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Proportions Of Convective And Stratiform Precipitation Revealed In Water Isotope Ratios, Pradeep K. Aggarwal, Ulrike Romatschke, Luis Araguas-Araguas, Dagnachew Belachew, Fred J. Longstaffe, Peter Berg, Courtney Schumacher, Aaron Funk

Earth Sciences Publications

Tropical and midlatitude precipitation is fundamentally of two types, spatially-limited and high-intensity convective or widespread and lower-intensity stratiform, owing to differences in vertical air motions and microphysical processes governing rain formation. These processes are difficult to observe or model and precipitation partitioning into rain types is critical for understanding how the water cycle responds to climate changes. Here, we combine two independent data sets – convective and stratiform precipitation fractions, derived from the Tropical Rainfall Measuring Mission satellite or synoptic cloud observations, and stable isotope and tritium compositions of surface precipitation, derived from a global network – to show that …

Agriculture Causes Nitrate Fertilization Of Remote Alpine Lakes, Elizabeth J. Hundey, Sam S.D. Russell, Fred Longstaffe, Katrina A. Moser

Earth Sciences Publications

Humans have altered Earth’s nitrogen cycle so dramatically that reactive nitrogen (Nr) has doubled. This has increased Nr in aquatic ecosystems, which can lead to reduced water quality and ecosystem health. Apportioning sources of Nr to specific ecosystems, however, continues to be challenging, despite this knowledge being critical for mitigation and protection of water resources. Here we use D¹⁷O, d¹⁸O and d¹⁵N from Uinta Mountain (Utah, USA) snow, inflow and lake nitrate in combination with a Bayesian-based stable isotope mixing model, to show that at least 70% of nitrates in aquatic systems are anthropogenic …

Oxygen-Isotope Variations In Post-Glacial Lake Ontario, Ryan Hladyniuk, Fred J. Longstaffe

Earth Sciences Publications

The role of glacial meltwater input to the Atlantic Ocean in triggering the Younger Dryas (YD) cooling event has been the subject of controversy in recent literature. Lake Ontario is ideally situated to test for possible meltwater passage from upstream glacial lakes and the Laurentide Ice Sheet (LIS) to the Atlantic Ocean via the lower Great Lakes. Here, we use the oxygen-isotope compositions of ostracode valves and clam shells from three Lake Ontario sediment cores to identify glacial meltwater contributions to ancient Lake Ontario since the retreat of the LIS (~16,500 cal [13,300 ¹⁴C] BP). Differences in mineralogy …

Limiting The Impact Of Destructive Analytical Techniques Through Sequential Microspatial Sampling Of The Enamel From Single Teeth, Alexis E. Dolphin, Mathew A. Teeter, Christine D. White, Fred J. Longstaffe

Earth Sciences Publications

A fundamental research concern within contemporary bioarchaeology is the sensitive balance between the preservation of human remains and the use of destructive techniques to collect information. Here we describe one example of how multiple microspatial destructive/semi-destructive techniques may be carried out in sequence using only the enamel of a single tooth. With careful planning of both sample preparation strategies and sequencing of sampling methods, it is possible to produce multiple datasets, and yet to retain material for future analyses.

In this case, enamel from the teeth of 27 individuals who lived during the early medieval period (AD 1170-1198) in Bergen, …

Assortative Mating But No Evidence Of Genetic Divergence In A Species Characterized By A Trophic Polymorphism, Scott F. Coborne, S R. Garner, Fred Longstaffe, Bryan D. Neff

Earth Sciences Publications

Disruptive selection is a process that can result in multiple sub-groups within a population, referred to as diversification. Foraging related divergence has been described in many taxa, but many questions remain about the contribution of such divergence to reproductive isolation and potentially sympatric speciation. Here we use stable isotope analysis of diet and morphological analysis of body shape to examine phenotypic divergence between littoral and pelagic foraging ecomorphs in a population of pumpkinseed sunfish (Lepomis gibbosus). We then examine reproductive isolation between ecomorphs by comparing the isotopic compositions of nesting males to eggs from their nests (a proxy for maternal …

Climatic Cycles Recorded In Glacially Influenced Rhythmites Of The Gowganda Formation, Huronian Supergroup, Tim S. Howe, Patricia L. Corcoran, Fred Longstaffe, Elizabeth A. Webb, R Gerhard Pratt

Earth Sciences Publications

The Gowganda Formation of the 2.45–2.2 Ga Huronian Supergroup contains glacially-induced, varve-like rhythmites that potentially preserve a detailed record of climatic conditions during the Paleoproterozoic Era. Four rhythmic couplet thickness records were measured at two outcrops near Wharncliffe, Ontario for the purpose of time-series analysis. The couplets, which range from 1 to 32 mm thick, are composed of alternating layers of siltstone and claystone. Time-series analysis of the couplet thickness records using the MTM Toolkit of Mann and Lees (1996) consistently revealed periodicities in the range of 2.2–2.9 couplets per cycle, which is consistent with climatic cycles such as the …

Stable Isotopes And Selective Forces: Examples In Biocultural And Environmental Anthropology, Christine D. White, Fred J. Longstaffe

Earth Sciences Publications

No abstract provided.

A Brief Account Of New Petrographic And Isotopic Insights Into The Hertfordshire And Buckinghamshire Puddingstones Of Se England, Jennifer Huggett, Fred Longstaffe

Earth Sciences Publications

Determining the process of silicification in silcretes is essential to understanding their environmental significance. For the late Paleocene silcretes of the Anglo-Paris basin this is of particular interest due to their association with the PETM (Paleocene-Eocene Thermal Maximum). Here puddingstone samples from Hertfordshire and Buckinghamshire have been examined by optical, BSEM and CL petrography, X-ray diffraction and oxygen isotope analysis. The range of quartz sand luminescence colours indicates a diverse provenance. Flint pebbles show little variability, consistent with a single source. The oxygen isotope compositional range of the flint pebbles is consistent with chemical sedimentation at normal temperatures from Cretaceous …

Formation Of The Neoarchean Bad Vermillion Lake Anorthosite Complex And Spatially Associated Granitic Rocks At A Convergent Plate Margin, Superior Province, Western Ontario, Canada, Shuda Zhou, Ali Polat, Fred Longstaffe, Kunguang Yang, Brian J. Fryer, Crhis Weisener

Earth Sciences Publications

The Bad Vermilion Lake Anorthosite Complex (henceforth, the BVLA Complex) in western Ontario is one of the well-exposed, anorthosite-bearing, Archean layered intrusions in the Superior Province, Canada. This study presents new whole-rock major and trace element data for the various units of the Complex, oxygen isotope data for the anorthosite, and major and trace element data for the spatially associated granitic rocks intruding the BVLA Complex to constrain their petrogenetic and geodynamic origin. Zircons from granitic rocks have yielded a ²⁰⁷Pb/²⁰⁶Pb age of 2716 ± 18 Ma, constraining the minimum intrusion age of the Complex. Despite deformation …

Isotopic Anthropology Of Rural German Medieval Diet: Intra- And Inter-Population Variability, Karyn C. Olsen, Christine D. White, Fred J. Longstaffe, Frank J. Rühli, Christina Warinner, Domingo S. Salazar-Garcia

Earth Sciences Publications

This study investigates the diet of an 11th century CE parish community located in northwestern Germany. We assessed the isotopic compositions of human (n = 24) and faunal (n = 17) bone collagen (δ¹³C_col, δ¹⁵N_col) and human structural carbonate (δ¹³C_sc) using skeletal material recovered from the Dalheim cemetery. Traditional interpretation of the isotopic data indicates that Dalheim residents likely relied on a C₃ plant-based diet and consumed some terrestrial animal products without evidence of marine resource input in the diet. Bivariate and multivariate models used as an additional …

Microbially Induced Sedimentary Structures In The Paleoproterozoic, Upper Huronian Supergroup, Canada, Carolyn Hill, Patricia I. Corcoran, Rohan Aranha, Fred Longstaffe

Earth Sciences Publications

The Paleoproterozoic Gordon Lake and Bar River formations, Huronian Supergroup, contain a variety of sedimentary structures in the Flack Lake area of Ontario, Canada, that have been considered of debatable origin. We identify these structures as microbially induced sedimentary structures (MISS). The preserved MISS are related to microbial mat destruction and decay, and include sand cracks, mat chips, remnant gas domes, pyrite patches, and iron laminae. A biological origin for the fossil structures is supported by their similarities to modern and ancient documented examples of MISS, the sand-dominated nature of the substrate in which they are preserved, and key microtextures …

Taxonomy, Location Of Origin, And Health Status Of Proboscideans From Western Canada Investigated Using Stable Isotope Analysis, Jessica Z. Metcalfe, Fred Longstaffe, Christopher N. Jass, Grant D. Zazula, Grant Keddie

Earth Sciences Publications

We investigated the application of stable isotope analysis of proboscidean remains (collagen in bone/dentin/cementum and structural carbonate in enamel bioapatite) for genus-level identification of isolated specimens, assessment of geographic origins, and testing for nutritional stress. Mammoths (Mammuthus sp.) tended to have higher δ¹⁵N_col and lower δ¹³C_col than mastodons (Mammut americanum), but differences were not significant in every location. Determining the genus of isolated specimens may be possible for locations and time periods with good isotopic baselines, but environmental changes can confound interpretations. For example, an Alberta proboscidean with a δ¹⁵N …

Dentine Oxygn Isotopes (Δ18o) As A Proxy For Odontocete Distributions And Movements., Cory J.D. Matthews, Fred J. Longstaffe, Steven H. Fergispm

Earth Sciences Publications

Spatial variation in marine oxygen isotope ratios ( δ¹⁸O) resulting from differential evaporation rates and precipitation inputs is potentially useful for characterizing marine mammal distributions and tracking movements across δ¹⁸O gradients. Dentine hydroxyapatite contains carbonate and phosphate that precipitate in oxygen isotopic equilibrium with body water, which in odontocetes closely tracks the isotopic composition of ambient water. To test whether dentine oxygen isotope composition reliably records that of ambient water and can therefore serve as a proxy for odontocete distribution and movement patterns, we measured δ¹⁸O values of dentine structural carbonate (δ^{18 …}

Early Horizon Camelid Management Practices In The Nepeña Valley, North-Central Coast Of Peru, Paul Szpak, David Chicone, Jean-François Millaire, Christine D. White, Rebecca Parry, Fred Longstaffe

Earth Sciences Publications

South American camelids (llamas and alpacas) were of great economic, social and ritual significance in the pre-Hispanic Andes. Although these animals are largely limited to high-altitude (>3500 masl) pastures, it has been hypothesised that camelids were also raised at lower altitudes in the arid coastal river valleys. Previous isotopic studies of Early Intermediate Period (c. 200 BC - AD 600) and Middle Horizon (c. AD 600 - 1100) camelids support this argument. Here, we utilise carbon and nitrogen isotopic analyses of camelid bone collagen from the Early Horizon (c. 800 - 200 BC) sites of Caylán and Huambacho on …

Sources And Sinks Of Microplastics In Canadian Lake Ontario Nearshore, Tributary And Beach Sediments, Anika Ballent, Patricia L. Corcoran, Odile Madden, Paul A. Helm, Fred J. Longstaffe

Earth Sciences Publications

Microplastics contamination of Lake Ontario sediments is investigated with the aim of identifying distribution patterns and hotspots in nearshore, tributary and beach depositional environments. Microplastics are concentrated in nearshore sediments in the vicinity of urban and industrial regions. InHumber Bay and Toronto Harbour microplastic concentrations were consistently greater than 500 particles per kg dry sediment. Maximum concentrations of ~28,000 particles per kg dry sediment were determined in Etobicoke Creek. The microplastic particles were primarily fibres and fragments less than 2 mm in size. Both low- and high-density plastics were identified using Raman spectroscopy. We provide a baseline for future monitoring …

Maize Provisioning Of Ontario Late Woodland Turkeys: Isotopic Evidence Of Seasonal, Cultural, Spatial And Temporal Variation, Zoe Morris, Christine D. White, Lisa Hodgetts, Fred J. Longstaffe

Earth Sciences Publications

The isotopic composition (δ¹³C, δ¹⁵N) of bone collagen from Ontario Late Woodland archaeological turkeys was compared with that of modern Ontario wild turkeys, and archaeological turkeys from American Southwestern, Mexican and other Woodland sites to determine whether Late Woodland Ontario peoples managed wild turkeys by provisioning them with maize, the only isotopically distinct horticultural plant at that time. Despite the fact that humans from Late Woodland Western Basin and Iroquoian traditions consumed equal amounts of maize, wild turkeys utilized by the two groups exhibit different diets. Western Basin turkeys reflect a C₃-only diet, …