Search results for "ORGANIC MATTER"
showing 10 items of 577 documents
Intra-skeletal variability in trace elemental content of Precolumbian Chupicuaro human bones: the record of post-mortem alteration and a tool for pal…
2011
14 pages; International audience; This study applies an intra-skeletal sampling strategy to examine post-mortem alteration of archaeological human bone from west Mexico, and to reconstruct ancient diet. Human bone from the Chupicuaro culture (Mexico, Preclassic period) constitutes an ideal material with which to examine subsistence strategies because the specific hydrothermal environment in which the population lived would have provided certain food components (hydrothermal waters and carbonates) with distinct signature in Ca, Mg, F, Li, Sr, Mn, V and U values. Four to ten samples were taken from the long bones of six skeletons. Bone trace element content (Ca, P, F, Mn, Mg, Na, Li, V, Zn, R…
Conjunctive use of spectral gamma-ray logs and clay mineralogy in defining late Jurassic-early Cretaceous palaeoclimate change (Dorset, U.K.).
2006
Abstract Detrital clay mineralogy is controlled by weathered source rock, climate, transport and deposition that in turn influence the spectral gamma-ray (SGR) response of resultant sediments. Whilst a palaeoclimate signal in clay mineralogy has been established in some ancient successions, the SGR response remains contentious, largely because the data sets have yet to be collected at the same or appropriate vertical scales to allow comparison. In addition, the influence of organic matter on SGR is not always considered. Here, we present clay mineralogical, total organic carbon (TOC) and SGR analyses from the late Jurassic and early Cretaceous of the Wessex Basin, a period of previously doc…
Bone diagenesis in arid environments; An intra-skeletal approach
2014
Bone trace element content and isotopic composition are closely related to human nutrition. The investigation of archaeological bone geochemistry can help us to better understand the relationship between past populations and their environment alongside cultural practices as inferred from dietary reconstruction. However, dietary in- formation may be altered post-mortem by diagenetic processes in soil. In this study, bone mineralogy (Ca/P, sec- ondary minerals, organic matter content and bone apatite crystallinity), histology, element content (Mg, Na, F, Sr, Ba, Mn, Fe, La, Ce and U) and stable isotope composition (δ13Candδ18O carbonate) were investigated at the intra- individual scale in ord…
Influence of dissolved organic matter on rare earth elements and yttrium distributions in coastal waters
2010
International audience; Data collected during this study indicate that dissolved Y and REE (rare earth element) behaviour can be monitored through shale-normalised ratios. Relationships occurring between these ratios suggest that leaching from lithogenic materials is the main source of REE in the studied area. This process involves riverine detrital matter in the inner area of the Gulf of Palermo. Features of shale-normalised patterns and the relationship recognised between dissolved Fe and Y/Ho suggest that REE are released from Fe-rich coatings of atmospheric dust. Observed similarities between dissolved Fe and chlorophyll- content suggest that leaching of Fe-rich atmospheric particulates…
Occurrence of organic-matter-rich beds in Early Cretaceous coastal evaporitic setting (Dorset, UK): a link to long-term palaeoclimate changes?
2009
11 pages; International audience; In Dorset (southern U.K.), the Durlston Bay and Lulworth Cove sections expose lowermost Cretaceous coastal marine and non-marine partly evaporitic sediments (the so-called Purbeckian facies). An interval with organic matter (OM)-rich layers is recognized in both sections. This OM-rich interval is 20 m thick in the middle of the Durlston Bay section. Within these beds, a large OM accumulation is recorded, with total organic carbon (TOC) of up to 8.5 wt%. High hydrogen index (HI) values (up to 956 mgHC/gTOC) point to a Type I OM, generally considered as derived from algal-bacterial biomass. This contrasts with the OM present in the underlying and overlying in…
Soil physicochemical and microbial drivers of temperature sensitivity of soil organic matter decomposition under boreal forests
2020
Abstract Soil organic matter (SOM) in boreal forests is an important carbon sink. The aim of this study was to assess and to detect factors controlling the temperature sensitivity of SOM decomposition. Soils were collected from Scots pine, Norway spruce, silver birch, and mixed forests (O horizon) in northern Finland, and their basal respiration rates at five different temperatures (from 4 to 28 °C) were measured. The Q10 values, showing the respiration rate changes with a 10 °C increase, were calculated using a Gaussian function and were based on temperature-dependent changes. Several soil physicochemical parameters were measured, and the functional diversity of the soil microbial communit…
Effect of Intensity and Mode of Artificial Upwelling on Particle Flux and Carbon Export
2021
Reduction of anthropogenic CO2 emissions alone will not sufficiently restrict global warming and enable the 1.5°C goal of the Paris agreement to be met. To effectively counteract climate change, measures to actively remove carbon dioxide from the atmosphere are required. Artificial upwelling has been proposed as one such carbon dioxide removal technique. By fueling primary productivity in the surface ocean with nutrient-rich deep water, it could potentially enhance downward fluxes of particulate organic carbon (POC) and carbon sequestration. In this study we investigated the effect of different intensities of artificial upwelling combined with two upwelling modes (recurring additions vs. on…
History of land-use intensity can modify the relationship between functional complexity of the soil fauna and soil ecosystem services - A microcosm s…
2012
Abstract Agricultural intensification generally results in the loss of soil organic matter, a decline in soil biodiversity, and the reduced ability of soils to retain nutrients. Intensified land-use can bring about legacy effects in soil ecosystem services that may last for hundreds of years after the cessation of agricultural practises. We studied, in a laboratory pot experiment, whether legacy effects due to intensive land/soil management (intensively managed wheat field) can be alleviated by restoring the disturbed soil with soil fauna typical of less managed soils (grassland soil). We also compared the effects of functional complexity of the soil fauna (microfauna, microfauna + mesofaun…
Net ammonification as influenced by plant diversity in experimental grasslands
2012
Abstract Previous plant diversity experiments have mainly reported positive correlations between diversity and N mineralization. We tested whether this relationship can be explained by plant diversity-induced changes i) in the quantity or quality of organic matter or ii) in microclimatic conditions of central European grassland mixtures. We measured ex-situ net ammonification in a laboratory incubation of aboveground plant material and soil sampled in differently diverse plant mixtures. Secondly, in-situ net ammonification was assessed in a field incubation with mineralization cores containing standardized material in four treatments: soil only (control), and soil mixed with field-fresh pla…
Primary production calculations for sea ice from bio-optical observations in the Baltic Sea
2016
Abstract Bio-optics is a powerful approach for estimating photosynthesis rates, but has seldom been applied to sea ice, where measuring photosynthesis is a challenge. We measured absorption coefficients of chromophoric dissolved organic matter (CDOM), algae, and non-algal particles along with solar radiation, albedo and transmittance at four sea-ice stations in the Gulf of Finland, Baltic Sea. This unique compilation of optical and biological data for Baltic Sea ice was used to build a radiative transfer model describing the light field and the light absorption by algae in 1-cm increments. The maximum quantum yields and photoadaptation of photosynthesis were determined from 14C-incorporatio…