Ratios Of Shells Research Articles

Benthic foraminifera as indicators of recent mixed turbidite-contourite sediment transport system in the Eastern Mediterranean upper continental slope, offshore Israel

Nile derived siliciclastic sediments are the main source of sedimentation along the Levant continental margins of the Mediterranean Sea. These sediments are transported along the southeastern Mediterranean coast via well-documented longshore currents, mainly operating along the shelf. However, the cross shelf component of sediment transport, responsible for conveying sediments toward the upper slope, is less known. To better understand the cross-shelf vs. the longshore component of sediment transport we studied a ~6 m long piston core (DOR280) sampled on the upper continental slope (280 m water depth) and analyzed benthic foraminiferal assemblages and their shell taphonomy alongside the particle size distribution and mineralogy of bulk sediments, to document both the source and the transport mechanism of those upper continental-slope sediments. The radiocarbon dating at the core-base is ~650 Cal. Yrs BP, indicating an exceptionally high average sedimentation rate of ~800 cm/kyr.DOR280 consists of two alternating distinct sedimentary facies: (1) laminated (L) intervals up to ~40 cm thick each and showing a high ratio of allochthonous vs. autochthonous (allo/auto) benthic foraminiferal species and a high percentage of broken shells, indicating contribution of transported sediments originating from mid-shelf habitats; (2) non-laminated (NL) intervals up to ~200 cm thick each and showing a low allo/auto ratio and low percentages of broken shells, indicating mostly in-situ hemipelagic deposition. The L intervals are interpreted here as turbidites. The sedimentation rates calculated only for the NL intervals are still exceptionally high, thus excluding hemipelagic sedimentation as the sole mechanism for the NL deposition. Therefore, a contour bottom current transported component is suggested here as a source of the NL sedimentation.We conclude that a mixed contourite-turbidite system actively prevails along the upper continental slope of the Levant coast, offshore Israel. The mid-shelf to upper slope sediment transport is nearly continuous and presents occasional turbidite events of average decadal reoccurrence time.

Using neodymium isotope ratio in Ruditapes philippinarum shells for tracking the geographical origin

Geographical traceability of marine bivalves is becoming increasingly important to assure their quality and to defend the interest of consumers and producers. This study verifies the neodymium isotopic ratio (143Nd/144Nd) in Ruditapes philippinarum shells as a tracer of the geographic origin, based on the geochemical aspect that 143Nd/144Nd of their habitats strongly depends on the geology of its catchment areas. The 143Nd/144Nd ratios of clam shells from the Japanese and Chinese coastal areas displayed a heterogeneous pattern from local to international scales, reflecting the geological age of the catchment area. The blind test suggested that a part of Manila clam was sold with mislabeling in the Japanese market, demonstrating the high potential of 143Nd/144Nd to unmask the fraud labeling in a food market. Our findings emphasize the potential of 143Nd/144Nd as a tracer for the geographical origin of marine bivalves, and also as a strong deterrent against mislabeling.

Subsonic and supersonic flow-induced vibration of sandwich cylindrical shells with FG-CNT reinforced composite face sheets and metal foam core

Based on the linear fluid-solid interaction (FSI) model and classical shell theories, vibration behavior of sandwich cylindrical shells subjected to external incompressible or compressible fluid flow is investigated. The sandwich shell includes the same outer and inner face sheets made of carbon nanotube (CNT) reinforced composites and a metal foam core. The effective mechanical properties of CNT reinforced composites are obtained using the extended rule of mixture. Also, the porosity distribution through the foam thickness is assumed to be in the form of a trigonometric function. Equations of motion and corresponding boundary conditions are derived according to the Donnell's, Love's and Sanders’ theories. For the first time, a closed-form expression of three-dimensional pressure distribution in both subsonic and supersonic regimes of compressible flow passing along the length of shell is presented by studying conservation of mass, generalized Bernoulli equation and linear fluid-solid interaction. The governing equations are exactly and analytically solved to develop natural frequencies and mode shapes of fluid-loaded sandwich shells with various boundary conditions using the state-space and Galerkin's methods. So the validity and accuracy of the Galerkin's method in conjunction with beam modal functions for different boundary conditions are investigated. In addition, a closed-form expression is obtained for critical upstream speed of water flow at which the dynamic instability of sandwich shells occurs. Findings indicate the frequency ratio (fWet/fDry) of air-loaded sandwich shells decreases slightly with upstream speed in the subsonic regime, while a significant increase is seen in the supersonic regime (more than 20%). Also, the effect of flow specifications on the natural frequency and critical speed are much more pronounced for larger values of aspect (L/R) and wall slenderness (R/h) ratios. It is shown that Love's shell theory is accurate enough for vibration analysis of flow-induced sandwich cylindrical shells with different geometric ratios and boundary conditions and the sanders’ terms can be neglected.

Last glacial temperature reconstructions using coupled isotopic analyses of fossil snails and stalagmites from archaeological caves in Okinawa, Japan

We applied a new geoarchaeological method with two carbonate archives, which are fossil snails from Sakitari Cave and stalagmites from Gyokusen Cave, on Okinawa Island, Japan, to reconstruct surface air temperature changes over the northwestern Pacific since the last glacial period. Oxygen isotope ratios (δ18O) of modern and fossil freshwater snail shells were determined to infer seasonal temperature variations. The observational and analytical data confirm that δ18O values of fluid inclusion waters in the stalagmite can be regarded as those of spring waters at the sites where snails lived. Our results indicate that the annual mean, summer, and winter air temperatures were lower by 6–7 °C at ca. 23 thousand years ago (ka) and 4–5 °C at ca. 16–13 ka than those of the present day. Our reconstruction implies that surface air cooling was possibly two times greater than that of seawater around the Ryukyu Islands during the Last Glacial Maximum, which potentially enhanced the development of the East Asian summer monsoon during the last deglaciation. Considering the potential uncertainties in the temperature estimations, the climatic interpretations of this study are not necessarily definitive due to the limited number of samples. Nevertheless, our new geoarchaeological approach using coupled δ18O determinations of fossil snails and stalagmite fluid inclusion waters will be useful for reconstructing snapshots of seasonally resolved time series of air temperatures during the Quaternary.

Key particle properties of shells for cadmium chemisorption

Previous studies on cadmium adsorption of calcium carbonate have found that polymorph, and, crystallinity are influential factors for adsorbing cadmium ions. The predominant factor for cadmium adsorption has yet to be elucidated because these factors are linked. To overcome this, here each factor is investigated separately. First, atmospheric grinding prepared surf clam (aragonite phase) and scallop (calcite phase) shells with similar crystallite sizes and specific surface areas. Using adsorption isotherm models, kinetics, X-ray diffraction analysis, and TEM observations, both calcite and aragonite react with cadmium to form cadmium carbonate. The chemisorption follows the adsorption mechanism reported in the literature. Based on the Langmuir isotherm model fitting, the maximum adsorbed amount for the ground surf clam shells is 633.3 mg/g, while that for scallop shells is 195.8 mg/g. Then fine surf clam shell particles with a similar specific surface area, and with a relatively wide range of the aragonite ratio, and crystallite size are prepared via a combination of grinding and a subsequent calcination process. Our experiments where one explanatory variable is changed at a time demonstrate that the polymorph ratio and crystallite size of the ground shells play key roles in the chemisorption.

Behavior of Offshore Pile in Calcareous Sand—Case Study

The erosion of limestone and calcarenite ridges that existed parallel to the Mediterranean shoreline forms the calcareous sand (CS) formation at the surface layer of Egypt’s northern coast. The CS is often combined with broken shells which are considered geotechnically problematic due to their possible crushability and relatively high compressibility. In this research, CS samples collected from a site along the northern coast of Egypt are studied to better understand its behavior under normal and shear stresses. Reconstituted CS specimens with different ratios of broken shells (BS) are also investigated to study the effect of BS ratios on the soil mixture strength behavior. The strength is evaluated using laboratory direct-shear and one-dimensional compression tests (oedometer test). The CS specimens are not exposed to significant crushability even under relatively high-stress levels. In addition, a 3D finite element analysis (FEA) is presented in this paper to study the degradation offshore pile capacity in CS having different percentages of BS. The stress–strain results using oedometer tests are compared with a numerical model, and it gave identical matching for most cases. The effects of pile diameter and embedment depth parameters are then studied for the case study on the northern coast. Three different mixing ratios of CS and BS have been used, CS + 10% BS, CS + 30% BS, and CS + 50% BS, which resulted in a decrease of the ultimate vertical compression pile load capacity by 8.8%, 15%, and 16%, respectively.

Optimization of wet flue gas desulfurization system using recycled waste oyster shell as high-grade limestone substitutes

Wet flue gas desulfurization, which is performed in many thermal power plants, has a high desulfurization efficiency and produces desulfurized gypsum as a by-product. Currently, high-grade limestone with a CaCO3 content of 94 wt% or more is used to produce desulfurized gypsum with a purity of 93 wt% or more. However, high-grade limestone resources are depleting, so new substitutes to this are required. The objective of this work is to optimize the wet flue gas desulfurization system using recycled waste oyster shells as high-grade limestone substitutes. The process model was developed for predicting the optimal blending ratio of waste oyster shells to limestone with constraints of desulfurization efficiency and purity of desulfurized gypsum. A mathematical model was addressed for optimized process costs, which was a nonlinear programming problem that minimizes the total annualized cost (TAC) by considering the total product cost (TPC) and equivalent annual cost; these vary according to the blending ratio. The optimal blending ratio of waste oyster shells is 16.160 wt% or 599.536 kg/h, TPC and TAC are reduced by $ 840,721 and $ 760,543, respectively. The waste oyster shell can be utilized 4,901 t/y, which is about 20.66 wt% of the total landfilled waste oyster shell. The results of this study suggest waste oyster shells, which pose landfill and odor problems, can be used as excellent substitutes for high-grade limestone for high economic and environmental benefits.

An evaluation of cleaning methods, preservation and specimen stages on trace elements in modern shallow marine ostracod shells of Sinocytheridea impressa and their implications as proxies

Trace elements of marine shells are important tools for reconstructing past ocean conditions, which are usually obtained through empirical calibrations with ocean parameters. For example, Mg/Ca ratios of ostracod shells have been linked to ocean temperature. However, some uncertainties usually arise from extraneous impacts, such as the selection of cleaning methods, specimen ontogenetic stage and shell preservation. Here, we present an evaluation of trace elements (Ca, Mg, Sr, Na, Al and Fe) in a shallow marine ostracod, Sinocytheridea impressa, and their potential utility as paleoceanographic proxies. We investigated single-shell variability of trace-element-to‑calcium ratios through Inductively Couple Plasma Mass Spectrometry (ICP-MS). In addition, the internal distribution of trace-elements was studied by Electron Probe Micro Analysis (EPMA) and Flow-Through Time-Resolved Analysis (FT-TRA). We conducted these analyses on ostracod specimens of different life stages and preservation conditions, subject to different cleaning methods, to resolve the suitability of this species as a new paleoenvironmental archive. Based on cleaning tests, we observe that clays stuck to the shells are the major contaminants in our specimens. We report an optimal cleaning procedure using sodium hypochlorite, which reduced the adherence of clays to the organism without significantly dissolving adult and juvenile calcite. We additionally find that the internal Mg distribution of S. impressa specimens is different for adults and the oldest stage of juveniles, namely A-1, with only the former having an enriched inner Mg layer. Therefore, precautions should be taken when combining life stages for trace-element analysis. While Sr and Mn are found to be mostly homogenous throughout all shells, the distribution of Na was found to be heterogeneous, which suggests that the incorporation of Na is controlled by a different mechanism than Mg, Sr and Mn. Finally, we report that transparent and opaque shells show similar Mg/Ca, Sr/Ca and Na/Ca ratios, unlike Mn/Ca and Fe/Ca, which suggests that opaque shells result from Mn- and Fe-enriched porewaters and Mn-enriched waters from the Pearl River. Our combined analysis suggests that Mg, Sr and Mn of adult S. impressa are incorporated into the carbonate matrix during calcification, and may therefore be suitable proxies of important environmental variables such as temperature and aqueous elemental concentrations.

Elemental concentrations of waters and bivalves in the fresh to hypersaline Coorong Lagoons, South Australia: Implications for palaeoenvironmental studies

Element-to-calcium ratios of bivalve shells are potentially useful proxies for environmental change, provided the relationship between the environmental variable and element ratio are calibrated using modern specimens. In this study we investigate the utility of trace elemental ratios in the estuarine micromollusc Arthritica helmsi as (palaeo)environmental proxies. Sr/Ca, Mg/Ca and Ba/Ca ratios were measured in waters (n = 137) and live bivalves (n = 125) were collected along a salinity gradient from fresh to hypersaline in the Coorong Lagoon and Lake Alexandrina, at the terminus of the Murray River, South Australia. Water Mg, Sr and Ca exhibited linear relationships with salinity, while Ba showed no relationship. Mg/Ca and Sr/Ca in water both showed positive logarithmic responses to increasing salinity, while the response of Ba/Ca was best explained by a negative power function. The Sr concentration and Sr/Ca of water collected between 2016 and 2018 were elevated compared to a previous study conducted between 2007 and 2008, possibly due to a higher river flow regime in the more recent period. The range of Sr/Ca, Mg/Ca and Ba/Ca measured in A. helmsi were in agreement with previous studies, as were the range of partition coefficients. However, the incorporation of Sr/Ca, Mg/Ca and Ba/Ca did not correlate with water elemental ratios, temperature, salinity or pH and are therefore likely to be more heavily influenced by biological processes. As a consequence, while the elemental composition of other carbonate fossils within the Coorong system may hold potential to reconstruct past climate and environmental change, the trace element geochemistry of A. helmsi aragonite shells, and possibly other similar micro-bivalve molluscs, should be treated with caution as a palaeoenvironmental tracer.

Calibration of Mg ∕ Ca and Sr ∕ Ca in coastal marine ostracods as a proxy for temperature

Abstract. The Mg/Ca and Sr/Ca ratios of marine shells have been widely used in environmental paleoreconstructions to understand past marine conditions. Temperature calibrations to ostracod Mg/Ca ratios are known to be species-specific but only available for a few species, despite the large number of known ostracod species. Here, we develop temperature calibrations for two shallow marine ostracods, Sinocytheridea impressa and Neomonoceratina delicata, using modern sediment samples. Our results show that adult specimens of these two species might be useful as a paleothermometer. We observed significant correlations using the Mg/Ca ratios of both species to the annual (Mg/CaS. impressa=3.7 ⋅ T−62.7; Mg/CaN. delicata=1.6 ⋅ T−16.8) and April (Mg/CaS. impressa=2.8 ⋅ T−39.2; Mg/CaN. delicata=1.6 ⋅ T−15.7) temperatures. The correlation of temperature to the Mg/Ca ratio of S. impressa is more significant and therefore should be preferred for paleoreconstructions. Re-analysis from satellite data allows us to validate our temperature calibration to an extended area around the Pearl River estuary. Our results show that Mg/Ca of S. impressa and N. delicata ostracods can be used to reconstruct water temperature at a regional scale, which provides information on the oceanic circulation in coastal areas of the South China Sea. Sr/Ca ratios of both species do not correlate with any of the 24 water parameters recorded by the Environmental Protection Department of Hong Kong, including temperature (21.7–24.1 ∘C), salinity (23.8–33.7 PSU), dissolved oxygen (4.3–7.1 mg L−1), suspended solids (1.9–35.4 mg L−1) and pH (7.7–8.2).

Performance and mechanism of a biochar-based Ca-La composite for the adsorption of phosphate from water

In this study, a calcium-modified biochar with a high dephosphorization efficiency was obtained using sheep manure as a carbon source and oyster shells as a calcium(Ca) source. However, it was found that the calcium-modified biochar had a low-pH inadaptability. Based on this, lanthanum(La) was doped in place of Ca to prepare biochar with a strong phosphate adsorption ability in a wide range of pH. The results showed that with the increase of Ca content, the phosphorus adsorption capacity of the material with a mass ratio of biochar to oyster shells of 1:1 (BC-Ca5) increased gradually, and the maximum adsorption capacity that was fitted by the Langmuir equation reached 78.11 mg P/g. Also, the adsorption capacity was 48.70 mg P/g when the pH > 7, and lower than 6 mg P/g when pH ≤ 7. The maximum adsorption capacity fitted to the Langmuir equation of the material with a mass ratio of biochar, oyster shells, and La of 1:1(BC-La4) reached 88.34 mg P/g, and the adsorption capacity reached 50 mg P/g under all pH conditions except pH = 7. Ca was mostly found on the surface of the biochar, and La was mainly present in the internal pore structure. The FTIR, XRD, and XPS results showed that the main adsorption mechanism was complexation. This study provides a reference for the resource utilization of livestock and poultry manure and shell solid wastes, as well as metal sources for metal modified biochar, and improving the adsorption performance of calcium-modified biochar.

Preparation and application of a novel biochar-supported red mud catalyst：Active sites and catalytic mechanism

A novel catalyst RM-BC(HP) was synthesized by hydrothermal treatment and pyrolysis (800 ℃) using red mud and coconut shells. Influence of different preparation conditions on catalyst performance was explored. SEM showed that RM-BC(HP) was porous and RM was successfully loaded on the outside surface and inside the pores of BC. XRD revealed that Fe2O3 in RM was reduced to Fe0 and Fe3O4 in the pyrolysis process, in which pyrolysis temperature and addition ratio of coconut shells were critical. TGA-MS, FT-IR and XPS were also applied to character the catalyst. 100% of AO7 was removed within 30 min with conditions of 2 mM PS, 50 mg/L AO7 and 0.5 g/L RM-BC(HP), and the Fe leaching was negligible. High removal rate was obtained in tap, river, and lake water. RM-BC(HP)/PS system also exhibited excellent degradation performance for other dyes (MB, MG and RhB) and antibiotics (TC, OTC and CTC). The mechanism studies demonstrated that PS was mainly activated by Fe0 and Fe2+ in RM-BC(HP) to produce different radicals, then 1O2 was generated by the reactions among these radicals to degrade AO7. Finally, nine intermediate products of AO7 were identified by FT-ICR-MS and a probable degradation pathway was proposed.

Paleoclimate of the Little Ice Age to the Present in the Kankakee Valley of Illinois and Indiana, USA Based on 18O/16O Isotope Ratios of Freshwater Shells

ABSTRACT The cooling associated with the Little Ice Age (LIA) had differential severity across the globe. Within the American Midwest, the local impacts of this cooling have not been established. Our purpose here is to determine its local effects and establish the impacts on the environment encountered at a seventeenth century Native American village in Illinois, USA. We obtained oxygen and carbon stable isotope ratios of freshwater mussel shells from this early seventeenth century site, occupied during one of the coldest periods of the LIA. These data were compared to the oxygen and carbon ratios of freshwater shells from a nineteenth century cabin as well as modern shells. Results demonstrate that shell stable oxygen isotopes capture environmental conditions at the three sites and suggest more arid conditions during the LIA and increased precipitation into the present. Findings also may capture the extensive alteration of the Kankakee region’s drainage between the late nineteenth and early twentieth centuries as well as contemporary global warming. Overall, this study illustrates the value of archaeological data to past and contemporary climate studies.

Shell sclerochronology and stable oxygen isotope ratios from the limpet Patella depressa Pennant, 1777: Implications for palaeoclimate reconstruction and archaeology in northern Spain

Stable oxygen isotope ratios of mollusc shells (δ18Oshell) offer the possibility to reconstruct coastal resource exploitation patterns and changes in the oceanographic conditions of direct relevance to past human populations. This method relies on the fact that shell carbonate is deposited by molluscs in equilibrium with their surrounding environment and actualistic investigation of modern specimens is needed to ensure that selected species can be used as accurate palaeoclimate indicators. The limpet Patella depressa Pennant, 1777 is one of the most common mollusc species found in Holocene archaeological assemblages along the Atlantic coast of Europe. However, this taxon has not, to date, been tested as a seawater palaeothermometer. Here, we explore the ability of P. depressa to be used as an environmental recorder in this littoral region, specifically in northern Iberia where we obtained live-collected specimens throughout the year. We undertook sclerochronological investigations combining observations of incremental shell growth patterns with δ18Oshell values. Carbonate samples were taken on (i) the ventral margins of shells collected alive year-round in order to test for isotopic equilibrium and (ii) along the axis of maximum shell growth of four modern specimens to decipher the shell growth pattern of this species. Isotopic data showed that calcium carbonate is precipitated in predictable isotopic disequilibrium with the ambient seawater (R2 = 0.95; p < 0.0001), reporting a consistent offset of +1.08‰. Some periods of growth cessation were observed in the shells when thermal tolerances were exceeded in winter and occasionally in summer. Nevertheless, estimated seawater temperatures from modern shell δ18Oshell values agreed closely with instrumentally measured temperatures (R2 = 0.88–0.93; p < 0.0001) and correctly reflected seasonal temperature patterns. As a result, multi-proxy analysis of P. depressa shells can provide a high-resolution palaeothermometer with significant implications for future palaeoclimate and archaeological studies along the Atlantic coast of Europe.

Seawater 87Sr/86Sr ratios along continental margins: Patterns and processes in open and restricted shelf domains

To better constrain the Sr isotope budget in marginal domains without any fluvial inputs, we analyzed the chemical composition and 87Sr/86Sr ratio of waters and shells from four locations: two coastal lagoons, one hemipelagic platform and one open marine shelf. Our results highlight homogeneous 87Sr/86Sr ratios typical of oligotrophic oceanic waters (OOW) (i.e., 0.709172 ± 0.000023) in the Pacific Tatakoto atoll and along a Mediterranean shore to offshore transect (~25 km off Banyuls-sur-Mer, BSM). This attests that oceanic inputs from oligotrophic areas remain the main Sr source in open shelf areas compared with submarine groundwater discharges (SGD) or particulate dissolution influences. In BSM, only foreshore data are more radiogenic, possibly due to rainwater mixing, local groundwater springs or more efficient particle dissolution in the intertidal zone. In restricted areas, we report variable 87Sr/86Sr ratios between the Salses-Leucate (France) and Oualidia (Morocco) lagoons. The first one has homogeneous 87Sr/86Sr ratio typical of OOW except close to SGD. In Oualidia, 87Sr/86Sr ratios decrease by 1.2 × 10−3 from OOW values close to the Atlantic inlet to progressively less radiogenic ones upstream within the interior of the lagoon. These differences depend on several factors including the leaky, restricted or choked morphology of lagoons modulating the oceanic Sr inputs, but also SGD fluxes whose 87Sr/86Sr ratios and Sr concentrations are highly variable according to the nature of rocks leached in karstic aquifer. In Oualidia, the low 87Sr/86Sr ratios correspond to high Sr concentrations (up to 150 μmol·l−1) issued from the dissolution of Mesozoic evaporites, leading to SGD fluxes accounting for 60% of the local Sr budget. Through data compilation, we show that similar 87Sr/86Sr gradients and processes prevail at the whole Mediterranean scale. Finally, we postulate that high coastal water retention times can also account for anomalous coastal 87Sr/86Sr ratios and that the combination of water mass restriction, SGD, bioadsorption and early diagenetic processes could decrease seawater Sr concentrations in some marginal areas.

High temperature stress does not distort the geochemical thermometers based on biogenic calcium carbonate: Stable oxygen isotope values and Sr/Ca ratios of gastropod shells in response to rearing temperature

Quantitative profiles of stable isotopes and trace elements in biogenic carbonates have received considerable attention for the purpose of reconstructing past temperatures. The relationships between temperature and the geochemical parameters of carbonates are often subject to both inter- and intraspecific variations, which critically impair the accuracy of temperature estimation. One of the issues that must be addressed to improve temperature estimation is enhancing our understanding of the influence of the kinetic effect. This effect matters because the purely thermodynamic effect to geochemical profiles cannot be effectively separated from the effect of temperature-driven calcification rate. Cowries (Mollusca, Gastropoda, Cypraeidae) may provide a good model system for quantitatively investigating these two effects, because they undergo a callus-building stage in which aragonitic shell formation exclusively occurs to monotonically increase the thickness outward. We reared a total of 230 juvenile individuals of Monetaria annulus under six constant thermal regimes, ranging from the minimum growing temperature (21 °C) to the maximum tolerated long-term temperature (34 °C). The portions of the shells built in the callus-building stage were analyzed to quantify isotopic and elemental compositions. Shell growth rate positively depended on temperature from 21 °C to 33 °C, but dramatically decreased at 34 °C, presumably because of high temperature stress. Nevertheless, the heat stress did not make any impact on the thermal dependences (and among-individual variabilities within the same temperature) of either δ18Oc or Sr/Ca. A linear relationship exists between temperature and the stable oxygen isotope value of the shells (δ18Oc) across the entire thermal range (n = 103), whereas the shell Sr/Ca ratio increased exponentially with increasing temperature (n = 227). These results strongly suggest that any chemical processes responsible for quantitative incorporation of 18O and Sr into aragonite crystals were not impacted by heat stress at temperatures up to 34 °C. Within-temperature residual correlations between shell growth rates and δ18Oc were weakly positive, which is compatible with a widely accepted hypothesis that carbonic anhydrase suppresses the kinetic effect in molluscs. Likewise, we found no association between shell growth rates and Sr/Ca, which rejected the possibility that faster CaCO3 precipitation caused the positive relationship between temperature and Sr/Ca. A large proportion of among-individual variability in shell Sr/Ca was caused by unspecified factors other than temperature. This makes it difficult to accurately estimate the past temperature by measuring the Sr/Ca value of a single shell specimen.

Journal Vol – 15 No -7, July 2020 Journal &gt; Journal &gt; Journal Vol – 15 No -7, July 2020 &gt; Page 6 PERFORMANCE AND EMISSION CHARACTERISTICS OF GASOLINE-ETHANOL BLENDS ON PFI-SI ENGINE Authors: D.Vinay Kumar ,G.Samhita Priyadarsini,V.Jagadeesh Babu,Y.Sai Varun Teja, DOI NO: https://doi.org/10.26782/jmcms.2020.07.00051 admin July 26, 2020 Abstract: Alcohol based fuels can be produced from renewable energy sources and

Journal Vol – 15 No -7, July 2020 Journal &gt; Journal &gt; Journal Vol – 15 No -7, July 2020 &gt; Page 6 PERFORMANCE AND EMISSION CHARACTERISTICS OF GASOLINE-ETHANOL BLENDS ON PFI-SI ENGINE Authors: D.Vinay Kumar ,G.Samhita Priyadarsini,V.Jagadeesh Babu,Y.Sai Varun Teja, DOI NO: https://doi.org/10.26782/jmcms.2020.07.00051 admin July 26, 2020 Abstract: Alcohol based fuels can be produced from renewable energy sources and

Study on engineering and thermal properties of environment-friendly lightweight brick made from Kinmen oyster shells & sorghum waste

The application of adding oyster shells and rice straw into cement has proven its applicability in past researches. This project not only focuses on the engineering study of the application of adding oyster shells into cement to make lightweight bricks, but also discusses the feasibility of replacing fine aggregates with the unique agricultural waste of Kinmen Island, sorghum. The study is mainly about achieving the best mixing ratio of ground oyster shells and sorghum to replace fine aggregate. The present study found that when the best mixing ratio of replacing fine aggregates with ground oyster shell and sorghum is achieved, the compaction degree was not significantly decreased. Fine aggregates replaced by up to 10–15% waste products—that is, made from 10% ground oyster shells or mixing 10% ground oyster shells and sorghum (5%) without other admixtures, meet the Chinese National Standards (CNS) and a lower thermal conductivity. Replacing fine aggregates with Kinmen’s fishery and agricultural waste, oyster shells and sorghum, and adding to generic non-structural light bricks not only decreases the use of cement mortar, imported partition bricks are replaced in addition to decreasing the overall carbon footprint of the island, balancing the island’s annual agricultural and fishery waste and needed construction materials, and solving environmental pollution problems stemming from business waste.

Study of bio-briquette formulation from mixture palm oil empty fruit bunches and palm oil shells

Bio-briquette is an alternative fuel derived from biomass. West Java has the potential of palm oil empty bunches (OPEFB) and palm oil shells biomass that can be used as bio-briquette raw material. The characteristics of each raw material affect the quality of the bio-briquettes produced. it is necessary to find a mixture of formulations between palm oil empty bunches (OPEFB) and palm oil shells that produce the highest quality bio-briquettes. This study aims to find a mixture of palm oil empty bunches and palm oil shell formulations that produce biobriquettes with optimum quality based on calorific value. This study used an experimental method with descriptive analysis. Variation of mixed formulations consisted of 5 treatments with a concentration of 7% adhesive material, carbonization temperature OPEFB 350 °C and palm oil shell 500 °C, compression pressure 225 kg/cm2, drying temperature 60 °C within 3 hours (2 replication). The observational parameters were the calorific value and proximate characteristics. The results showed that carbon content increased in both raw materials after the carbonization process expected, The highest calorific value of 5, 475 cal/gram was produced by bio briquettes with a mixture ratio of oil palm empty bunches and oil palm shells of 25:75.

Isotopic evidence for partial geochemical decoupling between a Jurassic epicontinental sea and the open ocean

We report stable isotope ratios (δ13C, δ18O), minor and trace elements (Mn, Fe, Sr, Mg) together with Ca concentrations from bivalve shells and belemnites from the Middle-Upper Jurassic Sundance Seaway (western United States), we compare them with coeval open-ocean Tethyan data, and reconstruct the palaeo-circulation of seaway waters. The Sundance Seaway was a 2000 km long epicontinental sea with a single entrance at mid latitudes (55–60°N), which would have fostered substantial evolution of seawater chemistry relative to its open-ocean source. Samples are distributed across the 13-million-year marine history of the seaway, and across a 540 km east-west transect spanning Wyoming. Delta13C values are in the same range as Tethyan data, and this suggests that they might record global changes in the carbon cycle, with one exception in the Oxfordian. Delta18O values from the seaway are in contrast highly depleted compared with Tethyan data (−2 to −6‰), and they indicate unrealistically high palaeotemperatures (20–40 °C), assuming an isotopic composition of seawater of −1‰, as generally used for the Jurassic. Given more realistic temperature estimates from Mg/Ca ratios of bivalve shells (10–25 °C), we explain such negative δ18O values by the southward inflow of normal-salinity, isotopically depleted (−3, −4‰), Arctic water into the seaway. Such water would become progressively more saline and denser as it flowed towards the southernmost portion of the seaway. In the Late Jurassic, characterised by wetter climate conditions, less dense Sundance waters may have instead exhibited a northward flow, reducing the southward surface flow from the Arctic. The observed partial geochemical decoupling of Sundance Seaway water masses from the open ocean strongly recommends caution in interpreting the geochemical record of ancient shallow seas, where local, regional and global drivers of change all need to be considered.