International Programs News & Views Volume 20
IMPACT OF FUEL SPILLS ON ANTARCTICA SOILS
The U.S. Department of Agriculture’s Natural Resources Conservation Service (NRCS) has considerable expertise in monitoring soil climate. Many of the NRCS stations are located in regions of extreme environments. Although the soil climate stations were established as part of the Global Climate Change Program, the ensuing data are in great demand for a variety of applications.
Some of the data uses include:
Water resource management.
Monitoring drought extent and severity.
Remote sensing sensor calibration and verification.
Hydric soils studies.
Soil microbial population predictions.
Surface and ground water pollution studies.
Soil Taxonomy improvement.
Continental scale climate modeling.
Snake hibernation research.
Permafrost active layer studies.
Assorted engineering uses.
Various agricultural planning activities.
Data from many of the NRCS soil climate stations are available through the National Water and Climate Center’s home page at http://www.wcc.nrcs.usda.gov. All of the NRCS soil climate data will be made available on this site in the future. Data from permafrost-affected soils are shared with the International Permafrost Association as part of their Circumpolar Active Layer Monitoring program. In addition, NRCS participates in the Land-Air-Ice-Interaction project, a part of the National Science Foundation’s (NSF) Arctic Research Program.
As part of the Global Climate Change Program, NRCS has established a number of soil climate-monitoring stations. Soils in the Polar Regions and in high altitude areas, such as Tibet, are thought to be particularly sensitive to climate change. Relatively little is known about Antarctic soil climate, other than the soils are assumed to be the coldest and driest on earth. They represent an end in the soil climate continuum.
An opportunity to learn more about Antarctic soils and soil climate presented itself when New Zealand researchers expressed a need for soil climate information with respect to studies they were conducting on fuel spills on Antarctic soils. A cooperative project lead by Landcare Research, Hamilton, New Zealand, was initiated in 1999. For its part of the project, NRCS agreed to establish a number of soil climate stations in Antarctica and to describe and sample the soils at all sites for characterization analysis. The soil climate stations were to be established in areas near the fuel-spill sites, with additional instrumentation in the fuel-spill affected soils to monitor soil moisture and temperature. Waikato University, Hamilton, New Zealand, is an additional participant in this project. Antarctica New Zealand provided logistical support.
The project will provide information useful for management to decide whether to ameliorate oil-contaminated soils in the Antarctic. In addition, information obtained from this project has implications for soil management in other cold areas, such as Alaska. Most importantly for NRCS, this project provides an opportunity to gather data in an area sensitive to global climate change that will be useful in associated activities.
Impact of Fuel Spills on Antarctic Soils
Accidental fuel spills on land in the Antarctic occur mainly near scientific stations where storage and refueling of aircraft and vehicles take place. Fuel spills have been reported at McMurdo Station, Marambio Base, and Faraday Research Station. In addition, oil contamination of soil was a consequence of drilling activities at numerous sites. As Antarctic soils occur in an environment of low precipitation and severe cold, with unique biological communities, it is difficult to predict the impacts of fuel spills on the environment.
Understanding the effect of fuel spills on the thermal and moisture regimes of Antarctic soil is crucial, as they are major influences on chemical and biological processes. An increase in soil temperature from oil darkening the soil will lead to permafrost melt, which can transport dissolved salts to the soil surface where they are deposited. When salt concentrations in Antarctic soils are high, available water decreases, and this can impact negatively on microbial activity.
The overall objective of this program is to determine the impact of fuel spills on soil biology, chemistry, and physics. To achieve this objective, the properties of oil-contaminated soils are being compared with those of nearby control sites. The oil-spill sites are located at Scott Base, Marble Point, and Bull Pass in the Wright Valley, and represent contrasting soil types. Soils around Scott base have been impacted as a result of establishment and habitation of the base. At Marble Point, spills occur on the site of a former base, which was inhabited between 1957 and 1963. The spill at Bull Pass results from drilling activities.
John Kimble and Ron Paetzold, Research Soil Scientists, National Soil Survey Center, made a trip to Antarctica in January 1999, with other members of the research group. After the two days of required survival training, they were transported to Marble Point. Two sites were selected, one in an oil spill and another in a control location. The soil at each site was described and sampled for characterization. Soil moisture and temperature probes were installed at each site.
In addition, at the control site, atmospheric sensors were installed to monitor air temperature, relative humidity, wind speed and direction, and solar radiation. The atmospheric variables are measured every 10 seconds and averaged hourly. The soil variables are measured every 20 minutes and averaged hourly. A solar panel was installed to provide power to the system and two batteries were installed to provide continuous power during the dark winter months. Data must be downloaded from the datalogger annually using a palmtop computer.
Control sites were selected at Bull Pass and Scott Base, the soils described and sampled, and instrumentation was installed. The sensors are the same as for the Marble Point control site.
An opportunity for research cooperation between NRCS, the National Aeronautics and Space Administration (NASA), and the University of Washington surfaced during the field preparations. Chris McKay, NASA, and Ron Sletten, University of Washington, are working on NSF projects in the dry valleys. One project is to improve soil moisture measurement methods in extremely dry soils. They loaned some experimental soil moisture humidity sensors to our group for testing and evaluation. We installed them at the Bull Pass site. In turn, we loaned them some instrumentation to install in Victoria Valley. They will maintain that station and we will share data.
In December 1999, Ron Paetzold returned to Antarctica to perform routine maintenance and retrieve data from the stations. At this time, the Marble Point oil-spill station was upgraded to a stand-alone station and an oil-spill station was installed at Scott Base. Logistics prevented the installation of an oil-spill station at Bull Pass. The Kiwis managed to ding their only helicopter in whiteout conditions and it had to be returned to New Zealand for repairs. Due to the resulting shortage of helicopter time, only two members of the party were allowed to travel to Bull Pass and they were only allowed five hours there. This was barely enough time to download the data, perform routine maintenance, and replace a faulty wind speed sensor.
Data from the first year’s activities are excellent and dispel many of the misconceptions about Antarctica soils. The shallow soil temperatures are much greater than anticipated and the thaw depths concomitantly are greater. While the maximum air temperature was about 44°F, the soil surface warmed to 83°F. The average and minimum air temperatures were –7°F and -64°F, respectively.
The soil at this site (Bull Pass) thawed to deeper than 2 feet. The average soil temperature was close to the average air temperature at all depths, but a just little warmer below 2 feet. The surface soil temperature reflected the incident solar radiation. Evidently, during the summer, solar radiation warms the soil, which in turn warms the air. The soil undergoes many more freeze-thaw cycles than anticipated. In addition, the oil-spill sites were significantly warmer in the summer than the control sites.
Water contents were dry, as expected, but did change with melting snow and evaporation. The higher surface soil temperatures are responsible for higher than expected evaporative demands. The average soil moisture were around five percent by volume. The maximum water contents were around 14 percent by volume in the soil surface during snowmelt.
The project is scheduled to end in June 2002. However, the scientific community is urging NRCS to continue to maintain the stations for long-term monitoring activities. As long as the project continues, annual maintenance and data retrieval is necessary. The environment in Antarctica is extremely harsh and hard on instruments. The combination of cold, dry, dusty, and windy conditions conspire to damage instruments and power supplies. The data, on the other hand, are extremely valuable.
Not only are they useful for the fuel-spill project, but they provide base-line information for global climate change and information on the behavior of cold and dry soils. Long-term data would be useful for defining normal conditions, departures from normal, trends, and cyclic events. It would also provide information on the magnitude of year-to-year variability. Already a great deal has been learned during the first year of this project and it is anticipated that the information gathered during the remaining project time will provide even more insight on the behavior of Antarctic and other cold soils.
Author: Ron F. Paetzold (retired), Research Soil Scientist, National Soil Survey Center, Lincoln, Nebraska
Editor: Gail C. Roane (retired), International Programs Division