Christina River Basin Critical Zone Observatory post-doctoral researchers (L to R): Diana Karwan, Olesya Lazareva, and Carl Rosier. Not pictured: Audrey Sawyer.
Stroud™ Scientists at Work
Introducing Our Post-Doctoral Researchers’
“Fresh waters and the carbon they transport play a major role in the global cycling of greenhouse gases.” — Anthony Aufdenkampe, Associate Research Scientist, Stroud Water Research Center.
A Year in Review
2011 witnessed the completion of the second full year of the collaboration between Stroud Water Research Center and the University of Delaware on the Christina River Basin Critical Zone Observatory (CRB-CZO). The goal of the NSF-funded CZO is to increase both scientific understanding and public awareness of how the water, mineral, and carbon cycles interact in the critical zone (defined by scientists as “the portion of the planet from the treetops to the groundwater that sustains terrestrial life”) to affect global climate change.
The program’s accomplishments last year included:
- providing new corroboration for earlier studies by Anthony Aufdenkampe, who is the CRB-CZO’s co-principal investigator, and others indicating that rivers transport far more carbon than scientists had believed, most of which is either returned to the atmosphere as CO2 or buried in sediment;
- creating low-cost, open-source wireless sensor networks that have the potential to radically transform critical zone science;
- developing Web applications, such as WikiWatershed and Model My Watershed, as innovative resources for research, education and public outreach programs; and
- educating the public about the impact of land use on carbon cycling, water quality, and climate change through a series of workshops, lectures, publications, and programs for researchers, policymakers, teachers, students, and informal educators.
Last year also witnessed the most extensive use of post-doctoral researchers in Stroud Water Research Center’s 45-year history, as four newly minted Ph.D.s made significant contributions to the CZO project:
Diana Karwan, a hydrologist with a doctorate from Yale, has become known at the Center for something called “dial-a-pump.” Created in partnership with Steve Hicks and Dave Montgomery, the process enables Diana to collect water samples in a 55-gallon drum by literally dialing up an on-site pump from her cell phone and telling it to get to work pumping water into the barrel. She collects the water primarily during storms, which is when most sediment moves — and when it is most problematic for a human to be physically working in a stream. Diana requires huge volumes of water to extract the amount of sediment she needs to do a variety of chemical experiments that will enable her to track the movement of the sediment in the stream and the sources of those sediments. By comparing the stream samples with ones she has taken from a variety of landscapes — open fields, cropland, flood plains, urban sites, and forests — she can determine where the sediment came from. With the help of additional hydrologic and statistical models, she can investigate how sediments and organic particles react as they move through the stream. Understanding how streams process sediments — in lay terms, where the murkiness comes from in a stormy stream — has enormous implications for improving land-management practices, both to protect fresh water and to reduce carbon emissions to the atmosphere. “Water is the connector moving everything,” she said. “We need clean water, and I want to understand how streams process material as it moves through the stream network.”
After receiving her undergraduate degree in environmental geology from Lomonosov Moscow State University in 2002, Olesya Lazareva moved to the University of South Florida for graduate study on the release of arsenic from a limestone aquifer. Arsenic is an extremely carcinogenic metal, and its presence in drinking water has become a worldwide problem. In 2006 the U.S. Environmental Protection Agency drastically reduced the legal levels of arsenic in water, and Olesya’s Ph.D. research was part of a broader project to reclaim a phosphate mine and determine if a wetland built on the site could become a potential pre-treatment option for aquifer storage and recovery, as well as for the remediation of elevated levels of arsenic. Now she is applying what she learned in south Florida to a study of the biogeochemical transformation of iron and manganese (two other heavy metals) and carbon across a wide range of land uses in White Clay Creek watershed. Olesya works as part of a team of soil scientists, chemists, biologists, and hydrologists whose goal is to advance our understanding of how human activities affect the carbon cycle. Using the Center’s real-time monitoring sensors, which allow them to see “what’s really going on in the soil,” said Olesya, the research team hopes to integrate knowledge of the distinct but interrelated cycles of water, minerals, and carbon. Bringing together such a diversity of scientific disciplines in a single study has been very exciting, she said, for it has until now been “a major missing link in critical zone science.”
Carl Rosier brought his Ph.D. in soil microbiology and biochemistry from the University of Montana to learn more about how tiny organisms process carbon in the soil. In particular, he is studying what causes microorganisms to wear down mineral surfaces in the soil and what impact that has on carbon sequestration. Practices ranging from farming to development — and events as different as a raging storm and a falling tree — disrupt the soil and diminish its capacity to bind and hold carbon. One of the primary goals of the CRB-CZO is to determine what happens to that carbon and to quantify how much of it returns to the atmosphere as carbon dioxide. Carl believes that understanding how microbial communities in the soil respond to different land uses has important implications for climate change models. He is also looking at how different tree species process rainwater and what implications that might have for the soil processes he is analyzing. Beech trees, for example, behave like giant straws, channeling water down the surface of their trunks to their shallow roots. On the other hand, the rain drips from the leaves and branches of poplars, and the quantity and quality of the water reaching the ground below may have a significantly different impact on the soil’s microbial diversity. One of the attractions of this area for Carl is what he believes is its proximity to family in Pittsburgh — a concept that makes perfect sense if you used to live in Montana.
As the public’s obsession with pharmaceuticals in its drinking water made clear a few years ago, streams and rivers carry a lot of chemicals. The focus of Audrey Sawyer’s research is to understand what happens to chemicals as they move from the land to the stream and then down to the estuary and ultimately into the ocean. She has set up research sites at three very different settings: (1) a forested third-order tributary to White Clay Creek; (2) a tidal section of the creek just before it enters the Christina River above Wilmington; and (3) the river’s brackish estuary at Indian River Bay. The chemistry of the water varies at each site, as do the processes that drive the interactions between groundwater and surface water. It is those interactions that she is studying, particularly as they manifest themselves during large events: the great pulses of water that discharge into the stream during storms; the ebb and flow of the urban river in response to the tides; the run-off of chemical-rich groundwater from the surrounding shores directly into the bay; and the movement of the bay water through the estuary’s shallow sediment. “My goal is to understand how the tides, waves, and storms affect the flow of chemical contaminants on their journey through the watershed,” said Audrey. “Those processes can tell us a lot about the health of the entire system.” A hydrogeologist with a Ph.D. from the University of Texas, Audrey has come back to the area where she first learned to love the streams in which her parents taught her to fly fish as a child.
CZO: A National Program
The CRB-CZO is one of six projects across the country that together compose a huge multiyear, interdisciplinary effort funded by the National Science Foundation. The CZO work is focused on quantifying the impact that humans have on carbon sequestration across an entire watershed — from upland headwaters to the ocean. Its overarching goal is to create models that can predict how the critical zone will respond to changes in land use, water quality, and climate. A key component of the study is to understand the role that streams and rivers play in the transport and sequestration of carbon, something Stroud Water Research Center has been doing since 1967.