Grantee Research Project Results
1999 Progress Report: A Comparison of Agricultural vs. Forested Basins: Carbon and Nutrient Cycling Within the Hyporheic Ecotone of Streams
EPA Grant Number: R824786Title: A Comparison of Agricultural vs. Forested Basins: Carbon and Nutrient Cycling Within the Hyporheic Ecotone of Streams
Investigators: White, David , Johnston, Timothy C. , Spencer, William E. , Hendricks, Susan P. , Kipphut, George
Institution: Murray State University
EPA Project Officer: Packard, Benjamin H
Project Period: November 1, 1996 through October 1, 1998
Project Period Covered by this Report: November 1, 1998 through October 1, 1999
Project Amount: $300,000
RFA: Water and Watersheds (1995) RFA Text | Recipients Lists
Research Category: Watersheds , Water
Objective:
Processes and patterns within the hyporheic zone?the interface between groundwater and surface water beneath streams?may help explain differences in stream functions between forested and agricultural basins. Most of our knowledge of hyporheic zones comes from studies on a very limited number of streams, primarily high gradient and in relatively pristine condition. Also, few studies have considered the function of hyporheic zones across seasons or the effects of storm discharge. It is well known that agricultural practices greatly alter the chemistry and flow of surface waters. Alterations may result from land use practices (e.g., increased runoff), basin modifications (e.g., changes in groundwater quantity or quality), or instream processes (e.g., effects of siltation, channelization). Land use effects on subsurface processes resulting in increased nutrient, carbon, and sediment loads are largely unknown. The overall objective of the proposed research is to characterize the function of hyporheic ecotones in pristine versus agricultural streams. The study focuses primarily on third order reaches of two basins, one in a forested ecosystem, the other in an agricultural basin.The overall objective has been met by: (1) determining surface, groundwater, and hyporheic dynamics seasonally, (2) following changes in surface and subsurface conditions during and after seasonal storm events, and (3) spatially and temporally comparing selected chemical and biological processes that may be directly affected by hyporheic storage and release?specifically, methane production, benthic algal structure and bacterial abundance, activity, and diversity.
Progress Summary:
Initially, we expected that higher levels of silt deposition observed in the agricultural/rural stream (Ledbetter Creek) during low flow periods would decrease water flow into the streambed substrates and, thus, alter hyporheic functions. Although this does occur to some extent, effects of siltation on hyporheic processes directly beneath the stream were found to be minimal. What appears to be equally or even more important than silt deposition is the increased runoff that comes from agricultural and rural development. Increased runoff alters the physical structure of stream channel. The size and extent of gravel bars are greatly increased, which results in much larger lateral areas of hyporheic storage and processing. Water movement through these gravel bar hyporheic zones is generally much slower than through streambed substrates, even in a forested ecosystem. The addition of silt deposition along the gravel bars further decreases water flow through them. The slower water movement results in longer nutrient and carbon residence times (processing times for N, P, and dissolved organic carbon). Increased nutrient and carbon residence time results in greater bacterial abundance and diversity, higher rates of nitrification and methanogenesis, greater algal growth and diversity, and higher hyporheos diversity and abundance. We would expect similar changes in stream functions and biota to occur in any permanent stream where discharge patterns and gravel bar formations are greatly altered by human activity; therefore, the extent of gravel bar hyporheic zones should be considered in any attempts at stream restoration.Future Activities:
The year 1996 was the wettest year on record for western Kentucky. The years 1997 and 1998 also were among the wettest years ever recorded and contained some of the greatest single event rainfalls on record, including three 4-inch and one 8-inch rainfall. All instrumentation was lost twice at both sites. The year 1999 was the second driest year on record. In most third order areas, the water table remained well below stream surface level and, as of November 1999, the watertable was approximately 0.5 m below the Ledbetter Creek stream surface. Thus, two components of the research were not complete at the time of this report. The first is determination of whole-stream metabolism using propane injections. These data will provide a total estimate of biological activity occurring in the two watersheds. A preliminary report on whole-stream metabolism will be presented at the 2000 meeting of the North American Benthological Society (Colburn and Kipphut). The second is determination of nitrogen sources to the Ledbetter stream system. The storage and flux of nitrate and ammonium is being examined in six first order streams of differing land use (crop, pasture, old-field, forested, clear-cut, and homes and lawns). This study should be completed sometime in September 2000.Journal Articles on this Report : 3 Displayed | Download in RIS Format
Other project views: | All 32 publications | 5 publications in selected types | All 3 journal articles |
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Type | Citation | ||
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Halda-Alija L, Johnston TC. Diversity of culturable heterotrophic aerobic bacteria in pristine stream bed sediments. Canadian Journal of Microbiology 1999;45:879-884. |
R824786 (1999) |
not available |
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Halda-Alija L, Hendricks SP, Johnston TC. Spatial and temporal variation of Enterobacter genotypes in sediments and the underlying hyporheic zone of an agricultural stream. Microbial Ecology 2001;42(3):286-294. |
R824786 (1999) |
not available |
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Hendricks SP, Rice GL. Utilization of a specially-designed sediment colonization chamber to examine hyporheic water chemistry and microbial communities. Journal of Freshwater Ecology 2000;15(4):445-453. |
R824786 (1999) |
not available |
Supplemental Keywords:
third order stream, advection-dispersion models, algae, artificial chambers, benthos, biology, chemical transport, CO2, colonization, ecology, ecosystem restoration, enteric bacteria, environmental chemistry, greenhouse gases, groundwater, hydrology, hyporheos, Kentucky Lake, land, limnology, methanogenesis, microbial diversity, microbial ecology, nitrification, nitrogen, phosphorus, piezometers, precipitation, sedimentation, sediments, solute transport, stream hydraulics, terrestrial-aquatic integrated assessment, water, watersheds, zoology., RFA, Scientific Discipline, Water, Ecosystem Protection/Environmental Exposure & Risk, Water & Watershed, Nutrients, Ecology, Hydrology, Ecosystem/Assessment/Indicators, Ecosystem Protection, exploratory research environmental biology, Chemical Mixtures - Environmental Exposure & Risk, Environmental Chemistry, Ecological Effects - Environmental Exposure & Risk, Ecological Effects - Human Health, Watersheds, Ecological Indicators, nutrient transport, ecological exposure, ecological effects, hyporheic ecosystem, dissolved organic matter, carbon cycling, agricultural watershed, forest ecosystems, forest ecosystem, ecosystem effects, surface water, agricultural basins, forested basins, aquatic ecosystems, ecosystem, agriculture, hyporheic ecotone, nutrient cycling, forested watershed, ecological benefits, groundwater, agriculture ecosystemsRelevant Websites:
http://www.mursuky.edu/qacd/cos/crr/crr-wtr.htm
http://www.mursuky.edu/qacd/cos/hbs/hbs.htm
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.