Understanding methanotroph ecology in a biofilter for efficiently mitigating methane emissions : a thesis presented in fulfilment of the requirements for the degree of Doctor of Philosophy in Soil Science (Biotechnology) at Massey University, Palmerston North, New Zealand

In New Zealand, the majority of the greenhouse gas (GHG), methane (CH4) emissions are from the agriculture sector (enteric fermentation, manure management) and the remainder from solid waste disposal, coal mining and natural gas leaks. A soil-based biofilter made from volcanic pumice soil (isolated from a landfill in Taupo, New Zealand) and perlite has been tested and promoted to mitigate high concentrations (3 300 ppm – 100 000 ppm) of CH4 emissions from a dairy effluent storage pond. This soil-perlite mixture exhibited excellent physical (porosity, water holding capacity and bulk density) characteristics to support the growth and activity of an active methanotroph community. Methanotrophs comprise a diverse group of aerobic alpha and gamma proteobacteria (type I and type II methanotrophs, respectively) that are present naturally in soils where CH4 is produced. However, there is little information on the methanotrophs community structure, population diversity and abundance in this soil-based biofilter. Understanding the activity of these diverse genera under varying soil conditions is essential for optimum use of biofiltration technology, and is the main aim of this thesis. This thesis describes a study to use molecular techniques (PCR, quantitative PCR, T-RFLP and molecular cloning) (Chapter 3) to reveal the population dynamics of methanotrophs (type I, type II and various genera – Methylobacter/Methylomonas/Methylosarcina, Methylococcus and Methylocapsa), in order to build a more efficient CH4 biofiltration system. Methanotroph population dynamics in two fundamentally different prototypes of volcanic pumice soil biofilters – a column and a floating/cover biofilter studied are presented in Chapters 4 and 5. The column biofilter study (Chapter 4) examined the performance of a previously used acidic soil-biofilter medium that was further acidified from pH 5.20 ± 0.20 to 3.72 ± 0.02 by H2S present in the biogas (from the dairy effluent pond).. The more acidic soil biofilter medium (volcanic pumice soil and perlite, 50:50 v/v) was reconstituted with optimal moisture content (110% gravimetric dry wt or ~ 60 % WHC) and achieved a maximum CH4 removal rate of 30.3 g m–3 h–1. In addition, the population of Methylocapsa-like methanotroph increased by 400 %, demonstrating the ability of these soil microorganisms to adapt and grow under acidic pH conditions in the biofilter. The results from this study indicated that (i) when primed with CH4, a soil biofilter can effectively regain efficiency if sufficient moisture levels are maintained, regardless of the soil acidity; (ii) changes in the methanotroph population did not compromise the overall capacity of the volcanic pumice soil to oxidise CH4; and (iii) the more acidic environment (pH 3.72) tends to favour the growth and activity of acid-loving Methylocapsa-like methanotroph while being detrimental to the growth of the Methylobacter / Methylococcus / Methylocystis group of methanotroph. In the floating biofilter (Chapter 5), original acidic soil biofilter medium (pH 5.20) as used in column study was assessed to remove CH4 from the effluent pond surface for a period of one year (December 2013 to November 2014). Field evaluation was supported with a concurrent laboratory study to assess their CH4-oxidising capacity, in addition to identifying and comparing the methanotroph community changes in the soil when exposed to field conditions. Results indicated that (i) irrespective of the season, the floating biofilters in the field were removing 67 ± 6% CH4 throughout the study period with a yearly average rate of 48 ± 23 g CH4 m-3 h-1; however, the highest CH4 removal rate achieved was 101.5 g m-3 h-1 CH4, about 300 % higher than the highest CH4 removal rate by the acidified column biofilter (Chapter 4); (ii) the acidity of the field floating biofilters increased from a pH value of 5.20 to 4.72, but didn’t suppress the genera of methanotrophs (particularly Methylobacter/Methylosinus/Methylocystis); (iii) the laboratory-based floating biofilters experienced biological disturbances with low and high CH4 removal phases during the study period, with an yearly average CH4 oxidation removal of 58%; and (iv) both type I and type II methanotrophs in the field floating biofilters were more abundant, diverse and even compared with the methanotroph community in the laboratory biofilters. This study has demonstrated the ability of the floating biofilters to efficiently mitigate dairy effluent ponds emissions in the field, without requiring any addition of nutrients or water; however, during very dry conditions, occasional addition of water might be needed to keep the biofilter bed moist (≥ 23±4 % dry wt). Earlier New Zealand studies and the current studies (Chapters 4 and 5) were based on the use of a particular volcanic pumice soil as biofilter medium. However, the limited availability of volcanic pumice soil and associated transportation costs limited the wider application of this technology within New Zealand and internationally. This necessitated the assessment of other farm soils and potentially suitable, economical, and locally available biofilter materials that could potentially be used by the farmers to mitigate CH4 emissions (Chapter 6). The potential biofilter materials, viz. farm soil (isolated from a dairy farm effluent pond bank area), pine biochar, garden waste compost, and weathered pine bark mulch were assessed with and without inoculation with a small amount of volcanic pumice soil. All materials supported the growth and activity of methanotrophs. However, the CH4 removal was high (> 80%) and consistent in the inoculated - farm soil and biochar, and was supported by the observed changes in the methanotroph community. The CH4 removal was further enhanced (up to 99%) by the addition of nutrient solution. Field evaluations of these potential materials are now needed to confirm the viability of these materials for recommending them for use on farms. Chapter 7 summarises the molecular results from all the above studies, and describes the future studies. Molecular techniques indicated that a very diverse (Shannon’s diversity, Hʹ = 3.9 to 4.4) group of type I and type II methanotrophs were present in the volcanic pumice soil, which assisted the biofilter materials to perform under varying abiotic conditions. Many novel species and strains of type I and type II methanotrophs were also identified in these soils. For long-term, low cost and efficient and stable CH4 removal, the presence of an even and abundant population (of type I and type II methanotrophs) is however essential. Nevertheless, biofilters offer much promise for mitigating CH4 emissions from dairy ponds, piggeries, and landfills, thereby contributing to the lowering of emissions of this potent greenhouse gas to mitigate the effects of climate change

A reappraisal of how oral rehydration therapy affected mortality in Egypt

Oral rehydration therapy is the key low-cost child survival intervention used to deal with diarrheal illness in developing countries. The existence of a low-cost, highly efficacious technological fix (oral rehydration salts) for the life-threatening dehydration that accompanies diarrhea provided a strong rationale for making oral rehydration therapy a cornerstone of diarrheal disease control programs. The Egyptian oral rehydration therapy program has been quoted as having the most spectacular success in reducing infant and child mortality. But there is a need to differentiate between the efficacy of oral rehydration therapy in clinical settings and in community use. The National Control of Diarrheal Diseases Project (NCDDP) was launched in Egypt in 1983. A pilot program was followed by national promotion starting in February 1984. As early as 1985, opinions were being expressed about the favorable impact of NCDDP activities on child mortality. There is no doubt that the NCDDP greatly increased both awareness of the dangers of dehydration consequent upon diarrhea in children and knowledge of oral rehydration therapy. But survey data on the use of oral rehydration therapy during diarrheal episodes show such use to be far from universal (with use in fewer than 50 percent of episodes). Futher, ethnographic studies show appropriate use, in terms of timing and quantity, to be the exception rather than the rule. The maximum theoretical effect of the NCDDP on child mortality would be to eliminate all deaths from diarrhea, a reduction of about 50 percent. The maximum effect that could realistically be expected is a reduction of less than 20 percent. Analysis of a time series of infant mortality from vital registration data indicates an abrupt, statistically-significant change in level in 1985 amounting to a once-off decline of about 15 percent. In the absence of other changes taking place at about the right time that might explain this drop, it is concluded that the NCDDP probably was responsible. Thus, although many of the claims made for the impact of the NCDDP on child mortality in Egypt appear to have been greatly exaggerated, it does seem likely, in the absence of alternative explanations, that the program significantly reduced infant mortality in the mid-1980s.Early Child and Children's Health,Health Monitoring&Evaluation,Health Systems Development&Reform,Demographics,Statistical&Mathematical Sciences

Structural Estimation of Caloric Intake, Exercise, Smoking, and Obesity

The escalating rate of obesity in the US highlights the importance of understanding the causes for this rise. In this paper I employ the First, Second, and Third National Health and Nutrition Examination Surveys to estimate a structural model of the determinants of adult obesity. To control for the potential endogeneity of some explanatory variables, such as caloric intake (adjusted for activity level) and smoking, a set of reduced form equations for these outcomes is estimated simultaneously with the obesity equation. To identify each equation, I use an array of state-level characteristics as instrumental variables. Trends in these variables shed light on the sources of the rapid increase in obesity since 1980.

Cycling: An Increasingly Untouched Source of Physical and Mental Health

Cost savings associated with increased gasoline prices and lower levels of urban sprawl have been cited in terms of personal savings, environmental awareness, reduced costs through lower travel times and congestion, and reduced income inequality. Cost savings in terms of improved health, however, are often not cited yet represent another dimension of savings associated with reduced urban sprawl and gas prices. Cycling is a form of exercise that can also be used as a mode of transportation if the surrounding environment facilitates such use. According to the United States Department of Transportation, 73 percent of adults want new bicycle facilities such as bike lanes, trails, and traffic signals. Using data from the 1990, 1995, and 2001 waves of the Nationwide Personal Transportation Survey, in addition to data from the Behavioral Risk Factor Surveillance System (1996-2000), I propose to analyze the effects of variations in the built environment in the form of urban sprawl and in real gasoline prices on cycling as a form of physical activity. Using bivariate probit and propensity score methods, I show how cycling can lead to improved physical health outcomes. This is turn may carry policy implications in terms of improved public awareness and city planning.

Employer-Provided Health Insurance and the Incidence of "Job-Lock": Is There a Consensus?

Several recent developments in health care in the United States include declining health care coverage, particularly that provided by employers, and a noticeable shift in the burden of medical care costs to employees. If these developments cause employees to feel locked into their jobs, optimal job matches in the labor force will not take place. Partly in response, the federal government has passed laws protecting health coverage for workers who switch jobs, with the passage of the Consolidated Omnibus Budget Reconciliation Act of 1986 and later the Health Insurance Portability and Accountability Act in 1996. In this paper we summarize the current literature on the topic and present some findings using the National Health Interview Survey, focusing on the 1997-2003 period. Our findings are consistent with recent assertions that there is some evidence of job-lock. Working Paper 06-5

Accident Analysis of Ice Control Operations

Highway maintenance involves all work necessary to assure that the highway system is kept safe, open to traffic, and in proper working order. During winter, the removal of snow and ice from streets, roads, and highways is a major maintenance operation. With more than 135 million motor vehicles registered in the United States and roughly four million miles of roads and streets, local governments must be prepared to deal with the removal of snow and ice to insure public safety, and to reduce the adverse impact on the affected area’s economy. Snow and ice covered roads can paralyze the functioning of the community and pose a considerable threat to the public safety. They produce hazardous driving conditions which increase traffic deaths, injuries, and property damage. The general assumption has always been that snow and ice on highways causes accidents. There are a number of reasons for this assumption. Snow and ice reduce the coefficient of friction between the pavement and vehicle tires, making maneuvering of the vehicle very difficult and occasionally impossible. Ice is not always apparent to the motorist and is not uniform, so that the driver is not always prepared when he encounters an icy section on the roadway. Vehicle mobility is reduced, causing possible severe disruption of important public emergency services, such as fire, police, and ambulance operations. Without close attention to the effective removal of snow and ice from roads, the economy of the region involved will suffer, and traffic accidents will escalate. Most activities of individuals, industries, utilities, schools, and government activities are handicapped in social and economic ways during the duration of snow and ice conditions on roads and streets