Carbon Cycle2. Analytical techniques in chemical oceanographyThe Marine C CycleDOC distributionSources of DOC to surface oceanWhat is DOC?POC distributionParticulate Organic Carbon (POC)Carbon cycle ratesAnalytical techniques in chemical oceanographyNutrient analyzerMetals: ICP-MSMetals: ICP-MSOrganic Carbon Analyses 1Organic Carbon Analyses 2Organic Carbon: Isotopes Overview13C ratios in environment1. Carbon Cycle2. Analytical techniques in chemical oceanography12.097 LectureJanuary 18, 2006From www.pmel.noaa.gov/co2/gif/The Marine C CycleValiela, 1994. (See readings.)Image removed due to copyright considerations. Please see:DOC distributionSummary depth profile of DOC in open ocean, separated into low and high molecular weight components. Please see: Williams 2000. (See readings.)Image removed due to copyright considerations.Sources of DOC to surface oceanPlease see: Nagata, 2000. (See readings.)Image removed due to copyright considerations.What is DOC?Please see: Williams, 2000. (See readings.)Image removed due to copyright considerations.POC distributionFrom: http://esd.lbl.gov/CLIMATE/OCEAN/images/observations.gifParticulate Organic Carbon (POC)• POC falls in episodic “clumps”• Cannot be sampled adequately by Niskin bottles –must use (semi-)permanently moored sediment traps• Flux: 1-100 mgC / m2/ d• Varies seasonally• Labile organic matter is transported quickly to ocean floor.Please see: S. Wakeham (www.skio.peachnet.edu/research/biogeochemlab/)Image removed due to copyright considerations.Carbon cycle ratesPlease see: Williams, 2000. (See readings.)Image removed due to copyright considerations.Analytical techniques in chemical oceanographyNutrient analyzerMatt Charette’s lab in Marine Chemistry dept at WHOI• Lachat nutrient auto-analyzer: measures total dissolved nitrogen (TDN), ammonia, nitrate, nitrite, phosphate, silicate• Based on standard spectrophotmetric techniquesMetals: ICP-MS1H3Li4Be12Mg20Ca21Sc22Ti23VMulticollector ICP-MS24Cr25Mn26Fe27Co28Ni29Cu30Zn31Ga13Al14Si15P16S17Cl18Ar5B6C7N8O9F10Ne2He32Ge33As34Se35Br36Kr38Sr39Y40Zr41Nb42Mo43Tc44Ru45Rh46Pd47Ag48Cd49In50Sn51Sb52Te53I54Xe56Ba57La72Hf73Ta74W75Re76Os77Ir78Pt79Au80Hg81Tl82Pb83Bi84Po85At86Rn11Na19K37Rb55Cs87Fr(119)58CeLanthanidesActinidesSuper-Actinides59Pr60Nd61Pm62Sm63Eu64Gd65Tb66Dy67Ho68Er69Tm70Yb71Lu(120) (121) (154) (155) (156) (157) (158) (159) (160) (161) (162) (163) (164) (165) (166) (167) (168)88Ra89Ac104Rf105Ha106Sg107Ns108Hs109Mt110 111 112(113) (114) (115) (116) (117) (118)90Th91Pa92U93Np94Pu95Am96Cm97Bk98Cf99Es100Fm101Md102No103Lr(122) (123) (124) (125) (126) (153)Figure by MIT OCW.Metals: ICP-MSPlease see: Thermo-Finnigan NEPTUNE/TRITON brochureImage removed due to copyright considerations.Organic Carbon Analyses 1• Bulk analyses:– Elemental analysis • Amt of C, H, or N in solid sample• Used on particulate material or freeze-dried “dissolved” material– Carbon combustion• Amt of C in sample after removal of CO2• High-temperature combustion (>800oC)• Used for aqueous samples only.Image removed due to copyright considerations. Please see: http://www.uark.edu/ua/isotope/about/elemental_analyzer.jpgImage removed due to copyright considerations. Please see: L. Guo(http://denali.frontier.iarc.uaf.edu/)Organic Carbon Analyses 2• Compound-specific analyses require (relatively) large amounts of a single compound: need to concentrate initial sample!• Polar compounds: remove water– Analysis by HPLC• Nonpolar compounds: extract with organic solvent or solid organic matrix (SPE)– Analysis by GC• Semi-polar compounds– Change pH of solution to make compound neutral (non-ionic)– Derivatize polar component with non-polar functional group• Mass spectrometry– Used to characterize structure and/or composition of individual moleculesFrom: www.chemterra.com/imgs/hc-mkwfig10.jpgOrganic Carbon: Isotopes Overview• There are 3 isotopes of carbon:–12C: 6 neutrons, 6 protons, stable, 98.89% of all carbon–13C: 7 neutrons, 6 protons, stable, 1.11% of all carbon–14C: 8 neutrons, 6 protons, radioactive, 10-10%• Dominant process for determining 13C/12C: fractionation– The small mass difference (approx 1 Da) creates a small (but significant) in energy requirements for bonds between 13C and the more abundant 12C atoms. – Thus, biological systems will preferentially use 12C over 13C, resulting in a decreased 13C/12C in biological material and an increased 13C/12C in the reservoir.– Reported values: δ13C1000*12131213121313⎥⎥⎥⎥⎥⎦⎤⎢⎢⎢⎢⎢⎣⎡⎟⎟⎠⎞⎜⎜⎝⎛⎟⎟⎠⎞⎜⎜⎝⎛−⎟⎟⎠⎞⎜⎜⎝⎛=∂stdstdsampleCCCCCCCδ13C ratios in environmentImage removed due to copyright considerations. Please see: Image removed due to copyright considerations. Please see: Image removed due to copyright considerations. Please