Ref. No. [UMCES]CBL 2013-015
ACT VS12-02
A summary of the physical and water quality conditions experienced over the duration of
the moored deployment are presented in Table 3. Water temperature ranged from 25.3 to 29.4
°C and salinity varied from 3.9 to 9.9. Chlorophyll and CDOM are quite high at this location
and can contribute significantly to the fluorescent properties of the ambient seawater.
Table 3.
Ancillary physical and water quality conditions for the moored field deployment test conducted
in Winans Cove, Baltimore Harbor, Baltimore, MD.
Site
Temperature
(
o
C)
Salinity
Chlorophyll
(µg/L)
CDOM
A
400
, m
-1
Turbidity
(NTU)
Baltimore
Harbor
Min
25.3
3.9
2.6
1.17
1.3
Max
29.4
9.9
44.8
2.48
6.0
Mean
27.0
8.2
16.6
1.52
3.0
The time series response of the UviLux-CDOM and UviLux-HC fluorometers during the
moored deployment in Baltimore Harbor are shown in figures 13 and 14, respectively. During
the deployment 33 discrete reference samples were collected and analyzed for hydrocarbon.
Only three samples, one on 8/22 and two on 8/24 had any detectable level of hydrocarbons as
analyzed by TestAmerica using GC-FID. The instrument response of the UViLux-CDOM unit
averaged 1713 +/- 118 mV during the initial deployment but no TPH detects were reported from
the corresponding reference samples. The UViLux-HC averaged 1735 +/- 184 mV over this
same period. During the second deployment the UViLux HC unit reported a similar initial
baseline but with occasional signal transients to 3600 mV during a period when baseline signal
decreased to approximately 1000 mV. While there was no apparent response to the reported TPH
measured on the 8/22 reference sample, the two TPH positive reference samples on 8/24 were
associated with upward transients in the UviLux-HC signal (Fig. 14, panel A). There was no
apparent tracking of instrument response by either unit to variation in temperature or salinity
(Fig. 13 and 14, panel B), or with chlorophyll, CDOM, or Turbidity despite substantial variation
in these parameters (Table 3 and Fig. 13 and 14, panel C).
Representative EEM fluorescent maps for reference samples collected on five different
dates are shown in figure 15 (with CDOM unit optical window depicted) and figure 16 (with HC
unit optical window depicted). EEM characteristics were fairly consistent over time and
fluorescence intensity maxima are actually more closely matched to the CDOM unit
configuration than the HC unit configuration.
Cross plots of instrument response to concentrations of TPH detected by GC-FID and
predicted EEM
QSE
intensities are shown in in figure 17 (UviLux-CDOM) and figure 18 (UviLux-
HC). The average EEM
QSE
for the reference samples yielding non-detects was 4099 (±82) cps
for the UviLux-CDOM optics. The EEM
QSE
for the UviLux-HC optics averaged 2729 (±578) for
the TPH non-detect reference samples and were 2893, 2893 and 3009 cps for the two 25 and 35
ppb reported TPH detects respectively, higher, but within the environmental range observed
during this deployment. The corresponding UviLux-HC response was 1167, 1106 and 1635 mV
for 25 ppb and 35 ppb reported TPH detects respectively. Only the referenced 35 ppb detect
sample corresponded to an instrument signal above the deployment average. These patterns
point to the difficulty in the quantitative interpretation of instrument signal responses in
environments with variable ambient fluorescence properties.
