Integrating Geographic Information System network analysis and nighttime light satellite imagery to optimize landfill regionalization on a regional level

More than half of financial resources allocated for municipal solid waste management are typically spent on waste collection and transportation. An optimized landfill siting and waste collection system can save fuel costs, reduce collection truck emissions, and provide higher accessibility with lower traffic impacts. In this study, a data-driven analytical framework is developed to optimize population coverage by landfills using network analysis and satellite imagery. Two scenarios, SC1 and SC2, with different truck travel times were used to simulate generation-site–disposal-site distances in three Canadian provinces. Under status quo conditions, Landfill Regionalization Index (LFRI) ranging from 0 to 2 population centers per landfill in all three jurisdictions. LFRI consistently improved after optimization, with average LFRI ranging from 1.3 to 2.0 population centers per landfill. Lower average truck travel times and better coverage of the population centers are generally observed in the optimized systems. The proposed analytical method is found effective in improving landfill regionalization. Under SC1 and SC2, LFRI percentages of improvement ranging from 58.3% to 64.5% and 22.7% to 59.4%, respectively. Separation distance between the generation and disposal sites and truck capacity appear not a decisive factor in the optimization process. The proposed optimization framework is generally applicable to regions with different geographical and demographical attributes, and is particularly applicable in rural regions with sparsely located population centers.

     

Probabilistic risk assessment for personal exposure to carcinogenic polycyclic aromatic hydrocarbons in Taiwanese temples

To assess how the human exposure to airborne carcinogenic polycyclic aromatic hydrocarbons (PAHs) during working in or visiting a typical Taiwanese temple, we present a probabilistic risk model, appraised with reported empirical data. Two approaches are applied, one based on animal-derived benzo[a]pyrene (B[a]P) toxic equivalents (B[a]P(eq)) of individual PAHs and one is assumed that the potency of PAH mixtures is linked to their B[a]P level. The model integrates probabilistic exposure profiles of total-PAH and particle-bound PAH levels inside a temple from a published exploratory study with probabilistic incremental lifetime cancer risk (ILCR) models taking into account inhalation and dermal contact pathways, to quantitatively estimate the exposure risks for three age groups of adult, adolescent, and child. Risk analysis indicates that 90% probability inhalation ILCRs for three age groups have orders of magnitude around 10(-7)--10(-6); whereas for the dermal contact ILCRs ranging from 10(-5) to 10(-4), indicating high potential cancer risk. All 90% probabilities of B[a]P- and B[a]P(eq)-based total ILCRs are larger than 10(-6), indicating unacceptable probability distributions for three age groups. Sensitivity analysis indicates that to increase the accuracy of the results efforts should focus on a better definition of probability distributions for inhalation cancer slope factor, inhalation rates, and particle-bound PAH-to-skin adherence factor. We estimate risk-based visiting frequency advice for adult, adolescent, and child to a temple ranging from 5 to 7, 17 to 23, and 48 to 65 year(-1), respectively, based on an average 3h residence time.     

Sonographic features of lethal multiple pterygium syndrome at 14 weeks

Lethal multiple pterygium syndrome is a rare inherited disorder. Previous reports suggest that the diagnosis may be based on prenatal sonographic demonstration of severe limb flexion, absence of fetal motion, and a large cystic hygroma in the second and third trimesters. We present the sonographic features and postmortem features of a fetus with lethal multiple pterygium syndrome at 13 weeks of gestation, which shows that the condition can possibly be diagnosed in the first trimester of pregnancy. Copyright © 2005 John Wiley & Sons, Ltd.     

Thermocoagulation of fetal sacrococcygeal teratoma

Fetal sacrococcygeal teratoma can lead to a high output cardiac failure resulting in hydrops fetalis. One of the prenatal therapeutic options is to occlude the feeding vessels by radiofrequency ablation. We present a case of fetal sacrococcygeal teratoma diagnosed at 13 weeks of gestation. The tumour increased in size more than 100-fold over 5 weeks causing polyhydramnios and cardiac and placental enlargement. Thermocoagulation was performed at 18 weeks' gestation by passing an insulated electric wire through an 18-gauge needle placed close to the feeding vessels of the tumour at its neck. Blood supply to the tumour was successfully reduced. However, fetal death was diagnosed 2 days after the procedure. We speculate that it may be safer to limit the extent of coagulation in one attempt but to repeat the procedure at a later stage when necessary. Copyright © 2002 John Wiley & Sons, Ltd.     

Applying mass transfer models for controlling organic compounds in ozonation process

Mass transfer plays a significant role in the ozonation process. The prediction models associated with the volumetric overall mass transfer coefficient (K_La) and initial fractional ozone absorption (FOA₀) during the ozonation process were developed through the use of dimensional analysis. It was found that the volumetric overall mass transfer coefficient is the function of diffusivity, agitation speed, and gas flow rate, and the parameters in the K_La equation are determined. Application of the prediction models for K_La and FOA₀ would yield information to choose the most practically feasible operating parameters. The removability of total organic carbon (TOC) can be estimated based on the mass balance relationship and kinetic expression of TOC oxidation, during continuous laboratory ozonation of humic acid solution. The reaction rate constant averaged 0.0291 L/mg·min. The developed model in combination with the mass transfer and reaction kinetics can be used successfully in forecasting the most efficient agitation speed to control the formation of organic compounds. Also, the critical value of ozone partial pressure to achieve the highest TOC removability can be determined through the use of the above developed model.     

Economic and Political Factors that Lead to the Budget Deficit in Hong Kong from 1998 to 2003

Despite the adverse impact of the budget deficit in Hong Kong has been alleviated since the economic recovery from 2003, the fiscal deficit may return when there is another downturn in the economy if the problem is not handled fundamentally.Based on the economic and political situation from 1998 to 2003,the factors that lead to the budget deficit in Hong Kong are analyzed in four perspectives,including(a)increase in public expenditure;(b)decrease in public revenues;(c)poor management of public money and(d) weak administration.With a better understanding on these factors, possible solutions to the fiscal problem faced by the government may be developed.     

cfDNA screening and diagnosis of monogenic disorders – where are we heading?

Cell-free fetal DNA analysis for non-invasive prenatal screening of fetal chromosomal aneuploidy has been widely adopted for clinical use. Fetal monogenic diseases have also been shown to be amenable to non-invasive detection by maternal plasma DNA analysis. A number of recent technological developments in this area has increased the level of clinical interest, particularly as one approach does not require customized reagents per mutation. The mutational status of the fetus can be assessed by determining which parental haplotype that fetus has inherited based on the detection of haplotype-associated SNP alleles in maternal plasma. Such relative haplotype dosage analysis requires the input of the parental haplotype information for interpretation of the fetal inheritance pattern from the maternal plasma DNA data. The parental haplotype information can be obtained by direct means, reducing the need to infer haplotypes using DNA from other family members. The technique also allows the assessment of complex mutations and has multiplexing capabilities where a number of genes and mutations can be assessed at the same time. These advantages allow non-invasive prenatal diagnosis of fetal monogenic diseases to be much more scalable. These applications may drive the next wave of clinical adoption of cell-free fetal DNA testing. © 2018 The Authors Prenatal Diagnosis Published by John Wiley & Sons Ltd     

PFAS Experts Symposium: Statements on regulatory policy,chemistry and analytics,toxicology, transport/fate,and remediation for per‐ and polyfluoroalkyl substances (PFAS) contamination issues

Sixty leading members of the scientific, engineering, regulatory, and legal communities assembled for the PFAS Experts Symposium in Arlington, Virginia on May 20 and 21, 2019 to discuss issues related to per‐ and polyfluoroalkyl substances (PFAS) based on the quickly evolving developments of PFAS regulations, chemistry and analytics, transport and fate concepts, toxicology, and remediation technologies.  The Symposium created a venue for experts with various specialized skills to provide opinions and trade perspectives on existing and new approaches to PFAS assessment and remediation in light of lessons learned managing other contaminants encountered over the past four decades. The following summarizes several consensus points developed as an outcome of the Symposium:

• Regulatory and policy issues: The response by many states and the US Environmental Protection Agency (USEPA) to media exposure and public pressure related to PFAS contamination is to relatively quickly initiate programs to regulate PFAS sites. This includes the USEPA establishing relatively low lifetime health advisory levels for PFAS in drinking water and even more stringent guidance and standards in several states. In addition, if PFAS are designated as hazardous substances at the federal level, as proposed by several Congressional bills, there could be wide‐reaching effects including listing of new Superfund sites solely for PFAS, application of stringent state standards, additional characterization and remediation at existing sites, reopening of closed sites, and cost renegotiation among PRPs.
• Chemistry and analytics: PFAS analysis is confounded by the lack of regulatory‐approved methods for most PFAS in water and all PFAS in solid media and air, interference with current water‐based analytical methods if samples contain high levels of suspended solids, and sample collection and analytical interference due to the presence of PFAS in common consumer products, sampling equipment, and laboratory materials.
• Toxicology and risk: Uncertainties remain related to human health and ecological effects for most PFAS; however, regulatory standards and guidance are being established incorporating safety factors that result in part per trillion (ppt) cleanup objectives. Given the thousands of PFAS that may be present in the environment, a more appropriate paradigm may be to develop toxicity criteria for groups of PFAS rather than individual PFAS.
• Transport and fate: The recalcitrance of many perfluoroalkyl compounds and the capability of some fluorotelomers to transform into perfluoroalkyl compounds complicate conceptual site models at many PFAS sites, particularly those involving complex mixtures, such as firefighting foams. Research is warranted to better understand the physicochemical properties and corresponding transport and fate of most PFAS, of branched and linear isomers of the same compounds, and of the interactions of PFAS with other co‐contaminants such as nonaqueous phase liquids. Many PFAS exhibit complex transport mechanisms, particularly at the air/water interface, and it is uncertain whether traditional transport principles apply to the ppt levels important to PFAS projects. Existing analytical methods are sufficient when combined with the many advances in site characterization techniques to move rapidly forward at selected sites to develop and test process‐based conceptual site models.
• Existing remediation technologies and research: Current technologies largely focus on separation (sorption, ion exchange, or sequestration). Due to diversity in PFAS properties, effective treatment will likely require treatment trains. Monitored natural attenuation will not likely involve destructive reactions, but be driven by processes such as matrix diffusion, sorption, dispersion, and dilution.

The consensus message from the Symposium participants is that PFAS present far more complex challenges to the environmental community than prior contaminants. This is because, in contrast to chlorinated solvents, PFAS are severely complicated by their mobility, persistence, toxicological uncertainties, and technical obstacles to remediation—all under the backdrop of stringent regulatory and policy developments that vary by state and will be further driven by USEPA. Concern was expressed about the time, expense, and complexity required to remediate PFAS sites and whether the challenges of PFAS warrant alternative approaches to site cleanups, including the notion that adaptive management and technical impracticability waivers may be warranted at sites with expansive PFAS plumes. A paradigm shift towards receptor protection rather than broad scale groundwater/aquifer remediation may be appropriate.