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Carbon in Urban River Biogeochemistry Project

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By Washington Water Science Center September 11, 2025

Carbon in Urban River Biogeochemistry Project

The Issue:

In aquatic ecosystems, dissolved organic carbon represents the largest flux of carbon in streams and it is a primary energy source in aquatic food webs. There is limited understanding of how human activities related to urban development influence the timing and scale of carbon cycling in aquatic ecosystems. 

How USGS will help:

The USGS is working with university partners to assess how urban development impacts in-stream dissolved organic carbon quality, quantity, and timing in five U.S. cities. 

More information about the Carbon in Urban River Biogeochemistry Project

Problem

Most ecosystems worldwide are impacted by human activities; yet the effects of human activities at variable scales are not adequately represented by existing ecosystem models. This is especially true for models of aquatic carbon cycling and fluxes.

Objectives

Media
US map showing study cities (Portland, Salt Lake City, Atlanta, Miami, Boston)
Sources/Usage: Some content may have restrictions. View Media Details
Locations and characteristics of the five cities included in the Carbon in Urban River Biogeochemistry Project.

The Carbon in Urban River Biogeochemistry Project’s main goal is to understand how the things humans build – like wastewater systems and residential neighborhoods – and natural factors – like streamflow and rainfall – influence the amount, makeup, and how easily carbon can be used by organisms and how those effects change in different types of urban areas. 

The USGS, in collaboration with university partners, is studying how the quality, quantity, and timing of dissolved organic carbon in streams vary across different urban environments. This research is taking place in five U.S. cities that represent a wide range of climates and eras of urban development. Cities include Portland, Oregon, Salt Lake City, Utah, Atlanta, Georgia, Miami, Florida, and Boston, Massachusetts.  By comparing these different urban environments, the study aims to better understand how urban landscapes influence carbon dynamics in freshwater systems.

Approach

Synoptic water quality sampling

University partners collected water samples over four seasons at 100 urban stream sites in each city. Water samples were analyzed for dissolved organic carbon concentration, bioavailability (via enzyme activity), and fluorescence. Additional measurements of stream discharge, water temperature, pH, specific conductance, and dissolved oxygen were also taken to help contextualize spatial and temporal trends in dissolved organic carbon. These data will be used to assess how human and natural controls on water quality vary across urban contexts.

In-stream water quality sensors

At three sites in each city, university partners installed sensors to measure dissolved organic matter, temperature, pH, conductivity, turbidity, and optical brighteners (an indicator of wastewater contamination). Measurements were recorded at 15-minute intervals for roughly one year. These data will be used to understand how stream water characteristics change over time in urban watersheds.

Media
Scientist collecting water samples on bridge
Sources/Usage: Some content may have restrictions. View Media Details
Water quality samples collected from the Malden River at Hwy 16 in Medford, MA in September 2021.
Media
Scientists installing sensor in river
Sources/Usage: Some content may have restrictions. View Media Details
Water quality sensors installed on the South River at Springdale Road in Atlanta, GA in November 2021. 

Relevance and Benefits

By studying how human activities affect carbon in rivers, scientists can better predict when and how carbon is released into the environment—and come up with smarter ways to reduce it. Since organic carbon plays a key role in keeping aquatic ecosystems healthy, this research also helps us understand how streams and rivers work. That means we can make better decisions when restoring urban waterways, leading to cleaner, more vibrant places for both people and wildlife.

The important role of dissolved organic carbon in streams

  • Source of energy and carbon for heterotrophic organisms: Dissolved organic carbon is a primary energy source in aquatic food webs and the cycling of nutrients (nitrogen and phosphorous) is tied to these carbon metabolizing processes.
  • Influences with light and UV radiation: Dissolved organic carbon absorbs both ultraviolet and visible light, meaning its concentration directly affects how much light is available for organisms that rely on photosynthesis.
  • Contaminant transport: Organic compounds and trace metals can bind to dissolved organic carbon thereby influencing their transport and release into aquatic ecosystems. 

 

Media
Remote image Url
Diagram showing sources and transport of organic matter within and adjacent to urban streams.
Sources/Usage: Some content may have restrictions. View Media Details
Diagram of the factors shaping the source and movement of organic matter in urban streams. Source (Hale et al. 2025).

Data

Data associated with this project are listed below. 

Landscape Characteristics

  • Hopkins, K.G., Hale, R., Capps, K., Kominoski, J., Morse, J., Roy, A., Blinn, A., Chen, S., Ortiz Muñoz, L., Quick, A., Rudolph, J., 2024, Landscape characteristics for urban gradients in United States cities across multiple scales: U.S. Geological Survey data release, https://doi.org/10.5066/P13UZYZF. 

Synoptic Water Quality Data

Data collected by university partners for the synoptic water quality sampling events are available through the Environmental Data Initiative. 

 

Boston, Massachusetts 

Miami, Florida

Portland, Oregon

Salt Lake City, Utah

U.S. Geological Survey publications are linked below.

Non-USGS Publications:

Ortiz Muñoz, L. D., and J. S. Kominoski. 2025. Forecasting climate and human alterations to coastal and estuarine dissolved organic matter. Limnology and Oceanography Letters 10(3):265-286. doi:10.1002/lol2.70002

Urban heterogeneity drives dissolved organic matter sources, transport, and transformation from local to macro scales Urban heterogeneity drives dissolved organic matter sources, transport, and transformation from local to macro scales

Urbanization reshapes dissolved organic matter (DOM) sources, transport, and transformations through changes in vegetation, hydrology, and management of waste and water. Yet the impacts of urbanization on DOM are variable within and among cities. Predicting heterogeneous responses to urbanization is challenged by diverse human activities and underlying biophysical variation along stream...
Authors
Rebecca Hale, Kristina G. Hopkins, Krista A. Capps, John S. Kominoski, Jennifer L. Morse, Allison H. Roy, Shuo Chen, Annika Quick, Andrew Blinn, Liz Ortiz Muñoz, Gwendolynn Folk
By
Washington Water Science Center

Salting behaviors influence urban stream conductivity in Boston, Massachusetts (USA) Salting behaviors influence urban stream conductivity in Boston, Massachusetts (USA)

Freshwater salinization is a major concern in temperate climates where road salt is used as a deicer to manage snow and ice on roadways. In urban and suburban areas, wastewater, weathering of infrastructure, and salting on parking lots and sidewalks can also contribute to salt contamination, but little is known about how well these sources explain variation in stream conductivity and...
Authors
Allison H. Roy, Annika Quick, Rebecca L. Hale, Kristina G. Hopkins, Jack S. Soucie
By
Cooperative Research Units, South Atlantic Water Science Center (SAWSC)

Overcoming challenges in mapping hydrography and heterogeneity in urban landscapes Overcoming challenges in mapping hydrography and heterogeneity in urban landscapes

Understanding how water moves through a watershed is one of the most fundamental yet often complicated aspects of hydrology, especially in urban areas. Urban infrastructure and water management alter natural hydrological pathways in developed watersheds, which can violate assumptions of a watershed approach to ecosystem science. We focus on two aspects of urban landscapes that often...
Authors
Kristina G. Hopkins, Rebecca L. Hale, Krista A. Capps, John S. Kominoski, Jennifer L. Morse, Allison H. Roy, Andrew Blinn, Shuo Chen, Liz Ortiz Muñoz, Annika Quick, Jacob Rudolph
By
Cooperative Research Units, Washington Water Science Center

Spatial and temporal variation in dissolved organic matter in urban streams in metropolitan Boston, Massachusetts (USA) Spatial and temporal variation in dissolved organic matter in urban streams in metropolitan Boston, Massachusetts (USA)

Urban riverine systems are heterogeneous, and the substantial variability in impervious cover, riparian cover, wetlands, and wastewater and stormwater infrastructure affect sources and transport of dissolved organic matter (DOM), of which dissolved organic C (DOC) is a substantial component. An understanding of the quantity, bioavailability, and timing of DOM inputs (a key energy source...
Authors
Annika M. Quick, Allison H. Roy, Rebecca L. Hale, Kristina G. Hopkins, Shuo Chen, Liz D. Ortiz Muñoz
By
Cooperative Research Units

This project is a collaboration between the U.S. Geological Survey and partners at:

- Smithsonian Institution

- University of Georgia

- Florida International University

- Portland State University

Funding support is provided by the National Science Foundation

National Science Foundation (NSF) National Science Foundation (NSF)

The Issue:

In aquatic ecosystems, dissolved organic carbon represents the largest flux of carbon in streams and it is a primary energy source in aquatic food webs. There is limited understanding of how human activities related to urban development influence the timing and scale of carbon cycling in aquatic ecosystems. 

How USGS will help:

The USGS is working with university partners to assess how urban development impacts in-stream dissolved organic carbon quality, quantity, and timing in five U.S. cities. 

More information about the Carbon in Urban River Biogeochemistry Project

Problem

Most ecosystems worldwide are impacted by human activities; yet the effects of human activities at variable scales are not adequately represented by existing ecosystem models. This is especially true for models of aquatic carbon cycling and fluxes.

Objectives

Media
US map showing study cities (Portland, Salt Lake City, Atlanta, Miami, Boston)
Sources/Usage: Some content may have restrictions. View Media Details
Locations and characteristics of the five cities included in the Carbon in Urban River Biogeochemistry Project.

The Carbon in Urban River Biogeochemistry Project’s main goal is to understand how the things humans build – like wastewater systems and residential neighborhoods – and natural factors – like streamflow and rainfall – influence the amount, makeup, and how easily carbon can be used by organisms and how those effects change in different types of urban areas. 

The USGS, in collaboration with university partners, is studying how the quality, quantity, and timing of dissolved organic carbon in streams vary across different urban environments. This research is taking place in five U.S. cities that represent a wide range of climates and eras of urban development. Cities include Portland, Oregon, Salt Lake City, Utah, Atlanta, Georgia, Miami, Florida, and Boston, Massachusetts.  By comparing these different urban environments, the study aims to better understand how urban landscapes influence carbon dynamics in freshwater systems.

Approach

Synoptic water quality sampling

University partners collected water samples over four seasons at 100 urban stream sites in each city. Water samples were analyzed for dissolved organic carbon concentration, bioavailability (via enzyme activity), and fluorescence. Additional measurements of stream discharge, water temperature, pH, specific conductance, and dissolved oxygen were also taken to help contextualize spatial and temporal trends in dissolved organic carbon. These data will be used to assess how human and natural controls on water quality vary across urban contexts.

In-stream water quality sensors

At three sites in each city, university partners installed sensors to measure dissolved organic matter, temperature, pH, conductivity, turbidity, and optical brighteners (an indicator of wastewater contamination). Measurements were recorded at 15-minute intervals for roughly one year. These data will be used to understand how stream water characteristics change over time in urban watersheds.

Media
Scientist collecting water samples on bridge
Sources/Usage: Some content may have restrictions. View Media Details
Water quality samples collected from the Malden River at Hwy 16 in Medford, MA in September 2021.
Media
Scientists installing sensor in river
Sources/Usage: Some content may have restrictions. View Media Details
Water quality sensors installed on the South River at Springdale Road in Atlanta, GA in November 2021. 

Relevance and Benefits

By studying how human activities affect carbon in rivers, scientists can better predict when and how carbon is released into the environment—and come up with smarter ways to reduce it. Since organic carbon plays a key role in keeping aquatic ecosystems healthy, this research also helps us understand how streams and rivers work. That means we can make better decisions when restoring urban waterways, leading to cleaner, more vibrant places for both people and wildlife.

The important role of dissolved organic carbon in streams

  • Source of energy and carbon for heterotrophic organisms: Dissolved organic carbon is a primary energy source in aquatic food webs and the cycling of nutrients (nitrogen and phosphorous) is tied to these carbon metabolizing processes.
  • Influences with light and UV radiation: Dissolved organic carbon absorbs both ultraviolet and visible light, meaning its concentration directly affects how much light is available for organisms that rely on photosynthesis.
  • Contaminant transport: Organic compounds and trace metals can bind to dissolved organic carbon thereby influencing their transport and release into aquatic ecosystems. 

 

Media
Remote image Url
Diagram showing sources and transport of organic matter within and adjacent to urban streams.
Sources/Usage: Some content may have restrictions. View Media Details
Diagram of the factors shaping the source and movement of organic matter in urban streams. Source (Hale et al. 2025).

Data

Data associated with this project are listed below. 

Landscape Characteristics

  • Hopkins, K.G., Hale, R., Capps, K., Kominoski, J., Morse, J., Roy, A., Blinn, A., Chen, S., Ortiz Muñoz, L., Quick, A., Rudolph, J., 2024, Landscape characteristics for urban gradients in United States cities across multiple scales: U.S. Geological Survey data release, https://doi.org/10.5066/P13UZYZF. 

Synoptic Water Quality Data

Data collected by university partners for the synoptic water quality sampling events are available through the Environmental Data Initiative. 

 

Boston, Massachusetts 

Miami, Florida

Portland, Oregon

Salt Lake City, Utah

U.S. Geological Survey publications are linked below.

Non-USGS Publications:

Ortiz Muñoz, L. D., and J. S. Kominoski. 2025. Forecasting climate and human alterations to coastal and estuarine dissolved organic matter. Limnology and Oceanography Letters 10(3):265-286. doi:10.1002/lol2.70002

Urban heterogeneity drives dissolved organic matter sources, transport, and transformation from local to macro scales Urban heterogeneity drives dissolved organic matter sources, transport, and transformation from local to macro scales

Urbanization reshapes dissolved organic matter (DOM) sources, transport, and transformations through changes in vegetation, hydrology, and management of waste and water. Yet the impacts of urbanization on DOM are variable within and among cities. Predicting heterogeneous responses to urbanization is challenged by diverse human activities and underlying biophysical variation along stream...
Authors
Rebecca Hale, Kristina G. Hopkins, Krista A. Capps, John S. Kominoski, Jennifer L. Morse, Allison H. Roy, Shuo Chen, Annika Quick, Andrew Blinn, Liz Ortiz Muñoz, Gwendolynn Folk
By
Washington Water Science Center

Salting behaviors influence urban stream conductivity in Boston, Massachusetts (USA) Salting behaviors influence urban stream conductivity in Boston, Massachusetts (USA)

Freshwater salinization is a major concern in temperate climates where road salt is used as a deicer to manage snow and ice on roadways. In urban and suburban areas, wastewater, weathering of infrastructure, and salting on parking lots and sidewalks can also contribute to salt contamination, but little is known about how well these sources explain variation in stream conductivity and...
Authors
Allison H. Roy, Annika Quick, Rebecca L. Hale, Kristina G. Hopkins, Jack S. Soucie
By
Cooperative Research Units, South Atlantic Water Science Center (SAWSC)

Overcoming challenges in mapping hydrography and heterogeneity in urban landscapes Overcoming challenges in mapping hydrography and heterogeneity in urban landscapes

Understanding how water moves through a watershed is one of the most fundamental yet often complicated aspects of hydrology, especially in urban areas. Urban infrastructure and water management alter natural hydrological pathways in developed watersheds, which can violate assumptions of a watershed approach to ecosystem science. We focus on two aspects of urban landscapes that often...
Authors
Kristina G. Hopkins, Rebecca L. Hale, Krista A. Capps, John S. Kominoski, Jennifer L. Morse, Allison H. Roy, Andrew Blinn, Shuo Chen, Liz Ortiz Muñoz, Annika Quick, Jacob Rudolph
By
Cooperative Research Units, Washington Water Science Center

Spatial and temporal variation in dissolved organic matter in urban streams in metropolitan Boston, Massachusetts (USA) Spatial and temporal variation in dissolved organic matter in urban streams in metropolitan Boston, Massachusetts (USA)

Urban riverine systems are heterogeneous, and the substantial variability in impervious cover, riparian cover, wetlands, and wastewater and stormwater infrastructure affect sources and transport of dissolved organic matter (DOM), of which dissolved organic C (DOC) is a substantial component. An understanding of the quantity, bioavailability, and timing of DOM inputs (a key energy source...
Authors
Annika M. Quick, Allison H. Roy, Rebecca L. Hale, Kristina G. Hopkins, Shuo Chen, Liz D. Ortiz Muñoz
By
Cooperative Research Units

This project is a collaboration between the U.S. Geological Survey and partners at:

- Smithsonian Institution

- University of Georgia

- Florida International University

- Portland State University

Funding support is provided by the National Science Foundation

National Science Foundation (NSF) National Science Foundation (NSF)

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