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DESCRIPTIONOrganic (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 - PowerPoint PPT Presentation
Contaminant TypesOrganic (carbon based)PathogensPAHsHalogenated HydrocarbonsDDD, DDE, DDT, 2,4-D and 2,4,5-T PCBsPersistent Organic Pollutants (POPs)PCBs, aldrin, chlordane, DDT, dieldrin, endrin, mirex, toxaphane, and heptachlor as well as dioxins, hexachlorobenzene, and furans
InorganicNutrientsP, N, C
Metals/MetalloidsPb, Zn, Cd, Cu, Hg, Cr, NiAs, Sb
RadionuclidesAlpha, Beta, Gamma U/Th Series
Contaminant TypesPAHs Polycyclic Aromatic Hydrocarbons
PCBs - Polychorinated biphenyl compound
POPs Persistent Organic Pollutants
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).
NutrientsN, P, C, KEutrophication (Cultural/natural)P control in freshwaterN control in marine waters
Nitrate methylmeglobenemia (blue baby disease.
Metals and MetalloidsTheir 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.
Heavy MetalsIncludes: 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 >3.5 g/cm3 to >7 g/cm3. Hodson (2004) has argued that investigators should avoid using the term.
RadionuclidesProduced by the fission of relatively heavy elements such as uranium, thorium, and plutonium.Alpha particlesBeta particlesGamma rays
Measured in terms of picocurie (pCi): 3.7 x 10-2 disintegrations per second
National Assessments of Riverine EcosystemsThe National Water Quality Inventory (USEPA)
The National Sediment Quality Survey (USEPA)
The National Water-Quality Assessment Program (USGS)
Problems with National Assessmentsdata 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.
Important Aspects of the National Water Quality InventoryRequired 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
Water Quality StandardsConsist of Three ComponentsDesignated 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.
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
Leading Pollutants in Rivers and Streams19%
The National Sediment Quality Survey(Important Aspects)In response to 1992 Water Resources Development Act
Based on National Sediment InventoryContains 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.
Categorization of Monitoring StationsTier 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 expectedTier 3 no indication of associated adverse effects on aquatic or human health
National AssessmentRiver Reach CategoriesOf 21,000 Sites26 % Tier 149 % Tier 2Data not Uniformly Collected~ 5% of sediment inrivers is polluted enough to cause adverse effectsBased on a totalof 6,774 riverreaches
At Least One Tier 2 Station & Zero Tier 1 Sations (5 %)
All Tier 3 Stations (2 %)
At Least One Tier 1 Station (4%)4
At Least One Tier 2 Sation & Zero Tier 1 Sations (5 %)5
All Tier 3 Stations (2 %)2
No Data (89 %)89
Areas of Probable ConcernWatershed must contain:10 or more Tier 1 stationsAnd/or 75 % classified as Tier 1 or Tier 2
Of the 2,110 watersheds in assessment, only 488 have 10 or more sampling stationsOf these, ~20 % qualify as areas of probable concern.
Chemical Classes(National Sediment Quality Survey)PCBsPesticidesPAHs Other Organics (including dioxin & furans)MercuryOther Metals
Significance of Chemical Classes
Was AVS measured for the sampleWhat was the result of comparing [SEM] to [AVS]?Did Chemical concentrationExceed any metal screening values?noyesnoyes[SEM] [AVS] = 0 to 5[SEM] [AVS] > 5[SEM] [AVS] < 0
Sources of ContaminationPoint 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
Sources associated with selected classes of contaminants
Source/Chemical ClassMercuryMetalsPCBsPAHsPesticidesOtherOrganicsAgricultural croplands*Mine sites**Atmospheric Deposition******Urban Sources*****Industrial Discharges******Municipal Discharges******
National Water-Quality Assessment ProgramEstablished in 1991 in response to National Academy of Science Report;Primary Difference of Other AssessmentsWatershed basedSampling and Analysis Protocols are Consistent50 Watersheds included in analysis
Guiding Questions for NAWQAWhat 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?
Some NAWQA ConclusionsAgricultural Areas95 % of stream samples had measurable pesticides66 % exhibited 5 or more, including DDT
Urban Areas80 % of samples contained 5 or more pesticides
70 % of river samples from both areas exceeded nutrient levels for preventing eutrophication in rivers
A Significant NAWQA Conclusionvulnerability of water resources to contamination differs from region to region depending on the underlying geology, soils, hydrology, and land-management practices.