The stable aryl hydrocarbon receptor agonist potency of United Kingdom Continental Shelf (UKCS) offshore produced water effluents

The in vitro aryl hydrocarbon receptor (AhR) agonist potency of offshore produced water effluents, collected from the United Kingdom Continental Shelf, was determined using the dioxin responsive (DR)-chemically activated luciferase expression (CALUX) assay. Octadecylsilane (C18) solid phase extraction (SPE) extracts of produced water were exposed to DR-CALUX cells for 24 h in order to investigate the contribution in potency from compounds that are stable to metabolism by the CALUX cells during exposure. The stable AhR agonist potency determined over 24 h was highly variable and ranged from 1 to 430 ng TCDD TEQ_CALUX l⁻¹. These data reflect the highly variable composition of produced water discharges from different production fields. It is recommended that further work be performed to characterise the full range of stable dioxin like AhR agonists present in offshore produced water discharges using techniques such as bioassay-directed analysis.     

Some thermodynamical and microphysical aspects of monsoon clouds

The thermodynamical and microphysical characteristics of monsoon clouds in the Poona, Bombay and Rihand regions were investigated using extensive aircraft in-cloud observations. The number of clouds sampled at Poona, Bombay and Rihand is 2199, 169 and 104 respectively. The temperatures inside the cloud are colder than its environment at Poona and Rihand. The maximum difference is about 3°C at the cloud base level and the difference decreased with height. At Bombay the difference is less than 1°C and at some levels the temperatures inside the cloud are warmer than its environment. The lapse rates of temperatures inside the cloud are slightly less than those in the immediate environment of the cloud. The environmental lapse rates are nearly equal to the saturated adiabatic value. The positive increments in liquid water content (LWC) are associated with the increments in temperature inside the cloud. Similarly positive increments in temperatures inside the cloud are associated with the increments in temperature of its immediate environment at the same level or the layer immediately above. The maximum cloud lengths observed at Poona and Bombay respectively are 14 and 3 km. The horizontal cross-section of LWC showed a maximum number of 13 peaks in clouds at Poona while only 7 peaks were observed at Bombay. The location of maximum LWC in the horizontal cross-section is more or less at the centre of the cloud. The LWC profile showed an increase with height from the base of the cloud at Poona and Bombay. There is no marked variation of LWC with height at Rihand. The total droplet concentration at different altitudes at Poona and Bombay is in the range 28–82 cm^?3. The size distribution of cloud droplets experienced a broadening effect with increase in height from the cloud base at Poona. The broadening effect at Bombay is not as marked as that at Poona.     

Regional conductance map of Andaman and Nicobar region

To image the electrical conductivity distribution, fluxgate magnetometers are operated at five sites in Andaman and Nicobar region. Transfer functions are estimated for the period range 8–128 min, from nighttime transient geomagnetic variations, using robust regression analysis. The observed induction arrows in Andaman Islands are found to point towards east despite deep sea located towards its west. This indicates that fore-arc basin (Andaman–Nicobar deep) is more conducting than the region of outer non-volcanic Island arc.Thin sheet model requires the conductance of 10,000–35,000 S (with increase conductivity towards the south) for explaining the observed induction pattern. The observed induction pattern at Andaman–Nicobar stations can be explained in terms of high conducting Cretaceous–Tertiary sediments filling the Andaman–Nicobar deep. High conductivity over Invisible bank has been attributed to the partial melts/volatile fluids derived from the subducting Indian plate that are intruding into the eastern margin of fore-arc basin through the West Andaman Fault (WAF).The induction pattern at Great Nicobar station (Campbell Bay) may be related to the highly conducting sediments filling the Mergui basin along with mafic intrusions. Also crustal transition occurs below the Mergui Terrace at the Malayan coast contributing to the enhanced conductivity anomaly.     

The Coolgardie Goldfied,Western Australia: district-scale controls on an Archaean gold camp in an amphibolite facies terrane

Archaean lode gold deposits in the Coolgardie Goldfield, Western Australia, occur in mafic and ultramafic rocks which have been metamorphosed to the amphibolite facies. Mineralisation was broadly synchronous with peak metamorphism, the main phase of granitoid emplacement, and regional deformation. Several different structural styles are represented by the deposits of the Coolgardie Goldfield. Mineralisation occurs along sheared felsic porphyry-ultramafic rock contacts, in gabbro-hosted quartz-vein sets, in fault-bounded quartzvein sets, and in laminated quartz reefs sited in brittleductile shear zones. The structures hosting mineralisation formed in response to a progressive deformation event, related to granitoid emplacement in an east-west compressional far-field stress régime, but with local heterogeneous stress orientations. This occurred after an earlier period of thrust-stacking, with probable north-south directed tectonic transport. Two contrasting styles of goldrelated wallrock alteration are associated with the auriferous lodes of the Coolgardie Goldfield. A high-temperature assemblage (formation temperature >500°C), characterised by the proximal alteration assemblage garnet+ hornblende + plagioclase + pyrrhotite, contrasts with a medium-temperature assemblage (formation temperature <500°C), consisting of calcic amphibole + biotite + plagioclase + calcite + arsenopyrite + pyrrhotite. The distribution of the two styles of gold-related alteration is controlled by distance from voluminous syntectonic granitoids located to the west of the Coolgardie Goldfield, with the high-temperature style of alteration more proximal to the granitoid-greenstone contact than the medium-temperature style. The occurrence of gold deposits that formed under amphibolite facies conditions throughout the Coolgardie Goldfield supports a crustal continuum model for Archaean lode-gold deposits, which proposes that gold is deposited in metamorphic environments that range from the sub-greenschist to granulite facies. In addition, the data from Coolgardie suggest that syntectonic, synmineralisation granitic plutons may play a significant role in controlling the style of gold associated wallrock-alteration at deep crustal levels.     

Sporadic and recurrent geomagnetic disturbances in 1859–1860 according to the archived data from the Russian network of stations

Based on an analysis of the available archived data from the Russian network of geomagnetic stations, it has been indicated that the known event of August–September 1859 was the first and the greatest event in the series of the recurrent geomagnetic storms. Similar series were repeatedly observed in the next years. These series are caused by the processes on the Sun and in the heliosphere related to the superposition of the solar wind flows. The sporadic and regular components in joint activity of the complex, including active regions and coronal holes on the rotating Sun, play the role of the Bartels M regions responsible for initiation and development of geomagnetic storms. Neither coronal holes nor active regions can separately explain observations. During interpretation, active regions and coronal holes should be considered as a unified complex.     

Investigation by backscatter radar of artificial irregularities produced in ionospheric plasma heating experiments

The artificial ionospheric turbulence occurs in the ionosphere illuminated by high power HF radio waves. There are a lot of irregularities stretched along the geomagnetic field in this region. The investigation of the artificially disturbed ionospheric region is based on the reception of back scattered signals (BSS) which permits the basic parameters of this region to be estimated and its inhomogeneous structure to be described.Experiments were carried out using ‘Sura’ heating facility in the frequency range of ? = 4.7–9 MHz (ordinary mode) with the effective radiated power P_eff = 50–70 MW beamed vertically upwards. The most important dynamic and statistical BSS characteristics (the built-up time, the relaxation and autocorrelation times, the BSS amplitude spatial correlation function and power spectra) were measured using probe waves in the frequency range of that made it possible to obtain the basic parameters of the artificial irregularities. The model representation of a disturbed region in a form of a periodic structure gives a possibity to evaluate the scale of the structure, the whole size of the disturbance and its power and to calculate the main BSS characteristics.