Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • BCO-DMO Processing Description
• Related Publications
• Parameters
• Instruments
• Project Information
• Funding

Upper Newport Back Bay near-shore surface waters at inlet, mid-estuary and outlet. Site 1 (33.650327, -117.8671967), located at the San Diego creek inlet; site 2 (33.6302266, -117.8859726), located mid-estuary; and site 3 (33.6181867, -117.9051099), located near the Newport Beach marina and Pacific Ocean outlet. 

Surface water (<5 cm) was sampled in the morning from the shore using a 6-foot sampling scoop. Samples were collected in amber glass bottles and immediately transported to the laboratory where they were filtered through 0.2-mm Durapore filters.  After filtering, samples were stored at 4 oC until analysis if necessary.  A range of water quality measurements were made in-situ with a Hanna Instruments HI 9829 multiparameter probe equipped with a double junction pH/oxidation reduction potential (ORP) sensor (HI7609829-1), galvanic dissolved oxygen (DO) sensor (HI7609829-2), and a conductivity/turbidity sensor (HI7609829-4). The probe also has a temperature sensor.  To measure DOC, filtered samples were placed in 50 mL glass DOC vials with Teflon-lined caps and acidified to pH <2 using a few drops of hydrochloric acid (6 M). Prepared samples were stored at 4ºC for less than 30 days prior to analysis. DOC concentrations (in units of mg/L) were measured using a Shimadzu TOC analyzer with a 0.20 mg C L-1 method detection limit and a 0.34 mg C L-1 minimum reporting level.

This is a summary of methods from W. J. De Bruyn, D. Manickam, A. Harrison, C. D. Clark. “Time-resolved fluorescence lifetimes of dissolved organic matter (DOM) as a function of environmental parameters in estuarine waters”. Environmental Science and Pollution Research (2025). https://doi.org/10.1007/s11356-024-35777-3

* adjusted parameters to comply with database requirements
* converted dates to ISO format
* added sampling lat/lon to dataset

NSF Award Abstract

Ethanol is added to gasoline to increase octane levels and lower the concentrations of carbon monoxide and surface ozone in the atmosphere. As a renewable fuel, ethanol may also help decrease our dependence on gasoline. Increased use of ethanol in the United States and globally as a fossil fuel substitute and additive is expected to increase ethanol levels in the atmosphere. Atmospheric ethanol is converted to acetaldehyde which is a hazardous pollutant. To understand the impact of increasing ethanol usage, it is important to understand the cycling of ethanol and acetaldehyde in the environment--how they are produced, consumed, and interconverted. Because these compounds can cross from air into water, this requires understanding what happens to these compounds in both the atmosphere and in seawater and other surface waters. This proposal focuses on improving our understanding of processes that produce and consume ethanol and acetaldehyde in coastal seawater and other coastal surface waters like estuaries and salt marshes. This project will measure the rates of photochemical production of ethanol and acetaldehyde, as well as their chemical and biological degradation rates. The project will also measure the rate and efficiency of the biological production of acetaldehyde from ethanol by microbial organisms in these waters. The scientists have an excellent track record of involving undergraduate students, including underrepresented minorities, in their research and as co-authors on publications, a trend they plan to continue with this project. These students would be trained in analytical chemistry and environmental research and would present their research findings at local and national conferences. Lastly, the PIs also plan outreach activities with high school STEM programs to improve student diversity in environmental research.

The primary sink for ethanol in the troposphere is reaction with OH to produce acetaldehyde. Acetaldehyde levels in the troposphere are also expected to increase with increased use of ethanol. Changes in the atmospheric concentrations of these species are expected to have a significant impact on the oxidative capacity of the troposphere. To understand future impacts, it is important to understand current tropospheric budgets which have significant uncertainties for both species. One of the largest sources of uncertainty is the role of the oceans and surface waters in cycling these species into and out of the troposphere. The current understanding is limited by the very small database of ambient concentration measurements in both air and water and an incomplete insight into the processes that control concentrations in seawater and surface waters; these processes represent a complex interplay between biological and photochemical sources and sinks, and air-water exchange. To improve the current understanding of the cycling of ethanol and acetaldehyde in coastal seawater and surface waters, this project will measure: 1) chemical and biological degradation rates of ethanol and acetaldehyde in coastal waters; 2) the rate and efficiency of the biological production of acetaldehyde from ethanol by microbial organisms; 3) ethanol and acetaldehyde concentrations in air and surface waters; 4) the ethanol and acetaldehyde source strength of estuary and saltmarsh sediments; and 5) ethanol and acetaldehyde photochemical production rates in surface waters.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.