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Methanol, formaldehyde, and acetaldehyde in rain : Development of a method to determine ¹5N-NO2- and NO3- in fresh and brackish waters

UNCW Author/Contributor (non-UNCW co-authors, if there are any, appear on document)
Joseph David Felix (Creator)
Institution
The University of North Carolina Wilmington (UNCW )
Web Site: http://library.uncw.edu/
Advisor
S. Bart Jones

Abstract: Methanol, formaldehyde, and acetaldehyde concentrations were measured in 49 rain events in Wilmington, NC from August 2007 to August 2008. The first methanol concentrations in rainwater are reported. Methanol concentrations ranged from below the detection limit (<0.10 µM) up to 9.3 µM with a volume weighted average concentration of 1.2 + 0.2 µM and a simple average concentration of 1 +2 µM. Formaldehyde in the same rain events had a range of 0.1 µM to 5.5 µM with a volume weighted average concentration of 1.5 +0.2 µM and a simple average concentration of 2 +2 µM. Acetaldehyde in the rain events had a volume weighted average concentration of 0.140 + 0.002 µM and a simple average concentration of 0.2 + 0.2 µM with concentrations ranging from 0.01 to 0.72 µM. Additional rainwater components including hydrogen peroxide, hydrogen ion, nitrate, formate, acetate, and non sea salt sulfate (NSS) were measured in an attempt to correlate these components with methanol, formaldehyde, and acetaldehyde. Methanol only correlated well with acetaldehyde which may be due to both having strong biogenic sources. Formaldehyde correlated well with H+, NO3-, and NSS suggesting common anthropogenic sources. Acetaldehyde correlates well with methanol, formaldehyde, nitrate, NSS, and hydrogen peroxide suggesting substantial anthropogenic and biogenic sources. When methanol, formaldehyde, and acetaldehyde weighted average concentrations were grouped according to rain event origin, methanol and acetaldehyde concentrations were highest in rain events originating strictly over land, supporting previous observations of methanol having a large biogenic source. Formaldehyde concentrations in rain events originating over land were also higher, supporting the idea of formaldehyde having anthropogenic sources but also suggesting a significant biogenic source. When methanol, formaldehyde, and acetaldehyde volume weighted concentrations were sorted according to seasons (winter, fall, spring, summer) and to growing and non-growing seasons, concentrations of all three increased during the spring, summer, and growing seasons, suggesting an increase in biogenic sources and photochemical production. Methanol, formaldehyde, and acetaldehyde concentrations also increased during rain events occurring between 12pm – 6pm. Increases may be due to increases in photochemical production, plant activity, and activity from anthropogenic sources during the day.

Additional Information

Publication
Thesis
A Thesis Submitted to the University of North Carolina Wilmington in Partial Fulfillment of the Requirements for the Degree of Master of Science
Language: English
Date: 2009
Keywords
Environmental chemistry, Nitrates--Environmental aspects, Rain and rainfall--Analysis, Rain and rainfall--Environmental aspects, Water--Nitrogen content--Analysis, Water chemistry
Subjects
Environmental chemistry
Rain and rainfall -- Environmental aspects
Rain and rainfall -- Analysis
Water chemistry
Water -- Nitrogen content -- Analysis
Nitrates -- Environmental aspects