As part of the Regional Stream Quality Assessments (RSQA), hydrologists, ecologists, and technicians did ecological surveys of aquatic biota and stream habitat. Here, an ecologist uses a net to collect a sample of aquatic invertebrates for ennumeration and identification.
Barbara J Mahler (Former Employee)
Science and Products
USGS Streamgaging Network
The USGS Groundwater and Streamflow Information Program supports the collection and (or) delivery of both streamflow and water-level information at approximately 8,500 sites and water-level information alone for more than 1,700 additional sites. The data are served online—most in near realtime—to meet many diverse needs.
Urban Land Use and Water Quality
Wherever you live, there’s a creek or stream near you. The eighty percent of Americans who live in metropolitan areas are often unaware of the network of urban creeks—many teeming with life—that weaves through our cities and town. Nowhere are the environmental changes associated with urban development more evident than in urban streams.
NWQP Water-Quality Topics
From chloride to corrosivity, from pesticides to PAHs, find the most recent National Water Quality Program (NWQP) science on these topics and effects on surface water, groundwater, and ecology. Informative web pages provide an overview and links to related web pages, publications, maps, news, and data.
Coal-Tar-Based Pavement Sealcoat, PAHs, and Environmental Health
Sealcoat is the black, viscous liquid applied to many asphalt parking lots, driveways, and playgrounds in North America to protect and enhance the appearance of the underlying asphalt. Coal-tar-based pavement sealcoat is a potent source of polycyclic aromatic hydrocarbon (PAH) contamination in urban and suburban areas and a potential concern for human health and aquatic life.
Water-Quality Quick Links
Looking for data? Maps? Use the links below to quickly access some of the most frequently visited USGS web pages on water quality.
National Water-Quality Project Sampling Methods
USGS National Water Quality Assessment (NAWQA) studies require analyses of stream and bed-sediment samples for major ions, nutrients, sediments, and organic contaminants that are consistent across time and space. Procedures have been designed specifically to produce information that is comparable among studies in different parts of the Nation.
Water-Quality Trends
Is water quality getting better or worse? Answering this deceptively simple question has been a fundamental objective of the USGS National Water-Quality Assessment Project’s research. Learn about trends in contaminants in the nation’s streams and rivers, trends in contaminants that collect in the bed sediment of streams and lakes, and changes in the quality of the nation’s groundwater.
Sediment-Associated Contaminants
Stream, river, and lake bed sediment are reservoirs for many contaminants. These contaminants include some “legacy” contaminants, like DDT, PCBs, and chlordane, and chemicals currently in use, like the insecticide bifenthrin and many flame retardants. Learn about techniques used to study sediment-associated contaminants and their importance to aquatic biota.
USGS Research: PAHs and Coal-Tar-Based Pavement Sealcoat
Coal-tar-based pavement sealant is a potent source of polycyclic aromatic hydrocarbons (PAHs), as documented by the USGS and other researchers. Coal-tar-based sealcoat products typically are 20 to 35% coal tar or coal-tar pitch—these materials are known human carcinogens that contain high concentrations of PAHs and related chemicals. Coal-tar-based pavement sealcoat typically contains 35,000 to...
Webinar: Karst, Critters, and Climate Change: A Multidisciplinary Evaluation of Karst Species Vulnerability to Climate Change
View this webinar to learn how scientists are exploring the vulnerability of karst species to climate change.
Evaluating the Impacts of Climate Extremes on Karst Hydrology and Species Vulnerability
Karst aquifers—formed when the movement of water dissolves bedrock—are critical groundwater resources in North America. Water moving through these aquifers carves out magnificent caves, sinkholes, and other formations. These formations are home to high concentrations of rare and endangered species, but the hydrological conditions that support these species can change rapidly. Managing these ecosys
Filter Total Items: 24
An ecologist uses a net to collect a sample of aquatic invertebrates
As part of the Regional Stream Quality Assessments (RSQA), hydrologists, ecologists, and technicians did ecological surveys of aquatic biota and stream habitat. Here, an ecologist uses a net to collect a sample of aquatic invertebrates for ennumeration and identification.
Biofilms colonize a deployed tile
Biofilms take up pesticides in streams. Here, a hydrologic technician collects a sample of biofilm that has colonized an unglazed ceramic tile over 60-90 days. Learn more about biofilms as integrative samplers of pesticides here.
Biofilms take up pesticides in streams. Here, a hydrologic technician collects a sample of biofilm that has colonized an unglazed ceramic tile over 60-90 days. Learn more about biofilms as integrative samplers of pesticides here.
Biofilms colonize a deployed tile
Biofilms take up pesticides in streams. Here, a hydrologic technician collects a sample of biofilm that has colonized an unglazed ceramic tile over 60-90 days. Learn more about biofilms as integrative samplers of pesticides here.
Biofilms take up pesticides in streams. Here, a hydrologic technician collects a sample of biofilm that has colonized an unglazed ceramic tile over 60-90 days. Learn more about biofilms as integrative samplers of pesticides here.
Biofilms colonize a deployed tile
Biofilms take up pesticides in streams. Here, a hydrologic technician hold ups an unglazed ceramic tile that has been colonized by biofilm over 60-90 days. Learn more about biofilms as integrative samplers of pesticides here.
Biofilms take up pesticides in streams. Here, a hydrologic technician hold ups an unglazed ceramic tile that has been colonized by biofilm over 60-90 days. Learn more about biofilms as integrative samplers of pesticides here.
Hydrologic technicians survey and record streambed characteristics
As part of the Regional Stream Quality Assessments (RSQA), hydrologists, ecologists, and technicians did ecological surveys of aquatic biota and stream habitat. Here, two hydrologic technicians record characteristics of stream habitat.
As part of the Regional Stream Quality Assessments (RSQA), hydrologists, ecologists, and technicians did ecological surveys of aquatic biota and stream habitat. Here, two hydrologic technicians record characteristics of stream habitat.
Concrete channelization of urban creek
Sausal Creek in central Oakland, California, is an urban creek that has been extensively modified for flood control. The USGS Regional Stream Quality Assessment assessed the water quality and ecological integrity of small streams like Sausal Creek in five major regions of the country.
Sausal Creek in central Oakland, California, is an urban creek that has been extensively modified for flood control. The USGS Regional Stream Quality Assessment assessed the water quality and ecological integrity of small streams like Sausal Creek in five major regions of the country.
Concrete channelization of urban creek
Sausal Creek in central Oakland, California, is an urban creek that has been extensively modified for flood control. The USGS Regional Stream Quality Assessment assessed the water quality and ecological integrity of small streams like Sausal Creek in five major regions of the country.
Sausal Creek in central Oakland, California, is an urban creek that has been extensively modified for flood control. The USGS Regional Stream Quality Assessment assessed the water quality and ecological integrity of small streams like Sausal Creek in five major regions of the country.
A hydrologist carefully folds a filter used to collect an eDNA sample
As part of the Regional Stream Quality Assessments (RSQA), hydrologists, ecologists, and technicians did ecological surveys of aquatic biota and stream habitat. Here, a hydrologist carefully folds a filter used to collect a sample for analysis of eDNA.
As part of the Regional Stream Quality Assessments (RSQA), hydrologists, ecologists, and technicians did ecological surveys of aquatic biota and stream habitat. Here, a hydrologist carefully folds a filter used to collect a sample for analysis of eDNA.
A hydrologic technician records stream habitat characteristics
As part of the Regional Stream Quality Assessments (RSQA), hydrologists, ecologists, and technicians did ecological surveys of aquatic biota and stream habitat. Here, a hydrologic technician records characteristics of the habitat of a highly urbanized stream.
As part of the Regional Stream Quality Assessments (RSQA), hydrologists, ecologists, and technicians did ecological surveys of aquatic biota and stream habitat. Here, a hydrologic technician records characteristics of the habitat of a highly urbanized stream.
A geomorphologist walks a stream as part of an ecological survey
As part of the Regional Stream Quality Assessments (RSQA), hydrologists, ecologists, and technicians did ecological surveys of aquatic biota and stream habitat. Here, a geolomorphologist assesses stream banks.
As part of the Regional Stream Quality Assessments (RSQA), hydrologists, ecologists, and technicians did ecological surveys of aquatic biota and stream habitat. Here, a geolomorphologist assesses stream banks.
PAHs near pavement sealed or not sealed with coal-tar sealant
Concentrations of polycyclic aromatic hydrocarbons (PAHs) in settings near pavement sealed with coal-tar-based sealants were substantially higher than concentrations in settings where coal-tar sealant was not used.
Concentrations of polycyclic aromatic hydrocarbons (PAHs) in settings near pavement sealed with coal-tar-based sealants were substantially higher than concentrations in settings where coal-tar sealant was not used.
Transport pathways for PAHs from coal-tar-based sealcoat
Coal-tar-based sealcoat is a potent source of PAHs and related chemicals. Worn particles of coal-tar-based sealcoat are transported by rain, wind, tires, and even our feet from pavement to other environmental settings. Sealcoat product (A), after it dries, gradually abrades to a powder and becomes part of the dust on the pavement (B).
Coal-tar-based sealcoat is a potent source of PAHs and related chemicals. Worn particles of coal-tar-based sealcoat are transported by rain, wind, tires, and even our feet from pavement to other environmental settings. Sealcoat product (A), after it dries, gradually abrades to a powder and becomes part of the dust on the pavement (B).
Collecting a water-quality sample for the USGS Regional Stream Quality
Hydrologic Technician Denis Scanlon removes a Pankow sampler from Lincoln Creek, in Milwaukee, Wisconsin, as USGS Hydrologist Dave Saad assists. High waters make the job particularly challenging.
Hydrologic Technician Denis Scanlon removes a Pankow sampler from Lincoln Creek, in Milwaukee, Wisconsin, as USGS Hydrologist Dave Saad assists. High waters make the job particularly challenging.
micro-sampler collects "sips" of water for pesticide time-series
Micro-samplers are sophisticated instruments that collect small "sips" of water at frequent intervals. The samples, collected every few hours, provide a picture of how rapidly water quality can change over time. These samples were analyzed for a suite of hundreds of pesticides. In 2013, the USGS Regional Stream Quality Assessment (
Micro-samplers are sophisticated instruments that collect small "sips" of water at frequent intervals. The samples, collected every few hours, provide a picture of how rapidly water quality can change over time. These samples were analyzed for a suite of hundreds of pesticides. In 2013, the USGS Regional Stream Quality Assessment (
Installing a micro water-quality sampler in high water
Micro-samplers are sophisticated instruments that collect small "sips" of water at designated intervals. Installing one during high water conditions is a tricky business. The samples, collected every few hours, provide a picture of how rapidly water quality can change over time. These samples were analyzed for a suite of hundreds of pesticides.&nbs
Micro-samplers are sophisticated instruments that collect small "sips" of water at designated intervals. Installing one during high water conditions is a tricky business. The samples, collected every few hours, provide a picture of how rapidly water quality can change over time. These samples were analyzed for a suite of hundreds of pesticides.&nbs
Sealcoated Driveway With Basketball Hoop
A driveway in an upscale residential community in the Lake in the Hills, Ill, is coated with coal-tar-based sealcoat. The driveway has a basketball hoop and a skateboard ramp.
A driveway in an upscale residential community in the Lake in the Hills, Ill, is coated with coal-tar-based sealcoat. The driveway has a basketball hoop and a skateboard ramp.
Driveway with black sealcoat
Many homeowners have their driveway sealcoat to protect and beautify the underlying asphalt. Coal-tar-based sealcoat, predominantly used east of the Continental Divide, is a potent source of polycyclic aromatic hydrocarbons (PAHs). Read more about coal-tar-based sealcoat and PAHs here.
Many homeowners have their driveway sealcoat to protect and beautify the underlying asphalt. Coal-tar-based sealcoat, predominantly used east of the Continental Divide, is a potent source of polycyclic aromatic hydrocarbons (PAHs). Read more about coal-tar-based sealcoat and PAHs here.
Parking Lot With Coal-Tar-Based Sealcoat
Sealcoat particles abraded from a parking lot with coal-tar-based sealcoat collect by the curbside. Also shown is a storm drain, half coated with sealcoat, down which the loose particles will be washed by runoff.
Sealcoat particles abraded from a parking lot with coal-tar-based sealcoat collect by the curbside. Also shown is a storm drain, half coated with sealcoat, down which the loose particles will be washed by runoff.
Residential Driveways With Coal-Tar-Based Sealcoat
Driveways in an upscale residential subdivision in Lake in the Hills, Ill., are coated with black coal-tar-based sealcoat, contrasting with the white cement sidewalk.
Driveways in an upscale residential subdivision in Lake in the Hills, Ill., are coated with black coal-tar-based sealcoat, contrasting with the white cement sidewalk.
Black sealcoat contrasts with unsealcoated asphalt on parking lot
Sealcoat, marketed to protect and beautify the underlying asphalt, sharply contrasts here with the light gray of unsealcoated asphalt pavement. Read more about coal-tar-based sealcoat and PAHs here.
Sealcoat, marketed to protect and beautify the underlying asphalt, sharply contrasts here with the light gray of unsealcoated asphalt pavement. Read more about coal-tar-based sealcoat and PAHs here.
Sealcoat wear indicated by bare asphalt patches
The abrasive action of car tires and snow plows causes sealcoat to wear off. Here, light-colored patches indicate where the sealcoat has worn off and the underlying asphalt shows through.
The abrasive action of car tires and snow plows causes sealcoat to wear off. Here, light-colored patches indicate where the sealcoat has worn off and the underlying asphalt shows through.
Science and Products
USGS Streamgaging Network
The USGS Groundwater and Streamflow Information Program supports the collection and (or) delivery of both streamflow and water-level information at approximately 8,500 sites and water-level information alone for more than 1,700 additional sites. The data are served online—most in near realtime—to meet many diverse needs.
Urban Land Use and Water Quality
Wherever you live, there’s a creek or stream near you. The eighty percent of Americans who live in metropolitan areas are often unaware of the network of urban creeks—many teeming with life—that weaves through our cities and town. Nowhere are the environmental changes associated with urban development more evident than in urban streams.
NWQP Water-Quality Topics
From chloride to corrosivity, from pesticides to PAHs, find the most recent National Water Quality Program (NWQP) science on these topics and effects on surface water, groundwater, and ecology. Informative web pages provide an overview and links to related web pages, publications, maps, news, and data.
Coal-Tar-Based Pavement Sealcoat, PAHs, and Environmental Health
Sealcoat is the black, viscous liquid applied to many asphalt parking lots, driveways, and playgrounds in North America to protect and enhance the appearance of the underlying asphalt. Coal-tar-based pavement sealcoat is a potent source of polycyclic aromatic hydrocarbon (PAH) contamination in urban and suburban areas and a potential concern for human health and aquatic life.
Water-Quality Quick Links
Looking for data? Maps? Use the links below to quickly access some of the most frequently visited USGS web pages on water quality.
National Water-Quality Project Sampling Methods
USGS National Water Quality Assessment (NAWQA) studies require analyses of stream and bed-sediment samples for major ions, nutrients, sediments, and organic contaminants that are consistent across time and space. Procedures have been designed specifically to produce information that is comparable among studies in different parts of the Nation.
Water-Quality Trends
Is water quality getting better or worse? Answering this deceptively simple question has been a fundamental objective of the USGS National Water-Quality Assessment Project’s research. Learn about trends in contaminants in the nation’s streams and rivers, trends in contaminants that collect in the bed sediment of streams and lakes, and changes in the quality of the nation’s groundwater.
Sediment-Associated Contaminants
Stream, river, and lake bed sediment are reservoirs for many contaminants. These contaminants include some “legacy” contaminants, like DDT, PCBs, and chlordane, and chemicals currently in use, like the insecticide bifenthrin and many flame retardants. Learn about techniques used to study sediment-associated contaminants and their importance to aquatic biota.
USGS Research: PAHs and Coal-Tar-Based Pavement Sealcoat
Coal-tar-based pavement sealant is a potent source of polycyclic aromatic hydrocarbons (PAHs), as documented by the USGS and other researchers. Coal-tar-based sealcoat products typically are 20 to 35% coal tar or coal-tar pitch—these materials are known human carcinogens that contain high concentrations of PAHs and related chemicals. Coal-tar-based pavement sealcoat typically contains 35,000 to...
Webinar: Karst, Critters, and Climate Change: A Multidisciplinary Evaluation of Karst Species Vulnerability to Climate Change
View this webinar to learn how scientists are exploring the vulnerability of karst species to climate change.
Evaluating the Impacts of Climate Extremes on Karst Hydrology and Species Vulnerability
Karst aquifers—formed when the movement of water dissolves bedrock—are critical groundwater resources in North America. Water moving through these aquifers carves out magnificent caves, sinkholes, and other formations. These formations are home to high concentrations of rare and endangered species, but the hydrological conditions that support these species can change rapidly. Managing these ecosys
Filter Total Items: 24
An ecologist uses a net to collect a sample of aquatic invertebrates
As part of the Regional Stream Quality Assessments (RSQA), hydrologists, ecologists, and technicians did ecological surveys of aquatic biota and stream habitat. Here, an ecologist uses a net to collect a sample of aquatic invertebrates for ennumeration and identification.
As part of the Regional Stream Quality Assessments (RSQA), hydrologists, ecologists, and technicians did ecological surveys of aquatic biota and stream habitat. Here, an ecologist uses a net to collect a sample of aquatic invertebrates for ennumeration and identification.
Biofilms colonize a deployed tile
Biofilms take up pesticides in streams. Here, a hydrologic technician collects a sample of biofilm that has colonized an unglazed ceramic tile over 60-90 days. Learn more about biofilms as integrative samplers of pesticides here.
Biofilms take up pesticides in streams. Here, a hydrologic technician collects a sample of biofilm that has colonized an unglazed ceramic tile over 60-90 days. Learn more about biofilms as integrative samplers of pesticides here.
Biofilms colonize a deployed tile
Biofilms take up pesticides in streams. Here, a hydrologic technician collects a sample of biofilm that has colonized an unglazed ceramic tile over 60-90 days. Learn more about biofilms as integrative samplers of pesticides here.
Biofilms take up pesticides in streams. Here, a hydrologic technician collects a sample of biofilm that has colonized an unglazed ceramic tile over 60-90 days. Learn more about biofilms as integrative samplers of pesticides here.
Biofilms colonize a deployed tile
Biofilms take up pesticides in streams. Here, a hydrologic technician hold ups an unglazed ceramic tile that has been colonized by biofilm over 60-90 days. Learn more about biofilms as integrative samplers of pesticides here.
Biofilms take up pesticides in streams. Here, a hydrologic technician hold ups an unglazed ceramic tile that has been colonized by biofilm over 60-90 days. Learn more about biofilms as integrative samplers of pesticides here.
Hydrologic technicians survey and record streambed characteristics
As part of the Regional Stream Quality Assessments (RSQA), hydrologists, ecologists, and technicians did ecological surveys of aquatic biota and stream habitat. Here, two hydrologic technicians record characteristics of stream habitat.
As part of the Regional Stream Quality Assessments (RSQA), hydrologists, ecologists, and technicians did ecological surveys of aquatic biota and stream habitat. Here, two hydrologic technicians record characteristics of stream habitat.
Concrete channelization of urban creek
Sausal Creek in central Oakland, California, is an urban creek that has been extensively modified for flood control. The USGS Regional Stream Quality Assessment assessed the water quality and ecological integrity of small streams like Sausal Creek in five major regions of the country.
Sausal Creek in central Oakland, California, is an urban creek that has been extensively modified for flood control. The USGS Regional Stream Quality Assessment assessed the water quality and ecological integrity of small streams like Sausal Creek in five major regions of the country.
Concrete channelization of urban creek
Sausal Creek in central Oakland, California, is an urban creek that has been extensively modified for flood control. The USGS Regional Stream Quality Assessment assessed the water quality and ecological integrity of small streams like Sausal Creek in five major regions of the country.
Sausal Creek in central Oakland, California, is an urban creek that has been extensively modified for flood control. The USGS Regional Stream Quality Assessment assessed the water quality and ecological integrity of small streams like Sausal Creek in five major regions of the country.
A hydrologist carefully folds a filter used to collect an eDNA sample
As part of the Regional Stream Quality Assessments (RSQA), hydrologists, ecologists, and technicians did ecological surveys of aquatic biota and stream habitat. Here, a hydrologist carefully folds a filter used to collect a sample for analysis of eDNA.
As part of the Regional Stream Quality Assessments (RSQA), hydrologists, ecologists, and technicians did ecological surveys of aquatic biota and stream habitat. Here, a hydrologist carefully folds a filter used to collect a sample for analysis of eDNA.
A hydrologic technician records stream habitat characteristics
As part of the Regional Stream Quality Assessments (RSQA), hydrologists, ecologists, and technicians did ecological surveys of aquatic biota and stream habitat. Here, a hydrologic technician records characteristics of the habitat of a highly urbanized stream.
As part of the Regional Stream Quality Assessments (RSQA), hydrologists, ecologists, and technicians did ecological surveys of aquatic biota and stream habitat. Here, a hydrologic technician records characteristics of the habitat of a highly urbanized stream.
A geomorphologist walks a stream as part of an ecological survey
As part of the Regional Stream Quality Assessments (RSQA), hydrologists, ecologists, and technicians did ecological surveys of aquatic biota and stream habitat. Here, a geolomorphologist assesses stream banks.
As part of the Regional Stream Quality Assessments (RSQA), hydrologists, ecologists, and technicians did ecological surveys of aquatic biota and stream habitat. Here, a geolomorphologist assesses stream banks.
PAHs near pavement sealed or not sealed with coal-tar sealant
Concentrations of polycyclic aromatic hydrocarbons (PAHs) in settings near pavement sealed with coal-tar-based sealants were substantially higher than concentrations in settings where coal-tar sealant was not used.
Concentrations of polycyclic aromatic hydrocarbons (PAHs) in settings near pavement sealed with coal-tar-based sealants were substantially higher than concentrations in settings where coal-tar sealant was not used.
Transport pathways for PAHs from coal-tar-based sealcoat
Coal-tar-based sealcoat is a potent source of PAHs and related chemicals. Worn particles of coal-tar-based sealcoat are transported by rain, wind, tires, and even our feet from pavement to other environmental settings. Sealcoat product (A), after it dries, gradually abrades to a powder and becomes part of the dust on the pavement (B).
Coal-tar-based sealcoat is a potent source of PAHs and related chemicals. Worn particles of coal-tar-based sealcoat are transported by rain, wind, tires, and even our feet from pavement to other environmental settings. Sealcoat product (A), after it dries, gradually abrades to a powder and becomes part of the dust on the pavement (B).
Collecting a water-quality sample for the USGS Regional Stream Quality
Hydrologic Technician Denis Scanlon removes a Pankow sampler from Lincoln Creek, in Milwaukee, Wisconsin, as USGS Hydrologist Dave Saad assists. High waters make the job particularly challenging.
Hydrologic Technician Denis Scanlon removes a Pankow sampler from Lincoln Creek, in Milwaukee, Wisconsin, as USGS Hydrologist Dave Saad assists. High waters make the job particularly challenging.
micro-sampler collects "sips" of water for pesticide time-series
Micro-samplers are sophisticated instruments that collect small "sips" of water at frequent intervals. The samples, collected every few hours, provide a picture of how rapidly water quality can change over time. These samples were analyzed for a suite of hundreds of pesticides. In 2013, the USGS Regional Stream Quality Assessment (
Micro-samplers are sophisticated instruments that collect small "sips" of water at frequent intervals. The samples, collected every few hours, provide a picture of how rapidly water quality can change over time. These samples were analyzed for a suite of hundreds of pesticides. In 2013, the USGS Regional Stream Quality Assessment (
Installing a micro water-quality sampler in high water
Micro-samplers are sophisticated instruments that collect small "sips" of water at designated intervals. Installing one during high water conditions is a tricky business. The samples, collected every few hours, provide a picture of how rapidly water quality can change over time. These samples were analyzed for a suite of hundreds of pesticides.&nbs
Micro-samplers are sophisticated instruments that collect small "sips" of water at designated intervals. Installing one during high water conditions is a tricky business. The samples, collected every few hours, provide a picture of how rapidly water quality can change over time. These samples were analyzed for a suite of hundreds of pesticides.&nbs
Sealcoated Driveway With Basketball Hoop
A driveway in an upscale residential community in the Lake in the Hills, Ill, is coated with coal-tar-based sealcoat. The driveway has a basketball hoop and a skateboard ramp.
A driveway in an upscale residential community in the Lake in the Hills, Ill, is coated with coal-tar-based sealcoat. The driveway has a basketball hoop and a skateboard ramp.
Driveway with black sealcoat
Many homeowners have their driveway sealcoat to protect and beautify the underlying asphalt. Coal-tar-based sealcoat, predominantly used east of the Continental Divide, is a potent source of polycyclic aromatic hydrocarbons (PAHs). Read more about coal-tar-based sealcoat and PAHs here.
Many homeowners have their driveway sealcoat to protect and beautify the underlying asphalt. Coal-tar-based sealcoat, predominantly used east of the Continental Divide, is a potent source of polycyclic aromatic hydrocarbons (PAHs). Read more about coal-tar-based sealcoat and PAHs here.
Parking Lot With Coal-Tar-Based Sealcoat
Sealcoat particles abraded from a parking lot with coal-tar-based sealcoat collect by the curbside. Also shown is a storm drain, half coated with sealcoat, down which the loose particles will be washed by runoff.
Sealcoat particles abraded from a parking lot with coal-tar-based sealcoat collect by the curbside. Also shown is a storm drain, half coated with sealcoat, down which the loose particles will be washed by runoff.
Residential Driveways With Coal-Tar-Based Sealcoat
Driveways in an upscale residential subdivision in Lake in the Hills, Ill., are coated with black coal-tar-based sealcoat, contrasting with the white cement sidewalk.
Driveways in an upscale residential subdivision in Lake in the Hills, Ill., are coated with black coal-tar-based sealcoat, contrasting with the white cement sidewalk.
Black sealcoat contrasts with unsealcoated asphalt on parking lot
Sealcoat, marketed to protect and beautify the underlying asphalt, sharply contrasts here with the light gray of unsealcoated asphalt pavement. Read more about coal-tar-based sealcoat and PAHs here.
Sealcoat, marketed to protect and beautify the underlying asphalt, sharply contrasts here with the light gray of unsealcoated asphalt pavement. Read more about coal-tar-based sealcoat and PAHs here.
Sealcoat wear indicated by bare asphalt patches
The abrasive action of car tires and snow plows causes sealcoat to wear off. Here, light-colored patches indicate where the sealcoat has worn off and the underlying asphalt shows through.
The abrasive action of car tires and snow plows causes sealcoat to wear off. Here, light-colored patches indicate where the sealcoat has worn off and the underlying asphalt shows through.