하구및 연안생태Coastal management 2014 년 가을학기

Measuring diagenesis From vertical profiles Simple 1-dimensional diagenetic model

Anaerobic energy flux: sulfur cycle Much of the energy is modulated through anaerobic microbial metabolism; sulfur cycle Assimilatory; amino acid, methionine, cystine Dissimilatory; disulfovibrio elemental sulfur Chemoautotrophic, photoautotrophic Pyrite formation and reoxidation Sulfate reduction played major role in Eh on sediments

Anaerobic energy flux: sulfur cycle About 50% of sediment oxygen demand is due to sulfide oxidation Sulfide oxidation is almost balanced by sulfate reduction Autotrophic sulfide oxidation: Beggiatoa; up to 4g dry wt/m2

Beggiatoa

Sulfate reduction and denitrification Denitrification was relatively important in winter in Danish sediments; up to 20% CH4 formation is less important; presence of SO4 inhibits Ch4 formation However, when the OM load is high CH4 production can be substantial

Metabolic gases O2. CO2, N2, CH4, H2S, NH3, N2O Abundant gases: N2, O2, Ar Noble gases: Ar, Ne, He, Kr, Xe N2:Ar ration: indicator of denitrification and nitrogen fixation Solubility: Busen coeeficient: volume of the pure gas 1 atm pressure that can desolve in a unit volume of water at standard temperature and presure.

Metabolic gases Gas flux across air-sea interface O2 flux is 2 times more than N2 Co2 flux is 70 time more than N2 Transfer coefficient: Kd: AD/Dz 0.1~2.5 mg O2 m-2 h-1 Lower value: shallow salt pond Higher value: windy conditions Saturation depicts

The Carbon dioxide system CO2 react with Water !!! “Chemical composition of the ocean is the result of a great acid-base titration !!!” Acid leaked from earth’s interior Substance that can donate proton Base released by weathering of rock Substance that can accept proton Carbonate system Equilibrium constant

The carbonate system Carbonic acid formation: Hydration-dehydration; carbonic anhydrase Ionization Dissociation Controlled by pH Dissociation constant; k1’, k2’ not k1, k2: calculated from concentration rather than the activity.

Calculating Carbon system TCO2, CO2 can be measured. All other should be calculated Buffering reaction of sea water: resist to the pH change. In sediments, however, high NH4+, HS- can exceeds buffering capacity On geologic time scale, suspended clay mineral provide buffering actions

Alkalinity Alkalinity: degree to which water accept protons [Bicarbonate, carbonate, borate OH- ] – [H+] Borates can be ignored in normal pH Carbonate alkalinity: bicarbonate + carbonate Conservative: TCO2 >> CO2 and CO32- variation

CaCO3 Calcite Aragonite Shells of benthic animals; mollusks etc..

Biological efftecs on O2, CO2 CO2: 2% is stored in the air. Water, rock, carbonate sediments, living, dead organisms Green house gas Diel changes in pH and O2 can be used to indicate production and consumption Photosynthesis: increase of O2 and pH

Biological efftecs on O2, CO2 AOU: apparent oxygen utilization Long-term changes in oxygen versus conservative tracers of water masses such as salinity can be used to estimate consumptions.; does not apply to estuaries

O2 budget for Chesapeake Bay Biological processes account for 43~69% of observed input Anoxia formations

The autotrophic nutrients C,N,P,Si,S,K,Mg,Na,Ca,Fe,Mn,Zn,Cu,B,Mo,Co,V, vitamins, thiamin, cyanocobalamin, biotin Macro nutrients; N, P, Si Constantly changing; river flow, ocean exchange Organic  inorganic Nutrient cycles can control energy flux in a ecosystem !!!; Nutrient cycle is fundamental to understanding of estuarien ecosystem

Nutrient forms and distributions Oxidation state Solid-liquid-gas Chemical structure Nitrogen is most diverse; -3~+5 Organic: highly reduced P: PO43- :+5; ortho, papa, meta Si: dissolved +4 (H4SiO2) detrital quartz, aluminosilicate clays, dissolved silicon

Nutrient forms and distributions Seasonal variations Mid summer PO4 peak: temperature regulated regenerations and redox condition NO3: winter maxima; external input via land run-off NH4: high in sewage input sites; balance between phytoplankton uptake and benthic regneration

Nutrient forms and distributions High in river head