Disentangling climate variability and human activity in past nitrogen cycling is key to understanding ecosystems. Previous studies in Ireland observed a widespread, permanent shift in terrestrial nitrogen cycling during Later Prehistory, potentially linked to intensifying land-use. Here, we investigate whether this shift was climatically or anthropogenically driven by analysing three raised bogs-highly sensitive to climate change-using pollen, testate amoebae-inferred water-table depth and geochemical proxies (delta N-15, delta C-13(org) and C-org:N). We identify shifts in bog surface wetness, based on radiocarbon- and tephra-constrained age-depth models: wet conditions similar to 4700-4450 cal BP, a dry interval similar to 4400 cal BP, wetter conditions similar to 4300-3150 cal BP, two drought phases similar to 3150-3050 and similar to 2850-2700 cal BP (Late Bronze Age and Terminal Dowris droughts), and renewed wet conditions similar to 2600 cal BP, consistent with the 2.7 ka event. Bulk peat delta N-15 values broadly tracked bog surface wetness but were more strongly influenced by secondary decomposition, highlighting post-depositional controls. Overall, our results show that Bronze Age droughts did not produce lasting changes in peat delta N-15, indicating that sustained nitrogen cycle shifts observed by others after similar to 3000-2600 cal BP likely reflect cumulative human impacts rather than climate. (c) 2026 The Author(s). Journal of Quaternary Science Published by John Wiley & Sons Ltd.

Isotopic techniques have been used to study phenomena in the geological, environmental, and ecological sciences. For example, isotopic values of multiple elements elucidate the pathways energy and nutrients take in the environment. Isoscapes interpolate isotopic values across a geographical surface and are used to study environmental processes in space and time. Thus, isoscapes can reveal ecological shifts at local scales, and show distribution thresholds in the wider environment at the macro-scale. This study demonstrates a further application of isoscapes, using soil isoscapes of 13C/12C and 15N/14N as an environmental baseline, to understand variation in trophic ecology across a population of Eurasian badgers (Meles meles) at a regional scale. The use of soil isoscapes reduced error, and elevated the statistical signal, where aggregated badger hairs were used, and where individuals were identified using genetic microarray analysis. Stable isotope values were affected by land-use type, elevation, and meteorology. Badgers in lowland habitats had diets richer in protein and were adversely affected by poor weather conditions in all land classes. It is concluded that soil isoscapes are an effective way of reducing confounding biases in macroscale, isotopic studies. The method elucidated variation in the trophic and spatial ecology of economically important taxa at a landscape level. These results have implications for the management of badgers and other carnivores with omnivorous tendencies in heterogeneous landscapes.

Potentially Toxic Elements (PTEs) in Badgers (Meles meles), otherwise known as heavy metals, are unique amongst environmental pollutants occurring, both naturally and anthropogenically. PTEs have a broad range of negative health and environmental effects, therefore identifying their sources and pathways through the environment is imperative for public health policy. This is difficult in terrestrial systems due to the compositional nature of soil geochemistry. In this study, a compositional statistical approach was used to identify how PTEs accumulate in a terrestrial carnivorous mammal, Eurasian Badgers (Meles meles). Compositional principal component analysis (PCA) was used on geochemical data from the Tellus survey, the soil baseline and badger tissue data to map geo-spatial patterns of PTEs and show accumulative trends measured in time. Mapping PCs identified distinct regions of PTE presence in soil and PTE accumulation in badger tissues in Northern Ireland. PTEs were most elevated in liver, kidney and then muscle tissues. Liver and kidney showed the most distinct geo-spatial patterns of accumulation and muscle was the most depleted. PC1 and 2 for each type were modelled using generalised additive mixed models (GAMM) to identify trends through time. PC1 for the liver and muscle were associated with rainfall and ∂N15 in the liver, showing a link to diet and a bioaccumulation pathway, whilst PC2 for both tissues was associated with mean temperature, showing a link to seasonal activity and a bioaccessibility pathway. However, in kidney tissue these trends are reversed and PC1 was associated with bioaccessibility and PC2 with bioaccumulation. Combined these techniques can elucidate both geo-spatial trends in PTEs and the mechanisms by which they move in environment and in future may be an effective tool for assessing PTE bioavailability in environmental health surveys.

1. Ocean warming and the loss of larger (often predatory) fauna are major threats to seabed (benthic) ecosystem functioning. Yet we know little about the combined effects of warming and faunal species loss upon the marine carbon cycle. 2. Using stable-isotope pulse-chase experiments, we tested how faunal species loss affects microbial carbon sequestration and retention in intertidal sediments, under both ambient and predicted future warming conditions (ambient + 2°C), using the shore crab Carcinus maenas as a model predator. We traced the fixation and retention of a fixed dose of 13 C-labelled sodium bicarbonate within sediment organic matter and microbial biomass. 3. Carcinus presence was associated with higher total organic carbon concentration within the mesocosm sediments. Temperature had no significant effect upon sediment total organic carbon concentrations. Temperature and Carcinus presence had no significant effect on polar lipid fatty acids (PLFAs) concentrations within the sediment, which is a proxy for microbial biomass. 4. Carcinus presence increased retention of 13 C-labelled carbon within the sediment organic matter pool under future warming conditions. Retention of the 13 C-label within the microbial PLFAs decreased significantly under future-warming conditions. 5. Changes in the relative abundance of PLFAs revealed increased contribution of microeukaryotes to the microbial community under ambient conditions, in the absence of Carcinus . PLFA profiles revealed significant changes in 13 C-label retention within the bacteria and microeukaryotes, driven by interactions between Carcinus presence and temperature. species ocean warming a pronounced effect upon marine carbon Experiments were conducted over 4 weeks (28 days). A single male crab (carapace width = 3.47 [± 0.14] cm, wet biomass = 9.66 [± 2.21] g) placed into five ambient and five warmed mesocosms 7 days after the incubations commenced; a 24 mg (0.1 g.m -2 ) dose of 13 C-labelled sodium bicarbonate was sprayed directly onto the sediment surface of all mesocosms on day 21. The experiments were then incubated for a further 5 days and then destructively sampled to quantify 13 C-incorporation and retention in microbial biomass and the sediment organic matter pool, following Middelburg et al. (2000). Changes in the biomass and spatial variability of the sediment microphytobenthos (MPB) were measured within each mesocosm using a BBE Moldänke BenthoTorch [BBE Moldänke Gmbh, Schwentinental, Germany] to quantify surficial chlorophyll a (Chl a ) concentrations after 7 (Week 0), 14 (Week 1), 21 (Week 2) and 28 (Week 3) days (Kahlert & McKie 2014). At each interval five replicate measurements of the surficial Chl a were made, within each mesocosm. Mean Chl a concentrations within each mesocosm were estimated as a proxy for MPB biomass, with the coefficient of variation of the Chl a measurements within each mesocosm providing a metric for MPB patchiness within each mesocosm. The study shows that the presence of the mobile epibenthic predator, Carcinus maenas, mediated the retention of newly fixed ( 13 C-labelled) carbon within intertidal sediments, with faunal impacts altered by changes to the ambient temperature. MPB biomass and patchiness, (proxies for assessing the productive potential of coastal sediments, Hicks et al. 2009; Kahlert & McKie 2014), were both initially affected by the introduction of Carcinus to the mesocosms. Where Carcinus were present, the sediment surface was visibly disturbed with track marks, and appeared loss cohesive in texture. Alongside this disturbance the MPB biomass increased and MPB patchiness decreased over the subsequent two weeks, suggesting that faunal reworking of the sediment had little long term effects upon the MPB. This is surprising given that faunal disturbance tends to limit the accumulation of MPB biomass or fresh algal phytodetritus at the sediment surface (Canuel et al. 2007; Spivak et al. 2007; Hicks et al. 2009; Jeffreys et al. 2011; Fanjul et al. 2015). However, benthic diatoms can switch between autotrophy at the sediment surface and heterotrophic fermentation within oxygen and light limited sub-surface sediments (Bourke et al. 2016). We postulate that faunal reworking of the sediments provides a mechanism for the transfer of active MPB cells between the sediment surface and deeper sediment layers, which allows MPB biomass to recover from the initial disturbance event. Our study builds upon observations of cascading effects of crab predation upon sediment organic matter composition in coastal sediments and provides a direct test of how faunal species loss affects sediment carbon sequestration under both present climatic conditions and predicted future-warming conditions. Our study demonstrates that both faunal presence and temperature are important regulators for organic matter retention within coastal sediments. Faunal presence was the primary driver of changes in ‘old’ organic carbon within the mesocosm, whilst strong interactions between faunal presence and temperature determine the fate of ‘recently-fixed’ organic matter. Bulk analysis of the TOC and total PLFAs was, however, limited in its scope to identify the interacting effects of Carcinus presence and temperature. Compound-specific analysis of the PLFA profiles, allowed us, to discern how faunal presence stimulated 13 C-incorporation by heterotrophic microbes under the predicted-future warming treatment, and suppressed the accumulation of microeukaryote (fungal) biomass under ambient conditions. These effects are clearly driven by changes in faunal bioturbation and the rate-limiting effects of temperature upon microbial activity.

Despite being one of the world's oldest deserts, and the subject of decades of research, evidence of past climate change in the Namib Desert is extremely limited. As such, there is significant debate regarding the nature and drivers of climate change in the low-latitude drylands of southwestern Africa. Here we present data from stratified accumulations of rock hyrax urine that provide the first continuous high-resolution terrestrial climate record for the Namib Desert spanning the past 50,000 yr. These data, spanning multiple sites, show remarkably coherent variability that is clearly linked to orbital cycles and the evolution and perturbation of global boundary conditions. Contrary to some previous predictions of southwestern African climate change, we show that orbital-scale cycles of hydroclimatic variability in the Namib Desert region are in phase with those of the northern tropics, with increased local summer insolation coinciding with periods of increased aridity. Supported by climate model simulations, our analyses link this to variations in position and intensity of atmospheric pressure cells modulated by hemispheric and land-sea temperature gradients. We conclude that hydroclimatic variability at orbital time scales is driven by the combined influence of direct low-latitude insolation forcing and the influence of remote controls on the South Atlantic anticyclone, with attendant impacts on upwelling and sea-surface temperature variations.

Few papers using hydrogen stable isotope analysis for human palaeodietary reconstruction purposes have been published and the usefulness of this additional dietary indicator is highlighted here. The hydrogen stable isotope results provide evidence for the continued exploitation of aquatic resources throughout the prehistory of the Limfjord area in Denmark, which is supported by FRUITS estimates using three (CNH) isotopic proxies. While aquatic dietary input has been identified in Mesolithic and Viking Age individuals before, our results show that, in fact, this continued throughout the periods in between (Neolithic, Bronze and Iron Age), albeit on a small scale.

Few papers using hydrogen stable isotope analysis for human palaeodietary reconstruction purposes have been published and the usefulness of this additional dietary indicator is highlighted here. The hydrogen stable isotope results provide evidence for the continued exploitation of aquatic resources throughout the prehistory of the Limfjord area in Denmark, which is supported by FRUITS estimates using three (CNH) isotopic proxies. While aquatic dietary input has been identified in Mesolithic and Viking Age individuals before, our results show that, in fact, this continued throughout the periods in between (Neolithic, Bronze and Iron Age), albeit on a small scale.

AbstractConsumption of marine protein in humans and animals can result in an apparent older radiocarbon (14C) age due to reservoir offsets. In order to correct for this, an estimate of the marine protein intake should be used to correct the 14C age for reservoir offsets, which is ordinarily done using δ13C or δ15N values. However, these two isotopic proxies can be influenced by a number of factors which can hamper estimation of the correct marine protein intake. A small dataset of 12 samples from the Limfjord, Denmark, ranging in age from Mesolithic to Viking Age, was used to test the use of δ2H values to quantify marine protein intake and determine the reservoir corrections. Each of the three stable isotopic values (δ2H, δ13C, δ15N) was used to estimate the percent marine protein intake, which produced three different calibrated 14C ages. The calculated percent marine protein intake differed between the use of the stable isotopic ratios with a maximum difference of 42.1% between the use of δ15N and δ13C, 23.8% between δ2H and δ13C, and 46.2% between δ2H and δ15N. In some cases the calculated percent marine protein intake changed the sample’s archaeological period, although there was generally still overlap in the archaeological periods for samples used in this study.

Here we used organic composition and stable isotopic analysis to evaluate the effects of drainage and restoration at an ombrotrophic peatland, to assess whether rewetting of blanket bogs will reverse degradation. The organic composition of the peat and the isotopic fractionation between the solid (peat), liquid (pore water) and gas (soil gas) phases on actively accumulating, degrading and restored locations are compared. Fourier Transform Infrared Spectroscopy (FTIR) analysis of the organic material has shown a high level of humification (low decomposition) in the active peat. Stable isotope analysis in the solid, liquid and gas phases has corresponded with this and indicated that the active location is enriched in 13C in the solid and gas phases, 15N in the solid phase, 18O in the liquid and gas phases and D in the liquid phase, suggesting a closed system with limited isotopic fractionation and thus limited water movement and decomposition. The degrading location has a lower level of humification, and is depleted in 13C in the solid phase due to ingression of vascular plants. The restored location has high humification and enrichment of 13C and 15N in the solid phase, and D in the liquid phase suggesting increased microbial activity. 13C and 18O in the gas phase and 18O in the liquid phase are depleted, as a result of microbial mediated gas production and rewetting. FTIR analysis has also indicated a subsurface zone of increased decomposition between the acrotelm and catotelm in both the active and degrading peat. This is due to a stable water table and is not present within the restored location, which we attribute to water table fluctuation associated with rewetting. This zone of increased decomposition adds to the complexity of blanket bog peatlands and the assumption that all systems can be generalized under one conceptual model.

This study represents the first stable isotope (δ13С, δ15N and δ34S) palaeodietary data and AMS radiocarbon dates for Early Bronze Age humans and fauna (n=24), and two modern fish from the Altai Mountains, Southern Siberia. The results show that the diet of the population was mainly C3-based with heavy reliance on animal protein. Within the population, males are overall higher in δ15N values which could be the result of better access to higher-trophic level foods, such as meat. Another important observation is that comparison of the results with the previous data for the Afanasyevo population from the Minusinsk Basin (Southern Siberia) suggests a difference in the amount of fish in the diet, with the Altai population virtually not using this food source. Modern fish (data from previous research) demonstrates a strong freshwater reservoir offset, although a human sample from a single archaeological terrestrial/human pair analysed does not appear to be affected. No significant offsets were detected between δ34S values of archaeological humans and herbivores, and modern fish.

A number of recent studies have highlighted the importance of freshwater reservoir effects (FRE) when dating human remains across large parts of Eurasia, including the Eurasian steppes. Here, we address this question in the context of the Early Bronze Age (Okunevo), Late Bronze Age (Karasuk) and Late Iron Age (Tashtyk culture) of the Minusinsk Basin, Southern Siberia. The issue is important given the large number of radiocarbon dates that have been published on human remains here, which have been used both to refine the cultural historical sequence (Svyatko et al. 2009 ), as well as to suggest a date of ca. 1400 bc for the appearance of millet agriculture (Svyatko et al. 2013 ). In these studies, it was argued that there was little or no freshwater reservoir effect to take into account, despite the likely consumption of freshwater fish. Subsequent work across the steppe raised a legitimate question concerning this assumption. Here, we present the first set of paired dates on late prehistoric humans and terrestrial fauna from the Minusinsk Basin, as well as data from modern fish for the region. The results, with one exception, show no clear evidence for a reservoir effect, with the human-fauna difference averaging −31 ± 95 14 C years. Yet, dating of modern fish from the Yenisei River and its tributary Karasuk River does show a variable but significant FRE. Either this effect has changed radically over time, or the contribution of fish to human diets in the Minusinsk Basin was less than previously thought.

Lower Cretaceous meandering and braided fluvial sandstones of the Nubian Formation form some of the most important subsurface reservoir rocks in the Sirt Basin, north‐central Libya. Mineralogical, petrographical and geochemical analyses of sandstone samples from well BB6–59, Sarir oilfield, indicate that the meandering fluvial sandstones are fine‐ to very fine‐grained subarkosic arenites (av. Q91F5L4), and that braided fluvial sandstones are medium‐ to very coarse‐grained quartz arenites (av. Q96F3L1). The reservoir qualities of these sandstones were modified during both eodiagenesis (ca. <70°C; <2 km) and mesodiagenesis (ca. >70°C; >2 km). Reservoir quality evolution was controlled primarily by the dissolution and kaolinitization of feldspars, micas and mud intraclasts during eodiagenesis, and by the amount and thickness of grain‐coating clays, chemical compaction and quartz overgrowths during mesodiagenesis. However, dissolution and kaolinitization of feldspars, micas and mud intraclasts resulted in the creation of intercrystalline micro‐ and mouldic macro‐porosity and permeability during eodiagenesis, which were more widespread in braided fluvial than in meandering fluvial sandstones. This was because of the greater depositional porosity and permeability in the braided fluvial sandstones which enhanced percolation of meteoric waters. The development of only limited quartz overgrowths in the braided fluvial sandstones, in which quartz grains are coated by thick illite layers, retained high porosity and permeability (12–23% and 30–600 mD). By contrast, meandering fluvial sandstones underwent porosity loss as a result of quartz overgrowth development on quartz grains which lack or have thin and incomplete grain‐coating illite (2–15% and 0–0.1 mD). Further loss of porosity in the meandering fluvial sandstones occurred as a result of chemical compaction (pressure dissolution) induced by the occurrence of micas along grains contacts. Other diagenetic alterations, such as the growth of pyrite, siderite, dolomite/ankerite and albitization, had little impact on reservoir quality. The albitization of feldspars may have had minor positive influence on reservoir quality through the creation of intercrystalline micro‐porosity between albite crystals.The results of this study show that diagenetic modifications of the braided and meandering fluvial sandstones in the Nubian Formation, and resulting changes in reservoir quality, are closely linked to depositional porosity and permeability. They are also linked to the thickness of grain‐coating infiltrated clays, and to variations in detrital composition, particularly the amounts of mud intraclasts, feldspars and mica grains as well as climatic conditions.

The uppermost 500cm sedimentary core from ODP sitelocated at the Eastern flank of Najareth bank in the Northern Indian Ocean has yielded altogether twenty four species of planktonic foraminifera. Among all these species, Globorotalia menardii has been found to be consistently dominant in the faunal assemblages from most of the samples. The δ18O measured on the tests of Globorotalia menardii from all levels help in precisely working out the sediment accumulation rates at different isotopic stages, and deciphering the change in climate in the Late Quaternary as well.

In recent years distillers dried grains and solubles (DDGS), co-products of the bio-ethanol and beverages industries, have become globally traded commodity for the animal feed sector. As such it is becoming increasingly important to be able to trace the geographical origin of commodities in case of a contamination incident or authenticity issue arise. In this study, 137 DDGS samples from a range of different geographical origins (China, USA, Canada and European Union) were collected and analyzed. Isotope ratio mass spectrometry (IRMS) was used to analyze the DDGS for 2H/1H, 13C/12C, 15N/14N, 18O/16O and 34S/32S isotope ratios which can vary depending on geographical origin and processing. Univariate and multivariate statistical techniques were employed to investigate the feasibility of using the IRMS data to determine botanical and geographical origin of the DDGS. The results indicated that this commodity could be differentiated according to their place of origin by the analysis of stable isotopes of hydrogen, carbon, nitrogen and oxygen but not with sulfur. By adding data to the models produced in this study, potentially an isotope databank could be set up for traceability procedures for DDGS, similar to the one established already for wine which will help in feed and food security issues arising worldwide.

This study aims to unravel the spatial and temporal distribution of diagenetic alterations of the Mheiherrat Member, the Rudeis Formation (lower Miocene) of the Gulf of Suez rift, Egypt within depositional fades and sequence stratigraphy. The Mheiherrat member is represented by shoreface calcarenites and hybrid arenites (transgressive and highstand systems tracts; TST and HST; respectively) and deltaic rudites and coarse-grained calcarenites and hybrid arenites (lowstand systems tracts; LST). Petrographic, stable O- and C-isotopes, mineral chemical and geochemical analyses have revealed that the arenites are pervasively cemented by eogenetic carbonates and, to small extent, by zeolite and pyrite as well as by telogenetic palygorskite. The shoreface TST and HST calcarenites and hybrid arenites were dominantly cemented by microcrystalline grain-rimming and inter- and intragranular pore-filling calcite (delta O-13(V-PDB) = -3.6 parts per thousand to -0.3 parts per thousand and delta C-13(V-PDB) = -2.3 parts per thousand to -0.7 parts per thousand) and rhombic dolomite (delta C-13(V-PDB) = -3.9 parts per thousand to +0.9 parts per thousand and delta C-13(V-PDB) = -2.5 parts per thousand to -0.7 parts per thousand). These cements are interpreted to be formed by marine to brackish waters with delta O-13(V-SMOW) -1.2 parts per thousand to +3.2 parts per thousand, at temperature of 20-55 degrees C. The deltaic LST coarse-grained calcarenites and hybrid arenites were dominantly cemented by coarse-crystalline, inter- and intragranular pore-filling calcite (delta O-13(V-PDB) -4.4 parts per thousand to -2.3% and delta C-13(V-PDB) = -2.8 parts per thousand. to -1.3 parts per thousand.), which are interpreted to have precipitated from pore waters with delta O-13(V-SWOM) +3.5 parts per thousand. to +5.5 parts per thousand, at temperatures of greater than 55 degrees C. Such pervasive cementation by carbonates is attributed to the occurrence of abundant intrabasinal carbonate grains. The carbonate cement texture is suggested to be controlled by changes in pore-water chemistry owing to transgression and regression events. This case study revealed that better understanding of factors controlling the extent and textural habits of carbonate cements can be achieved when it is linked with depositional facies and sequence stratigraphy. (C) 2013 Elsevier Ltd. All rights reserved.