About

Ellen Druffel is a Distinguished Professor Emerita of ESS at the University of California, Irvine. The page provides her contact information but does not include specific details about her research focus, background, or key contributions.

Research topics

• Geology
• Oceanography
• Environmental science
• Chemistry
• Environmental chemistry
• Ecology
• Environmental engineering

Selected publications

• Indonesian Seas Circulation Linked to Mean Climate State Reversals

  Paleoceanography and Paleoclimatology · 2025-12-01

  article

  Abstract The Indonesian Throughflow (ITF) plays a critical role in modifying global ocean and climate systems through interactions with Indo‐Pacific climate. The El Niño Southern Oscillation (ENSO) and East Asian Winter Monsoon (EAWM) alter the spatial distribution of surface layer freshwater within the Maritime Continent, which affects heat and freshwater distribution from the Pacific to the Indian Ocean via the ITF. Yet, limited observations prior to the 1980s hinder examination of the role of ENSO and the EAWM on surface layer variability. Here, we use coral Δ 14 C and Ba/Ca records as proxies of ocean circulation from locations along main ITF pathways to investigate behavior in EAWM and ENSO strength and interaction. We focus on biennial variability given that the biennial modulation of the ENSO‐EAWM relationship remains a critical gap in understanding their interaction. From 1953 to 1963, the EAWM influences surface layer pathways at biennial timescales. Following 1963, shifts in EAWM mean state and the frequency of central Pacific El Niño events coincide with lower biennial variance and modulations of EAWM‐ and ENSO‐driven surface layer circulation. These historical ENSO and EAWM influences provide insight into future ITF variability and its associated global impacts.

  PublisherDOI

• Hydrothermally Induced Refractory DOC Sinks in the Deep Pacific Ocean

  Global Biogeochemical Cycles · 2025-09-01 · 1 citations

  articleOpen access

  Abstract Dissolved organic carbon (DOC) constitutes the largest pool of reduced carbon in the global ocean, with important contributions from both recently formed and aged, biologically refractory DOC (RDOC). The mechanisms regulating RDOC transformation and removal remain uncertain though hydrothermal vents have been identified as sources and sinks. This study examines RDOC sinks in the deep Pacific Ocean, highlighting the role of submarine hydrothermal systems. Geochemical survey data from GO‐SHIP and GEOTRACES projects, alongside specific investigations of Pacific hydrothermal systems, suggest that particulate iron introduced by hydrothermal systems plays a key role in scavenging DOC and delivering it to the seafloor, leaving a deficit in the RDOC of the deep ocean. Dilution of the oceanic water column by hydrothermal fluids exhibiting low DOC concentrations likely plays a secondary role.

  PublisherOA PDFDOI

• Removal of dissolved organic carbon in the West Pacific hadal zones

  Nature Communications · 2025-01-16 · 3 citations

  articleOpen accessSenior author

  The deep oceans are environments of complex carbon dynamics that have the potential to significantly impact the global carbon cycle. However, the role of hadal zones, particularly hadal trenches (water depth > 6 km), in the oceanic dissolved organic carbon (DOC) cycle is not thoroughly investigated. Here we report distinct DOC signatures in the Japan Trench bottom water. We find that up to 34% ± 7% of the DOC in the trench bottom is removed during the northeastward transport of dissolved carbon along the trench axis. This DOC removal increases the overall DOC recalcitrance of the deep Pacific DOC pool, and is potentially enhanced by the earthquake-triggered physical and biogeochemical processes in the hadal trenches. Radiocarbon analysis on representative oceanic transects further reveals that the Pacific deep-water DOC undergoes distinct removal compared to those in the Atlantic and Indian Oceans along the thermohaline transport. Our findings highlight hadal trenches as previously unrecognized DOC sinks in the deep ocean system, with varying dynamics that warrant further investigation. Deep-sea dissolved organic carbon is significantly removed within hadal trenches, positioning these regions as critical sinks in the global DOC pool and highlighting a potential coupling between the marine carbon cycle and tectonic activity.

  PublisherOA PDFDOI

• Changes in Pyrogenic Tracers Over the Last 15,000 Years in the Congo River Catchment Through Multi‐Method Analysis

  Journal of Geophysical Research Biogeosciences · 2025-09-28 · 2 citations

  articleOpen access

  Abstract Black carbon (BC), the most recalcitrant part of the pyrogenic carbon continuum, is formed by the incomplete combustion of biomass and fossil fuels. Methods for detecting BC include the chemical degradation of condensed aromatic compounds into benzenepolycarboxylic acids (BPCA), chemothermal oxidation of organic carbon at 375°C (CTO), 13 C nuclear magnetic resonance combined with a molecular mixing model, thermogravimetry‐differential scanning calorimetry, and the use of polycyclic aromatic hydrocarbons as tracers. However, there is limited knowledge about the comparability of these methods in marine sediments and their suitability as wildfire proxies. Here, we examined a sediment core from the Congo River outflow using a multi‐methodological approach with environmental data and proxies to assess pyrogenic tracers from the Congo River basin over the last 15,000 years and determine commonalities between the methods. Despite differing analytical windows, both dry‐weight and total organic carbon concentrations, and δ 13 C values for most methods showed a congruous trend. Higher BC concentrations and higher δ 13 C values were present during arid periods and lower during humid periods, reflecting changes in vegetation and terrestrial organic matter inputs. For all methods, the sedimentation flux identified significant variations in BC deposition only in the last 1,000 years BP due to anthropogenic land use changes. These findings deepen our understanding of BC in the global carbon cycle and show that BC proxies can reveal distinct transport pathways, with CTO‐BC representing atmospheric deposition and BPCA‐BC and NMR‐BC indicating fluvial inputs to coastal margins, aiding in the reconstruction of past climates and landscapes.

  PublisherDOI

• Proteinaceous corals reveal heterogeneity in shifting Southern California oceanographic regimes

  Marine Environmental Research · 2025-01-11 · 1 citations

  article
  PublisherDOI

• Variable aging and storage of dissolved black carbon in the ocean

  Proceedings of the National Academy of Sciences · 2024-03-22 · 21 citations

  articleOpen accessCorresponding

  During wildfires and fossil fuel combustion, biomass is converted to black carbon (BC) via incomplete combustion. BC enters the ocean by rivers and atmospheric deposition contributing to the marine dissolved organic carbon (DOC) pool. The fate of BC is considered to reside in the marine DOC pool, where the oldest BC 14 C ages have been measured (>20,000 14 C y), implying long-term storage. DOC is the largest exchangeable pool of organic carbon in the oceans, yet most DOC (>80%) remains molecularly uncharacterized. Here, we report 14 C measurements on size-fractionated dissolved BC (DBC) obtained using benzene polycarboxylic acids as molecular tracers to constrain the sources and cycling of DBC and its contributions to refractory DOC (RDOC) in a site in the North Pacific Ocean. Our results reveal that the cycling of DBC is more dynamic and heterogeneous than previously believed though it does not comprise a single, uniformly “old” 14 C age. Instead, both semilabile and refractory DBC components are distributed among size fractions of DOC. We report that DBC cycles within DOC as a component of RDOC, exhibiting turnover in the ocean on millennia timescales. DBC within the low-molecular-weight DOC pool is large, environmentally persistent and constitutes the size fraction that is responsible for long-term DBC storage. We speculate that sea surface processes, including bacterial remineralization (via the coupling of photooxidation of surface DBC and bacterial co-metabolism), sorption onto sinking particles and surface photochemical oxidation, modify DBC composition and turnover, ultimately controlling the fate of DBC and RDOC in the ocean.

  PublisherOA PDFDOI

• Stable Isotopic (<i>δ</i>¹³C) Evidence for Global Microbial Sequestration of Refractory Dissolved Organic Matter

  Geophysical Research Letters · 2024-05-03 · 7 citations

  articleOpen accessSenior author

  Abstract Dissolved organic carbon (DOC) in the global oceans is an important long‐term carbon sink. Connections between molecular size, reactivity, and isotopic characteristics show that DOC exists on a continuum from biologically reactive to recalcitrant. The driving mechanisms behind the creation and persistence of recalcitrant DOC remain unknown. We show mean recalcitrant DOC (isolated via solid‐phase extraction; SPE‐DOC) δ 13 C values are 1.3 ± 0.6‰ lower than mean total DOC δ 13 C between depth ranges 0–200 m and 2–4 km on three GO‐SHIP Repeat Hydrography cruises. Lowest observed δ 13 C values correlate with low ∆ 14 C and proximity to deep ocean hydrothermal systems. These data support the hypothesis that reworking of DOC through the microbial carbon pump is a key driver of the ocean's long‐term carbon sink. Mass‐balance modeling shows deep‐ocean DOC not captured by SPE is enriched in 13 C , highlighting the need for continued research on non‐retained DOC to predict mechanisms that drive ocean carbon storage.

  PublisherOA PDFDOI

• Pulses of South Atlantic water into the tropical North Atlantic since 1825 from coral isotopes

  Science Advances · 2023-12-15 · 5 citations

  articleOpen access

  Decadal and multidecadal changes in the meridional overturning circulation may originate from either the subpolar North Atlantic or the Southern Hemisphere. New records of carbon and oxygen isotopes from an eastern Martinique Island (Lesser Antilles) coral reveal irregular, decadal, double-step events of low ∆ 14 C and enhanced vertical mixing, high δ 18 O and high δ 13 C values starting in 1885. Comparison of the new and published ∆ 14 C records indicates that the last event (1956–1969) coincides with a widespread, double-step ∆ 14 C low of South Atlantic origin from 32°N to 18°S, associated with a major slowdown of the Caribbean Current transport between 1963 and 1969. This event and the past Martinique ∆ 14 C lows are attributed to pulses of northward advection of low ∆ 14 C Sub-Antarctic Mode Waters into the tropical Atlantic. They are coeval with changes of the tropical freshwater budget and likely driven by meridional overturning circulation changes since ~1880.

  PublisherOA PDFDOI

• TIME SERIES OF SURFACE WATER DISSOLVED INORGANIC CARBON ISOTOPES FROM THE SOUTHERN CALIFORNIA BIGHT

  Radiocarbon · 2023-09-19 · 5 citations

  articleOpen accessSenior author

  ABSTRACT Dissolved inorganic carbon (DIC) in ocean water is a major sink of fossil fuel derived CO 2 . Carbon isotopes in DIC serve as tracers for oceanic water masses, biogeochemical processes, and air-sea gas exchange. We present a timeseries of surface DIC δ 13 C and Δ 14 C values from 2011 to 2022 from Newport Beach, California. This is a continuation of previous timeseries (Hinger et al. 2010; Santos et al. 2011) that together provide an 18-year record. These data show that DIC Δ 14 C values have declined by 42‰ and that DIC δ 13 C values have declined by 0.4‰ since 2004. By 2020, DIC Δ 14 C values were within analytical error of nearby clean atmospheric CO 2 Δ 14 C values. These long-term trends are likely the result of significant fossil fuel derived CO 2 in surface DIC from air-sea gas exchange. Seasonally, Δ 14 C values varied by 3.4‰ between 2011 and 2022, where seasonal δ 13 C values varied by 0.7‰. The seasonal variation in Δ 14 C values is likely driven by variations in upwelling, surface eddies, and mixed layer depth. The variation in δ 13 C values appears to be driven by isotopic fractionation from marine primary producers. The DIC δ 13 C and Δ 14 C values record the influence of the drought that began in 2012, and a major upwelling event in 2016.

  PublisherOA PDFDOI

• Effect of marine sediment on the phase partitioning and isotopic content of riverine <scp>DOC</scp>

  Limnology and Oceanography · 2023-07-11 · 7 citations

  articleSenior author

  Abstract Rivers discharge significant quantities of dissolved organic carbon (DOC) to the ocean, yet biomarker and isotope studies suggest that terrigenous DOC makes up only a small amount DOC in the ocean. One of the removal pathways proposed for riverine DOC is sorption to marine sediments. This process is chemically selective, but whether sorption alters the isotopic composition of riverine DOC is unknown. Because there is isotopic variability across different organic compound classes, sorptive removal of DOC could also alter the isotopic composition of DOC. As a first step in addressing this question, we examined phase partitioning and isotopic composition of a riverine DOC standard in the presence of marine sediment particles. In a series of controlled experiments, the standard was mixed with marine sediment in 35‰ NaCl solution, then separated into particulate and dissolved phases for analyses of mass, δ 13 C, and ∆ 14 C of organic carbon (OC). Across a range of sediment OC to DOC mass ratios (from &lt; 0.1 to ~ 3), we found that: (1) sediment sorbed 0.8 μ g OC per mg of sediment; and (2) DOC compounds with higher ∆ 14 C and lower δ 13 C values relative to the bulk DOC was preferentially removed from solution. In effect, mixing a riverine DOC standard with marine sediment resulted in increased ∆ 14 C and decreased δ 13 C of the DOC that remained in solution. These results show that sorption of DOC to sediment can alter the isotopic content of riverine DOC.

  PublisherDOI

Recent grants

• Study of Seasonal Radiocarbon Variability in the Eastern Tropical Pacific During Periods of Decadal and Interannual Climate Shifts

  NSF · $513k · 2006–2010

• Radiocarbon in Dissolved Organic Matter in the Arctic Ocean

  NSF · $539k · 2010–2015

• CYCLING OF DISSOLVED ORGANIC MATTER IN THE PACIFIC AND ATLANTIC OCEANS USING RADIOCARBON

  NSF · $640k · 2015–2019

• Acquisition of Capability for Single-Compound AMS Measurement of Organic Matter at the W.M. Keck Carbon Cycle Accelerator Mass Spectrometry Facility at UC Irvine

  NSF · $411k · 2005–2008

• Radiocarbon in Dissolved Organic Matter in Ocean Water

  NSF · $571k · 2010–2014

Frequent coauthors

• Sheila Griffin

  Irvine University

  137 shared

• James E. Bauer

  The Ohio State University

  106 shared

• Pavel P. Povinec

  Comenius University Bratislava

  92 shared

• Ann P. McNichol

  Woods Hole Oceanographic Institution

  79 shared

• Peter M. Williams

  Center for Astrophysics Harvard & Smithsonian

  71 shared

• Brett D. Walker

  University of Ottawa

  66 shared

• Andrew Jull

  University of Auckland

  52 shared

• Herbert Haas

  49 shared

Labs

• Druffel Research GroupPI

  at the University of California, Irvine

Education

• Ph.D., Chemistry

  University of California San Diego