Residues of dicofol on cucumber grown under plastic covers in Jordan

Residues of dicofol were determined on cucumber leaves and fruits under plastic house (PH) and plastic tunnels (PT). Five sprays, 8 d apart, were applied at 0.15% concentration. Initial deposits on leaves were 48 and 58 ppm under PH and PT, respectively. In the last sampling date of leaves, the amounts of 191 and 135 ppm were detected under both cultures, respectively. There was a continuous increase in the initial residue after each spray. The highest amount of dicofol (401) was determined 1 d after the fifth spray under PH. The exposure to high residues may pose a risk to fieldworkers. On cucumber fruits, residues of 0.95 and 1.60 ppm were determined 1 d after the fourth spray under PH and PT, respectively. These residues decreased after 4 d to 0.40 and 1.49 ppm, respectively. Almost no detectable residues could be determined 8 d after sprays number 4 and 5 under both cultures. All dicofol residues on the fruits were below the tolerance level of 2 ppm.     

Phytoremediation: Modeling removal of TNT and its breakdown products

Contamination of soil and groundwater by trinitrotoluene (TNT) is a widespread problem confronting military bases and ammunition manufacturing facilities throughout the United States. Phytoremediation provides a promising treatment of TNT-contaminated groundwater and wastewater because many plants contain the necessary enzymes to degrade explosives such as TNT. Two phytoremediation methods are proposed in this article: controlled reactors and constructed wetlands. Controlled reactors provide greater control of operating parameters, a reduced possibility of contaminant migration, control of animals feeding on the plants, and minimization of competition from other plant species. Constructed wetlands have relatively low capital costs, and the wetland becomes a desirable ecological resource. Because cost, as opposed to reactor size, appears to be the most significant factor for military base cleanup, this project focused on the constructed wetland approach. To estimate the disappearance of TNT and its breakdown products from a constructed wetland, a first-order, nonreversible reaction, plug-flow, finite-difference model was developed. Batch scale experiments were conducted to define disappearance kinetics for individual chemical species. The results of the model suggest that reasonably sized wetlands may be used to treat a wastestream with an influent TNT concentration of 2.25 ppm at flow rates ranging from 10 to 5,000 gpm. Economic comparisons to other published costs for competing technologies are promising.     

Accounting for the quality of work life

This study describes the development and issuance of an independent report on the quality of work life in a Corporation. The theory underlying the report, criteria, definitions, measurement procedures, the properties of the measures, and report itself are presented. A survey indicating a favourable reception to the data by stockholders, financial analysts, and employees is analysed. Recommendations for increased collaboration between accountants and behavioural scientists in the measurement and assessment of the quality of work life are presented in an effort to stimulate further research in the development of standardized measures and in the preparation of independent reports on the quality of work life in organizations.     

Respiration and physiological state in marine bacteria

The relationship between oxygen consumption (R) and respiratory electron-transport-system (ETS) activity was investigated in batch cultures of 5 species of marine bacteria, Vibrio adaptatus, V. anguillarum, a partially identified Vibrio sp. SA774, Serratia marinorubra, and Pseudomonas perfectomarinus. Although cellular levels of R and ETS varied widely among the species tested, the R:ETS ratios for growing or senescent populations were relatively constant among the species; these ratios were 5.02 in growth and 0.426 in senescence, with coefficients of variation of 29 and 20%, respectively. The lower senescent-phase R:ETS ratio was due to a depression of the respiration rates following growth termination. The regression log (R per cell) = 0.832 log (ETS per cell) + 0.727 for the growing populations was similar to that determined for marine zooplankton. The slight dependency of the R:ETS ratio on organism dry weight found for zooplankton was supported by our data. Planktonic respiration rates estimated from measured ETS-depth profiles in the eastern tropical North Pacific Ocean using the senescent-phase R:ETS ratio were similar to published oxygen consumption rates in the deep sea.Contribution No. M79-61 from the University of Washington's Department of Oceanography, and No. 79032 from the Bigelow Laboratory for Ocean Sciences.     

Cytotoxicity to alveolar macrophages of airborne particles and waste incinerator fly-ash fractions

A waste incinerator fly ash was separated into different grain-size fractions by sieving and sedimentation in butanol. The element content of each fraction was determined by atomic absorption and emission spectrometry. The fly-ash fractions, an eluted fine fly-ash fraction and an eluted airborne dust were analysed microscopically for particle size and numbers, together with standard quartz DQ 12 and three element-analysed airborne dusts. Rabbit alveolar macrophages, isolated by lung lavage, were incubated for 24 h with the particulates, the two eluates and a mixed element compound solution corresponding to the element concentrations of one airborne dust. At the end of incubation, the activities of lactate dehydrogenase, N-acetyl-beta-glucosaminidase, beta-galactosidase and acid phosphatase were determined in medium and cell lysates. Cytotoxicity was expressed as ratio of extracellular to total LDH (lactate dehydrogenase) activity. Release of N-acetyl-beta-glucosaminidase and beta-galactosidase was correlated positively with LDH release, whereas the total activity of acid phosphatase decreased with increasing LDH release. Cytotoxicity of the dusts was correlated with particle numbers, and As, Sb and Pb contents. The contribution of As to particle toxicity is discussed. Eluates of dusts did not affect rabbit alveolar macrophage viability.