The Transit of 35SO4 2- and 3H2O Added In Situ to Soil in a Boreal Coniferous Forest

A solution containing ³⁵SO₄ ^2- and ³H₂O was applied to four plots (5 × 5 m) in a boreal coniferous forest in the Laflamme Lake watershed, Québec, under two contrasting conditions: in summer (plots 1 and 2), and on the snowpack before snowmelt (plots 3 and 4). The transit of both these tracers in the soil solution was then followed through a network of soil lysimeters located at different depths. Four months after the summer application, ³H₂O had infiltrated the whole soil profile at plot 1, while ³⁵SO₄ ^2- was only observed in the LFH and Bhf horizons. A ³⁵SO₄ ^2- budget calculated from mid-August to November indicated that 89 and 10.6% of the added ³⁵SO₄ ^2- was retained within the LFH and the Bhf layers, respectively. Fifteen months later, the added ³⁵SO₄ ^2- was distributed in the following proportions within the soil horizons: LFH (73.7%), Bhf (11.8%) and Bf (12.8%), for a total retention rate of 98.3%. The superficial penetration of ³H₂O at plot 2 was indicative of a major lateral water movement that prevented the calculation of a ³⁵SO₄ ^2- budget. This situation also was observed at plot 4 during snowmelt. At plot 3, ³H₂O moved freely through the soil profile and a significant fraction of the added ³⁵SO₄ ^2- reached the B horizons, where it was presumably adsorbed on aluminum (Al) and ferric (Fe) oxides. The ³⁵SO₄ ^2- budget for plot 3 from March to November indicated that 87% of the added ³⁵SO₄ ^2- was retained within the soil profile, with most being retained in the B horizons (LFH = 33.1%, Bhf = 33.1%, Bf = 20.8%). The contrasting retention patterns of ³⁵SO₄ ^2- within the soil profile following the summer addition and snowmelt likely was caused by the contrastingsoil temperatures and soil solution residence times within the differentsoil layers. The persistence of ³⁵SO₄ ^2- in the soil solution of the entire profile long after the initial tracer infiltration, and the relative temporal stability of specific activity of SO₄ ^2-, point to the establishment of an isotopic equilibrium between the added ³⁵SO₄ and the active S-containing reservoirs within a given soil horizon. Overall, the results clearly illustrate the very strong potential for ³⁵SO₄ ^2- retention and recycling in forest soils.     

Transition to self‐directed work teams: implications of transition time and self‐monitoring for managers' use of influence tactics

In the face of heightened competitive pressures, elevated quality expectations, and calls for worker empowerment, more and more organizations have turned to self‐directed work teams (SDWTs). A review of the literature devoted to SDWTs suggests that managers often struggle with the transition to SDWTs because of the required shift in control to SDWT members. To promote the development of work teams, managers must modify their use of influence tactics in direct response to the control shift. In this study, we explore changes in managers' usage of influence tactics during the transition to SDWTs within a large aluminum manufacturing plant. Analyses of longitudinal data show that despite the new team environment, managers' use of influence tactics was focused at the individual level. We also found that transition time accounts for variance in managers' choices of influence tactics. Finally, an exploratory analysis suggests that high as opposed to low self‐monitoring managers may be more prone to increase their usage of soft influence tactics and decrease their usage of hard influence tactics over the course of the transition; the influence behavior of low self‐monitoring managers remained unchanged. Implications for future research are discussed. Copyright © 2004 John Wiley & Sons, Ltd.     

Client–project manager engagements,trust, and loyalty

This study addresses the behaviors of project managers under various conditions of cognitive and affective trust, and the implications for obtaining client loyalty. Theoretical foundations were drawn from interpersonal and interorganizational trust literature. A test of the proposed theoretical framework was conducted in a field setting utilizing a matched design of both project managers and their clients. The results show that reliable project performance positively impacted client loyalty intentions and service‐oriented OCBs positively impacted client secondary retention. An interaction showed that in low cognitive trust situations the project manager behavior of reliable project performance facilitated the obtainment of client loyalty intentions. Implications for research and practice are discussed. Copyright © 2004 John Wiley & Sons, Ltd.     

MODELING THE IMPACT OF MULTICOMPONENT VOCs ON GROUND WATER USING THE STEFAN‐MAXWELL EQUATION1

ABSTRACT: Computer programs that model the fate and transport of organic contaminants through porous media typically use Fick's first law to calculate vapor phase diffusion. Fick's first law, however, is limited to the case of a single, dilute species diffusing into a stagnant, high concentration, bulk vapor phase. When dealing with more than one diffusing species and at higher concentrations, the multicomponent coupling effects on vapor phase diffusion and advection of the various constituents become significant. VLEACH, a one‐dimensional finite difference model developed for the U.S. Environmental Protection Agency (USEPA), is typical of the models using Fick's first law to model vapor‐phase diffusion. The VLEACH model was modified to accommodate up to 10 components and to calculate the binary diffusion coefficients for each of the components based on molecular weight, molecular volume, temperature and pressure, and to address the coupling effects on multiple component vapor phase diffusion and its impact on ground water. The resulting model was renamed MC‐CHEMSOIL. At low vapor phase concentrations, MC‐CHEMSOIL predicts identical ground water impacts (dissolved phase loading) to those from VLEACH 2.2a. At higher vapor phase concentrations, however, the relative difference between the models exceeded 20 percent.     

REGION,LANDSCAPE, AND SCALE EFFECTS ON LAKE SUPERIOR TRIBUTARY WATER QUALITY1

ABSTRACT: In 1998 and 1999, third‐order watersheds in high mature forest (HMF) and low mature forest (LMF) classes were selected along gradients of watershed storage within each of two hydrogeomorphic regions in the Lake Superior Basin to evaluate threshold effects of storage on hydrologic regimes and watershed exports. Differences were detected between regions (North and South Shore) for particulates, nutrients, and pH, with all but silica values higher for South Shore streams (p < 0.05). Mature forest effects were detected for turbidity, nutrients, color, and alkalinity, with higher values in the LMF watersheds, that is, watersheds with less that 50 percent mature forest cover. Dissolved N, ammonium, N:P, organic carbon, and color increased, while suspended solids, turbidity, and dissolved P decreased as a function of storage. Few two‐way interactions were detected between region and mature forest or watershed storage, thus threshold based classification schemes could be used to extrapolate effects across regions. Both regional differences in water quality and those associated with watershed attributes were more common for third‐order streams in the western Lake Superior drainage basin as compared with second‐order streams examined in an earlier study. Use of ecoregions alone as a basis for setting regional water quality criteria would have led to misinterpretation of reference condition and assessment of impacts in the Northern Lakes and Forest Ecoregion.     

火电厂烟气脱硫装置的性能检测

详细介绍了火电厂烟气脱硫装置性能检测的指标、系统、组织、流程和方法,为脱硫工程后评估中脱硫装置的性能考核和验收检测提供了技术支持和指导。     

The effects of parental altruism on the governance of family‐managed firms

We draw on the economic, corporate governance, and family business literatures to explain why the effects of family on family firms makes this governance form theoretically distinct from those of public and private non‐family firms. Our thesis is that parental altruism, when combined with private ownership and owner‐management, influences the ability of the firm's owner‐manager to exercise self‐control, which, in turn, can expose some family firms to conflicts rooted in the agency threats of moral hazard, hold‐up, and adverse selection. We then discuss why some other family firms are able to minimize these dark side threats and thereby attain altruism's brighter side. Finally, we discuss how altruism's influence changes over time as ownership becomes dispersed among family members and across generations. Copyright © 2005 John Wiley & Sons, Ltd.     

Rapid amino acid cycling in arctic and antarctic soils

Amino acids constitute one of the largest inputs of organic nitrogen (N) to most polar soils and have been hypothesized to be important in regulating vegetational succession and productivity in Arctic ecosystems. Our understanding of amino acid cycling in these soils, however, is poor. The aim of this study was to investigate the size and rate of turnover of the amino acid pool in a range of Arctic and Antarctic soils. Our results indicate that in polar soils with either high or low ornithogenic inputs the amino acid pool is small in comparison to the inorganic N pool (NO^? ₃ and NH⁺ ₄). The free amino acid pool constituted only a small proportion of the total dissolved organic nitrogen (DON) pool in these soils. Here we show that these low concentrations may be due to rapid use by the soil microbial community in both Arctic and Antarctic soils. The turnover of the amino acid pool in soil was extremely rapid, with a half-life ranging from 2 to 24 h, indicating that this N pool can be turned over many hundred times each summer when polar soils are frequently unfrozen. The implications of amino acids in N cycling and plant and microbial nutrition are discussed.     

An automated wet deposition system to compare the effects of reduced and oxidised N on ombrotrophic bog species: Practical considerations

Critical N loads for ombrotrophic bogs, which often contain rare and N-sensitive plants (especially those in lower plant groups: lichens, mosses and liverworts), are based on very few experimental data from measured, low background N deposition areas. Additionally the relative effects of reduced versus oxidised N are largely unknown. This paper describes an automated field exposure system (30 km S. of Edinburgh, Scotland) for treating ombrotrophic bog vegetation with fine droplets of oxidised N (NaNO₃) and reduced N (NH₄Cl). Whim Moss exists in an area of low ambient N deposition (ca. 8 kg N ha^?1 y^?1), the sources and quantification of which are described. The wet N treatment system is run continuously, and is controlled/activated by wind speed and rainfall to provide a unique simulation of “real worl” treatment patterns (no rain=no treatment). Simulated precipitation is supplied at ionic concentrations below 4 mM in rainwater collected on site. Treatments provide a replicated dose response to 16, 32 and 64 kg N ha^?1 y^?1 adjusted for ambient deposition (8 kg N ha^?1 y^?1). The 16 and 64 kg N ha^?1 y^?1 are duplicated with a P+K supplement. Baseline soil chemistry and foliar nutrient status was established for all 44 plots for Calluna vulgaris, Sphagnum capillifolium, Hypnum jutlandicum and Cladonia portentosa.