To the untrained eye, the verdant woods and babbling streams of White Clay Creek State Park in the northwestern corner of Delaware may look more pristine than most landscapes along the heavily populated Mid-Atlantic coast.
But the careful observer can find the telltale signs of past generations: abandoned roadbeds, traces of dams and millraces, and crumbling stone foundations are scattered throughout the park, testaments to 300 years of settlement, agriculture and industry.
The park is now more heavily forested than it was 100 years ago, and White Clay Creek has been designated a National Wild and Scenic River, but human activities such as forestry and construction have left behind a lasting imprint.
The state park is just one small section of the 565-square-mile Christina River Basin, which includes five counties and 60 municipalities in Delaware, Pennsylvania and Maryland and encompasses Brandywine Creek, White Clay Creek, Red Clay Creek and the Christina River and their watersheds. Land use within the basin ranges from more pristine areas, to second-growth forests, farm fields, suburban settings and highly industrialized and urbanized areas.
The Christina River Basin is now a living laboratory, one of six areas in the nation designated by the National Science Foundation as a “Critical Zone Observatory.” In 2009, NSF awarded a multidisciplinary team of scientists from the University of Delaware and Stroud Water Research Center in Avondale, Pa., a five-year grant to study the basin. The $4.3-million grant was funded as part of the American Recovery and Reinvestment Act.
Scientists define the “critical zone” as the portion of the planet from the treetops to the groundwater that sustains terrestrial life. Within this zone, chemical elements that are the building blocks of life — such as carbon, nitrogen and oxygen — circulate at various rates between “storage pools” in the soil, water, atmosphere and living organisms.
Carbon sparks particular interest among scientists since carbon-based molecules serve as the “batteries” that store energy from the sun for use by organisms. In addition, warming of the global climate has been attributed to the transfer of carbon from terrestrial and living storage pools to the atmosphere in the form of greenhouse gases such as carbon dioxide and methane.
Members of the CZO team, including three postdoctoral researchers, eight graduate students and more than a dozen undergraduate students at UD and Stroud Water Research Center, are working to determine how, and how rapidly, soil erosion and sediment transport through rivers impact the exchange of carbon between the land and the atmosphere, and thus affect climate.
Factors influencing carbon cycling range from the chemical and physical processes of weathering and erosion that form the mineral basis of soil, to the changes caused by the addition of organic matter to the mix and the role of decomposer microorganisms in releasing carbon to the atmosphere.
As co-principal investigator Anthony Aufdenkampe, assistant research scientist at Stroud, explains, “Erosion and excavation activities expose minerals that mix with organic matter in surface soils and are transported through streams and rivers to the sea. We want to better understand how the interaction of carbon with minerals might sequester that carbon from the atmosphere and also understand how humans have altered that process. To do that effectively, we need to take a whole watershed approach to studying these processes at multiple scales in order to put them all together into a predictive model. That would be a significant contribution.”
A research project of this magnitude requires the collection, management and analysis of large amounts of data. A key feature of the project is expanding and enhancing the network of environmental monitoring stations throughout the study area with some of the most sophisticated techniques available. For example, a partnership with NSF’s National Center for Airborne Laser Mapping is providing for the collection and processing of extremely detailed and accurate topographic data by Light Detection and Ranging (LIDAR) measurements.
“The Christina River Basin is already one of the best-studied watersheds of its
size in the nation, with more than 40 years of research conducted by the Stroud
Water Research Center and governmental agencies,” says lead investigator Donald Sparks, S. Hallock du Pont Chair of Soil and
Environmental Chemistry and director of the Delaware Environmental Institute at
UD. “But answering the big questions of earth and environmental science requires
extensive real-time data and a collaborative effort that the
cyber-infrastructure of this Critical Zone Observatory will make available to
scientists around the nation.”
New field installations and data management systems are enhancing the extensive existing network of stations used for monitoring water flow and water chemistry within the Christina River Basin. The network of monitoring sites extends from uplands to inland waters and from inland waters to the coastal zone and covers the range of human uses within the watershed. These niche regions will provide the students involved in the program with valuable multi-scale field training.
Cutting-edge technologies are being used for real-time gathering of hydrological, physical and chemical data at spatial scales ranging from the landscape to the molecular level. Advances in cyber-infrastructure that seamlessly merge real-time data with state-of-the-art graphics are further establishing the CZO as a community resource for sharing scientific data and public information.
As the CZO team learns about the Christina River Basin, they will share results not only with the scientific community but also with policy makers and the public. Results will be communicated regularly with the Christina Basin Water Quality Management Committee, which includes representatives from 15 federal, state and local environmental resource agencies and hosts an annual series of public workshops to identify the science needs of policy makers. Additionally, the Stroud Water Research Center maintains four full-time staff to translate research into educational programs for students, teachers and citizen/conservation groups.