I. I.Water Pollution – Components D. D.Other Chemicals and Minerals 1. 1.Acids and acidifying compounds Many originate in the atmosphere (sulfuric acid,

I. Water Pollution – Components

D. Other Chemicals and Minerals1. Acids and acidifying compounds

• Many originate in the atmosphere (sulfuric acid, nitric acid) or from runoff passing through mine tailings

• Aquatic organisms generally intolerant of low pH• Effects

1) Irritates gills of fishes and crustaceans and interferes with gas exchange

2) Irritates slime layer of fishes (reduces resistance to pathogens)

3) Erodes shells of aquatic mollusks and arthropods

4) Impedes ability of crustaceans to recalcify after molting

5) Facilitates release of toxins bound to particles in sediments


D. Other Chemicals and Minerals1. Acids and acidifying compounds

• Many originate in the atmosphere (sulfuric acid, nitric acid) or from runoff passing through mine tailings

• Aquatic organisms generally intolerant of low pH• Effects

1) Irritates gills of fishes and crustaceans and interferes with gas exchange

2) Irritates slime layer of fishes (reduces resistance to pathogens)

3) Erodes shells of aquatic mollusks and arthropods

4) Impedes ability of crustaceans to recalcify after molting

5) Facilitates release of toxins bound to particles in sediments


D. Other Chemicals and Minerals2. Nutrients

• Nitrates, nitrites, phosphates• Common sources

1) Crop and lawn fertilizers2) Manure3) Sewage4) Detergents containing phosphates and nitrates

• Excessive nutrient loading eutrophication• Effects

1) Plant growth can clog waterways (ecology, navigation)2) Plants can interfere with recreation (swimming, boating)3) Algal growth can impede submerged plant growth4) Nighttime oxygen depletion5) Nitrate methemoglobinemia (blue baby syndrome)

• Nutrients can be difficult to control once in a system• Recycling and regeneration

• Eutrophied water bodies can recover if sources are removed• Ex: Lake Washington

Kiely 1997 Environmental Engineering


D. Other Chemicals and Minerals3. Metals

• Normal constituents of fresh waters at low concentrations

• Human activities sometimes lead to elevated levels• May not be toxic at low concentrations or low trophic

levels• Toxic at higher concentrations• May bioaccumulate and biomagnify

• Effects

1) Health – Ex: Aluminum interferes with salt regulation in fishes and causes gills to produce large quantities of mucus

2) Chelators – Bind nutrients, trace elements, and other necessary chemicals


E. Sediments (Siltation)• Suspended particles, usually from erosion in

watershed• Especially problematic in areas with

• Plowed fields• Construction sites• Logging sites• Strip-mined areas

• Effects1) Clog respiratory/feeding structures2) Abrade skin and shells3) Smother eggs and larvae on bottom4) Impair photosynthesis by blocking light5) Transport bound chemicals6) Decrease aesthetic, recreational, commercial value

(beneficial uses)7) Fill in crevices and, eventually, water bodies


F. Heat (Thermal pollution)• Sources

• Condenser cooling water from electricity generating facilities (industrialized nations)

• Especially problematic in areas with low flow rates• Heat discharged per kW generated has dropped by 50-70%

since 1950• Generation capacity has increased substantially• Total heat discharge today 50-100% greater than in 1950

• Effects1) Reduces solubility of O2

2) Increases rate of degradation (exacerbates O2 depletion)3) Disrupts life cycles of organisms that use temperature

changes as cues4) Enhances development of some eggs/larvae/juveniles and

inhibits/kills others5) Alters composition of algal community - Diatoms dominate cool, oligotrophic waters - Chlorophytes dominate warm, oligotrophic waters - Cyanobacteria dominate still warmer waters

II. Biodiversity – Definitions and Assessment

• Major issue – Potential loss as a result of human activities

A. Definitions• Discussion requires clear consensus about what

biodiversity is and how it’s defined• Fundamental unit = species• What is a species??

1. Species• Group of genetically similar organisms that interbreed

naturally and freely to produce viable, fertile offspring, but do not share this behavior and outcome with individuals of other species

• Problem: Some people consider this definition to be inadequate. Why??


A. Definitions1. Species

a. Geographic Isolation• Populations could interbreed if geographic barrier

could be surmounted• Separate species? Subspecies? Populations?

b. Natural Hybrids• Ex – Horse + Donkey Mule• Ex – Queen + Blue Townsend’s Angelfish• Separate species? If a natural hybrid disappears, is

it really gone so long as parent species remain?c. Polymorphism

• Ex - Hamlets• How different must two species be to constitute

separate species? Humans and chimpanzees are estimated to be 98% identical at the DNA level.






it really gone so long as parent species remain?c. Polymorphism

• Ex - Hamlets• How different must two species be to constitute

separate species? Humans and chimpanzees are estimated to be 98% identical at the DNA level.

Blue Queen

Townsend’s






it really gone so long as parent species remain?• Quagga

c. Polymorphism and Genetic Variability• Ex - Hamlets• How different must two species be to constitute

separate species?

Barred Black

Blue

Golden

Indigo

Yellowtail



• How do we identify a species?• How do we quantify the number of species in an area

when there is disagreement about what constitutes a species?

• Recently: Focus on preservation of processes that lead to speciation

• Suggests emphasis on conservation of intact habitat vs. single species (HCP vs. ESA)

• •

Documents

I. I.Water Pollution – Components D. D.Other Chemicals and Minerals 1. 1.Acids and acidifying compounds Many originate in the atmosphere (sulfuric acid,