Unit 3: Water Chemistry & Contaminants Exam Review

Exam Review

• Organic vs. Inorganic– Organic contains carbon

• Percentage of Freshwater– 2.5% of the planet’s water is fresh water

• Common elements in organic molecules– Carbon, hydrogen, and oxygen

• Hydrophilic– “water loving”– A solute that will dissolve in water

• Hydrophobic– “water fearing”– A solute that will not dissolve or mix in water

Exam Review

• Alkalinity– The ability of a solution (body of water) to buffer

against a change in pH, specifically an increase in acidity

Exam Review

• Carbonate system

CO2(g)

CO2(aq)

H2O

H2CO3

H+

HCO3–

H+

CO32-

CaCO3(s)limestone

Ca2+

Carbonic Acid

Bicarbonate

Carbonate

pH

8 1064

Exam Review

• Diatoms – – Most common brown algae

• Euglena – – Has both animal & plant features, protist, prominent

flagella• Paramecium –

– Protist covered in cilia• Hydra –

– Animal with a tremendous regenerative ability• Amoeba –

– Protist that uses phagocytosis to consume other organisms

Exam Review

• Microbes & biomass– Microbes account for ~ 50% of all biomass on

Earth– They are ubiquitous on the surface and deep

within the earth• Species richness

– the total number (biodiversity) of different species present

• Species abundance– the total number of individuals in a sample

Exam Review

Exam Review

• Guilds– Metabolically related microbial populations– Microbial species richness and abundance is a

function of the kinds and amounts of nutrients available in a given habitat

• Niche– Job/role an organism plays within its environment

• Prime Niche– For each organism there exists at least one

niche in which that organism is most successful (thrive)

Exam Review

• Biofilms– Assemblages of bacterial cells adhered to a surface and

enclosed in an adhesive matrix excreted by the cells– The matrix is typically a mixture of polysaccharides

• Formation & purpose of biofilms– Self-defense

• Biofilms resist physical forces that sweep away unattached

cells, phagocytosis by immune system cells, and penetration of

toxins (e.g., antibiotics)

– Allows cells to remain in a favorable niche

– Allows bacterial cells to live in close association with one

another

Exam Review

Exam Review

• Biochemical Oxygen Demand (BOD)– The microbial oxygen-consuming capacity of

a body of water

• Prochlorococcus– > 40% of the biomass of marine phototrophs – ~50% of the net primary production– Most of the primary productivity in the open

oceans

Exam Review

• Psychrophilic/tolerant– cold-loving– Can survive the cold, but does not thrive

• Barophilic/tolerant– pressure-loving– Can survive the pressure, but does not thrive

Exam Review

• Change in ratios of archaea/bacteria through aquatic life zones

Exam Review

• Hydrothermal vent microbes– Chemolithotrophic prokaryotes that utilize

reduced inorganic materials emitting from the vents form endosymbiotic relationships with vent invertebrates such as vent tube worms

• Chemolithotrophic– Organisms that use inorganic matter (chemicals)

to create their own food (chemo-auto-trophs)

Nitrogen Cycle

Exam ReviewSimplified Nitrogen Cycle

NH4+

AmmoniumNO2

–

NitriteNO3

–

NitrateN2

Nitrogen

NitrosofyingBacteria

NitrifyingBacteria

DenitrifyingBacteria

Nitrogen Fixation

Nitrification Denitrification

Aerobic Anaerobic

Exam Review

• Bioremediation– Refers to the cleanup of oil, toxic chemicals, or

other pollutants from the environment by microorganisms

– Often a cost-effective and practical method for pollutant cleanup

• Xenobiotics –– chemically synthesized compounds that have never

occurred in nature (pesticides, herbicides, plastics).• Phytoremediation:

– Degrading a pollutant using sunlight/UV light– Downsides: only the surface is effected, and its slow

Exam Review

• Chemical Cocktails – – A mixture of chemicals that, when consumed

independently cause no/little harm, but when put together can have damaging, and rarely studied effects.

Exam Review

• Oxygen depleting contaminants– organic carbon + O2 + bacteria →

CO2 + H2O + more bacteria

– if oxygen is depleted in natural water, most aquatic life will die (Ex. fish kills)

• C:N:P molar ratio ideal for bacterial growth– 100:10:1– Phosphorous is often the limiting factor in

bacterial/algal growth

Exam Review

• Cyanotoxins - – Produced by algal blooms (blue-green algae) that

is toxic to humans and most animals. Under the right conditions, these blooms can reduce DO to the point that nearby organisms will asphyxiate.

• Effects of Total Dissolved Salts– Measured as Total Dissolved Solids (TDS)– High salt concentration can damage crops, reduce

soil’s permeability– In drinking water, recommended that

TDS < 500 mg/L

Exam Review

• Thermal pollution– Primarily cooling water from power plants and

other industries– ↑Temperature, ↓Dissolved oxygen– ↑Temperature, ↑bacterial growth, ↓DO

Exam Review

• Sources of Nitrates in water– Septic systems (on-site waste water disposal systems)– Runoff and leaching from agricultural land, residential

lawns and gardens (nitrogenous fertilizers)– Animal wastes (ranging from confined animal feeding

operations to horses in the pasture)• Methemoglobinemia

– In humans, nitrate (NO3-) is reduced to nitrite (NO2

-)– Nitrite binds with hemoglobin to form

methemoglobin, a substance that cannot bind and transport oxygen

– Methemoglobinemia effects children & preganacies

Exam Review

• Chlorine byproducts (DBPs)– Chlorine is a common disinfectant in drinking

water– Excellent oxidizing disinfectant– Inactivates most bacteria, viruses and certain

protozoa– Most DBPs are regulated based on their suspected

human carcinogenicity (known carcinogenicity to laboratory animals)

– Epidemiologic evidence that chlorine DBPs, primarily trihalomethanes, are related to adverse reproductive outcomes

Exam Review

• Trihalomethanes –– The most common DBP, highly volatile

• Viruses – – Smallest known microbial contaminant– Consist of a DNA/RNA filled capsid & enzymes

• Bacteria – – Simple internal organization, simple life cycle,

flagellated– Creates spores when stressed

Exam Review

• Protozoa – – Complex, single-celled organisms– Complex life cycle– Forms cysts/oocysts when stressed

• Helminths – – Parasitic worms ranging in size from microscopic

to over one meter in length– Very complex life cycles– Eggs serve as the environmentally resistant form

for helminths

Exam Review

• E. coli – – bacteria– Small number of US outbreaks & low number of cases. 3

to 5% fatal• Fomite –

– An inanimate object that houses pathogens

• Salmonella – – Bacteria– 12 to 30% mortality, low # of outbreaks, slightly higher #

of cases

Exam Review

• Vibrio cholera – – Bacteria– Low rate of infection within the US, but

responsible for a many-decade pandemic in Asia, Africa, and Latin America

• Giardia – – Protist– Larger number of US outbreaks higher rate of

infection than common infectious bacteria

Exam Review

• Cryptosporidium – – Protist– Small number of US outbreaks yielding an extremely

high rate of infection (421,473 cases)– 1-3% US, 5% Asia, 10% Africa infected at any given time

• Toxoplasmosis – – Oocysts are extremely resistant to common disinfectants– Cats are the definitive host for Toxo– Close to 25% of US population is infected– Life threatening to immuno-compromised individuals – Congenital infected children

Exam Review

• Platyhelminthes –– “flat” worms– Common examples: tape worms, flukes

• Ashelminthes – – “round” worms– Hookworms, ascaris, trichinella, etc

• Lung Fluke – • Hookworms –

– Extensive lifecycle: burrowing into skin, travelling through blood, lungs, stomach, then small intestine

– Shed 10,000 to 20,000 eggs per day– Can consume 0.2mL of blood per adult per day

Exam Review

• Trichinella –– “Biblical worm”– Most commonly found in swine muscle tissue & our first

example of nature/parasites/illnesses changing/shaping human culture

– Causes painful & aching muscles in infected humans • Ascaris –

– Large (25-45 cm) & most common infectious worm – Common where sanitation is poor & human feces is used

as fertilizer