Second Generation Chemical Mass Balance Source Apportionment of Sulfur Oxides and Sulfate at the Grand Canyon during the Project MOHAVE Summer Intensive

ABSTRACT

Receptor-based chemical mass balance (CMB) analysis techniques are designed to apportion species that are conserved during pollutant transport using conserved source profiles. The techniques will fail if non-conservative species (or profiles) are not properly accounted for in the CMB model. The straightforward application of the CMB model developed for Project MOHAVE using regional profiles resulted in a significant under-prediction of total sulfate oxides (SO_x, SO₂ plus fine particulate sulfate) for many samples at Meadview, AZ. In addition, for these samples the concentration of the inert tracer emitted from the MOHAVE Power Project (MPP), ocPDCH, was also under-predicted. A second-generation model has been developed which assumes that separation of particles and SO₂ can occur in the MPP plume during nighttime stable plume conditions. This second-generation CMB model accounts for all SO_x present at the various receptor sites. In addition, the concentrations of ocPDCH and the presence of other inert tracers of emission from regional sources are accurately predicted. The major source of SO_x at Meadview was the MPP, but the major source of sulfate at this site was the Las Vegas urban area. At Hopi Point in the Grand Canyon, the Baja California region (Imperial Valley and northwestern Mexico) was the major source of both SO_x and sulfate.     

Biodiversity Conservation in a Changing Climate: A Review of Threats and Implications for Conservation Planning in Myanmar

High levels of species richness and endemism make Myanmar a regional priority for conservation. However, decades of economic and political sanctions have resulted in low conservation investment to effectively tackle threats to biodiversity. Recent sweeping political reforms have placed Myanmar on the fast track to economic development—the expectation is increased economic investments focused on the exploitation of the country’s rich, and relatively intact, natural resources. Within a context of weak regulatory capacity and inadequate environmental safeguards, rapid economic development is likely to have far-reaching negative implications for already threatened biodiversity and natural-resource-dependent human communities. Climate change will further exacerbate prevailing threats given Myanmar’s high exposure and vulnerability. The aim of this review is to examine the implications of increased economic growth and a changing climate within the larger context of biodiversity conservation in Myanmar. We summarize conservation challenges, assess direct climatological impacts on biodiversity and conclude with recommendations for long-term adaptation approaches for biodiversity conservation.     

Familial cystic hygroma with normal karyotype

A patient is described who had three consecutive fetuses with cystic hygroma and hydrops, two of which had documentation of normal karyotype. Some twenty percent of fetuses with cystic hygroma have a normal karyotype, and many of these have other major malformations. An autosomal recessive pattern of inheritance has been postulated, but cystic hygroma may also occur is association with a variety of syndromes, some of which have other patterns of inheritance.     

Place,human agency and community resilience – considerations for public health management of smoke from prescribed burning

Prescribed burning is now a widely accepted bushfire hazard management strategy. While evidence points to reduced levels of public health harm compared to severe bushfire, smoke created by planned burns remains a community concern with need for evidence-based public health management. Findings are presented from an Australian study of community experiences of prescribed burns, associated smoke, and public health communications. We find that “place” influences how information is received and used for the management of the effects of planned burns; and that this is significant for human agency and community resilience. We provide recommendations for public health management.     

Possibility of converting indigenous Salvadora persica L. seed oil into biodiesel in Pakistan

In this research study, biodiesel has been successfully produced from vegetable seed oil of an indigenous plant Salvadora persica L. that meets the international biodiesel standard (ASTM D6751). The biodiesel yield was 1.57 g/5 g (31.4% by weight) and the in-situ transesterification ester content conversion was 97.7%. The produced biodiesel density was 0.894 g/mL, its kinematic viscosity 5.51 mm²/s, HHV 35.26 MJ/kg, flash point 210°C, cetane no. 61, and sulfur content 0.0844%. Thermal analysis of the biodiesel showed that 97% weight loss was achieved at 595°C with total oxidation of the biodiesel. The production energy efficiency was 0.46% with a lab scale setup, assuming the volume fraction ratio (volume of the sample/total volume of the equipment used). The results revealed that single-step in-situ transesterification method is suitable for the production of biodiesel from S. persica seed oil.     

Amniotic fluid analysis in a fetus with laryngeal atresia

Complete laryngeal atresia is a rare congenital malformation that is known to cause hypertrophy of the fetal lung in utero. A fetus with laryngeal atresia was found to have markedly immature amniotic fluid lung maturity studies at term. Inappropriately low amniotic fluid lung maturity studies may be an important clue to the diagnosis of this condition.     

A Common Representative Intermediates (CRI) mechanism for VOC degradation. Part 3: Development of a secondary organic aerosol module

A Photochemical Trajectory Model (PTM), containing the Master Chemical Mechanism version 3.1 (MCM v3.1) coupled with an optimised representation of gas–aerosol absorptive partitioning of 365 oxygenated product species, has been used to simulate mass concentrations of secondary organic aerosol (SOA) for the conditions of the TORCH-2003 campaign in the south-east UK in late July and August 2003. A comprehensive reference dataset of 50 case study arrival events (and 4750 associated hourly air mass history events) has been compiled, which considers the base case conditions and scenarios in which emissions of anthropogenic pollution have been reduced by factors of up to 100. The relative contributions of SOA derived from anthropogenic and biogenic precursors are presented for the range of conditions, and the composition of these simulated components is discussed in terms of average molecular formulae, atomic ratios (H/C, O/C and N/C) and organic aerosol mass to organic carbon mass ratios (OM/OC), which are compared to reported measurements. The MCM v3.1 dataset has been used as a reference benchmark for development and optimisation of a reduced (14 species) SOA module for use with version 2 the Common Representative Intermediates mechanism (CRI v2), described in the first of two preceding companion papers [Jenkin, M.E., Watson, L.A., Utembe, S.R., Shallcross, D.E., 2008a. A Common Representative Intermediates (CRI) mechanism for VOC degradation. Part 1: gas phase mechanism development. Atmospheric Environment, 42, pp. 7185–7195. doi:10.1016/j.atmosenv.2008.07.028.]. The resultant version of the PTM containing CRI v2 and the reduced SOA module has been used to simulate the entire TORCH-2003 campaign at hourly resolution, and the contributions of SOA derived from anthropogenic and biogenic precursors are presented and discussed. The reduced SOA module is also shown to be compatible with the most reduced CRI variant (CRI v2-R5), described in the second of two preceding companion papers [Watson, L.A., Shallcross, D.E., Utembe, S.R., Jenkin, M.E., 2008. A Common Representative Intermediates (CRI) mechanism for VOC degradation. Part 2: gas phase mechanism reduction. Atmospheric Environment, 42, pp. 7196–7204. doi:10.1016/j.atmosenv.2008.07.034.], which is considered appropriate as a traceable reference mechanism in global simulations.     

Estimating first-order reaction rate coefficient for transport with nonequilibrium linear mass transfer in heterogeneous media

A travel-time based approach is developed for estimating first-order reaction rate coefficients for transport with nonequilibrium linear mass transfer in heterogeneous media. Tracer transport in the mobile domain is characterized by a travel-time distribution, and mass transfer rates are described by a convolution product of concentrations in the mobile domain and a memory function rather than predefining the mass transfer model. A constant first-order reaction is assumed to occur only in the mobile domain. Analytical solutions in Laplace domain can be derived for both conservative and reactive breakthrough curves (BTCs). Temporal-moment analyses are presented by using the first and second moments of conservative and reactive BTCs and the mass consumption of the reactant for an inverse Gaussian travel-time distribution. In terms of moment matching, there is no need for one to specify the mass transfer model. With the same capacity ratio and the mean retention time, all mass transfer models will lead to the same moment-derived reaction rate coefficients. In addition, the consideration of mass transfer generally yields larger estimations of the reaction rate coefficient than models ignoring mass transfer. Furthermore, the capacity ratio and the mean retention time have opposite influences on the estimation of the reaction rate coefficient: the first-order reaction rate coefficient is positively linearly proportional to the capacity ratio, but negatively linearly proportional to the mean retention time.