A5069831736- Geology and Paleoclimatology Research
- Methane Hydrates and Related Phenomena
- Isotope Analysis in Ecology
- Marine and coastal ecosystems
- Geological formations and processes
- Radioactive contamination and transfer
- Marine Biology and Ecology Research
- Geochemistry and Elemental Analysis
- Paleontology and Stratigraphy of Fossils
- Hydrocarbon exploration and reservoir analysis
- Atmospheric and Environmental Gas Dynamics
- Geological Studies and Exploration
- Marine and environmental studies
- Radioactive element chemistry and processing
- Arctic and Antarctic ice dynamics
- Oceanographic and Atmospheric Processes
- Heavy metals in environment
- Ocean Acidification Effects and Responses
- Geological and Geophysical Studies
- earthquake and tectonic studies
- Groundwater and Isotope Geochemistry
- Mercury impact and mitigation studies
- Geochemistry and Geologic Mapping
- Chromium effects and bioremediation
- Astro and Planetary Science
University of British Columbia
2013-2023
University of British Columbia Hospital
2023
Okanagan University College
2009-2021
Pacific Centre for Isotopic and Geochemical Research
2016
Pacific Environment
2016
NOAA Oceanic and Atmospheric Research
2016
Vancouver Biotech (Canada)
2016
Woods Hole Oceanographic Institution
1995-2009
Institut de France
2008
Sorbonne Université
1999
In two contrasting regions of the ocean, equatorial Pacific and southern δ 15 N core top sediments were strongly related to [NO 3 − ] in surface waters. With distance from equator Pacific, increased 7‰ 16‰ as decreased 8μM < 0.1 μM. Going 60° 30° S SE Indian Ocean, 5‰ 11‰ 25μM These results are strong evidence that sedimentary these is recording increasing isotopic enrichment near‐surface NO with its depletion by phytoplankton. case values for sinking particles collected at 150 m matched...
Particle fluxes measured with time series sediment traps deployed below 2000 m at 68 sites in the world ocean are combined satellite‐derived estimates of export production from overlying water to assess factors affecting transfer particulate organic matter surface deep water. Multiple linear regression is used derive an algorithm suggesting that efficiency carbon, defined as settling flux carbon normalized production, increases carbonate and decreases depth seasonality. The predicts >80%...
Dymond et al. (1992) have recently proposed an algorithm to reconstruct paleoproductivity from biogenic Ba (bio‐Ba) accumulation rates in sediments. Their equation is based on sediment trap data which indicate that C org /bio‐Ba ratios settling particles are higher the western Atlantic compared Pacific. From this observation they suggested flux of bio‐Ba seafloor may depend dissolved concentrations intermediate and deep waters significantly Pacific Atlantic. Accordingly, introduced a factor...
We report nitrogen isotope data for nitrate from transects of hydrocast and surface samples collected in the eastern Indian Pacific sectors Southern Ocean, focusing here on upper water column to study effect consumption by phytoplankton. The δ 15 N increases 1–2‰ deep into Antarctic summertime layer, due kinetic isotopic fractionation during uptake. Estimation uptake depth profiles yields values range 5–6‰ east sector 4–5‰ sector. Surface transect also yield 4–5‰. major uncertainty...
There is increasing evidence indicating that syndepositional redistribution of sediment on the seafloor by bottom currents common and can significantly affect mass accumulation rates. Notwithstanding its incidence, this process (generally referred to as focusing) often difficult recognize. If near synchronous deposition, stratigraphy not disturbed focusing easily be overlooked. Ignoring it, however, lead serious misinterpretations sedimentary fluxes, particularly when past changes in export...
We report analyses of the nitrogen isotopic composition nitrate in eastern Indian and Pacific sectors Southern Ocean. In this paper, we focus on subsurface data as well from deep waters other ocean basins. Nitrate δ 15 N is relatively invariant much abyssal (i.e., below 2.5 km), with a value 4.8±0.2‰ observed Lower Circumpolar Deep Water, North Atlantic central water. The invariance stems fundamentally completeness utilization most global surface ocean, Ocean being an important exception....
Treatment of diatom microfossils from Southern Ocean sediments with hot perchloric acid leaves a “diatom‐bound” N fraction which is 0–4‰ lower in δ 15 than the bulk sediment, typically 3‰ recent Antarctic ooze. Results surface indicate that early diagenetic changes sediment content and are not reflected diatom‐bound N, suggesting physically protected diagenesis by microfossil matrix. A meridional transect multicores Indian sector shows northward increase like sedimentary varies nitrate...
We have measured the carbon isotopic composition of particulate organic matter suspended in surface waters (POM) between 59°S and 30°S SW Indian Ocean during austral summer. In an attempt to further document pattern causes covariance POC‐δ 13 C [CO 2aq ], we concurrently water pCO 2 , temperature, salinity, nitrate concentration, POM chlorophyll a δ total dissolved inorganic carbon. While found previously reported general negative correlation also observed prominent maximum region...
Studies from the subtropical western and eastern Atlantic Ocean, using 231 Pa/ 230 Th ratio as a kinematic proxy for deep water circulation, provided compelling evidence strong link between climate rate of meridional overturning circulation (MOC) over last deglaciation. In this study, we present compilation existing new sedimentary records North cores 1710 4550 m depth. Comparing different depths provides insights into evolution geometry formation in during 20,000 years. The measured upper...
Variations in carbonate flux and dissolution, which occurred the equatorial Atlantic during last 24,000 years, have been estimated by a new approach that allows point‐by‐point determination of paleofluxes to seafloor. An unprecedented time resolution can thus be obtained sequencing relatively rapid events occurring deglaciation. The method is based on observations unsupported 230 Th into deep‐sea sediments nearly independent total mass close production rate. Thus excess activity used as...
High‐resolution records of opal, carbonate, and terrigenous fluxes have been obtained from a high‐sedimentation rate core (MD84‐527: 43°50′S; 51°19;′E; 3269 m) by normalization to 230 Th. This method estimates paleofluxes the seafloor on point‐by‐point basis distinguishes changes in sediment accumulation due variations vertical rain rates those syndepositional redistribution bottom currents. We also measured δ 15 N evaluate nitrate utilization overlying surface waters associated with...