Ch.27 Environmental Micro Flashcards
what is the hydrologic (water) cycle?
is the cyclic exchange of water between the atmosphere and biosphere
what are the steps to the hydrologic water cycle?
- water precipitates as rain; falls to earth
- It is returned by evaporation to the air
what carries nutrients into the river and what does it increase?
- water
- increases BOD
what accelerates microbial respiration?
Carbon runoff
what is BOD?
Biochemical oxygen Demand
it is the amount of O2 removed from the environment through respiration
what creates BOD?
Microbial Oxygen Consumption
how is BOD measured?
with how fast oxygen is removed
where are dead zones or zones of hypoxia?
large regions of the ocean
what is an example of a dead zone or zone of hypoxia?
Gulf of Mexico, off the Louisiana coast
when did the dead zone expand?
by 2010 oil spill
Heterotrophs in a large region of the ocean that have become dead zones or zones of hypoxia increase in response to what?
the influx of organic nutrients
what depletes oxygen in large regions of the ocean that have become dead zones or zones of hypoxia?
aerobic respiration
when does eutrophication occur?
from an influx of excess nutrients that triggers hypoxic zones in the water
Eutrophication results in high levels of what?
aerobic respiration
what decreases the BOD and the level of human pathogens before water is returned to local rivers?
wastewater treatment
what are the steps to wastewater treatment?
- Preliminary treatment
- Primary treatment
- Secondary Treatment
- Tertiary (advanced) treatment
what does the preliminary treatment do?
removes solid debris
what does the primary treatment do?
fine screens & sedimentation tanks remove insoluble particles.
what does secondary treatment do?
microbial decomposition of organic content
what does tertiary advance treatment do?
chlorination or other chemical application to eliminate pathogens
what is the activated sludge process?
a process for treating wastewater using air and a biological floc composed of bacteria and protozoa.
why is flocculation important?
floc formation is critical in promoting the setting of bacteria
associated microbes from the treatment process.
what does flocculation yield?
abundant, clarified effluent
what is important in floc formation?
filamentous bacteria
what is a healthy sludge(brown floc) largely composed of?
Saprotrophic bacteria
what does saprotrophic bacteria feed on?
feed on decayed matter
what is the protozoan flora composed of?
amoebae
ciliated protozoans
stalked ciliates
true or false?
Nitrogen has more oxidation states than any other major biological element
true
What can’t the nitrogen cycle exist without?
it cannot exist without prokaryotes
what is the major accessible nitrogen source?
atmosphere
what is artificial nitrogen fixation accomplished by?
by the Haber process
what is the Haber process?
it generates fertilizers for agriculture
N2+3H2—-> 2NH3
What is ammonification?
the catabolism of organic N sources (proteins); release ammonia (NH3)
The N2 is catalyzed by what?
nitrogenase
does N2 fixation function anaerobically or aerobically?
anaerobically
what does symbiotic mean?
bacterial associations with certain types of plants
what does N2 fixation occur in?
free-living types and symbiotic types of bacterial
cyanobacteria in oceans and freshwater compartmentalize N2 fixation in what?
heterocysts
what is the formula for N2 fixation?
N2—–>NH3—-NH4+
steps to symbiotic N2 fixation:
- Rhizobia attaches to root hair
- An infection thread is formed through which bacteria enter root cells
- Bacteria change into bacteroids; packed roots enlarge
- Enlarged root cells form a nodule
What is the formula for nitrification?
NH4+—>NO2- —->NO3-
what is lithotrophy?
oxidation of NH4+ provides electrons and energy.
what does denitrification represent?
represents anaerobic respiration
what does denitrification lead to?
loss of nitrogen from the environment
what stimulates denitrification?
influx of nitrate(NO3-) into areas lacking O2
what happens in hypoxic areas during denitrification?
anaerobic respiration using NO3-
causes: NO2- buildup
then used to for N2O
what happens when water passes through the ground and picks up nutrients?
carbon runoff accelerates microbial respiration
02 becomes depleted
High BOD can threaten what?
viability of fish & other aquatic animals
when does high BOD threaten the viability of aquatic animals?
when O2 levels are < 5 mg L
what is the process of Eutrophication?
- influx of N, P boosts levels of phototrophs
ex: alage & cyanobacteria; a mat of growth occurs
- once excess N, P is used up, the algal mass dies and falls to the bottom
- Hetertropic bacteria on the organic matter feast on organic matter
- Aerobic respiration depletes oxygen from the water- fish killed
