A5078740265- Ionosphere and magnetosphere dynamics
- Geophysics and Gravity Measurements
- Solar and Space Plasma Dynamics
- Methane Hydrates and Related Phenomena
- Marine and coastal ecosystems
- Earthquake Detection and Analysis
- Heavy metals in environment
- Marine Biology and Ecology Research
- Microbial Community Ecology and Physiology
- Geochemistry and Elemental Analysis
- Environmental Toxicology and Ecotoxicology
- Mercury impact and mitigation studies
- Water Quality and Pollution Assessment
- Ocean Acidification Effects and Responses
- Electrochemical Analysis and Applications
- Water Quality Monitoring and Analysis
- Isotope Analysis in Ecology
- Toxic Organic Pollutants Impact
- Groundwater and Isotope Geochemistry
- Geology and Paleoclimatology Research
- Analytical Chemistry and Sensors
- Atmospheric and Environmental Gas Dynamics
- Molecular Sensors and Ion Detection
- Marine Toxins and Detection Methods
- Algal biology and biofuel production
GEOMAR Helmholtz Centre for Ocean Research Kiel
2016-2025
National Oceanography Centre
2010-2023
University of Southampton
2010-2023
Massachusetts Institute of Technology
2023
Universidade Federal de Santa Maria
2020
Royal Netherlands Institute for Sea Research
2015
University of Plymouth
1997-2008
University of Liverpool
1994-2008
Plymouth Marine Laboratory
2008
Centre d'Estudis Avançats de Blanes
2007
Siderophores are chelates produced by bacteria as part of a highly specific iron uptake mechanism. They thought to be important in the bacterial acquisition seawater and influence biogeochemistry ocean. We have identified quantified two types siderophores samples collected from Atlantic Ocean. These were hydroxamate siderophores, both ferrioxamine species representative more soluble marine characterized date. Ferrioxamine G was widely distributed surface waters throughout Ocean, while E had...
Iron (Fe) binding phases in two hydrothermal plumes the Southern Ocean were studied using a novel voltammetric technique. This approach, reverse titration–competitive ligand exchange–adsorptive cathodic stripping voltammetry, showed that on average 30±21% of dissolved Fe was stabilised by chemically labile to ligands. The conditional stability constant (log K′FeL) observed complexes 20.61±0.54 (mean±1 SD) for vent sites, intermediate between previous measurements deep ocean ligands (21.4–23;...
Abstract. Based on an international workshop (Gothenburg, 14–16 May 2008), this review article aims to combine interdisciplinary knowledge from coastal and open ocean research iron biogeochemistry. The major scientific findings of the past decade are structured into sections natural artificial fertilization, inputs estuarine systems, colloidal organic matter, biological processes. Potential effects global climate change, particularly acidification, biogeochemistry discussed. synthesized...
Coastal marine environments are contaminated globally with a vast quantity of unexploded ordnance and munitions from intentional disposal. These contain organic explosive compounds as well variety metals, represent point sources chemical pollution to waters. Most underwater originate World Wars at the beginning 20th century, metal housings have been impacted by extensive corrosion over course following decades. As result, risk munitions-related contaminant release water column is increasing....
With the common goal of more accurately and consistently quantifying ambient concentrations free metal ions natural organic ligands in aquatic ecosystems, researchers from 15 laboratories that routinely analyze trace speciation participated an intercomparison statistical methods used to model their most type experimental dataset, complexometric titration. All were asked apply techniques they familiar with synthetic titration data are typical those obtained by applying state-of-the-art...
Abstract Iron (Fe) bioavailability limits phytoplankton growth in vast ocean regions. Iron-rich dust uplifted from deserts is transported the atmosphere and deposited on surface. However, this a poor source of iron for most since dust-bound Fe poorly soluble seawater rapidly sinks out photic zone. An exception Trichodesmium , globally important, N 2 fixing, colony forming, cyanobacterium, which efficiently captures shuffles to its core. bacteria that reside within colonies carry diverse...
The ocean region along the latitude of 40oS in South Atlantic, characterized by enhanced primary productivity, forms a transition zone between nutrient replete but iron depleted Southern Ocean, and nitrate Subtropical Gyre. Here, we present distributions nutrient-type dissolved particulate trace metals (dTMs pTMs) including cadmium (Cd), nickel (Ni), copper (Cu), zinc (Zn) Atlantic from GEOTRACES GA10 cruises. Phytoplankton uptake, riverine atmospheric inputs shaped dTM pTM concentrations...
High-performance liquid chromatography−electrospray ionization mass spectrometry was applied to the detection of iron(III) complexes hydroxamate siderophores rhodotoluric acid, deferrioxamine B, and deferrichrome. Separation obtained using a polystyrene−divinylbenzene stationary phase. The retention responses ferrioxamine ferrichrome were optimal when gradient elution program with methanol 0.1% (v/v) formic acid as mobile phases used. These conditions also suitable for separation uncomplexed...
The pH of aqueous solutions is known to impact the chemical speciation trace metals. In this study we conducted titrations coastal seawaters with iron and copper at 7.91, 7.37 6.99 (expressed on total scale). Changes in concentration that complexed added ligands 1-nitroso-2-napthol salicylaldoxime respectively were determined by adsorptive cathodic stripping voltammetry - competitive ligand equilibrium (AdCSV-CLE). Interpretation results, assuming complexation a low discrete ligands, showed...
As a consequence of World War II, large amounts munition have been deposited in coastal waters. Deterioration the mines and bombs is resulting release compounds (MCs) like trinitrotoluene to surrounding marine environment, with potential implications ecosystems. Analytical methods thus far unable detect these reliably seawater. We present highly sensitive method for analysis MCs environment. combine preconcentration sample clean up by solid phase extraction separation detection ultra-high...
Abstract Upwelling ocean currents associated with oxygen minimum zones (OMZs) supply nutrients fuelling intense marine productivity. Perturbations in the extent and intensity of OMZs are projected future, but it is currently uncertain how this will impact fluxes redox‐sensitive trace metal micronutrients to surface ocean. Here we report seawater concentrations Fe, Mn, Co, Cd, Ni alongside redox indicator iodide/iodate Peruvian OMZ during 2015 El Niño event. The drove atypical upwelling...
The chemical speciation of iron (Fe) in oceans is influenced by ambient pH, dissolved oxygen, and the concentrations strengths binding sites organic matter (DOM). Here, we derived new nonideal competitive adsorption (NICA) constants for Fe(III) to marine DOM via pH-Fe titrations. We used calculate derive apparent solubility (SFe(III)app) water column across Peruvian shelf slope region. define SFe(III)app as sum aqueous inorganic species bound at a free Fe (Fe3+) concentration equal limiting...
Abstract Lateral fluxes (i.e., outwelling) of dissolved organic (DOC) and inorganic (DIC) carbon total alkalinity were estimated using radium isotopes at the groundwater, mangrove creek, continental shelf scales in Amazon region. Observations salinity creek indicated tidally driven groundwater exchange as main source carbon. Radium‐derived transport rates indicate that is exported out on timescales 22 ± 7 d. Bicarbonate was form (82% 11%) all samples, followed by DOC (13% 12%) CO 2 (5% 4%)....