Contaminant Types

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Contaminant Types

• Organic (carbon based)
• Pathogens
• PAHs
• Halogenated Hydrocarbons
• DDD, DDE, DDT, 2,4-D and 2,4,5-T
• PCBs
• Persistent Organic Pollutants (POPs)
• PCBs, aldrin, chlordane, DDT, dieldrin, endrin,
  mirex, toxaphane, and heptachlor as well as
  dioxins, hexachlorobenzene, and furans

• Inorganic
• Nutrients
• P, N, C
• Metals/Metalloids
• Pb, Zn, Cd, Cu, Hg, Cr, Ni
• As, Sb
• Radionuclides
• Alpha, Beta, Gamma
• U/Th Series

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Contaminant Types

• PAHs Polycyclic Aromatic Hydrocarbons
• PCBs - Polychorinated biphenyl compound
• POPs Persistent Organic Pollutants
• Dioxins/Furans -

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Persistent Organic Pollutants (POPs)

• Other characteristics that make them particularly
  hazardous include
• (1) their propensity to accumulate in biota,
• (2) a strong tendency for concentrations to
  increase up the food chain (i.e., biomagnify),
• (3) their ability to be transported over long
  distances, and
• (4) their potential to be toxic to both humans
  and other animals at very low concentrations.
  More specifically, POPs have been linked to
  disruptions of the immune system, cancer,
  reproductive problems, and nervous system
  dysfunction.
• POPs were recently addressed by the Stockholm
  Convention, a United Nations Treaty that seeks to
  reduce or completely eliminate the production,
  use, and/or release of the 12 most important POPs
  (sometimes referred to as the dirty dozen).

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Nutrients

• N, P, C, K
• Eutrophication (Cultural/natural)
• P control in freshwater
• N control in marine waters
• Nitrate methylmeglobenemia (blue baby disease.

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Metals and Metalloids

• Their physical properties generally include
• They are good conductors of heat and electricity.
  
• They are malleable and ductile in their solid
  state.
• They show metallic luster.
• They are opaque.
• They have high density.
• They are solids (except mercury)
• They have crystal structure in which each atom is
  surrounded by eight to twelve near neighbors
• Their chemical properties generally are
• They have one to four valence electrons.
• They have low ionization potentials they readily
  lose electrons.
• They are good reducing agents.
• They are electopositive.

• Metals defined by an electrolysis test test
  consists of dissolving the element in acid and
  running an electric current through the solution.
  If the element is metallic, the atoms of the
  element will show a positive charge. That is they
  will seek the negative pole.

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Heavy Metals

• Includes Pb, Hg, Zn and others, most of which
  are transition elements
• These elements are often considered as the most
  harmful to aquatic ecosystems, and are of
  particular concern to site assessments because
  they can be extremely toxic to humans at high
  concentrations.
• Heavy metals are often defined according the
  density of the metal densities that have been
  cited in the literature range from gt3.5 g/cm3 to
  gt7 g/cm3.
• Hodson (2004) has argued that investigators
  should avoid using the term.

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Radionuclides

• Produced by the fission of relatively heavy
  elements such as uranium, thorium, and plutonium.
• Alpha particles
• Beta particles
• Gamma rays
• Measured in terms of picocurie (pCi)
• 3.7 x 10-2 disintegrations per second

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National Assessments of Riverine Ecosystems

• The National Water Quality Inventory (USEPA)
• The National Sediment Quality Survey (USEPA)
• The National Water-Quality Assessment Program
  (USGS)

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Problems with National Assessments

• data is typically collected by multiple people,
  using different protocols, and analyzed by
  different labs. Hard to determine if delineated
  trends are real or simply represent differences
  in the methods of sample collection and analysis.
• samplings sites are not randomly selected, but
  represent geochemical records collected to
  address a specific question. So, most large
  scale assessments are biased by the geographical
  distribution of the sampling locations.

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Important Aspects of the National Water Quality
Inventory

• Required by Section 305b of Clean Water Act
• Assessments conducted by states other
  jurisdictions, but USEPA must approve standards
• Findings reported to USEPA very other year

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Water Quality StandardsConsist of Three
Components

• Designated uses of water
• A set of criteria that are intended to protect
  human and aquatic life
• Some form of anti-degradation policy that
  attempts to prevent degraded waters from getting
  worse, and high quality waters from becoming
  degraded.

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River Reaches are Reported As

• Good Fully supporting of their uses, or fully
  supporting of all uses but are threatened for one
  or more
• Impaired partially or not supporting of one or
  more uses
• Not attainable not able to support one or more
  use

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Leading Pollutants in Rivers and Streams
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The National Sediment Quality Survey(Important
Aspects)

• In response to 1992 Water Resources Development
  Act
• Based on National Sediment Inventory
• Contains 2 million records of sediment chemistry
  and biological data from 21,000 monitoring
  stations
• Primary goal to assess probable risk of
  contaminated channel bed sediments to benthic
  organisms and human populations who consume
  aquatic organisms that have been exposed to
  contaminated materials.
• Also, aimed at identifying regions where
  additional studies are warranted.

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Categorization of Monitoring Stations

• Tier 1 associated adverse effects on aquatic
  life or human health are probable.
• Tier 2 associated adverse effects on aquatic
  life or human health are possible, but
  infrequently expected
• Tier 3 no indication of associated adverse
  effects on aquatic or human health

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National AssessmentRiver Reach Categories

• Of 21,000 Sites
• 26 Tier 1
• 49 Tier 2

• Data not Uniformly
• Collected
• 5 of sediment in
• rivers is polluted
• enough to cause adverse effects

Based on a total of 6,774 river reaches
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Areas of Probable Concern

• Watershed must contain
• 10 or more Tier 1 stations
• And/or 75 classified as Tier 1 or Tier 2
• Of the 2,110 watersheds in assessment, only 488
  have 10 or more sampling stations
• Of these, 20 qualify as areas of probable
  concern.

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Chemical Classes(National Sediment Quality
Survey)

• PCBs
• Pesticides
• PAHs
• Other Organics (including dioxin furans)
• Mercury
• Other Metals

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Significance of Chemical Classes
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What was the result of comparing SEM to AVS?
yes
Was AVS measured for the sample
no
SEM AVS gt 5
Did Chemical concentration Exceed any metal
screening values?
SEM AVS lt 0
yes
SEM AVS 0 to 5
no
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Sources of Contamination

• Point source refers to the discharge of
  contaminants from a specific location, such as
  the end of a pipe or canal
• Nonpoint source refers to the delivery of
  pollutants to a river from a diffuse area, such
  as an agricultural field or an urban center

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Sources associated with selected classes of
contaminants
Source/Chemical Class Mercury Metals PCBs PAHs Pesticides Other Organics
Agricultural croplands
Mine sites
Atmospheric Deposition
Urban Sources
Industrial Discharges
Municipal Discharges
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National Water-Quality Assessment Program

• Established in 1991 in response to National
  Academy of Science Report
• Primary Difference of Other Assessments
• Watershed based
• Sampling and Analysis Protocols are Consistent
• 50 Watersheds included in analysis

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Guiding Questions for NAWQA

• What is the current conditions of the water
  resources in U.S.?
• How is water quality changing over time?
• What are the natural and human controls on stream
  and groundwater quality?

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Some NAWQA Conclusions

• Agricultural Areas
• 95 of stream samples had measurable pesticides
• 66 exhibited 5 or more, including DDT
• Urban Areas
• 80 of samples contained 5 or more pesticides
• 70 of river samples from both areas exceeded
  nutrient levels for preventing eutrophication in
  rivers

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A Significant NAWQA Conclusion

• vulnerability of water resources to contamination
  differs from region to region depending on the
  underlying geology, soils, hydrology, and
  land-management practices.