Ecology team improves understanding of valley-wide streamwater chemistry

A geostatistical approach for studying environmental conditions in stream networks and landscapes has been successfully applied at a valley-wide scale to assess headwater stream chemistry at high resolution, revealing unexpected patterns in natural chemical components.

"Headwater streams make up the majority of stream and river length in watersheds, affecting regionalwater quality," said Assistant Professor Kevin J. McGuire, associate director of the Virginia Water Resources Research Center in Virginia Tech's College of Natural Resources and Environment. "However, the actual patterns and causes of variation ofwaterquality in headwater streams are often unknown."

"Understanding the chemistry of these streams at a finer scale could help to identify factors impairing water quality and help us protect aquatic ecosystems," said Gene E. Likens, president emeritus and distinguished senior scientist emeritus with the Cary Institute of Ecosystem Studies and the University of Connecticut.

Results of the study that used a new statistical tool to describe spatial patterns ofwater chemistryin stream networks are published in the April 21 issue of theProceedings of the National Academy of Scienceby a team of ecosystem scientists, including McGuire and Likens.

The data used in the new analysis consist of 664 water samples collected every 300 feet throughout all 32 tributaries of the 14-square-mile Hubbard Brook Valley in New Hampshire. The chemistry results were originally reported in 2006 in the journal Biogeochemistry by Likens and Donald C. Buso, manager of field research with the Cary Institute.

McGuire and other members of the National Science Foundation's Long-Term Ecological Research team at the Hubbard Brook Ecosystem Study decided that the huge, high-resolution dataset was ideal for a new statistical approach that examines how water flows both within the stream network and across the landscape.

"The goal was to visualize patterns that no one has been able to quantify before now and describe how they vary within headwater stream networks," said McGuire. "Some chemical constituents vary at a fine scale, that is patterns of chemical change occur over very short distances, for example several hundred feet, but some constituents vary over much larger scales, for example miles. Several chemical constituents that we examined even varied at multiple scales suggesting that nested processes within streams and across the landscape influence the chemistry of stream networks."

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• Water Quality
• Chemistry
• Ecohydrology