Changes in aliphatic hydrocarbon tracer composition during the digestive process of the marine worm Nereis virens. Preliminary results

In the laboratory, marine worms were fed with a mixture of algae and several aliphatic hydrocarbons for 15 days. By comparing hydrocarbons in food and in faeces, it appeared that the worm's digestive process led to changes in the distribution of the n-alkanes mixture. These changes were different from those only due to physical processes in the experimental conditions, indicating that marine worm feeding could substantially affect the fate of hydrocarbons in the sedimentary marine ecosystem

The in vitro influence of the burrowing polychaete Nereis diversicolor on the fate of petroleum hydrocarbons in marine sediments

The in vitro fate of the saturated hydrocarbon fraction (SF) of Arabian Light crude oil has been studied in PVC cores filled with a coastal marine sediment defaunated by sieving. Experiments were conducted in absence or presence of polychaetes Nereis diversicolor. The luminophore tracer technique was used to quantify the mixing of sediment by worms. Presence of crude oil reduced the building of burrows by polychaetes. This work demonstrates the ability of infaunal organisms to stimulate both downard and outward transfers of hydrocarbons from sediment reservoirs. In non-bioturbated sediment hydrocarbons were confined to the sediment surface. Introduction of polychaetes in sediment (1) induced the burying of SF in sediment (2.5 % and 13.5 % of the initial surface input after 15 and 45 days, respectively); (2) enhanced the exportation of SF in the overlying water (plus 59 % and 23.5 % compared to defaunated control sediment after 15 and 45 days, respectively). Buried hydrocarbons were submitted to biodegradation, from 2 cm to 10 cm depth in polychaete burrows, after 45 days

Gender differences in work and family commitments and their effect on work-family role conflict among administrators in higher education

This study intended to determine 1) if, among administrators in higher education, commitment to the work role, commitment to the family role, and work-family role conflict varied by gender and other demographic variables, and 2) what combination of variables best explained level of work-family role conflict in this population. A random sample, stratified by type of institution, was selected from the 4,679 department chairs in 196 public colleges and universities in the Southern Regional Education Board (SREB) member states. Questionnaires measured work commitment (Organizational Commitment, Career Commitment, Job Involvement), Family Commitment, work-family role conflict, and demographic variables. One-way analysis of variance and multiple regression procedures were used for data analysis. Several findings were significant. Family Commitment was greatest for males, for those who had more than one child, and those whose spouse did not work outside the home. The oldest department chairs and those who had the highest tenure in their careers, had significantly higher work commitment than younger administrators. Work-family role conflict was greatest for the youngest respondents who had the fewest years of tenure in their careers and organizations and had young children. A combination of age, Organizational Commitment, and Job Involvement were helpful in explaining Professional vs Spouse conflict. These variables, plus the number of adults in the household, were helpful in explaining Professional vs Parent conflict. Administrators in this sample expressed commitment to their work and their families and experienced conflict between these roles. However, conflict was most severe among young administrators, just beginning their careers. Since work commitment explained only a relatively small portion of conflict, other factors such as internalization of expectations from work and family role partners appear to contribute to conflict. If institutions are to attract and hold the commitment of young administrators, research is needed to examine institutional changes and personal coping strategies that allow persons to minimize work-family role conflict

Estimating soil/sediment partition coefficients for organic compounds by high performance reverse phase liquid chromatography

High performance reverse phase liquid chromatography (HPRPLC) retention parameters were correlated to organic-carbon-normalized partition coefficient (Koc) values for sorption of various uncharged organic substances onto sediments and soils in an attempt to devise a model for predicting sorption behavior. The results reveal a relationship between the logarithm of HPRPLC retention time and log Koc that appears to provide a reasonable means for estimating partitioning properties from HPRPLC data. The technique was compared to methods which utilize octanol/water partition coefficients (Kow) and aqueous solubilities as surrogate predictors of sorption behavior and was found to yield superior correlations in all cases tested.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27257/1/0000266.pd

The variable influence of dispersant on degradation of oil hydrocarbons in subarctic deep-sea sediments at low temperatures (0-5 °C)

The microbial degradation of petroleum hydrocarbons at low temperatures was investigated in subarctic deep-sea sediments in th e Faroe Shetland Channel (FSC). The effect of the marine oil dispersant, Superdispersant 25 on hydrocarbon degradation was also examined. Sediments collected at 500 and 1000 m depth were spiked with a model oil containing 20 hydrocarbons and incubated at ambient temperature (5 and 0 °C, respectively) with and without marine dispersant. Treatment of sediments with hydrocarbons resulted in the enrichment of Gammaproteobacteria, and specifically the genera Pseudoalteromonas, Pseudomonas, Halomonas, and Cobetia. Hydrocarbon degradation was faster at 5 °C (500 m) with 65-89% of each component degraded after 50 days compared to 0-47% degradation at 0 °C (1000 m), where the aromatic hydrocarbons fluoranthene, anthracene, and Dibenzothiophene showed no degradation. Dispersant significantly increased the rate of degradation at 1000 m, but had no effect at 500 m. There was no statistically significant effect of Superdispersant 25 on the bacterial community structure at either station. These results show that the indigenous bacterial community in the FSC has the capacity to mitigate some of the effects of a potential oil spill, however, the effect of dispersant is ambiguous and further research is needed to understand the implications of its use

Scaling Behavior of Human Locomotor Activity Amplitude: Association with Bipolar Disorder

Scale invariance is a feature of complex biological systems, and abnormality of multi-scale behaviour may serve as an indicator of pathology. The hypothalamic suprachiasmatic nucleus (SCN) is a major node in central neural networks responsible for regulating multi-scale behaviour in measures of human locomotor activity. SCN also is implicated in the pathophysiology of bipolar disorder (BD) or manic-depressive illness, a severe, episodic disorder of mood, cognition and behaviour. Here, we investigated scaling behaviour in actigraphically recorded human motility data for potential indicators of BD, particularly its manic phase. A proposed index of scaling behaviour (Vulnerability Index [VI]) derived from such data distinguished between: [i] healthy subjects at high versus low risk of mood disorders; [ii] currently clinically stable BD patients versus matched controls; and [iii] among clinical states in BD patients

Sorption of hydrophobic compounds by sediments, soils and suspended solids--I. Theory and background

This is the first of a two-part series describing the adsorption of hydrophobic pollutants by sediments, soils, and suspended solids. Many pollutants, including a large number of hazardous compounds, are hydrophobic and their environmental behavior varies markedly between sorbed and dissolved states. It is thus necessary to account for sorption reactions in analysis and prediction of the environmental transport and fate of such pollutants. In this first part the energetics of sorption reactions are discussed and models for description of equilibrium relationships are summarized. Factors which affect the sorption of pollutants in natural environmental systems are then considered and evaluated.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25452/1/0000902.pd

Effect of Surfactants at Low Concentrations on the Sorption of Atrazine by Natural Sediment

A series of experiments were carried out to determine the effect of surfactants at low concentrations on the sorption of atrazine by natural sediments. With surfactant concentrations ranging from 0 to 20 mg/ L, anionic and cationic surfactants appreciably reduce the adsorption of atrazine, while nonionic surfactant decreases the adsorption of atrazine at concentrations equal to or less than 1 mg/L and increases adsorption at higher concentrations. Desorption of atrazine in the presence of different sodium dodecylbenzene sulfonate (SDBS) concentrations shows that a portion of the bound pesticide resists desorption in the SDBS free system. However, the addition of SDBS accelerates the desorption of atrazine. Furthermore, the nature of sediment and the contacting sequence of SDBS, at 10 mg/L, with the sediment, also influence the adsorption of atrazine. The conclusions in this study could be explained partially by the effect of the type and concentration of surfactants and the characteristics of sediments