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Kayla Holleman
Variability of Submarine Groundwater Discharge in Honokohau Harbor, Hawaii
Kayla HollemanCraig Glenn
Henrieta Dulaiova
Submarine Groundwater Discharge (SGD)
Introduction Results ConclusionsMethods
SGD
Submarine Groundwater Discharge (SGD)
• SGD is the discharge of fluids of any composition
• SGD is a naturally occurring phenomenon
• SGD is temporally and spatially different
• Source of anthropogenic and naturally occurring nutrients
Introduction Results ConclusionsMethods
Conservative Tracers
Introduction Results ConclusionsMethods
• Discrete point source measurements• Salinity • Temperature
•Grab Samples • Specific Nutrients• Total Nutrients
Geochemical Tracers
Introduction Results ConclusionsMethods
Geochemical Tracers
Introduction Results Conclusions
• Collect water in cubies• Filter sample water
through manganese impregnated fibers
• Analyze fibers via RaDECC
• Apply 224Ra/223Ra to TW equation
Methods
Sample Coverage
A
A’
Vertical Profiles
Introduction Methods ConclusionsResults
A A’
0 5 10 15 20 25 30 3505
101520253035404550
Dissolved Nutrient Characteristics
Introduction Results Conclusions
0 5 10 15 20 25 30 350
1
2
3
4
5
6
7
8
0 5 10 15 20 25 30 350
50100150200250300350400450500
PO
43- (μ
M)
Si(
OH
) 4 (μM
)
NO
3- (μM
)
SalinitySalinity
Salinity
Methods
0 5 10 15 20 25 30 350
50
100
150
200
250
300
350
400
450
0 5 10 15 20 25 30 350
1
2
3
4
5
6
7
8
Dissolved Nutrient Characteristics
Introduction Results Conclusions
PO
43- (μ
M)
Si(
OH
) 4 (μM
)
NO
3- (μM
)
0 5 10 15 20 25 30 350
10
20
30
40
50
60
70
SalinitySalinity
Salinity
Methods
0 5 10 15 20 25 30 350
10
20
30
40
50
60
70
80
f(x) = − 1.81344858660512 x + 63.7362090488741R² = 0.98390576198514
0 5 10 15 20 25 30 350
100
200
300
400
500
600
700
800
900
f(x) = − 21.9978763295607 x + 773.176302828587R² = 0.993646159557476
0 5 10 15 20 25 30 350
1
2
3
4
5
6
7
8
f(x) = − 0.127091390665817 x + 4.68709201634845R² = 0.965409374473733
Dissolved Nutrient Characteristics
Introduction Results Conclusions
PO
43- (μ
M)
Si(
OH
) 4 (μM
)
NO
3- (μM
)
SalinitySalinity
Salinity
Methods
SGD Flux
Jun. 2010 Sept. 2010
Number 140 76
Rn (dpm/L) 19.2 15.9
Average Advection Plume (cm/d) 23 23
SGD Flux Plume (m3/d) 87.3 84.8
Average Advection (cm/d) 54 32
SGD Flux (m3/d) 202.3 118.5
0 5 10 15 20 25 30 35 400
50
100
150
200
250
300
350
400
Residence Time
Introduction Results Conclusions
223Ra (dpm/m3)
223Ra (dpm/m3)
224 R
a (d
pm/m
3 )
224 R
a (d
pm/m
3 )
0 10 20 30 40 50 60 70 800
100
200
300
400
500
600
700
800
Methods
0 5 10 15 20 25 30 35 400
50
100
150
200
250
300
350
400
f(x) = 4.6854171089841 xR² = 0.979887737541571
f(x) = 10.3146291200307 xR² = 0.983311378928376
Residence Time
Introduction Results Conclusions
223Ra (dpm/m3)
223Ra (dpm/m3)
224 R
a (d
pm/m
3 )
224 R
a (d
pm/m
3 )
0 10 20 30 40 50 60 70 800
100
200
300
400
500
600
700
800
f(x) = 10.3629751135003 xR² = 0.993304524013884
TwJUNE= <0.5 day
TwSEPTEMBER= 6.2-6.3 days
Methods
Conclusions
Introduction Results Conclusions
• The SGD flux within Honokohau Harbor plays a vital role in shaping the composition of the harbor water
• SGD in Honokohau Harbor occurs as a thin lens of brackish water floating on more dense salt water
• The nutrients within the harbor are enriched compared to the conservative mixing line demonstrated within the harbor
• The SGD flux experiences seasonal variability; thus, the residence time is seasonally variable
Methods
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