Filename: PSEA0902_ver_Brooks_cruise_plan.doc
DYNAMIC OPTICAL PROPERTIES PROJECT
Lead: Marjorie L. Brooks, Ph.D.
Biogeochemistry and Aquatic Ecology
MC 6501, Dept. of Zoology
Southern Illinois University
Carbondale, IL 62901
Tel: 618-453-4121
Cell: 307-399-0576
FAX: 618-453-2806
Email: mlbrooks@siu.edu
Technicians on PSEA0902 Cruise:
Dawn Sechler, M.S.
Daniel Whiting, M.S.
I. BRIEF SCIENCE OBJECTIVE
Dynamic Optical Properties Project. Global warming is decreasing total extent and duration of sea
ice. Consequently, seas will receive sunlight exposure for longer periods in spring and summer. Data
collection as described above will evaluate the net effect of increased photosynthesis (more visible light)
versus the negative impact of ultraviolet radiation, which suppresses photosynthesis. Rates of
photooxidative processes combined with measures of the vertical attenuation of UV radiation in the
water column will provide data to calculate bulk quantum yield of chromophoric dissolved organic
matter (CDOM) production or bleaching in the water column and compare it to Chl a as a proxy for
primary production.
II. PROJECT SUMMARY AND RESEARCH QUESTIONS
A. Summary of Dynamic Optical Properties Project: Optics of seawater affected by loss of
sea ice. Dissolved organic matter (DOM) protects aquatic biota from ultraviolet (UV) radiation
and is an important source of organic carbon to the microbial community. However, DOM is
photochemically unstable, prone to both photomineralization (conversion from organic to
inorganic CO and CO2) and photobleached (loss of colored or “chromophoric” component that
absorb light). In the span of a few days, DOM from most sources loses 15 to 20% of its
dissolved organic carbon (DOC, which comprises about half of DOM) through
photomineralization (Molot and Dillon 1997, Xie et al. 2004). However, DOM from pure
cultures of algae is not photomineralized (Obernosterer and Benner, 2004). In the past, it was
thought that regardless of source, sunlight destroys the colored component of DOM (its
“CDOM”). This coloration absorbs UV radiation, and thus, protects biota from DNA damage
(Lehmann et al. 2004). CDOM also protects phytoplankton from UV radiation that impairs
primary productivity (Cullen et al. 1992; Hérnandez et al. 2007). This photobleaching indicates
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altered chemical composition of the residual DOM (e.g., the loss of sp2 hybridized bonds–the
double bonds of aromatic rings) in DOM from both terrestrial vegetation (Moran et al., 2000;
Del Vecchio and Blough, 2002) and pure algal cultures (Obernosterer and Benner, 2004).
Other researchers have conducted descriptive field studies of the role of CDOM and DOC in the
North Water Polynya (NWP) and the eastern and sub-Arctic. Observational studies indicate
that a combination of photooxidation and advective processes determine carbon loss in Baffin
Bay (Miller et al. 2002). Turn-over rate constants for photochemical removal dimethylsulfide
in the northeast subarctic Pacific (Bouillon et al. 2006) were similar to low latitude locations in
the literature, possibly suggesting that photooxidation rates of DOC might also be similar.
However, controls on CDOM production and loss in the NWP differed from low latitude sites.
Spectral quality and DOC concentration of terrigenous DOM varies among riverine sources
(Clark et al. 2004, Retamal et al. 2007). Interestingly, sea-ice algae may have a significant
biologic effect on CDOM character (Scully and Miller 2000, Belzile et al. 2000), which may
alter the spectral qualities of seawater if ice no longer forms in spring and fall.
Little work has evaluated the effect of photooxidation on DOM and CDOM in the Bering Sea,
aside from work conducted by Marjorie Brooks (HLY0702 and HLY0901) and an ironenrichment study demonstrating up-regulation of dimethylsulfide production and its subsequent
photooxidation (Bouillon et al. 2006). This research couples spectral characteristics of the
water column with controlled experiments and biogeochemistry of organics to investigate the
role of DOM photooxidation in the Arctic. In 2007, Brooks found that when exposed to
sunlight, CDOM from most field stations was photobleached as expected. However, in waters
collected at stations with extremely high primary production, sunlight exposure of seawater
produced CDOM. While unexpected, this finding makes biologic sense, because it is logical
that phytoplankton (or possibly associated bacterial or zooplankton communities) would
produce their own highly efficient sunscreen in optically clear waters. Moreover, others have
observed the same trend in temperate seas (Norm Nelson, pers. comm.) and in laboratory
experiments (Biers et al. 2007).
B. Research Questions
1. What is the role of DOM photooxidation in relation to the freshwater lens that forms during
sea ice melt (Spring) and to brine rejection during sea ice formation (Fall)?
2. How does source of DOM (e.g. ice algae, marine diatoms, bacteria, or zooplankton) alter the
spectral and photochemical behavior of DOM?
3. One means of narrowing the answer to question 2 is to ask, does source-dependent behavior
continue after algal-derived DOM is advected downward in to saltier substrata?
4. Another question that narrows source-dependent photoreactivity is how does sunlight affect
CDOM from ice algae vs. CDOM from marine phytoplankton (mainly diatoms) vs. cytosol
from microzooplankton and bacteria?
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5. Since CDOM differentially absorbs greater UV (λ = 280-400 nm) than PAR, how do varying
UV:PAR ratios alter primary production of ice algae vs marine phytoplankton?
III. FIELD SAMPLING
Opportunistic sampling and on-deck incubations during polar bear operations conducted 24
September to 31 October 2009 in the Beaufort Sea (See Ben-David cruise plan)
IV. DESCRIPTION OF OPERATIONS, Dynamic Optical Properties Project
A. General Approach: Data collection and sampling will include 4 components:
1. On-deck, recirculating incubations of seawater exposed to sunlight (Figs. 1, 2, & 3).
Time-series incubations will expose filtered water from varying depths to
ambient sunlight in 1 day intervals for a maximal exposure treatment of 3
days. Integrated measures of continuous UV radiation will be collected using
polysulfone dosimeters during exposures.
2. Collection of water samples at 70, 35, and 2 m depths for analyses of:
a. Particulate organic matter (POM) on 0.7µm filters.
b. Analysis of organic mass, organic carbon, and metals concentrations in POM.
3. Analysis of Chl α in water samples collected at 70, 35, and 2 m depths.
4. Hand-deployed casts of a UV-visible radiometer to a depth of ~100 m.
B. Water and Space Requirements:
1. Seawater: 40 L of water from 70, 35, and 2 m depths at approximately 10 to 20 stations
from CTD or collected by deployed carboy as polar bear operations and weather conditions
allow.
2. Space and other:
a. Refrigeration: Space for 2 chest coolers (1.0 x 0.5 x 0.5 m).
b. Freezer: Space for 2 small filter boxes (approximately 30 x 20 x 5 cm)
c. Deck Space on Foc’s’cle: Minimally shaded deck for deployment of incubation system
consisting of sealed quartz test tubes containing seawater secured inside 1 to 2 open-air
water baths with continuous circulation between an auxiliary reservoir of water to
maintain a constant water level in the incubation chamber. Entire system is surrounded
by a spill guard (<4 x 4 m).
i. Electrical requirements: 1 110 Volt outlet with a power strip or similar
configuration providing a minimum of 8 outlets.
ii. Seawater requirements: Hand-carry not more than 80 L to incubator.
iii. Space requirements: not more than 4 x 4 x 1 m
d. Lab Bench Space:
i. 2 m length and access to sink for draining filtered water.
ii. Subdued lighting (will bring garbage sacks to drape over temporary frame if
needed) for measuring Chl α.
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C. MST Support:
1. Oversee proper delivery of science seawater by Brooks’s research team (Sechler and
Whiting) to outside incubation system on foc’s’cle. Equipment will be provided by
Brooks’s team, but request that as MSTs desire, they evaluate heat-taped-and-insulated
water hoses, extension cords, tie-downs, and all other equipment for Coast Guard safety
guidelines (Figs. 1, 2, and 3).
2. Provide access to outside electrical outlets adjacent to incubation system (see Figs 4 and
5 for potential electrical outlet access points and tie-down options on foc’s’cle).
3. Preparation, deployment, and data collection of CTD.
4. Oversee hand deployment of radiometer by Brooks’s team.
D. Opportunistic Station Time:
1. CTD deployment: <60 min.
2. Radiometer deployment: <30 min.
3. Stations will be chosen by chief scientist and opportunistic as time allows during
missions on bears.
E. Specific Field Operations and Order of Opportunistic Sampling at Stations. Equipment
to be deployed into the water column during the cruise includes a CTD/rosette, and hand-held
radiometer. The following summary provides the lead contact for the major work
responsibilities:
1. Brooks team consisting of Dawn Sechler and Daniel Whiting have the lead for
deployments into the water column, focusing on CTD (Temperature /Salinity data, water
samples for chlorophyll and particulate organic matter [POM]).
2. After one deployment of the CTD, subsamples for chlorophyll and POM will be
collected by Sechler and Whiting.
3. A hand-held UV/PAR detector will be lowered from the starboard side-mid-ship position
to ~100 m by Sechler and Whiting.
4. Operations take place only during daylight hours.
5. Sensors on ship: Marjorie Brooks requests that data from all available scientific sensors
on the Polar Sea (ADCP, wind sensors, temperature and salinity data loggers, and on-deck
light meters) be provided on a CD at the end of the cruise.
V. REFERENCES
Belzile, C., S. C. Johannessen, M. Gosselin, S. Demers, and W. L. Miller. 2000. Ultraviolet attenuation
by dissolved and particulate constituents of first-year ice during late spring in an Arctic polynya.
Limnol. Oceanogr. 45: 1265-1273.
Biers, E.J., R.G. Zepp, and M.A. Moran. 2007. The role of nitrogen in chromophoric and fluorescent
dissolved organic matter formation. Mar. Chem, 103: 46-60.
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Clark, C. D. and others. 2004. CDOM distribution and CO2 production on the Southwest Florida Shelf.
Mar. Chem. 89: 145-167.
Cullen, J.J., Neale, P.J. & Lesser, M.P. 1992. Biological weighting function for the inhibition of
phytoplankton photosynthesis by ultraviolet radiation. Science 258: 646-650.
Del Vecchio, R. & N. V. Blough, 2002. Photobleaching of chromophoric dissolved organic matter in
natural waters: Kinetics and modeling. Mar. Chem. 78: 231-253.
Hérnandez, K. L., R. A. Quiñones, G. Daneri, M. E. Farias, and E. W. Helbling. 2007. Solar UV
radiation modulates daily production and DNA damage of marine bacterioplankton from a
productive upwelling zone (36°S), Chile. J. Exp. Mar. Biol. Ecol. 343: 82–95.
Lehmann, M. K., R. F. Davis, Y. Huot, and J. J. Cullen. 2004. Spectrally weighted transparency in
models of water-column photosynthesis and its inhibition by ultraviolet radiation. Mar. Ecol.
269: 101-110.
Miller, L.A., Yager, P.L., Erickson, K.A., Amiel, D., Bacle, J., Kirk Cochran, J., Garneau, M.-E.,
Gosselin, M., Hirschberg, D.J., Klein, B., LeBlanc, B. & Miller, W.L.. 2002. Carbon
distributions and fluxes in the North Water, 1998 and 1999. Deep Sea Res. Pt II: Topical Stud.
Oceanogr.49: 5151-5170.
Molot, L. A. & P. J. Dillon, 1997. Photolytic regulation of dissolved organic carbon in northern lakes.
Global Biogeoch. Cycles 11: 357-365.
Moran, M. A., W. M. Sheldon, Jr., & R. G. Zepp, 2000. Carbon loss and optical property changes
during long-term photochemical and biological degradation of estuarine dissolved organic
matter. Limnol. Oceanogr. 45: 1254-1264.
Obernosterer, I. and R. Benner, 2004. Competition between biological and photochemical processes in
the mineralization of dissolved organic carbon. Limnol. Oceanogr. 49: 117-124.
Scully, N. M., and W. L. Miller. 2000. Spatial and temporal dynamics of colored dissolved organic
matter in the North Water polynya. Geophys. Res. Lett. 27: 1009-1011.
Retamal, L., W. F. Vincent, C. Martineau, and C. L. Osburn. 2007. Comparison of the optical properties
of dissolved organic matter in two river-influenced coastal regions of the Canadian Arctic.
Estuar. Coast. Shelf Sci. 72: 261-272.
Xie, H., O. C. Zafiriou, W.-J. Cai, R. G. Zepp, and Y. Wang, 2004. Photooxidation and its effects on the
carboxyl content of dissolved organic matter in two coastal rivers in the southeastern United
States. Environ. Sci. Technol. 38: 4113-4119.
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Figures
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Figure 1. On-deck, Recirculating incubation system for PSEA0902. Quartz test tubes will be
secured to the incubation rack. Tie downs will secure the incubation tank and overflow reservoir.
* Water hoses that require electrical connections to power heat tape under insulation. A wooden
platform may be added under the incubation tank to raise it above shading from the short bulkheads on
the foc’s’cle. This will depend on how much sea ice has formed on the deck while steaming from
Seattle to Barrow, AK.
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Figure 2. Photograph during dismantling of Flow-Through incubation system used on HLY0901.
Note insulated and heat-taped, blue, inflow hose. Test tube rack was secured in center of the ice chest.
Aquarium heaters deployed along perimeter of ice chest maintained above-freezing temperatures.
Figure 3. Photograph during dismantling of Flow-Through incubation system used on HLY0901.
Note that all inflow and outflow water hoses are insulated and heat-taped then wrapped in blue duct
tape. Outflow hose was attached to upper back of white ice chest and deployed over the side. Test tube
rack was secured in center of the white ice chest. Aquarium heaters were deployed along perimeter of
ice chest maintained above-freezing temperatures. The gray ice chest functioned to hold down that
section of flexible spill barrier.
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Figure 4. Photographs of potential electrical access points on the Polar Sea taken 28 May 2009.
Figure 5. Photographs of potential tie down points on the Polar Sea taken 28 May 2009.
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Appendix of answers to Cruise Plan on IceFlow form
Dynamic Optical Properties Project
1. Area of operations: Opportunistic sampling and on-deck incubations as determined by Dr. Merav
Ben-David during polar bear operations conducted 24 September to 31 October 2009 in the Beaufort
Sea (See Ben-David cruise plan)
2. Type of work:
a. Off-side deployment of a hand-held radiometer.
b. Collection and analysis of the water samples from <101 m depths by the conductivity, temperature,
and density (CTD) rosette.
c. On-deck incubations of seawater in open water baths.
3. Science objective: Global warming is decreasing total extent and duration of sea ice. Consequently,
seas will receive sunlight exposure for longer periods in spring and summer. Data collection as
described above will evaluate the net effect of increased photosynthesis (more visible light) versus the
negative impact of ultraviolet radition, which suppresses photosynthesis. Rates of photooxidative
processes combined with measures of the vertical attenuation of UV radiation in the water column will
provide data to calculate bulk quantum yield of chromophoric dissolved organic matter (CDOM)
production or bleaching in the water column and compare it to Chl a as a proxy for primary production.
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