Oceanography 2 (Ocean salts)

How does hydrothermal activity act as a removal mechanism for ocean salts? -what elements does it remove?

It removes magnesium due to the high temperature processes other Ca ans S minerals removed as well

describe Forchhammer's principle / principle of constant proportions

Ratio of dissolved solids is constant between localities even if the concentrations differ!

Ocean Salinity Is Mostly ____ and _____ Ions

Sodium; Chlorine

Sea water contributes to the composition rainwater but the rainwater contributes to the composition of sea water. Why does rainwater contain high CL content?

because of the sea spray from the ocean. this is a cyclic salt for it it transfered from the ocean to the atmosphere and from the atmosphere back into the ocean

What are the components of geochemical cycles?

resevior: volume that contains the material

What are the different Processes That Regulate the Major Constituents in Seawater?(4 major) which act as sources AND sinks?

-river transfer of elements to the ocean -Volcanoes can act as a source of elements to the ocean -Hydrothermal vents can act as a source and sink for elements in the ocean -particles and biological processes in the water column and sediments act as sources and sinks too

Removal mechanisms of ocean salts:

1. Deposition of biogenic materials -sulfur -silica -calcite 2. Deposition of evaporites 3. Hydrothermal Activity

What are the sources of chloride from the ocean into the atmosphere?

1. sea spray 2. excess volatiles (substance that vaporizes readily) from volvanic activity

residence time 2. how do you figure out an elemts resident time?

1. the average length of time during which a substance stays in a system 2. amount of element in ocean/rate at which element is added or removed

1. Describe the principle of constant proportions -what are exceptions to this principle?

1. the ratios of major ions are constan in oceanst, regardless of variations in salinity, exceptions: -coastal areas with large inputs of fresh water -minor constituents -biologically active

Salinity of the ocean

35 psu (practical salinity units)

• The average time water stays in the ocean (residence time) is _____ years. • The residence time of water in the air is ~____days.

4,100 years 9 days

~_____%of all water entering the atmosphere evaporates from the ocean. The rest is from land. -_____%of precipitation falls back on the ocean

85% 80%

Earth has about 1.37 billion cubic kilometers of water. About _____% is the ocean. _____ % is glaciers. _____% is groundwater, rivers, lakes, wetlands.

97.5% 1.8% 0.46%

Gasses dissolve in sea water. Do higher or lower water temperatures can hold more gas in a solution?

Cold water can hold more gas in solution than warm water

How do marine organisms contribute to inputs and outputs of ocean salts? (hint. 3 compunds) -what compounds -they are major resevoirs of which elements? (3)

Control inputs and outputs of calcite (CaCO3): calcite is precipitated as hard parts of marine organisms (ex. Mollusks) . algae - coccolithophorid (coccoliths) pyrite (FeS) -formed in sediments silica -formed by organisms such as diatoms . major reservoirs of Ca, S and Si

What does it mean that the ocean is in chemical equilibrium? -how long have salt contents been constant for?

The ocean is in steady state! Inputs = outputs• -concentration of elements are neither increasing or decreasing -salt contents have been nearly constant for millions of years!

Seawater Consists of _____ and ______

Water; Dissolved Solids

solution

a liquid mixture in which the minor component (the solute) is uniformly distributed(homogonously dispersed) within the major component (the solvent).

What is an ion? How do they move through water in solution?

a molecule with unbalanced charge by diffusion • Saturation - no more will dissolve • Precipitation - forming crystals from solution

adsorbtion ex:

adherence of ions onto a surface ex: clay minerals supplied from continental weathering absorb ions and settle to form sediments

residence time depends on what?

an ions activity

For a given element... +/- a neutron = _____ +/- a proton =______ +/- an electron = ______

an isotope a new element an ion

The oceans havent gotten saltier over time because theyre in chemical equalibrium. What does this infer?

concentration of salts is constant (steady state)

Though salinity may vary with location, the ratio of dissolved solids in seawater is ______

constant

What is the major output(via deposition) of silica in the ocean?

diatoms (phytoplankton) radiolarian (amoeboid protozoan)

If the rates of input/output are greater than the ocean mixing time, then they will be ________ If the rates of input/output are less than the ocean mixing time, there is ______

evenly distributed throughout the ocean. the potential for large-scale spatial variability.

Deposition of evaporites: -embayments become isolated from the ocean and experience due to _____ -salt deposits left behind = _____ - only 0.004 to 0.02 % of ocean need evaporate each year to remove river input of ____ and _____

extensive evaporation evaporites sulfate;cl

Water cycles constantly in the _______ cycle

hydrologic cycle

Only major output of magnesium from the oceans is what process? - entire volume of ocean is cycled through vents every ___myr

hydrothermal activity 3

Properties of Sea water: Heat capacity decreases with _____ salinity Salinity increases; freezing point ______ (why do we salt the roads?) Salinity increases; evaporation _____ (salts attract water molecules, slowing the process, consider sweating for example...) Salinity increases; osmotic pressure _______ (this is important for cells)

increasing decreases slows increase

The residence times of elements in the ocean differ depending on their rates of ______

input and output.

Salt in a solution: Most salts are held together by bonds based on electrical charges (______) The polar water molecule is efficient at breaking these bonds, aka _____ the salts.

ionic bonds dissolving

chloride content of continental rocks is very (high/low)?

low

salinity -ocean salinity varies by?

measure of dissolved inorganic solids • Ocean salinity varies by about 3.3% to 3.7% by mass.

ion exchange -what ion replaces sodium

occurs when some ions have a greater affinity for clays than others and replace them -potassium replaces dosium

If the concentration of an element is high and has a high residence time in the ocean that exceeds the mixing time you would expect ______ concentrations between locations. if residence time(which is based on inputs and outputs) is lower than mixing time then you would expect concentrations to ____ between location

similar vary

How is sulfur removed (via deposition) in the ocean? half of S entering ocean removed as:

via sulfate reduction and precipitation half of S entering ocean removed as iron sulfides, FeS and FeS2

Atmospheric sources of ocean salts come from? where does the Cl come from? what is is classified as?

volcanism -. HCl a common volcanic gas. - Cl classified as a excess volatile -the gas is released from crystalline rock from inside the mantle

How does river input contribute as a sourse of ocean salts? what are some problems with this?

weathering of continental rocks dissolves ions into river water which runs into ocean Problems: . seawater salts 300 times more concentrated than river water -evaporation . relative abundance of ions differs. -rivers high in Ca, HCO3 and SiO2 composition of saline lakes not at all like seawater - Dead Sea 60% MgCl, - only 20% NaCl - salinity = 240 PSU

What are the different sources that contribute to ocean salinity from the Earths crust?

• Weathering of surface rock -weathering of continental rocks dissolves ions into river water • Excess volatiles - from outgassing