Dynamics of the chemical composition of rainwater throughout Hurricane Irene

Abstract

Abstract. Sequential sampling of rainwater from Hurricane Irene was carried out in Wilmington, NC, USA on 26 and 27 August 2011. Eleven samples were analyzed for pH, major ions (Cl−, NO3−, SO42−, Na+, K+, Mg2+, Ca2+, NH4+), dissolved organic carbon (DOC) and hydrogen peroxide (H2O2). Hurricane Irene contributed 16% of the total rainwater and 18% of the total chloride wet deposition received in Wilmington NC during all of 2011. This work highlights the main physical factors influencing the chemical composition of tropical storm rainwater: wind speed, wind direction, back trajectory and vertical mixing, time of day and total rain volume. Samples collected early in the storm, when winds blew out of the east, contained dissolved components indicative of marine sources (salts from sea spray and low DOC). The sea-salt components in the samples had two maxima in concentration during the storm the first of which occurred before the volume of rain had sufficiently washed out sea salt from the atmosphere and the second when back trajectories showed large volumes of marine surface air were lifted. As the storm progressed and winds shifted to a westerly direction, the chemical composition of the rainwater became characteristic of terrestrial storms (high DOC and NH4+ and low sea salt). This work demonstrates that tropical storms are not only responsible for significant wet deposition of marine components to land, but terrestrial components can also become entrained in rainwater, which can then be delivered to coastal waters via wet deposition. This study also underscores why analysis of one composite sample can lead to an incomplete interpretation of the factors that influence the chemically divergent analytes in rainwater during extreme weather events.

Sodium fertilization increases termites and enhances decomposition in an Amazonian forest

“…Low levels of Na deposition, likely of little direct consequences to plants, enhanced decomposition in this study; low-levels of Na delivery by hurricanes, to otherwise Na-impoverished ecosystems, have a similar potential to enhance ER. Aerosol deposition of Na and other marine ions peak during tropical storms (Miller et al 2008, Mullaugh et al 2012. Moreover, anecdotal accounts from New England suggest hurricanes can deposit Na far inland.…”

Variability of dissolved organic carbon in precipitation during storms at the Shale Hills Critical Zone Observatory

“…Dissolved OC concentrations during Hurricane Sandy ranged from 0.43 to 1.61 mg C L −1 over the course of the event, with an average concentration of 0.90 mg C L −1 (Table , Figure ). This average concentration is higher than the concentrations of 0.31 mg C L −1 reported from sequential samples collected during tropical storm Ernesto (Miller et al, ), and 0.19 mg C L −1 during Hurricane Irene in Wilmington (NC, USA; Mullaugh et al, ), but lower than concentration of 2.30 mg C L −1 reported from a composite sample from Hurricane Irene in Greenville (NC, USA; Mitra et al, ) . Those studies during extreme events were from coastal locations (Wilmington and Greenville, NC), whereas our observations are the first to consider changes in quantity and quality of precipitation DOC during a hurricane as it followed an inland track.…”

“…Several addressed variability of DOC and its components in precipitation during typical‐frequency events in South America (Germer et al, ; Zimmermann, Wilcke, & Elsenbeer, ), Japan (Sempéré & Kawamura, ; Taguchi et al, ), and the United States (Kawamura, Steinberg, & Kaplan, ). Others focused on dynamics during extreme events such as tropical storms and hurricanes in the United States (Miller, Willey, & Kieber, ; Mullaugh, Willey, Kieber, & Mead, ; Willey et al, ). In general, studies found that concentrations of DOC can be variable during events (Germer et al, ; Kawamura et al, ) or change very little (Zimmermann et al, ) and are influenced by storm characteristics (Mullaugh et al, ).…”

“…Others focused on dynamics during extreme events such as tropical storms and hurricanes in the United States (Miller, Willey, & Kieber, ; Mullaugh, Willey, Kieber, & Mead, ; Willey et al, ). In general, studies found that concentrations of DOC can be variable during events (Germer et al, ; Kawamura et al, ) or change very little (Zimmermann et al, ) and are influenced by storm characteristics (Mullaugh et al, ). Results also show changes in the quality of DOC during storms, as evidenced by abundance of organic compound classes (Kawamura et al, ; Sempéré & Kawamura, ; Taguchi et al, ) .…”

“…Results also show changes in the quality of DOC during storms, as evidenced by abundance of organic compound classes (Kawamura et al, ; Sempéré & Kawamura, ; Taguchi et al, ) . The levels of DOC usually decreased sharply with increasing precipitation depth during typical storm events (Germer et al, ; Zimmermann et al, ) but showed increases towards the end of extreme weather events (Miller et al, ; Mullaugh et al, ). Yet one study from tropical rainforests in South America observed a lack of intraevent variation in DOC concentrations (Zimmermann et al, ), which was explained by the remoteness of the sampling location from major sources of emissions.…”