Nonequilibrium Systems in Natural Water Chemistry - ACS Publications

4 Silica Variation in Stream Water with Time and Discharge V A N C E C. K E N N E D Y

Downloaded by UNIV LAVAL on April 7, 2016 | http://pubs.acs.org Publication Date: June 1, 1971 | doi: 10.1021/ba-1971-0106.ch004

U . S. Geological Survey, Menlo Park, Calif. 94025

Silica

concentration

fornia

varies in a consistent

in the

water from various concentrated surface Thus,

during

than

which

a stream

increases

as subsurface With

an increasing

concentration

flow

rise, silica

flow comprises

of streamflow.

of northern

during

much flow

or

Silica the

in

decreases

decreasing proportion

soil

groundwater

of streamflow, Correlation

between

or specific

conductance

is poor

storm

from

Data

is present

variation

other

streams

observed

suggest

in the

be-

and

decreases.

of silica

then

component

slowly

runoff.

while

and

and stream discharge pattern

(sub-

initially

the major

discharge,

as

is more

groundwater.

of the streamflow

becomes

Cali-

storm runoff

seeps through

in overland

overland

comes

River

manner

sources enters the stream.

in water

flow)

Mattole

silica silica during

that

Mattole

the River

elsewhere.

S i l i c a comprises a significant f r a c t i o n of the d i s s o l v e d solids i n s t r e a m ^

w a t e r s ; h o w e v e r , there is r e l a t i v e l y l i t t l e d e t a i l e d i n f o r m a t i o n o n the

variations i n s i l i c a c o n c e n t r a t i o n w i t h t i m e a n d s t r e a m d i s c h a r g e , a n d f e w attempts h a v e b e e n m a d e to e x p l a i n s u c h t i m e - d e p e n d e n t v a r i a t i o n s as h a v e b e e n o b s e r v e d .

T h e c o n c e n t r a t i o n of most d i s s o l v e d constituents

i n s t r e a m w a t e r decreases w i t h i n c r e a s i n g d i s c h a r g e b u t , as D a v i s

(J)

has p o i n t e d out, the s i l i c a content is less v a r i a b l e t h a n t h a t of a n y o t h e r of the m a j o r d i s s o l v e d constituents. T h i s means t h a t the p r o p o r t i o n of s i l i c a i n the d i s s o l v e d solids b e c o m e s greater w i t h i n c r e a s i n g d i s c h a r g e a n d i m p l i e s that the rate of s i l i c a release f r o m soils increases m o r e r a p i d l y t h a n t h a t o f the other d i s s o l v e d solids d u r i n g s t o r m runoff. T h e f a c t t h a t s i l i c a shows l i t t l e or no c o r r e l a t i o n w i t h d i s c h a r g e or specific c o n d u c t a n c e suggests that the controls of s i l i c a c o n c e n t r a t i o n i n stream w a t e r are 94 Hem; Nonequilibrium Systems in Natural Water Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1971.

4.

KENNEDY

complex.

Silica Variation

in Stream

95

Water

C h e m i c a l - e q u i l i b r i u m m o d e l s a p p e a r i n a d e q u a t e to e x p l a i n the

b e h a v i o r of s i l i c a i n n a t u r a l w a t e r s d u r i n g s t o r m periods. T h i s r e p o r t presents d e t a i l e d i n f o r m a t i o n o n the v a r i a t i o n of s i l i c a w i t h t i m e , changes i n stream d i s c h a r g e , a n d specific c o n d u c t a n c e i n t h e w a t e r of the M a t t o l e R i v e r of n o r t h e r n C a l i f o r n i a a n d gives results of s o i l l e a c h i n g studies t h a t h e l p i n u n d e r s t a n d i n g the s i l i c a v a r i a t i o n s i n the M a t t o l e R i v e r . T h e s e results a n d d a t a f r o m other streams i n d i c a t e t h a t s i l i c a v a r i a t i o n s d u r i n g the w e t season m a y b e r e l a t e d to v a r y i n g rates of c h e m i c a l reactions i n the s o i l zone. S i l i c a c o n c e n t r a t i o n i n subsurface runoff waters is r e l a t e d to the l e n g t h of t i m e of contact w i t h the s o i l , the s o i l : w a t e r r a t i o , a n d the r a i n f a l l h i s t o r y p r i o r to the t i m e of s a m p l i n g . Downloaded by UNIV LAVAL on April 7, 2016 | http://pubs.acs.org Publication Date: June 1, 1971 | doi: 10.1021/ba-1971-0106.ch004

P r e v i o u s W o r k . I n f o r m a t i o n p e r t i n e n t to this i n v e s t i g a t i o n has b e e n d r a w n f r o m three types of d a t a : the large b o d y of p u b l i s h e d s t r e a m - w a t e r analyses, the b a s i c w o r k o n s o l u b i l i t i e s of c r y s t a l l i n e a n d a m o r p h o u s s i l i c a a n d of v a r i o u s silicates, a n d a g r o u p of recent reports o n d i s s o l v e d s i l i c a i n s o i l waters. P a l m e r (2)

t h o u g h t that the m o r e a l k a l i n e waters f a v o r e d the r e t e n -

t i o n of s i l i c a i n s o l u t i o n i n streams of the P i e d m o n t P l a t e a u a n d G u l f C o a s t . H e also n o t e d that the p r o p o r t i o n of s i l i c a i n the d i s s o l v e d solids was h e l p f u l i n c o m p a r i n g the c h e m i s t r y of v a r i o u s s t r e a m waters. H e n d rickson and Krieger (3)

c o n c l u d e d that s i l i c a a n d specific c o n d u c t a n c e

w e r e p o o r l y r e l a t e d for several streams i n K e n t u c k y . D a v i s ( I )

made a

c o m p r e h e n s i v e s t u d y of silica i n g r o u n d a n d surface w a t e r s , u s i n g m a n y h u n d r e d s of p u b l i s h e d analyses. F r o m these he c o n c l u d e d that s i l i c a i n g r o u n d w a t e r — a n d , h e n c e , that i n stream w a t e r at l o w stages—is

pri-

m a r i l y r e l a t e d to the rocks a n d m i n e r a l s c o n t a c t i n g the w a t e r . H e f o u n d no m a r k e d influence of p H , s a l i n i t y , c l i m a t i c regions, v e g e t a t i o n , temperature on silica concentration.

or

S t o r m runoff a p p e a r e d to a c q u i r e

most of its silica w i t h i n a f e w days. E v i d e n c e for this w a s the fact t h a t s i l i c a concentrations i n stream w a t e r r e m a i n e d r e l a t i v e l y constant d u r i n g p e r i o d s of h i g h d i s c h a r g e despite the decrease i n d i s s o l v e d solids.

He

mentions several possible explanations for this, one of w h i c h w a s t h a t w a t e r t r a v e l l i n g t h r o u g h the u p p e r p a r t of the s o i l profile m i g h t c o n t a i n a p p r e c i a b l e s i l i c a l e a c h e d f r o m the s o i l a n d c o m p r i s e m u c h of the runoff d u r i n g a n d s h o r t l y after storms.

H o w e v e r , he felt that this m e t h o d

of

o b t a i n i n g s i l i c a r e q u i r e d that s i l i c a b e l e a c h e d f r o m the s o i l w h i l e other constituents w e r e d i s s o l v e d less r a p i d l y . A n e x p l a n a t i o n of this process p o s e d difficulties. I n a later s t u d y , D a v i s ( 4 )

f o u n d that surface runoff

f r o m r a i n c a n a c q u i r e 1-3 m g / l i t e r s i l i c a d u r i n g the first f e w m i n u t e s after r a i n contacts the soil. F e t h a n d others ( 5 )

also s h o w e d that s i l i c a

is released r a p i d l y ( t h a t is, i n a f e w days or so) to p e r c o l a t i n g , s l i g h t l y a c i d i c , s n o w m e l t waters w h i c h s u p p l y e p h e m e r a l springs i n the h i g h Sierra N e v a d a .

Hem; Nonequilibrium Systems in Natural Water Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1971.

96

NONEQUILIBRIUM

SYSTEMS

IN

NATURAL

WATERS

O n e a p p r o a c h to i n t e r p r e t i n g the s i l i c a content of n a t u r a l waters is to d e t e r m i n e the rate of s o l u t i o n a n d s o l u b i l i t y of v a r i o u s m i n e r a l s w h i c h m i g h t b e the source of the d i s s o l v e d s i l i c a . K r a u s k o p f (6)

summarized

p r e v i o u s w o r k a n d p o i n t e d out that s i l i c i c a c i d ( s i l i c a ) is v i r t u a l l y u n d i s sociated b e l o w p H 9 a n d t h a t s i l i c a i n n a t u r a l waters is p r e d o m i n a n t l y i n true s o l u t i o n as H S i 0 , m o n o m e r i c s i l i c i c a c i d . I n a d d i t i o n , h e p e r 4

4

f o r m e d n e w experiments w h i c h i n d i c a t e d that the s o l u b i l i t y of a m o r p h o u s s i l i c a i n d i s t i l l e d w a t e r a n d sea w a t e r is o n the o r d e r of 120 m g / l i t e r at 2 5 ° C . T i m e for e q u i l i b r a t i o n was a p p r o x i m a t e l y 40 days for s i l i c a g e l o r c o l l o i d a l s i l i c a b u t w a s greater t h a n t w o m o n t h s for o p a l .

Siever

(7)

c o n f i r m e d K r a u s k o p f s w o r k o n s o l u b i l i t y of a m o r p h o u s s i l i c a as b e i n g Downloaded by UNIV LAVAL on April 7, 2016 | http://pubs.acs.org Publication Date: June 1, 1971 | doi: 10.1021/ba-1971-0106.ch004

120-140 m g / l i t e r and estimated from higher-temperature data that quartz solubility was about

10.8 m g / l i t e r at 2 5 ° C , a l t h o u g h , e x p e r i m e n t a l l y ,

q u a r t z samples s h o w e d n o m e a s u r a b l e d i s s o l u t i o n at 25 ° C after three years. M o r e y et al. (8)

r e p o r t e d q u a r t z s o l u b i l i t y at 2 5 ° C as 6 m g / l i t e r .

Stober ( 9 ) s t u d i e d the s o l u b i l i t y of v a r i o u s f o r m s of s i l i c a a n d c o n c l u d e d that after i n i t i a l release of s i l i c a f r o m the s o l i d , a l a y e r of a d s o r b e d s i l i c a forms a n d controls the final c o n c e n t r a t i o n of s i l i c a i n s o l u t i o n . W o r k has also b e e n d o n e o n the rate of release of s i l i c a f r o m s i l i c a t e m i n e r a l s a n d o n e q u i l i b r i u m concentrations of s i l i c a i n solutions i n c o n tact w i t h n a t u r a l l y - o c c u r r i n g silicates.

Garrels and Christ

(10)

have

i n d i c a t e d that, c o n s i d e r i n g the p H a n d a l u m i n u m concentrations present, the s i l i c a concentrations i n most g r o u n d a n d s t r e a m waters ( 6 - 6 0

mg/

l i t e r ) are i n the range that m i g h t b e e x p e c t e d f r o m e q u i l i b r i u m w i t h kaolinite.

P o l z e r a n d H e m (11)

f o u n d that s i l i c a concentrations

were

s t i l l i n c r e a s i n g after t w o years i n a d i l u t e suspension of i m p u r e k a o l i n i t e at p H 3.3-3.7. A t the e n d of the experiments, t h e s i l i c a c o n c e n t r a t i o n w a s 8 - 1 0 m g / l i t e r . P a r t of the d i s s o l v e d s i l i c a w a s a t t r i b u t e d to s o l u t i o n of a free s i l i c a i m p u r i t y . M a c k e n z i e a n d G a r r e l s (12)

and Mackenzie

et al. ( 13 ) s h o w e d that a p p r e c i a b l e amounts of s i l i c a w e r e released to sea w a t e r f r o m v a r i o u s c l a y m i n e r a l s w i t h i n a 10-day p e r i o d a n d c o n c l u d e d that the s i l i c a release w a s g o v e r n e d b y a n a l u m i n o u s r e s i d u e o n minerals.

C o r r e n s a n d v o n E n g e l h a r d t (14),

a n d G a r r e l s a n d H o w a r d (16)

Nash and Marshall

the (15),

i n s t u d y i n g release of Κ f r o m K - f e l d s p a r s

a l l v i s u a l i z e the d e v e l o p m e n t of a r e a c t i o n film o n the g r a i n surface w h i c h is d e p l e t e d i n Κ ( h e n c e , r e l a t i v e l y h i g h i n s i l i c a ) a n d t h r o u g h w h i c h Κ ions m u s t diffuse as t h e y go f r o m the m i n e r a l i n t o solution. W o l l a s t

(17)

s t u d i e d the k i n e t i c s of s i l i c a release f r o m K - f e l d s p a r a n d stated t h a t " t h e w e a t h e r i n g of f e l d s p a r u n d e r n a t u r a l c o n d i t i o n s c a n b e d e s c r i b e d as a diffusion m e c h a n i s m of H S i 0 4

4

through a residual layer, constituted b y

s l i g h t l y s o l u b l e A l ( O H ) a n d subsequent r e a c t i o n of these t w o substances H

to f o r m a h y d r a t e d a l u m i n o - s i l i c a t e .

,,

L u c e (18)

f o u n d solid-state d i f

f u s i o n to be the r a t e - c o n t r o l l i n g step for b o t h s i l i c a a n d m a g n e s i u m d u r i n g


4.

Silica Variation

KENNEDY

in Stream

97

Water

e a r l y stages of l e a c h i n g of m a g n e s i u m silicates. I n s u m m a r i z i n g controls o n s i l i c a c o n c e n t r a t i o n i n s o i l w a t e r s , K i t t r i c k (19)

l i s t e d the f o l l o w i n g

factors: rate of d i s s o l u t i o n of u n s t a b l e silicates, rate of p r e c i p i t a t i o n of stable silicates, rate of m o v e m e n t of s i l i c a - b e a r i n g solutions out of the system, a n d rate of p l a n t u p t a k e . S o i l - l e a c h i n g studies i n d i c a t e t h a t some s i l i c a is r e l e a s e d f r o m s o i l rather r a p i d l y . M c K e a g u e a n d C l i n e (20)

have shown that i n soil-water

m i x t u r e s at 1 0 0 % w a t e r s a t u r a t i o n , the s i l i c a i n s o l u t i o n after 5 m i n u t e s was a p p r o x i m a t e l y h a l f as great as t h a t after 10 d a y s . A f t e r t h e first d a y or t w o the s i l i c a c o n c e n t r a t i o n i n c r e a s e d v e r y s l o w l y . T h e y also d e m o n strated t h a t p H has a m a r k e d effect o n s i l i c a concentrations i n s o i l s o l u Downloaded by UNIV LAVAL on April 7, 2016 | http://pubs.acs.org Publication Date: June 1, 1971 | doi: 10.1021/ba-1971-0106.ch004

tions (21).

T h e s e authors a t t r i b u t e d the c o n t r o l of s i l i c a c o n c e n t r a t i o n

to p H - d e p e n d e n t

a d s o r p t i o n a n d i n d i c a t e d t h a t , of the c o m m o n

soil

m i n e r a l s , i r o n a n d a l u m i n u m oxides h a v e a p p r e c i a b l e a d s o r p t i o n c a p a c i t y . Jones a n d H a n d r e c k (22,

23)

s t u d i e d the effects of i r o n a n d a l u m i n u m

oxides o n s i l i c a concentrations i n s o i l solutions a n d c o n c l u d e d t h a t b o t h c a u s e d a significant r e d u c t i o n i n d i s s o l v e d s i l i c a , w i t h a l u m i n u m oxides b e i n g most effective.

M i n i m u m s i l i c a concentrations

occurred

9 - 1 0 i n solutions i n contact w i t h i r o n a n d a l u m i n u m oxides. F l e h m i g (24)

at p H

Harder and

r e p o r t e d that the h y d r o x i d e s of i r o n , a l u m i n u m , a n d other

elements c o u l d r e m o v e s i l i c a f r o m solutions c o n t a i n i n g as l i t t l e as 0.5 mg/liter Si0 . 2

B r i c k e r a n d G o d f r e y ( 2 5 ) f o u n d t h a t o n l y a f e w h o u r s to a f e w d a y s w e r e n e e d e d for the s i l i c a c o n c e n t r a t i o n to a c h i e v e a constant v a l u e i n w a t e r r e c y c l e d t h r o u g h a s o i l c o l u m n . T h e same s i l i c a c o n c e n t r a t i o n w a s a t t a i n e d s t a r t i n g w i t h w a t e r c o n t a i n i n g either m o r e or less s i l i c a t h a n that at " e q u i l i b r i u m . " S i m i l a r conclusions r e g a r d i n g the s t a b i l i z i n g effect of s o i l o n d i s s o l v e d s i l i c a w e r e r e a c h e d b y M i l l e r

(26).

T h e w o r k d e s c r i b e d a b o v e shows t h a t s i l i c a c a n b e r e l e a s e d o r t a k e n u p r a p i d l y — t h a t is, w i t h i n a f e w m i n u t e s or h o u r s — a n d t h a t the m e c h a n i s m is not s i m p l y one of s o l u b i l i t y . Methods of Sample Treatment

and

Analysis

W a t e r samples o b t a i n e d i n this s t u d y w e r e c o l l e c t e d n e a r m i d s t r e a m i n p o l y e t h y l e n e bottles a n d filtered t h r o u g h 0 . 4 5 - m i c r o n m e m b r a n e as soon as possible

after c o l l e c t i o n u s i n g c o m p r e s s e d

filters

air. N o r m a l l y ,

samples of 4 - 8 liters w e r e passed t h r o u g h a 4 - i n c h ( 1 0 . 1 6 - c m ) d i a m e t e r filter,

a n d the first 1-1.5 liters w e r e d i s c a r d e d . E x c e p t u n d e r c o n d i t i o n s

of u n u s u a l l y clear w a t e r , the filter w a s p a r t i a l l y c l o g g e d b y

sediment

b e f o r e a n y filtrate w a s r e t a i n e d , so the effective p o r e size of the

filter

was p r o b a b l y less t h a n 0.2 m i c r o n for most samples a n d less t h a n 0.1 m i c r o n for samples c o l l e c t e d d u r i n g l a r g e r flows w h e n s e d i m e n t

concen-

trations w e r e h i g h . W h e n samples c o n t a i n i n g m o r e t h a n 5000 m g / l i t e r


98

NONEQUILIBRIUM

of s u s p e n d e d s e d i m e n t w e r e

filtered,

SYSTEMS

the t i m e for

IN

NATURAL

filtration

occasionally

exceeded 6 hours but c o m m o n l y 2-4 hours were required. After 4 m l of reagent g r a d e c o n c e n t r a t e d H N 0 filtrate,

3

WATERS

filtration,

was a d d e d to e a c h g a l l o n of

w h i c h was stored i n a polyethylene bottle u n t i l it was analyzed

f o r m a j o r constituents. S u s p e n d e d - s e d i m e n t s a m p l e s w e r e o b t a i n e d at l o w

flow

by

com-

p o s i t i n g w a t e r samples c o l l e c t e d at three points i n the cross section. U n d e r h i g h e r flow c o n d i t i o n s , s a m p l i n g w a s d o n e at five p o i n t s e q u a l l y s p a c e d i n the cross section. T h e s a m p l i n g d e v i c e , a D H - 5 9 h a n d s a m p l e r ( 2 7 ) , w a s p a s s e d t h r o u g h the w a t e r c o l u m n at the same rate at e a c h s a m p l i n g p o i n t so t h a t the w a t e r c o l l e c t e d r e p r e s e n t e d the i n t e g r a t e d Downloaded by UNIV LAVAL on April 7, 2016 | http://pubs.acs.org Publication Date: June 1, 1971 | doi: 10.1021/ba-1971-0106.ch004

effect of s t r e a m v e l o c i t y a n d d e p t h .

T h u s , a l l five samples c o u l d

be

c o m p o s i t e d to represent the average s e d i m e n t c o n c e n t r a t i o n i n the s t r e a m as a w h o l e . U n d e r v e r y h i g h flow c o n d i t i o n s , w h e n w a t e r v e l o c i t i e s n e a r the surface a p p r o a c h e d 15 feet (4.5 m e t e r s ) p e r s e c o n d ( 2 8 ) , o n l y s a m ples o f the u p p e r 2 feet ( 0.5 m e t e r ) of flow c o u l d b e o b t a i n e d .

However,

the extreme t u r b u l e n c e u n d e r s u c h c o n d i t i o n s s h o u l d h a v e c a u s e d suffic i e n t v e r t i c a l m i x i n g that the samples t r u l y r e p r e s e n t e d the average c o n c e n t r a t i o n of t r a n s p o r t e d s e d i m e n t of m e d i u m s a n d size a n d

finer.

The

s i z e a b l e l o a d of coarse s a n d a n d g r a v e l m o v i n g near the s t r e a m b e d w a s not s a m p l e d .

Suspended-sediment

samples w e r e a l w a y s t a k e n w i t h i n

1 5 - 2 0 m i n u t e s of the c o l l e c t i o n of w a t e r samples. S i l i c a analyses w e r e m a d e o n a n a u t o m a t i c a n a l y z e r u s i n g a m o d i f i c a t i o n of the m e t h o d of M u l l i n a n d R i l e y ( 2 9 ) .

C h l o r i d e analyses w e r e

also m a d e o n the a u t o m a t i c a n a l y z e r , u s i n g the m e t h o d of O ' B r i e n

(30).

C o n d u c t i v i t y measurements u s u a l l y w e r e m a d e o n the pressure-filtered

Figure

1.

Index map of River Basin

Mattole


4.

Silica Variation

KENNEDY

samples.

in Stream

99

Water

E n o u g h d e t e r m i n a t i o n s w e r e m a d e to e s t a b l i s h that n o

change

i n c o n d u c t i v i t y c o u l d b e d e t e c t e d b e t w e e n filtered a n d u n f i l t e r e d samples. T h e specific c o n d u c t a n c e w a s u s e d as a n i n d e x of the c o n c e n t r a t i o n of d i s s o l v e d electrolytes i n the w a t e r a n d w a s d e t e r m i n e d for e v e r y s a m p l e collected.

C a , M g , N a , and Κ were determined using an atomic absorp

t i o n spectrophotometer.

Mattole

Drainage

Basin

T h e M a t t o l e b a s i n is i n n o r t h e r n C a l i f o r n i a ( F i g u r e 1 ) , a n d a n area of a b o u t 240 square m i l e s lies u p s t r e a m f r o m the s a m p l i n g p o i n t u s e d i n Downloaded by UNIV LAVAL on April 7, 2016 | http://pubs.acs.org Publication Date: June 1, 1971 | doi: 10.1021/ba-1971-0106.ch004

this s t u d y .

R a n c h i n g a n d t i m b e r sales h a v e b e e n the m a j o r source

of

i n c o m e b u t a little f a r m i n g is d o n e o n s u i t a b l e areas a l o n g the r i v e r . T h e towns g e n e r a l l y consist of just a f e w r a t h e r o l d b u i l d i n g s w i t h some other homes i n the v i c i n i t y . A v e r a g e p o p u l a t i o n is p r o b a b l y less t h a n t w o persons p e r square m i l e . Topography and Geology.

T o p o g r a p h y is m a t u r e w i t h a m a x i m u m

relief of a p p r o x i m a t e l y 3500 feet a n d a n average r e l i e f of p e r h a p s feet.

1500

T h e rocks i n the b a s i n are m a i n l y f o l d e d g r a y w a c k e , shale, a n d

conglomerate

(31).

A n o r t h w e s t strike of the f o l d e d a n d f a u l t e d s e d i

m e n t a r y rocks causes

the n o r t h w e s t t r e n d of the stream b a s i n .

The

d o w n s t r e a m h a l f of the b a s i n is c h a r a c t e r i z e d i n p a r t b y steep grassy slopes w i t h shrubs a n d second g r o w t h trees l o c a t e d a l o n g some d r a i n a g e lines a n d c o v e r i n g some w h o l e t r i b u t a r y basins ( F i g u r e 2 ). T h e u p s t r e a m h a l f of the b a s i n contains l a r g e areas of s e c o n d - g r o w t h

timber

with

scattered grasslands i n a n area of s o m e w h a t gentler t o p o g r a p h y . Soils a n d Sediments. Soils i n the M a t t o l e b a s i n r a n g e f r o m g r a v e l l y to c l a y l o a m (32)

a n d are a c i d w i t h a p H g e n e r a l l y i n the range 4.6-6.0.

I n one 9-foot profile of u p l a n d s o i l s a m p l e d i n this s t u d y , the p H r a n g e d f r o m 4.8-5.2.

W h e r e r e l a t i v e l y l i t t l e recent erosion has o c c u r r e d ,

the

soils are 10 feet or m o r e i n d e p t h . H o w e v e r , i n the last 20 years there has been extensive l o g g i n g a n d r o a d - b u i l d i n g a c t i v i t y , a n d this has b e e n a factor i n the d i s t u r b a n c e a n d r e s u l t i n g erosion of the s o i l .

A t present,

erosion i n the b a s i n is r a p i d , a n d a l o n g d r a i n a g e lines o n some of the slopes the s o i l has b e e n c o m p l e t e l y r e m o v e d to b e d r o c k .

T h i s erosion

has c a u s e d a g g r a d a t i o n of the r i v e r b e d , a n d s u s p e n d e d - s e d i m e n t centrations i n the r i v e r n o w exceed 10,000 m g / l i t e r d u r i n g h i g h

con

flows.

X - r a y d i f f r a c t i o n analyses of the < 2 - m i c r o n size f r a c t i o n of s u s p e n d e d s e d i m e n t a n d soils f r o m t h e M a t t o l e b a s i n i n d i c a t e that k a o l i n i t e , v e r m i c u l i t e , a n d a l u m i n u m - i n t e r l a y e r e d v e r m i c u l i t e c o m p r i s e the m a i n c l a y m i n e r a l s . M u c h s m a l l e r amounts of i l l i t e c o m m o n l y are present. C h l o r i t e is detectable i n a f e w s u s p e n d e d - s e d i m e n t

samples.



100

NONEQUILIBRIUM

Figure

2.

SYSTEMS

IN

NATURAL

WATERS

View of lower Mattole River basin showing bridge from sampling was done

which

V e r m i c u l i t e i d e n t i f i c a t i o n is b a s e d u p o n the presence of a m i n e r a l h a v i n g a 14-Â d - s p a c i n g w i t h M g s a t u r a t i o n a n d g l y c o l s o l v a t i o n w h i c h collapses to 10.5 Â w i t h Κ s a t u r a t i o n a n d a i r d r y i n g ( 3 3 ) . e x p a n s i o n a b o v e 14 Â w h e n m a g n e s i u m - s a t u r a t e d

T h e r e is l i t t l e

c l a y is s o l v a t e d w i t h

ethylene

g l y c o l , w h i c h i n d i c a t e s that little, i f a n y , m o n t m o r i l l o n i t e

present.

W h e n h e a t e d to 5 5 0 ° C , o n l y c l a y w i t h a b o u t a 10-Â

r e m a i n s i n most samples, b u t a s m a l l a m o u n t of c h l o r i t e i n a f e w samples is i n d i c a t e d b y the presence of 14-Â s p a c i n g ( 3 4 ) . aluminum-interlayered vermiculite

(or

possibly

is

(f-spacing sediment

E v i d e n c e for

aluminum-interlayered

m o n t m o r i l l o n i t e ) is the presence of a 14-Â m i n e r a l i n M g - s a t u r a t e d s a m ples w h i c h fails to collapse to a b o u t 10 Â o n Κ s a t u r a t i o n ( 3 5 ) b u t w h i c h is n e i t h e r m o n t m o r i l l o n i t e n o r c h l o r i t e , based o n g l y c o l l a t i o n or h e a t i n g to 5 5 0 ° C . P r e c i p i t a t i o n . R a i n f a l l averages 92 inches p e r y e a r for the b a s i n as a w h o l e b u t w i t h i n the b a s i n ranges f r o m a b o u t 50 to 110 inches. O f t h i s , 7 6 % appears as runoff ( 3 6 ) .

T h e b u l k of the a n n u a l r a i n f a l l occurs i n the

m o n t h s of N o v e m b e r t h r o u g h M a r c h , w i t h intense d o w n p o u r s w i t h some storms.

associated

N o r m a l l y , l i t t l e or no r a i n falls f r o m late M a y u n t i l

late O c t o b e r . The

average c o m p o s i t i o n

of

p r e c i p i t a t i o n f a l l i n g i n the

Mattole

R i v e r b a s i n is s h o w n i n T a b l e I. Samples w e r e c o l l e c t e d near P e t r o l i a , Honeydew,

E t t e r s b u r g , a n d T h o r n d u r i n g p a r t of

the 1 9 6 6 - 6 7 r a i n y


4.

Silica Variation

KENNEDY

Table I.

in Stream

101

Water

Composition of Atmospheric Precipitation in the Mattole River Basin Weighted Average Values January-May 1967

Constituent Ca + Mg + Na+ K+ S0 CI" Si0 2

4

2

2


October-A pril 1968-69

5.5 0.4 1.1 0.1 6.4 1.6 0.1

2

(mg/liter)

2.2 0.3 0.9 0.1 4.7 1.7 3 0 0 ) , a n d r a t h e r l o w s i l i c a ( 7 - 8 m g / l i t e r ) . T h u s , the alkalis a n d a l k a l i n e earths are p r e f e r e n t i a l l y r e m o v e d as c o m p a r e d w i t h s i l i c a f r o m r o c k m i n e r a l s at or near the w a t e r t a b l e .

I n surface soils, h o w e v e r , d u r i n g

s t o r m runoff, q u i t e different c o n d i t i o n s p r e v a i l . T h e p H of the w a t e r m a y at first b e l o w ( 5 ± ) ,

s i l i c a release is r e l a t i v e l y r a p i d ( 8 - 1 2

mg/

l i t e r ) , a n d alkalis a n d a l k a l i n e earths are r e m o v e d r a t h e r s l o w l y ( S p e c . Cond. 70-150).

T h e result is t h a t the rate of s i l i c a r e m o v a l


compared

126

NONEQUILIBRIUM SYSTEMS IN N A T U R A L WATERS

w i t h t h a t of the m a j o r cations is a b o u t f o u r times as great d u r i n g s t o r m runoff as at l o w

flow.

E v e n d u r i n g s t o r m runoff, h o w e v e r , the r a t i o of

s i l i c a to a l k a l i s a n d a l k a l i n e earths i n s o l u t i o n is m u c h less t h a n the r a t i o i n p r i m a r y minerals. F r o m the s t a n d p o i n t of the a n n u a l l o a d of d i s s o l v e d s i l i c a , t h e l a c k of c o r r e l a t i o n b e t w e e n s i l i c a c o n c e n t r a t i o n a n d d i s c h a r g e , w h e n c o n s i d e r e d o n a n a n n u a l basis (see

F i g u r e 8 ) , means t h a t s i l i c a l o a d c a n b e

c a l c u l a t e d as t h o u g h i t v a r i e d d i r e c t l y w i t h d i s c h a r g e . of

flow-duration

T h i s a l l o w s use

curves to c o m p u t e the t i m e d i s t r i b u t i o n of s i l i c a l o a d

carried b y the M a t t o l e R i v e r . Such information was obtained from the r e p o r t of R a n t z a n d T h o m p s o n Downloaded by UNIV LAVAL on April 7, 2016 | http://pubs.acs.org Publication Date: June 1, 1971 | doi: 10.1021/ba-1971-0106.ch004

were made.

(36),

a n d the necessary

computations

T h e s e s h o w t h a t a b o u t 25, 60, a n d 9 0 % of the a n n u a l d i s

s o l v e d s i l i c a l o a d is c a r r i e d b y the M a t t o l e i n 2, 10, a n d 3 5 % of the t i m e , respectively.

B e c a u s e s t o r m runoff makes u p most of the s t r e a m

i n the M a t t o l e d u r i n g at least 2 0 %

of the y e a r , 7 5 %

or m o r e of

flow the

d i s s o l v e d s i l i c a t r a n s p o r t e d b y the M a t t o l e R i v e r a n n u a l l y is d e r i v e d f r o m near-surface soils r a t h e r t h a n f r o m w e a t h e r i n g of soils a n d rocks at d e p t h . S o m e tentative c o n c l u s i o n s c a n n o w b e d r a w n r e g a r d i n g the w a y i n w h i c h s i l i c a is released f r o m M a t t o l e soils. T h e l i n e a r r e l a t i o n b e t w e e n s i l i c a c o n c e n t r a t i o n a n d the square root of t i m e i n s o i l a n d

sediment

suspensions, w h e r e d i s s o l v e d s i l i c a is less t h a n a b o u t 1 m g / l i t e r , suggests t h a t a d i f f u s i o n m e c h a n i s m controls the release o f s i l i c a f r o m m i n e r a l particles.

S u c h a m e c h a n i s m w o u l d b e i n a g r e e m e n t w i t h studies b y

others (14,

17, I S ) .

T h o s e studies suggest that i n the i n i t i a l release of

silica from feldspar only a diffusion mechanism w o u l d be apparent, b u t as the s i l i c a c o n c e n t r a t i o n i n c r e a s e d a subsequent

sorption

(precipita

t i o n ? ) r e a c t i o n o n the a l t e r e d s o l i d surface w o u l d s l o w the net release of s i l i c a u n t i l a r e l a t i v e l y steady c o n d i t i o n existed. T h i s appears to b e a p a t t e r n t h a t w o u l d e x p l a i n the s i l i c a released f r o m b o t h l o w a n d h i g h concentrations of p r e w a s h e d M a t t o l e s o i l a n d s e d i m e n t i n w a t e r . T h e f o l l o w i n g s e q u e n c e for the release of s i l i c a f r o m soils a n d rocks of t h e M a t t o l e b a s i n is i n d i c a t e d b y a v a i l a b l e d a t a . A t the e n d of the s u m m e r , surface soils c o n t a i n w e a t h e r i n g p r o d u c t s t h a t i n c l u d e r e a d i l y s o l u b l e s i l i c a . E a r l y r a i n s , w h i c h are too l i g h t to c a u s e runoff, m a y c a r r y m u c h of this s o l u b l e m a t e r i a l i n t o the l o w e r A a n d u p p e r Β s o i l h o r i z o n s . B u t h y d r a t i o n of m i n e r a l surfaces encourages f u r t h e r w e a t h e r i n g a n d the f o r m a t i o n of m o r e s o l u b l e s i l i c a w h i c h is a v a i l a b l e for r e m o v a l w i t h the first runoff.

W h e n r a i n f a l l is h e a v i e r t h a n t h a t r e q u i r e d to saturate the

surface s o i l , o v e r l a n d flow a n d subsurface flow, the latter c o n t a i n i n g some of the e a s i l y - s o l u b l e s i l i c a , j o i n together

to cause a s t r e a m rise.

r a i n f a l l c o n t i n u e s , the surface s o i l is l e a c h e d , a n d s i l i c a diffuses

As into

s o l u t i o n i n the s o i l w a t e r u n t i l i t reaches a l i m i t i n g c o n c e n t r a t i o n w h i c h represents a b a l a n c e b e t w e e n the

flushing

rate a n d the rate of


release

4.

KENNEDY

Silica Variation

in Stream

127

Water

f r o m s o i l m a t e r i a l s . W h e n r a i n stops, the s i l i c a c o n c e n t r a t i o n i n s o i l w a t e r increases to a n e w p l a t e a u l e v e l w i t h i n 24 h o u r s or less. I f m o r e r a i n falls o n the m o i s t s o i l , the d i s s o l v e d s i l i c a a n d some s o r b e d or f r e s h l y r e p r e c i p i t a t e d s i l i c a f o r m a r e s e r v o i r of r e a d i l y - a v a i l a b l e s i l i c a w h i c h c a n b e flushed o u t first. W i t h m o r e r a i n a n d l e a c h i n g , d i f f u s i o n a g a i n b e c o m e s a n i m p o r t a n t process, s u p p l y i n g the s i l i c a to the s u b s u r f a c e runoff.

As

the r a i n y season continues, the c o n c e n t r a t i o n of s i l i c a i n s o i l w a t e r s l o w l y increases.

A f t e r the r a i n y season ends, w a t e r continues to d r a i n f r o m

s u p e r f i c i a l deposits for s e v e r a l m o n t h s , a n d s i l i c a concentrations i n t h e r i v e r r e m a i n w e l l a b o v e those o b s e r v e d at the e n d of t h e s u m m e r d r y period.

A s g r o u n d w a t e r c o n t a i n i n g l o w e r concentrations of s i l i c a b e -


comes a n i n c r e a s i n g p a r t of the s t r e a m flow, s i l i c a decreases i n c o n c e n t r a t i o n . I n late O c t o b e r or e a r l y N o v e m b e r , a n e w c y c l e begins. Summary

and

Conclusions

S i l i c a concentrations i n the M a t t o l e R i v e r of n o r t h e r n C a l i f o r n i a v a r y i n a consistent p a t t e r n w i t h r e l a t i o n to d i s c h a r g e a n d t o t a l c o n c e n t r a t i o n of electrolytes, as m e a s u r e d b y specific c o n d u c t a n c e .

D u r i n g the i n i t i a l

p a r t of a s t r e a m rise, b o t h s i l i c a a n d electrolytes decrease i n a n e a r l y constant r a t i o , b u t as the rise continues, the rate of s i l i c a decrease slows r e l a t i v e to that of the electrolytes, c a u s i n g the S i 0 : S p e c . C o n d . r a t i o 2

to t u r n u p w a r d . C o m m o n l y , 2 - 4 hours b e f o r e p e a k d i s c h a r g e , m i n i m u m silica occur.

concentration

and m a x i m u m suspended

sediment

concentration

A t p e a k d i s c h a r g e , the specific c o n d u c t a n c e is at a m i n i m u m b u t

b o t h s i l i c a a n d the r a t i o S i 0 : S p e c . C o n d . are r i s i n g a n d c o n t i n u e to d o 2

so for another 1 2 - 1 8 hours. T h e n s i l i c a c o n c e n t r a t i o n b e c o m e s a l m o s t constant w h i l e specific c o n d u c t a n c e r a t i o b e t w e e n t h e m to decrease. crease s l o w l y .

continues to increase, c a u s i n g the

A f t e r s e v e r a l days, s i l i c a begins to d e -

T h i s c y c l e is r e p e a t e d w i t h e a c h s t r e a m rise.

Enough

d a t a f r o m other streams are a v a i l a b l e to suggest that the p a t t e r n occurs elsewhere. T h e silica-concentration pattern observed

i n the M a t t o l e e x p l a i n s

b o t h the l a c k of h i g h c o r r e l a t i o n b e t w e e n s i l i c a a n d d i s c h a r g e or specific c o n d u c t a n c e a n d the r e l a t i v e l y s m a l l changes i n s i l i c a c o n c e n t r a t i o n w i t h d i s c h a r g e n o t e d b y investigators for other streams. B e c a u s e the m i n i m u m i n s i l i c a c o n c e n t r a t i o n a n d m a x i m u m i n s e d i m e n t c o n c e n t r a t i o n n o r m a l l y p r e c e d e p e a k d i s c h a r g e , p e a k o v e r l a n d flow p r o b a b l y also precedes p e a k d i s c h a r g e . T h e r e f o r e , runoff that has spent a n a p p r e c i a b l e p e r i o d of t i m e i n s o i l pores contributes a m a j o r p a r t of the s t r e a m flow at p e a k d i s c h a r g e . T h e r a t h e r s m a l l decrease i n s i l i c a c o n c e n t r a t i o n d u r i n g a stream rise supports this i n t e r p r e t a t i o n . B e c a u s e l i t t l e s i l i c a c a n b e o b t a i n e d b y i n t e r a c t i o n b e t w e e n w a t e r a n d stream s e d i m e n t


128

NONEQUILIBRIUM SYSTEMS IN N A T U R A L WATERS

d u r i n g t r a n s p o r t , the r e l a t i v e l y h i g h c o n c e n t r a t i o n of s o l u b l e s i l i c a m u s t result f r o m p e r c o l a t i o n of w a t e r t h r o u g h the s o i l i m m e d i a t e l y after f a l l i n g as r a i n . T h i s a p p a r e n t l y o c c u r s o n slopes of 1 5 ° - 2 5 ° that are c o m m o n i n the M a t t o l e b a s i n . I f i t c a n b e s h o w n that s i l i c a m i n i m a a n d s e d i m e n t m a x i m a m a r k p e a k o v e r l a n d flow elsewhere a n d that the e n d of o v e r l a n d flow is m a r k e d b y a l e v e l i n g off i n s i l i c a c o n c e n t r a t i o n after p e a k d i s c h a r g e i n s t r e a m flow,

t h e n m o n i t o r i n g of these p a r a m e t e r s s h o u l d b e v e r y h e l p f u l i n

s e p a r a t i n g s t o r m runoff i n t o the v a r i o u s c o m p o n e n t s of

flow.

T h e r a p i d a c h i e v e m e n t of a " c o n s t a n t " v a l u e of s i l i c a i n s o i l w a t e r demonstrates that the o p p o r t u n i t y for e q u i l i b r a t i o n exists, b u t the electro Downloaded by UNIV LAVAL on April 7, 2016 | http://pubs.acs.org Publication Date: June 1, 1971 | doi: 10.1021/ba-1971-0106.ch004

lytes d o not s h o w a n y signs of r e a c h i n g a p l a t e a u c o n c e n t r a t i o n .

The

electrolytes a p p a r e n t l y d o not e q u i l i b r a t e w i t h the s o i l d u r i n g o r s h o r t l y after a s t o r m p e r i o d . T h u s , d u r i n g s t o r m runoff, w h e n m o r e t h a n 7 5 % of the a n n u a l d i s c h a r g e occurs, there is not sufficient t i m e for c h e m i c a l e q u i l i b r i u m of the electrolytes to b e r e a c h e d i n s o i l w a t e r , a n d i t appears that r e a c t i o n k i n e t i c s m u s t b e a n i m p o r t a n t factor i n d e t e r m i n i n g the concentrations of the electrolytes. W o r k o n M a t t o l e R i v e r w a t e r a n d studies of s o i l - w a t e r interactions i n d i c a t e that d e t a i l e d investigations of changes i n w a t e r c h e m i s t r y d u r i n g s t o r m runoff c a n b e a p o w e r f u l t o o l i n o b t a i n i n g a better u n d e r s t a n d i n g of w e a t h e r i n g reactions.

T h e use of ratios b e t w e e n constituents c a n b e

e s p e c i a l l y h e l p f u l because d i l u t i o n is e l i m i n a t e d as a factor.

Sampling

i n t e r v a l s a p p a r e n t l y s h o u l d not exceed 2 hours d u r i n g a s t r e a m rise, a n d 1-hour intervals are p r e f e r r e d .

A s basins increase i n size, t r a v e l - t i m e

effects m a y o b s c u r e changes i n c h e m i s t r y o w i n g to w e a t h e r i n g reactions. It is d e s i r a b l e , therefore, to w o r k w i t h the smallest b a s i n that c a n c o n s i d e r e d representative of the area u n d e r study.

be

M i n o r changes i n

c o n c e n t r a t i o n trends c a n b e seen best i f samples are r u n i n s e q u e n c e , u s i n g a u t o m a t i c e q u i p m e n t for analysis. Acknowledgment R . L . M a l c o l m w o r k e d w i t h the a u t h o r i n c o l l e c t i n g m a n y of the w a t e r samples, often u n d e r adverse c o n d i t i o n s . W a t e r samples w e r e also collected b y M r . and M r s . T . E . M a t h e w s a n d b y John Schonrock.

Many

of the ideas expressed h a v e b e e n d i s c u s s e d a n d m o d i f i e d as a r e s u l t of talks w i t h E . A . Jenne, J . D . H e m , a n d Κ. V . S l a c k . E . A . J e n n e , J . D . H e m , R . M . G a r r e l s , S. N . D a v i s , P . B . H o s t e t l e r , a n d D . R . S c h i n k r e a d the m a n u s c r i p t a n d suggested

improvements.

Analyses were made

by

C . S. B a r w i s , E . A . C l a r k e , a n d D . K . M a c D o n a l d or w e r e m a d e i n the S a c r a m e n t o , C a l i f o r n i a l a b o r a t o r y of the U . S. G e o l o g i c a l S u r v e y u n d e r the s u p e r v i s i o n of J . W . H e l m s . T h e s t u d y w o u l d h a v e b e e n i m p o s s i b l e w i t h o u t the h e l p of these i n d i v i d u a l s .


4.

KENNEDY

Silica

Variation

in Stream

Water

129

Literature Cited


(1) Davis, S. N., Am. J. Sci. (1964) 262, 870. (2) Palmer, Chase, U. S. Geol. Surv. Bull. (1911) 479, 24. (3) Hendrickson, G. E., Krieger, R. Α., U. S. Geol. Surv. Water-Supply Paper (1964) 1700, 93. (4) Davis, S. N., Univ. Hawaii Water Resources Res. Center Tech. Rept. (1969) 29. (5) Feth, J. H., Roberson, C. E., Polzer, W. L., U. S. Geol. Surv. Water -Supply Paper (1964) 1535-I, 39. (6) Krauskopf, Κ. B., Geochim. Cosmochim. Acta (1956) 10, 1. (7) Siever, R., J. Geol. (1962) 70, 127. (8) Morey, G. W., Fournier, R. O., Rowe, J. J., Geochim. Cosmochim. Acta (1962) 26, 1029. (9) Stöber, W., "Equilibrium Concepts in Natural Water Systems," ADVAN. C H E M . SER. (1967) 67, 161-82.

(10) Garrels, R. M., Christ, C. E., "Solutions, Minerals, and Equilibria," p. 361, Harper and Row, New York, 1965. (11) Polzer, W. L., Hem, J. D., J. Geophys. Res. (1965) 70, 6223. (12) Mackenzie, F. T., Garrels, R. M., Science (1967) 150, 57. (13) Mackenzie, F. T., Garrels, R. M., Bricker, O. P., Bickley, Frances, Science (1967) 155, 1404. (14) Correns, C. W., von Engelhardt, W., Chem. Erde (1938) 12, 1. (15) Nash, V. E., Marshall, C. E., Missouri Univ. Res. Bull. (1956) 613, Pt. 1. (16) Garrels, R. M., Howard, P. F., Clays Clay Minerals (1959) 6, 68. (17) Wollast, R., Geochim. Cosmochim. Acta (1967) 31, 635. (18) Luce, R. W., Ph.D. dissertation, Stanford University, 1969. (19) Kittrick, J. Α., Clays Clay Minerals (1969) 17, 157. (20) McKeague, J. Α., Cline, M. G., Can. J. Soil Sci. (1963) 43, 70. (21) Ibid., (1963) 43, 83. (22) Jones, L. H. P., Handreck, Κ. Α., Nature (1963) 198, 852. (23) Jones, L. H. P., Handreck, Κ. Α., Advan. Agron. (1967) 19, 107. (24) Harder, H., Flehmig, W., Geochim. Cosmochim. Acta (1970) 34, 296. (25) Bricker, O. P., Godfrey, A. E . , "Trace Inorganics in Water," ADVAN. C H E M . SER. (1968) 73, 128-42.

(26) Miller, R. W., Soil Sci. Soc. Am. Proc. (1967) 31, 46. (27) Inter-Agency Committee on Water Resources, Report No. 14, p. 60, Supt. of Documents, Washington, D. C., 1963. (28) LaRue, G. W., oral communication, 1970. (29) Mullin, J. B., Riley, J. P., Anal. Chim. Acta (1955) 12, 1962. (30) O'Brien, J. F., Wastes Eng. (1962) 33, 670. (31) Irwin, W. P., Calif. Div. Mines Bull. (1960) 179, 42. (32) McLaughlin, J., Harradine, F., "Soils of Western Humboldt Co., Calif.," p. 68, 71, 81-4, Univ. of Calif. at Davis, 1965. (33) Walker, G. F., "X-Ray Identification and Structures of Clay Minerals," Ch. VII, pp. 199-223, Mineral Society of Great Britain Monograph, 1951. (34) Grim, R. E., "Clay Mineralogy " 2nd ed., pp. 83, 105, McGraw-Hill, New York, 1968. (35) Hathaway, J. C., Clays Clay Minerals (1955) 3, 74. (36) Rantz, S. E., Thompson, T. H., U. S. Geol. Surv. Water-Supply Paper (1967) 1851, 38, 47. (37) U. S. Geological Survey, "Water Resources Data for California, 1968 W. Y.," Pt. 1, 426 (1968). (38) Barnes, Ivan, Geochim Cosmochim. Acta (1965) 29, 85. (39) Enright, J. T., Ecology (1969) 50, 1070.



130

NONEQUILIBRIUM

SYSTEMS

IN

NATURAL

WATERS

(40) Smith, G. M., "The Fresh Water Algae of the United States," 2nd ed., p. 451, McGraw-Hill, New York, 1950. (41) Dana, E. D., Ford, W. E., "A Textbook of Mineralogy," 4th ed., pp. 536, 659, 663, Wiley, New York, 1947. (42) Chow, V. T., "Handbook of Applied Hydrology," Sec. 14, p. 2, McGraw-Hill, New York, 1964. (43) Storey, H. C., Hobba, R. L., Roas, J. M., "Handbook of Applied Hydrology," Sec. 22, p. 10, McGraw-Hill, New York, 1964. (44) Jamieson, D. G., Amerman, C. R., J. Hydrol. (1969) 8, 122. (45) Pinder, G. F., Jones, J. F., Water Resources Res. (1969) 5, 438. (46) Steele, T. D., "Seasonal Variations in Chemical Quality of Surface Water in the Pescadero Creek Watershed," Ph.D. dissertation, Stanford University, 1968. (47) U. S. Weather Bureau, "Climatological Data for California," Vols. 11 and 12, 1966. RECEIVED June 29, 1970. Publication authorized by the Director, U. S. Geological Survey.


Nonequilibrium Systems in Natural Water Chemistry - ACS Publications

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