Presentation on theme: "Chemical Oceanography"— Presentation transcript:
1 Chemical Oceanography Marine Science Unit 4:umassmarine.net
2 Marine Science: Chemical Oceanography Day 1 – Water Structure and Properties Objectives:Explain the structure of a water molecule.What is a polar molecule?What “special” properties does water have because it is a polar molecule?Why does ice float? Why is that important to Earth?
3 Chemical Oceanography The study of the chemical reactions that occur in sea waterstudydiscussions.com
4 Water Structure Water is made up of two elements HydrogenOxygenThe chemical symbol for water is H2OThis means that each molecule of water is composed of two hydrogen atoms and one oxygen atom.Water Boy clip:ehe.osu.edu
5 Water StructureThe hydrogen atoms are bonded to the oxygen atom in waterThe type of bond that holds these atoms together is a covalent bond.Covalent Bond: Type of chemical bond that involves the sharing of electrons between two or more atomsmedicalsciencenavigator.com
7 cultivatecuriosity.comPolarity of WaterWater is a polar molecule because it has an uneven distribution of chargesThe oxygen atom attracts the shared electrons close towards its large nucleus – making it slightly more negative (-)The two hydrogen atoms have more protons than electrons – making them slightly positive (+)teachingphysics.wordpress.com
8 Water Molecules form Hydrogen Bonds Water’s polarity allows it to bond with many other molecules – including itselfHydrogen Bonds form between water molecules because the slightly positive hydrogen end of one water molecule is attracted to the slightly negative oxygen end of another water moleculeHydrogen bonds are much weaker than covalent bonds++-++--++++-uic.edu
12 Properties of Water Due to its polarity, water has special properties… Water as a liquidCohesion/AdhesionViscositySurface TensionIce Floatsxsteam.sourceforge.net
13 Liquid WaterWater is liquid at room temperature because hydrogen bonds hold the molecules togetherMore energy (heat) is needed to break the hydrogen bonds to turn water from a liquid to a gas (water vapor/steam)whatscookingamerica.net
14 Cohesion and Adhesion Cohesion Water molecules stick to each other ga.water.usgs.govCohesion and AdhesionCohesionWater molecules stick to each otherAdhesionWater sticks to other materialsDue to its polarity, the partial positive and negative charges of water molecules are attracted to positive and negative forces of other substancesmylargescale.com
17 Viscosity The tendency of a fluid (gas or liquid) to resist flow nationstates.netViscosityThe tendency of a fluid (gas or liquid) to resist flowMost fluids change viscosity as the temperature changesHydrogen bonds hold water molecules together, they make water more viscousAs water cools, the viscosity rises more than other liquids because the hydrogen bonds resists the tendency to move molecules apartThis is important for aquatic organisms because it affects the amount of energy they expend:For floating/drifting organisms like plankton need less energy to keep from sinkingFor swimming organisms because it requires them to use more energy to move through it
19 Surface Tension Water’s resistance to objects penetrating its surface The polar nature of water allows it to form a “skin”Caused by hydrogen bonds holding the water molecules togetherMany smaller animals use surface tension and weight distribution to “walk on water”defneapul-cive1170.wikispaces.com
23 gps.caltech.eduIce Floats?Most substances become dense and sink as they cool and turn from liquid to solidMost substances lose density as they heat and turn from liquid to gasWater also becomes less dense as it heats and becomes denser as it cools… but only to a certain pointAs water cools enough to turn from a liquid to a solid, the hydrogen bonds spread the molecules into a crystal structure that takes up more space than liquid waterWith more volume, ice is less dense than water so it floatsThis property has a huge effect on EarthBy floating, ice insulates the water below, allowing to retain heat and remain a liquid – if ice sank the oceans would be entirely frozen or at least much colder – this would drastically change the Earth’s climate
25 Marine Science: Chemical Oceanography Day 2 – Chemistry of Water Objectives:What are the differences between solutions and mixtures?What is the “universal solvent”? Why?
26 Solutions and Mixtures in Water What is a mixture?Two or more substances are closely intermingling , yet retain their individual characteristicsEx. India ink in water = can be mixed together but if left alone ink settles outWhat is a solution?When the molecules of one substance are evenly (homogenously) dispersed among molecules of another substance.Water is the universal solvent due to its polaritySolvent: the substance that dissolves the soluteSolute: the substance that is dissolved in anotherwater.me.vccs.edu
29 Water as a Solvent Salt dissolves in water due to water’s polarity physicscentral.comSalt dissolves in water due to water’s polarityWater’s polarity pulls apart/dissociates the salt crystals (NaCl)In the process, the dissociated sodium and chloride become charged particles/ions and are attracted to the positive hydrogen atoms and the negative oxygen atoms of water moleculesThese bonds tend to keep salt in the solutionelmhurst.edu
30 Water as a SolventSubstances that do not separate into ions can still dissolve in water through other mechanismsEx. Sugar is not ionic but can dissolve in water when it is broken down into its individual moleculesBecause so many substances dissolve in water, it is known as the “universal solvent”A few substances do NOT dissolve in water…Non-polar substances like oil do not dissolve in waterThis is why oil spills float on top of the water…
32 Marine Science: Chemical Oceanography Day 3- Salinity Objectives:What is salinity?What are the major sea salts?What are the colligative properties of seawater?What is the principle of constant proportions?What are the most abundant chemicals in seawater?Where do sea salts come from?How do temperature and salinity affect seawater?What factors affect seawater pH?
33 planet-science.comSalts and SalinitySalinity: The total quantity or concentration of all dissolved inorganic solids (ions) in seawater.Dissolved Salts: Any salt dissolved in seawaterSalinity is expressed in parts per thousand (‰) because even very small variations are significantTo convert parts per thousand into percent you divide by 10, so that 35 ‰ = 3.5%How do scientists measure salinity?Methods vary but usually involve the conduction of electricity
34 Major Sea SaltsOnly six elements and compounds comprise about 99% of sea salts:chloride (Cl-)sodium (Na+)sulfur (SO4-2)magnesium (Mg+2)calcium (Ca+2)potassium (K+)The chloride ion makes up 55% of the salt in seawater.
36 Why are the oceans salty? Weathering/ErosionEvaporationHydrothermal VentsBiological ProcessesVolcanic Activity
37 Are the Oceans Getting Saltier? oceanclassrooms.comAre the Oceans Getting Saltier?
38 Why are the oceans salty? When it rains on land, some of the water dissolves minerals, like salt, in rocks. That water flows in rivers to the sea. It carries the minerals with it. When water evaporates back out of the ocean, it leaves the minerals behind. The minerals make sea water salty.palomar.edu
39 Variations in Oceanic Salinity The proportion of dissolved sea salts does not change, only the relative amount of waterThere is variation in specific areas:Mouth of River – near zeroRed Sea - 40 ‰Brackishwater (freshwater mixes with seawater in estuaries) ‰ to 30 ‰Brine Water (areas with high evaporation and little inflow of freshwater or where salt domes dissolved on the seafloor – Gulf of Mexico) – Saturated or nearly saturated
41 Colligative Properties of Seawater Colligative Properties: The properties of a liquid that may be altered by the presence of a soluteThe strength of the colligative properties depends on the quantity of soluteThe colligative properties of seawater are:Raised Boiling Point – boiling point of seawater is slightly higher than pure fresh waterDecreased Freezing Temp – freezing point of seawater is slightly lower than that of pure fresh waterAbility to Create Osmotic Pressure – see next slideElectrical Conductivity – Salts act like conductors and conduct electricityDecreased Heat Capacity – It takes less heat to raise the temperature of seawater than to raise freshwaterSlowed Evaporation– The attraction between salt ions and water keeps seawater from evaporating as fast as freshwater
42 Ability to Create Osmotic Pressure Osmosis: Movement of water through a semi-permeable membrane from areas of HIGH concentration to areas of LOW concentrationCrucial to many biological processessparknotes.com
43 Principle of Constant Proportions Principle of Constant Proportions: Principle that the proportions of dissolved elements in seawater are constantOnly the amount of water (and therefore the salinity) changesConservative Constituents: Dissolved SaltsNo matter how much the salinity varies, the proportion of key elements and compounds don’t changeUseful b/c if you know the amount of one element, you can determine how much there is of others.
44 Dissolved Solids in Seawater Besides hydrogen and oxygen (H2O) the most abundant chemicals in seawater are:Chloride gSodium gSulfate 2.65 gMagnesium 1.28 gBicarbonate 0.14 gCalcium 0.40 gPotassium 0.38 gOther 0.16 g*Remember Average Salinityis 35‰ = 3.5% = 35 g
45 Determining SalinityUsing the principle of constant proportions, if you know how much you have of one seawater chemical, you figure out the salinity.The formula for determining salinity is based on all the chloride compounds (not just sodium chloride)Salinity ‰ = x chlorinity ‰Example: You have a seawater sample that tests 19.2 ‰ chlorinity – What is the salinity of this water sample?Salinity ‰ = x 19.2 ‰Salinity ‰ = ‰Likewise, when you know salinity you can determine chlorinity:Example: You have a seawater sample that tests ‰ salinity – What is the chlorinity of this water sample?34.68 ‰ = x chlorinity ‰19.2 ‰ = chlorinity ‰
46 Practice Using The Principle of Constant Proportions Salinity ‰ = 1 Practice Using The Principle of Constant Proportions Salinity ‰ = x chlorinity ‰2. If the salinity of seawater sample is 41.06g, what is the chlorinity?1. If the cholorinity of a seawater sample is 21.3g, what is the salinity?
47 Determining Salinity, Temperature, and Depth Scientists measure salinity, temperature, and depth using special instruments and procedures:Salinometer: Determines the electrical conductivity of waterConductivity, Temperature, and Depth Sensor (CTD): Sensor that can be attached to a submersible or deployed by itself to profile temperature, depth and salinity. Data are transmitted to a ship/vesselTemperature and salinity are used to determine densitysardi.sa.gov.au
49 Salinity, Temperature, and Water Density Most of the ocean’s surface has an average salinity of 35 ‰Waves, tides, and currents mix waters of varying salinity and make them more uniform – so, even surface salinity varies with the season, weather (especially rainfall and evaporation), and location (bays, semi-enclosed seas, and mouths of large rivers)Rainwater and water flowing from freshwater rivers lowers salinity while evaporation increases salinitySalinity and temperature also vary by depthDensity differences cause water to separate into layersHigh density layers like beneath lower density layersWarmer, lower density surface waters are separated from cool, high density deep waters by the thermoclineThermocline: The zone at which the temperature changes rapidly with depth
52 Acidity and Alkalinity Acidity and alkalinity are measured on the pH Scale.The pH scale measures the amount of positive hydrogen ions (H+) and negative hydroxide ions (OH-) in a liquidAcid: A solution high in H+ ions is considered (0-7)Base: A solution high in OH- ions is considered to be alkaline (7-14)Increasingly AcidicIncreasingly Basic
54 Acidity and Alkalinity pH of Seawater:Pure seawater has a pH of 7 (7 is neutral)Typical seawater has a pH range of 7.8 – 8.3Carbon dioxide in seawater acts as a buffer and prevents changes in the pH of the oceannature.com
55 Carbon Compensate Depth Although seawater pH is relatively stable it changes with depth b/c the amount of carbon dioxide varies by depthUpper Depths - generally 8.5 pH– warmer and have photosynthetic organisms with less CO2Middle Depths - more carbon dioxide present from respiration of marine organisms – more acidic with lower pHLower Depths-1,000 meters = more alkaline/basic3,000 meters and deeper = more acidic again b/c the decay of sinking organic materials produces CO2Carbonate Compensation Depth (CCD): The depth at which calcium carbonate dissolves as fast as it accumulatesGenerally occurs around 4,500 metersWater below the CCD is acidic enough to dissolve sinking shells (which are made of calcium carbonate)
56 Marine Science: Chemical Oceanography Day 4 – Biogeochemical Cycles Objectives:How do the proportions of organic elements in seawater differ from the proportion salts?What is the biogeochemical cycle?What elements is fundamental to all life?What are the roles of carbon in organisms?What are the roles of nitrogen in organisms?Why is phosphorous important to life?What is the role of silicon in marine organisms?What are the roles of iron and other trace metals in marine organisms?
57 Organic Dissolved Solids Although the majority of dissolved solids are inorganic salts, there are many other types of organic solids that are also found in seawaterOrganic: Compound that contains carbon and is associated with living thingsThe Principle of Constant Proportions does not pertain to organic solidsConcentrations and proportions of organic material varies widely
58 Biogeochemical CycleAll life depends on materials from the non-living (abiotic) part of the EarthOrganisms require specific elements and compounds to stay alive.Ex. Humans require oxygen gas, water, etcBiogeochemical Cycle: The continuous flow of elements and compounds between organisms and the earth
59 Fundamentals of Biogeochemical Cycles All matter cycles...it is neither created nor destroyed...As the Earth is essentially a closed system with respect to matter, we can say that all matter on Earth cycles .Biogeochemical cycles are basically the movement (or cycling) of matter through a system
60 The Cycling ElementsMacronutrients: Required in relatively large amounts“BIG SIX": carbon , hydrogen , oxygen , nitrogen , phosphorous, sulfurOther Macronutrients: potassium , calcium , iron , magnesiumMicronutrients: Required in very small amounts, (but still necessary)boron (green plants)copper (some enzymes)molybdenum (nitrogen-fixing bacteria)
61 Generalized Biogeochemical Cycle Five cycles that we will focus on in Marine Science:The nitrogen cycleThe phosphorus cycleThe carbon/oxygen cycleThe water cycleThe silicon CycleThe circulation of chemicals in these biogeochemical cycles and interactions between cycles are critical for the maintenance of terrestrial, freshwater and marine ecosystems. Global climate change, temperature, precipitation and ecosystem stability are all dependent upon biogeochemical cycles
62 Nitrogen CycleOrganisms require nitrogen for organic compounds like proteins, DNA, and chlorophyll (the plant pigment used in photosynthesis)Nitrogen makes up 78% of the air and 48% of all dissolved gasses in seawater… gaseous nitrogen must be converted into a chemically usable form before living things can use itNitrogen Fixation: Bacteria in the soil can convert gaseous nitrogen into ammonium (lightning also fixes small amounts of nitrogen)Nitrificaiton: Nitrifying bacteria convert ammonium ions into nitrite and nitrate (some plants can use ammonium ions others need nitrates)Ammonification: Breaking down nitrogen compounds in the remains of organisms into ammonia – this is preformed by decomposersDenitrification: Conversion of ammonia, nitrite, or nitrates into N2 gas. Denitrifying bacteria take nitrogen compounds in the soil and convert them intro free nitrogen/N2 gas
66 Carbon and Oxygen Cycle The main phases of the cycle are:Photosynthesis: During this process plants and algae take in carbon dioxide and release oxygen gasCellular respiration: During this process organisms take in oxygen and release carbon dioxideDecay/Decomposition: When organisms die they are decomposed and any remaining carbon atoms are released into the atmosphere/groundFossil Fuels: Rich fuel composed of dead plant and animal matterCombustion: Burning of plant or animal matter, burning of fossil fuels, volcanic eruptions, etc. releases gasses into the atmosphere, ocean, and groundOcean Storage: Large amounts of carbon are stored in the ocean in various forms
67 http://www.whoi.edu/main/topic/carbon-cycle slide of Carbon Cycle video of ocean rock in Oman
68 Carbon in the OceanSeas have plenty of carbon in many different forms:Carbon dioxide in the atmosphere dissolves into the oceanCertain carbon containing rocks and minerals can be eroded and their sediments dissolve in ocean waterAnimals wastes and the decomposition of dead organisms and their wastes release carbon into the oceanBiological pump tends to concentrate carbon and other nutrients with depth – action by bacteria decomposing organic material. This pump transfers carbon from the atmosphere to the deep sea where it concentrates and remains for centuries
69 Carbon and Oxygen Cycle- Human Impact Humans are impacting the carbon cycle in various ways…Burning of fossil fuels- releases excessive amounts of CO2 that is causing global warming/global climate changeDeforestationPollutionbritannica.com
73 Water Cycle Main Phases: Evaporation: Liquid water stored in lakes, rivers, streams, and oceans is heated and forms water vaporCondensation: Water Vapor in the atmosphere attaches to particles in the atmosphere like dust and condenses to form liquid water dropletsPrecipitation: Water in form of rain, snow, sleet, hail etc. fall from cloudsGroundwater: Precipitation infiltrates the soil/rocks and is stored in the groundRun-Off: Precipitation that is not absorbed into the ground flows into rivers, lakes, streams, and the oceanTranspiration: Water is taken up by the roots of plants and can be used to cool the plant as it evaporates from small holes in the leaves of plants
77 http://quercus. igpp. ucla. edu/research/projects/res_fr_main_silicon Silicon CycleAbout three quarters of the primary production in coastal and nutrient replete areas of the world oceans is carried out by diatoms.Diatom: A phytoplankton that needs silicon (Si) for the build up of their opaline (silicate) shells.In low nutrient areas diatoms still contribute to about one third of the marine primary production.Silicic acid is the biologically available form of silicon in the marine environment and its surface water concentration can severely limit diatom biomass build up.The silicious tests (skeletons/shells) produced by diatoms tend to be much heavier than water and sink which provides for the transport of organic carbon (which is another element found in their shells) from the surface ocean into the deep ocean(the biological carbon pump).Once in the deep ocean, their shells/skeletons form sediments like rocks and sand (silica is a major component of sand).MUCH later, these sediments are moved and may become exposed and eroded…
79 Phosphorus CyclePhosphorus is important to marine life in a number of ways… it is component of ATP and ADP (energy for cells) and also a part of DNA (genetic information)Phosphorus is cycled through marine ecosystems in a number of ways:Plants obtain phosphorous from the soil or water in which they liveAnimals obtain it by eating plantsWhen the animals die they decompose and the phosphorous is returned to the soilWhen animals defecate (waste) phosphorus is also released. For example, bird guano is a primary source of phosphorus in seawaterPhosphorous is also washed into the sea from the weathering of rocksHumans are disrupting this cycle…Organic fertilizers and human pollution from detergents can release extra phosphorous into the environment and cause problems for fresh water and inshore marine ecosystemsExtra phosphorous can cause algae blooms – the algae will bloom out of control and when they die the bacteria that decompose them will use all of the oxygen in the water killing fish and other freshwater organisms
81 Chemical Factors Affect Marine Life’s Homeostasis Homeostasis mechanisms protect an animal’s internal environment from harmful fluctuationsCellular Transport: living things must obtain materials from their environment and cellular transport is how living cells obtain materials/nutrients that they needThere are two types of cellular transport:Passive TransportActive Transport
82 Passive TransportPassive Transport: Type of cellular transport that does not require energy because materials are being transported with the concentration gradientConcentration Gradient: when materials are moved across a membrane from higher concentrations to lower concentrations3 Types of Passive Transport:Diffusion – movement of materials from high to low concentrationsOsmosis – diffusion of water across a semi-permeable membraneFacilitated Diffusion – use of protein channels to move materials from high to low across a cell membrane
84 Osmotic SolutionsHypertonic Solution When the osmotic pressure of the solution outside the cells is higher than the osmotic pressure inside the cells, the solution is hypertonic. The water inside the cells exits the cells in an attempt to equalize the osmotic pressure, causing the cells to shrinkIsotonic Solution When the osmotic pressure outside the cells is the same as the pressure inside the cells, the solution is isotonic with respect to the cytoplasm. This is the usual condition of red blood cells in plasma.Hypotonic Solution When the solution outside of the cells has a lower osmotic pressure than the cytoplasm of the cells, the solution is hypotonic with respect to the cells. The cells take in water in an attempt to equalize the osmotic pressure, causing animal cells to swell and potentially burst. Plant cells swell and the cell wall pushes against the cell membrane creating turgor pressure. This is the usual condition of plant cells.
86 Active TransportActive Transport: Type of cellular transport that does require energy because materials are being transported against the concentration gradient (low to high)2 Types of Active Transport:Bulk Transport: Transporting large materials into or out of the cell membraneEndocytosis: Taking material into the cellExocytosis: Taking material out of the cellMembrane Pump: Using proteins in cell membranes to pump materials across the cell membrane
87 Osmoregulation in Different Environments Each species has a range of environmental osmotic conditions in which it can function:Stenohaline – Organisms that tolerate a narrow range of salinities in external environmentEuryhaline – Organisms that tolerate a wide range of salinities in external environment:short term changes:estuarine ‰, intertidal - 25 – 40‰long term changes:Diadromous fishes -spend part of life in salt water, part in freshwaterCatadromous – live in freshwater and migrate seaward to spawn ex. eelsAnadromous – born in freshwater, live in sea, migrate up river to spawn ex. salmon and sturgeon
88 OsmoregulatorsOsmoregulators: Organisms that can adapt to changes in salinity of the surrounding seawaterOsmoregulators use active transport to maintain a stable internal salinity so this requires the use of energyHelps conserve loss of freshwater from their bodiesExamples include most vertebrate fish, sharks, etc.B/c they can adapt to changing salinities they survive in variations of salinities…
89 Osmoregulation: Sharks vs Bony Fish Maintain internal salt concentrations lower than seawater by pumping salt out through rectal glands and through the kidneys, yet their osmolarity is slightly hypertonic to seawater.Sharks retain urea as a dissolved solute in the body fluids.Sharks also produce and retain trimethylamine oxide (TMAO), which protects their proteins from the denaturation by urea.Retention of these organic solutes (urea, TMAO) in the body fluids actually makes the slightly hypertonic to seawater.Do not drink water, but balance osmotic uptake of water by excreting urine.MARINE BONY FISHMarine bony fishes are hypotonic to seawater.Compensate for osmotic water loss by drinking large amounts of seawater and pumping excess salt out with their gill epithelium.Excrete only a small amount of urine.
92 Osmoconformerdangerous-animals-pets.blogspot.comOsmoconformers: Organisms that cannot adapt to changing salinities.Internal salinities rises and falls with the waters surrounding themPassive transport occurs in these organisms so no energy is neededSome osmoconformers do well in changing salinities but most do NOTExamples include many Hagfish and invertebrates like:MollusksJellyfishSquidOctopusphys.org