Mixed memory, (non) Hurst effect, and maximum entropy of rainfall in the tropical Andes

Diverse linear and nonlinear statistical parameters of rainfall under aggregation in time and the kind of temporal memory are investigated. Data sets from the Andes of Colombia at different resolutions (15 min and 1-h), and record lengths (21 months and 8-40 years) are used. A mixture of two timescales is found in the autocorrelation and autoinformation functions, with short-term memory holding for time lags less than 15-30 min, and long-term memory onwards. Consistently, rainfall variance exhibits different temporal scaling regimes separated at 15-30 min and 24 h. Tests for the Hurst effect evidence the frailty of the R/S approach in discerning the kind of memory in high resolution rainfall, whereas rigorous statistical tests for short-memory processes do reject the existence of the Hurst effect.Rainfall information entropy grows as a power law of aggregation time, S(T) ∼ T^β with 〈β〉 = 0.51, up to a timescale, T_MaxEnt (70-202 h), at which entropy saturates, with β = 0 onwards. Maximum entropy is reached through a dynamic Generalized Pareto distribution, consistently with the maximum information-entropy principle for heavy-tailed random variables, and with its asymptotically infinitely divisible property. The dynamics towards the limit distribution is quantified. Tsallis q-entropies also exhibit power laws with T, such that S_q(T) ∼ T^β(q), with β(q) ? 0 for q ? 0, and β(q) ? 0.5 for q ? 1. No clear patterns are found in the geographic distribution within and among the statistical parameters studied, confirming the strong variability of tropical Andean rainfall.     

Conditions when anisotropy is negligible for solute transfer in sediment beds of lakes or streams

To reduce the complexity and save computation time, an isotropic and a scalar dispersion model are explored and compared to the anisotropic advection/dispersion model to study the interstitial flow in a stream and lake sediment induced by a periodic pressure wave. In these systems, the solute transport is controlled by the ratio (R = a/(LS)) of the pressure wave steepness (a/L) to the stream slope (S), and the dispersivity ratio (λ = α_L/L) that measures the longitudinal dispersivity (α_L) relative to the pressure wave length (L). Through a series of numerical experiments, the conclusion is reached that a scalar dispersion model can be applied with satisfactory results for advection-dominated transport, i.e. when R ?  0.1 and λ ? 0.01, or λ ? 0.0001, i.e. Peclet number (Pe) ? 10000; an isotropic dispersion model can be applied when R ? 10 or λ ? 0.001, and the full anisotropic advection/dispersion model has to be applied when R > 10 and λ > 0.001.     

Thermal equation of state of majorite with MORB composition

In situ synchrotron X-ray diffraction experiments were conducted using the SPEED-1500 multi-anvil press at SPring-8 on majoritic garnet synthesized from natural mid-ocean ridge basalt (MORB), whose chemical composition is close to the average of oceanic crust, at 19 GPa and 2200 K. Pressure-volume-temperature data were collected using a newly developed high-pressure cell assembly to 21 GPa and 1273 K. Data were fit to the high-temperature Birch-Murnaghan equation of state, with fixed values for the ambient cell volume (V₀ = 1574.14(4) Å³) and the pressure derivative of the isothermal bulk modulus (K^′T = 4). This yielded an isothermal bulk modulus of K_T0 = 173(1) GPa, a temperature derivative of the bulk modulus (∂K_T/∂T)_P = −0.022(5) GPa K⁻¹, and a volumetric coefficient of thermal expansivity α = a + bT with values of a = 2.0(3) × 10⁻⁵ K⁻¹ and b = 1.0(5) × 10⁻⁸ K⁻². The derived thermoelastic parameters are very similar to those of pyrope. The density of subducted oceanic crust compared to pyrolitic mantle at the conditions in Earth's transition zone (410-660 km depth) was calculated using these results and previously reported thermoelastic parameters for MORB and pyrolite mineral assembledges. These calculations show that oceanic crust is denser than pyrolitic mantle throughout the mantle transition zone along a normal geotherm, and the density difference is insensitive to temperature at the pressures in lower part of the transition zone.     

A Review of some Recent Radiation Fog Prediction Studies and the Results of Integrating a Simple Numerical Model to Predict Radiation Fog over Brunei

— Several radiation fog studies with emphasis on numerical simulation and prediction are reviewed. One of the earliest attempts started with a given surface diurnal variation of temperature and water vapor, and concluded by forecasting the onset of saturation at various levels; thus fog, by examining the spread of temperature and moisture in the vertical. The one-dimensional (1-D) models are still popular. Some of the recent numerical simulations use more than 100 levels in the vertical and treat various kinds of vegetation, aerosols, and soils with moisture contents. Some also employ a mesoscale model in conjunction with a 1-D model to consider the advective effects. In the following a simple 1-D numerical model was used to predict the onset of fog at Brunei, based on a desktop computer and routine surface observations of dry bulb temperature (T), dewpoint temperature (T _d ), and wind speed at 1800 Local Time (LT). Optimism exists in improved predictions of fog and stratus as 1-D models incorporate many physical processes, and mesoscale models continue to improve in predicting advection and cloud cover.     

The thermodynamic properties of the earth's lower mantle

The thermodynamic properties of the lower mantle are determined from the seismic profile, where the primary thermodynamic variables are the bulk modulus K and density ρ. It is shown that the Bullen law (K ∝ P) holds in the lower mantle with a high correlation coefficient for the seismic parametric Earth model (PEM). Using this law produces no ambiguity or trade-off between ρ₀ and K₀, since both K₀ and K′₀ are exactly determined by applying a linear K?ρ relationship to the data. On the other hand, extrapolating the velocity data to zero pressure using a Birch-Murnaghan equation of state (EOS) results in an ambiguous answer because there are three unknown adjustable parameters (ρ₀, K₀, K′₀) in the EOS.From the PEM data, K = 232.4 + 3.19 P (GPa). The PEM yields a hot uncompressed density of 3.999 ± 0.0026 g cm^?3 for material decompressed from all parts of the lower mantle. Even if the hot uncompressed density were uniform for all depths in the lower mantle, the cold uncompressed mantle would be inhomogeneous because the decompression given by the Bullen law crosses isotherms; for example, the temperature is different at different depths. To calculate the density distribution correctly, an isothermal EOS must be used along an isotherm, and temperature corrections must be placed in the thermal pressure P_TH.The thermodynamic parameters of the lower mantle are found by iteration. Values of the three uncompressed anharmonic parameters are first arbitrarily selected: α₀ (hot), the coefficient of thermal expansion; γ₀, the Grüneisen parameter; and δ, the second Grüneisen parameter. Using γ₀ and the measured ρ₀ (hot) and K₀ (hot), the values of θ₀ (Debye temperature) and q = dlnγ/dlnρ are found from the measured seismic velocities. Then from (αK_T)₀ and q the thermal pressure P_TH at all high temperatures is found. Correlating P_TH against T to the geotherm for the lower mantle, P_TH is found at all depths Z. The isothermal pressure, along the 0 K isotherm, at every Z is found by subtracting P_TH from the measured P given by the seismic model. Using the isothermal pressure at depth Z, the solution for the cold uncompressed density ρ_0C and the cold uncompressed bulk modulus, K_T0 is found as a trace in the K_T0?_ρ0C plane. A narrow band of solutions is then found for ρ_0C and K_T0 at all depths.The thermal expansion at all T is found from [ρ_0C ? ρ₀ (hot)/ρ_0C. From Suzuki's formula, the best fit to the thermal expansion determines γ₀ and α₀ (hot). When the values of these two parameters do not agree with the original assumptions, the calculation is repeated until they do agree. In this way all the important thermodynamic parameters are found as a self-consistent set subject only to the assumptions behind the equations used.     

Short scale heterogeneity in the lowermost mantle: insights from PcP-P and ScS-S data

We compare lateral variations at the base of the mantle as inferred from a global dataset of PcP-P travel time residuals, measured on broadband records, and existing P and S tomographic velocity models, as well as ScS-S travel time data in some selected regions. In many regions, the PcP-P dataset implies short scale lateral variations that are not resolved by global tomographic models, except under eastern Eurasia, where data and models describe a broad region of fast velocity anomalies across which variations appear to be of thermal origin. In other regions, such as central America and southeastern Africa, correlated short scale lateral variations (several hundred kilometers) are observed in PcP and ScS, implying large but not excessive values for the ratio R=∂ ln V_s/∂ ln V_p (∼2.5). On the other hand, in at least two instances, in the heart of the African Plume and on the edge of the Pacific Plume, variations in P and S velocities appear to be incompatible, implying strong lateral gradients across compositionally different domains, possibly also involving topography on the core-mantle boundary. One should be cautious in estimating R at the base of the mantle from global datasets, as different smoothing and sampling of P and S datasets may result in strong biases and meaningless results.     

New paleomagnetic constraints on the late Cretaceous and early Cenozoic tectonic history of the Eastern Pontides

The Pontides are characterized by a series of Mesozoic-Cenozoic fold belts comprising a N-vergent foreland fold and thrust belt in the Western Pontides and a concave, upward-shaped fold belt in the Eastern Pontides. The curvature of the fold belt follows the Caucasus which may imply a phase of oroclinal bending. In order to test whether the fold curvature represents a phase of oroclinal bending, a paleomagnetic study has been carried out in the Eastern Pontides on late Cretaceous and middle Eocene volcanic and sedimentary rocks from 29 sites. Rock magnetic studies reveal medium-temperature components with an unblocking temperature of 400–580 °C, indicating pseudo-single domain titanomagnetite as the most abundant carrier of magnetic remanence in the middle Eocene rocks studied here. In the upper Cretaceous rocks, a high-temperature component with an unblocking range of 580–650 °C was isolated. Stepwise thermal and alternating field demagnetization isolated two components of remanent magnetization in middle Eocene rocks comprising a low unblocking temperature/coercivity component near the present field direction and a characteristic remanent magnetization (ChRM) component of D_s = 332.3°, I_s = 49.9° (k = 33.3, α₉₅ = 9.2°, N = 15 sites). A positive fold test at a 95% confidence level and a reversal test indicate a primary magnetization. Component analysis of the upper Cretaceous rocks identifies a stable ChRM D_s = 160.3°, I_s = −45.0°, (k =  85.6, α₉₅ = 6.0°, N =  8 sites) following removal of secondary remanence. Their ChRM direction passes fold and reversal tests at a 95% confidence level. Both the upper Cretaceous and middle Eocene paleomagnetic data from the Eastern Pontides and the Lesser Caucasus clearly demonstrate evidence of oroclinal bending that occurred contemporaneouslywith the convergence between Arabia and Eurasia in the Paleocene.     

The effect of wave-induced turbulence on intertidal mudflats: Impact of boat traffic and wind

Semi-diurnal and fortnightly surveys were carried out to quantify the effects of wind- and navigation-induced high-energy events on bed sediments above intertidal mudflats. The mudflats are located in the upper fluvial part (Oissel mudflat) and at the mouth (Vasière Nord mudflat) of the macrotidal Seine estuary. Instantaneous flow velocities and mudflat bed elevation were measured at a high frequency and high resolution with an acoustic doppler velocimeter (ADV) and an ALTUS altimeter, respectively. Suspended particulate matter concentrations were estimated by calibrating the ADV acoustic backscattered intensity with bed sediments collected at the study sites. Turbulent bed shear stress values were estimated by the turbulent kinetic energy method, using velocity variances filtered from the wave contribution. Wave shear stress and maximum wave–current shear stress values were calculated with the wave–current interaction (WCI) model, which is based on the bed roughness length, wave orbital velocities and the wave period (T_S). In the fluvial part of the estuary, boat passages occurred unevenly during the surveys and were characterized by long waves (T_S>50 s) induced by the drawdown effect and by short boat-waves (T_S<10 s). Boat waves generated large bottom shear stress values of 0.5 N m⁻² for 2–5 min periods and, in burst of several seconds, larger bottom shear stress values up to 1 N m⁻². At the mouth of the estuary, west south-west wind events generated short waves (T_S<10 s) of H_S values ranging from 0.1 to 0.3 m. In shallow-water environment (water depth <1.5 m), these waves produced bottom shear stress values between 1 and 2 N m⁻². Wave–current shear stress values are one order of magnitude larger than the current-induced shear stress and indicate that navigation and wind are the dominant hydrodynamic forcing parameters above the two mudflats. Bed elevation and SPM concentration time series showed that these high energy events induced erosion processes of up to several centimetres. Critical erosion shear stress (τ_ce) values were determined from the SPM concentration and bed elevation measurements. Rough τ_ce values were found above 0.2 N m⁻² for the Oissel mudflat and about 1 N m⁻² for the Vasière Nord mudflat.     

Spatial distribution of polyfluoroalkyl compounds in dab (Limanda limanda) bile fluids from Iceland and the North Sea

The spatial distribution of polyfluoroalkyl compounds (PFCs) was investigated in dab (Limanda limanda) bile fluids collected from Iceland and the North Sea. Concentrations of various PFCs, including perfluorinated sulfonates (C₄-C₆, C₈ PFSAs), perfluorinated carboxylic acids (C₉-C₁₄ PFCAs) and n-methyl perfluorooctane sulfonamidoethanol (MeFOSE), were quantified. Perfluorooctane sulfonate (PFOS) was the predominant compound with highest concentrations along the Danish and German coast (mean 9.36 ng/g wet weight (ww)). Significantly lower PFOS concentrations were found at the other sampling stations in the North Sea and Iceland (p < 0.01, t-test). Conversely, the spatial distribution of the PFCAs in Iceland and the North Sea was more uniform. The most abundant PFCA was perfluorononanoic acid (PFNA), while the mean concentration decreased with increasing chain length from 4.7 ng/g ww for PFNA to 0.04 ng/g ww for perfluorotetradecanoic acid (PFTeDA). Overall, the different spatial distribution of PFCs indicates different origin of sources and different transportation mechanism.     

Hot springs mediate spatial exchange of heat and mass in the enclosed sediment domain: A stability perspective

In many natural environments, such as in underwater hot springs and hydrothermal vents, thermal gradients are accompanied with changes in the concentration of chemical compounds transported to the seawater, causing the so-called double-diffusive, mixed convection. To study the physical scenarios in such systems, a vertical channel filled with a porous medium saturated with saline water is considered. The motion in the sediment-filled channel is induced by two buoyancy forces and an external pressure gradient, similar to the situation in a vent with an upward flow direction. The fluid flow has been modeled by an extended Darcy model, and the flow instability mechanisms have been studied numerically. The linear stability analysis is performed considering a wide range of Darcy number (Da = 10⁻⁵ -10⁻⁸). The instability boundary curve showed three distinct dynamic regimes: (i) Rayleigh-Taylor (R-T), (ii) log-log non-linear variation, and (iii) log-log linear variation. The domain of different regimes were sensitive to external pressure gradient as well as permeability. Similar to cross-diffusive natural convection in pure viscous fluids, a linear relationship between logarithmic absolute values of critical thermal Rayleigh number (∣Ra_T∣) and solute Rayleigh number (Ra_C) is found in the third regime. Based on the permeability, for any solute Rayleigh number (Ra_C), there existed a minimum value of Reynolds number (Re), below which R-T type of instability appeared. Above this minimum value, the instability was due to two buoyancy forces, known as buoyant instability. Simulations of secondary flow via energy analysis demonstrated the development of complex dynamics at the critical state in all three regimes characterized by transition of multi to uni-cellular structures and vice verse.     

Terrestrial and marine biomarker estimates of organic matter sources and distributions in surface sediments from the East China Sea shelf

Revealing of the sources and distributions of sedimentary organic matter in the East China Sea (ECS) is important for understanding its carbon cycle, which has significant temporal and spatial variability due to the influences of recent climate changes and anthropogenic activities. In this study, we report the contents of both terrestrial and marine biomarkers including ∑C₂₇+C₂₉+C₃₁n-alkanes (38.6-580 ng/g), C₃₇ alkenones (5.6-124.6 ng/g), brassicasterol (98-913 ng/g) and dinosterol (125-1521 ng/g) from the surface sediments in the Changjiang River Estuary (CRE) and shelf areas of the ECS. Several indices based on biomarker contents and ratios are calculated to assess the spatial distributions of both terrestrial and marine organic matter in the ECS surface sediments, and these results are compared with organic matter distribution patterns revealed by the δ¹³C (−20.1‰ to −22.7‰) and C/N ratio (5-7.5) of total organic matter. The contents of terrestrial biomarkers in the ECS surface sediments decrease seaward, controlled mostly by Changjiang River (CR) inputs and surface currents; while higher contents of the two marine biomarkers (brassicasterol and dinosterol) occur in upwelling areas outside the CRE and in the Zhejiang-Fujian coastal zone, controlled mostly by marine productivity. Four proxies, f_Terr(δ¹³C) (the fraction of terrestrial organic matter in TOC estimated by TOC δ¹³C), odd-alkanes (∑C₂₇+C₂₉+C₃₁n-alkanes), 1/P_mar-aq ((C₂₃+C₂₅+C₂₉+C₃₁)/(C₂₃+C₂₅) n-alkanes) and TMBR (terrestrial and marine biomarker ratio) (C₂₇+C₂₉₊C₃₁n-alkanes)/((C₂₇+C₂₉+C₃₁) n-alkanes+(brassicasterol+dinosterol+alkenones)), reveal a consistent pattern showing the relative contribution of terrestrial organic matter (TOM) is higher in the CRE and along the Zhejiang-Fujian coastline, controlled mostly by CR inputs and currents, but the TOM contribution decreases seaward, as the influences of the CR discharge decrease.     

Hydroclimatology of the Volta River Basin in West Africa: Trends and variability from 1901 to 2002

Long-term historical records of rainfall (P), runoff (Q) and other climatic factors were used to investigate hydrological variability and trends in the Volta River Basin over the period 1901-2002. Potential (E_p) and actual evaporation (E), rainfall variability index (δ), Budyko’s aridity index (I_A), evaporation ratio (C_E) and runoff ratio (C_Q) were estimated from the available hydroclimatological records. Mann-Kendall trend analysis and non-parametric Sen’s slope estimates were performed on the respective time series variables to detect monotonic trend direction and magnitude of change over time.Rainfall variability index showed that 1968 was the wettest year (δ = +1.75) while 1983 was the driest (δ = −3.03), with the last three decades being drier than any other comparable period in the hydrological history of the Volta. An increase of 0.2 mm/yr² (P < 0.05) was observed in E_p for the 1901-1969 sub-series while an increased of 1.8 mm/yr² (P < 0.01) was recorded since 1970. Rainfall increased at the rate of 0.7 mm/yr² or 49 mm/yr between 1901 and 1969, whereas a decrease of 0.2 mm/yr² (6 mm/yr) was estimated for 1970-2002 sub-series. Runoff increased significantly at the rate of 0.8 mm/yr (23 mm/yr) since 1970. Runoff before dam construction was higher (87.5 mm/yr) and more varied (CV = 41.5%) than the post-dam period with value of 73.5 mm/yr (CV = 23.9%). A 10% relative decrease in P resulted in a 16% decrease in Q between 1936 and 1998. Since 1970, all the months showed increasing runoff trends with significant slopes (P < 0.05) in 9 out of the 12 months. Possible causes, such as climate change and land cover change, on the detected changes in hydroclimatology are briefly discussed.     

The influence of bed forms on reference concentration and suspension under waves and currents

Hydrodynamic, suspension and bed-form measurements were made 2 km off the Dutch coast near Noordwijk aan Zee in ∼14 m water depth for a period of 32 days in 2003. Tidal currents were just able to suspend sand at the bed at peak spring tide but most suspension and transport occurred as a result of the combination of waves and currents. Burst-average (17 min) sand concentration profiles (C¯-profiles) from an acoustic backscatter instrument were used to define the (varying) location of the sea-bed, following the method used by Green et al. [Green, M.O., Dolphin, T.J., Swales, A., Vincent, C.E., 1999. Transport of mixed-size sediments in a tidal channel. Coastal Sediments ‘99, edited by N.C. Kraus, and W.G. McDougal, ASCE, Long Island, New York, pp. 644–658]. Reference concentrations at the sea-bed (C₀) and at 1 cm (C₁) were examined in relation to both the hydrodynamic conditions and the type of bed forms present. The C₀ predictive equations of Green and Black [Green, M.O., Black, K.P., Suspended sediment reference concentration under waves: field measurements and critical analysis of two predictive models, Coastal Engineering, 38, 115–141, 1999](short-wave ripples) and Nielsen [Nielsen, P., Suspended sediment concentrations under waves, Coastal Engineering, 10, 23–31, 1986](all bed forms; includes ripple steepness), both of which require knowledge of the bed-form type, were not as successful in explaining the variance in our C₀ data as a regression of C₀ against the skin-friction Shields parameter θ′_cw that ignored bed-form type (73% of variance explained). The values of the reference concentration C₁ were compared with the Lee et al. [Lee, G.-H., Dade, W.B., Friedrichs, C.T., Vincent, C.E., Examination of Reference Concentration Under Waves and Currents on the Inner Shelf., Journal of Geophysical Research, 109, 1–10, 2004] equation which predicts C₁ from the product of the Shields parameter and the inverse Rouse parameter; 51% of the variance in C₁ was explained.     

Seasonal contribution of living phytoplankton carbon to vertical fluxes in a coastal upwelling system (Ría de Vigo, NW Spain)

The aim of this study is to explore the contribution of living phytoplankton carbon to vertical fluxes in a coastal upwelling system as a key piece to understand the coupling between primary production in the photic layer and the transfer mechanisms of the organic material from the photic zone. Between April 2004 and January 2005, five campaigns were carried out in the Ría de Vigo (NW Iberian Peninsula) covering the most representative oceanographic conditions for this region. Measurements of particulate organic carbon (POC), chlorophyll-a (chl a), phaeopigments (phaeo), and identification of phytoplankton species were performed on the water column samples and on the organic material collected in sediment traps.The POC fluxes measured by the sediment traps presented no seasonal variation along the studied period ranging around a mean annual value of 1085±365 mg m⁻² d⁻¹, in the upper range of the previously reported values for other coastal systems. The fact that higher POC fluxes were registered during autumn and winter, when primary production rates were at their minimum levels points to a dominant contribution of organic carbon from resuspended sediments on the trap collected material. On the contrary, fluxes of living phytoplankton carbon (C_phyto) and chl a clearly presented a seasonal trend with maximum values during summer upwelling (546 mg m⁻² d⁻¹ and 22 mg chl a m⁻² d⁻¹, respectively) and minimum values during winter (22 mg m⁻² d⁻¹ and 0.1 mg chl a m⁻² d⁻¹, respectively). The contribution of C_phyto to the vertical flux of POC ranged between 2% and 49% in response to the pelagic phytoplankton community structure. Higher values of C_phyto fluxes were registered under upwelling conditions which favour the dominance of large chain-forming diatoms (Asterionellopsis glacialis and Detonula pumila) that were rapidly transferred to the sediments. By contrast, C_phyto fluxes decreased during the summer stratification associated with a pelagic phytoplankton community dominated by single-cell diatoms and flagellates. Minimal C_phyto fluxes were observed during the winter mixing conditions, when the presence of the benthic specie Paralia sulcata in the water column also points toward strong sediment resuspension.     

Height stratification and polar reversal of the Sun’s magnetic fields in cycles 21–23

Using calculations of the magnetic field in the solar atmosphere in the potential approximation, it is shown that, (1) as distance R from the Sun’s center grows, the area of the positive magnetic field (S _+field) in 10-deg latitude zones tends to 100% (0%) in the neighborhood of the solar minimum. At the distance R = 2.5R _⊙(R _⊙ is the solar radius), these values of the positive field are observed during ≈(12–55) Carrington rotations (CRs) for solar minima between neighboring cycles; (2) polar magnetic field reversals can occur repeatedly. Note that a polar reversal at large heights ends by 6–16 Carrington rotations earlier than on the Sun’s surface. On the Sun’s surface, a field polar reversal begins earlier at lower latitudes than at high ones; (3) for each longitude at different Rs and separately for each solar hemisphere the radial component of the field was averaged on synoptic maps in the 0°–40° latitude range. It is established that the T _R rotation periods of the boundaries between the sectors (areas of longitudes with the same sign of the averaged field) can be shorter than, longer than, and equal to Carrington solar rotation period T _CR. It turned out that boundaries with T _R < T _CR are observed at all heights, while boundaries with T _R > T _CR are observed at relatively small heights.     

Distribution of synthetic organotins and total tin levels in Mytilus galloprovincialis along the Portuguese coast

Despite the huge amount of literature available on butyltins (BuTs), few studies addressed the environmental levels of phenyltins (PhTs), octyltins (OcTs) and total tin (Sn_T) in environmental samples. In 2006 a mussel watch survey was developed for the Portuguese coast (total of 29 sampling sites) in order to describe the concentrations of BuTs , PhTs, OcTs and Sn_T in the whole tissues of Mytilus galloprovincialis (Lamarck, 1819). BuTs were detected in all analyzed samples accounting, in average, for 98.6% of total organotins (∑OTs = BuTs + PhTs + OcTs), and presented highest values in the vicinity of harbors. Tributyltin (TBT) was the dominant butyltin, representing, in average, 62% of ∑BuTs (∑BuTs = TBT + DBT + MBT) suggesting that fresh inputs of TBT are still occurring in the Portuguese coast, particularly near harbors. The contribution of organotin compounds derived from antifouling paints to the total tin levels in M. galloprovincialis is discussed.     

The crystal structure and thermal history of orthopyroxene from lunar anorthosite 15415

A single crystal of untwinned orthopyroxene from lunar anorthosite sample 15415, with composition (Mg_1.14Fe_0.80Mn_0.02Ca_0.04)(Si_1.97Al_0.03)O₆, has a unit cell in space groupPbca witha = 18.310(15)Å,b = 8.904(10)Å,c = 5.214(7)Å, containing 2 formula units. A set of 742 counter-measured intensity data made with MoK_α radiation has been used to refine the crystal structure in isotropic thermal mode toR = 0.116. Anisotropic refinement led toR = 0.092, but thermal parameters are distorted by non-random errors resulting from poor crystal texture. The resulting structure is in close agreement with that obtained by Ghose [9] for a hypersthene from Greenland. A parameterq, which gives (Mg_qFe_1?q) for cation siteM(1) and (Mg_1.14?qFe_q?0.18Ca_0.04) for siteM(2), was included in the least-squares analysis, yieldingq = 0.90(1).This orthopyroxene has the high degree of cation order expected of pyroxenes subjected to Apollonian metamorphism at lower than 500–600°C. No evidence exists for a subsequent thermal event of sufficient intensity to disorder the pyroxene. On the basis of previous laboratory studies of argon-release patterns of lunar plagioclase and order-disorder kinetics of terrestrial pyroxenes, we attribute the reported isotopic age (3.9–4.1 AE) to cessation of metamorphism, perhaps caused by impact excavation.     

Effects of alumina refinery wastewater and signature metal constituents at the upper thermal tolerance of: 2. The early life stages of the coral Acropora tenuis

The success of early life history transitions of the coral Acropora tenuis were used as endpoints to evaluate thermal stress and the effects of wastewater discharged to a tropical marine environment. The studies assessed the effects of: (i) temperature; (ii) three signature metals of the wastewater, aluminium (Al), vanadium (V) and gallium (Ga); and (iii) the wastewater (at 27 °C and 32 °C) on fertilisation and larval metamorphosis. The median inhibition temperatures for fertilisation and metamorphosis were 32.8 °C and 33.0 °C, respectively. Fertilisation IC₅₀s for Al, V and Ga were 2997, 2884 and 3430 μg L⁻¹, respectively. Metamorphosis IC₅₀s for Al, V and Ga were 1945, 675 and 3566 μg L⁻¹, respectively. The wastewater only affected fertilisation and metamorphosis at moderate concentrations (IC₅₀s = 63% and 67%, v/v, respectively, at 27 °C), posing a low risk to this species in the field. The effects of wastewater and temperature on fertilisation and metamorphosis were additive.     

Volume-temperature relationship for iron at 330 GPa and the Earth's core density deficit

Estimates of core density deficit (cdd) of the Earth's outer core recently reported by Anderson and Isaak [Another look at the core density deficit of Earth's outer core, Phys. Earth Planet Int. 131 (2002) 19-27] are questionable in view of the serious errors in the pressure-volume and bulk modulus data due to an inadequacy in the calibration process used by Mao et al. [Static compression of iron to 300 GPa and Fe_0.8Ni_0.2 alloy to 200 GPa: implications for the core, J. Geophys. Res. 94 (1990) 21737-21742]. The data used by Anderson and Isaak deviate significantly from the corresponding values derived from seismology. In the present study we have used the input data on density, isothermal bulk modulus and its pressure derivative from Stacey and Davis [High pressure equations of state with application to lower mantle and core, Phys. Earth Planet Int. 142 (2004) 137-184] which are consistent with the seismological data. Volumes of hexagonal close-packed iron have been calculated at different temperatures under isobaric conditions at P = 330 GPa, the inner core boundary (ICB) pressure using the relationship between thermal pressure and volume expansion based on the lattice potential theory originally due to Born and Huang [Dynamical Theory of Crystal Lattices, Oxford University Press, Oxford, 1954, p. 50]. The formulation for thermal pressure used by Anderson and Isaak has been modified by taking into account the variations of thermal expansivity α and isothermal bulk modulus K_T with temperature. Values of cdd are then estimated corresponding to different temperatures ranging from 4000 to 8000 K. The results for cdd at different temperatures obtained in the present study are significantly higher than those estimated by Anderson and Isaak suggesting that the cdd for the Earth's outer core is nearly 10%. The effects of nickel when an Fe-Ni alloy replaces Fe are estimated and found to be insignificant.     

Effects of alumina refinery wastewater and signature metal constituents at the upper thermal tolerance of: 1. The tropical diatom Nitzschia closterium

Ecotoxicological studies, using the tropical marine diatom, Nitzschia closterium (72-h growth rate), were undertaken to assess potential issues relating to the discharge from an alumina refinery in northern Australia. The studies assessed: (i) the species’ upper thermal tolerance; (ii) the effects of three signature metals, aluminium (Al), vanadium (V) and gallium (Ga) (at 32 °C); and (iii) the effects of wastewater (at 27 and 32 °C). The critical thermal maximum and median inhibition temperature for N. closterium were 32.7 °C and 33.1 °C, respectively. Single metal toxicity tests found that N. closterium was more sensitive to Al compared to Ga and V, with IC₅₀s (95% confidence limits) of 190 (140-280), 19,640 (11,600-25,200) and 42,000 (32,770-56,000) μg L⁻¹, respectively. The undiluted wastewater samples were of low toxicity to N. closterium (IC₅₀s > 100% wastewater). Environmental chemistry data suggested that the key metals and discharge are a very low risk to this species.