Atmospheric methyl tertiary butyl ether (MTBE) at a rural mountain site in California

Methyl tertiary butyl ether (MTBE) was measured in air samples collected at hourly intervals near Blodgett Forest Research Station on the western slope of the Sierra Nevada, California, in July 1997, October 1998, and June through September 1999. Mixing ratios ranged from below the detection limit (< approximately 0.01 ppbv) to 0.5 ppbv, but were generally less than 0.3 ppbv. At these mixing ratios partitioning of MTBE into surface waters would lead to MTBE concentrations of less than 0.2 microg L(-1). As expected, MTBE mixing ratios were highly correlated with other anthropogenically emitted hydrocarbons. Based on the observed diurnal cycle of MTBE and its ratio to 2-methyl-butane (isopentane), we estimated the average regional daytime oxidant concentration to be (9 to 13) x 10(6) OH radicals per cubic centimeter, consistent with our earlier estimates for this region. Furthermore, MTBE ratios to toluene, another ubiquitous anthropogenic hydrocarbon, were generally consistent with regional transport and dilution, as well as atmospheric oxidation. Exceptions, pertaining to MTBE mixing ratios below or close to the detection limit, were associated with the influence of marine air masses that did not experience anthropogenic hydrocarbon input from California. With all these constraints in place, evidence for an additional atmospheric loss process, such as nonreversible deposition of MTBE, could not be established, and we conclude that any deposition is slow compared with removal from the atmosphere by the OH radical.     

A biotechnological agenda for the third world

Third World countries should exploit the genetic information stored in their flora and fauna to develop independent and highly competitive biotechnological and pharmaceutical industries. The necessary condition for this policy to succeed is the reshaping of their universities and hospitals—to turn them into high-caliber research institutions dedicated to the creation of original knowledge and biomedical invention. Part of the service of the Third World foreign debt should be co-invested with the lending banks in high technology enterprises. This should be complemented with an active program of investments in First World biotech companies and university research departments which could contribute to the solving of problems connected with the First World. These strategic alliances would allow effective training of molecular biologists, improvement of South American universities, and education of biotechnologists, managers, and lawyers in the complexities of high-technology business. The establishment of real joint ventures between developed and underdeveloped countries might contribute to change the present strained relations between the North and the South, and science and technology could become real forces of social and economic development.     

Redistributing the world's wealth: Cancun ‘summit’ discord

The aim of the North-South ‘summit’ conference in 1981 was to bridge the wealth gap between the few industrial nations and the hundred-odd poor countries. Unfortunately no firm proposals materialized. The rich nations refused to increase their aid transfers to the developing countries or to correct the growing inequalities in world trade. The multiplication of wealth is the basic concern of the North in an era of recession and unemployment. The division of wealth is an urgent necessity for the South, but their demands for a global reallocation of resources remained unmet. The gap is likely to widen considerably in future.     

Functional Ecosystems and Biodiversity Buzzwords

Abstract: Several increasingly popular paradigms in conservation remove organismal information and life-history requirements from management planning with claims that species-specific information is not necessary to the understanding and management of "ecosystem function" and may therefore be discarded. Although several authors have called attention to the fact that ecosystem management has not yet been articulated sufficiently to comprise an adequate paradigm for wildlife protection, there has been a series of suggestions paralleling ecosystem management's popularity that the perceived or imagined emergent properties of communities should be at the root of conservation planning. Such reductions most commonly take the form of abstracted species diversity measures that may be irrelevant or misleading with respect to site-specific planning and to the monitoring of specific management treatments. Following earlier examinations of ecosystem management, I emphasize that several of its apparent outgrowths may be too vague to inform specific recommendations, that the historical mechanics of "ecosystem processes" are essentially unknowable, and that anecdotal definitions of ecosystems allow one to justify virtually any protocol as management. The primacy of process-dependent, landscape-functional considerations in conservation planning is specious in the absence of species- and population-specific information, which should form the foundation for understanding such processes in the first place. Only by viewing nature in terms of the relationships between processes and organisms, rather than in terms of emergent properties of organismal assemblages or abiotic factors divorced from organismal data, can conservation plans claim to protect biological elements.     

Apportioning black carbon to sources using highly time-resolved ambient measurements of organic molecular markers in Pittsburgh

We present highly time-resolved measurements of organic molecular markers in downtown Pittsburgh, which are used to investigate sources contributing to atmospheric aerosols in the area. Two-hour average concentrations of condensed-phase and semivolatile organic species were measured using a Thermal Desorption Aerosol GC/MS (TAG). Concentrations for mobile source markers like hopanes had regular diurnal and day-of-week patterns. Pairing high time-resolved measurements with meteorological data helped identify contributions from known point sources for markers correlated with wind direction. Black carbon (BC), volatile organic compounds (VOCs) and organic molecular markers were apportioned to sources using the Chemical Mass Balance (CMB) and Positive Matrix Factorization (PMF) receptor models. Diesel and gasoline mobile source factors were identified as the main sources of BC in the downtown Pittsburgh area, contributing 67% and 20% of the study-average BC. 13% of the BC was associated with a source factor tentatively identified as an industrial or regional source. The high time resolution of the TAG has the potential to provide important new insight into source apportionment efforts using organic molecular marker measurements.     

Asthma and Air Pollution in Two Inner City Areas in New York City

The preliminary analysis of four months of emergency room visits for asthma in two inner city areas containing populations of similar socioeconomic, racial, and ethnic compositions, with similar day to day weather conditions but differing in their day to day levels of air pollution was made, and the relationship of visits to emergency rooms to daily temperature and air pollution levels measured in the areas, are described.

In Harlem no relationship between daily visits to emergency rooms and daily levels of either smokeshade or sulfur dioxide have been observed whereas in Brooklyn a relatively strong correlation between daily visits for asthma and daily levels of sulfur dioxide but not with smokeshade have been observed over and above the effect of temperature. In both areas there was a strong relationship between daily visits for asthma and the first cold spells of the fall season. The average male/female ratio for asthma visits to hospital emergency rooms of both areas in the age group under thirteen years of age was 1.7 and for the over thirteen years of age group was 0.6.

It appears from the data that Brooklyn presents a different picture for the environmental influence on asthma attacks. Even though it has been shown by previous investigators that asthmatics are sensitive to sulfur dioxide, we feel that in our case sulfur dioxide is not necessarily the causative agent, but might rather implicate some other confounding variable (most likely an environmental agent) that is disseminated in the general Bedford-Stuyvesant area in a similar day to day pattern to sulfur dioxide. We infer this from the fact that levels of sulfur dioxide were somewhat higher on the average in the Harlem area than they were in the Brooklyn area.     

Rationale for an Eight-Hour Ozone Standard

As part of the exposure assessment scheme for a community-based air pollution health effects study, 43 homes of study participants, located in two Houston neighborhoods, were monitored for weekly-average indoor formaldehyde levels by means of diffusion samplers. Consecutive 12-hour aldehyde sampling for one-week periods was conducted in 12 of the homes by means of pumps and impingers. In six houses where simultaneous monitoring with both methods occurred, good correlation between the results from the diffusion samplers and the standard impinger method was observed. Diffusion sampler precision was variable and lower than expected, and a small positive measurement bias could be inferred. The distribution of house-average indoor formaldehyde concentrations from diffusion monitoring was similar to that obtained during a previous housing survey in Houston, with concentrations in 19 percent of the homes exceeding 0.10 ppm. Formaldehyde levels in this group of conventional, mostly older homes could not be associated with smoking, cooking, home age or structure type. However, there was a statistically significant difference between mean indoor concentrations in the two neighborhoods.     

Can Basin Land Use Effects on Physical Characteristics of Streams Be Determined at Broad Geographic Scales?

The environmental setting (e.g., climate, topography, geology) and land use affect stream physical characteristics singly and cumulatively. At broad geographic scales, we determined the importance of environmental setting and land use in explaining variation in stream physical characteristics. We hypothesized that as the spatial scale decreased from national to regional, land use would explain more of the variation in stream physical characteristics because environmental settings become more homogeneous. At a national scale, stepwise linear regression indicated that environmental setting was more important in explaining variability in stream physical characteristics. Although statistically discernible, the amount of variation explained by land use was not remarkable due to low partial correlations. At level II ecoregion spatial scales (southeastern USA plains, central USA plains, and a combination of the western Cordillera and the western interior basins and ranges), environmental setting variables were again more important predictors of stream physical characteristics, however, as the spatial scale decreased from national to regional, the portion of variability in stream physical characteristics explained by basin land use increased. Development of stream habitat indicators of land use will depend upon an understanding of relations between stream physical characteristics and environmental factors at multiple spatial scales. Smaller spatial scales will be necessary to reduce the confounding effects of variable environmental settings before the effects of land use can be reliably assessed.