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Iowa Precipitation Monitoring for the National Trends Network
PERIOD OF PROJECT: Continuous since 1984
PROJECT CHIEF: S.M. Linhart (slinhart@usgs.gov)
STUDY AREA: Clayton and Lucas Counties
COOPERATING AGENCIES: U.S. Geological Survey (Federal program)
NEED FOR STUDY: The amount of substances dispersed into the atmosphere
and deposited by precipitation, aerosols, and gases is expected to continue to
increase throughout North America. Thus, there is an increasing need for
careful, coordinated measurement on a National scale of the amounts, nature, and
effects of these substances. To establish long-term trends in composition and
flux, it is necessary that these measurements be made for a period of at least
10 years. These measurements will be used to assess the link between
environmental effects and atmospheric deposition and will provide the
information necessary for the responsible management of agricultural, forest,
and aquatic ecosystems of the United States.
OBJECTIVES: The Iowa precipitation-monitoring stations are part of the
National Atmospheric Deposition Program/National Trends Network (NADP/NTN)
program which provides a regional-to-national overview of chemical composition
of atmospheric deposition in the United States. This program includes scientific
research in atmospheric deposition, monitoring, and assessment activities.
Information from this overview is being used to discover and characterize
environmentally important geographical and temporal trends in the chemical
climate of North America. In addition, information from this national program is
being used to assess the effects of atmospheric deposition on: - the
productivity of agricultural and forest lands;
- the health of domestic
animals, wildlife, and fish;
- the chemistry of surface and ground water;
- visibility and materials.
PROGRESS: Wet deposition samples are collected weekly at the two Iowa
National Trends Network sites. One is at Big Springs Fish Hatchery in Clayton
County (425435091281101), and the other is at the McNay Research Station in
Lucas County (405747093233201). Field values of pH and specific conductance and
the chemical analyses of the precipitation are published in the Annual Data
Report, as well as in the National Atmospheric Deposition Program/National
Trends Network Annual Data Summary of Precipitation Chemistry in the United
States. Beginning in 2005, collection of field pH and specific conductance were discontinued. This decision by the NADP/NTN program office was based on several factors which include; comparisons showing small differences between field and laboratory pH values (since 1994), reduction of sample handling by site operators to minimize the possibility of contamination, increasing the volume of precipitation available for laboratory chemistry analysis, and to allocate freed resources for network improvements (NADP Data Reort 2004-02: Discontinuation of Support for Field Chemistry Measurements in the National Atmospheric Deposition Program National Trends Network (NADP/NTN)). Annual data reports from water years 1998 through 2004 are currently on-line
under "Publications", and the 2005 water year data should be on-line in 2006. Laboratory pH and specific conductance values are included in the 2005 data report.
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