_ I
s o lu tio n w ith an a l k a l i n i t y o f I m-equiv I . I n the present experiments, the i n i t i a l rate of pH change was Increased about 2i times when the a l k a l i n i t y was doubled from 0.5 to I m-equiv I 'and f u r t h e r 2i times when the a l k a l i n i t y was redoubled; w h ile the
f i n a l pH increased from 8.38 t o 9.15 t o 10.00. This can be compared t o the t h e o r e t ic a l maximum pH at 20^ reached on the removal o f a l l
inorganic carbon, being 10.87, 11.17 and 11.77 with a l k a l I n i t i e s
- 1
o f 0.5, I. and 2 m-equiv I re s p e c tiv e ly (F ig . 4 ).
In a second set of experiments in v o lv in g p H - d r i f t , the ra te of carbon uptake under c o n d itio n s of constant a l k a l i n i t y was ca lc u la te d from the increase In pH w ith time. The change In f o r each change of 0.1 pH u n i t was determined from the t a b le s in Appendix
HE , and the time taken f o r t h i s u n i t pH change was obtained from a p l o t of pH values against tim e . Rate of uptake was then c a l c u l ated’ f o r each pH i n t e r v a l ; two sets of these data are presented in Fig II . The top row i l l u s t r a t e s the rate of 0^ uptake by Etodea canadensis at a l k a l i n i t y values o f 0.5, 1.0, and 2,0 m-equiv I ' ,
in r e l a t i o n t o concentration In the bulk s o l u ti o n . The bottom row provides si m l l a r curves f o r Euphynohiim vusciforme^ Andbaena cytindrica and Fontinatis antipyretica, a l l at an a l k a l i n i t y of
- I I m-equiv I
The p l o ts of Cy uptake ra te as a fu n c tio n of concentration are li n e a r (.Fontinatis) or, li k e those of Etodea
and Eurhynohiion a t I m-equiv 1 show a steep phase a t higher Cy concentratio ns and a phase w ith smaller slope at lower Cy values.
I f a l k a l i n i t y is lowered t o 0.5 m-equiv I Etodea produces a
- 1
s t r a i g h t lin e also, but an increase of a l k a l i n i t y t o 2 m-equiv I extends the c u r v i l i n e a r phase t o even sm aller Cy values. The steep phase of the p l o t may be extra polate d t o in te r s e c t w ith the a x is .
* '
The COg concentratio n and pH o c curring at th a t p o in t may then be d e te r mined from the Cy t a b le s , Such an e x tra p o la tio n f o r the curves
o f Etodea a t a l k a l i n i t i e s o f I and 2 m-equiv I ' y ie ld s e q u il ib r iu m CO concentratio ns o f 4.3 and 3.1 uM re s p e c tiv e ly . S i m i l a r l y a t 0.5
^ - I *
m-equiv I , the s t r a i g h t - lin e in te r c e p t y ie ld s 4.9 CO . These
* ^
*'i n te r c e p t ” 00^ conce ntratio ns so determined f o r Etodea appear to be f a i r l y constant. S i m i la r e x tra p o la tio n s were made f o r other species which showed the two-phase p l o t . " I n t e r c e p t " concentratio ns
FIGURE il
Rate of net Cy uptake by named species In r e l a t i o n t o Cy concentratio n in the bathing s o l u ti o n during p H - d r i f t experiments w ith a l k a l i n i t y concentratio ns of 0 ,5 , 1.0,
- 1 - 1
and 2.0 m-equiv 1 in the case of Etodea and I m-equiv I f o r the remainder.