SILICA IN STREAMS AND GROUND WATER OF HAWAII
by
Stanley N. Davis
Technical Report No. 29
January 1969
Project Completion Report
of
IDENTIFICATION OF IRRIGATION RETURN WATER IN THE SUBSURFACE
OWRR Project No. B-010-HI, Grant Agreemtn No. 14-01-001-1495
Principal Investigators:
Project Period:
Reginald H.F. Young, Stanley N. Davis
and H. Collins Whitehead
July 1, 1967 to June 30, 1968
The programs and activities described herein were supported in part by funds
provided by the United States Department of the Interior as authorized under
the Water Eesources Act of 1964, Public Law 88-379.
ABSTRACT
Concentrations of silica in natural waters of Hawaii vary from
less than 0.2 ppm in rain water to almost 90 ppm in ground water. The
acquisition of silica by the water is probably most rapid near the
ground surface. Between 1 and 3 ppm will go into solution within a
few minutes after rain comes in contact with the rock and soil. Rain
water that percolates to the subsurface and eventually becomes groundwater recharge will have from 5 to 20 ppm silica before it reaches
high-level dike compartments. The high-level water will continue to
dissolve more silica until it has from 15 to 45 ppm silica. Some of
the dike water will discharge into streams which in turn recharge the
basal-water body and some will leak directly into the basal-water body.
Basal water that may start with 25 to 45 ppm silica will slowly dissolve
more silica until it contains from 30 to 60 ppm. Concentrations of more
than about 40 ppm appear to be correlated with irrigation return water
and in addition may be owing to dissolution of less weathered rocks in
the more arid parts of Oahu as well as the other islands of Hawaii.
Rates of silica removal in small watersheds of the high-rainfall
portions of the Koolau Range appear to be as much as 8 mg/cm2/yr~ which
is more than any other area in the United States. Silica in a relatively soluble fo~ in the basaltic bedrock together with unusually large
amounts of water from frequent rains account for the rapid removal of
silica in solution. w~ climate and tropical vegetation do not appear
to be necessary for the rapid leaching of silica.
iii
CONTENTS
LI ST· OF TABLES .....................•................................. v
LIST OF FIGURES
vi
INTRODUCTION
1
SOURCES OF DATA
2
SURFACE RUNOFF
9
STREAM ',lATER
11
WATER FROM TUNNELS
13
BASAL GROUND WATER
14
WATER FROM LEACH TESTS
16
RATES OF SILICA REMOVAL.
17
CONCLUS IONS
22
ACKNOWLEDGP~ENTS
23
BIBLIOGRAPHy
24
APPENDIX: SELECTED ANALYSES OF WATERS FROM VARIOUS PACIFIC
ISLANDS AND VENEZUELA
27
LIST OF TABLES
Table
Description of Location of Streams and Other Sample
Collection Data
2 Description of Sampling Sites of Artificial Runoff
3 Description of Samples Used for Leaching Tests
4 Che~ical Analyses of Stream Samples
5 Chemical Analyses of Artificial Runoff
6 Chemical Analyses of Leach Water
7 Median Composition of Stream Water from the Hawaiian
Islands
·
8 Median Composition of High-Level Tunnel Water,
Koo 1au Range, Oahu
9 Median Composition of Basal Ground Water
lOS il i ca Removed from Se1ected ~la tersheds
v
4
5
6
7
8
8
11
13
14
18
LIST OF FIGURES
Figure
2
Approximate Concentrations of Silica in Waters of the
Hawaiian Islands
Relationship between Total Runoff and Rate of Removal
of Silica for Various Watersheds
vi
19
2l
INTRODUCTION
Dissolved silica in water has been of minor concern to most water
engineers inasmuch as it affects only the utility of water for highpressure boilers, electroplating, and a few other industrial uses that
require a purity approaching that of distilled water.
Indeed, the lack
of interest is such that many people consider water analyses to be complete even though the amount of dissolved silica has not been determined.
During the past decade, however, researchers studying the genesis of
chert, clays, aluminum ore, and various soil components have made an
increased effort to obtain more data concerning silica in water and to
understand the natural variations of silica in terms of the principles
of physical chemistry.
(Garrels, 1965; Gifford
and Frugoli, 1964;
Jones, Rettig, and Eugster, 1967, Fox, et aZ., 1967.)
Silica in ground water has also been of interest to hydrogeologists as an index to
the overall lithology of aquifers.
Water
traveling slowly in the subsurface will approach chemical equilibrium
with minerals present in the aquifers.
Under normal conditions of tem-
perature and pressure, median silica concentrations in ground water varies
from low values of about 7 ppm in carbonate aquifers to about 85 ppm
in aquifers containing unaltered rhyolitic ash (Davis, 1964).
Water
from unweathered or slightly weathered basaltic aquifers generally
ranges from 25 to 75 ppm and has a median silica value of about 45 ppm,
(see Appendix, also Davis, 1964; White, Hem, and Waring, 1963).
Theoret-
ically, if the water were in chemical equilibrium and if the thermodynamic
properties and amounts of all minerals present were known, then the
exact silica concentrations of water in the subsurface might be predicted.
Many reactions involving silicate minerals, however, are sluggish and
equilibrium carr.lot be assumed, particularly in highly permeable basaltic
aquifers.
Furthermore, the types and distribution of minerals may
be quite varied and difficult to determine in most aquifers.
Despite
these complicating factors, however, field data indicate that silica
values for any given aquifer lithology are moderately uniform.
Visher and Mink (1964) have suggested that the silica content of
ground water on Oahu can be used to help differentiate normal ground
water which has from 20 to 50 ppm silica from return irrigation water
which generally has from 40 to 75 ppm silica.
If this criterion for
2
return irrigation water is reliable, then the silica content of subsurface
water should also prove valuable in helping to understand the movement
of nitrate, bromide, phenols, and other chemicals which may be present
in the return irrigation water.
The removal of silica from rocks by percolating ground water will
ultimately cause some reduction in land elevations.
Moberly (1963)
has made calculations which indicate rather high denudation rates on
Oahu due to the removal of material in solution, much of which is removed as dissolved silica.
Also, Stearns and Macdonald (1942, p. 150)
have described the karst-like topography on the island of Maui.
They
ascribe the "karst" development to rapid removal of silica in solution
through ground-water circulation.
Almost all silica analyses are expressed as parts per million or
milligrams per liter of Si02.
This custom was adopted before the exact
chemical form of dissolved silica was understood.
Even though it is
now known that most silica in natural water is in the form of dissolved
but nonionized silicic acid, H4Si04, (Krauskopf, 1956) the conventional
form of reporting silica as Si0 2 is retained in this report. To convert
ppm Si02 to ppm H4Si04, multiply ppm Si02 by 1.60. To convert ppm Si0 2
to ppm Si, multiply by 0.466.
SOURCES OF DATA
Various sources of complete water analyses are used in this report,
hence, a comment on their relative reliability is in order.
In general,
misleading water analyses are obtained in at least four different ways.
First, the actual sample may not be representative of the water that was
thought to have been sampled.
A stream can be sampled near a tributary
and inadequate mixing in the stream may mean that the water collected
was mostly from the tributary rather than the master stream.
a single well may yield water from several aquifers.
Similarly,
The proportion of
water yielded from each aquifer will be a complex function of time and
is hard to predict without a detailed study of the well.
sample
bottles.
Second, the
may be contaminated by unclean, leaky, or chemically reactive
The dissolution of silica from glass bottles is particularly
troublesome.
Sorption of trace constituents on surfaces of all types
of bottles could produce measurable errors.
Third, various chemical
3
reactions take place in the water after it is collected.
Unless treated
with a growth inhibitor, microbiological activity in the sample will
affect iron, silica, sulfate, and other constituents;
The hydrogen ion
concentration (pH) will be changed radically by variations in the amount
of C02 in solution and the microbiological activity during sample storage.
Fourth, and lastly, laboratory techniques may not be accurate.
Sampling for the reconnaissance-type analyses reported in Tables
I through 6 was done with careful attention to the problem of obtaining
a representative sample.
All streams were sampled far below tributaries
to minimize the problem of uneven mixing.
Possible contamination was
carefully avoided by using new polyethylene bottles and caps that were
thoroughly washed with distilled water and then vigorously rinsed three
times with the water that was to be sampled.
Excessive microbiological
activity was avoided by making all but the sodium and potassium analyses
within 48 hours of the time of collection.
The pH measurements were
made at the time of collection.
Although the reconnaissance-type analyses reported in Tables 4
through 6 are not accurate enough to use in many calculations of interest
to geochemists, they are generally within 10% of being balanced chemically
and can, therefore, be used in a semi-quantitative way.
Traditionally,
water chemists have avoided using reconnaissance-type analyses, but if
their level of accuracy is fully recognized, they can be used with
confidence.
Science and technology accept work of varying degrees of accuracy
for different purposes.
For example, all elevation determinations are
not made with first-order techniques.
For some purposes, barometeric
leveling only to the nearest 20 feet is of sufficient accuracy.
Con-
siderations of time and economics dictate that "second order" or even
"third order" chemical analyses should be used for many purposes.
The
only real problem is for researchers and technologists to keep their
conclusions concerning water chemistry in perspective with the accuracies
of the analytical techniques used.
Analyses given in Tables 4 through 6 were made with the aid of a
kit marketed commerically by the Hach Chemical Company of Ames, Iowa.
Limitations of this kit are largely those of small sample and reagent
TABLE l.
SAMPLE
NJMBER
f\W1E OF
STREAM
DATE OF
COLLECTION
DESCRIPTION OF LOCATION OF STREAMS AND OTHER SAMPLE COLLECTION DATA.
t-()UR OF
COLLECTION
MANOA
JAN. 14, 1967
0840
LOCATION OF STREAM
ESTIMATED
DISCHl\RGE
cfs
10
+:-
NEARBY LANDMARK
LATITUDE
LONGITUDE
21 0 18' 40"
157 0 48' 40"
0
0
SAFEWAY STORE
4
KANEALOLE
JAN. 14, 1967
1030
0.05
21
5
NWANU
JAN. 14, 1967
1120
2
21 0 21' 00"
157 0 49' 25"
NUUANU PALl DRIVE
6
r-ooLE
JAN. 14, 1967
1130
0.5
21 0 21' 05"
157 0 49' 35"
AT NUUANU PALl DRIVE
18' 50"
157
0
50' 00"
START OF ROUND TOP DRIVE
8
IWAWAO
JAN. 14, 1967
1300
0.03
21° 21' 40"
157
45' 40"
NEAR JUNCTION WITH
MAUNAWILI STREAM
9
KANEOHE
JAN. 14, 1967
1345
5
21 0 24' 40"
157 0 47' 40"
EAST OF KAMEHAMEHA
HIGHWAY
10
AHUIMANU
JAN. 14, 1967
1410
0.5
21° 26' 55"
157 6 50' 10"
AT HIGHWAY
11
UNNAMED
STREAM
JAN. 14, 1967
1420
0.7
21° 26' 45"
157° 50'
5"
AT HIGHWAY
12
KALUANUI
JAN. 14, 1967
1530
0.5
21° 35' 55"
157 0 54' 25"
UPPER EDGE OF CANE
FIELDS
13
PUNALUU
JAN. 14, 1967
1550
0.05
21 0 34' 55"
157 0 53'
PUNALW PARK
0
JAN. 14, 1967
1800
0.1
21
15
KANEOLOLE
JAN. 17, 1967
1130
0.04
21° 18' 50"
157 0 50' 00"
START OF ROUND TOP DRIVE
16
MAI'.OA
JAN. 17, 1967
1145
7
21 0 18' 40"
157 0 48' 40"
SAFEWAY STORE
157° 48' 40"
SAFEWAY STORE
MANOA
JAN. 18, 1967
0800
27
SMALL
UNf\W1ED
STREAM
JAN. 18, 1967
1410
34
MANOA
FEB. 10, 1967
0935
6
0.1
60
21
21
0
18' 40"
20' 20"
21° 18' 40"
157
0
47' 35"
AUENUE SCHOOL
PALOLO
23
157
5"
14
0
18' 30"
0
48' 10"
157° 48' 40"
MAI'.OA FALLS
SAFEWAY STORE
TABLE 2.
SAMPLE NUMBER
NATURE OF SURFACE
AND
GENERAL LOCAL! TY
DESCRIPTION OF SAMPLING SITES OF ARTIFICIAL RUNOFF.
LOCATION
APPROXI MA.TE
AREA WASHED
DATE
cm 2
SLIGHTLY WEATHERED BOULDER
IN MA.NOA VALLEY.
JAN. 14, 1967
"ROUND TOP CINDERS" IN ROADCUT
ON ROUND TOP DRIVE.
LATITUDIO
LONGITUDE
1200
21° 18' 45"
157 0 48' 40"
JAN. 14, 1967
450
21° 18' 55"
157° 49' 30"
ROCK AT PALl LOOKOUT.
JAN. 14, 1967
900
21° 22' 15"
157° 47' 45"
24
HIGHLY WEATHERED OUTCROP IN
BACK OF NEW HOUSING
DEVELOPMENT NEAR CHINESE
CEMETERY. REDDISH ZONE.
JAN. 18, 1967
900
21° 19' 30"
157 0 48' 10"
25
SAME AS 24, BUT RUNOFF FROM
GREY ZONE.
JAN. 18, 1967
900
21° 19' 30"
157 0 48' 10"
26
COLLUVIAL SOIL, SAME GENERAL
LOCATION AS 24.
JAN. 18, 1967
1200
21° 19' 35"
157 0 48' 10"
28
LARGE BOULDER IN STREAM BED
AT HEAD OF MA.NOA VALLEY.
JAN. 18, 1967
1000
21 0 20' 20"
157 0 48'
2
7
5"
V1
0'
TABLE 3.
DESCRIPTION OF SN1PLES USED FOR LEACHING TESTS.
SAMPLE
NUMBER
ORIGIN OF
SAMPLE
DATE OF
COLLECTION
DATE OF
LEACH
17
FRAGMENTS OF BASALT, 16 TO
32 r~ DIAMETER, FROM OLD
BORROW AREA AT PAll LOOKOUT.
JAN. 14, 1967
JAN. 18, 1967
18
SAME AS SAMPLE 17. RERUN ON
ON SAME SAMPLE WITHOUT PERIOD
OF DRYING.
JAN. 14, 1967
19
SAME AS SAMPLE 17.
RERUN WITHOUT PERIOD
OF DRYING.
20
VOLLt-1E OF
DISTILLED
WATER
ANTECEDENT
MJISTURE ON
SAMPLE
CONTACT TIME
MINUTES
260
150
DRY
60
JAN. 18, 1967
260
150
WET
60
JAN. 14, 1967
JAN. 18, 1967
260
ISO
WET
60
ROUND TOP CINDERS FROM
MAMAUE PLACE OFF ROUND TOP
DRIVE.
JAN. 18, 1967
JAN. 18, 1967
500
210
DRY
60
PLUS 60
MINUTES FOR
DECANTING
CLEAR WATER
21
FRESHLY BROKEN PIECES OF
BASALT, 16 TO 32 ~
DIAMETER, FROM OLD BORROW
AREA AT PAll LOOKOUT
(SAME AS In.
JAN. 14, 1967
JAN. 18, 1967
250
150
DRY
60
22
SAME AS SAMPLE 20.
JAN. 18, 1967
JAN. 18, 1967
500
150
WET
60
29
SAME AS SAMPLE 20.
JAN. 18, 1967
JAN. 19, 1967
500
160
WET
60
30
SAME AS SAMPLE 17.
JAN. "14, 1967
JAN. 19, 1967
260
150
MJIST
60
31
SAME AS SAMPLE 21,
JAN. 14, 1967
JAN. 19, 1967
250
150
MJIST
60
32
SAME AS SAMPLE 21.
JAN. 14, 1967
JAN. 19, 1967
250
150
WET
5
33
SAME AS SAMPLE 21.
JAN. 14, 1967
JAN. 19, 1967
250
150
WET
5
VOLLt-1E OF
SAMPLE
em 3
<i'il-~;iiil.~.L"li.~~fi~id~iRi=;.wpp."--
TABLE It.
SAMPLE I'01BER
pH
AT Tlr-t:
OF
COLLECTION
SPECIFIC
ELECTRICAL
C{)I'{)UCTI VITY
MICR()ot-()S AT
25°C
CHEMICAL ANALYSES OF STREJlJ'1 SAl"'PLES.
CONSTITUENTS OF Wb.TER GIVEN IN PPM
Si0 2
Ca++
Mg++
Na
+
K+
HCO' 3
Cl
.
DISCREPANCY IN
ANION-CATION BALANCE
C% OF LARGER SUM)
SO=-
8.35
192
18.8
13.6
9.3
1"
1.0
88
22
7
1.8 C-)
"
7.61
27"
21.2
17.6
13.6
13
2.9
13"
31
5
11.5 C-)
7.21
1"9
11.3
5.6
6.8
10
0.6
6
7.60
133
12.8
7.2
8.1
12
0.7
""
8
7.00
135
22.0
6."
11. 7
1"
9
7.52
167
18.9
8.8
9.8
15
10
7.10
163
18.0
13.6
9.8
1"
11
6.78
179
8.6
15.2
".9
12
7.12
68
6.8
".0
2."
13
7.01
2300
25.5
8".8
8".0
227
22.2
12.8
11.5
222
2".5
17.6
187
19.2
171
25.6C?)
1"
15
16
23
27
3"
---
---
17
6
8.5 C-)
"9
22
6
0.6 C-)
1.0
68
25
73
2"
"
0.5 C+)
1.0
0.9
66
26
5
3.0 C-)
8
6.2 C+)
1."
61
28
10.5
8.0 C-)
0.5
17
19
3
12.5 C-)
328
10.2
89
850
110
7.5 C-)
21
1.2
88
30
9
1.6 C+)
12.2
26
2.8
1""
30
5
6.9 C-)
12.8
9.8
13
0.8
88
21
6
6.0 C-)
12.8
9.8
13
0.8
88
22
6
7.3 C-)
32
12
"1
12
"
15
8.2
76.5
15.3
6."
2.9
9.6
0.6
85
10.1
6.8
3.7
7.0
0.8
5
9.0 C+)
12.6 C-)
"-.l
CONSTITUENTS OF WATER GIVEN IN PPM
SAMPLE NlJiIBER
SPECIFIC ELECTRICAL
COf'i)UCT1VITY
MICROMHOS AT 25°C
SiOz
TOTAL HARDNESS
AS CaC03
Na+
K+
HCO-3
2
21.&
2.0
10
3.0
1.9
330
Cl -
SO~4
3
1080
1.7
47&
48
5.0
---
7
142
0.9
20
27
1.0
10
42
7
2
7.5
24
14.5
2.0
8
2.&
0.2
5
5
25
15.5
1.7
&
2.&
0.2
7
10
1.5
2&
39.5
2.&
8
4.8
1.1
5
10
4
28
&.&
0.4
--
1.&
0.2
10
&
(Xl
9
volumes that are not measured with sufficient accuracy.
Nevertheless,
use of abundant quantities of distilled water for washing glassware and
the substitution of larger volumes measured from more accurate pipets
allows a moderately acceptable analysis to be made.
Sodium and potassium
determinations were made with a Baird-Atomic flame spectrophotometer.
Sodium values are probably accurate to better ±O.l ppm and potassium
to better than ±0.2 ppm.
Determinations of pH were made by colormetric
methods using a portable photometer.
Comparison with an electric pH
meter suggests that accuracy is about ±O.l of a pH unit and precision
is about ±O.OS of a pH unit, provided the water temperature is relatively
constant during testing of duplicate samples.
Specific electrical con-
ductivity was standardized with KCl solutions and is probably accurate
to about ±S% of the stated value.
Analyses by the Board of Water Supply of the City and County of
Honolulu were made in their well-equipped laboratory by trained analytical chemists.
The only limitation of the analyses is in the determina-
tions of pH which have been done in the laboratory and hence do not
represent the actual pH of the water in the field.
Analyses by the
Water Resources Research Center at the University of Hawaii were also
made in a modern analytical laboratory by professional chemists.
The pH
reported is the field pH.
SURFACE RUNOFF
Little is known
of the chemistry of surface runoff before it
reaches stream channels or infiltrates into the subsurface.
Highly
variable local conditions make a lengthy research project necessary in
order to obtain a complete treatment of this topic.
Nevertheless, a
few samples of artificial runoff were collected from seven different
surfaces (Table 2) for a first approximation of the amount of silica in
runoff waters.
From 300 to 500 ml of distilled water that had been
passed through a deionization resin were sprayed from a polyethylene
bottle onto about 1000 cm 2 of rock or soil surface.
The volume of runoff
collected varied from about 100 ml to 200 ml, the exact volume depended
on the absorption of the water by the soil or rock.
The contact time
between water and rock surfaces varied from about 30 seconds for dense
rock to 2 minutes for soils and highly weathered rock.
10
Three distinct chemical types of runoff were collected.
The most
mineralized water (Sample 3, Table 5) was from a roadcut in basaltic
cinders.
A slight overhang protected the part washed by distilled water
from antecedent rains.
The washed surface had a discontinuous coating
of a light-colored residue that appeared to be formed by evaporation of
soil moisture.
The residue was easily dissolved and undoubtedly accounts
for the high dissolved-solids content of the artificial runoff.
The next highest concentration of dissolved solids came from a
bare outcrop of basalt in an old borrow area at the Pali (Sample 7,
Table 5).
face.
Residues left by evaporation were not evident on the rock sur-
The porosity and permeability of the rock appear to be too low
to permit significant post-precipitation movement of water to the rock
surface during periods of drying.
The relatively large amounts of
sodium and chloride in the analysis of the runoff suggest the presence
of sea-spray fallout.
Strong winds that are common in the area could
transport significant amounts of dry fallout to the Pali.
contained
10- 11
g/cm 3
If the air
(a conservative figure judging by Woodcock, 1953)
of salt and if 50% of the salt nuclei were captured from a 1.0-cm
layer of air traveling at 400 km/day and deposited on a 1000-cm 2 surface,
200 mg of NaCl would accumulate in one day, or more than enough to account
for the observed salinity of the artificial runoff.
The moderately low
concentration of silica in the artificial runoff suggests that continual
washing by rain and mist has removed some of the relatively mobile silica
present at the rock surface.
The lowest concentration of dissolved solids was found in runoff
from a large boulder in the bed of an ephemeral stream (Sample 28,
Table 5).
A thick canopy of vegetation protected the boulder from dry
fallout.
The other 4 analyses given in Table 5 are considered to be more
indicative of normal runoff from rock and soil surfaces.
In general,
the concentration of total dissolved solids is probably between 10 and
40 ppm and the dissolved silica between 1 and 3 ppm.
Owing to the uneven
influence of evaporation residues and dry fallout, a direct relationship
between silica and total solids in the water should not be expected.
11
STREAM WATER
Analyses of 16 samples of water from 12 streams on Oahu were made
for the purpose of this study (Tables 1 and 4).
Other data used for
this report were from 7 analyses by Bryson (1953) from Oahu; 43 analyses
by Kunishi (1956) from Oahu, Kauai, Hawaii, and Maui; and 8 analyses
from Oahu that were made as a part of a current investigation by the
Water Resources Research Center at the University of Hawaii.
Selected
analyses of stream water froIn these sources as well as other investigators
are given in the Appendix.
Most of the stream water is a calcium-magnesium-sodium-bicarbonate
water with about 15 ppm of Si0 2 . If all the chloride in the stream
water is assumed to be from recycled ocean salts carried by rain and dry
fallout (Visher and Mink, 1964), a comparison between "median" stream
water and sea water diluted to the same chloride value (Table 7) will
give some indication of the rock components being removed in solution
by streams on the Hawaiian Islands.
Calcium, magnesium, and silica
appear to be the rock components removed most readily in solution by
stream water.
Bicarbonate given in the river analysis is derived mostly
from decaying vegetation in the soil and is recycled ultimately as C02
gas through the atmosphere.
TABLE 7.
CONSTITUENTS
MEDIAN COMPOSITION OF STREAM WATER FROM THE HAWAIIAN ISLANDS.
STREAM WATER
DILUTED SEA WATER
CONS TI TUENTS IN PPM
Sia z
15
0.0
Ca
10
0.&
Mg
9
1.9
Na
13
14.4
K
Cl
0.8
0.5
&0
0.2
8
3.&
2&
2&.0
Most of the analyses used to calculate "median" stream composition
were from samples obtained during low-flow conditions.
A much larger
number of samples is needed, particularly of flood flows, before quantitative conclusions can be reached concerning the precise nature of
solute removal. For example, data in Table 7 suggest that the land is
12
actually ga1n1ng sodium, perhaps through ion exchange while at the same
time losing large amounts of the other two abundant cations, namely,
calcium and magnesium.
To state this as a conclusion, however, would be
premature inasmuch as the bulk of the water is discharged during brief
periods of storm runoff and the chemistry of storm runoff is virtually
unknown.
Silica concentrations of stream water in the Hawaiian Islands
have a total range
fro~
about 3 ppm to more than 30 ppm.
More than 50%
of the analyses studied, however, have values between 8 and 20 ppm.
The median of 70 analyses is 15 ppm, and the mode is 12 ppm.
The pre-
ceding values are from samples that were taken mostly during low to
medium discharge conditions in the stream.
Flood flows will dilute the
water so that most dissolved constituents will be present in only a
fraction of their low-flow concentrations.
Silica is an exception to
this generalization (Davis, 1964); consequently, the average silica concentration of stream water based on total water discharged (rather than
on sampling frequency, as are the above values) should not be much lower
than, perhaps, 10 ppm.
The reason
why flood conditions have only a minor effect on dis-
solved silica concentrations in some streams is as yet unknown.
In
addition to the possibilities discussed by Davis (1964), the presence
of opaline phytoliths (Riquier, 1960) and a soluble layer of silicic
acid on mineral grains (Gifford and Frugo1i, 1964; McKeague and Cline,
1963) may provide a source of pure Si0 2 that would not involve an increase
in other soluble constituents.
Gill (1967), however, has summarized
evidence to indicate that in certain environments phytoliths are more
stable than their opaline composition would suggest.
The explanation
presently favored visualizes moderately high silica in the stream during
times when low flow is sustained by ground water.
During heavy rains,
surface runoff and interflow through the soil horizon will come in contact with the more soluble forms of silica and, hence, will acquire
silica concentrations almost as high as in ground water.
Therefore, the
silica content does not fluctuate as widely as does the other dissolved
constituents.
One difficulty in the application of this theory to con-
ditions on Oahu is the fact that soils at the surface in the drainage
areas of many streams in Oahu are depleted in silica.
Thus, one might
expect a somewhat larger fluctuation of silica in Oahu streams than has
13
been observed in most mainland streams.
Limited data from Manoa Stream
(Table 4, Samples 1, 16, 23, and 34) support this possibility.
WATER FROM TUNNELS
The median composition of ground water collected from high-level
tunnels in the Koolau Range of Oahu is shown in Table 8.
The composition
of sea water diluted to 16 ppm Cl, which is the chloride concentration
of the tunnel water, is also shown for comparison.
An independent compilation of 20 silica analyses from high-level
tunnels in the Waianae Range as well as the Koolau Range show a median
of 23 ppm Si02 with a range from 5 to 45 ppm.
The somewhat higher median
value than that given in Table 8 is probably a reflection of slower
water movement and less antecedent leaching in the Waianae Range which
is an area of much lower rainfall than the Koolau Range.
TABLE 8.
MEDIAN COMPOSITION OF HIGH-LEVEL TUNNEL WATER, KOOLAU RANGE, OAHU.l
CONS TITUENTS
TUNNEL WATER
DILUTED SEA WATER
CONSTI TUENTS IN PPM
5i0 2
0.0
15
Ca
7.2
0.3
Mg
4.6
1.1
Na
K
HC03
5°4
Cl
N0 3
8.8
11
1.4
0.3
50
0.1
3.5
2.2
16
16
0.55
0.0
lDATA FROM VISHER AND MINK, 1964.
The striking similarity between stream water (Table 7) and tunnel
water (Table 8) is most likely owing to high-level dike water which
sustains both tunnel flow and stream flow.
The most significant differ-
ence between stream flow and tunnel water appears to be the larger
amount of chloride in the strewn water.
Dry fallout and contamination
from human sources probably account for the added chloride in the streams.
Sodium that is probably introduced into the streams with the chloride
is partly exchanged for calcium and magnesium ions which are available
on clay and organic particles in the stream channels.
Some exchange
14
must also take place at the soil surface before runoff reaches the stream.
The median concentration of silica in tunnel
water from streams.
water is the same as
This fact suggests that little 'dissolution or pre-
cipitation of silica takes place in the stream.
Activity of algae and
diatoms as well as the establishing of new chemical equilibrium with
clay minerals in the stream channel could, nevertheless, remove silica
from the stream water.
The streams flow rapidly to the sea, however, so
little time is available for new conditions of chemical equilibrium to
be approached.
BASAL GROUND WATER
The term "basal ground water" has been used for many years in' the
Hawaiian Islands to designate ground water that is essentially in free
contact with both the atmosphere and sea water.
In its most elementary
form, basal ground water is unconfined water near sea level in a highly
permeable basalt.
Coastal sediments, ash beds, buried soils, and the
nonisotropic nature of the basalt will produce local semi-confining
conditions as well as complicated ground-water flow patterns, precluding
a simple concept of unconfined water in most natural situations.
Analyses from 30 wells in basaltic aquifers were used to determine
the median composition of basal ground water (Table 9).
All but 5 of
the analyses are from wells on Oahu, and of those from Oahu, most are
from the southern part of the island.
Despite uneven sampling, the
chemistry of all well waters is quite similar, and therefore can be
considered representative for all of the Hawaiian Islands.
TABLE 9.
CONSTITUENTS
MEDIAN COMPOSITION OF BASAL GROUND WATER.
BASAL WATER
DILUTED SEA WATER
CONST! TUENTS IN PPM
Si0 2
44
0.0
Ca
10
1.6
Mg
10
5.1
Na
45
42.2
K
Analyses of
2.5
1.5
IIC03
74
0.6
S04
14
10.2
Cl
76
76.0
15
waters that were partly return irrigation water were included in the
determination of median values for Table 9.
Silica in basal ground water has a median value.of 44 ppm.
range of values used for Table 9 is from 30 to 72 ppm.
The
In a more exten-
sive summary of silica determinations prepared by Mr. Y. F. Lee (personal
communication, 1966), the range was from 18 to 88 ppm with a median of
45 ppm.
Visher and Mink (1964) concluded that silica concentrations
above 35 ppm were suggestive of return irrigation water.
The explanation
offered was that:
The latosols have a kaolinite base and represent an intermediate stage of laterization that results from relatively
low rainfall (60 inches per year or less). However, the
application of irrigation water on these soils is equivalent
to about 120 inches of rain per year, which when added to
the normal rainfall gives a total of about 150 inches per
year • . . . The application of large quantities of irrigation
water to fields in normally dry areas simulates high rainfall conditions, which can be expected to accelerate the
laterization process. The silica is mobilized during laterization and moves from the soil to the basal water body.
(Visher and Mink, 1964, p. Ill)
Although silica leaching may be accelerated by irrigation and
other agricultural practices, present information appears to argue against
most of the silica being derived from accelerated laterization.
Theoret-
ical work by Garrels and others (summarized by Garrels and Christ, 1965,
p. 352-365) would suggest that water in equilibrium with soils containing
clays in a tropical environment would not exceed 30 ppm Si0 2 . Leaching
tests of Hawaiian soils by Professor R. L. Fox and other soil scientists
at the University of Hawaii strongly suggest that waters percolating
through Reddish Prairie soils developed in areas of low rainfall should
not contain more than 20 ppm Si02 (Fox, et
aZ.~
1967).
The actual maxi-
mum concentration of soil-leach water after 48 hours was 14 ppm Si0 2 .
Inasmuch as soils are very permeable and contact with irrigation water
is of relatively short duration, 20 ppm is considered to be an upper
limit of possible concentrations of silica that can be ascribed to dissolution of natural soil materials.
For comparison, the maximum silica
concentrations of leach water from aluminous Humic Ferruginous Latosol
was slightly less than 2.0 ppm after 48 hours contact time.
Similar
concentrations of from 1.2 to 4.1 ppm were found in ground water perched
within deeply weathered basalt on Kauai (Patterson and Roberson, 1961).
16
If the silica in excess of 35 ppm does not come from a normal
laterization process, it must then come from the dissolution of minerals in relatively fresh basaltic aquifers or from certain agricultural practices.
A possible interpretation of higher silica content
in waters is that they are produced by recent leaching of rocks in the
drier irrigated areas as well as the slower movement of ground water
in the lowlands near the ocean.
The slower moving water would allow
a longer time for dissolution of the silica-rich minerals and finegrained groundmass of the basalt.
Leaching tests made by Bryson (1953)
suggest that the time needed for water to reach chemical equilibrium
with the rocks might be a factor in controlling the silica concentrations
of ground water.
His leaching tests totaled between 350 and 450 hours
and used unweathered basalt and basaltic cinders.
One test started
with water having a concentration of 40 ppm Si02'
This sample increased
to only 41 ppm
Si02 at the end of the test.
Another water sample
increased from 37.5 ppm to 40.5 ppm Si0 2 .
Some Si02 in excess of 35 ppm may arise from agricultural practices.
Addition of phosphates will mobilize silica (Fox, et al.).
Burning sugar cane leaves and other agricultural wastes will leave an
ash with significant amounts of soluble silica.
Also, slag, calcium
metasilicate, and other sources of soluble silica are added to some
soils.
Reduction of the soil pH could also release sorbed silicic acid
on soil particles (Beckwith and Reeve, 1964).
Data gathered in this
study are not sufficient to evaluate the various sources of silica
related to agricultural practices.
WATER FROM LEACH TESTS
A total of 11 short-term leaching tests were made of samples of
basalt (Tables 3 and 6) for the purposes of the present report.
The
tests were made in order to obtain a rough approximation of the amount
of silica that might go into solution during the infiltration of rainwater into the subsurface.
Only distilled water that had been passed
through a deionizing column was used for the tests.
Although the experiments were not elaborate, the following conclusions appear justified.
Significant amounts of silica can be leached
rapidly from rock that has been exposed to rain for several years (Sample 17, Table 6).
A thin film of moisture on the rock for a period of
17
24 hours will aid the dissolution of silica during the next leaching
cycle (Sample 30, Table 6).
The same basalt when it is freshly broken
will yield more silica than old gravel exposed to prior natural leaching
by rain (compare Samples 17 and 21, Table 6).
Surface area exposed to
water is undoubtedly the most critical factor determining the rate of
silica dissolution of unweathered basaltic rocks (compare the effects
of cinders in Sample 20 with large pieces of broken rock in Sample 17,
Table 6).
When the silica concentrations given in Table 6 as well as the
results of leaching tests by Bryson (1953) are considered, it is not
unreasonable to assume that downward percolating rain water may arrive
at the zone of saturation in the Koolau Range with silica concentrations
of between 5 and 15 ppm.
Further residence time in the dike compartments
could easily allow for dissolution of more silica and account for the
concentrations observed in tunnel water.
RATES OF SILICA REMOVAL
The chemical weathering of basaltic rocks in the Hawaiian Islands
has been described by Bates (1962) as largely a process of desilication.
This fact is shown clearly by the data in this report.
The analyses in
Table 4 and those in the Appendix, as well as the average water compositions given in Tables 7 through 9, demonstrate that silica is one of
the major constituents of all waters moving through or over basaltic
rocks in the Hawaiian Islands.
Cyclic dissolved solids derived from
the ocean do not contain significant amounts of silica.
The only other
possible sources of soluble silica besides basaltic rocks are nucleation
particles in rainfall and solid fallout such as the phytolith-rich dust
described by Folger and others (1967) from the central part of the
Atlantic Ocean.
Silica is virtually absent from most Hawaiian rain
water (Analyses 18 and 19, Appendix, and Fox, et
aZ.~
1967, p. 778).
Even the proposed aeolian quantity in Hawaiian soils (Rex, et aZ.,1969)
must contribute only minor amounts of silica to the ground water since
the quantity persists and numbers accumulated in the soil surface layers.
The conclusion is, therefore, that silica is being removed from the
local volcanic rocks and associated soils at a rapid rate.
Further chemical analyses are needed before reliable calculations
18
can be made of rates of silica removal from any part of Oahu.
Neverthe-
less, data given in this report and summarized in Figure 1 allow
preliminary estimates to be made.
The greatest uncertainty in the surface-
water data is in the silica content of storm runoff.
Moderately high
values are used for calculations (Table 10) on the assumption that silica
is dissolved rather rapidly from soil and rocks in contact with runoff.
The possibility that surface runoff may come only in contact with lowsilica soils, however, suggests that storm runoff contains less silica
that have been assumed.
Uncertainties concerning silica in ground water
are even greater than those of surface water.
Silica values of ground
water in Table 10 were taken from water analyses of basal ground water
near watershed areas.
Again, these values may be too large in view of
the lower silica concentrations in most high-level dike water (Table 8).
SILICA REMJVED FROM SELECTED WATERSHEDS. l
TABLE 10.
WATERSHED
SURFACE
RUNOFF
(em)
LOCATION
GROUNDWATER
"RUNOFF"2
(em)
SILICA IN
SURFACE
RUNOFF
(ppm)
SILICA IN
GROUND
WATER
(ppm)
(mg/em 2/year)
SiLICA
REMJVAL
EAST t-'ANOA
OAHU
173
135
14
35
7.13
WAIOMtIO
(PALOLO)
OAHU
62
131
16
35
5.58
PUNALUU
OAHU
332
185
10 3
30
8.87
SOUTH FORK
PIT RIVER
CALIFORNIA
93
0
35
3.25
PIT RIVER
AT t-'ONTGOMERY
CALIFORNIA
38
0
30
1.15
UMC>.TI LLA
RIVER
OREGON
16.3
0
31
0.51
NEVARI
RIVER
VENEZUELA
98
0
9
0.88
lRUNOFF DATA FOR OAHU SUPPLIED BY MR. S. P. BOWLES, BOARD OF WATER SUPPLY, CITY AND COUNTY OF
HONOLULU
lGROUND-WATER RUNOFF WAS CALCULATED BY TAKING THE TOTAL RAINFALL AND SUBTRACTING SURFACE RUNOFF
AND AN ASSUMED EVAPOTRANSPIRATION. THE EVAPOTRANSPIRATION VALUES ASSUMED WERE EAST MC>.NOA, 64
em/yr.; WAIOMtIO, 73.5 em/yr.; AND PUNALUU, 61 em/yr. THESE VALUES ARE APPROXIMC>.TELY THOSE SUGGESTED BY PROFESSOR EKERN (PERSONAL COMMUNICATION). GROUND-WATER DISCHARGE FROM LARGE BASINS IN
CALIFORNIA, OREGON, AND VENEZUELA IS CONSIDERED TO BE NEGLIGIBLE.
3SILICA VALUE OF PUNALUU STREAM GIVEN IN TABLE 4 IS NOT REPRESENTATIVE OF SURFACE RUNOFF INASMUCH
AS IT WAS COLLECTED AT THE SHOR~LINE AND IS INFLUENCED BY THE DISCHARGE OF BRACKISH BASAL WATER.
Comparative data for four watersheds outside of Hawaii are given
also in Table 10.
Chemical and runoff values for watersheds underlain
largely by basalt in continental United States are from publications of
the U. S. Geological Survey.
Runoff for Rfo Nevarf is from the Anuario
RAIN
T
fiJJJ-..
WATER TABLE
[]]]-
~
/
FRESH WATER
/
mn--
-
/'
",,/
--------------SEA
WATER
t-'
<.0
FIGURE 1.
~1::.::~:
APPROXIMATE CONCENTRATIONS OF SILICA IN WATERS OF THE HAWAIIAN ISLANDS.
",:,.;,..:~,,:~¢'i:;,.~ :;~~:8:jfJ~;'.z.E',,'~!~J~"'~~~~~;;;O::-~
•.L-
20
Hidrometrico of the Obras Publicas, Venezuela and chemical analyses are
from unpublished data of the Obras Sanitarias, Venezuela.
Table 10 together with data published earlier (Davis, 1964, p. 886887) show that removal rates of silica are much larger in the higher
parts of the Koolau Range than any other area in the United States.
At
least five possible variables may account for the larger rates in Hawaii.
These are temperature, vegetation, relief, rock types, and total runoff.
Figure 2 suggests that some of these factors are more important than
others.
The fact that data from watersheds in basalt are roughly par-
allel with the trend line from other areas would seem to indicate that
ground-water discharge plus surface runoff, or "total runoff," is a very
important factor.
The additional fact that the basalt trend line is
offset to the right of the general trend line would suggest that rock
type is also an important factor.
The Rio Nevari drains a hot tropical
region underlaid by sedimentary rocks, mostly shale and sandstone.
Al-
though tropical forests recycle large quantities of silica, the fact that
the Nevari data fallon the average trend line for the continental United
States suggests, further, that temperature and vegetation are not of primary
importance (Lovering, 1958).
Inasmuch as all watersheds listed in Table
10 have a moderate to high relief, this factor could not be evaluated.
According to work by Gibbs (1967) in the Amazon Basin, relief should be
important in determining the rate of removal of material in solution.
The rates of solution and removal of silica in Hawaii exceed the
rates of solution and removal of calcium carbonate from many regions
containing karst topography.
For example, Hendrickson and Krieger (1964)
calculated rates of about 120 tons m2 jyr of total dissolved solids for
a limestone region in Kentucky.
About 70% of the 120 tons is CaC03
which, when converted to units used in this report, would be a removal
rate of 1.5 mg CaC0 3jcm 2 jyr.
One might question, if silica removal
in Hawaii is more rapid than calcite removal in karst areas, why are
there not more karst-like features similar to those described by Stearns
and Macdonald (1942) on Maui?
The answer probably lies in the fact
that removal of silica alone does not necessarily mean a reduction in
the volume of the rock.
Various products of weathering are hydrated
and porous so that their volume may be equal to or even greater than the·
original volume of the solid rock.
The silica removal during weathering,
therefore, would soften the rock and thereby accelerate stream erosion
21
I.
2.
3.
4,
500
5.
6.
7.
UMATILLA R., OREGON
PIT R., MONTGOMERY, CAL I F.
NEVARI R. t VENEZUELA
SOUTH FORK PIT R., CALIF.
WAIOMAO STR., HAWAII
EAST MANOA STR., HAWAII
PUNALUU VALLEY, HAWAII
~
,~
~
"~
<:;)~
u
z:::)
100
@
~q;.
,
~~
,,
.$>
t-
"
/
,'®
,~
,~e,
,'q,
Q:-~
50
,,
,@
,~
V
...J
<X
t-
,,
O~
a::
O
~;'
,
,,
0)(0
a::
>-
0
,,
~
200
lL
lL
<V
,'cJ.
~
,~~~
® , ' v"
,~
,~~
,~
/~
'~v
20
<D
,,
,'td
,
'O~
" q,
10
0.2
0.5
1.0
2.0
5.0
SILICA REMOVED (MG/CMa/YR)
FIGURE 2.
RELATIONSHIP BETWEEN TOTAL RUNOFF AND RATE OF REMOVAL
OF SILICA FOR VARIOUS WATERSHEDS. TREND LINE TO THE
LEFT OF DATA POINTS IS FROM DAVIS (1964).
10.0
22
and mass wasting at the land surface but would not normally produce subsurface voids that would give rise to a karst topography.
CONCLUSIONS
The following are the most important conclusions resulting from
this study:
1.
Runoff from rains will acquire 1 to 3 ppm Si0 2 during the
first few minutes after the rain comes in contact with soil
or rocks.
2.
Despite the initial rapid uptake of silica, subsurface water
will continue to dissolve silica during most of the distance
that it travels before being discharged at the coast.
3.
Surface water has roughly the same silica content as high-level
tunnel water except possibly during periods of runoff from
intense rains.
4.
High silica content of ground water in areas of irrigation
cannot be attributed to leaching of semi-arid soils.
An alter-
native explanation, that of leaching of underlying unweathered
basalt, appears to be more likely.
5.
Silica removal from small watersheds high in the Koolau Range
is much more rapid than in any other area in the United States.
Rates of more than 8 mg Si0 2 cm 2 jyr are likely in areas of
highest rainfall.
Although the above rate is very high, it
is no higher than might be predicted by projecting relationships
between runoff and silica removal derived from much colder
regions in the United States.
6.
The most important factors controlling rates of silica removal
are rock types in contact with water and the amount of water
available for chemical leaching of silica.
Evidence is entirely
lacking that a tropical environment is a prerequisite for the
rapid mobilization of silica in the hydrosphere.
7.
Data in this report lend credence to the suggestion of Stearns
and Macdonald that karst-like features on Maui were caused by
the dissolution of volcanic rocks by infiltrating rain water.
23
ACKNOWLEDGEMENTS
Most of the work reported here was completed in the Water Resources
Research Center of the University of Hawaii during the winter of 1966-67.
The sodium and potassium determinations were made at Stanford University with the assistance of Maurice Veatch.
Personnel of the Board of
Water Supply of the City and County of Honolulu made available much of
the data used in the report; Y. F. Lee, chemist, and S. P. Bowles, geologist, were particularly helpful.
The results of recent water analyses
made at the Water Resources Research Center at the University of Hawaii
have also been used.
H. C. Whitehead.
These analyses were made under the direction of
Comparative data from Venezuela were supplied by the
chief chemist of the Barcelona Water Works.
Venezuelan analyses were
made by the Instituto Nacional de Obras Sanitarias in Caracas.
Finally,
Professors Stephen Lau, Paul Ekern, and Reginald Young of the University
of Hawaii gave liberally of their time and helped me in countless ways.
To the above individuals and organizations, I am very grateful.
24
BIBLIOGRAPHY
Bates, T. F. 1962. Halloysite and gibbsite formation. in Hawaii. IN
Clays and clay minerals. Earl Ingerson, ed. Pergamon Press.
London. p. 315-328.
Beckwith, R. S. and R. Reeve. 1964. Studies on soluble silica in soils.
II: the release of monosilicic acid from soils. Australian
Journal of Soil Research. Vol. 2. p. 33-45.
BrY~0~,
L. T. 1953. Watershed surface waters and rock leaching tests.
Board of Water Supply, City and County of Honolulu. Unpublished
report. 23 p. plus 26 tables and 5 figures.
Corwin, G., L. D. Bonham, M. J. Terman and G. W. Viele. 1957. Military
geology of Pagan~ Mariana Islands. U.S. Army Engineers, Engineering Intelligence Dossier (open file). 259 p.
Davis, D. A. 1958. Military geology of Saipan~ Mariana Islands~ Vol.
II: Water Resources. U.S. Army Engineers, Engineering Intelligence
Dossier (open file). 96 p.
Davis, S. N. 1964. Silica in streams and ground water.
Journal of Science. Vol. 262. p. 870-891.
Folger, D. W., L. H. Burckle and B. C. Heezen.
in a North Atlantic dust fall. Science.
American
1967. Opal phytoliths
Vol. 155. p. 1243-1244.
Fox, R. L., J. A. Silva, O. R. Younge, D. L. Plucknett and G. D. Sherman.
1967. Soil and plant silicon and silicate response by sugar cane.
Soil Sci. Soc. Am. Proc. Vol. 31. p. 775-779.
Garrels, R. M.
Science.
1965. Silica: Role in buffering of natural waters.
Vol. 148. p. 69.
Garrels, R. M. and C. L. Christ. 1965. Solutions~
libria. New York. Harper and Row. 450 p.
minerals~
and equi-
Gibbs, R. J. 1967. The geochemistry of the Amazon River system. Part
I: The factors that control the salinity and the composition and
concentration of the suspended solids. Geol. Soc. Am. Bull.
Vol. 78. p. 1203-1232.
Gifford, R. O. and D. M. Furgoli. 1964.
Science. Vol. 145. p. 386-388.
Gill, E. D. 1967.
p. 810.
Silica source in
Stability of biogenetic opal.
Science.
soi~
solutions.
Vol.
1~8.
Hendrickson, G. E. and R. A. Drieger. 1964. Geochemistry of natural
waters of the Blue Grass Region~ Kentucky. U.S. Geological Survey
Water-Supply Paper 1700. 135 p.
Jones, B. F., S. L. Rettig and H. P. Eugster. 1967.
brines. Science. Vol. 158. p. 1310-1314.
Silica in alkali
25
Krauskopf, K. B. 1956. Dissolution and precipitation of silica at low
temperatures. Geochim. et Cosmochim. Acta. Vol. 10. p. 1-26.
Kunishi, H. M. 1956. Mineral analyses of Hawaiian surface and seepage
waters. Dept. of Chemistry, University of Hawaii. M. S. thesis
No. 215. Unpublished. 34 p.
Lovering, T. S.
Vol. 128.
1958. Accumlator plants and rock weathering.
p. 416-417.
Science.
McKeague, J. A. and M. G. Cline. 1963. Silica in soils. IN Advances
in Agronomy. A. G. Norman, ed. Academic Press. New York. Vol. 15.
15. p. 339-396.
Moberly, Ralph, Jr. 1963. Rate of denudation in Hawaii.
Vol. 71. p. 371-375.
Patterson, S. H. and C. E. Roberson.
eastern part of Kauai~ Hawaii.
424-C. p. 195-198.
Jour. Geology.
1961. Weathered basalt in the
U.S. Geological Survey Prof. Paper
Rex, R. W., J. K. Syers, M. L. Jackson, and R. N. Clayton. 1969. Eolian
origin of quartz in soils of Hawaiian Islands and in Pacific
pelagic sediments. Science. Vol. 163. p. 277-279.
Riquier, J. 1960. Les phytolithes de certains sols tropicaux et des
podzols. Transactions of the 7th International Congress of Soil
Science. Madison, Wisconsin. Vol. 4, Commision 5. p. 425-431."
Stearns, H. T. and G. A. Macdonald. 1942. Geology and ground water
res urces of the Island of Maui~ Hawaii. Terr. Hawaii Div. Hydrography. Bull. 7. 344 p.
Valenciano, S. and K. J. Takasaki. 1959. Military geology of Truk Islands~ Carolina Islands.
Water Resources Supplement. U.S. Army
Engineers, Engineering Intelligence Dossier (open file). 81 p.
Visher, F. N. and J. F. Mink. 1964. Ground-water resources in southern
Oahu~ Hawaii.
U.S. Geological Survey Water-Supply Paper 1778.
133 p.
Ward, P. E. and J. W. Brookhart. 1962. Military geology of Guam~ Mariana Islands. U.S. Army Engineers, Engineering Intelligence
Dossier (open file). 182 p.
Woodcock, A. H. 1953. Salt nuclei in marine air as a function of
altitude and wind force. Jour. Meteorology. Vol. 10. p. 362-371.
APPENDIX:
SELECTED ANALYSES OF WATERS FROM
VARIOUS PACIFIC ISLANDS AND VENEZUELA
29
ANALYSIS
NU'1BER
DESCRIPTION OF
SAMPLE
SPECIFIC
ELECTRICAL
CONDUCTANCE
MICR<l-1HQS
AT 25°C
DISSOLVED CONSTITUENTS OF WATER IN PARTS PER MILLION
SiO~
Ca
Mg
Na
K
HC0 3
SO~
Cl
F
ANALYTICAL
LABORATORY
N0 3
NUUANU STREAM
WATER-OAHU
FR<l-1 BASALT.
(BRYSON, 1952)
117
9.3
4 ..~
4.5
12.5
0.4
33.0
6.1
16.5
0.4
BOARD WATER
SUPPLY,
HONOLULU
(1952)
LEACH WATER,
NWANU
STREAM WATER
AS INFLUENT,
ROCK IS
CRUSHED BASALT.
(BRYSON, 1952)
197
29.0
8.9
8.7
16.7
1.3
73.0
7.2
20.0
0.6
DO.
3
KAIMUKI WELL,
OAHU. BASALT
AQUIFER.
382
36
7.4
9.9
50.7
2.4
73.0
12.3
69.5
0.05
1.7
00.
(1961)
4
WAIANAE TlffiEL
OAHU. BASALT
AQUIFER. DIKE
WATER, WAIANAE
RAI'l;E.
208
36
11. 7
5.0
18.4
3.9
72.0
7.8
18
0.2
2.0
00.
(962)
5
WELL,
BASALT
AQUIFER.
235
30
10.3
6.5
22.1
1.2
55
4.9
36
0.05
0.9
00.
(962)
6
WAHIAWA WELL,
OAHU. BASALT
AQUIFER.
194
71
6.7
8.4
17.7
1.4
63
6.4
21
0.15
3.1
00.
(962)
7
KALIHI WELL,
OAHU. BASALT
AQUIFER.
351
36
35.7
2.5
68.5
9.8
63.5
1.8
00.
(1963)
8
HAIKU TlfflEL,
OAHU. BASALT
AQUIFER.
121
21
6.2
3.9
10.8
0.8
39.5
2.5
14.5
0.3
00.
(963)
9
WAIMANALO
TlfflEL, *4,
OAHU. BASALT
AQUIFER.
159
26
8.5
5.1
13.6
1.1
53.5
2.9
18
0.5
00.
(1963)
10
KAHALW TlfflEL,
OAHU. BASALT
AQUIFER.
128
23
7.2
4.3
10.8
0.9
44
2.4
15
0.3
00.
(1963)
11
WILDER WELL,
OAHU. BASALT
AQUIFER.
378
34
6.0
8.0
52.3
5.3
81.5
9.4
63.0
0.05
2.4
00.
(965)
12
K\.XIIIA WELL,
OAHU. BASALT
AQUIFER.
597
73
13.5
15.3
79.8
3.4
98
0.25
10.7
00.
(965)
13
BERETANIA WELL,
OAHU. BASALT
AQUIFER.
318
39
8.2
8.9
37.4
3.5
78.1
7.8
49.0
0.05
2.0
00.
(1965)
14
KALAUAO STREAM,
OAHU, BASALTIC
ROCKS IN
WATERSHED.
16.0
6.0
5.0
8.0
0.6
37
9.0
20.2
0.06
0.9
WATER
RESOURCES
RESEARCH
CENTER
\.XIII V, HAWAII
096])
15
WELL T-191
SAMPLE DEPTH
530 FEET OAHU,
BASALT AQUIFER.
37.0
6.0
6.5
19.0
2.5
41
10.0
24.0
0.13
1.2
00.
2
USI~
P~LUU
0AI-fJ •
11
12
106
38.6
30
ANAlYSIS
1'U1BER
DESCR I PTION OF
SAMPLE
SPECIFIC
ELECTRICAL
CONDucTANCE
MICRC»1OS
AT 25°C
DISSOLVED
CONSTlT~NTS
Si02
Ca
Mg
Na
OF WATER IN PARTS PER MILLION
K
HC03
SO~
F
CI
ANALYTICAL
lABORATORY
N03
16
WELL T-202
SAMPLE DEPTH
308 FEET OAHU,
BASALT AQU I FER.
SO."
12.0
12.0
99
5. I
6..
27.6
162
0.11
6."
00.
17
KAULAULA WELL,
KAUAI, BASALT
AQUIFER.
60.0
23.0
"0.5
80.0
1.0
15"
15.0
159
0.25
3.6
00.
18
RAIN WATER
FROM PlASTIC
SHEET. DATE
STREET, OAHU.
0.0
<1
<I
<1
0.0
19
RAIN WATER
FROM RAIN
GAtX;E.
HAEKAU, MIIUI
0.0
20
HALAWA STREAM,
OAHU. BASALT
IN WATERSHED.
(KLNISHI, 1956)
15.8
21
KEALIA RIVER,
KAUAI. BASALT
IN WATERSHED.
(KLNISHI, 1956)
22
2.5
2.8 0.0
0.0
00.
5.2
6.5 0.0
0.0
00.
1.5
2.5
0.0
6.0
2.9
9.8
0.5
l.NIV. HAWAII,
DEPT.
OiEMISTRY.
(956)
1".6
10.3
18."
1".6
1.0
00.
ANA/-()LA STREAM,
KAVAI. BASALT
IN WATERSHED.
(Kl.NISHI, 1956)
7.9
9.0
16.1
12.6
0.5
00.
23
-KAWAIHAE STREAM,
HAWAII. BASALT
IN WATERSHED.
(KUNISHI, 1956)
26.8
11. 6
7.9
5.0
1.2
00.
2..
WAIPIO STREAM,
HAWAII. BASALT
IN WATERSHED.
(Kl.NISHI, 1956)
5.0
3.9
I."
2.7
0.3
00.
25
lAO STREAM,
MIIUI. BASALT
IN WATERSHED.
(Kl.NISHI, 1956)
16.6
15.5
8.5
5.5
0.6
00.
26
Tl.MLt'lU RIVER,
DUBLON IS. (TRlJ<).
BASALT AND ANDESITE IN DRAINIlGE
BASIN. (VALENCIANO
ANO TAKASAK I, 1959)
26
8."
".6
8.1
0.9
51
2.6
27
l.f'\I\TAC RIVER,
GUAM. BASALT
IN ORAINIlGE BASIN.
(WARD AND BROOKHART,
1962)
..0
2"
3.0
2"3
2.6
1"
00.
28
tX;lJol RIVER, GUAM
BASALT IN DRAINAGE
BASIN. (WAR\;) ANO
BROOKHART, 1962)
30
11
2.5
60
1.5
13
00.
29
ALMAGOSA SPRINGS,
GUAM. LIMESTONE
AQUIFER. (WARD &
BROOKHART, 1962)
0.8
158
2.0
12
00.
7.1
..8
7.2
"9
II
6.6
2.7
7.8
10
8.0
-
U.S. GEOL.
SURVEY.
31
ANALYSIS
NlJ'oIBER
DESCRIPTION OF
SAMPLE
SPECIFIC
ELECTRICAL
CONDUCTANCE
MICROt+iOS
AT 25°C
30
DONN I SPRlt>(;,
SAl PAN.
LIMESTONE
AQUIFER.
(DAVIS, 1958)
31
TANAPAG SPRIN;
*1, SAIPAN.
ANDES ITE AND
DACITE AQUIFER.
(DAVIS, 1958)
32
WARM SPR It>(;,
PAGAN
(MARIANAS)
BASALT TALUS
AQUIFER.
(CORWIN /IN)
OTHERS, 1957)
975
33
OCEAN WATER,
PAGAN
(MARIANAS).
(CORWIN &
OTHERS, 1957)
50,600
34
NARICUAL RIVER,
ANZOATEGUI
STATE,
VENEZUELA
SEDIMENTARY
ROCKS IN
DRAINAGE BASIN.
35
WELL AT EL
TIGRE, VENEZUELA.
IN SEDIMENTARY
ROCKS, SANDSTONE (1).
36
37
DISSOLVED CONSTITUENTS OF WATER IN PARTS PER MILLION
SiO z
7.0
Ca
111
Mg
Na
K
5.2
18.0
0.7
47
45
14
32
63
41
15
122
3.4
385
1370
9620
9.7
10
2
HC03
333
S04
8.2
C1
F
30
232
16
23
10
79
63
224
401
141
2630
19000
17
42
15
6
ANALYTICAL
LABORATORY
NO]
11.0
DO.
MEDICAL
LABORATORY,
SAl PAN.
0.9
25
13
1.4
U.S. GEOL.
SURVEY.
00.
S.N. DAVIS.
28
20
0
0
6
5
a
6
0.1
0.1
INST. NAC.
OBRAS
SANITARIAS,
CARACAS.
NEVARI RIVER,
VENEZUELA.
WATERSHED
ENTIRELY SEDIMENTARY ROCKS.
LOW RIVER
DISCHARGE.
367
10
52
5
15
156
25
20
0.15
0.4
00.
NIO:VARI RIVER,
VENEZUELA.
HIGH DISCHARGE.
224
10
35
4
8
97
25
10
0.0
1.4
DO.