This document discusses environmental chemistry of mercury. It begins with an introduction to mercury in the environment, its various forms, and how it biomagnifies through aquatic food chains. It then discusses how atmospheric chemists are interested in mercury due to its unique liquid and gaseous properties. Next, it summarizes the Minamata disease discovered in Japan caused by methylmercury pollution and the United Nations Minamata Convention on Mercury. Finally, it lists some common uses of mercury in products like thermometers and discusses the risks of climate change mobilizing mercury stored in soils.

1. Environment Chemistry Of Mercury
Presented
By
Name Waqar Ahmad Khan
Mphil Chemistry Student
Sarhad University Of Science and Information technology,Peshawar,

2. Outlines
 Introduction Of Environmental Chemistry Of Mercury
 Mercury from fish consumption
 atmospheric chemists interested in mercury
 UNEF MINIMATA CONVENTION OF MERCURY
 IRAQ GRAIN DISASTER
 USES OF MERCURY

3. Introduction Of Mercury
Mercury (Hg) exists in nature largely as elemental Hg0 (a liquid or
monatomic vapor) or its oxidized form, mercuric ion (Hg2+), with the
two forms undergoing interconversion through biotic and abiotic redox
processes.
Although trace amounts of mercurous ion, Hg+, may be present in the
environment.

4. Introduction Of Mercury Continued
Methylmercury is transported across the blood-brain
barrier and hence is neurotoxic. As methylmercury
biomagnifies along the aquatic food chain,
consumption of predatory fish and other seafood is
the major exposure pathway in humans.1

5. The Mercury Cycle

6. Why atmospheric chemists
inter interested in mercury?
Mass number = 80: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2
• Filling of subshells makes elemental Hg(0) liquid, volatile
• Mercury can also shed its two outer electrons (6s2)
and be present as Hg2+ , also called Hg(II)
6s2

7. Mercury is present in the atmosphere as an elemental gas
Xe
KrNe
Ar
He
Hg Rn
…a property that it shares only with the noble gases!
But unlike noble gases, mercury has a biogeochemical cycle driven by:
Hg(0) Hg(II)
oxidation
reductionelemental
mercury
mercuric
compounds

8. Minamata Disease Discovered
 Minamata disease was first discovered in Minamata city in Kumamoto prefecture,
Japan, in 1956. It was caused by the release of methylmercury in the industrial
wastewater from the Chisso Corporation's chemical factory, which continued from
1932 to 1968.
 This highly toxic chemical bio accumulated and biomagnified in shellfish and fish in
Minamata Bay and the Shiranui Sea, which, when eaten by the local population,
resulted in mercury poisoning. While cat, dog, pig, and human deaths continued for
36 years, the government and company did little to prevent the epidemic. The
animal effects were severe enough in cats that they came to be named as having
"dancing cat fever"

9. United nation emergency force UNEF Minimata Convention on Mercury
First major global environmental treaty in over a decade
• Requires best available control technology
for coal-fired power plants
• Mercury mining to be banned in 15 years
• Many mercury-containing commercial
products to be banned
Opened for signatures in October 2013; already signed by 128 countries
Convention requires ratification by 50 countries to go into effect;
nine (including the US) have ratified so far

10. 1971 Iraq poison grain dis
aster
 Grain treated with a methylmercury fungicide and
never intended for human consumption was imported
into Iraq as seed grain from Mexico and the United
States.
 6,530 patients were admitted to hospitals with
poisoning, and 459 deaths reported.
 with perhaps 100,000 cases of brain damage.

11. Global source contributions to Hg in present-day surface ocean
Amos et al. [2013]
Europe Asia
N America
S America
former
USSR
Rest of world
pre-1850natural
by time of initial emission:
by source continent:
Half of human-derived mercury
presently in the ocean
was emitted before 1950

12. Uses Of Mercury
 It is used in thermometers because it has a large thermal expansion which is constant
over a large temperature range although it is being phased out in favour of safer
liquids.
 It is also used in barometers an manometers due to its high density. From
this it has also become a way of measuring pressure in millimetres of
mercury.
 It has also been used as liquid electrolyte for the production of chlorine and
sodium hydroxide from the electrolysis of brine but is again being phased
out in favour of safer alternatives.
 It is still sometimes used in electrical switches as a liquid contact.
Thermometer Barometer

13. Uses Of Mercury
 Mercury also used to be used as a component for dental amalgams
for making fillings for teeth. This process has again been phase out
due to health concerns but many people still have mercury
containing fillings and crematoria are thought to emit about 5kg of
mercury each year simply from dental fillings. The amalgam of
70% silver and 30% tin when mixed with mercury formed a pliable
material that could be inserted into the tooth and the amalgam
expanded as it dried to fill the entire cavity. However this amalgam
has been replaced by a similar one made from 60% silver, 27% tin
and 13% copper.
Dental Filling
Mercury

14. Many commercial products contain mercury
Wiring Devices &
Industrial Measuring Devices
Medical Devices
Pharmaceuticals & Personal Care Products

15. Pesticides and Fertilizer Explosives/Weapons
Dyes/Vermilion
Many commercial products contain mercury

16. Tracking the environmental fate of commercial mercury
Global mercury mined
per decade
Commercial use by country
Disposal
Air Land Water
Landfill
Horowitz et al., 2014

17. The wild card of climate change:
potential mobilization of the large soil mercury pool
Global soils: 270,000 tons mercury Oceans: 330,000 tons
Atmosphere: 5,000 tons
Increasing soil respiration
due to warmer temperature
Climate change may be as important as emission controls
for the future of environmental mercury in the century ahead.