scientists at work

Diving into the Sandstorm

A blog post by Sean Sheldrake, an EPA scientific diver and frequent contributor to It All Starts with Science, was recently featured on the Smithsonian Institution’s Ocean Portal blog. We are reposting it again here for you to enjoy. 

By Sean Sheldrake

Ship with a large pipe off the side with a stream of sand coming out.

U.S. Army Corps of Engineers removing a sandbar off Virginia Beach, VA.
U.S. Army Corps of Engineers image

Diving can be a wild ride that evokes more than a little trepidation, especially in the Pacific Ocean’s famously big, cold waves. Waves that are otherwise fun for my weekend surfing can turn a scientific dive into a serious challenge. But then, diving to support the mission of the Environmental Protection Agency (EPA) can be full of surprises. At a seafloor survey site at the mouth of the Chetco River off the Oregon coast, waves transmit so much energy that divers can feel the swells nearly 80 feet down on the seafloor. As divers swim along the bottom, these swells often push them several feet forward, then “suck” them backward several feet.

Such natural water movements not only make diving difficult, but can also drastically alter the underwater terrain. Humans further these changes by digging up sand and sediment from the bottom of a river or ocean and depositing it elsewhere, a process known as dredging. Ports might dredge an area to clean up the seafloor, or make an area deep enough for large ships to navigate. Without it, sandbars would grow to such enormous heights that river entry would be worrisome to even the most experienced captains. Such large sandbars can wreck ships; one was nicknamed the “Graveyard of the Pacific” (PDF) in the early days of Columbia River navigation. And, on one beach I often surf, the wreck of the Peter Iredale remains as an eerie reminder to respect “the bar.”

EPA divers from Atlanta place this instrument in Charleston Harbor in order to monitor currents and better predict sand movement.

EPA divers placed this instrument to monitor currents and better predict sand movement. EPA image

But if you’re going to dig up a bunch of sand, you have to put it somewhere. EPA divers around the country evaluate dredge material disposal sites regularly, where ports deposit literally tons of sand into the ocean. How much? In 2013, more than eight million cubic yards of sediment will be removed from Oregon’s Columbia River alone. This, and many other dredging operations upriver, help move 42 million tons of cargo from Oregon, Washington, and Idaho farms to market each year with as few bumps as possible.

Placing dredged material from a river or harbor into the ocean is not necessarily a problem, as long as it’s a load that is small enough to not overwhelm the creatures that live there, like crabs or sea stars.  For example, if the load just adds several inches of sand to the area, crabs and sea stars can ‘hop’ up above that material. But if several feet were placed all at once, it’s likely that these critters would be buried. Sometimes, new sand can be beneficial to certain ecosystems, such as sandy beaches that have eroded. However, when sand is placed on rocky reefs or other sensitive environments, it can change the habitat. A rocky reef that gets buried in sand can no longer support its vital organisms, such as anemones and urchins.

That’s where the divers come in. EPA’s scientific divers visit and observe dredge deposit sites to make sure there is no damage to marine life on the seafloor—critters like worms, clams, crabs, and other tiny organisms that live in the bottom sediments—as ordered by the Marine Protection, Research, and Sanctuaries Act. To do this, we visit locations before and after dredged sand has been dumped to see if habitat has changed slightly, been dramatically transformed, or remained relatively unchanged since our last visit. For some areas, we might also use remote sensing techniques like sonar to quickly direct divers toward areas that need to be monitored more closely, like those sensitive rocky reefs. If we find the impacts to an area are too severe, the dredge disposal may be moved or future deposits will be stopped altogether in that location.

Because ports continually accumulate sediment—from human dredging, natural erosion and runoff—the cycle of dredging, dumping and observation happens on a regular basis, even twice a year for some sites. All to make sure that ecosystems stay healthy, ports can continue working, and that beachgoers and surfers like me can continue to enjoy them.

Read more about the latest EPA scientific diving.

About the AuthorSean Sheldrake is part of the Seattle EPA Dive unit, and 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.   

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

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Women’s History Month: Honoring Achievements in Science

By Maggie Sauerhage

Ecologist Rachel Carson helped shape how people see the natural world.

An ecologist who changed how an entire country looks at the natural world. The first woman to win a Nobel prize and the only one to win the prize in two separate fields. A computer scientist whose research helped launch rockets into space. A pioneer who realized the dangers of air pollution during the Industrial Revolution. A champion in protecting endangered species. And the first African-American woman to receive a degree in bacteriology.

Who are they? Rachel Carson. Marie Curie. Annie Easley. Mary Walton. Jane Goodall. Ruth Ella Moore.

These are just a few of many inspiring women who have impacted all of us with their innovations in science, engineering, conservation, medicine, and human health protection. They have inspired generations of scientists, engineers, trailblazers, women, and men to find a place where they can make their own impact, no matter how small, in comparison to these great achievements.

March is Women’s History Month, and this year’s theme is Women Inspiring Innovation through Imagination.

In honor of women, both past and present, who have changed all of our lives for the better through their work protecting human health and the environment, this month we are profiling EPA women scientists and engineers who are striving to make the planet a safer, cleaner, and more sustainable place to live. They share their research, how they discovered their passion for science or engineering, and give advice for anyone who is interested in pursuing their dreams.

We’ll add more profiles throughout the month, so please check back as the next four weeks roll on and maybe you, too, will find a passion for environmental and human health research!

About the Author: Maggie Sauerhage is part of the communications team in EPA’s Office of Research and Development.

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

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Scientist at Work: Mehdi S. Hazari, Ph.D.

EPA scientist Mehdi S. Hazari is a recipient of the 2011 Presidential Early Career Award for Scientists and Engineers. The award is the highest honor bestowed by the U.S. government on outstanding science and engineering professionals in the early stages of their independent research careers.

Dr. Mehdi’s award recognizes his work demonstrating how breathing in low levels of air pollutants, such as particulate matter and ground level ozone, can increase people’s susceptibility to heart attacks and other cardiac events. His research is also receiving international recognition and is under consideration for inclusion in the update of worldwide standards. Read more about his research in the previous blog post, “You Don’t Need Oz to Give You a Healthy Heart.”

What do you like most about your research?

The opportunity to try something new in the laboratory, but more broadly, the direct impact it can potentially have on protecting human health and the environment.

How does your science matter?

Despite the fact that we are learning quite a bit about how air pollution is directly detrimental to the body, particularly when adverse symptoms are observed, we still need to better identify the latent (hidden) effects of exposure. This is especially true of low concentration exposures to air pollution during which no direct responses may be observed.

My work demonstrates that even in the absence of obvious “symptoms,” air pollution might have the potential to cause subtle internal body changes that increase the risk of triggering something bad happening to your heart, such as an arrhythmia. We all know that exercise is generally a good thing, but its hard physical activity that does create mild to moderate stress on the body. Add high air pollution levels into the mix on a hot day, and instead of getting healthier, that stress might be the trigger for an adverse response. Doing that same activity in a healthy air environment might not. And in the case of stress, it doesn’t have to be just air pollution. The triggers might be any stressful stimuli.

Again, I think my science matters because of the direct impact it can potentially have on protecting human health and the environment.

If you could have dinner with any scientist past or present, who would it be and what would you like to ask them about?

William Harvey—the English physician and physiologist who completely described the cardiovascular system.

Continue reading Dr. Hazari’s interview here.

Read more Scientist at Work profiles here.

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

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Scientist at Work: Dr. Swinburne A.J. Augustine


Dr. Swinburne A. J. Augustine (Jason), Ph.D. is an EPA Research Microbiologist/Immunologist. His research is aimed at developing and applying rapid, cost-effective and multiplexed immunoassays to determine and/or measure human exposures to environmental pathogens using antibodies in human saliva as biomarkers of exposure. He is a member of the American Association of Immunologists and the American Society for Microbiology. Dr. Augustine also served in the U.S. Army.

How does your science matter?

Every day, we are exposed to a myriad of harmful environmental (airborne, food-borne, and waterborne) organisms. Sometimes they make us sick but more often than not, our immune system protects us from these pathogens. My research uses antibodies in human saliva to measure levels of exposure to environmental pathogens. Epidemiologists use this data to determine if the levels of exposure are high enough to be harmful to humans. This information helps inform Agency decisions on what measures should be taken to protect human health. My research partners and I are analyzing multiple pathogens simultaneously, which saves EPA time and money.

If you could have dinner with any scientist, past or present, who would it be and what would you like to ask them about?

I’d like to have dinner with Antonie Van Leeuwenhoek. I’d ask him what inspired him to invent the microscope and what is the secret to its construction?

What do you like most about your research?

I really enjoy the collaboration with a range of scientists including epidemiologists, virologists, microbiologists, immunologists and engineers. We work together to tackle tough water quality, sustainability and exposure questions in order to ensure the protection of public health and the environment.

To keep reading about Dr. Augustine, click here.

For more Scientists at Work profiles, click here.

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

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Scientist at Work: Interview with Thomas Knudsen

Dr. Tom Knudsen is a developmental systems biologist at EPA’s Center for Computational Toxicology. His research focuses on developing predictive models of developmental toxicity, building and testing sophisticated computer models such as the Virtual Embryo Project. This effort explores the potential for chemicals to disrupt prenatal development—one of the most important lifestages.

In addition to his research at EPA, Dr. Knudsen is an Adjunct Professor at the University of Louisville, Editor-in-Chief of the scientific journal Reproductive Toxicology, and Past-President of the Teratology Society.

Before joining EPA, he was Professor at the University of Louisville.

How does your science matter?

I am part of an exciting effort to develop new ways to explore development toxicology and prioritize the testing of chemicals using vast amounts of data and biological knowledge, powerful computers, sophisticated computer models and very large databases. Instead of the conventional approach to developmental toxicology, which over the past 50 years or so has relied on tests conducted on pregnant lab animals, we are developing virtual models that are both faster and less expensive.

For example, in the Virtual Embryo project we are using a suite of screening models that look at the interactions of various chemicals with the complex biology of a developing embryo. We think that these models and tools will be a new way of asking questions about how a pregnant woman’s exposure to chemicals in the environment might result in a risk to development.

Our work will help protect human health, greatly increase the number of chemicals we can screen quickly, and reduce costs all at the same time. So I guess it really does matter.

What do you like most about your research?

Most days I feel like I have the best job in the country!

The team that I work with consists of bright and exceptionally talented scientists, among them more than a half dozen outstanding young scientists and post-doctoral fellows. As a like-minded team, we strive to unravel complexity in a biological system such as the embryo.

I really enjoy the many opportunities for productive collaboration here at EPA. The opportunity to conceptualize the Virtual Embryo Project and see it grow and evolve has been most gratifying, not only because of the innovative science that it allows, but also because of the opportunities that it presents for professional development of young scientists.

Click here to keep reading Thomas’s interview.

To read more Scientists at Work interviews, click here.

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.