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Transcript of Lecture 3: Chemical Contaminantspkukmweb.ukm.my/zuhairi/Pengajaran/intranet/STAG3112/lecture...
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Lecture 3: Chemical Contaminants
Dr. Wan Zuhairi Wan YaacobProgram Geologi
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Principal groups of contaminants• INORGANIC
– Metals; Ca, Na, Mg, K– Heavy metals; Pb, Cu, Ni, Zn, etc– Cyanides; chlorides; asbestos fibre
• ORGANIC– Volatile organic compounds (VOC)– Chlorinated hydrocarbons – PCBs, solvents– Semi volatile compounds– Aromatics – phenols & Cresols ; PAH (polynuclear aromatic
hydrocarbons)– Pesticides & Herbicides– Petroleum hydrocarbons (oils; fuels; tars)
• OTHERS– Flammable materials - substances that can ignite easily and burn rapidly– Gases –CH4, H2S, NOx, SOx– Water quality indicators – BOD, COD, DO, TOC, pH, etc
Inorganic pollutants• ¾ of all known chemical elements• Forms in water:-
– Cations: Ca2+, Fe 2+ , K +, Al 3+ etc– Complexes : Zn(OH4)2+, Ca(P2O7) 2-
– Organometallics: Al(C2H5)3
• Particulate forms– Mineral sediments– Precipitated oxides, hydroxides, sulfides,
carbonates– Cations sorbed to soils
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Heavy metals
• Chromium• Copper • Cadmium• Mercury • Lead• Zinc• Arsenic
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• Aluminium• Beryllium• Bismuth • Chromium • Nickel • Cobalt• Selenium
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Organic chemical pollutants• Product of commercial use
– Organic solvents; paints; pesticides; oils; gasoline; greases; creasotes
• A million organic chemical; thousands are in chemical use.
• Three major groups:– (1) Hydrocarbons
• PHCs (petroleum hydrocarbons)• Alkanes• Alkenes• Aromatic hydrocarbons (benzene)• MAHS (multicyclic Aromatic Hydrocarbons)• PAHS (Polycyclic Aromatic Hydrocarbons)
– (2) Organohalide compounds• TCE, PBBs
– (3) other groupings
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Hydrocarbons• Aliphatic hydrocarbons – do not contain the
benzene ring– Alkanes, alkenes, alkynes
• Aromatic hydrocarbons – contain the benzene ring– Benzene, Toluene, Ethyl Benzene, Xylene (BTEX)– Polynuclear aromatic hydrocarbon (PAHs)
• Eg: asphalt, coal tar, creosote– Polychlorinated biphenyls (PCBs)
• Used in the manufacture of eletrical capacitors and transformers
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Persistent organic pollutants (POPs)
• Most unwanted chemicals in the world• Began in 1945: large-scale manufacture of DDT
– DDT: insecticide; control mosquitoes/insects– After 20 years: dying wildlife; eggs with thin shells– DDT was banned in USA in 1971
• Chemicals that may persist for very long periods of time in the environment (highly persistence).
• become concentrated in the food chain where they may cause toxic effects on animal reproduction, development, and immunological function (Bioaccumulative).
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Environmental Protection Agency list of priority pollutants
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POPs selected on theStockholm Convention(2001)
Organic pollutants (orproposed POPs)
Emerging POPs
Aldrin (carcinogenic)ChlordaneDDTDieldrin (carcinogenic)EndrinHeptachlorHexachlorobenzeneMirexToxaphenePCBsPCDDs/PCDFs
PCBsPCDDs/PCDFsPCNsPBDEsPBDDs/PBDFsPBBsPAHs
PBDEsPBDDs/PBDFsPBBs
Comparative lists of POPs selected for environmental and toxicological studies.
Before the dangers of DDT were known
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1
2
3
4
Stockholm convention on Persistent Organic Pollutants (POPs)
• The Stockholm Convention is a global treaty to protect human health and the environment from persistent organic pollutants (POPs).
• POPs are chemicals that remain intact in the environment for long periods, become widely distributed geographically, accumulate in the fatty tissue of living organisms and are toxic to humans and wildlife.
• POPs circulate globally and can cause damage wherever they travel
• In implementing the Convention, Governments will take measures to eliminate or reduce the release of POPs into the environment
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What are the criteria for POP in the Stockholm Convention on POPs (Procedure to add new POPs)?
• PERSISTENCE: half life of 2 months in water
• BIOACCUMULATION• ADVERSE EFFECTS: evidence of adverse
effects to human health or to the environment
• POTENTIAL FOR LONGE-RANGE ENVIRONMENTAL TRANSPORT: measured levels of the chemical in locations distant from the sources of its release that are of potential concern
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Dirty Dozen
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known as 'poisons without passports‘!!!
Dirty Dozen
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POP Global historical use/source1. DichlorodiphenylTrichloroethane (DDT)
-Insecticide used on agricultural crops, primarily cotton, and insects that carry diseases such as malaria and typhus. -Banned in 34 countries but used in many countries (Mexico, India, Thailand)
2. Toxaphene -To replace DDT in 1970s-Insecticide used to control pests on crops and livestock, and to kill unwanted fish in lakes.
3. PolychlorinatedBiphenyls (PCBs)
-Used for a variety of industrial processes and purposes, including in electrical transformers and capacitors, as heat exchange fluids, as paint additives, in carbonless copy paper, and in plastics. -Also unintentionally produced during combustion.
POP Global historical use/source4, 5. Dioxins and Furans -Unintentionally produced during most forms of
combustion, including burning of municipal and medical wastes, backyard burning of trash, and industrial processes. -Also can be found as trace contaminants in certain herbicides, wood preservatives, and in PCB mixtures.
6. Hexachlorobenzene(HCB)
-Fungicide used for seed treatment. -Also an industrial chemical used to make fireworks, ammunition, synthetic rubber, and other substances.-Also unintentionally produced during combustion and the manufacture of certain chemicals.-Also an impurity in certain pesticides.
7. Chlordane -Insecticide used on crops, including vegetables, small grains, potatoes, sugarcane, fruits, nuts, citrus, and cotton. -Used on home lawn and garden pests. Also used extensively to control termites.
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POP Global historical use/source8. Dieldrin -Insecticide with probably the strongest
carcinogenic effect amongst all organochlorinepesticides
9. Endrin -Insecticide used on crops such as cotton and grains
10. Aldrin -Insecticides used on crops such as corn and cotton; also used for termite control.
11. Mirex -Insecticide used to combat fire ants, termites-Also used as a fire retardant in plastics, rubber, and electrical products. (carcinogenic)
12. Heptachlor -Insecticide used primarily against soil insects and termites. -Also used against some crop pests and to combat malaria.
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http://www.atsdr.cdc.gov/tfacts35.html#bookmark06
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Organic chemical pollutants• Important: whether there are lighter or denser
than water• Well accepted classification: NAPL (non-
aqueous phase liquids)• Light NAPLS – LNAPLS – Lighter than water –
stay above the water table• Dense NAPLS – DNAPLS – Heavier than water –
sink through the water table• LNAPLS: Gasoline; heating oil; kerosene• DNAPLS: organohalide, 1,1,1 Trichloroethane,
creasote, pentachlorophenols, dichlorobenzene, etc.
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Geoenvironmental Engineering: Contaminated Soils, Pollutant Fate, and Mitigation. By Raymond N. Yong
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DNAPL & LNAPL• NAPL – was developed during hazardous waste
landfill in Niagara Falls, New York
• DNAPL– Dense, nonaqueous-phase liquid hydrocarbons– is a liquid that is denser than water and does not
dissolve or mix easily in water – chlorinated solvents, such as trichloroethylene;
tetrachloroetylene; etc
• LNAPL– Light, nonaqueous-phase liquid hydrocarbons– Lubricating oils; diesel fuel; jet fuel; gasoline
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NAPLs
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Geoenvironmental Engineering: Contaminated Soils, Pollutant Fate, and Mitigation. By Raymond N. Yong
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RESEARCH on DNAPL
• RESEARCH ON THE MOVEMENT OF DNAPL IN POROUS MEDIUM
• TANK MODEL
• COLUMN EXPERIMENT
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DNAPL
DNAPL
Water
Dyed PCE using Sudan (V)
Chlorinated organic solvents (Pelarut organic berklorin)
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Technical Factsheet : TETRACHLOROETHYLENE
Chemical/Physical Properties
• CAS Number: 127-18-4 • Color/ Form/Odor: Colorless liquid with mildy sweet, chloroform-like odor; available in many forms,
from worm pills to dry-cleaning grades containing various stabilizers. • Drinking water standard = 0.005 mg/L (5ug/L)• Vapor Pressure: 18.47 mm Hg at 25 C • Octanol/Water Partition (Kow ): Log Kow = 3.40 • Density/Spec. Grav.: 1.62 at 20 C • Solubility: 0.15 g/L of water at 25 C; Slightly soluble in water • Soil sorption coefficient: Koc= 210 to 238 ; low to moderate mobility in soil • Odor/Taste Thresholds: Taste threshold in water is 0.3 mg/L • Trade Names/Synonyms: Ethylene tetrachloride, Perchloroethylene, PCE, Ankilostin, Didakene,
Fedal-un, Nema, Perclene, Persec, Tetlen, Tetracap, Tetraleno, Tetropil, Antisal 1, Dow-per, Perawin, Perchlor, Percosolv, Perk, Perklone, Tetraguer, Tetralex, Tetravec
http://www.epa.gov/safewater/dwh/t-voc/tetrachl.html
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1-D Column Dissolution model experiment
Sand packing
Experimental set-up
Fired clay beads Glass beads
The measured data will be used to develop an empirical correlation to estimate mass transfer rate coefficient between NAPL-aqueous phases under one-dimensional flow conditions
Flow rate: 4.4 g/min
British Standard soil, Fraction C
Top view
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Ujian Tanki 2-Dimensi
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Objektif utama ialah untuk melihat (visualize) cara pergerakan TCE dalam pelbagai strukturgeologi di bawah permukaan bumi.
Sampel pelbagai gred (A&B) dipadatkan secara konsistenmenggunakan mechanical shaker
Dimensi tangki yang digunakan Keadaan tangki sebelum dimasukkan TCE
Dyed TCE using Sudan (V)
TCE - Trichloroethylene
1 minit 9 minit
60 minit18 jam
Hasil Ujian 3: Percubaan dengan kekantapasir yang miring
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Pasir Gred A / Sand
Pasir Gred B
Hasil Ujian 3: Percubaan dengankekanta pasir yang miring
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THE END