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Monitoring Nitrogen Deposition in Throughfall Using Ion Exchange Resin Columns

A Field Test in the San Bernardino Mountains

^a USDA Forest Service, Pacific Southwest Research Station, Forest Fire Laboratory, 4955 Canyon Crest Dr., Riverside, CA 92507
^b Current address: USDA-CSREES, National Research Initiative Competitive Grants Program, Stop 2241, 1400 Independence Ave. SW, Washington, DC 20250

View larger version (158K): [in a new window]   Fig. 1. Photograph of throughfall/precipitation collectors used in this study: (a) Ion exchange resin (IER) column collector with a protective tube installed around the IER column to reduce heating from solar radiation; (b) IER collector with the solar shield tube removed, showing the IER column at the bottom of the collector assembly; (c) Tube that is attached to the funnel collector opening in winter to capture snow; (d) Conventional type rain gauge collector used to collect bulk precipitation or throughfall solutions.

View larger version (34K): [in a new window]   Fig. 2. Comparison of deposition of NH4–N to ion exchange resin collectors (open bars) and conventional solution collectors (black bars) in open areas and under mature ponderosa pine trees at (a) Camp Paivika and (b) Barton Flats. The first four pairs of histogram bars represent four consecutive 3-mo exposures. The last three pairs of histogram bars are for the 6-, 9- and 12-mo exposures. In each case, the IER collectors were continuously exposed in the field for the indicated time periods. The data for the conventional solution collectors are the sum of deposition in the throughfall or precipitation solutions collected in the conventional collectors for the indicated time periods. The horizontal dashed line traversing each figure represents the zero baseline for precipitation or throughfall volume.

View larger version (20K): [in a new window]   Fig. 3. Discrepancy in NH4–N deposition (IER minus conventional) in open areas and under pine canopies between the IER collectors and the conventional throughfall solution collectors at Barton Flats (BF) and Camp Paivika (CP).

View larger version (34K): [in a new window]   Fig. 4. Comparison of deposition of NO3–N to conventional throughfall solution collectors and ion exchange resin collectors in open areas and under mature ponderosa pine trees at (a) Camp Paivika and (b) Barton Flats. See caption to Fig. 2 for a description of the histogram bars.