Short communication: public interest in rip currents relative to other natural hazards: evidence from Google search data

Natural Hazards - Informing and warning beach users about the danger posed by the rip current hazard remain a difficult challenge. Recent evidence suggests that warning signs and flags alone have...     

Study of mango biomass (Mangifera indica L) as a cationic biosorbent

Unfertilizable fruiting buds of mango plant Mangifera Indica L, an agrowaste, is used as a biomass in this study. The efficacy of the biosorbent was tested for the removal of lead, copper, zinc and nickel metal ions using batch experiments in single and binary metal solution under controlled experimental conditions. It is found that metal sorption increases when the equilibrium metal concentration rises. At highest experimental solution concentration used (150 mg/L), the removal of metal ions were 82.76 % for lead, 76.60 % for copper, 63.35 % for zinc and 59.35 % for nickel while at lowest experimental solution concentration (25 mg/L), the removal of metal ions were 92.00% for lead, 86.84 % for copper, 83.96 % for zinc and 82.29 % for nickel. Biosorption equilibrium isotherms were plotted for metal uptake capacity (q) against residual metal concentrations (C_f) in solution. The q versus C_f sorption isotherm relationship was mathematically expressed by Langmuir and Freundlich models. The values of separation factor were between zero and one indicating favourable sorption for four tested metals on the biosorbent. The surface coverage values were approaching unity with increasing solution concentration indicating effectiveness of biosorbent under investigation. The non-living biomass of Mangifera indica L present comparable biosorption capacity for lead, copper, zinc and nickel metal ions with other types of biosorbent materials found in literature and is effective to remove metal ions from single metal solutions as well as in the presence of other co-ions with the main metal of solution.     

Bioaccumulation of heavy metals in organs of fresh water fish Cyprinus carpio (Common carp)

The objective of the present study is to determine the bioaccumulation of heavy metals in various organs of the fresh water fish exposed to heavy metal contaminated water system. The experimental fish was exposed to Cr, Ni, Cd and Pb at sublethal concentrations for periods of 32 days. The elements Cd, Pb, Ni and Cr were assayed using Shimadzu AA 6200 atomic absorption spectrophotometery and the results were given as μ/g dry wt. The accumulation of heavy metal gradually increases in liver during the heavy metal exposure period. All the results were statistically significant at p < 0.001. The order of heavy metal accumulation in the gills and liver was Cd > Pb > Ni > Cr and Pb > Cd > Ni > Cr. Similarly, in case of kidney and flesh tissues, the order was Pb > Cd > Cr > Ni and Pb > Cr > Cd > Ni. In all heavy metals, the bioaccumulation of lead and cadmium proportion was significantly increased in the tissues of Cyprinus carpio (Common carp).     

The zircon-thorite mineral group in metasomatized granite,Ririwai, Nigeria 1. Geochemistry and metastable solid solution of thorite and coffinite

Summary At Ririwai, Nigeria, a biotite granite has suffered extensive post-magmatic metasomatism to produce albitized, microclinized, and greisenized rocks; the latter two lithologies form the wallrocks adjacent to tin-zinc vein-style mineralization. All the rock-types carry accessory amounts of thorite, locally accompanied by trace amounts of paragenetically late coffinite and xenotime. Petrographical and electron-microprobe data are presented for these minerals. In the biotite granite, thorite and coffinite range to high Zr contents (25.1 wt% ZrO₂ in thorite and 11.7 wt% in coffinite), exceeding the highest values previously reported in both minerals. In the lode wallrocks, yttrium contents range up to 13.9 wt% Y₂O₃ in thorite and 15.9 wt% in coffinite. From stoichiometric considerations, both minerals are inferred to contain OH. Petrographically, the thorites of the lode wallrocks are distinctive, and they are interpreted as having grown from the metasomatizing fluids. The albitized rocks and some of the lode wallrocks contain the thorites with the highest U contents, including one example of continuous zoning to coffinite. The unusual mineral compositions are interpreted as metastable solid-solution ranges formed from fluids that transported U, Th, Y and, over short distances, Zr.

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Die Zirkon-Thorit Mineral Gruppe in metasomatisiertem Granit, Ririwai, Nigeria. 1. Geochemie und metastable feste Lösungen des Thorit und Coffinit

Zusammenfassung In Ririwai, Nigeria, wurde ein Biotit-Granit durch extensive Metasomatose in albitisierte, mikroklinisierte und vergreisete Gesteine umgewandelt. In Mikroklin-Gesteinen und Greisen sitzt eine Zinn-Zink-Gangvererzung! Sämtliche Gesteinstypen führen Thorit als akzessorischen Gemengteil, stellenweise mit Spuren von spätgebildetem Coffinit und Xenotim. Petrographische und Mikrosonden-Daten dieser Minerale werden präsentiert. Im Biotit-Granit erreichten die Zr-Gehalte im Thorit und Coffinit Werte, wie sie bisher noch nicht bekannt waren (25.1 Gew.-% ZrO₂ im Thorit und 11.7 Gew.-% im Coffmit). In den Nebengesteinen reichen die Yttrium-Gehalte im Thorit bis 13.9 Gew.-% Y₂O₃, und im Coffinit bis 15.9 Gew.-%. Aus stöchiometrischen Überlegungen kann vermutet werden, daß beide Minerale OH enthalten. Petrographisch sind die Thorite aus den Nebengesteinen eindeutig definiert, und sie dürften aus metasomatischen Fluida entstanden sein. Die albitisierten Gesteine und auch einige Nebengesteine führen Thorite mit den höchsten U-Gehalten, darunter ein Beispiel mit einem kontinuierlichen Zonarbau bis zum Coffinit. Die ungewöhnlichen Mineralzusammensetzungen werden als metastabile feste Lösungen interpretiert, die aus Fluiden gebildet worden sind, welche U, Th, Y und über kurze Distanzen auch Zr transportiert haben.

     

Late Quaternary tephra layers around Raoul and Macauley Islands,Kermadec Arc: implications for volcanic sources,explosive volcanism and tephrochronology

A suite of deep‐sea cores were collected along transects up to 100 km across the fore‐arc and back‐arc regions of the predominantly submarine Kermadec arc near Raoul and Macauley islands, southwest Pacific. The cores reveal a macroscopic tephra record extending back >50 ka. This is a significant addition to the dated record of volcanism, previously restricted to fragmented late Holocene records exposed on the two islands. The 27 macroscopic tephra layers display a wide compositional diversity in glass (～50–78 wt% SiO₂). Many tephra layers comprise silicic shards with a subordinate mafic shard population. This could arise from magma mingling and may reflect mafic triggering of the silicic eruptions. Broadly, the glass compositions can be distinguished on diverging high‐K and low‐K trends, most likely arising from different source volcanoes. This distinction is also reflected in the tephra records exposed on Raoul (low‐K) and Macauley (high‐K) islands, the likely source areas. Heterogeneous tephra comprising shards of both high‐ and low‐K affinity, silicic and mafic compositions, and more homogeneous tephra with subordinate outlier shard compositions, are best explained by post‐depositional mixing of separate eruption deposits or contemporaneous eruptions. Evidently, the slow sedimentation rates of the calcareous oozes (～10¹–10² mm ka^?1) were insufficient to adequately separate and preserve closely spaced eruption deposits. This exemplifies the difficulty in assessing eruption frequencies and magmatic trends, and erecting a tephrostratigraphy, using geochemical fingerprinting in such environments. Despite these difficulties, the ca. 5.7 ka Sandy Bay Tephra erupted from Macauley Island can be correlated over a distance of >100 km, extending east and west of the island, showing that the mostly submerged volcanoes are capable of wide tephra dispersal. Hence there is potential for developing chronostratigraphies for the southwest Pacific beyond the region covered by the extensive rhyolite marker beds from the Taupo Volcanic Zone. Copyright © 2011 John Wiley & Sons, Ltd.     

A multi‐proxy record of changing environments from ca. 30 000 to 9000 cal. a BP: Onepoto maar palaeolake,Auckland, New Zealand

We present a high‐resolution record of lacustrine sedimentation spanning ca. 30 000 to 9000 cal. a BP from Onepoto maar, northern North Island, New Zealand. The multi‐proxy record of environmental change is constrained by tephrochronology and accelerator mass spectrometric ¹⁴C ages and provides evidence for episodes of rapid environmental change during the Last Glacial Coldest Period (LGCP) and Last Glacial–Interglacial Transition (LGIT) from northern New Zealand. The multi‐proxy palaeoenvironmental record from Onepoto indicates that the LGCP was cold, dry and windy in the Auckland region, with vegetation dominated by herb and grass in a beech forest mosaic between ca. 28 500 and 18 000 cal. a BP. The LGCP was accompanied by more frequent fires and influx of clastic sediment indicating increased erosion during the LGCP, with a mid‐LGCP interstadial identified between ca. 25 000 and 23 000 cal. a BP. Rapid climate amelioration at ca. 18 000 cal. a BP was accompanied by increased terrestrial biomass exemplified by the expansion of lowland podocarp forest, especially Dacrydium cupressinum. Increasing biomass production is reversed briefly by LGIT perturbations which are apparent in many of the proxies that span ca. 14 000–10 500 cal. a BP, suggesting generally increased wetness and higher in situ aquatic plant productivity with reduced terrestrial organic matter and terrigenous detrital influx. Furthermore, conditions at that time were probably warmer and frosts rare based on the increasing importance of Ascarina. The subsequent early Holocene is characterised by podocarp conifer forest and moist mild conditions. Postglacial sea‐level rise breached the crater rim and deposited 36 m of estuarine mud after ca. 9000 cal. a BP. Copyright © 2011 John Wiley & Sons, Ltd.     

Early Permian climate change in the Falkland Islands

An Early Permian glacial diamictite forms a distinctive unit within the Falkland Islands sedimentary succession and two aspects of its significance have recently been serendipitously enhanced. Fossil discoveries in exotic limestone clasts bear on palaeogeography, whilst a series of mineral‐exploration borehole cores have allowed a detailed study of the sedimentary record of deglaciation that followed deposition of the diamictite. Statistical analysis of reflectance and XRF core‐scanning data has identified likely Milankovitch periodicities and enabled tentative time‐scale modelling. The ‘icehouse to greenhouse’ transition appears to have spanned approximately 1.2 million years, with waning cycles of re‐advance superimposed on overall glacial retreat. The new results play into a long‐debated geological paradox: although the Falkland Islands are now proximal to the South Atlantic coastline of South America, their geology bears an uncanny resemblance to that of the Cape Fold Belt and Karoo Basin in South Africa. This puzzled the geological pioneers, but became readily explicable when first continental drift and then plate tectonics were invoked to reconstruct the break‐up of the Gondwana supercontinent—although the details remain controversial. One of the key stratigraphical correlation levels throughout the major fragments of southern Gondwana—South Africa, South America, Antarctica and Australia—is the glacigenic deposit left behind by the extensive, Late Carboniferous to Early Permian regional glaciation; in the Falkland Islands it is designated the Fitzroy Tillite Formation.     

Cross inoculation studies: Response of Vigna mungo to inoculation with rhizobia from tree legumes growing under arid Environment

Cross-inoculation experiments were conducted in the greenhouse to test the rhizobia isolated from nodules of seven tree legumes for their effectiveness in Vigna mungo plants. The tree legumes included Albizia lebbeck, Dalbergia sissoo, Leucaena leucocephala, Pithecellobium dulce, Prosopis cineraria, Prosopis glandulosa and Prosopis juliflora, all growing under arid environment. Rhizobia from these legumes formed nodules on the roots of Vigna mungo except isolates from Albizia lebbeck. Dry weight and nitrogen contents of Vigna mungo plants increased significantly (P<0.05) in response to cross inoculation as compared to uninoculated control. Rhizobia from Leucaena leucocephala and Prosopis glandulosa showed significant increase in dry weight (P<0.05) and nitrogen contents (P<0.05) than other inoculated treatments. The natural rhizobia of wild tree legumes growing under arid environment show higher tolerance to prevailing adverse conditions like salt stress, elevated temperatures and drought. These rhizobia may be used to inoculate wild as well as crop legumes cultivated in reclaimed desert lands. These rhizobia may have specific traits that can be transferred to other rhizobia through genetic engineering tools. The cross infection of agriculturally important legumes with isolates from wild legumes may prove a useful means of increasing nitrogen contents within these plants.     

Biodegradation of palmarosa oil (green oil) by Serratia marcescens

Biodegradation of oil depends on the nature of the oil, the type of microbial community and a variety of environmental factors. Green oils are being used as consumer goods and as raw materials in industries such as food processing, pharmaceutical and cosmetic. Microbial contaminations of green oils have been the cause of degradation problems. Serratia Marcessens produced cytochrome oxidase, catalase, Dextrose, Lactose, Manose and sorbitol enzymes were the main reason for the degradation af palmarosa oil. Changes of colour and turbidity was also the evidence for green oil degradation by bacteria. More oxygen included protons (0-CH²) group was produced in the presence of bacterial species and the addition of oxygen took place during bacterial degradation of palmarosa oil. The biodegradation of palmarosa oil by Serratia marcescens have been carried out using High Performance Liquid Chromatography, Fourier Transform Infrared Spectroscopy and Nuclear Magnetic spectroscopy analysis. Carboxyl group present in the palmorasa oil is utilised as a sole carbon sources for the Serratia marcescens.