Integrated Measures of Anthropogenic Stress in the U.S. Great Lakes Basin

Integrated, quantitative expressions of anthropogenic stress over large geographic regions can be valuable tools in environmental research and management. Despite the fundamental appeal of a regional approach, development of regional stress measures remains one of the most important current challenges in environmental science. Using publicly available, pre-existing spatial datasets, we developed a geographic information system database of 86 variables related to five classes of anthropogenic stress in the U.S. Great Lakes basin: agriculture, atmospheric deposition, human population, land cover, and point source pollution. The original variables were quantified by a variety of data types over a broad range of spatial and classification resolutions. We summarized the original data for 762 watershed-based units that comprise the U.S. portion of the basin and then used principal components analysis to develop overall stress measures within each stress category. We developed a cumulative stress index by combining the first principal component from each of the five stress categories. Maps of the stress measures illustrate strong spatial patterns across the basin, with the greatest amount of stress occurring on the western shore of Lake Michigan, southwest Lake Erie, and southeastern Lake Ontario. We found strong relationships between the stress measures and characteristics of bird communities, fish communities, and water chemistry measurements from the coastal region. The stress measures are taken to represent the major threats to coastal ecosystems in the U.S. Great Lakes. Such regional-scale efforts are critical for understanding relationships between human disturbance and ecosystem response, and can be used to guide environmental decision-making at both regional and local scales.     

Evaluation of California's safety belt law change from secondary to primary enforcement

Some states allow an officer to stop a vehicle for an observed belt law violation alone (primary). Most require that the initial stop be made for some other violation before a belt law citation can be issued (secondary). On January 1, 1993, California became the first state to implement an uninterrupted change from secondary to primary belt law enforcement. In six study communities, the percentage of drivers observed wearing seat belts increased from 58% prior to the law change to 76% soon thereafter. Drivers surveyed at DMV offices indicated that they had knowledge of the new law and were more likely to wear their belts now than in the past.     

STORMWATER DETENTION BASINS AND RESIDENTIAL LOCATIONAL DECISIONS1

ABSTRACT: Residents of seven subdivisions with wet and dry stormwater basins were questioned about the role the basin played in their decision to purchase their home. They were asked to estimate the impact of such basins on the image of residential developments and on lot values. Respondents believed that wet basins contributed positively to subdivision image and that lots in developments with wet basins were more valuable than comparable lots in dry basin subdivisions. Lots adjacent to wet basins were perceived as the most valuable, while those adjacent to dry basins were considered the least valuable.     

Phthalate and alkyl phenol concentrations in soil following applications of inorganic fertiliser or sewage sludge to pasture and potential rates of ingestion by grazing ruminants

Soil concentrations of dioctyl phthalate (DOP) and the alkyl phenols, octyl phenol (OP) and nonyl phenol (NP), after repeated surface applications of sewage sludge to pastures, were investigated. Liquid sludge was applied at a rate of 2.25 tonnes dry matter (DM) per hectare to each of three treated (T) plots on three occasions during the summer and two occasions in the early spring over a period of 2.5 years. Control (C) plots were treated with inorganic fertiliser containing amounts of nitrogen equivalent to those applied to the treated plots. At between 69 and 81 days after the application of sludge, 15 separate soil samples were collected from one half of each of the plots (Experiment 1). Concentrations (microg g(-1)) of DOP were higher (P < 0.001) than those of NP, while those of OP were generally below detectable levels. Mean soil concentrations of DOP were not significantly different in T and C plots [0.233 vs. 0.155 microg g(-1); standard error of the difference (SED) = 0.046; not significant (NS)], partly because there was already a relatively large amount of DOP present. NP concentrations were, however, significantly higher in T than in C plots (0.021 vs. 0.013 microg g(-1) SED = 0.002; P < 0.05). There was no consistent change over time in the mean soil concentrations of these compounds when sampled at intervals of 3-6 months. Concentrations in soil samples collected at monthly intervals following sludge application indicated that the variation in concentrations of these endocrine-disrupting compounds (EDC) was unrelated to time since sludge application. Rates of soil ingestion, expressed as the percentage of DM intake represented by soil, were higher during the winter than the summer (5.40 vs. 1.17; SED = 0.360; P < 0.001) and estimated daily intakes of DOP and NP were up to 150 microg and 8 microg, respectively. It is concluded that the application of sewage sludge to pasture does not increase soil concentrations of phthalate (as DOP) or alkyl phenols. Thus, the risk of increased exposure to these EDC as a result of sludge application is small. However, the small effect of sludge application on soil concentrations may be largely a reflection of the relatively high concentrations of DOP already present in the soil, which may be biologically significant.     

A closer look at the effects of subordinate–supervisor age differences

Relational demography research has emphasized a similarity–attraction paradigm in explaining employees' reactions to demographic differences from other organizational members. This study examined similarity–attraction (nondirectional age differences) and status incongruence (directional age differences) predictions of age difference effects. The nondirectional and directional differences between the age of a subordinate and the ages of his or her immediate and higher‐level supervisors were used to predict employee absenteeism, citizenship, and work change behaviors. Results revealed that there were more significant and marginally significant directional age difference effects than nondirectional age difference effects on work outcomes. The implications of these results for organizations are discussed. Copyright © 1999 John Wiley & Sons, Ltd.     

Organizational politics and organizational support as predictors of work attitudes,job performance,and organizational citizenship behavior

This study investigated the relationship of organizational politics and organizational support to various work attitudes and behaviors among a field sample of 128 participants. Consistent with our hypothesis, politics and support were related to job satisfaction, commitment, turnover intentions, and supervisor ratings of organizational citizenship behaviors. However, only support was related to job performance. We also examined whether or not organizational politics and organizational support comprise two distinct constructs or one global factor. The evidence here was ambiguous. Fit indices obtained from confirmatory factor analysis suggested that it is more parsimonious to treat politics and support as opposite ends of the same construct, though the two‐factor model did show a slightly better fit. On the other hand, subsequent multiple regression analyses showed that support tended to account for additional criterion variance beyond the effect of politics, implying that there may be some practical utility to retaining politics and support as distinct constructs. Copyright © 1999 John Wiley & Sons, Ltd.