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Chemical Considerations in Stream Restoration
Paul CapelResearch Team Leader
National Water Quality Assessment Program
U.S. Geological Survey
Adjunct Associate ProfessorDepartment of Civil Engineering
University of Minnesota
[email protected]
Photo: www.ctpurcellinc.com/gallery.htm
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“Big Picture” Perspective of Chemicals in Streams
Cl-
Photos: http://www.sharnoffphotos.com, http://www.evsc.virginia.edu
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Questions for You !
1.What do chemicals have to do with stream restoration?
2.What chemicals are of importance to stream restoration? Why?
3.What questions would you like addressed during this class?
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THE “OLIVE THEORY” OF THE BEHAVIOR AND TRANSPORT OF CHEMICALS IN THE ENVIRONMENT
Properties of the Environment
- temperature- pH- salinity- kind of solids- amount of solids- amount of water- bacteria....
Properties of the Chemical
- water solubility- vapor pressure- Henry’s Law- acid / base- charge- size- reactivity.....
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Chemical-based Concerns
-- Toxicity, health effects (human, ecosystem)
-- Accumulation in biota (human, ecosystem)
-- Accumulation in hydrologic system (volume loss, disposal, legacy, …)
-- Ecosystem / habitat change
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Energy and Carbon Flow in Streams
Source: http://www.mrothery.co.uk/ecology
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“Needs” for a Healthy Stream Ecosystem
-- Light
-- Heat (relatively stable temperature)
-- Habitat
-- Dissolved oxygen
-- Carbon
-- Nutrients (N, P)
-- Lack of toxic chemicals
-- Biotic diversity
-- ….
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Chemical Distribution among Environmental Phases
liquid (water), air, solid
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Solids-Water Distribution
concentration of the chemical on solid (mg/kg)
concentration of the chemical in water (mg/L)
Air-Water Distribution
concentration of the chemical in air (mg/m3)
concentration of the chemical in water (mg/L)
Kd =
Kaw =
Chemical Distribution among Environmental Phases
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Holistic Perspectives of Chemicals in Streams
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Capel et al., USGS, in review
EQUILIBRIUM DISTRIBUTIONS OF CHEMICALS AMOUNG SOLIDS, WATER, AND AIR
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Chemical Transformations
Induced by (external energy): - light - biota - chemical - hydrolysis - oxidation - reduction- heat
“Half-life”: time for 50% to be transformed
“Environmental lifetime” of a chemical = 6 half-lives (~1% remains)
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Holistic Perspectives of Chemicals in Streams
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Capel et al., USGS, in review
Legacy Chemicals
Legacy Chemicals
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“Chemicals” of Particular Interest
-- Carbon
-- Nutrients (N, P)
-- Salts
-- Sediment
-- Trace Elements
-- Organic chemicals
-- Pathogens
Important Redox Elements
-- Oxygen
-- Nitrogen
-- Manganese
-- Iron
-- Sulfur
-- Carbon
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“Chemicals” of Particular Interest: Carbon
-- Natural Organic Matter (NOM, DOC, ...)
-- Anthropogenic Organic Chemicals
Source: http://www.acadiau.ca/~jmurimbo
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“Chemicals” of Particular Interest: Nutrients (N, P)
-- necessary for growth (limiting nutrient)
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“Chemicals” of Particular Interest: Salts
-- major ions (Na+, K+, Ca++, Mg++, Cl-, SO4
--, HCO3-)
-- Sources: -- road salt -- irrigation return -- natural -- seawater intrusion
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“Chemicals” of Particular Interest: Sediment
-- as particles themselves turbidity, erosion, sedimentation, ...
-- as carriers of chemicals
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“Chemicals” of Particular Interest: Trace Elements
-- low-abundance cations copper, zinc, mercury, chromium, arsenic, ... iron, manganese, aluminum, ...-- Sources: -- anthropogenic -- natural -- mobilized by redox changes (As, Se)
Kesterson Reservoir, CACopper sulfate
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“Chemicals” of Particular Interest: Organics
Anthropogenic Organic Chemicals
PCBs, PAHs, dioxins, PBDE, PFOS, pesticides, detergents, disinfectants, pharmaceuticals, plastics, personal care products, ...
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“Chemicals” of Particular Interest: Pathogens
-- microorganisms that cause disease bacteria, fungi, parasites, and viruses
Staphylococcus E. coli
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Source: http://www.soils.wisc.edu/courses/SS325
-- Oxygen
-- Nitrogen-- Manganese
-- Iron
-- Sulfur-- Carbon
Important Redox Elements
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Mineral surfaces
Organic matter
Air
WaterChemical
SOIL-CHEMICAL INTERACTIONS
Photo: Karnok, 2003, Australian Turfgrass Management
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CHEMICAL CONTROLS ONSOIL-CHEMICAL INTERACTIONS
WaterSolubility (S)
Charge andreactivity
Henry’s Lawconstant (~V/S)
Vapor pressure (V)
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EQUATIONS – FOR THE ENGINNERS !
Solids-Water Distribution
concentration of the chemical on solid (mg/kg)
concentration of the chemical in water (mg/L)
Air-Water Distribution
concentration of the chemical in air (mg/m3)
concentration of the chemical in water (mg/L)
Kd =
Kaw =
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Capel et al., USGS, in review
EQUILIBRIUM DISTRIBUTIONS OF CHEMICALS AMOUNG SOLIDS, WATER, AND AIR
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Capel et al., USGS, in review
EQUILIBRIUM DISTRIBUTIONS OF CHEMICALS AMOUNG SOLIDS, WATER, AND AIR
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Capel et al., USGS, in review
Legacy Chemicals
Legacy Chemicals
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Nitrate as a Legacy Chemical
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Sediment as a Legacy “Chemical”
Source: http://www.fws.gov/digitalmedia
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Source: Gilliom et al., USGS Circular 1291
DDT and Friends as Legacy Chemicals
Dredging sediments!
Many trace elements, too!
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Landscape Changes: Improved Irrigation
Furrow / Flood to Sprinkler
Central Washington
<1980s present
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Landscape Changes: Improved Irrigation
Granger Drain
Yakima River
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Landscape Changes: Improved Irrigation
Unfortunate result ...
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Excess Irrigation: “Delta” Region (Mississippi)
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Excess Irrigation: “Delta” Region (Mississippi)
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Excess Irrigation: “Delta” Region (Mississippi)
Big Sunflower River (kind of ....)
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Influence of Water Flowpaths to the Stream
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Influence of Water
Flowpaths
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Influence of Water Flowpaths to the Stream
Nitrate concentrations and watershed yields for agricultural streams with various types of
dominant water flowpaths
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Agricultural DitchesSouthfork of the Iowa River
Source: http://www.southforkwatershed.org
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Starts in three tile drains, emerges from a culvert, …
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and turns into a very beautiful stream.