Sex differences in diet and life conditions in a rural Medieval Islamic population from Spain (La Torrecilla, Granada): An isotopic and osteological approach to gender differentiation in al-Andalus.

OBJECTIVES: Gender differentiation can influence the diet, physical activity, and health of human populations. Multifaceted approaches are therefore necessary when exploring the biological consequences of gender-related social norms in the past. Here, we explore the links between diet, physiological stress, physical activity, and gender differentiation in the Medieval Islamic population of La Torrecilla (Granada, Spain, 13th-15th century AD), by analyzing stable isotope patterns, stature, and long bone diaphyseal measurements. MATERIALS AND METHODS: The sample includes 96 individuals (48 females, 48 males) classified as young and middle adults (20-34 and 35-50 years of age respectively). Diet was reconstructed through the analysis of δ13 C and δ15 N. Stature, humeral and femoral diaphyseal shape and product of diaphyseal diameters served as proxies of physiological stress and physical activity. RESULTS: Isotopic ratios suggest a substantial dietary contribution of C4 plants (e.g., sorghum, millet), a variable access to animal proteins, and no differences between the sexes. Sexual dimorphism in stature derives from a markedly low female stature. Long bone diaphyseal properties suggest that men performed various physically stressful activities, whereas women were involved in less physically demanding activities (possibly related to household work). DISCUSSION: Gender differentiation in La Torrecilla was expressed by a possibly differential parental investment in male versus female offspring and by culturally sanctioned gender differences in the performance of physical tasks. Diet was qualitatively homogenous between the sexes, although we cannot rule out quantitative differences. Our results shed new light on the effects of gender-related social norms on human development and lifestyle.

Isotopic enrichment in Rhizoprionodon porosus (Poey, 1861) and Carcharhinus porosus (Ranzani, 1840) embryos.

Isotopic values of two Caribbean sharpnose shark Rhizoprionodon porosus litters (Poey, 1861) with two and three embryos and one litter of 11 smalltail shark Carcharhinus porosus embryos showed enriched 15 N and 13 C compared to their mothers. In R. porosus, embryonic isotope values were 3.06 ± 0.07‰ and 0.69 ± 0.15‰ greater than their mothers' for δ15 N and δ13 C, respectively, whereas in C. porosus, δ15 N and δ13 C were 1.79 ± 0.09‰ and 1.31 ± 0.17‰ greater in embryos than their mothers.

Interlaboratory test for stable carbon isotope analysis of dissolved inorganic carbon in geothermal fluids.

RATIONALE: Stable carbon isotope ratios have many applications in natural sciences. In the first worldwide interlaboratory proficiency test, the discrepancies in measured δ13 CDIC values of natural waters were up to σ = ±3‰. Therefore, we continued the investigation on the analytical data quality assurance of individual laboratories and internal consistency among laboratories worldwide. METHODS: We designed and performed an interlaboratory comparison exercise for δ13 C analyses of ten water and two solid samples (Na2 CO3 , CaCO3 ), including two synthetic samples prepared by dissolving the carbonates individually. Three laboratories analyzed an additional sample set to assess solution stability, at least one month after the first set analysis period. The δ13 C values were measured using dual inlet isotope ratio mass spectrometry (DI-IRMS) or continuous flow (CF)-IRMS. RESULTS: The δ13 C values of solid Na2 CO3 and its aqueous solution were -5.06 ± 0.21‰ and 5.32 ± 0.24‰, respectively, while the δ13 C value of solid CaCO3 was -4.49 ± 0.93‰. Similarly, the lake water has a consistent value (2.45 ± 0.19‰). The δ13 C values of geothermal water have a wide dispersion among individual laboratory measurements and among those of different laboratories; however, a trend exists in the δ13 C values measured at the three sampling points of each well. CONCLUSIONS: The δ13 C values of solid Na2 CO3 and its solution, and lake water (i.e. DIC concentration samples >100 mg/L carbon) are consistent among all the participating laboratories. The dispersion in the δ13 C values of solid CaCO3 is associated with its lower chemical affinity than that of Na2 CO3 . The poor reproducibility in the δ13 C values of geothermal fluids, collected at three points of a geothermal well, despite overall consistent trends regarding their collection points suggests inadequate sample handling (atmospheric CO2 exchange) and/or inappropriate analytical approaches (incomplete H3 PO4 acid reaction).

Stable-isotope analysis reveals sources of organic matter and ontogenic feeding shifts of a mangrove-dependent predator species, New Granada sea catfish, Ariopsis canteri.

To gain a better understanding on the trophic ecology of New Granada sea catfish, Ariopsis canteri, and their linkage to mangroves, nitrogen and stable carbon isotopes (δ15 N and δ13 C), as well as Bayesian mixing models, were used to explore trophic dynamics and potential ontogenic feeding shifts across different size classes: class I (8-20 cm), class II (21-32 cm) and class III (>32 cm). The study area was the estuary of the Atrato River Delta, where information about fish ecology is scarce. The δ13 C of size class I was lower (mean ± s.d. = -24.96 ± 0.69‰) than that of size classes II (-22.20 ± 0.90‰) and III (-22.00 ± 1.96‰). The δ15 N of size class I was lower (mean ± s.d. = 8.50 ± 0.67‰) than that of size classes II (9.77 ± 0.60‰) and III (10.00 ± 0.66‰). Body size was positively and significantly correlated to δ15 N and δ13 C. Individuals with LT > 32 cm presented the highest estimated trophic position (3.8). Five-source mixing models indicated that for class I, the mean estimated contribution of macroalgae was the highest (6%-57% c.i.), and for classes II and III, the mean estimated contribution of macrophytes was the highest (3%-53% c.i. and 4%-53% c.i., respectively). Ontogenetic feeding shifts of A. canteri were confirmed evidencing decreasing intraspecific competition between small and large individuals. Results suggest that mangroves are a nursery and feeding ground habitat for this species and that mangroves support A. canteri mainly due to the substrate/habitat that supports sources in the food webs. These results can be used in ecosystem-based fishery management focused on the protection of extensive mangrove areas in the southern Caribbean Sea.

Photosynthetic use of inorganic carbon in deep-water kelps from the Strait of Gibraltar.

Mechanisms of inorganic carbon assimilation were investigated in the four deep-water kelps inhabiting sea bottoms at the Strait of Gibraltar; these species are distributed at different depths (Saccorhiza polysiches at shallower waters, followed by Laminaria ochroleuca, then Phyllariopsis brevipes and, at the deepest bottoms, Phyllariopsis purpurascens). To elucidate the capacity to use HCO3(-) as a source of inorganic carbon for photosynthesis in the kelps, different experimental approaches were used. Specifically, we measured the irradiance-saturated gross photosynthetic rate versus pH at a constant dissolved inorganic carbon (DIC) concentration of 2 mM, the irradiance-saturated apparent photosynthesis (APS) rate versus DIC, the total and the extracellular carbonic anhydrase (CAext), the observed and the theoretical photosynthetic rates supported by the spontaneous dehydration of HCO3(-) to CO2, and the δ(13)C signature in tissues of the algae. While S. polyschides and L. ochroleuca showed photosynthetic activity at pH 9.5 (around 1.0 µmol O2 m(-2) s(-1)), the activity was close to zero in both species of Phyllariopsis. The APS versus DIC was almost saturated for the DIC values of natural seawater (2 mM) in S. polyschides and L. ochroleuca, but the relationship was linear in P. brevipes and P. purpurascens. The four species showed total and CAext activities but the inhibition of the CAext originated the observed photosynthetic rates at pH 8.0 to be similar to the theoretical rates that could be supported by the spontaneous dehydration of HCO3(-). The isotopic (13)C signatures ranged from -17.40 ± 1.81 to -21.11 ± 1.73 ‰ in the four species. Additionally, the δ(13)C signature was also measured in the deep-water Laminaria rodriguezii growing at 60-80 m, showing even a more negative value of -26.49 ± 1.25 ‰. All these results suggest that the four kelps can use HCO3(-) as external carbon source for photosynthesis mainly by the action of external CAext, but they also suggest that the species inhabiting shallower waters show a higher capacity than the smaller kelps living in deeper waters. In fact, the photosynthesis in the two Phyllariopsis species could be accomplished by the spontaneous dehydration of HCO3(-) to CO2. These differences in the capacity to use HCO3(-) in photosynthesis among species could be important considering the increasing levels of atmospheric CO2 predicted for the near future.

Hydrodynamics and water quality of a highly anthropized wetland: the case study of the Massaciuccoli basin (Tuscany, Italy).

Owing to increasing anthropogenic impacts, wetlands have suffered a serious environmental decline in recent decades. The sustainable management of these natural resources is fundamental to maintain both the ecosystems and the economic activities. The Lake Massaciuccoli and nearby areas represent one of the largest residual coastal marshy areas in Tuscany (Italy). This wetland is characterized by large-scale and intensive agricultural use and affected by reclamation activities, with consequent problems of erosion, subsidence and lake eutrophication and siltation. In this context, an integrated study combining hydrochemical data (water levels, electrical conductivity, pH, turbidity, major ions, trace metals) and stable isotopes (H, O, S) has been performed in the southernmost part of the basin, to better disentangle processes and interactions between groundwater and surface water and to understand the origin of solutes and their evolution. Our results indicated that both groundwater and surface water have a meteoric origin and that geochemical composition of groundwater is mainly affected by local geological and biological processes. Moreover, surface water is affected by sea water mixing and evapotranspiration/precipitation processes. The impact of agricultural activity and the use of fertilizers on the water quality appears to be limited as regards nitrates, indicating that less intense agricultural practices implemented in recent years have been successful. As regards sulfates, Fe, and Mn, we cannot fully elucidate the mechanisms underlying human influence, but the oscillation of water level and degradation of peat enhanced by reclamation and agriculture activities likely played an important role in controlling the fate of these elements. Overall, these results underline the importance of integrated approaches to disentangle geochemical processes and will be useful in supporting policy implementation and environmental protection in this valuable area of Tuscany. Findings from this work suggest the need for policy-making authorities to take actions as soon as possible to mitigate risks. Closer co-operation is essential between authorities and farmers to reduce inputs of fertilizers and chemicals into the lake and the surrounding area. Also, additional policy measures should be enforced to reduce the mechanical soil tillage and limit erosion and runoff, such as the NBSs implemented within the Phusicos Project.

Stable carbon isotope analysis of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) in natural waters--results from a worldwide proficiency test.

RATIONALE: Stable carbon isotope ratios of dissolved inorganic (DIC) and organic carbon (DOC) are of particular interest in aquatic geochemistry. The precision for this type of analysis is typically reported in the range of 0.1‰ to 0.5‰. However, there is no published attempt that compares δ(13)C measurements of DIC and DOC among different laboratories for natural water samples. METHODS: Five natural water samples (lake water, seawater, two geothermal waters, and petroleum well water) were analyzed for δ(13)CDIC and δ(13)CDOC values by five laboratories with isotope ratio mass spectrometry (IRMS) in an international proficiency test. RESULTS: The reported δ(13)CDIC values for lake water and seawater showed fairly good agreement within a range of about 1‰, whereas geothermal and petroleum waters were characterized by much larger differences (up to 6.6‰ between laboratories). δ(13)CDOC values were only comparable for seawater and showed differences of 10 to 21‰ for other samples. CONCLUSIONS: This study indicates that scatter in δ(13)CDIC isotope data can be in the range of several per mil for samples from extreme environments (geothermal waters) and may not yield reliable information with respect to dissolved carbon (petroleum wells). The analyses of lake water and seawater also revealed a larger than expected difference and researchers from various disciplines should be aware of this. Evaluation of analytical procedures of the participating laboratories indicated that the differences cannot be explained by analytical errors or different data normalization procedures and must be related to specific sample characteristics or secondary effects during sample storage and handling. Our results reveal the need for further research on sources of error and on method standardization.

Growth and stable isotope signals associated with drought-related mortality in saplings of two coexisting pine species.

Drought-induced events of massive tree mortality appear to be increasing worldwide. Species-specific vulnerability to drought mortality may alter patterns of species diversity and affect future forest composition. We have explored the consequences of the extreme drought of 2005, which caused high sapling mortality (approx. 50 %) among 10-year-old saplings of two coexisting pine species in the Mediterranean mountains of Sierra Nevada (Spain): boreo-alpine Pinus sylvestris and Mediterranean P. nigra. Sapling height growth, leaf δ(13)C and δ(18)O, and foliar nitrogen concentration in the four most recent leaf cohorts were measured in dead and surviving saplings. The foliar isotopic composition of dead saplings (which reflects time-integrated leaf gas-exchange until mortality) displayed sharp increases in both δ(13)C and δ(18)O during the extreme drought of 2005, suggesting an important role of stomatal conductance (g(s)) reduction and diffusional limitations to photosynthesis in mortality. While P. nigra showed decreased growth in 2005 compared to the previous wetter year, P. sylvestris maintained similar growth levels in both years. Decreased growth, coupled with a sharper increase in foliar δ(18)O during extreme drought in dead saplings, indicate a more conservative water use strategy for P. nigra. The different physiological behavior of the two pine species in response to drought (further supported by data from surviving saplings) may have influenced 2005 mortality rates, which contributed to 2.4-fold greater survival for P. nigra over the lifespan of the saplings. This species-specific vulnerability to extreme drought could lead to changes in dominance and distribution of pine species in Mediterranean mountain forests.

Trophic inferences of blue shark (Prionace glauca) in the Mexican Pacific from stable isotope analysis in teeth.

RATIONALE: Isotopic analysis of biogenic tissues such as teeth of elasmobranchs has been well recognized as an important method to interpret present and past environmental conditions. However, few studies on shark teeth have focused their attention on making trophic inferences or reconstruction of diet. METHODS: We analyzed the carbon (δ(13)C) and nitrogen (δ(15)N) isotope composition of the tooth crown and root from blue sharks Prionace glauca caught in southern Baja California using a continuous-flow system by means of an elemental analyzer combined with a Delta Plus XL mass spectrometer, to describe their feeding ecology, considering sex and maturity stage. RESULTS: Significant differences in δ(13)C values for tooth root were found between immature and mature males, with depleted values of (13)C in immature individuals. No statistical differences were found between maturity stages in females for both the C and N isotopes in any part of the tooth, which suggests that females were consuming the same prey in the same area. In addition, we observed significant differences in δ(15)N values between the tooth crown and root. CONCLUSIONS: Isotopic analysis in the tooth crown (dentin) and root may represent a new tool to describe the feeding ecology of different species of elasmobranchs, showing dietary change over a short timescale.

How to stay together? Habitat use by three sympatric sharks in the western coast of Baja California Sur, Mexico.

Sharks are top predators and play an important role in the regulation of marine ecosystems at lower trophic position. Mustelus californicus, Sphyrna zygaena, and Isurus oxyrinchus prove to be important fishery resources along the western coast of Baja California Sur and cohabit the same coastal areas, probably sharing resources. However, our knowledge about ecological dynamics of multiple species coexisting and sharing similar habitat resources is still limited, particularly for predators such as sharks. Therefore, this study focuses on the analysis of trophic ecology of the sharks species, using carbon (13C) and nitrogen (15N) stable isotope values in muscle tissues coupled with trace element concentration (Hg, Se, and Cd) in muscle and hepatic tissues of sharks. The values of δ13C (M. californicus -17.3 ± 1.1‰, S. zygaena -17.9 ± 0.5‰, and I. oxyrinchus -18.3 ± 0.3‰) and δ15N (M. californicus 18.2 ± 1.1‰, S. zygaena 18.4 ± 0.9‰, and I. oxyrinchus 17.8 ± 1.1‰) indicated that these species feed in the Gulf of Ulloa all throughout the year, and for extended periods with similar habitat use and trophic niche. The above-mentioned statement is also a conclusion supported by the significant correlation between isotopic and trace element concentrations in the muscular tissues in all studied species. Thus, the results of the present study emphasize the habitat and niche characteristics of three sympatric sharks off the coast of Baja California Sur, Mexico.

Fine-scale metabolic discontinuity in a stratified prokaryote microbiome of a Red Sea deep halocline.

Deep-sea hypersaline anoxic basins are polyextreme environments in the ocean's interior characterized by the high density of brines that prevents mixing with the overlaying seawater, generating sharp chemoclines and redoxclines up to tens of meters thick that host a high concentration of microbial communities. Yet, a fundamental understanding of how such pycnoclines shape microbial life and the associated biogeochemical processes at a fine scale, remains elusive. Here, we applied high-precision sampling of the brine-seawater transition interface in the Suakin Deep, located at 2770 m in the central Red Sea, to reveal previously undocumented fine-scale community structuring and succession of metabolic groups along a salinity gradient only 1 m thick. Metagenomic profiling at a 10-cm-scale resolution highlighted spatial organization of key metabolic pathways and corresponding microbial functional units, emphasizing the prominent role and significance of salinity and oxygen in shaping their ecology. Nitrogen cycling processes are especially affected by the redoxcline with ammonia oxidation processes being taxa and layers specific, highlighting also the presence of novel microorganisms, such as novel Thaumarchaeota and anammox, adapted to the changing conditions of the chemocline. The findings render the transition zone as a critical niche for nitrogen cycling, with complementary metabolic networks, in turn underscoring the biogeochemical complexity of deep-sea brines.

Elucidating the Possible Involvement of Maize Aquaporins and Arbuscular Mycorrhizal Symbiosis in the Plant Ammonium and Urea Transport under Drought Stress Conditions.

This study investigates the possible involvement of maize aquaporins which are regulated by arbuscular mycorrhizae (AM) in the transport in planta of ammonium and/or urea under well-watered and drought stress conditions. The study also aims to better understand the implication of the AM symbiosis in the uptake of urea and ammonium and its effect on plant physiology and performance under drought stress conditions. AM and non-AM maize plants were cultivated under three levels of urea or ammonium fertilization (0, 3 µM or 10 mM) and subjected or not to drought stress. Plant aquaporins and physiological responses to these treatments were analyzed. AM increased plant biomass in absence of N fertilization or under low urea/ ammonium fertilization, but no effect of the AM symbiosis was observed under high N supply. This effect was associated with reduced oxidative damage to lipids and increased N accumulation in plant tissues. High N fertilization with either ammonium or urea enhanced net photosynthesis (AN) and stomatal conductance (gs) in plants maintained under well-watered conditions, but 14 days after drought stress imposition these parameters declined in AM plants fertilized with high N doses. The aquaporin ZmTIP1;1 was up-regulated by both urea and ammonium and could be transporting these two N forms in planta. The differential regulation of ZmTIP4;1 and ZmPIP2;4 with urea fertilization and of ZmPIP2;4 with NH4+ supply suggests that these two aquaporins may also play a role in N mobilization in planta. At the same time, these aquaporins were also differentially regulated by the AM symbiosis, suggesting a possible role in the AM-mediated plant N homeostasis that deserves future studies.

Discovery of Afifi, the shallowest and southernmost brine pool reported in the Red Sea.

The previously uncharted Afifi brine pool was discovered in the eastern shelf of the southern Red Sea. It is the shallowest brine basin yet reported in the Red Sea (depth range: 353.0 to 400.5 m). It presents a highly saline (228 g/L), thalassohaline, cold (23.3 °C), anoxic brine, inhabited by the bacterial classes KB1, Bacteroidia and Clostridia and the archaeal classes Methanobacteria and Deep Sea Euryarcheota Group. Functional assignments deduced from the taxonomy indicate methanogenesis and sulfur respiration to be important metabolic processes in this environment. The Afifi brine was remarkably enriched in dissolved inorganic carbon due to microbial respiration and in dissolved nitrogen, derived from anammox processes and denitrification, according to high δ15N values (+6.88‰, AIR). The Afifi brine show a linear increase in δ18O and δD relative to seawater that differs from the others Red Sea brine pools, indicating a non-hydrothermal origin, compatible with enrichment in evaporitic environments. Afifi brine was probably formed by venting of fossil connate waters from the evaporitic sediments beneath the seafloor, with a possible contribution from the dehydration of gypsum to anhydrite. Such origin is unique among the known Red Sea brine pools.

Competition and drought limit the response of water-use efficiency to rising atmospheric carbon dioxide in the Mediterranean fir Abies pinsapo.

The gas-exchange and radial growth responses of conifer forests to climatic warming and increasing atmospheric CO2 have been widely studied. However, the modulating effects of variables related to stand structure (e.g., tree-to-tree competition) on those responses are poorly explored. The basal-area increment (BAI) and C isotope discrimination (C stable isotope ratio; delta13C) in the Mediterranean fir Abies pinsapo were investigated to elucidate the influences of stand competition, atmospheric CO2 concentrations and climate on intrinsic water-use efficiency (WUEi). We assessed the variation in delta13C of tree-rings from dominant or co-dominant trees subjected to different degrees of competition. A high- (H) and a low-elevation (L) population with contrasting climatic constraints were studied in southern Spain. Both populations showed an increase in long-term WUEi. However, this increase occurred more slowly at the L site, where a decline of BAI was also observed. Local warming and severe droughts have occurred in the study area over the past 30 years, which have reduced water availability more at lower elevations. Contrastingly, trees from the H site were able to maintain high BAI values at a lower cost in terms of water consumption. In each population, trees subjected to a higher degree of competition by neighboring trees showed lower BAI and WUEi than those subjected to less competition, although the slopes of the temporal trends in WUEi were independent of the competitive micro-environment experienced by the trees. The results are consistent with an increasing drought-induced limitation of BAI and a decreasing rate of WUEi improvement in low-elevation A. pinsapo forests. This relict species might not be able to mitigate the negative effects of a decrease in water availability through a reduction in stomatal conductance, thus leading to a growth decline in the more xeric sites. An intense and poorly asymmetric competitive environment at the stand level may also act as an important constraint on the adaptive capacity of these drought-sensitive forests to climatic warming.

A Polyextreme Hydrothermal System Controlled by Iron: The Case of Dallol at the Afar Triangle.

One of the latest volcanic features of the Erta Ale range at the Afar Triangle (NE Ethiopia) has created a polyextreme hydrothermal system located at the Danakil depression on top of a protovolcano known as the dome of Dallol. The interaction of the underlying basaltic magma with the evaporitic salts of the Danakil depression has generated a unique, high-temperature (108 °C), hypersaline (NaCl supersaturated), hyperacidic (pH values from 0.1 to -1.7), oxygen-free hydrothermal site containing up to 150 g/L of iron. We find that the colorful brine pools and mineral patterns of Dallol derive from the slow oxygen diffusion and progressive oxidation of the dissolved ferrous iron, the iron-chlorine/-sulfate complexation, and the evaporation. These inorganic processes induce the precipitation of nanoscale jarosite-group minerals and iron(III)-oxyhydroxides over a vast deposition of halite displaying complex architectures. Our results suggest that life, if present under such conditions, does not play a dominant role in the geochemical cycling and mineral precipitation at Dallol as opposed to other hydrothermal sites. Dallol, a hydrothermal system controlled by iron, is a present-day laboratory for studying the precipitation and progressive oxidation of iron minerals, relevant for geochemical processes occurring at early Earth and Martian environments.

The 13C method as a robust alternative to 14C-based measurements of primary productivity in the Mediterranean Sea.

Due to the increasing constraints on using the radioactive isotope 14C to measure primary productivity (14C-PP), we determined the surface carbon fixation rates in the Mediterranean Sea, using the alternative stable isotope 13C method (13C-PP). Rates obtained (13C-POCp) were compared with simultaneous 14C-POCp measurements in samples of different volumes (72 mL and 1.2 L). We also tested the variation of the percentage of dissolved primary production (PER), to the total productivity using organic and inorganic filters (14C method). 13C-POCp rates ranged from 0.4, in the Ionian basin, to 1.5 mgC m-3 h-1 in the Ligurian region. These results agreed with those found with the 14C-PP in 1.2-L samples (two sample t-test, t = 1.035, df = 22, P = 0.31). However, we found that 14C-POCp rates derived from 72-mL incubations were 46% lower than those measured with 13C-PP. The discrepancy between large and small volume incubations was likely due to differences in the number of large phytoplankton cells within the community. PER values measured with silver membrane filters yielded similar results than those obtained using polycarbonate filters. Our findings showed that when the sample size is carefully chosen, the 13C-PP provide comparable results to 14C-PP even in waters of low productivity in the Mediterranean Sea.

Holocene geochemical footprint from Semi-arid alpine wetlands in southern Spain.

Here we provide the geochemical dataset that our research group has collected after 10 years of investigation in the Sierra Nevada National Park in southern Spain. These data come from Holocene sedimentary records from four alpine sites (ranging from ∼2500 to ∼3000 masl): two peatlands and two shallow lakes. Different kinds of organic and inorganic analyses have been conducted. The organic matter in the bulk sediment was characterised using elemental measurements and isotope-ratio mass spectrometry (EA-IRMS). Leaf waxes in the sediment were investigated by means of chromatography with flame-ionization detection and mass spectrometry (GC-FID, GC-MS). Major, minor and trace elements of the sediments were analysed with atomic absorption (AAS), inductively coupled plasma mass spectrometry (ICP-MS), as well as X-ray scanning fluorescence. These data can be reused by environmental researchers and soil and land managers of the Sierra Nevada National Park and similar regions to identify the effect of natural climate change, overprinted by human impact, as well as to project new management policies in similar protected areas.

Effects of seawater mixing on the mobility of trace elements in acid phosphogypsum leachates.

This research reports the effects of pH increase on contaminant mobility in phosphogypsum leachates by seawater mixing, as occurs with dumpings on marine environments. Acid leachates from a phosphogypsum stack located in the Estuary of Huelva (Spain) were mixed with seawater to achieve gradually pH7. Concentrations of Al, Fe, Cr, Pb and U in mixed solutions significantly decreased with increasing pH by sorption and/or precipitation processes. Nevertheless, this study provides insight into the high contribution of the phosphogypsum stack to the release of other toxic elements (Co, Ni, Cu, Zn, As, Cd and Sb) to the coastal areas, as 80-100% of their initial concentrations behaved conservatively in mixing solutions with no participation in sorption processes. Stable isotopes ruled out connexion between different phosphogypsum-related wastewaters and unveiled possible weathering inputs of estuarine waters to the stack. The urgency of adopting effective restoration measures in the study area is also stressed.

Stable isotope insights into the weathering processes of a phosphogypsum disposal area.

Highly acidic phosphogypsum wastes with elevated potential for contaminant leaching are stack-piled near coastal areas worldwide, threatening the adjacent environment. Huge phosphogypsum stacks were disposed directly on the marshes of the Estuary of Huelva (SW Spain) without any impermeable barrier to prevent leaching and thus, contributing to the total contamination of the estuarine environment. According to the previous weathering model, the process water ponded on the surface of the stack, initially used to carry the waste, was thought to be the main washing agent through its infiltration and subsequently the main component of the leachates emerging as the edge outflows. Preliminary restorations have been applied to the site and similar ones are planned for the future considering process water as the only pollution agent. Further investigation to validate the pollution pathway was necessary, thus an evaluation of the relationship between leachates and weathering agents of the stack was carried out using stable isotopes (δ18O, δ2H, and δ34S) as geochemical tracers. Quantification of the contribution of all possible end-members to the phosphogypsum leachates was also conducted using ternary mixing via the stable isotopic tracers. The results ruled out ponded process water as main vector of edge outflow pollution and unveiled a continuous infiltration of estuarine waters to the stack implying that is subjected to an open weathering system. The isotopic tracers revealed a progressive contribution downstream from fluvial to marine signatures in the composition of the edge outflows, depending on the location of each disposal zone within the different estuarine morphodynamic domains. Thus, the current study suggests that the access of intertidal water inside the phosphogypsum stack, for instance through secondary tidal channels, is the main responsible for the weathering of the waste in depth, underlying the necessity for new, more effective restorations plans.

Assembling the Dead, Gathering the Living: Radiocarbon Dating and Bayesian Modelling for Copper Age Valencina de la Concepción (Seville, Spain).

The great site of Valencina de la Concepción, near Seville in the lower Guadalquivir valley of southwest Spain, is presented in the context of debate about the nature of Copper Age society in southern Iberia as a whole. Many aspects of the layout, use, character and development of Valencina remain unclear, just as there are major unresolved questions about the kind of society represented there and in southern Iberia, from the late fourth to the late third millennium cal BC. This paper discusses 178 radiocarbon dates, from 17 excavated sectors within the c. 450 ha site, making it the best dated in later Iberian prehistory as a whole. Dates are modelled in a Bayesian statistical framework. The resulting formal date estimates provide the basis for both a new epistemological approach to the site and a much more detailed narrative of its development than previously available. Beginning in the 32nd century cal BC, a long-lasting tradition of simple, mainly collective and often successive burial was established at the site. Mud-vaulted tholoi appear to belong to the 29th or 28th centuries cal BC; large stone-vaulted tholoi such as La Pastora appear to date later in the sequence. There is plenty of evidence for a wide range of other activity, but no clear sign of permanent, large-scale residence or public buildings or spaces. Results in general support a model of increasingly competitive but ultimately unstable social relations, through various phases of emergence, social competition, display and hierarchisation, and eventual decline, over a period of c. 900 years.