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 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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Low medium high very high


Groundwater nitrate risk:

LowMediumHighVery High

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

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Types of water pollutants

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.

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Sources of water pollutants

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

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Federal Policy

1965 Water Quality Actrequired states to set ambient standards for water quality1972 Water Pollution Control Act Amendmentsset a “zero discharge” standard (inefficient!)set technology-based effluent standards and federal discharge permits1977Clean Water Actrequired Best Conventional Technology

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Biological Oxygen Demand (BOD)

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.”

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DO profile


Time or distance

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Emission vs. Concentration


Transfer coefficient

Transfer coefficient

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


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

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



Two sources, one receptor site.

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


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

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Zone Approach





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

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Key Points

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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