On the propagation of error in air pollution measurements

Four methods for estimating the uncertainties in air pollution measurements are outlined. The approaches are: analytical solution-approximation; application of distribution theory; experimentation; and simulation. The advantages and disadvantages of each method are illustrated using data from High-Volume air samplers, the instrument most commonly used for monitoring ambient concentrations of airborne particles.Dr Evans is Assistant Professor of Environmental Science and Mr Kinney is a doctoral candidate in the Department of Environmental Science and Physiology, Harvard School of Public Health. Dr Cooper is at the Manufacturing Research Laboratory, Thomas J. Watson Research Center, IBM, Yorktown Heights, NY.     

POLICIES FOR RESOLVING THE CLIMATE CHANGE AND THE STRATOSPHERIC OZONE DEPLETION ISSUES: ANTAGONISTIC OR RE-ENFORCING?

Unlike the past, anthropogenic activities have begun to have greaterand greater impact on the environment. Policy formulation is no longerconfined to just responding to an existing set of environmentalconditions, but involves taking into account how the decision mightaffect the original set of environmental conditions to which the originalpolicy was formulated as a response.We discuss how certain policies could be developed, using the resultsfrom two integrated scientific models which incorporate parametersreflecting two air issues: (1) climate change, and (2) stratospheric ozonedepletion. Model results suggest very clearly that these two air issuesare not scientifically independent from each other. Following asingle-issue policy would lead to inconsistencies and undesirableconsequences in other related issues. Thus, the policy decision processhas now become complex.One of the sources of this complexity is the uncertainty in the responseof the environmental system to certain policy decisions, complexityarising from the fact that the environmental system is highly nonlinearand evolving. Model results indicate that it is essential for the policyformulation process to be flexible enough to take into account thenonlinear evolutionary nature of the environmental system. A policymust reflect, and be tailored to, the dynamical history and present stateof the system, if it is to be effective in influencing the future evolution of the system.     

Variable resource defense by the Tana River crested mangabey

Summary Behavioral observations over 16 months of two groups of Tana River crested mangabeys (Cercocebus galeritus galeritus) in East Africa provide evidence, contrary to previous reports, for site-specific aggression and territorial exclusion. In addition, movements and vocal responses to neighboring group's long-call vocalizations vary temporally, reflecting seasonal variation in food availability and distribution. Patterns of response to neighboring groups are consistent with the hypothesis that resources should be defended only when it is economic to do so. When fruit resources are rare intergroup interactions are infrequent and groups use separate areas. As fruit availability increases, the distribution of diet species influences the type of interaction; peaceful intergroup interactions generally occur when mangabeys eat uniformly distributed species and aggressive interactions occur when mangabeys eat species with patchy distributions. Differences between male vocal responses and group spatial responses may reflect conflicting objectives of territorial defense by males and females.     

Nonylphenolic compounds in drinking and surface waters downstream of treated textile and pulp and paper effluents: a survey and preliminary assessment of their potential effects on public health and aquatic life

Eleven drinking water treatment plants, located downstream of textile plants or pulp and paper mills, have been sampled monthly during a year for the analysis of 17 nonylphenol ethoxylates (NP1-17EO) and two nonylphenoxycarboxylic acids (NP1-2EC). At all but one plant, results in the drinking water, for the sum of these 19 substances, range between below detection levels and 6.7 microg/l. Annual means are between 0.02 and 2.8 microg/l. At the other plant, the yearly average concentration is 10.4 microg/l and the monthly maximum is 43.3 microg/l. In the surface (pre-treatment) water, the annual mean concentrations of the 11 plants range between 0.14 and 17.8 microg/l and the recorded instantaneous maximum is 55.3 microg/l. According to Canadian health authorities, drinking water is a negligible route of human exposure to nonylphenolic compounds, even at the highest concentrations found in this study. After transformation of the data into nonylphenol equivalents, about 20% of the surface water samples exceed the Canadian 1 microg/l nonylphenol water quality guideline for the protection of aquatic life. Some results also exceed Québec's 6 microg/l nonylphenol guideline. The efficiency of the plants in removing nonylphenolic compounds from drinking water is highly variable, ranging from 11% to 99%.     

Evolution of the magnitude and spatial extent of the weekend ozone effect in California's South Coast Air Basin, 1981-2000

Since the mid-1970s, ozone (O3) levels in portions of California's South Coast Air Basin (SoCAB) on weekends have been as high as or higher than levels on weekdays, even though emissions of O3 precursors are lower on weekends. Analysis of the ambient data indicates that the intensity and spatial extent of the weekend O3 effect are correlated with-day-of-week variations in the extent of O3 inhibition caused by titration with nitric oxide (NO), reaction of hydroxyl radical (OH) with nitrogen dioxide (NO2), and rates of O3 accumulation. Lower NO mixing ratios and higher NO2/oxides of nitrogen (NOx) ratios on weekend mornings allow O3 to begin accumulating approximately an hour earlier on weekends. The weekday/weekend differences in the duration of O3 accumulation remained relatively constant from 1981 to 2000. In contrast, the rate of O3 accumulation decreased by one-third to one-half over the same period; the largest reductions occurred in the central basin on weekdays. Trends in mixing ratios of O3 precursors show a transition to lower volatile organic compound (VOC)/NOx ratios caused by greater reductions in VOC emissions. Reductions in VOC/NOx ratios were greater on weekdays, resulting in higher VOC/NOx ratios on weekends relative to weekdays. Trends in VOC/NOx ratios parallel the downward trend in peak O3 levels, a shift in the location of peak O3 from the central to the eastern portion of the basin, and an increase in the magnitude and spatial extent of the weekend O3 effect.     

Using markets for land preservation: Results of a TDR program

This paper reviews different approaches to using transferable development rights (TDRs) as a way to preserve rural lands in the face of development pressure. One TDR program is examined in detail, that of Calvert County, Maryland, which has had an active TDR market since the mid-1980s. This program uses TDRs as a key policy tool for achieving a total amount of preserved acreage in the county, and for providing incentives for preservation in some areas and development in others. The paper examines both the early difficulties in developing participation in the program, and the events that lead eventually to an active TDR market. It assesses the workings of the market including factors that influence the demand and supply of TDRs, the movement of prices over time, and the location of preserved areas and of additional developed areas. The study found that the program is achieving many of the county's land preservation goals because of the high level of activity in the TDR market. However, most of the additional density is being channeled into rural areas with underlying low-density zoning.     

BLACK WILLOW CUTTING SURVIVAL IN STREAMBANK PLANTINGS,SOUTHEASTERN UNITED STATES1

Field studies were conducted on black willow (Salix nigra) cuttings planted for riparian zone restoration along Harland Creek, Twentymile Creek, and Little Topashaw Creek in Mississippi, USA. Planted cuttings were 2.5 to 3 m long and had base diameters of 2.5 to 7.5 cm. Streams were unstable, deeply incised sand bed channels with eroding banks 1 to 6 m high. Soil texture, redox potential (Eh), depth to water table, and willow survival were monitored for two to three years after planting. While many factors influence willow cuttings at restoration sites, soil texture and moisture are key to plant success. In these studies, plant survival and growth were best for cuttings planted in soils with less than 40 percent silt‐clay content and a water table 0.5 m to 1.0 m below the soil surface during the growing season. These conditions produced soil Eh greater than approximately 200 mV and were most often observed 1 to 2 m higher than the bank toe. These findings suggest criteria useful for preplanting site evaluations. Additional evidence suggests that preplanting soaking enhances performance of black willow cuttings. Additional factors (channel erosion, herbivory by beaver, and competition from exotics) may control performance over periods longer than two to three years.     

Moisture effects in heat transfer through clothing systems for wildland firefighters.

Wildland firefighters work in unfavourable environments involving both heat and moisture. Moisture in clothing systems worn by wildland firefighters may increase or decrease heat transfer, depending on its source and location in the clothing system, location on the body, timing of application and degree of sorption. In this experiment, 4 outerwear/underwear combinations were exposed to 1 of 5 different conditions varying on amount and location of moisture. The fabric systems were then exposed to either a high-heat-flux flame exposure (83 kW/m(2)) or a low-heat-flux radiant exposure (10 kW/m(2)). Under high-heat-flux flame exposures, external moisture tended to decrease heat transfer through the fabric systems, while internal moisture tended to increase heat transfer. Under low-heat-flux radiant exposures, internal moisture decreased heat transfer through the fabric systems. The nature and extent of such differences was fabric dependent. Implications for test protocol development are discussed.