Chemical- and Site-Specific Factors That May Affect Contaminant Transport

Chemical- and Site-Specific Factors That May Affect Contamination Transport
Transport Mechanism	Factors Affecting Transport
Transport Mechanism	Chemical -specific considerations	Site-specific considerations
Ground water
Movement within and across aquifers and to surface water	Density (more or less dense than water) Water solubility K_OC (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, including foundation type (e.g., basement, slab, crawl-space), foundation thickness and condition (e.g., cracks or other openings in basement floors and walls, blocked crawlspace vents), sumps, ventilation systems, drainage, utility lines, and dwelling elevation relative to average grade. Porosity and permeability of soils and shallow geologic materials
Adsorption to soil or precipitation out of solution	Water solubility K_OW (octanol/water partition coefficient) K_OC	Presence of natural carbon compounds Soil type, temperature, and chemistry Presence of other compounds
Biologic uptake	K_OW	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)	Water solubility K_OC	Presence of plants Soil type and chemistry Precipitation rate Configuration of land and surface condition
Leaching	Water solubility K_OC	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)	Water solubility K_OC	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	Density	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 K_OW K_OC Density	Particle size and density Geochemistry of soils/sediments Organic carbon content of soils/sediment
Biologic uptake	K_OW Bioconcentration factor	Chemical concentration Presence of fish, plants, and other animals
Air
Aerosolization	Water solubility	Chemicals stored under pressure
Atmospheric deposition	Particle size	Rainfall/wind
Volatilization	Henry’s law constant	Presence of open containers, exposed surfaces, or leaking equipment
Wind	Not applicable	Speed, direction, atmospheric stability
Biota
Bioaccumulation	K_OW Persistence/half-life	Presence of plants and animals Consumption rate
Migration	Not applicable	Commercial activities (farming, aquaculture, livestock, dairies) Sport activities (hunting, fishing) Migratory species
Vapor sorption	Not applicable	Soil type Plant species
Root uptake	Not applicable	Contaminant depth Soil moisture Plant species
Waste Materials (Site-Specific Factors only)
Surface water runoff	Not applicable	Waste type Integrity of contaminant Integrity of containers, impoundments, and other structures Climatic conditions
Leaching
Groundwater movement
Volatilization