Ocean Water

Why is the ocean salty?

What is a salt?

Salts are made from Ions

Elements Electrons (-) Elements in the periodic table have equal numbers of protons (+) and electrons (-). They are electrically neutral Protons (+)

Ions Ions are stable forms of elements that acquire an electrical charge by gaining or losing electrons Elemental Sodium (Na) 11 protons (+), 11 electrons (-) Sodium ion (Na+) 11 protons (+), 10 electrons (-) By losing an electron, sodium has more protons than electrons and becomes positively charged. Na - 1e- = Na+

+ Sodium Na Na Na+ 11 protons e- e- e- Much more stable It is anxious, if fact, desperate to lose that electron and assume its more stable form.

2Na + 2H20 2Na+ + 2 OH- + H2 http://video.google.com/videoplay?docid=-2158222101210607510&ei=syO5SuaVBJLiqgKWif37AQ&q=sodium+explosion&hl=en#

Ions Ions are stable forms of elements that acquire an electrical charge by gaining or losing electrons Elemental Chlorine (Cl) 17 protons (+), 17 electrons (-) Chloride ion (Cl-) 17 protons (+), 18 electrons (-) By gaining an electron, chlorine has more electrons than protons and becomes negatively charged. Cl + 1e- = Cl-

Chlorine _ e- e- e- e- Cl Cl- 17 protons Much more Stable

Elements that lose electrons and become positively charged are called cations. Na+, K+, Ca2+, Mg2+, Cu2+, Fe3+ Elements that gain electrons and become negatively charged are called anions. Cl-, Br-, F-, I- CO32-, SO42-, PO4-3 oxoanions

Salts Salts are formed by combining cations and anions to form solids that have no charge. Cations: K+, Na+, Mg2+, Ca2+ Anions: Cl-, CO3-2, SO4-2 K+ + Cl- = KCl Na+ + Cl- = NaCl KCl, NaCl, MgCl2, CaCO3, CaSO4

KCl K+ + Cl- NaCl Na+ + Cl- Conversely, if solid salts are mixed with water they dissolve and the ions go into solution solid solution Water KCl K+ + Cl- Water NaCl Na+ + Cl- CaCO3 CaSO4 Ca+2 and CO3-2 Ca+2 and SO4-2

Dissolution Cl- Cl Cl Na Cl Cl NaCl Na+

Oceans have enormous amounts of salt (ions) dissolved in the water. Where does it come from?

90% of rainfall is on the oceans 10% So far, we have considered the largest portion of the hydrologic cycle, the oceans, particularly with respect to their integrative effect on climate and heat distribution on earth. We’ve also discussed precipitation and rainfall and it’s causes. Remember that 90% of surface evaporation comes from the ocean and in turn about 90% of all precipitation returns to the oceans. This leaves only 10% that reaches the land. We’ll now begin to examine what happens to precipitation that strikes land in the form of fresh water; specifically, rivers, lakes, soil water, and groundwater. 90% of rainfall is on the oceans

Fate of Precipitation to Land Evaporation / Transpiration Infiltration to Soil/Soil flow Overland Flow (Runoff) Aquifers/ Groundwater Exchange and transport of freshwater in the terrestrial environment is complex and varied, but basically, water that falls to the earth is subject to well known fates. Much of precipitation falling on land is subject to evaporation or transpiration by plants and is therefore returned to the atmosphere. Another fraction infiltrates the soil becoming part of the soil water reservoir. However, if rainfall volume exceeds the ability of the soil to accept it, water flows over the land as runoff. Water that infiltrates the soil is constantly in flux. Some moves within the soil or is stored there. Another fraction is withdrawn by plants or moves to lakes, rivers and streams. Some, however is subject to percolation to groundwater. Aquifer or groundwater storage and transport is vitally important and comprises the largest of our readily available freshwater resources. Streams, Rivers, Lakes

Watershed River basin Drainage basin Catchment Total land area that drains surface water to a common point. River basin Drainage basin Catchment Recall that a watershed is the total land area that drains water to a common point. Thus, in terms of freshwater resources, the watershed encompasses all of the available freshwater reservoirs and the exchange of freshwater between them. Rain that falls anywhere within a given body of water's watershed or basin will eventually drain into that body of water.

Amazon Watershed Atlantic

Watersheds, Erosion and Dissolution rain rain salts salts Dissolution of salts; erosion of rocks and minerals

Minerals and Erosion Feldspars KAlSi3O8 CaAl2Si2O8 NaAlSi3O8 water KAlSi3O8 CaAl2Si2O8 NaAlSi3O8 water K+, Ca2+, Na+, Si4+ granite water Dissolved in water

Dissolved Salts and Minerals KAlSi3O8 CaAl2Si2O8 NaAlSi3O8 KCl NaCl MgCl2 CaCO3 CaSO4 Rivers contain small amounts of dissolved salts that are delivered to the oceans

Amazon Watershed Atlantic K Na Mg Cl Ca CO3 SO4 Si

Total Salts If rivers have low salt contents and they Rivers < 500 mg/L Oceans 35,000 mg/L If rivers have low salt contents and they are delivering salts to the oceans, why do oceans have such high salt contents?

evaporation Salts left behind The primary factor leading to ocean salinity.

Salts are delivered to the oceans in small amounts Evaporation removes water from the oceans, but leaves the salts behind. Rainfall on land dissolves more salts, which are subsequently delivered to the oceans

Microcosm: The Dead Sea 34% salt content Endorheic sea Elevation: 1400 ft below sea level Lowest dry elevation on earth The sea is called "dead" because its high salinity means no fish or macroscopic aquatic organisms can live in it, although bacteria and microbial fungi are present. The salinity of the Dead Sea varies according to depth with the surface water being approximately 15% saline (5 times the average ocean salinity) and water near the bottom being saturated, such that salt precipitates out of solution onto the sea floor. The mineral content of the Dead Sea is significantly different from that of ocean water, consisting of approximately 53% magnesium chloride, 37% potassium chloride and 8% sodium chloride (table salt) with the remainder comprised of various trace elements. The concentration of SO4 ions is very low, and the bromine ions concentration is the highest of all waters on Earth. Chlorides neutralize most of the calcium ions in the Dead Sea and its surroundings. While in other seas NaCl is 97%, in the Dead Sea the quantity of the NaCl is only 12-18 percent. The water temperature goes from 19 degrees Celsius in February to 31 degrees Celsius in August. 59 inches of Evaporation/yr

The Dead Sea is Dying 10% of natural flow now reaches the sea. Salt Works 1973 10% of natural flow now reaches the sea. Salt works, installed in what was the shallow southern basin of the Sea prior to its separation from the northern basin in the 80s, also contributes to the shrinking of the Sea. The evaporation ponds fed by water pumped in main water body are said to be responsible for 25-30% of the total evaporation of Dead Sea water. 1987 Sea levels are dropping by 3 ft/yr 2000

Great Salt Lake 5 to 27% Salt Content Jordan Weber Bear Remnant of Lake Bonneville. Catastrophic water loss around 15,000 years ago lower lake bonneville by about 350 feet. Railroad causeway one inch to six feet thick Remnant of Lake Bonneville (15,000 years ago)

Amu Darya and Syr Darya rivers The Aral Sea (up to 8% salinity) 60% loss in area 80% loss in volume In 1965, USSR tapped the lake for irrigation to develop surrounding economies. Today the sea is less than 1/2 its previous area. Increased salinity has killed all the fish (4.5%). 95% of its former inputs are now diverted. It was the 4th largest lake in 1950 and now has lost 60% of its area and 80 % of its volume. Amu Darya and Syr Darya rivers

Oceans and Rivers 4 billion tons of dissolved salts to the ocean annually

What kind of Salts?

River Salt Composition Carbonate Calcium Sulfate Silicate Chloride Sodium Magnesium Potassium River Water 35.15 20.39 12.14 11.67 5.68 5.79 3.41 2.12 KCl NaCl MgCl2 CaCO3 CaSO4 KAlSi3O8 CaAl2Si2O8 NaAlSi3O8 Dominated by Carbonate, Calcium, Sulfate, and Silicate

Ocean Salt Composition Chloride Sodium Sulfate Magnesium Calcium Potassium Carbonate Silicate Sea Water (%) 55.04 30.62 7.68 3.69 1.15 1.10 0.40 .0004 2.9% Na+ and Cl- In the beginning the primeval seas must have been only slightly salty. But ever since the first rains descended upon the young Earth hundreds of millions of years ago and ran over the land breaking up rocks and transporting their minerals to the seas, the ocean has become saltier. It is estimated that the rivers and streams flowing from the United States alone discharge 225 million tons of dissolved solids and 513 million tons of suspended sediment annually to the sea. Recent calculations show yields of dissolved solids from other land masses that range from about 6 tons per square mile for Australia to about 120 tons per square mile for Europe. Throughout the world, rivers carry an estimated 4 billion tons of dissolved salts to the ocean annually. About the same tonnage of salt from the ocean water probably is deposited as sediment on the ocean bottom, and thus, yearly gains may offset yearly losses. In other words, the oceans today probably have a balanced salt input and outgo. Past accumulations of dissolved and suspended solids in the sea do not explain completely why the ocean is salty. Salts become concentrated in the sea because the Sun's heat distills or vaporizes almost pure water from the surface of the sea and leaves the salts behind. This process is part of the continual exchange of water between the Earth and the atmosphere that is called the hydrologic cycle. Water vapor rises from the ocean surface and is carried landward by the winds. When the vapor collides with a colder mass of air, it condenses (changes from a gas to a liquid) and falls to Earth as rain. The rain runs off into streams which in turn transport water to the ocean. Evaporation from both the land and the ocean again causes water to return to the atmosphere as vapor and the cycle starts anew. The ocean, then, is not fresh like river water because of the huge accumulation of salts by evaporation and the contribution of raw salts from the land. In fact, since the first rainfall, the seas have become saltier. (85% of total) Dominated by Chloride, Sodium, and Sulfate

} } Percentage of Total Dissolved Minerals River Water Ion Sea Water Carbonate Calcium Silicate Sulfate Chloride Sodium Magnesium Potassium River Water 35.15 20.39 11.67 12.14 5.68 5.79 3.41 2.12 Sea Water .40 1.15 .0004 7.68 55.04 30.62 3.69 1.10 } 79% } 85% Carbonate, calcium and silicate are disappearing Chloride and sodium are appearing

River Water has high amounts of Calcium, Carbonate, and Silicate Ocean Water has high amounts of Sodium and Chloride If ocean salts come from rivers, some process is removing calcium, carbonate, and silicates from the river water, and sodium and chloride are being enriched in ocean waters.

Alterations Enrich Sodium, Chloride in ocean water Remove Silica, Calcium, Carbonate from river water No known biological process removes sodium from the sea. Therefore, it is very abundant in sea water. Certain constituents in sea water, such as calcium, magnesium, bicarbonate, and silica, are partly taken out of solution by biological organisms, chemical precipitation, or physical-chemical reactions Part of the explanation is the role played by marine life -- animals and plants -- in ocean water's composition. Sea water is not simply a solution of salts and dissolved gases unaffected by living organisms in the sea. Mollusks (oysters, clams, and mussels, for example) extract calcium from the sea to build their shells and skeletons. Foraminifers (very small one-celled sea animals) and crustaceans (such as crabs, shrimp, lobsters, and barnacles) likewise take out large amounts of calcium salts to build their bodies. Coral reefs, common in warm tropical seas, consist mostly of limestone (calcium carbonate) formed over millions of years from the skeletons of billions of small corals and other sea animals. Plankton (tiny floating animal and plant life) also exerts control on the composition of sea water. Diatoms, members of the plankton community, require silica to form their shells and they draw heavily on the ocean's silica for this purpose

NaCl Solubility 350 g/L Enriching Sodium and Chloride Solubility: ease of dissolution in water sodium, potassium, and ammonium salts are soluble chloride, bromide and iodide salts are soluble. Once these types of ions reach the oceans they stay dissolved 350 g/L = 0.75 lb/L NaCl Solubility 350 g/L

Calcium Carbonate Removal Remove Silica, Calcium, Carbonate Incorporate into shells of marine invertebrates Depends on pH and Co2 Ca2+ + CO32- = CaCO3

Life and Silica Diatoms Use silica as structural material Remove Silica, Calcium, Carbonate Diatoms Diatoms (Gr. dia 'through'; tomos 'cutting', i.e., "cut in half") are a major group of eukaryotic algae, and are one of the most common types of phytoplankton. Most diatoms are unicellular, although some form chains or simple colonies. A characteristic feature of diatom cells is that they are encased within a unique cell wall made of silica. These walls show a wide diversity in form, some quite beautiful and ornate, but usually consist of two symmetrical sides with a split between them, hence the group name. Diatoms in both fresh and salt water extract silica from the water to use as a component of their cell walls (“test”, “shell”). Likewise, some holoplanktonic protozoa (Radiolaria), some sponges, and some plants (leaf phytoliths) use silicon as a structural material. The richest sources of diatom fossils are deposits of their skeletons known as diatomite, or diatomaceous earth. This mineral was formed as ancient diatoms died and settled to the bottom of lakes or oceans. Today, they form large deposits of white chalky material, which is mined for use in cleansers, paints, filtering agents, and abrasives. Many toothpastes contain bits of fossil diatoms. The Bacillariophyta are the diatoms. With their exquisitely beautiful silica shells Use silica as structural material

Percentage of Total Dissolved Minerals River Water 35.15 20.39 11.67 5.68 5.79 3.41 2.12 12.14 Sea Water .40 1.15 .0004 55.04 30.62 3.69 1.10 7.68 Ion Carbonate Calcium Silicate Chloride Sodium Magnesium Potassium Sulfate

Other Constituents in Ocean Water

The Oceans and Carbon Dioxide Chemical interaction between the Oceans and the Atmosphere

Gases Dissolve in Water Constant interchange of gases at the surface of the oceans Oxygen slips into "pockets" that exist in the loose hydrogen-bonded network of water molecules without forcing them apart. The oxygen is then caged by water molecules, which weakly pin it in place. dissolution 45

Composition of the Atmosphere Gases Nitrogen 78.1% Oxygen 20.9% Argon 0.93% CO2 0.038%

Oxygen Solubility: 0.043 g/L (20oC) 47 The diffusion of oxygen is often of great importance in relation to water, particularly in lakes and rivers. Oxygen contents dictate in many ways the life limits of aquatic organisms. We will explore in some detail the factors controlling oxygen contents in water particularly in relation to temperature. The solubility of oxygen is greater in colder water than in warm water. 47

Carbon Dioxide - + O C O -

Carbon Dioxide

CO2 Solubility = 1.69 g/L Between 1800 and 1994, the 380 ppm CO2 Solubility = 1.69 g/L (Oxygen Solubility: 0.043 g/L) Analysis of CO2 levels in ice cores have shown scientists that for the 400,000 years before the industrial revolution began in the 1800s, atmospheric CO2 concentrations remained between 200 and 280 parts per million. Today CO2 levels are reaching 380 parts per million in the atmosphere. “If the ocean had not removed 118 billion metric tons of anthropogenic carbon between 1800 and 1994, the CO2 level in the atmosphere would be about 55 parts per million greater than currently observed,” said Sabine. ocean removed about 118 billion metric tons. Between 1800 and 1994, the 48 percent of all fossil fuel emissions Middle Ages Industrial Revolution 50

Present and Future Problems Gases/Heat Gas Solubility = 1.69 g/L Oxygen Solubility: 0.043 g/L

Carbon Dioxide also is an Acid

Dissolution of Carbon Dioxide CO2 + H2O H2CO3 H2CO3 H+ + HCO3- H+ is acid CO2 Water Acid Acids (H+) are reactive and dissolve a number of substances

Copper and Silver Cleaning: CuO + 2HCl → CuCl2 + H2O View edEx's map Taken in a place with no name (See more photos or videos here) Ag2O + 2 HCl → 2 AgCl + H2O CaCO3 Fe2O3 + 6H+ 2Fe3+ + 3H2O Fe2O3 CaCO3 + H+ Ca2+ + HCO3-

Invertebrate shells and skeletons largely CaCO3 “It isn’t just the coral reefs which are affected – a large part of the plankton in the Southern Ocean, the coccolithophorids, are also affected. These drive ocean productivity and are the base of the food web which supports krill, whales, tuna and our fisheries. They also play a vital role in removing carbon dioxide from the atmosphere, which could break down WASHINGTON - Nearly half the excess carbon dioxide emitted into the air by humans over the past two centuries has been taken up by the ocean, according to a study published in the new issue of the journal Science. An accompanying report stated that if the trend continues, it could damage the ability of corals, snails and plankton to make their shells. Invertebrate shells and skeletons largely CaCO3 Corals, “lithic” plankton, clams, oysters 56

CO2 H+ CaCO3 + H+ Ca2+ + HCO3- Water pH change: 8.179 to 8.104 Acidification of the oceans Inhibits the calcification and growth of invertebrates 17% increase in H+ concentrations. “It isn’t just the coral reefs which are affected – a large part of the plankton in the Southern Ocean, the coccolithophorids, are also affected. These drive ocean productivity and are the base of the food web which supports krill, whales, tuna and our fisheries. They also play a vital role in removing carbon dioxide from the atmosphere, which could break down Analysis of CO2 levels in ice cores have shown scientists that for the 400,000 years before the industrial revolution began in the 1800s, atmospheric CO2 concentrations remained between 200 and 280 parts per million. Today CO2 levels are reaching 380 parts per million in the atmosphere. “If the ocean had not removed 118 billion metric tons of anthropogenic carbon between 1800 and 1994, the CO2 level in the atmosphere would be about 55 parts per million greater than currently observed,” said Sabine. The results of our study were visibly obvious and may provide a glimpse into the future. We saw a 92-percent decrease in the area covered by crustose coralline algae in the tanks with lower pH compared with tanks at the pH level of today's ocean. Non-calcifying fleshy algae increased by 52 percent," said Kuffner. "These findings suggest that at lower pH, the reef-building algae could be much less competitive on future coral reefs." Based on our present knowledge, it appears that as seawater CO2 levels rise the skeletal growth rates of calcareous plankton will be reduced as a result of the effects of CO2 on calcification,” said Victoria Fabry, a biologist at California State University at San Marcos and a paper co-author. Recent studies have shown that calcification rates can drop by as much as 25 to 45 percent at CO2 levels equivalent to atmospheric concentrations of 700 to 800 parts per million. Those levels will be reached by the end of this century if fossil fuel consumption continues at projected levels. Analysis of coral cores shows a steady drop in calcification over the last 20 years http://www.npr.org/templates/story/story.php?storyId=17243164 57

Coral Reef Bleaching Scleractinian corals receive their nutrient and energy resources in two ways. They use the traditional cnidarian strategy of capturing tiny planktonic organisms with their, as well as having a symbiotic relationship with a single cell algae known as zooxanthellae. Zooxanthellae are autorophic microalgaes   Zooxanthellae live symbiotically within the coral polyp tissues and assist the coral in nutrient production through its photosynthetic activities. These activities provide the coral with fixed carbon compounds for energy, enhance calcification ,and mediate elemental nutrient flux. The host coral polyp in return provides its zooxanthellae with a protected environment to live within, and a steady supply of carbon dioxide for its photosynthetic processes. The symbiotic relationship allows the slow growing corals to compete with the faster growing multicellular algaes because the tight coupling of resources and the fact that the corals can feed by day through photosynthesis and by night through predation.   Three hypotheses have been advanced to explain the cellular mechanism of bleaching, and all are based on extreme sea temperatures as one of the causative factors. High temperature and irradiance stressors have been implicated in the disruption of enzyme systems in zooxanthellae that offer protection against oxygen toxicity. Photosynthesis pathways in zooxanthallae are impaired at temperatures above 30 degrees C, this effect could activate the disassociation of coral / algal symbiosis. Low- or high-temperature shocks results in zooxanthellae low as a result of cell adhesion dysfunction. This involves the detachment of cnidarian endodermal cells with their zooxanthellae and the eventual expulsion of both cell types. Corals live in very nutrient poor waters and have certain zones of tolerance to water temperature, salinity, UV radiation, opacity, and nutrient quantities.  58

Anthropogenic Inputs

Homework II Oceanic Dead Zones This is an excerpt from a news story from June 21 by the AP concerning recent Mid-west flooding and its potential impact on the dead zone in the Gulf of Mexico. Flood, size of gulf dead zone linked Extra farm runoff in the Mississippi to increase area with no oxygen Associated Press June 21, 2008 WASHINGTON - Floodwaters loaded with farm runoff are heading down the Mississippi River, and scientists fear that the deluge will sharply increase the expected dead zone this summer in the Gulf of Mexico, covering an area the size of Maryland. The dead zone is a region of the gulf that becomes starved for oxygen during much of the summer and cannot support fish or other sea life. There are hundreds of dead zones around the world that wreak havoc on marine ecology and cut off vast areas for commercial fishing. The zone in the gulf is the largest in the Western Hemisphere.