Stable Sulfur Isotope Ratios Research Articles

Determination of food sources of marine invertebrates from a subtidal sand community using analyses of fatty acids and stable isotopes

The fatty acid compositions and stable isotope ratios of carbon, nitrogen, and sulfur were analyzed in the bivalve mollusks Mactra chinensis, Pandora pulchella, Felaniella usta, and Megangulus zyonoensis, the polychaete Chaetopterus cautus, and the main sources of organic matter in a subtidal sand bottom community in Vostok Bay (Sea of Japan). The fatty acid composition and stable isotope ratios of some bivalves is likely to be indicative of substantial inputs from benthic microalgae and an important role of microbial food chains. Only the filter-feeding polychaete C. cautus showed similarity in these characteristics to suspended particulate organic matter synthesized by phytoplankton. It is suggested that the contribution of benthic microalgae to the diet of a consumer organism, inferred solely from the carbon stable isotope analysis, can be significantly overestimated.

Reconstruction of changes in global sulfur cycling from marine sulfate isotopes

Stable isotope ratios of sulfur ( δ 34S) and oxygen ( δ 18O) in marine sulfate respond to changes in fluxes and processes in the global sulfur cycle. The two isotope systems respond on different time scales to different factors affecting the global sulfur cycle. Sulfur isotopes respond primarily to the relative fluxes of weathering-derived sulfate to the oceans versus the net flux of sulfur exported from the oceans as pyrite in marine sediments. At the present day, this response is relatively slow (∼ 20 Ma) because of the large size of the marine sulfate reservoir; ancient oceans had lower sulfate concentrations and thus sulfate residence times may have been shorter. The δ 34S of marine sulfate is also sensitive to the development of a significant reservoir of H 2S in ancient stratified oceans. Sulfate–oxygen isotopes respond primarily to changes in the cycling of sulfur in the oceans and marine sediments. Sulfur disproportionation, oxic and anaerobic sulfide oxidation all impart different δ 18O signatures to marine sulfate; the relative importance of these different processes is in turn controlled by the distribution of redox conditions and microbial ecology of sea-floor sediments. The mutual interpretation of changes in marine sulfate δ 34S and δ 18O can thus give rather precise information on the nature of changes in global sulfur cycling. Recently, records of isotope compositions of ancient marine sulfate have become available through the analysis of carbonate-associated sulfate (CAS) in limestones and marine biogenic barite, both of which provide far more continuous records than previous data based primarily on marine evaporite sulfate minerals. We review a number of case studies which use sulfur or combined sulfur and oxygen isotopic records derived from CAS and biogenic barite. Proterozoic CAS-sulfur isotope datasets often show marked variations over very small stratigraphic intervals (e.g. 20‰ over 300 m). When examined in conjunction with estimates of deposition rates, they are used to infer a new evolutionary curve of marine sulfate concentrations and therefore a protracted oxidation of the Earth's biosphere. Through the Cretaceous–Tertiary interval, the marine sulfate–sulfur record is characterised by significant periods of relative stability punctuated by phases of more rapid change (limited to 7‰ variation over the last 130 Ma). The Carboniferous was characterized essentially by a gradual change of 9‰ over 60 Ma. By contrast, at the Permian–Triassic boundary, extreme changes occur over very short geological time scales (14‰ over < 1 Ma); simple mass balance considerations suggest the development of a large, relatively short-lived, reservoir of H 2S in the oceanic water column at this time. In this case, it is the short time scale of the response of the sulfate–oxygen record that enables the interpretation of rapid changes in oceanic redox state. Over the last 10 Ma, sulfate–oxygen δ 18O in biogenic barite exhibits large isotope changes (∼ 7‰) that occur independently of those in sulfate–sulfur. These changes must reflect changes in depositional/redox environment at the ocean margins and/or changes in microbial cycling of sulfur, but the exact cause remains controversial. Our limited understanding of the influence of redox environment and sediment microbial ecology on sulfur cycling currently restricts the level to which we are able to interpret such changes in marine sulfate δ 18O.

The Chemistry of Soils, Rocks and Plant Bioindicators in Three Ecosystems of the Holy Cross Mountains, Poland

In June of 2000, biogeochemical study was carried out in three ecosystems of the Holy Cross Mountains (south-central Poland). This paper presents element concentrations and stable sulfur (and in one site lead) isotope ratios in rocks, detailed soil profiles, and plant bioindicators including epiphytic lichen Hypogymnia physodes (L.) Nyl., mosses (Pleurozium schreberi (Brid.) Mitt., Hypnum cupressiforme Hedw. S. Str., Hylocomium splendens (Hedw.) B.S.G.), Scots pine (Pinus sylvestris L.), common birch (Betula pendula Roth.), aspen (Populus tremula L.) and English oak (Quercus robur L.). Chemical analyses were performed with ICP-AES and AAS methods in the accredited laboratory (Central Chemical Laboratory of the Polish Geological Institute in Warsaw). The principal objective of this study was to compare the chemical composition of rocks, soils and selected plant bioindicators between investigation sites using the same methods of sample collection, preparation and analyses. The results of this study have shown that there is a high variability in concentrations of elements in plant bioindicators from the same sites that can not be explained only by soil properties or anthropogenic influence. This conclusion indicates that for biomonitoring purposes (especially with vascular plants) we cannot neglect individual features of the species examined.

バイカル湖堆積物における過去25万年間の炭素・窒素・硫黄の安定同位体組成変動

バイカル湖堆積物における過去25万年間の炭素・窒素・硫黄の安定同位体組成変動

Geochemistry, alteration, and genesis of gold mineralization in the Okote area, southern Ethiopia

Ductile shear zone hosted mesothermal gold mineralization of the Okote area is located in southern Ethiopia. Three N-S striking ductile shear zones, with different intensity of shearing and hydrothermal alteration, cut the mafic rocks. The gold-mineralized parts of these shear zones reveal zonings: slightly altered but not sheared protolith at shear boundaries, transitional zone, and mylonite zones. Auriferous quartz-carbonate-tourmaline veins occur mainly in the mylonite zone. The ore minerals of the veins and their wall rocks are pyrite, chalcopyrite, pyrrhotite, gold, and accessory chalcocite, covellite, galena, and melonite (NiTe2). The textural relationships among minerals in these alteration zones indicate that epidote, ferroamphiboles, and magnetite were formed first, followed by chlorite, ankerite, pyrrhotite, chalcopyrite I, and K-feldspar, and, finally, calcite, chlorite, biotite, tourmaline, gold, and galena. Primary fluid inclusion data from auriferous type 2 quartz veins (qv2) indicate aqueous-carbonic inclusions with low salinity (<6.59 wt % NaCl equivalent), 0.38 to 0.90 g/cm3 in density that homogenized at 218°C to 345°C. Most of the inclusions decrepitate at 220°C to 388°C before or immediately after homogenization. Chlorite geothermometry gives temperatures of formation that range from 230°C to 410°C with modes at 250°C and 380°C, in good agreement with fluid inclusion data. Chemical mass balance studies, using samples from meta-gabbro and alteration products, reveal addition of K2O, P2O5, volatile, Ba, Sr, V, and Cu into wall rock and loss of MgO, CaO, and SiO2 from the wall rock to the veins accompanying gold mineralization. Chondrite-normalized REE patterns of samples show HREE enrichments in meta-gabbro, a flat pattern with a positive Eu anomaly in the epidote-amphibole-magnetite rich transitional zone, and HREE enrichment with a negative Cc anomaly in the mylonite zone. Stable isotope ratios of sulfur, carbon, and oxygen indicate a predominance of deep-seated fluids of metamorphic and magmatic signatures. Considering the combined structural and spatial association of gold with greenschist facies, the mineral and wall rock chemistry, fluid inclusion data, and isotopic data presented here, we conclude that the Okote gold mineralization formed by interaction of structurally focused hydrothermal fluids with mafic rocks.

03/02612 Stable sulfur isotope ratio indicates long-term changes in sulfur deposition in the Broadbalk Experiment since 1845: Zhao, F. J. et al. Journal of Environmental Quality, 2003, 32, (1), 33–39

03/02612 Stable sulfur isotope ratio indicates long-term changes in sulfur deposition in the Broadbalk Experiment since 1845: Zhao, F. J. et al. Journal of Environmental Quality, 2003, 32, (1), 33–39

Variation in trophic shift for stable isotope ratios of carbon, nitrogen, and sulfur

Use of stable isotope ratios to trace pathways of organic matter among consumers requires knowledge of the isotopic shift between diet and consumer. Variation in trophic shift among consumers can be substantial. For data from the published literature and supplementary original data (excluding fluid‐feeding consumers), the mean isotopic shift for C was +0.5±0.13‰ rather than 0.0‰, as commonly assumed. The shift for C was higher for consumers analyzed as muscle (+1.3±0.30‰) than for consumers analyzed whole (+0.3±0.14‰). Among consumers analyzed whole, the trophic shift for C was lower for consumers acidified prior to analysis (−0.2±0.21‰) than for unacidified samples (+0.5±0.17‰). For N, trophic shift was lower for consumers raised on invertebrate diets (+1.4±0.21‰) than for consumers raised on other high‐protein diets (+3.3±0.26‰) and was intermediate for consumers raised on plant and algal diets (+2.2±0.30‰). The trophic shift for S differed between high‐protein (+2.0±0.65‰) and low‐protein diets (‐0.5±0.56‰). Thus, methods of analysis and dietary differences can affect trophic shift for consumers; the utility of stable isotope methods can be improved if this information is incorporated into studies of trophic relationships. Although few studies of stable isotope ratios have considered variation in the trophic shift, such variation is important because small errors in estimates of trophic shift can result in large errors in estimates of the contribution of sources to consumers or in estimates of trophic position.

Stable Sulfur Isotope Ratio Indicates Long-Term Changes in Sulfur Deposition in the Broadbalk Experiment since 1845

Stable Sulfur Isotope Ratio Indicates Long-Term Changes in Sulfur Deposition in the Broadbalk Experiment since 1845

Stable sulfur isotope ratio indicates long-term changes in sulfur deposition in the Broadbalk experiment since 1845.

Archived wheat (Triticum aestivum L.) grain and straw, and soil samples from the control plot of the Rothamsted Broadbalk Experiment, located in southeastern England and established in 1843, were used to investigate the effects of dramatically changing SO2 pollution inputs on the concentrations and stable isotope ratios (delta34S) of S in the samples. Representative coal samples from UK major coal fields were also determined for delta34S. Concentrations of S showed no clear trends in either grain or straw over the 155 years from 1845 to 1999. However, grain and straw delta34S decreased rapidly from 6 to 7/1000 in 1845 to -2 to -5/1000 in the early 1970s, and since then have increased to 0.5 to 2/1000 in the late 1990s. This pattern mirrored the trend of UK SO2 emissions over the 155 years. Both grain and straw delta34S correlated strongly and negatively with UK SO2 emissions (R2 > 0.89), but the relationships were different for the pre- and post-1970 data sets. Soil delta34S also decreased considerably, from 8.2/1000 in 1865 to 3.7 to 4.5/1000 during 1965-1999. A negative delta34S value was inferred for the anthropogenic S deposited at the experimental site before 1970, and further confirmed by negative delta34S values (-6 to -10/1000) found in the coal samples from southeastern England and southern Wales. Based on the S isotope ratios, we estimated that anthropogenic S contributed 62 to 78% of the S uptake by wheat at the peak of SO2 emissions, and accounted for 28 to 37% of the topsoil S in 1965.

Isotopic study of sulfate sources and residence times in a subalpine watershed

Stable sulfur and oxygen isotope ratios and naturally occurring 35SSO4 activities were used to examine sulfate sources, address the role of sulfur dynamics, and estimate residence times of atmospherically derived sulfate in Loch Vale Watershed, Colorado. In 1996, surface water samples from small streams flowing through talus, forest, and wetland areas had δ34SSO4 values ranging from 1.8 to 3.7‰. Values of δ18OSO4 at the three sites ranged from –1.3 to 3.7‰. Average δ34SSO4 and δ18OSO4 values in Loch Vale precipitation (1991–1999) are higher (5.2 and 13.6, respectively) than surface water values, indicating that some of the deposited sulfate is transformed and/or mixed with other sulfur sources in the watershed (e.g. mineral and organic sulfur). Sulfate ages determined by 35SSO4 activities support this and show that deposited sulfate may be stored on a timescale of 1 year or more prior to being released to surface waters.

Survey of stable sulfur isotope ratios (34S/32) of sulfite and sulfate in foods

A study was conducted to determine the natural abundance sulfur isotope ratios in foods containing sulphite preservatives. This involved determining (1) the accuracy and repeatability of sulfur isotope ratios measured using an elemental analyser (EA) coupled to an isotope ratio mass spectrometer (IRMS); and (2) the isotope ratios of 21 samples of commercially available S(IV) oxo-anion compounds, nine samples of S(VI) sulfate salts and the isotope ratios of the sulfate obtained by modified Monier-Williams distillation of SO2 from 33 retail foods containing sulfite preservatives. The sulfur isotope ratio data for SO2 recovered from foodstuffs showed a large spread of results, which suggested that the SO2 derived from sulfite preservatives does not have a distinctive sulfur signature ratio. The range of results (3.1–52.1) overlapped with that found for a range of commercially available sulfite and sulfate reagents commonly used to preserve food (sulfites 2.5–13.7, sulfates 10.0–16.9). Whilst the variability in isotope ratios originated from the food samples themselves, evidence from the analysis of SO2 gas suggested that isotope fractionation during dissolution, reaction and recovery was also a confounding factor.

Evolution of water chemistry in natural acidic environments in Yangmingshan, Taiwan

In Yangmingshan National Park, located in the northern part of the Taiwan Island, there is a very rare area where fish (Channa asiatica) live in spite of acid environments. The origin of the acid in local acid ponds and rivers and the evolution of the water chemistry are discussed on the basis of sulfur stable isotope ratios and chemical equilibria. One of the sources of the acid is sulfuric acid, which is derived from the oxidation of hydrogen sulfide in volcanic gas gushing out from fumaroles around the area and from acid deposition supplied from Taipei City. It is also derived from the oxidation of pyrite: the sulfur stable isotope ratios of delta 34S of +1@1000 to +4@1000 (relative to CDT) of sulfate in acid pond waters (pH 3-4) could be related to those of hydrogen sulfide in volcanic gas, pyrite in local pond sediments and soils, and sulfate in rain water. One acid source is sulfuric and hydrochloric acids arising in springs from geothermal activity: the delta 34S values were characterised by +13@1000 to +17@1000 sulfate-S, which was provided by a disproportionation reaction of sulfur dioxide in the depths. Another acid source could be the oxidation of iron(II). Under acidic conditions, the water-rock reaction gives rise to high concentrations of aluminium and iron. While flowing down surface streams, iron(II) is oxidised to iron(III) and then hydrolysed to cause further acidification under oxic conditions. The concentrations of iron and aluminium are controlled by redox and dissolution equilibria.

In situ assessment of microbial sulfate reduction in a petroleum-contaminated aquifer using push–pull tests and stable sulfur isotope analyses

Anaerobic microbial activities such as sulfate reduction are important for the degradation of petroleum hydrocarbons (PHC) in contaminated aquifers. The objective of this study was to evaluate the feasibility of single-well push–pull tests in combination with stable sulfur isotope analyses for the in situ quantification of microbial sulfate reduction. A series of push–pull tests was performed in an existing monitoring well of a PHC-contaminated aquifer in Studen (Switzerland). Sulfate transport behavior was evaluated in a first test. In three subsequent tests, we injected anoxic test solutions (up to 1000 l), which contained 0.5 mM bromide (Br −) as conservative tracer and 1 mM sulfate (SO 4 2−) as reactant. After an initial incubation period of 42.5 to 67.9 h, up to 1100 l of test solution/groundwater mixture was extracted in each test from the same location. During the extraction phases, we measured concentrations of relevant species including Br −, SO 4 2− and sulfide (S(-II)), as well as stable sulfur isotope ratios ( δ 34S) of extracted, unconsumed SO 4 2− and extracted S(-II). Results indicated sulfate reduction activity in the vicinity of the test well. Computed first-order rate coefficients for sulfate reduction ranged from 0.043±0.013 to 0.130±0.015 day −1. Isotope enrichment factors ( ε) computed from sulfur isotope fractionation of extracted, unconsumed SO 4 2− ranged from 20.2±5.5‰ to 22.8±3.4‰. Together with observed fractionation in extracted S(-II), isotope enrichment factors provided strong evidence for microbially mediated sulfate reduction. Thus, push–pull tests combined with stable sulfur isotope analyses proved useful for the in situ quantification of microbial sulfate reduction in a PHC-contaminated aquifer.

Use of stable sulfur isotopes to identify sources of sulfate in Rocky Mountain snowpacks

Stable sulfur isotope ratios and major ions in bulk snowpack samples were monitored at a network of 52 high-elevation sites along and near the Continental Divide from 1993 to 1999. This information was collected to better define atmospheric deposition to remote areas of the Rocky Mountains and to help identify the major source regions of sulfate in winter deposition. Average annual δ 34S values at individual sites ranged from +4.0 to +8.2‰ and standard deviations ranged from 0.4 to 1.6‰. The chemical composition of all samples was extremely dilute and slightly acidic; average sulfate concentrations ranged from 2.4 to 12.2 μeq l −1 and pH ranged from 4.82 to 5.70. The range of δ 34S values measured in this study indicated that snowpack sulfur in the Rocky Mountains is primarily derived from anthropogenic sources. A nearly linear relation between δ 34S and latitude was observed for sites in New Mexico, Colorado, and southern Wyoming, which indicates that snowpack sulfate in the southern part of the network was derived from two isotopically distinct source regions. Because the major point sources of SO 2 in the region are coal-fired powerplants, this pattern may reflect variations in the isotopic composition of coals burned by the plants. The geographic pattern in δ 34S for sites farther to the north in Wyoming and Montana was much less distinct, perhaps reflecting the paucity of major point sources of SO 2 in the northern part of the network.

Identification of food sources of invertebrates from the seagrass Zostera marina community using carbon and sulfur stable isotope ratio and fatty acid analyses

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 220:103-117 (2001) - doi:10.3354/meps220103 Identification of food sources of invertebrates from the seagrass Zostera marina community using carbon and sulfur stable isotope ratio and fatty acid analyses V. I. Kharlamenko*, S. I. Kiyashko**, A. B. Imbs, D. I. Vyshkvartzev Institute of Marine Biology, Far East Branch, Russian Academy of Sciences, Vladivostok, 690041 Russia *Present address: Kamchatka Research Institute of Fisheries and Ocenography, Naberegnaya 18, Petropavlovsk-Kamchatsky 683002, Russia **Corresponding author. E-mail: sekiyash@hotmail.com ABSTRACT: Carbon and sulfur stable isotope ratios, as well as fatty acid composition of tissues, of dominant consumer species were determined and compared to those of potential food sources in an isolated community of Zostera marina in a shallow, semi-enclosed inlet of the Sea of Japan. Of the 6 dominant species of invertebrates, 4 species were enriched in 13C, compared to all sampled carbon sources alternative to Z. marina. Among them, the grazing gastropods Littorina squalida and Homalopoma sangarense exhibited the most enriched δ13C values. On the dual δ13C versus δ34S plot, these mollusks occupy an intermediate position between Z. marina and epiphytes, suggesting nearly equal proportions of organic carbon from both nutritional sources. In lipids of H. sangarense there was a high content of the 18:1(n-7) acid characteristic of aerobic bacteria; however, another grazer (L. squalida) showed the lowest content of bacterial fatty acids among all consumers. Other highly 13C-enriched consumers were the surface-deposit-feeding mollusks, the gastropod Batillaria cumingii and the bivalve Macoma incongrua; however, their δ34S values were markedly lower than those of any of the primary producers sampled, including Z. marina. Although the high δ13C values of grazers and surface-deposit feeders are suggestive of a great contribution of Z. marina organic carbon, no substantial concentrations of seagrass marker fatty acids were detected. Significant interspecific variations of both the sulfur isotope ratios and the fatty acid composition of these consumers suggest that there are a variety of pathways by which seagrass organic matter reaches invertebrates at lower trophic levels of the community food web. Dominant filter feeders, the bivalves Ruditapes philippinarum and Pillucina pisidium, had carbon drastically different in isotopic composition from Z. marina organic matter. Body tissues of P. pisidium and especially its gills, which bear symbiotic bacteria, were dramatically depleted both in 13C and 34S compared to all sources of photosynthetically fixed carbon in the bay. Very low δ13C and δ34S values of P. pisidium body together with a high content of 18:1(n-7) acid suggest a leading role of sulfur-oxidizing symbiotic bacteria in the nutrition of this species. R. philippinarum was only slightly 13C-enriched, compared to POM, and was the only consumer which had the high concentration of fatty acids characteristic of plankton, particularly 22:6(n-3). At the same time, it was much more 34S-depleted than would be expected, assuming negligible contribution of Z. marina detritus to its food. This mollusk showed a high content of branched fatty acids, especially the iso17:0 and anteiso17:0 acids characteristic of bacteria from sediment; this suggests that R. philippinarum assimilated notable amounts of bacteria from resuspended sediment. Furthermore, the contribution of 34S-depleted bacteria, which inhabit reduced sediment, to R. philippinarum nutrition was high enough to result in the observed depletion of 34S in mollusks. Further progress in food web studies of seagrass ecosystems using a complex of multiple stable isotope and fatty acid analyses would appear possible on the basis of analysis of separate components of the seagrass epiphytic community and micro- and meiobenthic organisms, inhabiting surface sediments. KEY WORDS: Eelgrass community · Mollusks · Stable carbon isotope · Stable sulfur isotope · Fatty acids · Food web Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 220. Online publication date: September 27, 2001 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2001 Inter-Research.

Trophic importance of epiphytic algae in subtropical seagrass beds: evidence from multiple stable isotope analyses

Multiple stable isotope analyses were employed to examine food web dynamics in a northern Gulf of Mexico seagrass system in which epiphytic algae were the single most important primary productivity component, being responsible for 46 and 60 % of total system and benthic primary production, respectively. The seagrass Halodule wrightii Ascherson contributed only 13% to total system primary production on an annual basis. Stable isotope ratios of carbon (δ 13 C), nitrogen (δ 15 N), and sulfur (δ 34 S) were measured for producer and consumer samples collected from May 1989 through November 1992. Epiphytes and leaves of H. wrightii had distinct δ 13 C values (-17.5 vs -12‰, respectively) as well as distinct δ 34 S values‰ (+18 vs +11‰, respectively). δ 13 C values for the sand microflora, occasional macroalgae, and phytoplankton were -16, -17, and -22‰, respectively; δ 15 N values were lowest for epiphytes and H. wrightii (+6‰) and highest for phytoplankton (+10‰). Virtually all consumers had δ 13 C values that fell within a narrow range of - 20 to -15%o, which included all δ 13 C values of epiphytes and the sand microflora but none of those for either H. wrightii or phytoplankton. Values for δ 15 N for consumers fell within a range of + 8 to +16‰ spanning herbivorous species with diets of microalgae to carnivorous species feeding at secondary to tertiary levels in the local food webs. Consumer values for δ 34 S ranged from +4 to +20‰ (mean = 14.2‰), and indicate a stronger influence of seawater-derived sulfate than sediment-associated sulfides. The stable isotope data, in combination with measured high biomass and primary production rates of the epiphytic algae, strongly suggest that these algae are the primary source of organic matter for higher trophic levels in seagrass beds of Mississippi Sound. The contribution af H. wrightii to the food web appears to be minimal. The overall picture that has emerged based on the present and previous stable isotope studies is one of the major trophic importance of benthic microalgae (i.e. epiphytic and sediment-associated) in seagrass beds.

Stable carbon, nitrogen, and sulfur isotope ratios in riparian food webs on rivers receiving sewage and pulp-mill effluents

We examined spatial trends in ratios of stable isotopes of nitrogen (δ15N), carbon (δ13C), and sulfur (δ34S) in riparian food webs leading to a riparian, insectivorous bird species, the tree swallow (Tachycineta bicolor), on rivers receiving pulp-mill effluent and municipal sewage and compared them with ratios of these isotopes in components of the effluents themselves. The study was conducted on two rivers in western Canada at sites upstream and downstream from sewage and pulp mill effluent sources. Municipal sewage contained materials with δ15N or δ13C values that were distinct from background conditions in the receiving environment. Pulp-mill effluent contained materials with δ34S values that were distinct from those at upstream sites on the rivers. At both locations, effluent-derived nitrogen and sulfur were observed in algae and suspended sediments at sites downstream from the effluent sources. This was also observed in adult aquatic insects, the one exception being that uptake of effluent-derived nitrogen was detected isotopically at only one location. Tree swallows' use of sewage-derived nitrogen was evident only at one location, while use of pulp-mill-derived sulfur was evident only at the other location. Our study demonstrates the usefulness and limitations of measuring stable isotopes for tracing the movement of nutrients derived from sewage and pulp-mill effluent in freshwater ecosystems and, further, indicates that such tracing may be extended to riparian species feeding on aquatic prey.

Stable carbon, nitrogen, and sulfur isotope ratios in riparian food webs on rivers receiving sewage and pulp-mill effluents

Stable carbon, nitrogen, and sulfur isotope ratios in riparian food webs on rivers receiving sewage and pulp-mill effluents

The Role of Tidal Salt Marsh as an Energy Source for Marine Transient and Resident Finfishes: A Stable Isotope Approach

Stable isotope ratios of carbon, nitrogen, and sulfur (δ13C, δ15N, and δ34S) in bay anchovy Anchoa mitchilli and white perch Morone americana from Delaware Bay were a function of capture location and, for restored tidal salt marshes, possibly a function of the relative position of the marsh restoration trajectory. White perch collected in polyhaline restoration and reference (Moore's Beach) sites had stable isotope signatures that reflected contributions from both benthic microalgae and Spartina alterniflora. Isotope values from white perch captured at the reference site were slightly enriched compared with those captured at the restoration sites. At upper estuary oligo–mesohaline locations, Phragmites australis contributed to the isotopic composition of both species. Although P. australis was not dominant at the reference marsh (Mad Horse Creek), it also seemed to influence the flow of nutrients into these species. White perch were not collected in open waters of Delaware Bay, but bay anchovy were abundant at offshore sampling stations. A striking result of this study was that stable isotopes that originated in macrophytes and benthic microalgae of salt marshes occurred ubiquitously among bay anchovy collected several kilometers from shore. Interestingly, fish from Mad Horse Creek, a reference marsh where Phragmites was abundant only along creek banks, were intermediate in their isotopic composition. Although benthic microalgal signatures varied both within and among sites, the isotopic composition of bay anchovy and white perch was clearly influenced by these primary producers across all marsh types. Particulate organic matter (POM) appeared to play a lesser role in bay anchovy and white perch nutrition, although depletion of POM sulfur due to the presence of inorganic sulfur may have led to underestimates of the contribution of phytoplankton. Further studies are required to elucidate the relative role of phytoplankton in the trophodynamics of these species.

Bone chemistry and palaeodiet: Bioarchaeoiogical research at Roonka Flat, lower Murray River, South Australia 1983–1999.

The predominance of stone and bone in prehistoric archaeological deposits has resulted in the development of a range of methods to extract information from these important cultural resources. Since the development of radiocarbon dating in the late 1940s, a variety of analytical techniques derived from chemistry have been applied to archaeological research problems. Many of these methods have been employed in the analysis of archaeological skeletal remains, both human and faunal. In addition to providing information about chronology, chemical analyses of bones and teeth offer independent scientific methods to address past diet, climate and ecology that supplement conventional approaches (Price 1989; Schoeninger and Moore 1992; MacFadden and Bryant 1994; Pate 1994, 1997a; Bocherens et al. 1999). During the 1970s and early 1980s a variety of analytical techniques derived from chemistry emerged in the archaeological literature as a means to reconstruct past dietary patterns. The inorganic and organic chemical constituents of bone provide a record of long-term dietary intake. Elements and amino acids liberated by the digestion of foods are incorporated into the inorganic hydroxyapatite, organic collagen, and non-collagenous protein components of bone throughout a vertebrate's lifetime. In contrast, the chemical composition of teeth reflect the early stages of life during dental development. In some cases, chemical concentrations in bones and teeth can be related quantitatively to the chemical composition of past diet. Thus, chemical analyses of archaeological teeth and bones have the potential to provide information about juvenile and long-term dietary patterns, respectively, in both humans and associated fauna. Elemental analyses of inorganic hydroxyapatite focused primarily on strontium (Sr), barium (Ba) and magnesium (Mg). The concentrations of these alkaline earth metals in bone and tooth mineral reflect percentages of meat vs. plant foods and marine vs. terrestrial foods in the diet (Boaz and Hampel 1978; Sillen and Kavanagh 1982; Connor and Slaughter 1984; Klepinger 1984). In addition, strontium isotope ratios in bones and teeth were employed to distinguish marine vs. terrestrial inputs to prehistoric human diets (Ericson 1985). Many of these early elemental studies addressed relationships between dietary variability and mortuary variability as a means to assess past social differentiation (Brown 1974; Gilbert 1977; Lambert et al. 1979; Schoeninger 1979; Blakely and Beck l98 1; Pate 1984). Stable carbon, nitrogen and sulphur isotope ratios in the collagen and non-collagenous protein components of bones and teeth record the relative amounts of marine vs. terrestrial foods and C 3 vs C 4 , plants in individual diets (Schoeninger and DeNiro 1984; Peterson and Fry 1987). Stable carbon and oxygen  isotope ratios in the inorganic carbonate and phosphate portions of bone and tooth apatite can supplement these organic analyses (Krueger and Sullivan 1984; Sponheimer and Lee-Thorp 1999). Initial archaeological applications involved stable carbon isotopes in bone collagen. These studies addressed the relative contribution of photosynthetically distinct plants, e.g. corn (C 3 ) vs. wheat (C 4 ), to prehistoric human diets (van der Merwe and Vogel 1978; Bender et al. 1981; van der Merwe 1982). Subsequent research involved stable carbon and nitrogen isotope analyses of prehistoric human bone collagen to infer relative consumption of marine vs. terrestrial foods (Norr; 1981, 1982; Chisholm et al. 1982; 1983; Schoeninger et al. 1983; Hobson and Collier 1984). More recently, stable oxygen isotopes have been employed to provide information about trophic level and diets based on browsing vs. grazing (Kohn et al. 1996; Wright and Schwarcz 1999). Because of the substantial difficulties associated with quantitative inferences regarding prehistoric human dietary composition from archaeological food remains and artefacts, chemical palaeodietary techniques involving analyses of human and faunal bones and teeth received great attention following their introduction in various parts of the world and became widespread in the archaeological and physical anthropological literature during the 1990s. Â