Andreetta A.,University of Florence |
Huertas A.D.,Instituto Andaluz Of Ciencias Of La Tierra Iact Csic Ugr |
Lotti M.,University of Florence
Agriculture, Ecosystems and Environment | Year: 2016
Guinea-Bissau has the largest area of mangrove swamp rice, an important cropping system that significantly contribute to the food security of the nation. Attempts to reclaim mangrove swamps for rice growing have shown the importance of a greater knowledge on the effects of land use change on soil properties and soil carbon storage. To address this problem, a study was undertaken within Cacheur and Oio regions in Northern Guinea-Bissau, along the following chronosequence: mangrove, rice and abandoned fields. Changes in C/N ratio, δ13C and δ15N values were used to study the dynamics of C3 plant-derived and marine-derived carbon (C) in order to analyze the origin of soil organic matter (SOM) and estimate the impact of marine contribution to SOC. Isotopic signatures within the mangrove swamp rice soils suggested the inwelling of marine derived C. SOC stock was estimated in 0-10, 0-20, 0-40 and 0-80cm soil layers using fixed soil depth (FD) and fixed soil mass (FM) approaches. The significantly highest values were found in mangrove soils and the lowest in the abandoned fields for both sites, while no significant differences were recorded for the topsoil (0-10cm) between mangrove and rice fields. The results of this study revealed that conversion of mangrove to rice cropping has technical potential of SOC sequestration in the upper part of the soil (0-40cm). On the other hand, the abandonment of the fields caused decreases in carbon storage along the whole soil depth. These findings may have important implications for national forest carbon monitoring systems and regional level reducing emission from deforestation and forest degradation (REDD+) strategies. © 2015 Elsevier B.V.
Mladenov N.,University of Granada |
Mladenov N.,University of Colorado at Boulder |
Sommaruga R.,University of Innsbruck |
Morales-Baquero R.,University of Granada |
And 9 more authors.
Nature Communications | Year: 2011
Remote lakes are usually unaffected by direct human influence, yet they receive inputs of atmospheric pollutants, dust, and other aerosols, both inorganic and organic. In remote, alpine lakes, these atmospheric inputs may influence the pool of dissolved organic matter, a critical constituent for the biogeochemical functioning of aquatic ecosystems. Here, to assess this influence, we evaluate factors related to aerosol deposition, climate, catchment properties, and microbial constituents in a global dataset of 86 alpine and polar lakes. We show significant latitudinal trends in dissolved organic matter quantity and quality, and uncover new evidence that this geographic pattern is influenced by dust deposition, flux of incident ultraviolet radiation, and bacterial processing. Our results suggest that changes in land use and climate that result in increasing dust flux, ultraviolet radiation, and air temperature may act to shift the optical quality of dissolved organic matter in clear, alpine lakes. © 2011 Macmillan Publishers Limited. All rights reserved.
Velasco F.,University of the Basque Country |
Delgado A.,Instituto Andaluz Of Ciencias Of La Tierra Iact Csic Ugr |
Slack J.F.,U.S. Geological Survey |
Escobar J.M.,Cobre Las Cruces S.A.
Nature Communications | Year: 2014
Las Cruces is a base-metal deposit in the Iberian Pyrite Belt, one of the world's best-known ore provinces. Here we report the occurrence of major Pb-Ag-Au mineralization resulting from recent sub-surface replacement of supergene oxyhydroxides by carbonate and sulphide minerals. This is probably the largest documented occurrence of recent microbial activity producing an ore assemblage previously unknown in supergene mineralizing environments. The presence of microbial features in the sulphides suggests that these may be the first-described natural bacteriomorphs of galena. The low δ13C values of the carbonate minerals indicate formation by deep anaerobic microbial processes. Sulphur isotope values of sulphides are interpreted here as reflecting microbial reduction in a system impoverished in sulphate. We suggest that biogenic activity has produced around 3.1 × 109 moles of reduced sulphur and 1010 moles of CO2, promoting the formation of ca. 1.19 Mt of carbonates, 114,000 t of galena, 638 t of silver sulphides and 6.5 t of gold. © 2014 Macmillan Publishers Limited. All rights reserved.
Almaraz P.,CSIC - Doñana Biological Station |
Almaraz P.,Instituto Andaluz Of Ciencias Of La Tierra Iact Csic Ugr |
Green A.J.,CSIC - Doñana Biological Station |
Aguilera E.,CSIC - Doñana Biological Station |
And 2 more authors.
Journal of Animal Ecology | Year: 2012
Understanding the impact of environmental variability on migrating species requires the estimation of sequential abiotic effects in different geographic areas across the life cycle. For instance, waterfowl (ducks, geese and swans) usually breed widely dispersed throughout their breeding range and gather in large numbers in their wintering headquarters, but there is a lack of knowledge on the effects of the sequential environmental conditions experienced by migrating birds on the long-term community dynamics at their wintering sites. Here, we analyse multidecadal time-series data of 10 waterfowl species wintering in the Guadalquivir Marshes (SW Spain), the single most important wintering site for waterfowl breeding in Europe. We use a multivariate state-space approach to estimate the effects of biotic interactions, local environmental forcing during winter and large-scale climate during breeding and migration on wintering multispecies abundance fluctuations, while accounting for partial observability (observation error and missing data) in both population and environmental data. The joint effect of local weather and large-scale climate explained 31·6% of variance at the community level, while the variability explained by interspecific interactions was negligible (<5%). In general, abiotic conditions during winter prevailed over conditions experienced during breeding and migration. Across species, a pervasive and coherent nonlinear signal of environmental variability on population dynamics suggests weaker forcing at extreme values of abiotic variables. Modelling missing observations through data augmentation increased the estimated magnitude of environmental forcing by an average 30·1% and reduced the impact of stochasticity by 39·3% when accounting for observation error. Interestingly however, the impact of environmental forcing on community dynamics was underestimated by an average 15·3% and environmental stochasticity overestimated by 14·1% when ignoring both observation error and data augmentation. These results provide a salient example of sequential multiscale environmental forcing in a major migratory bird community, which suggests a demographic link between the breeding and wintering grounds operating through nonlinear environmental effects. Remarkably, this study highlights that modelling observation error in the environmental covariates of an ecological model can be proportionally more important than modelling this source of variance in the population data. © 2012 The Authors. Journal of Animal Ecology © 2012 British Ecological Society.
Pena A.,Instituto Andaluz Of Ciencias Of La Tierra Iact Csic Ugr |
Rodriguez-Liebana J.A.,Instituto Andaluz Of Ciencias Of La Tierra Iact Csic Ugr |
Mingorance M.D.,Instituto Andaluz Of Ciencias Of La Tierra Iact Csic Ugr
Chemosphere | Year: 2011
Wastewater treatment plants receive organic contaminants, such as pesticides, which reach the sewage system from domestic, industrial or agricultural activities. In wastewater, which is a complex mixture of organic and inorganic compounds, biotic or abiotic degradation of contaminants can be affected by the presence of co-solutes. The photodecomposition in natural sunlight of two neonicotinoid insecticides, thiamethoxam and thiacloprid, was investigated in wastewater, aqueous extracts of sewage sludge and in aqueous surfactant solutions, which are abundant in wastewater. Dissipation in the dark was also studied in wastewater, due to reduction of transmitted sunlight in wastewater ponds. With regard to photolysis, thiamethoxam degraded rapidly in all the aqueous solutions. Among them sewage sludge extracts slightly modified (average half-life 17.6. h), wastewater increased (13.7. h) and non-ionic surfactants led, as a family, to the highest dissipation rates (average 6.2. h), with respect to control water (18.7. h). Additionally this pesticide also underwent a slower biodegradation process in wastewater in the dark under anaerobic conditions (around 25. d). A metabolite of thiamethoxam from the biological decomposition in wastewater was identified by HPLC/MS. On the other hand thiacloprid was found to be resistant to photo- and biodecomposition and remained almost unchanged during the experimental periods in all the tested media. © 2011 Elsevier Ltd.
Moleon M.,University of Witwatersrand |
Almaraz P.,Instituto Andaluz Of Ciencias Of La Tierra Iact Csic Ugr |
Sanchez-Zapata J.A.,University Miguel Hernández
European Journal of Wildlife Research | Year: 2013
In a previous study, we suggested that hyperpredation by shared predators on red-legged partridges (Alectoris rufa), once a parasite (rabbit haemorrhagic disease, RHD) had decimated populations of rabbit (Oryctolagus cuniculus), the primary prey for most of the Mediterranean predators, was a major force driving partridge population dynamics in Spain years ago (Moleón et al., PLoS One 3:e2307, 2008). Recently, however, Blanco-Aguiar et al. (Eur J Wildl Res 58:433-439, 2012) have asserted that this conclusion is poorly evidence-based and can subsequently promote raptor persecution by hunters. In response to Blanco-Aguiar and colleagues, here we provide complementary insights that favour our earlier hypothesis. After explaining several key concepts of the hyperpredation process, we use additional data and analyses to show that (1) a synchronised regime shift (i.e. a step, abrupt change in population size) to significantly lower population levels in both the rabbit and partridge populations took place coinciding with the RHD outbreak; (2) rabbit and partridge population dynamics were highly synchronised after the RHD outbreak, but not before; (3) an enhanced spatial autocorrelation at all the spatial scales emerged after RHD for partridge populations; and (4) the main shared predators' diet patterns were consistent with the hypothesis of enhanced predation pressure as a plausible mechanism behind the observed partridge dynamics. We support the idea that hunting bag data may be useful to infer realistic population dynamics and the ecological mechanisms explaining them, provided that (1) they are corrected by the number of hunting licenses; (2) appropriate statistical tools are employed; and (3) methodological constraints are adequately taken into account. Finally, we argue that the opinion of Blanco-Aguiar and colleagues that our original results can lead to raptor persecution is a misinterpretation of our study. In this sense, we make an appeal for the importance of accurately differentiating between the ultimate (e.g. infectious diseases favoured by humans) and the proximate (e.g. enhanced predation pressure) causes of the decline in prey of economic interest (e.g. game species) in order to avoid unnecessary, unfounded or presumed conflicts with lobbies of conservation concern (e.g. hunters). © 2013 Springer-Verlag Berlin Heidelberg.
Diaz-Hernandez J.L.,IFAPA Camino de Purchil |
Sanchez-Navas A.,University of Granada |
Sanchez-Navas A.,Instituto Andaluz Of Ciencias Of La Tierra Iact Csic Ugr |
Reyes E.,Instituto Andaluz Of Ciencias Of La Tierra Iact Csic Ugr
Chemical Geology | Year: 2013
Dolomite formation in soils constitute a particular challenge because of: 1) scant magnesium content in continental environments as opposed to the marine medium, 2) the kinetic problem related to the incorporation of magnesium into the carbonate, and 3) the unknown role of soil dolomites in the global carbon cycle. Pedogenic dolomite formed at deeper soil levels (subsoil) before the development of petrocalcic horizon barriers was investigated in a semiarid region of SE Spain (Guadix-Baza basin). Mineralogical characterization, textural relationships and isotopic data concerning soil dolomite, together with the results of a precipitation experiment, provided fuller knowledge of the processes and conditions governing neoformation of dolomite in these soils. In the study case, dolomite enrichment occurs beyond the limit of major biological activity, which coincides with the rooting depth of native perennial plants in the semiarid soils studied. Textural studies reveal the corrosion of inherited dolomite crystals in the upper soil horizons and the formation of dolomite in depth in relation to a clayey material, composed mainly of smectites. Stable isotope distribution in dolomites throughout the profiles indicates a fractionation with depth. This is explained by the formation of dolomites after the dissolution of the pedogenic calcite. The calcite detected in the subsoil is interpreted here as a precursor of the neoformed dolomites that transport the isotopic signal associated with biological activity of soils to deeper layers. Dolomite formation appears to be favoured by the presence of clay minerals in the precipitation media. Clays retain water during evapotranspiration stages, which drastically change the transport properties of the media and promote the incorporation of Mg into the structure of the neoformed Ca,Mg-carbonate. As confirmed by laboratory experiments, diffusion-controlled crystal-growth processes lead to the formation a precursory "protodolomite" with disordered Ca,Mg distribution from a fluid locally supersaturated in dolomite. © 2013 Elsevier B.V.
Cardenas-Parraga J.,University of Granada |
Garcia-Casco A.,University of Granada |
Garcia-Casco A.,Instituto Andaluz Of Ciencias Of La Tierra Iact Csic Ugr |
Harlow G.E.,American Museum of Natural History |
And 3 more authors.
European Journal of Mineralogy | Year: 2012
Jadeitite (jadeite jade) from Sierra del Convento (eastern Cuba) occurs in a subduction-related serpentinite-matrix mélange associated with a variety of high-pressure tectonic blocks including garnet-amphibolites and related anatectic trondhjemites. The eastern Cuban jadeitite is massive and characterized by rare quartz inclusions and omphacite exsolution in jadeite crystals, as well as replacement or infilling by omphacite. Minor minerals include epidote, biotite, albite, phengite, titanite, rutile, zircon, and apatite. Oscillatory zoning in jadeite crystals and zircon ages suggest hydrothermal crystallization in veins formed in serpentinized peridotite, probably of the mantle wedge. Al-Na-Mg-Ca-bearing fluids of variable composition but high pH (capable of mobilizing Zr and Hf at SiO2-subsaturated conditions) deposited jadeitite in veins during episodic opening of the fractures at depth in the subduction environment. Late-stage crystallizations include omphacite, albite and epidote from fluids nearly saturated in SiO 2. The compositional gap of two coexisting pyroxenes indicates a temperature of jadeite formation higher than 500 °C. Zircon Pb/U ages of 107.4 ± 0.5 Ma and 107.8 ±1.1 Ma attest formation during the earliest stages of subduction in the region. These ages and the high temperature of formation of jadeitite suggest a genetic link between the jadeite-forming fluids and fluids derived from associated anatectic trondhjemites crystallized at depth (15 kbar). © 2012 E. Schweizerbart'sche Verlagsbuchhandlung.
Capaccioni B.,University of Bologna |
Menichetti M.,Urbino University |
Renzulli A.,Urbino University |
Tassone A.,University of Buenos Aires |
Huertas A.D.,Instituto Andaluz Of Ciencias Of La Tierra Iact Csic Ugr
Geofluids | Year: 2013
The geothermal area of Rio Valdez is located in the central portion of the Isla Grande de Tierra del Fuego (South Argentina), ten kilometers south of the southeastern sector of the Fagnano Lake. It consists of a series of thermal springs with low discharge rates (≤1L/s) and temperatures in the range of 20-33°C distributed in an area of <1km2. The thermal springs are characterized by alkaline, Na-HCO3 waters with low salinity (0.53÷0.58g/L), but relatively high fluoride contents (up to 19.4mg/L). Their composition is the result of a slow circulation at depth, possibly through deep tectonic discontinuities connected with the Magallanes-Fagnano Fault (MFF) system. According to geothermometric calculations, thermal waters reach temperatures in the range of 100-150°C and an almost complete chemical equilibrium with the alkali-feldspars in the metavolcanic country rocks. The relatively high fluorine contents can be explained by the slow ascent and cooling of deep groundwaters followed by a progressive re-equilibration with F-bearing, hydrated Mg-silicates, such as chlorite, which has been recognized as an abundant mineral in the metavolcanics of the Lemaire Formation and metapelites and metagraywackes of the Yahgán Formation. Finally, the isotopic composition of the investigated samples is consistent with the infiltration from local snow melting at altitudes in the range of 610-770m asl. The comparison of our data with those collected in 1991 seems to suggest a possible progressive decline of the bulk thermal output in the near future. This possibility should be seriously considered before planning a potentially onerous exploitation of the resource. Presently, the only ways to exploit this geothermal resource by the population scattered in the area are the direct use of thermal waters and/or spa structures. © 2012 Blackwell Publishing Ltd.
Fairhurst G.D.,University of Saskatchewan |
Vogeli M.,University of Saskatchewan |
Vogeli M.,CSIC - Doñana Biological Station |
Serrano D.,CSIC - Doñana Biological Station |
And 3 more authors.
Oecologia | Year: 2013
Physiological mechanisms link the environment with population dynamics, and glucocorticoid hormones are of particular interest because they respond adaptively to environmental change and can influence vertebrate reproduction and fitness. We tested a novel approach of synchronizing feather-based measures of corticosterone (the primary avian glucocorticoid; CORTf) and ratios of stable isotopes (SIs) of C (δ13C) and N (δ15N) to provide information about environmental conditions and an integrated physiological response to those conditions over the same period of feather synthesis. Using a fragmented metapopulation of Dupont's larks Chersophilus duponti, an endangered steppe songbird, we analyzed interrelationships among CORTf, δ13C, δ15N, and the physical environment, including measures of habitat loss and fragmentation. CORTf was not related to any habitat variable measured directly. However, we detected a significant spatial structure to CORTf values and food availability, with greater similarity in both at smaller spatial scales. Using SIs as proxies for the local environment, we found CORTf was negatively related to δ13C. Values of CORTf, δ13C, and the relationship between the two were likely driven by variation in agricultural land use surrounding lark habitat patches. Our feather-based approach revealed that individual physiology was sensitive to environmental conditions (e.g., an interaction of food availability and variation in habitat) at a local scale, but not patch or landscape scales. Combining CORTf and SIs may be a promising tool because it can provide individual-based information about habitat, physiology, and their relationship during the same time period. © 2013 Springer-Verlag Berlin Heidelberg.