ALBERT

Notes: Abstract A 4-year study (1972–1976) determined long-term trends of organochlorine residues (DDT, DDE, DDD, PCB's, mirex) and trawl-susceptible organisms in a shallow, river-dominated estuary in North Florida (Apalachicola Bay, USA). Moderate levels of such compounds were found in various species prior to the restricted use of DDT in 1972. A subsequent precipitous decline in organochlorine besidues was attributed to decreased upland usage, major flushing of the river basin in early 1973, and various factors associated with estuarine function. No mirex was found in sediments or aquatic organisms. Apparently, the half-life of organochlorines is relatively short in this bay system. Various statistical methods were used to test the relationships of different physico-chemical and biological parameters. During the 4-year study period, seasonal river flow fluctuations dominated water color, turbidity, salinity, nutrients (NO3), chlorophyll a, and the temporal succession of fishes in the bay. Certain long-term trends of fish associations were noted; relative dominance of key fish species declined and stabilized while bay-wide species richness and diversity increased with time. Qualitative changes in species representation determined the long-term pattern of community variability. This was consonant with a distinctive fish fauna during the first year of sampling. The bay anchovy Anchoa mitchilli was dominant during 9 of the first 12 monts of the project; this influenced the time-related changes in community indices. Temporally clustered fish associations reflected the importance of river flow in the estuarine environment. Direct correlation of fish distribution with the rapid disappearance of organochlorine compounds was complicated by aperiodic natural phenomena such as storms and river fluctuations. Population and community trends appeared consistent with other studies showing similar patterns of dominance of stress-resistant fish populations and related changes in community parameters. In this case, the relatively predictable annual succession of fish associations allowed an appraisal of key forcing functions. Due to the high level of seasonal and annual biological variability in this estuary, there were some problems in the application of linear statistical models to the data base. Although the long-term trend of relative species representation is useful as an index of stress, new techniques are needed to analyze extensive field data so that functions such as trophic interactions are included in the estimation of causal relationships. There are indications that such effects could be related to the impact of organochlorine compounds on estuarine systems.

Notes: Summary Radiochemical studies of Populus tremuloides xylem tissue administered l-[1-3H]arabinose, d-[1-3H]glucose, and d-[6-3H]glucose demonstrate that l-[1-3H]arabinose is an excellent precursor for pentosan in this tissue. Transverse sections of first-year xylem (from cambial zone to pith) were examined by light and electron microscope autoradiography. Relatively large amounts of labeled pentosan are found in parenchyma cell walls, including the “protective layer” of ray parenchyma. Computeraided analyses of grain distributions in electron micrographs of cell walls of individual fibers localized the labeled wall components after different periods of incubation by comparison to model behavior. These analyses indicate that pentosan is added to the secondary cell wall of developing fibers by an appositional mechanism.

Notes: Abstract Five different treatments of ethion on Valencia orange trees were compared for decay rates and for ethion monoxon and ethion dioxon production under different environmental conditions. The oxon metabolite levels observed were low and always below the residue level of ethion itself. There were no significant differences in the decay rates of ethion between treatments. A model of ethion decay utilizing environmental variables as a time base is presented. This model explains 94% of the variation observed in ethion decay during very wet and very dry periods in Florida. The application of these results and general experimental approach to worker safety reentry standards is discussed.

Notes: Summary Diets containing 264.6 ppm o,p′- or p,p′-DDT were fed to 6-week-old male and female turkeys for 7 and 15 weeks. Such chronic feeding of DDT did not cause alterations of: Blood pressure; gross structure of body tissues; histology of heart, aorta, liver, testes, oviduct, ovary, thyroid, or kidney; plasma cholesterol or calcium levels; albumin-globulin ratio; or plasma lipoprotein patterns. The residue of DDT in body fat was determined. Trace amounts were found in birds fed the control diet. Minute quantities of o,p′-DDT and large amounts of p,p′-DDT were found in fat of turkeys fed p,p′-DDT, and the converse was true of turkeys fed o,p′-DDT.

Notes: Summary Microscopic and electron microscopic examination of the resin canal complex isolated from slash pine chlorite holocellulose showed it to be composed of thin-walled, unlignified tissue apparently without secondary thickening. The mature structure consisted of a central canal surrounded by three cellular layers. Epithelium forms the inner layer while the middle and outer layers consist of short (intermediate) and elongated (outer) parenchyma cells, respectively. In contrast to previous concepts, the middle lamella of these tissues is a complex structure which contains intercellular membranes and cellulosic and noncellulosic (probably galacturonan) intercell wall fibrils. Intercellular membranes encapsulate two or more cells and consist of one or more intact ancestral walls The number and total thickness of ancestral walls in the mature middle lamella vary with the number of cell divisions and the location of the cell plates within a fusiform cambium daughter cell. The development of the canal complex and of the ray tissue associated with it can be traced by studying the cell wall ultrastructure.

Notes: Abstract Eddy fluxes of momentum, sensible and latent heat, and turbulence spectra measured over the Thetford Forest during 10 days in the Spring of 1973 are described. The measured total heat flux (H + λE) for 122 20-min periods agreed closely on average with independent estimates from an energy balance method. There was evidence that the energy balance data gave small systematic overestimates of available energy during the hours before noon, compensated by slight underestimates for the remainder of the day. A comparison of measured wind speeds and friction velocities in neutral stability confirmed the validity of the aerodynamic method for estimating momentum fluxes at heights of a few roughness lengths above the canopy. In stable conditions the log-linear wind profileU = (u */k)(ln ((z -d)/z o) + α (z -d -z o)/L) with α = 3.4 ± 0.4 provided a good fit to the data. Spectra in unstable conditions were generally more sharply peaked than those measured by other workers over smoother terrain: differences were less marked in the case of vertical velocity in stable conditions. Temperature spectra in these stable conditions showed high energy at relatively low wavenumbers, andwT cospectra showed a cospectral gap; both of these results were associated with an intermittent sawtooth structure in the temperature fluctuations.

Notes: Abstract Zinc bicrystals containing high-angle tilt boundaries, and others containing twist boundaries were subjected to constant shear stresses parallel to the boundary at temperatures in the range 20 to 300° C. At stresses both above and below that necessary to cause macroscopic slip in the constituent crystals, the grain-boundary sliding rate decreased with time. This “slide-hardening” at the grain-boundary was identified with the formation of asperities in the grain-boundary which were generated first near the intersection of boundary and free surface. Removal of the layer containing these asperities restored the boundary behaviour to that of a virgin bicrystal in certain cases. This leads to the conclusion that when slide-hardening occurs, the rate-limiting process for grain-boundary sliding is that associated with the deformation of the crystal regions which have been introduced into the original boundary plane by grain-boundary migration.