed. Clcium nd mgnesium showed similr leching pttern in soil profiles of the three sites, probbly suggestive of similr nthropogenic nd/or geogenic origin nd behvior (Tbles 1-3). Contmintion fctors for potssium in WDA nd LLA were 0.83 nd 1.44 respectively, suggestive of the downwrd leching of potssium from WDA nd its subsequent ccumultion in LLA down-grdient of the dumpsite. Similr results were obtined by Ahmed & Suleimn (2001) on Mlysin lndfill. Furthermore, the humid regions of southern Nigeri re known to hve high leching intensity which often results in potssium deficiency in some soils in this region, prticulrly sndy soils (Iderih et l., 2006). WDA soils hd high snd content (Tble 1), thus the high leching intensity coupled with lechte percoltion through soil my hve resulted in potssium deficiency in WDA nd its subsequent ccumultion down-grdient. This my explin the low levels of potssium in WDA soils compred to control. Iron levels were highest in LLA down-grdient, lso suggestive of downwrd leching of iron from WDA (Tbles I-III). High levels of iron in the control my suggest high nturl bckground concentrtions in soils djoining the dumpsite. Nturl soils my contin high concentrtions of iron (Ademoroti, 1996; Agunbide nd Fwle, 2009). The computed contmintion fctors for metls in WDA were zinc (56.84), copper (21.30), cdmium (19.29), led (4.27), mngnese (1.99) nd iron (1.83). The site LLA downgrdient hd much lower contmintion fctors of 3.71 (copper), zinc (3.28), iron (1.90), led (1.46), cdmium (1.09) nd mngnese (1.07). Thus, contmintion fctors in WDA top-soils were in the order Zn > Cu > Cd (very high contmintion fctor of 6) > Pb (considerble contmintion fctor of 3-6 > Mn > Fe (moderte contmintion fctors of 1-3). Furthermore, copper, zinc nd cdmium in WDA exceeded locl regultory stndrds t ll depths in the profile. Led exceeded the stndrds t ll depths except the cm depth, while chromium exceeded the stndrds t 0-15; 15-30cm depths nd cm depths. Copper exceeded the limits in LLA t ll depths, while other metls were within the limits. Metls in the control were ll within regultory limits (Tbles 1-3). These results clerly illustrte the effects of the wstes dumped on metl levels in soils. High metl levels in the soils re reflective of the high proportion of metl wstes t the dumpsite (bout 25%) (Oni, 2010). The LLA hd contmintion fctors rnged from considerble for copper nd zinc to moderte for iron, led, cdmium nd mngnese respectively. Two plnts (Chromolen odort (L. King & Robinson) (Sim weed) nd Pennisetum purpureum (Elephnt grss) were found growing bundntly in vegetted res djcent to WDA. The hyper-ccumultion potentils of C. odort for hevy metls such s copper, mercury (Alisung, 2005; Alinsug et l, 2005), led, cdmium (Tnhn et l, 2007; Agunbide nd Fwle, 2009; Aziz, 2011) nd zinc (Aziz, 2011) re well known nd reported in literture. Pennisetum pupureum is known to be hevy metl tolernt (Chen et l, 2011) nd lso hs potentil for the phyto-extrction of Soil profile of contminted dumpsite cdmium nd zinc polluted sites (Zhng et l, 2010). Thus, the presence of these plnts in the vicinity of the study re my perhps explin the considerbly reduced contminnt levels in the down-grdient re of the dump site. These metls lso exceeded locl regultory limits highlighting the need for remedition. The potentil of C. odort nd Pennisetum pupureum my be further exploited for site remedition. Soils of WDA hd high percentges of snd nd grvel with little mounts of silt nd cly (Tbles 1-3). Consequently, the soils permebilities were higher thn the stipulted minimum vlue of 1 x 10-6 cm/sec (Diz nd Svge, 2002) for lndfill soils. Although LLA soils hd higher percentges of snd, their permebilities were still higher thn the stipulted minimum for lndfill soils. Significntly incresed levels of grvel t higher depths (60-75cm depth) in the control resulted in significnt increse in permebility t tht depth. The high permebilities imply tht contminnts my move rpidly through the soil, receiving very little filtrtion long the wy (Lindorff, 1979), thus resulting in groundwter contmintion. Groundwter nlysis over similr time-frme showed elevted metl levels (Oni, 2010). Positive lodings from percent grvel nd permebility nd the negtive loding from percent snd on the first PC for WDA nd second PC for LLA, suggests tht increses in the corse soil frction nd decreses in the finer frction re ssocited with moderte increses in permebility t both sites. Nhmni et l, (2007b) in their nlysis of metl contminted soils obtined similr results. Lechtes my contin incresed hevy metls, orgnic mtter, mmoninitrogen, orgnic nd inorgnic slts (Renou et l, 2008). The lodings from potssium, iron, mngnese, copper, zinc, clcium nd mgnesium on the first PC for LLA re probbly indictive of similr nthropogenic origin from lechtes wshing out towrds the down-grdient re. Strong positive lodings on the first PC from iron, mngnese, copper nd zinc in the control my likely indicte similr geo-genic origin; while the negtive loding from cdmium my possibly indicte the influences of other metls on sorption nd desorption of cdmium in control soil. The positive lodings from zinc nd SOM on the third PC in WDA my suggest the possible contribution of SOM to some of these micro- nutrients such s zinc (Gskell et l, 2007). The results obtined for the fourth PC for WDA nd LLA, nd the third for control, probbly indictes the influence of CEC on potssium, zinc nd copper levels in these soils. The CEC is very importnt soil property for nutrient retention nd supply (Crvc et l, 1999). It ppers tht ction exchnge probbly plys n importnt role in the levels of these elements in these soils. The sixth PC illustrtes the probble role of incresed ph in led desorption from the soil, ultimtely leding to incresed mobility of this metl in WDA soils. This ws corroborted by high led levels in the groundwter djoining the dumpsite which exceeded interntionl nd locl regultory stndrds (Oni, 2010). The ssocition of mngnese nd SOM on PC three in sites WDA nd LLA is probbly indictive of possible occurrence s complexes with SOM (Riediker et l, 2000). Percent silt nd cly frction nd SOM loded strongly on the fourth PC in LLA nd my be due to the fct tht orgnic 225 Afr. J. Biomed. Res. Vol. 19, No.3 (September) 2016 Oni nd Hssn

8 Soil profile of contminted dumpsite mtter in rble soils re mostly ssocited with the silt nd cly frction (Christensen 1992; Hssink, 1997). Furthermore, soil frction of less thn 6.3mm which constitutes the silt/cly frction is good source of orgnic mtter (Jin et l, 2005) nd perhps explins this ssocition. The high levels of the vrious contminnts hve importnt implictions for underlying groundwter. Metls such s led, cdmium nd iron in groundwter of Ab-Eku community hve been confirmed to be bove interntionl ind locl regultory limits; while others such s zinc nd copper were within the limits, illustrting the importnt role mobility in soil plys in determining contminnt levels in groundwter (Oni, 2010). Bioremedition strtegies re thus necessry for soils of the dumpsite. Phyto-remedition, common bioremedition strtegy for hevy metl polluted soils my be considered in view of its cost effectiveness nd environmentlly cceptble nture. The results showed elevted levels of hevy metls in depth profiles of Ab-Eku dumpsite. This hs implictions for underlying groundwter of the site. The high contminnt levels negtively impcts the ecosystem nd my lso ffect humn helth. C. odort, nd P. pupureum, two plnts found in the djoining down-grdient res of the dumpsite my hve plyed n importnt role in hyper-ccumultion of some hevy metls resulting in much lower contmintion downgrdient. Elevted levels of some metls bove intervention/regultory guidelines mke remedition of the dumpsite highly necessry. The potentil of C. odort nd P. pupureum in remedtion of the site needs to be further exploited. Acknowledgements AAO cknowledges the Acdemy of Sciences for the Developing World (TWAS) nd the Chinese Acdemy of Sciences (CAS), for fellowship support. The Pollution Ecology group of the Institute of Applied Ecology, Shenyng, Chin, heded by Prof Li Peijun is hereby cknowledged for their support nd provision of fcilities throughout my sty in Chin. 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