Differential sensitivity of flounder (Platichthys flesus) in response to oestrogenic chemical exposure: an issue for design and interpretation of monitoring and research programmes

This study was conducted as an initial investigation of 'differential response' in one of the main sentinel organisms used for monitoring programmes in United Kingdom estuaries, the flounder Platichthys flesus. It has been hypothesised that monitoring using species with a wide geographical spread and limited migration, such as flounder, might result in the comparison of different genetic stocks and certainly of populations with differing early life stage contaminant exposure histories. Furthermore, it is probable that these pre-exposure and genetic differences could manifest themselves in an ability to respond differently to contaminant exposure, so-called 'differential response'. It is important that the extent and nature of this response is understood, if we want to be able to fully interpret the monitoring data from such programmes. During this study, flounder were collected from four separate sources; wild caught fish from the estuaries of the Rivers Alde, Mersey and Tyne, and farmed flounder from Port Erin Farm, Isle of Man. Under controlled laboratory conditions, groups of fish from each source were exposed to water-borne concentrations of the synthetic oestrogen ethynylestradiol (EE2) at a nominal concentration of 50 ng/l. Plasma was taken from each male fish after 6 and 10 days exposure and analysed for the presence of vitellogenin (VTG) using an ELISA technique. Significant levels of VTG induction were evident in fish from all sources after both 6 and 10 days exposure. Flounder from the Mersey were the only fish with significantly elevated initial background levels of VTG (day 0) and this appeared to be reflected in that these specimens showed the highest induction response after day 6. However, after day 10, fish from all other sites had a slightly higher mean VTG than those from the Mersey which showed significantly (p < 0.05) lower mean plasma VTG. It is suggested that other differential responses may have been masked by the use of a high dose of EE2 which produced maximum induction in nearly all fish. The findings of the study are discussed in terms of implications for further research into the differential response issue and how the initial plasma VTG figures contribute to a time-series from the Mersey, Tyne and Alde estuaries.     

Detrital zircon provenance of Neoproterozoic to Cenozoic deposits in Iran: Implications for chronostratigraphy and collisional tectonics

Ion-microprobe U–Pb analyses of 589 detrital zircon grains from 14 sandstones of the Alborz mountains, Zagros mountains, and central Iranian plateau provide an initial framework for understanding the Neoproterozoic to Cenozoic provenance history of Iran. The results place improved chronological constraints on the age of earliest sediment accumulation during Neoproterozoic–Cambrian time, the timing of the Mesozoic Iran–Eurasia collision and Cenozoic Arabia–Eurasia collision, and the contribution of various sediment sources of Gondwanan and Eurasian affinity during opening and closure of the Paleotethys and Neotethys oceans. The zircon age populations suggest that deposition of the extensive ~ 1 km-thick clastic sequence at the base of the cover succession commenced in latest Neoproterozoic and terminated by Middle Cambrian time. Comparison of the geochronological data with detrital zircon ages for northern Gondwana reveals that sediment principally derived from the East African orogen covered a vast region encompassing northern Africa and the Middle East. Although most previous studies propose a simple passive-margin setting for Paleozoic Iran, detrital zircon age spectra indicate Late Devonian–Early Permian and Cambrian–Ordovician magmatism. These data suggest that Iran was affiliated with Eurasian magmatic arcs or that rift-related magmatic activity during opening of Paleotethys and Neotethys was more pronounced than thought along the northern Gondwanan passive-margin. For a Triassic–Jurassic clastic overlap assemblage (Shemshak Formation) in the Alborz mountains, U–Pb zircon ages provide chronostratigraphic age control requiring collision of Iran with Eurasia by late Carnian–early Norian time (220–210 Ma). Finally, Cenozoic strata yield abundant zircons of Eocene age, consistent with derivation from arc magmatic rocks related to late-stage subduction and/or breakoff of the Neotethys slab. Together with the timing of foreland basin sedimentation in the Zagros, these detrital zircon ages help bracket the onset of the Arabia–Eurasia collision in Iran between middle Eocene and late Oligocene time.     

Source and supply of sediment to a shoreline salient in a fringing reef environment

Reef-associated landforms are coupled to the health of the reef ecosystem which produces the sediment that forms and maintains these landforms. However, this connection can make reef-fronted coastlines sensitive to the impacts of climate change, given that any decline in ecosystem health (e.g. decreasing sediment supply) or changes to physical processes (e.g. sea level rise, increasing wave energy) could drive the sediment budgets of these systems into a net erosive state. Therefore, knowledge of both the sediment sources and transport mechanisms is required to predict the sensitivity of reef-associated landforms to future climate change. Here, we examine the benthic habitat composition, sediment characteristics (composition, texture, and age), and transport mechanisms and pathways to understand the interconnections between coastal morphology and the reef system at Tantabiddi, Ningaloo Reef, Western Australia. Benthic surveys and sediment composition analysis revealed that although live coral accounts for less than 5% of the benthic cover, coral is the dominant sediment constituent (34% on average). Sediment ages (²³⁸U/²³⁰Th) were mostly found to be thousands of years old, suggesting that the primary sediment source is relic reef material (e.g. Holocene reef framework). Sediment transport across the lagoon was quantified through measurements of ripple migration rates, which were found to be shoreward migrating and responsible for feeding the large shoreline salient in the lee of the reef. The derived sediment fluxes were comparable with previously measured rates of sediment production by bioerosion. These results suggest that sediment budgets of systems dependent on old (>10³ years) source materials may be more resilient to climate change as present-day reef health and community composition (i.e. sources of ‘new’ carbonate production) have limited influence on sediment supply. Therefore, the vulnerability of reef-associated landforms in these systems will be dictated by future changes to mechanisms of sediment generation (e.g. bioerosion) and/or physical processes. © 2018 John Wiley & Sons, Ltd.     

The solar radio event of January 14, 1971

A study has been made of the behaviour in time of the positions, flux density and polarization for the radio emissions at frequencies of 237 and 408 MHz (from Trieste observations), taking into account also the published results at 169 and 160–200 MHz (from Nançay and Utrecht) connected with the solar flare which occurred on January 14, 1971, at 11^h21^m UT.The flare and the subsequent emissions may have been excited by a fall of coronal matter along the lines of force of the magnetic field in the relevant active region, exciting radio emissions of two different types: a type II-like emission and a type III group apparently located at different positions.This discrepancy can be easily explained if we assume that the type III group was due to second harmonic emission in backward direction, strongly refracted by the coronal plasma.The observed spike emission was due to a source high in the corona, excited by the type II-like perturbation which originated in the flare region, and this fact clearly points out the relationship between all the observed peculiar emissions from type IV sources, as has already been stated by this author.     

A 3.5 Ga record of water-limited, acidic weathering conditions on Mars

The secondary mineral budget on Earth is dominated by clay minerals, Al-hydroxides, and Fe-oxides, which are formed under the moderate pH, high water-to-rock ratio conditions typical of Earth's near-surface environment. In contrast, geochemical analyses of rocks and soils from landed missions to Mars indicate that secondary mineralogy is dominated by Mg (± Fe, Ca)-sulfates and Fe-oxides. This discrepancy can be explained as resulting from differences in the chemical weathering environment of Earth and Mars. We suggest that chemical weathering processes on Mars are dominated by: (1) a low-pH, sulfuric acid-rich environment in which the stoichiometric dissolution of labile mineral phases such as olivine and apatite (± Fe–Ti oxides) is promoted; and (2) relatively low water-to-rock ratio, such that other silicate phases with slower dissolution rates (e.g., plagioclase, pyroxene) do not contribute substantially to the secondary mineral budget at the Martian surface. Under these conditions, Al-mobilization is limited, and the formation of significant Al-bearing secondary phases (e.g., clays, Al-hydroxides, Al-sulfates) is inhibited. The antiquity of rock samples analyzed in-situ on Mars suggest that water-limited acidic weathering conditions have more than likely been the defining characteristic of the Martian aqueous environment for billions of years.     

Holocene changes in seasonal precipitation highlighted by fire incidence in eastern Canada

Postglacial fire history has been reconstructed for eastern Canada from charcoal-influx anomalies from 30 sites taken from a lacustrine charcoal database. The reconstruction exhibits coherent patterns of fire occurrence in space and time. The early Holocene is characterised by high fire incidence. There is a major change to much lower occurrence slightly after 8 ka BP. A return to more fire appears after 3 ka BP. This sequence does not fit with the hydro-climatic reconstruction deduced from lake level reconstructions for northeastern North America, which indicates a dry early and mid-Holocene, and a wet late-Holocene. Fire occurrence however closely matches summer relative humidity inferred from δ¹⁸O. The differences between fire frequency and lake level history, are due to changes in the seasonality of precipitation and drought frequency. Lake levels are essentially controlled by winter precipitation while summer precipitation controls fire occurrence. The early Holocene before 8–7.5 ka BP experienced dry summers due to higher solar radiation and dry adiabatic winds from the residual Laurentide Ice Sheet. The middle Holocene was dominated by wet summers due to stability of the Atlantic air mass over eastern Canada. After 2.5 ka BP, summers became drier, albeit not as fire-conducive as during the early Holocene. Late-Holocene summers conducive to fire are explained by more frequent incursions of dry Cool Pacific or Cold Arctic air masses over eastern Canada. Received: 25 January 1999 / Accepted: 14 December 1999     

The U–Pb SHRIMP age of zircons from diorites of the Tomino–Bereznyaki ore field (South Urals,Russia): evolution of porphyry Cu–epithermal Au–Ag system

The Tomino–Bereznyaki ore field lies in the western part of the East Urals volcanic megazone (20–30 km southwest of Chelyabinsk). The commercial Tomino porphyry (Mo, Au)–Cu deposit is localized in the east of the field, within a small mesoabyssal intrusion of quartz–diorite composition. The epithermal Au–Ag Bereznyaki deposit is confined to subvolcanic dioritic porphyrites in the west of the field. The western and eastern parts of the ore field have a tectonic boundary. Granitoids belong to a single volcanoplutonic complex of K–Na-quartz–diorite composition. The U–Pb concordant age of zircons from the ore-bearing dioritic porphyrite of the Tomino and Bereznyaki deposits is 428 ± 3 Ma (MSWD = 0.9) and 427 ± 6 Ma (MSWD = 1.1), respectively. A Silurian absolute age has been established for the Urals porphyry Cu ore-magmatic system for the first time. The diorites and acid metasomatites of both deposits contain a unique three-mica assemblage (Mu, Pa, and Mu0.36Pa0.64). The metasomatized diorites are of similar isotope-petrogeochemical compositions; they have close total REE contents (24–52 ppm) and REE patterns. Their Zr–Hf, Nb–Ta, and La–Ce diagrams show similar trends. The obtained data indicate the close time of formation of the porphyry and epithermal deposits and their probable genetic unity. The vertical evolution of the porphyry Cu column from meso- and hypabyssal to subvolcanic level includes the isotope (Sr, S, and O) crust–mantle interaction. The deposits formed at different depths expose on the modern surface as a result of the block tectonic processes in the ore field.     

Structural relationships between a brown coal and its kerogen and humic acid fractions

A South Australian Tertiary brown coal is fractionated into humic acid and kerogen fractions. These related samples are then subjected to a number of different analytical techniques including infrared and¹³C-Nuclear Magnetic Resonance spectroscopies and pertrifluoroacetic acid oxidation. Structural conclusions are drawn from an integrated consideration of the data. Brown coal aliphatic structure is concentrated in the kerogen and the solvent soluble polar acid fractions. The humic acids are the most aromatic and contain a high degree of hydrogen bonding. Only very minor amounts of long polymethylene chain structures are observed in the humic acids, in complete contrast to the kerogen fraction. Different organic detrital origins are proposed for the coal fractions.     

Three-dimensional crustal and upper mantle structure beneath Chalkidiki (northern Greece)

We invert teleseismic relative residuals recorded in the Thessaloniki seismological network, for the crustal and upper mantle structure beneath Chalkidiki (Northern Greece) where extension is observed to have occurred since Eocene time. After conducting several tests to insure the reliability of the results, a low-velocity anomaly (5–8%) is observed which is located beneath Chalkidiki for the top two layers (0–35 km and 35–85 km); this anomaly is probably related to the fact that the crust is thicker here than beneath the neighboring basins. For the two other layers, with depths between 85 and 145 km and between 145 and 205 km, relatively low velocities (3–5%) are observed beneath the Thermaico Gulf and the Kavala Basin. These results are compared with Lyberis's (1985) [8] calculated shallowing of the isotherms due to extension and thinning of the lithosphere. We conclude that the velocity anomalies that we observe are likely to be due to the intrusion of hot material from the asthenosphere into the gap in the extended lithosphere.