- toxicity depends on pH - decreased solubility as pH increases -> less toxic - free ionic form usually most toxic (except aluminum) Toxicity is pH dependent!

Inorganic pollutants Flashcards by Jin K

What are inorganic pollutants?

metals, metalloids
nitrates, nitrites
minerals?
radioactive substances

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Naturally occuring inorganic pollutants?

some are essential for life:
Co, Cu, Fe etc.
some are always toxic (non-essential)
Pb, Cd, Hg

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Can inorganic pollutants be destroyed?

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What about their background concentrations?

Something occurs and we cant do anything about it, but we need to know how much

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Adaptation to inorganic pollutants?

Some species can adapt to high concentrations while some die.

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List some Potential toxic elements (PTE)!

Arsenic
Chromium
Cobalt
Copper
Lead
Mercury
Zinc

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What are potential toxic elements?

Elements that exhibit metallic properties.

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PTE:s are sometimes referred to ‘heavy metals’, what does it mean?

relatively high density (above 5g/cm^3)
relatively high atomic weight
toxic at low concentrations
cant be destroyed
widely distributed

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What are metals properties?

accumulates in organisms
cant be broken down by liver
persistent in environment

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pH effect on metals?

toxicity depends on pH
decreased solubility as pH increases -> less toxic
free ionic form usually most toxic (except aluminum)

Toxicity is pH dependent!

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Something about mercury (Hg)?

most volatile of all metals
highly toxic in vapor form
liquid in ordinary temperatures
liquid mercury itself is not highly toxic
rarely occurs naturally

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Anthropogenic (human made) presence of mercury?

fossil fuel burning
waste incineration
mining
smelting

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Some sources of mercury?

emissions of mercury vapor from large industrial operations
unregulated burning of coal and fuel oil
emissions from batteries, thermometers
gold and silver extraction from mines

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Environmental effects of mercury?

Mercury is normally a problem only where the rate of natural formation of METHYLMERCURY from inorganic mercury is greater than the reverse action.

Methylmercury is the only form which accumulates

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Which waters can contain a lot of mercury?

Acidic surface waters can contain significant amounts of mercury.
Low soil pH increases the mobility in soil -> water ecosystems in danger

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Other environmental effects of mercury (bio) ?

Bioaccumulation:
- increase in concentration of a pollutant from the environment to the first organism in a food chain
Biomagnification:
- increase in concentration of a pollutant from one link in a food chain to another.

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Health effects of mercury (ways)?

Toxicity in all forms:
MeHg > vapor > Hg2+ > liquid

Liquid is readily excreted
Hg2+ affects liver and kidneys
Vapor Hg diffuses from lungs to bloodstream to brains
Methylmercury:
lipophilic (soluble in fatty tissues)
Converted to Hg2+ in brain (neurotoxin)

Health effects of mercury?

skin burns
irritation of nose and skin
rashes
damage to kidneys
damage to vision
loss of hearing and muscle coordination
severe brain damage
CNS dysfunction

Something about lead (Pb)?

melting point of 327 C
commonly used in the building industry for roofing, flashing and soundproofing
when combined with tin, it forms a solder, used in electronics and other applications to make connections between metals
used in batteries, paints and ceramics
in foods, soft drinks and wine
application with gasoline
industrial processes

Chemistry of lead?

Exists in Pb2+ form (PbS is highly insoluble)

PbO (batteries), PbCO3, PbS, PbCl

The solubility of lead compounds in water is a function of?

pH
hardness
salinity

Solubility is highest in soft, acidic water

Significant fraction of lead carried by in undissolved form

Lead, chimistry + soil?

The sink for lead is the soil and sediment

strongly absorbed to soil
generally retained in the upper layers of soil
does not leach appreciably into the subsoil and groundwater

Environmental effects of lead?

bioaccumulates in the bodies of water- and soil organisms
health effects can take place in low concentrations
soil organisms are suffered from lead poisoning
plants and animals may bioconcentrate lead

Health effects related to lead?

lead can enter fetus through the placenta of a mother
transferred from breast milk -> serious damage to nervous system and brain of unborn child
lowered IQ in children
behavioral disruptions in childen

More health effects related to lead?

- rise in blood pressure - kidney damage - miscarriages - nervous system and brain damages - death, with high levels

Something about cadmium?

- most toxic in its ionic form (unlike mercury, vapor)

Greatest source of cadmium? Greatest application?

- from our food supply-seafood, organ meats, potatoes, rice and other grains - greatest application in batteries

Environmental effects of cadmium?

Longe range transportation when absorbed by sludge - it pollutes surface waters as well as soils Strongly adsorbs to organic materials in soils

Why cadmium can be extreme dangerous in soils?

- its uptake through food will increase | - low pH enhance cadmium uptake by plants -> accumulated in plants

Health effects of cadmium?

- kidney- and lung toxicity - skeletal effects - osteoporosis and osteomalacia - cancer

Something about chromium?

- steel-gray solid, high melting point - occurs in the environment in two valance states: - trivalent chromium (III) - hexavalent chromium (IV) more toxic!

Difference between chromium III and IV?

III: - in an organic form is an essential micronutrient for life - shortages cause cause health problems, uptake a bit too IV: - powerful epithelial irritant - carcinogenic - toxic to many plants, aquatic animals and bacteria

Sources if chromium?

``` - naturally occurs in rocks, plants, animals, soil, and volcano dust and gases Natural sources of Cr: - weathering of rock constituents - wet precipitation - dry fallout from atmosphere ```

Environmental effects of chromium (pathways)?

- the atmosphere is a major pathway for long-range transfer - most of the chromium in the air will settle and end up in waters or soil - in water, chromium will absorb on sediment and become immobile - in soils chromium strongly attaches to soil particles and as a result it will NOT move towards groundwater

Environmental effects of chromium III and IV?

- Cr (III) is generally not transported over great distances because of its low solubility and tendency to be adsorbed by soil particles - Cr (IV) most mobile in water and soil - Conversion from III to IV increases Cr dislocation from soil to water systems

Health effects of chromium?

- chromium (IV) is a danger to human health mainly for people who work in the steel and textile industry - smokers have a higher chance of exposure to chromium - all other stuff

Something about arsenic?

- widespread in the environment, human activity has mobilized it - found naturally in the Earth's crust - odor- and colorless - organic or inorganic compounds - NOT easily water soluble

Sources of arsenic?

``` Atmosphere: - volcanoes, burning of fossil fuels - commercial or industrial processes Smelting of metals Pharmaceutical industry etc. ```

Environmental effects arsenic?

- runoff through surface- and groundwater - accumulates in plants if soil conditions are right - bioaccumulates in aquatic ecosystems

Health effects on arsenic?