AGEC/FNR 406                                                         LECTURE 33
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AGEC/FNR 406 LECTURE 33. Groundwater nitrate risk:. Low Medium High Very High. Source: http://pasture.ecn.purdue.edu/~frankenb/watershedmap.html. Types of water pollutants.

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AGEC/FNR 406 LECTURE 33

Groundwater nitrate risk:

LowMediumHighVery High

Source: http://pasture.ecn.purdue.edu/~frankenb/watershedmap.html


Types of water pollutants LECTURE 33

1. Organic wastes: degradable wastes, residuals, some chemicals (detergents, pesticides, oil).

2. Inorganic substances: toxic metals, salts, acids, nitrate and phosphorous compounds.

3. Nonmaterial pollutants: heat, radioactivity.

4. Infectious agents: bacteria, viruses.


Sources of water pollutants LECTURE 33

1. Point sources: industry and municipal sewage treatment plants. “end of the pipe” typically continuous emission typically governed by Federal (EPA) standards

2. Nonpoint sources: agriculture, yard, and street runoff

hard to monitor episodic governed by states


Federal Policy LECTURE 33

1965 Water Quality Act required states to set ambient standards for water quality1972 Water Pollution Control Act Amendments set a “zero discharge” standard (inefficient!) set technology-based effluent standards and federal discharge permits1977 Clean Water Act required Best Conventional Technology


Biological Oxygen Demand (BOD) LECTURE 33

High quality water is usually associated with a high level of dissolved oxygen (DO).

DO is typically used up in the degradation process.Main source is treated municipal wastewater.One way to measure water quality is via “biochemical oxygen demand.”


DO profile LECTURE 33

DOppm

Time or distance



Transfer coefficient
Transfer coefficient LECTURE 33

A transfer coefficient measures the per unit relationship between a level of emission at a source and a constant concentration of the pollutant at a receptor site.


Transfer coefficient1
Transfer coefficient LECTURE 33

I

ai Ei + B

KR =

i =1

KR = concentration at receptor site

ai = transfer coefficient

Ei = emission level of ith source

B = background emission, if any


Cost effective clean up
Cost-effective clean up LECTURE 33

Policy Goal: Obtain given concentration target (not emission target) at minimum cost.

Procedure: translate emission reduction into concentration reduction.

Concentration = emission x transfer coefficientMC of concentration reduction = MC of emission reduction / transfer coefficient


Example
Example LECTURE 33

Two sources, one receptor site.

EA= 10/day, a = 0.50, MC = 100

R

EB= 10/day, a = 1.0, MC = 100

Concentration at R = 10*.5 + 10*1.0 = 15

MC of concentration reduction = 100/0.5 = 200 for A

MC of concentration reduction = 100/1.0 = 100 for B


Zone Approach LECTURE 33

B

C

A

R

Standards based on zone may be useful when monitoring costs are high


Key Points LECTURE 33

Goal: reduce damages at receptor site at lowest cost

How: balance the impact each polluter has (not on emission, but on concentration) with cost of reducing damages (in terms of concentration)

Key concept: Target concentration, not emission.


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