1. 1

2. OUTLINE
 Introduction
 Physical and Chemical Properties
 Sources of Mercury in the environment
 Application of Mercury
 Historic Application
 World Mercury Production and Consumption
 Toxicity
 Forms/Transformation of Mercury in the Environment
 Environmental Concern
 Effects on the Environment
 Environmental Control and Safety
 Environmental Regulation
 Situation in Ghana
 Conclusion
2

3. INTRODUCTION
3
 Mercury is a heavy silvery liquid metal with atomic number 80 a
standard atomic weight of 200.59. It is also known as quicksilver
or hydrargyrum from "hydr-" water and "argyros" silver.
 It is found in group 12 and period 6 of the d block transition
metals.
 Mercury is an extremely rare element in the earth crust with an
average abundance by mass of 0.08ppm. It rarely blends
geochemically with majority of the elements in the crust and it
ores can be up to 2.5% Hg by mass and even the least
concentrated deposits are at least 0.1%.
Elemental mercury

4. PHYSICAL PROPERTIES
 It is a silvery liquid metal and the only metal that is liquid at standard
conditions for temperature and pressure (using current IUPAC's standard,
temperature of 0 °C (273.15 K, 32 °F) and an absolute pressure of
100 kPa (14.504 psi, 0.986 atm) besides bromine, and metals such as
caesium, francium, gallium and rubidium melt just above room
temperature.
 Has alow meltingpoint of-38.83oCandahigh boiling point of357oC.
 It vapour pressure varies at different temperature and pressure. (tendency
to evaporate at varying temperature and pressure). That is normal room
temperatureHg will vaporise.
4
PHYSICAL AND CHEMICAL PROPERTIES

5. Physical Properties Cont’d
 It a heavy metal with density of 13.6g/cm3. Thus objects such as bricks,
cannonballs, andlumpsoflead orironwill floatinMercury.
 Itis apoorconductor ofheatbutafairconductor ofelectricity
 Although mercury is a liquid it is not wet. It has a negative coefficient of
surface tension, which means that the meniscus on the surface is the
other way up from normal, or to put it another way it does not soak into
materialbutrunsoffin thestyleof"water off aduck's back".
5

6. CHEMICAL PROPERTIES
 Mercury has 7 stable isotopes. These include 196Hg, 197Hg, 198Hg
199Hg, 200Hg, 201Hg and 202Hg. 202Hg being the most abundant
(29.86%). The longest-lived radioisotopes are 194Hg with a half-
life of 444 years, and 203Hg with a half-life of 46.612 days. Most of
the remaining radioisotopes have half-lives that are less than a
day. 199Hg and 201Hg are the most often studied NMR-active
nuclei, having spins of 1⁄2 and 3⁄2 respectively.
 Hg react with oxygen in the air very readily and reacts also with
some hot acids such as sulfuric acid and nitric acid or aqua regia
to give sulfate, nitrate, and chloride salts.
 The extraction of elemental Hg is by heating Cinnabar (HgS ) in
current air and condensing the vapour.
HgS +O2 Hg + SO2
6

7. Chemical Properties Cont’d
 Mercury exist in two main oxidation state, +1 and +2. Ahigher oxidation
state has been detected in the form of mercury (IV) fluoride (HgF4) but
onlyunder extraordinaryconditions.
 The most important salts are mercuric chloride HgCl2 (corrosive sublimate
— a violent poison), mercurous chloride Hg2Cl2(calomel, occasionally still
used in medicine), mercury fulminate (Hg(ONC)2), a detonator widely
used inexplosives, and mercuric sulfide (HgS, vermillion, a high-grade
paint pigment).
7

8. CHARACTERISTICSOF MERCURY(I),(II) ANDORGANOMERCURYCOMPOUNDS
MERCURY(I)COMPOUNDS:
 The mercury(I) compounds are diamagnetic and feature the dimeric
cation, Hg2
2+ and Stable derivatives include the chloride and nitrate.
 Treatment of Hg(I) compounds complexation with strong ligands such as
sulphide, cyanide, etc induces disproportionation to Hg2+ and elemental
mercury (Hg0).
 Mercury(I) chloride, a colourless solid also known as calomel (Hg2Cl2),
with the connectivity Cl-Hg-Hg-Cl. It is a standard in electrochemistry. It
reacts with chlorine to give mercuric chloride, which resists further
oxidation.
 Hg (I) forms mercurous salt
MERCURY(II)COMPOUNDS:
 Mercury(II) oxide, the main oxide of mercury, arises when the metal is
exposed to air for long periods at elevated temperatures. It reverts to the
elements upon heating near 400 °C. Hydroxides of mercury are poorly
characterized, as they are for its neighbors gold and silver.
8
Chemical properties Cont’d

9.  Hg (II) forms mercuric salts
ORGANOMERCURYCOMPOUNDS:
 Organic mercury compounds are historically important but are of little
industrial value in the western world.
 Organomercury compounds are always divalent and usually two-
coordinate and linear geometry.
 Unlike organocadmium and organozinc compounds, organomercury
compounds do not react with water. They usually have the formula
HgR2, which are often volatile, or HgRX, which are often solids, where
R is aryl or alkyl and X is usually halide or acetate.
 Methylmercury, a generic term for compounds with the formula CH3HgX
is a dangerous family compounds that is found in some a polluted water.
9
Chemical properties Cont’d

10. SOURCES OF MERCURY IN THE ENVIRONMENT
NATURAL SOURCES:
 Volcanoes
 Forest Fires
 Weathering of Mercury bearing rocks or Geologic deposits like Cinnabar or
mercury (II) sulfide (HgS), Cordierite – (Hg3S2Cl2), Livingstonite - Mercury
Antimony sulfosalt mineral (HgSb4S8)
 volatilization from the ocean.
These are responsible for approximately half of atmospheric mercury emissions.
Native mercury (Cinnabar)
10

11. ANTHROPOGENIC SOURCES:
The human-generated half can be divided into the following
estimated percentages:
 65% from stationary combustion, of which coal-fired power plants
are the largest aggregate source (40% of U.S. mercury emissions
in 1999). This includes power plants fueled with gas where the
mercury has not been removed. Emissions from coal combustion
are between one and two orders of magnitude higher than
emissions from oil combustion, depending on the country.
 11% from gold production. The three largest point sources for
mercury emissions in the U.S. are the three largest gold mines.
Hydrogeochemical release of mercury from gold-mine tailings has
been accounted as a significant source of atmospheric mercury in
eastern Canada.
 6.8% from non-ferrous metal production, typically smelters.
 6.4% from cement production.
11

12.  3.0% from waste disposal, including municipal and hazardous
waste, crematoria, and sewage sludge incineration. This is a
significant underestimate due to limited information, and is
likely to be off by a factor of two to five.
 3.0% from caustic soda production.
 1.4% from pig iron and steel production.
 1.1% from mercury production, mainly for batteries.
 2.0% from other sources.
The above percentages are estimates of the global human-caused
mercury emissions in 2000, excluding biomass burning, an
important source in some regions.
12
Sources of mercury Cont’d

13. APPLICATION OF MERCURY
AS A METAL:
for extraction of gold and silver
as a catalyst for chloralkali production
in manometers for measuring and controlling pressure
in thermometers for taking body temperature
in electrical and electronic switches
in fluorescent lamps
as dental amalgam fillings
In the 19th century Mercury was used for numerous
conditions including constipation, depression, child bearing
and toothaches.
13

14. Application of Mercury Cont’d
 In liquid-mirror telescopes
 Early in the 20th century, mercury was administered to
children yearly as laxative, dewormer and in teething
powders for infants.
 Used as a working fluid for a heat pipe type of cooling
device for spacecraft heat rejection systems.
 Gaseous Mercury is used in Hg-vapour lamps. At low
pressure the lamps emit spectrally narrow lines which
are traditionally used in optical spectroscopy for
calibration of spectral position.
14

15. AS CHEMICAL COMPOUNDS :
in batteries (as a dioxide)
biocides in paper industry, paints and on seed grain
as antiseptics in pharmaceuticals
 laboratory analyses reactants
pigments and dyes (may be historical)
 detergents (may be historical)
 explosives (may be historical)
for cosmetics - mascara (banned in the US 2008)
 treatment of syphilis (mercuric chloride)
mercury (I) chloride has been used as a topical
disinfectant and laxative
15
Application of Mercury Cont’d

16. IDENTIFIED MERCURY APPLICATIONS, AND INDICATIONS OF THEIR CURRENT USE.
Application Indications of current use
Chlor-alkali production (chlorine and caustic soda) General
Dental amalgam General
Artisanal gold and silver mining Australia, Burundi, Brazil, Burkina Faso(?), China, Costa Rica, Colombia, Côte d’Ivoire(?), Ecuador, Colombia,
French Guyana, Ghana, Indonesia, Mongolia, Panama, Papua New Guinea, Peru, Philippines, Russia, Tanzania,
Venezuela, Vietnam, Zimbabwe
Batteries In use, but banned or restricted in many countries
Medical thermometers General, but banned or restricted in a few countries
Other thermometers (marine engine control, laboratory) General, but banned or restricted in a few countries
Blood pressure gauges (sphygmomanometers) General, but banned or restricted in a few countries
Industrial and meteorological manometers Most likely general, but banned or restricted in a few countries
Pressure valves (district heating systems, industry) Banned or restricted in a few countries
Gyroscopes Banned or restricted in a few countries
Electric and electronic switches Banned or restricted in a few countries
Level switches (sewer pumps, door bells, railway signals, car boot lids, refrigerators, freezers, fall-alarms for
the elderly, etc.)
Banned or restricted in a few countries
Multiple poled switches (for example in excavation machines) Banned or restricted in a few countries
Mercury-wetted microelectronic switches Most likely general
Thermo-switches Banned or restricted in a few countries
Switches in sports shoes with lights in soles Banned or restricted in a few countries
Discharge lamps General
Fluorescent lamps General
Other mercury-containing lamps General
Laboratory chemicals, electrodes and apparatus for analysis General
Pesticides (seed dressing and/or others) Australia, Belarus, Benin (unspecified), Burkina Faso (unspecified), Côte d’Ivoire, Ghana, Guinea
(unspecified), India (unspecified), Ireland
Biocides for different products and processes Cameroon (unspecified industrial production), Ireland
Paints (latex paints and possibly others) Australia, Ghana, Guinea, India, Ireland, Samoa, Thailand (substitution ongoing), Trinidad and Tobago
(subst. ongoing or completed recently)
Slimicides for paper production Morocco,
Pharmaceuticals (biocide or systemic functions) Czech Republic (unspecified), Ghana (unspecified), India, Australia (unspecified and for horses), Switzerland
Preservatives in vaccines In use
Preservatives in eye drops Most likely still in use
Disinfectants, e.g. in hospitals Burkina Faso (unspecified)
Herbal medicine, “folk” medicine, “street pharmacies” India (some herbal medicines), Lesotho (metallic mercury)
Catalytic mercury compounds India
Catalysts for polyurethane/other polymer production Finland, Australia, Ireland
Cosmetics (creams, soaps) Benin (unspecified), Ireland (unspecified)
Skin lightening creams and soaps In common use, restricted in some countries
Biocides in eye cosmetics Possibly in use, restricted in some countries
Lighthouses (marine use; for stabilising lenses) Canada (possibly general – mentioned in the literature)
Religious ceremonies “superstitious” activities USA and possibly Caribbean regions (US ATSDR, 1999), Lesotho
Tanning Ireland
Browning and etching steel Ireland
Colour photograph paper Australia
Artisanal diamond production Guinea (“to clean stones and improve physical quality”)
Recoil softeners for rifles Ireland
Arm and leg bands (e.g. for “tennis elbow”) Ireland
16

17. Overview of existing and future national actions, including legislation relevant to mercury
Application Import, sale and/or use banned or restricted nationally
Chlor-alkali production (chlorine and caustic soda) Japan
Gold extraction Brazil, China, Philippines
Mercury-containing products in general (with some exemptions) Denmark, Sweden, Switzerland
Dental amalgam Denmark, France, New Zealand, Norway, Sweden, Switzerland
Batteries Canada, China, Estonia, European Union countries*, Hungary, Mauritius, Norway, Slovak Republic,
Switzerland, Turkey, USA,
Mercury-oxide batteries European Union countries*, Japan
Alkaline batteries Canada, European Union countries*
Other batteries (zinc-oxide, silver-oxide, mainly button cell formats) Canada, European Union countries*
Measuring and control equipment Sweden (in general)
Medical thermometers Canada, Denmark, France, Norway, Sweden,
Other thermometers (marine engine control, laboratory) Denmark, Sweden
Blood pressure gauges
Industrial and meteorological manometers Denmark
Pressure valves (district heating systems, industry) Denmark
Gyroscopes Denmark
Electric and electronic switches Denmark, Sweden, Switzerland
Level switches (sewer pumps, door bells, railway signals, car back lids, refrigerators, freezers, fall-
alarms for old people, etc.)
Denmark, Sweden
Multiple poled switches (for example in excavation machines) Denmark
Mercury-wetted microelectronic switches
Thermo-switches Denmark
Switches in sports shoes with lights in soles Denmark
Discharge lamps
Fluorescent lamps Canada, Sweden, European Union countries* from 1 July 2006
Other mercury-containing lamps Denmark, Sweden
Laboratory chemicals, electrodes and apparatus for analysis Denmark, Sweden
Pesticides
Seed dressing and/or other agricultural uses Armenia, Burundi, Canada, China, Colombia, Cuba, Czech Republic, European Union countries*,
Hungary, Japan, Latvia, Lesotho, Lithuania, Mauritius, Norway, Samoa, Switzerland, Tanzania, USA
Biocides for different products and processes Denmark, Japan, Sweden, Switzerland
Paints (latex paints and possibly others) Cameroon, Costa Rica, European Union countries*, Japan, Norway, Switzerland, USA
Preservation of wood European Union*, Norway
Pharmaceuticals (biocide or systemic functions) Austria, Canada, Costa Rica, Denmark, Japan, Mauritius, Sweden, Switzerland, USA
Preservatives in vaccines
Preservatives in eye drops
Disinfectants, e.g. in hospitals Denmark
Herbal medicine, “folklore” medicine, “street pharmacies” Denmark
Catalytic mercury compounds
Cosmetics (creams, soaps) China, European Union countries*, Norway
Skin lightening creams and soaps Cameroon, Denmark, USA, Zimbabwe
Biocide in eye cosmetics
Production of counterfeit money
Religious ceremonies and so-called “superstitious” activities
Pigments Denmark
Explosives, fireworks Denmark
Airbag activators and anti-lock braking system (ABS) mechanisms in cars European Union countries*
Packaging and packaging waste European Union countries*, Norway
17

18. HISTORIC APPLICATION
 In China and Tibet, mercury use was thought to prolong life, heal
fractures, and maintain generally good health.
 One of China's emperors, Qín Shǐ Huáng Dì— allegedly buried
in a tomb that contained rivers of flowing mercury on a model of
the land he ruled, representative of the rivers of China — was
killed by drinking a mercury and powdered jade mixture (causing
liver failure, poisoning, and brain death) intended to give him
eternal life.
 The ancient Greeks use mercury in ointments.
 The ancient Egyptians and the Romans used it in cosmetics
which sometimes deformed the face.
 In Lamanai, once a major city of the Maya civilization, a pool of
mercury was found under a marker in a Mesoamerican ballcourt.
 By 500 BC mercury was used to make amalgams (Medieval
Latin amalgama, "alloy of mercury") with other metals.
18

19. WORLD MERCURY PRODUCTION AND CONSUMPTION
19
ESTIMATED WORLD PRODUCTION OF PRIMARY (MINED) MERCURY (METRIC TONS), AS REPORTED BY THE US GEOLOGICAL SURVEY AND BY HYLANDER &
MEILI (2002) FOR THE YEAR 2000.
COUNTRY 1981-1985 *1 1986-1989 *1 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000
Algeria 386-877 587-764 637 431 476 459 414 292 368 447 224 200 240
China 800 850-1200 1000 760 580 520 470 780 510 830 230 200 200
Finland *2 65-130 135-160 141 74 85 98 89 90 88 63 80 80 45
Kyrgyzstan - - - - 300 1000 379 380 584 610 620 620 600
Mexico 221-394 124-651 735 340 21 12 12 15 15 15 15 15 25
Russia - - - - 70 60 50 50 50 50 50 50 -
Slovakia /Cz 144-158 131-168 126 75 60 50 50 0 0 0 20 0 0
Slovenia - - - - 7 ? 6 0 5 5 5 0 0
Spain 1416-1560 967-1471 - - - 643 393 1497 862 863 675 600 237 *3
Tajikistan - - - - 100 80 55 50 45 40 35 35 40
Ukraine - - - - 100 50 50 40 30 25 20 - -
USA 570-962 140-520 562 58 64 w w w 65 w - - 15
USSR 1600-1700 1500-1650 800 750 - - - - - - - - -
Yugoslavia 0-88 51-75 37 9 - - - - - - - - -
Other countries 200-400 100-200 - - - - 223 200 - - 830 380 448
Totals for reported
activity (rounded)
5500-7100 4900-6700 4000 2500 1900 3000 2200 3400 2600 2900 2800 2200
Derived by Hylander
& Meili (2002)
5600-6100 6100-6600 6100 3700 3100 3000 2000 3300 2800 2500 2000 2100 1800
Notes and legend:
w Withheld in the references , - Not relevant or not available, /Cz Up to 1992 as part of Czechoslovakia
1 Reference: Metallgesellschaft (1992), as cited by OECD (1994). This reference's totals for 1990 and 1991 were 400-900 metric tons higher than the presented totals from USGS.
2 Numbers for Finland from 1990-1997 are from Finnish Environment Institute (1999).
3 Spain has reported a production in 2000 of 237 metric tons from the Spanish mercury mines.

20. GLOBAL CONSUMPTION OF MERCURY IN METRIC TONS/YEAR
COUNTRY
REPORTED ANNUAL CONSUMPTION (OR IMPORT), METRIC TONS/YEAR UNLESS
NOTED
YEAR(S) REFERENCE
Australia >30 tons metallic mercury imported
1996 National submission, sub63gov+ 5 tons produced as by-product
+ 4 tons import of mercury compounds
Canada 2.8-2.9 tons consumption, metallic mercury
1998-1999 National submission, sub42gov
(of 9.4-11.4 tons imported)
Denmark
1.5 tons total consumption (including with products, domestic and imported) 2000/2001
Submission from the Nordic Council of
Ministers, sub84gov
Finland App. 10 tons comsumption
1991 National submission, sub44gov
(mercury produced as by-product, see table 7.2)
France 45 tons net import averaged over 3 years Averaged over 1998, 1999 and 2000
(individual years in brackets)
Comments from France, comm-10-gov
(2, 112 and 20 tons respectively)
India
170-190 tons imports of metallic mercury
Not mentioned (presumably relatively
recent estimate)
National submission sub71govatt1
Norway 0.8-1.4 tons consumption with products only, additional consumption as
metallic mercury
1995/1999
Submission from the Nordic Council of
Ministers, sub84gov
Peru 30-45 tons import of metallic mercury
1998-2000 National submission, sub47gov+ 19-48 tons produced as by-product
+ small import of compounds
Philippines 55.658 tons import of metallic mercury 1999
National Statistics Office & Bureau of Export
Trade Promotion, DTI Philippines (comm-4-
gov)
26.169 tons import of metallic mercury 2000
19.100 tons import of metallic mercury 2001
Sweden 2 tons consumption with products only, additional consumption as metallic
mercury
1997
Submission from the Nordic Council of
Ministers, sub84gov
Switzerland 30 tons import (uncertain estimate) “Late 1990’s” National submission, sub38gov
Thailand 12,1 tons import of metallic mercury 2000
National submission, sub53gov,
www.customs.go.th (2805.40)
17.2 tons import of metallic mercury 2001
5.8 tons import of metallic mercury Jan.-June 2002
(mostly for fluorescent lamp production, and a little for dentistry and lab
analysis)
Turkey 4.5 “of mercury and its compounds imported” 2000-2001 National submission, sub34gov
USA 372 tons consumption, including with products produced in the USA (not
imports)
1996 Sznopek and Goonan, 2000
20

21.  In 2005, China was the top producer of mercury with almost two-thirds
global share followed by Kyrgyzstan. Several other countries are believed
to have unrecorded production of mercury from copper electrowinning
processes and by recovery from effluents.
 The European Union directive calling for compact fluorescent bulbs to be
made mandatory by 2012 has encouraged China to re-open deadly
cinnabar mines to obtain the mercury required for CFL bulb manufacture.
As a result, environmental dangers have been a concern, particularly in the
southern cities of Foshan and Guangzhou, and in the Guizhou province in
the south west.
 Abandoned mercury mine processing sites often contain very hazardous
waste piles of roasted cinnabar calcines. Water run-off from such sites is a
recognized source of ecological damage. Former mercury mines may be
suited for constructive re-use. For example, in 1976 Santa Clara County,
California purchased the historic Almaden Quicksilver Mine and created a
county park on the site, after conducting extensive safety and
environmental analysis of the property.
21

22. 22
AMOUNT OF ATMOSPHERIC
MERCURY DEPOSITED AT WYOMING'S
UPPER FREMONT GLACIER OVER THE
LAST 270 YEARS

23. TOXICITY
 The toxic effects of mercury depend on its chemical form and the
route of exposure.
 The risk is determined by the likelihood of exposure, the form of
mercury present (some forms are more toxic than others), and
the geochemical and ecological factors that influence how
mercury moves and changes form in the environment.
 Research has shown that mercury can be a threat to the health
of people and wildlife in many environments that are not
obviously polluted.
 Methyl-Hg or MeHg+ is a potent neurotoxin, damages the central
nervous system and especially toxic to fetus.
23

24.  The primary mechanisms for transporting mercury from the
atmosphere to terrestrial and aquatic systems are:
o Wet Deposition – Rain, Fog and Snow
o Dry deposition – Gravitational sedimentation
 The main pathway of human exposure to this toxic metal is
through the consumption of Hg contaminated fish as illustrated
by the mass Hg poisoning in Minamata Bay and Agano River in
Japan (D’Itri & D’Itri, 1977; Takizawa,1979) during the 1950s and
1960s.
 Current atmospheric mercury contamination in outdoor urban air
is (0.01–0.02 µg/m3) indoor concentrations are significantly
elevated over outdoor concentrations, in the range 0.0065–
0.523.
Hg(CH3)2= CH3Hg >Hg2+ >Hg0
Increasing toxicity
24
Toxicity Cont’d

25. Elemental mercury, Hg0 (Metal and Gas)
 It is quite volatile and only slightly soluble in water.
 It is dispersed very effectively through the atmosphere
with long residence times of about 2 years, and is
normally transported from likely sources of emission
(Lodenius & Malm, 1998; Boening, 2000).
Mercury (II)
 It is more prevalent in the environment and form
tetrahedral complexes with other ligands but the halides
adopt linear coordination geometry, somewhat like Ag+
does. Best known is mercury(II) chloride, an easily
sublimating white solid.
25
FORMS/TRANSFORMATION OF MERCURY IN THE
ENVIRONMENT

26. Forms of mercury in the environment cont’d
Being a soft metal", it forms very stable derivatives
with the heavier chalcogens. Preeminent is
mercury(II) sulfide, HgS, which occurs in nature as
the ore cinnabar and is the brilliant pigment
vermillion.
Like ZnS, HgS crystallizes in two forms, the
reddish cubic form and the black zinc blend form.
Mercury(II) selenide (HgSe) and mercury(II)
telluride (HgTe) are also known, these as well as
various derivatives, e.g. mercury cadmium
telluride and mercury zinc telluride being
semiconductors useful as infrared detector
materials.
26

27. Methylmercury, CH3Hg+
 It is the most toxic of the forms and referred to as the bioacummulative
environmentaltoxicant.
 Methylmercury is a shorthand for Monomethylmercury and most correctly
monomethylmercuric cation. It is composed of a methyl group
(CH3-) bonded to a mercury atom; its chemical formula is CH3Hg+
(sometimes written as MeHg+).
 It is formed from inorganic Hg by action of anaerobic organisms
(methanogenic (TK) bacteria (that produce methane)), that live in
aquatic systems like rivers, lakes, wetlands, sediments, soils and open
ocean.
 The process by which inorganic Hg is converted to Methylmercury in natural
environment is known asMethylation.
 Certain types of wetlands and dilute low-pH lakes favour the
formation of methyl mercury.
27
Forms of mercury in the environment cont’d

28.  As a positively charged ion it readily combines with anions such
as chloride (Cl−), hydroxide (OH-) and nitrate (NO3
−).
 It also has very high affinity for sulfur-containing anions,
particularly the thiol (-SH) groups on the amino acid cysteine
and hence in proteins containing cysteine, forming a covalent
bond. More than one cysteine moiety may coordinate with
methylmercury, and methylmercury may migrate to other metal-
binding sites in proteins.
 It is very soluble in lipids and, therefore, crosses biological
membranes with ease and with a half-life of 70 days in humans.
Because of its protein binding properties, it readily bio-
accumulates and bio-magnifies in aquatic food chains. As a
result, it poses a threat to humans and other fish-eating animals
(Lodenius & Malm, 1998).
Structureof Methylmercury
H3C Hg
+
X
-
Forms of mercury in the environment cont’d

29. Dimethlymercury, ((CH3)2Hg)
It is a colorless organomercury compound and one
of the strongest known neurotoxins. It can be
extremely toxic.
It is described as having a slightly sweet smell,
although inhaling enough vapor to detect its odor
would be hazardous.
It is formed by treating sodium amalgam with
methyl halides.
Hg + 2Na + 2CH3I→ (CH3)2Hg + 2NaI
29
Forms of mercury in the environment cont’d

30. It can also be obtained by alkylation of mercuric chloride
with methyllithium. The molecule adopts a linear
structure with Hg-C bond lengths of 2.083 Å.
It is nonreactive toward water.
Structure of Dimethylmercury
30

31. 31

32. MERCURY RELEASE TO ECOSYSTEM IN SMALL-SCALE GOLD MINING
32

33. ENVIRONMENTAL CONCERN
Toxic nature ( poisonous)
Non-biodegradability
Environmental persistence
33

34. EFFECTS ON THE ENVIRONMENT
Human
 Elemental mercury, Hg0, when released from broken
thermometers, causes tremors, gingivitis, and excitability when
vapours are inhaled over a long period of time.
 Although it is less toxic than methylmercury, elemental mercury
may be found in higher concentrations in environments such as
gold mine sites, where it has been used to extract gold. If
elemental mercury is ingested, it is absorbed relatively slowly
and may pass through the digestive system without causing
damage. Hg2+ targets the kidney and liver and can cause
extensive damage.
 Methylmercury affects the immune system, alters genetic and enzyme
systems, and damages the nervous system, including coordination and the
senses of touch, taste and sight. It is particularly damaging to developing
embryos,which arefivetotentimesmoresensitivethanadults.
 Exposure to methylmercury is usually by ingestion, and it is absorbed more
readily and excreted more slowly than other forms of mercury.
Methylmercury has a half-life in human blood of about 50 days.
34

35.  Dimethylmercury crosses the blood–brain barrier easily. The
symptoms of poisoning may be delayed by months, possibly
too late for effective treatment. The toxicity of dimethylmercury
was highlighted with the death of the inorganic chemist Karen
Wetterhahn of Dartmouth College in 1997, months after spilling
no more than a few drops of this compound on her latex-gloved
hand.
 Studies has shown that acute exposure (4 – 8 hours) of
elemental mercury can be calculated with levels at 1.1 to 44
mg/m3 resulted in chest pain, dyspnea, cough, hemoptysis,
impairment of pulmonary function, and evidence of interstitial
pneumonitis.
 Acute exposure to mercury vapour has been shown to result in
profound central nervous system effects, including psychotic
reactions characterized by delirium, hallucinations, and suicidal
tendency.
35
Effects of mercury on the environment cont’d

36.  The dumping of industrial waste that resulted in the pollution and
subsequent mass poisoning in Minamata and Niigata, Japan and the
situation in Iraq in the 1960s and 1970s in which wheat treated with
methylmercury as a preservative and intended as seed grain was fed to
animals and directly consumed by people (see Basra poison grain
disaster).
 These episodes resulted in neurologic symptoms including paresthesias,
loss of physical coordination, difficulty in speech, narrowing of the visual
field, hearing impairment, blindness, and death. Children who had been
exposed in-utero through their mothers' ingestion were also affected
with a range of symptoms including motor difficulties, sensory problems
and mental retardation.
 Occupational exposure has resulted in broad-ranging functional
disturbance, including erethism, irritability, excitability, excessive
shyness, and insomnia. With continuing exposure, a fine tremor develops
and may escalate to violent muscular spasms. Tremor initially involves
the hands and later spreads to the eyelids, lips, and tongue. Long-term,
low-level exposure has been associated with more subtle symptoms of
erethism, including fatigue, irritability, loss of memory, vivid dreams, and
depression.
36
Effects of mercury on the environment cont’d

37. Wildlife and Fish
 In recent years, there has been increasing recognition that
methylmercury affects fish and wildlife health, both in acutely
polluted ecosystems and ecosystems with modest
methylmercury levels.
 Aquatic birds and animals that feed on fish in mercury
contaminated water bodies are susceptible to mercury
poisoning. Their protective enzymes are less effective following
exposure to mercury.
 Analyses of such biochemical indicators indicate that mercury is
adversely affecting diving ducks from the San Francisco Bay,
herons and egrets from the Carson River, Nevada, and heron
embryos from colonies along the Mississippi River.
37
Effects of mercury on the environment cont’d

38. 38
Fish-eating birds in certain parts of the
United States may ingest large amounts
of methylmercury in their diet.
Mercury can cause deformities
in developing animals.
Effects of mercury on the environment cont’d

39.  Two reviews document numerous studies of diminished
reproductive success of fish, fish-eating birds and mammals
due to methylmercury contamination in aquatic ecosystems.
 A study by U.S. researcher Peter Frederick suggests
methylmercury may increase male homosexuality in birds:
Except a control group, all of 160 captured young ibises were
given small amounts of methylmercury with their food. The
reproductive behaviour of these coastal wading birds
changed in such a way, that the more methylmercury was
ingested the more male birds choose to build nests with other
males, and snub females.
39
Effects of mercury on the environment cont’d

40. ENVIRONMENTAL CONTROL AND SAFETY
 In case of spill of elemental mercury sprinkle fine sulfur or zinc,
or some other powder that readily forms an amalgam (alloy)
with mercury at ordinary temperatures over the area before
collecting and properly disposing it of.
 Mercury can be inhaled and absorbed through the skin and
mucous membranes, so containers of mercury should be
securely sealed to avoid spills and evaporation.
 In the Ghanaian small scale gold mining glass retort was
introduced by German Agency for Technical Assistance (GTZ)
to recycle Mercury in order to control the inhaling and emission
of elemental mercury into the atmosphere during the burning of
the amalgam (gold and Mercury).
40

41.  Research on the treatment of mercury poisoning is limited.
Currently available drugs for acute mercurial poisoning include
chelators N-acetyl-D, L-penicillamine (NAP), British Anti-Lewisite
(BAL), 2,3-dimercapto-1-propanesulfonic acid (DMPS), and
dimercaptosuccinic acid (DMSA).
 In a study including 11 construction workers exposed to
elemental mercury, patients were treated with DMSA and NAP.
Chelation therapy with both drugs resulted in the mobilization of
a small fraction of the total estimated body mercury. DMSA was
able to increase the excretion of mercury to a greater extent than
NAP.
 Phytoremediation to decontaminate mercury polluted soils. This is
done by transgenic plants containing genes for bacterial enzymes.
An example is yellow poplar (Liriodendron tulipifera) , can absorb
enough toxic mercury compounds and convert it to elemental
mercury vapour which they exhale into the air.
41
Environmental Control And Safety cont’d

42. ENVIRONMENTAL REGULATION
 Due to the health effects of mercury exposure, industrial and
commercial uses are regulated in many countries. The World
Health Organization (WHO), Occupational Safety and Health
Administration (OSHA), and National Institute for Occupational
Safety and Health (NIOSH) all treat mercury as an occupational
hazard, and have established specific occupational exposure limits.
Environmental releases and disposal of mercury are regulated in
the U.S. primarily by the United States Environmental Protection
Agency.
 In July 2007, the European Union also banned mercury in non-
electrical measuring devices, such as thermometers and
barometers. The ban applies to new devices only, and contains
exemptions for the health care sector and a two year grace period
for manufacturers of barometers.
 Norway enacted a total ban on the use of mercury in the
manufacturing and import/export of mercury products, effective
January 1, 2008. In 2002, several lakes in Norway were found to
have a poor state of mercury pollution, with an excess of 1 mg/g of
mercury in their sediment.
42

43. SITUATION IN GHANA
 Available information at the Ministry of Trade, EPA, Ghana Standards
Board and Customs, Excise and Preventive Service revealed that, private
companies as well as institutions or their agents could obtain licence to
import mercury.
 Available statistics show that the mercury enters the country through the
main points of entry: Kotoka International Airport (KIA) (55.1%), Tema
(36.7%), Takoradi (6.3%) and Aflao (2.1%). Imports between 1989 and
2000.
 Mercury is imported mainly for the mining sector (80.4%), health (11.7%)
and education (7.8%). The values represent the frequency of import. The
estimated quantity of mercury metal imported into the country between
1994 – 2000 is about 36,294 kg. This excludes mercury compounds for
educational and health institutions.
 The right to import possess and distribute/sell the chemical is regulated by
the Mercury Law, 1989, PNDC L 217 and the Small-Scale Gold Mining
Law 1989, PNDC L 128. These two laws are subsidiary legislation to the
main law on mining, Minerals and Mining Law, PNDC L 153, 1986. But
currently there is no information on the distribution pattern and
transportation of the chemical in the country.
43

44. SITUATION IN GHANA
 The law requires small-scale gold miners to observe good mining
practices in the use of mercury for carrying out mining operations .
 The holder of a mineral right shall in the exercise of his rights under the
license or lease have due regard to the effect of the mineral operations on
the environment and shall take such steps as may be necessary to
prevent pollution of the environment as a result of such mineral operation.
 These laws do not deal with other users of mercury like health and
educational institutions. There are also no records on what quantities of
mercury are allowed into the immediate environment or what residual
quantities are still in the system.
 Officials of the Minerals Commission and the EPA, are of the view that
currently the level of awareness among artisanal gold miners is very low.
44

45. SITUATION IN GHANA
 Miners still handle the chemical in the open and without protective gear;
they burn off the mercury from the amalgam in open containers. Some
also keep the chemical on their body (in the pockets).
 Education of the miners on the health and environmental hazards of
mercury (by Minerals Commission) is ongoing. The miners have also been
introduced to the retort, which would allow them not only to recover the
mercury for reuse, but also prevent same from getting into the
environment. Due to the high cost of the retort (current subsidised price is
$100), many are unable to afford.
 Various studies in Ghana indicates:
 the mercury levels found in soils/sediment in the Obuasi area range
from 0.46 to 50.48ppm. Mercury is readily adsorbed onto sediment
and is slowly released to the water forming a reservoir capable of
causing chronic pollution long after the original source of mercury has
been removed.
45

46. SITUATION IN GHANA
 Levels of the chemical found in fish (mudfish, tilapia and catfish) in the
Dumasi area ranged from 0.46 - 6.42ug/g dry wt. The values are in the
same range of concentrations as found in other gold mining areas,
especially Brazil and Tanzania. It would take an average
consumption of only 45g of fish per day to exceed WHO’s weekly
tolerance of 300ug .
 in the Dunkwa and Tarkwa areas, total mercury levels in fish ranged
from 0.01 to 2.50ug/g wet wt. 9.3% of the fish analysed exceeded
0.5ppm, the WHO (1976) guideline for mercury in fish .
 levels of mercury obtained for surface and borehole water in the
Prestea - Bogoso area are in the range of 0.14 - 0.76 and 0.12 -
0.27ug/L respectively . In the Obuasi area drinking water (tap and
borehole waters) range from 1.23 - 2.15ppb. The WHO (1976) limit for
drinking is 1ppb.
46

47. CONCLUSION
Mercury and its compounds are toxic and should be handled
with care.
Mercury is treated by most international bodies as a hazard and
toxic compound.
The organomercury compounds and Mercury crosses the blood-
brain barrier to cause nervous breakdown, tremors and suicidal
tendency.
It use for some medicinal, electrical and cosmetic purpose have
been banned in some countries around in the world.
Mercury poison can be treated with Chelating therapy.
Soil and sediments can be decontaminated by phytoremediation.
47

48. CONCLUSION
 In Ghana, mercury is imported for use mainly in the mining
sector. Small quantities go to the health and education sectors.
There is no information on the transportation.
 Due to lack of awareness the chemical gets into the
environment during the mining process and uncontrolled
disposal/combustion of mercury-containing waste.
 The various compartments of the environment (water, soil and
vegetation) are significantly contaminated with the chemical.
 There are no national threshold values of mercury for imported
goods, water, food etc.
 The pieces of legislation on mercury are inadequate and
obscure. People are not aware of these laws;
 Regulatory bodies have the capability but lack the capacity
and resources for the task.
48

49. REFERENCE
 UNEP Chemicals – Mercury
 Colin Baird and Michael Cann. Environmental Chemistry, Fourth edition. 2000.
 http://en.wikipedia.org/wiki/Dimethylmercury
 http://en.wikipedia.org/wiki/mercury
 Senese, F. "Why is mercury a liquid at STP?". General Chemistry Online at Frostburg State
University. http://antoine.frostburg.edu/chem/senese/101/inorganic/faq/why-is-mercury-
liquid.shtml. Retrieved May 1, 2007.
 Eisler, R. (2006). Mercury hazards to living organisms. CRC Press. ISBN 9780849392122.
http://books.google.com/?id=gqc8wUvsI8cC&pg.
 "Mercury amalgamation". http://corrosion-doctors.org/Elements-Toxic/Mercury-
amalgamation.htm. Retrieved 2009-07-07.
 "Mercury: Spills, Disposal and Site Cleanup". Environmental Protection Agency.
http://www.epa.gov/mercury/spills/index.htm. Retrieved 2007-08-11.
 "Glacial Ice Cores Reveal A Record of Natural and Anthropogenic Atmospheric Mercury
Deposition for the Last 270 Years". United States Geological Survey (USGS).
http://toxics.usgs.gov/pubs/FS-051-02/. Retrieved May 1, 2007.
 Environmental Health Criteria 1: Mercury. Geneva: World Health Organization. 1976.
ISBN 9241540613. http://www.inchem.org/documents/ehc/ehc/ehc001.htm.
 V. K Nartey et al. Artisanal Mining of Gold with Mercury in Ghana . West Africa Journal of Applied
Ecology (WAJAE) –ISSN: 0855-4307 Volume 9 (Jan – Jun 2006)
 http://www.unep.org/hazardoussubstances/LinkClick.aspx?fileticket=jfzqIOojIz8%3d&tabid=
4325&language=en-US
49

50. THANK YOU
50