Seawater Earth is an Ocean Planet Topics • Origin of the Ocean and Atmosphere • Hydrologic Cycle • Biogeochemical Cycle • Seawater Salinity • Variations in Seawater Chemistry • Carbonic Acid System Topics • Origin of the Ocean and Atmosphere • Hydrologic Cycle • Biogeochemical Cycle • Seawater Salinity • Variations in Seawater Chemistry • Carbonic Acid System Seawater Salinity Seawater Salinity Major Constituents, Minor Constituents, Trace Elements, and Gases Seawater is 96.5% H2O (solvent) Seawater is 96.5% H2O (solvent) 3.5% dissolved constituents (solutes) Seawater Constituents Seawater Constituents • Four categories of solutes: Seawater Constituents • Four categories of solutes: 1. Major constituents Seawater Constituents • Four categories of solutes: 1. Major constituents 2. Minor constituents Seawater Constituents • Four categories of solutes: 1. Major constituents 2. Minor constituents 3. Trace elements Seawater Constituents • Four categories of solutes: 1. Major constituents 2. Minor constituents 3. Trace elements 4. Gases Salinity Salinity • Salinity of seawater is relatively uniform Salinity • Salinity of seawater is relatively uniform • Small changes are significant Salinity • Salinity of seawater is relatively uniform • Small changes are significant • Examples: 3.40% 3.49% Average Salinity Average Salinity • 3.5% Average Salinity • 3.5% • 3.5 per cent Average Salinity • 3.5% • 3.5 per cent • 3.5 parts per hundred Average Salinity • 3.5% • 3.5 per cent • 3.5 parts per hundred • 35‰ Average Salinity • 3.5% • 35‰ • 3.5 per cent • 35 per mil • 3.5 parts per hundred Average Salinity • 3.5% • 35‰ • 3.5 per cent • 35 per mil • 3.5 parts per hundred • 35 parts per thousand Average Salinity • 3.5% • 35‰ • 3.5 per cent • 35 per mil • 3.5 parts per hundred • 35 parts per thousand 35 ppt Average Salinity • 3.5% • 35‰ • 3.5 per cent • 35 per mil • 3.5 parts per hundred • 35 parts per thousand 35 ppt 34.7 ppt Major Constituents Major Constituents • Most seawater constituents are ions Major Constituents • Most seawater constituents are ions • e.g. Cl- and Na+ Major Constituents • Most seawater constituents are ions • e.g. Cl- and Na+ • Six major constituents Major Constituents • Most seawater constituents are ions • e.g. Cl- and Na+ • Six major constituents • Constitute >99% of seawater salinity Major Constituents • Most seawater constituents are ions • e.g. Cl- and Na+ • Six major constituents • Constitute >99% of seawater salinity • Concentrations of the major constituents determine the salinity of seawater Major Constituents Major Constituents 1. Cl- Major Constituents 1. Cl2. Na+ Major Constituents 1. Cl2. Na+ 3. SO42- Major Constituents 1. Cl2. Na+ 3. SO424. Mg2+ Major Constituents 1. Cl2. Na+ 3. SO424. Mg2+ 5. Ca2+ Major Constituents 1. Cl2. Na+ 3. SO424. Mg2+ 5. Ca2+ 6. K+ Major Constituents 1. Cl2. Na+ 3. SO424. Mg2+ 5. Ca2+ 6. K+ Salinity of Seawater Major Constituents Major Constituents NaCl 86% Range of Salinity Range of Salinity • Salinity is relatively uniform - 35 ppt Range of Salinity • Salinity is relatively uniform - 35 ppt • Salinity varies (over a small range) Range of Salinity • Salinity is relatively uniform - 35 ppt • Salinity varies (over a small range) • General range of variation in the open ocean is 33-37 ppt Range of Salinity • Salinity is relatively uniform - 35 ppt • Salinity varies (over a small range) • General range of variation in the open ocean is 33-37 ppt 33 ppt - 37 ppt Marcet’s Principle Marcet’s Principle • Despite small variations in seawater salinity, the relative proportions of the major constituents are constant Marcet’s Principle • Despite small variations in seawater salinity, the relative proportions of the major constituents are constant • Also called the principle of constant proportions Marcet’s Principle Example of Marcet’s Principle: Marcet’s Principle Example of Marcet’s Principle: • Station 1 Marcet’s Principle Example of Marcet’s Principle: • Station 1 • Salinity - 33.9 ppt Marcet’s Principle Example of Marcet’s Principle: • Station 1 • Salinity - 33.9 ppt • Cl/Na = x Marcet’s Principle Example of Marcet’s Principle: • Station 1 • Salinity - 33.9 ppt • Cl/Na = x • Mg/K = y Marcet’s Principle Example of Marcet’s Principle: • Station 1 • Salinity - 33.9 ppt • Cl/Na = x • Mg/K = y • Ca/SO4 = z Cl/Na Cl/Na Marcet’s Principle • Station 1 • Salinity - 33.9 ppt • Cl/Na = 1.8 • Mg/K = y • Ca/SO4 = z Mg/K Mg/K Marcet’s Principle • Station 1 • Salinity - 33.9 ppt • Cl/Na = 1.8 • Mg/K = 3.4 • Ca/SO4 = z Ca/SO4 Ca/SO4 Marcet’s Principle • Station 1 • Salinity - 33.9 ppt • Cl/Na = 1.8 • Mg/K = 3.4 • Ca/SO4 = 0.15 Marcet’s Principle • Station 1 • Salinity - 33.9 ppt • Cl/Na = 1.8 • Mg/K = 3.4 • Ca/SO4 = 0.15 Marcet’s Principle • Station 1 • Salinity - 33.9 ppt • Cl/Na = 1.8 • Mg/K = 3.4 • Ca/SO4 = 0.15 • Station 2 Marcet’s Principle • Station 1 • Station 2 • Salinity - 33.9 ppt • Salinity - 36.3 ppt • Cl/Na = 1.8 • Mg/K = 3.4 • Ca/SO4 = 0.15 Marcet’s Principle • Station 1 • Station 2 • Salinity - 33.9 ppt • Salinity - 36.3 ppt • Cl/Na = 1.8 • Cl/Na = 1.8 • Mg/K = 3.4 • Ca/SO4 = 0.15 Marcet’s Principle • Station 1 • Station 2 • Salinity - 33.9 ppt • Salinity - 36.3 ppt • Cl/Na = 1.8 • Cl/Na = 1.8 • Mg/K = 3.4 • Mg/K = 3.4 • Ca/SO4 = 0.15 Marcet’s Principle • Station 1 • Station 2 • Salinity - 33.9 ppt • Salinity - 36.3 ppt • Cl/Na = 1.8 • Cl/Na = 1.8 • Mg/K = 3.4 • Mg/K = 3.4 • Ca/SO4 = 0.15 • Ca/SO4 = 0.15 Marcet’s Principle Marcet’s Principle • Despite small variations in seawater salinity, the relative proportions of the major constituents are constant Marcet’s Principle • Despite small variations in seawater salinity, the relative proportions of the major constituents are constant • The principle of constant proportions Determine Salinity Determine Salinity • Station 3: salinity = x Determine Salinity • Station 3: salinity = x • To determine the salinity at a location, oceanographers need to know the concentrations of the major constituents Determine Salinity • Station 3: salinity = x • To determine the salinity at a location, oceanographers need to know the concentrations of the major constituents • Constitute >99% of seawater salinity Determine Salinity • Station 3: salinity = x • To determine the salinity at a location, oceanographers need to know the concentrations of the major constituents • Constitute >99% of seawater salinity • Concentrations of the major constituents determine the salinity of seawater Major Constituents Question Question • Considering Marcet’s principle - Question • Considering Marcet’s principle how many of the major constituents must be measured to determine the salinity of seawater? Major Constituents Determine Salinity Determine Salinity • Only need to measure the concentration of one major constituent Determine Salinity • Only need to measure the concentration of one major constituent • Use Marcet’s principle to calculate the concentrations of the other constituents Determine Salinity • Only need to measure the concentration of one major constituent • Use Marcet’s principle to calculate the concentrations of the other constituents • Which major constituent generally is measured? Determine Salinity • Only need to measure the concentration of one major constituent • Use Marcet’s principle to calculate the concentrations of the other constituents • Which major constituent generally is measured? • Cl- Determine Salinity Determine Salinity • Measure the concentration of Cl- Determine Salinity • Measure the concentration of Cl• Cl- = 19.35 ppt Determine Salinity • Measure the concentration of Cl• Cl- = 19.35 ppt • Cl-/Na+ = 1.8 Determine Salinity • Measure the concentration of Cl• Cl- = 19.35 ppt • Cl-/Na+ = 1.8 • Na+/Cl- = 0.56 Determine Salinity • Measure the concentration of Cl• Cl- = 19.35 ppt • Cl-/Na+ = 1.8 • Na+/Cl- = 0.56 • 19.35 x 0.56 = 10.8 ppt Determine Salinity • Measure the concentration of Cl• Cl- = 19.35 ppt measure Cl- • Cl-/Na+ = 1.8 • Na+/Cl- = 0.56 • 19.35 x 0.56 = 10.8 ppt calculate Na+ Determine Salinity Determine Salinity • Measure Cl- Determine Salinity • Measure Cl• Na+/Cl- = 0.56 Determine Salinity • Measure Cl• Na+/Cl- = 0.56 • SO42-/Cl- = 0.14 Determine Salinity • Measure Cl• Na+/Cl- = 0.56 • SO42-/Cl- = 0.14 • Mg2+/Cl- = 0.07 Determine Salinity • Measure Cl• Na+/Cl- = 0.56 • SO42-/Cl- = 0.14 • Mg2+/Cl- = 0.07 • Ca2+/Cl- = 0.02 Determine Salinity • Measure Cl• Na+/Cl- = 0.56 • SO42-/Cl- = 0.14 • Mg2+/Cl- = 0.07 • Ca2+/Cl- = 0.02 • K+/Cl- = 0.02 Determine Salinity • Measure Cl• Na+/Cl- = 0.56 • SO42-/Cl- = 0.14 • Mg2+/Cl- = 0.07 • Ca2+/Cl- = 0.02 • K+/Cl- = 0.02 • 19.35 ppt Determine Salinity • Measure Cl- • 19.35 ppt • Na+/Cl- = 0.56 • 19.35 ppt x 0.56 = 10.8 ppt • SO42-/Cl- = 0.14 • Mg2+/Cl- = 0.07 • Ca2+/Cl- = 0.02 • K+/Cl- = 0.02 Determine Salinity • Measure Cl- • 19.35 ppt • Na+/Cl- = 0.56 • 19.35 ppt x 0.56 = 10.8 ppt • SO42-/Cl- = 0.14 • 19.35 ppt x 0.14 = 2.7 ppt • Mg2+/Cl- = 0.07 • Ca2+/Cl- = 0.02 • K+/Cl- = 0.02 Determine Salinity • Measure Cl- • 19.35 ppt • Na+/Cl- = 0.56 • 19.35 ppt x 0.56 = 10.8 ppt • SO42-/Cl- = 0.14 • 19.35 ppt x 0.14 = 2.7 ppt • Mg2+/Cl- = 0.07 • 19.35 ppt x 0.07 = 1.3 ppt • Ca2+/Cl- = 0.02 • K+/Cl- = 0.02 Determine Salinity • Measure Cl- • 19.35 ppt • Na+/Cl- = 0.56 • 19.35 ppt x 0.56 = 10.8 ppt • SO42-/Cl- = 0.14 • 19.35 ppt x 0.14 = 2.7 ppt • Mg2+/Cl- = 0.07 • 19.35 ppt x 0.07 = 1.3 ppt • Ca2+/Cl- = 0.02 • 19.35 ppt x 0.02 = 0.4 ppt • K+/Cl- = 0.02 Determine Salinity • Measure Cl- • 19.35 ppt • Na+/Cl- = 0.56 • 19.35 ppt x 0.56 = 10.8 ppt • SO42-/Cl- = 0.14 • 19.35 ppt x 0.14 = 2.7 ppt • Mg2+/Cl- = 0.07 • 19.35 ppt x 0.07 = 1.3 ppt • Ca2+/Cl- = 0.02 • 19.35 ppt x 0.02 = 0.4 ppt • K+/Cl- = 0.02 • 19.35 ppt x 0.02 = 0.4 ppt Determine Salinity • Measure Cl- • 19.35 ppt • Na+/Cl- = 0.56 • 19.35 ppt x 0.56 = 10.8 ppt • SO42-/Cl- = 0.14 • 19.35 ppt x 0.14 = 2.7 ppt • Mg2+/Cl- = 0.07 • 19.35 ppt x 0.07 = 1.3 ppt • Ca2+/Cl- = 0.02 • 19.35 ppt x 0.02 = 0.4 ppt • K+/Cl- = 0.02 • 19.35 ppt x 0.02 = 0.4 ppt 35.0 ppt Determine Salinity Determine Salinity • To determine salinity within 1%, need to know the concentrations of only the major constituents Determine Salinity • To determine salinity within 1%, need to know the concentrations of only the major constituents • Major constituents are >99% of salinity Determine Salinity • To determine salinity within 1%, need to know the concentrations of only the major constituents • Major constituents are >99% of salinity • Only have to measure one major constituents to determine salinity Determine Salinity • To determine salinity within 1%, need to know the concentrations of only the major constituents • Major constituents are >99% of salinity • Only have to measure one major constituents to determine salinity • Measure one constituent and calculate the others using Marcet’s principle Determine Salinity • To determine salinity within 1%, need to know the concentrations of only the major constituents • Major constituents are >99% of salinity • Only have to measure one major constituents to determine salinity • Measure one constituent and calculate the others using Marcet’s principle • Generally measure Cl- Conservative Property Conservative Property • Concentrations of the major constituents are conservative properties of seawater Conservative Property • Concentrations of the major constituents are conservative properties of seawater • Conservative properties are Conservative Property • Concentrations of the major constituents are conservative properties of seawater • Conservative properties are 1. altered primarily at the ocean’s surface Conservative Property • Concentrations of the major constituents are conservative properties of seawater • Conservative properties are 1. altered primarily at the ocean’s surface 2. not significantly affected by biological activity Change Salinity Change Salinity • Salinity is altered primarily at the ocean’s surface by Change Salinity • Salinity is altered primarily at the ocean’s surface by 1. addition of water (precipitation) Change Salinity • Salinity is altered primarily at the ocean’s surface by 1. addition of water (precipitation) 2. removal of water (evaporation) Explains Marcet’s Principle 35 ppt Na+ Cl- Cl- Cl-/Na+ = 1.8 Despite small variations in seawater salinity, the relative proportions of the major constituents are constant Explains Marcet’s Principle 35 ppt Na+ Cl- Na+ Cl- Cl-/Na+ = 1.8 Cl- Cl- Explains Marcet’s Principle 35 ppt Na+ Cl- Cl- Na+ Cl- Cl-/Na+ = 1.8 Cl- Explains Marcet’s Principle 35 ppt 37 ppt Na+ Cl- Cl- Na+ Cl- Cl-/Na+ = 1.8 Cl- Explains Marcet’s Principle 35 ppt 37 ppt Na+ Cl- Cl- Na+ Cl- Cl-/Na+ = 1.8 Cl- Cl-/Na+ = 1.8 Explains Marcet’s Principle 35 ppt 37 ppt Na+ Cl- Cl- Na+ Cl- Cl-/Na+ = 1.8 Na+ Cl- Cl-/Na+ = 1.8 Cl- Cl- Explains Marcet’s Principle 35 ppt 37 ppt Na+ Na+ Cl- ClCl- Na+ Cl- Cl-/Na+ = 1.8 Cl- Cl-/Na+ = 1.8 Cl- Explains Marcet’s Principle 35 ppt 37 ppt 33 ppt Na+ Na+ Cl- ClCl- Na+ Cl- Cl-/Na+ = 1.8 Cl- Cl-/Na+ = 1.8 Cl- Explains Marcet’s Principle 35 ppt 37 ppt 33 ppt Na+ Na+ Cl- ClCl- Na+ Cl- Cl-/Na+ = 1.8 Cl- Cl- Cl-/Na+ = 1.8 Cl-/Na+ = 1.8 Uniformity of Salinity Uniformity of Salinity • Why is salinity relatively uniform? Uniformity of Salinity • Why is salinity relatively uniform? a small open ocean range of 33-37 ppt Uniformity of Salinity • Why is salinity relatively uniform? a small open ocean range of 33-37 ppt • Uniform because the ocean is well mixed Uniformity of Salinity • Why is salinity relatively uniform? a small open ocean range of 33-37 ppt • Uniform because the ocean is well mixed • To explain how the ocean became well mixed, oceanographers use the Uniformity of Salinity • Why is salinity relatively uniform? a small open ocean range of 33-37 ppt • Uniform because the ocean is well mixed • To explain how the ocean became well mixed, oceanographers use the long residence times of the major constituents Uniformity of Salinity • Why is salinity relatively uniform? a small open ocean range of 33-37 ppt • Uniform because the ocean is well mixed • To explain how the ocean became well mixed, oceanographers use the long residence times of the major constituents short mixing time of the ocean All of the major constituents have residence times > 106 yr Ocean Mixing pattern Atlantic Indian Pacific Ocean Mixing pattern Atlantic Indian Pacific Ocean Mixing pattern Atlantic Indian Pacific Ocean Mixing pattern Atlantic Indian Pacific Ocean Mixing pattern Atlantic Indian Pacific Ocean Mixing pattern Atlantic Indian Pacific Mixing time ≈ 1000 yr Ocean Mixing pattern Mixing time ≈ 1000 yr Ocean Is Well Mixed Ocean Is Well Mixed • Residence times of the major constituents are much, much longer than the mixing time Ocean Is Well Mixed • Residence times of the major constituents are much, much longer than the mixing time 1,000,000 yr >>> 1,000 yr Ocean Is Well Mixed • Residence times of the major constituents are much, much longer than the mixing time 1,000,000 yr >>> 1,000 yr 106 yr >>> 103 yr Ocean Is Well Mixed • Residence times of the major constituents are much, much longer than the mixing time 1,000,000 yr >>> 1,000 yr 106 yr >>> 103 yr • Residence time/mixing time = X Ocean Is Well Mixed • Residence times of the major constituents are much, much longer than the mixing time 1,000,000 yr >>> 1,000 yr 106 yr >>> 103 yr • Residence time/mixing time = X 106 yr/103 yr = 103 Ocean Is Well Mixed • Residence times of the major constituents are much, much longer than the mixing time 1,000,000 yr >>> 1,000 yr 106 yr >>> 103 yr • Residence time/mixing time = X 106 yr/103 yr = 103 • In 1,000,000 yr, the ocean mixes itself 1000x Minor Constituents and Trace Elements Minor Constituents and Trace Elements • Minor constituents measured in ppm Minor Constituents and Trace Elements • Minor constituents measured in ppm • Trace elements measured in ppb or pptr Minor Constituents and Trace Elements • Minor constituents measured in ppm • Trace elements measured in ppb or pptr • In general, Minor Constituents and Trace Elements • Minor constituents measured in ppm • Trace elements measured in ppb or pptr • In general, Marcet’s principle does not apply Minor Constituents and Trace Elements • Minor constituents measured in ppm • Trace elements measured in ppb or pptr • In general, Marcet’s principle does not apply tend to be nonconservative Minor Constituents and Trace Elements • Minor constituents measured in ppm • Trace elements measured in ppb or pptr • In general, Marcet’s principle does not apply tend to be nonconservative tend to have shorter residence times Biolimiting Nutrients Biolimiting Nutrients • Primary biolimiting nutrients are in trace concentrations: N, P, Si, Fe Nutrient concentrations are low in the open ocean Nutrient concentrations are low in the open ocean Water is clear Atmospheric Gases Gases Gases • Atmospheric Gases Gases • Atmospheric Gases N2 - 78% Gases • Atmospheric Gases N2 - 78% O2 - 21% Gases • Atmospheric Gases N2 - 78% O2 - 21% CO2 - 0.035% Gases • Atmospheric Gases N2 - 78% O2 - 21% CO2 - 0.035% • Oceanic Gases Gases • Atmospheric Gases N2 - 78% O2 - 21% CO2 - 0.035% • Oceanic Gases N2 - 48% Gases • Atmospheric Gases • Oceanic Gases N2 - 78% N2 - 48% O2 - 21% O2 - 36% CO2 - 0.035% Gases • Atmospheric Gases • Oceanic Gases N2 - 78% N2 - 48% O2 - 21% O2 - 36% CO2 - 0.035% CO2 - 15% Gases Gases • Are N2, O2, and CO2 conservative or nonconservative? Gases • Are N2, O2, and CO2 conservative or nonconservative? • N2 is conservative Gases • Are N2, O2, and CO2 conservative or nonconservative? • N2 is conservative • O2 is nonconservative Gases • Are N2, O2, and CO2 conservative or nonconservative? • N2 is conservative • O2 is nonconservative • CO2 is nonconservative Gases • Are N2, O2, and CO2 conservative or nonconservative? • N2 is conservative • O2 is nonconservative • CO2 is nonconservative Both O2 and CO2 are strongly affected by biological activity Gases • Are N2, O2, and CO2 conservative or nonconservative? • N2 is conservative • O2 is nonconservative • CO2 is nonconservative Both O2 and CO2 are strongly affected by biological activity The concentrations of O2 and CO2 are altered below the ocean’s surface Banded Ironstone Variations in Seawater Chemistry Next Variations in Seawater Chemistry
© Copyright 2024 Paperzz