Nitrogen uptake kinetics in three year-classes of Laminaria groenlandica (Laminariales: Phaeophyta)

Nitrate and ammonium uptake rates were measured for three year-classes of the perennial macrophyte Laminaria groenlandica Rosenvinge, collected from nitrogen-depleted waters in Barkley Sound, British Columbia, Canada, in summer 1981. A time course of uptake rate revealed that ammonium uptake was high during the first hour and then decreased for all three year-classes; the opposite pattern was exhibited for the time course of nitrate uptake rate. Nitrate uptake rate increased linearly with nitrate concentration up to the highest level tested (60 M). The nitrate uptake rate of first-year plants was three times higher than second- and third-year plants; ammonium uptake rates showed similar patterns to those for nitrate. The interaction between nitrate and ammonium was examined for first-year plants. Nitrate and ammonium were taken up simultaneously and uptake rates were identical and equal to uptake rates when only nitrate or ammonium was present in the medium. Therefore, first-year plants are able to take up twice as much inorganic nitrogen per unit time when both nitrate and ammonium are present. First-year plants showed significant diel periodicity in ammonium uptake rates, whereas second- and third-year plants showed no periodicity in nitrate or ammonium uptake rates.     

Acquired changes in stomatal characteristics in response to ozone during plant growth and leaf development of bush beans (Phaseolus vulgaris L.) indicate phenotypic plasticity

Bush bean (Phaseolus vulgaris L.) lines 'S156' (O3-sensitive)/'R123' (O3-tolerant) and cultivars 'BBL 290' (O3-sensitive)/'BBL 274' (O3-tolerant) were used to study the effects of O3 on stomatal conductance (gs), density, and aperture size on leaf and pod surfaces with the objective of establishing links between the degree of plant sensitivity to O3 and plasticity of stomatal properties in response to O3. Studies in open-top chambers (OTCs) and in continuously stirred tank reactors (CSTRs) established a clear relationship between plant developmental stages, degrees of O3 sensitivity and gs: while 'S156' had higher gs rates than 'R123' earlier in development, similar differences between 'BBL 290' and 'BBL 274' were observed at later stages. Gs rates on the abaxial leaf surfaces of 'S156' and 'BBL 290', accompanied by low leaf temperatures, were significantly higher than their O3-tolerant counterparts. Exposure to O3 in CSTRs had greater and more consistent impacts on both stomatal densities and aperture sizes of O3-sensitive cultivars. Stomatal densities were highest on the abaxial leaf surfaces of 'S156' and 'BBL 290' at higher O3 concentrations (60 ppb), but the largest aperture sizes were recorded on the adaxial leaf surfaces at moderate O3 concentrations (30 ppb). Exposure to O3 eliminated aperture size differences on the adaxial leaf surfaces between sensitive and tolerant cultivars. Regardless of sensitivity to O3 and treatment regimes, the smallest aperture sizes and highest stomatal densities were found on the abaxial leaf surface. Our studies showed that O3 has the potential to affect stomatal plasticity and confirmed the presence of different control mechanisms for stomatal development on each leaf surface. This appeared to be more evident in O3-sensitive cultivars.     

Remediation of metal polluted mine soil with compost: co-composting versus incorporation

Trace element contamination of post-industrial sites represents a major environmental problem and sustainable management options for remediating them are required. This study compared two strategies for immobilizing trace elements (Cu, Pb, Zn, and As) in mine spoil: (1) co-composting contaminated soil with organic wastes and (2) conventional incorporation of mature compost into contaminated soil. Sequential chemical extraction of the soil was performed to determine temporal changes in trace element fractionation and bioavailability during composting and plant growth. We show that mine spoil can be co-composted successfully and this action causes significant shifts in metal availability. However, co-composting did not lead to significant differences in metal partitioning in soil or in plant metal uptake compared with simply mixing mine spoil with mature compost. Both treatments promoted plant growth and reduced metal accumulation in plants. We conclude that co-composting provides little additional benefit for remediating trace-element-polluted soil compared with incorporation of compost.     

Designing a sustainable facility to improve energy and environmental performance at the women's humane society

Susan Maxman Architects was selected to design a new facility for the Women's Humane Society. The project, located on a disturbed site in Bensalem, Pennsylvania, presented an environmental challenge as a large part of the site is wetlands and the site is home to a large PECO power line. This case study describes the process of designing a facility that incorporates the concerns of environmental responsibility. It will show how the decisions in the design of the built environment can very much influence the well-being of the natural environment. It describes the ways in which the client was convinced that it was of great benefit to create a facility that was energy-efficient and environmentally sensitive. The article also explores the successes and failures of this process. It discusses barriers that exist in comprehensively incorporating sustainable design principles in these facilities and shows how it is applicable for the development of other facilities.     

Data,data everywhere but not a byte to read: Managing monitoring information

The problem of managing scientific information for widespread availability and use can be overwhelming. At Oregon State University, the Quantitative Sciences Group has found a workable solution. The group has developed a Forest Science Data Bank (FSDB) to house data generated by scientists and collaborating researchers in the Andrews Long-Term Ecological Research program. Today the FSDB houses some 2400 data sets from over 350 existing ecological studies and adds about 20 new studies yearly. This paper describes what we have learned in setting up the FSDB as a facility that can be used by researchers who both deposit information in and retrieve information from the FSDB.     

Technical‐administrative task performance,leadership task performance,and contextual performance: considering the influence of team‐ and task‐related composition variables

The purpose of the present study was to examine how the mix of ability, experience, and personality impacts three types of team performance: technical‐administrative task performance, leadership task performance, and contextual performance. Relationships were tested using data collected from student management teams, who were required to plan and supervise the preparation and service of meals in a cafeteria‐style dining room patronized by university students, staff, and faculty. Results revealed that both team‐ and task‐related composition variables predicted leadership and contextual performance. Specifically, grade point average was significantly related to technical‐administrative task performance, and extraversion, neuroticism, and grade point average were related to leadership task performance. Agreeableness and restaurant experience predicted contextual performance. Surprisingly, conscientiousness did not account for significant variance in any of the three types of performance measured. The implications of these findings for the study of team performance in organizations are discussed. Copyright © 2002 John Wiley & Sons, Ltd.