2. Logam berat
•
•
•
•
Yang termasuk dalam logam
berat antara lain:
Hg, Pb, Cd, Cr, As, Cu, Cr, Ni,
Co, Mg
Tersebar merata
Toksisitas tinggi
Nondegradable
Densitasnya lebih tinggi jika
dibandingkan dengan logam lain
Tabel: apakah semua logam berat bersifat
toksik?
4. Apa itu Logam Berat?
Yang termasuk dalam Logam Berat.
5. • Heavy metals are chemical elements that have a specific
gravity (a measure of density) at least five times that of
water.
• generally interpreted to include those metals from periodic
table groups IIA through VIA
• Heavy metals are natural constituents of the Earth's crust
and are present in varying concentrations in all ecosystems
• Metals differ from other toxic substances in that they are
neither created nor destroyed by humans. Therefore, they
tend to accumulate in the soils, seawater, freshwater, and
sediments.
6. Introduction
Although we commonly think of heavy metals as water
pollutants, they are for the most part transported from place
to place via the air, either as gases or as species absorbed
on, or absorbed in, suspended particulate matter. (Baird,
2011)
7. • Metals are probably the oldest toxins known to
humans. Lead usage may have begun prior to 2000
BC in the smelting of silver. Arsenic was obtained
during the melting of copper and tin, and an early
use was for decoration in Egyptian tombs/
8. Mercury illuminated by incandescent
and UV light
Speciation and Toxicity
•
•
Unsur bebas bersifat tidak toksis (kecuali uap Hg)
Bersifat toksis sebagai kation
Putnam, 1972
11. • Mercury is a contaminant of our water ways.
Humans are exposed to mercury in the fish they
eat as well as in the amalgam fillings in their
teeth.
• Arsenic is found naturally in high concentration
in drinking water in various parts of the world.
Cadmium has been classified as a known human
carcinogen.
12. CHEMICAL AND PHYSICAL
PROPERTIES
CHEMICAL AND PHYSICAL PROPERTIES
• 1. Physical states - solids, liquids, gases
aerosols
• 2. Elements - indestructible
• 3. Electrophyllic cations - react with ligands
reversible complexes molecular mimicry
• 4. Oxidation States affects toxicity
• 5. Organometallic compounds differ from
inorganic
• 6. Essential versus non-essential
13. • Heavy metals (HM) exert their toxic effects by
combining with one or more reactive groups
(ligands) essential for normal physiological
functions.
• Heavy metal antagonists (HMA) - chelating
agents are designed specifically to compete with
these groups for the metals, and thereby
prevent or reverse toxic effects and enhance
excretion of metals.
14. Sources of heavy metal pollution
ATMOSPHERIC
Metals can be transferred by the atmosphere in gas or particle
form (aerosol)
• Particles can fall from the atmosphere onto the land or sea = dry
deposition
• Also precipitation can carry particles or dissolved gases = wet
deposition
• Gaseous state elements (Boron, Mercury, Selenium) can also dissolve at the
surface of water bodies (gaseous exchange)
• Bubbles breaking the surface of the sea can release salt particles
containing metals
– can travels from sea to atmosphere as well as atmosphere to sea
15. Sources of heavy metal pollution
RIVERS
• Erosion of rocks containing metals
• Surface runoff sweeps up naturally formed and
anthropogenic metal particles
Metals often bind with sediments and are deposited
on the seabed
– but these can enter the marine environment again is
there is:
– Dredging
– Trawling
– Severe weather
16. Sources of heavy metal pollution
GROUNDWATER SEEPAGE
• Dissolved substances are carried via ground
water movement – contamination in soil may
be picked up by the moving waters
DELIBERATE DISCHARGE
• Contaminated waste dumping
• Industrial discharges
• Sewage
