| Transport Mechanism |
Factors Affecting Transport |
| Chemical-specific considerations |
Site-specific considerations |
| Groundwater |
| Movement within and across aquifers and to surface water |
- Density (more or less dense than water)
- Water solubility
- KOC (organic carbon partition coefficient)
|
- Site hydrogeology
- Precipitation
- Infiltration rate
- Porosity
- Hydraulic conductivity
- Groundwater flow direction
- Depth to aquifer
- Groundwater/surface water recharge and discharge zones
- Presence of other compounds
- Soil type
- Geochemistry of site soils and aquifers
- Presence and condition of wells (well location, depth, and use; casing material and construction; pumping rate)
- Conduits, sewers
|
| Volatilization (to soil gas, ambient air, and indoor air) |
- Water solubility
- Vapor pressure
- Henry's Law Constant
- Diffusivity
|
- Depth to water table
- Soil type and cover
- Climatologic conditions
- Contaminant concentrations
- Properties of buildings
- Porosity and permeability of soils and shallow geologic materials
|
| Adsorption to soil or precipitation out of solution |
- Water solubility
- KOW (octanol/water partition coefficient)
- KOC
|
- Presence of natural carbon compounds
- Soil type, temperature, and chemistry
- Presence of other compounds
|
| Biologic uptake |
|
- Groundwater use for irrigation and livestock watering
|
| Soil (Surface and Subsurface), Sediment, Sludge, Waste Materials (Site-specific factors for Waste Materials are at the conclusion of this table) |
| Runoff (soil erosion) |
|
- Presence of plants
- Soil type and chemistry
- Precipitation rate
- Configuration of land and surface condition
|
| Leaching |
|
- Soil type
- Soil porosity and permeability
- Soil chemistry (especially acid/base)
- Cation exchange capacity
- Organic carbon content
|
| Volatilization |
- Vapor pressure
- Henry's Law Constant
|
- Physical properties of soil
- Chemical properties of soil
- Climatologic conditions
|
| Biologic uptake |
- Bioconcentration factor
- Bioavailability
|
- Soil properties
- Contaminant concentration
|
| Surface Water |
| Overland flow (via natural drainage or man-made channels) |
|
- Precipitation (amount, frequency, duration)
- Infiltration rate
- Topography (especially gradients and sink holes)
- Vegetative cover and land use
- Soil/sediment type and chemistry
- Use as water supply intake areas
- Location, width, and depth of channel; velocity; dilution factors; direction of flow
- Floodplains
- Point and nonpoint source discharge areas
|
| Volatilization |
- Water solubility
- Vapor pressure
- Henry's law constant
|
- Climatic conditions
- Surface area
- Contaminant concentration
|
| Hydrologic connection between surface water and groundwater |
|
- Groundwater/surface water recharge and discharge
- Stream bed permeability
- Soil type and chemistry
- Geology (especially Karst conditions)
|
| Adsorption to soil particles and sedimentation (of suspended and precipitated particles) |
- Water solubility
- KOW
- KOC
- Density
|
- Particle size and density
- Geochemistry of soils/sediments
- Organic carbon content of soils/sediment
|
| Biologic uptake |
- KOW
- Bioconcentration factor
|
- Chemical concentration
- Presence of fish, plants, and other animals
|
| Air |
| Aerosolization |
|
- Chemicals stored under pressure
|
| Atmospheric deposition |
|
|
| Volatilization |
|
- Presence of open containers, exposed surfaces, or leaking equipment
|
| Wind |
NA |
- Speed, direction, atmospheric stability
|
| Biota |
| Bioaccumulation |
- KOW
- Persistence/half-life
|
- Presence of plants and animals
- Consumption rate
|
| Migration |
NA |
- Commercial activities (farming, aquaculture, livestock, dairies)
- Sport activities (hunting, fishing)
- Migratory species
|
| Vapor sorption |
NA |
|
| Root uptake |
NA |
- Contaminant depth
- Soil moisture
- Plant species
|
| Waste Materials (Site-Specific Factors only) |
| Surface water runoff |
NA |
- Waste type
- Integrity of contaminant
- Integrity of containers, impoundments, and other structures
- Climatic conditions
|
| Leaching |
| Groundwater movement |
| Volatilization |
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