stream of where it enters ERF, and in Knik
Arm in the nearshore zone, about 200 m
north of the Eagle River mouth.
A suite of water characterization data was
collected at 4-minute intervals at each site.
Mortar
These data include salinity, pH, redox, dis-
Coast
solved oxygen, turbidity and water surface
Bread Truck
elevation (Table 6). Figure 18 shows the times
of data collection since 1993. Water samples
In-Between
were collected with an ISCO suction sam-
Parachute
pler automatically at various intervals be-
C Pond
B Gully
fore, during and following flood tides. The
sampler was programmed to obtain 500-mL
A Pond
Racine Pond
N
water samples at specific intervals through
the flood and ebb cycles. These samples were
Racine Gully
River
processed for TSS concentration using
Hydrolab & ISCO Water Sampler
P
vacuum techniques and 45-m glass micro-
Clankton Net
WD
T
fiber filters, generally following procedure
Wave & Tide Gauge
2540D in Standard Methods for the Examina-
I eather Station
tion of Water and Wastewater (APHA, AWWA,
SCO Water Sampler
WEF 1992). Modifications to this procedure
were described in Lawson et al. (1996).
0
500
1000 m
A MarshMcBirney electromagnetic flow
probe was used to measure current velocity
Figure 17. 1995 locations of instrumentation recording water
during ebb and flood in selected tidal gul-
quality parameters and water depths. Locations of weather
lies. A unit was also installed in C-Pond to
station and plankton net sampling sites are also shown.
Table 6. Specifications of sensors used in water quality parameter measurements.
Instrument type
Sensor
Accuracy
Resolution
0.15C
0.01C
Hydrolab
Temperature
0.2 units
(H2O Multiprobe)
pH
0.01 units
Specific conductance
0.0015 to 0.1 mS/cm*
Fresh water
0.001 mS/cm
0.15 to 1.0 mS/cm*
Salt water
0.01 mS/cm
0.2 ppt
Salinity
0.1 ppt
0.2 ppm
Dissolved Oxygen
0.01 ppm
20 mV
Redox
1 mV
0.45 m water
Depth
0.1 m water
0.02C
0.01C
CRREL thermistor
Temperature
0.008 m water
Druck (PDCR 950)
Pressure (water depth)
0.001 m water
100 mV
D&A OBS-3
Turbidity
1 mV
5 V = 2000 FTU
6.10 cm/s
Marsh-McBirney
Water current (velocity)
2.13 cm/s
(model 512)
1 cm
Campbell Ultrasonic
Distance (water depth)
0.05 cm
(model UDG01)
0.003 m water
Seabird Wave/Tide
Pressure (water depth)
0.0015 m water
0.02C
0.01C
(model SBE 26-03)
Temperature
0.75 m water
Seabird CTD
Pressure (water depth)
0.045 m water
0.01C
0.001C
(model SBE 16)
Temperature
0.001 S/m
0.0001 S/m
0.1 mL/L
Dissolved oxygen
0.01 mL/L
0.1 units
pH
100 mV
OBS [5 V=2000 FTU]
3 mV
* Depends on which of three auto-adjusting ranges is employed.
22
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