Global Transport of Contaminants

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Global Transport of Contaminants to the
Poles GEOS 489/689 October 30, 2007 José L.
Sericano, Ph.D. (jsericano_at_gerg.tamu.edu) Geochemi
cal Environmental Research Group 833 Graham
Rd., College Station, TX 77845
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Persistente Organic Pollutants (POPs) Stockholm
Convention (2001) The Stockholm Convention is a
global treaty to protect human health and the
environment from persistent organic pollutants
(POPs).  POPs are chemicals that remain intact in
the environment for long periods, become widely
distributed geographically, accumulate in the
fatty tissue of living organisms and are toxic to
humans and wildlife.  POPs circulate globally and
can cause damage wherever they travel.  In
implementing the Convention, Governments will
take measures to eliminate or reduce the release
of POPs into the environment.
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The 12 POPs under the Stockholm Convention

• Aldrin A pesticide applied to soils to kill
  termites, grasshoppers, corn rootworm, and other
  insect pests.
• Chlordane Used extensively to control termites
  and as a broad-spectrum insecticide on a range of
  agricultural crops.
• DDT Perhaps the best known of the POPs, DDT was
  widely used during World War II to protect
  soldiers and civilians from malaria, typhus, and
  other diseases spread by insects. It continues to
  be applied against mosquitoes in several
  countries to control malaria.
• Dieldrin Used principally to control termites
  and textile pests, dieldrin has also been used to
  control insect-borne diseases and insects living
  in agricultural soils.
• Endrin This insecticide is sprayed on the
  leaves of crops such as cotton and grains. It is
  also used to control mice, voles and other
  rodents.

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The 12 POPs under the Stockholm Convention

• Heptachlor Primarily employed to kill soil
  insects and termites, heptachlor has also been
  used more widely to kill cotton insects,
  grasshoppers, other crop pests, and
  malaria-carrying mosquitoes.
• Hexachlorobenzene (HCB) HCB kills fungi that
  affect food crops. It is also released as a
  byproduct during the manufacture of certain
  chemicals and as a result of the processes that
  give rise to dioxins and furans.
• Mirex This insecticide is applied mainly to
  combat fire ants and other types of ants and
  termites. It has also been used as a fire
  retardant in plastics, rubber, and electrical
  goods.
• Toxaphene This insecticide, also called
  camphechlor, is applied to cotton, cereal grains,
  fruits, nuts, and vegetables. It has also been
  used to control ticks and mites in livestock.

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The 12 POPs under the Stockholm Convention
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The 12 POPs under the Stockholm Convention

• Polychlorinated Biphenyls (PCBs) These
  compounds are employed in industry as heat
  exchange fluids, in electric transformers and
  capacitors, and as additives in paint, carbonless
  copy paper, sealants and plastics.
• Dioxins These chemicals are produced
  unintentionally due to incomplete combustion, as
  well as during the manufacture of certain
  pesticides and other chemicals. In addition,
  certain kinds of metal recycling and pulp and
  paper bleaching can release dioxins. Dioxins have
  also been found in automobile exhaust, tobacco
  smoke and wood and coal smoke.
• Furans These compounds are produced
  unintentionally from the same processes that
  release dioxins, and they are also found in
  commercial mixtures of PCBs.

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The 12 POPs under the Stockholm Convention
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The 12 POPs under the Stockholm Convention
DDT is still used in many tropical areas where
Malaria is a problem
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Other POPs of Increasing Concern
Insecticides Aldicarb Carbaryl Carbofuran Chlorpy
rifos Diazinon Endosulfan Lindane Malathion Parath
ion Permetrin
Herbicides Ametrin Alachlor Atrazine Gliphosate S
imazine 2,4-D Trifluralin Paraquat
Plus Pentachlorofenol Flame retardants Polynucl
ear aromatic hydrocarbons
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Pesticide movement in the hydrologic cycle
including pesticide movement to and from sediment
and aquatic biota within the stream. Modified
from Majewski and Capel (1995). Majewski, M.S.,
and Capel, P.D., 1995, Pesticides in the
atmosphere-distribu- tion, trends, and governing
factors, Ann Arbor Press, Inc., Chelsea, Mich.,
228 p.
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Fate of POPs in the Environment
diffusion
Troposphere
Atmosphere
evaporation
adsorption
Gaseous Phase
Dissolved Fraction
degradation
dissolution
desorption
degradation
degradation
precipitation
diffusion
Soil
evaporation
evaporation
diffusion
deposition
Water
Gaseous Phase
adsorption
Dissolved Fraction
degradation
desorption
evaporation
dissolution
dispersion
degradation
degradation
Dissolved Fraction
degradation
diffusion
diffusion
resuspension
sedimentation
percolation
Sediment
desorption
adsorption
adsorption
Dissolved Fraction
desorption
degradation
degradation
degradation
accumulation
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Dissipation Processes

• Physicochemical Degradation
• This includes hydrolysis and photodegradation of
  POPS in water, soil, and air and the
  identification, formation, and persistence of
  breakdown products.
• Biological Degradation
• This includes aerobic and anaerobic soil and
  aquatic metabolisms and determines the
  persistence of POPs when they interact with soil
  microorganisms living under aerobic and anaerobic
  conditions, including breakdown products that
  result from biological degradation.
• Mobility
• This includes processes such as leaching,
  adsorption/desorption, laboratory volatility, and
  field volatility that assess the mobility of POPs
  and their breakdown products through soils of
  different types.

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Dissipation Processes

• Bioconcentration
• It estimates the potential of POPs, under
  controlled laboratory conditions, to partition to
  aquatic organisms from respiratory and dermal
  exposures. These studies also provide information
  on the degree to which bioconcentration of POPs
  and their degradation products can be reversed
  (depuration) should levels in the surrounding
  aquatic environment be reduced.
• Field Dissipation
• Field dissipation addresses POP loss as a
  combined result of chemical and biological
  processes (e.g., hydrolysis, photolysis,
  microbial transformation) and physical migration
  (e.g., volatilization, leaching, plant uptake).

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Dissipation Processes

• Physicochemical Degradation
• This includes hydrolysis and photodegradation of
  POPS in water, soil, and air and the
  identification, formation, and persistence of
  breakdown products.

Ref. Korpraditskul et al., J. Pest. Sci.,
17287-289, 1992
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Dissipation Processes

• Physicochemical Degradation
• This includes hydrolysis and photodegradation of
  POPS in water, soil, and air and the
  identification, formation, and persistence of
  breakdown products.

Ref. Racke Coats, American Chemical Society
Nro 426, 1990
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Dissipation Processes

• Field Dissipation
• Field dissipation addresses POP loss as a
  combined result of chemical and biological
  processes (e.g., hydrolysis, photolysis,
  microbial transformation) and physical migration
  (e.g., volatilization, leaching, plant uptake).

DDT Half Life in Tropical Climates
Ref. Wandiga, S.O., Pure Appl. Chem., Vol 73,
1147-1155, 2001
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Pesticide Half Lives in Temperate Soils
Ref. Wandiga, S.O., Pure Appl. Chem., Vol 73,
1147-1155, 2001
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A Global Distribution Model for POPs
Ref. Wania Mackay, Sci of Total Environ.,
160/161, 211-232, 1995
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Latitudinal Distribution of POPs
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A Global Distribution Model for POPs
Ref. Wania Mackay, Sci of Total Environ.,
160/161, 211-232, 1995
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Latitudinal Distribution of POPs (PCBs)
Ref. Wania F., WECC Report 1/99, 1999
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PCB Mobility in the Global Environment
Ref. Wania F., WECC Report 1/99, 1999
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PCB Mobility in the Global Environment
Ref. Wania F., WECC Report 1/99, 1999
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PCB Mobility in the Global Environment
Ref. Wania F., WECC Report 1/99, 1999
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Global Distillation The Migration Process of POPs
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Global Distillation The Migration Process of POPs
In a process resembling a distillation, organic
compounds become latitudinally fractionated
according to their volatility as they condense at
different ambient temperatures.
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Global Distillation The Migration Process of POPs
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The Significance of Long Range Transport of POPs
by Migratory Organisms

• How much chemical is transported to a particular
  system by migrating organisms?
• How much chemical is delivered to a particular
  system by migrating organisms?
• How much chemical is delivered to a particular
  organism/population by migrating organisms?

Ref. Wania F., WECC Report 3/98, 1998
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How Much Chemical is Transported to a Particular
System by Migrating Organisms?
Air NA GA . CA Water NW GW . CW Migrating
organisms NM GM . CM
Ref. Wania F., WECC Report 3/98, 1988
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How Much Chemical is Delivered to a Particular
System by Migrating Organisms?
N1 - N2 (G1 . Cout)- (G2 . Cin) For long-term
air and water exchange, G1 G2 then Net Exchange
Cint Cout Comparatively, for long-term
migrating organisms G1 ? G2
Ref. Wania F., WECC Report 3/98, 1988
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How Much Chemical is Delivered to a Particular
System by Migrating Organisms?
Advection Intermedia exchange Permanent loss
Ref. Wania F., WECC Report 3/98, 1988
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How Much Chemical is Delivered to a Particular
Organism/Population by Migrating Organisms?
It is immediately obvious that this question can
not be answered in a general valid fashion
because the significance of long-range transport
by migrating animals will be entirely dependent
on the dietary habits of a particular wildlife
population or a human individual.
Ref. Wania F., WECC Report 3/98, 1988
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Estimating Gross Transport Rates of Selected POPs
into Arctic
How much chemical is transported annually across
60o Northern latitude into the Arctic by 1-
atmospheric currents, 2- sea water currents,
and 3- migrating organisms? Following is a very
rough estimation of the gross transport rates
of 1- hexachlorocyclohexanes (HCHs), 2- DDT and
related substances (DDTs), and 3- polychlorinated
biphenyls (PCBs)
Ref. Wania F., WECC Report 3/98, 1988
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Transport of POPs with Atmospheric Currents
The flux of air en and out of the Artic
atmosphere GA in m3/h can be estimated as GA
VA / tA where VA, total volume of Arctic
atmosphere North of 60o tA, average residence
time of air in the Arctic atmosphere north of
60o VA 2 . p . r2 . (sin 90o sin 60o) . hA r
is the global radius 6370289.6 m hA is the
average height of Arctic Atmosphere (6000
m) Assuming a residence time tA of 5 days, the
average transport rate for air GA is 1.71 . 1015
m3/h
Ref. Wania F., WECC Report 3/98, 1988
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Transport of POPs with Atmospheric Currents
These data indicate that the gross fluxes into
the Arctic atmosphere are on the order of tons to
thousand of tons per year
Ref. Wania F., WECC Report 3/98, 1988
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Transport of POPs with Ocean Currents
The amount of sea water flowing annually into the
Arctic Ocean has been estimated (Barrie et al.,
1997) as GW 14.88 . 104 km3/y 1.488 . 1014
m3/y 1.7 . 1010 m3/h
Ref. Barrie et al., Canadian Arctic Contaminants
Assessment Report, 1997
Ref. Wania F., WECC Report 3/98, 1988
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Transport of POPs with Migratory Animals
The potential transport of POPs with migratory
animals into the Arctic is exemplified with two
types of organisms, seabirds and whales Example
1 Seabirds
The amount of POPs transferred in and out of the
Arctic with these birds is thus in the range of
grams to kilograms per year
Ref. Wania F., WECC Report 3/98, 1988
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Transport of POPs with Migratory Animals
Example 2 Whales
The amount of POPs transferred in and out of the
Arctic with these whales is of a few tons per year
Ref. Wania F., WECC Report 3/98, 1988
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Comparison of Gross Fluxes
This suggests that the amount of some POPs
transported in migratory organisms, particularly
whales, may be on a similar order of magnitude as
the gross transport rates estimated for the
physical transport via atmosphere and ocean
currents
Ref. Wania F., WECC Report 3/98, 1988
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Net Transport of POPs by Migratory Organisms

• The estimation of the quantity of POPs that is
  net-transported with migratory animals from one
  location to another is very complex.
• The net transport of POPs with migrating
  organisms across a boundary will depend on where
  the organisms take up and release their
  contaminants.
• Examples
• Distinct feeding areas
• Distinct areas of fecal excretion
• Distinct areas of death

Ref. Wania F., WECC Report 3/98, 1988
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Distribution of selected POPs in Arctic air,
snow, sewater, and the marine mammals food chain
plotted for each compartment or species as the
percent of POPs in that media to demonstrate the
importance of physical and chemical
characteristics in the movement and fate of POPs
in polar environments.
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Summary and Conclusions

• Global distillation and atmospheric transport are
  the main processes for POPs to move from low
  (i.e., application) to high latitudes (i.e.,
  sink). The general gross transport rate of POPs
  in air is similar to that of whales and
  significantly higher than those in water and
  birds.
• As air masses, migrating organisms, such as birds
  and whales, do transport POPs over long distances
  and across international boundaries.
• On a local scale, biotic focusing of POPs can
  even become more significant than contaminant
  inputs via abiotic pathways, i.e. air and water.
  The direction of POP transport is from the
  feeding areas to the areas of excretion, spawning
  and death/decay/consumption

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Summary and Conclusions

• The relative significance of the biotic transport
  of a chemical increases with decreasing
  volatility (air) and solubility (water) and
  increasing bioaccumulation potential.
• The availability of biological transported POPs
  to other organisms, including humans, tends to be
  higher than for POPs transported in abiotic media.