a five-year study on the heavy-metal.pdf

8/13/2019 A FIVE-YEAR STUDY ON THE HEAVY-METAL.pdf

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~ PergamonPlh S0043-1354(97)00171-1

Wat. Res. Vol. 31, No. 12, pp. 3017-3028, 1997 1997 ElsevierScience Ltd. All rights reservedPrinted in Great Britain0043-1354/97 17.00 + 0.00

A F IV E - Y E A R S T U D Y O N T H E H E A V Y - M E T A LP O L L U T IO N O F G U A N A B A R A B A Y

S E D I M E N T S R I O D E J A N E I R O , B R A Z I L)A N D E V A L U A T I O N O F TH E M E TA L

B IO A V A I LA B IL IT Y B Y M E A N S O F G E O C H E M I C A LS P E C I A T I O N

G. PER IN @l*, R. FABRI S 1, S. MAN ENT E I, A. REBELLO WA GE NE R 2,C. HAM ACH ER 2 and S. SCOTTO j

~Ca'Foscari University of Venice, Dept. Environmental Sciences, Dorsoduro 2137 Venezia, Italy; and2Pontificia Universidade Catolica de Rio de Janeiro (PUC), Rio de Janeiro, BrazilReceived January 199C accepted in revised for m April 1997)

Abstract--Surface sediments of the Guanabara Bay (Rio de Janeiro, Brazil) were analyzed by a sequentialextraction procedure for Cd, Cr, Cu, Pb, Zn, Mn and Fe, determining their distribution among fivegeochemical phases and in the nitric acid extractable phase. Bioavailable phases and non-bioavailablephases have been determined in six transects in the bay to define the significant evel of pollution due tosediment meLal contamination. A multiple correlation showed limited responsibility of Mn and Fe oxidesand humic acids in the adsorption process, which allowed discrimination among the different processesand suggested the strong influence of the hydrogen sulfide present in the highly reduced bay bottomenvironment. The authors suggest the need to avoid disturbing bottom sediment by dredging or byartificial bottom aeration which could result in a rapid worsening of the environment due to the acceleratedformation of more soluble oxygenated metal compounds making the toxic metals much more availableto the benthic fauna and to the bay biota in general. 1997 Elsevier Science LtdKey words--.sediments, heavy metals, sequential extraction, metal bioavailability, iron and manganeseoxides

INTRODU TIONThis research is a five-year invest igation to evaluatethe bi oavailability of the toxics buried in the surficialsediments in a tropical environment. The main aim isto identify the care needed in cleani ng very pollutedwater bodies witheut disturbing the delicate ecosys-tem. This paper reports the results of the researchdone in the Baia de Guanabara (Rio de Janeiro,Brazil) regarding the bioavailabil ityand the dynamicsof heavy metals The role of Mn and Feoxides/hydroxides was analyzed and, indirectly, thatof the hydrogen sulfide in metal distribution andrelease.Heavy metals are widely spread in the waterenviron ment, and the sediment, being their final fatein the water bodies, has been investigated frequentlyfor the metal content. Usually, only the total metalis determined in the sediments, giving only a roughapproach to the un derst andin g the role of metals aspollutan ts in ecotoxicology because, normall y, therebioavailability s net considered. It is well known thatwater pollutants, sinking on the sediments, can bebonded to the inorganic /organic matrices by adsorp-tion processes; the intensity can be predicted by ma ny

ecotoxicological constants (e.g. Ka or partitioncoefficient of the compound between sediment andwater, K~ or the Kd corrected for the organic carboncontent) (Schwarzenbach et a l . , 1993). For metals,the main processes are the co-precipi tation and theco-reaction with oxides and hydroxides of manganeseand iron, humic acids, sulfides and clays (Foerstnerand Wit tma nn, 1981; Schoer, 1985; Belzile et a l . ,1989).

These processes may occur at the same time or theymay develop successively on the gra in coatings of thesediment. In some cases, one may prevail over theothers, depe nding on envir onment al conditions ofpH, redox potential, oxygen availability, etc.

Metal availability depends on the strongestadsorber/ligand; in a complex system like pollutedsediments, the roles played by the Mn and Fe oxides,clay structures, humic acids, the most importantgeochemical matrices in an environment similar tothe one studied, and sulfide are not easily defined.There is a strong partition co mpetition in terms of K~among different surfaces (Mn and Fe oxides, highmolecular weight humic acids, clays) and a ligandcompetition among the same structures and the

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3018 G. Per in e t a l .s u l fi d e i o n s . B e c a u s e t h e p a r t i t i o n s e e m s t o t a k e p l a c ei n a f e w d a y s , t h e r e f o r e r e l a t i v e l y r a p i d l y , o n e c o u l dc o n s i d e r t h e f i rs t p r o c e s s ( p a r t i t i o n ) v e r y c l o s e t o a ne q u i l i b r i u m a t a f ir s t a p p r o x i m a t i o n .

E a c h g e o c h e m i c a l p h a s e ( G P H ) s e em s t o h a v ed i ff e re n t a d s o r p t i o n c o n s t a n t s , a s r e p o r t e d b y O a k l e ye t a l . ( 19 8 1) . H y d r o u s M n o x i d es e x h i b it m o r ee x t e n s i v e i s o m o r p h i c s u b s t i t u t i o n t h a n a m o r p h o u sF e o x i d e s a n d , t h e r e f o r e , s h o w c o n d i t i o n a l e q u i -l i b ri u m c o n t a n t s ( f o r C u a n d C d ) o f o n e o r t w oo r d e r s a s c o m p a r e d t o t h o s e o f b e n t o n i t e c la y , F eo x i d e s o r h u m i c a c i d s . D e s p i t e t h e r e l a t i v e s m a l la m o u n t n o r m a l l y p r e s e n t in th e s e d i m e n t ( O a k l e ye t a l . 1 9 8 1 ) M n o x i d e p l a y s a n i m p o r t a n t r o l e i nm e t a l a d s o r p t i o n . H o w e v e r , i n th e c a s e o f v e r y a n o x i cs e d i m e n t s , h y d r o g e n s u l f id e c o u l d b e t h e m a i nd e t e r m i n i n g f a c t o r b e c a u s e o f t h e v e r y lo w s o l u b i l i t yc o n s t a n t s ( K s ) o f t h e s u lf i d e o f t h e m o r e i m p o r t a n th e a v y m e t a l s i n v o l v e d i n s e d i m e n t p o l l u t i o n .T h e r e f o r e , a s t r o n g c o m p e t i t i o n i s e x p e c t e d t o e x i s ta m o n g t h e in v o l v e d p a r a m e t e r s.

T h e p u r p o s e o f th e r e s e a r c h h a s b e e n , t h e r e f o r e ,t h e d e t e r m i n a t i o n o f t h e f a c t o rs i n v o l v e d i n m e t a ls i n k i n g i n t h e B r a z i l i a n - t r o p i c a l w a t e r b o d y i n o r d e rt o g e t i n f o r m a t i o n o n e n v i r o n m e n t a l r is k s d u r i n g t h ep o s s ib l e r e c o v e r y o f t h o s e e n v i r o n m e n t s u s i n gs t a n d a r d t e c h n i q u e s s u ch a s b o t t o m d r e d g i n g o r d e e pa e r a t i o n .

M TERI LS ND METHODSC h a r a c t e r i s t i c s o f t h e c a s e s t u d i e s

G u a n a b a r a B a y c a n b e c o n s i d e r e d a s a n e s t u a r y o f380 km2 be tween the c i t ie s o f R io de Jan e i ro a nd Ni te ro i ,l o c a t e d i n t h e c e n t e r o f t h e m e t r o p o l i t a n r e g i o n o f R i o d eJ a n e i r o , w i t h a p o p u l a t i o n o f m o r e t h a n 8 m i ll i o n . T h e b a yrece ives 91 t r ibu ta r ies and i t s d ra inage bas in (abou t11,000 km2) has a wa te r f low of 150 m3 s w i t h a n e x c h a n g er a t e o f a b o u t 1 0 w i t h t h e o c ea n . O r i g i n al l y , t h e e c o s y s te mo f t h e b a y w a s a m a n g r o v e f o r e s t w i t h m u d f i a t s a n d b a n k s .N o w a d a y s , t h e m a n g r o v e f o r e s t h a s a l m o s t c o m p l e t e l yd i s a p p e a r e d . M a n y i n d u s t r i e s a r e l o c a t e d i n t h e b a y a r e a .Spec ia l emph as i s mus t be g iven to the two o i l r e f ine r ies andt o t h e m a n y s h i p y a r d s m o s t l y i n t h e n o r t h - e a s t r e gi o n . D u eto in tens ive por t ac t iv i t i e s , connec ted wi th the o i l indus t ry ,o i l sp il l s a re a f re quen t p rob lem as we l l a s t ank c lean ings inthe bay . The indus t r i a l d i scharges o f sewage and p rocessw a s t e s r e p r e s e n t a p r i n c ip a l s o u r c e o f p o l l u t i o n o f t h e b a yw a t e r s a n d c a n a c c o u n t f o r 2 5 o f t h e o r g a n i c p o l l u t i o na n d m o r e t h a n 9 0 o f t h e c h e m i c a l p o l l u t io n . T h e b a y ist h e r e c e p ta c l e t a n k o f a b o u t 1 8 m3 s of domes t ic sewage ,w i t h a s e c o n d a r y t r e a t m e n t m a d e o n o n l y 2 5 o f t h e t o t a l.L a r g e a m o u n t s o f m e t a l s a r r i v e i n t o t h e b a y t h r o u g h t h er ive rs (Rego e t a l . 1993).A t t h e w a t e r s u r f a c e , G u a n a b a r a B a y h a s a v e r y h i g ho x y g e n l ev el , s o m e t i m e s u p t o 3 0 0 o f s a t u r a t io n d u e t o t h eh i g h p r i m a r y p r o d u c t i v i t y a c c o r d i n g t o t h e h i g h n u t r i e n tl e v e l a n d t h e t r o p i c a l c o n s t a n t h i g h t e m p e r a t u r e a n dava i lab i l i ty o f l igh t . A t the bo t tom (3 -19 m) , the d i s so lvedoxygen i s c lose to ze ro . Sed imenta t ion ra tes appear to beh i g h i n r e c en t y e ar s ( M o r e i r a a n d G o d o y , 1 98 8 ) r a n g i n ga r o u n d 0 .1 5 c m / y r u n t i l 1 9 5 0 a n d t h e n s u d d e n l y i n c r e a s in gto ab ou t 1 .3 cm/yr .T h e s e d i m e n t h e a v y m e t a l p o l l u t i o n i n t h e b a y h a s b e e ns t u d i ed b y D e L u c a R e b e U o et a l . (1986). The resea rches o fD e S o u z a e t a l . (1986) and P er in e t a l . (1993) dea l t w i th th e

geochemica l spec ia t ion in some a reas o f the bay , g iv ing ap r e l i m i n a r y f r a m e o f t h e m a i n p o l l u t i o n s o u r ce s .S a m p l i n g a n d a n a l y s e s

T h e s a m p l i n g p o i n t s h a v e b e e n c h o s e n a l o n g t h e m a i ncur ren t s in the bay a long s ix t r ansec t s , a s shown in F ig . 1 .T h e s a m p l i n g s w e re d o n e a l o n g t r a n s e c t s w h i c h f o ll o w t h em a i n t i d a l c u r re n t s i n t h e b a y a n d a r e d i v i d e d i n to t h e m a i nt r a n s e c t ( o r n u m b e r 1 ) a n d b r a n c h t r a n s e c t s ( f r o m n u m b e r2 to number 6 ) , in o rde r to show the in f luence o f then e a r s h o r e d i s c h ar g e s . E a c h b r a n c h t r a n s e c t e n d s i n th e m a i nt ransec t .T h e m a i n t r a n s e c t s t a r ts i n t h e m o r e i n t e r n a l w e s te r n p a r to f t h e b a y r o u n d i n g t h e I l h a d o G o v e r n a d o r ( I n t e r n a t i o n a lA i r p o r t ) , c r o s s e s t h e w h o l e b a y a l o n g t h e m a i n c u r r e n td i r e c t i o n a n d e n d s i n f r o n t o f C o p a c a b a n a b e a c h r e c e iv i n g ,a long i t s way , the o the r t r ansec t s . T ransec t 2 has beens e t t l e d i n t h e N o r t h , i n t h e v e r y i n t e r n a l p a r t o f t h e b a ybeyond the Paque ta ' i s l e . T ransec t 3 i s loca ted c lose to thee a s t e r n p a r t o f t h e b a y r e c e i v i n g t h e w a t e r s o f t h e R i oG u a p i r i m , G u a r a i ' , G u a r a i - M i r i m a n d G u a x i n d i b a u n t i lS e t e P o n t o s a n d N e v e s , m e e t i n g th e m a i n t r a n s e c t i n S t a t i o n1 4. T r a n s e c t 4 c o n t r o l s t h e s e d i m e n t s b e t w e e n t h e l l h a d oF u n d f i o u n t i l t h e I l h a S t a . C r u z . T r a n s e c t 5 m o n i t o r ss e d i m e n t q u a l i ty i n t h e a r e a b e l o w t h e P r e s i d e n t e C o s t a a n dS i l v a b r i d g e , a l o n g t h e c o a s t o f I l h a d a s C o b r a s a n d t h eS a n t o s D u m o n t A i r p o r t . F i n a l l y , t r a n s e c t 6 c o n t r o l s t h eN i t e r o i B a y ( E n s e a d a d o S a c o S ~ o F r a n c i s c o a n d E n s e a d ad e J u r u j u b a ) .Samples were t aken wi th a Pe te r sen d redge , ge t t ing thef i r s t 4b cm of su r f i c ia l sed ime nt ( represen t ing , the re fo re , thelas t 30-35 years o f sed imenta t ion) , ca re fu l ly sc reened fo rd e t e r m i n i n g t h e p r e s e n c e o f a n i m a l s a n d f o r c h e c k i n g t h eco lo r , the s t ruc tu re a nd th e smell , then pu t in g lass j a r s andf r o ze n . D e p e n d i n g o n t h e b o t t o m s t r u ct u r e , e a c h s t a t i o n w a ssampled severa l t imes (min imum th ree ) to ge t a r ep resen ta -t ive sample ob ta ined by ca re fu l ly mix ing the d i f fe ren tsub-samples . S ix ty -one s ta t ions were de te rmined in the bayd u r i n g t h e 1 0 c a m p a i g n s ( 1 9 9 1 - 1 9 9 5) a n d 5 1 u s ed f o r t h et ransec t ana lys i s .

F i g . 1 . G u a n a b a r a B a y - - s a m p l i n g s t a t i o n s , t r a n s e c t s andpol lu t ion sources .


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He a vy- me t a l po l l u t i on i n Gua na ba r a Ba y 3019The sequent ia l ext rac t ion procedure was a s l ight lymod i f i e d ve r s i on o f t he t e c hn i que a s p r opo s e d by Ch e s t e rand Hughes (1967) and Tess ier e t a l . (1979) . Recen t papersconf i rmed the soundness o f the metho d (Sager , 1989; Rub io

e t a l . 1993) . The f ive GPH s ob t a i ne d h a ve t he s a m eme a n i ngs a s i n Che n e t a l . (197 6) : i .e . phase 1 ,i on - e xc ha nge a b l e me t a l ; pha s e 2 , me t a l bonde d t ocarbona tes ; phase 3 . eas ily-reducible me ta l (bonded tooxides of manganese and non-crys ta l l ine la t t ice i ron) ; phase4, meta l bonde d to o rganics and sulf ides ; phase 5 , reduciblemeta l (bonded to i ron oxides) remaining af ter the coat ingdes t ruc t ion by oxida t ive t rea tm ent o f phase 4 . Tota l meta lcontent was de termined in two di f ferent ways: by hot n i t r ica c i d tr e a t me n t ( a n t h r opoge n i c pha se ) a nd by HF + HNO3dissolut ion in a Tef lon conta iner . The geochemical phaseswe r e c al l e d GPHs , i nd i ca t i ng wi t h a num be r t he e x t r a c ti ons tep . The suf f ixes HNO3 or a and HF or b indica te thegeochem ical phases ob ta ined by t rea tm ent wi th n i t r ic ac idand wi th hydrof luor ic ac id in a sea led Tef lon conta iner( b o m b ) .The G PH s w e r e de t e r mi ne d a s f ol lows . Te n g r a ms o f d r ys e d i me n t wa s t r e a te d wi t h 40 ml o f 1 M NH4O H, s ha ke n f o r1 h, sett led ove rnigh t, f i l tered with 0.45-/~m fil ter, w ashedthree t im es with disti l led w ater metal-free; the residue (1)was dr ied overnig ht ~.t 105C. This so lu t ion co nta ined thef ir s t GPH . Th ree gram s of the residue (1) was m ixed wi th40 ml o f 1 M Na OA c p l u s 1 ml o f H Ac , s ha ke n f o r 2 h ,sett led for two nights, f i l tered and washed. This solutionconta ined the second GPH. The res idue (2) was dr iedovern ight l ike res idue (1). Al l the res idue (2) was m ixed wi th40m l NH 2OH - HC I i n 0 . 01 M HNO3, s ha ke n f o r 45 mi n ,sett led for two night, ; , f i l tered and washed. This solutionconta ined the th i rd GPH. The res idue (3) was dr iedovernight l ike res idue (1) . Al l the res idue (3) , t rea ted wi th6 ml of 0 .02 M HNO3 plus 10 ml o f 30% H202, was ac id i fiedwi th HNO3 a t pH 2 , hea ted to 75C for 2 h and mixed wi th3 0 % H 2 0 2 at pH 2 . The m ixture was heated for 4 h in anoven. Af te r cool ing , i t was m ixed together w i th 15 ml o f3 .2 M NH 4OA c in 20% (v/v) HNO3, and se t t led for twonights . This c leared solu t ion conta ined the four th G PH . Theres idue (4) , washed accura te ly , was dr ied in an ovenovernig ht l ike res idue (1) . Final ly , the res idue (4) was mixedwi t h 40 ml o f 0 .04 M NH 2O H' H CI i n 25% HA c , he a t e d t o98C fo r 5 h, sett led for tw o nights and fi l tered. Th iss o l u t ion c on t a i ne d t he f if th GP H. Fo r t he de t e r mi na t i on o fthe to ta l anthro pogen ic m eta l content , 10 g of the or ig ina lsediment was t rea ted w i th HNO3 conc. a t 150C in a Tef lonconta iner sea led wi th a Tef lon cap (Tef lon Bomb) in anove n , mi xe d wi t h e nough H 2 0 2 to e l iminate the N204 vaporsa nd d i l u t e d t o 100 ml . Fo r H F t o t a l me t a l c on te n t , 0 .5 g o fdry sedim ent was t rea ted in a Tef lon conta iner sea led wi tha Te f l on c a p ( Te f l on Bomb) i n a n ove n wi t h 0 . 5 ml o fdist il led water , 1 .5 ml of conc ent ra ted H F and 3 .0 ml ofaqua regia (HCI conc . + HN O3, 3 :1). Al l the solu t ions wereexamined by f lame a tomic absorpt ion analys is (Spect ra AA250 plus, Varian).The h igh concentr~.t ion of hydrog en sulf ide in the baysediments prevented a co r rec t quant i ta t ive analysis o f thefree sulfide because, dLespite of th e v ery care ful sam plings,the sample loses H2S dur ing the sampl ing and the s torage .Because the H2S conten t var ies be tween 0 . 01 and0.53 mo l /kg fo r the wet sediment, as ac id vola t i le sul fidede t e r mi ne d a c c o r d i ng t o D i Tor o e t a l . ( 1992 ) , t o a vo i dsulfide doubtful analyses, a regression analysis was preferredto ge t a cor re la t ion matr ix for the f ive more impor tantmeta ls (Cr , Cu, Ni , Pb, Zn) and the d i f ferent forms of Feand M n presen t as l igands in the sediment. In such a way,the autho rs t r ied to g ive account , indirec tly , of the sul fiderole . Vola t i le so l ids (VS, humic ac ids indica tors) a l so hasbeen inc luded in the matr ix . Data on the c lay d is t r ibut ionhave not been inc luded because former research done byMa r a b i n i e t a l . (1994) showed in the in terna l and in thecent ra l par t o f the bay an hom ogen ous presence o f pe l ite .

Fo r a c ompa r i s on o f po l l u t i on le vel s i n Gua na ba r a Ba ywi t h a f o r me r i nve s t i ga t i on i n o t he r wa t e r ( Foe r s t ne r a ndW it tmann , 1981) , the analyt ica l da ta have been t rea tedsumming the resul t s f rom the f i r s t , second and th i rd GPHst o ge t t he b i o - a va i l a b l e pha s e ( BAP) a nd f r om t he f ou r t ha nd f i ft h t o ob t a i n t he no n - b i oa va i l a b le pha s e ( NBAP) . T h i sp r oc e du r e i mpr ove s t he me t a l i mme d i a t e b i oa va i l a b l e(M IBA ) sediment c lass if ica tion propo sed in a former paper(Per in e t a l . 1993) where on ly the fi rs t and second G PH swere used as b ioava i labi l i ty cr i te r ia . As show n by P er in e t a l .(1986) in carbonate- r ich sediments , a la rge amount ofcarbonate i s again present in the th i rd GPH and, therefore ,i t mus t be t a ke n i n t o a c c oun t . F r o m now on t he me t a l s w i llbe i de n t i f i e d a s BAP a nd NBAP de pe nd i ng i f t he y a r ei nc l ude d i n t he EGPH 1 , 2 , 3 o r EGPH 4 , 5 ( s um o f t hevalues of the geochem ical phases 1 , 2 and 3 or 4 and 5 ,respectively).

RESULTST h e r e s u l t s o f th e i n v e s t i g a t i o n s a r e s h o w n i n

T a b l e s 1 , 2 a n d 3 a n d i n F i g s 2 - 5 . F i g u r e s 2 a n d 3d e s c r ib e t h e b e h a v i o r o f Z n , M n , C r , C u , N i a n d P ba l o n g t h e m a i n t r a n s e c t ( T r a n s e c t 1 ) f r o m t h e i n t e r n a lp a r t o f t h e b a y u n t i l th e e s t u a r y g a t e w a y a s B A P s .F i g u r e s 4 a n d 5 s h o w t h e s a m e m e t a l s b u t a s N B A P s .T a b l e 1 s h o w s t h e r e s u lt s o f in v e s t i g a t i o n o n t r a n s e c t s2 , 3 , 4 , 5 a n d 6 . T a b l e 2 d i s p l a y s t h e d e s c r i p t i v es t a t is t ic a l a n a l y s i s o f t h e s e d i m e n t m e t a l d i s t r i b u t i o ni n t h e d if f e r e n t G P H s a n d t h e v a l u e s o f t h e V S . I ns o m e G P H s t h e v a l ue s w e r e b el o w t h e i n s t r u m e n t a ld e t e c t i o n l i m i t o r s c a r c e l y s i g n i f i c a n t a n d , t h e r e f o r e ,h a v e b e e n n o t c o n s i d e r e d i n t h e t a b l e . D u e t o t h ee x t r e m e ly l o w c o n c e n t r a t i o n o f C d ( m o s t l y b e l o w t h ei n s t r u m e n t a l d e t e c t i o n l i m i t ) t h e G P H s v a l u e s a r e n o tr e p o r t e d h e r e b u t i t s c o n c e n t r a t i o n w i ll b e d i s c u s s edl a t e r i n t e rm s o f t o t a l H N O 3 - e x t r a c t a b l e m e t a l( T a b l e 4 ) , w h e n t h e r i s k l e v e l c l a s s i f i c a t i o n o f t h eG u a n a b a r a s e d i m e n t s w i ll b e c o n s i d e r e d . F o r t h ep u r p o s e o f d e f i n in g q u a l i t y l i m i t s f o r s e d i m e n t s , t h ea u t h o r s t r i e d t o p r e p a r e a r e fe r e n c e t a b l e , c o m b i n i n ga n d e x t r a p o l a t i n g t h e v a l u e s o f t h e s e d i m e n t p a r t i t i o na p p r o a c h ( S P A ) ( C h a p m a n , 1 98 9; J o n k e r s a n dE v e r t s , 1 99 2; W e b s t e r a n d R i d g w a y , 1 9 9 4; C h a p m a ne t a l . 1 9 9 6 ) w i t h t h e d r e d g e d s e d i m e n t l a n d d i s p o s a lc r i t e r ia ( O n t a r i o M i n i s t r y o f E n v i r o n m e n t , 1 9 88 ).O n e m o r e l e v e l w a s i n c l u d e d t o g e t a m o r e d e t a i l e dc l a s s if i c a ti o n b e t w e e n t h e n o - r i s k l e v e l a n d t h em a x i m u m - r i s k l e v e l ( M R L ) a s r e p o r t e d b y J o n k e r sa n d E v e r t s ( 1 99 2 ). T h e p r e s e n t a u t h o r s a r e a w a r e t h i sk i n d o f c l a ss i f ic a t i o n c o u l d n o t b e p e r f e c t b e c a u s eS P A i s m o r e s i g n i f i c a n t i n t h e o r g a n i c p a r t i t i o ne q u i l i b r ia , b u t i t c o u l d b e a r e f e r e n c e p o i n t s i m p l e a n de a s y t o b e u s e d . A c c o r d i n g t o T a b l e 3 , a f i n al T a b l e 4h a s b e e n p r e p a r e d s h o w i n g t h e p e r c e n t a g e o fG u a n a b a r a B a y s e d i m e n t s i n t h e s p e c if i c r i sk l e v e l.

M u l t i p l e r e g r e s s i o n a n a l y s i s m a t r i c e s ( T a b l e 5 )s h o w t h e c o r r e l a t i o n c o e f f i c ie n t s a m o n g t h e d i f f e re n tm e t a l s i n t h e d i ff e r e n t p h a s e s r e g r e s s e d a l s o t o F e a n dM n e x t r a ct e d b y t h e T e f l o n B o m b p r o c e d u r e ( i.e .d i s s o l v e d i n H F ) . T a b l e 6 s h o w s t h e c o r r e l a t i o n sa m o n g t h e H N O 3 - e x t r a c t e d m e t a l s ( a n t h r o p o g e n i cp h a s e ) a n d t h e H F - e x t r a c t e d F e a n d M n . B o t h


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3 0 2 0 G , P e r i n et alTable 1 . Sum of the GPHs in the t ransec t s 2 , 3 , 4 , 5 a n d 6 m g / k g d . w . )

S u m o f G P H s 1 , 2 a n d 3 S u m o f G P H s 4 a n d 5Stat ion C r C u N i P b Z n M n C r C u N i P b Z n M nTransect 22 2 < d l < d l < d l < d l 1 5 4. 4 3 0 5 .92 3 < d l < d l < d l < d l 1 9 2. 9 2 7 4 .52 4 < d l < d l < d l < d l 1 46 .1 5 1 0 .52 5 < d l < d l < d l < d l 1 76 .1 3 7 0 .2

7 < d l < d l < d l < d l 8 5. 0 2 6 4 .4Transect 32 6 < d l < d l 9 , 5 6 < d l 1 0 4 .6 1 6 7 .42 7 < d l < d l < d l < d l 8 5 .9 2 2 7 5. 72 8 < d l < d l 8 . 4 4 < d l 1 0 2 .5 7 2 9 5. 12 9


5/12

H e a v y - m e t a l p o l l u t i o n in G u a n a b a r a B a yT a b l e 2 . G u a n a b a r a B a y s e d i m e n t s - - d e s c r i p t i v e s ta t is t ic a l a n a l y si s o f t h e m e t a l d i s t r ib u t i o ni n d i f f e re n t G P H s ( a l l v a l u e s i n m g / k g d . w . )

Coef f i c i en tM e t a l P h a s e M i n M a x M e d i a n M e a n o f v a r i a t i o nCr 4 th 0 .0 186 .5 18 .7 24 .5 127 .8Cr 5 th 0 .0 10 .4 0 .0 1 .4 190 .3C r H N O 3 1 .9 2 7 9 . 2 4 1 . 7 5 9 . 7 9 1 . 6C r H F 0 . 2 3 2 2 . 0 6 8 . 4 8 1 . 5 8 1 . 0Cu 4 th 0 .0 138 .8 18 .4 28 .4 113 .3Cu 5 th 0 .0 20 .3 0 .0 1 .9 200 .7C u H N O 3 0 . 0 4 7 8 . 0 5 2 . 0 8 7 . 8 1 1 9 . 7C u H F 0 . 0 2 4 2 . 0 6 0 . 8 7 9. 5 7 6 . 8Ni 4 th 0 .0 16 .7 7 .0 6 .5 69 .1Ni HN O3 5 .0 60 .8 24 .1 24 .5 35 .8N i H F 6 . 4 8 0 . 4 3 5 . 2 3 4 . 2 3 7 . 5Pb 4 th 0 .0 139 .3 23 .3 27 .6 99 .2P b 5 t h 0 . 0 5 6 . 8 0 . 0 4 . 4 2 2 9 . 9P b H N O 3 4 . 7 4 6 0 . 0 7 2 . 8 1 2 0 . 0 9 8 . 4Pb H F 18 .2 556 .0 100 .5 122 .9 79 .77 n 1st 0 .0 10.3 1.1 1.8 134.87 n 2 r i d 0 . 0 1 5 7 .5 3 4 . 3 4 7 . 0 9 0 . 77 n 3 r d 0 . 0 4 5 2 . 3 6 7 . 8 8 5 . 8 1 0 6 . 72 'n 4 th 0 .0 25 6 .7 7 4 .5 85 .5 75 .37 n 5 t h 0 . 0 2 6 0 . 9 2 2 . 0 6 5 . 5 1 1 7 . 8Z n H N O 3 1 0 . 4 1 6 6 0 2 4 2 . 0 3 8 4 . 0 9 3 . 67 n H F 8 . 6 9 4 0 . 0 0 . 0 2 3 7 . 5 8 4 . 3M n Is t 0 .0 95 .7 5 .6 13 .9 141 .0M n 2 n d 0 . 0 3 5 4 . 3 4 2 . 7 6 6 . 5 1 1 2 . 0} / In 3 rd 0 .0 719 .8 72 .2 110 .2 115 .8M n 4 t h 0 . 0 5 8 5 . 7 1 1 8 .8 1 5 8 . 0 8 9 . 0M n 5 th 0 .0 43 .4 13 .3 12 .4 85 .5M n H N O 3 1 3 . 2 1 6 0 0 4 3 7 . 0 5 1 2 . 3 6 7 . 9M n H F 2 5 . 6 1 4 1 0 4 3 8 . 8 4 6 6 . 8 6 4 .9Fe 1 t 0 .0 72 .1 0 .0 5 .2 260 .9F e 2 n d 0 . 0 2 7 2 4 2 1 .1 1 4 8 . 0 2 9 0 . 2F e 3 r d 0 . 0 8 4 1 7 2 2 4 0 2 5 1 0 8 8 . 2F e 4 t h 0 . 0 2 0 , 8 8 0 5 5 8 8 6 1 8 6 7 8 . 2F e 5 t h 0 . 0 9 5 8 5 3 3 2 8 3 2 7 0 5 8 . 6F e H N O 3 1 1 6 0 8 3 , 8 0 0 3 6 , 5 5 0 4 2 , 2 1 0 4 9 . 6F e H F 1 2 72 1 0 9 , 0 0 0 5 4 , 0 2 0 5 1 , 1 0 0 5 4 . 7Vola t i l e so l id s 0 .7 26 .0 17 .0 15 .2 37 .6

3 0 2 1

M n o x i d e a s t h e m a i n f a c t o r in o x i d i c se d i m e n t m e t a la b s o r p t i o n .

T h e r o l e p l a y e d b y c la y s , c o m p a r e d w i t h t h a t o f t h eM n a n d F e o x i h y d r o x i d e s , s e em s t o b e l e ss im p o r t a n tb u t w o r t h c o n s i d e r i n g ( T u i n a n d T e l s, 1 99 0) . I ns a l t - w a t e r s e d i m e n t s t h e v a l u e s o f K d r a n g e b e t w e e n4 3 .0 f o r t h e C u t o 1 .1 f o r C d , l o w v a l u e s i f c o m p a r e dwi th the Kd va lue o f M nO2 (7339 and 15 ,re s pec t ive ly ) .

I n r e d u c e d s e d i m e n t , t h e p r e se n c e o f h y d r o g e ns u l f i d e c o m p l i c a t e s t h e m e t a l s i n k i n g p r o c e s s e sb e c a u s e i t a l l o w s t h e f o r m a t i o n o f a s e r ie s o fequi l ibr ia l ike Me(OH)2ads~:~Me(OH)2uee~=: ,M e + + + 2 O H - a n d M e + + + H S - ~ * ~ M e ( H S ) + a n dM e + + + n S - . * ~ M e ( S ) ~ - 2 ) - , w h e r e t h e f i r st t e r m

r e p r es e n t s t h e m e t a l h y d r o x i d e a d s o r b e d o n t h e M nh y d r o x i d e . C o n s i d e r i n g t h e s o l u b i l i t y p r o d u c t s (K ~o )a s i n d i c a t o r s o f t h e s t a b i l i t y c o n s t a n t s o f t h em e t a l - l i g a n d c o m p l e x e s ( w h i ch c o u l d b e th e O H - i o no r t h e S - - , o r H S - i o n s) , i t s e em s t h a t o n l y s o m eh y d r o x i d e s c o u ld c o m p e t e w i t h t h e b i n d i n g c a p a b i l i t yo f s u l f i d e i o n s s h i f t i n g t h e e q u i l i b r i a o f t h e o t h e rm e t a l s t o w a r d s t h e f o r m a t i o n o f M e ( S) ~ - 2 )- c o m -p l e x / p r e c i p i t a t e s . A t t h e b a y w a t e r p H ( 6 - 8 ) t h e p K ao f t h e s y s t e m H 2 S / S * i s 2 2. W i t h a s u l fi d e s a t u r a t i o nv a l u e o f 0 .1 m o l / l i t e r , t h e p S v a l u e s o f t h e i n v o l v e dm e t a l s r e s u l t s ( a t p H - - 8) in n o t m o r e t h a n 1 8. 5 fo rC d , 2 8 . 5 f o r C u , b e t w e e n 1 4 a n d 2 0 f o r N i , b e t w e e n1 4. 0 a n d 1 7. 0 f o r Z n a n d 1 4. 0 f o r P b . C o m p e t i t i o nw i l l e x i s t a m o n g M n a n d F e h y d r o x i d e s a n d s u l fi d e s,

T a b l e 3 . T e n t a t i v e r i s k l e v e l c l a s s i f ic a t i o n f o r m a r i n e s e d i m e n t c a l c u l a t e d f r o mJ o n k e r s a n d E v e r t s ( 1 9 9 2 ) , O n t a r i o M i n i s t r y f o r E n v i r o n m e n t ( 1 9 8 8 ) a n dW e b s t e r a n d R i d g w a y 0 9 9 4 ) a c c o r d i n g t o m e t a l c o n c e n t r a t io n s e x tr a c t e d b y h o tc o n c e n t r a t e d n i t r i c a c i d p r o c e d u r e ( v a l u e s i n p p m )

No -r i sk l eve l 1 s t r i sk l eve l 2nd r i sk l eve l M ax im um r i sk l eve lC d < 0 . 5 0 . 5 - 5 . 0 5 . 0 - 5 0 > 5 0C r < 2 5 2 5 - 5 0 5 0 - 1 2 0 > 1 2 0C u < 0 . 7 0 . 7 . 0 7 . 0 - 7 0 > 7 0F e < 1 0 1 0 - 1 0 0 1 0 0 - 3 5 0 > 3 5 0N i < 2 5 2 5 - 3 0 3 0 - 6 0 > 6 0P b < 1 2 1 2 - 1 2 0 1 2 0 - 1 2 0 0 > 1 2 0 0Zn < 3 .5 3 ,5- -35 35 - 350 > 350

WR 31 /12 - -D


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3022 G. Perin e t a l .M A I N T R A N S E C T - 1 -

7 0 0 -6 0 0 .5 0 0 -

r. N

, - QF i g . 2 . M a i n t r a n s e c t s u m o f t h e G P H s l , 2 a n d 3 o f z i n c a n d m a n g a n e s e B A P )

w i t h e x c l u s i o n o f M n O H ) 4 p K ~o f o r t h e h y d r o x -ide = 56 ) be ing the pK,o o f M n O H ) 2 a n d F e O H ) 2 ,12 .5 and 15 .0 , r e s pec t ive ly . The c o r re s po nd i ngs u l f ide s have the pK,o be twee n 12 .0 and 17 .0 B u t l e r ,1964 ; Fe rnex e t a l . 1989).

O r g a n i c m a t t e r , a s h u m i c a c i d , h a s l o w s t a b i l i t yc o n s t a n t s f o r m e t a l s , r a n g i n g f r o m a b o u t 3 . 7 t o 4 . 0a t p H 5 a n d m = 0. 1. B e c a u s e t h e p K i s i n c r e a s i n gw i t h p H a n d d e c r e a s i n g w i t h m , i t se e m s r e a s o n -a b l e t o t h i n k t h a t h u m i c a c i d s p l a y a l i m i t e dr o l e a s c o m p l e x i n g c o m p o u n d s i n v e r y s a l i n es e d i m e n t s c o m p a r e d w i t h t h a t e x e r t e d b y t h eM n / F e - o x i d e s a n d t h e s u lf i d es S c h n i t z e r a n dKhan , 1972) .

O N L U S I O NT h e g r a p h i c s o f F i g s 2, 3 , 4 a n d 5 a n d t h e d a t a i n

T a b l e 1 s h o w , f o r t h e m a i n t r a n s e c t , h i g h l e ve ls , o f Z na n d M n p o l l u t i o n in t h e i n n e r p a r t o f t h e b a y e it h e ri n t h e B A P o r i n t h e N B A P f o r m s . C r s h o w s aw e l l - d e f in e d d e c r e a s i n g b e h a v i o r f r o m t h e i n t e r n a lp a r t t o t h e o p e n o c e a n , b u t i t s sp e c i e s a r e m o s t l yn o n - b i o a v ~ i l a b le . C u , N i a n d P b s h o w s o m e p e a k s i ns p e c if i c p o i n t s , w i t h t h e m a x i m a i n t h e a r e a c l o s e t ot h e g a t e w a y b e l o w t h e R i o - N i t e r o i b r i d g e a n db e t w e e n B o t a f o g o a n d F l a m e n g o b e a c h e s a n d t h eN i t e r o i b a y . T r a n s e c t 2 i n d i c a t e s h i g h l e v el s o f Z na n d M n , e i t h er B A P o r N B A P ; C r , C u , N i a n d P b a r ep r e s e n t o n l y a s N B A P i n r e l a t i v e ly h i g h c o n c e n -

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F i g . 3 . M a i n t r a n s e c t - - s u m o f t h e G P H s 1 , 2 a n d 3 f o r c h r o m i u m , c o p p e r , n i c k e l a n d l e a d B A P ) .


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EZO

Heavy-meta l pol lu t ion in Gua naba ra BayM A I N T R A N S E C T - 1 -

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F i g . 4 . M a i n t r a n s e c t - - s u m o f t h e G P H s 4 a n d 5 o f z i nc a n d m a n g a n e s e ( N B A P ) .

3023

t r a t i o n s e s p e c i a l l y C u ) . T r a n s e c t 3 s h o w s M n a n d N ia s t h e m o s t i m p o r t a n t m e t a l s in t h e B A P s , w h i l e P bi s t h e m o s t s i g n i f i c a n t i n t h e N B A P . T r a n s e c t 4c r o s s i n g t h e b a y f r o m w e s t t o e a s t a b o v e t h e b r i d g e )

s h o w s a c le a r l y d e c r e a si n g B A P a n d N B A P C r a l o n gt h e t r a n s e c t ; B A P a n d N B A P c o n c e n t r a t i o n s a r e ,s u r p r i s i n g l y , v e r y a l i k e . Q u i t e h i g h c o n c e n t r a t i o n s o fB A P Z n a n d M n b o t h f o r m s ) a re , a ls o , p r e s e n t i n th et r a n s e c t . T r a n s e c t 5 s h o w s t h e s t r o n g i n f lu e n c e o n t h es e d i m e n t q u a l it y o f t h e d o w n t o w n a r e a a n d o f t h e

C a n a l d o C u n h a a n d C a n a l d o M a n g u e . B o t h a r e li k es e w e r s c o l le c t i n g se w a g e a n d i n d u s t r i a l w a s t e s o f al a r g e p a r t o f R i o d e J a n e i r o . T h e i r e f fe c ts a r e c l e a r lye v i d e n t f r o m t h e s e d im e n t m e t a l p o l l u t i o n d a t a . B A PP b , B A P a n d N B A P Z n a n d N B A P C u i n d i c a t es t r o n g p o l l u t i o n s o u r c e s w h i c h i n f l u en c e th e b a y a l s oo f f - s h o re . F i n a l l y , T r a n s e c t 6 r e v e a l s t h e r o l e o f a ni n d u s t r i a l a r e a N i t e r o i ) , d i s c h a r g i n g i ts e ff l u en t s i nt h e i n n e r N i t e r o i b a y f l o w i n g i n t h e G u a n a b a r a ;a p p a r e n t l y , t h e N i t e r o i b a y i s n o t v e r y p o l l u te d , w i t h

M A I N T R A N S E C T - 1 -

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Fig. 5 . Main t ransec t--sum of the GPH s 4 and 5 of chromium, copper , n ickel and lead NBAP).


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3024 G. Perin e t a lTable 4. Distribution in different classes of risk levels of the metals in the sedimentso f Guana bara Bay referr ing to the ho t HNO3-ex tracted meta l s anthropogen icphase) and expressed as percentage o f the m oni tor ing s ta t ions )

No -risk level 1st risk level 2nd risk level M axim um risk levelC d 6 73 21 0C r 18 48 23 11C u 0 3 55 42Fe 12 88 0 0Ni 56 31 11 2Pb 7 60 33 0Z n 0 5 61 34

o n l y B A P Z n a n d N B A P P b a t r e l a t i v e l y h i g hco n cen tra t io n s .

T h e d escr ip t iv e a n a ly s i s (T a b le 2 ) sh o w s ah i g h p r e v a l e n c e o f G P H 4 , i n t h e s e n s e t h a t m o s to f C r , C u , N i a n d P b s e e m t o b e m o s t l y e x t r a c t a b l ei n t h i s p h a s e , e m p h a s i z i n g t h e r o l e p l a y e d b ysu l f id e a n d o rg a n ic m a t ter a s m a in a d so rb er /l i g a n d s . G P H 3 , i n d e e d , a c c o u n t s f o r a m i n i m u mo f 6 0 t o a m a x i m u m o f 1 00 o f t h e t o t a lex tra c ta b le m eta l fo r C r , C u , N i a n d P b . T h e v eryh ig h su l f id e /o rg a n ic m a t ter co m p lex in g v a lu es fo rth e C r , w h ich i s n o t fo rm in g su l f id e , co u ld b ee x p l a i n e d b y t h e c o - p r e c i p i t a t i o n / a d s o r p t i o n o f t h eC r o x id es w i th a n d o n F e a n d M n su l f id e . Z n , a se x p e c t e d , s e e m s t o b e d i s t r i b u t e d h o m o g e n e o u s l yin a l l th e G P H s ex cep t th e f i r s t . A re la t iv e lyb a la n ced d i s t r ib u t io n , a cco rd in g to th e i r ro l e a sa d s o r b e r , i s s h o w n b y F e a n d M n , e s p e c i a l l y i nt h e f o u r t h , s e c o n d a n d t h i r d ( M n ) g e o c h e m i c a l

sp ec ia t io n a n d in th e fo u rth , th i rd a n d f i f th G P Hf o r F e . F u r t h e r m o r e , t h e h i g h v a l u e s o f t h e G P H 5o f F e v a l id a ted th e f i f th ex tra c t io n s t ep in th es e q u e n t i a l e x t r a c t i o n a n a l y s i s a s p r o p o s e d b y C h e ne t a l 1976) .

A n a ly z in g th e w h o le b a y a s g lo b a l sy s tem , re ferr in gto T a b le 3 , a n d , th ere fo re , co n s id er in g o n ly th eso -ca l l ed a n th ro p o g en ic p h a se ex tra c ted b y h o t n i t r i ca c id , i t ca n b e seen th a t th e C u a n d Z n a re th e m a inp o l lu ta n t s , th e f i r s t o n e ex ceed in g th e M R L in th e4 2 o f t h e s t a t io n s a n d w i t h a 5 5 o f t h e v a l u e s i nt h e s e c o n d r i s k le v e l (t h e s e c o n d o n e g o e s b e y o n d t h eM R L i n t h e 3 4 a n d at t a in s t h e s e c o n d r is k l e ve l i nth e 6 2 o f th e sa m p les ) .

T h e co rre la t io n m a tr i ces (T a b les 5 , 6 , 7 a n d 8 ) g a v ea v e r y l o w r e l a ti o n a m o n g t h e f i v e m e t a l s ( a s a l r e a d yd i s c u ss e d , C d w a s n o t c o n s i d e r e d b e c a u s e o f i t sex trem ely lo w co n ce n tra t io n in a l l th e p h a ses ) a n d th ed i f f eren t sp ec i e s o f F e a n d M n p resen t in th e

T a b l e 5. GPH 3----correlation matrix amon g the phase-extracted meta l s , VS and the d if ferent spec ies o f Fe an d Mn N = 54, casewise de l e t ion o fmis s ing da ta )

C r C u Ni Pb Zn Fe Fe Fe Fe Mn Mn Mn Mn3rd 3rd 3rd 3rd 3rd Fe Mn 2nd 3rd 4 th 5 th 2nd 3rd 4 th 5 thGPH GPH GPH GPH GPH b b VS GPH GPH GPH GPH GPH GPH GPH GPHA B C D E F G H I J K L M N O P1.01) 0.94 0.92 0.60

1.00 0.95 0.681.00 0.70

1.00

0.04 --0.130.07 --0.240.10 --0.150.60 -0.23***1.00 0.13

1.00

-0 .0 8 0.87 0.01 0.00 -0 .1 0 -0 .1 3 0.19 0.10 0.06 0.27 A-0 .1 6 0.89 0.06 --0.13 --0.1 6 --0.21 0.11 0.02 --0.0 4 0.31 B-0 .1 3 0.89 0.01 0.03 -0 .0 8 -0 .1 5 0.18 0.14 -0. 01 0.27 C-0. 21 0.62 0.47 0.04 -0. 01 -0 .1 5 0.02 -0.1 1 -0 .1 4 0.12 D-0 .0 7 0.16 0.70 0.38 0.43 0.05 0.09 -0 .0 5 0.01 -0 .2 3 E

0.55 0.06 -0 .1 0 0.66 0.59 0.55 0.41 0.60 0.59 -0 .1 2 F1.0 0 0.12 -0 .0 7 0.27 0.35 0.44 0.60 0.69 0.83 0.20 G

1.00 0.11 0.10 0.07 0.06 0.32 0.24 0.21 0.39 H1.00 0.17 0.09 0.05 0.02 --0.15 -0 .1 2 --0.11 I1.00 0.57 0.41 0.43 0.62 0.33 -0 .2 6 J

1.00 0.32 0.48 0.48 0.58 -0 .2 6 K1.00 0.44 0.45 0.47 0.11 L

1.00 0.72 0.67 -0 .0 2 M1.0 I 0.69 -0. 03 N

1.00 0.04 O1.00 P*P < 0.05; ***P < 0.001.


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Heavy-metal pollutio n in Gu ana bara Bay 3025T a b l e 6 GPH 4--correlation matrix among the phase-extractedmetals,VS and the different speciesof Fe and Mn N = 59, casewisedeletionofmissing data)C r C u N i P b Z n F e F e F e F e M n M n M n M n4 t h 4 t h 4 t h 4 t h 4 t h F e M n 2 n d 3 r d 4 t h 5 t h 2 n d 3 r d 4 t h 5 t hG P H G P H G P H G F H G P H b b V S G P H G P H G P H G P H G P H G P H G P H G P HA B C D E F G H I J K L M N O P1.00 0 . 4 1 0 . 2 9 0 . 3 5 0 . 4 9 0 . 2 7 0 . 2 3 0 . 3 7 0 . 2 0 0 . 3 9 0 . 2 8 0 . 2 8 0 . 2 2 0 . 1 8 0 . 2 7 0 . 0 0 A

4

1 . 00 0 . 3 6 0 .9 1 0 . 7 4 0 . 0 7 - 0 . 1 7 0 . 3 8 0 . 6 7 0 . 2 3 0 . 4 0 0 . 0 3 0 . 0 8 - 0 . 1 1 - 0 . 0 2 - 0 . 1 0 B1 .0 0 0 . 44 0 . 1 9 - 0 . 1 2 - 0 . 0 1 0 . 92 0 . 00 - 0 . 1 0 0 .0 6 - 0 . 0 5 0 . 2 4 - 0 . 1 2 0 . 18 0 .3 1 C

1 .(1 0 0 . 6 9 0 . 0 6 - 0 . 1 3 0 .4 1 0 . 4 6 0 . 1 6 0 . 4 0 - 0 . 0 2 0 . 1 4 - 0 . 0 4 0 . 0 8 - 0 . 1 0 D1 .0 0 0 . 2 3 - 0 . 0 7 0 . 2 5 0 . 6 3 0 . 2 8 0 . 4 8 0 . 2 4 0 . 2 0 0 . 0 3 0 . 2 3 - 0 . 1 3 E

1 .0 0 0 . 5 7 0 . 0 3 - 0 . 0 7 0 . 4 8 0 . 4 2 0 . 4 0 0 . 0 6 0 . 1 0 0 . 2 5 - 0 . 0 9 F1 .0 0 0 . 0 8 - 0 . 1 9 0 . 21 0 . 2 5 0 . 3 6 0 . 3 2 0 . 3 2 0 . 5 6 0 . 1 8 G

1 . 0 0 0 . 11 0 . 1 0 0 . 0 9 0 . 0 7 0 . 2 6 0 . 1 9 0 . 21 0 . 3 9 H1 .0 0 0 . 1 4 0 . 0 7 0 . 0 4 0 . 0 4 - 0 . 1 4 - 0 . 1 1 - 0 . 1 1 I

1 .0 0 0 . 5 7 0 . 4 2 0 . 3 8 0 . 5 8 0 . 3 6 - 0 . 2 5 J1 . 0 0 0 . 3 5 0 . 4 0 0 . 4 6 0 . 5 8 0 . 2 7 K

1.00 0 .41 0 .40 0 .49 0 .10 L1 . 00 0 . 5 8 0 .7 1 - 0 . 0 2 M

1 .0 0 0 . 6 6 - 0 . 0 4 N***1 . 0 0 0 . 0 2 O1.01) p

* P < 0 . 0 5 ; * * * P < 0 . 0 0 1 .

s e d i m e n t . G o o d c o r r e l a t i o n w a s f o u n d , h o w e v e r ,w i t h V S .

T h e c o r r e l a t i o n m a t r i c e s w e r e c a l c u l a t e d a tP < 0 . 0 5 a n d P < 0 .0 01 o n l y f o r t h e m e t a l s e x t r a c t e da s G P H s 3 , 4 a n d 5 . D a t a o f t h e G P H s 1 , a n d 2 w e r em o s t l y b e l o w t h e a n a l y t i c a l d e t e c t io n l i m i t . C o r r e -l a t i o n w e r e d o n e a m o n g t h e e x t r a c t e d m e t a l i ns p ec if ic G P H w i t h V S a n d a l l t h e f o r m s o f F e a n dM n , i n c l u d i n g t h o s e e x t r a c t e d b y d i s s o l u t i o n w i t hh y d r o f l u o r i c p l u s n i t r ic a c i d . T h e r e s u l t s s h o w f o r t h em e t a l s e x t r a c t ed in G P H 3 T a b l e 5) g o o d c o r r e l a t io na m o n g C r , C u , N i a n d P b a n d V S , s t a t i s t i c a l l yre l i ab le a t P < 0 .001 l eve l . Pb a nd Z n co r re l a t e , a l s o ,t o F e G P H 2 t h e l ev e l o f P < 0 . 0 5 . M e t a l s e x t r a c t e di n G P H 4 T a b l e 61) c o r r e l a t e h i g h l y P < 0. 0 01 ) b u tw i t h a s m a l l c o e f f ic i e n t t o F e G P H 2 C u , P b a n d Z n )a n d F e G P H 4 Z n ) . I n G P H 5 T a b l e 7 ) s ig n i fi c an tc o r r e l a t i o n P < 0 . 0 0 1 ) a n d h i g h c o ef f ic i en t s o fc o r r e l a t i o n to d i f f er e n t f o r m s o f F e a n d M n a r es h o w n b y C r , C u a n d N i s m a l l c o e f f ic i e n t f o r P b ) .F i n a l l y , n o c o r r e l a t i o n w e r e f o u n d a m o n g a n t h r o p o -g e n ic m e t a l h o t H N O 3 e x t r a c t i o n ) a n d t o t a l F e a n dt o t a l M n h y d r o f l t t o r i c p l u s n i t r ic a c id e x t r a c ti o n ) .

I ~N A L C O M M E N T ST h e r e s u l ts o f t h e i n v e s t i g a t i o n i n d i c a t e a s t r e s s e d

e n v i r o n m e n t w h e r e a l o w l e v e l o f o x y g e n i n t h eb o t t o m c a u s es a s t r o n g r e d u c t i o n o f t h e o r g a n i cs u l fu r w i t h t h e p r o d u c t i o n o f a h i g h l ev e l o f h y d r o g e n

s u l fi d e . T h e s t a t i s t ic a l c o r r e l a t i o n a n a l y s i s d e m o n -s t r a te d t h a t F e a n d M n o x i d e s a n d h y d r o x i d e s se e mn o t t o b e t h e m a i n r e s p o n s i b l e f a c t o rs o f t h e m e t a ls i n k in g in t h e s e d i m e n t s o f G u a n a b a r a B a y .T h e r e f o r e , t h e c o n c l u s i o n i s t h a t h y d r o g e n s u l f i d e a n dh u m i c a c i d s o r g a n i c m a t t e r ) a r e t h e m o s t i m p o r t a n td e v i c e s i n r e g u l a t i n g th e a m o u n t o f f r e e o rb i o a v a i l a b l e m e t a l s i n t h e s e d i m e n t a n d , t h e r e f o r e , i nt h e m e t a l e x c h a n g e b e t w e e n t h e b i o t a a n d t h e w a t e r .A s d i s c u ss e d a b o v e, t h e a u t h o r s t h i n k t h a t h y d r o g e ns u l f i d e i n s u c h a r e d u c t i v e e n v i r o n m e n t l i k e t h eb o t t o m s e d im e n t o f G u a n a b a r a B a y m u s t p l a y t hem a j o r r o l e . I t s p r e s e n c e i n l a r g e a m o u n t s w i l l p r o d u c ev e r y i n s o l u b l e su l f id e w i t h t h e m e t a l a c c u m u l a t e d a n da d s o r b e d i n t h e s ed i m e n t . T h e l a r g e a m o u n t o fh y d r o g e n s u lf id e u n d o u b t e d l y s h if t s th e a d s o r p t i o ne q u i l i b r i a o f t h e M n / F e / h u m i c a c i d s / c l a y , f o r c in g ac o n t i n u o u s r e l e a s e f r o m t h a t s y s t e m o f h e a v y m e t a li o n s , i m m e d i a t e l y b o n d e d t o t h e s u l f i d e i o n i n o r d e rt o m a i n t a i n t h e t h e r m o d y n a m i c c o n d i t i o n s o f t h es o l u b i l i t y p r o d u c t s .

G e n e r a l l y s pe a k i n g , t h e b a y o f G u a n a b a r a i s h i g h l yp o l l u t e d w i t h t o x i c m e t a l s , a n d t h e a s s o c i a t e dr i s k s e e m s t o b e h i g h a c c o r d i n g t o T a b l e 3 ) f o r C ua n d Z n . I n a m o r e a c c u r a t e e n v i r o n m e n t a l p o i n t o fv i e w , h o w e v e r , i t s h o w s a r e l a t i v e l y l o w r i s k w i t hr e g a r d t o t h e m e t a l s i n t h e s e d i m e n t . T h eb i o a v a i l a b i l i t y o f th o s e m e t a l s B A P s ) , i n d e e d ,a s d e m o n s t r a t e d t h r o u g h t h e s p e c i a t i o n a n a l y si s ,s e em s , n o w , t o b e s m a l l c o m p a r e d w i t h t h e t o t a l a n d


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3026 G. Perin et alTable 7. GPH 5---correlation matrix among the phase-extracted metals, VS and the different species of Fe and Mn N = 59, casewise deletion ofmissing data)Cr Cu Ni Pb Zn Fe Fe Fe Fe Mn Mn Mn Mn5th 5th 5th 5th 5th Fe Mn 2nd 3rd 4th 5th 2nd 3rd 4th 5thGPH GPH GPH GPH GPH b b VS GPH GPH GPH GPH GPH GPH GPH GPHA B C D E F G H I J K L M N O P1.00 0.95 0.96 0.67*** *** ***

1.00 0.94 0.70*** ***1.00 0.74

1 . 0 0

0.10 --0.11 -0 .0 2 0.89 --0.04 --0.15 --0.18 -0 .1 3 0.060.06 -0. 15 -0. 12 0.89 0.07 -0. 12 -0. 20 -0. 15 0.090.03 - 0.22 -0.11 0.88 - 0.04 -0.2 0 -0.23 -0.25 0.020.11 0.27 -0 .1 9 0.61 0.20 0.39 0.41 -0 .2 3 -0 .1 41.00 -0 .0 3 -0 .0 3 0.13 0.03 0.01 0.15 0.29 0.07

1.00 0.57 0.03 -0 .0 7 0.48 0.42 0.40 0.06*** *** *** ***1.0 0 0.08 -0 .1 9 0.21 0.25 0.36 0.32

1.00 0. I 1 0.10 0.09 0.07 0.261.00 0.14 0.07 0.04 0.041.00 0.57 0.42 0.38***

1.00 0.35 0.401.00 0.41

1 . 0 0

-0. 02 -0.01 0.46 A-0.0 4 -0.0 7 0.32 B-0.05 -0.1 0 0.46 C-0 .2 5 0.29 0.59 D

0.08 0.07 0.21 E0.10 0.25 -0 .0 9 F0.32 0.56 0.18 G0.19 0.21 0.39 H

,-0.14 -0.11 -0.11 I0.58 0.36 -0 .2 5 J

0.46 0.58 0.27 K*** ***0.40 0.49 0.10 L0.58 0.71 -0 .0 2 M1.00 0.66 -0 .0 4 N

1.00 0.02 O1.00 P*P < 0.05; ***P < 0.001.

t h e n o n - b i o a v a i l a b l e m e t a l p h a s e s b u r i e d i n t h eb o t t o m .

O n t h e o t h e r h a n d , p r e c i o u s i n f o r m a t i o n s e e m s t oa r i se f r om the inves t iga t ion . A ny t ime the sed iment i sd i s t u r b e d b y d r e d g i n g o r b y a e r a t i n g , a n a l t e r a t i o ncould be induced in the meta l tox ic i ty , i . e .t r a n s f o r m i n g t h e m i n t o m o r e s o l u b l e c o m p o u n d sw h i c h c o u l d s p r e a d o u t i n t h e o v e r f l o w i n g w a t e rG a m b r e l l e t a l . 1980; Foer s tne r e t a l . 1 9 85 ; L u d w i g

a n d S h e r r a r d , 1 9 89 ; H o n g e t a l . 1991; Saeki e t a l .1993).

A n o t h e r f a c t o r w o r t h c o n s i d e r i n g i s r e l a t e d t opol lu t ion sour ces th a t a r e c lea r ly iden t if i ed a t spec if icp o i n t s o n t h e b a y a s d e s c r i b e d b y t h e t r a n s e c tt e c hn i q u e o f F ig s 2 - 5 . U n e x p e c t e d N i a n d M ns o u r c e s h a v e b e e n d i s c o v e r e d i n t h e n o r t h e r n b a y a r e aT r a n s e c t 1 , 2 a n d 3 ) a n d o l d C r c o n t a m i n a t i o n p o i n t s

i n t h e n o r t h - w e s t T r a n s e c t 1 ) h a v e b e e n c o n f i rm e d .

Tabl e 8. HNO3-e xtracted phase----correlation matri x amo ng HNO3-ex tracted metals anth ropo geni cphase) and HF/HNO3 -extracted Fe and Mn b) and VS N = 41, casewise deletion of missing data)Fe b M n bCr Cu Ni Pb Zn Fe Mn HNO3 HNO3HNO3 HNO j HNO3 HNO3 HNO3 HNO3 HNO3 HF HF VSA B C D E F G H I J

1 . 0 0 0.16 0.20 0.20 0.071.00 0.05 0.78 0.81*** ***

1.00 -0.02 0.001.00 0.94

1.00

0.34 0.35 0.15 0.22 0.27 A0.55 -0. 08 0.12 -0 .1 0 -0. 12 B0.44 0.44 0.39 0.33 0.11 C0.54 - -0.1 0 0.10 - -0.09 0.11 D0.48 --0 .21 0.05 --0.1 4 0.01 E1.130 0.48 0.54 0.40 - 0.05 F

1.00 0.33 0.61 0.02 G1.00 0.68 --0.0 4 H

1.00 0.02 I1.00 J*P < 0.05; ** *P < 0.001.


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He a vy- m e t a l po l l u t ion i n Gua na ba r a Ba y 3027A n e w u n e x p e c t e d C r p o l l u t i o n s o u r c e a p p e a rs i n th ec e n t r a l b a s i n ( T r a n s e c t 4 ) i n th e f o r m , h o w e v e r , o fN B A P . F i n a l ly , C u p o l l u t io n i n t h e c en t r a l b a y( T r a n s e c t 5 ) a n d t h e s t r o n g i n f l u e n c e o f t h e R i o d eJ a n e i r o t o w n w i t h i n d u s t r i a l d i s c h a r g e s r i c h i n Z n( T r a n s e c t s 4 , 5 , a n d 6 ) a n d P b ( T r a n s e c t s 4 a n d 5 )h a v e b e e n c l e a r l y r d e m o n s t r a t e d .Acknowledgements--This work was par t ia l ly funded byC.N.R. (Consigl io l '~az ionale de l le Ricerche , Rome, I ta ly)and by C.N .Pq (C onselho Na cional de Pesquisa , Brasi lia ,Brazil).

R E F ER EN C E SBelzi le N. , De Vi t re R. R. and Tessier A. (1989) Che mis t ryo f As ( V) / As ( I I I ) a nd i r on ox i hyd r ox i de s i n na t u r a llacustrine sediments. Proc. Int . Conf. Heavy Metals in theEnvironment 1, pp. 512-515.Bu t l e r J . N . ( 1964 ) Ionic Equilibria--A MathematicalApproach. Addi s on - We s l e y , Re a d i ng , MA.Cha pm a n P . M. ( 1989 ) Cur r e n t a pp r oa c h t o de ve l op ing

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