P.J. Statham

P.J. Statham
University of Southampton · National Oceanography Centre Southampton (NOCS)

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163
Publications
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Introduction

Publications

Publications (163)
Article
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The Gulf of Guayaquil (GG) is the most important tropical estuarine system of the eastern coast of South America, receiving an average water flow of about 1 650 m³ s⁻¹ from a river basin of approximately 33 700 km². The city of Guayaquil surrounds the inner coastal lagoon of the Estero Salado (ES) that empties into the GG. This coastal lagoon is of...
Preprint
Full-text available
16 17 Over the period 2016-2022 environmental data were obtained at four points in the northern section 18 of the tropical Estero Salado (ES), the inner coastal lagoon that flows through Guayaquil, the largest 19 city in Ecuador. Surface water from the more remote southern limit of the ES, El Morro was also 20 sampled in 2022. The study shows that...
Article
Full-text available
The offshore Gulf of Alaska—in the northeastern subarctic Pacific—is a high-nitrate, low-chlorophyll (HNLC) oceanic region where concentrations of dissolved iron (DFe) and zinc (DZn) are of the order ~0.1 nmol kg⁻¹ in surface waters. At the average winter mixed layer depth of ~120 m, DFe and DZn are of the orders ~0.1–0.2 nmol kg⁻¹ and ~1–2 nmol kg...
Article
Full-text available
Sampling water from shallow estuaries, rivers, or lakes, particularly where access is difficult, can be problematic. In estuaries at low tide, water depths can be less than a meter, and therefore conventional samplers based on vertical tubes of plastic or metal, such as Nansen and Niskin bottles, are inappropriate. During three consecutive years (2...
Article
Full-text available
The Gulf of Guayaquil (GG) is the most important tropical estuarine system of the eastern coast of South America, receiving an average water flow of about 1 650 m3 s-1 from a river basin of about 53 300 km2. The city of Guayaquil surrounds the inner coastal lagoon of the Estero Salado (ES) that empties into the GG. This estuary is of high social, c...
Article
Full-text available
The COVID-19 pandemic has obliged Governments all around the world to implement confinement and social distancing measures. Leisure and business activities on beaches and in ports have restricted direct and indirect contamination from, for example, plastics, hydrocarbon spillage, microbiological loads, and noise levels. This has led to temporarily...
Article
Whilst Sediment Profile Imaging (SPI) is a very widely used technique in the regulatory assessment of seabed environmental health, and in the study of seafloor sediment-biology interactions, the potential for SPI images to be used in a geochemical context has not been rigorously assessed. Here we have examined relationships between colour and geoch...
Article
Full-text available
Shelf sediments underlying temperate and oxic waters of the Celtic Sea (NW European Shelf) were found to have shallow oxygen penetrations depths from late spring to late summer (2.2–5.8 mm below seafloor) with the shallowest during/after the spring-bloom (mid-April to mid-May) when the organic carbon content was highest. Sediment porewater dissolve...
Article
Full-text available
Continental shelf sediments are globally important for biogeochemical activity. Quantification of shelf-scale stocks and fluxes of carbon and nutrients requires the extrapolation of observations made at limited points in space and time. The procedure for selecting exemplar sites to form the basis of this up-scaling is discussed in relation to a UK-...
Conference Paper
Iron (Fe) supplied by continental margins to the open ocean is considered to have a vital impact on marine eco-system productivity. However, Fe fluxes from many margin types are not well constrained, and the seasonal variability in Fe flux is critically unknown. Continental margins account for ~20 % of the global sea floor, and oxic shelf systems,...
Conference Paper
Continental shelf sediments represent a major source of essential trace elements to the world’s oceans, and are of notable importance in cycling of the micronutrient iron (Fe). However, considerable uncertainties remain concerning the release of such micronutrients, including the overall flux of Fe from sediments, seasonal variation in this flux, a...
Conference Paper
Shelf seas are globally important in contributing to the biogeochemical cycling of carbon and nutrients. Much of the benthic environment found in shelf seas comprise of relic permeable sands whereby advective pore-water flow processes govern the biogeochemical cycling within these sediments. To further elucidate our understanding of the biogeochemi...
Article
Full-text available
Iron (Fe) is an essential micronutrient for phytoplankton, and is scarce in many regions including the open Southern Ocean. The western Antarctic Peninsula (WAP), an important source region of Fe to the wider Southern Ocean, is also the fastest warming region of the southern hemisphere. The relative importance of glacial versus marine Fe sources is...
Article
Full-text available
Recent work has shown that glaciers are a globally significant source of the micronutrient Fe to the ocean. Polar regions are particularly susceptible to climate change and have been subject to pronounced warming in the past few decades. In response to this warming, the volume of glacial meltwater runoff from Greenland has increased. This meltwater...
Article
Full-text available
We present the first evidence of Fe(II) complexation by natural organic ligands in estuarine waters. Across five diverse river/estuary systems we find evidence of terrestrially derived ligands with binding constants (log KFe(II)L) mainly in the range 6–8. These Fe(II) ligands were stable over short time periods (1–2 days), generally equivalent to,...
Article
Purpose Diagenetic modelling, the mathematical simulation of the breakdown of sedimentary organic matter and subsequent fate of associated nutrients, has progressed to a point where complex, non-steady state environments can be accurately modelled. A genetic algorithm has never been used in conjunction with an early diagenetic model, and so we aim...
Article
Full-text available
The Greenland and Antarctic Ice Sheets cover ~\n10% of global land surface, but are rarely considered as active components of the global iron cycle. The ocean waters around both ice sheets harbour highly productive coastal ecosystems, many of which are iron limited. Measurements of iron concentrations in subglacial runoff from a large Greenland Ice...
Article
Full-text available
The Greenland and Antarctic Ice Sheets cover ~ 10% of global land surface, but are rarely considered as active components of the global iron cycle. The ocean waters around both ice sheets harbour highly productive coastal ecosystems, many of which are iron limited. Measurements of iron concentrations in subglacial runoff from a large Greenland Ice...
Article
Full-text available
Supply of Fe to high nitrate low chlorophyll (HNLC) waters, such as the Southern Ocean, is the principle limiting factor for primary production and the associated carbon uptake. Glacial meltwaters have recently been shown to provide a globally substantial input of Fe to both Antarctic and Arctic polar waters. The particulate Fe flux in glacial runo...
Article
A phytoplankton bloom shown to be naturally iron (Fe) induced occurs north of the Crozet Islands (Southern Ocean) every year, providing an ideal opportunity to study dissolved trace metal distributions within an island system located in a high nutrient low chlorophyll (HNLC) region. We present water column profiles of dissolved nickel (Ni), zinc (Z...
Article
Full-text available
A phytoplankton bloom shown to be naturally iron (Fe) induced occurs north of the Crozet Islands (Southern Ocean) every year, providing an ideal opportunity to study dissolved trace metal distributions within an island system located in a high nutrient low chlorophyll (HNLC) region. We present water column profiles of dissolved nickel (Ni), zinc (Z...
Article
Previous studies have revealed considerable Cd isotope fractionations in seawater, which can be used to study the marine cycling of this micronutrient element. The low Cd concentrations that are commonly encountered in nutrient-depleted surface seawater, however, pose a particular challenge for precise Cd stable isotope analyses. In this study, we...
Article
Whilst there is increasing evidence for the presence of stabilized Fe(II) associated with organic matter in aquatic environments, the absence of a reliable method for determining Fe(II) speciation in solution has inhibited the study of this aspect of Fe biogeochemistry. A technique is described here for the determination of Fe(II) organic complexat...
Article
Full-text available
Abstract Pyrite and chalcopyrite are the two most abundant sulphides observed in seafloor hydrothermal systems. The alteration of sulphides is primarily controlled by reactions on the mineral surfaces and Fe(II)-oxidising bacteria closely related to Marinobacter aquaeolei are thought to play a major role in iron oxidation under circumneutral condit...
Article
Full-text available
Microfluidic technology permits the miniaturization of chemical analytical methods that are traditionally undertaken using benchtop equipment in the laboratory environment. When applied to environmental monitoring, these "lab-on-chip" systems could allow high-performance chemical analysis methods to be performed in situ over distributed sensor netw...
Article
We present ex situ sediment incubation results from the California and Oregon shelves and compare the calculated benthic flux of dissolved Fe with those from in situ incubations and pore water concentration profiles. We also examine the influence of oxygen depletion and sediment re-suspension on benthic Fe exchange. Ex situ incubation of the Califo...
Article
In-situ sensors are of crucial importance for gaining a deeper understanding of key physico-chemical processes that occur in the ocean. Current laboratory methods cannot provide the spatial and temporal resolution needed to characterise the chemical parameters of marine ecosystems and they are expensive, time consuming, and are often affected by ma...
Article
The investigation of the distribution of trace elements between the dissolved, colloidal and particulate phases within a hydrothermal plume is key to understanding plume processes. Particulate and colloidal size fractions of four trace elements (iron, manganese, copper and phosphorus) along with the dissolved size fraction of iron, manganese and co...
Article
The fate and cycling of macronutrients introduced into estuaries depend upon a range of interlinked processes. Hydrodynamics and morphology in combination with freshwater inflow control the freshwater flushing time, and the timescale for biogeochemical processes to operate that include microbial activity, particle-dissolved phase interactions, and...
Article
Volcanogenic sediments are typically rich in Fe and Mn-bearing minerals that undergo substantial alteration during early marine diagenesis, however their impact on the global biogeochemical cycling of Fe and Mn has not been widely addressed. This study compares the near surface (0–20 cm below sea floor [cmbsf]) aqueous (<0.02 μm) and aqueous + coll...
Article
Chemoautotrophic production in seafloor hydrothermal systems has the potential to provide an important source of organic carbon that is exported to the surrounding deep-ocean. While hydrothermal plumes may export carbon, entrained from chimney walls and biologically rich diffuse flow areas, away from sites of venting they also have the potential to...
Article
The in situ annular flume, Voyager II, was deployed at three sites in the North Sea in order to investigate resuspension events, to determine the physical characteristics of the seabed, to determine the threshold of resuspension of the bed and to quantify erosion rates and erosion depths. These are the first controlled, in situ flume experiments to...
Article
Full-text available
Despite a large macronutrient reservoir, the Southern Ocean has low levels of chlorophyll, primarily due to low iron availability. Exceptions to this situation are island systems where natural terrestrial iron inputs allow the development of large blooms. Particulate organic carbon (POC) and particulate (labile and refractory) iron analyses were pe...
Conference Paper
Early diagenesis (ED), the physical and biogeochemical changes undergone in surficial sediments, plays an important role in the biogeochemical cycles of key elements (carbon, nitrogen and oxygen) in highly productive shelf-seas. Modelling the process uses a relatively simple set of mathematical equations to represent the transport and reaction term...
Article
This paper reports on investigations into interferences with the measurements of nanomolar nitrate + nitrite and soluble reactive phosphate (SRP) in oceanic surface seawater using a segmented continuous flow autoanalyser (SCFA) interfaced with a liquid-waveguide capillary flow-cell (LWCC). The interferences of silicate and arsenate with the analysi...
Article
Full-text available
The effect of artificial acidic polysaccharides (PS) and exudates of Phaeodactylum tricornutum on the half-life of Fe(II) in seawater was investigated in laboratory experiments. Strong photochemical hydrogen peroxide (H2O2) production of 5.2 to 10.9 nM (mg C)−1 h−1 was found in the presence of PS and diatom exudates. Furthermore when illuminated wi...
Article
Full-text available
Pore-fluid Fe isotopes may be a unique tracer of sediment respiration by dissimilatory Fe reducing bacteria, but to date pore-fluid Fe isotope measurements have been restricted to continental shelf settings. Here we present the δ56Fe of pore-fluids from 2 distinct sedimentary settings: (1) a riverine-dominated site on the northern California margin...
Article
Full-text available
The effect of artificial acidic polysaccharides (PS) and exudates of Phaeodactylum tricornutum on the half-life of Fe(II) in seawater was investigated in laboratory experiments. Strong photochemical hydrogen peroxide (H2O2) production of 5.2 to 10.9 nM (mg C)−1 h−1 was found in the presence of PS and diatom exudates. Furthermore when illuminated wi...
Article
Fe isotopes are a potential tool for tracing the biogeochemical redox cycle of Fe in the ocean. Specifically, it is hypothesized that Fe isotopes could enable estimation of the contributions from multiple Fe sources to the dissolved Fe budget, an issue that has received much attention in recent years. The first priority however, is to understand an...
Article
Natural iron fertilization processes are occurring around the Crozet Islands (46°26′S–52°18′E), thus relieving the water masses from the normally encountered High Nutrients Low Chlorophyll (HNLC) conditions of the Southern Ocean. During austral summers 2004/2005 and 2005/2006, iron and aluminium concentrations were investigated in large particles (...
Conference Paper
Full-text available
Some regions of the global ocean, notably the Southern Ocean, have high levels of macronutrients yet low levels of chlorophyll (the high nutrient, low chlorophyll or HNLC condition). Numerous artificial iron fertilization experiments conducted in the Southern Ocean have resulted in enhanced phytoplankton biomass and macronutrient drawdown. However...
Article
Full-text available
The release of dissolved iron from artificial aggregates formed from oxic natural coastal water and senescent phytoplankton material was demonstrated under dark conditions. The rate of release was controlled by the amount of reducible Fe(III) available, and appears to be limited by the competing oxidation of Fe(II). Molecular (16S rRNA gene) analys...
Article
Full-text available
The addition of iron to high-nutrient, low-chlorophyll regions induces phytoplankton blooms that take up carbon. Carbon export from the surface layer and, in particular, the ability of the ocean and sediments to sequester carbon for many years remains, however, poorly quantified. Here we report data from the CROZEX experiment in the Southern Ocean,...
Article
We present the first extensive dataset for copper (Cu) isotopes in rivers, as well as preliminary data for estuaries and seawater. Rivers exhibit a range in dissolved δ65Cu (relative to NIST SRM 976) of + 0.02 to + 1.45 per mil (‰). The discharge-weighted average dissolved δ65Cu and Cu concentration for the studied rivers, representing around 25% o...
Article
We have conducted a study of hydrothermal plumes overlying the Mid-Atlantic Ridge near 5° S to investigate whether there is a significant export flux of dissolved Fe from hydrothermal venting to the oceans. Our study combined measurements of plume-height Fe concentrations from a series of 6 CTD stations together with studies of dissolved Fe speciat...
Article
Full-text available
Environmental context. The North Sea, which is of significant ecological, economic and recreational value to NW Europe, has for many years received enhanced inputs of contaminant metals arising from human activity around its shores. Fluxes of copper, nickel, zinc, chromium and other constituents throughout the southern North Sea were estimated usin...
Article
Over much of the world’s surface oceans, nitrate and phosphate concentrations are below the limit of detection (LOD) of conventional techniques of analysis. However, these nutrients play a controlling role in primary productivity and carbon sequestration in these waters. In recent years, techniques have been developed to address this challenge, and...
Article
Full-text available
In this paper, the kinetics of Mo and V (100 mM) uptake on ferrihydrite (FHY) were evaluated in batch, mono-sorbate systems at pH between 4 and 9, and in bi-sorbate systems in the presence of P (100 mM) at pH 7. In the Mo and V single-sorbate experiments, 100% adsorption was observed at pH values below 6 and 8, respectively. Above the point of zero...
Chapter
IntroductionAnalytical strategySamplingFiltrationSample storageAnalysisReagents and standardsAnalytical procedureData analysisMethod performanceIdentification and solution of common problems
Article
This special issue describes the findings of the first planned natural iron fertilisation experiment in the Southern Ocean, the CROZet natural iron bloom and EXport experiment (CROZEX), which took place from November 2004 to January 2005. The bloom that occurs annually north of the Crozet Islands and Plateau (Crozet) was surveyed and compared with...
Article
Elevated levels of productivity in the wake of Southern Ocean island systems are common despite the fact that they are encircled by high-nutrient low-chlorophyll (HNLC) waters. In the Crozet Plateau region, it has been hypothesized that iron from island runoff or sediments of the plateau could be fueling the austral summer phytoplankton bloom. Here...
Article
The annual phytoplankton bloom occurring north of the Crozet Plateau provides a rare opportunity to examine the hypothesis that natural iron fertilization can alleviate high-nutrient low-chlorophyll (HNLC) conditions normally associated with the Southern Ocean. Therefore, during CROZet natural iron bloom and EXport experiment (CROZEX), a large mult...
Conference Paper
Full-text available
In deep-ocean hydrothermal plumes molybdenum and vanadium are known to be readily scavenged by freshly formed iron oxihydroxides nanoparticles (i.e., ferrihydrite, FH) forming during the oxidation of hydrothermal vent fluids via mixing with seawater. These scavenging processes have important implications for the cycling and budget of Mo and V in th...
Conference Paper
Molybdenum a highly soluble and conservative element is readily scavenged by iron oxyhydroxides (i.e., ferrihydrite) forming in the oxidized portion of ‘black smoker’ plumes. Its sequestration and build up in sediments leads to the formation of concentration gradients across the sediment-water interface and therefore strongly influences the cycling...
Article
Shelf break systems are highly dynamic environments. However little is known about the influence that benthic interactions and water mass mixing may have on vertical distributions of iron in these systems. Dissolved Fe (< 0.4 μm) concentrations were measured in samples from nine vertical profiles across the upper slope (150–2950 m water depth) at t...
Article
The concentrations of Cr (III) and Cr (VI) were determined in the upper 500 m of the Sargasso Sea at different times of the year. Total Cr concentrations ranged between 2.5 and 4.5 nM, and the predominant species of Cr was the thermodynamically favoured Cr (VI). Cr (III) concentrations were greatest during periods of high biological activity, as in...
Article
The hydrology of ice sheets is of current interest because of the linkage between water storage in high pressure subglacial drainage systems and the dynamics of ice sheet margins. However, little is known about the hydrology and hydrochemistry of runoff from the Greenland Ice Sheet (GIS) or the nature of the subglacial drainage system beneath the i...
Article
In the context of the iron hypothesis and natural Fe fertilization by islands, the biogeochemical characteristics of the water masses located in the North and South wake of the Crozet Islands were studied during CROZEX, a large multidisciplinary study performed between November 2004 and January 2005. Near real-time satellite ocean colour data (SeaW...
Conference Paper
To date the development of in situ chemical and biological sensors has focused on the production of macro instruments for single point deployment. With the exception of oxygen sensors and biological sensors based on fluorometry (that are now commercially available) chemical and biological sensors are not able to make repeated synoptic measurements...
Article
Full-text available
A series of shipboard experiments using the radiotracer Cd-109 investigated the role of phytoplankton and bacteria in the uptake of dissolved Cd in the English Channel and Celtic Sea. The results demonstrate that Cd uptake is related to rates of primary production and bacterial numbers. Statistical analysis of plankton species abundance infer that...
Article
The stable isotope compositions of Zn and Cu in natural materials are newly available for measurement with the advent of multiple-collector inductively coupled mass spectrometry (MC–ICPMS). Although the oceans are prime scientific targets, no progress has been made as yet because of considerable analytical challenges involving the low concentration...
Article
Loch Etive is a fjordic system on the west coast of Scotland. The deep waters of the upper basin are periodically isolated, and during these periods oxygen is lost through benthic respiration and concentrations of dissolved manganese increase. In April 2000 the autonomous underwater vehicle (AUV) Autosub was fitted with an in situ dissolved mangane...
Article
Tritium (3H) concentrations in tree rings should reflect ambient precipitation. Thus, to improve knowledge of the 3H input to the oceans, we developed a new technique to measure 3H concentrations in annual tree rings. Measurements of 3H were made on cellulose, the primary constituent of wood, as the isotopic signal of its carbon bound hydrogen atom...
Article
Iron- and zinc-enrichment experiments were carried out at Ocean Station Papa in the subarctic North Pacific. In iron-enriched treatments, phytoplankton chlorophyll a (Chl a) increased 20-fold (9.7 m gL 21 ) above the concentration on day zero. No stimulation of Chl a production or nitrate drawdown was observed on addition of zinc alone compared to...
Article
Deep-sea hydrothermal activity cycles the entire volume of the global ocean through deep-sea hydrothermal plumes at least every 4–8 × 103 a, a rapid timescale that is comparable to global deep-ocean mixing. An important process within hydrothermal plumes is the oxidation of dissolved iron discharged with vent fluids, leading to the co-precipitation...