Heavy mineral stratigraphy of the Unayzah Formation and Basal Khuff Clastics (Carboniferous to Permian) of Central Saudi Arabia

A study of heavy mineral assemblages in the Unayzah Reservoir sandstones of central Saudi Arabia has identified successive changes in provenance signature. These define four heavy mineral units that are of regional extent and largely coincident with the four main depositional units defined by previous authors: Unayzah C, Unayzah B, Unayzah A and the Basal Khuff Clastics. Sandstone bodies with anomalous mineral signatures also occur, however, especially within the Unayzah B Member. These are attributed to local supply of sand from pre-Unayzah Paleozoic sandstones exposed on the Central Arabian Arch and on intrabasinal highs. The stratigraphic changes in mineralogy reflect successive developments in the geography and climate of the region and in the pattern of sand sourcing and transport. The Unayzah C sands and the majority of Unayzah B sands were derived from the south but whereas the southerly derived Unayzah C sands appear to have been derived from pre-existing mature sandstones, those of Unayzah B were sourced from a wider range of rock types including crystalline basement. This contrast is interpreted as indicating that a significant hiatus may separate the two units. The Unayzah B sands are also characterised by the common presence of apatite, indicating that the source rocks were relatively unweathered. This observation is compatible with the glacial origin attributed to many of the Unayzah B sediments. A further change in provenance signature takes place at the base the newly recognised ‘un-named middle Unayzah member’, equivalent to the base of Unayzah A of previous authors. This is associated with the onset of red-bed sedimentation throughout the area. Unayzah A sedimentation was terminated by a fall in sea level that led to the formation of a widespread unconformity and to the development of deeply incised valleys along the western basin margin. In most of the study area this unconformity corresponds to the base of the Khuff Formation, but in the east of the area, where the succession is more complete, it is believed to occur within the Unayzah Formation, at a level equivalent to the base of the Upper Gharif Member of Oman. By identifying lateral and vertical changes in sand provenance, heavy mineral analysis provides an important additional tool in the stratigraphic analysis of the Permian sandstone succession of Saudi Arabia, both at the regional scale and wand at the scale of individual reservoir sandstone successions

Biogas from source separated organic waste within a circular and life cycle perspective. A case study in Ontario, Canada

Abstract The appropriate transformation and valorisation of biogas offers environmental and economic opportunities in a future with restrictions upon fossil-based fuels and materials. The LCA method was used to quantify and compare the potential environmental impacts of an AD plant incorporating biogas co-generation and upgrading options, namely AD-CHP and AD-RNG. Using an average Anaerobic Digestion facility in Ontario, Canada, modelled after real facilities, as a case study, electricity and steel were identified as potential hotspot input materials carrying a disproportionate environmental burden for biogas production. With a system expansion approach, the biogas was subsequently utilized to produce (1) both heat and electricity using a Combined Heat and Power (CHP) system, or (2) upgraded to renewable natural gas (also called biomethane) through chemical amine scrubbing, respectively. In comparing the biogas co-generation and upgrading options, the AD-CHP alternative resulted in a lesser environmental load, two times lower when compared to the AD-RNG biomethane recovery option. Furthermore, the avoided burden of producing fossil-based electricity, natural gas, and chemical fertilizer was analyzed and compared against their renewable counterparts. Significant reductions in emissions and in the depletion of fossil fuels were achieved, thus confirming the positive efforts of diverting organic waste from landfills to reduce organic waste disposal impacts and improve the management of organic waste. The analysis has provided useful insights to bioenergy project developers, policy makers and the scientific community regarding the processing of source separated organic waste, biogas production, and its upgrading alternatives in a circular economy perspective

What is the impact of public care on children's welfare? A review of research findings from England and Wales and their policy implications.

The outcomes for children in public care are generally considered to be poor. This has contributed to a focus on reducing the number of children in care: a goal that is made explicit in the provisions of the current Children and Young Persons Bill. Yet while children in care do less well than most children on a range of measures, such comparisons do not disentangle the extent to which these difficulties pre-dated care and the specific impact of care on child welfare. This article explores the specific impact of care through a review of British research since 1991 that provides data on changes in child welfare over time for children in care. Only 12 studies were identified, indicating a lack of research in this important area. The studies consistently found that children entering care tended to have serious problems but that in general their welfare improved over time. This finding is consistent with the international literature. It has important policy implications. Most significantly it suggests that attempts to reduce the use of public care are misguided, and may place more children at risk of serious harm. Instead, it is argued that England and Wales should move toward a Scandinavian system of public care, in which care is seen as a form of family support and is provided for more rather than fewer children and families

Detailed geologic mapping of aquifer recharge areas in the upper coastal plain of southwest Georgia

Detailed geologic mapping on a scale of 1:24,000 has better defined the recharge areas of the Upper Floridan, Claiborne, Clayton and Cretaceous aquifers between the Flint River and the Chattachoochee River. Mapping over an eight year period that covered twenty-four 7.5” quadrangles was funded, in part, by the U.S. Geological Survey’s STATEMAP program. In addition to classical field mapping, interpretive geologic maps of each quadrangle were derived and developed as GIS coverages. Field observations suggest the aquifer recharge areas are more complex than previous studies of ideal geologic sections. Several periods of extensive weathering and erosion in the geologic record, particularly in the current recharge areas of the Upper Floridan, Claiborne, Clayton and Cretaceous aquifers, have resulted in removal of portions of the stratigraphic units that host these aquifers, removal of portions of the confining units, and adversely altered the porosity and permeability of the updip portions of these aquifers. Multiple episodes of paleo-groundwater movement recorded as cross-cutting alteration patterns in outcrops may further degrade optimal aquifer recharge in these areas. Previously unrecorded folding during the Tertiary may alter groundwater flow patterns, also.Sponsored by: Georgia Environmental Protection Division U.S. Geological Survey, Georgia Water Science Center U.S. Department of Agriculture, Natural Resources Conservation Service Georgia Institute of Technology, Georgia Water Resources Institute The University of Georgia, Water Resources Facult

Catalyzed Gasoline Particulate Filters Reduce Secondary Organic Aerosol Production from Gasoline Direct Injection Vehicles

The effects of photochemical aging on exhaust emissions from two light-duty vehicles with gasoline direct injection (GDI) engines equipped with and without catalyzed gasoline particle filters (GPFs) were investigated using a mobile environmental chamber. Both vehicles with and without the GPFs were exercised over the LA92 drive cycle using a chassis dynamometer. Diluted exhaust emissions from the entire LA92 cycle were introduced to the mobile chamber and subsequently photochemically reacted. It was found that the addition of catalyzed GPFs will significantly reduce tailpipe particulate emissions and also provide benefits in gaseous emissions, including nonmethane hydrocarbons (NMHC). Tailpipe emissions composition showed important changes with the use of GPFs by practically eliminating black carbon and increasing the fractional contribution of organic mass. Production of secondary organic aerosol (SOA) was reduced with GPF addition, but was also dependent on engine design which determined the amount of SOA precursors at the tailpipe. Our findings indicate that SOA production from GDI vehicles will be reduced with the application of catalyzed GPFs through the mitigation of reactive hydrocarbon precursors

Secondary organic aerosol formation from phenolic compounds in the absence of NO_x

SOA formation from benzene, toluene, <i>m</i>-xylene, and their corresponding phenolic compounds were investigated using the UCR/CE-CERT Environmental Chamber to evaluate the importance of phenolic compounds as intermediate species in aromatic SOA formation. SOA formation yield measurements coupled to gas-phase yield measurements indicate that approximately 20% of the SOA of benzene, toluene, and <i>m</i>-xylene could be ascribed to the phenolic route under low NO_x conditions. The SOA densities tend to be initially as high as approximately 1.8 g cm^&minus;3 and eventually reach the range of 1.3–1.4 g cm^&minus;3. The final SOA density was found to be independent of elemental ratio (O/C) indicating that applying constant density (e.g., 1.4 g cm^&minus;3) to SOA formed from different aromatic compounds tested in this study is a reasonable approximation. Results from a novel on-line PILS-TOFMS (Particle-into-Liquid Sampler coupled with Agilent Time-of-Flight Mass Spectrometer) are reported. Major signals observed by the on-line/off-line Agilent TOFMS indicated that products had the same number of carbon atoms as their parent aromatics, suggesting importance of ring-retaining products or ring-opening products following ring-cleavage