Concentrations of p,p'-DDE in plasma of nestling Wood Storks from Georgia

We determined the concentrations of organochlorine pesticides and total PCBs in plasma of nestling Wood Storks (Mycteria americana) from two colonies in Georgia in 2000. Of 20 compounds analyzed for, only p,p'-DDE was quantified in reportable concentrations, ranging from <2.0-174.0 ng/g wet weight (ww). Concentrations of p,p'-DDE were significantly greater (P<0.0001) in plasma of nestlings from an inland colony, Chew Mill (x 16.9 ng/g,ww) than a coastal colony, Harris Neck (x 1.2 ng/g,ww). Concentrations from nestlings from Chew Mill were significantly different among sampling weeks (P=0.01), with week 8 being significantly greater than weeks 1, 2, and 5. While the Chew Mill colony had much greater concentrations of p,p'-DDE in plasma of nestlings than the Harris Neck colony, reproduction was greater there (1.8+/-1.0 SD fledged young per nesting attempt) than Harris Neck (1.4+/-1.0 SD fledged young per nesting attempt). While concentrations of p,p'-DDE determined in plasma of nestling Wood Storks are an indirect measure of adult exposure to environmental toxicants, concentrations reported would not be considered detrimental to reproduction in these colonies.     

An exploratory study of self-regulating activities and their effects on job performance

The present study attempted to assess the extent to which job incumbents engage in performance relevant self-regulatory activities. Specifically, the degrees to which 62 insurance salespersons; (1) set performance goals, (2) monitored performance levels, and (3) exercised contingent self-reward or punishment with respect to goal achievement or goal failure were measured; and, the consequences that such activities had on performance were examined. The results of this study indicate that, in general, subjects set goals, but typically of a distal/result-orientated, as opposed to a proximal/behaviourally orientated-nature. Goal setting per se had no effects on sales performance, although an objective measure of goal difficulty was related to this criterion. With respect to self-monitoring, it was discovered that the greatest amount of performance feedback came from oneself and one's supervisor, as opposed to one's co-workers. In terms of performance, there was an interaction of feedback source and feedback preference such that the ability to generate internal feedback was related to performance only for individuals who had a preference for such internal feedback. There appeared to be no substantial amount of contingent self-reward occurring within this organization, although contingent self-punishment (in the form of self-criticism) was in evidence; and, such self-admonishment seemed to have detrimental effects on performance. While the three classes of variables independently explained 26 per cent of the variance in performance, the interactive effects suggested by theories of self-regulation (Bandura, 1977; Kanfer, 1971) were not in evidence.     

Experimental warming, not grazing, decreases rangeland quality on the Tibetan Plateau.

We investigated experimental warming and simulated grazing (clipping) effects on rangeland quality, as indicated by vegetation production and nutritive quality, in winter-grazed meadows and summer-grazed shrublands on the Tibetan Plateau, a rangeland system experiencing climatic and pastoral land use changes. Warming decreased total aboveground net primary productivity (ANPP) by 40 g x m(-2) x yr(-1) at the meadow habitats and decreased palatable ANPP (total ANPP minus non-palatable forb ANPP) by 10 g x m(-2) x yr(-1) at both habitats. The decreased production of the medicinal forb Gentiana straminea and the increased production of the non-palatable forb Stellera chamaejasme with warming also reduced rangeland quality. At the shrubland habitats, warming resulted in less digestible shrubs, whose foliage contains 25% digestible dry matter (DDM), replacing more digestible graminoids, whose foliage contains 60% DDM. This shift from graminoids to shrubs not only results in lower-quality forage, but could also have important consequences for future domestic herd composition. Although warming extended the growing season in non-clipped plots, the reduced rangeland quality due to decreased vegetative production and nutritive quality will likely overwhelm the improved rangeland quality associated with an extended growing season. Grazing maintained or improved rangeland quality by increasing total ANPP by 20-40 g x m(-2) x yr(-1) with no effect on palatable ANPP. Grazing effects on forage nutritive quality, as measured by foliar nitrogen and carbon content and by shifts in plant group ANPP, resulted in improved forage quality. Grazing extended the growing season at both habitats, and it advanced the growing season at the meadows. Synergistic interactions between warming and grazing were present, such that grazing mediated the warming-induced declines in vegetation production and nutritive quality. Moreover, combined treatment effects were nonadditive, suggesting that we cannot predict the combined effect of global changes and human activities from single-factor studies. Our findings suggest that the rangelands on the Tibetan Plateau, and the pastoralists who depend on them, may be vulnerable to future climate changes. Grazing can mitigate the negative warming effects on rangeland quality. For example, grazing management may be an important tool to keep warming-induced shrub expansion in check. Moreover, flexible and opportunistic grazing management will be required in a warmer future.     

Variability of Water Column Transparency, Volume Flow and Suspended Solids Near San Diego Sewage Outfall (California): 15 Years of Data

The spatial and temporal variability of transparency measured for 15 years at 7 stations near the San Diego sewage outfall has been investigated and compared to the temporal variability of sewage suspended solid discharge and flow rate. the purpose of the time-series analyses was to distinguish natural from human (sewage discharge) causes of temporal changes in transparency. the results show that: 1) variations in transparency are highly correlated over the entire area, but there is a gradient in means and variability in the direction perpendicular to the coast; 2) there are no long term trends for increase or decrease in the water clarity at any of the stations; 3) most of the variance of transparency is contained in the seasonal frequency band; 4) over the same time period sewage discharge has significantly increased and suspended solids decreased; 5) most of the variance of these human-caused properties is in the interannual frequency band; (6) there is no correlation at any time-lag between water clarity and suspended solid discharge or flow. These results lead to the conclusion that these anthropogenic properties are not affecting transparency, while natural factors such as seasonality and distance from coast do.     

Investigation of contact vacuuming for remediation of fungally contaminated duct materials

Environmental fungi become a potential Indoor Air Quality (IAQ) problem when adequate moisture and nutrients are present in building materials. Because of their potential to rapidly spread contamination throughout a building, ventilation system materials are of particular significance as potential microbial contamination sources. Current recommendations are to discard fibrous glass insulation that appears to be wet or moldy. Unfortunately, this advice is not always followed. Instead, cleaning is sometimes being used in buildings to remediate fibrous glass duct liner that is already contaminated with microbial growth. The objectives of this research program were to: 1) determine, under dynamic test conditions, whether fungal spore levels on heating, ventilating, and air-conditioning (HVAC) duct material surfaces could be substantially reduced by thorough vacuum cleaning, 2) evaluate whether subsequent fungal growth could be limited or contained by mechanical cleaning, and 3) provide data concerning the advisability of cleaning duct materials. The constant high relative humidity (RH) environment to which the test materials were exposed during this study was selected as a favorable growth environment that is frequently found in Southeastern United States HVAC systems. The results showed that, following cleaning, the levels of the two test fungi, A. versicolor and P. chrysogenum, recovered to preclean levels within 6 weeks. Therefore, mechanical cleaning by contact vacuuming alone was able to only temporarily reduce the surface fungal load. The current guidelines to discard contaminated materials should be followed.     

Soil Respiration and Carbon Storage of an Acrisol Under Forest and different Cultivations in rio de Janeiro State, Brazil

Soil respiration rates of a clay-loam textured Acrisol under different uses (Atlantic forest, manioc, horticulture and pasture) from Rio de Janeiro State were measured. The relationship between carbon dioxide (CO₂) emissions and soil physico-chemical properties were investigated. Rates of CO₂ emission of two sites (Atlantic forest and horticulture) were also evaluated in different seasons in 1997 and 1998. In the forest site, monthly means of measured respiration rates showed good correlation with soil temperature in the range 19.6–24.1°C (r² = 0.89). In the horticulture site, no change was observed with soil moisture alone, in the range 3.0–13.2 wt%. In the horticulture soil, even when the surface soil was very dry, respiration rates increased in the hot, wetter summer but remained higher than the mean flux from forest soil. The CO₂ emission flux of the Acrisol under different use showed good correlation with soil temperature (r² = 0.72) and moisture (r² = 0.61).