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Chapter 34

Coordination Model of Metal-Ion Interactions with Water Hyacinth Plants

Downloaded by SUNY STONY BROOK on October 26, 2014 | http://pubs.acs.org Publication Date: November 4, 1994 | doi: 10.1021/bk-1994-0565.ch034

Dean F. Martin Institute for Environmental Studies, Department of Chemistry, University of South Florida, Tampa, FL 33620-5520

Waterhyacinth plants [Eichhornia crassipes (Mart.) Solms], which infest waterways i n many parts of the world, were used as a model system for studying uptake of metal ions by floating aquatic plants. Observed rates of uptake of manganese(II)-54 and iron(III)-59 by water hyacinth compare favorably with the values expected based upon a coordination model: control by chelation with dihydrogen ethylenediamine- tetraacetate ion and control by metal(II) carbonate s o l u b i l i t y . Agreement depends upon the assumption of the reduction of iron(III) species by the plant. T h e r e i s no e v i d e n c e t h a t A l f r e d W e r n e r h a d a g r e a t c o n c e r n f o r t h e e n v i r o n m e n t , n o r e v e n f o r what m i g h t be c a l l e d a p p l i e d problems. This a s s o c i a t i o n with pure fundamental chemistry stands i n c o n t r a s t w i t h J u s t u s von Liebig, who s e r v e d as a consultant for the German fertilizer i n d u s t r y a n d l e a r n e d what elements were essential by a c l e v e r , p r a c t i c a l method: he a n a l y z e d healthy plants for their constituents, especially n i t r o g e n ( Ν ) , phosphorus ( Ρ ) , and p o t a s s i u m (Κ) (1) . T h e s e a n a l y s e s l e d t o t h e NPK numbers o f fertilizer sacks, and r e p r e s e n t a t r i b u t e t o L i e b i g ' s p r a c t i c a l nature. L i e b i g a l s o d e v e l o p e d b a k i n g powder, w i t h t h e u n d e r s t a n d i n g t h a t i f s o l d i e r s had b a k i n g powder, c l e a n w a t e r , a n d f l o u r , t h e y c o u l d b a k e t h e i r own b r e a d a n d h a v e no n e e d f o r y e a s t , w h i c h g e n e r a t e s c a r b o n d i o x i d e much more s l o w l y (2). On t h e o t h e r h a n d , t h e f a c t t h a t W e r n e r f o c u s e d o n significant i n o r g a n i c chemical problems i s hardly a c r i t i c i s m t h a t would have v a l i d i t y i n h i s t i m e o r o u r s . I n f a c t , i t was h i s p r i n c i p l e s t h a t p e r m i t t e d s t u d i e s o f t h e e f f e c t s o f m e t a l i o n s on p l a n t g r o w t h . These

0097-6156/94/0565-0418$08.00/0 © 1994 American Chemical Society In Coordination Chemistry; Kauffman, G.; ACS Symposium Series; American Chemical Society: Washington, DC, 1994.

34.

MARTIN

Metal-Ion Interactions with Water Hyacinth Plants

419

p r i n c i p l e s w e r e a p p l i e d t o an u n d e r s t a n d i n g o f p r o b l e m s o f , and a p p l i c a t i o n s i n v o l v i n g , w a t e r h y a c i n t h p l a n t s [Eichhornia erassipes (Mart.) Solms]. Werner's p r i n c i p l e s were t h u s combined w i t h L i e b i g ' s a p p r o a c h .


Waterhyacinth

Plants

W a t e r h y a c i n t h p l a n t s were p r o b a b l y f i r s t i n t r o d u c e d i n t o the United States during a h o r t i c u l t u r a l exposition i n New O r l e a n s i n t h e l a t e 1880s, and s o u v e n i r p l a n t s w e r e g i v e n away ( 3 , 4 ) . The p l a n t f l o a t s on w a t e r , i s c a l l e d an emersed aquatic macrophyte, and i t p o s s e s s e s a b e a u t i f u l h y a c i n t h flower t h a t appears i n the l a t e s p r i n g o r e a r l y summer. Owing t o i t s a t t r a c t i v e f l o w e r , t h e p l a n t seemed a l o g i c a l c h o i c e a s an o r n a m e n t a l floating plant. I t was thus deliberately and accidentally propagated i n v a r i o u s l a k e s and waterways. It was introduced t o the S t . Johns R i v e r of F l o r i d a near P a l a t k a , b e i n g grown d e l i b e r a t e l y , b u t t h e n e s c a p i n g a s a c o n s e q u e n c e o f t h e f l o o d i n g o f an o r n a m e n t a l p o n d . A w a t e r h y a c i n t h p l a n t c a n p r o l i f e r a t e r a p i d l y by v i r t u e o f i t s s t r u c t u r e ( F i g . 1 ) , which has a s t o l o n t h a t leads t o the formation of a daughter plant. Under optimum conditions of sunshine, temperature, and sufficient nutrients, waterhyacinth plants can p r o l i f e r a t e a t t h e r a t e o f 1.8 d a u g h t e r p l a n t s p e r p a r e n t p l a n t p e r week ( 5 ) . P l a n t s a r e c h a r a c t e r i z e d i n t e r m s o f their doubling time — the time required for the p o p u l a t i o n t o d o u b l e i n number. The d o u b l i n g t i m e f o r w a t e r h y a c i n t h p l a n t s i s s o m e t h i n g l e s s t h a n a week, i n c o m p a r i s o n w i t h 20 m i n u t e s o r l e s s f o r many b a c t e r i a a n d 3.5 d a y s f o r Ptychodiscus brevis, the F l o r i d a red t i d e organism (6). D e s p i t e what may seem l i k e a c o m p a r a t i v e l y slow g r o w i n g t i m e , by t h e m i d - 1 8 9 0 s , w a t e r h y a c i n t h p l a n t s w e r e a m a j o r p r o b l e m on t h e S t . J o h n s R i v e r b e c a u s e o f t h e t h i c k , n e a r l y i m p e n e t r a b l e mats t h a t s h a d e d t h e n a t i v e p l a n t s , p r o v i d e d a n e s t i n g s p o t f o r m o s q u i t o l a r v a e , and a f f e c t e d the n a v i g a b i l i t y of the S t . Johns R i v e r . This f a c t must h a v e b e e n n o t i c e d b y many. I t seems l i k e l y , however, t h a t t h e Army C o r p s o f E n g i n e e r s , a n a g e n c y w i t h r e s p o n s i b i l i t y f o r maintaining n a v i g a b i l i t y of waters, was s t i m u l a t e d i n t o a c t i o n by t h e i n t e r e s t o f H e n r y F o r d and Harvey F i r e s t o n e . I t i s thought t h a t these two leading i n d u s t r i a l i s t s wintered i n F l o r i d a and used p a d d l e b o a t s on t h e S t . J o h n s R i v e r a s f l o a t i n g b a s e s f o r f i s h i n g and h u n t i n g . The f o r m a t i o n o f f l o a t i n g m a t s must h a v e s e r i o u s l y i n t e r f e r e d w i t h t h e p r o g r e s s o f t h e i r paddle boats (7). Management o f W a t e r h y a c i n t h

Plants

E a r l y e f f o r t s a t managing w a t e r h y a c i n t h p l a n t s were l i m i t e d t o sodium a r s e n i t e , a h e r b i c i d e n o t w i d e l y

In Coordination Chemistry; Kauffman, G.; ACS Symposium Series; American Chemical Society: Washington, DC, 1994.

COORDINATION CHEMISTRY


420

F i g u r e 1. S c h e m a t i c r e p r e s e n t a t i o n o f a w a t e r h y a c i n t h , s h o w i n g d a u g h t e r p l a n t w i t h 1, l e a f ; 2, i s t h m u s , 3, p e t i o l e ; 4, s t o l o n , a n d 5, r o o t s o f p a r e n t p l a n t .



34. ΜΑΚΉΝ


All

favored because Florida cattle were known t o e a t w a t e r h y a c i n t h p l a n t s a d j a c e n t t o t h e banks. I n L o u i s i a n a , s o d i u m a r s e n i t e was m a n u f a c t u r e d o n s p r a y b o a t s f r o m raw s t o c k s a n d was u s e d f o r 35 y e a r s u n t i l 1937 when i t was abandoned i n t h e i n t e r e s t s o f s a f e t y (7, 8 ) . The o t h e r a l t e r n a t i v e c o n t r o l c h e m i c a l was c o p p e r s u l f a t e , a n a l l purpose a l g i c i d e t h a t a f f e c t e d a p l a n t ' s redox system (9). After World War II, 2,4-D (2,4dichlorophenoxyacetic acid, s u p p l i e d as a s u i t a b l e s a l t ) was t h e h e r b i c i d e o f c h o i c e f o r w a t e r h y a c i n t h p l a n t s ( 9 , 10). M e c h a n i c a l r e m o v a l b y c r a n e s was a l s o a s u c c e s s f u l , a l b e i t e x p e n s i v e , approach, most s u i t e d f o r c o n t r o l o f waterhyacinths i n flood control canals. Subsequently, b i o c o n t r o l proved t o be s u c c e s s f u l i n c o n t r o l l i n g w a t e r h y a c i n t h p l a n t s ( 1 2 ) , p a r t i c u l a r l y when undertaken i n c o n j u n c t i o n w i t h chemical c o n t r o l , though not a l l types of waterhyacinth plants responded s i m i l a r l y ( ο Γ · 13). Appreciating the differences i nthe u p t a k e o f m e t a l i o n s b y t h e p l a n t t y p e s was a k e y t o u n d e r s t a n d i n g t h e i r c h a r a c t e r i s t i c s , e s p e c i a l l y s i z e and i n s e c t avoidance. Waterhyacinth

P l a n t Types

Waterhyacinth plants have a characteristic called " p l a s t i c i t y " : they a r e able t o a t t a i n notably d i f f e r e n t sizes i n response t o environmental characteristics, presumably d i f f e r e n c e s i n c o n c e n t r a t i o n s o f n u t r i e n t s o r species of nutrients. This led t o a designation of three g r o u p s o r p l a n t t y p e s , " s m a l l , " "medium," a n d " s u p e r " ( T a b l e I ) . The l a r g e s t p l a n t s a r e found i n water w i t h Table I .

Height,

Comparison o f Waterhyacinth

cm

D i s s o l v e d oxygen a t site,ppm

Medium

Super

30-31

60-75

90-120

4.0

0.5

mg F e / k g d r y p l a n t * leaves stems roots

+

Types*

Small

8.0

D r y w t / f r e s h wt

Plant

557 811 711 0.049 0.008

±

± 157 ± 154 ± 186

0.059 0.004

b

b

837 ± 3 5 1 904 ± 107 12,039 ± 1,567

±

0.068 0.004

* R e f s 11 a n d 12 ± Standard e r r o r f o r 5 samples

b



422


low d i s s o l v e d o x y g e n c o n c e n t r a t i o n s , w h e r e i r o n ( I I ) , a more s o l u b l e f o r m , m i g h t be f o u n d . I n c o n t r a s t , medium a n d s m a l l w a t e r h y a c i n t h p l a n t s were f o u n d i n w a t e r w h e r e f e r r i c f o r m w o u l d be t h e d o m i n a n t s p e c i e s . Superhyacinth p l a n t s c o n t a i n e d s i g n i f i c a n t l y more i r o n , a n a v e r a g e o f 2890 mg o f i r o n p e r k g o f d r y p l a n t (2890 ppm), compared with a n a v e r a g e o f 104 ppm f o r medium p l a n t s . Most o f t h e d i f f e r e n c e s were a s s o c i a t e d w i t h d i f f e r e n c e s i n t h e i r o n content of the roots f o r the p l a n t types (13). The e n v i r o n m e n t a l c h a r a c t e r i s t i c s t h a t seemed m o s t l o g i c a l t o e x p l a i n the ecotypes and t h e i r d i f f e r e n c e s w e r e b a s e d u p o n t r a c e m e t a l s and t h e i r c o o r d i n a t i o n chemistry. T h e r e a r e a t l e a s t two c o n s e q u e n c e s o f t h i s h y p o t h e s i s : i n s e c t a v o i d a n c e and t r a c e - m e t a l u p t a k e ( f o r u s e i n t h e " p o l i s h i n g " s t a g e s o f sewage t r e a t m e n t ) . Insect

Avoidance

A c o o p e r a t i v e p r o g r a m i n v o l v i n g t h e U.S. D e p a r t m e n t o f Agriculture and The Florida Department of Natural R e s o u r c e s ( B u r e a u o f A q u a t i c P l a n t R e s e a r c h and C o n t r o l ) was d i r e c t e d a t f i n d i n g n a t u r a l e n e m i e s o f w a t e r h y a c i n t h p l a n t s . A c c o r d i n g l y , a s e a r c h was l a u n c h e d i n A r g e n t i n a , where waterhyacinth plants were thought to have o r i g i n a t e d , and a f t e r s e a r c h i n g , a w e e v i l (Neochetinia eichhornia Warner) was i s o l a t e d , s t u d i e d , b r o u g h t t o the U n i t e d S t a t e s , and s u b j e c t e d t o a d d i t i o n a l s t u d y d u r i n g q u a r a n t i n e ( 1 2 ) . The i n s e c t s t r e s s e s t h e p l a n t by b o r i n g i n t o t h e l e a v e s and b u l b o u s t i s s u e and l a y s e g g s ; the a f f e c t e d waterhyacinth p l a n t s then are additionally s t r e s s e d by f u n g i t h a t h a v e a p a t h w a y t o t h e i n t e r i o r . U n f o r t u n a t e l y , by M a r c h , 1976 i t was e v i d e n t t h a t the weevil avoided the obvious waterhyacinth plants, i.e., the 10 percent of the population that were superhyacinth plants. The reason was not plant a d a p t a b i l i t y ( 1 3 ) . The b a s i s seemed t o be d i f f e r e n c e s i n t h e t r a c e m e t a l c o n t e n t o f t h e e c o t y p e s : most n o t a b l y t h e s u p e r h y a c i n t h p l a n t s had a g r e a t e r c o n c e n t r a t i o n o f i r o n i n l e a v e s and s t e m and r o o t s . T h o u g h t h i s m i g h t be e x p e c t e d on an a b s o l u t e b a s i s , t h e p l a n t s b e i n g n o t a b l y l a r g e r ( T a b l e I ) , i t was a l s o t r u e on a r e l a t i v e b a s i s , i . e . , when t h e c o n c e n t r a t i o n a s e x p r e s s e d a s mg m e t a l p e r kg dry p l a n t . I n a d d i t i o n , t h e s u p e r h y a c i n t h p l a n t l e a v e s were t h i c k e r i n t e x t u r e , more l e a t h e r y , and h a d 25 p e r c e n t l e s s c h l o r o p h y l l p e r gram d r y w e i g h t t h a n t h e small plants ( 1 3 ) . One can imagine t h a t the superhyacinth p l a n t s w o u l d be u n p a l a t a b l e o r w o u l d r e p r e s e n t a more challenging s i t u a t i o n to a borer insect. It i s possible t h a t t h e l a r g e r p l a n t s may g e n e r a t e d e f e n s e c h e m i c a l s , though this should be a genetically linked c h a r a c t e r i s t i c , and t h e r e was no e v i d e n c e t h a t t h e t h r e e w a t e r h y a c i n t h p l a n t t y p e s a r e g e n e t i c a l l y d i s t i n c t (14) . On t h e b a s i s o f an a s s u m p t i o n t h a t i n s e c t a v o i d a n c e


34.

MARTIN

423 Metal-Ion Interactions with Water Hyacinth Plants

was b a s e d u p o n d i f f e r e n c e s i n m e t a l - i o n concentrations, two s t u d i e s were done. F i r s t , we m e a s u r e d t h e m e t a l concentrations i n three plant types from a natural s e t t i n g ( T a b l e I ) . S e c o n d , we m e a s u r e d t h e r a t e o f u p t a k e by s m a l l w a t e r h y a c i n t h p l a n t s i n c o n t r o l l e d c o n d i t i o n s .


Trace-metal Content of Three Waterhyacinth P l a n t

Types

P l a n t s were c o l l e c t e d f r o m t h r i v i n g i n f e s t a t i o n s o f e a c h plant type ( 1 6 ) , were d r i e d , s e c t i o n e d (into roots, l e a v e s , stems) , decomposed i n n i t r i c a c i d - p e r c h l o r i c a c i d m i x t u r e s u s i n g a m o d i f i e d m i c r o w a v e o v e n (15) t o s a v e t i m e , and a n a l y z e d u s i n g a t o m i c a b s o r p t i o n s p e c t r o m e t r y o r an A u t o A n a l y z e r I I ( f o r i r o n s a m p l e s ) {11,13,16) . The e l e m e n t a l f r a c t i o n o f e a c h p l a n t segment was c a l c u l a t e d , and t h e v a l u e s were f o u n d t o be a l i n e a r f u n c t i o n of -log K f o r t h e m e t a l c a r b o n a t e (11, 16). I t s h o u l d be n o t e d tïiat t h e v a l u e s f o r l e a v e s and s t e m s w e r e g r o u p e d a b o u t t h e d e s c e n d i n g l i n e a r p o r t i o n and t h e r o o t s w e r e a s s o c i a t e d w i t h t h e a s c e n d i n g b r a n c h . The d a t a f o r s m a l l and medium waterhyacinth plants had good linear c o r r e l a t i o n c o e f f i c i e n t s f o r s i x m e t a l s and l e a v e s and s t e m s ( r = 0.97, Ρ < 0.01) and f o r s i x m e t a l s and f o r roots ( r = -0.98, Ρ < 0.01) (16). A s i m i l a r l y valid correlation was n o t o b s e r v e d f o r s u p e r h y a c i n t h plants because t h i s p l a n t t y p e had a s i g n i f i c a n t l y greater f r a c t i o n o f i r o n and c o b a l t i n t h e l e a v e s . The values f o r i r o n represented a s i g n i f i c a n t deviation. The metal ions e x a m i n e d were magnesium, c a l c i u m , zinc, manganese, c o p p e r , and i r o n . The m e t a l c a r b o n a t e v a l u e s used were for the divalent species, which seems s i g n i f i c a n t f o r i r o n i n the l i g h t of previous d i s c u s s i o n o f t h e s p e c i a t i o n o f i r o n as a f u n c t i o n o f d i s s o l v e d oxygen. No v a l u e f o r t h e K f o r C o C 0 was f o u n d , and s u b s e q u e n t l y , t h e d a t a f o r cadmium d i d n o t f i t (17) . The m o d e l p r e d i c t e d 1% o f t h e cadmium w o u l d be d i s t r i b u t e d i n t h e l e a v e s and s t e m s ; i n s t e a d , 25% was the observed percentage, and there was good evidence that w a t e r h y a c i n t h p l a n t s c o u l d a b s o r b and t r a n s l o c a t e cadmium i o n (17). s p

s p

3

These o b s e r v a t i o n s i n d i c a t e d t h e need f o r measuring t h e r a t e s o f u p t a k e o f s e l e c t e d m e t a l s by w a t e r h y a c i n t h p l a n t s and t r y i n g t o o b t a i n a b e t t e r m o d e l f o r m e t a l - i o n uptake. Metal-ion

U p t a k e by W a t e r h y a c i n t h

Plants

Uptake S t u d i e s . Small waterhyacinth p l a n t s f l o a t i n g i n a d e f i n e d medium ( H o a g l a n d ' s s o l u t i o n ) w e r e t r e a t e d w i t h known amounts o f M n ( E D T A ) " and m a n g a n e s e ( I I ) - 5 4 , o r Fe(EDTA)" and iron(III)-59, or phosphorus-32 as o r t h o p h o s p h o r i c a c i d and o r t h o p h o s p h a t e ( 1 8 ) . Rates of r a d i o a c t i v i t y were c o u n t e d a p p r o p r i a t e l y u s i n g p o r t i o n s o f r o o t s o r p o r t i o n s o f stems a t v a r i o u s times. By 2



424


p r e v i o u s e x p e r i m e n t s , i r o n and manganese w e r e known t o s t i m u l a t e t h e growth o f t h i s p l a n t , and waterhyacinth p l a n t s w e r e known t o remove o r t h o p h o s p h a t e . Uptake o f a l l t h r e e elements followed f i r s t - o r d e r r a t e constants, but the r a t e s o f t r a n s l o c a t i o n s from the r o o t s t o the leaves d i f f e r e d . P h o s p h o r u s a s p h o s p h o r u s - 3 2 was t a k e n up b y t h e r o o t s and a p p e a r e d i n m e a s u r a b l e l e v e l s i n t h e s t e m s w i t h i n 48 h o u r s . R a d i o - i r o n was t a k e n up r a p i d l y by t h e r o o t s , b u t e x p e r i m e n t a l l y s i g n i f i c a n t q u a n t i t i e s o f t h e e l e m e n t a p p e a r e d i n t h e l e a v e s o n l y a f t e r a b o u t 21 days. R a d i o - m a n g a n e s e was t a k e n up b y t h e r o o t s as r a p i d l y as i r o n , but t h e r a t e o f appearance i n t h e l e a v e s was t e n t i m e s f a s t e r . The a c c u m u l a t i o n o f p h o s p h o r u s , c a l c u l a t e d on t h e b a s i s o f a 12-month g r o w i n g s e a s o n , was c o n s i s t e n t w i t h e s t i m a t e s p r o v i d e d by o t h e r s (18)· Coordination C h e m i s t r y M o d e l o f Manganese and Iron U p t a k e . On t h e b a s i s o f a v a i l a b l e i n f o r m a t i o n c o n c e r n i n g m e t a l u p t a k e by w a t e r h y a c i n t h p l a n t s (17,18) c e r t a i n a s s u m p t i o n s seem r e a s o n a b l e . F i r s t , t h e r a t e - d e t e r m i n i n g step i s a function of the concentration of f r e e metal ion. T h i s c o n c e n t r a t i o n i s g o v e r n e d by a n e q u i l i b r i u m i n v o l v i n g a more s t a b l e s p e c i e s , w h i c h i s a s p a r i n g l y s o l u b l e complex s a l t ( r e c a l l i n g the l i n e a r p l o t s of f r a c t i o n vs l o g Ksp f o r m e t a l c a r b o n a t e s p e c i e s ) o r a s t a b l e c o m p l e x i o n , e . g . , t h e EDTA m e t a l c o m p l e x . Assuming that carbonate species determine the concentration of t r a c e metal ions, appropriate Ksp e x p r e s s i o n s may be u s e d a n d r e a r r a n g e d i n t e r m s o f t h e carbonate concentration: 2

(C0 -) = Κ 3

β ρ

2

(C0 -) = K 3

e p

/(Μη

2 +

'/(Fe

)

2 +

(1)

)

(2)

F o r a g i v e n pH i n H o a g l a n d ' s s o l u t i o n , t h e c a r b o n a t e i o n c o n c e n t r a t i o n i s c o n s t a n t , and r i g h t - h a n d p o r t i o n s o f t h e two equations are equal t o each other. Thus, rearranging yields 2 +

2 +

Log(Mn )/(Fe ) -

log K

e p

/log

Κ

β ρ

'

(3)

G i v e n known v a l u e s f o r Ksp f o r manganese ( I I ) a n d i r o n ( I I ) carbonates [10" · and 1 0 " · , r e s p e c t i v e l y ( 2 0 ) ] , t h e a p p r o p r i a t e r a t e r a t i o s from the l a s t equation can be c a l c u l a t e d t o be 1 0 · . The a g r e e m e n t b e t w e e n c a l c u l a t e d and o b s e r v e d r a t e r a t i o s ( 1 0 · ) was q u i t e g o o d ( 1 9 ) . R e a l i s t i c a l l y , the v a l u e s o f s o l u b i l i t y p r o d u c t c o n s t a n t s v a r y , and t h u s t h e agreement depends upon w h i c h v a l u e s a r e t a k e n . The r a n g e o f p r e d i c t e d v a l u e s t h u s was 10 · - 1 0 · , and the observed value i s s t i l l w i t h i n the p r e d i c t e d range. I t was a l s o r e c o g n i z e d (19) t h a t o t h e r i o n s m i g h t c o n t r o l the f r e e metal i o n concentration. S u l f a t e might 9

4 1

1 0

1

Γ

4 6

0 5

1 2

1

0 5

1

2 0


34. MARTIN


425

be v a l i d f o r some s p e c i e s , b u t m a n g a n e s e ( I I ) s u l f a t e is comparatively soluble. Phosphate i o n i s e n v i r o n m e n t a l l y logical, especially i n F l o r i d a , which i s a source of phosphate d e p o s i t s (19), but the p r e d i c t e d r a t e r a t i o would be 1 0 · . F i n a l l y , c o n t r o l b y a c h e l a t i n g a g e n t , EDTA, seems logical. A d e r i v a t i o n indicated that the p r e d i c t e d r a t e r a t i o s would be 1 0 . T h e p r e d i c t e d r a t e r a t i o was improved u s i n g formation constants f o r p r o t o n a t e d s p e c i e s f o r i r o n , b u t n o t manganese, a n d t h e c h e l a t i o n a p p r o a c h was n o t p u r s u e d f u r t h e r (19). 0

5

1 1


Conclusion T h i s h a s b e e n a summary o f t h e u t i l i z a t i o n o f a f i e l d o f c h e m i s t r y founded by A l f r e d Werner and a d a p t e d t o a p r o b l e m t h a t he c o u l d n o t p o s s i b l y have a n t i c i p a t e d . E x c e s s i v e a q u a t i c p l a n t g r o w t h was n o t a p r o b l e m i n S w i t z e r l a n d i n W e r n e r ' s t i m e , t h o u g h now i t i s f o r some species. W a t e r h y a c i n t h p l a n t s s e r v e as a u s e f u l model f o r metal i o n uptake because t h e i r c h a r a c t e r i s t i c s l e a d t o c o m p a r t m e n t a l i z a t i o n and because r e m o v a l o f m e t a l i o n s from sewage by means of waterhyacinths has been r e c o g n i z e d as a u s e f u l process (21, 22). It is an interesting irony t h a t a few y e a r s a g o , one o f the i n s e c t s s p e c i f i c a l l y imported f o r waterhyacinth p l a n t c o n t r o l was o b s e r v e d t o f o c u s o n a sewage t r e a t m e n t p l a n t where s m a l l w a t e r h y a c i n t h p l a n t s w e r e g r o w i n g a s p a r t o f the water treatment p r o c e s s . A v o l a t i l e s u b s t a n c e , more p r e v a l e n t i n young t i s s u e , s e r v e s as an a t t r a c t a n t (23). Acknowledgments I t i s a p l e a s u r e t o acknowledge f i n a n c i a l s u p p o r t o f t h e Florida Department of Natural Resources (now the Department o f E n v i r o n m e n t a l P r o t e c t i o n ) Bureau of A q u a t i c P l a n t R e s e a r c h and C o n t r o l , t h e encouragement o f Dr. A . P. Burkhalter, the c o l l a b o r a t i o n of those l i s t e d i n r e f e r e n c e s c i t e d , and t h e l o n g - t e r m encouragement and advice of Barbara B. Martin.

Literature Cited 1.

2.

3. 4.

Liebig, J . F. von. Organic Chemistry in Its Applications to Agriculture and Physiology (edited from the manuscript of the author by L . P l a y f a i r ) ; Bradbury and Evans: London, 1840. Jones, P.R. "Justus von Liebig, Eben Horsford, and the Baking Powder Industry," Paper no. 18, Division of the History of Chemistry, 205th ACS National Meeting, Denver, CO, March 28- A p r i l 2, 1993. Pierterse, A. H. Abstrs. Trop. Agric. 1 9 7 8 , 4, 9-42. Penfound, W. T.; Earle, T. T. Ecol. Monogr. 1 9 4 8 , 18, 448-472.



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5.

Ornes, W. H . ; Sutton, D. L. Hyacinth Contr. J. 1975, 13, 56-58. 6. Doig, III, M. T . ; Martin, D. F. Mar. Biol. 1974, 24, 223-228. 7. Tabita, Α.; Woods, J. W. Hyacinth Contr. J. 1962, 1, 19-23. 8. Wunderlich, W.E. Hyacinth Contr. J. 1962, 1, 15-16. 9. Martin, D. F . ; Martin, B. B. J. Chem. Educ. 1985, 62, 1006. 10. Herbicide Handbook, 6th ed.; Weed Science Society of America: Champaign, IL, 1989. 11. Cooley, T. N.; Martin, D. F. J. Environ Sci. Health 1978, A13, 469-479. 12. Perkins, B.D.; Lovarco, M. M.; Durden, W. C. Fla. Ent. 1976, 59, 352. 13. Cooley, T. N.; Martin, D. F . ; Durden, J r . , W.C.; Perkins, B. D. Wat. Res. 1979, 13, 343-348. 14. Wain, R P.; Martin, D.F. J. Environ. Sci. Health 1980, A15, 625-633. 15. Cooley, Τ. Ν., Martin, D. F . ; Quincel, R. H. J. Environ. Sci. Health 1977, A12, 15-19. 16. Cooley; T. N.; Martin, D. F. J. Inorg. Nucl. Chem. 1977, 39, 1893-1896. 17. Cooley, T. N.; Martin, D. F. Chemosphere 1979, 2, 75-79. 18. Cooley, T. N.; Gonzalez, M. H . ; Martin, D. F. Econ. Bot. 1978, 32, 371-378. 19. Cooley, T. N.; Martin, D. F. J. Inorg. Nucl. Chem. 1980, 42,151-153. 20. Sillen, L. G.; Martell, A. E. Stability Constants of Metal-Ion Complexes; Special Publication No. 17; The Chemical Society: London, 1964. 21. Wolverton, W. New Scient. 1976, 71, 318-320. 22. Simmons, M. A. Prog. Water Tech. 1979, 11, 507-519. 23. Center, T. D.; Durden, W. C. "Studies on the Biological Control of Waterhyacinth with the Weevils Neochetina eichhorniae and N. bruchi," Misc.Paper A84-4,APCRP, U.S. Army Waterway Experiment Station: Vicksburg, MS, 1984; pp. 85-98. RECEIVED October 14, 1993


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