Collection And Characterization Of Organic And Other Particulate Matter In NADP Wet And Dry Deposition
Goss, Natasha R 1 ; Mladenov, Natalie 2 ; Boor, Ethan M 3 ; Seibold, Chris 4 ;Chowanski, Kurt 5 ; Schmidt, Steve K 6 ; Williams, Mark W 7
1 University of Colorado
2 Kansas State University
3 University of Colorado
4 University of Colorado
5 University of Colorado
6 University of Colorado
7 University of Colorado
Dissolved organic matter (DOM) is predominantly organic carbon and, among other functions, supplies energy to support the food web. Recent findings suggest that atmospheric deposition influences the quality of DOM in alpine lakes on a global scale. In the Green Lake 4 alpine watershed at the Niwot Ridge Long Term Ecological Research Station ((NWT-LTER) Colorado, USA) wet deposition of dissolved organic carbon (DOC) has been found to represent an annual input of 2000 kg C (roughly 15 kg C ha-1 yr-1), which was equivalent to >80% of the carbon yield from the watershed. The carbon inputs from dry deposition, including aeolian dust and biological material deposition, are not well constrained. Here, we evaluated the amount of total particulate matter (PM) in dry deposition and examined the pollen content and water chemistry of dissolved constituents in wet and dry deposition at the NWT-LTER Soddie site (3345 m a.s.l.). A marble insert was developed for the dry deposition collector, and in tests with known dust loading, we found that PM recovery and DOC content were comparable to controls with no insert (p>0.05).
A Flow Cytometer and Microscope (FlowCAM), a magnification and real-time particle imaging device, was used to discern and evaluate seasonal trends in wet and dry deposition quality and quantity between 31 May and 6 September 2011. Detected particles ranged in size from 4 to 550 μm. Dry deposition PM loading to the Soddie site was highly variable, ranging from 100 to >230 g/ha/d in June-August 2011.
DOC in dry deposition extracted in 1L of ultrapure water was found to range from 1.19 to 2.14 mg C/L, while wet deposition DOC ranged from 1.13 to 4.16 mg C/L. Higher dry deposition DOC levels were noted in mid-to-late June and mid-to-late July. Wet deposition DOC varied widely. Particle count estimates with the FlowCAM echoed this variability, showing that 104 to 105 particles/d were found in dry and wet deposition. Particle counts peaked from mid-June to late July as shown in Figure 1. Whereas FlowCAM identification of particles, such as pollen and other bioaerosols, proved insightful, further work is needed to improve the reproducibility of particle counting with the FlowCAM.