Edward A Boyle

Massachusetts Institute of Technology | MIT · Department of Earth Atmospheric and Planetary Sciences

Although the crucial role that dissolved trace metals (dTMs) play in both carbon cycling and climate have been revealed over the past three decades, much about the oceanic budgets of dTMs remains unknown. Rivers are one of the most important dTM sources to the ocean, and estuaries are a key interface between land and ocean. However, our understandi...

Reversible scavenging, the oceanographic process by which dissolved metals exchange onto and off sinking particles and are thereby transported to deeper depths, has been well established for the metal thorium for decades. Reversible scavenging both deepens the elemental distribution of adsorptive elements and shortens their oceanic residence times...

Lead (Pb) isotopes are widely used in tracing processes that transport Pb within the environment due to the globally spread Pb pollution. In today’s ocean, Pb is mainly sourced from anthropogenic emissions and is removed by particle scavenging. However, recent efforts involving Pb isotopes have started to indicate that sediments at ocean boundary,...

Since North America and European countries phased out leaded gasoline, Asia has become the major contemporary lead (Pb) source to the marine environment, at first from leaded gasoline, but more recently from coal burning and other high‐temperature industrial activities (Flegal et al., 2013, https://doi.org/10.1080/10643389.2012.671738; Lee et al.,...

Material fluxes at the land-ocean interface impact seawater composition and global cycling of elements. However, most attention has been focused on the fluvial dissolved fluxes. For elements like lead (Pb), whose fluvial particulate flux into the ocean is two orders of magnitude higher than the dissolved counterpart, the role of particulates in ele...

Anthropogenic lead (Pb) has been the overwhelming Pb source to the global ocean, primarily contributed from Pb gasoline and industrial emissions. However, since Pb gasoline has been phased out globally, questions about whether there was a decrease in seawater Pb concentration, or if there are other sources taking over remains unclear in Southeast A...

Significance Chromium isotopes have been used to study ancient earth atmospheric oxygen levels and seem promising as a paleoredox proxy. However, few studies have focused on its cycling in the modern ocean. Here we analyzed samples from oxygen-deficient zones and investigated how chromium speciation and isotopes respond to extremely low oxygen envi...

Most of the lead (Pb) in today's ocean is from human activities, although natural sources contribute small amounts of Pb that are usually masked by massive anthropogenic emissions. In the U.S. GEOTRACES East Pacific Section (GP16), anthropogenic Pb is observed throughout the water column, and as seen elsewhere in the Pacific, Pb concentrations are...

Cr isotope geochemistry is being explored in the context of a variety of geological problems as well as the environmental remediation of pollutant Cr(VI). There is a strong Cr isotope fractionation during reduction of oxidized Cr(VI) to reduced Cr(III). We present chromium concentration and Cr isotope data for samples from highly reducing environme...

Ocean time‐series sites are influenced by both temporal variability, as in situ conditions change, as well as spatial variability, as water masses move across the fixed observation point. To remove the effect of spatial variability, this study made sub‐daily Lagrangian observations of trace elements and isotopes (Al, Sc, Mn, Fe, Co, Ni, Cu, Zn, Cd,...

Trace element (TE) fluxes and their residence times (Fe, Mn, Cu, Pb, Cd, and V) within the surface ocean were determined along the GEOTRACES East Pacific Zonal Transect (GP16/EPZT) and found to reflect the diverse physical and geochemical conditions encountered across the track. The TE flux from atmospheric deposition, vertical mixing, and upwellin...

The environmental impacts of the urban expansion in Rio de Janeiro was evaluated based on the historical accumulation of black carbon (BC), aliphatic (AHs) and aromatic hydrocarbons (PAHs) and sterols in a sediment core retrieved from Botafogo Cove. BC related to oil combustion sources increased significantly since the 1990s. AHs were associated wi...

The ratio of barium to calcium in coral skeletons (Ba/Ca coral ) is broadly used as a proxy for tracking terrestrial/river runoff. There are, however, inconsistencies in Ba/Ca coral records that have prompted caution in its reliability as an environmental proxy. Direct comparisons between in-situ seawater measurements and coral Ba/Ca are therefore...

Anthropogenic activities have increased the fluxes of many trace metals into the oceans, changing their concentrations and distribution patterns. Despite their low dissolved concentrations, a number of these metals can still pose human and ecological risks. Some of these metals are well known (e.g. Pb, Hg), while others, such as the rare earth elem...

The GEOVIDE cruise, a collaborative project within the framework of the international GEOTRACES programme, was conducted along the French-led section in the North Atlantic Ocean (Section GA01), between 15 May and 30 June 2014. In this special issue (https://bg.copernicus.org/articles/special_issue900.html), results from GEOVIDE, including physical...

Two sediment cores collected in the shelf off Rio de Janeiro (RJ13-01B: 10.8 cal kyr BP, and RJ13-02B: 4.7 cal kyr BP) were investigated in high-resolution to evaluate changes in sedimentary processes and paleoclimatic and paleoceanographic variability during the Holocene in the Southeastern Brazil. Information from inorganic proxies of continental...

During the 2014 GEOVIDE transect, seawater samples were collected for dissolved Pb and Pb isotope analysis. These samples provide a high-resolution “snapshot” of the source regions for the present Pb distribution in the North Atlantic Ocean. Some of these stations were previously occupied for Pb from as early as 1981, and we compare the 2014 data w...

The GEOVIDE cruise, a collaborative project within the framework of the international GEOTRACES programme, was conducted along the French-led section in the North Atlantic Ocean (Section GA01), between 15 May and 30 June 2014. In this Special Issue, results from GEOVIDE, including physical oceanography and trace element and isotope cyclings, are pr...

Although the cycling of chromium (Cr) in the ocean may have direct implications on the Cr isotope system's application as a paleo-redox proxy, little seawater Cr isotope data has been published. This may be partly due to the analytical challenges associated with the preconcentration and the purification of the nano-molar trace metal Cr from the sea...

The GEOTRACES Intermediate Data Product 2017 (IDP2017) is the second publicly available data product of the international GEOTRACES programme, and contains data measured and quality controlled before the end of 2016. The IDP2017 includes data from the Atlantic, Pacific, Arctic, Southern and Indian oceans, with about twice the data volume of the pre...

The GEOTRACES Intermediate Data Product 2017 (IDP2017) is the second publicly available data product of the international GEOTRACES programme, and contains data measured and quality controlled before the end of 2016. The IDP2017 includes data from the Atlantic, Pacific, Arctic, Southern and Indian oceans, with about twice the data volume of the pre...

During the 2014 GEOVIDE transect, seawater samples were collected for dissolved Pb and Pb isotope analysis. These samples provide a high resolution snapshot of the source regions for the present Pb distribution in the North Atlantic Ocean. Some of these stations were previously occupied for Pb from as early as 1981, and we compare the 2014 data wit...

Pb is a trace metal that tracks anthropogenic pollution in natural environments. Despite recent leaded petrol phase out around Southeast Asia, the region's growth has resulted in continued exposure of Pb from a variety of sources. In this study, sources of Pb into Singapore, a highly urbanised city-state situated in the central axis of Southeast As...

The evolution of the impacts of anthropogenic activities in Todos os Santos Bay was evaluated by profiles of trace metals and Pb isotopes determined in sediment cores. Fluxes of metals increased up to 12, 4 and 2 times for Cu, Pb, and Zn, respectively, compared to those recorded in the beginning of the 20th century. Stable Pb isotopes identified a...

In recent decades, the flow of fixed—that is, biologically usable—nitrogen from human activities into the environment has grown substantially. The sources include excess production and use of nitrogen fertilizers; ammonia emitted from animal husbandry and sewage; and nitrogen oxides emitted by automobiles, airplanes, and fossil fuel power plants. T...

Thorium and uranium isotopes (²³²Th, ²³⁰Th, ²³⁸U, and ²³⁴U) were investigated to refine their use for estimating mineral dust deposition and Fe delivery to the ocean. U concentrations and isotope ratios were consistent with conservative behavior and can safely be described using published U-salinity relationships and global average seawater isotopi...

Atmospheric aerosols are the dominant source of Pb to the modern marine environment, and as a result, in most regions of the ocean the Pb isotopic composition of dissolved Pb in the surface ocean (and in corals) matches that of the regional aerosols. In the Singapore Strait, however, there is a large offset between seawater dissolved and coral Pb i...

Despite its potential linkages with North Atlantic climate, the variability in Saharan dust transport to the western North Atlantic over the past two millennia has not been well-characterized. A factor of 4 increase in dust production in sub-Saharan Africa has been attributed to the onset of Sahelian agriculture 200 yr ago. The regional extent of t...

The Southeast Pacific Ocean is a severely understudied yet dynamic region for trace metals such as iron, since it experiences steep redox and productivity gradients in upper waters and strong hydrothermal iron inputs to deep waters. In this study, we report the dissolved iron (dFe) distribution from seven stations and Fe isotope ratios (δ56Fe) from...

Reconstructing the history of metal deposition in Singapore lake sediments contributes to understanding the anthropogenic and natural metal deposition in the data-sparse Southeast Asia. To this end, we present a sedimentary record of Pb, Pb isotopes and eleven other metals (Ag, As, Ba, Cd, Co, Cr, Cu, Ni, Tl, U and Zn) from a well-dated sediment co...

In recent decades, rapid industrial developments have increased lead (Pb) inputs to the South China Sea (SCS). To quantify the increasing variability, we investigated 170 years of skeletal Pb and Pb isotopes from an offshore, central Vietnamese coral. The Pb/Ca in the coral was 10-16 nmol/mol before the mid-1950s and increased to more than 30 nmol/...

In recent decades, rapid industrial developments have increased lead (Pb) inputs to the South China Sea. To quantify the increasing variability, we investigated 170 years of skeletal Pb and Pb isotopes from an offshore, central Vietnamese coral. The Pb/Ca in the coral was 10–16 nmol/mol before the mid-1950s and increased to more than 30 nmol/mol by...

The role of iron as a limiting micronutrient motivates an effort to understand the supply and removal of lithogenic trace metals in the ocean. The long-lived thorium isotopes (232Th and 230Th) in seawater can be used to quantify the input of lithogenic metals attributable to the partial dissolution of aerosol dust. Thus, Th can help in disentanglin...

Pb and Pb isotope ratios in the modern ocean have been altered significantly by anthropogenic Pb inputs over the past century. Most studies of anthropogenic Pb in the ocean have focused on the North Atlantic and North Pacific Oceans, and the impact of anthropogenic Pb inputs to the Indian Ocean and processes controlling the distribution of Pb in th...

Time-series studies of trace metals in the ocean are rare, but they are critical for evaluating both the residence times of the metals themselves and also the timescales over which the marine ecosystems that depend on micronutrient metals can change. In this paper we present two new time-series of the essential micronutrient iron (Fe) taken from th...

The GEOTRACES Intermediate Data Product 2014 (IDP2014) is the first publicly available data product of the international GEOTRACES programme, and contains data measured and quality controlled before the end of 2013. It consists of two parts: (1) a compilation of digital data for more than 200 trace elements and isotopes (TEIs) as well as classical...

Significance The vertical supply of dissolved Fe (iron) is insufficient compared with the physiological needs of marine phytoplankton in vast swathes of the open ocean. However, the relative importance of the main sources of “new” Fe to the ocean—continental mineral dust, hydrothermal exhalations, and sediment dissolution—and their temporal evoluti...

The size partitioning of dissolved Fe (dFe<0.2 µm) into soluble (sFe<0.02 µm) and colloidal (0.02 µm<cFe<0.2 µm) species was investigated at 28 stations along the GEOTRACES GA03 North Atlantic Transect. Upper ocean dFe size partitioning was highly variable with depth: 79±6% of aerosol-derived surface dFe was maintained in the colloidal size fractio...

We present the distributions of hydrographic properties (potential temperature, salinity, dissolved oxygen, and micromolar level inorganic macronutrients) along two sections occupied in the subtropical North Atlantic as part of the first U.S. GEOTRACES (GA03) survey during 2010 and 2011. The purpose of this work is to place subsequent papers in thi...

This study presents dissolved Pb concentration and isotopic composition distributions from GEOTRACES GA03, the U.S. North Atlantic Transect. Pb in the ocean is primarily derived from anthropogenic sources and Pb fluxes into the North Atlantic Ocean have been steadily decreasing following the phase-out of alkyl leaded gasoline usage in North America...

Biological nitrogen fixation (BNF) supplies nutrient-depleted oceanic surface waters with new biologically available fixed nitrogen. Diazotrophs are the only organisms that can fix dinitrogen, but the factors controlling their distribution patterns in the ocean are not well understood. In this study, the relative abundances of eight diazotrophic ph...

Significance Low concentrations of the micronutrient iron in seawater are known to limit primary production and nitrogen fixation in large regions of the global ocean. Thus, it is important to constrain the sources and sinks controlling the marine dissolved iron distribution and consequent micronutrient supply to surface plankton. Although the majo...

Significance Humans have altered the earth surface environment by massive injection of certain chemicals into our air and water. In some cases these injections are detrimental to environmental health and must be monitored to limit the damage (e.g., freons and the ozone layer); in other cases (e.g., freon dissolving into the ocean) there are no harm...

The two most frequently used methods for determining the size fractionation of dissolved iron (dFe) in seawater, 0.02 µm pore size Anopore membrane filtration and cross flow filtration using a 10 kDa regenerated cellulose filter, were evaluated and compared. Anopore filtration was found to produce consistent soluble Fe (sFe) concentrations in the f...

Significance The end-Permian extinction is the most severe biotic crisis in the fossil record. Its occurrence has been attributed to increased CO 2 levels deriving from massive Siberian volcanism. However, such arguments have been difficult to justify quantitatively. We propose that the disruption of the carbon cycle resulted from the emergence of...

The two most frequently used methods for determining the size fractionation of dissolved iron (dFe) in seawater, 0.02 μm pore size Anopore membrane filtration and cross flow filtration using a 10 kDa regenerated cellulose filter, were evaluated and compared. Anopore filtration was found to produce consistent soluble Fe (sFe) concentrations in the f...

We review the current distribution of lead and lead isotopes in the ocean with regard to the evolving pattern of human emissions during the past decades and centuries.

Surficial sediment samples were obtained from 25 locations within Kuwait Bay and outside the Bay, in the Northwestern Arabian Gulf, to access recent pollution in Kuwait. The historical deposition of PBDEs to this portion of the Arabian Gulf was reconstructed by collecting a sediment core at the entrance of Kuwait Bay. The mean (and range) in concen...

The size partitioning of dissolved iron (dFe, <0.4 μm) into soluble (sFe, <0.02 μm) and colloidal (0.02 μm < cFe < 0.4 μm) phases was investigated at seven stations in the tropical North Atlantic Ocean, and the results are compared to the dFe size fractionation study of Bergquist et al. (2007) in the same region. Downwind of the North African dust...

Objective and Methods The objective of this study was to reconstruct detailed input chronologies of Pb and other trace metals in the Kuwaiti marine environment, influenced by the Shatt-al-Arab River’s load (SaAR), using seawater, and sediment and coral cores. Pb concentrations were determined by plasma mass spectrometry using resin preconcentration...

Seawater from 27 stations was sampled in a zig-zag transect across the tropical North Atlantic from Barbados to the Cape Verde Islands, 7–20°N and 21–58°W. Under the Northwest African dust plume, surface dissolved Fe (dFe) was elevated, averaging 0.55 ± 0.29 nmol/kg (1SD), but showed a wide range from 0.12 to 1.31 nmol/kg with no clear longitudinal...

Organic ligands dominate the speciation of iron in the ocean. Little is known, however, about the chemical composition and distribution of these compounds. Here we describe a method to detect low concentrations of organic Fe ligands using reverse phase high-performance liquid chromatography (HPLC) tandem multi-collector inductively coupled plasma m...

Organic complexing ligands dominate the chemical speciation of Zn and Cd in seawater, affecting their bioavailability. The use of modern, comprehensive mathematical tools allows for the determination of very precise ligand parameters, so that ligand maturation along water mass trajectories can be inferred from discrete samples. Recently, we have sh...

We report data on the isotopic composition of cadmium, copper, iron, lead, zinc, and molybdenum at the GEOTRACES IC1 BATS Atlantic intercalibration station. In general, the between lab and within-lab precisions are adequate to resolve global gradients and vertical gradients at this station for Cd, Fe, Pb, and Zn. Cd and Zn isotopes show clear varia...

Objective and Methods The objective of this study was to reconstruct detailed input chronologies of trace metals in the Kuwaiti marine environment, influenced by the Shatt al-Arab River’s load, using water, sediment cores and corals. Pb, Cd and Cu concentrations in seawater and sediments were determined by plasma mass spectrometry using isotope dil...

An intercalibration of dissolved iron (dFe) concentrations was conducted from samples collected on the GEOTRACES Pacific Intercalibration cruise using two different sampling devices: the GEOTRACES GO-FLO rosette system and MITESS/Vane samplers. At each depth, the dFe concentrations were identical within analytical error, except at 500 m where conta...

The objective of this study was to reconstruct detailed input chronologies of trace metals in the Kuwaiti marine environment, influenced by the Shatt al-Arab River’s load, using water, sediment cores and corals. Pb, Cd and Cu concentrations in seawater and sediments were determined using isotope dilution and Indium internal standard by plasma mass...

Growth limitation of phytoplankton and unicellular nitrogen (N(2)) fixers (diazotrophs) were investigated in the oligotrophic Western South Pacific Ocean. Based on change in abundances of nifH or 23S rRNA gene copies during nutrient-enrichment experiments, the factors limiting net growth of the unicellular diazotrophs UCYN-A (Group A), Crocosphaera...

A simple and accurate low-blank method has been developed for the analysis of total dissolved copper, cadmium, lead, and iron in a small volume (1.3-1.5 mL per element) of seawater. Pre-concentration and salt-separation of a stable isotope spiked sample are achieved by single batch extraction onto nitrilotriacetate (NTA)-type Superflow(®) chelating...

Baffin Bay serves as the conduit of relatively fresh Arctic waters to the deep convection region of the Labrador Sea. As part of an effort to develop proxies for presence and possibly flux of freshwater through the region in the past, multiple oceanographic tracers were profiled in the water during the July-August 2003 Healy cruise to Baffin Bay an...

Understanding past Atlantic meridional overturning circulation is critical given its pivotal role in modulating abrupt climate events. However, a lack of accurate estimates of reservoir ages hinders testing the potential synchronicity of abrupt deglacial climate events such as Heinrich massive ice-rafting event 1 (H1) and the Younger Dryas cooling...

Ocean viruses alter ecosystems through host mortality, horizontal gene transfer and by facilitating remineralization of limiting nutrients. However, the study of wild viral populations is limited by inefficient and unreliable concentration techniques. Here, we develop a new technique to recover viruses from natural waters using iron-based flocculat...

The absence of accurate measurements of lead (Pb) isotopic composition in the North Pacific abyssal water has made it difficult to assess the relative importance of what are believed to be the two major Pb sources: the natural Pb introduced during preindustrial time and recent anthropogenic Pb resulting from leaded gasoline combustion and high temp...

We are deeply disturbed by the recent escalation of political assaults on scientists in general and on climate scientists in particular. All citizens should understand some basic scientific facts. There is always some uncertainty associated with scientific conclusions; science never absolutely proves anything. When someone says that society should...

Vita. "Joint Program in Oceanography, Massachusetts Institute of Technology - Woods Hole Oceanographic Institution, and Department of Earth and Planetary Sciences, Massachusetts Institute of Technology, April, 1976." "June, 1976."--Cover. Thesis (Ph. D.)--Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1976. Includes...