A5015788292- Marine and coastal ecosystems
- Isotope Analysis in Ecology
- Marine Biology and Ecology Research
- Geology and Paleoclimatology Research
- Ocean Acidification Effects and Responses
- Methane Hydrates and Related Phenomena
- Microbial Community Ecology and Physiology
- Atmospheric and Environmental Gas Dynamics
- Arctic and Antarctic ice dynamics
- Groundwater and Isotope Geochemistry
- Archaeology and ancient environmental studies
- Hydrocarbon exploration and reservoir analysis
- Marine Bivalve and Aquaculture Studies
- Oil Spill Detection and Mitigation
- Atmospheric chemistry and aerosols
- Toxic Organic Pollutants Impact
- Metabolomics and Mass Spectrometry Studies
- Water Quality Monitoring and Analysis
- Diatoms and Algae Research
- Radioactive element chemistry and processing
- Radioactive contamination and transfer
- Cultural Heritage Materials Analysis
- Analytical Chemistry and Chromatography
- Geochemistry and Elemental Analysis
- Membrane Separation Technologies
University of California, Irvine
2014-2025
University of Ottawa
2019-2025
Ottawa University
2024
Irvine University
2018-2024
University of California, Santa Cruz
2007-2021
University of Arizona
2013
Woods Hole Oceanographic Institution
2011
Abstract Marine dissolved organic carbon (DOC) is a major global reservoir, yet its cycling remains poorly understood. Previous work suggests that DOC molecular size and chemical composition can significantly affect bioavailability. Thus, may control radiocarbon age (via Δ 14 C). Here we show correlated to C in the Pacific Ocean. Our results, based on series of increasing fractions from three depths Pacific, with size. We use size‐age distribution model predict ultrafiltered DOC. The...
Abstract Marine dissolved organic carbon (DOC) is produced in the surface ocean though its radiocarbon ( 14 C) age deep thousands of years old. Here we show that ≥10% DOC North Atlantic postbomb origin and C prebomb ≥4900 year, ~900 year older than previous estimates. We report ages South are intermediate between values Southern Ocean. Finally, conclude a portion more dynamic previously reported.
Abstract Dissolved organic carbon (DOC) in the global oceans is an important long‐term 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 creation persistence of recalcitrant remain unknown. We mean (isolated via solid‐phase extraction; SPE‐DOC) δ 13 C values are 1.3 ± 0.6‰ lower than total depth ranges 0–200 m 2–4 km three GO‐SHIP Repeat Hydrography...
Abstract The composition and cycling dynamics of marine dissolved organic carbon (DOC) have received increased interest in recent years; however, little research has focused on the refractory, low molecular weight (LMW) component that makes up majority this massive C pool. We measured stable isotopic (δ 13 C), radioisotopic (Δ 14 compositional (C/N, solid‐state NMR) properties separately isolated high (HMW) LMW DOC fractions collected using a coupled ultrafiltration solid phase extraction...
During wildfires and fossil fuel combustion, biomass is converted to black carbon (BC) via incomplete combustion. BC enters the ocean by rivers atmospheric deposition contributing marine dissolved organic (DOC) pool. The fate of considered reside in DOC pool, where oldest 14 C ages have been measured (>20,000 y), implying long-term storage. largest exchangeable pool oceans, yet most (>80%) remains molecularly uncharacterized. Here, we report measurements on size-fractionated (DBC)...
Earth’s deep ocean holds a vast reservoir of dissolved organic carbon, traditionally considered old and resistant to microbial degradation. Radiocarbon analyses indicate the hidden occurrence younger carbon components, assumed be accessible deep-sea microorganisms but not yet demonstrated. Using compound-class radiocarbon analysis, molecular characterization, bioassay experiments, we provide direct evidence for rapid utilization young, labile, high–molecular weight proteinaceous material in...
Abstract The Canadian Arctic is warming four times faster than the global average, yet impact of this perturbation on marine carbon cycle remains unknown. Dissolved inorganic (DIC) stable isotope (δ 13 C) and radiocarbon (Δ 14 values are powerful tools for tracing water mass transport, residence cycling. While hydrography Archipelago (CAA) well documented, few DIC δ C Δ exist region. Here, we present new depth profiles from 19 stations across CAA sampled in 2021 place them into context five...
Abstract Geochemical and stable isotope measurements in the anoxic marine zone (AMZ) off northern Chile during periods of contrasting oceanographic conditions indicate that microbial processes mediating sulfur nitrogen cycling exert a significant control on carbonate chemistry (pH, A T , DIC p CO 2 ) this region. Here we show 2015, large isotopic fractionation between POC, N deficit AMZ waters predominance situ dark carbon fixation by sulfur-driven autotrophic denitrification addition to...
Compound-specific radiocarbon analysis (CSRA) of amino acids (AAs) is great interest as a proxy for organic nitrogen (N) cycling rates, dating archeological bone collagen, and investigating processes shaping the biogeochemistry global N reservoirs. However, recoverable quantities individual compounds from natural samples are often insufficient ((14)C) analyses (<50 μg C). Constraining procedural carbon (C) blanks their isotopic contributions critical reporting accurate CSRA measurements....
Abstract Dissolved organic carbon (DOC) is the largest pool of exchangeable in ocean. However, less than 10% DOC has been molecularly characterized deep ocean to understand DOC's recalcitrance. Here we analyze radiocarbon ( 14 C) depleted, and presumably refractory, low molecular weight (LMW) from North Central Pacific using atomic force microscopy produce first atomic‐resolution images individual LMW molecules. We evaluate surface chemical structures context their relative persistence...
Abstract We report marine dissolved organic carbon (DOC) concentrations, and DOC ∆ 14 C δ 13 values in seawater collected from the central Pacific. Surface are low equatorial polar regions where upwelling occurs high subtropical dominated by downwelling. A core feature of these data is that aging (682 ± 86 years) inorganic (643 40 Antarctic Bottom Water between 54.0°S 53.5°N similar. These estimates minimum due to mixing with deep waters. also observe (−550‰ −570‰) depths 2,000 3,500 m North...
Abstract We report marine dissolved organic carbon (DOC) concentrations, and DOC Δ 14 C δ 13 values in seawater collected from the Southern Ocean eastern Pacific GOSHIP cruise P18 2016/2017. The aging of circumpolar deep water northward 69°S to 20°N was similar that measured inorganic same samples, indicating transport waters is primary control DIC DOC. Low ∆ measurements between 1,200 3,400 m depth may be evidence a source produced nearby hydrothermal ridge systems (East Rise).
RATIONALE Compound‐specific isotope analysis of individual amino acids (CSI‐AA) is a powerful new tool for tracing nitrogen (N) source and transformation in biogeochemical cycles. Specifically, the δ 15 N value phenylalanine (δ Phe ) represents an increasingly used proxy signatures, with particular promise paleoceanographic applications. However, current derivatization/gas chromatography methods require expensive relatively uncommon instrumentation, have low precision, making many potential...
We report the interseasonal variation in bulk elemental and stable isotopic ( δ 13 C, 15 N) composition of dissolved particulate organic matter (DOM, POM) during a high‐resolution time series (2007–2009) on Big Sur coast. In addition to variations, we explore relationships between physical size reactivity (i.e., composition) exportable (OM) pools, characterize size‐fractionated POM DOM pools within this potentially high‐nutrient, low‐chlorophyll (HNLC) California upwelling region. Average...
Abstract Dissolved organic carbon (DOC) in the ocean is thousands of 14 C years old, yet a portion DOC cycles on much shorter time scales (days to decades). We present measurements Arctic Ocean and estimate that ≥8% deep Eurasian Basin contains bomb C. While this limited data set, there appears be selective loss modern surface halocline waters open Beaufort Sea versus slope. At one stations, linear relationship between Δ values previously measured total hydrolysable amino acid concentrations...