Bayesian treatment of a chemical mass balance receptor model with multiplicative error structure

The chemical mass balance (CMB) receptor model is commonly used in source apportionment studies as a means for attributing measured airborne particulate matter (PM) to its constituent emission sources. Traditionally, error terms (e.g., measurement and source profile uncertainty) associated with the model have been treated in an additive sense. In this work, however, arguments are made for the assumption of multiplicative errors, and the effects of this assumption are realized in a Bayesian probabilistic formulation which incorporates a ‘modified’ receptor model. One practical, beneficial effect of the multiplicative error assumption is that it automatically precludes the possibility of negative source contributions, without requiring additional constraints on the problem. The present Bayesian treatment further differs from traditional approaches in that the source profiles are inferred alongside the source contributions. Existing knowledge regarding the source profiles is incorporated as prior information to be updated through the Bayesian inferential scheme. Hundreds of parameters are therefore present in the expression for the joint probability of the source contributions and profiles (the posterior probability density function, or PDF), whose domain is explored efficiently using the Hamiltonian Markov chain Monte Carlo method. The overall methodology is evaluated and results compared to the US Environmental Protection Agency's standard CMB model using a test case based on PM data from Fresno, California.     

Community Forestry as Perceived by Local People Around Cross River National Park, Nigeria

The prior identification of local people’s preferences for conservation-development projects will help gear nature-conservation strategies toward the needs of different groups of local people. This will help policy-makers in designing a more acceptable and effective conservation strategy. This article reports a study of local perceptions of a community forestry project that aims to help improve the design as well as local acceptance of the project. The data originated from personal interviews conducted in communities around Okwangwo Division of the Cross River National Park in southeast Nigeria and were analysed using ordered logit and binary logit models. The results showed that >50% of the respondents were satisfied with the community forestry project. The respondents’ perceptions were mainly influenced by education, age, gender, and willingness to contribute money to tourism as well as the contributions of cocoa, banana, and afang (Gnetum africanum) to the respondents’ income. The results from this study have important implications for nature conservation in Nigeria and potentially other conservation contexts across the developing world.     

Air Analysis: The Standard Dosage-Area Product

The Dosage-Area Product is an areawide smog index obtained by combining contaminant concentration, duration, and areal extent: DAP = c×f×A (ppm × hr × mi²). The first step in developing a DAP is to plot daily contaminant dosages from an air monitoring network and to draw isopleths showing the dosage pattern. The second step is to determine the areas between isopleths and to multiply these areas by the applicable dosage levels. The final step is to sum the above partial products into a single number and to add a type designator indicating the geographic configuration of the dosage pattern. The DAP smog index is a realistic yardstick for measuring areawide smog experience. Reproducible results are obtained at low cost by using standard techniques. The standard DAP smog index is also useful for: analyzing air pollution episodes, estimating contaminant trends, and informing the public.     

Preparation and Use of Spatially and Temporally Resolved Emission Inventories in the San Francisco Bay Region

Three regional agencies recently prepared an Air Quality Maintenance Plan for the San Francisco Bay Area oxidant problem. An Eulerian, photochemical model, LIRAQ, provided the technical basis for the plan recommendations. A major LIRAQ input is an emission inventory accurately resolved to one kilometer and one hour increments. The cooperating agencies prepared such inventories, covering 20,000 sq km, for one base and two future years. Several manual and computer-assisted techniques were developed to utilize a variety of independent data bases. Population, land use, employment and transportation data were oganized into a common system of coordinates and units to produce the needed spatial input. Estimates of hourly variation were made by source category based on production rates, fuel use, traffic patterns, flight schedules, and other factors. The result was a series of consistent, detailed inventories which provide a powerful air quality modeling and planning tool. The detail is attained at considerable expense, but the cost is easily justifiable when compared to implementation costs for control strategies.     

Climatic, socio-economic, and health factors affecting human vulnerability to cholera in the Lake Victoria basin, East Africa

Cholera epidemics have a recorded history in the eastern Africa region dating to 1836. Cholera is now endemic in the Lake Victoria basin, a region with one of the poorest and fastest growing populations in the world. Analyses of precipitation, temperatures, and hydrological characteristics of selected stations in the Lake Victoria basin show that cholera epidemics are closely associated with El Ni?o years. Similarly, sustained temperatures high above normal (T(max)) in two consecutive seasons, followed by a slight cooling in the second season, trigger an outbreak of a cholera epidemic. The health and socioeconomic systems that the lake basin communities rely upon are not robust enough to cope with cholera outbreaks, thus rendering them vulnerable to the impact of climate variability and change. Collectively, this report argues that communities living around the Lake Victoria basin are vulnerable to climate-induced cholera that is aggravated by the low socioeconomic status and lack of an adequate health care system. In assessing the communities' adaptive capacity, the report concludes that persistent levels of poverty have made these communities vulnerable to cholera epidemics.     

A situational analysis of Cameroon’s Technical Operation Units (TOUs) in the context of the landscape approach: critical issues and perspectives

The integrated landscape approach is re-emerging in the global agenda as an approach which can give a fair deal to landscape functions such as climate change response, biodiversity conservation, food security, poverty reduction and economic growth. However, transformational change might be required to enable landscapes respond to these different functions. This is due to the sensitive nature of landscapes to local, national and global economic, social and political drivers. Based on national policy instruments, this paper presents a situational analysis of the landscape concept in Cameroon, operationalized as Technical Operation Units (TOUs) and in the context of the present institutional, social, economic and political features, it examines the rationale for a landscape approach in Cameroon. We notice potential trade-offs, indicating that the landscape approach is an opportunity for TOUs in Cameroon. Firstly, TOUs are characterized by multiple resource regimes with overlapping claims each having a legal land allocation and management plan. Secondly, TOUs are characterized by different stakeholders, with different land-use interests and motives, each controlling key components in the landscapes. Thirdly, the interests and motives of stakeholders overlap spatially and are connected to different sectoral policies at the national level. This setting might threaten decision making and the sustainability potentials of landscapes. Nonetheless, we propose areas for in-depth studies to generate knowledge and information to orientate win–win policy construction for landscapes. This is relevant for the social, ecological and economic objectives that underpin the sustainable development goals proposed in the post-2015 development agenda.