Nanoparticle and ultrafine particle events at the Fresno supersite

Continuous measurements of particle size distributions of 3-407 nm were collected from August 2002 to July 2004 at the Fresno Supersite to understand their number concentrations, size distributions, and formation processes. Measurements for fine particulate matter (PM2.5) mass, sulfate (SO4(2-)), nitrate (NO3-), black carbon (BC), particle-bound polycyclic aromatic hydrocarbons (PAHs), nitrogen oxides (NOx), carbon monoxide (CO), ozone (O3), and meteorological data (wind speed, wind direction, temperature [T], relative humidity [RH], and solar radiation) were used to determine the causes of nanoparticle (3-10 nm) and ultrafine (10-100 nm) particle events. These events were found to be divided into four types: (1) 3- to 10-nm morning nucleation; (2) 10- to 30-nm morning traffic; (3) 10- to 30-nm afternoon photochemical; and (4) 50- to 84-nm evening home heating, including residential wood combustion. Intense examples of the first type (>10(4) number [#]/cm3) were observed on 29 days, nearly always during the summer. The second type of event was observed on more than 73 days and occurred throughout the year. The third type was observed on 36 days, from spring through summer. The fourth type was found on 109 days, all of them during the winter. Although sulfur dioxide (SO2) emissions in Central California are low, the small residual amounts in gasoline and diesel fuel are apparently sufficient to initiate nucleation events. These were measured in the morning, soon after the shallow surface inversion coupled with layers aloft where nucleation probably was initiated. PM2.5 concentrations were poorly correlated with nanoparticle number.     

Psychological success and the boundaryless career

The boundaryless career could be a bane or boon to people's experience of psychological success. This paper describes the contours of the boundaryless career and then looks at how workers will have to deal with aging over several career cycles, integrate diverse experiences into their identities, and come to terms with new types of employer-employee relationships. This introduces the idea of finding psychological success in one's life work, encompassing not only a job and an organization, but also work as a spouse, parent, community member, and as a self-developer.     

The job satisfaction of older workers

Older workers re-entering the workforce and those changing jobs are coming to play an increasingly important role in the labor force, especially as part-time workers. Yet the work orientation and job satisfaction of these workers has not been studied. Do ‘situational’ factors such as skill and pay matter for this subgroup of workers, and if so, which ones? If significant factors exist, can their effect be explained by the mediating influence of ‘dispositional’ factors like work values? This paper explores these questions in a study of 198 older workers who had begun new, mostly part-time jobs. Regression analysis shows that the intrinsic indicators for skill and autonomy have a positive effect on job satisfaction. No extrinsic factor was significantly related to satisfaction, indicating that these workers are more than ‘instrumentally’ oriented. This support for a ‘situational’ interpretation of the impact of work, especially intrinsic features, was sustained in analyses which incorporated work values. To the extent that the growing number of part-time jobs are relatively low-skilled, and to the extent that older workers in new jobs are influenced most by intrinsically rewarding work, there appears to be a growing mismatch between an occupational niche and those who are being sought to fill it.     

Background ozone levels of air entering the west coast of the US and assessment of longer-term changes

An analysis of surface ozone measurements at a west coast site in northern California (Trinidad Head) demonstrates that this location is well situated to sample air entering the west coast of the US from the Pacific Ocean. During the seasonal maximum in the spring, this location regularly observes hourly average ozone mixing ratios 50 ppbv in air that is uninfluenced by the North American continent. Mean daytime values in the spring exceed 40 ppbv. A location in southern California (Channel Islands National Park) demonstrates many of the characteristics during the spring as Trinidad Head in terms of air flow patterns and ozone amounts suggesting that background levels of ozone entering southern California from the Pacific Ocean are similar to those in northern California. Two inland locations (Yreka and Lassen Volcanic National Park) in northern California with surface ozone data records of 20 years or more are more difficult to interpret because of possible influences of local or regional changes. They show differing results for the long-term trend during the spring. The 10-year ozone vertical profile measurements obtained with weekly ozonesondes at Trinidad Head show no significant longer-term change in tropospheric ozone.     

Increasing the effectiveness of environmental decision support systems: lessons from climate change adaptation projects in Canada and Australia

Regional Environmental Change - There is a need to increase regional and community level action towards adaptation to climate change. Natural resource managers and planners have to make challenging...     

Tillage, crop rotation, and organic amendment effect on changes in soil organic matter

Carbon sequestration in agricultural soils is controlled by the balance of added organic residues and microbial oxidation of both residues and native organic matter (OM) as moderated by management and tillage. The PC-based model CQESTR predicts decomposition of residues, organic amendments and soil OM, based on cropping practices. CQESTR uses RUSLE (Revised Universal Soil Loss Equation) crop rotation and management practice, crop production, and operation databases. These data are supplemented with residue nitrogen and soil OM, bulk density, and layer thickness. CQESTR was calibrated with soil carbon data from 70-year-long experiments at the Research Center at Pendleton, OR. The calibrated model provides estimates with a 95% confidence interval of 0.33% OM. Validation at 11 independent sites resulted in a matching of observed with calculated OM with a 95% confidence interval of 0.55% OM. A 12th site, with a history of severe erosion, provided a poor match.     

Partitioning and bioaccumulation of cadmium in artificial sediment systems: application of a stable isotope tracer technique

The utility of stable isotope tracers for investigating the relationship between cadmium (Cd) partitioning in artificial sediment-water systems and Cd accumulation in a benthic detritivore (Asellus racovitzai, Isopoda) was explored. In the laboratory, Cd isotopes were applied to synthetic sediment and isotope concentrations were measured in sediment, overlying water and exposed asellids over a 10-day period. Isotope ratios measured in sediment and water were compared to ratios measured in asellids to determine whether Cd partitioning could predict metal bioaccumulation. Two different parameters which might affect Cd partitioning between the sediment and overlying water compartments were investigated: the chemical form in which Cd was added to systems, and the organic matter content of the sediment. To test the effect of chemical form on Cd partitioning, three isotopes of cadmium were individually applied to formulated sediment in varying combinations of 113Cd(NO3)2, 112Cd-humic acid (HA) 114CdSO4. The results demonstrated that chemical form did not influence partitioning, as the Cd isotope that was applied to sediment in the nitrate form exhibited similar partitioning between sediment and overlying water as the isotope that was applied in the sulfate or HA form. However, Cd isotope concentrations in overlying water were strongly related to the pattern of isotope accumulation in asellids suggesting that overlying water concentrations determined Cd bioaccumulation. In contrast, when the organic matter content of sediment was increased through the addition of Sphagnum peat moss, total Cd concentrations in overlying water and tissue were low, and there was no relationship between Cd-isotope concentrations in tissue and water. These results indicate that Cd accumulation occurred primarily from water, and factors that increase metal partitioning to sediment, such as increased sediment organic matter content, decrease Cd accumulation in asellids. The stable isotope tracer method described herein appears to be a useful technique for investigating the relationship between metal partitioning and bioaccumulation in simple sediment systems, but could also be extended to more complex systems, and used with different metals that have multiple stable isotopes.     

Organizational career development is not dead: a case study on managing the new career during organizational change

New forms of careers have received increased attention in contemporary organizational research. A prominent focus in this research has been whether and how, in an increasingly unpredictable career environment, individuals are taking responsibility for their own career development. The implication is that career is becoming less central to organizational management practices. At the same time there is evidence that organizational changes typically described in this literature (such as delayering the organization in a quest for flexibility) have had a negative impact on career progress, resulting in resistance to change. The implication here is that career concerns are more central to organizational management practices. This in‐depth qualitative case study examines whether individuals do in fact take more responsibility for their career development during times of organizational change. We also examine whether this does indeed mean that the organization takes less responsibility for career management. Our data indicate that individuals are, in fact, taking more responsibility for their own careers. At the same time we found that the organization in our case study also became more actively involved in career development and management. However, this active approach did not resemble traditional top‐down career management and development. To us, the pattern of organizational and individual career development actions appear to constitute a kind of ‘organizational dance,’ a highly interactive mutual influence process, in which both parties are at once the agent and the target of career influence. Strengths and limitations of the study are discussed, as are directions for future research. Copyright © 2007 John Wiley & Sons, Ltd.     

Contamination of fish by 2,3,7,8-tetrachlorodibenzo-P-dioxin: A survey of fish from major watersheds in the United States

A survey of contamination of fish from major watersheds in the United States by 2,3,7,8-TCDD has been conducted by the U.S. EPA. Bottom feeding and predator fish were collected at 90 statistically selected and 305 regionally selected sites and analyzed by GC/MS. It was found that 19% of the statistically sampled sites and 31% of the regionally selected sites were contaminated at or above a minimum level of detection varying from 0.5 to 2.0 pg/g. Ten percent of all samples were contaminated at levels greater than 5.0 pg/g. It was also observed that a subset of samples collected at sites near discharge from pulp/paper manufacture (N=28) had a higher frequency of TCDD contamination above 5.0 pg/g (38%). This subset of samples also contained the sample of the greatest level of TCDD contamination (85 pg/g).