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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
Photo: www.ctpurcellinc.com/gallery.htm
“Big Picture” Perspective of Chemicals in Streams
Cl-
Photos: http://www.sharnoffphotos.com, http://www.evsc.virginia.edu
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?
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.....
Chemical-based Concerns
-- Toxicity, health effects (human, ecosystem)
-- Accumulation in biota (human, ecosystem)
-- Accumulation in hydrologic system (volume loss, disposal, legacy, …)
-- Ecosystem / habitat change
Energy and Carbon Flow in Streams
Source: http://www.mrothery.co.uk/ecology
“Needs” for a Healthy Stream Ecosystem
-- Light
-- Heat (relatively stable temperature)
-- Habitat
-- Dissolved oxygen
-- Carbon
-- Nutrients (N, P)
-- Lack of toxic chemicals
-- Biotic diversity
-- ….
Chemical Distribution among Environmental Phases
liquid (water), air, solid
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
Holistic Perspectives of Chemicals in Streams
Capel et al., USGS, in review
EQUILIBRIUM DISTRIBUTIONS OF CHEMICALS AMOUNG SOLIDS, WATER, AND AIR
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)
Holistic Perspectives of Chemicals in Streams
Capel et al., USGS, in review
Legacy Chemicals
Legacy Chemicals
“Chemicals” of Particular Interest
-- Carbon
-- Nutrients (N, P)
-- Salts
-- Sediment
-- Trace Elements
-- Organic chemicals
-- Pathogens
Important Redox Elements
-- Oxygen
-- Nitrogen
-- Manganese
-- Iron
-- Sulfur
-- Carbon
“Chemicals” of Particular Interest: Carbon
-- Natural Organic Matter (NOM, DOC, ...)
-- Anthropogenic Organic Chemicals
Source: http://www.acadiau.ca/~jmurimbo
“Chemicals” of Particular Interest: Nutrients (N, P)
-- necessary for growth (limiting nutrient)
“Chemicals” of Particular Interest: Salts
-- major ions (Na+, K+, Ca++, Mg++, Cl-, SO4
--, HCO3-)
-- Sources: -- road salt -- irrigation return -- natural -- seawater intrusion
“Chemicals” of Particular Interest: Sediment
-- as particles themselves turbidity, erosion, sedimentation, ...
-- as carriers of chemicals
“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
“Chemicals” of Particular Interest: Organics
Anthropogenic Organic Chemicals
PCBs, PAHs, dioxins, PBDE, PFOS, pesticides, detergents, disinfectants, pharmaceuticals, plastics, personal care products, ...
“Chemicals” of Particular Interest: Pathogens
-- microorganisms that cause disease bacteria, fungi, parasites, and viruses
Staphylococcus E. coli
Source: http://www.soils.wisc.edu/courses/SS325
-- Oxygen
-- Nitrogen-- Manganese
-- Iron
-- Sulfur-- Carbon
Important Redox Elements
Mineral surfaces
Organic matter
Air
WaterChemical
SOIL-CHEMICAL INTERACTIONS
Photo: Karnok, 2003, Australian Turfgrass Management
CHEMICAL CONTROLS ONSOIL-CHEMICAL INTERACTIONS
WaterSolubility (S)
Charge andreactivity
Henry’s Lawconstant (~V/S)
Vapor pressure (V)
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 =
Capel et al., USGS, in review
EQUILIBRIUM DISTRIBUTIONS OF CHEMICALS AMOUNG SOLIDS, WATER, AND AIR
Capel et al., USGS, in review
EQUILIBRIUM DISTRIBUTIONS OF CHEMICALS AMOUNG SOLIDS, WATER, AND AIR
Capel et al., USGS, in review
Legacy Chemicals
Legacy Chemicals
Nitrate as a Legacy Chemical
Sediment as a Legacy “Chemical”
Source: http://www.fws.gov/digitalmedia
Source: Gilliom et al., USGS Circular 1291
DDT and Friends as Legacy Chemicals
Dredging sediments!
Many trace elements, too!
Landscape Changes: Improved Irrigation
Furrow / Flood to Sprinkler
Central Washington
<1980s present
Landscape Changes: Improved Irrigation
Granger Drain
Yakima River
Landscape Changes: Improved Irrigation
Unfortunate result ...
Excess Irrigation: “Delta” Region (Mississippi)
Excess Irrigation: “Delta” Region (Mississippi)
Excess Irrigation: “Delta” Region (Mississippi)
Big Sunflower River (kind of ....)
Influence of Water Flowpaths to the Stream
Influence of Water
Flowpaths
Influence of Water Flowpaths to the Stream
Nitrate concentrations and watershed yields for agricultural streams with various types of
dominant water flowpaths
Agricultural DitchesSouthfork of the Iowa River
Source: http://www.southforkwatershed.org
Starts in three tile drains, emerges from a culvert, …
and turns into a very beautiful stream.
