Effect of pond ash on ground water quality: a case study

Ef fect of pond ash on ground water quality: a case study I.V. Suresh Disaste r Manage me nt Institute (DMI), Paryavaran Parisar, Bho pal, India C. Padmakar, Prabha Padmakaran, M .V.R.L. M urthy, C.B. Raju and R.N. Yadava Re gio nal Re se arc h Labo rato ry (CSIR), Bho pal, India K. Venkata Rao Vijayawada The rmal Po we r Statio n (VTPS), Ibrahimpatnam, India The potential problems and their consequences due to fl y ash disposal have been well studied around the world. Ash pond is a common available disposal facility for thermal power plants. The pond ash is subjected to weathering and the ions present in ash migrate to the soil and subsequently to the ground water over a period of time. A study has been carried out at Vijayawada Thermal Power Station (VTPS), Andhra Pradesh, India, to monitor the ground water quality in order to determine the potential impact of ash ponds. It has been found that ground water quality is deteriorated due to the presence of fl y ash ions (macro and micro such as Fe, Ca, Mg etc.) which were leached out from the ash up to some extent. The contamination is likely to increase in the case of toxic and other ions with the passage of time. The presence of vegetative cover and plant growth on the down stream slope and fl y ash ponds which are covered by soil may effectively control the leaching of ions. Enviro nme ntal Manage me nt and He alth 9 / 5 [ 1998] 2 0 0 –2 0 8 © MCB Unive rsity Pre ss [ ISSN 0956-6163] [ 200 ] Introduction F ly a sh is pr odu ced a s a r esu lt of coa l com bu stion in th er m a l power pla n ts a n d disch a r ged in a sh pon ds. In th er m a l power pla n t boiler s, th e in or ga n ic m in er a l con ten t of coa l is con ver ted in to a m or ph ou s gla ssy m a ter ia l du e to com bu stion of coa l a t 1,3001,350°C a n d devitr ified a s a r esu lt of h igh viscosity. Cu r r en tly, m or e th a n 60 m illion ton n es of a sh per a n n u m a r e pr odu ced fr om differ en t th er m a l power sta tion s in In dia , wh ich w ill tou ch th e figu r e of 100 m illion ton n es by th e n ext cen tu r y. Th e pr edom in a n t m eth ods for fly a sh disposa l in developin g cou n tr ies a r e a sh settlin g ta n k s, du m pin g or dir ect disposa l in loca l w a ter w ays. Th ese pon d w a ter s con ta in m a n y solu ble ca tion s/ a n ion s th a t a r e r elea sed fr om th e gla ss m a tr ix of th e a sh . After settlin g, w a ter w ith its h igh er qu a n tity of tota l dissolved solids (TDS) m ay eith er en ter in to r iver or str ea m or pa r tly seep in to th e gr ou n d w a ter. It h a s been r epor ted by Ma lek et a l. (1983) th a t fly a sh con ta in s h igh er con cen tr a tion s of B, Co, Cr, Cd, Mo, N i, As, a n d Se th a n n or m a lly fou n d in soils. Th e m ost en vir on m en ta l con cer n com es fr om th e a bove a for esa id h eavy m eta ls in fly a sh . Th e lea ch in g poten tia l of th ese h eavy m eta ls fr om a n open system (fly a sh pon ds) is expected to be gr ea ter du e to diu r n a l a n d sea son a l va r ia tion s in tem per a tu r e, m oistu r e con ten t, a n d oth er pa r a m eter s. Sin ce a ll th e m eta ls of fly a sh a r e in th e pr ior ity pollu ta n ts list (USE PA, 1993), th eir su ita bility a n d lea ch in g poten tia ls w ill be expected to be h igh . It h a s been deter m in ed by Ru ssel (1981) th a t lon gter m lea ch in g of fly a sh u sin g low pH w a ter r elea sed su bsta n tia l a m ou n ts of N a , K, Al, S, As, Mo, Se, a n d V in to th e solu tion ph a se. Oth er stu dies by N a tu sch et a l. (1975) in dica te th a t N a , S04, As, Se, Mo, Cr, a n d P b levels wer e h igh er in fly a sh a ffected gr ou n d w a ter th a n in sa m ples fr om u n a ffected a r ea s. Ou t of m a n y types of pa r ticles pr esen t in a sh , th e gla ss-lik e pa r ticles a r e r ela tively in solu ble in w a ter. Bu t, th e en r ich ed su r fa ce elem en ts on th ese pa r ticles is solu ble a n d h en ce ava ila ble to th e en vir on m en t on lea ch in g. Toxicity stu dies su ggest th a t th r ou gh lea ch in g fl y a sh m ay a dver sely a ffect w a ter ecosystem s, wh ile th e solid m a ter ia ls em itted to th e a tm osph er e m ay be h a za r dou s to ter r estr ia l ecosystem s by dir ect exter n a l r ea ction s (sk in , eyes etc.) or by r ea ction s in th e r espir a tor y tr a ct. In th e developed n a tion s su ch a s USA, th e gr ou n d w a ter qu a lity m a ps a r e r ecor ded fr om tim e to tim e a n d well m a in ta in ed to k eep a close w a tch on th e w a ter qu a lity in or der to en for ce en vir on m en ta l pr otection law s (Ch u gh , 1996). ln th e pr esen t stu dy it h a s been pr oposed th a t it is ver y a ppr opr ia te to in itia te sim ila r stu dies in a ll th er m a l power sta tion s th r ou gh ou t In dia to k eep a ch eck on gr ou n d w a ter qu a lity to fu lfil th e r equ ir em en ts of en vir on m en ta l pr otection law s. Study area Th e Vijayaw a da Th er m a l Power Sta tion (VTP S) is loca ted a t Ibr a h im pa tn a m , 16Km aw ay fr om th e Ra ilw ay city, ca lled Vijayaw a da , An dh r a P r a desh , In dia . VTP S a sh pon d site togeth er w ith 13 sa m plin g sta tion s a r e pr esen ted in F igu r e 1. M ethods and materials Th e fly a sh u n der stu dy w a s collected fr om th e a sh pon d of Vijayaw a da Th er m a l Power Sta tion , Vijayaw a da (VTP S). Soil a n d gr ou n d w a ter sa m ples wer e collected fr om differ en t loca tion s cover in g a bou t 10k m s fr om th e a sh pon d of VTP S. Ch em ica l con stitu en ts of th e soil, a sh a n d w a ter sa m ples wer e ca r r ied by well esta blish ed m eth ods u sin g a tom ic a bsor ption spectr oph otom eter (AAS), dir ect cu r r en t pla sm a (DCP ) em ission spectr om eter, a n d fla m e ph otom eter. Wa ter a n a lysis k it w a s u sed for m ea su r in g pH a n d electr ica l con du ctivity a t th e site. Den sity w a s m ea su r ed by th e specifi c gr avity bottle m eth od. Ava ila ble N, P, S a n d exch a n gea ble K in soil a n d fly a sh sa m ples wer e exa m in ed by th e sta n da r d m eth ods (J a ck son , 1973; Su bba Ra o, 1993). Ava ila ble Cu , Fe, Zn a n d Mn wer e deter m in ed by th e DTPA (dieth ylen e tr ia m in e pen ta a cetic a cid) extr a ction m eth od (Gu pta , 1993; Lin dsay a n d N or vell, 1978). Abou t 10gm fly a sh w a s sh a k en w ith 20 m l DTPA extr a ctin g solu tion . Th e solu tion w a s fi lter ed a n d th e con stitu en ts deter m in ed u sin g AAS a n d DCP. X-r ay pow der diffr a ction a n a lysis w a s ca r r ied ou t by th e P h illips diffr a ctom eter m odel 1710 u sin g Cu K r a dia tion a n d n ick el filter a t 40KV a n d 20m A. Th e iden tifica tion of m in er a l ph a ses w a s don e w ith th e h elp of Min er a l Pow der Diffr a ction fi le J CP DS a n d ASTM diffr a ction da ta . In fr a r ed spectr oph otom eter m odel 984 G of M/ s Per k in -E lm er, UK I.V. Sure sh, C. Padmakar, Prabha Padmakaran, M.V.R.L. Murthy, C.B. Raju, R.N. Yadava and K. Ve nkata Rao Effe c t o f po nd ash o n gro und wate r quality: a c ase study Enviro nme ntal Manage me nt and He alth 9 / 5 [1 9 9 8 ] 2 0 0 –2 0 8 w a s u sed for m ea su r in g IR spectr a l lin es by con ven tion a l KBr pellet m eth od. Results and discussions Che mic al c o mpo s itio n o f po nd as h T h e ch em ica l com p osit ion of p on d a s h is sh ow n in Ta ble I w h ich h a s a lk a lis (N a 2O + K 2O) in t h e r a n ge of 1.5 – 2.3 w t p er cen t a n d a lk a lin e r a r e ea r t h ’s (Ca O + MgO) less t h a n 3.0 w t p er cen t (P r a b h a et a l., 1994). T h e m a jor con st it u en t s a r e SiO 2 (59 – 61 w t % ) a n d a lu m in a (28 – 29 w t % ). Fe 2O 3 d oesn ’t exceed 5.5 w t % . In a d d it ion t o t h e a b ove, p on d a sh sa m p les h ave m icr o-n u t r ien t s s u ch a s Cu , Fe, Zn , Mn a n d m a cr o-n u t r ien t s lik e ava ila ble n it r ogen (n it r it es), p h osp h or u s, p ot a ssiu m , sod iu m a n d su lp h u r (Ta ble II). T h e va lu es in Ta ble II sh ow som e of t h e Figure 1 Lo c atio n map o f sampling statio ns ne ar ash po nd Hillocks HYDRABAD VUAYAWADA CAPITAL THERMAL POWER STATION Fly as h Pond (About 180 Acres ) 10 TRILOCHANAPURAM N AGRICULTURAL LAND 7 KOTA MULAPADU S 8 QUALITY STONE CRUSHER 11 MULAPADU GUDEM 9 3 NH 9 NH 9 2 J UPUDI EAST 4 J UPUDI SDA SCHOOL 5 1 6 Table I Che mic al c o mpo sitio n o f po nd ash sample s o f VTPS (wt%) LOI 0.50 – 2.50 SiO2 Al2 O3 Fe 2 O3 Na 2 O K2 O CaO M gO 59.0 – 61.0 28.0 – 28.8 2.70 –5.52 0.24 – 0.50 1.26 – 1.76 0.7 – 1.0 1.40 – 1.90 [ 201 ] I.V. Sure sh, C. Padmakar, Prabha Padmakaran, M.V.R.L. Murthy, C.B. Raju, R.N. Yadava and K. Ve nkata Rao Effe c t o f po nd ash o n gro und wate r quality: a c ase study Enviro nme ntal Manage me nt and He alth 9 / 5 [1 9 9 8 ] 2 0 0 –2 0 8 Table II Available mac ro -nutrie nts and mic ro -nutrie nts in po nd as sample s o f VTPS Name of macro-nutrient Total (ppm) Available N2 – do – P – do – K – do – S 155 014 007 040 Name of micro-nutrient Total (wt%) Available (ppm) Cu Fe Zn Mn 0.087 – 0.102 1.90 – 3.8 0.008 – 0.042 0.02 – 0.06 0.40 – 00.76 4.0 – 14.50 0.6 – 20 0.60 – 2.80 – 180 – 045 – 019 – 121 Figure 2 X-ray diffrac tio n patte rns o f fly ash sample s fro m VTPS Key – MULLITE – QUARTZ Relative Intens ity (I/I0 ) – MAGNETITE 10 20 30 40 50 60 70 2∅ Figure 3 Infrare d spe c tra o f re pre se ntative fly ash sample s fro m VTPS tota l m icr o-n u tr ien t s su ch a s Cu , Fe, Zn a n d Mn wh ich a r e in th e for m of both lea ch a ble a n d n ot ea sily lea ch a ble ion s r espectively. Abs orption 495 1092 790 3800 3000 Wave Number (Cm –1 ) [ 202 ] 1900 1100 540 394 300 Mine ralo gy and mic ro -struc ture o f fly ash F ly a sh con sists of m ostly a m or ph ou s gla ssy ph a ses of SiO 2 a n d a lu m in o-silica te in th e poor ly cr ysta llin e m u llite for m . X-r ay pow der diffr a ction a n a lysis a n d IR spectr oph otom etr y h ave con fir m ed th e pr esen ce of a lph a qu a r tz a n d m u llite (F igu r e 2 a n d 3). Fe is pr esen t m ostly in th e for m of Ma gn etite h avin g d(Å) = 2.5 (F igu r e 3). A pa r t of it is in m olten sta ge a n d for m s a coa tin g on th e su r fa ce of th e a lu m in o-silica te cen o-sph er es (F igu r e 4). Th e ch a n ces of m olten ir on pr esen t in sph er ica l sh a pe ca n n ot be r u led ou t. Sca n n in g electr on m icr o-gr a ph s of va r iou s sa m ples su ggest th e pr esen ce of sph er ica l a n d n ea r sph er ica l sh a pe pa r ticles w ith h a r dly a n y cr ysta llin e str u ctu r e or ph a se sepa r a tion (F igu r e 4). I.V. Sure sh, C. Padmakar, Prabha Padmakaran, M.V.R.L. Murthy, C.B. Raju, R.N. Yadava and K. Ve nkata Rao Effe c t o f po nd ash o n gro und wate r quality: a c ase study Enviro nme ntal Manage me nt and He alth 9 / 5 [1 9 9 8 ] 2 0 0 –2 0 8 Crystal struc ture Th e SiO 2 r ich ph a se is cr ysta llin e a n d h a s th e tetr a h edr a l str u ctu r e a s sh ow n in F igu r e 5. Th e cr ysta l str u ctu r e of th e sph er ica l pa r ticles ca n be expected to be m ostly disor der ed beca u se of th e a m or ph ou s n a tu r e of th e m a ter ia l wh ich for m ed a s a r esu lt of su per coolin g of th e pa r tia lly fu sed silica te/ a lu m in o-silica te pr esen t in th e coa l. Alu m in o- silica te n et- Figure 4 SEM mic ro graph o f flyash (VTPS) Si-O-M or Al-O-M; wh er e M – N a , K, B, Ca , Mg, Zn , Cu , N i, P b, As. X-r ay pow der diffr a ction pa tter n (F igu r e 2) a n d IR spectr a (F igu r e 3) h ave clea r ly sh ow n th e a bsen ce of ca r bon a tes or spin a l. Hen ce th e F igu r e 5 a n d 6 r epr esen ts th e tr u e str u ctu r e of fiy a sh . Weathering of fly ash and its effec t on soil and ground water in the vic inity of ash pond It h a s been n oticed th a t pH of pon d a sh va r ies fr om 7.09 to 8.63, electr ica l con du ctivity r a n ges fr om 0.017 to 0.036m m h os/ cm , specific gr avity 1.63 to 1.83 a n d or ga n ic m a tter 0.73 to 1.94 w t% w ith a n in cr ea se in dista n ce u p to 650/ 700 m etr es aw ay fr om th e disposa l poin t th a t is cover in g th e en tir e br ea dth of th e pon d (Ta ble III a n d F igu r e 1). It w a s r epor ted ea r lier th a t th e ch lor ide, su lph a tes, bica r bon a tes, or ga n ic m a tter, w a ter extr a cta ble solids a n d electr ica l con du ctivity va lu es of fly a sh a r e decr ea sed pr ogr essively fr om th e su r fa ce of th e pon d w ith a n in cr ea se in depth of th e a sh pon d (Ra ju , 1993). Su ch a situ a tion sh ow s th e possibility of w a ter con ta m in a tion wh en ever th e w a ter ta ble r ises h igh . Th e test r esu lts of gr ou n d w a ter sa m ples collected fr om a bou t 13 sta tion s over a dista n ce of 10k m fr om th e a sh pon d of VTP S a r e given in Ta ble IV. Th e TDS of gr ou n d w a ter h a s been pr esen ted in F igu r e 7 a s con tou r s. An a lysis of th ese r esu lts sh ow a n in cr ea se in th e ca lciu m h a r dn ess (96-298ppm ), tota l h a r dn ess (168-904ppm ), Ma gn esiu m (17-147ppm ), Cl¯ (56-499ppm ) a n d tota l a lk a lin ity 105- 10 µm Figure 5 Crystal struc ture ne two rk o f silic a Figure 6 Crystal struc ture o f alumino silic ate glass in flyash Key : Si wor k h olds m a n y ca tion s a n d a n ion s in th e va ca n t spa ces (F igu r e 6). Th e va r iou s ca tion s lik e N a , K, B, Ca , Mg, Zn , Cu , N i, P b a n d As a r e a tta ch ed to Si/ Al th r ou gh oxygen “O”. At th e sa m e tim e, som e of th ese ca tion s occu py va ca n t spa ces a s sh ow n in th e F igu r e 6. : O2 Table III Physic o Che mic al analysis re sults o f po nd ash VTPS Samples distance from disposal point (meters) 700 650 550 400 300 200 pH Electrical conductivity (mmhos/ cm) Specific gravity Organic carbon (wt%) Organic matter (wt%) 8.63 8.54 7.24 7.09 7.10 7.40 0.036 0.032 0.025 0.021 0.017 0.019 1.836 1.755 1.702 1.660 1.630 1.680 0.425 0.461 0.503 0.713 0.754 1.128 0.733 0.794 0.867 1.229 1.229 1.944 Key ∅: M : Si (or) Al : O2 [ 203 ] I.V. Sure sh, C. Padmakar, Prabha Padmakaran, M.V.R.L. Murthy, C.B. Raju, R.N. Yadava and K. Ve nkata Rao Effe c t o f po nd ash o n gro und wate r quality: a c ase study Enviro nme ntal Manage me nt and He alth 9 / 5 [1 9 9 8 ] 2 0 0 –2 0 8 Table IV Charac te ristic s o f gro und wate r ne ar ash po nd site (VTPS) Regulatory body M in. M ax. M ean Desirable limit (ppm) Zn 0.01 Pb 0.01 Fe 0.10 Na 100 K 20 Ca 38.6 Ca hardness 96.6 Total hardness 168 Mg 17.4 Chloride 56.8 Total alkalinity 105 pH 6.5 1.30 0.05 4.20 155 170 129.5 298 904 147 499 533 7.5 0.17 0.03 1.30 122.8 81.18 85.72 214.18 457.45 59.22 270.30 314.2 7.0 5.00 0.05 0.30 – – 75 300 300 – 250 200 6.5–8.5 Elements USEPA (1976) ES ISI (1983) – – – 200 – 200 – – 125 250 – 6.5–8.0 – – – 175 12 – – 100-500 125 250 – 6.5–8.0 115 NR 1.00 – – 200 600 600 125 1,000 600 6.5–9.2 Number of samples exceeding limits Nil Nil 5 Nil Nil Nil Nil 3 1 Nil Nil Notes: US = US standards; ES = European standards; ISI = Indian standards; NR = no relaxation 533ppm (Ta ble IV). A m a r gin a l r ise in th e con cen tr a tion of Zn (0.01 to 1.30ppm ) a n d P b (0.01-0.05ppm ) a r e n oticed. High er va lu es of Fe u p to 4ppm sh ow th a t th e lea ch a bility of Fe is a s h igh a s 40 tim es. Th e effect of pon d a sh on a lk a li ion s N a a n d K in gr ou n d w a ter a ppea r s to be n ot ver y sign ifica n t (Ta ble IV). Th is m ay pr oba bly be du e to h igh er ion ic r a dii of N a a n d K ion s wh ich a r e r ea dily exch a n ged to th e soil a n d w a ter slu r r y. F r om th e lea ch in g stu dy of fly a sh a n d ch em ica l a n a lysis of th is w a ter solu ble m a ter ia l, it h a s been n oted th a t a ll of th e m a jor elem en ts pr esen t in th e fly a sh a r e a lso pr esen t in its w a ter solu ble fr a ction s. Th e a m ou n t of w a ter solu ble fr a ction s in differ en t a sh es va r ies sign ifica n tly. Th er e is n o sign ifi ca n t cor r ela tion between th e com position of a sh a n d w a ter solu ble fr a ction of a sh . Th e m ovem en t of th e ca tion s Ca a n d Mg a n d th e tota l h a r dn ess follow a n in cr ea sin g tr en d a t th e loca tion s in th e or der 5 > 1 > 6 wh er ea s ch lor ide h a ppen s to be a t its m a xim u m va lu e a t th e loca tion -l wh ich m ea n s, Cl¯ Figure 7 Co nto ur plo t o f TDS c o nc e ntratio n TDS 0.40 4.40 8.40 12.40 16.40 29.20 48.40 29.20 25.23 25.23 21.26 20.40 24.40 28.40 32.40 36.40 40.40 44.40 21.26 8 9 17.29 4 17.29 2 3 13.31 13.31 5 9.34 9.34 1 5.37 5.37 1.40 1.40 0.40 [ 204 ] 4.40 8.40 12.40 16.40 20.40 24.40 28.40 32.40 36.40 40.40 44.40 48.40 I.V. Sure sh, C. Padmakar, Prabha Padmakaran, M.V.R.L. Murthy, C.B. Raju, R.N. Yadava and K. Ve nkata Rao Effe c t o f po nd ash o n gro und wate r quality: a c ase study Enviro nme ntal Manage me nt and He alth 9 / 5 [1 9 9 8 ] 2 0 0 –2 0 8 is m or e loca lized h er e th a n a t loca tion s 5 a n d 6 (F igu r es 8 a n d 9). If we con sider th e loca tion s 7, 4, 3, 9 a n d 8 th er e is a r e gu la r tr en d in th e pr esen ce of both ca tion s a n d a n ion s (F igu r es 10-11). In gen er a l, loca tion N o. 3 h a s m a xim u m qu a n tities of ca tion s a n d a n ion s a s com pa r ed to th e oth er loca tion s. Wh en th e loca tion s 8, 9 a n d 3 a r e on ly con sider ed it is seen th er e is a r e gu la r fa ll in th e con cen tr a tion s of Cl¯, Ca , Mg a n d tota l h a r dn ess a s 8 < 9 Figure 8 Mo ve me nt o f mac ro nutrie nts (a) Concentration (mg/I) 800 600 400 200 0 0 2 4 6 8 10 Sampling points Key Ca T.hardne Na K < 3. Th ese r esu lts a r e sh ow n in F igu r es 6-12 a n d th e m ovem en t of th e ion s h a s som e bea r in g on th eir ion ic r a diu s, ion exch a n ge ca pa city, geologica l ter r a in a n d pH of th e fly a sh . Th e bigger th e ion ic r a diu s of elem en ts, th e h igh er is th e r a te of th eir exch a n ge. Apa r t fr om sligh t solu bility in w a ter, fly a sh is ch em ica lly ver y sta ble a n d th er e is n o deter ior a tion on exposu r e to th e a tm osph er e. F u r th er m or e, sin ce th e solu ble con ten t becom es fi xed by pa r ticipa tion in th e pozzola n ic a ction , w a ter pa ssin g over or th r ou gh th e a sh is u n lik ely to pick u p sign ifica n t qu a n tities of a n y com pou n d th a t wou ld lower th e qu a lity of str ea m or gr ou n d w a ter. Th e pa r a m eter s th a t gr ea tely a ffect th e lea ch in g pr ocess a lso in clu de soil textu r e, pH, pa r ticle size, th e pr esen ce of ch ela tin g a gen ts in soil, r a tio of fly a sh to th e solu tion ’s tem per a tu r e, pr esen ce of lea ch a te collection system s a n d th e or igin of fly a sh . Exc hange of ions from soil/ fly ash to plants Con cen tr a tion of solu ble elem en ts in soil h ave sh ow n a n u pw a r d tr en d by a ddin g m or e fly a sh to it (P a ge et a l., 1979). It is essen tia lly du e to th e fa ct th a t th e solu ble fr a ction of elem en ts com in g fr om fly a sh a r e r ea dily a bsor bed a n d r eta in ed by th e soil in or der to en h a n ce gr ow th of pla n ts. Soybea n , la dy’s fin ger, pea s a n d ben ga l gr a m h ave sh ow n en cou r a gin g gr ow th r a te in th e fly a sh (30 – 90 w t% ) a m en ded soil (RRL, Bh opa l, 1996). Th e edible pa r ts of th e th ese pla n ts wer e a n a lyzed for Fe, Mg, N i, Cu , Zn , N a , K wh ich h ave sh ow n h igh er u pta k e of th ese ion s wh en com - – Cl Mg Figure 1 0 Mo ve me nt o f mic ro nutrie nts (a) Figure 9 Mo ve me nt o f mac ro nutrie nts (b) Concentration (mg/I) Concentration (mg/I) 4 500 400 3 300 2 200 1 100 0 0 4 2 6 8 10 0 0 Sampling points 4 2 6 8 10 Sampling points Key Ca T.hard Na K Mg – Cl Key Zn Pb Fe [ 205 ] I.V. Sure sh, C. Padmakar, Prabha Padmakaran, M.V.R.L. Murthy, C.B. Raju, R.N. Yadava and K. Ve nkata Rao Effe c t o f po nd ash o n gro und wate r quality: a c ase study Enviro nme ntal Manage me nt and He alth 9 / 5 [1 9 9 8 ] 2 0 0 –2 0 8 pa r ed to th e cr ops gr ow n on con tr ol soil (Ta ble V). In a ddition to th e h igh er con cen tr a tion of th e a bove ion s in th e edible pa r ts of th ese pla n ts, th e r a te of u pta k e of th e elem en ts va r ied fr om pla n t to pla n t. Th is m ay be du e to m eta bolic r ea ction s a t th e r oots of th ese pla n ts a n d by con tr ollin g a ssim ila tion of solu ble elem en ts by pla n ts (Adr ia n o et a l., 1980). F u r th er, a ddition of m in er a ls su ch a s Figure 1 1 Mo ve me nt o f mic ro nutrie nts (b) Concentration (mg/I) 5 4 3 2 1 0 0 4 2 8 6 10 Sampling points Key Zn Pb Fe Figure 1 2 Princ ipal c o ntro ls o f fre e me tal c o nc e ntratio ns in so il so lutio ns (adapte d fro m Mattigo d e t al., 1 9 8 1 ) Mas s Trans fer Ion Exchange and Ads orption Precipitation & Dis s olution of Solids Free Metal Concentration in s oil s olution Redox Reaction Acid-Bas e Reaction Biological Reaction [ 206 ] Complex Formation low gr a de r ock ph osph a te en h a n ced th e gr ow th pa tter n of pea s a n d oth er pla n ts ow in g to th e in ter a ction of ph osph a te ion w ith som e of th ese elem en ts lea din g to a n in cr ea se in th eir lea ch a bility. Th e a bove stu dies in dica te a possible m eth od of con tr ollin g th e seepa ge of va r iou s ion s to th e gr ou n d w a ter by selective ve geta tion a n d system a tic pla n t gr ow th on a sh pon ds a n d fly a sh a m en ded soils. Th is exer cise w ill fu r th er r edu ce th e pollu tion of gr ou n d w a ter. Th e envir on m en ta l pa th w ays of a ll pollu ta n ts ca n be pr edicted a s a ser ies of even ts. On ce th e con stitu en ts a r e r elea sed to th e a qu eou s ph a se, th ey m ay dir ectly be a bsor bed by pla n t r oots or th ey m ay lea ch to th e su bsu r fa ce. If th ey a r e a bsor bed by th e pla n ts, th en th ey w ill r em a in fixed u n til th e pla n ts a r e con su m ed by a n im a ls or decom posed. In th e la tter ca se th e con stitu ten ts a r e r elea sed ba ck to th e soil. If th e con stitu en ts a r e r elea sed in to th e su bsu r fa ce en vir on m en t, th ey pa r ticipa te in sever a l ch em ica l a n d h ydr ologic pr ocess. Th e com bin ed effects of su ch ph ysica l, ch em ica l a n d h ydr odyn a m ic pr ocesses con tr ibu te to decr ea se th e con cen tr a tion of th e solu tes r elea sed fr om th e w a ste a s a fu n ction of dista n ce fr om th e poin t of a pplica tion . Th e tr a n spor t of pa r ticu la r ch em ica l species in ter r estr ia l system s is of in ter est to a va r iety of scien tists (Bower a n d Wilcox, 1965; Cole, 1980), sin ce m ea su r em en t or r epor tin g of tota l con cen tr a tion of a pa r ticu la r in or ga n ic com pou n d (E n field et a l., 1980) in th e soil m ay be m islea din g in m a n y en vir on m en ta l m a n a gem en t situ a tion s. Toxic effects of tr a ce m eta ls m ay be a ffected m or e by th eir ch em ica l for m th a n by th eir tota l con cen tr a tion (F lor en s, 1977). Th er efor e m a th em a tica l m odels ca pa ble of sim u la tin g th e distr ibu tion of in or ga n ic pollu ta n t species in soil a n d gr ou n d w a ter system s a r e va lu a ble tools for a n a lysin g con ta m in a n t pa th w ays. An eva lu a tion of th e fa te of in or ga n ic com pou n ds in soil a n d gr ou n d w a ter r equ ir es a deta iled con sider a tion of th e ph ysica l, ch em ica l a n d biologica l pr ocesses a n d r ea ction s in volved su ch a s com plexa tion , a dsor ption , pr ecipita tion , oxida tion -r edu ction (Ma h ier et a l., 1980), ch em ica l specia tion a n d biologica l r ea ction s (F igu r e 12) to deter m in e th e fr ee m eta l con cen tr a tion in soil solu tion s. Th ese pr ocesses ca n a ffect su ch ch a r a cter istics a s species solu bility, ava ila bility for biologica l u pta k e ph ysica l tr a n spor t a n d cor r osion poten tia l (Lym en et a l., 1982; P r ick ett et a l., 1981) E n vir on m en ta l m on itor in g com pr isin g collection a n d a n a lysis of gr ou n d w a ter, su r fa ce r u n -off, a n d th e lea ch a te a n a lysis of a sh ta k en fr om w ith in th e a sh pon d sh ow s th a t fl y I.V. Sure sh, C. Padmakar, Prabha Padmakaran, M.V.R.L. Murthy, C.B. Raju, R.N. Yadava and K. Ve nkata Rao Effe c t o f po nd ash o n gro und wate r quality: a c ase study Enviro nme ntal Manage me nt and He alth 9 / 5 [1 9 9 8 ] 2 0 0 –2 0 8 Table V Elemental c onc entration (ppm) in edible portions of c rops grown on pure soil and 9 0 per c ent fly ash Elements Soybean Control F.A. Lady’s finger Control F.A. Peas Control F.A. Bengal gram Control F.A. Calcium M agnesium Sodium Potassium M anganese Iron Nickel Copper Zinc 900 2,000 3,020 2,500 70 425 10 16 40 1,900 1,820 1,050 4,550 13 175 8 11 32 1,100 1,400 4,500 1,435 30 235 10 19 77 1,500 1,700 1,435 3,100 80 350 8 13 45 850 2,100 3,820 4,850 50 300 21 31 70 2,200 1,850 1,200 4,700 25 200 10 16 37 2,750 2,300 1,800 3,315 23 150 15 13 35 2,700 1,500 3,315 3,750 61 100 21 17 30 Notes: F.A. = fly ash; Control = soil without flyash a sh pon d does n ot n ecessa r ily detr im en ta lly a ffect gr ou n d w a ter con cen tr a tion s. However, poten tia l im pa ct of fl y a sh pon d on th e loca l en vir on m en t m ay gen er a lly a r ise ou t of w in d er osion , su r fa ce w a ter er osion , dissolu tion by su r fa ce r u n -off, r a in a n d su bsequ en t per cola tion to gr ou n d w a ter. Per cola tion of w a ter th r ou gh fly a sh pon ds gen er a lly yield h igh a lk a lin e solu tion (pH: 8-10) th a t w ill r estr ict h eavy m eta l lea ch in g. Th e con cer n , h en ce, lies on th e lon gevity of th is su ffer in g con tin u a l r a in fa ll in filtr a tion or gr ou n d w a ter in tr u sion . Acid extr a ction pr ocedu r es, su ch a s th e USE PA, E P -toxicity test (sim u la tes th is lon g-ter m con dition in a n a ggr essive ba tch equ ilibr iu m lea ch in g test) in dica te th a t th e efflu en t fr om th ese fly a sh pon ds a r e w ill w ith in lim its a s pr escr ibed by USE PA (1976) by a t lea st on e or der of m a gn itu de for a ll m eta ls of con cer n except ir on . In or der to m in im ize th e occu r r en ces of su ch en vir on m en ta l pr oblem s w ith str u ctu r a l fly a sh pon d, it is a dvisa ble to r estr ict th e r a te of w a ter per cola tion by a pr oper ly design ed dr a in a ge a n d collection system . Conclusions • N ea r th e a sh pon d th e gr ou n d w a ter qu a lity is ch a n ged ow in g to th e lea ch in g of solu ble ion s pr esen t in fly a sh . • Addition of fl y a sh to th e n a tive soil lea d to a n in cr ea se in th e ava ila bility of n u tr ien t ion s lik e Cu , N i, Zn , Fe, P, K a n d N a a n d en h a n ced gr ow th of pla n ts. • E xter n a l er osion du e to w in d, r a in a n d w ave a ction ca n a lso be con tr olled by a su ita ble ve geta tive cover on th e dow n str ea m slope wh ile pr otectin g th e u pstr ea m slope. Adequ a te spillw ay or r u n off diver sion s m u st be pr ovided a n d w ill be m a in ta in ed pr oper ly. • Selection of pa r ticu la r type of pla n ts a n d th eir pla n n ed gr ow th , wou ld con tr ol th e m igr a tion of m eta llic ion s to th e gr ou n d w a ter. Avoidin g h igh in pu ts of fly a sh in soil a m en dm en t sch em es for better cr op gr ow th a n d in tr odu ction of m eta bolic m ech a n ism s wou ld con tr ol th e lea ch a bility of solu ble ion s a n d r edu ce m igr a tion of va r iou s elem en ts to th e gr ou n d w a ter. References Adr ia n o, D.C., Woodlor d, T.A. a n d Cir avelo, T.G. (1978), J En viron qu a lity, Vol. 7, p. 416. Adr ia n o, D.C., P a ge, A.L., E lseew i, A.A., Ch a n g, A.C. a n d Str a u gh a n , I. (1980), “Utiliza tion a n d Disposa l of fl y a sh a n d oth er coa l r esidu es in ter r estr ia l ecosystem – a r eview ”, J En viron Qu a lity, Vol. 9, p. 33. Am er ica n Society of Civil E n gin eer s (1979), “Solid Wa ste r esea r ch n eeds for em er gin g coa l tech n ologies”, in Proc of th e A S CE, P RC-E P RI Wor k sh op, Sa n Die go, CA, ASCE P RC, N ew Yor k , N Y. Bower, C.A. a n d Wilcox, L.V. (1965), “Solu ble sa lts in m eth ods of soil a n a lysis”, Bla ck , C.A. (E d.), A m er ica n S ociety of A gron om y, Ma dison , WI, pp. 947-8. Cen tr a l Boa r d of Ir r iga tion a n d Power (1995), Wor k sh op on “F ly Ash Utilisa tion ”, 11-12 Ma r ch , N ew Delh i, In dia . Cen tr a l Boa r d of Ir r iga tion a n d Power (1996), Sem in a r on “F ly Ash Utiliza tion ”, 26-27 Ma r ch , N ew Delh i, In dia a n d US Agen cy for In ter n a tion a l Developm en t. Ch u gh , P. (1996), “F ly a sh u tiliza tion in USA”, P r esen ted in th e sem in a r on ‘fl y a sh u tilisa tion ’, 26-27 Ma r ch 1996, h eld a t N ew Delh i (In dia ). Cole, C.R. (1980), In for m a tion in th e MMT/ VVT Model, Ba ttlle P a cifi c N or th west La bor a tor y, Rich la n d, Wa sh . 99352. E n fi eld, C.G., Ca r sel, R.F., Coh en , S.Z., P h a n , T. a n d Wa lter s, D.M. (1980), A pprox im a tin g [ 207 ] I.V. Sure sh, C. Padmakar, Prabha Padmakaran, M.V.R.L. Murthy, C.B. Raju, R.N. Yadava and K. Ve nkata Rao Effe c t o f po nd ash o n gro und wate r quality: a c ase study Enviro nme ntal Manage me nt and He alth 9 / 5 [1 9 9 8 ] 2 0 0 –2 0 8 The authors express their sincere thanks to Professor T.C. Rao, Director, CSIR, for his kind permission to publish the work. The authors are also highly thankful to the Environmental Engineers of VTPS for their co-operation and the Central Board of Irrigation and Power, New Delhi for fi nancial support of this project. [ 208 ] pollu ta n t tra n spor t to Grou n d Wa ter, USE PA, RSKE RL, a da , Ok la F lor en s, T.M. (1977), “Tr a ce m eta l species in fr esh w a ter s”, Wa ter R es. Vol. 11, pp. 681-7. Gu pta , V.K. (1993), “An a lysis of soils for ava ila ble m a jor n u tr ien ts”, in Ta n don , H.L.S. (E d.), M eth od s of A n a lysis of S oils, Pla n ts, Wa ter a n d Fer tiliz er, Fer tilizer Developm en t a n d Con su lta tion Or ga n isa tion , N ew Delh i, pp. 36-48. ISI (1983), Dr in k in g Wa ter S ta n d a rd s, In dia n Sta n da r d In stitu te P u blica tion N o. 10500 J a ck son , M.L. (1973), S oil Ch em ica l A n a lysis, P r en tice-Ha ll of In dia P r iva te Lim ited, N ew Delh i. Lin dsay, W.L. a n d N or vell, W.A. (1978), “Developm en t of DTPA soil test for zin c, ir on , m a n ga n ese a n d copper ”, S oil S ci. S oc. A m . J., Vol. 42, p. 421. Lym en , W.J ., Reeh l, W.F. a n d Rosen bla n t, D.H. (1982), Ha n d b ook of Ch em ica l Proper ty M eth od s, Mc Gr aw -Hill, N ew Yor k , N Y. Ma h ier, R.J ., Bin gh a m , F.T., Sposito, G. a n d P a ge, A.L. (1980), “Ca dm iu m en r ich ed sew a ge slu dge a pplica tion to a cid a n d ca lca r eou s soils: r ela tion between tr ea tm en t ca dm iu m in sa tu r a ted extr a cts a n d ca dm iu m u pta k e”, J. En viron . Qu a l., Vol. 9, pp. 359-64. Ma lek , R.I.A., Lica str o, P.H. a n d Roy, D.M. (1983), M a ter ia ls R esea rch S ociety Proceed in gs S ym posia , P ittsbu r g, PA, Vol. 65, pp. 269-84. Ma ttigod, S.V., Sposito, G. a n d P a ge, A.L. (1980), “F a ctor s a ffectin g th e solu bilities of tr a ce m eta ls in soils”, Ch em istr y in th e En viron m en t, Am er ica n Society of Agr on om y, Soil Scien ce Society of Am er ica , ASA Specia l P u blica tion N o. 40. Natu sch , D.F.S., Ba u er, C.F., Matu siewicz, H., Eva n s, C.A., Ba ker, J., Lok , A. a n d Lin ton , R.W. (1975), Proceedin gs of th e In ter n ation al Con feren ce on Heavy M etals in En viron m en t, Tor on to, Ca n a da , pp. 553-76. P a ge, A.L., E lseew i, A.A. a n d Str a u gh a n , I. (1979), R es id u e R ev, p. 71. P r a bh a P a dm a k a r a n , Ra ju , C.B. a n d Su bba Ra o, A. (1994), “Ch a r a cter isa tion of fly a sh to a sses its su ita bility for Agr icu ltu r a l pu r poses”, Clay R esea rch , Vol. 13, pp. 30-7. P r ick ett, T.A., N aym ik , T.G. a n d Lon qu ist, C.G. (1981), A Ra n dom Wa lk Solu te Tr a n spor t Model for Selected Gr ou n d w a ter Qu a lity E va lu a tion s, Bu lletin 65, Illin ois Sta te Wa ter Su r vey, Ch a m pa ign , IL. Ra ju , M.V.S. (1993), In d ia n J. En viron . Hlth , Vol. 35 N o. 1, pp. 9-14. Re gion a l Resea r ch La bor a tor y (1996), F in a l r epor t of th e pr oject “F ly a sh Ch a r a cter isa tion a n d Utiliza tion ” spon sor ed by CBIP, Bh opa l, N ew Delh i. P lu m b, R., J r (1981), P r oceedin gs for Ha n dlin g a n d Ch em ica l An a lysis of Sedim en t a n d Wa ter Sa m ples. USE PA/ Cor ps of E n gin eer s Tech n ica l Com m ittee on Cr iter ia for dr edged a n d fill m a ter ia l, Vick sbu r g, MI. Su bba Ra o, A. (1993), “An a lysis of soils for ava ila ble m a jor n u tr ien ts”, in Ta n don , H.L.S. (E d.), M eth od s of A n a lysis of S oils, Pla n ts, Wa ter a n d Fer tiliz er, Fer tilizer Developm en t a n d Con su lta tion Or ga n isa tion , N ew Delh i, pp. 13-35. USE PA (1976), Qu a lity Cr iter ia for Wa ter, Wa sh in gton , DC. USE PA (1993), Sta n da r ds for th e Use or Disposa l of Sew a ge slu dge: F in a l r u les. 58 F R 9391-9392. Office of th e Feder a l Re gister. N a tion a l Ar ch ives a n d Recor ds Adm in istr a tion , Wa sh in gton , DC. Wor ld Hea lth Or ga n isation (WHO) (1984), Gu idelin es for Drin k in g Water Qu ality, Vol. 1, Gen eva .