Adsorptive Removal of Acid Blue 15: Equilibrium and Kinetic Study

Activated carbons prepared from sunflower seed hull have been used as adsorbents for the removal of acid blue 15 (AB‐15) from aqueous solution. Batch adsorption techniques were performed to evaluate the influences of various experimental parameters, e. g., temperature, adsorbent dosage, pH, initial dye concentration and contact time on the adsorption process. The optimum conditions for AB‐15 removal were found to be pH = 3, adsorbent dosage = 3 g/L and equilibrium time = 4 h at 30°C. The adsorption of AB‐15 onto the adsorbent was found to increase with increasing dosage. It was found from experimental results that the Langmuir isotherm fits the data better than the Freundlich and Temkin isotherms. The maximum adsorption capacity, Q_m (at 30°C) was calculated for SF1, SF2, and SF3 as 75, 125 and 110 mg g^–1 of adsorbent, respectively. It was found that the adsorption follows pseudo‐second order kinetics. The thermodynamic parameters such as ΔG°, ΔH°, and ΔS° were also evaluated. The activated carbons prepared were characterized by FT‐IR, SEM and BET analysis.     

Clumped isotope thermometry of carbonatites as an indicator of diagenetic alteration

We measure the clumped isotopic signature of carbonatites to assess the integrity of the clumped isotope paleothermometer over long timescales (10⁷-10⁹ years) and the susceptibility of the proxy to closed system re-equilibration of isotopes during burial diagenesis. We find pristine carbonatites that have primary oxygen isotope signatures, along with a Carrara marble standard, do not record clumped isotope signatures lighter than 0.31‰ suggesting atoms of carbon and oxygen freely exchange within the carbonate lattice at temperatures above 250-300 °C. There is no systematic trend in the clumped isotope signature of pristine carbonatites with age, although partial re-equilibration to lower temperatures can occur if a carbonatite has been exposed to burial temperatures for long periods of time. We conclude that the solid-state re-ordering of carbon and oxygen atoms is sufficiently slow to enable the use of clumped isotope paleothermometry on timescales of 10⁸ years, but that diagenetic resetting can still occur, even without bulk recrystallization. In addition to the carbonatite data, an inorganic calibration of the clumped isotope paleothermometer for low temperature carbonates (7.5-77 °C) is presented and highlights the need for further inter-lab standardization.     

Geochemistry of silicic magmas in the Macolod Corridor, SW Luzon, Philippines: evidence of distinct, mantle-derived, crustal sources for silicic magmas

Silicic volcanic deposits (>65 wt% SiO₂), which occur as domes, lavas and pyroclastic deposits, are relatively abundant in the Macolod Corridor, SW Luzon, Philippines. At Makiling stratovolcano, silicic domes occur along the margins of the volcano and are chemically similar to the silicic lavas that comprise part of the volcano. Pyroclastic flows are associated with the Laguna de Bay Caldera and these are chemically distinct from the domes and lavas at Makiling stratovolcano. As a whole, samples from the Laguna de Bay Caldera contain lower concentrations of MgO and higher concentrations of Fe₂O_3(t) than the samples from domes and lavas. The Laguna de Bay samples are more enriched in incompatible trace elements. The silicic rocks from the domes, Makiling Volcano and Laguna de Bay Caldera all contain high alkalis and high K₂O/Na₂O ratios. Melting experiments of primitive basalts and andesites demonstrate that it is difficult to produce high K₂O/Na₂O silicic magmas by fractional crystallization or partial melting of a low K₂O/Na₂O source. However, recent melting experiments (Sisson et al., Contrib Mineral Petrol 148:635–661, 2005) demonstrate that extreme fractional crystallization or partial melting of K-rich basalts can produce these silicic magmas. Our model for the generation of the silicic magmas in the Macolod Corridor requires partial melting of mantle-derived, evolved, moderate to K-rich, crystallized calc-alkaline magmas that ponded and crystallized in the mid-crust. Major and trace element variations, along with oxygen isotopes and ages of the deposits, are consistent with this model. Electronic Supplementary Material Supplementary material is available for this article at     

Direct and Indirect Validation of Potential Fishing Zone Advisory off the Coast of Uttara Kannada,Karnataka

The technique of predicting Potential Fishing Zone using satellite derived sea surface temperature and chlorophyll is becoming an important aspect for the fishermen. In the present study an attempt has been made to compare fish density/catch per unit effort in the areas predicted by Satellite imagery and available to fishermen via electronic display boards at the fish landing centers of Uttara Kannada district, Karnataka with those of non predicted areas. Direct and Indirect validation was done. Direct method means comparing the catch using fishing vessels simultaneously in the notified region with that of catch from non notified region. And in indirect method by comparing catch data from landing centers on notified days with that of non notified days. Direct validation off Karwar showed that catch was significantly higher in notified (PFZ) area with high densities as compared to non notified (non PFZ) regions. When comparisons of landing center data of Karwar, Tadadi and Bhatkal are done it is evident that in all the centers during the period under study, higher catches were observed on notified days than non notified days except in Bhatkal centre in 2009–10. There by validating the accuracy of PFZ predictions and economic gains to fishermen.     

Using slowness and azimuth fluctuations as new observables for four‐dimensional reservoir seismic monitoring

Four‐dimensional imaging using geophysical data is of increasing interest in the oil and gas industries. While travel‐time and amplitude variations are commonly used to monitor reservoir properties at depth, their interpretation can suffer from a lack of information to decipher the parts played by different parameters. In this context, this study focuses on the slowness and azimuth angle measured at the surface using source and receiver arrays as complementary observables. In the first step, array processing techniques are used to extract both azimuth and incidence angles at the source side (departure angles) and at the receiver side (arrival angles). In the second step, the slowness and angle variations are monitored in a laboratory environment. These new observables are compared with traditional arrival‐time variations when the propagation medium is subject to temperature fluctuations. Finally, field data from a heavy‐oil permanent reservoir monitoring system installed onshore and facing steam injection and temperature variations are investigated. The slowness variations are computed over a period of 152 days. In agreement with Fermat's principle, strong correlations between the slowness and arrival‐time variations are highlighted, as well as good consistency with other techniques and field pressure measurements. Although the temporal variations of slowness and arrival time show the same features, there are still differences that can be considered for further characterization of the physical changes at depth.     

Late- to post-orogenic basins of the Pan-African – Brasiliano collision orogen in southern Africa and southern Brazil

Late- to post-orogenic basins formed on both sides of the Pan-African – Brasiliano orogen when the Congo and Kalahari Cratons collided with the Rio de la Plata Craton during the formation of western Gondwana. Trace fossil evidence and radiometric age dating indicate that deposits on both sides are coeval and span the Cambrian–Precambrian boundary. A peripheral foreland basin, the Nama Basin, developed on the subducting southern African plate. Lower, craton-derived fluviomarine clastics are overlain by marine platform carbonates and deltaic flysch derived in part from the rising subduction complex along the northern (Damara Belt) and western (Gariep Belt) orogenic margins. Rare, thin volcanic ash layers (tuffs and cherts) are present. Upper sediments consist of unconformable red molasse related to collisional orogenesis. Orogenic loading from the north and west led to crustal flexure and the formation of a remnant ocean that drained to the south and closed progressively from north to south. During final collision SE-, E- and NE-verging nappes overrode the active basin margins. Although younger than most of the post-orogenic magmatism, its setting on the cratonic edge of the subducting plate precluded marked volcanism or granitic intrusion, the only exception being the youngest intrusions of the Kuboos-Bremen Suite dated at 521±6 Ma to 491±8 Ma. Two foreland-type basins, perhaps faulted remnants of a much larger NE–SW elongated retroarc foreland basin, are found west of the Dom Feliciano Belt on the edge of the Rio de la Plata Craton in southern Brazil. In the southern Camaqua Basin, basal fluvial deposits are followed by cyclical marine and coarsening-up deltaic deposits with a notable volcanic and volcaniclastic component. This lower deformed succession, comprising mainly red beds, contain stratabound Cu and Pb–Zn deposits and is overlain unconformably by a fluviodeltaic to aeolian succession of sandstones and conglomerates (with minor andesitic volcanics), derived primarily from an eastern orogenic source and showing southerly longitudinal transport. In the northern Itajaí Basin, sediments range from basal fluvial and platform sediments to fining-up submarine fan and turbidite deposits with intercalated acid tuffs. The Brazilian basins had faulted margins off which alluvial fans were shed. They also overlie parts of the Ribeira Belt. Thrust deformation along the orogenic margin bordering the Dom Feliciano Belt was directed westward in the Camaqua and Itajaí basins, but reactivated strike-slip and normal faults are also present. Late- to post-orogenic granitoids and volcanics of the Dom Feliciano Belt, ranging in age from 568±6 Ma to 529±4 Ma, occur in the foreland basins and are geochemically related to some of the synsedimentary volcanics.     

Early tertiary deltaic sedimentation around Kalka and Nahan, Punjab Himalaya, India

During the Early Tertiary epoch a basin of deposition covered almost all the present Himalayan foot hill zone. Large quantities of detrital sediments were transported from the northern source area to the depositional basin. The rivers carrying the sediment load formed large delta complexes. In the area studied at least two such delta complexes, one around Kalka and the other around Nahan, were formed; of these the one around Kalka contains the greatest volume of sediments.

The recognition of the deltas is based on: (a) greater abundance of stream deposits than deposits of other environments; (b) lithologic criteria, particularly sedimentary structures, repetitive lithologic associations; (c) the general coarsening-upward nature of the sediments; (d) strong unimodal current direction; (e) the typical lenticular lithogenetic model, common in recent deltas.

The rocks of the Nahan Group are divisible into three formations at Kalka and two formations at Nahan where central formation did not develop. Himalayan tectonism has largely controlled both delta formation and stratigraphy.

The differential rates of sedimentation greatly influenced the rates of subsidence within the Nahan basin. The sediments of the Nahan Group are roughly bounded between two major phases of Himalayan uplift, namely Eocene and middle Miocene tectonic movements. The effects of intermittent tectonic pulses are well depicted in rocks of the Nahan Group. The intensity of the tectonism that controlled both the source-area rise and basin subsidence during deposition of the Nahan Group of sediments was nonuniform, both in vertical and lateral directions. Because of a generally higher rate of deposition compared to the rate of subsidence, the rocks of the Nahan group represent a normal regressive basin-filling sedimentation, forming thick detrital deposits due to progradation of younger deltas beyond the distal end of older deltas.     

Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in sediments from Hong Kong

Concentrations of 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were determined in 14 sediment samples collected from four sites in the Mai Po Marshes Nature Reserve (within a RAMSAR Site) and from another six sites in Victoria Harbour and along the Hong Kong coastline. Elevated levels of PCDDs, and particularly OCDD, were detectable in all samples collected from the Mai Po Marshes and five of the six sites. In contrast to PCDDs, PCDFs were mainly found in sediment samples collected from industrial areas (Kwun Tong and To Kwa Wan) in Victoria Harbour. PCDD/F levels and congener profiles in the samples from the Mai Po Marshes Nature Reserve in particular show strong similarities to those reported in studies which have attributed similar elevated PCDD concentrations to nonanthropogenic PCDD sources.     

Morphology and structure of the Galapagos Rise

Geophysical data collected on three U.S. Naval Oceanographic Office cruises to the Galapagos Rise are presented. These data allow definition of the morphology and structure of the Galapagos Rise.A postulated “hot spot” beneath the Galapagos platform is suggested as the cause of: (1) decreased seismicity along the spreading center for a 400 km E—W distance from the islands; (2) distinctive petro-chemistry of tholeiites from the islands and adjacent oceanic crust generated by the Galapagos Rise; (3) high-amplitude magnetic anomalies in a 1,000 km E—W band including and just north of the Galapagos platform; and (4) morphologic shape and the regionally elevated sea floor of the Galapagos Rise as it approaches the insular platform.