Cloud Deposition Monitoring Clingmans Dome, TN, Great Smoky Mountains National Park 2010

MACTEC Engineering and Consulting, Inc.

The Clingmans Dome cloud water deposition estimates show an overall decline in sulfur and nitrogen deposition estimates over the history of the project despite interannual increases observed for both species in 2004, 2006, and 2009. The small increase in the 2009 cloud water deposition estimates (Figure 4-6) was attributed to the higher amount of water deposition in 2009 and offsets the substantial decreases in ion concentrations (Figure 3-7). Despite some annual variability from year to year, estimates of total deposition, i.e. deposition produced by cloud + dry components, show a general, overall decline since 2001 (Figure 6-1). The 2010 seasonal estimates show that dry deposition is a small contributor to the deposition of pollutants at high elevations (Table 5-1). Cloud deposition is the significant pathway for deposition at these elevations. The principal recommendation for the 2011 season is to improve the efficiency of the power supply system to ensure proper operation of the cloud collection system, specifically control of the valve opening and closing functions. Random valve openings and/or two valves being open at the same time occurred throughout the second half of the 2010 season resulting in uncertainty in collection dates as well as sample volumes. Power fluctuations were suspected of causing these random valve openings, but the actual cause was not specifically determined during the 2010 field season. This problem will be thoroughly investigated at MACTEC’s Gainesville, FL test location and at the CLD303 site before commencement of the 2011 season. A new field pH probe will be purchased to replace the field pH probe that failed early in the 2010 season. In addition to continuing laboratory pH and conductivity measurements in order to verify proper operation of the field pH meter and probe and to provide backup measurements for this important parameter, an audit of the field laboratory is recommended. Although an audit was conducted in 2010, problems with the field pH and conductivity measurement protocols during the 2006, 2007, 2009, and 2010 field seasons, necessitate the audit for the 2011 season. The audit should also include the PVM calibration procedures and documentation, as well as cloud water sample collection, handling, and documentation procedures. New site operators should be provided with continual on-the-job training during the first year of performance. Returning site operators should continue to be trained and monitored carefully since the cloud water collection system is complex with many different components and requires several years of operational experience before proficiency can be achieved. There will be additional modifications to the cloud collection system for the 2011 season in order to resolve the random valve opening problem and to improve the efficiency of the power supply system.