Stable Sulfur Isotope Ratios Research Articles

Incremental analysis of vertebral centra can reconstruct the stable isotope chronology of teleost fishes

Abstract Isotope analysis has high potential for understanding fish ecology and food‐web structure in aquatic ecosystems. The utility of isotope analysis will be greatly improved if we can reconstruct the chronology of several isotopes at multiple growth stages of individual fish. However, no practical methods exist for reconstructing the chronology of light‐element isotopes (e.g. δ13C, δ15N, δ34S, and Δ14C) in teleost fishes. Here, we present and test a new analytical approach for reconstructing the isotopic ratios of light isotopes at multiple life‐stages in teleost fishes. We sampled an anadromous salmon species, masu salmon Oncorhynchus masou (n = 3), along with water from its natal stream and from the ocean. We subdivided the vertebral centra of the salmon equally into 10 sections and extracted bone collagen from each sample. We then measured the stable sulphur isotope ratios of each vertebral section and compared them with δ34S values of the river water and sea water. We also measured the 87Sr/86Sr ratios of otoliths as a reference indicator of salmon migration between fresh water and the ocean. In all samples, the bone section closest to the centre of the centrum had the lowest δ34S values, which were similar to those of fresh water. The δ34S values gradually increased from the centre to marginal sections, finally reaching constant values similar to those of seawater. The 87Sr/86Sr ratios of sagittal otolith sections had significant inter‐individual differences and were consistent with the patterns of variation of the δ34S values of the vertebral sections. Our results show that the vertebral centra of teleost fishes record isotopic information from juvenile to adult life stages. We suggest that our method can provide reproducible isotopic chronology, even in teleost fishes smaller than 50 cm. This method can be used in isoscape studies and in studies of the ecology of marine teleost fishes.

Stable sulfur isotopes identify habitat-specific foraging and mercury exposure in a highly mobile fish community

Tracking the uptake and transfer of toxic chemicals, such as mercury (Hg), in aquatic systems is challenging when many top predators are highly mobile and may therefore be exposed to chemicals in areas other than their location of capture, confounding interpretation of bioaccumulation trends. Here we show how the application of a less commonly used ecological tracer, stable sulfur isotope ratios (34S/32S, or δ34S), in a large river-delta-lake complex in northern Canada allows differentiation of resident from migrant fishes, beyond what was possible with more conventional 13C/12C and 15N/14N measurements. Though all large fishes (n=105) were captured in the river, the majority (76%) had δ34S values that were indicative of the fish having been reared in the lake. These migrant fishes were connected to a food chain with greater Hg trophic magnification relative to the resident fish of the river and delta. Yet, despite a shallower overall trophic magnification slope, large river-resident fish had higher Hg concentrations owing to a greater biomagnification of Hg between small and large fishes. These findings reveal how S isotopes can trace fish feeding habitats in large freshwater systems and better account for fish movement in complex landscapes with differential exposure pathways and conditions.

Rapid quadruple sulfur isotope analysis at the sub-micromole level by a flash heating with CoF3

Stable sulfur isotope ratio has been useful for tracing a wide range of biogeochemical processes. The conventional SF6 method allows us to make high-precision analyses of all four of the stable isotopes (32S/33S/34S/36S), though the fluorination step is time consuming and requires the hazardous elemental fluorine (F2). Here we show a novel flash-fluorination technique for instantaneous preparation of SF6 from sulfide samples by reaction with cobalt fluoride (CoF3) instead of F2. Flash heating by using a Curie-point pyrolyzer dramatically simplifies the fluorination procedure. A series of experiments demonstrated that silver sulfide (Ag2S) can be converted into SF6 at 590°C within 3s with sufficient reproducibilities for δ34S (±0.4‰), Δ33S (±0.01‰) and Δ36S (±0.1‰). Instrumental fractionation is negligible for δ34S and Δ33S, but should be corrected for Δ36S, when fluorinating small samples less than 150nmol. Further, application of the method to various other sulfur compounds shows that pyrite and several organic sulfur species can be directly converted into SF6, though more work is necessary for improving the accuracy of isotopic analysis comparable to that of Ag2S. Nevertheless, the new CoF3-flash-fluorination technique provides fast, convenient and safe procedure for high-precision analysis of quadruple sulfur isotopes.

Isotopic Discrimination in the Double-Crested Cormorant (Phalacrocorax auritus).

The diet-tissue discrimination factor is the amount by which a consumer’s tissue varies isotopically from its diet, and is therefore a key element in models that use stable isotopes to estimate diet composition. In this study we measured discrimination factors in blood (whole blood, red blood cells and plasma), liver, muscle and feathers of Double-crested Cormorants (Phalacrocorax auritus) for stable isotope ratios of carbon, nitrogen and sulfur. Cormorants exhibited discrimination factors that differed significantly among tissue types (for carbon and nitrogen), and differed substantially (in the context of the isotopic variation among relevant prey species) from those observed in congeneric species. The Double-crested Cormorant has undergone rapid population expansion throughout much of its historic range over the past three decades, leading to both real and perceived conflicts with fisheries throughout North America, and this study provides an essential link for the use of stable isotope analysis in researching foraging ecology, diet, and resource use of this widespread and controversial species.

Stable sulfur isotope ratios and water-soluble inorganic compositions of PM10 in Yichang City, central China.

Chemical and sulfate-sulfur isotopic compositions of water-soluble inorganic ions were analyzed for aerosol sample particulate matter with aerodynamic diameter ≤10μm (PM10) collected during 17-28 December 2012 at Yichang City, Hubei Province, central China. Most water-soluble inorganic ions, except for NO3 (-) and NH4 (+), showed slightly higher concentration in daytime than in nighttime, and the major detected ions followed the order of SO4 (2-) > NO3 (-) > Ca(2+) > Na(+) > NH4 (+) > Cl(-) in daytime and nighttime, of which SO4 (2-) is the most abundant ionic component that accounted for about 49.1 and 49.3% of the total mass of analyzed ions in daytime and nighttime, respectively. According to the correlation coefficients among the mass concentrations of water-soluble inorganic ions, there may mainly exist in forms of (NH4)2SO4 and NH4NO3 in daytime and NH4NO3 in nighttime. The δ(34)S values of sulfate ranged from +2.82 to +4.63 ‰ (average +3.97 ‰) in daytime and from +2.90 to +5.39 ‰ (average +4.08 ‰) in nighttime, indicating that the source of sulfate in PM10 was mainly derived from coal burning (δ(34)S, +3.68 ‰) in Yichang City. The [NO3 (-)]/[SO4 (2-)] mass ratio varied between 0.2 and 0.6 with an average of 0.4 in daytime and 0.1 to 0.8 with an average of 0.4 in nighttime, which implying that the stationary source emissions would be more important than the vehicle emissions in the studied area. As a whole, the mixture of coal burning, vehicle exhaust, and resuspended road dust would be responsible for the sources of PM10 in Yichang City during wintertime.

Food for Thought: Re-Assessing Mesolithic Diets in the Iron Gates

Stable isotope ratios of carbon, nitrogen, and sulfur in human bone collagen are used routinely to aid in the reconstruction of ancient diets. Isotopic analysis of human remains from sites in the Iron Gates section of the Lower Danube Valley has led to conflicting interpretations of Mesolithic diets in this key region of southeast Europe. One view (Bonsall et al. 1997, 2004) is that diets were based mainly on riverine resources throughout the Mesolithic. A competing hypothesis (Nehlich et al. 2010) argues that Mesolithic diets were more varied with at least one Early Mesolithic site showing an emphasis on terrestrial resources, and riverine resources only becoming dominant in the Later Mesolithic. The present article revisits this issue, discussing the stable isotope data in relation to archaeozoological and radiocarbon evidence.

New Frontiers for Sulfur Isotopic Analyses

Measurements of sulfur stable isotope ratios (34S/32S) have suffered in the past from technical difficulties in analyzing low-S materials reducing their use despite their undeniable scientific interest. The measurement of 34S/32S ratios is a powerful tool for deciphering problems such as determining the sources of environmental pollutants, to detect adulteration, tracking the evolution of the redox state of the oceans, and quantifying the role of the bacterial activity in sulfide minerals genesis. We have used an innovative high–precision, easy and rapid method of simultaneous analysis of carbon (13C/12C), nitrogen (15N/14N) and sulfur (34S/32S) isotope ratios as well as elemental concentrations using a new combination of elemental analyzer and isotopic ratio mass spectrometer. This new technique provides multiple isotopic signatures on smaller sample aliquots with high precisions especially for sulfur determinations. The technique described here is Isotopic Ratio Mass Spectrometry (IRMS) on line in continuous flow mode with an Elemental Analyzer (EA) based on “purge and trap” technology rather than conventional packed-GC gas separation. Emphasis is put on the efficiency of the system to reliably combust sulfur–bearing compounds of both organic and inorganic origin with high conversion yields. This new technique demonstrates the high quality of 34S/32S measurements for samples with S concentrations lower than 1 wt%. International calibrated references of diverse sulfur-bearing materials were used to calibrate two low (<1%) S -bearing phosphorites used as compositional reference material for future use as isotopic references: BCR32 and NBS120c. High quality of 34S/32S determinations is illustrated using various international reference materials. Working calibrated material has been selected and characterized for all three isotopic signatures as well in order to fully use the capacities of the system in future work. The possibilities of such a system to reliably measure S isotopes as well as N and C within the same aliquot of sample opens up new fields of investigation in many domains where multi-isotopic approaches are required.

A preliminary study on sulfate reduction bacteria behaviors in groundwater by sulfur and carbon isotopes: a case study in Jiaozuo City, China.

Inorganic pollutants in groundwater, such as sulfate and nitrate, have been a serious problem in China for decades. These pollutants are difficult to be removed because of their high solubility and ease of transport in subsurface environment. It had been found that microorganism could be one of the most feasible methods for inorganic pollutant elimination. During the process of degradation, some microorganisms can utilize sulfur and nitrogen in sulfate and nitrate forms, respectively, as energy sources. Meanwhile, significant variations of sulfur stable isotope ratios happened. Therefore sulfur isotope can be used as a good indicator for pollutant degradation and microbial activities. Shallow groundwater (SGW), deep groundwater (DGW), and surface water (SFW) were investigated in alluvial plain in Jiaozuo City, China. The results of hydrochemical analysis indicated that K(+), Na(+), and HCO3(-) were dominant ions in DGW, Mg(2+) and HCO3(-) were dominant ions in SGW, and Ca(2+) and HCO3 (-) were dominant in SFW except for LR sample. A wide variation of δ (34)SSO4 values ranging from + 7.3 to +23.6‰ had been observed for all water samples, with a mean value of +20.7, +12.6 and +10.0‰ for DGW, SGW, and SFW respectively. At the same time, δ(13)C values of dissolved inorganic carbon (DIC) ranged from -12.4 to -5.7‰, with a mean value of -7.5, -9.0, and -9.6‰ for DGW, SGW, and SFW, respectively. The microbial degradation processes resulted in significant sulfur isotope fractionations in DGW. Organic carbon was utilized by bacteria and transferred into inorganic carbon, leading to negative fractionation of carbon isotopes. Thus the variations in stable isotope ratios of sulfur and carbon in groundwater can be used as good indicators for understanding of the relationship between bacteria behaviors and sulfate degradation.

A stable isotopic constraint on the origin of sulphur ore excavated from the exotic four‐lobe jars that prevailed during late medieval to early modern times in Sakai (Osaka), south‐western Japan

Stable sulphur isotope ratios were determined for native sulphur ore that was excavated from exotic four‐lobe jars in Sakai, south‐western Japan. The jars were buried after a fire event that occurred on 28 April 1615. The sulphur isotopic results (average δ34S = +0.5‰) were evaluated in terms of comparing ancient documents with a database from new sulphur collections. The origin of the sulphur ore is estimated to be transportation from native sulphur deposits formed around the solfataric fumaroles from Mts Garan and Kuju–Iwozan, in central‐eastern Kyushu. These analytical results support the validity of history based on the analysis of ancient documents.

In search of the dead zone: Use of otoliths for tracking fish exposure to hypoxia

Otolith chemistry is often useful for tracking provenance of fishes, as well as examining migration histories. Whereas elements such as strontium and barium correlate well with salinity and temperature, experiments that examine manganese uptake as a function of these parameters have found no such correlation. Instead, dissolved manganese is available as a redox product, and as such, is indicative of low-oxygen conditions. Here we present evidence for that mechanism in a range of habitats from marine to freshwater, across species, and also present ancillary proxies that support the mechanism as well. For example, iodine is redox-sensitive and varies inversely with Mn; and sulfur stable isotope ratios provide evidence of anoxic sulfate reduction in some circumstances. Further, S may be incorporated trophically whereas other elements appear to be taken up directly from water. This research suggests a potential means to identify individual fish exposure to hypoxia, over entire lifetimes. With further testing and understanding, in the future fish may be able to be used as “mobile monitors” of hypoxic conditions.

Simultaneous analysis of δ13C, δ15N and δ34S ratios uncovers food web relationships and the trophic importance of epiphytes in an eelgrass Zostera marina community

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 497:93-103 (2014) - DOI: https://doi.org/10.3354/meps10569 Simultaneous analysis of δ13C, δ15N and δ34S ratios uncovers food web relationships and the trophic importance of epiphytes in an eelgrass Zostera marina community Agnes Mittermayr*, Thomas Hansen, Ulrich Sommer GEOMAR Helmholtz Centre for Ocean Research Kiel, Düsternbooker Weg 20, 24105 Kiel, Germany *Corresponding author: amittermayr@geomar.de ABSTRACT: Simultaneous analysis of carbon, nitrogen and sulphur stable isotope ratios was applied in this pilot study to examine the food web of a Zostera marina L. system in the western Baltic Sea. Samples of 3 potential food sources: eelgrass, epiphytic algae and seston, as well as 69 consumer species were collected during the growing season of Z. marina from March to September 2011. The measured δ13C values of epiphytes were close to δ13C values of eelgrass, impeding a clear distinction of those 2 carbon sources, whereas seston δ13C values were clearly different. This frequently encountered problem was solved by the additional use of δ34S, which resulted in easily distinguishable values for sediment and seawater derived sulphur. The combination of δ34S and δ13C values made a separation of carbon sources possible and enabled the allocation of potential food sources to consumers and a description of their trophic relationships. The results of stable isotope ratio analysis of this eelgrass community strongly indicate a food web based on epiphyte and seston production. δ15N values show a food web consisting of large numbers of generalists and a high degree of omnivory amongst the consumer species analysed. This implies an occupation of every trophic position possible, which is supported by an even distribution of δ15N values. Previously described eelgrass food webs may have to be re-evaluated by considering sulphur stable isotope ratios in order to provide a clear picture on primary carbon sources. KEY WORDS: Stable isotopes · Food web · Seagrass · Epiphytes · Trophic level Full text in pdf format Supplementary material PreviousNextCite this article as: Mittermayr A, Hansen T, Sommer U (2014) Simultaneous analysis of δ13C, δ15N and δ34S ratios uncovers food web relationships and the trophic importance of epiphytes in an eelgrass Zostera marina community. Mar Ecol Prog Ser 497:93-103. https://doi.org/10.3354/meps10569 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 497. Online publication date: February 05, 2014 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2014 Inter-Research.

Equations for lipid normalization of carbon stable isotope ratios in aquatic bird eggs.

Stable isotope ratios are biogeochemical tracers that can be used to determine the source of nutrients and contaminants in avian eggs. However, the interpretation of stable carbon ratios in lipid-rich eggs is complicated because 13C is depleted in lipids. Variation in 13C abundance can therefore be obscured by variation in percent lipids. Past attempts to establish an algebraic equation to correct carbon isotope ratios for lipid content in eggs have been unsuccessful, possibly because they relied partly on data from coastal or migratory species that may obtain egg lipids from different habitats than egg protein. We measured carbon, nitrogen and sulphur stable isotope ratios in 175 eggs from eight species of aquatic birds. Carbon, nitrogen and sulphur isotopes were enriched in lipid-extracted egg samples compared with non extracted egg samples. A logarithmic equation using the C∶N ratio and carbon isotope ratio from the non extracted egg tissue calculated 90% of the lipid-extracted carbon isotope ratios within ±0.5‰. Calculating separate equations for eggs laid by species in different habitats (pelagic, offshore and terrestrial-influenced) improved the fit. A logarithmic equation, rather than a linear equation as often used for muscle, was necessary to accurately correct for lipid content because the relatively high lipid content of eggs compared with muscle meant that a linear relationship did not accurately approximate the relationship between percent lipids and the C∶N ratio. Because lipid extraction alters sulphur and nitrogen isotope ratios (and cannot be corrected algebraically), we suggest that isotopic measurement on bulk tissue followed by algebraic lipid normalization of carbon stable isotope ratio is often a good solution for homogenated eggs, at least when it is not possible to complete separate chemical analyses for each isotope.

東北地方太平洋沖地震による岩手，宮城，福島県沿岸域における津波堆積物の供給源

Geochemical analyses (total nitrogen: TN, total organic carbon: TOC, total sulfur: TS, and stable sulfur isotope ratio: δ34S) were performed on tsunami deposits by the 2011 off the Pacific coast of Tohoku Earthquake obtained from Iwate, Minamisanriku, Kesen-numa, and Sendai Bay areas for a total of 133 samples. Although TOC/TN ratios ranged widely (0.7–90), most of the samples (more than 80% of samples) ranged from 10–30, which were similar results to those for marine surface sediment in the Pacific coast area. Low δ34S values (from -29.6‰ to -11.3‰) from Iwate, Minami Sanriku, and Sendai Bay tsunami deposits were observed. Generally, such low δ34S values result from large isotope fractionation caused by the activity of sulfate-reducing bacteria in marine sediment under a sulfate (SO42-) rich environment. These results suggest that the tsunami deposits were mainly derived from marine sediment. High correlations between TS and As contents (r=0.958) were observed in tsunami deposits from the Kesen-numa area. Furthermore, the high δ34S values (from -3.1‰ to -0.7‰) in the tsunami deposits from the Kesen-numa area correspond well with those of hydrothermal ore samples from the Kesen-numa area. These results indicate that sulfur and arsenic in tsunami deposits from the Kesen-numa area originated in slag from the mines.

Sample acidification significantly alters stable isotope ratios of sulfur in aquatic plants and animals

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 493:1-8 (2013) - DOI: https://doi.org/10.3354/meps10560 FEATURE ARTICLE Sample acidification significantly alters stable isotope ratios of sulfur in aquatic plants and animals Rod M. Connolly1,*, Thomas A. Schlacher2 1Australian Rivers Institute - Coast and Estuaries, and School of Environment, Gold Coast Campus, Griffith University, Queensland 4222, Australia 2Faculty of Science, University of the Sunshine Coast, Maroochydore DC, Queensland 4558, Australia *Email: r.connolly@griffith.edu.au ABSTRACT: Sulfur stable isotopes are increasingly being used as tracers of material processing in studies of both modern and historical food webs. Preparation of plant and animal material for isotope analysis routinely includes steps that remove inorganic material not normally assimilated by consumers. Whereas acidification of samples is known to assist with this for some elements (carbon), it can produce unwanted effects for others (nitrogen). Here we tested the effects of acidification on sulfur isotopes by comparing isotope ratios of paired acidified and non-acidified samples of seagrass, epiphytic algae growing on seagrass and animal consumers (3 types of crustaceans: amphipods, copepods and isopods). Acid treatment resulted in significant losses of elemental sulfur from the tissues and changes in sulfur isotope ratios of samples. The artificial depletion of the heavy sulfur isotope decreased sulfur isotope ratios by 2.6‰ on average, and by as much as 7.0‰ in individual samples. Acidification of samples prior to sulfur isotope analysis results in invalid ratios and should not be used. KEY WORDS: Acid digestion · Amino acids · Carbonate · DMSP · Seagrass · Stable isotope analysis Full text in pdf format Information about this Feature Article NextCite this article as: Connolly RM, Schlacher TA (2013) Sample acidification significantly alters stable isotope ratios of sulfur in aquatic plants and animals. Mar Ecol Prog Ser 493:1-8. https://doi.org/10.3354/meps10560 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 493. Online publication date: November 20, 2013 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2013 Inter-Research.

Sulphur from heaven and hell

Fingerprints of sulphur isotopes in rocks from the ridge beneath the Atlantic Ocean suggest that a substantial fraction of sulphur at Earth's surface is left over from the formation of the planet's core. See Letter p.208 The differentiation of early Earth's subsurface material into core and mantle layers should be reflected in the residual mantle composition, as most of the iron-loving elements, presumably including sulphur, would have been scavenged by the liquid core. However, previous analyses of Earth's mantle have identified stable sulphur isotope ratios resembling those seen in chondritic meteorites, perhaps the result of a 'late veneer' meteoritic origin for mantle material. But here Jabrane Labidi et al. provide evidence that the mantle displays heterogeneous sulphur isotope ratios directly correlated to strontium and neodymium isotope ratios. The authors conclude that these results can be reconciled by fractionation during core-mantle differentiation.

Application of 34S analysis for elucidating terrestrial, marine and freshwater ecosystems: Evidence of animal movement/husbandry practices in an early Viking community around Lake Mývatn, Iceland

Carbon and nitrogen stable isotope ratios (δ13C and δ15N) have been used widely in archaeology to investigate palaeodiet. Sulphur stable isotope ratios (δ34S) have shown great promise in this regard but the potential of this technique within archaeological science has yet to be fully explored. Here we report δ34S, δ13C and δ15N values for 129 samples of animal bone collagen from Skútustaðir, an early Viking age (landnám) settlement in north-east Iceland. This dataset represents the most comprehensive study to date of its kind on archaeological material and the results show a clear offset in δ34S values between animals deriving their dietary resources from terrestrial (mean=+5.6±2.8‰), freshwater (mean=−2.7±1.4‰) or marine (mean=+15.9±1.5‰) reservoirs (with the three food groups being significantly different at 2σ). This offset allows reconstruction of the dietary history of domesticated herbivores and demonstrates differences in husbandry practices and animal movement/trade, which would be otherwise impossible using only δ13C and δ15N values. For example, several terrestrial herbivores displayed enriched bone collagen δ34S values compared to the geology of the Lake Mývatn region, indicating they may have been affected by sea-spray whilst being pastured closer to the coast, before being traded inland. Additionally, the combination of heavy δ15N values coupled with light δ34S values within pig bone collagen suggests that these omnivores were consuming freshwater fish as a significant portion of their diet. Arctic foxes were also found to be consuming large quantities of freshwater resources and radiocarbon dating of both the pigs and foxes confirmed previous studies showing that a large freshwater radiocarbon (14C) reservoir effect exists within the lake. Overall, these stable isotope and 14C data have important implications for obtaining a fuller reconstruction of the diets of the early Viking settlers in Iceland, and may allow a clearer identification of the marine and/or freshwater 14C reservoir effects that are known to exist in human bone collagen.

The Use of Stable Sulfur, Oxygen and Hydrogen Isotope Ratios as Geochemical Tracers of Sulfates in the Podwiśniówka Acid Drainage Area (South-Central Poland)

The paper presents the results of determinations of stable S and O isotopes of dissolved sulfates and O and H stable isotopes of waters from three ponds, that is, Marczakowe Doly acid pond, Marczakowe Doly fish pond and Podwiśniowka acid pit pond, located in the Holy Cross Mountains (south-central Poland). The δ34SV-CDT and δ18OV-SMOW of SO4 2− in waters of three ponds (n = 14) varied from −16.2 to −9.5 ‰ (mean of −13.6 ‰) and from −8.1 to −3.2 ‰ (mean of −4.8 ‰), respectively. The mean δ34S–SO4 2− values were closer to those of pyrite (mean of −25.4 ‰) and efflorescent sulfate salts (mean of −25.6 ‰), recorded previously in the Podwiśniowka quarry, than to sulfates derived from other anthropogenic or soil and bedrock sources. The SO4 2− ions formed by bacterially induced pyrite oxidation combined with bacterial (dissimilatory) dissolved sulfate reduction, and presumably with subordinate mineralization of carbon-bonded sulfur compounds, especially in both Marczakowe Doly ponds. In addition, the comparison of δ18O–SO4 2− and δ18O–H2O values indicated that 75–100 % of sulfate oxygen was derived from water. Due to the largest size, the Podwiśniowka acid pit pond revealed distinct seasonal variations in both δ18O–H2O (−9.2 to −1.6) and δD–H2O (−29.7 to −71.3) values. The strong correlation coefficient (r 2 = 0.99) was noted between δ18O–H2O and δD–H2O values, which points to atmospheric precipitation as the only source of water. The sediments of both acid ponds display different mineral inventory: the Marczakowe Doly acid pond sediment consists of schwertmannite and goethite, whereas Podwiśniowka acid pit pond sediment is composed of quartz, illite, chlorite and kaolinite with some admixture of jarosite reflecting a more acidic environment. Geochemical modeling of two acid ponds indicated that the saturation indices of schwertmannite and nanosized e-Fe2O3 (Fe3+ oxide polymorph) were closest to thermodynamic equilibrium state with water, varying from −1.44 to 3.05 and from −3.42 to 6.04, respectively. This evidence matches well with the obtained mineralogical results.

Anticorrelation between low δ13C of eclogitic diamonds and high δ18O of their coesite and garnet inclusions requires a subduction origin

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Early diagenesis of sulfur in a tropical upwelling system, Cabo Frio, southeastern Brazil

The early diagenesis of sulfur was assessed in four short sediment cores on the continental shelf off southeastern Brazil that were deposited under the influence of an upwelling tropical system. This tropical upwelling area allows a direct focus on the coupled roles of hydrodynamic- and bioturbation-driven influences on sulfate reduction, sulfide re-oxidation and corresponding stable sulfur isotope signal formation. Under the depositional conditions of Cabo Frio, the degree of reactive iron pyritization was limited by both dissolved sulfide availability and pyrite oxidation events. Textural analyses of pyrite framboids provide evidence of re-oxidation processes, reflecting dynamic redox conditions in the sediments. The isotope composition of pore-water sulfate remained close to the modern seawater value, but very light stable sulfur isotope ratios ( 34 S/ 32 S) of chromium reducible sulfur (essentially pyrite) are found that reflect intense bioturbation-induced sulfur re-cycling. The sulfur isotope signatures developing in these tropical upwelling sites are similar to those of modern euxinic systems, although they are caused by a superimposition of sulfate reduction and an intense oxidative sulfur cycle.

Exploring subsistence and cultural complexes on the south coast of Papua New Guinea using palaeodietary analyses

We present the results of a palaeodietary study of a skeletal sample (∼800–300 BP) from the south coast of Papua New Guinea (Nebira, site ACJ) using multiple stable isotope analysis of bone collagen. The carbon, nitrogen and sulphur stable isotope ratios of 28 individuals (n = 12 males, n = 13 females and n = 3 subadults) suggested the diet at Nebira was based on C3 plants (likely starchy vegetable staples) and included protein resources from the surrounding forested areas and C3/C4 savannah grasslands such as wallaby and other wild animals. Domestic species (e.g. Sus scrofa, Canis familiaris and Gallus gallus) may also have been consumed but could not be differentiated from wild species by stable isotope analysis. There were no significant differences in stable isotope values between males and females, but the δ34S values of the juveniles suggest they may have consumed varied protein resources. The sulphur stable isotope ratios indicate there was no discernable marine component in the diet of any of the individuals from Nebira. The stable isotope results are interpreted within a wider context of Papuan south coast trade and exchange systems in an attempt to understand local interaction in the region.