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ENVIRONMENTAL
MODELLING
Narsito
Department of ChemistryFaculty of Mathematics and Natural Sciences
Gadjah Mada University
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Our Problems
The world production of synthetic organic chemicals isabout 250 million metric tons per year (Korte 1992).
Every chemical sold is either destroyed by its use, that
produces degradation compounds, or released (via thesewer, the air or else), or is dumped, or incinerated afteruse.
Only a small fraction is re-used (recycled), meaning that
compounds, released from the factories, usually enterthe biosphere.
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If we are going to live so intimately with
these chemicals, eating and drinking them
into the very marrow of our bones, we had
better know something about their nature and
power.
- Rachel Carson, Silent Spring.
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The Scope of EnvironmentalModelling
Estimation of chemical exposure (usually done by applyingmathematical models) is becoming increasingly important,for 3 (three) reasons :
1. To gain a better understanding of the fate and transportof chemicals by quantifying their reaction, speciation,and movement.
2. To determine chemical exposure concentrations to
aquatic organisms in the past, the present, and/or thefuture.
3. To predict future condition under various loadingscenarios or management action alternatives.
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Environmental System
A (physical) system could be defined as a quantity ofmatter of fixed mass and identity on which attention isfocused for study.
The environmental system consists of :
Lithosphere
Hydrosphere
Atmosphere Biosphere
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Environmental System
Lithosphere
Hydrosphere Atmosphere
Biosphere
Terestrial Environment
Aquatic Environment Atmospheric Environment
Biotic Environment
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ECOSYSTEM Terestrial Ecosystem
Aquatic Ecosystem
Atmospheric Ecosystem
Biotic Ecosystem
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Ecosystem
ATMOSPHERICECOSYSTEM
AQUATIC
ECOSYSTEM
TERESTRIAL
ECOSYSTEM
BIOTIC/BIOLOGI-CAL ECOSYSTEM
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JOGJAKARTA - INDONESIA
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STRASBOURG - PERANCIS
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STUTTGART - JERMAN
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CURITIBA - BRASIL
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KALKUTA - INDIA
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HOW DANGEROUS IS OURENVIRONTMENT?
D A N G E R ?
H A Z A R D ?T O X I C ?
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Exposure ofCHEMICAL
SUBSTANCES
HUMANSPECIES
HRAHuman Risk Assessment
Acute Toxic Effect
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HUMANSPECIES
ENVIRONMENTALSYSTEMS
ERAEnvironmental RiskAssessment
Chronic Toxic Effect
Exposure ofCHEMICALSUBSTANCES
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ENVIRONMENTALSYSTEMS
NON HUMANSPECIES
ERAEcological Risk Assessment
Chronic Toxic Effect
HUMANSPECIES
Exposure ofCHEMICAL
SUBSTANCES
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Chemicals and Ecosystem
ATMOSPHERIC ECOSYSTEM
AQUATICECOSYSTEM
TERESTRIAL ECOSYSTEM
BIOLOGICALECOSYSTEM
Chemicals
Chemicals
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A GLOBAL ISSUE
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MORNING COASTAL WIN
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EVENING COASTAL WIN
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POLLUTION : A GLOBAL ISSUE
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The Scientific Rootsof Environmental Modelling
Chemicals in the environment
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To predict the environmental behaviourof chemicals led to the development ofmathematical models, which aredesigned to describe the transport andfate of chemicals under specialenvironmental conditions.
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Modelling of chemicals in environmental systems usesmethods of system analysis, model development, andsimulation of dynamic systems.
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Chemicals in the environment
Two different methods are identified :
1. The mechanistic method, which is basedon physical, chemical, and biological theories.
2. The empiric method, which uses measuredor observed data and parameters or timeseries.
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The Mechanistic Method :
The Flow Mechanistic Approach : Focuses on convectionand dispersion.
Typical examples : Models for atmospheric transport, andgroundwater simulation models.
This approach (roots are in physics) has been successfully usedin meteorology and hydrology for many years.
The Reaction Kinetic Approach : Focuses on chemicalphase transfers or biochemical transformations
Typical examples : The multimedia models.
It was originally derived from chemical engineering, has beenincreasingly used in environmental modelling.
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The empiric method
The method is very useful for systems and processes
that are too complex or too little understood for aphysico-chemical description.
Empirical relations found by experimental means may be used.
A typical example is the sorption of organic chemicals to humic
substances described by the KOC.
In the last years, it has been increasingly recognized thatthe environment needs to be considered as a system forsuccessful environmental protection.
The influence of chemicals on environmental systems can onlybe explained by the interaction of many single processes.
In the environment, chemicals are not controllable and maypersist a very long time before damage is apparent.
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SUBSTANCES
BIOTA SPECIES ECOSYSTEMSECOLOGY
ECOTOXICOLOGYMODELLING
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Risk Assessment
When compounds are released into theenvironment they should not reachenvironmentally damaging concentrations.
The concentration at the target is calledexposure (a term derived from toxicology).
The environmental hazard is the product of
exposure and its effect. The probability of a hazard multiplied by
the damage is the risk.
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Chemistry Problems !
A newly found chemical tends to be usedwithout enough supporting safety data,especially for the possible long termnegative effects.
At the time of finding, it is not easy for achemist to make such prediction for the
possible long term negative effects. The negative effects (especially chronic
effects) are usually identified after areasonable long period of time of uses.
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DDT Historydikloro difenil trikloroetana (Cobb dan Goldwhite, 1995)
1939-1970
1939 DDT was first founded by P Muller
1943 DDT was used successfully for typhoideradication in Italy.
1948 Noble Price in Chemistry was awarded for Muller
1955 WHO Recommendation for malaria control
1960 Applied in Green Revolution for rice production
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DDT Historydikloro difenil trikloroetana(Cobb dan Goldwhite, 1995)
1971-2004
1971 DDT was known to be persistent andcarcinogenic
1973 DDT was banned all over the world
2001 Stockholm Convention of May 2001
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Thank you