Solar Rotational Periodicities and the Semiannual Variation in the Solar Wind, Radiation Belt, and Aurora

The behavior of a number of solar wind, radiation belt, auroral and geomagnetic parameters is examined during the recent extended solar minimum and previous solar cycles, covering the period from January 1972 to July 2010. This period includes most of the solar minimum between Cycles 23 and 24, which was more extended than recent solar minima, with historically low values of most of these parameters in 2009. Solar rotational periodicities from 5 to 27 days were found from daily averages over 81 days for the parameters. There were very strong 9-day periodicities in many variables in 2005?–?2008, triggered by recurring corotating high-speed streams (HSS). All rotational amplitudes were relatively large in the descending and early minimum phases of the solar cycle, when HSS are the predominant solar wind structures. There were minima in the amplitudes of all solar rotational periodicities near the end of each solar minimum, as well as at the start of the reversal of the solar magnetic field polarity at solar maximum (～?1980, ～?1990, and ～?2001) when the occurrence frequency of HSS is relatively low. Semiannual equinoctial periodicities, which were relatively strong in the 1995?–?1997 solar minimum, were found to be primarily the result of the changing amplitudes of the 13.5- and 27-day periodicities, where 13.5-day amplitudes were better correlated with heliospheric daily observations and 27-day amplitudes correlated better with Earth-based daily observations. The equinoctial rotational amplitudes of the Earth-based parameters were probably enhanced by a combination of the Russell-McPherron effect and a reduction in the solar wind-magnetosphere coupling efficiency during solstices. The rotational amplitudes were cross-correlated with each other, where the 27-day amplitudes showed some of the weakest cross-correlations. The rotational amplitudes of the >?2 MeV radiation belt electron number fluxes were progressively weaker from 27- to 5-day periods, showing that processes in the magnetosphere act as a low-pass filter between the solar wind and the radiation belt. The A _p/K _p magnetic currents observed at subauroral latitudes are sensitive to proton auroral precipitation, especially for 9-day and shorter periods, while the A _p/K _p currents are governed by electron auroral precipitation for 13.5- and 27-day periodicities.     

Multisite campaign on the open cluster M67 – I. Observations and photometric reductions

We report on an ambitious multisite campaign aimed at detecting stellar variability, particularly solar-like oscillations, in the red giant stars in the open cluster M67 (NGC 2682). During the six-week observing run, which comprised 164 telescope nights, we used nine 0.6-m to 2.1-m class telescopes located around the world to obtain uninterrupted time series photometry. We outline here the data acquisition and reduction, with emphasis on the optimization of the signal-to-noise ratio of the low-amplitude (50–500 μmag) solar-like oscillations. This includes a new and efficient method for obtaining the linearity profile of the CCD response at ultrahigh precision (∼10 parts per million). The noise in the final time series is 0.50 mmag per minute integration for the best site, while the noise in the Fourier spectrum of all sites combined is 20 μmag. In addition to the red giant stars, this data set proves to be very valuable for studying high-amplitude variable stars such as eclipsing binaries, W UMa systems and δ Scuti stars.     

Health of red morwong, Cheilodactylus fuscus, and rock cale, Crinodus lophodon, from Sydney cliff-face sewage outfalls

Health of red morwong, Cheilodactylus fuscus and rock cale, Crinodus lophodon was assessed using histology to determine effects of the Sydney cliff outfalls on these two species. Ten individuals of each species were sampled from three outfall sites and three control sites. Benign epitheliocystis, presence of metazoan parasites, epithelial lifting, telangiectasis, haemorrhage and inflammation were found in the gills of some individuals. Hemosiderin was present in melanomacrophage aggregates in liver and spleen of some fish and also in kidneys of a few fish collected in Malabar outfall site. Hyaline droplets were present in tubular epithelium in kidney of some fish, particularly in the individuals collected from Malabar. Although for some changes there was a trend of greater prevalence at the outfall sites, there was no statistically significant difference between the fish from outfall sites and control sites. Most changes were species specific and the differences were statistically significant. This suggests problems with extrapolating results from one species to others. Greater replication, smaller range of size, chemical analysis of tissue residues as well as better knowledge of the fate of sewage and oceanographic processes would improve interpretation of any future surveys. A multidisciplinary approach would be most beneficial for pollution studies.     

Carbon Isotope Analysis to Evaluate Nanoscale Fe(O) Treatment at a Chlorohydrocarbon Contaminated Site

Remediation of groundwater contaminated by chlorinated hydrocarbons via in situ technologies such as direct injection of nanoscale zero valent iron (ZVI, Fe(O)) particles is increasingly common. However, assessing target compound degradation by abiotic processes is difficult because (1) the injection may displace the contaminant plume so that concentration measurements alone are often inconclusive and (2) biodegradation may also occur, making it challenging to identify and evaluate the abiotic degradation component. In this study, trichloroethylene (TCE) and 1,1,1-trichloroethane (1,1,1-TCA) were treated in a highly heterogeneous hydrogeologic setting. The purpose of this study was to evaluate the potential for compound-specific stable isotope analysis (CSIA) to monitor the effectiveness of ZVI injection by assessing TCE and 1,1,1-TCA degradation. Prior to ZVI injection, carbon isotope measurements demonstrated biodegradation of TCE by native microorganisms. This in situ biodegradation was quantified by measuring the enrichment of ¹³C in TCE samples downstream of the suspected source. When ZVI was injected through only two injection wells, no changes in TCE and 1,1,1-TCA isotope signatures were detected compared to preinjection values. In contrast, when ZVI was injected through 11 wells covering a greater portion of the contaminated area, 5 out of 10 monitoring wells showed further enrichment of ¹³C in either TCE or 1,1,1-TCA, indicating additional target compound transformation. The abiotic nature of this TCE transformation was confirmed through temporal trends in carbon isotope values of the putative transformation products cis-dichloroethylene (cis-DCE), ethene and ethane. This demonstrates the usefulness of CSIA in distinguishing abiotic vs. biotic transformation in the field.     

Turbulence Reynolds number and the turbulent kinetic energy balance in the atmospheric surface layer

The relation between the turbulence Reynolds numberR and a Reynolds numberz* based on the friction velocity and height from the ground is established using direct measurements of the r.m.s. longitudinal velocity and turbulent energy dissipation in the atmospheric surface layer. Measurements of the relative magnitude of components of the turbulent kinetic energy budget in the stability range 0 >z/L 0.4 indicate that local balance between production and dissipation is maintained. Approximate expressions, in terms of readily measured micrometeorological quantities, are proposed for the Taylor microscale and the Kolmogorov length scale .     

The evolution of a quasar population based on a simple source model

The cosmological evolution of a population of quasars and AGNs is considered. The applied source model provides that the star collisions in the central stellar system should be the principal mechanism of supply of the gas falling on to the black hole. The continuity equation for the assumed population is solved for the zero birth function as well as for its special type. The solutions obtained depend on the distribution of two parameters characterizing a single source: the radius of stellar core and the number of stars in the system. All these solutions allow to describe practically whole evolutionary track of the considered source population, and to relate the evolution to some features of a single source.     

Scale and timing of Rare Earth Element redistribution in the Taconian foreland of New England

Clastic sedimentary rocks, deposited on eastern North America in response to the Taconian Orogeny, commonly have Sm/Nd isotope relationships indicating substantial isotope disturbance near or subsequent to the time of sedimentation that may be associated with severe depletion in light rare earth elements (LREE). Affected units [Normanskill Formation (Austin Glen and Pawlet Members), Frankfort Formation and Perry Mountain Formation] are widely separated both geographically (western New York to western Maine) and stratigraphically (Middle Ordovician to Silurian). A model is proposed for the most likely explanation of the observed REE and Sm/Nd isotope relationships involving a two‐stage process. In the first stage, REE are redistributed on a mineralogical scale (dissolution/precipitation on a sample scale) often with the involvement of REE‐enriched trace phases such as apatite and monazite. This stage typically takes place during diagenesis but may also take place later during metamorphism and/or recent weathering, and results in isotope re‐equilibration on a sample scale. The second stage occurs when one or more of these phases is redissolved and REE are transported on large advective scales. Where LREE‐enriched phases are involved, this gives rise to LREE depletion in whole rocks. The timing of this second stage cannot be constrained from Sm/Nd isotope data and may take place at any time subsequent to the isotope re‐equilibration. Such complex histories of REE redistribution may result in serious errors in estimating Nd model ages but not in estimating the Nd isotope composition at the age of sedimentation. Thus, Sm/Nd ratios even of unmetamorphosed sedimentary rocks have to be carefully evaluated before the calculation of depleted mantle model ages for the provenance.     

Evolution of groundwater quality in intensive agricultural zone: case of Chtouka-Massa Aquifer,Morocco

The Chtouka-Massa area in Southern Morocco has shown an increase in water scarcity during the last decades, caused mainly by withdrawal of water resources aggravated by agricultural intensification and climate change impacts. To better understand the changes of groundwater quality, a sampling campaign was conducted in many wells during March 2015 and compared to historical chemical data from the hydraulic basin agency, as well as previous studies performed at Ibn Zohr University. All data were used to assess the spatial-temporal evolution of nitrate and salinity relevant to the recent sampling. This paper describes the current state of groundwater quality in the Chtouka-Massa zone with an overview of different sources of water mineralization and the nitrate evolution in an agricultural area. Our results indicate a general increase in mineralization from the north to the south, and from the east to the west. The plain, dominated by farms, shows a relatively high conductivity (up to 2000 μS/cm), while in both costal area and Anti-Atlas Mountain the water salinity shows a gradient increase from the north to the south. However, the highest electrical conductivity is observed along the Massa River. The water type is bicarbonate, chloride, and sodium for farm samples, while from the other parts, it is mostly dominated by chloride and sodium. The spatial-temporal analysis of nitrates generally shows an increasing trend. However, the levels remain overall lower than the limit. The temporal evolution of control points set by the hydraulic agency shows a decreasing trend decline that can be explained by the improvement of agriculture practices, including the conversion towards drip irrigation mode. Different chemical tracers highlighted some processes involving the changes of mineralization of groundwater (e.g., irrigation water return, marine intrusion, and water/rock interaction). The results will be used to improve water management in this area showing water quality degradation.