A5024842130- Marine and coastal ecosystems
- Geochemistry and Elemental Analysis
- Microbial Community Ecology and Physiology
- Marine Biology and Ecology Research
- Geology and Paleoclimatology Research
- Mercury impact and mitigation studies
- Methane Hydrates and Related Phenomena
- Oceanographic and Atmospheric Processes
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Paleontology and Stratigraphy of Fossils
- Crystallography and molecular interactions
- Atmospheric and Environmental Gas Dynamics
- Hydrocarbon exploration and reservoir analysis
- Heavy metals in environment
- Groundwater and Isotope Geochemistry
- Isotope Analysis in Ecology
- Aquatic Ecosystems and Phytoplankton Dynamics
- Atmospheric chemistry and aerosols
- Drug Transport and Resistance Mechanisms
- Marine and environmental studies
- Trace Elements in Health
- Plant Water Relations and Carbon Dynamics
- Alzheimer's disease research and treatments
- Hydrological Forecasting Using AI
University of Hawaiʻi at Mānoa
2018-2024
University of Hawaii System
2018-2023
Southern California Earthquake Center
2021-2022
University of Southern California
2018-2022
Southern California University for Professional Studies
2020-2021
Woods Hole Oceanographic Institution
2016-2020
Bigelow Laboratory for Ocean Sciences
2020
Massachusetts Institute of Technology
2016
Washington University in St. Louis
2012-2014
Significance Iron limits marine production across one third of the surface ocean. The chemical form iron in these regions is unknown, but it well established that molecular speciation affects microbial competition for uptake. Here we show abundance and identity siderophores, strong iron-binding compounds secreted by microbes to enhance uptake, changes iron-replete iron-deficient South Pacific Ocean. In low-iron regions, amphiphilic siderophores are particularly abundant, suggesting a...
Abnormal interactions of Cu and Zn ions with the amyloid β (Aβ) peptide are proposed to play an important role in pathogenesis Alzheimer's disease (AD). Disruption these metal-peptide using chemical agents holds considerable promise as a therapeutic strategy combat this incurable disease. Reported herein two bifunctional compounds (BFCs) L1 L2 that contain both amyloid-binding metal-chelating molecular motifs. Both exhibit high stability constants for Cu(2+) Zn(2+) thus good chelators metal...
Significance Mineral dust has long been considered an important source of Fe to the surface ocean, especially in remote areas away from continental margins. However, anthropogenic derived fossil-fuel burning may also contribute waters. Here we show situ evidence seawater, based on concentrations and isotopic composition measured during a springtime cruise which transected North Pacific Ocean. Our results suggest that could play globally role marine productivity carbon cycling.
Although iron and light are understood to regulate the Southern Ocean biological carbon pump, observations have also indicated a possible role for manganese. Low concentrations in surface waters suggest manganese limitation is possible, but its spatial extent remains poorly constrained direct of marine cycle has been neglected by ocean models. Here, using available observations, we develop new global biogeochemical model find that phytoplankton over half cannot attain maximal growth rates...
Abstract Siderophores are strong iron‐binding molecules produced and utilized by microbes to acquire the limiting nutrient iron (Fe) from their surroundings. Despite importance as a component of ligand pool in seawater, data on distribution siderophores that use them limited. Here, we measured concentrations types dissolved during two cruises April 2016 June 2017 transited iron‐replete, low‐macronutrient North Pacific Subtropical Gyre through Transition Zone (NPTZ) iron‐deplete,...
Abstract Mesoscale eddies have been shown to support elevated dinitrogen (N 2 ) fixation rates (NFRs) and abundances of N ‐fixing microorganisms (diazotrophs), but the mechanisms underlying these observations are not well understood. We sampled two pairs mesoscale cyclones anticyclones in North Pacific Subtropical Gyre 2017 2018 compared our with seasonal patterns from Hawaii Ocean Time‐series (HOT) program. Consistent previous reports, we found that NFRs were anomalously high for this...
Organic ligands form strong complexes with many trace elements in seawater. Various metals can compete for the same ligand chelation sites, and final speciation of bound is determined by relative binding affinities, concentrations uncomplexed metal concentrations, association/dissociation kinetics. Different have a wide range affinities specificities. However, chemical composition these marine environment remains poorly constrained, which has hindered progress modeling speciation. In this...
Abstract. Cobalt is a nutrient to phytoplankton, but knowledge about its biogeochemical cycling limited, especially in the Pacific Ocean. Here, we report sections of dissolved cobalt and labile from US GEOTRACES GP16 transect South Pacific. The distribution closely tied extent intensity oxygen minimum zone eastern with highest concentrations measured at oxycline near Peru margin. Below 200 m, remineralization circulation produce an inverse relationship between that extends throughout basin....
Abstract. Cobalt is the scarcest of metallic micronutrients and displays a complex biogeochemical cycle. This study examines distribution, chemical speciation, biogeochemistry dissolved cobalt during US North Atlantic GEOTRACES transect expeditions (GA03/3_e), which took place in fall 2010 2011. Two major subsurface sources to were identified. The more prominent two was large plume emanating from African coast off eastern tropical coincident with oxygen minimum zone (OMZ) likely due...
Abstract In stratified oligotrophic waters, phytoplankton communities forming the deep chlorophyll maximum (DCM) are isolated from atmospheric iron sources above and remineralized below. Reduced supply leads to a minimum in dissolved (dFe) near 100 m, but it is unclear if limits growth at DCM. Here, we propose that natural addition events occur regularly with passage of mesoscale eddies, which alter dFe other nutrients relative availability light, can be used test for limitation This...
Abstract We examined the biogeochemical impact of paired mesoscale cyclones and anticyclones in spatial proximity (<200 km apart) North Pacific Subtropical Gyre. While previous studies have demonstrated that upwelling associated with intensification cyclonic eddies can supply nutrients supporting plankton productivity, we observed steeper vertical gradients inorganic increased nutrient fluxes due to diapycnal mixing during mature stage eddies. The was linked expansion eukaryotic...
Abstract Scarce dissolved surface ocean concentrations of the essential algal micronutrient zinc suggest that Zn may influence growth phytoplankton such as diatoms, which are major contributors to marine primary productivity. However, specific mechanisms by diatoms acclimate deficiency poorly understood. Using global proteomic analysis, we identified two proteins (ZCRP-A/B, Zn/Co Responsive Protein A/B) among four diatom species became abundant under limitation. Characterization using...
Abstract. The stoichiometry of biological components and their influence on dissolved distributions have long been interest in the study oceans. Cobalt has smallest oceanic inventory inorganic micronutrients hence is particularly vulnerable to by internal processes including euphotic zone uptake, remineralization, scavenging. Here we observe not only large variations dCo : P but also acceleration those ratios upper water column response several environmental processes. ecological total...
Abstract Cobalt is an important micronutrient for ocean microbes as it present in vitamin B 12 and a co‐factor various metalloenzymes that catalyze cellular processes. Moreover, when seawater availability of cobalt compared to biological demands, emerges being depleted seawater, pointing potentially limiting role. To properly account the potential role cobalt, there therefore need understand processes driving biogeochemical cycling and, particular, balance between external inputs internal...
From June to August 2018, the eruption of Kīlauea volcano on island Hawai'i injected millions cubic meters molten lava into nutrient-poor waters North Pacific Subtropical Gyre. The lava-impacted seawater was characterized by high concentrations metals and nutrients that stimulated phytoplankton growth, resulting in an extensive plume chlorophyll a detectable satellite. Chemical molecular evidence revealed this biological response hinged unexpectedly nitrate, despite negligible quantities...
Significance Photosynthetic phytoplankton are the foundation of marine ecosystems. Their growth in sunlit ocean depends on ample supply over a dozen essential elements. Of these elemental nutrients, metal cobalt is found at lowest concentrations seawater, but it unknown whether scarcity impacts growth. We have measured minimum requirements photosynthetic bacterium Prochlorococcus , which flourishes nutrient-poor regions where many other cannot survive. can grow with less than 50 atoms per...
Multifunctional metal chelators that can modulate the amyloid β (Aβ) peptide aggregation and its interaction with ions such as copper zinc hold considerable promise therapeutic agents for Alzheimer's disease (AD). However, specific rather than systemic chelation by these compounds is needed in order to limit any side effects. Reported herein are two novel small bifunctional chelators, 2-[2-hydroxy-4-(diethylamino)phenyl]benzothiazole (L1) 2-(2-hydroxy-3-methoxyphenyl)benzothiazole (L2),...
The 2018 eruption of Kīlauea was associated with massive input molten lava into the coastal ocean, which altered seawater chemistry and increased phytoplankton production. In plumes advected away from site entry, we observed elevated concentrations over a dozen metals relative to background unique isotopic compositions Fe, Cu, Ni, Cd Zn. δ56Fe iron released lower than basaltic, riverine Hawaiʻi, but similar observations other high-temperature hydrothermal vent fluids. However, rapid...
Abstract. Cobalt (Co) is an important bioactive trace metal that the cofactor in cobalamin (vitamin B12) which can limit or co-limit phytoplankton growth many regions of ocean. Total dissolved and labile Co measurements Canadian sector Arctic Ocean during U.S. GEOTRACES expedition (GN01) International Polar Year (GIPY14) revealed a dynamic biogeochemical cycle for this basin. The major sources were from shelf rivers, with only minimal contributions other freshwater (sea ice, snow) eolian...
Primary productivity in the nutrient-poor subtropical ocean gyres depends on new nitrogen inputs from fixers that convert inert dinitrogen gas into bioavailable forms. Temperature and iron (Fe) availability constrain marine fixation, both are changing due to anthropogenic warming. We examined physiological responses of globally important fixer, Crocosphaera watsonii across its full thermal range as a function availability. At lower end range, 22 27°C, growth, Nitrogen-specific Iron Use...