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Flashcards in Understand Differences Deck (23)
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1

Point source pollution

Pollution that can be traced to a specific spot because it is DISCHARGED into the environment via pipes, sewers, etc.

Examples : Factory , waste water treatment plant

2

Non-source point pollution

Comes from many sources
- can be caused by rainfall or snow melt moving through or over ground

Examples : Agriculture fertilizer, run off, sediments from construction
-Urban streets, rural homes, suburban development, crop land, animal feeding lots

3

BOD

Biochemical oxygen demand
-Measures O2 Consumed
-indirect measurement of amount of organic pollutants in water
- bacteria act as organic matter in sewage water
- large amounts DO (dissolved oxygen) are used up rapidly
- LOW BOD = GOOD H20 QUALITY !
- To test BOD : 300 ml of H20 , standard bacteria, stoppered bottle, 5 days at 20 degrees C in the dark .
- DO is to be measured BEFORE AND AFTER.

4

What is LOW BOD a good thing?

It is good h20 quality because
-little oxygen demand from bacteria
- Bacteria demand oxygen when hey breakdown organic matter
- LOW CONTAMINATION in water

5

COD

Chemical oxygen demand
- amount of oxygen required to oxidize an organic compound to CO2 to H20
- Organic compound + H20 —> H20 + CO2 + Ammonia
* In order to reduce the organic compound, oxygen is REQUIRED.
*Measuring oxygen used for chemical reduction will INDICATE the AMOUNT of organic material

- Measurement in terms of TOTAL QUANTITY OF OXYGEN required for OXIDATION
- HIGHER value than BOD (Bacteria needs less oxygen to break down organic material than chemicals need to break down organic material)
- To TEST: 300 mL, heat reflux with dichromate (K2Cr2O7); Reduction of Cr+6 to Cr+3 (6 TO 3, basically remember REDUCING)
- indirect indicator of ORGANICS.

6

Aerobic bacteria

Requires FREE DO for growth
Oxidatively produces CO2 + H20 (respiration)
Mineralization of other elements (NO3- , PO43-, SO4-2)

7

Anoxic Bacteria

REQUIRES

Free DO and N for GROWTH!

8

Anaerobic bacteria

Grows in ABSENCE of free DO (Because its anaerobic)

Energy from breaking down complex organic substances

Reduce organic materials to CH4, NH3, H2S

9

Why are we concerned with BOD and/or COD in receiving water bodies?

Potential depletion of DO (dissolved oxygen) due to organic materials

10

What are the zones for urban runoff?

Clean zone
Decomposition zone
Septic zone
Recovery zone
Clean zone

Aka (CDSRC - crazy dinosaur singing romance choir - made this band up,but it works)

11

Clean zone

NO pollution
Normal organisms : trout, perch, bass, mayfly, stonefly

12

Decomposition zone

Polluted water ENTERS the stream

Trash fish : car, gar, leaches (hate leaches)

13

Septic Zone

Anaerobic ZONEEEEEEEE

Fish absent : fungi, sludge worms (google it, look how gross they are) , bacteria

14

Recovery zone

Less contamination present , INCREASE in DO and DECREASE in BOD (trash fish present)

BOD declines because most of organic material has settled as sludge
DO INCREASES

15

Second CLEAN ZONE

Normal water and organisms
After recovery zone

DO 8 ppm

16

Factors contributing to urban run off

Increase percent of impervious surfaces (concrete)
Decrease amount of percolation in soil
Increased amount of runoff from construction sites
Runoff rates depend on rainfall

17

Remediation solutions

Settling basins
Recharge basins
Interception of run off
Porous materials
Grassy channels

18

Settling basins

Pros : SS and BOD (some nutrients and toxins are absorbed)
Cons : system may be overwhelmed by storms and have short resistance time of 2-3 hours
Smaller particles will not be absorbed in that time

19

Recharge basins

Pros : slow percolation of water into the ground
Removes SS by SOIL

Cons: dissolved contaminates will percolate into groundwater

20

Interception of runoff

Pros : collect rainwater, clarifier, recharge ground water

21

Eutrophication

Enrichment of an ecosystem with chemical nutrients, typically compounds containing N, P or both in the form of nitrates and phosphates

Can occur naturally OVER TIME

22

stages of eutrophication

1. Excess nutrients accumulate due to Natural N/ P cycling or unnatural wastewater discharge

2. No longer constrained by limited nutrient availability , plants flourish

3. Algae blooms due to excess nutrients, blocks sunlight penetrating the water

4. Loss of light disallows plants below algae to conduction p/s resulting in drop in DO

5. Plant life below algal blooms dies without sunlight and are decomposed by bacteria further lowering DO

6. DO is so low that life is no longer possible in ecosystem

23

Sources of eutrophication

-Discharge of untreated municipal sewage (nitrates and phosphates)
- nitrogen compounds produced by cars and factories
- discharge of detergents (phosphates)
- inorganic fertilizer runoff (nitrates and phosphates)
- dishcharge of treated municipal sewage (primary and secondary treatment : nitrate and phosphates
- manure runoff from feedlots (nitrates, phosphates, ammonia)
- runoff from streets, lawns, and construction lots (nitrates and phosphates)
- dissolving of nitrogen oxides (from internal combustion engines and furnaces)
- runoff and erosion from cultivation, mining, construction and land use