Dynamic of Chromophoric Dissolved Organic Matter (CDOM ... - CICS

Components that absorb visible lightin the aquatic environmenta(λ) = a w (λ) +a d (λ) + a ph (λ) + a g (λ)Where:a(λ) = total absorptiona w (λ) = water absorption (Pope & Fry, 2001)a d (λ) = detritus absorption (measured)a ph (λ) = phytoplankton absorption (measured)a g (λ) = CDOM absorption (measured)

Then, what is this Chromophoric DissolvedOrganic Matter (CDOM)?It is an operational definition:They are all the dissolved organicsubstances in a water sample filtered by0.45-μm that absorb UV-Visible lightCDOM is mainly compose of Humic andFulvic acids

Importance of the study of the CDOM inthe Marine Environment?1- CDOM absorbs light in the UV-Visible range:a-Affects the estimate of chlorophyll-a concentration by RemoteSensing specially in coastal zonesb-Affects the primary production by light absorptionc-It has been related to the production of H 2 O 2 , free radicals andoxidation state of metals2- Can have implications in the availability of micro andmacronutrients for phytoplankton3- It compose a large fraction of the Dissolved OrganicMatter DOM (40-60%) with the advantage that it canbe studied by Remote Sensing Techniques

Absorption Coefficient Spectrum of CDOM andof Chlorophyll-a Percent of Absorption6Absorption Coefficient ( m- 1)543210250 350 450 550 650Wavelength (nm)

Specific ObjectivesDetermine the contribution of the CDOM to the Bioopticalproperties of the Mayagüez Bay from inshore tooffshore stations during the rainy and dry seasonsHow is the terrestrially derived CDOM transported bythe local rivers diluted and photodegraded from aninshore-offshore gradient?What is the effects of the co-transported clay materialin river waters have on the CDOM when bothmaterials enter the marine environment?

Study AreaInshore stations:A1AAA1Y1G1Offshore stations:A2G2Samples for:TSS, Chl-aCDOM

Field Work

Field WorkBio-optical package profiles:SalinityTemperatureTotal absorption and attenuation coefficient at 9channelsChlorophyll-a FluorescenceBackscattering at 6 channelsUpwelling and downwelling Irradiance meters at7 channels one for PARGER Spectroradiometer (Remote SensingReflectance)

Laboratory WorkWater samples taken in the field are analyzed for:CDOM:Absorption CoefficientSpectral SlopesChlorophyll-a ConcentrationTotal Suspended Solids (TSS) Concentration

CDOM Sampling and AnalysisEquipment

Suspended Solids Filtration Unit

Laboratory Experiment1- Dilution experiments of CDOM betweenriverine and marine end members2- Photodegradation experiments of CDOM3- Adsorption experiments between river waterCDOM and clays exposed to marine waterend members

Sediment Characterization for theWest Coast RiversTwo hundred liters of water from theGuanajibo and Añasco Rivers were left tosettle for a week the material was thencollected and dried at 60 o C. The claymaterial was characterized by X-Raydiffraction technique

River Discharge for the Río R o Grande de Añasco AandGuanajibo during the Study Period1400Rainy Season12001000Discharge (cf/s)800600Dry SeasonAñascoGuanajibo400Dry SeasonData from200USGS01/4/044/4/047/4/0410/4/041/4/054/4/057/4/0510/4/051/4/064/4/067/4/0610/4/061/4/07Months

Average Salinity During the Rainy and DrySeason for Inshore and offshore Stations36.53635.5Rainy SeasonDry SeasonPSUSalinity3534.5InshoreOffshore3433.5August 04Mar-05Jul-05Aug-05Sep-05Oct-05Dec-05Mar-05Apr-05Sep-05Sampling months

Total Suspended Solids (TSS) in the Surface andDepth During the Rainy Season30TSS (mg/L)252015A1A2AAAG1G2Y1River Discharge1050Surface Surface Surface Deep Surface DeepJuly 192005August 172005September 20 2005 October 19 2005Cruise Dates

Total Suspended Solids (TSS) in the Surface andDepth During the Dry Season30TSS ( mg/L)25201510A1A2AAAG1G2Y1Resuspention50Surface Deep Surface Deep Surface Deep Surface DeepMarch 10 2005 December 6 2005 March 8 2006 Abril 21 06Cruise Dates

a g 375 nm vs. Salinity Correlation for theRainy SeasonAbsorptionCoefficient(ag 375 nm)0.70.60.50.40.30.20.1033.8 34.3 34.8 35.3 35.8Salinityy = -0.3725x + 13.3R 2 = 0.6278r = 0.79n = 31SuperficieSurfacePDepthro fundidad

CDOM Profiles at A1 and A2 Station forthe Dry SeasonDepth (m)Absorption Coefficient at 412 nm (m -1 )Absorption Coefficient at 412 nm (m -1 )December March AprilCDOM Profile at the A1 Station(Inshore)December March AprilCDOM Profile at the A2 Station(Offshore)

Remote Sensing Reflectance (Rrs) for theMonth of May 2007Remote Sensing Reflectance (sr -1 )0.010.0080.0060.0040.0020Offshore watersInshore watersA1 inA2 offAAA1 inAAA2 offY1 inY2 offG1 inG2 off400432463494524555585615645675Wavelength (nm)

CDOM Distribution the Mayagüez Bay1- During the rainy season the CDOM absorptioncoefficient and the TSS distribution are correlated tosalinity due to the rivers discharge2 - During the dry season the high CDOM absorptioncoefficient and TSS on the G2 and G1 station can beexplained due to bottom resuspention3- Other factors that could be related to CDOMdistribution can be related to photodegradation in theupper water column during the Dry season4- Possible interactions of CDOM with clays transportedin river waters and by dilution of marine water endmember can also explain CDOM distribution duringrainy season

Questions?