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e c t i v e o f t hi s s _{t u d y} wa s t o i n v es _{t i g}a t e t h e e f f e c t o f br om i de i on c on c en t r at i o n on t h e d i s t r i b u t i on o f h a l o a c et i c a c i d (H A A ) s p e c i e s r es u l t i n g f r om ch l o r i na t i on , o z on a t i on an d c h l o r am i n a t i on of wa t e r s c on t a _{i n i n g} h u mi c s u bs t an c e s . H A A s a r e b y -pr od uc t s o f dr i n k i n g wat e r d i s i n f e c t i on , a n d l abo r a t o r y a n i ma l s t u d i e s h av e s _{u g g} e s t ed t ha t t h e s e c o_{m p} ou n ds a r e a s s o c i a t e d w i t h c a r c i nog en i c i t y , dev e l op men t al t ox i c i t y an d r ep r od uc t i v e t ox i c _{i t y} . T he po t en t i a l r i s k t o h uman h e a l t h p o s ed b y H A A s an d t h e v a r y i n g t ox i c o l og i c a l s i g n i f i c anc e o f I LA A sp e c i e s ne c e s s i t at e an u nde r s t an d in g o f t he f a c t o r s t h a t a f f e c t H A A f o r ma t i o n an d sp e c i a t i on . I n t h i s s t u dy , wa t e r s we r e ana l yz ed f o r a l l n i ne o f t h e H A A s_pe c i e s c on t a i n i n g br omi n e an d ch l o r i n e . S t an da r d s f o r b r omo di ch l o r o a c et i c a c i d and d i br omo ch l o r o a c et i c a c i d w e r e n o t c om me r c i a l _{l y} av a i l ab l e b u t we r e s _{y n t h} e s i z e d a t t h e U n i ve r s i t y o f N o r t h Ca r o l i na a n d t he U n i v e r s i _{t y} o f Ma s s a chus e t t s . A qu a t i c hu mi c sub st an c e s we r e ob t a i ned _{b y} X A D- _{8 ex t r a c t i on f r om} r aw w a t e r s a t _{M y} r t l e Be a c h , S C an d Pa l m Be a c h Cou n t y , F L . Mode l w a t e r s w e r e _pr e_pa r e d c on t ai n i _{n g} 4 _{m g} /L t ot a l o r _gan i c c a r b on , 2 m M i n o r _g an i c c a r b on , an d t en b r o m i de c o n c en t r a t i on s r an g i n g f r om 0- _{2 5} [JM (0 - ₂ m g/ L ) . Sam p l e s w e r e c h l o r i n a t ed a t p H 8 an d p H 6 w i t h an d w i t hou t _p r e - _{o z o n} at i on . A d d i t i on a l s am p l es we r e c h l o r am i n a t ed a t _{p H} 8 w i t h and wi t hou t p r e - _{o z o n a t i on} . C h l o r i na t e d an d c h l o r amin a t ed s am p l es we r e i nc u b a t ed a t 2 0° C f o r 2 4 hou r s i n t h e da r k , a f t e r w h i ch t i me ox i da n t r e s i du a l s we r e me a su r ed a n d _qu e nc hed . T he s am p l e s we r e ex t r ac t ed i n t o e t he r , de r i v a t i z e d wi t h d i a z ome t han e , t h en an a l y z ed f o r t he ni n e H A A s on a g a s ch r oma t o gr ap h wi t h e l ec t r on c ap t ur e d e t e c t o r . Br omi de i on c on c en t r a t i o n wa s an i m po r t an t f a c t o r i n H A A s p e c i a t i on i n ch l o r i n a t e d wa t e r s . Br omo - _{c h l o r o s} p e c i e s

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. D i st r i bu t i on o f t h e H A A s amon g mon o -, d i -, an d t r i ha l og ena t ed sp e c i e s a_{p p}e a r e d t o b e i n dep enden t o f br omi de i on c o nc en t r a t i on . I n a d di t i on , b r omi de i on ap p e a r e d t o hav e s i mi l a r e f f e c t s on H A A s p e c i a t i on in b o t h wa t e r s s t u di ed . L owe r i n g th e p H o f ch l o r i na t i on f r om _{p H} 8 t o _{p H} 6 en hanc ed t he f o rma t i on o f s ev e r a l s _p e c i e s ; h ow eve r , H A A s pe c i a t i on wa s l i t t l e a f f e c t ed . Pr e - _{o z on a t i on a} p pe a r ed t o e n han c e br om i n e in c o r _po r a t i o n i n t o t he H A As pr o d u c e d f r om s u bs equ en t ch l o r i n a t i on . To t a l H A A f o rma t i on i n ch l o r ami na t ed w a t e r s wa s de c r e as ed a_{p p}r ox i ma t e _{l y} 9 0 % c o_{m p}a r ed t o t o t a l H A A f o rma t i on i n c h l o r i na t ed wa t e r s . D i c h l o r o a c e t i c a c i d wa s t he pr i nc i p a l s p e c i e s f o r med i n ch l o r ami na t ed wa t e r s . C h l o r am i na t i o n o f br o m i de - _{c o n t a} i n i n g wa t e r s r e su l t ed i n s ome f o rma t i on o f br omi n a t e d s_p e c i e s , p r i n c i _p a l l_y br omo a c e t i c a c i d , d i br omo a c e t i c a c i d and b r omo ch l o r o ac e t i c a c i d _; l i t t l e f o rma t i on o f t r i ha l o_g ena t ed s _p e c i es wa s o b s e r ved f r o m ch l o r am i na t i on , b o t h i n t h e p r e s en c e an d abs enc e o f b r om i de i on . Pr e - o z o n a t i on f o l l owe d b y

ch l o r ami n a t i on enha_nc ed t o t a l H A A f o r ma t i on c o_{m p}a r ed t o c h l o r am i n a t i on a l on e ; howeve r , t o t a l H A A f o r ma t i o n wa s s t i l l d e c r e a s ed b y a_{p p}r ox i ma t e _{l y} 9 0 % c o_{m p}a r e d t o ch l o r i n a t i on . T he r e s u l t s s _{u g g}es t t h a t t he br omo - c h l o r o H A As , w ho s e o c c ur r en c e i n f i n i shed dr in k i n g wa t e r s i s p r e s e n _{t l y} no t kn ow n , a r e r e a di l y f o r med d u r i _{n g} c h l o r i n a t i on o f br omi de - c on t a in i n g w a t e r s . C h l o r ami n a t i o n an d _pr e - o z ona _{t i} on f o l l ow ed _{b y} c h l o r am i n a t i o n a _{p p} e a r t o be e f f e c t i v e me ans o f c on t r o l l i_{n g} H A A f o rma t i on . I n a d d i t i on , t he e f f e c t o f b r omi de i on o n H A A s p e c i a t i o n may b e i n de_pen den t o f t he s ou r c e o f hi om i c su bs t an c e s . I l l

T ab l e o f Con t en t s Page No , Li s t o f F i g u r e s v i i i L i s t o f T ab l e s x i i L i s t o f A b br ev i a t i ons x i i i A ck now l ed gemen t s x v 1 I n t r o d u c t i on 1 2 L i t e r a t ur e Revi ew 5 He a l t h e f f e c t s 6 A q u e o us chemi s t r y o f ch l o r i n e a nd b r omi n e 7 Me c ha ni sms o f H A A f o r ma t i on . 1 0 Fa c t o r s a f f e c t i n g H A A f o r ma t i on 1 2 Co_{m p} e t i t i on be t we e n c h l o r i n e an d b r omi ne i n ha l og ena t i on r e a c t i on s wi t h hum i c s u bs t an c e s 1 5 A q u e ou s chemi s t r y o f ch l o r ami ne s 1 8 A q u e ou s chemi s t r y o f o z o n e 1 9 Oz one - br omi d e r e ac t i on s ; 2 1 Oz ona t i on an d di s i n f e c t i on _{b y} -p r od u c t f o r ma t i on . . . . 2 3 3 Ma t e r i a l s a n d Me t ho ds 2 6 Pr epa r a t i on o f _gl a s swa r e 2 6 I s o l a t i on o f h u mi c s u bs t anc e s 2 8 Pr e_pa r a t i on o f mod e l wa t e r s 3 0 Oz o n a t i on _p r o c e d u r e 3 1 C h l o r i n a t i on a n d ch l o r ami na t i o n _p r o c e d ur e s 3 2 Sa_{m p l} e c o l l e c t i o n an d s t o r a ge 3 4 A na _{l y} s i s o f ha l o a c et i c a c i d s 3 5 S tan dar ds 3 5 B r omod i ch l o r o a c e t i c a c i d 3 6 D i b r omo ch l or o a c e t i c a c i d 3 7

s t o r a_g e an d s t ab i l i t_y o f s t an dar ds 3 8 Ca l i br a t i on c u r v e s 3 9 Ga s chr oma t o_{g r} a_{p h}i c an al _ys i s 3 9 Da t a an a l _y s i s 4 4 Me t hod de t e c t i on l i m i t s 4 5 S t a t i s t i c a l t r e a t men t o f r e s u l t s 4 5 4 Re s u l t s an d D i s cu s s i o n 4 9 Pa t t e r n s o f H A A spe c i a t i on i n ex t r a c t s ch l o r i n a t ed a t p H 8 4 9 For ma t i on o f i n di v i du a l s_p e c i e s 4 9 Di s t r i b u t i on of i nd i vi du a l s_p e c i e s 5 3 To t a l HA A f or ma t i on 5 5 To ta l f or ma t i on o f ch l or i n a t ed , b r omo - _{ch l o r o an d b r om i n a t ed s} p e c i e s 5 5 Di s t r i b u t i on of HA As amon g mono - , d i -, an d t r i ha l o_g ena t ed s_p e c i e s 5 8 B r omi n e an d ch l or i n e i n c o _{r p} or a t i on 6 0 E f f e c t o f p H on H A A f o r ma t i on an d sp e c i a t i on i n ch l o r i n a t ed wa t e r s 53 For ma t i on o f i n di v i du a l sp e c i e s 6 3 To ta l H A A f or ma t i on 6 3 Di s t r ib u t i on of i n di v i du a l sp e c _i e s 7 3 T o ta l f or ma t i on of ch l o r i n a t ed , b r omo - chl or o an d b r omi na t ed s_p e c i e s 7 3 D i s t r i bu t i on s of H A A s amo n _g mo n o -, di -, an d t r i ha l og ena t ed s_p e ci e s 7 7 B r omi n e and ch l or i n e i nc o_{r p} o r a t i o n 7 9 Fo r ma t i o n o f br omi n a t e d H A As f r om o z ona t i o n a l one 7 9 E f f e c t o f pr e - _{o z o n a t i o n on H A A f o r ma t i o n an d} s _p e c i a t i on i n c h l o r i n a t ed wa t e r s 7 9 F or ma t i on o f i n di v i du a l s_p e c i e s 7 9

To ta l H A A f or ma t i on 9 3 Di s t r i b u t i on o f i n di vi d u a l s_p e c i e s 9 5 To ta l f or ma t i on of ch l o r i na t ed , b r omo - ch l or o a n d b r o m i n a t ed sp e ci e s 9 7 Di s t r i b u t i on of H A A s amo_{n g m}on o - , di -, an d t r i h a l o_gen a te d s_p e c i e s 1 00 B r omi ne an d ch l or in e i n c o_{r p} or a t i on 1 0 0 E f f e c t o f b r omi de i on c on c en t r a t i on on ch l o r i ne c on s_{u m p t} i on i n ch l o r in a t ed e x t r a ct s 105 H A A f o rma t i on an d s pe c i a t i on i n ex t r a c t s c h l o r ami n a t ed a t p H 8 1 0 7 F or ma t i on an d d i s t r i b u t i o n o f i n d i v i d u a l s_p e c i e s 1 0 7 D i s t r i b u t i on of H A A s amo_{n g} mon o -, -d i -, an d t r i ha l og ena t ed spe c i e s 1 1 0 B r om i ne an d ch l or i ne i n c o_{r p} or a t i on 1 1 0 I n f l u enc e o f _p r e- _{o z on a t i on on H A A f o r ma t i o n} a n d sp ec i a t i o n i n ch l o r ami na t ed wa t e r s 1 1 3 F or ma t i on of i n d i vi d u a l s_pe c i e s 1 1 3 To t a l HA A f o r ma t i o n 1 13 Di s t r i bu t i on of i n di vi du a l s_p e c i e s 1 1 9 Di s t r i b u t i on o f H A A s amo_{n g} mon o - , d i -, an d t r i h al og ena t ed sp e c i e s 1 1 9 B r omi ne a n d ch l or i ne i n c o r_p or a t i o n 119 I m p l i ga t i on s o f t he wo r k 1 2 2 5 Co n c l u s i o ns an d Re c om men da t i ons 1 2 5 Conc l us i o n s 1 2 6 R e c om men da t i on s f o r f u t ur e r e s e a r c h 128 Re f e r enc e s 1 3 0 A p p en di x A . A na l y s i s o f Ha l o a c e t i c Ac i d s 1 3 5 A p p en di x B . Ma s s S p e c t r um o f S y n t he s i z ed Br omod i c h l o r o a c e t i c - "_{A c} i _{d Me t h y l Es t e r 1 3 8}

A p p en di x C . P u r i t y o f Br omod i c h l o r o a c e t i c Ac i d and D i b r omoc h l o r o a c e t i c A c i d 1 3 9 A p p end i x D . H A A Ca l i b r a t i on C ur v e s 1 4 1 A p p end i x E . Me t ho d De t e c t i on L imi t s f o r H A A s 1 53 A p p end i x F . Ni ime r i c a l Da t a o f Ha l o a c e t i c Ac i d Re su l t s . . 1 5 5 A p p en di x G . E f f e c t s o f Pr e - _o z on a t i o n on H A A f o rma t i on i n E x t r a c t s C h l o r i na t ed a t _{p H} 6 2 0 3 A p p en di x H . D i s t r i bu t i o n o f I n d i v i d ua l H A A S pe c i e s i n Pr e - o z o n a t e d E x t r a c t s C h l o r i n a t ed a t p H 6 . . 2 1 2 V I X

Li st o f F i g u r e s F i cr u r e Pa g e N o 1 . 1 C h emi c a l s t r u c t u r e s o f t he ha l o a c e t i c a c i d s 3 2 . 1 Pr op o s ed p a t h way s o f H A A f o r ma t i o n 1 3 2 . 2 S p e c i a t i on o f T H Ms a s a f u n ct i on o f b r omi d e / c h l o r i ne _{(m g} /_{m g )} r a t i o 1 7 2 . 3 S p e c i a t i on o f H A As a s a f u n ct i o n o f br omi de _/ ch l o r i ne _{(m g /m g )} r a t i o 1 7 3 . 1 E x pe r i men t a l des i g n 2 7 3 . 2 Ha l o a c et i c ac i d c a l i br a t i o n c u r ve s 4 0 3 . 3 C hr oma t o gr a ms o f H A A s t an da r d s 4 2 3 . 4 C hr oma t o gr am o f a ch l o r i na t ed Pa l m Be ac h s am p l e . . . . 4 3 4 . 1 F o r ma t i o n o f ch l o r in a t ed H A As a s a f u nc t i o n o f b r omi de c o nc en t r a t i on d ur i _{n g} ch l o r i n a t i on a t _{p H} 8 . . 5 0 4 . 2 F o r ma t i o n o f br omo - _{chl o r o H A As a s a f u n c t i on o f} b r om i d e c onc en t r a t i on dur _{i n g} ch l o r i n a t i on a t p H 8 . . 5 1 4 . 3 F o r ma t i o n o f br omi n a t ed H A As a s a f u nc t i on o f b r omi d e c o nc en t r a t i o n d ur _{i n g} ch l o r i n a t i on a t p H 8 . . 5 2 4 . 4 D i s t r i bu t i on o f i n di v i d ua l H A A sp e c i e s i n ex t r a c t s ch l o r i n a t ed a _{t p H 8} 5 4 4 . 5 T o t a l H A A f o r ma t i on i n ex t r a c t s ch l o r i n a t e d a t _{p H} 8 5 6 4 . 6 Sum o f c h l o r i na t ed , br omo - _{ch l o r o} , an d b r omi na t ed H A A sp e c i es i n ex t r a c t s c h l o r i na t e d a t _{p H} 8 5 7 4 . 7 D i s t r i b u t i on o f H A As i n t o mon o - , d i - , an d t r i ha l o_gen a t ed s_p e c i e s i n ex t r a c t s ch l o r i n a t e d a t _{p H} 8 5 9 4 . 8 Br omi n e an d c h l o r i n e in c o r po r a t i on i n t o H A As i n ex t r a c t s c h l o r i n a t e d a t _{p H} 8 6 1 4 . 9 I n f l uen c e o f p H on M C A A f o r ma t i on i n ch l o r i nat ed ex t r a c t s 6 4 4 . 1 0 I n f l ue n c e o f p H on D C A A f o r ma t i on in ch l o r i nat ed ex t r a c t s 6 5 4 . 1 1 I n f l ue nc e o f p H on T C A A f o r ma t i on i n c h l o r i n at ed ex t r a c t s 6 6

4 . 1 2 I n f l u enc e o f p H on M B A A f o r ma t i on i n c h l o r i na t e d e x t r a c t s ; 6 7 4 . 1 3 I n f l u enc e o f p H on D B A A f o rma t i on i n c h l o r i na t e d ex t r ac t s 6 8 4 . 1 4 I n f l u enc e o f p H on T B A A f o rma t i on i n c h l o r i na t e d e x t r a c t s 69 4 . 1 5 I n f l u enc e o f p H on Br C l A A f o r ma t i on i n c h l o r i na t e d e x t r a c t s 7 0 4 . 1 6 I n f l u enc e o f p H on Br C l _jA A f o r ma t i on i n c h l o r i na t e d ex t r a c t s 7 1 4 . 1 7 I n f l u enc e o f p H on Br _sCl A A f o r ma t i on i n c h l o r i na t e d e x t r ac t s 7 2 4 . 1 8 I n f l u enc e o f p H on t o t a l HAA f o r ma t i on i n c h l o r i na t e d ex t r a c t s 7 4 4 . 1 9 D i s t r i bu t i on o f i n d i v i d ua l H A A spe c i e s i n e x t r a c t s c h l o r i na t ed a t _{p H} 6 7 5 4 . 2 0 Sum o f c h l o r i n at ed , b r omo - _{ch l o r o} , an d br omi n a t ed H A A s p ec i e s i n ex t r a c t s ch l o r i n a t e d a t p H 6 7 6 4 . 2 1 Di s t r i b u t i on o f H A As i n t o mo no - , d i -, and t r i ha l o _g ena t e d s _pe c i e s i n ex t r a c t s ch l o r i na t ed a t p H 6 7 8 4 . 22 Br omi n e an d c h l o r in e i nc o r po r a t i on i n t o H A A s i n ex t r a c t s ch l o r i na t ed a t _{p H} 6 8 0 4 . 2 3 I n f l u enc e o f o z one o n M C A A f o rma t i on i n e x t r a c t s c h l o r i na t ed a t p H 8 81 4 . 2 4 I n f l u enc e o f o z one on D C A A f o rma t i on i n e x t r a c t s c h l o r i na t ed a t _{p H} 8 8 2 4 . 2 5 I n f l u enc e o f o z one on T C A A f o r ma t i on i n e x t r a c t s ch l o r i na _t e d a t p H 8 8 3 4 . 2 6 I n f l u enc e o f o z one on M B A A f o r ma t i on i n e x t r a c t s c h l o r i na t ed a t _{p H} 8 84 4,. 2 7 I n f l u enc e o f o z on e on D B A A f o r ma t i on i n ex t r a c t s ch l o r i na t e d a t _{p H} 8 8 5 4 . 2 8 I n f l u enc e o f o z one on T B A A f o r ma t i on i n ex t r a c t s ch l o r i na t ed a t _{p H} 8 8 6 4 . 2 9 I n f l u enc e o f o z on e on Br C l A A f o r ma t i on i n ex t r a c t s ch l o r i na t e d a t _{p H} 8 ' 87 3.x

4 . 3 0 I n f l uen c e o f o z one on Br C l ₂A A f o r ma t i o n i n ext r a c t s ch l o r i n a t e d a t _{p H} 8 8 8 4 . 3 1 I n f l uen c e o f o z o ne on Br _jC l A A f o r ma t i on i n ex t r a c t s ch l o r i n a t e d a t p H 8 8 9 4 . 3 2 E f f e c t of pr e - o z ona t i on o n t o t a l H A A f o r ma t i on i n ch l o r i n a t ed ex t r a c t s 94 4 . 3 3 D i s t r i b u t i on o f i n d i v i d ua l H A A sp e c i es i n p r e - o z o_na t e d ex t r a c t s c h l o r i n a t e d a t p H 8 96 4 . 3 4 S\ im o f c h l o r i na t ed , br omo - _{ch l o r o} , an d b r om i na t ed H A A s_p e c i e s i n _p r e - o z on a t ed ex t r a c t s ch l o r i na t ed a t _{p H} 8 9 8 4 . 3 5 S u m o f ch l o r i na t e d , br omo - c h l o r o , an d b r om i n a t ed H A A s_p e c i e s i n _p r e - _{o z on a t ed ex t r a c t s} ch l o r i n at ed a t p H 6 9 9 4 . 3 6 D i s t r ib u t i o n o f H A As i n t o mon o -, d i -, a nd t r i h a l o_gen a t ed sp e c i e s i n pr e - o z ona t ed e_{x t} r a c t s ch l o r in at ed a t p H 8 . 1 0 1 4 . 37 D i s t r i bu t i on o f H A As i n t o mon o -, d i -, a nd t r i ha l o_gen a t ed s_p e c i e s i n _pr e - o z ona t ed ex t r a c t s ch l o r i n a t e d a t _{p H} 6 1 0 2 4 . 3 8 Br omi n e an d ch l o r i n e in c o rp o r a t i o n i n t o H A As i n _p r e - _{oz ona t e d ex t r a c t s ch l o r i n a t e d a t} p H 8 1 0 3 4 . 3 9 Br omi n e an d c h l o r i n e in c o r po r a t i o n i n t o H A A s i n _p r e - oz ona t e d ex t r a c t s ch l o r i n a t ed a t p H 6 1 0 4 4 . 4 0 E f f e c t o f br omi de i on on c h l o r i n e c onsi om p t i on i n c h l o r i na t ed ex t r a c t s 1 0 6 4 . 4 1 E f f e c t o f br omi de i o n o n chl o r i n e c ons i om p t i on i n _p r e - _{o z ona t ed} , ch l o r i na t e d ex t r a c t s 1 0 8 4 . 4 2 Di s t r ib u t i o n o f i n di v i d ua l H A A sp e c i es i n ex t r a c t s ch l o r ami na t ed at p H 8 10 9 4 . 4 3 D i s t r i b u t i on o f H A As i n t o mon o -, d i -, an d t r i ha l o _gen a t ed s pe c i e s i n e x t r a c t s ch l o r ami n a t ed a t p H 8 I l l 4 . 4 4 Br omi n e a nd ch l o r i n e i nc o r po r a t i on i n t o H A As i n ex t r ac t s c h l o r am i na t ed a t p H 8 1 1 2 4 . 4 5 I n f l u enc e o f o z o ne on M C A A f o r mat i on in ex t r a c t s ch l o r ami n a t ed a t _{p H} 8 1 1 4 4 . 4 6 I n f l u enc e o f o z o ne o n D C A A f o r ma t i on i n ex t r a c t s ch l o r am i na t ed a t _{p H} 8 1 1 5

4 . 4 7 I n f l u enc e o f o z one o n M B A A f o r ma t i on i n e x t r a c t s ch l o r am i n a t e d a t _{p H} 8 . 1 1 6 4 . 4 8 I n f l u enc e o f o z o ne o n D B A A f o r ma t i o n i n ex t r a c t s ch l o r ami n a t e d a t _{p H} 8 1 1 7 4 . 4 9 I n f l u enc e o f o z one o n t o t a l H A A f o r ma t i on i n ch l o r ami n a t e d ex t r a c t s 1 1 8 4 . 5 0 Di s t r i b u t i on o f i n d i v i d ua l H A A sp e c i e s i n pr e - _{o z ona t ed ex t r a c t s ch l o r am i na t ed a t} p H 8 1 2 0 4 . 5 1 D i s t r i b u t i on o f H A As i n t o mon o -, d i -, a n d t r i ha l o ge na t ed spe c i e s i n pr e - o z ona t ed ex t r a c t s ch l o r ami n a t e d a t p H 8 1 2 1 4 . 5 2 Br omi n e an d ch l o r i n e i nc o r po r at i o n i n t o H A A s i n pr e - o z o n a t ed ex t r a c t s ch l o r ami n at ed a t _{p H} 8 1 2 3 X I

Li s t o f Ta b l e s T ab l e _{Pa g e N} o 3 A Me t h od de t e ct i o n l i mi t s o f H A A s _p e c i e s 4 5 3 B Co e f f i c i en t s o f v a r i a t i on f o r H A A me a s u r emen t s f r om d i f f e r en t e xp e r i men t s 4 7 3 C Co e f f i c i en t s o f v a r _i a t i on f o r _{H A A m}e a s u r emen t s f r om t h e s ame e _{x p} e r imen t 4 8 4A Br omi de c on c en t r at i ons o f p e ak f o r ma t i o n o f br omo - c h l o r o s _pe c i e s du r i n g c h l o r i na t i o n a t p H 8 5 3 4 B Br om i de r a_{n g}e s o f _pr i nc i p a l s _gie c i e s f o r me d in ex t r a ct s ch l o r i na t ed a t p H 8 5 8 4 C I n f l u en c e o f p H on br omi de r a_{n g}es o f pr i nc i pa l s_p e c i e s f o r me d in c h l o r i na t e d e xt r ac t s 7 7 4 D Re l a t i v e r a t e s o f h y dr ox y l r a_d i c a l s c a v en gi n g b y b r omi de i o n a t v a r i ous b r omi de c on c en t r a t i ons 9 3 4 E I n f l ue n c e o f _p r e - o z o n at i on on b r omi d e r a_{n g}e s o f p r i n c _{i p} a l s _pe c i e s f o r med i n c hl o r i na t e d ex t r a c t s 9 7 4 F H A A c on c en t r a t i on s and di s t r i bu t i ons i n f i n i sh ed dr i n k i n g w a t e r f r om t he Me t r o_p o l i t a n Wa t e r Di s t r i c t o f Sou t he r n Ca l i f o r n i a 1 2 4

L i st o f Ab b r ev i a t i o n s B C A A Br C l A A Br C l _jA A Br _zC l A A C V D B A A D B C A A D B F s D C A A D C B A A D O Br D O C D P D E I G C H A A S M B A A M C A A M C L M D L M S M t B E N O M R A R Rt T B A A T C A A br omo c h l o r o a c e t i c a c i d br omo c h l o r o a c et i c a c i d br omod i ch l o r o a c e t i c a c i d d i br omo ch l o r o a c e t i c a c i d c o e f f i c i en t o f v a r i a t i on di b r omo a c e t i c a c i d di b r omo ch l o r o ac e t i c a c i d d i s i n f e c t i on _{b y} -pr od u c t s d i ch l o r o a c e t i c a ci d d i ch l o r ob r omo a c e t i c a c i d d i s s o l ved o r _gan i c b r om i d e d i s s o l ved o r _gan i c c a r bon N ,N - _{d i} e_{t h y l} - _l , 4- p hen y l en ed i ami n e e l e c t r on i m pa c t ga s c h r oma t o_gr a_{p h} ha l o a c et i c a c i ds br omo a c e t i c a c i d c h l o r o a c e t i c a c i d ma xi m u m c on t ami na n t l eve l met ho d d e t e c t i on l i mi t mas s s pe c t r ome t e r me _{t h y l} t e r t i a r _y - _bu _{t y l} e t h e r n a t ur a l o r _g an i c ma t e r i a l r e l a t i ve a r e a r e l a t i v e r e t en t i o n t ime t r i b r omo a c e t i c a c i d t r i ch l o r o a c e t i c a c i d Xl l l

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on n i e r , Dan S . Sche c h t e r , an d Ma r i a E . S m i t h pr ov i de d v a l u ab l e adv i c e an d s_{u p p} o r t i n t he l a b o r a t o r _y . T h i s r e s e a r c h wa s s u p p o r t e d _{b y} a _gr an t f r om t he Ame r i c an W a t e r Wo r ks Re s e a r ch F ou n da t i on . I a m a l s o t han k f u l t o t h e Gr a d u a t e Sch o o l f o r _p r ovi d i _{n g} a f e l l ow s_{h i p} t h a t a l l ow ed me t o s _{t u d y} a t t h i s u n iv e r s i _{t y} . X V

C h a_{p t} e r 1 I nt r od u c t i o n T he p r es enc e o f ha l o _g ena t e d di s i n f e c t i on _{b y} -p r o d uc t s (D B Ps ) i n dr i n k i n g w a t e r b ec ame a c onc e r n i n t he e a r _{l y} 1 9 7 0s w hen ch l o r o f o r m wa s i den t i f i ed i n New Or l e an s f i n i s h ed dr _{i n k i n g} wa t e r . T h i s d i s c ov e r _{y p} r o_{m p t} ed t he U . S . E n v i r o nmen t a l Pr o t e c t i on A gen cy (U S E P A) t o c on d uc t t h e N a t i o n a l Or _ga n i c s Re c o n na i s s a n c e S ur v e_y o f r aw w a t e r s an d f i n i s h ed dr i n k i n g wa t e r s f o r t he p ur po s e o f i de n t i f y i n g an d qu an t i f y i n g ha l ogen a t e d o r ga n i c c om pou n d s p r e s en t i n t h e wa t e r s . T h i s s t u dy i nc lu de d e i g h t y wa t e r t r e a t men t f a c i l i t i e s cho s en t o r ep r e s en t a v a r i e t y o f s ou r c e wa t e r qu a l i t i e s an d wa t e r t r e a t men t _p r ac t i c e s , an d t h e r e s u l t s o f t h e s t u d y i n d i c a t ed a w i d e s_p r e ad oc cur r enc e o f h a l o gen a t e d o r gan i c s i n f i n i s h e d dr i n k i n g wa t e r ₍1 ₎ . D i s i n f e c t i on b y -pr o d uc t s a r e t h ou g h t t o b e f o r med p r ima r i l y b y r e a c t i on o f t he ch emi c a l di s i n f e c t a n t ₍ch l o r i ne , c h l o r ami ne , o z o ne , e t c . ) w i t h n a t ur a l o r gan i c ma t e r i a l (N O M ) , o f w hi ch h u mi c s u bs t anc es a r e t he _pr i nc i pa l c o_{m p}on en t . M uc h o f t h e i ni t i a l r e s e a r c h on D B Ps f o cu s e _d o n t he t r i ha l ome t ha n e s ₍T H Ms ₎ ; h ow eve r , s ev e r a l o t h e r _g r o_{u p} s o f D B Ps hav e b e en i den t i f i ed an d a r e p r e s e_{n t l y} o f s i g n i f i c an t i n t e r e s t i nc l u d i n g t he ha l o a c e t i c a c i ds (H A As ) , h a l o a c et on i t r i l e s , h a l o ket one s , h a l op i c r i n s , cyan o g en ha l i de s , ch l o r a l h y dr a t e , an d b r oma t e . So me o f t h e f a c t o r s t ha t a f f e c t t h e f o r ma t i on o f D B Ps a r e d i s i n f e c t an t _{t y p} e , d o s e a n d r e s i du a l ; t e_{m p} e r a t u r e , p H , r e ac t i on t ime , na t ur e an d c on c en t r a t i on o f t o t a l o r gan i c c a r b o n ₍T O G) , a n d b r omi de i o n c on c en t r a t i on . T he r e a r e n i ne s_pe c i e s o f ha l o a c et i c a c i d s c on t a _{i n i n g}

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C h l o r o ac e t i c a c i d (M C A A) D i c h l o r o a c e t i c a c i d (DCAA ) Tr i c h l o r o a c e t i c a c i d (T C A A )

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r Br omo a c e t i c a c i d ( MB A_{A )} Di br o mo a c e t i c a c i d (DB_{A A )} Tr i ibr omo a c e t i c a c i d (T BA_{A )}

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Br o mo ch l o r o a c e t i c a c i d Br o mo d i c h l o r o a c e t i c a c i d (B r C l AA ) (Br C1 2A_{A )} Di br c mo ch l o r o a c e t i c a c i d { Br _{2 C l A A )} F _{i g}u r e 1 . 1 . Ch e m

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I t i s w e l l k n ow n t h a t na t ur a l l y o c cu r r _{i n g} br omi de i n r aw wa t e r s i s r e adi l y i nc o r po r a t ed i n t o H A As i n t he f o r m o f o r _g ani c a l l _y b ou n d br o mi ne du r i _{n g} wa t e r c h l o r i na t i on . Dr i n k i n g wa t e r s ou r c e s c on t a i n i n g hi g h b r omi de c on c en t r a t i on s a r e t y p i c a _{l l y} f o un d i n c o a s t a l a r e a s w he r e s e awa t e r i n t r u s i on ma_y b e o c cu r r i _{n g} . A r e c en t n a t i on wi de sur v ey o f br omi d e c onc en t r a t i on s i n U . S . d r i n k i n g w a t e r s ou r c e s e s t i mat ed t ha t t h e me an o c c u r r en c e l ev e l o f b r omi d e i s 6 2 _|i_{g /}L w i t h an o v e r a l l o bs e r v ed r a_{n g}e o f < 5- _{4 29 |}I_{g /} L

(

7 ) . Oz ona t i o n an d c h l o r ami na t i on a r e a l t e r na t i ve d i s i n f e c t i on s t r a t e _gi es t o c h l o r i n a t i on , and t he s e t r e a t men t t e c hn i q ue s a r e u s e d _{b y} a n\ am be r o f wa t e r u t i l i t i e s i n t h e U . S . T h e r e i s p r e s e_{n t l y} gr e a t i n t e r e s t i n b o t h o z ona t i o n an d ch l o r ami n a t i o n a s me t hod s f o r c on t r o l l in g c h l o r i n a t i on _{b y} -p r od u c t f o r ma t i on , a s w e l l a s c on c e r n r e _ga r di n g t h e i r r e s _pe c t i v e _{b y} -p r o d u ct s . Oz one i s an e f f i c i en t d i s i n f e c t a n t ; h owev e r , o z one r e s i du a l s do n o t p e r s i s t i n d r i n k i n g wa t e r . Oz o n a t ed wa t e r _s a r e c om mon l y t r e a t ed w i t h ch l o r i n e o r c h l o r am i ne a s a s e c o n da r _y d i s i n f e c t an t t o ma i n t a i n a r e s i d ua l in t h e d i st r i b u t i on s_y s t em . T he _{p u} r _p o s e o f t he _pr e s en t s_{t u d y} i s _pr i ma r i _{l y} t o in v e s t i ga t e t he e f f e c t o f b r om i de i on c o n c en t r a t i on o n s _p e c i a t i on o f t h e ha l o a c e t i c a c i ds . I t i s r e a s o n ab l e t o ex p e c t , a nd he a l t h e f f e c t s s t u d i e s hav e s u g ge s t ed , t ha t i n d i v i du a l H A A sp e c i e s a r e o f v a r _y i _{n g} t ox i c o l o_g i c a l si _{g n}i f i c an c e . F r om t h i s c on s i de r a t i on i t i s ev i den t t ha t i n o r d e r t o a c cu r a t e _{l y} a s s e s s r i s k t o h u man h e a l t h i t i s no t s u f f i c i en t t o k no w t h e o c c ur r en c e o f a f ew s e l e ct ed s _p ec i e s , o r even t h e t o t a l c on c en t r at i o n o f H A A s p e c i e s , bu t r a t he r i t i s i m po r t an t t o k n ow t he o c cur r enc e l eve l s o f e a c h

i n d i v i d u a l sp e c i es . Fo r t h i s r e a s on i t i s i m p o r t an t t o u nde r s t an d t h e f a c t o r s a f f e c t i n g t he d i s t r i b u t i on o f H A As amo n g i n di v i du a l sp e c i e s . The in c l u s i o n o f a l l n i ne o f t h e H A A sp e c i e s i n t h i s s t u d y _p r ov i d e s a mo r e c o_{m p l} e t e v i ew o f H A A s_p e c i a t i on t h an ma_{n y} o f t he _p r ev i ou s st u d i e s , w h i ch ha ve f o cu s e d p r i ma r i l y on o_{n l y} f i v e o f t he H A A s . Ha l o a c e t i c a c i d s_p e c i a t i on wa s i nv es t i g a t e d d u r i n g ch l o r i n a t i on , o z ona t i on an d ch l o r amin a t i o n o f mod e l w at e r s pr e_p a r ed f r om e x t r a c t ed a_q u a t i c h u m i c s u bs t anc e s . C h l o r i n a t i o n s w e r e c on du c t e d a t b o t h p H 8 an d p H 6, an d a l l o z ona t i on s we r e f o l l owed by e i t h e r ch l o r i n a t i on o r ch l o r ami na t i on . Se c onda r y g o a l s o f t he s t udy i n c _{l u d}e c o m pa r i s on o f t h e e f f e c t o f t h es e d i f f e r en t chemi c a l t r e a t men t t e chni q u e s o n qu an t i t a t i ve f o r ma t i on o f e a ch o f t h e n i ne ha l o a c e t i c a c i ds , an d c om pa r i s o n o f t wo d i f f e r en t s o u r c e s o f na t ur a l o r _gan i c ma t e r i a l w i t h r e s_p e ct t o H A A f o r ma t i on an d s_pe c i a t i on .

C ha_{p t} e r 2 L i t e r a t ur e Re v i ew Ch l o r in at i on of dr i nk in g wa t e r i s kn ow n t o _pr o d u c e bo t h h a l ogen a t ed and non - _h a l og ena t ed p r o du c t s , an d on l y a f r a c t i o n o f t he s e c h l o r i n a t i on _p r o d uc t s h ave be en i den t i f i ed a n d c ha r a c t e r i z e d . I n 1 9 8 0 C h r i s t ma n e t a l . (3 ) i de n t i f i e d s ev e r a l c h l o r i n a t ed an d non - _{c h l o r i na t ed o r} g a n i c a c i ds as pr od uc t s o f c h l o r i n a t i on of a _qu a t i c h u mi c s u bs t a n c e s a t p H 1 2 , and t h e s e r e s e a r c he r s n o t e d t hat D C A A an d T C A A we r e p a r t i cu l a r l y a bu ndan t . T he s e r e s u l t s we r e c on f i r me d _{b y} ad di t i on a l ch l o r i na t i on s t u di e s o f a _{q u}a t i c hum i c sub st anc es bo t h a t _{p H} 1 2 an d a t neu t r a l _{p H} (2 , 4) . I n 1 9 8 3 U den an d Mi l l e r (5 ) i de n t i f i ed D C A A a n d T C A A i n t ap wa t e r a t l ev e l s s im i l a r t o t hat o f ch l o r o f o r m (3 0- _{1 6 0} |Xg / L ) . A na t i o n- _{w i d e s u r ve} y o f t h e o c cu r r en c e o f d i s i n f e c t i o n _{b y} ¬ p r oduc t s i n U . S . f i ni s hed dr i n k i n g wa t e r s e s t i ma t ed t h e med i an c on c e n t r a t i on o f " t o t a l " h a l o a c e t i c a c i d s_p e c i es t o be 1 9 _pg / L (6 ) . T h i s e s t i ma t e i s t he si om o f on l y f i v e o f t h e H A A spe c i e s : M C A A , D C A A , T C A A , M B A A an d D B A A . He a l t h e f f e c t s T h e h e a l t h e f f e c t s o f ha l o a c e t i c a c i ds a r e n o t we l l u n d e r s t o od , an d m u ch o f wha t i s k now n i s ba s e d on s t u d i es o f l ab o r a t o r _y an i ma l s e_{x p}o s e d t o h i _{g h} c on c e n t r a t i on s ₍o n t he o r de r o f _g / L ) o f in d i v i du a l c o_{m p} o un ds . Th e chl o r i n a t e d a c et i c a c i ds h av e b e en st u d i ed t he mos t ; l i m i t ed s t u d y o f M B A A a n d D B A A i n r e l a t i on t o r ep r o d u c t i ve an d dev e l op men t a l t o xi c _{i t y} ha s r e c e_{n t l y} b e g u n (8 ) . Bo t h D C A A an d T C A A hav e b e en s h o w n t o i ndu c e he _p a t i c t u mo r s

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i n m i c e ₍9- _{1 1 )} . Bo t h c om p o un ds a r e a l s o a s s o c i a t e d w i t h h epa t i c t ox i c _{i t y} in mi c e a n d r a t s , an d D CAA ap p e a r s t o c aus e mo r e s ev e r e e f f e c t s t h an T C A A (1 0, 1 2 ) . L a r s o n an d B u l l (1 3 ) o b s e r v e d t ha t D C A A i s me t ab o l i z ed t o a _g r e a t e r ex t en t t h an T C A A i n r a t s an d mi c e , a n d i t i s ex p e c t ed t ha t t h e t o xi c i t y an d c a r c i nog en i c i t y o f D C A A r e s u l t f r om b i o l o_{g i} c a _{l l y} r e a c t i v e me t abo l i t e s o f t h i s c o_{m p}ou n d . Ha l o a c e t i c a c i d s hav e a l s o be en a s s o c i a t ed w i t h d ev el o_{p m}en t a l an d r e _pr od uc t i v e t oxi c i t y . D C A A a n d T C AA h ave b o t h b e en s h ow n t o i n d u c e a d ve r s e dev e l o_{p m}en t a l e f f e c t s i n r a t s , p r i n c i p a _{l l y} c a r d i ov a s cu l a r ma l f o r ma t i on s ₍1 4 , 1 5

)

. I n ad di t i on , r epr od uc t i ve t ox i c i _{t y} i n ma l e r a t s an d do_g s h a s b e en ob s e r ve d f o r D C A A ₍1 6₎ . A<

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o r _{i t y} o f h a l o_gen a t ed d i s i n f e c t i o n b y -p r od u c t f o rma t i o n r es u l t s fr om r e a c t i on s b e t w e en ha l o _g ens a n d h\ im i c su b s t an c e s i n dr i n k i n g w at e r . T h e ch em i c a l s t r u c t u r e o f a qu a t i c humi c s u b s t anc es h a s n ot be en e l uc i da t e d (an d i t i s e_{x p}e c t e d t hat s t r uc t ur e ma y v a r _y f r om o ne s ou r c e t o t h e n e x t

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, b u t chem i c a l deg r ada t i on s t u d i es hav e s_{u g g} e s t ed t he _p r es en c e o f a r oma t i c r _{i n g} s , h y d r o x y l g r o u p s , me t hox y l gr ou ps , c a r bo x y l g r o_{u p} s , p heno l i c gr o u p s , k e t on es an d a l deh y de s . A qu e o u s c h l o r i n e

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H O C l ) r e a c t s w i th o r g ani c c o_{m p} ou n ds t hr o_{u g h} e l e ct r o_{p h} i l i c a n d ox i da t i ve me ch a n i sms . I n aqu e ou s s o l u t i on a n e_q u i l i b r i u m i s es t a b l i sh ed b et we en H O C l an d O C l " , w i t h H O C l be in g t he mo r e r e ac t i ve o f t h e t wo s_p e c i es : H O C l ;_^= == i H * + O C l " p Ka = ₇ . 6 @ 1 5 - _{2 0}° C

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The a r om a t i c r i n g i s a c t i v a t ed by s u b s t i t uen t s s u c h a s - _{O K} , - O C H 3 an d - _{N R} j w h i c h c a n don a t e e l e c t r on d ens i t y t o t he r i n g , s t ab i l i z i n g i n t e r med i a t e s . I t i _s b e l i eve d t ha t a c t i va t e d a r oma t i c _gr o_{u p} s in h u mi c su b st an c e s a r e _p a r t i cu l a r l y i m p o r t a n t di s i n f e c t i on _{b y} -p r od u c t _pr e c u r s o r s ₍1 7 ) . I n a d d i t i on , H O C l an d O C l " a r e s t r o _{n g} oxi da n t s . T h e i r o x i da t i o n po t en t i a l s a r e : H O C l + _H* + ₂e -> _{C I} " + Hj O Eq = + 1 . 4 9 vo l t _s O C l " + 2 H* + 2a ' > C I " + HjO Eq = + 1 . 7 1 v o l t _s H O C l c an r e a c t w i t h o r _ga n i c c o_{m p}ou n d s s i m p l y a s an ox i d an t , w i t ho u t ad d i t i on o f h a l o_gen . A n e x am p l e o f s uc h a r e a c t i on i s t he o xi d a t i on o f an a l d e_{h y d}e t o a c a r bo_{x y} l i c a c i d : R -

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I n ad d i t i on , ch l o r i ne i s c ap ab l e o f ox i da t i v e l y c l e av i n g r i ng s t r uc t u r e s . H y p o ch l o r ou s a c i d ox i d i z e s br omi de _i o n t o hy p obr omou s a c i d . T h i s i s c l e a r l _y t h e rmo_{d y n}ami c a l l y f av o r ab l e u pon i n sp e c t i on o f t h e ox i da t i on _p o t en t i a l s : En (v o l t s ) H O C l + H" + 2e ' > _{C I} " + HjO + 1 . 4 9 Br " + HjO > H O Br + H " + 2e " - ₁ . 3 3 H O Cl + Br ' > H O Br + C I ' + 0 . 1 6 T h i s h a s b e en s how n t o b e a r a_p i d r e a c t i on at 2 5° C , w i t h a r a t e e _{x p} r e s s i on o f t he f o rm d

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an d a s e c o n d -o r de r r a t e c on s t an t k = ₂ . 9 5 x 1 0 ^ M'^s e c "_^ (1 8

)

. T h e r e a c t i ons o f H O Br a r e s i m i l a r i n me ch a n i sm t o t h o s e o f H O C l an d i n c l u d e add i t i on t o dou b l e b on ds , e l e c t r op h i l i c a r oma t i c su b s t i t u t i on an d oxi da _{t i} o_n . L i ke H O C l , an e qu i l i br i um i s e s t a bl i sh ed be t we en _{h y p}obr omo u s a c i d and h_{y p} obr omi t e i o n i n a _q u e ou s s o l u t i on : H O Br _^ = == = ^ _H* + O Br " p K^ = ₈ . 7 @ 1 5 - _{2 0}° C A g a i n H O Br i s t he mo r e r e a c t i v e o f t h e t wo s_p e c i e s . Some r e s e a r che r s ₍1 9 - _{2 1) h}av e s u g ge s t ed t ha _{t b}r omi ne an d c h l o r i ne s_p e c i es t ha t a r e mo r e e l e c t r o_{p h} i l i c t h an H O C l an d H O Br a r e r es _p ons i b l e f o r mu ch o f t he a_{q u} e ou s h a l o ge_n a t i o n o f o r g ani c c o_{m p}ou n d s o t he r t h an _{h i g h l y} a c t i va _t ed c o_{m p} o un ds . T he e l e c t r o_{p h i l i} c s_p e c i e s t h a t h a_ve _be e n p r op o s ed i n c l u de Br C l , Br _j , C I 2 , H_jO Br * , H2O C I * an d C l _jO . I n s t u d y i n g the aqu e ou s ch l o r i n a t i on an d br om i na t i on o f _p - _{x y l e ne} , Vou dr i a s e t a l . (2 0 ) obs e r ve d t ha t ha l o gen a t i on wa s c a t a _{l y}z e d _{b y} H* , C I ' , an d Br ' . T h ey ob s e r v e d t h e

f o l l ow i n g o r de r o f r e a ct iv i t y w i t h _p - _{x y l en e} : Br C l > C I 2 ~ _{C I} 2O > Br 2 > H O Br > H O C l I n a d d i t i on , t h ey su g ges t e d t ha t H20 Br * may be ev en mo r e r e a c t i v e t ha n Br Cl . E ve n t hou g h t he c on c en t r a t i on s o f t h es e mo r e e l e c t r op h i l i c sp e c i e s a r e v e r _y s ma l l a t n e a r - _{neu t r a l p H} , i t ha s be en s u g ge s t e d t ha t t he_y ma_y s t i l l be i _{m p}o r t an t s_p e c i e s b e c aus e o f t h e i r h i g h r e a c t i v i t y . T he o r et i c a l c a l cu l a t i on s f o r t he ha l o _g ena t i on o f a r oma t i c c o_{m p}o u n ds a t _{p H} 6 su g g e s t ed t ha t Br Cl i s t h e mo s t _{i m p} o r t a n t br om i na t i n g s pe c i e s ev e n t ho u g h i t s c o nc en t r a t i on i s f i v e o r de r s o f ma _gn i t u de l es s t h a n t ha t o f H O Br (2 1 ) . T he s e c a l cu l a t i on s p r e d i c t e d t h e i m p o r t anc e o f ha l og ena t i n g s _p e c i es t o be i n t he o r d e r : Br C l > H20 Br * > C l j > C l jO > H O Br T h e s e mo r e e l e c t r o_{p h}i l i c ha l o_g ena t i n g a_g en t s a r e f av o r e d b_y l ow _{p H} , an d i t ha s b e en ob s e r v ed t ha t t o t a l o r g an i c h a l o gen (T O X ) f o r ma t i on f r om c h l o r i na t i on o f h u mi c su bs t an c e s t ends t o i n c r e a s e w i t h dec r e a s i _{n g p H (}1 7 , 2 2 ) . Me c han i sms o f H A A f o r mat i o n The chem i c a l p a t h wa y s _{b y} wh i c h ha l o a c e t i c a c i d s a r e f o r me d du r i _{n g} ch l o r i n a t i on o f r aw wa t e r s a r e no t we l l u nde r s t o o d . U nc e r t a _{i n t y} i n t h e ch emi c a l s t r u c t u r e o f humi c su bs t an c e s make s e l u ci d a t i on o f t h e r e a c t i o n me c han i sms pa r t i cul a r ly d i f f i cu l t . M u ch o f t he r e s e a r c h i n t hi s a r ea h a s i n v o l v ed ch l o r i n a t i on of mod el c om pou n d s w i t h s t r u c t u r a l ch a r a c t e r i s t i c s be l i ev e d t o be s i mi l a r t o t ho s e o f h u mi c s u bs t anc e s . Si nc e a c t i v a t ed a r oma t i c c o_{m p}ou n d s t e n d t o b e _{h i g h l y} r e a c t i v e w i t h c h l o r i ne , an d a c t i va t e d a r oma t i c gr o up s a r e k n o w n t o be _pr es en t i n h u m i c s u bs t an c e s , i t 1 0

i s e_{x p}e c t e d t ha t s u c h gr o_{u p} s ma_y be _pr e c u r s o r s o f d i si n f e c t i o n b y -pr od u c t s w hen dr i n k i n g wa t e r i s ch l o r i n a t ed . I n a s t u d y o f t he chl o r i n a t i on o f f u l v i c a c i ds an d h u m i c a c i d s , Re c k h ow e t a l .

(

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c h l o r i na t i o n , r e a c t i on t i me , " T O C c onc en t r at i on , b r om i de i on c on c en t r a t i on , a n d t em p e r a t ur e . Mu c h o f w ha t i s p r e s en t l y k now n i s ba s ed on st u d i e s i n v o l v in g o_{n l y} M C A A , D C AA , T C A A , M B A A an d D B A A . L i t t l e i s k now n abou t how t he s e f a c t o r s a f f ec t f o r ma t i on o f t h e b r omo - c h l o r o spe c i e s be c a u s e o f t he u nav a i l ab i l i _{t y} o f a n a l y t i c a l s t an da r d s f o r t h e s e c o_{m p}o u n ds . M i l l e r an d U den (2 4 ) i n v e s _{t i g}a t ed t h e i n f l u en c e o f c hl o r i n e do s e on D C A A an d T C A A f o r ma t i on f r om s o i l fu l v i c a ci ds , a n d t h ey ob s e r v ed t ha t t he f o r ma t i o n o f t h es e c o _{m p} o u n ds wa s en han c e d by h i g h ch l o r i ne dos e s . I n ad di t i on , T C A A ap pe a r ed t o b e mo r e gr e a t l y a f f e ct ed _{b y} t he r a t i o o f Na O C l t o o r _gan i c c a r bon (C ) t ha n d i d D C A A . Re l a t i v e f o r ma t i on o f D C A A c om pa r e d t o T C A A wa s de_p en den t on ch l o r i n e do s e . A t a l ow ch l o r i ne do s e

(

m g NaO C l /m g C = 0 . 5) , t he f o r ma t i o n o f D C A A w a s g r e a t e r t h a n t ha t o f T C A A ; b u t a t h i g he r ch l o r i ne do s e s (Na O C l /C > 1 ) , T C A A wa s f o rme d i n exc e s s o f D C A A . A t ve r y h i g h c h l o r i ne do s e s (N aO C l / C > 5 ) , a f a i r l y c on s t an t r a t i o o f T C A A /D C A A = 3 wa s o b s e r v ed . S t udy i n g t h e f o rma t i on o f H A A s f r om ch l o r i n a t i on o f c om me r c i a l _humi c a c i d i n t he _p r e s enc e o f br omi d e i o n , Pou r mo_{g h}add a s e t a l . (2 5) ob s e r ved t h a t a h i gh ch l o r in e do s e s _{l i g h t l y} i n c r e a s ed T C A A and Br C l A A f o r ma t i o n , g r e a t l y i n c r e a s e d Br C l jA A an d Br sC l A A f o r ma t i o n , an d d i d n o t s i g n i f i c an t l y a f f e c t D C A A f o r ma t i o n . Con v e r s e l y , D B A A a n d t r i br omo a c e t i c a c i d (T B A A

)

w e r e e n ha nc ed b y a l o we r ch l o r in e d o s e . A _gen e r a l t r end o f i n c r e a si _{n g} H A A f o r ma t i o n wi t h d e c r e a s i _{n g} p H ha s b e en ob s e r v e d f o r s ev e r a l o f t h e H A A spe c i e s . S t u d i e s o f D C A A a n d T C A A _{b y} Mi l l e r an d U den ₍2 4) an d Re c k how an d Si n ge r (2 2 ) 1 4

su g g e s t t h a t a l t ho_{u g}h s uc h an ov e r a l l t r en d i s ob s e r vab l e , t he b eh av i o r o f t he s e s_p e c i es a s a f u nc t i on o f _{p H} i s bo t h n on - _{l i n e a r} a n d c o_{m p l} ex . I n ch l o r i na t ed w a t e r s c o n t a i ni n g b r om i de i on in t he p H r a_{n g} e 5- ₉ . 4 , Pou r mo g ha d da s e t a l . (2 5) ob s e r v ed t ha t t he f o r ma t i o n o f T C A A , Br Cl A A, Br Cl jA A , Br zClA A an d T B A A w as c l e a r l y e n ha nc ed a t l ow p H. p H ap pe a r ed t o hav e l e s s , i f an y , e f f e c t on D C A A , M B A A an d D B A A f o r ma t i o n . Fo r ma t i on o f t h e ha l o a c e t i c a c i d s _g ene r a l _{l y} i nc r e a s e s w i t h i nc r e a s i n g r e a c t i on t ime . D C A A an d T C A A h a v e be en s how n t o ex hi b i t r a_p i d in i t i a l f o r mat i o n dur i _{n g} t h e f i r s t f ew mi n u t e s o f ch l o r in at i on (2 4 , 2 6 ) . Do r e e t a l . ( 26) an d Z h u an d Re c k h ow (2 7) h a v e ob s e r ve d c on t i nu ed , s l ow f o r ma t i o n o f t h e s e c om pou n d s even a f t e r 6 d a_ys o f r e ac t i on . Pour mo ghad das e t a l . ( 25) d i d ob s e r v e a s l i _{g h t} de c r e a s e i n T B A A c on c e n t r a t i on a t 1 6 8 h our s r e l a t i v e t o 4 8 h o u r s ; t h i s i s l i ke _{l y d u}e _t o _{t h}e _i n s t a_{b i} l i t y o f t h i s c o_{m p}ou n d . Comp e t i t i o n b e t we en ch l o r i ne an d br omi n e i n h a l o gen at i on r e a ct i ons wi t h h um i c su b st a nc e s Sev e r a l r e s e a r c he r -_s h_av _{e o}b_{s e r} v_e d t h_at b_{r o}m i n _{e a} p p e a r s t o b e mo r e r e a c t i v e t h a n c h l o r i ne i n su bs t i t u t i o n r e a c t i on s w i t h o r _g an i c s d ur i n g c h l o r in a t i o n o f mod e l c o_{m p}ou n ds an d hu_{m i} c su b s t an c e s in t h e _p r e s enc e o f br omi de i on ₍2 0, 2 1 , 2 8 ,2 9) . Br omi ne i s e x_p e ct ed t o be mo r e r e a c t iv e t han c h l o r i ne i n a d d i t i on a n d s u b s t i t u t i o n r e a c t i ons be c a u s e i t i s a mo r e _p o l a r i z a_{b l} e _mo l e c _{u l} e . Ro o k e t a l . (2 8 ) ob s e r v ed a mo l a r r a t i o o f ch l o r i ne t o br omin e i nc o r _p o r a t i on i n t o T H Ms o f C I /Br = 5 . 5 w i t h a mo l a r r a t i o o f (a d d e d ch l o r i ne _{) /} Br " e_qu i va l en t t o 4 0 . Vou dr i a s e t a l . (2 1 ) o bs e r v ed t ha t t h e c h l o r _i n a t i on d f p - x y l ene i n t h e _p r e s enc e o f Br "

p r o d u c e d m u c h gr e a t e r amou n t s o f br omo -_p - x y l en e t han ch l o r o - _p -x y l en e even t h o_{u g h} t he c o n c en t r a t i on o f H O C l wa s 3- 5 x g r e a t e r t h a n t h a t o f Br " . I n ad d i t i on , S we et man e t a l . (3 0 ) obs e r v ed g r e a t e r f o r ma t i on o f br omin a t ed _p r o du c t s f r om t r e a t men t o f p hen o l w i t h H O C l + Br " t h an f r om t r e a t men t wi t h Br " - _{f r e e H O Br a l one} . I t w a s s u g g es t ed t h a t s ome H O Br _p a r t i c i pa t e s i n o xi d a t i on r e a c t i on s w i t h pr od uc t i on o f Br " , an d t h i s Br " c an b e r e ox i d i z ed t o H O Br w hen H O C l i s _p r e s en t . Bas ed on s t u di es o f r e s o r c i no l r e a c t ed w i t h e_g u i mo l a r H O C l an d H O Br , Ro o k e t a l . (2 8 ) c onc l u de d t ha t ch l o r i n e wa s b e i n g p r e f e r en t i a _{l l y} co n s ume d i n ox i da t i on r e a c t i on s an d br omi n e in e l e c t r op hi l i c s u bs t i t u t i on r e a c t i ons . Se v e r a l r es e a r ch e r s hav e s t u di e d t h e e f f e c t o f br omi de i o n c onc en t r a t i on o n T H M f o r ma t i on an d sp e c i a t i on i n ch l o r i na t e d w a t e r s

(

2 9, 3 1 - _{3 4} ) . T he s e s t ud i e _s hav e i den t i f i ed br omi de c onc en t r a t i on a n _d T O C c onc en t r a t i on a s i m p o r t a n t f a c t o r s i n T H M sp e c i a t i on . I n gen e r a l , a s b r omi de i on c on c en t r a t i o n i nc r e a s e s , ch l o r o f o rm f o rma t i o n de c r e a s e s , b r omo f o r m i nc r e a s e s , a n d t he mi xe d s_p e c i e s ₍b r omodi c hl o r ome t han e an d di b r omo ch l o r ome t ha ne ₎ p a s s t h r ou g h a max i mum v a l u e . T h i s i s show n g r ap h i c a l l y i n F i g ur e 2 . 2 . A d d i t i o n a l l y , s ev e r a l s t u di e s hav e show n t ha t t h e |JM c onc en t r a t i on o f t o t a l T H Ms i n c r e a s e s w i t h i nc r e a s i n_g b r om i de c onc e_{n t} r a t i o n ₍2 9 , 3 1 , 3 4 ) ; howeve r . Co op e r e t a l . (3 3) d i d no t ob s e r ve a _de_p en denc e o f t o t a l T H M f o r ma t i o n on br om i de i on c onc en t r a t i o n . L u on g e t a l . (3 2) demo n s t r a t ed t h a t de c r e a s i n g T O C c on c e n t r a t i on s h i f t s s p e c i a t i o n t o mo r e br omi n a t ed T H Ms . T h i s s t u d y al s o s howe d t ha t d ec r e a s in g t he c h l o r in e do s e f r om 8 t o 2 m g /L

(

T O C= ₂ . 5 m g/ L

)

r e s u l t ed i n de c r e a s e d t o t a l T H M f o r ma t i on b u t di d no t s i g n i f i c an t l y cha_{n g}e t he di s t r _i b u t i on o f 1 6

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/

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L fu lv i c a c i d , 2 5 mg/ L ch l o r i ne , _{p H} 7 , 2 0 ° C, 2 4 ho u r s r e a c t io n t i me (f r o m O l i v e r (34 ) ) . 2 5 0 -, TC AA 2 0 0 -5 1 0 0 -T BAA D 8 CA A D CAA D B AA D CBAA B CA A Br " to CI₂—_{m g}/mg Fi g ur e 2 . 3 . Sp e c ia ti on o f HAA s a s a fu n c t i on o f br omi de /c h l o r i ne (m_{g / mg} ) r a t i o . 2 . 8 3 mg /L h umic a c i d, 1 1. 5 m g /L ch l o r in e , pH 7 , 2 5 ° C , 1 6 8 ho u r s r e a c t i o n t ime ( fr o m Po ur mo_gh a d da s e t a l . ( 2 5 ) ) .

spe c i e s . Pou r mo _{g h}a dda s e t a l . (2 5) hav e s how n t ha t beha v i o r o f t he HAA s_p e c i e s w i t h r e s_p e c t t o b r o mi de c on c en t r a t i on ap pe a r s t o b e s i mi l a r in s ome wa_y s t o t ha t o f t he T H Ms . Wi t h i n c r e a s i n g b r omi d e c onc en t r at i on , t h e f o r ma t i on o f D C A A a n d T C A A de c r e a s e d , M B A A , D B A A an d T BAA i n c r e a s ed , an d Br C l A A , Br C l zA A an d Br 2C l A A p a s s ed t h r ou g h a ma x i miun va l u e _{(F i g} u r e 2 . 3 ) . I t ap pe a r s t ha t a t l ow br omi de /c h l o r i ne r at i o s (< 0 . 0 5 on a m g /m g b a s i s ) , t h e p r i nc _{i p} a l s p e c i e s f o r me d , i n de c r e as i n g o r de r o f s i g ni f i c a n c e , w e r e T C A A , D CAA , Br C l _sA A , Br C l A A , Br jC l A A , D BAA an d T B A A . A t t h e hi _{g h}e s t b r omi de -c o nc en t r a t i on s t u di e d (4 . 5 m g /L ) , H A A f o r ma t i on w a s i n t h e o r d e r : T BAA > D BAA > Br _jC l A A > Br Cl AA > Br C l jA A , D CAA > T C A A . A q u e ou s chem i s t r y o £ ch l o r ami ne s C h l o r amin a t i on i s an a l t e r n a t i v e d i s i n f e c t i on st r a t e_{g y} t o ch l o r i na t i on w h i ch i s k no w n t o p r o d uc e l o we r l ev e l s o f H A A s , T H Ms an d T O X . I n t y p i c a l w at e r t r e a t men t p r a c t i _c e , ch l o r ami n e s a r e f o r med _{b y} r e a c t i n g h y p o ch l o r o u s a c i d (f r e e c h l o r i n e ) w i t h am mon i a . Re a c t i on o f f r e e chl o r i n e wi t h o r g an i c n i t r oge n t ha t ma_y b e _p r e s e n t i n na t ur a l wa t e r s _p r od u c e s o r _gan i c c h l o r am i n e s . Br omami n e s c an be f o rmed a n a l og ou s l y b y r e a c t i o n o f _{h y p} o br omou s a c i d w i t h n i t r ogen o u s c o_{m p}o u nds . The c h l o r am i ne sp e c ie s o f _p r i n c i _pa l i n t e r e s t in w a t e r d i s i n f e c t i on

i

s mono c hl o r ami n e (N HjC l ) . Com pa r e d t o f r e e c hl o r i ne , mo n o c h l o r ami ne i s a we ak e r ox i da n t , a w e a ke r d i s i n f e c t an t , an d i t i s l e s s r e a c t i ve w i t h o r ga ni c c om po u nd s . Mon o ch l o r ami n e i s f o rmed _{b y} r e a c t i on o f equ imo l a r amou n t s o f f r e e 1 8

ch l o r i ne an d ammon i a : H O C l + N H3

^

, N HjC l + HjO K^_g = ₁ . 5 x 1 0 ^ ^ (3 5 ) T he s e c on d - _{o r de r r a t e c ons t an t f o r t h e f o r w a r d r e a c t i o n i s} k= ₄ . 2 x l O ^ M ' ^ s e c " ^ a t 2 5° _C (36 ) . T he r eve r s e r e a ct i on , h y dr o l y s i s o f mono c hl o r ami ne t o f r e e ch l o r i n e an d am mo n i a , o c c u r s w i t h a f i r s t o r de r r a t e c on s t an t o f 2 . 1 x 1 0 " = s e c ' ^ a t 2 5° C (3 6) . W he n ex c e s s f r e e c h l o r i ne i s _pr es en t , d i - an d t r i ch l o r am i n e s pe c i e s (N H C l _j , N C I ₃ ) c a n b e f o rmed as we l l . T he f o r mat i on o f mo no c h l o r am i n e i s f av o r ed _{b y} h i g h p H and mo l a r r a t i o s o f H 0 C 1 : N H₃ < 1 :1 . T h e me ch an i sms o f r e a c t i on s b et we en chl o r ami n e s and a _{q u} a t i c humi c s u bs t a n c e s a r e no t w e l l u n d e r s t o od . I t h a s be en s u g ges t ed t h a t i n ma_{n y} o f t he r e a c t i o ns _p r o d uc i n g c h l o r i n a t ed b y -p r o d uc t s t h e a c t iv e ch l o r i n a _{t i n g} spe c i e s ma_y b e t he s ma l l c on c e n t r a t i on s o f f r e e c h l o r i ne t ha t a r e i n e_{q u} i l i b r i um w i t h mon o c h l o r ami ne (3 7 ) . A q ue o us ch em i s t zv o f o z one Oz on e i s a s t r o_{n g} o_{x i d}a_{n t} , an d i t i s h i g h l y r e a c t i v e w i t h na t ur a l o r _g an i c ma t e r i a l i n wa t e r . Oz on e i s a l s o kn ow n t o d e c o_{m p} o s e au t o c a t a _{l y t} i c a _{l l y} i n a_{q u} e o u s s o l u t i on , an d a p a t h way f o r t he de c o_{m p}o s i t i on h a s b e en de s c r ib ed _{b y} S t a e he l i n an d H o i _{g n}e (3 8 ) . T he de c om po s i t i o n o f o z o n e i s i n t i t i a t ed b y h y dr ox i de i on , a n d mo _l e cu l a r o z on e i s t h u s l e s s s t ab l e a t e l ev a t ed _{p H} . A n i m p o r t a_{n t p} r od u c t o f o z one de c o_{m p} o s i t i on i s t h e _{h y d}r o_{x y l} r adi c a l CO H ) , w h i ch pr opa ga t e s t he r ad i c a l c h a i n de c om p os i t i on o f o z on e . R adi c a l s c ave_{n g}e r s su ch as c a r b on a t e an d b i c a r b on a t e he _{l p} t o s t ab i l i z e mo l ec u l a r o z o n e . H y dr ox y l r ad i c a l s a r e a l s o ox i da n t

s _p e c i e s an d g ene r a _{l l y} r e a c t w i t h o r _g an i c c o _{m p} o u n d s mo r e r a_{p i d l y} an d l e s s s e l e c t iv e _{l y} t ha_n o z o n e . Ke t on e s , a l deh y de s an d c a r b o x y l i c a c i d s a r e c o m mo n p r o d uc t s o f t he o z on a t i o n o f o r _gan i c c o_{m p}ou n d s . Oz on e t en ds t o b e h i g h l y r e a c t i v e w i t h dou b l e bo n ds , an d a n e xam p l e i s t he o z o n o l ys i s o f an a l k en e :

R

. .

R

3

°

3

R

R

^ ^

c

=

c

.

►

,

C

=

₀

₊ 3

_c

=

_o

R ^

H

H

^

O

R

_^

H

Oz on e i s k now n t o be r e ac t i v e w i t h a r o ma t i c c o _{m p} o_{u n d} s a n d i s c _{a p}a b l e o f c l e av i _{n g} a r oma t i c r i _{n g}s . El e c t r o n - dona t i n g sii bs t i t u en t s s uch a s - O H an d - _{O C H} 3 a c t i v a t e a r oma t i c r i n gs t owa r d o z on a t i on r e a c t i o ns a s w e l l a s ch l o r i na t i o n r e a c t i on s . W h en a n a r oma t i c c o_{m p} ou n d c o n t a i n s s i d e ch a i n s , t h e s e s u b s t i t u en t s a r e o f t en mo r e r e adi l y ox i d i z e d b y o z one t ha_{n i} s t he a r oma t i c n uc l eu s d u e t o t h e hi g h s t ab i l i t y o f t h e a r oma t i c n s _y s t em . The _{h y d} r o_{x y l} r a di c a l i s a l s o r e ac t i v e w i t h o r _ga n i c c o_{m p}o u n d s . A c om mon r e a c t i o n o f t he h y dr ox y l r a di c a l w i t h s a t u r a t ed o r _g ani c c om p ou nds i s _{h y d} r o g en ab s t r a c t i on , r e s u l t i n g i n a r ad i c a l :

H

H _H

R

-

C

-

C

- R ' + '

O H

►

R

-

C

-

C

- R ' ₊ H _,

0

H

H

_{H H} T he r e su l t i n g r a di c a l s a r e o f t en _{h i g h l y} r e a c t iv e a n d u n s t ab l e . A n o t he r c om mo n r e a c t i o n o f * 0 H i s a dd i t i on t o a r oma t i c 2 0