LOCATION DESCRIPTION
Collected from a small riffle approximately 10m upstream from the lake and 30m downstream of the USGS stream-gauging flume. This sub-catchment (35 ha area) of the Mirror Lake watershed contains 3 seasonal homes and one unpaved (un-salted in winter) road. Numerous studies have been conducted on Mirror Lake since the mid-1960s, including extensive chemical, biological, and paleoecological research which are described in detail in the book: An Ecosystem Approach to Aquatic Ecology (Likens, 1985).
SAMPLING DESIGN
Samples are collected in acid-washed, deionized water-rinsed, polyethylene bottles. The normal sampling interval is weekly, with more frequent samples taken at times of increased discharge.
DATA DESCRIPTION
Concentrations (mg/L) in weekly streamwater samples. Base cation data are available since 1967: pH since 1968. Ammonium, anions, and dissolved silica have been measured routinely since 1970, and phosphate was determined routinely first in 1972, although some data are available prior to these dates for each solute.
NOTE REGARDING NITRATE DATA: After careful and exhaustive inter- and intra-laboratory tests we determined that nitrate concentrations in stream water were no longer remaining stable after collection, as they had in the past (see Buso, Likens and Eaton 2000). It is possible that the biological community in some streams of the HBEF has changed in recent years, affecting the nitrate concentration in complicated ways. While there was no systematic bias to the data, the situation occurred primarily during summer, when nitrate concentrations and streamflows are very low. Thus, we urge some caution in using the streamwater nitrate data collected since 2006, when nitrate stability was last confirmed. In 2013, new protocols were instituted to prevent decay of nitrate concentrations after collection and the problem has been resolved. There is no evidence that nitrate concentrations in the long-term precipitation record have been affected.
Buso, Donald C.; Likens, Gene E.; Eaton, John S. 2000. Chemistry of precipitation, streamwater, and lakewater from the Hubbard Brook Ecosystem Study: a record of sampling protocols and analytical procedures. Gen. Tech. Rep. NE-275. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northeastern Research Station. 52 p.
Likens, G.E. (1985). An Ecosystem approach to aquatic ecology: Mirror Lake and its environment. Springer-Verlag New York, Inc.
