Search results for "Biogeochemistry"
showing 10 items of 47 documents
Recognition of Trace Element Contamination Using Ficus macrophylla Leaves in Urban Environment
2020
Urban areas are characterized by numerous pollutants emitted by anthropic sources both in the form of solid and gaseous particulates. Biomonitoring is an easy, economical, and accessible approach for the determination of atmospheric pollutants. In this study, we used the leaves of Ficus macrophylla Desf. ex Pers., collected in the city of Palermo (Italy), to determine major and trace elements. Geogenic elements exhibited the highest concentrations, making up 99% of the weight of the analyzed elements (Ca, K, Mg, P, S, Na, Fe, and Al)
Modeling in Microbial Ecology
2014
SPE IPM; International audience; The bases and the principles of modeling in microbial community ecology and biogeochemistry are presented and discussed. Several examples are given. Among them, the fermentation process is largely developed, thus demonstrating how the model allows determining the microbial population growth rate, the death rate, and the maintenance rate. More generally, these models have been used to increase the development of bioenergetic formulations which are presently used in biogeochemical models (Monod, Droop, DEB models). Different types of interactions (competition, predation, and virus–bacteria) are also developed. For each topic, a complete view of the models used…
Electrochemical characterization of mangrove sediments: A proposal of new proxies for organic matter oxidation
2019
Abstract The voltammetric response of microparticulate deposits resulting from solvent evaporation of ethanolic extracts of mangrove sediments in contact with aqueous acetate buffer is hereby described. Dated sediment cores sampled from the Peruvian mangrove system (“Manglares de Tumbes” National Sanctuary) presented voltammetric responses dominated by oxidative signals of organic components that exhibit significant variations depending on the depth. Voltammetric data allowed for the definition of electrochemical indexes representative of the electrochemically oxidable organic matter fraction. These electrochemical indexes were fEAOM (for the total amount of organic matter being electrochem…
Origin and Diet of the Prehistoric Hunter-Gatherers on the Mediterranean Island of Favignana (Ègadi Islands, Sicily)
2012
Hunter-gatherers living in Europe during the transition from the late Pleistocene to the Holocene intensified food acquisition by broadening the range of resources exploited to include marine taxa. However, little is known on the nature of this dietary change in the Mediterranean Basin. A key area to investigate this issue is the archipelago of the Ègadi Islands, most of which were connected to Sicily until the early Holocene. The site of Grotta d'Oriente, on the present-day island of Favignana, was occupied by hunter-gatherers when Postglacial environmental changes were taking place (14,000-7,500 cal BP). Here we present the results of AMS radiocarbon dating, palaeogenetic and isotopic ana…
Evagination of Cells Controls Bio-Silica Formation and Maturation during Spicule Formation in Sponges
2011
The enzymatic-silicatein mediated formation of the skeletal elements, the spicules of siliceous sponges starts intracellularly and is completed extracellularly. With Suberites domuncula we show that the axial growth of the spicules proceeds in three phases: (I) formation of an axial canal; (II) evagination of a cell process into the axial canal, and (III) assembly of the axial filament composed of silicatein. During these phases the core part of the spicule is synthesized. Silicatein and its substrate silicate are stored in silicasomes, found both inside and outside of the cellular extension within the axial canal, as well as all around the spicule. The membranes of the silicasomes are inte…
Abundance of cellular material and proteins in the atmosphere.
2005
Suspended atmospheric particles play a crucial role in any global climate scenario: They can both enforce and suppress radiative forcing. In developing climate modeling further, a deeper understanding of atmospheric aerosol is needed. Because of extreme local and temporal variations, proper incorporation of aerosols into models requires modeling of the aerosol itself. It turns out that cellular material and proteins compose up to 25% of the atmospheric aerosol. Consequently, the source strength of the biogenic aerosol in general must be corrected and should be estimated on the order of other major aerosol sources.
Widespread Increases in Iron Concentration in European and North American Freshwaters
2017
Recent reports of increasing iron (Fe) concentrations in freshwaters are of concern, given the fundamental role of Fe in biogeochemical processes. Still, little is known about the frequency and geographical distribution of Fe trends or about the underlying drivers. We analyzed temporal trends of Fe concentrations across 340 water bodies distributed over 10 countries in northern Europe and North America in order to gain a clearer understanding of where, to what extent, and why Fe concentrations are on the rise. We found that Fe concentrations have significantly increased in 28% of sites, and decreased in 4%, with most positive trends located in northern Europe. Regions with rising Fe concent…
The role of Mediterranean wetlands in climate regulation and greenhouse gases exchanges: from carbon biogeochemistry to European water and nature Dir…
2022
Atesa la seua alta activitat biogeoquímica, els aiguamolls són un dels tipus d'ecosistemes més actius en el cicle global del carboni, amb altes taxes d'intercanvi de carboni i de gasos d'efecte hivernacle (GEH), i, per tant, un gran potencial de regulació climàtica. Una de les parts més importants de la biogeoquímica del carboni als aiguamolls està lligada a les taxes metabòliques, a partir del coneixement de les quals es pot determinar un balanç de carboni associat amb el potencial intercanvi de carboni amb l'atmosfera. La seua capacitat per retindre carboni i mitigar el canvi climàtic, o, per contra, d'alliberar més GEH, i contribuir a l'escalfament global, es determina pel balanç de carb…
Influence of biotic and abiotic factors on soil organic matter dynamics assessed by the biogeochemical characterisation of soluble organic matter
2014
Soils are the greatest reservoir of C on the continents, and organic matter mineralisation bymicrobial activity represents the major part of the CO2 emitted by terrestrial ecosystems.In this work, we studied water-extractable organic matter (WEOM), which corresponds to themore reactive fraction of soil organic matter (SOM). Our objectives were (i) to identify therelationships of WEOM dynamics with bacterial communities, and with soil physico-chemicalparameters; (ii) to provide a precise chemical characterisation of WEOM.There is a strong link between SOM solubility and the structure of bacterial communities, andan erosion of their diversity has an impact on SOM and WEOM dynamics, and leads …
Element variability in the coralline alga Lithophyllum yemenense as archive of past climate in the Gulf of Aden (NW Indian Ocean)
2017
This study presents the first algal thallus (skeleton) archive of Asian monsoon strength and Red Sea influence in the Gulf of Aden. Mg/Ca, Li/Ca, and Ba/Ca were measured in Lithophyllum yemenense from Balhaf (Gulf of Aden) using laser ablation inductively coupled plasma mass spectrometry, and Mg/Ca ratio oscillation was used to reconstruct the chronology (34 y). Oscillations of element rates corresponding to the algal growth between 1974 and 2008 were compared with recorded climate and oceanographic variability. During this period, sea surface temperatures (SST) in Balhaf recorded a warming trend of 0.55 degrees C, corresponding to an increase in Mg and Li content in the algal thallus of 2.…