Environmental Geosciences

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Environmental Geosciences

• Human Interactions with the Environment

Organics
Andrea Koschinsky
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Characteristics of Organic Compounds
Vapour pressure of organics Given a mixture
(ideal) of organics the partial pressure of
component i is given by Raoults law Pi xi
Pi,o where P0 is the vapor pressure of the pure
substance. Solubility of organics in water The
aqueous solubility will obey Henrys law Pi ki
Ciw where Ciw is the concentration in water and
ki is the Henrys Law constant.
Estimating values for Koc The partitioning of
organics between solid organic matter and water
is given by Koc. The values for Koc can be
predicted from the measured octanol-water
partitioning for insoluble organics Kow
organic in octanol/organic in water log Koc
0.49 0.72 log Kow Sorption of organics onto
soil organic matter The partitioning between soil
and groundwater is found by scaling Koc by the
fraction of organic matter (f 0.0001-0.02.) Dist
ribution coefficient Kd Kocfoc
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Organic Compounds
Aliphatic compounds
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Organic Compounds
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Organic Compounds
Aromatic compounds
BTEX is an acronym for benzene, toluene,
ethylbenzene, and xylene . This group
of volatile organic compounds (VOCs) is found in
petroleum hydrocarbons, such as gasoline, and
other common environmental contaminants.
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Organic Compounds
Volatile organic compounds (VOCs) are compounds
that have a high vapor pressure and low water
solubility. Many VOCs are human-made chemicals
that are used and produced in the manufacture of
paints, pharmaceuticals, and refrigerants. VOCs
typically are industrial solvents, such as
trichloroethylene fuel oxygenates, such as
methyl tertiary-butyl ether (MTBE) or
by-products produced by chlorination in water
treatment, such as chloroform. VOCs are often
components of petroleum fuels, hydraulic fluids,
paint thinners, and dry cleaning agents. VOCs are
common ground-water contaminants.
Persistant bioaccumulative toxic chemicals (PBTs)
are chemicals that are toxic, persist in the
environment and bioaccumulate in food chains and,
thus, pose risks to human health and ecosystems.
The biggest concerns about PBTs are that they
transfer rather easily among air, water, and
land, and span boundaries of programs,
geography, and generations.
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Organic Compounds
Polynuclear aromatic hydrocarbons (PAHs) are
hydrocarbon compounds with multiple benzene
rings. PAHs are typical components of asphalts,
fuels, oils, and greases. They are also called
Polycyclic Aromatic Hydrocarbons.
Larger systems of benzene ring structure fused
together is called PAH Chemistry of the
structures is the same but usually more reactive
then benzene
Benzene
Anthracene
Naphthalene
Phenanthrene
Perylene
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Organic Compounds

• Sources of PAHs
• PAHs mainly arise from combustion-related or
  oil-related man-made sources.
• burning of coal, oil, gas, wood, tobacco,
  rubbish, and other organic substances.
• also present in coal tars, crude oil, and
  petroleum products such as asphalt.
• ubiquitous environmental contaminants
• natural sources forest fires and volcanoes,
  biological sources of PAHs

• Effects of PAH
• Short-term irritation, nausea,
• Long term Carcinogenic
• Reproductive failures
• Kidney, liver damage, jaundice
• Bioaccumulates rapidly in aquatic life

• PAH burden in temperate environments is mostly
  pyrogenic
• Essential to understand and predict the global
  dynamics and trends of these compounds

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Organic Compounds
Persistent Organic Pollutants (POPs) are chemical
substances that persist in the environment,
bioaccumulate through the food web, and pose a
risk of causing adverse effects to human
population and the environment. There has been a
realization that these pollutants, upon exposure
of human population, can cause serious health
effects ranging from increased incidence of
cancers to disruption of hormonal system. These
effects have also been observed and recorded for
various animal species. Developing countries are
particularly vulnerable due to often
indiscriminate use and disposal of POPs.
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Organic Compounds
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Organic Compounds

• Polychlorinated biphenyls (PCBs)
• PCB contamination first recognized more than 30
  years ago by S. Jensen detecting PCBs in pike
  from Sweden. S. Jensen , Report of a new chemical
  hazard. New Scientist 32 (1966), p. 312.
• PCBs are now considered an environmental problem
  of global proportions.
• Several of these studies have indicated that the
  trends in environmental concentrations have
  followed the trends in production and use of
  PCBs.
• Quantitative knowledge of the global historical
  consumption is a prerequisite for estimating
  atmospheric emissions and eventually establishing
  sourcereceptor relationships for intentionally
  produced PCBs on a global scale.
• Not all congeners have been identified in
  commercial products or technical mixtures.
• Individual PCB congeners are assigned a number,
  ranging from PCB-1 (2-CB) to PCB-209
  (2,2',3,3',4,4',5,5',6,6'-CB). //IUPAC system.
  This numbering system is used in the study, and
  22 individual PCB congeners are studied.

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Organic Compounds

• Polychlorinated biphenyls (PCBs)
• Global Total PCB production in t as reported in
  the literature

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Organic Compounds

• Polychlorinated biphenyls (PCBs)

Global consumption of total PCBs for six
different time-periods (by latitude).

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Organic Compounds

• Polychlorinated biphenyls (PCBs)
• Global consumption

Estimated cumulative global usage of PCBs
(legends in t) with 11 longitude and latitude
resolution.
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Organic Compounds
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Organic Compounds
Dioxins - Sources and Pathways
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Organic Compounds
Dioxins - Emission
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Overview of Analytical Methods for Organic
Contaminants extraction, separation and
clean-up Regardless of the method used to
identify and quantify organic chemical
contaminants, steps must first be taken to
extract chemicals of interest from the bulk of
the sample material and to separate them from
other chemicals that might be co-extracted. These
steps are usually accomplished by "wet-chemistry"
procedures in the laboratory. The extraction and
separation methods selected by the analyst will
ultimately affect the limit of detection of the
chemical of interest and the final use of data.
The analyst begins to make trade-off decisions
(i.e., cost, method complexity, time, resolution,
etc.) at the time of initial sampling. These
early decisions concerning sample handling
ultimately affect data interpretation.
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Overview of Analytical Methods for Organic
Analytical instrumentation Usually, the end
result of the extraction, separation and clean-up
procedures used is a concentrated mixture
containing chemicals of similar structure that
can be analyzed further. This further analysis is
usually done by various kinds of instruments,
where instrument selection is based on the
specific data need. Some instrumentation will
only detect compound groups while others can
resolve and detect individual compounds. All
instrumentation have inherent detection limits
and these limits vary by orders-of-magnitude
between types of instruments. In addition to
sample resolution and limit detection
characteristics, the analyst will consider
initial cost, cost of operation, availability,
and operation complexity when making an
instrument decision.
Spectroscopic Methods UV-fluorescence When
excited by ultraviolet light, some organic
molecules are caused to emit fluorescent light.
By adjusting (or scanning) both the excitement
and emission spectra, aromatic hydrocarbons may
be analyzed. This method is specifically useful
to indicate the presence of polycyclic aromatic
hydrocarbons (PAH). This is a bulk measure and
provides little indication of the complexity of a
mixture or how much of a signal might derive from
interfering compounds (e.g., conjugated alkenes).
The use of this method is most appropriately
limited to highly contaminated samples or as a
screening technique. Reported results can not be
directly compared to results from other methods
of analysis.
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Overview of Analytical Methods for Organic
?Infra-red Spectroscopy (IR) ?? Organic molecules
have a flexible structure, which allows infrared
light to be absorbed by the molecule. The amount
of light absorbed (percent transmission) can be
related to structural characteristics of the
molecule and thus be used for identification.
This sensitive technique cannot be used for
analysis of individual hydrocarbons as it is
difficult to separate natural from contaminant
hydrocarbons however, it can be used for remote
analysis of samples. IR data will probably be
reported for environmental samples only in
situations which involve remote sensing of
complex mixtures such as for oil spills.
Principle IR With the absorption of light energy
in the range from 0.8-500 µm, different
mechanical vibrations of atoms or functional
groups are excited in a molecule.
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Overview of Analytical Methods for Organic
Chromatographic techniques All chromatographic
methods work on the same principle differential
mobility. Separation of molecular types, and even
individual compounds, is achieved by exploiting
the relative affinity of an organic compound (or
groups of similar compounds) to two phases one
mobile and one stationary. The phases may be
solid, liquid or gas and separation occurs as the
compound that is being analyzed spends more or
less time in either the mobile or the stationary
phase. Chromatography is a reliable method for
separation of hydrocarbon mixtures.
Gas Chromatography (GC) In GC, a gas carries the
volatilized sample mixture through a column in
which a liquid stationary phase has been coated.
After separation, the fractionated sample is
sequentially eluted and compounds of interest are
quantified on an appropriate detector. In early
environmental studies (pre-1975), most GC
analyses were accomplished in large diameter
columns that were packed with an inert substrate
on which the liquid phase was coated. Resolution
of complex environmental samples was mediocre and
full separation of most mixtures was not
possible. Beginning in the mid-70s,
high-resolution separation of environmental
samples using capillary GC began to be introduced
and eventually replaced packed column separations
as a routine analytical tool.
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Overview of Analytical Methods for Organic
Detectors Several detectors are available for the
analysis of the effluent stream from a gas
chromatography column. The flame ionization
detector is commonly selected because of its
applicability to a broad range of analytes.
Chemicals in the effluent stream are ionized in a
flame that is burning between two electrodes. The
ions migrate to one of the electrodes, and cause
a change in potential that is amplified and
detected. The electron capture detector has a
high sensitivity for analytes that contain
halides and is commonly used for the analysis of
chlorinated pesticides and PCBs.
Example High-resolution gas chromatogram of the
C6-C8 portion of a whole oil showing the
identification of more than 40 hydrocarbon
isomers, the distribution of which provides
information on source, maturity and alteration.
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Overview of Analytical Methods for Organic
High-Performance Liquid Chromatography (HPLC) In
HPLC, a liquid is pumped through a solid-phase
column to allow for partitioning between the
phases. With constantly improving resolution and
sensitivity, HPLC has evolved slowly into a
valuable analytical technique for separation of
chemical contaminants. Compounds are subsequently
eluted from the column and detection of the
presence and amount of chemical in the column
effluent is accomplished in a variety of ways,
including spectroscopy, change in refractive
index, UV-VIS absorption, or fluorescence after
excitation with a suitable wavelength.
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Organic Compounds in the Ecosystem
TCDD Tetrachlordibenzo-p-dioxine
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Organic Compounds in the Ecosystem
Bioaccumulation of PCBs
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Organic Compounds in the Ecosystem
Ecochemical materials properties and their
relevance for bioaccumulation of PCBs
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Organic Compounds in the Ecosystem
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Organic Compounds in the Ecosystem
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Organic Compounds in the Ecosystem
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Organic Compounds in the Ecosystem
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Organic Compounds
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Contamination with Organic Compounds
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Contamination with Organic Compounds
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Contamination with Organic Compounds
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Contamination with Organic Compounds
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Contamination with Organic Compounds