n . ogrinc “ j. stefan” institute, dept. of environ. sci., ljubljana, slovenia j . faganeli
DESCRIPTION
Phosphorus regeneration and burial in near-shore marine sediments (the Gulf of Trieste, N Adriatic). N . Ogrinc “ J. Stefan” Institute, Dept. of Environ. Sci., Ljubljana, Slovenia J . Faganeli Marine Biological Station, Piran, Slovenia. - PowerPoint PPT PresentationTRANSCRIPT
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Phosphorus regeneration and burial in near-shore marine sediments (the Gulf of Trieste, N Adriatic)
N. OgrincJ. Stefan Institute, Dept. of Environ. Sci., Ljubljana, Slovenia
J. FaganeliMarine Biological Station, Piran, Slovenia
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Aime . . . Investigation of the biogeochemical cycling of phosphorous to elucidate the present and future naturally and anthropogenically induced changes in this coastal ecosystem using
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Pore water chemistry
Sediment analysis to reconstruct sedimentary phosphorus budget
Examination of historical changes of sedimentary P - (long core GT3)
Benthic flux experiment (oxic and anoxic conditions)
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Some characteristics ILocation:N Adriatic seaarea: approx. 500 km2max. depth: 25m
Inflow:river Isonzo in the N
Water characteristicstemperature at the bottom: 8-22oCsalinity: 33-38.5overlying water oxic, in late summer hypoxia (occasionally anoxia)
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length: 130 cmwater depth: 25 mAA1GT3 coreFSampling locations - the Gulf of Trieste
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Some characteristics II
Composition of the sediment:
clay and silt-sized material carbonates: mostly low-Mg calcite: biogenic, up to 70%no carbonate fraction: quartz, illite, chlorite and mixed illite/montmorilloniteorganic content: 0.3 0.7 wt.% bioturbated: 10-15 cm
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AnalysesWater samples: O2, nutrients, sulphide, sulphate, Fe, Mn
Sediment samples:Organic C, Total N, Total P, Inorganic P, Total S, Reducible S, Total Fe, Total Mn
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Previous results in the Gulf of TriesteRedfield: N:P = 16
Suspended particulate matter: N:P = 9
Sedimenting organic matter: N:P = 11
Surficial Sediment: N:P = 7
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Pore water I
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Pore water II
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EXAFS - Goethite the predominant crystalline structure
Reduction of Fe oxide 8% of the P flux
Precipitation and nucleation - fluoroapatiteP - remobilization
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Incubation experiment I
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Incubation experiment II
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Sedimentary P - budgetPinput = Pefflux + Pburial
Pburial = w TP (1- )w sedimentation rate density ... porosity
E = Pefflux/Pinput ~ 50%
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Mass balance of particulate phosphorus
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Conclusions IPore water and incubation experiment:
Degradation of organic matter is a principal mechanism of phosphate regeneration
The high C:N:P ratio of degradable sedimentary organic matter suggests precipitation of phosphates - fluoroapatite
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Conclusions IISediment
The results of the tentative mass balance estimation indicate the preservation of TP in the form of fluoroapatite (about 50%)
Palaeoenvironmental reconstruction - the increase of TP, OP, TN and OC in the sediment core probably indicate the use of inorganic fertilizers and detergents after 1950
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10th International Symposium on the Interactions Between Sediments and WaterBled, SloveniaAugust 28th September 2nd, 2005Organized by:National Institute of BiologyJ. Stefan Institutewww.icjt.org/iasws2005E-mail: [email protected]