81
32
Technical Report Series
Number 78-1
32
THE RESULTS OF
FOUR OCEANOGRAPHIC CRUISES
IN THE GEORGIA BIGHT
by
L. P. Atkinson
31
31
Georgia Marine Science Center
University System of Georgia
Skidaway Island, Georgia
81
THE RESULTS OF FOUR OCEANOGRAPHIC CRUISES
IN THE GEORGIA BIGHT
L. P. Atkinson
Skidaway Institute of Oceanography
P. 0. Box 13687
Savannah, Georgia 31406
The Technical Report Series of the Georgia Marine Science Center
is issued by the Georgia Sea Grant Program and the Marine Extension
Service of the University of Georgia on Skidaway Island (P. 0. Box 13687,
Savannah, Georgia 31406). It was established to provide dissemination
of technical information and progress reports resulting from marine
studies and investigations mainly by staff and faculty of the University
System of Georgia. In addition, it is intended for the presentation of
techniques and methods, reduced data and general information of interest
to industry, local, regional, and state governments and the public.
Information contained in these reports is in the public domain. If this
prepublication copy is cited, it should be cited as an unpublished
manuscript.
TABLE OF CONTENTS
Page
List of Tables .
iii
List of Figures
iv
Acknowledgements
vi
Introduction . .
2
Results of Four Seasonal Cruises
Data
2
Horizontal Distributions
Surface Temperature
Bottom Temperature
Surface Salinity
Surface Density
Bottom Nutrients
3
3
3
3
4
4
Vertical Sections . .
Cruise E-13-73, 5-10 September 1973
Cruise E-19-73, 10-15 December 1973
Cruise E-3-74, 24-29 April 1974
Cruise E-12-74, 23-30 July 1974
Duscussion . . .
5
5
6
7
7
9
Freshwater Volume
9
Drift Bottle Returns
10
Apparent Oxygen Utilization
ll
Oxygen Anomaly
12
Summarized Horizontal Effect of Runoff and Intrusions
13
The Ranges of Temperature
13
T-S Relationship
15
Nitrate-Phosphate-Silicate-Temperature Relationships
16
Conclusions
18
References
19
Figures
20
ii
LIST OF TABLES
Page
1.
Sample Inventory . . .
2.
Average Onshore Extent of Intrusions and Offshore Extent
of Runoff . . . . . . . . . . . . .
. . ..... .
2
iii
14
LIST OF FIGURES
Page
l.
Station Locations, Cruise E-13-73
21
2.
Station Locations, Cruise E-19-73
22
3.
Station Locations, Cruise E-3-74
23
4.
Station Locations, Cruise E-12-74
24
5.
Surface Temperature
25
6.
Bottom Temperature
26
7.
Surface Salinity
27
8.
Surface Density
28
9.
Bottom Nitrate
29
10.
Vertical Section, Cruise E-13-73, Section I
30
11.
Vertical Section, Cruise E-13-73, Section II
31
12.
Vertical Section, Cruise E-13-73, Section III
32
13.
Vertical Section, Cruise E-13-73, Section IV
33
14.
Vertical Section, Cruise E-13-73, Section
v
34
15.
Vertical Section, Cruise E-19-73, Section I
35
16.
Vertical Section, Cruise E-19-73, Section I I
36
17.
Vertical Section, Cruise E-19-73, Section III
37
18.
Vertical Section, Cruise E-19-73, Section IV
38
19 .
Vertical Section, Cruise E-19-73, Section
v
39
20.
Vertical Section, Cruise E-19-73, Section VI
40
21.
Vertical Section, Cruise E-3-74, Section I
41
22.
Vertical Section, Cruise E-3-74, Section II
42
23.
Vertical Section, Cruise E-3-74, Section III
43
24.
Vertical Section, Cruise E-3-74, Section IV
44
25.
Vertical Section, Cruise E-3-74, Section
v
45
26.
Vertical Section, Cruise E-3-74, Section VI
46
iv
LIST OF FIGURES (Cont'd)
Page
27.
Vertical Section, Cruise E-12-74, Section I
47
28.
Vertical Section, Cruise E-12-74, Section II
48
29.
Vertical Section, Cruise E-12-74, Section III
49
30.
Vertical Section, Cruise E-12-74, Section IV
50
31.
Vertical Section, Cruise E-12-74, Section V
51
32.
Vertical Section, Cruise E-12-74, Section VI
52
33.
Distribution of Freshwater
53
34.
Drift Bottle Trajectories
54
35.
Apparent Oxygen Utilization, Cruise E-13-73
55
36.
Apparent Oxygen Utilization, Cruise E-19-73
56
37.
Apparent Oxygen Utilization, Cruise E-3-74
57
38.
Apparent Oxygen Utilization, Cruise E-12-74
58
39.
Oxygen Anomaly, Cruise E-13-73
59
40.
Oxygen Anomaly, Cruise E-19-73
60
41.
Oxygen Anomaly, Cruise E-3-74
61
42.
Oxygen Anomaly, Cruise E-12-74
62
43.
Summarized Horizontal Extent of Runoff and Intrusions
E-13-73
. .
.
.
63
44.
45.
46.
Summarized Horizontal Extent of Runoff and Intrusions
.
E-19-73
. .
.
64
Summarized Horizontal Extent of Runoff and Intrusions
. .
E-3-74
.
.
65
Summarized Horizontal Extent of Runoff and Intrusions
E-12-74
.
66
.
.
47.
Temperature-Salinity Plot .
48.
Schematic Seasonal T-S Plot
68
49.
Phosphate- Nitrate Plot
69
50.
Nitrate-Apparent Oxygen Ut il i za t ion Plot
70
51.
Nitrate-Temperature Plot
71
67
v
ACKNOWLEDGEMENTS
These cruises were a cooperative study coordinated by L. P.
Atkinson.
The following scientists acted as investigators in their
particular fields:
H. L. Windom - Trace Metals; W. M. Dunstan -
Phytoplankton; J. Kraeuter- Benthos; L. Sick - Zooplankton.
The
project was originally funded by a research grant from the Skidaway
Institute of Oceanography.
Ship support was provided by the Oceano-
graphic Program at Duke University Marine Laboratory.
The Oceano-
graphic Program is supported by the National Science Foundation Grant
GA-27725.
Additional funding to analyze the data was provided by the
Georgia Sea Grant Program (NOAA #04-6-158-44017) and the U. S.
Department of Energy (E(38-l)-889.
This report is published as a part of the Georgia Marine Science
Center•s Technical Report series issued by the Georgia Sea Grant
Program under NOAA Office of Sea Grant #04-7-158-44126.
vi
INTRODUCTION
During 1973 and 1974 we conducted four oceanographic cruises in
the Georgia Bight with the purpose of gaining background seasonal data
with which to plan more specific experiments.
In this technical report
the data are presented in graphical form with interpretation.
The data
itself was published in two technical reports (Atkinson, 1975 and 1976).
Some of the interpretations in this report will be given in more detail
in published journal articles.
2
RESULTS OF FOUR SEASONAL CRUISES
Data
The basic station grid was sampled four times as shown in Figures
In addition to the onshore/offshore line of stations samples were
1-4.
occasionally taken between sections.
The dates and sampling activities for the four Georgia Bight cruises
are summarized in the following table:
Table 1.
Sample Inventory
Cruise Name
Date {Inclusive)
# Stations
E-13-73
4-11/IX/73
Dates
E-19-73
8-15/XII/73
E-3-74
23-30/IV /74
E-12-74
23-30/VI I/74
55
62
63
68
# Sample Depths
278
239
215
296
# Salinity Samples
274
233
213
288
# Oxygen Samples
256
135
207
291
Observations
278
238
212
295
# Nitrate Samples
276
199
180
244
# Phosphate Samples
276
198
204
291
# Silicate Samples
260
200
208
293
60/15
60/15
36/18
36/18
# Temperature
Drift Bottles Released
(#/Stations)
All of the hydrographic data and bathythermograph profiles are
stored with the National Oceanographic Data Center and are available
under the appropriate cruise name.
The horizontal plots are presented first, followed by the vertical
plots.
Cruises are referred to by the name (e.g., E-19-73) or the month
during which the cruise took place.
3
Horizontal Distributions
Surface Temperature.
Surface temperatures (Figure 5) were observed
to range from less than 14°C to greater than 29°C.
The higher tempera-
ture are always found in the vicinity of the Gulf Stream.
During the
summer (E-13-73 and E-12-74) solar heating is effective in raising the
surface temperature of the Bight uniformly.
Thus the horizontal
temperature gradients are minimal during the summer.
During the winter
and spring {E-19-73 and E-3-74) a definite offshore gradient in temperature occurs. On E-19-73 the waters are cooling in response to lower air
temperatures. During E-3-74 the shelf waters are generally warmer in
response to warmer air temperatures and solar insolation.
In the spring
(E-3-74) horizontal gradients are minimal except in the vicinity of the
Gulf Stream.
Bottom Temperature.
The bottom temperature distributions (Figure
6) must be compared to the surface temperature distributions.
In three
cases (upper and lower left, and lower right) bottom temperatures
decrease towards the offshore.
This is in contrast to the surface water
temperatures that increase in the offshore direction.
This occurs
because relatjvely cold, deep, Gulf Stream water is moving onshore along
the bottom. This is normally referred to as the intrusion process.
This
process is very important because it brings new water onto the shelf,
replacing what was there.
The intrusion process is also evident in the
December cruise (upper right) but because the shelf waters are relatively
cold (15-20C) the intruding Gulf Stream water appears warm.
Surface Salinity.
greater than 36 0 joo.
Surface salinities (Figure 7) range from 31 to
The lower salinities are found near the shore as
4
expected.
isobath.
In general the 35°/oo isohaline follows the 18m (10 fathom)
However south of the Altamaha River the isohalines begin to
intersect the coast.
The surface shelf water salinities generally are
greater than 36°/oo with a tendency for higher salinities to the south
and lower salinities to the north at the same isobath.
During cruise E-13-73 a special situation existed.
The low surface
salinities on the outer shelf were hypothesized to originate from the
Mississippi River during periods of high runoff.
See Atkinson and
Wallace (1975) for additional discussion.
Surface Density.
The surface density plots (Figure 8) show the
effect of low salinity water lying along the coast.
The central shelf
waters are quite often of higher density than inner or outer shelf
waters because of the combination of relative high salinities and low
temperatures in contrast to higher offshore salinities (and temperatures).
Nearshore geostrophic currents to the south are indicated in all
cruises except E-19-73.
Bottom Nutrients.
The intrusion of deeper-nutrient rich water onto
the shelf is one of the principal sources of phytoplankton nutrients.
One way of identifying intruding waters is by looking at the near bottom
concentrations of the phytoplankton nutrients and especially nitrate
(Figure 9).
As Figure 9 demonstrates nitrate is usually at very low concentrations in the shelf waters, typically being less than 1
~m.
the vicinity of an intrusion it is higher, often reaching 10
However, in
~m .
The
figures show a steady increase in the nitrate concentration in the near
bottom waters towards the offshore with the only variant being where the
increase starts in the cross-shelf direction.
5
The wave-like structures in these plots are not significant since
they could reflect the bias in the time required for sampling.
It is
significant however that there always appeared to be an intrusion of
nitrate-rich water off the St. Johns River.
Vertical Sections
The vertical sections indicate, when combined with the horizontal
data, a three dimensional view of the shelf.
The data presented are
sample location and depth, temperature, sal i nity, sigma-t (density),
oxygen, phosphate, nitrate and silicate .
The legend above the section refer to station numbers.
The Roman
numerals inset in the section refer to the onshore/offshore sections,
I being the most northerly and VI the most southerly . Since station
numbers, locations and sections were nea rly invariant during the
cruises the reader may easily compare various stations and sections.
For each cruise the sections proceed f rom north to south.
The stations
in a section were either 5, 10, or 15 nautical miles (9 . 3, 18.5 or
27.8 km) apart.
Cruise E-13-73, 5-10 September 1973. (Figures 10-14) On all
sections a strong thermocline extended to varying distances across the
shelf.
If one compares the vertical temperature profiles with the
horizontal distribution of bottom temperatures the cause of the cold
bottom waters becomes evident.
The steeply sloping isotherms can
expose cold water to very shallow depths . For example on Section V
(Figure 14) at station 54 18°C water is found at about 220 m, whereas
at station 51, which is 25 nautical miles (46 km) to the west, 18°C
water is found at 50 m:
a rise of 3.7 m per km.
The intense thermocline in the outer shelf waters caused by the
invasion of deeper, cold Gulf Stream waters has many important consequences.
6
The outer shelf is extremely stable because of the extreme vertical
density gradients.
The cold water contains many dissolved constituents
that are lacking in shelf water and thus becomes an important source of
these constituents.
Nitrate, phosphate and silicate are quite high on the outer shelf
in relation to the lower temperatures because their source is cold, deep
water.
The onshore movement of nutrient-rich water is especially
noticeable in Section V (Figure 14).
An area of maximum salinity is always found at depths of 100-300
meters.
In this area salinities often reach 36.5°/oo and occasionally
36.7 0 joo.
Nearshore salinities progressively decrease .
As the near-
shore is approached the surface salinity is nearly always less than the
bottom salinity.
This is expected since fresher water flows out at the
surface and salt water flows shoreward to replace that entrained in the
surface flow.
Silica and phosphate also increase towards the coast with
higher concentrations usually found at the surface. This is because the
river water carries high concentrations of these nutrients .
The lens of low salinity water that appears in the surface waters
near the shelf break, which is especially noticable in sections III, IV,
and V (Figures 12-14), represents water that we hypothesized is of
Mississippi River origin.
An oxygen minimum is associated with the zone of high salinity.
Concentrations often are less than 3.5 ml 0211.
Cruise E-19-73, 10-15 December 1973. (Figures 15-20)
This cruise
was during a period of strong winds and cooling and the data reflect
that.
Nearly all isolines are vertical which indicate the complete
absence of vertical gradients in the shelf waters.
7
Temperature and salinity progressively decrease towards the coast
indicative of atmospheric cooling and the influence of river runoff,
respectively.
In all sections the colder deep water is poised at the
shelf edge and nutrient concentrations are higher in that area.
In
fact in spite of the intense wind mixing the temperature and nutrient
profiles at the shelf break look much like Cruise E-13-73.
Temperature data indicates the Gulf Stream lies nearer to the
shelf break in the southern part of the study area relative to the
northern sections.
Cruise E-3-74, 24-29 April 1974 (Figures 21-26).
This cruise was
during a time of moderation of the stronger winter winds and seasonal
heating.
Shelf water temperatures are 18-21°C with little horizontal
or vertical structure.The outer shelf waters on section VI (Figure 26)
are significantly affected by an intrusion of colder Gulf Stream
water.
This results in the coldest shelf waters being in the most
southerly section.
Salinities in the shelf waters decrease towards the coast and
exhibit estuarine type structure with higher salinities near bottom.
A salinity maximum usually occurs well east of the shelf break at
depths of 100-200 m.
The isotherms in deeper water slope up to the east in section I
and II then down (Figures 21-22).
At other more southerly sections,
they slope down to the east. This implies a counter-current near the
shelf break in the northern part of the area:
isotherms sloping down
to the west indicate the possible presence of a southerly flowing
current (flowing counter to the Gulf Stream).
8
The nutrient concentrations reflect the presence of colder water
at the shelf break and are relatively high.
Sections I and VI (Figures
21, 26) show an especially active intrusion of deeper Gulf Stream
water into the outer shelf waters.
Oxygen concentrations show a consistent minimum at 100-200 m.
Cruise E-12-74, 23-30 July 1974 (Figures 27-32).
was in July during the typical summer season.
by southerly winds.
This cruise
The area is dominated
In all sections there was a significant intrusion
of colder water onto the shelf.
On section I (Figure 27) water of 2ooc is present at the shelf
break.
This cold water was accompanied by nutrient concentrations of
.3, 2 and 2
There
~m
for phosphate, nitrate and silicate, respectively.
is an indication of a counter-current at 200- to 300 m in the
slope of the isotherms and isopycnals.
Low salinity water is present
in the nearshore surface waters implying an offshore movement of
surface waters.
No salinity maxima is observed which implies that the
Gulf Stream lies farther to the east as is also implied by the isotherm
slopes.
Section II is similar to section I with 20°C water at the shelf
break. And again this water is accompanied by high nutrient concentrations.
The lack of a well-developed salinity maximum and the
isotherm position indicates that the Gulf Stream is well to the east
of our stations.
Salinities decrease near the coast.
There is also
an indication of offshore flow of low salinity water at mid-depth in
the middle shelf.
There are no well-developed oxygen minima.
In Section III (Figure 29) there are indications that the Gulf
Stream is near the shelf break.
None of the isopycnals or isotherms
9
slope down to the west and the presence of a salinity maximum indicate
that the Gulf Stream is closer to the she lf.
20°C water is still at the
shelf break and accompanied by high nutrient concentrations.
In Section IV (Figure 30) the position of the isohalines indicates
that the Stream is still near the shelf break.
Nutrient concentrations
are low because of the Gulf Stream position.
In Section V (Figure 31) a current reversal is indicated near the
shelf break. The isotherms and isopycnals dip at about 100 m near the
shelf break.
Nutrient concentrations are higher.
Section VI (Figure 32) represents an eastern movement of the
Stream with a current reversal indicated.
eddy like feature.
This could be caused by an
The presence of high salinity water (36.5°/oo) at
shallow depths (Stations 58 and 59) confirms this conclusion.
High
nutrient concentrations also accompany the high salinity water and
nutrient concentrations in the shelf waters have been raised.
It is
concluded that water had intruded into these shelf waters and then was
cut off, which is typical for the intrusion process.
DISCUSSION
In the previous sections the data were examined by plotting in
horizontal and vertical planes.
In this section, we will look at the
relationship between the parameters, such as the temperature-salinity
relationship.
In addition we will calculate new parameters based on the
original observations.
Freshwater Volume
The offshore distribution of river runoff (freshwater) is a useful
indicator of the potential distribution of a river borne pollutant and
of the gross circulation and diffusive characteristics of shelf waters.
10
Freshwater volume is the amount of freshwater (S 0 /oo = 0) in m3
required to reduce the salinity of a water column (1 m2) at 36°/oo to
the observed salinity.
The key assumption is that Georgia Bight waters
would have a salinity of 36.0°/oo if no runoff waters were present.
At
any geographic location the amount of required freshwater to affect the
observed salinity reduction is:
freshwater volume
= number of depths sampled
= twice the base salinity
Si = observed salinity at depth Zi
Z·1 = depth of sample i
where n
72
This calculation is made for each oceanographic station yielding a set
of values for freshwater volume in m3;m 2 that can be plotted and contoured as shown in Figure 33.
Drift Bottle Returns
The drift bottle returns (Figure 34) essentially confirm the
results of Bumpus (1973).
The offshore releases were within 45 km of
the coast and not subject to the direct influence of the Gulf Stream
which dominates flow at the shelf break. Thus these returns indicate the
general direction of circulation of the shelf waters.
The September returns (E-13-73) all indicate a southerly flow with
velocities greater than 20 km/day.
The very high return rate and
consistent southern direction implies a strong coherent flow during this
time.
The December 1973 release had no returns although the release
pattern was similar to the September release.
11
The April 1974 returns were also sparse with only two bottles
returned. They indicated a weak northerly flow.
The July 1974 returns were high with a strong northerly flow in the
northern part of the Georgia Bight and a southerly flow indicated in the
inshore part of the southern part of the Bight.
The July data may indicate
the transition from a predominant northward flow in the winter, spring
and early summer to a southerly flow in later summer and fall.
Apparent Oxygen Utilization
In deeper ocean waters the decomposition of plant and animal
tissue produces higher concentrations of phosphate, nitrate, and silicate and reduces the amounts of oxygen present:
consumes oxygen.
the oxidation process
The loss of oxygen is measured by subtracting the
measured amount (02) from that which should be there if no oxidation had
occurred.
The amount of 02 that should be in solution is the saturation
value (02) which is the amount of 02 that dissolved in seawater if that
water is equilibrated with air at the observed temperature and salinity.
The apparent oxygen utilization (AOU) is 02 - 02 . Since the oxygen loss
(AOU) is dependent on biological oxidative processes it is proportional
to the nitrate, phosphate, and silicate produced.
The high AOU (low
oxygen) water (Figures 35-38) usually inclined with depth as did the
isotherms.
These values, although low, are not in any way restrictive
to biological activity.
The initial oxygen concentrations are 5-6 ml
02/l so even an AOU of 3 ml 0211 leaves 2-3 ml 0211 in the water. While
the AOU is an interesting parameter the oxygen anomaly is in many ways
more useful.
12
Oxygen Anomaly
The water flowing north in the Gulf Stream has at least two origins.
One is the Florida Strait between Florida and Cuba.
The second is the
Antilles current which flows northward in the area east of the Bahamas.
These waters have a common origin in the central north Atlantic Ocean,
however, the path for some water is more circuitious than others.
The
waters that emerge from the Straits of Florida have spent much time in
the Caribbean Sea and the Gulf of Mexico and their chemical characteristics have changed.
The Gulf Stream water that traveled through the
Caribbean and Gulf of Mexico has lower oxygen content than water of an
identical temperature that moved in the Antilles current.
of this difference is the oxygen anomaly.
The amount
Thus this tracer is useful to
define the two water masses and was originally discussed by Rossby
(1936).
Since the tracer indicates water of tropical origin it is
useful in the interpretation of the shelf flora and fauna which often
has tropical components.
During the September cruise (E-13-73) (Figure 39) the zones of high
oxygen anomaly coincided with temperatures of ca. 22°C.
In Sections I
through IV the oxygen anomaly water is not abundant; however, Section V
shows large amounts and what appears to be two masses.
This correlates
with the temperature and density structure which indicates an eddy
feature.
During the December cruise (E-19-73) (Figure 40) the oxygen anomaly
occurs in large quantities in Section VI which coincides with high
nutrient concentrations.
Contrasting Section II and VI temperatures and
oxygen anomaly the oxygen anomaly occurs when the isotherms tilt up
steeply to the continental slope.
This condition corresponds to an east
position of the Gulf Stream with no eddy structures present.
13
The E-3-74 data (April) (Figure 41) shows the pattern displayed
previously.
Where the isotherms indicate an eddy structure we find
oxygen anomaly water at the shelf break.
Data from Cruise E-12-74 (July) (Figure 42) shows the most amounts
of oxygen anomaly.
This correlates with the eddy structure present in
many of the sections (I, III, V, and VI).
The distribution of the anomaly is difficult to predict although it
does correlate with the presence of eddies (isotherms tilting down to
the west) and possibly with Gulf Stream positions.
The important
observation is the extreme variability of the position and amount of
anomalous water.
This could be partly due to bias induced by our
discrete sampling, however we feel more is indicated.
It is indicated
that the amounts of various water masses vary with time in the Gulf
Stream.
Summarized Horizontal Effect of Runoff and Intrusions.
The offshore extent of runoff and the onshore extent of intrusions
were determined from all the data to see if a pattern exists.
The
composite data (Figures 43-46) for the four cruises are summarized in
Table 2.
Runoff averages 56 km offshore in the north but less than 3 km
in the south .
Conversely intrusions extend onshore an average of 20 km
but extend much further onshore in the south than the northern part of
the area.
The Ranges of Temperature
The annual range in water temperature is important since it will
effect animal growth rates or, in extreme cases, the survival rate.
While the nearshore waters have an annual range of 12 . 3°C the offshore
surface waters have an average range of 6.4°C and the shelf break
bottom waters an annual range of 4.2°C.
This results from the influence
14
TABLE 2
Average offshore extent of runoff
Section
T
56.5 + 33.3
n=4
II
42.3 + 23.6
n=4
III
33.8 + 15.0
n=4
IV
37.8 + 23.0
n=4
v
19.5 +
1.3
n=4
2.7 + 4.6
n=3
VI
33.4 + 24.7 km
n=23
15.5 + 17.2
n=4
II
12.8 + 10.5
n=4
III
27.3 + 9.5
n=4
IV
11.5 + 1.3
n=4
v
13.5 + 13.4
n=4
VI
40.0 + 30.8
n=3
19.2 + 16.6 km
n=23
Average for all sections
Average inshore extent of
intrusions
Section I
Average for all sections
15
of the Gulf Stream.
The nearshore waters are subject to extreme cooling
and heating causing the large annual range.
The offshore surface waters,
while also subject to seasonal heating and cooling are moderated by the
consistently warm Gulf Stream waters.
The deep waters offshore are not
subject to atmospheric cooling or heating, but only minor variations
caused by Gulf Stream meandering.
These results are important to fisheries since many tropical
species cannot tolerate the large temperature ranges observed in the
nearshore waters. However they can tolerate the minor temperature
ranges in the deeper waters at the shelf break.
T-S Relationship
The relationship of temperature to salinity, a T-S plot, is a
standard oceanographic procedure used to analyze data.
In the central
oceans the TS plot is very characteristic for each ocean and each depth
in that ocean (i.e., water of 10°C always has a salinity of about
35.0 0 joo).
The relationship is very predictable for subsurface waters.
However, surface waters can easily change temperature because of atmospheric conditions, and the salinity may change as a result of runoff,
rain, or evaporation.
Therefore, while the T-S relationship of deeper
waters such as the deeper Gulf Stream waters is constant, the T-S relationship of Georgia shelf waters is quite variable depending on the
season.
Figure 47 shows the T-S plots for the four cruises.
The early winter cruise is a time of minimum temperatures and low
runoff, consequently observed temperatures were at a minimum and salinities
were relatively high.
During April 1974, which is during the high runoff and warming
season, higher temperatures were observed and the lowest salinities of
any cruise.
16
In July 1974, during a period of highest temperatures and decreasing runoff, higher temperatures were observed and lower salinities than
in September 1973 when runoff is lower.
The T-S relationship of shelf water closely reflects the runoff and
air temperature.
That relationship is shown in the following schematic
(Figure 48). This diagram was made by taking the minimum observed salinities and temperature for the four cruises, plotting them (heavy dots)
and then connecting the dots.
This represents the seasonal cycle of
salinity and temperature in the nearshore zone for the whole coast.
The
pattern reflects the combined effect of seasonally varying temperatures
and runoff that peaks in the late winter and again in the late summer.
Thus from January to April the water continues to warm, but the runoff
decreases causing salinity to increase.
From July to September the
temperatures stabilize while runoff increases, decreasing the salinity.
Finally, from October to December the temperature decreases, because of
lowering air temperature, while salinity increases because of decreased
runoff.
This is caused by the subtropical runoff pattern:
the runoff
pattern in most temperate areas is unimodal.
Nitrate-Phosphate-Silicate-Temperature Relationships
The various relationships between nitrate, phosphate, silicate and
temperature are useful to confirm the quality of the data and to elucidate some of the chemical, biological, and physical processes at work.
The ratio between nitrate and phosphate concentrations in deeper
water is usually 16:1.
This results from the 16:1 ratio of N toP in
phytoplankton tissue.
The subsequent bacterial mineralization of this
tissue in deep water produces the observed 16:1 ratio.
All of our
17
nitrate-phosphate data is plotted in Figure 49.
1 line is also shown.
The theoretical 16 to
Note that at low concentrations there is usually
excess phosphate with respect to nitrate.
These samples are from
shallow areas where nitrate is consumed and not quickly released while
phosphate is quickly released.
The plot of nitrate vs AOU (apparent oxygen utilization; Figure 50)
demonstrates that nitrate is produced at the expense of oxygen:
an
oxidation/reduction reaction.
Since all nutrient concentrations generally increase with depth and
temperature decreases one may expect a relationship between these
parameters. Figure 51 shows a nitrate-temperature plot of all of our
data.
At lower temperatures the relationship is very consistent and
essentially allows one to predict nitrate given the water temperature.
18
CONCLUSIONS
The preceding data presentation and discussions make many points.
It should be apparent that many things about the Georgia Bight are
predictable. Temperature-salinity relationships and patterns are consistent and reasonably predictable as are the nutrient relationships.
Knowledge of the processes that control these is where we fall short.
Intrusions, although easily recognized, are not understood.
know to what extent they occur or how often.
We do not
The distribution of
freshwater in the offshore waters is also easily detected but we do not
understand the forces that disperse the waters and produce the distribution we observe.
The understanding of these processes is more important in many
cases than knowing the distribution of some compound resulting from the
process. We must know the process if we are to make reasonable judgments
concerning the effects of man•s activities on the ocean system.
19
REFERENCES
Atkinson, L. P., Oceanographic observations in the Georgia Bight, R/V
EASTWARD cruises E-13-73
~nd
E-19-73.
Georgia Marine Science
Center Technical Report 75-6, 1975.
Atkinson, L. P., Oceanographic observations in the Georgia Bight, R/V
EASTWARD cruises E-3-74 and E-12-74.
Georgia Marine Science
Center Technical Report 76-1, 1976.
Atkinson, L. P. and D. Wallace, The source of unusually low surface
salinities in the Gulf Stream off Georgia.
Deep-Sea Res., 29:913-
916, 1975.
Bumpus, D. F., A description of the circulation on the continental shelf
of the east coast of the United States, in Progress in Oceanography,
Vol. 6., 1973.
Rossby, C.-G.,
Dynamics of steady ocean currents in the light of experi-
mental fluid dynamics.
5(1), 1936.
Papers in Physical Oceanog. and Meterol.,
20
FIGURES
21
CAP£
ROW AI N
J lo
v..""
v..<l>
':t~
'?q,<;t..._ ~
<?
<?"".>
I
0
0
o
.:.,.)
¢
>O
20
I
~
+
I
I
\
E-13-73
4- I I SEPT I 973
C.t. PE
\.,
C ANAVER A L
(
_l .o:.Figure lo
79"
Station locations, Cruise E-13-73
22
)2 .
+
) I.
+
lo• I
+
E-19-73
8-IS DEC 1973
,,.
Figure 2.
Station Locations, Cruise E-19-73
23
C A P(
I •
R OM AIN
/
.,.
l-
~ ~·
+
Jo· '
.,_)
¢
oo,
«>-'>:>
«>~
to
.«>' ~ ~~
)
100
~'f7~
r
)
\
l
I
I
\\
E-3-74
23-3~
\
s o•
Fi gure 3.
,
I
__
APRIL, 1974
79 "
Station Locations, Cruise E-3-74
24
CAP£
/..
RO,A IN
,
....
1. •
(
/
,... j
,_ j'
/'
'
\
\
\\
29"
E-12-7Lf
2::3-::3121 JULY 197Lf
eo•
~j
Figure 4.
79"
-
Station Locations, Cruise E-12-74
25
r
...
.,.
29
...
,.
Surface Temperature
T't:
Surface Temperature
T"C
E-19 -7 3
8 - 19/XII/73
E-13-73
4 - 11/ IX:/73
~.Ill k!lam£0e'6
0
50
100
...
...
•..
Surface Temperature
T't:
E - 3 - 74
23 - 30/TIZ:/74
Figure 5. ·surface Temperature
Surface Temperature
T'C
E-12 - 74
23- 30/:iZII 174
26
J2•
32.
,,.
,.
,.
J/•
Bottom Temperature
T°C
E-13-73
4-11/IX/73
sca le
lO"
-::···
0
1n
Bottom Temperature
T°C
E- 19-73
8-19/Xll/73
kilometers
50
100
30"
.,.
,.
..
,
.········
JZ.
32.
JZ•
J2•
,,.
,.
31"
J /•
Bottom Temperature
T°C
E- 3 - 74
23 -30/.ril/74
Bottom Temperatur
T°C
E-12 - 74
23-30/W 174
JO •
Figure 6.
Bottom Temperature
27
..
,.
_,
l •
,.
Jl'
Surface Salinity
Surface Salinity
S•t••
E-19 -7 3
8-19 /XII/ 73
s .,••
E-13-73
4- 11/ IX/73
.
r
.····
l
.·,.
...
•
/
/
,.
ll"
./
. ;"
Surface Sal1n ity
s .,.•
·..-
E-3 -74
23-30 /N/74
Figure 7.
.r .
Surface Salinity
.
Surface Salinity
s .,••
E - 12 -74
23 - 30/:sz:II/74
28
.,.
.,.
1r
Surface Density
sigma-t
E -1 9 -73
B-19t xn 173
seale m kilometer<.
50
0
.
r
100
..···
.•
/
31'
~·
Surface Dens ity
s igma-t
E -1 2 - 74
Surface Density
s igma - t
E- 3 -74
23 - 30/'W/74
23 -30/TSl/74
Figure 8.
Surface Density
29
-~
,.
...
,.
Bottom N1trate
jjg - all L
E - 13-73
4 - 11/IX/13
.....··
Bottom Nitrate
~ - at/L
E-19-73
8-19/XI[/73
_),!
...........
...
Bottom Nitrate
Bottom Nitrate
)JQ-at/L
E -12-74
23-30/JZI1J74
~-at/L
E- 3-74
23-30/17/74
Figure 9.
Bottom Nitrate
30
0
1
2
4
3
5
&
&
~
10
01
2
SAMPLE POINTS
100
5
TEMPERATURE
I
100
( •C)
E-13 -7 3
5 f iJ: /73
I
200
200
300
300
400
400
6
7
8
~
10
0
~
SALINITY
( "loo)
100
4
3
I
_./'
E - 13 - 73
5/[1/73
E - 13-73
5/[1/73
1
4
2 3
6
g
10
7
6
~
10
SIGMA - T
I
E-13 - 73
5 / tl /73
../
../d
200
7
&
23
100
.25
5
200
/
300
300
400
400
0
100
1
2
4
3
5
OXYGEN
(mi/LJ
I
10
0
1
E -13 - 73
5 / tl /73
200
300
300
400
400
0
100
NITR ..TE
(UQ -at/Ll
3
4
5
e
PHOSPHATE
(ug-<Jt/L)
I
E - 13 - 73
5/IJ: / 73
100
200
2
1
10
100
I
E - 13-73
5/IJ:/73
200
200
/ 10
300
300
400
400
/
~,5..---
Figure 10.
Vertical Section, Cruise E-13-73, Section I
31
20 19 16
0
17
16
15
14
13 12
11
17
20 19 16
16
15
16
15
14 13 12
11
0
•?8
SAMPLE POINTS
TEMPERATURE
(•C)
0
100
E - 13-73
6 -7/ IX/ 73
100
200
200
300
300
400
400
20
0
19 16
0
E - 13 - 73
6-7/IX/73
17
16
11
0
20 19 16
335 3"4 34.5 )!)35.25 35.5
22
SALINITY
SIGMA·T
(•J-)
100
17
n
100
II
E-13 · 73
6-7JlXJ 73
E-13-73
6 -7/IX/73
200
200
300
300
400
400
OXYGEN
(miJL)
100
D
E - 13- 73
6-7/ IX /73
200
300
«>O
20
19 18
17
16
15
14 13 12
11
OF~==~==~~~~--~----~
<0.5
12
NITRATE
100
(>'Q-<lt/ L)
-_3
32 1
-
--;::: 1
SILICATE
0.5
4
~
D
E-13-73
020f,R~19~1~6~::1:7:J::':6~=-t~s~--~14~1=3~12~--~,~--------~
100
(j>9·0IIL)
D
E -13-73
6 - 711XI73
6 - 7t !X I73
200
200
300
400
15
400
Figure 11.
Vertical Section, Cruise E-13-73, Section II
32
0
24
Z1 22 23
24
0'11 22 23
25
2e
27
2e 2G lO
31
32
2!5
2e
27
28 2Q lO
31
32
25
28
27
SAMPLE P()jNTS
m
~RATI.IIE
E -13 - 73
I()()
('Cl
100
7 -ll t l% 113
II
E - 13 - 73
7 - ll tl% 173
~.0
200
)()()
lOO
400
400
24
25
2!1
0
Z1 22 23
SIGMA-T
( 't- )
I()()
m
100
200
200
300
)()()
400
400
24
21 22 23
m
E - 13 - 73
7-8 t 1Xt73
E-13- 73
7-8/IX/73
0
24
1 22
-- 34.~ )!)D
SALINITY
25
28
(.2)
!)D
•t3l
~TE
OXYG£N
100
• (.2 )
0.1
( mi/L)
100
m
(118-<lt /L)
II
E -1 3 - 73
7- 8 / IX /73
E -13 -73
7-8 / IX /73
200
)()()
400
0
21 22 23
24
25
(1.1)
28
27
• (\2 )
NITRATE
(I'Q-<rt /L)
100
m
E-13 -73
7- 8 /IX / 73
200
)()()
400
Figure 12 .
Vertical Section, Cruise E-13-73, Section III
33
4 3 42 4 1
0
40
39
38
37 36 35
34
33
4 3 42 41
0
I
SAMPLE POINTS
200
300
300
400
400
40
39
38
43 42 41
0
36
SALINITY
200
200
300
300
400
400
100
40
39
38
37 36 35
34
33
>~
43 42 41
0
.5 , .3
<~
33
36
100
(m i l l )
40
39
38
37 36 35
Q2
PHOSPHATE
!.,g-ot!LI
OXYGEN
IlZ:
IlZ:
E -13-73
8-9 /IX /7 3
200
200
300
300
400
400
40
39
IlZ:
E -1 3 -73
8 - 9/IX/73
43 42 41
0
40
E -1 3-73
8 - 9/IX/73
E -1 3 -73
8-9 /IX /73
>~
39
38
37 36 35
34
33
43 42 41
0
40
39
38
64
100
33
SIGM A - T
100
IlZ:
43 42 41
0
34
21
,.,.. ,
100
37 36 35
E-13-73
8 - 911XI73
200
32 33 34
38
!•c)
IlZ:
100
E -13 -73
8 -9 / IX/73
43 4 2 41
0
39
TEMPERATURE
N
100
40
28
NITRATE
(.,g-ot/L)
100
llZ
N
E -13-7 3
8 -9 / IX /7 3
E-13-73
8 - 9/IX/73
200
200
300
300
400
400
Figure 13.
SILICATE
(.,g -ot/U
Vertical Section, Cruise E-13-73, Section IV
34
33
34
44 45 4e
...
48
IH
4!5
0
.e
47
48
<211
100
SAMPLE POINTS
!50 !51 !52
!54
!53
<28
TEMPERATURE
( 'C l
100
ll
49
ll:
E - 13 -73
9-101 1%173
E - 13 -73
9-10 / ct / 73
200
200
300,
300
400
400
~
'~
' 18
16
'
~'t'\
~
~;
{'o'\
',I \
49
48
47
!50 51 52
!53
!54
44 4!5 46
0
47
48
49
50 51
52
54
53
22
~
100
SALINITY
SIGMA -T
100
( •!.. )
ll:
ll:
200
E-13-73
9 -10/ IX/73
E - 13 -73
9 -10/ IX /73
200
27
300
300
400
400
44 4!5 4e
100
49
48
47
0
!50 !51 52
!53
!54
~ 4.0
45 -
( milL)
~\
ll:
E-13 -7 3
9 -10/llt / 73
200
300
4e
47
0
100
!50 !51 52
!53
54
100
50 51 52
53
!5-4
PHOSPHATE
(,.g -ot/L )
ll:
200
E - 13 -7 3
9-10/llt/73
300
400
400
44 4!5 4e
44 45 4e
47
0
<0 3>0.3
o..
....7<07<~.1
OXYGEN
\
411
<1,0
NITRATE
t,.g-ot /L)
!50 !51 !52
!53
!54
0
100
47
48
49
SILICATE
(..,g -oi/LI
ll:
ll:
E -13-73
9 -10/ JJ[ /73
200
200
300
300
400
400
Figure 14.
E -1 3 -73
9 -10 / JJ[/73
Vertical Section, Cruise E-13-73, Section V
35
01
2
5
4
3
SAMPLE POINTS
l
6
7
i
i
E -19 - 73
10/ Xll /73
100
01
2
0
1
2
111
-4
3
5
6
21
TEM~RATUVe:
c ·c >
7
2~
~
"'-21
I
E-19-73
10/Xll/73
100
3
350 35.5
3
SALINITY
(
.,..
)
I
100
E - 19 -7 3
10/ Xll /73
0
1
2
4
3
6
5
h
5.5 50
5.0
OXYGEN
5.5
( milL>
2
3
4
01
2
4
3
6
7
01= 2
NITRATE
(1'1;1-ot/L)
100
Figure 15.
7
5
6
7
I
E -1 9-73
10/Xll/73
3
2 1
I
E - 19-73
10/ Xl! /7 3
6
PHOSPHATE
( ug -ot/Ll
5.5
100
5
5
<0.04
I
E-19 -73
10/ XD /73
100
01
7
I.
100
4
.lf~
SILICATE
(1'1;1 -0tiLJ
I
E -19-73
10/:xn /73
Vertical Section, Cruise E-19-73, Section I
36
TEMPERATURE
SAMPLE POINTS
n
(• C )
100
E -19 -7 3
11-121 .111 1 73
n
E -19 - 73
11 - 12 / .lll /73
200
200
300
300
500
020~~~~~~==1=7====1=&==~~~~~~~--1~1----------~
)A.()35D 360
20
SALINITY
SIGMA-T
( •t- )
100
D
100
n
E-19-73
11-121 .111 173
E - 11~ - 73
11 -121 .111 173
200
200
300
300
400
400
20 19
0
100
a.o
~
1&
17
20~
18
17
16
11
0
.) .2 .1
!>.!>
OXYGEN
( m i/U
100
n
E -19 - 73
11-12 1.111 173
200
'\
PHOSPHATE
(,.g-<lt /L)
D
E - 19 -7 3
11-121 .111 173
200
300
300
500
400
NITRATE
100
(.,g-at ILl
n
E -1 9 -73
11 - 12/ .lll /73
200
300
400
25
Figure 16.
Vertical Section, Cruise E-19-73, Section II
37
21
24
22 23
25
26
27
26 29 30
31
32
0
2 1 22 23
0
32
24
15
SAMPLE POINTS
m
100
100
E -19 -73
12 -13 /XD / 73
200
200
300
300
400
400
~f1=2~2==2=3~\2~4::=:2:5:=32~e~======-2~7--~~~~=--3~1--~32
26
SIG MA -T
m
100
E - 111 -73
12 -13/ XD /7 3
200
300
400
21
0
22 2 3
24
25
26
27
26 29 30
""
32
( m llll
m
E -111 -73
12 -13/ XU /7 3
~
200
21 22 2 3
0
.2
~;
OXYGE N
100
31
I
..--:::: :;<)
24
25
26
27
28 29 30
.1
PHOSPHATE
( o<~ · at/ U
100
m
E - 111 -73
12 - 13 / J:n /7 3
4.0
200
')~~
300
300
4 00
400
~
2 1 22 2 3
0
25
24
26
27
28 211 30
31
32
21
0
NITRATE
100
(,.g -<lliU
m
100
24
25
26
1
SILICATE
(J.Q -o t il)
m
E - 19 ·73
E - Ul - 73
12- 13 / XU 17 3
12 - 13/ .J:n /7 3
200
200
300
300
400
400
Figure 17.
22 23
Vertical Section, Cruise E-19-73, Section III
31
32
38
)4
04~3~.~:?~,:~'--,,~4~0~.-8 ~3;~~9~X)~l~,~:~~--~?J--~~~~--~-------,
TEMPERATURE
SAMPLE POINT S
Ill
( •C l
TOO
E 19 · 73
16 1X0 t7 )
1Y
E -19 -73
16 / X0 17 3
200
lOO
300
400
400
37 36 35
34
l'>O
SA LI N ITY
TOO
( •I" )
Ill
E -19·73
161 XO I 73
200
300
400
400
<4 3 <42 4 1
40
39
38
37 36 35
34
0~.2~===i_~,======~~~~--,
100
PHOSPHATE
1'-0 · 0lll)
Ill
E -19.-73
16 1 XII / 73
200
300
400
38
'
NITRATE
100
(ug -ott U
Ill
SILICATE
( ug ot /U
4
100
1Y
E - 19 -73
16/ X0 / 73
E -1 9-73
16 1D I73
200
200
300
300
400
Figure 18.
Vertical Section, Cruise E-19-7 3, Section IV
39
45 45
47
48
411
50 51 52
0
53
45 .ole
54
48
49
20
18
SAMPLE POINTS
TEMPERATURE
ll
100
47
0
I
C• Cl
:ll.
100
E-111 -73
14 - 16 / Xll /73
E - 11~ - 73
14 - 10 / Xll /73
200
200
300
300
400
400
4 5 46
47
49
0
100
50 51 52
53
54
45 45
47
48
49
0
35..~
350
3~
360 3625 3625
SA LINITY
..
( •/
)
SIGMA-T
ll
100
E - 19 -73
14 -16/Xll I 7 3
ll
E - 19 - 73
14 -16 / XI! /73
200
200
300
300
400
400
4 5 46
100
PHOSPHATE
(ug -ol /L)
ll
E - 19 - 73
14 -16/XI! /73
300
400
100
NITRATE
(,.g -ot/L )
SILIC ATE
100
ll
ll
E - 19-73
E - 19 -73
14 - 15 / XI! I 73
14 - 16/ D / 73
200
200
300
300
400
400
Figure 19.
( ug · at /L)
Vertical Section, Cruise E-19-73, Section V
40
64
0
!53
!52
!51
SAMPLE
100
eo
511 5e 57
5!5
55
55
P0 1 ~TS
lll
100
E -111 - 73
14 · 15 1:111 17 3
200
200
...
....
...
300
.000
64
0
56
64
0
!53
!52
!5 1
..b.. .h
J~
eo
5Q 58 57
300
400
\
56
55
64
0
63
61
S A LI ~ ITY
( ' 1- )
~~):;\
:lll
E - 111 · 73
14 -1 5!:111 I 73
200
300
...
..
\
400
!53
!5 1
!52
eo
5Q 5e 5 7
~
5!5
55
60
55
56
59 58 57
2~
Jeo
100
64
0
62
SIGMA ·T
:lll
100
E -1 11 -7 3
14 · 15/.IIJJ /73
200
300
"""-2/
~·-
\~.
~
.
...
.000
\
55
64
0
\...:
~
OXYGE~
100
( m i/Ll
K~
lll
E · 1Q-73
14 -1 5IIII!73
200
....
.
\
.
300
..
64
!53
!5 2
!51
eo
200
300
\
.-30-
.000
0
3.!'>
100
.000
64
0
!53
!52
C..o-ot /U
lll
1~
100
E - 111 -7 3
· 15/ XD /73
E - 111 -73
t• -15/ .J:D. /7 3
200
200
300
300
400
400
Figure 20.
55
<2
~I T RATE
100
5!5
Vertical Section, Cruise E-19-73, Section VI
41
1
0
2
.
3
5
e
7
8
g
10
1
0
2
3
4
2
3
.
g
10
SAMPLE POINTS
100
100
I
E -3-74
<!4 -25/lll/74
200
200
300
300
400
400
1
2
0
3
5
4
6
7
6
g
10
1
0
23
35 3!>5
33 34
100
E-3-74
24 - 25/lll/74
·----
300
400
400
.
525
100
10
200
300
3
g
E-3-74
24 - 25/lll/74
.. ··- 3~
200
2
6
I
I
1
7
SIGMA-T
( •t•• )
0
6
24
SALINITY
100
5
5
6
7
8
g
10
~
1
2
0
55
~
OXYGEN
(mi/Ll
I
E - 3-74
24 - 25/ lll /74
5
4
6
7
6
g
10
6
7
6
g
10
PHOSPHATE
(I'Q·Ot /L)
100
1
----
125
200
3
.2 l
E-3-74
24 - 25 / lll/74
200
l 3.25-
300
300
4 00
400
1
0
2
3
5
4
3 2
NITRATE
100
( j<Q-ot /LJ
SILIC ATE
100
(.,g-ot /L)
I
I
E-3-",l4
24 - 25/ lll /74
E-3-74
24-25/lll/74
200
200
300
300
400
Figure 21.
Vertical Section, Cruise E-3-74, Section I
42
20 19
18
17
16
0
15
14 13
12
11
14 1)
12
11
~ -- ...-
SAMPLE POINTS
D
100
TEMPERATURE
(• CI
100
E - 3 -74
25 -26 / ll1/74
74
7>
•A
D
'6
E -3 -74
25 -261 IlZI 74
200
200
·r,
300
300
400
400
20 19
0
17
18
'"
16
15
14
13
12
11
20 19
0
13
12
11
12
11
II
100
n
E - 3-74
2!5-26 / !ll/ 74
E - 3 74
25 - 26 / rl /74
200
200
300
300
400
400
_j
18
14
SIGMA -T
( • !.. )
20 19
0
15
25
SALINITY
100
16
17
18
2A
35
34.!':1
11
12
17
20 19 18
17
16
0
OJ
OXYGEN
( m ilL)
100
PHOSPHATE
100
n
E- 3 - 74
2 !5 - 26 / rl/74
( &.~Q · Ot /l )
D
E - 3 -74
25 -26 / !ll /74
3.5
200
200
<3.25
300
300
400
400
20 19
18
17
16
15
,4
0
13
12
11
20 19 18
0
17
4J
SIL IC ATE
Nl RATE
( ~ g-ot/ LI
100
n
100
1 ~ - ot1 LI
n
E - 3 - 74
E-3-74
25 -26 / !ll/74
25-26/!ll/74
200
200 .
300
300
4 00
400
L_
Figure 22.
Vertical Section, Cruise E-3-74, Section II
43
31
32
32
100
400
SIGMA · T
100
m
E · 3 ·74
26 · 27/lll/74
200
300
4()()
31
200
300
400
400
Figure 23
Vertical Section , Cruise E-3-74 , Section III
32
44
43 42 41
40
3Q
38
37 36 35
34
33
~3
~2
~1
~d
311
36
21
SAMPLE POINTS
100
Ill
nz:
E-3-74
27 - 26/N/74
200
200
300
300
400
400
4 3 42 4 1
0
34.0 31.0
100
40
JQ
35.5
37 36 35
38
36.0 36.25
36.25
34
33
<43 42 4 1
..
38
JQ
36
SIGMA -T
nz:
100
E -3-74
27-26/Lil/74
200
300
300
400
400
39
39
22 23
SALINITY
('/ )
Ill
E - 3 - 74
27-26 / l'Z/74
40
40
- 360 ~
200
43 4 2 41
TEMPERATURE
C'C )
100
E - 3 -74
27 - 26/l'Z/74
38
37 36 35
33
34
~3 ~2 ~·
0
40
37 36 3!5
34
33
34
33
Q2
OXYGEN
PHOSPHATE
(m il L)
100
100
I'Z
27-28/ l'Z /74
200
200
300
300
400
400
43 4 2 41
·a
40
39
38
37 36 35
34
33
43 · 42 4 1
40
JQ
SILICATE
NITRATE
100
(..o - at iL)
Ill
E - 3 -74
27-26 / Ill/74
E - 3 - 7~
( ~ - at1Ll
100
(..O-atiL)
Ill
E-3-74
Ill
E - 3 -74
27- 28/N/ ';:14
27 - 281~ /74
200
200
300
300
\6
20\'
\ 1fl
400
Figure 24.
400
Vertical Section, Cruise E-3-74. Section IV
45
44 4 5 4 6
47
0
49
48
21
.·~
50 5 1 52
53
54
TE MPERATURE
( • Cl
100
44 4 5 4 6
200
200
300
300
400
400
47
49
48
18,5
JS.5
36.5
360
5 0 51 52
53
54
24
49
50 51 5 2
53
54
24
SIGMA -T
.11
E-3-74
28 ·29/ lll /74
200
200
300
300
400
400
d-~4~4~5~46~~=4=7====4=8==~~·=9~~~=5;0~5_1~5~2--~5~3--~54~
>so
5.Q.
rf4 45 46
cso
47
48
49
- - o.1-
02
OXYGEN
50 51 52
53
<Ol
PHOSPHAT£
Cmi/Ll
.11
100
54
25
100
E-3 -74
28 -29 1 1.11 174
s_o
48
47
25
j[
ls.s s.o
53
j[
44 45 46
0
3625
SA LI NITY
0
(
/oo l
100
50 51 5?
E - 3 · 74
28 -2911.11174
E - 3 74
28 ·291 1l1 174
44 4 5 46
49
SAMPLE POINTS
100
j[
0
48
47
0
22 2J 24 .?":>
100
( ~g - at /Ll
.11
E-3 - 74
28- 29 / 1.11174
E - 3 -74
28 - 29 1 1.11174
200
200
300
400
400
dc4=4=5==4~6====4=7====4=8======·=9~~==~s~o_s~~~s~2--~s~J--~sr4~
I
<0.7
NITRATE
100
(ug - ot /L)
.11
SILICATE
100
E -3 -74
28·29/ lll /74
E - 3 -74
28 - 29 / lll /74
200
200
300
300
4001
400
Figure 25.
c.g-at /Ll
.11
Vertical Section, Cruise E-3-74, Section V
46
64
0
63
61
62
60
59 58 57
56
55
54
0
63
300
300
400
400
61
52
59 58 57
50
56
55
36'-
36.25
54
0
63
200
200
300
300
400
400
62
61
50
59 58 57
56
55
59 58 5 7
60
?5
55
56
55
26
E - J - 74
291 1!1174
( m ilL)
64
63
51
62
59 58 57
50
0
~15
OX YGEN
100
51
Ill
100
Ill
53
62
25
E- J -74
29 11!1174
64
0
56
~
Ill
SIGMA -T
SALIN ITY
( ••1.)
100
55
E - J -74
29 11!1174
200
6J
56
- ~>/
<•c)
100
5 9 58 57
50
n
TEMPERATURE
Ill
E - J - 74
291 [Jl/74
200
54
0
51
>2
SAMPLE POINTS
100
62
J2] 4
.6
PHOSPI--ATE
(ug -at /_}
100
Ill
Ill
E-3-74
29 / l'Sl /74
E - 3 - 74
291 15l174
200
200
300
300
400
400~
J
I
64
0
53
51
62
59 58 57
/'-~
NITR ATE
100
60
(,.g -o t/U
56
55
64
0
~
Ill
63
52
, 12 34
61
3
59 58 57
50
2
:!
56
55
4 ~7
SILICATE
100
E-3-74
29 / 1!1174
CuQ· ot fl)
Ill
E - 3-74
29illl/74
200
200
JOOr-
300
400
400
1
J
I
Figure 26.
Vertical Section, Cruise E-3-74, Section VI
47
2
ol
4
3
5
6
7
8
9
10
ol
I
E · 12 -74
23 24 1llll1 74
300
300
400
400
3
4
,.
( ' 1- l
l
E -1 2 -74
23 · 24 / llll /74
9
10
300
300
4 00
400
1
2
3
4
o1
2
( mllll
200
300
300
400
400
o1
100
I
E · 12-74
23 · 24 / llll /74
300
400
4 00
Figure 27.
7
8
9
10
5
6
7
8
9
10
6
7
8
9
10
( 1-Q-<JI / L )
I
2
3
5
4
~·-
( 1-Q · at /L)
l
E -12·74
23 - 24/llll/74
200
300
6
SILIC ATE
N ITRAT E
200
5
E - 12 · 74
23 · 24/llll/74
200
100
10
PHOSP HATE
100
I
E - 12-74
23 -24/lllll74
( I'Q · Ol/ LJ
9
4
3
OXYGEN
100
8
SIGMA · T
l
E -12-74
23 · 24/llll/74
100
200
4
3
o1
200
0
7
I
SA LI NITY
100
6
E - 12 -74
23 · 24 / llll / 74
200
2
5
TEMPERATURE
(' C l
100
200
ol
4
3
"
SAMPLE POINTS
100
2
~. .......
,-.........
~·
~·,
'\
.
l,;~
I,.
Vertical Sections Cruise E-12-74s Section I
48
20 11l 16
17
1e
1!1
1<4
13 12
20 1g 1e
11
0
17
1e
0
5AMPlE P01NT5
Jr
100
11
TEMPERATU RE
( • CJ
100
E - 12 - 7<4
24 - 2!1 1lZII 174
1!1
n
E -12 -74
24 - 2!1 / lZII / 74
200
no
300
300
400
400
17
SIGMA -T
100
n
E-12 -14
24 -2!1 / lZII /7<4
200
300
1!1
100
14
13 12
11
11
PHOSPHATE
OXYGEN
! m ilL J
1()()
n
E - 12 - 74
I>Q-<>t / L )
n
E - 12 -7<4
24 - 2!1/lZII / 7<4
24 - 2!1 / lZII /74
200
200
300
300
400
20 1Q 16
17
1e
1!1
0
,.
13 12
,
20 1Q 18
( ug -at /LJ
u
100
1!1
14
1) 12
( >Q-<11 /L)
n
E - 12 - 74
24 - 25/llll I 74
E -12 - 7<4
24 - 2!1/llll/74
200
200
300
300
4 00
400
Figure 28.
1e
SILICATE
NITRATE
1()()
17
0
Vertical Section, Cruise E-12-74, Section II
11
49
0
2 1 Z2 2 3
24
Z5
Z6
27
28 2Q
X)
31
3'
0
21 22 23
24
31
SAMPLE POINTS
m
100
100
E · 12 - 74
2 5 · 26 / llll /74
200
200
JOO
300
~ 00
4 00
0
21 22 23
).1 0
2..
l~
31
32
21 22
0
"
""'
SAL INITY
(' 1•• )
100
23
m
-
-----.
~¥
E -12-74
25·26/llll/74
200
3~\\
300
400
23
2!1
2<1
Z6
27
31
32
~~
SIGMA · T
m
100
28 2Q lO
~
- 200.... ~
E -12-74
25· 28J:llll174
~~
200
300
400
0
....
21 22 23
25
2<1
..!10
2e
27
28 2QX)
31
32
21 22 23
24
""
OXYGEN
(m ilL)
100
0
100
m
E -12 -74
2!1 · 28/llll/7..
200
200
300
_.-
21 22 23
·"
100
300
400
4 00
0
..... .
.
24
25
2e
)0
0
21 22 23
24
25
2e
27
28 2Q
X)
"'
NITRATE
(.,g-ot/U
m
100
m
E - 12 - 74
25 - 28/llll/74
E - 12 - 74
25- 28 / llll / 74
200
200
300
300
400
4 00
Figure 29.
SILIC ATE
(.,g-a t/L)
Vertical Section, Cruise E-12-74, Section III
31
32
50
43 42 4 1
40
3i
l8
37 )!5 35
or==:::::::::===~~-
33
s.t.MI'LE I'OINTS
Ill
1()()
200
)()()
300
400
400
-
4) 42 4 1
100
....
40
li
llr
E -12 - 74
28 -27J ll!l J7•
200
0
TEMPERATU RE
I " Cl
100
E · 12-74
2fl - 27 Jll!I J 74
38
~3 42 41
SI. LI NIT V
( •t. )
100
llr
E · 12 · 7•
2fl - 2 7J ll!I J74
200
200
)()()
)()()
400
400
311
40
33
l8
,..,--..._,_
2lD
SIGMA · T
.Ill:
E -12 -74
21! -27/Jlll /7•
....
043 42 41
40
38
0
43 42 41
( m ilL)
Ill
1()()
200
200
300
)()()
400
400
( i'Q · Ot /U
II[
SI LIC ATE
NITIIATE
lll
l8
E -12 ·"14
21! · 27 / llll /74
E -12 - 74
2fl - 27/lll!J74
( IJij •Otll)
l ll
PHOSPHATE
OXYGEN
1()()
40
..,
100
( ~Jg-<rt /Ll
llr
E · 12 -74
28 ·27 /llll /74
E -12 · 74
2fl · 27J ll!I J74
300
300
Figure 30.
Vertical Section, Cruise E-12-74, Section IV
51
47
044 45 46
48
411
50 5 1 52
54
53
044 45 4&
S.O.MPLE POINTS
c•c J
•oo
E -12 - 74
28 · 211 / lll! 174
ll
E-12-74
28 · 211/lll!/74
200
200
300
300
400
.oOOO
47
47
"
S.O.LINlTY
( •1- )
100
48
TEM PER.O.TURE
ll
•oo
47
SlGM.O. -T
100
ll:
ll
E - 12-114
27 - 211 / lll! /74
E -12-74
28 ·2Gi lZI! I74
200
200
300
300
400
o••
45
..e
""'
100
47
4e
50 51 52
....
....
53
54
"""
~i
lr
E -12- 74
26 - 2G i lZI! I74
200
..«,"-...._
300
<ll>J ~
.oOOO
0
44 45 4e
45
47
50 51 52
53
54
.20 ·"'
PHOSPH.O.TE
(>Q-<It ll)
100
lr
E-12-74
26 - 211 / lZI!/74
200
300
.oOOO
47
4e
411
50 51 52
53
54
0
44 45 4&
~ID
NITRATE
100
..e
. ]()
-~~
OXYGEN
( m ill)
o••
<,g:;t ll)
100
48
47
200
200
300
300
400
400
( ~-G-at ll)
:sr
""~t
~
\ ...a
Figure 31.
54
"'"'SlLICATE
E -12 - 74
28 - 2G i lll! 174
E -12-74
28 - 2G i lZI! /74
53
1D
.0
Vertical Section, Cruise E-12-74, Section
..:~
v
52
8-4
63
0
61
62
60
51158
57 56
55
64
0 -
63
62
SAM PLE POINTS
lli
100
200
300
300
400
400
8-4
..,
63
61
62
eo
:11158
!57 5 6
5:1
~
0 ~
~
~JOO~'\
SALINITY
( •J•• )
100
lll
E -12 - 74
29 - 30/ llll / 74
200
0
61
TE MPERATURE
( • C)
100
E -12 - 74
211 - 30/ l!IJ /74
,.
lli
E-12 - 74
211 - 30 / l!IJ /74
,A
200
~
,
63
61
62
eo
!50
SIGMA - T
100
lli
E-12 -J-4
211 - 30 / l!IJ /74
200
.~,
300
300
400
400
8-4
0
63
:17 :16
:1:1
8-4
0
63
62
61
:11158
57 5 6
:15
.>0
OXYGEN
PHOSPHATE
( m i/L)
100
<..o-at iL)
100
lli
E -12 -74
211 - 30/ l!IJ /74
lli
E- 12 -74
211 - 30/ l!IJ /74
200
200
300
300
lOO
400
400
>JDO \
8-4
0
.
63
61
62
eo
55
64
0
( .-Q-<>t /L)
100
ll1
200
;:oo
300
300
,. I,,.
Figure 32.
61
eo
:11158
:1:1
(.,g-at/L )
lZI
E - 12 -74
211 -30/ l!IJ /74
E -12- J-4
211 - 30 /l!IJ /74
400
62
SILIC ATE
NITRATE
100
63
4()()
Vertical Section, Cruise E-12-74, Section VI
'"'
53
..
,.
- I
I
,.
I
,.
Freshwater Volume
m 3 H20/ m 2
.. .
E - 13-73
4 11/IX/73
~le
0
,_,.
Freshwater Volume
...
m 3 ~-i:!Oim 2
E -19-73
8 19/Xll/73
...
1n k:Jim£l.e;rs
50
100
,..
..
,
,.
~~~~--- -
,..
1· ·.
;'
/
I· ..
Freshwater Volume
m3 ~-i:!O im 2
E-3-74
23-30/N/74
Figure 33 .
...
...
Distribution of Freshwater
Freshwate-r Volu me
m3Hpirr?
E-12- 74
23-30/:Z:::/74
54
,,.
4
f
.,.
Dr1ft Bottle Return
E-13-73
4 - 11/IX/73
~nmdQy - 1
10
20 km ooy-1
~
0
50
100
30°
,..
,,.
5
...
i
,,.
Dr ift Bottle Return
E - 3-74
23-30/ ISl/74
~nmooy · 1
10
Figure 34.
20 km day-1
Drift Bottle Trajectories
...
Dnft Bottle Return
E -12 -74
23- 30/W/74
~nmooy·1
10
20km day 1
55
17
AOU
AOU
100
16
[
100
£ · 13 73
n
E-13-73
6-71 IX173
I IX173
200
200
300
300
400
0
21
22 23
24
25
26
27
28 2Q 30
AOU
100
m
E -13-73
7-8/IX/73
_ . ,_
-·- - - -.:10 -
043 42 .1
--~~~:\
·"\""\
300
)()()
··)
400
40
39
38
37 36 35
34
AOU
100
-- ~
200
100
31
Ill
E -1 3 -73
8 -9 / IX/73
200
300
400
AOU
ll
E -13 -73
9 -101 1XI73
200
NO DATA
300
400
Figure 35.
Apparent Oxygen Utilization, Cruise E-13-73
33
56
AOU
100
NO DATA
II
E - 19 -73
11- 12/ Xll /73
200
JOO
400
21
0
22 23
24
25
26
27
31
32
\~
AOU
100
28 29 30
m
E - 19 -7 3
12-13/Xll /7 3
200
NO DATA
200
50'
3,;;--
JOO
'
400
AOU
100
:lZI
E-19 -73
14 -15/ Xll/ 73
NO DATA
200
JOO
400
Figure 36.
Apparent Oxygen Utilization, Cruise E-19-73
57
A OU
AOU
100
J
100
E - 3 -74
24 - 25/I!Z /74
200
200
300
300
n
E-3 -74
25 · 261.1l1:174
400
24
02 1 22 23
25
27
26
31
32
-~50-
AOU
100
26 29 30
m
E · 3 ·74
26·271 lll/74
100 ~
0~
200
300
400
043 4 2 4 1
40
3Q
37 38 35
38
33
34
AOU
100
.IlL
E-3 ·74
27-28/ .llL /74
200
300
·3~
1250
400
\
47
0 44 4 5 4 6
48
49
50 51 5 2
53
54
o64_
63
62
NO OATA
lr
100
E · 3· 74
28 -29/I!Z/74
200
200
300
300
400
<400
Figure 37.
60
59 58 57
56
NO DATA
......
AOU
100
61
AOU
Jll
E · 3 -74
29/I!Z"/74
Apparent Oxygen Utilization, Cruise E-3-74
55
58
2
4
]
5
6
7
8
9
10
0
20 t9 t8
17
te
,
t5
AOU
tOO
tOO
n
E - 12-74
24 -25/:llll/74
200
]()()
300
400
400
2t
0
24
22 23
25
27
26
2930
]I
32
__
~00
-_,...,
AOU
t OO
28
m
E-12 -74
25 -26/'!ZII/74
----~~
200
- 2~~
04 3 4 2 41
40
39
38
37
36 35
34
AOU
tOO
llZ
E -12-74
26 - 27/'!ZII/74
200
- -9()0 --
300
300
400
4()()
47
48
AOU
tOO
ll
E-t2 -74
26 - 29/'!ZII/74
49
50 51 52
_
53
,oo ---
--
~2-~200
200
250200
tOO
AOU
1lJ
£ -12 -74
29-JOflll/74
200
>..a
)
300
300
400
J..a
/
Figure 38.
Apparent Oxygen Utilization, Cruise E-12-74
33
59
0
100
200
1
2
5
3
6
7
8
9
10
J?:
0
16
11
OXYGEN ANOMALY
OXYGEN ANOMALY
I
E- 13 -73
51 !X I73
•
17
19 18
100
5-10
a 10
n
E -13-73
6-7/"JX /7 3
200
~
><>· ~
3CXl
3CXl
4()()
400
26
27
28 2!1 30
31
O F==========~~~
~'F3~4~2~4=1===·=o====3=9======3=8====~3~7~3r6~35~~3r•--_,33~
OXYGEN ANOMA LY
100
m
100
E -13 -73
7-8/IX/73
200
200
3CXl
3CXl
4()()
400
OXYGEN ANOMALY
l:l!:
E -13-73
8 -9/IX/73
OXYGEN ANOMALY
100
Jl:
E-13-73
9 -10 /IX /7 3
200
NO DATA
3CXl
Figure 39 .
Oxygen Anomaly (ml
o2;L),
Cruise E-13-73.
60
~
? ?
\
0
6
7
8
10
9
0
NO DATA
()X YGEN ANOM ALY
100
E-19-73
IOIXII/7)
D
•
200'
16
17
OXYGEN ANOMALY
I
100
?0 19 18
5-10
l
0
0
E 19-73
1-12/XII/73
200
!.10
'Lf~ .....
XlO
=l
0
4()()
24
22 23
?
25
27
26
28 29 30
31
32
39
38
37 36 35
OXYGEN ANOMALY
OXYGEN ANOMALY
10
100[
40
043 42 41
100
E-19-73
12-13/XII /73
I
200
200
300'
XlO
Ill
E-19-73
14-16/Xll/73
400
L
ol•l
4 5 46
47
48
49
50 5
52
53
54
054
63
51
62
01
nr
OXYGEN ANOMALY
v
E 19 73
14 16fXIl173
OXYGEN ANOMALY
100
:'\'(1 ·
200
\
)()()
lZI
E-19-73
14-151XDI73
\
I
\
\
I
\
4()()
Figure 40.
Oxygen Anomaly (ml
I
I
o2;L),
Cruise E-19-73.
34
33
61
OXYGEN ANOMALY
OXYGEN ANOMALY
100
200
I
E - 3 -74
2 4 - 25/ nll 74
0
•
,
13 12
17
100
5 - 1.0
~ 1.0
D
E-3-7-4
25-26/!'ZI 74
200
300
300
400
24
39
m
100
E - 3-74
26 - 27 / l"Z/ 74
200
200
300
300
400
400
0 44 4 5 46
47
50 51 52
rrz
E-3-74
27-28/lll/74
53
NO DATA
NO DATA
OXYGEN AN()fi.4ALY
OXYGEN ANOMALY
100
:1(
E-3-74
28-29/l"Z/74
37 36 35
OXYGEN ANOMALY
OXYGEN ANOMALY
100
38
100
200
200
300
300
lli:
E-3 - 74
2fJ ll"Z/74
400
Figure 41.
Oxygen Anomaly (ml
o2;L),
Cruise E- 3-74.
33
62
17
020 19 18
OXYGEN ANOMALY
O XYGEN ANOMALY
100
100
l
E - 12-74
23-24 IW/74
200
0
•
5 - 10
200
300
400
400
21
4
24
22 23
0
OXYGEN ANOMALY
OXYGEN ANOMALY
100
m
100
E - 12-74
25 26/llll/74
200
200
300
300
400
400
47
48
49
nz:
E-12-74
28-271:llii /74
57 56
064
OXYGEN ANOMALY
OXYGEN ANOMALY
100
0
E-12-74
24 -25/W/74
2 10
300
0
n
100
ll
E-12-74
26-29/llll/74
Jll
E-12-74
29 -30/llll/74
200
300
300
400
Figure 42.
Oxygen Anomaly (ml 02/L), Cruise E-12-74.
63
320
Runoff
3
Intrusions
, S.£1ille..j,Q. kUiJD1f..er,L
0
Figure 43.
50
100
Summarized Horizontal Extent of Runoff and Intrusions E-13-73
64
0
COOPER
II Runoff
II
Intrusions
s.;.s Ie..j,g. k UiJn a,t.e r,L
0
Figure 44.
50
100
Summarized Horizontal Extent of Runoff and Intrusions E-19-73
65
COOPER
RIVER
320
-
II
Runoff
Intrusions
5£2 le..!Ll. kj.li.m W r;....
0
Figure 45.
50
100
Summarized Horizontal Extent of Runoff and Intrusions .E-3-74
66
COOPER
RIVER
•
Runoff
•
Intrusions
s.ssteJc. kUi.m£J.erl.
0
Figure 46.
50
100
Summarized Horizontal Extent of Runoff and Intrusions E-12-74
67
)~
:-- -- ---·------------------------ ----·---------·------ ------------··
I
U
·---------·-----------------------------------------------·---------··
.
H
H
h
"
l~
U
~
l '
.,
. . ........
"
..
-
"
December 1973
E-19-7 3
September 1973
E-13-73
. --------- ;~ -------- !~- ------- ~ ~ -------- ~~--- --- . :~ -------- ~ - - ------..
l~
l1
•
0
...
•
0
0
••
••
•
-
"
..
April 1974
E-3-74
July 1974
E-12-74
Figure 47.
J -4
•
----- ·--- ·----------- ------ ·- ------·----- ---- ·--------- ----------··
-
Temperature-Salinity Plot
•
0
•
-
68
~ August~eJuly
J
Sept•
~une
25
/ay
Q)
"-
:::J
0
~
Aprile
20
\
Q.
E
~
Oct
Mar,__
15
31
~
i
Nov
Feb._ Jon
32
+-•
33
34
ec
35
Salinity
Figure 48.
Schematic Seasonal T-S Plot
36
69
3S.l2!
·. ·.
312l.l2l
1'\
I:
.:.· :
.......
..
2S.l2!
::l.
.
v
w
t-
It
2121.{2!
....
.
....·.•.
t-
IS.l2!
"''
. ·:.·
0:
z
.. ...
......
. ...,.
....,......
.·.:··.. ..
··...,... .'
.
•• .:..;t•• •
~
1121.121
''\
... .
.-··"'
S.t21
U1
U1
N
PHOSPHATEC)JM)
Figure 49.
Phosphate-Nitrate Plot
70
3121
..
. . .·~ .·
A2S:
.. .
"l:
:l..
v
~121
41
..
t-
It
..
[t
t-
IS:
z
..
..
~
·'
'· . .
. ,.,
..
•• > '• I
1121
. . . . .·....
. ... .
....
..
. ,. ' .. .·
• f •
s:
... . . ,..', ...· ..
. ~ .-~· .
·::~·-~ . .:
,•
•
•
I
N
:r
AOUCML/L)
Figure 50.
Nitrate-Apparent Oxygen Utilization Plot
71
3121
.,
.··
. : .. .
:
.. . . .
~
::2121
1"\
I:
:(
v
w
IS:
1-
a:
ll
1-
z
. ..
.........
. •·.
....
.. .,.'\......
.. .
..• . .....,...... ·.
' ..., .
•I I. • •
.. ...
......
...·
.~.
1121
··.)
~
lit
N
TEMPCC)
Figure 51.
Nitrate-Temperature Plot