U.S. Geological Survey (USGS) scientists determined that the colmation layer (top 25 centimeters of lake sediments) was highly effective in removing cyanobacteria, viruses, and dissolved organic carbon during water passage through the lake bottom to aquifer sediments.
River-bank filtration has proven to be a sustainable and cost-effective method of removing microorganisms and chemicals from surface water during filtration through bottom and aquifer sediments. Lakes can also be important locations for bank filtration operations. The biologically active layer of sediments immediately beneath the sediment/water interface, sometimes referred to as the colmation layer, is considered to be important for contaminant and carbon removal, although its specific role(s) in the elimination of human pathogens poses a lingering question.
In this study, scientists focused on the importance of the upper 25 centimeters of lake sediments in the removal of cyanobacteria, bacteriophages (viruses of bacteria), and dissolved organic carbon during natural bank filtration in lakes. This study was done at two shallow (0.5 meter deep), sandy, near-shore sites at the southern end of Ashumet Pond, a waste-impacted, kettle pond on Cape Cod, Massachusetts , that is subject to periodic blooms of cyanobacteria and continuously recharges a sole-source drinking-water aquifer. Cultured cyanobacteria (Synechococcus sp. IU625), its cyanophage (virus, AS-1), a coliphage (MS-2), and synthetic microspheres were injected into a pond water/groundwater interface and tracked as they passed through the colmation layer and underlying aquifer sediments.
Scientists determined that more than 99 percent of the cyanobacteria and bacteriophages and approximately 44 percent of the pond-dissolved organic carbon were removed in the colmation layer. Scientists determined that the low relative breakthrough of the bacteriophages occurred through a combination of sorptive-filtration and inactivation. Although the physicochemical and biological parameters controlling microbial removal in the colmation layer vary from site to site, there is evidence to indicate that cyanobacteria populations are largely removed within the top few centimeters of bottom sediments during lake-bank filtration.
Environmental Health Considerations
Lakes can contain large numbers of cyanobacteria that may produce harmful toxins, as well as viruses and high levels of dissolved organic carbon that can be of concern if the lakes are used as sources of drinking water. The findings of this study indicate that lake-bank filtration can contribute to removal of cyanobacteria and viruses, thus providing a method of pre-treatment of lake water used for drinking water.
This research was funded by the USGS Ecosystems Mission Area’s Environmental Health Program (Contaminant Biology and Toxic Substances Hydrology) and the Sonoma County Water Agency.
Below are other science projects associated with this project.
Toxins and Harmful Algal Blooms Science Team
Drinking Water and Wastewater Infrastructure Science Team
Algal and Other Environmental Toxins — Lawrence, Kansas
Nitrate Addition Enhances Arsenic Immobilization in Groundwater
Nutrients in Dust from the Sahara Desert cause Microbial Blooms on the East Coast of the United States
USGS Scientists Measure New Bacterial Nitrogen Removal Process in Groundwater
New Study on Cyanotoxins in Lakes and Reservoirs Provides Insights into Assessing Health Risks
Sewage-Contaminated Ground Water
U.S. Geological Survey Scientists Complete First Systematic Regional Survey of Algal Toxins in Streams of the Southeastern United States
Remote Sensing Provides a National View of Cyanobacteria Blooms
Potential Exposure to Bacteria and Viruses Weeks after Swine Manure Spill
Antibiotics in Groundwater Affect Natural Bacteria
- Overview
U.S. Geological Survey (USGS) scientists determined that the colmation layer (top 25 centimeters of lake sediments) was highly effective in removing cyanobacteria, viruses, and dissolved organic carbon during water passage through the lake bottom to aquifer sediments.
U.S. Geological Survey (USGS) scientists collecting water-quality samples from shallow groundwater under Ashumet Pond, Cape Cod, Massachusetts. Photo Credit: Denis R. LeBlanc, USGS River-bank filtration has proven to be a sustainable and cost-effective method of removing microorganisms and chemicals from surface water during filtration through bottom and aquifer sediments. Lakes can also be important locations for bank filtration operations. The biologically active layer of sediments immediately beneath the sediment/water interface, sometimes referred to as the colmation layer, is considered to be important for contaminant and carbon removal, although its specific role(s) in the elimination of human pathogens poses a lingering question.
In this study, scientists focused on the importance of the upper 25 centimeters of lake sediments in the removal of cyanobacteria, bacteriophages (viruses of bacteria), and dissolved organic carbon during natural bank filtration in lakes. This study was done at two shallow (0.5 meter deep), sandy, near-shore sites at the southern end of Ashumet Pond, a waste-impacted, kettle pond on Cape Cod, Massachusetts , that is subject to periodic blooms of cyanobacteria and continuously recharges a sole-source drinking-water aquifer. Cultured cyanobacteria (Synechococcus sp. IU625), its cyanophage (virus, AS-1), a coliphage (MS-2), and synthetic microspheres were injected into a pond water/groundwater interface and tracked as they passed through the colmation layer and underlying aquifer sediments.
Sources/Usage: Public Domain.Experimental setup for small-scale transport test designed to assess the effectiveness of the "colmation layer" at the bottom sediments of Ashumet Pond (Cape Cod, Massachusetts) for filtering out cyanobacteria and viruses. The green color in the collapsible bag containing the colloids and a bromide tracer is caused by the presence of microbial sized fluorescent microspheres that scientists added to act as colloidal tracers. Photo Credit: Denis R. LeBlanc, USGS Scientists determined that more than 99 percent of the cyanobacteria and bacteriophages and approximately 44 percent of the pond-dissolved organic carbon were removed in the colmation layer. Scientists determined that the low relative breakthrough of the bacteriophages occurred through a combination of sorptive-filtration and inactivation. Although the physicochemical and biological parameters controlling microbial removal in the colmation layer vary from site to site, there is evidence to indicate that cyanobacteria populations are largely removed within the top few centimeters of bottom sediments during lake-bank filtration.
Environmental Health Considerations
Lakes can contain large numbers of cyanobacteria that may produce harmful toxins, as well as viruses and high levels of dissolved organic carbon that can be of concern if the lakes are used as sources of drinking water. The findings of this study indicate that lake-bank filtration can contribute to removal of cyanobacteria and viruses, thus providing a method of pre-treatment of lake water used for drinking water.
This research was funded by the USGS Ecosystems Mission Area’s Environmental Health Program (Contaminant Biology and Toxic Substances Hydrology) and the Sonoma County Water Agency.
- Science
Below are other science projects associated with this project.
Filter Total Items: 13Toxins and Harmful Algal Blooms Science Team
The team develops advanced methods to study factors driving algal toxin production, how and where wildlife or humans are exposed to toxins, and ecotoxicology. That information is used to develop decision tools to understand if toxin exposure leads to adverse health effects in order to protect human and wildlife health.Drinking Water and Wastewater Infrastructure Science Team
The team studies toxicants and pathogens in water resources from their sources, through watersheds, aquifers, and infrastructure to human and wildlife exposures. That information is used to develop decision tools that protect human and wildlife health.Algal and Other Environmental Toxins — Lawrence, Kansas
About the Laboratory The Environmental Health Program collaborates with scientists at the Organic Geochemistry Research Laboratory (OGRL) in Lawrence, Kansas, to develop and employ targeted and non-targeted analytical methods for identification and quantitation of known and understudied algal/cyanobacterial toxins. The laboratory contructed in 2019 is a 2,500 square foot modern laboratory facility...Nitrate Addition Enhances Arsenic Immobilization in Groundwater
The addition of nitrate in a low oxygen groundwater resulted in the immobilization of naturally occurring dissolved arsenic and the conversion of nitrate to innocuous nitrogen gas.Nutrients in Dust from the Sahara Desert cause Microbial Blooms on the East Coast of the United States
Saharan dust nutrients, particularly iron, deposited episodically in tropical marine waters stimulate marine microbial bloom growth and change microbial community structure.USGS Scientists Measure New Bacterial Nitrogen Removal Process in Groundwater
For the first time, U.S. Geological Survey (USGS), Virginia Institute of Marine Science, and the University of Connecticut scientists have detected active anammox bacteria in groundwater.New Study on Cyanotoxins in Lakes and Reservoirs Provides Insights into Assessing Health Risks
Newly published study provides new evidence of the widespread occurrence of cyanotoxins in lakes and reservoirs of the United States and offers new insights into measures used for assessing potential recreational health risks.Sewage-Contaminated Ground Water
The USGS is investigating a wastewater plume in a shallow aquifer near Cape Cod, Massachusetts, to increase the understanding of the physical, chemical, and microbiological processes that affect the fate and transport of contaminants in groundwater.U.S. Geological Survey Scientists Complete First Systematic Regional Survey of Algal Toxins in Streams of the Southeastern United States
U.S. Geological Survey (USGS) scientists detected microcystin—an algal toxin—in 39 percent of 75 streams assessed in the southeastern United States. These results will inform and become part of a larger, systematic national survey of algal toxins in small streams of the United States.Remote Sensing Provides a National View of Cyanobacteria Blooms
Four Federal agencies, including the U.S. Geological Survey (USGS), are collaborating to transform satellite data into information managers can use to protect ecological and human health from freshwater contaminated by harmful algal blooms.Potential Exposure to Bacteria and Viruses Weeks after Swine Manure Spill
Manure spills may be an underappreciated pathway for livestock-derived contaminants to enter streams. Scientists from the U.S. Geological Survey (USGS) and Johns Hopkins Bloomberg School of Public Health studied an Iowa stream after the release of a large volume of swine manure (a manure spill). The scientists observed an increase in viruses and bacteria, which have the potential to cause human or...Antibiotics in Groundwater Affect Natural Bacteria
U.S. Geological Survey (USGS) scientists have documented adverse health effects on populations of native soil bacteria exposed to levels of the antibiotic (SMX) below those used to treat diseases (subtherapeutic). Because SMX has been found in environmental waters by many previous studies, the scientists conducted laboratory exposure experiments to determine the effect of SMX on native bacteria... - Publications