![]() ![]() By following those procedures and stringent sampling protocols, the MDN is able to report mercury concentrations below 1 part per trillion (< 1 nanogram/liter).ĭata are available from samples collected at two locations in Nebraska: 1) our station (Site NE15) located at the Agrometeorology lab at University of Nebraska Agricultural Research and Development Center (ARDC) near Mead began collection data in June 2007 and 2) a site at the North Platte Agricultural Experiment Station (NE99) near North Platte that has been collecting data since October 2008. The HAL supplies the collection bottles already charged with the hydrochloric-acid preservative. ![]() Rigorous cleaning ensures that each sampling train component is essentially mercury-free. With each MDN sample, the entire sampling train is replaced with one that is cleaned by the Mercury Analytical Laboratory (HAL) at Frontier Geosciences, Inc., Seattle, Washington. Site operators collect samples Tuesday morning or daily within 24 hours of the start of precipitation. As an additional sample preservation measure, the collection bottle is charged with 20 mL of a one percent hydrochloric acid solution. The funnel and connecting tube reduce sample exposure to the open atmosphere and limit loss of dissolved mercury. Nebraska Tornado Average - 38. Modifications include a glass funnel, connecting tube, bottle for collecting samples, and an insulated enclosure to house this sampling train. Nebraska Annual Precipitation - 23.63 inches, 38th wettest state in the U.S. The automated collector has the same basic design as the NTN collector but is modified to preserve mercury. All MDN sites follow standard procedures and have uniform precipitation chemistry collectors and gages. The MDN is the only network providing a long term record of total mercury (Hg) concentration and deposition in precipitation in the United States and Canada. The CAL also measures orthophosphate, but only for quality assurance as an indicator of sample contamination. The CAL measures free acidity (H + as pH), conductance, calcium (Ca 2+), magnesium (Mg 2+ ), sodium (Na + ), potassium (K + ), sulfate (SO 4 2-), nitrate (NO 3 + ), chloride (Cl - ), and ammonium (NH 4 +). All samples are sent to the CAL for analysis, and data entry, verification, and screening. They weigh the collection bucket to determine sample volume and transfer the sample from the collection bucket to a shipping bottle. All other mosaics are now updated hourly, including the 48h and 72h maps. Data Update Cycle: The 1-hr mosaic is updated every 5 min (approx). They collect samples weekly on Tuesday morning, using only containers cleaned at the Central Analytical Laboratory (CAL) at the Illinois State Water Survey (ISWS). Rainfall totals for the last 24 hours to 3 days high resolution map. Site operators follow standard operational procedures to help ensure NTN data comparability and representativeness. The automated collector ensures that the sample is exposed only during precipitation (wet-only-sampling). Each site has a precipitation chemistry collector and gage. Sites predominantly are located away from urban areas and point sources of pollution. National Trends Network - Acids, Bases & Nutrients ![]()
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