Nutrient pollution

Visualizing Our Waters

By Dustin Renwick

“Data mining” conjures images of someone clanking away with a pick-axe at a mountain of 1s and 0s. But the sentiment isn’t far off. Heaps of data are useless without understanding the relevance and context within the larger picture.

Graphic showing swirling water with  words "Visualizing Nutrients" belowNutrient pollution is one the most expensive problems associated with aquatic environments. Excess nitrogen and phosphorus in water affects human health and the sustainability of ecosystems. Green water means increased risks for harmful algal blooms, hypoxia, and other nutrient-related water quality issues.

To help provide a clearer picture of this problem, 29 teams are now developing and testing affordable, real-time technologies for measuring nitrogen and phosphorus in water as part of our Nutrient Sensor Challenge. Yet those sensors will produce more data, ever increasing our need to make the numbers understandable to a larger audience beyond the scientists who study the measurements.

Today, with the U.S. Geological Survey and Blue Legacy International (a nonprofit focused on water), EPA launched Visualizing Nutrients. This innovation competition includes $15,000 in cash prizes.

We want talented designers, coders, data scientists, sensor experts, and anyone interested in complex problems to analyze and organize existing nitrogen and phosphorus water pollution data.

The best submissions will transform publicly available, open government data sets into dynamic visual representations that reveal insights, trends, and relationships. First Place will take home $10,000 and a People’s Choice Award will win $5,000.

Visit the competition website to submit a solution. The deadline is 11:59 p.m. on June 8, 2015.

This is one of many efforts by the broader Challenging Nutrients Coalition to bring innovative ideas and solutions to bear on the problem of nutrient pollution. The group consists of federal agencies, universities, and nonprofits.

About the Author: Dustin Renwick works in conjunction with the Innovation Team in EPA’s Office of Research and Development.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

Please share this post. However, please don't change the title or the content. If you do make changes, don't attribute the edited title or content to EPA or the author.

Farmers Using Special Crops in Holtwood, PA to Protect Soil & Help Their Farms Thrive

By Kate Pinkerton and Erika Larsen

It is hard to imagine anything growing in fields during winter, but last fall, we visited a farm in Pennsylvania that was covered in thriving, green crops. This farm showcases crop research and water quality conservation practices on agricultural lands. One of its practices is planting “cover crops” – or crops planted specifically to help replenish the soil and protect our waters outside of the typical farming season.

We are two coworkers in the Oak Ridge Institute of Science and Education (ORISE) program in the EPA Office of Wetlands, Oceans, and Watersheds. We come from two different backgrounds – agriculture and water quality – to help farmers ensure that nutrients like phosphorus and nitrogen stay on the farm where they help crops grow, rather than getting washed into our rivers and streams where they can build up and become nutrient pollution, or the excess of the vital nutrients phosphorus and nitrogen.

Farmers plant cover crops to improve and protect their soil and keep these nutrients from washing away in runoff, especially when they’re not growing crops they can sell. A variety of plants can be used as cover crops, including grasses, grains, legumes or broadleaf plants. By planting cover crops, farmers help the environment and themselves by increasing their soil’s health and water retention, potentially increasing crop yields and creating more habitat for wildlife.

The 200-acre farm we visited in Holtwood, PA – owned by Steve and Cheri Groff – produces corn, alfalfa, soybeans, broccoli, tomatoes, peppers and pumpkins. Annual cover crops help the farm be productive by maintaining a permanent cover on the soil surface at all times. During the tour, we talked with the Groffs about how cover crops store nutrients for the next crop and impact yields, what cover crop mixtures to use and the benefits of having multiple species. We also watched demonstrations on cover crop rooting depths, and how cover crops help soil health and water/nutrient cycling.

We were joined by other local farmers, agricultural conservation NGO staff, and representatives from other government agencies, including USDA’s Natural Resources Conservation Service and Risk Management Agency. Rob Myers, Regional Director of the North Central Sustainable Agriculture Research and Education (SARE) program, said, “When you compare fields that are normally bare in the fall with a cover crop field capturing sunlight and protecting soil and water, it’s a pretty striking comparison.”

We enjoyed checking out the Groffs’ farm and seeing the wonderful progress that has been made on cover crop use and research, and we’re excited by the opportunities to collaborate to improve soil health and water quality. We hope to see this field continue to grow!
To learn more about cover crops please visit our website: http://water.epa.gov/polwaste/nps/agriculture/covercrops.cfm.

 

ORISE program participant Kate Pinkerton, Chief of the Rural Branch in EPA’s Office of Wastewater Management Allison Wiedeman, and ORISE program participant Erika Larsen stand in front of a cover crop research plot at Steve and Cheri Groff’s farm in Holtwood, PA.

ORISE program participant Kate Pinkerton, Chief of the Rural Branch in EPA’s Office of Wastewater Management Allison Wiedeman, and ORISE program participant Erika Larsen stand in front of a cover crop research plot at Steve and Cheri Groff’s farm in Holtwood, PA.

 

About the authors:

Erika Larsen is an Oak Ridge Institute for Science and Education (ORISE) research participant in the Nonpoint Source Control Branch in EPA’s Office of Wetlands, Oceans, and Watersheds. Erika is a soil scientist from Florida and currently works on agriculture and water quality issues.

Kate Pinkerton is an Oak Ridge Institute for Science and Education (ORISE) program participant on the Hypoxia Team in EPA’s Office of Wetlands, Oceans, and Watersheds. Kate is originally from Kentucky and studied environmental science at American University. She currently works on nutrient pollution and hypoxia issues in the Mississippi River Basin and the Gulf of Mexico.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action, and EPA does not verify the accuracy or science of the contents of the blog.

Please share this post. However, please don't change the title or the content. If you do make changes, don't attribute the edited title or content to EPA or the author.

When Green Goes Bad

Flyer banner for "When Green Goes Bad" webinar

By Lahne Mattas-Curry

When you think about the environment, what color comes to mind? Green, right? Because in everything we know in the environment “Green is Good.”

And while that is very often true, in the case of lakes and ponds that suddenly go green, it is most likely the result of an algae bloom, which, increasingly, contain many harmful cyanobacteria.  Also known as “blue-green algae,” some species of these tiny, photosynthetic aquatic organisms produce toxins. The impacts of these harmful algal blooms are widespread and often not good. Not good at all.

From acute adverse human health impacts such as respiratory and gastrointestinal problems (yuck) to known deaths of animals (keep the family dog out of green water, please!!), blooms like these are becoming a more frequent occurrence and are having greater impacts.

To better understand how algal blooms impact human health, identify the toxicity of cyanobacteria, predict the probability of bloom occurrences, and share this information broadly, our researchers have been working on a research project focused this topic since 2012.

The researchers involved in the project will be sharing what they have learned during a webinar on Wednesday, June 25 from 12:00 to 1:00pm as part of EPA’s Water Research Webinar Series.

We hope you will join them to hear an overview of the breadth of their algae bloom research, and learn details about ecological modeling they conducted on cyanobacterial blooms in U.S. lakes. They will explain how they embraced the concept of “Open Science”—the movement to make scientific research and data accessible to the public.

And if that’s not enough, they will also be available for a twitter chat on June 26 from 2:00pm to 3:00pm. You can submit questions now by using #greenwater or you can wait until the day of the chat. Please follow us @EPAresearch.

To register for the webinar, please send an email to sswr@epa.org with your name, title, organization and contact information.

Meet our Scientists

Jeff Hollister, Ph.D.
EPA research ecologist Jeff Hollister received his Ph.D. in Environmental Science from the University of Rhode Island. His past experience is in applications of geospatial technologies to environmental research and broad-scale environmental monitoring, modeling, and assessment. His current research focuses on how nutrients drive the risk of cyanobacterial blooms in lakes and ponds.

Betty Kreakie, Ph.D.
EPA research ecologist Betty Kreakie earned her Ph.D. in integrative biology from the University of Texas. Her work focuses on the development of spatially-explicit landscape level models that predict how biological populations and communities will respond to human-caused influences, such as nutrient and contaminant pollution, climate change, and habitat conversion.

Bryan Milstead, Ph.D.
EPA post-doctoral research ecologist Bryan Milstead received his Ph.D. from Northern Illinois University for work on small mammal population dynamics in Chile. Before coming to EPA, he worked for the U.S. National Park Service and for the Charles Darwin Foundation for the Galapagos Islands. His current work focuses on understanding how nutrient over-enrichment affects the aesthetic quality and risk of cyanobacteria blooms in lakes.

About the Author: Lahne Mattas-Curry communicates the many cool things happening in water science for EPA and hates #greenwater. She urges everyone to think twice about what fertilizers they use on their lawn and encourages pet owners to “pick up the poop” to reduce nutrient pollution.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

Please share this post. However, please don't change the title or the content. If you do make changes, don't attribute the edited title or content to EPA or the author.

SPARROWs, Lakes, and Nutrients?

By Jeff Hollister

Dock extending into a lake with forested background.Based on the title above, you probably think I don’t know what I am talking about. I mean really, what do sparrows, lakes, and nutrients have in common? In this case, a lot. So much so, an inter-agency team of EPA researchers in Narragansett RI, and a colleague from the U.S. Geological Survey (USGS) in New Hampshire have been working together to better understand how these three seemingly disparate concepts can be linked together. Some of the results of this work are outlined in a recent publication in the Open Access journal, PLos One

The sparrow I am referring to isn’t small and feathered, it is a model developed and refined by the USGS. Since the late 1990’s, USGS has been developing SPARROW models which have been widely used to understand and predict the total amount of nutrients (among other materials) that streams are exposed to over the long-term. This is known as “nutrient load.” The models are important because they provide a picture over a very large extent of where nutrients might be relatively high.

However, when it comes to lakes, SPARROW doesn’t directly provide the information we need. For our research on lakes, we need reasonable estimates of the quantity of nutrients in a given volume of water (i.e., nitrogen and phosphorus concentration), not long term nutrient load for the year. This is important, because the higher the nutrient concentrations at any given time, the greater the chance of triggering algal blooms—and more blooms mean a greater probability of toxins released by algae reaching unhealthy levels.

In order to better estimate the nutrient concentrations, we needed to use the SPARROW model for total load, but also account for the differences between load and concentration. Our solution: combining field data, data on lake volume and the SPARROW Model.

In our paper “Estimating Summer Nutrient Concentrations in Northeastern Lakes from SPARROW Load Predictions and Modeled Lake Depth and Volume,” recently published in PLoS One, we describe how we combined modeling information from SPARROW, summertime nutrient concentrations collected during EPA’s 2007 National Lakes Assessment, and estimated lake volume (see this and this for more).

The end result of this effort is better predictions, by an average of 18.7% and 19.0% for nitrogen and phosphorus, respectively.

What is the meaning of this in terms of our environment, and importantly, the potential human health impacts? If we are able to better predict concentrations of nutrients it will hopefully also improve our ability to know where and when we might expect to see harmful algal blooms, specifically harmful cyanobacterial algal blooms. Cyanobacteria have been associated with many human health issues, from gastro-intestinal problems, to skin rash, and even a hypothesized association with Lou Gehrig’s Disease (for example, see this). So, in short, better predictions of nutrients, will, in the long run, improve our understanding of cyanobacteria and hopefully reduce the public’s exposure to a potential threat to health.

About the author: Jeff Hollister, a co-author on the study outlined in this blog post, is a research ecologist with an interest in landscape ecology, Geographic Information Systems (GIS), the statistical language R, and open science. The focus of Jeff’s work is to develop computational and statistics tools to help with the cyanobacteria groups research efforts. Jeff is also an outspoken advocate for open science and open access among his colleagues.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

Please share this post. However, please don't change the title or the content. If you do make changes, don't attribute the edited title or content to EPA or the author.

Challenging Nutrients: EPA and Partners Launch New Ideation Prize

Effects from excess nutrients in American waterways cost the country more than $2 billion each year.

Activities of daily modern life add small amounts of the nutrients nitrogen and phosphorus to our lakes, rivers and estuaries, either directly or indirectly.

We all contribute to the widespread problem. Runoff from our suburban lawns, city streets and rural fields is just one of many ways we introduce more nutrients into the environment.

The partnership for this challenge currently includes: - White House Office of Science and Technology Policy - U.S. Environmental Protection Agency - U.S. Department of Agriculture - National Oceanic and Atmospheric Administration  - U.S. Geological Survey - Tulane University - Everglades Foundation

The partnership for this challenge currently includes:
– White House Office of Science and Technology Policy
– U.S. Environmental Protection Agency
– U.S. Department of Agriculture
– National Oceanic and Atmospheric Administration
– U.S. Geological Survey
– Tulane University
– Everglades Foundation

These excess nutrients end up in our waterways and fuel algae growth that exceeds healthy ecosystem limits. In turn, algal blooms can contaminate drinking water, kill aquatic species and negatively affect water-based recreation and tourism.

A partnership of federal agencies and stakeholders has announced a new prize competition to collect innovative ideas for addressing nutrient overloads.

The challenge aims to identify next-generation solutions from across the world that can help with excess nutrient reduction, mediation and elimination. The total payout will be $15,000, with no award smaller than $5,000. Proposals can range from completely developed ideas to exploratory research projects.

Ideas will be judged on a range of criteria, including technical feasibility and strategic plans for user adoption. Additionally, the challenge entries will inform the partnership members’ broader commitment and vision to find new ways to approach this decades-long problem.

Submit your idea today!

About the Author: Dustin Renwick works as part of the innovation team in the EPA Office of Research and Development.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

Please share this post. However, please don't change the title or the content. If you do make changes, don't attribute the edited title or content to EPA or the author.

Join us for a nutrient Twitter chat today at 2:00 pm (ET)!

Questions and AnswersReminder: Join us for a Twitter chat today at 2:00 pm (ET)!
Got questions about how nutrient pollution affects our water? Join EPA scientist Anne Rea and other Agency experts today at 2:00 pm (ET).

Use #waterchat to ask a question or participate.

To get you started and introduce you to Anne, we’ve asked her to answer a few questions.

What is your educational background?
I have a Ph.D. in Environmental Health Sciences from the University of Michigan. I studied the biogeochemical cycling of mercury and trace elements in forested ecosystems. Since little work existed in the mercury realm, most of the literature and experts I worked with focused on nitrogen pollution.

How did you become interested in nutrient pollution?
After joining EPA, I wanted to work on the ecological side of things (versus human health) and spent several years doing ecological risk assessments. I then led a joint review of two air pollutants, nitrogen dioxide and sulfur dioxide, for the National Ambient Air Quality Standards. This was the first time two pollutants were reviewed together, and the first time a “secondary” (public welfare) standard was separated from the “primary” standard (human health effects). I’ve always worked on multi-pollutant, multi-media problems, so was uniquely suited to lead the risk assessment for that review.

What’s the most interesting thing you have learned trying to solve this problem?
The dedication and commitment of staff across EPA is amazing. This is one problem the Agency is uniquely suited to solving from a scientific and regulatory perspective—but we can only do it together—across offices, regions and research programs in the Agency, and in collaboration with the states and other federal partners.

How can technology and innovation help solve the problem?
We’ve struggled to solve this problem for more than 40 years, and I think as an Agency we’ve made some progress. As the world’s population increases, there is a demand for increased food production and increased energy use—all of which releases nitrogen (and sometimes phosphorus, sulfur, and carbon) into the environment.

We are working across the Federal government to develop a ‘nutrients challenge’ which will challenge teams globally to come up with innovative ideas to reduce nutrients—either from the emissions source or from the waste stream.

We know we can’t solve nutrient pollution alone. What other federal agencies are we partnering with?
We are working with the National Oceanic and Atmospheric Administration (NOAA) the U.S. Geologic Survey (USGS), the U.S. Department of Agriculture (USDA) the U.S. Fish and Wildlife Service (FWS), the National Park Service (NPS), and others, through jointly funded research, collaborations, cooperative agreements, etc. We work hard to share and use each others data and models as we work collectively to make an impact on nutrient pollution for the country.

Join us at 2:00 pm (ET) to Learn More!
Got more questions? Want to learn more? Don’t forget to join us for a Twitter chat today at 2 pm (ET). Use #waterchat to ask a question or participate. Not on Twitter but have a question? Please add it to the comments section below.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

Please share this post. However, please don't change the title or the content. If you do make changes, don't attribute the edited title or content to EPA or the author.

Diving into Nutrients: How much is too much?

By Sean Sheldrake

An EPA diver kept isolated from contaminants.

An EPA diver kept isolated from contaminants.

There’s a nutrient “problem”?

Did you know nutrient pollution, primarily in the form of too much nitrogen and phosphorus, is one of the nation’s most widespread, costly and challenging environmental problems?  Some 16,000 waterways are impaired, and 78 percent of assessed coastal waters suffer from nutrient pollution, affecting water used for drinking, fishing, swimming and other recreational purposes.  These impacts also threaten tourism, home and property values and public health.

Nitrogen and phosphorous are food for some plants, like algae, and too much can spark a large algal bloom that can end up consuming all the dissolved oxygen in a waterway, causing fish to be starved for that critical gasp of O2.  Fish die-offs are common with extreme nutrient problems.

Where does it come from?

Excessive nitrogen and phosphorus are often the result of human activities. Primary sources include agriculture (manure, excess fertilizer and soil erosion), inadequately treated wastewater, stormwater runoff, air pollution from burning fossil fuels and—us! Huh? Whenever we do things around the house that add nitrogen and phosphorus to the local watershed we are part of the problem. That can include not cleaning up after your dog, using too much fertilizer on the lawn or garden, or washing your car on the driveway (most soaps contain nutrients).

How can I help?

Washington Department of Ecology Image.

Washington Department of Ecology Image.

The good news is that since we are all part of the problem, we can all be part of the solution.

Bag the dog waste, apply fertilizer according to the label (or better yet, switch to using some backyard compost!) and park your car on the lawn instead of the driveway when you wash it, or go to a carwash. We can really make a dent in the problem.

How about a little science to help out?

But it’s not all up to individuals alone. EPA scientists are working on solutions, too.

EPA divers help deploy and retrieve scientific instruments, such as Acoustic Doppler Current Profilers (ADCPs), to help study nutrient pollution.  For example, in one project in Puget Sound we deployed ADCPs to collect information on water flow, a critical first step that EPA computer modelers use to calculate the level of nutrients a water body can tolerate.  Ensuring the proper placement for data collection is paramount for data quality.

EPA diver deploys an ADCP.

EPA diver deploys an ADCP.

Getting into the water can be a challenge though!  Divers may have to upgrade to protective equipment and do a decontamination wash after the dive to ensure the safety of each diver getting in the water to collect data.

Read more about the latest in EPA scientific diving at facebook.com/EPADivers.

 

About the AuthorSean Sheldrake is part of the Seattle EPA Dive unit and is also a project manager working on the Portland Harbor cleanup in Oregon.  He serves on the EPA diving safety board, responsible for setting EPA diving policy requirements.  

Join us for a Twitter Chat to Learn More!
Got questions? Want to learn more? Join us for a Twitter chat this Thursday (July 18, 2013) at 2 pm ET on nutrient pollution and harmful algal blooms. Use #waterchat to ask a question or participate. Not on Twitter but have a question? Please add it to the comments section below. 

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

Please share this post. However, please don't change the title or the content. If you do make changes, don't attribute the edited title or content to EPA or the author.

Around the Water Cooler: American Wetlands Month—and Your Dinner

By Lahne Mattas-Curry

ShrimpboatBayou country, located along the Gulf of Mexico, specifically Louisiana, has historically shaped the culture and the economy of the region. The Bayou—otherwise known as wetlands, swamps, or bogs—is an economic resource supporting commercial and sport fishing, hunting, recreation and agriculture.

Remember the Bubba Gump Shrimp Company? The shrimping business the fictional Forrest Gump started (and since inspired a real restaurant chain). Without clean and healthy wetlands, there’s no shrimping business, not in the movies and not in real life.

This month is American Wetlands Month and EPA is acknowledging the extensive benefits—or “ecosystem services”—that wetlands provide. From trapping floodwaters and recharging groundwater supplies to removing pollution and providing fish and wildlife habitat, wetlands improve water quality in nearby rivers, streams and lakes and even serve as a natural filter for our drinking water. They are the “kidneys” of our hydrologic cycle.

In Bayou Country, wetlands provide nearly all of the commercial catch and half the recreational harvest of fish and shellfish. They are extremely valuable to the region’s economy. Wetlands in the region provide the habitat for birds, alligators and crocodiles, muskrat, beaver, mink and a whole bunch of other important critters.

EPA researchers all over the country are looking at different ways to keep our wetlands clean and healthy. From nutrient pollution research and water quality research to buffers around rivers and stream habitat (“riparian zones”) and other green infrastructure efforts, scientists are ensuring that our wetlands can continue to do their work – providing a habitat, filtering out pollution, and supporting our economy.

This month, wherever you sit down to enjoy all the shrimp and seafood you can eat, remember that without healthy and clean wetlands, none of that would be possible.

For more information on how EPA scientists monitor and assess our wetlands, read here.

About the Author: Lahne Mattas-Curry loves clean water, healthy beaches and great seafood. A regular contributor to EPA’s It All Starts with Science blog, she helps communicate the great science in the Agency’s Safe and Sustainable Water Resources Program.

 

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

Please share this post. However, please don't change the title or the content. If you do make changes, don't attribute the edited title or content to EPA or the author.

Around the Water Cooler: Watersheds and Climate Change

To celebrate Earth Day, all this week and into next we will be highlighting EPA climate change research with Science Matters feature articles. Today’s “Around the Water Cooler” addition illustrates the connection between climate change and water.

Climate Change and Watersheds: Exploring the Links
EPA researchers are using climate models and watershed simulations to better understand how climate change will affect streams and rivers.

A warming climate threatens hotter summers and more extreme storms. We know we may need to upgrade our air conditioning systems and make emergency preparedness kits, but aside from temperatures and storms, what are other ways we will be affected by climate change?

Map showing the 20 watersheds EPA researchers studied. Click on the image for a large version.

EPA water scientists and their partners are studying how climate change may affect watersheds—the network of rivers and streams that feed into larger water bodies such as big rivers, lakes, and oceans. A recent EPA report, referred to as the 20 Watersheds Report, combines climate change models and watershed simulations to develop a better understanding of what changes to streams and rivers we might expect over the next several decades.

“A key thing that’s unique about this work is the scope; we applied a consistent set of methods and models to 20 large watersheds throughout the nation,” says lead scientist Tom Johnson.

Johnson’s team of researchers used different climate change scenarios to model changes in streamflow volume and water quality in the 20 chosen watersheds.

“Climate can be defined loosely as average weather,” Johnson explains. “Climate change scenarios describe potential future changes in climate, like temperature or precipitation.”

For a given climate change scenario, watershed simulations were used to determine changes in streamflow (the actual volume of water running through the streams) and in nutrient and sediment pollution levels.

In addition to climate change scenarios, researchers also took into account urban and residential land development scenarios in their watershed simulations. The ways people use and alter the land (such as building roadways, parking lots, etc) will also have an impact on water resources. The land development scenarios used were based on projected changes in population and housing density in the study watersheds.

Research results show a great variety in watershed responses to climate and urban development scenarios in different parts of the country. Generally, simulations suggest certain trends for streamflow: that flow amount decreases in the Rockies and interior southwest, but increases in the northeast. Results also show higher peaks in streamflow that can increase stream bank erosion and sediment transport, as well as potentially increase nutrient pollutants. Overall, the research shows that the potential changes in streamflow and water quality response in many areas could be very large.

“This information can be used by water managers to better understand if and how things like water quality and aquatic ecosystems might be vulnerable, and to help guide the development of response strategies for managing any potential risk,” says Johnson.

For example, where water is suggested to be scarce, managers can plan alternative water supply methods; where water is expected to become highly polluted from nutrients and sediment, managers can take action now to limit the actual impact of these pollutants on the water resource.

The findings of EPA’s 20 Watersheds Report will help water and resource managers recognize the changing conditions of streams and rivers and identify any future conditions that may need addressing.

Learn More

EPA Climate Change Research

EPA Water and Climate Research

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

Please share this post. However, please don't change the title or the content. If you do make changes, don't attribute the edited title or content to EPA or the author.

Discovering Silica Cycling

By Joanna Carey

Rivers draining more forested watersheds contain significantly less silica than those draining more developed watersheds.

I am standing, engrossed in quiet, on a wooden bridge in Northern Massachusetts, with a perfect view of the Ipswich River.  I can see it meander once before it eventually opens up to form a babbling riffle. This river is alive, performing complicated metabolic processes as the water moves downstream.

Thanks to my EPA Science To Achieve Results (STAR) Graduate Research Fellowship, I went to this bridge (among others) weekly for a year, sampling the river for nutrients. While filtering my water samples here, people walking by would often ask, ‘how is the river doing?’

Before answering, I would hesitate; it turns out this is a complicated question!

From a human health perspective, most of the rivers I studied were in fine shape (thanks to the Clean Water Act and EPA), meaning that people could swim in the river without getting sick. However, other aspects of the river condition could use improvement.

Human activities, such as wastewater discharge, use of fertilizers, and fossil fuel combustion, are increasing the amount of nutrients flowing into rivers, which can spark excess algal growth and other negative repercussions on the entire ecosystem.

As an EPA STAR Fellow, I had the opportunity to be one of the first in the world to examine how watershed land use impacts the amount of silica in the rivers. Silica, or SiO2, is a required nutrient for diatoms, a common type of phytoplankton (tiny photosynthetic organisms) in temperate waters.

Why is the amount of silica in the rivers important?

Well, it all goes back to the fact that rivers supply over 80% of the silica that’s found in marine waters. And the amount of silica directly controls the amount and type of phytoplankton that grow in the ocean. Because phytoplankton makes up the base of the marine food chain, their type and abundance directly impacts organisms higher up on the food chain, such as commercial fisheries.

My research resulted in the discovery that land use type is indeed an important driver of the amount of silica in rivers.

I found that rivers draining more forested watersheds contain significantly less silica than those draining more developed watershed, which may be because of the large amount of silica taken up by land plants. It appears that lack of vegetation in urbanized landscapes results in more silica entering river systems. While more silica in rivers is not a bad thing, the research highlights a previously unrecognized way in which human actions are altering the environment.

For the last three years, I have been honored to be an EPA STAR Fellow. The award not only allowed me to perform the research of my dreams, but highlighted for me the importance of these fellowships for training the next generation of scientists. Thanks to the EPA, I can now count myself among the experts in aquatic biogeochemistry!

About the Author: Joanna Carey, a former STAR Fellow, is currently an ORISE post-doctoral fellow with the EPA Atlantic Ecology Division in Narragansett, RI studying the impact of oysters on nitrogen cycling in Southern New England.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

Please share this post. However, please don't change the title or the content. If you do make changes, don't attribute the edited title or content to EPA or the author.