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Hydrology and Water Quality

Water

Molecular Water

Exists as an equilibrium

But equilibrium altered by what is dissolved in it

WaterMolecular Water – a great solvent

•In reality, water in the environment is a “solution” and a “suspension”•Solutes, colloids, and particulates from many sources found in waterWHERE DO THESE ADDITIONS COME FROM?

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Hydrologic Cycle

97.5 +

1.81 +

0.005 +

0.016 +

0.001 +

0.63 =

99.962%Leaving

0.038%

Water cycles in the environment

The Earth’s Freshwater• Fresh water is a finite natural resource• Majority of Earth's water is in oceans which is not

readily potable • Water consumption in the U.S./world is increasing

Constituents of the solution we call freshwater are the result of

• Geology• Geography/Climate• Location• Use

Diagram from

‘90s

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2006

1 km3 = 264,172,051,242 gallons

The Environmental Technologist’s Understanding Of Water

• Interacts with soil and rock at and below Earth’s surface

– geology affects water, water affects geology

– rainfall and topography affect water’s interactions with geology within watershed

• Interacts with organisms (like transpiration) including human technology and population

• Weather and climate affect the availability of water in the country

Since humans rely on water, ET seeks to provide it, protect it, and control it

Rock Formations

Not as solid as you think

• Can be porous – porosity = % occupied by voids – spaces where water may move, reside

• Can be permeable (permeability) – water can (slowly) flow through the pore spaces

• Can be soluble – develop solution cavities, affect water chemistry

• Otherwise solid rock possesses fractures, fissures, faults that allow water to enter

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Surface WaterReminder: What is surface

water?

• creeks, streams, rivers

• Impoundments (constructed)

• Wetlands, ponds, lakes, oceans

Surface Water Terms

Watersheds and

subwatersheds

Point of

concentration

Stream order

headwaters

Ridge line

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Watershed Concerns

• Rainfall effects

– Human use

• Drinking

• Industry

• Wastewater assimilation

– Erosion

– Design of stormwater management structures

– Design of drinking water reservoirs

– Flooding

Rain

• Of importance to environmental technologists:

– How much – total inches in single event

– How often – number of events

– How intense – rainfall total per hour

• All are described and modeled for prediction purposes

• Example: hydrographs --

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Water Quality

Categories of Constituents:

Type and concentration determine “water quality”

• Physical ‘constituents’ - characteristics

• Chemical constituents

– Inorganics

– Organics

• Biologic constituents

Turbidity

• Suspended solid materials

– Clay, silt, organic matter, microbes

• Natural sources – erosion, living things

• Anthropogenic sources – organic enrichment, development/construction

• 5 TU noticeable

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Turbidity

• Affects drinking water treatment and aesthetics

• Significantly affects aquatic life

– Suspended load -Transparency and primary productivity

Habitat Loss

Bed load -‘Silting in’

Affects benthic community

Temperature

• Significantly affects aquatic life

– Optimum temperature

• Coldwater versus warmwater species– Too warm a temperature can stimulate growth of undesirable

populations

• Acclimatization– Quick changes devastating

– Relationship to dissolved oxygen concentration

• Humans like drinking cold water!

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Color, Taste, and Odor

• Primarily drinking water or aesthetic issue

– Drinking water must look, taste, and smell good even if it is completely safe to drink

– Laundry issues

– Various measurements are used

• In aquatic systems, color is aesthetic issue and possibly a transparency one

Dissolved Oxygen Concentration

• Ecologically, one of the most important chemical parameters of water quality

• Oxygen gas does dissolve in water – mg O2/l

– Saturation is temperature dependent

• Most life on planet adapted to oxygen

– Important to aerobic metabolism

• Without it, no metabolism

• Aerobes compete for DO

• DO directly related to aeration and temperature

Biochemical Oxygen Demand

• Utilization of oxygen by aerobic microorganism community as they metabolize organic materials

– Organics decomposed (oxidized) to CO2 and H2O, theoretically

– Oxygen availability limits what can be done aerobically

• Organic concentration directly impacts BOD

• Affected by temperature

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Biological Oxygen Demand

• A conventional pollutant – lack of control significantly impacts water quality

• BOD has been controlled by municipal sewage treatment

Biological Oxygen Demand – Ecological Effects

Waste Assimilation in Waterways

• It’s real if the waste is– Biodegradable

– Pollutant loading not too strong and not too often

– Water flow and aeration provide dilution, volatilization, and O2 for aerobic biodegradation

• Persistent chems do not assimilate– Dilute

– Are lost to sediment only to reappear

• Note the BOD example

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Types of BOD• Ultimate BOD – BODL

– mg/l of O2 needed to completely oxidize organics

– ‘strong’ sewage needs more O2

• 5-day BOD – BOD5 - a management tool

– Change in DO during 5-day, 20°C incubation in dark

• 1 mg/l natural background

• >10 mg/l significantly organic enriched

– Dilution

– Seeding

Solids

• Suspended or dissolved

– Suspended solids contribute to turbidity

– Dissolved solids also related to the parameters of hardness, alkalinity, nutrients

• Measurements:

– Total Suspended Solids – ml/l, mg/l – Turbidity!

– Total Dissolved Solids – mg/l

• Impacts drinking water treatment and aquatic life

Undesirable Dissolved Solids

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Hardness and Alkalinity• Measure of Ca+2 and Mg+2 (hardness) and

buffering capacity (alkalinity) of water

– Both naturally occurring

– Reported as mg CaCO3/l

• Hardness presents challenges for drinking water use and delivery

• Related parameter acidity, has implications for drinking water delivery and taste

• Implications for aquatic life

Nitrogen and Phosphorus Compounds

• Ammonia

– Toxicity and BOD

• Nitrate

– Plant nutrient

• Phosphate

– Often a ‘limiting’ nutrient

Ammonia

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Nutrient Enrichment

pH

• Naturally occurring and controlled

• Human sources must be controlled or devastating effects on aquatic life

• A ‘conventional’ pollutant

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Residual Chlorine

• Different from Cl-, a naturally-occurring ion

• Added to drinking water for disinfection and protection during delivery

• Disinfection by-products

• Significant implications for aquatic life

Toxics

Organics And Inorganics

– heavy metals

– pesticides

– Hydrocarbons including chlorinated hydrocarbons

– miscellaneous synthetics

Biologic Constituents of Water

• Microbes

– Virus

– Bacteria

– Protozoa

– Algae

– Fungi

• Invertebrates

• Vertebrates

• Presence or absence gives indication of water quality

• Lack of diversity can be a sign of poor water quality

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Indicator Organisms

• Fecal coliforms

– Community of organisms that inhabit the colons of humans (and other warm blooded animals)

– Not all bad but indicate presence of contamination with fecal wastes, likely human

• Greater the number, the greater the probability of illness-causing organisms present

Indicator Organisms

• Protection and disinfection of drinking water the single most significant factor in extending human life span

• Nearly doubled since the advent of drinking water treatment

Water Pollution

“In general terms, water is considered to be polluted when it contains enough foreign

material to render it unfit for a specific beneficial use, such as for drinking,

recreation, or fish propagation.”

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Urban Hydrologic CycleWater use:

public,

industrial,

commercial

Water source:

Streams, rivers,

lakes,

groundwater

Wastewater

treatment

Water

treatment

Sources of Water Pollution• Point source

discharges

• Non point (dispersed) sources

• Discharge of dredge or fill materials

% Impaired River Miles – U.S.

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Causes of River Impairment

Point Source Discharges

• Municipal and industrial effluents

– Contaminants present in varying concentrations

– Actual contaminants present a function of source

– Contaminant concentrations regulated based on numeric values, physical characteristics, or toxicity limits

Point Source Discharges

• Sewage treatment plants

• Steel mills

• Paper mills

• Chemical manufacturers

• Automakers

• Textile manufacturers

• Others!

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Non Point Sources

• Urban runoff

– Major source

• Construction sites

• Septic systems

Non Point Sources

Agricultural use and runoff

Non-Point Sources- Mining

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Thermal Pollution

• Cooling water

• Sources mostly under control using cooling ponds and towers

• May result from uncontrolled point sources, non-point sources, and habitat alteration

Non-Point: Soil Erosion

• Sediment moved by wind or water

• Sheet erosion

• Stream erosion

• Control

– Vegetative cover

– Soil erosion and sediment control plans

– Detention

Special Consideration for Lakes

• Eutrophication

– Natural process but accelerated ‘culturally’ by anthropogenic nutrients

– Oligotrophic

– Mesotrophic

– Eutrophic

• Advanced wastewater treatment

• Significant sources remain

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Lake Pollutants• Organics impact

oxygen profile

• Nutrients impact plant growth, organic production, and therefore oxygen

• Silts/sediments impact plant growth and temperature via shallowing

Groundwater PollutionGW quality generally good right out of the ground• Natural filtration of particulate

– But also inclusion of minerals, hardness

But, in some areas, impacted by• Land disposal

– Industrial– municipal

• Deep well waste management• Accidental spills• USTs• Septic systems• Abandoned wells• Mining and petroleum• Overuse – groundwater mining• Agricultural chemicals• Urbanization