Earth Sciences

The aim of this experiment was to determine the effects of dietary sepiolite supplementation on performance, carcass characteristics, blood parameters and rumen fluid metabolites in Merino cross breed lambs. For this purpose, a total of 21 weaned lambs, which were 3-3.5 months of age were allocated to one control group and two treatment groups each containing 7 lambs. The experiment lasted for a total of 90 days, of which the adaptation and experimental periods were 22 and 68 days, respectively. Pelleted alfalfa and concentrates were given to lambs individually. Concentrate diets of first and the second treatment groups were supplemented with 1 and 2% sepiolite as top dressed, respectively. There were no significant differences observed in body weights, body weight gains, hot and cold carcass yields, meat pH and meat composition among the groups. Relative weights of internal organs and carcass parts were also not affected by sepiolite supplementation. The addition of 1 and 2% sepiolite to the diets of animals increased the consumption of concentrates and total dry matter intake (P < .05). There were no differences among the groups in terms of consumption of dry matter of alfalfa, concentrates and total feed required for one kg body weight gain in lambs. However, body weight gain was increased by 4.22% and total feed conversion ratio was improved by 4.56% with 2% dietary sepiolite supplementation. Haematological and biochemical blood parameters and fecal dry matter were also not affected by the usage of sepiolite. Blood serum IgG levels were increased with sepiolite supplementation (P < .05). While the percentage of acetic acid in the total volatile fatty acids (VFA) in rumen fluid was decreased, neither the proportion of other volatile fatty acids nor the quantity of total volatile fatty acids were affected by dietary addition of sepiolite. It was concluded that 2% sepiolite supplementation in diets of Merinos cross bred lambs as top dressed may have economic benefits based on animal's immunity enhancement and some improvement in body weight gain and total feed conversion ratio without any negative effects on performance, carcass characteristics, rumen metabolites and blood parameters.

Estimation of elastic anisotropy, which is usually caused by rock fabrics and mineral orientation, has an important role in exploration seismology and better understanding of crustal seismic reflections. If not properly taken care of during processing steps, it may lead to wrong interpretation or distorted seismic image. In this thesis, a state-of-the-art under the development Laser Doppler Interferometer (LDI) device is used to measure phase velocities on the surface of rock samples from a major deformation zone (Österbybruk Deformation Zone) in the Bergslagen region of eastern Sweden. Then, a general inversion code is deployed to invert measured phase velocities to obtain full elastic stiffness tensors of two samples from the major deformation zone in the study area. At the end, results are used to correct for the anisotropy effects using three dimensionless Tsvankin's parameters and a non-hyperbolic moveout equation. The resulting stacked section shows partial reflection improvement of the deformation zone compared with the isotropic processing section. This suggests that rock anisotropy may also contribute to the generation of reflections from the deformation zones in the study area but requires further investigations. I I would like to express my deepest appreciation to all those who provided me the possibility to complete this thesis. A special gratitude I give to my supervisor, Dr. Alireza Malehmir, whose contribution in productive suggestions and encouragement, helped me to complete this thesis. Special thanks go to my dearest friends, Taher Mazloumian, Ershad Gholamrezaie, Hanieh Shahrokhi, Amir Abdi, Omid Ahmadi, Ashkan Dorostkar and Magnus Andersson who helped me with their useful comments and suggestions about my thesis. I have to appreciate the guidance given by other professors and supervisors especially in my project presentation that has improved my presentation skills thanks to their comments and advices. Furthermore, I would also like to thank: • Dr. Robert W. Vestrum for letting me run his codes and use his helpful advices. • Geological Survey of Sweden for financially supporting the Dannemora data acquisition and collecting rock samples. • Dr. Maxim Lebedev for his corporation during laboratory measurements. • GLOBE Claritas T M under license from the Institute of Geological and Nuclear Sciences Limited, Lower Hutt, New Zealand was used to process the seismic data. • This master thesis has been done in collaboration with Curtin University in Perth.

One of the most important pathways for exposure to metals is drinking water ingestion. Chronic or acute exposure to metals can endanger the health of the exposed population, and hence, estimation of human health risks is crucial. In the current study for the first time, the concentrations of Mercury (Hg), Arsenic (As), Zinc (Zn), Lead (Pb) and Cobalt (Co) in 120 collected tap water samples (2015, July-November) from Ilam city, Iran were investigated using flame atomic absorption spectrophotometer. Also, the metal-induced carcinogenic and non-carcinogenic risks for consumers exposed to tap drinking water were calculated. The average (range) concentrations of Hg, Zn, As, Pb and Co were defined as 0.40 ± 0.10 μg/L (ND-0.9 μg/L), 5014 ± 5707 μg/L (2900.00-5668.33 μg/L), 21.008 ± 2.876 μg/L (3.5-62 μg/L), 30.38 ± 5.56 μg/L (6-87 μg/L), and 11.34 ± 1.61 μg/L (0.1-50 μg/L), respectively. Average concentrations of all examined metals were significantly higher than WHO and national standard ...

IMS reveals distribution of nitroaromatic compounds and their associations in soil. • Aromatic C plays a key role in sorption of nitroaromatic compounds to soil. • Hydrophobicity affects sorption of nitroaromatic compounds to clay minerals in soil.

High spatial resolution, 7 mm  7 mm confocal image plane masking, and 1 mm step size mapping were used to image small areas of an organically modified silicate (ORMOSIL) film. The film was prepared by the sol-gel process from separately hydrolyzed isobutyltrimethoxysilane and tetraethoxysilane sols that were mixed just prior to being spin cast onto a polished silicon substrate. Detailed mapping was performed in a reflection absorption mode with an infrared microspectrometer at beamline U10B of the National Synchrotron Light Source of Brookhaven National Laboratory. The main objective of this study was to characterize the spatial distribution of organic (i.e. butyl) components within the film. Functional group maps of each film region were produced from the peak areas of the CH, OH, and Si-O stretching bands. The organic content (relative to total silicate) was obtained by ratioing the peak areas of the CH and Si-O absorption bands. Functional group maps of a relatively large region (230 mm  230 mm) with a 10 mm  10 mm mask size and a 10 mm step size reveal heterogeneity on a larger scale. These data demonstrate the utility of IR imaging in the study of ORMOSIL film chemical heterogeneity.

RATIONALETo enhance the ionization efficiencies in atmospheric pressure photoionization mass spectrometry a dopant with favorable ionization energy such as chlorobenzene is typically used. These dopants are typically toxic and difficult to mix with water‐soluble organic solvents. In order to achieve a more efficient and less toxic dopant, a multicomponent mixed dopant was explored.METHODSA multicomponent mixed dopant for non‐targeted rapid screening of polycyclic aromatic hydrocarbons (PAHs) was developed and optimized using ultra high performance liquid chromatography (UPLC) coupled to atmospheric pressure photoionization high‐resolution mass spectrometry. Various single and multicomponent mixed dopants consisting of ethanol, chlorobenzene, bromobenzene, anisole and toluene were evaluated.RESULTSFourteen out of eighteen PAHs were successfully separated and detected at low pg/μL levels within 5 min with high mass accuracy ≤4 ppm. The optimal mixed multicomponent dopant consisted of ...

An attempt was made to study the impact of excreta from poultry birds fed with different levels of Azolla on water quality and performance of common carp. Day old broiler chicks were reared and brooded for 14 days on commercial pre-starter diet and from 15 day broilers were supplemented with 2 and 4% Azolla in their basal feed. Excreta from these birds were collected, sun dried and mixed with basal diet of fishes in ratio of 50:50 (Basal diet: excreta). 60 fingerlings of common carp were procured from Government fish hatchery, Jammu, acclimatized for one month with basal feed and regular water exchange. Experimental water in tubs of 100 L capacity was treated in duplicates along with control for a period of 28 days. There were no mortality and adverse impact was observed in behaviour of experimental fish. No significant differences were observed in growth parameters of fishes which may be attributed to short duration of experiment. All the water quality parameters were found to be i...

The seismic stratigraphy of the western McMurdo Sound region has been reevaluated in response to the apparent 8 m y . discrepancy in the age of seismic units traced between the CRP-1 drillhole located off Cape Roberts and the CIROS-1 drillhole, located 70 km further south. All the available seismic reflection in the region, including new single and multi-channel seismic data recorded in the region in 1996 by RIV N B PALMER, have been compiled and reanalysed to develop a consistent interpretation of the seismic units in the region, using the seismic stratigraphy of . The interpretation has been based on the original interpretation of seismic units in the data recorded by the RIV S. P. LEE (Cooper & Davey, 1987) and has been traced across the region to the CRP-1 drillsite. A crucial correlation at the CRP-1 site is for the boundary between the Units V3 and V4. This unconformity lies at depth east of the drillsite and the associated reflection event has been traced to the CRP-l site in two ways; one directly across the Roberts Ridge, where it has to be traced through the seafloor multiple, and the second through deep water north of Roberts Ridge. The two correlation pathways result in a discrepancy of about 100 m where the unconformity intersects CRP-l. If the correlation across Roberts Ridge is correct then the strata equivalent to 3 18 m in CIROS-1 will, at the CRP-1 site, be 21 thick and the V 3 N 4 boundary lies 163 mbsf. If the alternative is correct then the equivalent strata at the CRP-1 site will have also reduced in thickness, but only to about 120 m, and the V3N4 boundary lies around 250 mbsf.

A late Quaternary, current-lain sediment drift deposit over 30 m in thickness has been discovered on the continental shelf of East Antarctica in an 850 m deep glacial trough off George Vth Land. Radiocarbon dating indicates that a period of rapid deposition on the drift (averaging 290 cm/kyr) occurred in the mid-Holocene, between about 3000 and 5000 yr before present (yr bp). Slower deposition rates of around 10 cm/kyr, during the past 0±3000 yr and from 5000 to about 13000 yr bp, coincides with the deposition of bioturbated, ice-rafted debris (IRD) rich, sandy mud under an energetic bottom current regime. In contrast, the mid-Holocene (3000±5000 yr bp) sediments are ®ne-grained, laminated to cross-laminated with minimal IRD content, and are contemporaneous with a period of warmer marine conditions with less sea ice production. This pattern suggests that bottom currents were weaker than present day in the mid-Holocene, and that the rate of dense bottom water production was reduced at that time. This scenario is consistent with the hypothesis of non-steady state rates of Antarctic bottom water production through the Holocene as recently proposed by Broecker and his colleagues.

Predictions of present day secular variations in the Earth's long wavelength geopotential driven by glacial isostatic adjustment (GIA) have previously been analyzed to infer the radial profile of mantle viscosity and to constrain ongoing cryospheric mass balance. These predictions have been based on spherically symmetric Earth models. We explore the impact of lateral variations in mantle viscosity using a new finite-volume formulation for computing the response of 3-D Maxwell viscoelastic Earth models. The geometry of the viscosity field is constrained from seismic-to-mographic images of mantle structure, while the amplitude of the lateral viscosity variations is tuned by a free parameter in the modeling. We focus on the zonal J ˙S harmonics for degrees S = 2,. . .,8 and demonstrate that large-scale lateral viscosity variations of two to three orders of magnitude have a modest, 5-10%, impact on predictions of J ˙2. In contrast, predictions of higher degree harmonics show a much greater sensitivity to lateral variation in viscosity structure. We conclude that future analyses of secular trends (for degree S N 2) estimated from ongoing (GRACE, CHAMP) satellite missions must incorporate GIA predictions based on 3-D viscoelastic Earth models.

This study examined the impacts of hemlock woolly adelgid (Adelges tsugae Annand) (HWA), a small, invasive insect, on foliar chemistry, forest floor microclimate, and subsequent green foliage decomposition in eastern hemlock (Tsuga canadensis (L.) Carrière) forests. We investigated the direct effects of HWA feeding and indirect changes in microclimate on foliar decomposition by incubating HWA-infested and uninfested foliage across eight eastern hemlock dominated stands in southern New England that had different histories of HWA infestation. Infested stands had much poorer average crown health (3.4 versus 1.4 crown loss ratings), higher percent open sky (10.9 ± 2.4 vs. 5.3 ± 0.5 gap light index), and lower organic soil moisture (0.83 ± 0.02 g•g -1 vs. 1.06 ± 0.05 g•g -1 ) than uninfested stands. There were no significant differences in percent C, percent N, or percent lignin for the excised foliage at the start of the study. However, after 120 days, decomposing foliage from infested trees had significantly higher N concentrations (1.83% ± 0.05% vs. 1.69% ± 0.02 %) and lower C/N ratios (29.9 ± 0.8 vs. 31.6 ± 0.2) than uninfested foliage, suggesting that HWA herbivory resulted in alterations of litter chemistry as decomposition progressed. Mass loss of common uninfested foliage was lower in uninfested hemlock stands than in infested ones (30.9% ± 0.7% vs. 34.2% ± 0.1%). These rates of mass loss were significantly correlated with microclimate factors and indicate that organic soil moisture levels are controlling decomposition in HWA-infested forests. Infestation by HWA causes virtually no direct feeding damage to foliage, but it does lead to several indirect and significant ecological and functional changes over the 10-to 20-year course of infestation and stand decline. Résumé : Cette étude examine les impacts du puceron lanigère de la pruche (Adelges tsugae Ann.), un petit insecte invasif, sur les propriétés chimiques du feuillage, le microclimat dans la couverture morte et la décomposition subséquente du feuillage vert dans les forêts de pruche du Canada (Tsuga canadensis (L.) Carrière). Nous avons étudié les effets directs du puceron lanigère de la pruche et les changements indirects du microclimat sur la décomposition du feuillage en incubant du feuillage sain et du feuillage infesté par le puceron lanigère de la pruche dans huit peuplements dominés par la pruche du Canada dans le sud de la Nouvelle-Angleterre qui avaient différents historiques d'infestation par le puceron lanigère de la pruche. Les peuplements infestés étaient caractérisés par un état de santé des cimes beaucoup plus détérioré (3,4 vs. 1,4 d'indice de perte de cime), un pourcentage plus élevé d'ouverture du couvert (10,9 ± 2,4 vs. 5,3 ± 0,5 de coefficient de trouées lumineuses) et une humidité du sol organique plus faible (0,83 ± 0,02 vs. 1,06 ± 0,05 g•g -1 ) que les peuplements sains. Il n'y avait pas de différence significative dans le pourcentage de C, N ou de lignine du feuillage excisé au début de l'étude mais, après 120 jours, le feuillage en décomposition des arbres infestés avait des concentrations significativement plus élevées de N (1,83 ± 0,05 vs. 1,69 ± 0,02 %) et un rapport C/N plus faible (29,9 ± 0,8 vs. 31,6 ± 0,2) que le feuillage sains, ce qui indique que l'herbivorisme du puceron lanigère de la pruche entraîne des modifications des propriétés chimiques de la litière à mesure que la décomposition progresse. La perte de masse du feuillage sain commun était plus faible dans les peuplements de pruche sains que dans les peuplements infestés (30,9 ± 0,7 vs. 34,2 ± 0,1 %). Ces taux de perte de masse étaient significativement corrélés avec les facteurs du microclimat et indiquent que le niveau d'humidité du sol organique contrôle la décomposition dans les forêts infestées par le puceron lanigère de la pruche. Le puceron lanigère de la pruche ne cause pratiquement aucun dommage direct au feuillage en s'alimentant mais entraînent plusieurs changements écologiques et fonctionnels indirects et significatifs pendant la période d'infestation et de dépérissement du peuplement qui dure de 10 à 20 ans.

The Mersin ophiolite, represented by approximately 6-km-thick oceanic lithospheric section on the southern flank of the Taurus calcareous axis, formed in the Mesozoic Neo-Tethyan ocean some time during Late Cretaceous in southern Turkey. The ultramafic and mafic cumulates having over 3 km thickness consist of duniteBchromite, wehrlite, clinopyroxenite at the bottom and pass into gabbroic cumulates in which leucogabbro, olivine-gabbro and anorthosite are seen. Crystallization order is olivine (Fo 91-80 )Bchromian spinel (Cr8 60-80), clinopyroxene (Mg8 95-77 ), plagioclase ) and orthopyroxene (Mg8 68- 77 ). Mineral chemistry of ultramafic and mafic cumulates suggest that highly magnesian olivines, clinopyroxenes and absence of plagioclase in the basal ultramafic cumulates are in good agreement with products of high-pressure crystal fractionation of primary basaltic melts beneath an island-arc environment. Major, trace element geochemistry of the cumulative rocks also indicate that Mersin ophiolite was formed in an arc environment. Coexisting Ca-rich plagioclase and Forich olivine in the gabbroic cumulates show arc cumulate gabbro characteristics. Field relations as well as the geochemical data support that Mersin ophiolite formed in a supra-subduction zone tectonic setting in the southern branch of the Neo-Tethys in southern Turkey.

Carbon captured by marine living organisms is called "blue carbon", and seagrass meadows are a dominant blue carbon sink. However, our knowledge of how seagrass increases sedimentary organic carbon (OC) stocks is limited. We investigated two pathways of OC accumulation: trapping of organic matter in the water column and the direct supply of belowground seagrass detritus. We developed a new type of box corer to facilitate the retrieval of intact cores that preserve the structures of both sediments (including coarse sediments and dead plant structures) and live seagrasses. We measured seagrass density, total OC mass (OC total ) (live seagrass OC biomass (OC bio ) + sedimentary OC mass (OC sed )), and the stable carbon isotope ratio (δ 13 C) of OC sed and its potential OC sources at Thalassia hemprichii dominated back-reef and Enhalus acoroides dominated estuarine sites in the tropical Indo-Pacific region. At points with vegetation, OC bio accounted for 25 % and OC sed for 75 % of OC total ; this contribution of OC bio to OC total is higher than in globally compiled data. Belowground detritus accounted for ∼ 90 % of the OC mass of dead plant structures (> 2 mm in size) (OC dead ). At the back-reef site, belowground seagrass biomass, OC dead , and δ 13 C of OC sed (δ 13 C sed ) were positively correlated with OC sed , indicating that the direct supply of belowground seagrass detritus is a major mechanism of OC sed accumulation. At the estuarine site, aboveground seagrass biomass was positively correlated with OC sed but δ 13 C sed did not correlate with OC sed , indicating that trapping of suspended OC by seagrass leaves is a major mech-anism of OC sed accumulation there. We inferred that the relative importance of these two pathways may depend on the supply (productivity) of belowground biomass. Our results indicate that belowground biomass productivity of seagrass meadows, in addition to their aboveground morphological complexity, is an important factor controlling their OC stock. Consideration of this factor will improve global blue carbon estimates.

Carbon sequestrated in marine ecosystems has been termed “blue carbon”, and seagrass meadows are one of the most dominant blue carbon stocks. Globally, one of the major distribution sites of seagrass meadows is coral reef flat. Recent studies have revealed that the amount of sedimentary organic matter in tropical and subtropical coasts is comparable to that in temperate coasts. However, these estimations are based on a few data and have wide range. Since quantifying organic carbon in the carbonate sediment is technically difficult and costly, easier methods for estimating the amount of organic carbon in seagrass meadows are strongly needed to assess the global blue carbon stocks for mitigation of global warming. Seagrass biomass is suggested to have responsible for the variability of seagrass carbon sink capacity, but the models have not been presented yet. To identify the relationship between seagrass biomass and blue carbon stocks, we developed a new box corer which can facilitate...

The coral reef ecosystems at Palau Island have attracted growing attention recently. However, there are still many uncertainties about the coral reef ecosystems there because the characteristics of nutrient dynamics and primary production are expected to be largely different between shallow fringing coral reefs distributed in the Southern Japan and barrier reefs with deeper lagoon at Palau Island. Especially, how physical parameters such as light intensity, current velocity and wave strength, which vary depending on the water depth, control the primary production and material transport in the lagoon area is not yet well known. In this study, we investigated nitrogen cycles in the lagoon system combining the observations and several process studies: 1) distribution of nutrients and dissolved organic nitrogen in the water column, 2) depth-dependent characteristics of the surface sediment such as particle size, organic matter contents and nutrient profiles in the porewater, 3) flux of ...

Paleoecology is the study of the relationships between past organisms and their environments. The interpretation of the paleoecology and reconstruction of a paleoenvironment comes from extrapolating modern ecological theory and examples to fossil settings (e.g.

Groundwater is vulnerable and more susceptible to contamination from various anthropogenic elements. Various steps are taken to measure the groundwater vulnerability for a sustainable groundwater development. The present study estimates the aquifer vulnerability by applying DRASTIC model in the Geographic Information System (GIS) environment. The DRASTIC model uses seven hydrological parameters which include depth to water level, net recharge, aquifer media, soil media, topography, the impact of vadose zone and hydraulic conductivity. DRASTIC index was calculated from DRASTIC model that ranged from 31 to 154. All these parameters characterize the hydrological setting for evaluating aquifer vulnerability. Sensitivity analyses have also been performed to determine the sensitivity of every individual DRASTIC parameter towards the aquifer vulnerability. Sensitivity analysis indicated that all the parameters have an almost similar influence on vulnerability index. Depth to water paramete...

Salmonella Typhi (S. Typhi) is the causative agent of typhoid fever; a systemic disease affecting ~20 million people per year globally. There are little data regarding the contemporary epidemiology of typhoid in Latin America. Consequently, we aimed to describe some recent epidemiological aspects of typhoid in Colombia using cases reported to the National Public Health Surveillance System (Sivigila) between 2012 and 2015. Over the four-year reporting period there were 836 culture confirmed cases of typhoid in Colombia, with the majority (676/836; 80.1%) of reported cases originated from only seven departments. We further characterized 402 S. Typhi isolates with available corresponding data recovered from various departments of Colombia through antimicrobial susceptibility testing and molecular subtyping. The majority (235/402; 58.5%) of these typhoid cases occurred in males and were most commonly reported in those aged between 10 and 29 years (218/402; 54.2%); there were three (0.74%) reported fatalities. The overwhelming preponderance (339/402; 84.3%) of S. Typhi were susceptible to all tested antimicrobials. The most common antimicrobial to which the organisms exhibited non-susceptibility was ampicillin (30/ 402;7.5%), followed by nalidixic acid (23/402, 5.7%). Molecular subtyping identified substantial genetic diversity, which was well distributed across the country. Despite the diffuse pattern of S. Typhi genotypes, we identified various geographical hotspots of disease associated with local dominant genotypes. Notably, we found limited overlap of Colombian genotypes with organisms reported in other Latin American countries. Our work highlights a substantial burden of typhoid in Colombia, characterized by sustained transmission in some regions and limited epidemics in other departments. The disease is widely distributed across the country and associated with multiple antimicrobial susceptible genotypes that appear to be restricted to Colombia. This study provides a current perspective for typhoid in Latin

During the research programme conducted on the OVPuerto Deseadoin the summers of 2011 and 2013, 36 stations were sampled using a demersal net at depths between 53–590 m in the Antarctic Peninsula and South Shetland Islands. A total 3378 fish specimens belonging to 36 species were recorded. Notothenidae was the best-represented family in species number, withLepidonotothen nudifrons,L. larseniandTrematomus scottibeing the most numerous species. Of the fish assemblages, 20% of the species were considered as dominant, 10% as common, 13% as occasional and 57% as rare. Six groups (and two sub-groups) were obtained by the ordination diagram based on geographical location: group 1=Gerlache Strait, group 2=Deception Islands, group 3=Biscoe Island, group 4=between Elephant and King George islands, group 5=northern Antarctic Peninsula, and group 6=South Shetland Islands, with sub-groups 6a shallower South Shetland Islands and 6b deeper South Shetland Islands. Sampling depth and water temperatu...

Forest harvesting can impact site quality by removing essential nutrients, exacerbating effects of historic base cation losses associated with acid deposition. We studied the 30-year trajectory of forest recovery from clearcutting (whole-tree harvest (WTH)) in a forest originally dominated by sugar maple (Acer saccharum). At both the watershed-scale (21.9 ha) and "detailed" plot-scale (1 m 2 ), a dramatic decline of sugar maple was observed, along with maintenance of American beech (Fagus grandifolia), and an increase in birch, mainly yellow birch (Betula allegheniensis). Many of the "detailed" plots where sugar maple failed to recruit became unoccupied rather than being "won" by another species. The decline of sugar maple was most severe in the upper elevation zones of the watershed, where low base status (especially Ca) of the soils was a likely driver. The results support previous studies indicating that regeneration by sugar maple is severely compromised on base cation depleted soils. Lower survival of seedlings for sugar maple emphasized the importance of maintaining advance regeneration to favor desired species such as sugar maple. Foresters should consider that sites with low base saturation and exchangeable Ca are likely to exhibit regeneration failure for sugar maple in the long-term, even those with initial dominance by this species.

Forest harvesting can impact site quality by removing essential nutrients, exacerbating effects of historic base cation losses associated with acid deposition. We studied the 30-year trajectory of forest recovery from clearcutting (whole-tree harvest (WTH)) in a forest originally dominated by sugar maple (Acer saccharum). At both the watershed-scale (21.9 ha) and "detailed" plot-scale (1 m 2 ), a dramatic decline of sugar maple was observed, along with maintenance of American beech (Fagus grandifolia), and an increase in birch, mainly yellow birch (Betula allegheniensis). Many of the "detailed" plots where sugar maple failed to recruit became unoccupied rather than being "won" by another species. The decline of sugar maple was most severe in the upper elevation zones of the watershed, where low base status (especially Ca) of the soils was a likely driver. The results support previous studies indicating that regeneration by sugar maple is severely compromised on base cation depleted soils. Lower survival of seedlings for sugar maple emphasized the importance of maintaining advance regeneration to favor desired species such as sugar maple. Foresters should consider that sites with low base saturation and exchangeable Ca are likely to exhibit regeneration failure for sugar maple in the long-term, even those with initial dominance by this species.

During the solar eclipse of 11 August 1999, measurements of sap flow at branch and stem level were made in a 75-year-old beech tree which was 27 m high growing near Ghent, Belgium. The sky was relatively free from clouds during the eclipse which reached its maximum at 10.26 h GMT (=10.36 h True Solar Time). Measurements also included short-wave radiation, air temperature and vapour pressure deficit. The daily variation of the sap flows and of short-wave radiation and vapour pressure deficit were compared to a reference based on mean diurnal cycles. During the eclipse short-wave radiation, air temperature and vapour pressure deficit showed a maximum reduction between the pre-eclipse maximum and the following minimum of respectively 439 W/m 2 , 3.0 • C and 0.27 kPa. The reduction of the solar energy resulted in the formation of a temporary temperature inversion above the canopy. At the time of maximum eclipse the sap flow rates at branch level and at stem level were reduced by 92 and 76%, respectively, indicating non-stationary flow conditions in the beech tree. Due to the eclipse, the tree reduced its water loss from transpiration by 32.0 kg of water, being about 25% of the total amount which is transpired by the beech tree during a sunny day in August. Regression analysis indicated that both short-wave radiation and vapour pressure deficit changed in a nearly linear fashion during the eclipse. Sap flow rates were given by an exponential equation, allowing the description of sap flow dynamics in terms of time lag and rate of change.

This paper considers the lithospheric structure and evolution of the wider Barents–Kara Sea region based on the compilation and integration of geophysical and geological data. Regional transects are constructed at both crustal and lithospheric scales based on the available data and a regional three-dimensional model. The transects, which extend onshore and into the deep oceanic basins, are used to link deep and shallow structures and processes, as well as to link offshore and onshore areas. The study area has been affected by numerous orogenic events in the Precambrian–Cambrian (Timanian), Silurian–Devonian (Caledonian), latest Devonian–earliest Carboniferous (Ellesmerian–Svalbardian), Carboniferous–Permian (Uralian), Late Triassic (Taimyr, Pai Khoi and Novaya Zemlya) and Palaeogene (Spitsbergen–Eurekan). It has also been affected by at least three episodes of regional-scale magmatism, the so-called large igneous provinces: the Siberian Traps (Permian–Triassic transition), the High ...

A comprehensive assessment of policy impact on greenhouse gas (GHG) emissions from agricultural soils requires careful consideration of both socio-economic aspects and the environmental heterogeneity of the landscape. We developed a modelling framework that links the large-scale economic model for agriculture CAPRI (Common Agricultural Policy Regional Impact assessment) with the biogeochemistry model DNDC (DeNitrification DeComposition) to simulate GHG fluxes, carbon stock changes and the nitrogen budget of agricultural soils in Europe. The framework allows the ex-ante simulation of agricultural or agri-environmental policy impacts on a wide range of environmental problems such as climate change (GHG emissions), air pollution and groundwater pollution. Those environmental impacts can be analyzed in the context of economic and social indicators as calculated by the economic model. The methodology consists of four steps: (i) definition of appropriate calculation units that can be considered as homogeneous in terms of economic behaviour and environmental response; (ii) downscaling of regional agricultural statistics and farm management information from a CAPRI simulation run into the spatial calculation units; (iii) designing environmental model scenarios and model runs; and finally (iv) aggregating results for interpretation. We show the first results of the nitrogen budget in croplands in fourteen countries of the European Union and discuss possibilities to improve the detailed assessment of nitrogen and carbon fluxes from European arable soils.

Understanding the relationship between land use and the dynamics of nitrate (NO - 3 ) is the key to constrain sources of NO - 3 export in order to aid effective management of waterways. In this study, isotopic compositions of NO - 3 (δ 15 N-NO - 3 and δ 18 O-NO - 3 ) were used to elucidate the effects of land use (agriculture in particular) and rainfall on the major sources and sinks of NO - 3 within the Western Port catchment, Victoria, Australia. This study is one of the very few studies carried out in temperate regions with highly stochastic rainfall patterns, enabling a more comprehensive understanding of the applications of NO - 3 isotopes in catchment ecosystems with different climatic conditions. Longitudinal samples were collected from five streams with different agriculture land use intensities on five occasionsthree during dry periods and two during wet periods. At the catchment scale, we observed significant positive relationships between NO - 3 concentrations (p < 0.05), δ 15 N-NO - (p < 0.01) and percentage agriculture (particularly during the wet period), reflecting the dominance of anthropogenic nitrogen inputs within the catchment. Different rainfall conditions appeared to be major controls on the predominance of the sources and transformation processes of NO - 3 in our study sites. Artificial fertiliser was the dominant source of NO - 3 during the wet periods. In addition to artificial fertiliser, nitrified organic matter in sediment was also an apparent source of NO - 3 to the surface water during the dry periods. Denitrification was prevalent during the wet periods, while uptake of NO - 3 by plants or algae was only observed during the dry periods in two streams. The outcome of this study suggests that effective reduction of NO - 3 load to the streams can only be achieved by prioritising management strategies based on different rainfall conditions. W. W. Wong et al.: Nitrate isotopes in streams on a catchment scale et al., 2011). To date, the most promising tool to investigate the sources and sinks of NO - 3 are the dual isotopic compositions of NO - 3 at natural abundance level (expressed as δ 15 N-NO - 3 and δ 18 O-NO - 3 in ‰). Preferential utilisation of lighter isotopes ( 14 N and 16 O) over heavier isotopes ( 15 N and 18 O) leads to distinctive isotopic signatures that differentiate the various NO - 3 sources/end members (e.g. inorganic and organic fertiliser, animal manure, atmospheric deposition) and the predictable kinetic fractionation effect when NO - 3 undergoes different biological processes (e.g. nitrogen fixation and denitrification). For instance, numerous previous culture-based experiments revealed that denitrification and phytoplankton assimilation fractionate N and O isotopes equally (1 : 1 pattern), leaving behind NO - 3 that is enriched in both 15 N and 18 O (Fry, 2006). Simultaneous measurement of δ 15 N-NO - 3 and δ 18 O-NO - 3 also provides complementary information on the cycling of NO - 3 in the environment. δ 18 O-NO - 3 is a more effective proxy of internal cycling of NO - 3

Environmental context.Effective mitigation of algal blooms, and their associated detrimental impacts on flora and fauna, requires an understanding of the factors leading to bloom development, including nutrients, light and hydrodynamics. We investigated a shallow, freshwater lake and demonstrate that there is sufficient bioavailable phosphorus to annually generate a large algal biomass. Extensive, seasonal phosphorus release from sediments is controlled by the interactions of the biogeochemical cycles of nitrogen, carbon, oxygen, iron and sulfur. .The shallow, polymictic Ornamental Lake in the Royal Botanic Gardens, Melbourne, Australia, has suffered significant blooms of toxic Anabaena then Microcystis species every summer over the last decade. Although the hydrodynamic conditions of the water column are conducive for algal growth, the prolific growth is controlled by the bioavailable phosphorus concentration. Springtime phosphorus fluxes of 0.1–0.2 mmol m–2 day–1 from the sediment...

The deterioration of surface waters is one of the most important issues in the environmental management of the European Union. Thus, the EU Water Framework Directive 2000/60/EC (WFD) requires "good ecological and chemical status" of surface waters by 2015 allowing only a slight departure from ecological reference conditions characterized by the biological communities typical for the conditions of minimal anthropogenic impact. The WFD requires the determination of ecological reference conditions and the present ecological status of surface waters. To meet this legislative demand, sedimentary diatom assemblages were used in these studies with various methods 1) to assess natural and human activity induced environmental changes, 2) to characterize background conditions 3) to evaluate the present ecological status and 4) to predict the future of the water bodies in the light of palaeolimnological data. As the WFD refers to all surface waters, both coastal and inland sites were included. Two long and two short sediment cores from the Archipelago Sea in the northern Baltic Sea were examined for their siliceous microfossils in order to assess (1) the Holocene palaeoenvironmental history and (2) the recent eutrophication of the area. The diatom record was divided into local diatom assemblage zones (LDAZ, long cores) and diatom assemblage zones (DAZ, short cores). Locally weighted weighted averaging regression and calibration (LWWA) was applied for the quantitative reconstruction of past TN concentrations (short cores). An age model for the long cores was constructed by using independent palaeomagnetic and AMS-14 C methods. The short cores were dated using radiometric ( 210 Pb, 226 Ra and 137 Cs) methods. The long cores date back to the early history of the Archipelago Sea, which was freshwater -no salinity increase referable to the brackish phase of the Yoldia Sea is recognized. The nutrient status of the lacustrine phase was slightly higher in the Archipelago Sea than in the Baltic Proper. Initial brackish-water influence is observed at 8 150 ±80 cal. BP (LDAZ4), but fully brackish conditions were established at 7 700 ±80 cal. BP (LDAZ5). The diatom assemblages indicate increasing salinity, warming climate and possible eutrophic conditions during the lacustrine to brackish-water transition. The decreasing abundance of Pseudosolenia calcar-avis (Schultze) Sundström and the increasing abundance of the ice-cover indicator species Pauliella taeniata (Grunow) Round and Basson indicate decreasing salinity and climatic cooling after ca. 5 000 cal. BP. Signs of eutrophication are visible in the most recent diatom assemblage zones of both short cores. Diatom-inferred total nitrogen (DI-TN) reconstructions partially fail to trace the actual measured total nitrogen concentrations especially from the late 1980s to the mid 1990s. This is most likely due to the dominating diatom species Pauliella taeniata, Thalassiosira levanderi Van Goor and Fragilariopsis cylindrus (Grunow) W. Krieger being more influenced by factors such as the length of the ice-season rather than nutrient concentrations. It is concluded that the diatom assemblages of the study sites are principally governed by climate fluctuations, with a slight influence of eutrophication visible in the most recent sediments. There are indications that global warming, with reduced

The deterioration of surface waters is one of the most important issues in the environmental management of the European Union. Thus, the EU Water Framework Directive 2000/60/EC (WFD) requires “good ecological and chemical status” of surface waters by 2015 allowing only a slight ...

The relative impacts of autogenic and allogenic controls on the architectural evolution of deep-sea fans are not well constrained, mainly because of the difficulty in evaluating the role of each control on any specific stratigraphic pattern. This study presents four-dimensional (4D) forward stratigraphic modelling of the Late Quaternary Congo Axial Fan, which provides new insights on forcing factors of sedimentation over time. This modelling is based on a geological model describing successive sedimentary progradational/retrogradational cycles in the Congo turbidite system during the last 38 kyr. Analyses of geophysical and marine core data have suggested that the architectural cycles were controlled by changes in fluvial sediment discharge in relation to arid and humid periods in the Congo River watershed. The aims of this study were to simulate the architectural evolution of the Late Quaternary Congo Axial Fan from 210 ka to the present and investigate the factors controlling sedimentation using DionisosFlow™, a process-based stratigraphic forward modelling software. For this objective, several scenarios were tested to simulate the role of autogenic and climate forcings based on proxies recorded in marine sediments. The modelling results confirmed that climatic variations of sediment and water discharge succeeded in reproducing the timing, position, and sediment volume of basin-scale progradational/retrogradational cycles. The best-fit simulations particularly emphasise the role of continental vegetation cover expansion, governed by the precession-driven West African monsoon, on the sediment flux to the deep-marine environment. This vegetation/climate coupling acts directly on the transport capacity of flow over time by controlling the magnitude of river runoff and the timing of sediment production, storage, and transfer from the continent to the ocean. Thus, our results confirm the utility of stratigraphic forward models in constraining "source-to-sink" models for the architectural evolution of submarine fans. Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site. ► First 4D stratigraphic forward modelling of the Quaternary Congo Fan (DionisosFlow™). ► Test of autogenic and climate forcings using continental and marine proxies. ► Relative impact of sediment/water discharge and sand fraction on turbidite geometry. ► Role of climate-vegetation coupling on the sediment transfer from land to turbidites.

Remote sensing tools allow the environmental evaluation of coastal wetlands at a landscape scale, but a deeper understanding is needed of the interactions between biophysical parameters and the electromagnetic signal. The goal of this work was to analyze and quantify the influence of the aboveground biomass and the Leaf Area Index (LAI) on the spectral response of Spartina densiflora marshes in Mar Chiquita coastal lagoon, Argentina. Spectral reflectance at high resolution was measured in S. densiflora canopies under natural conditions, manipulating standing crop by means of successive harvest. Reflectance data were acquired using a spectroradiometer in visible, near infrared (IR) and shortwave IR bands. Spectral Vegetation Indices (VI) were calculated for each standing crop-LAI situation. Several VI significantly correlated with standing crop and LAI, including indices 1) based on the red-IR edge (IR Index (IRI), 695/760 ratio, Simple Ratio (SR), Red Edge Inflection Point (REIP), and different variations of the Normalized Difference VI (NDVI Rouse, NDVI amber, NDVI NOAA, NDVI Landsat, NDVI Modis), 2) indices based on the sharp change green-IR (green NDVI (GNDVI), 800/550 ratio) and 3) indices with a correction for soil noise (OSAVI: Optimized Soil Adjusted VI (OSAVI), and Modified SAVI (MSAVI). The indices with significant regressions with standing crop and LAI were IRI, NDVI Amber and REIP. The total and green standing crop showed better adjustments than LAI, showing R 2 values of 0.5. These values were obtained with REIP index. Results indicate that LAI and standing crop of S. densiflora stands could be determined from spectral data but estimations should be taken carefully in high biomass scenarios, because of indexes saturation at higher LAI values. Spectral indices . Remote sensing . Standing crop . Biomass . Leaf area index . Spartina densiflora * G. González Trilla

Despite increasing use of constructed wetlands for treatment of metalenriched acid coal mine drainage (AMD), the biotic and abiotic mechanisms of metal retention in such wetlands are poorly understood. The present study was conducted to evaluate the processes responsible for Fe and Mn retention in peat and the effects of microbial activity, pH, temperature, and metal concentration in AMD on these processes. Experimental units consisted in 30 g (wet wt.) of fresh Sphagnum peat, which was repeatedly flushed with synthetic AMD at pH 3.5. Of the four major processes of metal cation retention in peat (cation exchange, complexation with peat organics, precipitation as oxides, and precipitation as sulfides), Fe oxidation and Fe binding on peat organics were predominant, with Fe oxides and organically bound Fe making up, respectively, 62 and 22% of the total Fe in the peat at the end of the experiment. Whereas Fe complexation was a finite process, reaching saturation at 12 mg Fe g' dry peat, Fesxide concentration in peat increased steadily throughout the experiment. At pH 3.5, Fe-oxide precipitation was depressed by the addition of an antiseptic (formaldehyde) to AMD, suggesting that the process was microbially mediated. Iron oxide precipitation was higher at pH 5.5 than 3.5 and less depressed at pH 5.5 than 3.5 by the presence of formaldehyde in AMD. The efficiency of peat to remove Fe from AMD was diminished at low temperature (<15 "C) and high Fe concentration in AMD (>lo0 mg L-I). Manganese retention in peat was small compared with that of Fe, and Mn was retained in peat almost exclusively as exchangeable Mn2+. Retention oPFe2+ in peat was not affected by the presence of Mn2+ in AMD. Iron oxides that had accumulated in peat subjected to AMD were not readily resolubilized by any of three processes investigated: photoreduction, microbial Fe(II1) reduction under reducing conditions, and exposure to simulated acid precipitation. These findings suggest that constructed wetlands may be an appropriate technology to remove Fe from AMD with low soluble Fe concentration, but are inadequate for treating drainage waters rich in soluble Mn. CIDIC drainage from active and abandoned coal A mining operations is formed when sulfide-bearing minerals (principally pyrite) associated with coal and underlying bedrock are exposed to air and oxidized by chemical and microbiological processes, generating H+ and soluble species of S (SO:-) and Fe (Fez+).

This study quantifies the prevalence of a rarely documented occurrence of bryozoans encrusting fossil brachyuran crabs. Over 500 crab fossils were examined from the reef facies of the Rákos Limestone Member of the Leitha Limestone Formation in the quarry at Diósd, Hungary. They were deposited in the upper part of the regional Badenian stage (i.e., lower part of the international Serravallian stage) of the middle Miocene. Nine bryozoan colonies were found encrusting five dorsal carapaces of three different crab species: Panopeus wronai, Dromia neogenica, and Cancer styriacus. The bryozoans were restricted to the exterior surface of the preserved carapaces of the host crabs, so the epibiosis was most likely syn-vivo. The prevalence was calculated at 1%. The bryozoans were all cheilostome gymnolaemates identified as a cribrilinid, a calloporid, Onychocella? sp., and two indeterminate membraniporiform species. The low prevalence of bryozoan-encrusted crabs is consistent with other fossil-based bryozoan-crab studies but much lower than similar studies in today's faunas. This discrepancy was attributed to both colony spalling-induced preservational bias and differences in carapace size. The bryozoan-crab symbiosis was described as phoretic hitchhiking.

222 high-quality Landsat satellite images were used in this study to extract the instantaneous shoreline positions on 22 sections of the northern Yellow River delta. Based on the instantaneous water line position data, a new statistical method for studying annual shoreline change was proposed. The annual shoreline movement of the northern Yellow River delta after the latest deltaic course shift in 1976 was obtained. The results showed that the shoreline on northern Yellow River delta was mostly undergoing a retreat back process since 1976 due to the river course shift, relative sea level change, regional marine hydrodynamic forces and the local engineering constructions. The influence of the Yellow River deltaic course shift in 1976 on the shoreline change mainly occurred in the first 20 years in 1976-1996 after the course shift, and was mostly limited within 10 km range around the abandoned Diaokou river mouth. The coastal engineering constructions caused decrease of the erosion area by 61 km 2 , or 31% of the total erosion area. Most of the northern Yellow River delta was relatively insensitive to the relative sea level change except for the coast around sections S10 and S11; The annual shoreline movement due to the relative sea level change along most of the coast was only 1 -3% of the actual annual shoreline movement;the total erosion area due to the relative sea level change was 9 km 2 , or 5% of the actual erosion area. The coast erosion in the northern Yellow River delta was mainly influenced by the regional marine hydrodynamic forces, which gradually increase from west to east, resulting in gradually eastward increase of annual shoreline movement and slope steepness of the coast.

In this article, I analysed the biogeographical distribution and the historical origin of freshwater fish of the Ethiopian Rift Valley (ERV) region which is not a homogeneous area. The Ethiopian region, including Eritrea and part of Somalia, includes 13 basins as geographical units. A comparison was carried out with four Near East geographical units. A correspondence analysis was applied to presence-absence data for the 17 basins 9 170 species' matrix. Then, a faunistic distance (Euclidian distance) between basins was computed from the coordinates of factors retained in this new analysis. From this faunistic distance, a hierarchical cluster analysis was performed and a dendrogram produced by a UGPMA classification. The old Abyssinian ichthyo-province (sensu Roberts, Zool J Linn Soc 57: 1975) was not homogeneous in species composition. I distinguished four main groups based on the present species composition which seemed to be mainly influenced by historical events. The species composition of the ERV basins was not randomly distributed and can be classified into four main geographical units. The importance of the historical events was demonstrated and two origins can be considered. The westernmost basins are under Nilo-Sudan influence whereas the easternmost ones seem to have been colonised from the Near East. In this Eastern part it can be distinguished three different groups: the main ERV province and two derived subregions, Lake Tana with a Labeobarbus intermedius related species flock and the Coastal Red Sea, characterised by a very impoverished freshwater fish fauna.

The precise number of extant fish species remains to be determined. About 28,900 species were listed in FishBase in 2005, but some experts feel that the final total may be considerably higher. Freshwater fishes comprise until now almost 13,000 species (and 2,513 genera) (including only freshwater and strictly peripheral species), or about 15,000 if all species occurring from fresh to brackishwaters are included. Noteworthy is the fact that the estimated 13,000 strictly freshwater fish

Triple oxygen isotope (δ17O and δ18O) values of high- and low-temperature altered oceanic crust and products of basalt alteration experiments were measured to better constrain ocean isotope compositions in deep time. The data define an array of δ18O and Δ′17O (Δ′17O=δ′17O − λRL × δ′18O + γ) values from mantle values toward 1‰ and −0.01‰, respectively, with a λ of ~0.523. The altered oceanic crust data were used to construct a model for estimating δ18O-Δ′17O values of the ancient oceans if the continental weathering flux (FCW) and/or hydrothermal oceanic crust alteration flux (FHT) changed through time. A maximum lowering of 7‰ and 4‰, respectively, is achieved in the most extreme cases. The δ18O value of the ocean cannot be raised by more than 1.1‰. Eclogites from the Roberts Victor kimberlite (South Africa), with a protolith age of 3.1 Ga, have δ18O-Δ′17O values that precisely overlap with those of the modern altered oceanic crust, suggesting that the Archean oceans had similar iso...

Large igneous province (LIP) eruptions are increasingly considered to have driven mass extinction events throughout the Phanerozoic; however, uncertainties in radiometric age dating of LIP materials, along with difficulty in accurate age dating of sedimentary rocks that record the environmental and biological history of our planet, create inherent uncertainties in any linkage. As such, there is interest in using geochemical proxies to fingerprint periods of major volcanism in the sedimentary record (termed here LIP marks). The use of sedimentary mercury (Hg) contents has been suggested to be the best tool to accomplish this goal, and recent work is reviewed here. Studies to-date show that most extinction events, ocean anoxic events, and other environmental crises through the Phanerozoic have an associated sedimentary Hg anomaly. It remains unclear though if each Hg anomaly is truly a signature of massive volcanism, or if it is controlled by local or regional processes. As Hg has a strong affinity to organic matter (OM), normalisation with total organic carbon (TOC) has been used to assess anomalies. The measurement of TOC has been fraught with error throughout many studies, leaving some claimed Hg/TOC anomalies questionable. Normalisation by other elements that can affect Hg sequestration, such as Al and S, are less common but warrant further investigation. Stable isotope systematics of Hg have helped to further clarify the origin of Hg spikes, and clearly show that not all Hg anomalies are

Marine primary production is dominated by diatoms and these are dependent upon the riverine delivery of silicon (Si) to the ocean. In paleoreconstruction of silicic acid utilisation by diatoms, it is assumed that the isotopic composition of the Si that is delivered from the continent to the oceans remains constant. In this study it is shown that glacier-fed Icelandic rivers differ from those directly draining basaltic catchments in their dissolved Si isotope compositions. Lighter values (δ 30 Si¼+0.1770.18‰) are associated with the high physical erosion rates in glacial rivers, and heavier values (δ 30 Si¼ +0.9770.31‰) are associated with lower physical erosion rates and enhanced formation of secondary minerals in direct runoff rivers. The Si isotopic compositions correlate with those of Li and provide evidence of a climatic dependence that is likely to have led to glacial-interglacial differences. Based on existing δ 30 Si measurements from diatoms in a sediment record from the Southern Ocean, the interpretation of changes in Si utilisation between the Last Glacial Maximum (LGM) and the early Holocene is revisited taking into account changing isotopic compositions of the river water delivered to the ocean over glacial-interglacial intervals. During the LGM, Si utilisation values are higher when allowing for changing Si isotope input to the ocean (5975%), than when a constant Si isotope input is assumed (42-4775%). This reduces but does not eliminate the difference relative to the Holocene (8875%). Therefore, changes in Si isotope delivery to the ocean need to be taken into account in the precise reconstruction of ocean Si utilisation and primary productivity over glacial-interglacial timescales.

Diatom productivity in the oceans plays a crucial role in the carbon cycle, but is strongly dependent upon the continental silicon supply. However, the relative influence of weathering and biological processes on continental Si fluxes remains poorly constrained. This study aims to quantify the impact of terrestrial diatom productivity on Si fluxes to the ocean. Lake Myvatn in North Iceland is one of the most productive lakes in the Northern Hemisphere, with nutrient-rich waters almost uniquely sourced by groundwater. The primary production is mainly controlled by diatom growth but also by cyanobacteria, and the lake output is via a single river, thereby providing a relatively simple natural laboratory to quantify the impact of diatom growth on the chemistry and Si budget of lake waters. Silicon stable isotopes (δ 30 Si) provide a tracer of this biocycling, and have been measured in groundwater inputs to the lake, and in time-series monitoring of waters at the lake outlet. The δ 30 Si values at the outlet range from + 0.70 ± 0.08 to + 1.42 ± 0.06‰, which is significantly heavier than the groundwater input (average cold and hot springs: + 0.50 ± 0.17‰, 2SD) and consistent with the preferential uptake of light Si isotopes by diatoms. The δ 30 Si value at the outlet increases by up to 0.9‰ in spring and autumn relative to the Si isotope composition of the inflow. These seasonal diatom blooms can be modeled by an open system of Si uptake and affect Si fluxes at the outlet of the lake by up to 79%, or 53% integrated over the year. In the summer a shift to lighter δ 30 Si values is correlated with a higher pH, which results in dissolution of diatoms releasing light Si isotopes. From mass balance, this seasonal diatom dissolution affects Si fluxes by up to 33%, but is limited to 3.7% integrated over the year. These results clearly illustrate that biological activity can have a significant impact on both isotope composition and elemental abundance of continental derived Si. They also demonstrate the pH dependency of diatom dissolution and/or preservation, which is likely to affect not only the continental Si fluxes to the ocean but also the Si recycling in the oceans themselves.

The relative importance of biological and physical processes within the Southern Ocean for the storage of carbon and atmospheric pCO 2 on glacial-interglacial timescales remains uncertain. Understanding the impact of surface biological production on carbon export in the past relies on the reconstruction of the nutrient supply from upwelling deep-waters. In particular, the upwelling of silicic acid (Si(OH) 4 ) is tightly coupled to carbon export in the Southern Ocean via diatom productivity. Here, we address how changes in deep-water Si(OH) 4 concentrations can be reconstructed using the silicon isotopic composition of deep-sea sponges. We report δ 30 Si of modern deep-sea sponge spicules and show that they reflect seawater Si(OH) 4 concentration. The fractionation factor of sponge δ 30 Si compared to seawater δ 30 Si shows a positive relationship with Si(OH) 4 , which may be a growth rate effect. Application of this proxy in two down-core records from the Scotia Sea reveals that Si(OH) 4 concentrations in the deep Southern Ocean during the Last Glacial Maximum (LGM) were no different than today. Our result does not support a coupling of carbon and nutrient build up in an isolated deep-ocean reservoir during the LGM. Our data, combined with records of stable isotopes from diatoms, are only consistent with enhanced LGM Southern Ocean nutrient utilization if there was also a concurrent reduction in diatom silicification or a shift from siliceous to organicwalled phytoplankton.

The distribution of silicon in the North Pacific is controlled by the utilization of silicic acid by diatoms, a process that fractionates silicon (Si) isotopic compositions. Silicon isotope variations are presented for six water column profiles from the surface mixed layer down to the deep waters of the North Pacific Ocean. Although the observed Si isotopic variations display an apparently simple inverse relationship with dissolved nutrient concentrations, in fact they reflect mixing of surface waters undergoing active Si isotope fractionation and deep-waters with more uniform concentrations and isotope compositions. Samples from the surface of the subtropical gyre have the lowest dissolved Si concentrations and heaviest Si isotope compositions of marine waters measured thus far. Fractionation in the surface waters follows a typical Rayleigh-type distillation curve for a 'closed' surface water reservoir resulting from stratification of the surface layer in the subarctic region. In contrast, an 'open' system prevails within the subtropical gyre where there is significant recycling of silicic acid in the upper water column and lateral transport of silicon within surface currents. For deep waters, the Si isotope composition distinguishes between the northern North Pacific Deep Water (NPDW) and the southerly-derived bottom water. The relatively light Si isotope compositions measured from waters within the subarctic gyre provides evidence for isolation of the nutrient pool in the North Pacific.

The riverine flux of U that enters the deep oceans is not well constrained since the net losses during estuarine mixing are difficult to quantify. Riverine-dissolved U normally has a higher 234 U/ 238 U activity ratio ( 234 U/ 238 U ar ) than the uniform value that characterizes open ocean seawater and could be used as a tracer of riverine inputs if one could resolve subtle variations in seawater composition. Using new mass spectrometry techniques we achieve a long-term reproducibility ±0.3‰ on 234 U/ 238 U ar which permits the tracing of riverine U in seawater samples from the Arctica partially restricted basin that is ideal for such a study. We find that surface waters from the Arctic basins carry elevated 234 U/ 238 U ar when compared with deep ocean seawater. Samples from the Canada Basin have a significant freshwater component and provide evidence that the Mackenzie River loses ∼ 65% of its U in the Mackenzie shelf/estuary zone before entering the deeper basin. This is in contrast to samples from the Makarov Basin, which provide evidence that all of the freshwater input is derived from the major Yenisey River alone, despite the proximity of the Lena and Ob Rivers. The differing behaviour of U between the Mackenzie and Yenisey Rivers is most likely a consequence of the strong binding of U to dissolved organic matter (DOC) or secondary phases in these rivers. The Yenisey River appears to transport the majority of the DOC through the shelf and into the Makarov Basin. In contrast, the Mackenzie River appears to lose a significant amount of DOC (N 50%) in the estuary/shelf zone, which may lead to loss of associated U. These findings offer a more detailed picture of the fresh riverine water flow patterns in the Arctic Ocean when compared to other geochemical proxies. The non-conservative behaviour of U in the Mackenzie River through the shelf/estuaries has important implications for U input into oceans and the total marine budget.

This study presents silicon isotope data for rivers and groundwater from the Bengal Basin. Variations of Si isotope ratios were analyzed by means of high-resolution MC-ICP-MS using a NuPlasma HR. The rivers show typical positive δ 30 Si values between 1.3 and 1.7‰, whereas the groundwater samples show decreasing δ 30 Si values from 1.3‰ in shallow groundwater to -0.2‰ in the deeper groundwater. Beside a very distinctive isotope composition, the concentration of dissolved Si in these groundwater samples is 2-3 times higher than in river samples taken during dry season. The resulting Si flux by groundwater (9.3 × 10 10 mol yr -1 ) is on the order of the combined Ganges-Brahmaputra Si fluxes, and equals 40% of the total (river + groundwater) annual Si flux into the Bay of Bengal. Given the significant large flux and distinctive isotope composition means that the overall isotopic input into the ocean is different from riverine values. However, a sound knowledge of all inputs into the ocean and of how these inputs might vary throughout time is mandatory, in order to correctly interpret palaeo-records of δ 30 Si variations as recorded in sedimentary diatom opal from the last glacial maximum. We extrapolate our results from the Bengal Basin onto a global scale and assess the ocean's sensitivity to changes in inputs, as triggered by large-scale events, such as glaciation periods, where the hydrological cycle might be out of steady state due to the build-up of large continental ice-shields. In such a glaciation scenario, riverine vs. groundwater inputs can be shifted, favoring isotopically lighter groundwater over heavier river inputs into the ocean. The model proves impossible to change the biogenic output to a significant degree, on time scales of a few thousand years, by just changing the isotope inputs into the ocean.

It has been proposed that silicon (Si) isotopes are fractionated during weathering and biological activity leading to heavy dissolved riverine compositions. In this study, the first seasonal variations of stable isotope compositions of dissolved riverine Si are reported and compared with concomitant changes in water chemistry. Four different rivers in Switzerland were sampled between March 2004 and July 2005. The unique high-resolution multi-collector ICP-MS Nu1700, has been used to provide simultaneous interference-free measurements of 28 Si, 29 Si and 30 Si abundances with an average limiting precision of ± 0.04‰ on δ 30 Si. This precision facilitates the clarification of small temporal variations in isotope composition. The average of all the data for the 40 samples is δ 30 Si = + 0.84 ± 0.19‰ (± 1σ SD ). Despite significant differences in catchment lithologies, biomass, climate, total dissolved solids and weathering fluxes the averaged isotopic composition of dissolved Si in each river is strikingly similar with means of + 0.70 ± 0.12‰ for the Birs,+0.95 ± 0.22‰ for the Saane,+ 0.93 ± 0.12‰ for the Ticino and + 0.79 ± 0.19‰ for the Verzasca. However, the δ 30 Si undergoes seasonal variations of up to 0.6‰. Comparisons between δ 30 Si and physico-chemical parameters, such as the concentration of dissolved Si and other cations, the discharge of the rivers, and the resulting weathering fluxes, permits an understanding of the processes that control the Si budget and the fate of dissolved Si within these rivers. The main mechanism controlling the Si isotope composition of the mountainous Verzasca River appears to be a two component mixing between the seepage of soil/ground waters, with heavier Si produced by clay formation and superficial runoff associated with lighter Si during high discharge events. A biologically-mediated fractionation can be excluded in this particular river system. The other rivers display increasing complexity with increases in the proportion of forested and cultivated landscapes as well as carbonate rocks in the catchment. In these instances it is impossible to resolve the extent of the isotopic fractionation and contributed flux of Si contributed by biological processes as opposed to abiotic weathering. The presence of seasonal variations in Si isotope composition in mountainous rivers provides evidence that extreme changes in climate affect the overall composition of dissolved Si delivered to the oceans. The oceanic Si isotope composition is very sensitive to even small changes in the riverine Si isotope composition and this parameter appears to be more critical than

Cycling of deepwater silicon (Si) within the Southern Ocean, and its transport into other ocean basins, may be an important player in the uptake of atmospheric carbon, and global climate. Recent work has shown that the Si isotope (denoted by δ29Si or δ30Si) composition of deep sea sponges reflects the availability of dissolved Si during growth, and is a potential proxy for past deep and intermediate water silicic acid concentrations. As with any geochemical tool, it is essential to ensure analytical precision and accuracy, and consistency between methodologies and laboratories. Analytical bias may exist between laboratories, and sponge material may have matrix effects leading to offsets between samples and standards. Here, we report an interlaboratory evaluation of Si isotopes in Antarctic and sub-Antarctic sponges. We review independent methods for measuring Si isotopes in sponge spicules. Our results show that separate subsamples of non-homogenized sponges measured by three method...

Facies and biostratigraphic analyses of the Contrada Diesi succession, cropping out along the northern slope of Mt. Magaggiaro (Sciacca, SW Sicily), provided new data on the Middle Jurassic-Early Cretaceous pelagic sedimentation in the Saccense domain. The richness in ammonites allowed the identification of Bathonian-Kimmeridgian Biozones and Subzones, while the Tithonian-Valanginian interval was defined mainly by calpionellids and calcareous nannofossils. Facies and microbiofacies analyses of the Jurassic-Cretaceous pelagic sediments of the area, together with ammonite, calpionellid and calcareous nannofossil integrated biostratigraphy, were very effective tools for comparison of biostratigraphic events. Many gaps in sedimentation were recognized, the most important spanning the middle and late Berriasian and part of the early Berriasian. The Contrada Diesi succession provides new litho-biostratigraphic data on the Saccense Domain. It suggests a high degree of internal variability ...

Theory and seaborne measurements are presented for the near infrared (NIR: 700-900 nm) water-leaving reflectance in turbid waters. According to theory, the shape of the NIR spectrum is determined largely by pure water absorption and is thus almost invariant. A ''similarity'' NIR reflectance spectrum is defined by normalization at 780 nm. This spectrum is calculated from seaborne reflectance measurements and is compared with that derived from laboratory water absorption measurements. Factors influencing the shape of the similarity spectrum are analyzed theoretically and by radiative transfer simulations. These simulations show that the similarity spectrum is valid for waters ranging from moderately turbid (e.g., water-leaving reflectance at 780 nm of order 10 Ϫ4 or total suspended matter concentration of order 0.3 g m Ϫ3 ) to extremely turbid (e.g., reflectance at 780 nm of order 10 Ϫ1 or total suspended matter of order 200 g m Ϫ3 ). Measurement uncertainties are analyzed, and the air-sea interface correction is shown to be critical for low reflectances. Applications of the NIR similarity spectrum to atmospheric correction of ocean color data and to the quality control of seaborne, airborne, and spaceborne reflectance measurements in turbid waters are outlined.

ABSTRACTThe Middle Jurassic is a poorly sampled time interval for non-pelagic neosuchian crocodyliforms, which obscures our understanding of the origin and early evolution of major clades. Here we report a lower jaw from the Middle Jurassic (Bathonian) Duntulm Formation of the Isle of Skye, Scotland, UK, which consists of an isolated and incomplete left dentary and part of the splenial. Morphologically, the Skye specimen closely resembles the Cretaceous neosuchiansPachycheilosuchusandPietraroiasuchus, in having a proportionally short mandibular symphysis, shallow dentary alveoli and inferred weakly heterodont dentition. It differs from other crocodyliforms in that the Meckelian canal is dorsoventrally expanded posterior to the mandibular symphysis and drastically constricted at the 7th alveolus. The new specimen, together with the presence ofTheriosuchussp. from the Valtos Formation and indeterminate neosuchians from the Kilmaluag Formation, indicates the presence of a previously un...