Controls on Suspended Particle Properties and Water Clarity along
a Partially-Mixed Estuary, York River Estuary, Virginia
Kelsey A. Fall1, Carl T. Friedrichs1, Grace M. Cartwright1, and David G. Bowers2
1Virginia Institute of Marine Science
2School of Ocean Sciences, Bangor University
Motivation: Water clarity a major water quality issue in the Chesapeake Bay. Despite
decreases in sediment input water clarity has continued to deteriorate (especially in the
Lower (i.e., Southern) Chesapeake Bay).
Percent of Secchi Depths which passed USA
Environmental Protection Agency (EPA )water
clarity thresholds (Williams et al., 2010)
good
poor
good
poor
1/10
Motivation: Water clarity a major water quality issue in the Chesapeake Bay. Despite
decreases in sediment input water clarity has continued to deteriorate (especially in the
Lower (i.e., Southern) Chesapeake Bay).
Percent of Secchi Depths which passed USA
Environmental Protection Agency (EPA )water
clarity thresholds (Williams et al., 2010)
good
Annual means of the dimensionless product of Secchi Depth times
the diffuse light attenuation coefficient (ZSDKd) for upper, middle
and lower Bay (Gallegos et al.,2011).
poor
good
poor
Gallegos et al. (2011) suggested that the most
likely explanation for the change in the product
of ZSD times Kd is an increase in the
concentration of continually suspended, small
particles of non-algal organic matter.
1/10
Objective: Investigate the influence of suspended particle properties (size, concentration,
composition) on inherent and apparent optical properties in a partially-mixed estuary.
Study Site: York River Estuary, VA, U.S.A
• Partially mixed, microtidal estuary located adjacent to the
lower Chesapeake Bay.
• Although the York is microtidal, tidal currents dominate
suspension and peak spring surface currents can reach ~1
m/s.
Latitude
West Point
• Depths along axis of the main channel decrease from about
20 m near the mouth to about 6 m near West Point.
YORK
RIVER
CHESEAPEAKE
BAY
VIMS
• The channel bed is mostly mud, and Total Suspended Solids
(TSS) increases up estuary to the primary ETM located near
West Point.
This study: Utilized observations of 7 water column profiling
cruises at different stations along the York (3 in June 2013
and 4 in Sept. 2014).
Longitude
Average Total Suspended Solids (TSS)
Average Salinity
30
30
100
10
0
10
20
30
40
50
Distance from the Mouth (km)
60
70
Salinity PSU
Surface
Bottom
Salinity (ppt)
TSS mgL-1
1,000
Surface
Bottom
20
20
10
10
0
0
00
10
10
20
30
30
40
40
50
50
Distance
the Mouth
Distance from
the from
Mouth
(km)
60
60
70
70
2/10
Coastal Hydrodynamics and Sediment Dynamics (CHSD) Water Column Profiler
Deployed off vessel at various depths for along channel surveys.
•
Pump sampler
• Water samples analyzed for total suspended solids (TSS) and
organic content
•
CTD with a turbidity sensor
• water clarity proxy
•
Laser In-Situ Scattering and Transmissometry (LISST-100X)
• Suspended particle size distribution (~2.5-500 μm)
• Optical Transmission
•
Particle imaging camera system (PICS) –Added 2012
• particle sizes, density, and settling velocities (~30 μm- 1000 μm)
•
Acoustic Doppler Velocimeter (ADV)
• provide estimates of:
• mass concentration of suspended particle matter
• Bottom: turbulence/bed stress, bulk settling velocity
•
Radiometer (Summer 2013) or LI-COR light sensor (new 2014)
• Vertical profile of diffuse light attenuation (Kd)
CHSD Profiler
Pump
Sampler
ADVs
PICs
LISST
CTD
(Smith and Friedrichs, 2014, 2010; Cartwright et al., 2013; 2009; Fugate and Friedrichs, 2002).
3/10
Characterization of Particle Area with the LISST (2.5-500 μm) and PICS (30-1000μm)
Particle surface area important property to consider, because it is the area that is effective in blocking light.
Used LISST and PICs to determine particle area concentration per size class (i) [Ai]:
Particle area concentration
(per Liter) for size class (i):
Ai ( cmL
2
Vi ( mLL )
)=
*10-3
SizeClassi (cm)
Area Concentration Distributions [Ai]
5420 Area Distributions
Example from
surface water
September 2014:
1
0.9
0.9
0.8
0.8
0.7
0.7
Volume Conc (mL/L)
LISST
PICS
5420Vol Distribution
1
Ai cm2/L
Area (cm2/L)
0.6
0.5
0.4
0.6
Note: Area peaks at ~3 at
lowest size class. Figure
adjusted to see larger
0.4
grain sizes better.
0.5
0.3
0.3
0.2
0.2
0.1
0.1
0
(Neukermans et al., 2014; Smith and Friedrichs, 2010)
10
100
Grainsize mm
Particle Size μm
1000
0
10
100
Grainsize mm
1000
4/10
Characterization of Particle Area with the LISST (2.5-500 μm) and PICS (30-1000μm)
Combine PICS and LISST to create new volume and area distributions from 2.5-1000 μm where:
• 2.5-60 μm: LISST
• 60-200 μm: Linearly weighted average of LISST and PICS
• 200-1000 μm: PICS
Area Concentration Distributions [Ai]
5420 Area Distributions
LISST
PICS
1
0.9
0.9
LISST
AVG
PICS
0.8
0.8
0.7
0.7
Volume Conc (mL/L)
Example from
September 2014:
5420Vol Distribution
1
Ai cm2/L
Area (cm2/L)
0.6
0.5
0.4
0.6
Note: Area peaks at ~3 at
lowest size class. Figure
adjusted to see larger
0.4
grain sizes better.
0.5
0.3
0.3
0.2
0.2
0.1
0.1
0
(Neukermans et al., 2014; Smith and Friedrichs, 2010)
10
100
Grainsize mm
Particle Size μm
1000
0
10
100
Grainsize mm
1000
4/10
Characterization of Particle Area with the LISST (2.5-500 μm) and PICS (30-1000μm)
Combine PICS and LISST to create new volume and area distributions from 2.5-1000 μm where:
• 2.5-60 μm: LISST
• 60-200 μm: Linearly weighted average of LISST and PICS
• 200-1000 μm: PICS
LISST range dominates particle area.
Area Concentration Distributions [Ai]
5420 Area Distributions
3
2.5
Example from
surface water
September 2014:
LISST
AVG
PICS
22
AArea
(cm/L
/L)
i cm
2
1.5
1
0.5
0
(Neukermans et al., 2014; Smith and Friedrichs, 2010)
10
100
Grainsize mm
Particle Size μm
1000
4/10
Characterization of Particle Area with the LISST (2.5-500 μm) and PICS (30-1000μm)
Combine PICS and LISST to create new volume and area distributions from 2.5-1000 μm where:
• 2.5-60 μm: LISST
• 60-200 μm: Linearly weighted average of LISST and PICS
• 200-1000 μm: PICS
LISST range dominates particle area. But PICS range contributes to volume concentration
Area Concentration Distributions [Ai]
3 1
0.9
2.5
Example from
surface water
September 2014:
Volume Concentration Distribution [Vi]
5420
Area
Distributions
5420
Area
Distributions
LISST
AVG
5420Vol Distribution
1
0.9
PICS
0.8
0.8
0.7
0.7
Microflocs
Macroflocs
Volume Conc (mL/L)
V μL/L
2
2
Area (cm /L)
22
AArea
(cm/L
/L)
i cm
0.6
1.50.5
0.4
Volume ≈
Area x Size
Small organics(?)
0.6
0.5
0.4
1
0.5
0.3
0.3
0.2
0.2
0.1
0.1
0 0
(Neukermans et al., 2014; Smith and Friedrichs, 2010)
10 10
100100
Grainsize
mm mm
Grainsize
Particle Size μm
1000
1000
0
10
100
Grainsize mm
Particle Size μm
1000
4/10
Characterization of Particle Area with the LISST (2.5-500 μm) and PICS (30-1000μm)
Define particle size characteristics with new distributions ( D50A, AT, D50V ):
• D50A : Median particle size based on area distribution.
• AT: Total area per liter (AT=Σai)
• D50V : Median particle size based on volume distribution.
Area Concentration Distributions [Ai]
Volume Concentration Distribution [Vi]
5420
Distributions
5420
AreaArea
Distributions
3
2.5
Example from
surface water
September 2014:
5420Vol Distribution
1
1
0.9
D50A=6.2 microns
0.9
0.8
AT=11.38 cm2/L
0.8
0.7
Volume ≈
Area x Size
0.7
Volume Conc (mL/L)
V μL/L
2
2
Area (cm /L)
22
AArea
(cm/L
/L)
i cm
0.6
1.5 0.5
0.4
D50v =24.4 microns
0.6
0.5
0.4
1
0.5
0
0.3
0.3
0.2
0.2
0.1
0.1
0
(Neukermans et al., 2014; Smith and Friedrichs, 2010)
10 10
100100
Grainsize
mm mm
Grainsize
Particle Size μm
1000
1000
0
10
100
Grainsize mm
Particle Size μm
1000
4/10
Inherent and Apparent Optical Properties of Surface Water
•
Measures C at 670 nm (+/- 0.1 nm)
(Boss, 2003; Kirk, 1994; Lund-Hansen et al., 2010; LISST-100 User’s Guide; Neukermans et al., 2014)
LISST Beam Attenuation Coefficient
Sept. 2014
June 2013
C m-1
1. Beam Attenuation Coefficient (C)
• Inherent: Depends only on medium, not
ambient light field
• Measured by LISST beam transmission (T):
1
C = -( )* ln(T )
z
where z is beam path length. LISST z=0.05 m.
Distance from the Mouth (km)
5/10
Inherent and Apparent Optical Properties of Surface Water
Measures C at 670 nm (+/- 0.1 nm)
2. Vertical Diffuse Light Attenuation Coefficient (Kd)
• Apparent: Depends on medium and
ambient light field
• Measured by either Radiometer or LICOR
downward irradiance (Ed) at two depths
(z1,z2):
Kd =
•
Sept. 2014
June 2013
1
E (z )
* ln d 1
z2 - z 1
Ed (z2 )
Measures PAR (400-700 nm)
(Boss, 2003; Kirk, 1994; Lund-Hansen et al., 2010; LISST-100 User’s Guide; Neukermans et al., 2014)
Distance from the Mouth (km)
Vertical Diffuse Light Attenuation Coefficient
Sept. 2014
June 2013
Kd m-1
•
LISST Beam Attenuation Coefficient
C m-1
1. Beam Attenuation Coefficient (C)
• Inherent: Depends only on medium, not
ambient light field
• Measured by LISST beam transmission (T):
1
C = -( )* ln(T )
z
where z is beam path length. LISST z=0.05 m.
Distance from the Mouth (km)
5/10
Inherent and Apparent Optical Properties of Surface Water
Similar Temporal and Spatial Variability:
Measures C at 670 nm (+/- 0.1 nm)
2. Vertical Diffuse Light Attenuation Coefficient (Kd)
• Apparent: Depends on medium and
ambient light field
• Measured by either Radiometer or LICOR
downward irradiance (Ed) at two depths
(z1,z2):
Kd =
•
Sept. 2014
June 2013
1
E (z )
* ln d 1
z2 - z 1
Ed (z2 )
Measures PAR (400-700 nm)
(Boss, 2003; Kirk, 1994; Lund-Hansen et al., 2010; LISST-100 User’s Guide; Neukermans et al., 2014)
Distance from the Mouth (km)
Vertical Diffuse Light Attenuation Coefficient
Sept. 2014
June 2013
Kd m-1
•
LISST Beam Attenuation Coefficient
C m-1
1. Beam Attenuation Coefficient (C)
• Inherent: Depends only on medium, not
ambient light field
• Measured by LISST beam transmission (T):
1
C = -( )* ln(T )
z
where z is beam path length. LISST z=0.05 m.
Distance from the Mouth (km)
5/10
Inherent and Apparent Optical Properties of Surface Water
1. Beam Attenuation Coefficient (C)
• Inherent: Depends only on medium, not
ambient light field
• Measured by LISST beam transmission (T):
1
C = -( )* ln(T )
z
where z is beam path length. LISST z=0.05 m.
Measures C at 670 nm (+/- 0.1 nm)
2. Vertical Diffuse Light Attenuation Coefficient (Kd)
• Apparent: Depends on medium and
ambient light field
• Measured by either Radiometer or LICOR
downward irradiance (Ed) at two depths
(z1,z2):
Kd =
•
Beam Attenuation versus Light Attenuation
r2=0.88
Kd m-1
•
Strong linear regression between C and Kd :
C m-1
1
E (z )
* ln d 1
z2 - z 1
Ed (z2 )
Measures PAR (400-700 nm)
(Boss, 2003; Kirk, 1994; Lund-Hansen et al., 2010; LISST-100 User’s Guide; Neukermans et al., 2014)
5/10
Preliminary Look at Controls on Optical Attenuation (C and Kd): Total Suspended Solids (TSS)
K d versus TSS
C versus TSS
5
4.5
4
C m-1
Kd m-1
3.5
3
2.5
2
1.5
1
0.5
0
0
20
40
TSS
(Lund-Hansen et al., 2010)
60
(mgL-1)
80
100
TSS (mgL-1)
6/10
Preliminary Look at Controls on Optical Attenuation (C and Kd): Total Suspended Solids (TSS)
K d versus TSS
C versus TSS
5
4.5
4
C m-1
Kd m-1
3.5
3
2.5
2
1.5
KdDISS ~0.22 m-1
1
KdDISS
CDISS ~2.8 m-1
0.5
0
0
CDISS
20
40
TSS
60
(mgL-1)
80
100
TSS (mgL-1)
Use intercept from linear fit for TSS < 40 mg/L to estimate attenuation
due to water and dissolved constituents (KdDISS and CDISS).
(Lund-Hansen et al., 2010)
6/10
Preliminary Look at Controls on Optical Attenuation (C and Kd): Total Suspended Solids (TSS)
K d versus TSS
C versus TSS
5
4.5
4
C m-1
Kd m-1
3.5
3
2.5
2
1.5
KdDISS ~0.22 m-1
1
KdDISS
CDISS ~2.8 m-1
0.5
0
0
CDISS
20
40
TSS
60
80
100
(mgL-1)
TSS (mgL-1)
Calculate light (KdP) and beam (Cp) attenuation due to particles:
1. KdP = Kd - KdDISS
2. Cp = C - CDISS
(Lund-Hansen et al., 2010)
6/10
Preliminary Look at Controls on Optical Attenuation (C and Kd): Total Suspended Solids (TSS)
K d versus TSS
C versus TSS
5
4.5
4
C m-1
Kd m-1
3.5
3
2.5
2
1.5
KdDISS ~0.22 m-1
1
KdDISS
CDISS ~2.8 m-1
0.5
CDISS
0
0
20
40
60
Remove KdDISS ~0.22
5
80
100
m-1
Remove CDISS ~2.8 m-1
CP versus TSS
KdP versus TSS
4.5
4
CP m-1
KdP m-1
3.5
3
2.5
2
1.5
1
0.5
0
0
10
20
(Lund-Hansen et al., 2010)
30
40
TSS
50
mgL-1
60
70
80
90
100
TSS mgL-1
6/10
Preliminary Look at Controls on Optical Properties (CP and KdP): Area vs TSS
CP versus TSS
KdP versus TSS
50
40
5
r2=0.67
4
30
CP m-1
3
KdP m-1
r2=0.78
2
20
10
1
10
5
TSS mgL-1
50
10
100
KdP versus AT
50
40
r2=0.87
4
50
100
CP versus AT
r2=0.97
30
CP m-1
3
KdP m-1
TSS mgL-1
2
20
10
1
10
AT
50
2/
cm L
100
150 200
10
AT
50
cm2/L
100
150 200
7/10
Preliminary Look at Controls on Optical Properties (CP and KdP): Area vs TSS
Attenuation explained better by AT than TSS. (Also Cp less noisy than Kdp)
CP versus TSS
KdP versus TSS
50
40
5
r2=0.67
4
30
CP m-1
3
KdP m-1
r2=0.78
2
20
10
1
10
5
TSS mgL-1
50
10
100
KdP versus AT
50
40
r2=0.87
4
50
100
CP versus AT
r2=0.97
30
CP m-1
3
KdP m-1
TSS mgL-1
2
20
10
1
10
AT
50
2/
cm L
100
150 200
10
AT
50
cm2/L
100
150 200
7/10
Preliminary Look at Controls on Optical Properties (CP and KdP): Relationship to Area
5
KdP versus AT
50
40
r2=0.87
4
r2=0.97
30
CP m-1
3
KdP m-1
CP versus AT
2
20
10
1
10
AT
50
2/
cm L
100
10
150 200
AT
50
cm2/L
100
150 200
Attenuation explained better by AT than TSS.
Others (e.g., Neukermans et al., 2014) suggest that attenuation due to particles (both diffuse light
and beam) become nearly constant when normalized by AT :
K dP
AT
≈ constant,
CP
AT
≈ constant
8/10
Preliminary Look at Controls on Optical Properties (CP and KdP): Relationship to Area
5
KdP versus AT
50
40
r2=0.87
4
r2=0.97
30
CP m-1
3
KdP m-1
CP versus AT
2
20
10
1
10
AT
50
2/
cm L
100
10
150 200
AT
50
cm2/L
100
150 200
Attenuation explained better by AT than TSS.
Others (e.g., Neukermans et al., 2014) suggest that attenuation due to particles (both diffuse light
and beam) become nearly constant when normalized by AT :
K dP
AT
≈ constant,
CP
AT
≈ constant
Does this hold for York estuary? What are causes of any observed variations?
(note that above plots are log-log, not linear)
Next step: Normalize Kdp and Cp by AT to see if it is independent of particle composition.
8/10
Preliminary Look at Controls on Optical Properties (CP and KdP): Relationship to Area
CP normalized by AT versus organic matter content
KdP normalized by AT versus organic matter content
0.1
0.6
0.08
CP /AT
KdP/AT
0.5
0.06
0.4
0.04
0.3
0.02
0
0.1
0.2
0.3
0.4
0.2
0.1
0.5
Fraction Organic Content
0.2
0.3
0.4
Fraction Organic Content
0.5
Others (e.g., Neukermans et al., 2014) suggest that attenuation due to particles (both light and
beam) become nearly constant when normalized by AT :
K dP
AT
≈ constant,
CP
AT
≈ constant
Does this hold for York estuary? What are causes of any observed variations?
(now the above plots are linear)
No, our measurements (erroneously?) do not show area-normalized attenuation to be constant.
8/10
Preliminary Look at Controls on Optical Properties (CP and KdP): Relationship to Area
CP normalized by AT versus organic matter content
KdP normalized by AT versus organic matter content
0.1
0.6
0.08
CP /AT
KdP/AT
0.5
0.06
0.4
0.04
0.3
0.02
0
0.1
0.2
0.3
0.4
0.2
0.1
0.5
Fraction Organic Content
0.2
0.3
0.4
Fraction Organic Content
0.5
Others (e.g., Neukermans et al., 2014) suggest that attenuation due to particles (both light and
beam) become nearly constant when normalized by AT :
K dP
AT
≈ constant,
CP
AT
≈ constant
We need to consider instrument limitations, smallest particle measured by the LISST is 2.5 μm, while filters
used to measure organic content capture grains down to 0.7 μm.
Our LISST is NOT able to adequately include the smallest particles which could contribute a significant
portion of AT.
8/10
Preliminary Look at Controls on Optical Properties(CP and KdP): Relationship to Area
Simple Solution: Use iterative approach to estimate the particle area not captured by the LISST
(ATsp for sizes 0.7-2.5 microns) needed to make both Kdp/(AT+ATsp) and Cp/(AT+ATsp) nearly
constant.
Iterations suggest ATsp≈ 20 cm2/L
CP normalized by AT versus organic matter content
KdP normalized by AT versus organic matter content
0.1
0.6
0.08
☐ Without ATsp
CP/AT and CP/AT+ATsp
KdP/AT and KdP/AT+ATsp
Δ With Atsp
0.06
0.04
0.02
0
0.1
0.2
0.3
0.4
Fraction Organic Content
0.5
0.5
0.4
0.3
0.2
0.1
0
0.1
0.2
0.3
0.4
0.5
Fraction Organic Content
The addition of the Atsp shows area-normalized attenuation to be nearly constant.
8/10
Preliminary Look at Controls on Optical Properties(CP and KdP): Relationship to Area
Simple Solution: Use iterative approach to estimate the particle area not captured by the LISST
(ATsp for sizes 0.7-2.5 microns) needed to make both Kdp/(AT+ATsp) and Cp/(AT+ATsp) nearly
constant.
Iterations suggest ATsp≈ 20 cm2/L
CP normalized by AT versus organic matter content
KdP normalized by AT versus organic matter content
0.1
0.6
0.08
☐ Without ATsp
CP/AT and CP/AT+ATsp
KdP/AT and KdP/AT+ATsp
Δ With Atsp
0.06
0.04
0.02
0
0.1
0.2
0.3
0.4
Fraction Organic Content
0.5
0.5
0.4
0.3
0.2
0.1
0
0.1
0.2
0.3
0.4
0.5
Fraction Organic Content
The addition of the Atsp shows area-normalized attenuation to be nearly constant.
Now adjust D50A calculation to account for additional ATsp. by evenly distributing ATsp among
new additional sizes classes (0.7-2.5 microns).
8/10
Preliminary Look at the Relationship Between Particle Size and Composition (Organic Content):
D50A has a stronger, more significant negative correlation to organic matter content (i.e. smaller
particles are more organic). D50V does not show this trend.
r2=0.23
p=0.005
r2=0.16
p=0.01
r2=0.0023
p=0.80
0.5
Δ Adjusted D50A
 Unadjusted D50A
☐ D50V
0.4
Fraction Organic Content
0.3
0.2
0.1
10
100
1,000
D50 in Log Space
0.5
Δ Adjusted D50A
 Unadjusted D50A
0.4
0.3
0.2
0.1
2
5
D50A in Log Space
10
10
20
9/10
Preliminary Look at the Relationship Between Particle Size and Composition (Organic Content):
The most relevant D50 for attenuation light (i.e. medium size by area) is much smaller than the
“classic” D50 by volume. D50A for surface waters is 10 to 20 times smaller than D50v.
r2=0.23
p=0.005
r2=0.16
p=0.01
r2=0.0023
p=0.80
0.5
Δ Adjusted D50A
 Unadjusted D50A
☐ D50V
0.4
Fraction Organic Content
0.3
0.2
0.1
10
100
1,000
D50 in Log Space
0.5
Δ Adjusted D50A
 Unadjusted D50A
0.4
0.3
0.2
0.1
2
5
D50 in Log Space
10
10
20
9/10
Conclusions:
• Strong linear regression between Beam Attenuation Coefficient (C) and Vertical Diffuse
Attenuation Coefficient (Kd), which allows (C) to be a proxy of Kd (surface water clarity
for photosynthesis) when Kd values are not available.
• After removing effects of water and dissolved materials, both Particle Beam Attenuation
Coefficient (Cp) and Particles Diffuse Attenuation Coefficient (KdP) are better explained by
total particle area concentration (AT) than total suspended solids (TSS).
• There is a contribution of area of smaller particles that cannot be detected by the
current LISST (ATsp~0.7 - 2.5 microns ) that needs to be accounted for when looking at
total total particle area concentration (AT + ATsp) as well as D50A .
• Preliminary results from the York indicate importance of these small, more organic
particles on optical properties. The medium particle size for attenuating light in surface
waters is 10 to 20 times smaller than the classic D50 by volume.
• Future work will include (i) many more sampling cruises and (hopefully) (ii) deployment
of a LISST that can detect smaller particle sizes.
10/10
Questions?
Acknowledgements
Marjy Friedrichs
Tim Gass
Wayne Reisner
Ken Moore
Jarrell Smith
Steve Synder
Erin Shields
Funding:
11/11
1
0.8
Cp/TSS
1
Δ New Area
 Area
☐Volume
0.8
0.6
0.6
0.4
0.4
0.2
1
10
100
Δ New Area
 Area
1,000
0.2
1
10
Fraction Organic Content
D50 in Log-space
0.5
0.5
0.4
0.4
0.3
0.3
0.2
0.2
0.1
0.1
1
10
D50 in Log-space
100
1,000
1
10
Fraction Organic Content
0.5
Δ New Area
 Area
0.4
0.3
0.2
0.1
0
2
4
6
8
10
12
14
16
18
D50_A microns
Cp/TSS
1
0.8
0.6
0.4
0.2
0
5
10
D50_A microns
15
20
Fraction Organic Content
0.5
☐Volume
0.4
0.3
0.2
0.1
0
50
100
150
200
250
300
350
250
300
350
D50_V microns
1
D50_V microns
Cp/TSS
0.8
0.6
0.4
0.2
0
50
100
150
200
D50_V microns
Preliminary Look at Controls on Optical Properties (CP and KdP): Composition and Size
Kdp and Cp per unit mass  OM and D50A
A. KdP per unit mass versus fraction organic matter
B. CP per unit mass versus fraction organic matter
0.14
1
0.12
0.8
CP/TSS
KdP/TSS
0.1
0.08
0.6
0.06
0.04
0.4
0.02
0
0.1
0.2
0.3
0.4
0.2
0.1
0.5
Fraction Organic Matter
0.14
C. KdP per unit mass versus D50A
1
0.2
0.3
0.4
0.5
Fraction Organic Matter
D. CP per unit mass versus D50A
0.12
0.8
CP/TSS
KdP/TSS
0.1
0.08
0.6
0.06
0.04
0.4
0.02
0
3
4
5
6
7
D50A μm
8
9
10
11
0.2
3
4
5
6
7
8
D50A μm
9
10
11
9/10
Preliminary Look at Controls on Optical Properties (CP and KdP): Composition and Size
Smaller/more organic particles attenuate more light per unit mass than larger particles.
A. KdP per unit mass versus fraction organic matter
B. CP per unit mass versus fraction organic matter
0.14
1
0.12
0.8
CP/TSS
KdP/TSS
0.1
0.08
0.6
0.06
0.04
0.4
0.02
0
0.1
0.2
0.3
0.4
0.2
0.1
0.5
Fraction Organic Matter
0.14
C. KdP per unit mass versus D50A
1
0.2
0.3
0.4
0.5
Fraction Organic Matter
D. CP per unit mass versus D50A
0.12
0.8
CP/TSS
KdP/TSS
0.1
0.08
0.6
0.06
0.04
0.4
0.02
0
3
4
5
6
7
D50A μm
8
9
10
11
0.2
3
4
5
6
7
8
D50A μm
9
10
11
9/10
Preliminary Look at Controls on Optical Properties (CP and KdP): Relationship to Area
Attenuation explained better by AT than TSS.
Others (e.g., Neukermans et al., 2014) suggest that attenuation due to particles (both light and
beam) become constant when normalized by AT :
K dP
AT
5
= constant,
CP
AT
D. CP versus AT
C. KdP versus AT
50
r2=0.87
4
40
r2=0.97
30
CP m-1
3
KdP m-1
= constant
2
20
10
1
10
50
AT cm2/L
100
150 200
10
50
100
150 200
AT cm2/L
8/10
Preliminary Look at Controls on Optical Properties (CP and KdP): Relationship to Area
Attenuation explained better by AT than TSS.
Our results (and others, i.e. Neukermans et al., 2014) suggest that attenuation due to particles (both
light and beam) become constant when normalized by AT :
K dP
AT
= constant,
CP
AT
= constant
Does this hold true? What are causes of any observed variations?
5
D. CP versus AT
C. KdP versus AT
50
r2=0.87
4
40
30
CP m-1
3
KdP m-1
r2=0.97
2
20
10
1
10
50
AT cm2/L
100
150 200
10
50
100
150 200
AT cm2/L
8/10
Investigate deviations ?
Why not constant.
K Particle/TSS (attenuation per unit area) vs organic matter
Kd Particle/A (attenuation per unit area) vs D50 of area distribution
0.1
0.09
0.09
0.08
0.08
0.07
0.07
0.06
0.06
0.05
d
K /A
dP
K /A
d
0.1
0.04
0.04
0.03
0.03
0.02
0.02
0.01
0
0
0.05
0.01
0.05
0.1
0.15
0.2
0.25
Vss/TSS
0.3
0.35
0.4
0.45
0.5
0
3
4
5
6
7
8
D50 Area (microns)
9
10
11
We expect Kd/A (light attenuation normalized by area) to be constant. Why isn’t it?
Are we underestimating area? Recall LISST range: 2.5-500 mircons, and PICS 30-1000 microns.
Big sizes-not too worried about- we are in the top of the water column during slack, however
are we missing smaller, organic particles.
10-15-14- Use iterations to estimate the area that would not be captured by the LISST
(Asp~0.7=2.5 microns ). Found A of about ~20 cm^2/L was missing.
LICOR KD per AREA vs D50A
LISST Attenuationper AREA versus D50A
Kd Particle/A (attenuation per unit area) vs D50 of area distribution
0.1
A
=20cm2/L
sm
0.09
No Asm
0.08
0.07
KdP/A
0.06
0.05
0.04
0.03
0.02
0.01
0
3
4
5
6
7
8
D50 Area (microns)
9
10
11
Adjusting with estimated ASP shows the expected relationship for both, ie. KDP /A=Constant
and 1-Ltrans/A=Constant. LISST attenuation is less noisy than Kd .
10-15-14
LICOR KD per MASS vs D50 area
LISST Transmission per MASS vs D50 Area
Light Attenuation per unit mass vs D 50 Area
0.14
r2=0.23
0.12
KdP/TSS
0.1
0.08
0.06
0.04
0.02
0
3
4
5
6
7
8
D50 Area microns
9
10
11
Kd and LISST optical attenuation per unit mass both increase with more smaller particles.
Relationship between LISST trans less noisy.
Smaller particles attenuate more light per unit mass than larger particles.
10-15-14
LICOR KD per MASS vs Organic Matter
LISST Transmission per MASS versus Organic Matter
Light attenuation per unit mass vs organic matter
0.14
2
r =0.003
0.12
KDP/TSS
0.1
0.08
0.06
0.04
0.02
0
0.1
0.15
0.2
0.25
0.3
VSS:TSS
0.35
0.4
0.45
0.5
Not a strong relationship between Kd and LISST optical attenuation per unit mass and
organic matter. Relationship between LISST trans less noisy.
Neglecting particle size, increase in organic matter increase attenuation.
Preliminary look at trends along the York River : June 2013 vs. September 2014
(Apparent and Inherent)
Kd m-1
Light
Attenuation:
Distance from the Mouth (km)
LISST Transmission good
proxy for Kd.
B. LISST Attenuation determined by LISST transmission
1-LTransmission
A. Light Attenuation measured by LICOR meter
Distance from the Mouth (km)
Preliminary look at trends along the York River : June 2013 vs. September 2014
(Apparent and Inherent)
Kd m-1
Light
Attenuation:
B. LISST Attenuation determined by LISST transmission
1-LTransmission
A. Light Attenuation measured by LICOR meter
C. Total Suspended
Solids
Surface
TSS Along Estuary
D. Percent Organic
Matter
Percent Organics Along Estuary
60
40
20
0
0
Suspended Particle
Properties:
10
20
30
40
Distance from the Mouth
50
60
Percent Organics
50
Percent Organic
TSS mg/L
TSS mgL-1
80
20
10
20
30
40
50
60
70
Distance from the Mouth
D
F. PICS D50 by mass of Surface
particles
from 30-1000 μm
50m
1.5
110
50m
D(microns)
50 μm
1
0.5
D
-1
W
mms
W s50
(mm/s)
s
m
30
10
0
70
E. PICS mean Ws of Surface
particles
Ws50mfrom 30-1000 μm
0
0
40
10
20
30
40
50
Mouth (km)
DistanceDistance
fromfrom
the
Mouth (km)
60
70
90
70
50
0
10
20
30
40
50
Mouth (km)
DistanceDistance
fromfromthe
Mouth (km)
60
70
r2=0.87
r2=0.67
Kd explained more by particle A than TSS.
New Area Versus Old Area
12
8
Recall: I just evenly distributed the area
out in the smaller class (0.7-2.5
microns). Take with caution.
6
4
D
50
Area Corrected microns
10
2
0
0
2
4
6
D50 Area microns
8
10
D50 of New Area Versus PICS D50 of mass
D50 Area Corrected microns
8
7
6
5
4
3
2
1
60
80
100
120
140
PICS D50 by mass microns
Recall: I just evenly distributed the area
out in the smaller class (0.7-2.5
microns). Take with caution.
160
Area not corrected
11
10
D50 Area (microns)
9
8
7
6
5
4
3
60
80
100
120
PICS D50 mass
140
160
Original
New Area
K Particle/A (attenuation per unit area) vs D50 of area distribution
K Particle/A
d
d
0.1
0.08
0.08
0.06
0.06
KdP/A
KdP/A new
0.1
0.04
(attenuation per unit adjusted area) vs D50 of area distributi o
0.04
0.02
0.02
0
2
4
6
8
10
12
New Area, New D50
K Particle/A
d
new
(attenuation per unit area) vs New D50 of area distribution
0.1
0.08
0.06
0.04
0.02
0
2
4
6
8
New D50 Area (microns)
0
2
4
6
8
D50 Area (microns)
D50 Area (microns)
KdP/A new
new
10
12
10
12
K Particle/A (attenuation per unit mass) vs D50 of area distribution
d
0.14
0.12
Are these more organic?
0.08
dP
K /TSS
0.1
0.06
0.04
0.02
0
1
2
3
4
5
6
7
8
New D50 Area (microns)
Smaller particles composition more important in influence attenuation per unit mass?
D50_new of area may be incorrect.
Characterization of Particle Properties with the LISST (2.5-500 μm) and PICS (30-1000μm)
Combine PICS and LISST observations to create a larger size spectrum from 2.5-1000 μm where:
•
•
•
2.5-60 μm: LISST Area (red)
60-200 μm: LISST and PICS (yellow)
280-1000 μm: PICS (blue)
Example: Sample Volume and Area Distribution form September 2014
5420Vol Distribution
5420 Area Distributions
1
LISSTLISST
PICSPICS
COMBINED
0.9
0.8
2/L
A cm
2
0.6
Area (cm /L)
Volume Conc (mL/L)
Volume μL/L
0.7
0.5
0.4
0.2
0.1
Grainsize mm
1000
0
1
0.9
0.9
0.8
0.8
0.7
0.7
0.6
0.5
0.4
0.3
100
5420Vol Distrib
1
Volume Conc (mL/L)
Area Distributions
10
100
Grainsize mm
1000
0.6
0.5
0.4
0.3
0.3
0.2
0.2
0.1
0.1
0
Grainsize μm
10
100
Grainsize mm
1000
0
10
1
Grainsize m
Characterization of Particle Properties with the LISST (2.5-500 μm) and PICS (30-1000μm)
Combine PICS and LISST observations to create a larger size spectrum from 2.5-1000 μm where:
•
•
•
2.5-60 μm: LISST Area (red)
60-200 μm: LISST and PICS (yellow)
280-1000 μm: PICS (blue)
Example: Sample Volume and Area Distribution form September 2014
5420Vol Distribution
5420 Area Distributions
1
LISSTLISST
PICSPICS
COMBINED
0.9
0.8
2/L
A cm
2
0.6
Area (cm /L)
Volume Conc (mL/L)
Volume μL/L
0.7
0.5
0.4
0.2
0.1
Grainsize mm
1000
0
1
0.9
0.9
0.8
0.8
0.7
0.7
0.6
0.5
0.4
0.3
100
5420Vol Distrib
1
Volume Conc (mL/L)
Area Distributions
10
100
Grainsize mm
1000
0.6
0.5
0.4
0.3
0.3
0.2
0.2
0.1
0.1
0
Grainsize μm
10
100
Grainsize mm
1000
0
10
1
Grainsize m