Marine Water

n Marine waters may be fully saline, brackish or almost fresh. Marine habitats include those below spring high tide limit (or below mean water level in non-tidal waters) and enclosed coastal saline or brackish waters brackishhabitat springwater brackishwaterbrackishhabitat springwater brackishwater

Physical Characteristics

n Salinity n Temperature n Density n pH

Salinity n Salinity is the saltiness or dissolved salt content of a body of water. saltwatersaltwater

n The salinity of seawater is usually 35 parts per thousand in most marine areas. This salinity measurement is a total of all the salts that are dissolved in the water.

Factors Affecting Salinity n The relative amount of evaporation or precipitation in an area. n Due to a very large river emptying into the ocean. n The freezing and thawing of ice.

Salinity map showing areas of high salinity (36 o/oo) in green, medium salinity in blue (35 o/oo), and low salinity (34 o/oo) in purple.

Temperature n Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. physical propertyhotcoldphysical propertyhotcold

n The temperature of seawater varies with the amount of sun that hits that area. This includes the length of time as well as the angle of the sun's rays. The longer the time and the more direct the rays of the sun fall on the ocean, the greater the temperature of seawater.

The three layered ocean with the upper mixed layer (yellow), main thermocline (light blue), and deep (bottom) water (deep blue).

n The upper mixed layer is all one temperature but that temperature can vary from -2 degrees C, at the poles, to +30 degrees C, in the tropics. n The main thermocline is an area of rapidly decreasing temperature with depth. n Deep (or bottom) water is always one cold temperature ranging between -2 to +5 degrees C.

Density n The mass density or density of a material is defined as its mass per unit volume.

n Temperature, salinity and pressure affect the density of seawater. Large water masses of different densities are important in the layering of the ocean water (more dense water sinks). As temperature increases water becomes less dense. As salinity increases water becomes more dense. As pressure increases water becomes more dense.

pH n pH is a measure of the acidity or basicity of an aqueous solution

n pH is a measure of the acidity or alkalinity of a substance and is one of the stable measurements in seawater. Ocean water has an excellent buffering system with the interaction of carbon dioxide and water so that it is generally always at a pH of 7.5 to 8.5.

nAnAnAnAnything either highly acid or alkaline would kill marine life but the oceans are very stable with regard to pH.

Chemical Characteristics

n Seawater is mostly (~96.5%) water, but it contains important amounts of dissolved salts (~3.5%), which are mostly, but not all, sodium chloride, which is identical to table salt. sodiumtable saltsodiumtable salt

n Aside from calcium chloride salts, seawater also contains sulfates (7.7% of dissolved salts),magnesium (3.7%), calcium (1.2%), potassium (1.1%), and minor constituents (0.7%), including trace amounts of inorganic carbon (0.2%), bromide (0.08%), uranium ( %), and gold (similar amount). calciummagnesiumpotassiumcarboncalciummagnesiumpotassiumcarbon

Six elements and compounds compri se about 99% of sea salts: chlorine elementscompoundselementscompounds (Cl - ), sodium (Na + ), sulfur (SO 4 -2 ), magnesium (Mg +2 ), calcium (Ca +2 ), and potassium (K + ).

n The chlorine ion makes up 55% of the salt in seawater. Calculations of seawater salinity are made of the parts per 1000 of the chlorine ion present in one kilogram of seawater.

n Some of the important atmospheric gases found in seawater include: nitrogen, oxygen, carbon dioxide (in the form of bicarbonate HCO 3 ), argon, helium, and neon.

References: n physics/2_7/2_7_9.html physics/2_7/2_7_9.html physics/2_7/2_7_9.html n a-water-characteristics.html a-water-characteristics.html a-water-characteristics.html n /IntroOc/lecture03.html /IntroOc/lecture03.html /IntroOc/lecture03.html n e/02ocean/swcomposition.htm e/02ocean/swcomposition.htm e/02ocean/swcomposition.htm

n the-chemical-properties-of- seawater.htm the-chemical-properties-of- seawater.htm the-chemical-properties-of- seawater.htm n e/02ocean/swcomposition.htm e/02ocean/swcomposition.htm e/02ocean/swcomposition.htm

Prepared by: n Steffi Dawn C. Ilagan n Ranesa Joyce E. Poliran