Development of a High-Speed Ultraviolet Spectrometer for Remote Sensing of Mobile Source Nitric Oxide Emissions

ABSTRACT

The University of Denver (DU) has developed a new remote sensor for the measurement of mobile source nitric oxide (NO). This system is integrated with an existing infrared remote sensor and is capable of measuring carbon monoxide and hydrocarbons in addition to NO, at a rate of more than 1000 vehicles/hr. The detection limit on a low-emitting vehicle under typical measurement conditions is 24 parts per million NO (3σ). Measurements from this instrument correlated well in a side-by-side comparison with the previous NO remote sensor developed at DU, and we have used this study to confirm a suspected interference by aromatic hydrocarbons in the older instrument. The results of an extended field experiment using the new instrument, conducted in fall 1997, are also presented. The NO emissions of the fleet measured in this study (averaging 15.0 g NO/gal) exhibit a skewed distribution typical of mobile sources. This paper also describes the relationship between NO emissions and model year and NO emissions and vehicle acceleration, as measured by the new remote sensor.     

Implementation of food frequency questionnaire for the assessment of total dietary arsenic intake in Bangladesh: Part B, preliminary findings

Dietary intake of water and food has been identified as one of the major pathways for arsenic (As) exposure in the rural population of Bangladesh. Therefore, realistic assessment and measurement of dietary intake patterns are important for the development of an accurate estimate of As exposure and human health risk assessment. One important consideration is to identify an appropriate tool for measuring dietary intake. In this study an interviewer-administered Food Frequency Questionnaire (FFQ) was implemented to determine age and gender specific dietary intake. The developed FFQ was unique because it developed a synergy between field dietary assessment and As concentration measurements in various environmental media. The resulting integrated database provided an accurate framework for the process of As exposure and human health risk assessment. The preliminary results reported here from the FFQ demonstrated that this technique could be used in rural areas as a tool to assess As exposure and the associated human health risk.     

Bioenergy Sustainability in China: Potential and Impacts

The sustainability implications of bioenergy development strategies are large and complex. Unlike conventional agriculture, bioenergy production provides an opportunity to design systems for improving eco-environmental services. Different places have different goals and solutions for bioenergy development, but they all should adhere to the sustainability requirements of the environment, economy, and society. This article serves as a brief overview of China’s bioenergy development and as an introduction to this special issue on the impacts of bioenergy development in China. The eleven articles in this special issue present a range of perspectives and scenario analyses on bioenergy production and its impacts as well as potential barriers to its development. Five general themes are covered: status and goals, biomass resources, energy plants, environmental impacts, and economic and social impacts. The potential for bioenergy production in China is huge, particularly in the central north and northwest. China plans to develop a bioenergy capacity of 30GW by 2020. However, realization of this goal will require breakthroughs in bioenergy landscape design, energy plant biotechnology, legislation, incentive policy, and conversion facilities. Our analyses suggest that (1) the linkage between bioenergy, environment, and economy are often circular rather than linear in nature; (2) sustainability is a core concept in bioenergy design and the ultimate goal of bioenergy development; and (3) each bioenergy development scheme must be region-specific and designed to solve local environmental and agricultural problems.     

Habitat as a mediator of mesopredator‐driven mammal extinction

A prevailing view in dryland systems is that mammals are constrained by the scarcity of fertile soils and primary productivity. An alternative view is that predation is a primary driver of mammal assemblages, especially in Australia, where 2 introduced mesopredators—feral cat (Felis catus) and red fox (Vulpes vulpes)—are responsible for severe declines of dryland mammals. We evaluated productivity and predation as drivers of native mammal assemblage structure in dryland Australia. We used new data from 90 sites to examine the divers of extant mammal species richness and reconstructed historic mammal assemblages to determine proportional loss of mammal species across broad habitat types (landform and vegetation communities). Predation was supported as a major driver of extant mammal richness, but its effect was strongly mediated by habitat. Areas that were rugged or had dense grass cover supported more mammal species than the more productive and topographically simple areas. Twelve species in the critical weight range (CWR) (35–5500 g) that is most vulnerable to mesopredator predation were extirpated from the continent's central region, and the severity of loss of species correlated negatively with ruggedness and positively with productivity. Based on previous studies, we expect that habitat mediates predation from red foxes and feral cats because it affects these species’ densities and foraging efficiency. Large areas of rugged terrain provided vital refuge for Australian dryland mammals, and we predict such areas will support the persistence of CWR species in the face of ongoing mammal declines elsewhere in Australia.     

Using Geographically Isolated Loading Scenarios to Analyze Nitrogen and Phosphorus Exchanges and Explore Tailored Nutrient Control Strategies for Efficient Management

A set of geographically isolated differential nitrogen (N) and phosphorus (P) load model scenarios from major Chesapeake basins provides information on the relative impact of nutrient loads on primary production and dissolved oxygen in the Chesapeake Bay. Model results show the relationships of deep water dissolved oxygen with nutrient limitation-related algal blooms, organic carbon loads from the watershed, estuarine circulation, nutrient cycling, and nutrient diagenesis. The combined effect of changes in load from multiple basins is additive for changes in both chlorophyll-a and deep water dissolved oxygen concentrations. Management of both N and P are required in the Chesapeake watershed and tidal waters to achieve water quality standards, but overall efficiencies could be gained with strategies that place greater emphasis on P control in the upper Bay and greater emphasis on N control in the lower Bay. The areas of the Bay with the highest degree of dissolved oxygen degradation that generally drive management decisions are mostly P-limited and are significantly influenced by the load from the upper Bay’s basins. Reducing P from the upper Bay’s basins will intensify P limitation and would allow an increase in N of about six times the weight of P reduction. Combining the relative nutrient reduction effectiveness with the relative control cost information could improve management efficiency and provide benefits at a lower cost. This article describes initial steps that can be taken to examine the benefits from N-P exchanges.     

PCB126 blocks the thermogenic beiging response of adipocytes

Environmental Science and Pollution Research - Subcutaneous white adipose tissue is capable of becoming thermogenic in a process that is referred to as “beiging.” Beiging is associated...     

A COMPARISON OF METHODS FOR ESTIMATING LOW FLOW CHARACTERISTICS OF STREAMS1

ABSTRACT: Four methods for estimating the 7-day, 10-year and 7-day, 20-year low flows for streams are compared by the bootstrap method. The bootstrap method is a Monte Carlo technique in which random samples are drawn from an unspecified sampling distribution defined from observed data. The nonparametric nature of the bootstrap makes it suitable for comparing methods based on a flow series for which the true distribution is unknown. Results show that the two methods based on hypothetical distributions (Log-Pearson III and Weibull) had lower mean square errors than did the Box-Cox transformation method or the Log-Boughton method which is based on a fit of plotting positions.     

COUNTY COMMISSIONERS' WATER KNOWLEDGE1

ABSTRACT: This study examines the social construction of county commissioners' knowledge about water. Factors that influence what commissioners know about water include each commissioner's personal characteristics, education, experience in natural resources management, involvement in policy making, and use and evaluation of various sources of information. This study focused on county commissioners representing rural, mixed, and urban counties in Arizona, Nevada, and Utah and collected data through mail surveys and interviews. County commissioners in the survey were well educated; however, few had taken college courses directly addressing technical, management, or legal aspects of water issues. Approximately one-third had direct experience in farming and ranching; nearly two-thirds indicated that farming and ranching played a major role in their communities. Respondents had experience with a broad range of water policy issues. In evaluating thirteen information sources in terms of their frequency of use, relevancy, and reliability, respondents assessed fellow commissioners and local government staff and managers most positively and nonprofit organizations most negatively. The media was also broadly rated as less relevant and reliable than other sources of information. The commissioners in the study expressed a high level of general concern about water issues and a strung preference for local sources of information.