Q 2: chemical movement in the enviro Flashcards
How Do Chemicals Get Around ?
In the Environment – between different environmental compartments (oil tankers)
In Organisms – how do they get in ? (pestisides)
how are humans intervening
Moving substances from inaccessible to accessible compartments
Metal ores
Crude oil (not so bad when its in the ground but when we rtake it out, we concentrate it)
Concentrating previously diffuse sources
Metal refining
Changing Chemical Forms
Converting metal salts into elemental metals
AND THEN DUMPING IT ALL
how are non-human processes intervening
Many chemicals have been cycling in the environment since there was an earth
Carbon dioxide – plants – animals – carbon dioxide
Carbon, nitrogen, oxygen, sulphur, iron, etc. all have their natural cycles
So why would a human chemical put in one place stay in one place ?
what matters
Is it inorganic – metals – mercury, lead, copper
Is it ‘organic’ – made up of C, H, O, S, N, …
Does the chemical have a charge (+ or -) ? Is it ionized
Most inorganic chemicals that are uncharged are unavailable
There are a few exceptions
Most metal ions have a +ve charge
Organic molecules can also be charged (carboxylic acids, amines)
Organic molecules can be large and
have separate charged and uncharged
regions
what elements are in organic metals
C, H, O, S, N,
are metals positive or negative charges
mostly positive
amines
positively charged
carboxylic acid
- charge
what are some physico chemical properties
structure, water solubility, thermal conductivity, density, vapor pressure
what are some water solubility of chemicals
ethanol is infinite, DDT : 0.0017- will stay in same place for very long time becasue not soluble
vapor pressure
EVAPORATION CAUSES AN INCREASE IN VAPOR PRESSURE UNTIL EQUILIBRIUM IS REACHED, things that evaporate rapidly will have a higher vapor pressure
ethanol splil dont have to wipe up because it will evaporate quickly
what was found in the antarctic
DDT- A lot got their from the air and snow`
low altitude
more evaporation
mild latitude
equal deposition and evaporation
high altitudes
more deposition
Long Range Atmospheric Transport
Compounds need some volatility
Generally molecules that are not charged – i.e. non-polar (things that are charged are usually sticking to something)
Compound needs to be persistent in the atmosphere (uv light destroys them)
Polar compounds such as PFOS may travel as non-polar volatile precursors and degrade at distant locations
rubber duckies
15 years to travel over the artic down to florida
what is theGreat Pacific Garbage Patch
Ocean currents have resulted in the accumulation of ‘large’ amount of plastic wastes in the open ocean
Physical threat to wildlife
Potential to increase chemical exposures from adhered chemicals
how can chemicals move around
Even insoluble things can move in air and water if they are stuck to something like dust or sediment – which are moved around by these media
Many chemicals bind tightly to soil and sediment that can be moved by air and water
sedimentation
fanning out results in decreases water velocity so suspended particles are no longer supporter
occurs in freshwater and marine systems
can get some sorting of material depending on density
estarine systems are very important for the sorting of poplutants
enrichment of organic matter results in deposition of many contaminants- metal and organic
estuarine systems are critival marine habitats for the breeding of many aquatic species
uptake by organisms depend on
Depends on the chemicals properties
Depends on the organisms properties
Soil binds chemicals relatively tightly and may make them unavailable
Air, water and food are major routes of exposure
Bioconcentration
Gills work just as well for accumulating anything else dissolved in the water
Works well for dissolved metals – metals bound to organic matter no so well
Once in the body chemicals can dissolve in fat (organic chemical) or can bind to other components of the body such as protein
Chemicals dissolved in the blood can also be eliminated via the gills
Bioconcentration = the accumulation and sequestration of contaminant materials by living organisms directly from the ambient environment.
Bioconcentration-factor (BCF)
Bioconcentration-factor (BCF) indicates the degree to which a chemical may accumulate in organisms, coincident with concentrations of chemical in water.
OCTANOL/WATER PARTITION COEFFICIENT (Kow)
OCTANOL/WATER PARTITION COEFFICIENT (Kow)
Ratio of a chemical’s concentration in octanol phase to its concentration in the aqueous phase of a two-phase octanol/water system
octanol phase/ aqueous phase
