Using a CHN analyzer to reduce carbonate interference in particulate organic carbon analyses

Using a CHN analyzer at a reduced temperature (720°C), the organic carbon of particulates taken from water is oxidized while little, if any, dissociation of carbonate occurs. When necessary for increased precision or for samples with a high CaCO₃ content, the small interference of carbonate with organic C determinations can be quantified by running representative samples at different oxidation time intervals and interpolating to time zero. By running replicates, one at 720°C and one at 1100°C, data on organic and inorganic carbon and on nitrogen are obtained with the analyzer.     

Experimental ecology of the temperate scleractinian coral Astrangia danae

The combined effects of temperature, light and symbiont density on the metabolic rate and calcification of the temperate coral Astrangia danae were studied experimentally using colonies containing different concentrations of zooxanthellae. After acclimation to five temperatures between 6.5° and 27°C, and incubation at three light levels and in darkness, respiration and photosynthesis were measured and corrected for rates due to commensals alone. Calcification rates were regressed on zooxanthellae concentration and production in order to define “symbiotic” and “non-symbiotic” averages, and the enhancement of calcification by symbiotic interactions in the polyps. Respiration by the polyparium varied less with temperature between 11.5° and 23°C than that of the commensals, suggesting physiological acclimation by the coral tissue. In-vivo zooxanthellae photosynthesis increased linearly with temperature and was near its maximum at 400 μEin m^?2 s^?1, but the photosynthesis of the endolithic algae of the corallum varied little between 11.5° and 27°C. Calcification at any given temperature was near its maximum at 40 μEin m^?2 s^?1 in both symbiotic and non-symbiotic corals. CaCO₃ deposition increased linearly with temperature in non-symbiotic colonies and in symbiotic colonies incubated in the dark. In symbiotic colonies, calcification in the light increased above these basic rates as temperature rose above 15°C. Below 15°C, symbiotic interactions failed to stimulate calcification, apparently due both to a lowering of zooxanthellae photosynthesis and to a decrease in the enhancing effect of any given level of primary production.     

Effect of air pollution on peri-urban agriculture: a case study

Peri-urban agriculture is vital for the urban populations of many developing countries. Increases in both industrialization and urbanization, and associated air pollution threaten urban food production and its quality. Six hour mean concentrations were monitored for SO(2), NO(2) and O(3) and plant responses were measured in terms of physiological characteristics, pigment, biomass and yield. Parameter reductions in mung bean (Vigna radiata), palak (Beta vulgaris), wheat (Triticum aestivum) and mustard (Brassica compestris) grown within the urban fringes of Varanasi, India correlated directly with the gaseous pollutants levels. The magnitude of response involved all three gaseous pollutants at peri-urban sites; O(3) had more influence at a rural site. The study concluded that air pollution in Varanasi could negatively influence crop yield.     

A review of recent developments in European environmental planning

Since the late 1980s planners have had to start adjusting, much more quickly and fully than before, to the challenges posed by environmental issues. This applies at all potential levels of action, from the urban through the regional and national up to the European. A selection of recent work and ideas at each of these levels is discussed. Some of the complexities of the interrelations of sectors and levels are explored. The need for the more effective and more rapid exchange of experience and research across Europe is stressed, if urban and regional planning is to fulfil its potential as an instrument of preventative environmental policy.     

Monitoring of growth and yield and response to silvicultural treatments

The objectives for monitoring the growth and yield of forests can range from collecting data to validate current management on an ownership to collecting data at a regional level to develop models, measure treatment response, or observe long-term growth trends. Traditional inventory and research data each have drawbacks for observing growth and yield and treatment response. The actual design of a monitoring system should try to minimize these problems, but will depend on the specific objectives. Monitoring of operations may take an inventory-type approach, while gathering regional information to build models requires a design more like research. Each organization must be responsible for monitoring its own operations, however, cooperatives offer a viable and cost effective alternative to gathering regional growth and response data. Monitoring programs will lead to confidence and credibility in management practices and in the use of tested models.     

Validation of an electronic device for measuring driving exposure

OBJECTIVE: This study sought to evaluate an on-board diagnostic system (CarChip) for collecting driving exposure data in older drivers. METHODS: Drivers (N = 20) aged 60 to 86 years from Winnipeg and surrounding communities participated. Information on driving exposure was obtained via the CarChip and global positioning system (GPS) technology on a driving course, and obtained via the CarChip and surveys over a week of driving. Velocities and distances were measured over the road course to validate the accuracy of the CarChip compared to GPS for those parameters. RESULTS: The results show that the CarChip does provide valid distance measurements and slightly lower maximum velocities than GPS measures. From the results obtained in this study, it was determined that retrospective self-reports of weekly driving distances are inaccurate. CONCLUSIONS: Therefore, an on-board diagnostic system (OBDII) electronic device like the CarChip can provide valid and detailed information about driving exposure that would be useful for studies of crash rates or driving behavior.     

Managing compost stability and amendment to soil to enhance soil heating during soil solarization

Soil solarization is a method of soil heating used to eradicate plant pathogens and weeds that involves passive solar heating of moist soil mulched (covered) with clear plastic tarp. Various types of organic matter may be incorporated into soil prior to solarization to increase biocidal activity of the treatment process. Microbial activity associated with the decomposition of soil organic matter may increase temperatures during solarization, potentially enhancing solarization efficacy. However, the level of organic matter decomposition (stability) necessary for increasing soil temperature is not well characterized, nor is it known if various amendments render the soil phytotoxic to crops following solarization. Laboratory studies and a field trial were performed to determine heat generation in soil amended with compost during solarization. Respiration was measured in amended soil samples prior to and following solarization as a function of soil depth. Additionally, phytotoxicity was estimated through measurement of germination and early growth of lettuce seedlings in greenhouse assays. Amendment of soil with 10% (g/g) compost containing 16.9 mg CO₂/g dry weight organic carbon resulted in soil temperatures that were 2–4 °C higher than soil alone. Approximately 85% of total organic carbon within the amended soil was exhausted during 22 days of solarization. There was no significant difference in residual respiration with soil depth down to 17.4 cm. Although freshly amended soil proved highly inhibitory to lettuce seed germination and seedling growth, phytotoxicity was not detected in solarized amended soil after 22 days of field solarization.