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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


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.


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

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