Methods for analyzing the concentration and speciation of major and trace elements in marine particles
Introduction
Particulate matter in the ocean, traditionally defined as materials >0.2 μm, is one of the main reservoirs for trace elements and isotopes (TEIs), and regulates the distribution of dissolved TEIs through dissolution and scavenging. There is a broad diversity of types and compositions of particulate matter, including intact plankton cells, crustal aluminosilicates, resuspended sediments, authigenic minerals, organic polymers or gels, biogenic detrital material (e.g., fecal pellets, dead cells, empty frustules), or aggregates of a combination of these. In addition, particles in the upper water column can also be generated through spontaneous aggregation of Dissolved Organic Matter (DOM) into particles termed microgels (Verdugo and Santschi, 2010), ranging from molecules to a typical size of 4 μm, therefore becoming Particulate Organic Matter (POM, Chin et al., 1998). To understand the role of particulate matter in the biogeochemical cycling of both major elements and TEIs in the ocean requires knowledge about both the total composition of suspended matter and the composition of individual particles.
Particles affect TEI cycles both through their elemental composition and through their influence on the scavenging and dissolution of the dissolved elements (Goldberg, 1954, Jeandel et al., 2015; Turekian, 1977). Particle mass and major element composition (such as the proportions of POM, CaCO3, opal, and lithogenic material) may affect the efficiency of the scavenging of several particle-reactive TEIs (Akagi et al., 2011, Chase et al., 2002, Roy-Barman et al., 2005). A number of biopolymers, potentially produced by both phytoplankton and bacteria, could also be carrier molecules for naturally occurring radioisotopes, in addition to the purely inorganic surfaces generally thought to bind radioisotopes (Quigley et al., 2002, Roberts et al., 2009). A greater understanding of the roles of particles often requires the isolation of specific functional groups of particles and sometimes also the determination of the chemical and physical speciation of different elements. For example, the accumulation of TEIs by plankton is a significant control on dissolved metal distributions in the ocean, but determining the TEI content of plankton in natural communities is challenging due to the heterogeneous nature of the particle assemblage (Twining et al., 2008). As another example, the solubility and reactivity of some particle constituents can often be related to the nature of the lithogenic phase(s) that is (are) present (e.g. Si is more reactive in clays than in a grain of quartz; Fe in basalts is mostly reduced and potentially more reactive than oxidized Fe in granites). Thus, determining the mineralogy and speciation of TEIs in the solid phase may be necessary to understand their reactivity. This additional chemical information can also provide clues to the provenance of particles (Lam and Bishop, 2008, von der Heyden et al., 2012).
The complex compositions of marine particles are reflected in their multifaceted role in the cycling of TEIs. To understand these roles, a diverse suite of methods is required to characterize the particles. The methods have to account for relatively dilute concentrations of particles in the ocean and for the trace levels of TEIs in particulate matter. For example, suspended particulate matter (SPM) is typically present at concentrations of only 2–200 μg/kg (Biscaye and Eittreim, 1977, Jeandel et al., 2015). Important bioactive TEIs such as cobalt may be present at ppm levels in biogenic materials, and particulate organic carbon (POC) itself is often present at <10 μM in the open ocean. Thus many particulate TEIs may be present at pM (10−12 M) or lower levels in the ocean. While the development of in-situ optical techniques has enabled the characterization of particle abundance and size spectrum and some estimates of basic particle composition such as POC and particulate inorganic carbon (PIC) concentrations (Boss et al., 2015), the full chemical characterization of particles is essential to understand their role in the biogeochemical cycle of TEIs. Physical sampling of particles and analysis by laboratory-based techniques yield information on particle mass, most major and minor element concentrations, isotopic compositions, and chemical speciation. Sample collection for both major particle composition and TEI analysis is discussed in McDonnell et al. (2015), Planquette and Sherrell (2012), and Bishop et al. (2012).
Here we review some of the varied laboratory-based approaches used to study particle composition. We discuss methods to measure basic particulate parameters that are necessary to understand the role of particles in the cycling of TEIs. Because an understanding of the role of particles in biogeochemical cycling often requires knowledge of the physical and chemical speciation of particles, we also present some of the methods that have been used to study particle speciation. A review of analytical methods for characterizing marine particles was last published over twenty years ago (Hurd and Spencer, 1991), and many new techniques are now available, particularly spectroscopic techniques.
A comprehensive review of all techniques that can be applied to particles is beyond the scope of this paper. Instead, we aim to provide an overview of methods and touch on some of the major findings that have resulted from these techniques to provide a starting point for further studies. The paper begins with a description of methods to measure major particle composition and suspended particle mass. These are standard techniques that are commonly applied to the analysis of sediment trap material but may not be familiar to the GEOTRACES community. The discussion then shifts to the main focus of this paper, i.e., to the techniques used to measure TEI compositions of particulate matter. These are organized into three categories: (1) analytical or “wet” chemical methods, including chemical leaches of particles, followed by analysis of the solution phase, (2) nuclear techniques, and (3) spectroscopic techniques, in which the interaction of radiation with matter is used to determine elemental composition, mineralogy, or chemical speciation in the solid phase.
Section snippets
Major particle composition and suspended particle mass
The mass of total suspended matter in the ocean is the sum of its major, minor, and trace components, however it depends mostly upon its major components, which include particulate organic matter, biogenic silica, calcium carbonate, and often also lithogenic matter, strontium and barium sulfate, and iron and manganese oxyhydroxides. The major particle phases are implicated in the control of particle flux to depth (François et al., 2002, Klaas and Archer, 2002) and of scavenging of
Total chemical digests
Although an extensive literature describes the chemical digestion (complete and sequential) of sediments, the digestion of marine suspended particles collected on filters presents additional challenges. Particulate TEIs were traditionally collected on polycarbonate membrane filters because of their low blanks (e.g., Cullen and Sherrell, 1999, Landing and Bruland, 1987, Sherrell and Boyle, 1992). However, because polycarbonate-membrane filters have relatively low sample throughput, and the
Conclusions
In this paper, we have reviewed techniques that are used to study the composition and speciation of marine particles. The analytical «wet» chemistry techniques described here are being used in a high-throughput fashion to measure the first full ocean depth, basin-wide sections of marine particulate distribution and composition as part of the international GEOTRACES program (Lam et al., 2014, Ohnemus and Lam, 2014, Twining et al., 2014). We also described the physical principles behind
Acknowledgements
This paper arose from a workshop that was co-sponsored by ESF COST Action ES0801, “The ocean chemistry of bioactive trace elements and paleoproxies”. Additional support for the workshop came from SCOR, through support to SCOR from the U.S. National Science Foundation (Grant OCE-0938349 and OCE-1243377) and through a U.S. NSF award to the US GEOTRACES project office (OCE-0850963). Additional support was from U.S. NSF Grant OCE-0963026 to PJL and OCE-0928289 to BST. We are grateful to three
References (143)
- et al.
Composition of rare earth elements in settling particles collected in the highly productive North Pacific Ocean and Bering Sea: implications for siliceous-matter dissolution kinetics and formation of two REE-enriched phases
Geochimica et Cosmochimica Acta
(2011) - et al.
Suspended particulate matter: collection by pressure filtration and elemental analysis by thin-film X-ray fluorescence
Deep Sea Research and Oceanographic Abstracts
(1976) - et al.
The trace element composition of suspended particulate matter in the upper 1000 m of the eastern North Atlantic Ocean: A16N
Marine Chemistry
(2012) - et al.
Suspended particulate loads and transports in the nepheloid layer of the abyssal Atlantic Ocean
Marine Geology
(1977) - et al.
Chemical characterization of individual particles from the nepheloid layer in the Atlantic Ocean
Earth and Planetary Science Letters
(1982) - et al.
Chemistry, biology, and vertical flux of particulate matter from upper 400 m of equatorial Atlantic Ocean
Deep-Sea Research
(1977) - et al.
Soft X-ray microscopy and spectroscopy at the molecular environmental science beamline at the Advanced Light Source
Journal of Electron Spectroscopy and Related Phenomena
(2006) - et al.
Modern sampling and analytical methods for the determination of trace elements in marine particulate material using magnetic sector inductively coupled plasma–mass spectrometry
Analytica Chimica Acta
(2010) - et al.
Examining marine particulate organic matter at sub-micron scales using scanning transmission X-ray microscopy and carbon X-ray absorption near edge structure spectroscopy
Marine Chemistry
(2004) - et al.
Sulfur, sulfides, oxides and organic matter aggregated in submarine hydrothermal plumes at 9°50′N East Pacific Rise
Geochimica et Cosmochimica Acta
(2012)
Particle size and aerosol iron solubility: a high-resolution analysis of Atlantic aerosols
Marine Chemistry
The solubility and deposition of aerosol Fe and other trace elements in the North Atlantic Ocean: observations from the A16N CLIVAR/CO2 repeat hydrography section
Marine Chemistry
Pacific Ocean aerosols: deposition and solubility of iron, aluminum, and other trace elements
Marine Chemistry
The influence of particle composition and particle flux on scavenging of Th, Pa and Be in the ocean
Earth and Planetary Science Letters
A chemical technique for the separation of ferro-manganese minerals, carbonate minerals and adsorbed trace elements from pelagic sediments
Chemical Geology
Role of biopolymers as major carrier phases of Th, Pa, Pb, Po, and Be radionuclides in settling particles from the Atlantic Ocean
Marine Chemistry
The trace-element geochemistry of marine biogenic particulate matter
Progress in Oceanography
Scavenging rates of dissolved manganese in a hydrothermal vent plume
Deep Sea Research Part A: Oceanographic Research Papers
Techniques for determination of trace metals in small samples of size-fractionated particulate matter: phytoplankton metals off central California
Marine Chemistry
Discrete suspended particles of barite and the barium cycle in the open ocean
Earth and Planetary Science Letters
The supply and accumulation of silica in the marine environment
Geochimica et Cosmochimica Acta
Seasonality in the supply of sediment to the deep Sargasso Sea and implications for the rapid transfer of matter to the deep ocean
Deep-Sea Research Part A: Oceanographic Research Papers
Sorption of ferric iron from ferrioxamine B to synthetic and biogenic layer type manganese oxides
Geochimica et Cosmochimica Acta
A comparison of the scavenging of phosphorus and arsenic from seawater by hydrothermal iron oxyhydroxides in the Atlantic and Pacific Oceans
Deep Sea Research Part A: Oceanographic Research Papers
Export production of particles to the interior of the equatorial Pacific-Ocean during the 1992 Eqpac experiment
Deep-Sea Research Part II: Topical Studies in Oceanography
Particle dynamics in the Eastern Mediterranean Sea: a synthesis based on light transmission, PMC, and POC archives (1991–2001)
Deep Sea Research Part I: Oceanographic Research Papers
Spatial variability of particle associated trace elements in near-surface waters of the North Atlantic (30 degrees N/60 degrees W to 60 degrees N/2 degrees W), derived by large-volume sampling
Marine Chemistry
High biomass low export regimes in the Southern Ocean
Deep Sea Research Part II: Topical Studies in Oceanography
The speciation of marine particulate iron adjacent to active and passive continental margins
Geochimica et Cosmochimica Acta
Sinking fluxes of minor and trace elements in the North Pacific Ocean measured during the VERTIGO program
Deep-Sea Research Part II: Topical Studies in Oceanography
The contrasting biogeochemistry of iron and manganese in the Pacific-Ocean
Geochimica et Cosmochimica Acta
Computerized oceanic particle characterization using heavy metal staining, SEM, EDXS and image analysis
Deep Sea Research Part A: Oceanographic Research Papers
Mn, Fe, Zn and As speciation in a fast-growing ferromanganese marine nodule
Geochimica et Cosmochimica Acta
Elemental composition of plankton
Geochimica et Cosmochimica Acta
A simple method for the rapid-determination of biogenic opal in pelagic marine-sediments
Deep-Sea Research Part A: Oceanographic Research Papers
Pitfalls of sequential extractions
Water Research
Fifteen years of nuclear techniques application to suspended particulate matter studies
Journal of Radioanalytical and Nuclear Chemistry
GEOTRACES intercalibration of 230Th, 232Th, 231Pa and prospects for 10Be
Limnology and Oceanography: Methods
The Arctic Ocean marine carbon cycle: evaluation of air-sea CO2 exchanges, ocean acidification impacts and potential feedbacks
Biogeosciences
XPS and XAS study of the sorption of Hg(II) onto pyrite
Langmuir
Application of a chemical leach technique for estimating labile particulate aluminum, iron, and manganese in the Columbia River plume and coastal waters off Oregon and Washington
Journal of Geophysical Research
Principles and Practice of X-ray Spectrometric Analysis
The barite-opal-organic carbon association in oceanic particulate matter
Nature
Getting good weight
Geophysical Monograph Series
A multiple-unit large-volume in-situ filtration system for sampling oceanic particulate matter in mesoscale environments
Advances in Chemistry Series
Getting good particles: accurate sampling of particles by large volume in-situ filtration
Limnology and Oceanography Methods
Sediment trap experiments in the deep north Atlantic: isotopic and elemental fluxes
Journal of Marine Research
Mineral-aqueous solution interfaces and their impact on the environment
Geochemical Perspectives
Aerosol iron and aluminum solubility in the northwest Pacific Ocean: results from the 2002 IOC cruise
Geochemistry Geophysics Geosystems
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