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71 Cards in this Set
- Front
- Back
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What is special about Earth concerning water?
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All three phases of water exist in large quantities on Earth.
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What percentage of Earth's water is in the oceans?
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>97%
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What are the steps of a general biogeochemical cycle?
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erosion, transport, precipitation/deposition, compaction and reexposure/volcanism
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What can complicate the general biogeochemical cycle?
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marine organisms and hydrothermal vents
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Why are concentrations and input/output rates assumed to be constant?
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While some processes last millions of years, they are assumed to have behaved similarly for billions of years, reaching a steady state.
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Do the relative concentrations of dissolved chemicals in the ocean vary much?
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Some such as nutrients vary seasonally and regionally, but not annually.
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What is residence time?
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the average time a certain element's atom spends in the ocean
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How was/is salinity measured?
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Originally it was by evaporation and weighing of salts, but that lost Br, I, and others. Measurement of the chloride concentration and electrical conductivity dominate today.
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What is the range of ocean residence times of common dissolved ions?
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Chloride is 80M years, and aluminum and iron are just 100 years.
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What units does salinity have?
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originally parts per thousand (o/oo), now Practical Salinity Units (PSU)
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Why is salinity measured in PSU now?
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Since electrical conductivity has become the main method for measurement but it only works as a comparison, the need grew for standard solutions all over. Instead of making a bunch of standard solutions, they redefined salinity in terms of electrical conductivity.
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What accuracy for salinity can be achieved in the lab?
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It can be measured to the nearest .001 (PSU).
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What are the six dissolved constituents of seawater, from greatest concentration to least concentration?
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chloride, sodium, sulfate, magnesium, calcium and potassium
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What is the divide between major and minor constituents?
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100 parts per million
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What are the six minor dissolved solid constituents?
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bromine, carbon, strontium, boron, silicon, and fluorine
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What percentage by mass of the dissolved load do the major dissolved constituents make?
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99.28%
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What percentage by mass do the trace elements make?
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.4%
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What dissolved constituents are measured to the highest accuracy?
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radionuclides
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What are some examples of dissolved organic compounds?
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proteins, carbohydrates, lipids, amino acids, vitamins, petroleum hydrocarbons and synthetic compounds like DDT and PCBs
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How do organic compounds get into the ocean?
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They are excreted by marine organisms, dissolved after death or enter in runoff from mangrove swamps and salt marshes (gelbstoff).
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What are the three major dissolved gases in the ocean?
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N2, O2 and CO2
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How many times more CO2 is dissolved in the oceans than the atmosphere (including bicarbonate and carbonate)?
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70 times
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Why is carbon dioxide so prevalent in the ocean when it is only .04% of the atmosphere?
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It reacts to make carbonic acid, which can deprotonate to bicarbonate and carbonate ions.
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Where in the ocean are oxygen and carbon dioxide more concentrated?
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Oxygen is at higher concentrations at the surface, while there is more carbon dioxide at depth.
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What factors influence how much O2 and CO2 are in a water mass?
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photosynthesis and respiration/decomposition
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What effects do temperature, pressure and salinity have on saturation solubility of gases?
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Higher pressures, lower temperatures, and lower salinities contribute to higher solubilities.
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What are the five minor dissolved gases primarily produced by marine organisms and lost to the atmosphere?
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N2O, CO, CH4, CH3I, and (CH3)2S
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What does sulfur dioxide do?
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It is produced by burning of fossil fuels and dissolved in the ocean.
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What is the pH range of seawater?
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7.5 to 8.1
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What are the components of the buffering system present in seawater?
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CO2(g), H2CO3, HCO3- and CO3(2-)
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What are seven anomalous properties of water?
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high heat capacity, high latent heat of fusion, high latent heat of vaporization, low-density solid state, "universal solvent", high surface tension, and present on Earth in all three states
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What is hydration?
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when ions are surrounded by water molecules, removing them from the crystal
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As the Van der Waals forces increase, what happens to the boiling point and freezing point of a substance?
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both increase
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What causes the extra high boiling points of H2O, HF and NH3?
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hydrogen bonding, when hydrogen is bonded to a highly electronegative atom (N, O, and F)
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What are the heat capacities of the three states of water?
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Liquid water is 1 calorie per gram degree Celsius, while steam and ice are both .5 calories per gram degree Celsius.
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What are the latent heats of fusion and vaporization of water?
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fusion: 80 calories per gram; vaporization: 540 calories per gram
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What impacts do the anomalous thermal properties of water have for the ocean?
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Large amounts of heat can be stored with little temperature change; thermal inertia buffers coastal climate; polar ice keeps the temperature at high latitudes fairly constant.
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What effect does evaporation have on the remaining water?
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It cools the remainder.
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What impact does pressure have on water density?
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Liquids are incompressible, so pressure has a very little effect (2% increase at 1k atm).
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What impact does temperature have on water density?
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Increased temperature decreases density except below 3.98°C (for pure water, due to ice-like clustering).
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What impact does salinity have on water density?
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Dissolved substances are more dense and prevent clustering, so increased salinity increases density.
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Which has a greater effect on water density, temperature or salinity?
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When dealing with freshwater versus seawater, the salinity has a larger effect than any temperature change, but since ocean salinities are fairly constant (99% is 33-37), temperature changes have the most noticeable effect. However, in polar regions, where temperature is fairly constant, salinity is the primary factor governing density.
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Where are the highest seawater temperatures?
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hydrothermal vents, then tropical surface waters
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What effects does an increase in salinity have on freezing water?
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Both the density maximum and freezing point decrease (because of cluster inhibition), the former more rapidly than the latter, meeting at salinity 24.7.
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What effect does the density maximum have on freshwater lakes?
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The water is cooled and mixed ("overturning") until it is all at 4°C, then the surface water cools while the bottom water remains at 4°C.
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What happens to salinity when water freezes?
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Dissolved ions are expelled, and salinity of the surrounding water increases.
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What is the biological effect of the lower density of ice?
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Organisms can survive below the meter or two of ice on the surface.
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What is surface tension?
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the attractive force felt by molecules (or atoms) on the edge of a liquid towards the center; an avoidance of an increase in surface area
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Oceanographically, what are three effects of water's high surface tension?
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Small waves (capillary waves) are dissipated by the surface tension of water. Low mass objects such as razor blades can be made to float on water's surface. Gas bubbles are retained by surface water molecules.
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What is the surface microlayer?
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the very top layer of the ocean only a few molecules thick, important biologically
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What is viscosity?
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an liquid's internal resistance to flow or movement of an object through it
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What effect does temperature have on water viscosity?
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Increased temperatures mean decreased viscosities.
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What effect does salinity have on water viscosity?
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Increased salinity means a slightly increased viscosity.
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What is transmitted more easily through water, light or sound?
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sound
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Which colors of visible light are more readily absorbed, and which are transmitted?
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Red is absorbed, while blue and green are transmitted.
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What can contribute to the attenuation of light in seawater?
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turbidity, suspended sediment, and plankton
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Why does water appear blue?
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Blue light is absorbed less, and therefore is more likely to be backscattered.
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What can make water not blue?
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Green phytoplankton or brown suspended sediment can dominate the color.
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What can cause a scuba diver to be unable to differentiate up from down?
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when backscattering is as common as regular transmission and all directions look the same
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What causes the apparent dislocation of objects between water and air?
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refraction
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What effect does salinity have on refraction?
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Refraction increases as salinity increases.
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What is the speed of sound in seawater approximately?
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between 1400 and 1500 m/s
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How does sonar work?
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Given the speed(s) of sound, the time is measured for a pulse to be reflected off of plankton, fish schools, mineral grains, submarines, etc.
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Which frequencies are used in sonar?
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High frequencies for short-range small objects and low frequencies for long-range large objects.
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What effects do temperature and salinity have on the speed of sound in seawater?
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Both increase it, temperature more than salinity.
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How does the speed of sound change with depth?
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As one descends, the speed of sound increases, then decreases, then increases again.
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What goes on at the sound velocity maximum?
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There's a shadow zone, into which surface-emitted sound cannot reach and in which submarines can hide.
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What goes on at the sound velocity minimum?
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It's called the sound channel because sound is focused at this layer, with energy in proportion to the inverse of the distance, not the inverse square.
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What is ATOC?
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Acoustic Thermography of Ocean Climate, began in 1991 on the premise of using the speed of sound in seawater to measure temperature
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What are three contributors to ocean noise?
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breaking waves and bursting air bubbles, vessels and other man-made objects, and biological noises
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What are examples of biological noises?
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Whales/dolphins use sonar to detect prey; crustaceans make clicking noises, and fish with swim bladders make noises inflating and deflating them.
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