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Chapter 2 CHEMISTRY AND THE ANTHROSPHERE: ENVIRONMENTAL CHEMISTRY AND GREEN CHEMISTRY Environmental Chemistry, 9th Edition Stanley E.. 2.1 Environmental ChemistryEnvironmental chemistry

Chapter 2 CHEMISTRY AND THE ANTHROSPHERE: ENVIRONMENTAL

CHEMISTRY AND GREEN CHEMISTRY

Environmental Chemistry, 9th Edition

Stanley E Manahan Taylor and Francis/CRC Press

2010

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2.1 Environmental Chemistry

Environmental chemistry is the study of the sources,

reactions, transport, effects, and fates of chemical

species in the hydrosphere, the atmosphere, the

geosphere, and the anthrosphere and the effects of

human activities thereon

See Figure 2.1 (next slide) for an illustration of this

definition as exemplified by pollutant sulfur dioxide

Hãy xem trên hình vẽ slide trước và cho biết:

Major Categories of Environmental Chemistry

• Aquatic Chemistry deals with chemical phenomena in the

hydrosphere

• Biochemical processes are particularly important

• Atmospheric chemistry deals with chemical processes in the

atmosphere

• Many of these are photochemical

• Geochemistry and soil chemistry

• Toxicological chemistry

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2.2 Matter and Cycles of Matter

Global geochemical cycles involving the five spheres of the

environment and various reservoirs such as

• Oceans • Sediments • Soil • Air

Variable fluxes of matter flow

Often a strong biotic component such as

• Atmospheric CO 2 to biomass in the biosphere

• Biodegradation of organonitrogen compounds releasing N 2

Biogeochemical cycles, often elemental cycles involving

• Carbon • Oxygen • Nitrogen • Sulfur • Phosphorus

• Many powered by solar energy

• Mediated by organisms

• Plants • Microorganisms

Carbon Cycle

Nitrogen Cycle 9

The Oxygen Cycle (Chapter 9, Figure 9.11)

The Phosphorus Cycle 11

The Sulfur Cycle

2.3 The Anthrosphere and Environmental Chemistry

Anthrosphere : That part of the environment made or modified

by humans and used for their activities

Impact of humans

• Early impact was low, but not insignificant

• Impact in last 200 years has been enormous

•The anthropocene in which human activities predominate in

determining Earth’s environment

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The anthrosphere is categorized by the ways in which

humans do things and includes

• Dwellings

• Structures used for manufacturing, commerce, education, other

• Utilities such as water, fuel, electricity distribution systems

• Transportation systems such as railroads

• Components used for food production, processing, distribution

• Machines of all kinds

• Communications structures and devices

• Structures and machines used for extractive industries

• Mining • Petroleum production

Fig 2.7 Key Components of the Anthrosphere 15

2.4 Technology and the Anthrosphere

Technology refers to the ways in which humans do and make

things with materials and energy

• Metallurgy • Machines

Tremendous growth in technology in 1800s

• Steam power • Railroads • Telegraph

Since 1900

• Automobiles • Aircraft • Electronics • Petroleum use

Two major contributors to progress since 1900

• Electronics • Much improved materials

Computers are arguably making the greatest contribution to

progress now

Now the challenge is to reconcile progress with sustainability

2.5 Infrastructure

Infrastructure consists of utilities, facilities, and

systems used in common by members of society and

upon which they depend for their normal activities

• Water supply and distribution

• Waste treatment and distribution systems

Infrastructure deterioration is a major problem

• Corroded bridge structural members

* Deteriorated water distribution systems

Infrastructure vulnerable to attack

• Vulnerability due to interconnectivity

• Cascading failures on complex networks

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2.6 Components of the Anthrosphere That

Influence the Environment

Dwellings and buildings

• Many very inefficient

• Location (dwellings far from workplace) often a problem

• Potential of improved building materials

• Computerized control of heating and cooling

Communications: Acquisition, recording, computing,

displaying, transmission of information

• Huge advances made due to modern electronics

• Telematics with computer-based communications

Food and Agriculture

• Enormous environmental influence

• Loss of farmland to urban sprawl

• Loss of soil to erosion

• Practices such as low-tillage agriculture enhance

sustainability

Manufacturing

• Large pollution potential

• Important to consider environmental impact at early

stages

• Automation for repetitive tasks

• Robotics to simulate human activities

• Computer-aided design (CAD)

• Computer-aided manufacturing (CAM)

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2.7 Effects of the Anthrosphere on Earth (Fig 2.8)

2.8 Integration of the Anthrosphere into the Total Environment

Many effects on environment in last 200 years

• Alteration of geosphere

• Alteration of hydrosphere such as water diversion

Evolution of anthrosphere to more environmentally

compatible state (next slide)

The Anthrosphere and Industrial Ecology

• Industrial ecology is practiced when industrial enterprises interact in a mutually advantageous manner to produce

goods with minimum environmental impact and maximum efficiency

• Industrial ecosystems in which industrial ecology is

practiced

• Industrial metabolism for processing materials and energy

in industrial ecosystems

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Figure 2.9 Evolution of anthrosphere to more

environmentally compatible state

2 Use all materials

3 Avoid hazardous substances

4 Minimize toxicity

5 Minimize auxiliary substances

6 Minimize energy consumption

7 Use renewables

8 Minimize protecting groups

9 Maximize reagent selectivity

10 Degradability of products released

11 Monitor and carefully control processes

12 Avoid extremes

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Green Synthetic Chemistry

Key concept of atom economy, the fraction of all reagents that go into product

Risk Reduction

• Risk =F{hazardx exposure}

• Exposure reduction would be putting hazardous waste in a secure chemical landfill

• Hazard reduction would be changing waste to a non-hazardous form

• Hazard reduction is much preferable

Some Specific Aspects of Green Chemistry

1 Chemical transformations under mild conditions

2 Green catalysts

3 Solventless processes

4 Less dangerous, less polluting solvents

5 Use supercritical fluids (carbon dioxide)

6 Intensify processes, such as with small-volume reactors

7 Use electrons as mass-less reagents for oxidation and

Three undesirable characteristics of chemicals

1 Those that are persistent

2 Those that undergo bioaccumulation

3 Those that are toxic

Persistence/bioaccumulation/toxicity characteristics of common chemicals (PBT)

• U.S Environmental Protection Agency PBT Profiler on the

following website

http://www.epa.gov/oppt/sf/tools/pbtprofiler.htm

Green Chemistry and Environmental Chemistry

Green chemistry’s goal of environmental protection can best be

accomplished by the implementation of green chemistry

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