Dissipation of sulfamethoxazole and trimethoprim antibiotics from manure-amended soils

In this study, the dissipation of two antibiotics, sulfamethoxazole (SMX) and trimethoprim (TRM), in three soils under both aerobic and anaerobic conditions are evaluated. Under aerobic conditions, SMX dissipated rapidly through biodegradation but TRM was more persistent. Within the first 20 days in biologically active soils, >50% of the SMX was lost from the clay loam and loamy sand soils, and >80% loss was noted in the loam soil. Anaerobic dissipation of both compounds was more rapid than aerobic dissipation. The addition of manure to the soil only slightly increased the initial dissipation rate of the two compounds. Little effect was found on glucose mineralisation in soil following the addition of SMX and TRM, even as mixtures at high concentrations.     

The phenology of a Neotropical ant assemblage: evidence for continuous and overlapping reproduction

Reproductive phenologies reflect the interaction between the mating system of a taxon and the local environment. Ant colonies reproduce and disperse via the flights of winged alates. Few data exist on the reproductive phenologies of ant assemblages. Here we analyze the reproductive phenologies of 81 common ant species from 23,182 individuals collected over 3 years on Barro Colorado Island, Panama (BCI). Species ranged from highly synchronous to continuous fliers, but showed a median flight duration of at least 8 of 13 lunar months. In two statistical analyses (variance ratio test and Spearman rank correlations), 84% (16 of 19) of ant genera had species trending toward positively associated phenologies, more than expected by chance (P<0.00036 by a binomial test). Thus, there was little evidence for the hypothesis that competition for limiting resources staggers congeneric flights and ultimately promotes reproductive isolation. On the contrary, the timing of reproduction, and its synchrony, tended to be conserved within genera and subfamilies. These results closely match phenological studies of plant assemblages. The continuous reproduction and small colony size of many species in this study suggest that the female calling syndrome, a poorly documented mating system in ants, may be common on BCI.     

Interpreting seawater temperature range using oxygen isotopes and zooid size variation in Pentapora foliacea (Bryozoa)

This is the first investigation of how two independent proxies for seawater temperature inference (zooid size variation and oxygen isotope ratios of skeletal carbonate) relate to the actual measured ranges of temperature experienced by cheilostome bryozoan colonies. Nine specimens of the bimineralic marine cheilostome bryozoan Pentapora foliacea (Ellis and Solander, 1786) were analysed, collected from ~18-m depth at two localities in Wales, UK—four from Skomer Island (51°42′510″N, 5°13′42.60″W) and five from Porth Ysgaden, Lleyn Peninsula (52°54′6.75″N, 4°38′47.34″W). The annual range of temperature implied by zooid size variability provides a good approximation of the actual range of temperature recorded by a datalogger. However, annual ranges of temperature reconstructed from skeletal oxygen isotope ratios were narrower, typically not showing the lowest temperatures experienced by the colonies. This can be explained by progressive thickening of zooid skeletal walls during the life of the colony that homogenises the temperature signal by time-averaging over the lifetime of the colonies. Our study provides evidence that a combined morphological isotope approach has great potential in the reconstruction of annual ranges in seawater temperatures from historical and fossil bryozoans, particularly for species that lack ontogenetic skeletal wall thickening and bimineralic skeletal composition. As cheilostome bryozoans have been common in benthic communities since the Late Cretaceous, they represent a valuable and underutilised resource for the interpretation of environmental regimes.     

Biological Effects of Microwave Radiation

The possibility of exposure of large segments of the population to complex, multifrequency microwave radiation in the environment is now a reality. It is necessary, therefore, to determine the safe level of exposure for the general population so as to prevent any occurrence of harmful effects without unduly restricting the beneficial uses of microwaves.

The biological effects generated by exposure to microwave radiation are usually designated as thermal or non-thermal (specific) in nature. Thermal effects are those interactions which are caused by the heating of the biological specimen and can be duplicated using conventional heating techniques. Nonthermal or specific effects are due to the direct interaction of the electromagnetic field of the incoming microwave radiation and the biological specimen.

The two organs of the body which are particularly sensitive to elevation in temperature are the testicles and the eyes. These organs, therefore, are the most sensitive to exposure to microwave radiation. Research on dogs, rabbits, and rats has shown that at 10 mW/cm, (power density in milliwatts per square centimeter) pathological damage to the testes include a degeneration of the epithelium lining of the seminiferous tubules, and a sharp reduction in the number of maturing spermatocytes. The reduction in testicular function due to the heating effect at 10 mW/cm² appears to be temporary and reversible.

Cataracts have been produced in the eyes of experimental animals. Several investigators have used the eyes of rabbits to establish threshold for cataract formation. For CW radiation, the threshold in rabbits for long-term ex-posure, was measured to be approximately 100 mW/cm². Several cases of eye cataracts in man due to microwave exposure have been reported at power densities of the same order of magnitude. More research is needed before threshold values for cataract formation in humans can be specified with certainty.

Nonthermal or specific effects are more difficult to detect than the thermal effects. This difficulty is due to the nature of the response of the biological specimen and the lack of explanation of the mechanism causing the effect. The most often reported effects of low level microwave radiation are neurological in nature. Effects on animals include changes in EEG patterns, changes in the conditioned reflexes, alterations in sensitivity to light, sound, and olfactory stimuli, alterations in the biocurrents of the cerebral cortex, and changes in behavior. Many subjective symptoms in humans working around microwave equipment have been reported by investigators from the U.S.S.R. and Eastern European researchers.

Genetic effects have been reported by some investigators. Exposure of chick embryos to microwave radiation induced abnormal development while conventional heating to the same temperature did not cause abnormalities. In general, the abnormalities appeared to be caused by the inhibition of growth and cell differentiation. Abnormal development of the “mealworm” beetle pupae has also been detected when exposed to microwave radiation. This study also indicates that the abnormalities were not due to thermal effects but due to the inhibition of cell differentiation caused by a direct interaction with the electromagnetic field.     

Phytoremediation to remove nutrients and improve eutrophic stormwaters using water lettuce (<Emphasis Type="Italic">Pistia stratiotes</Emphasis> L.)

Background, aim, and scope  

Water quality impairment by nutrient enrichment from agricultural activities has been a concern worldwide. Phytoremediation technology using aquatic plants in constructed wetlands and stormwater detention ponds is increasingly applied to remediate eutrophic waters. The objectives of this study were to evaluate the effectiveness and potential of water lettuce (Pistia stratiotes L.) in removing nutrients including nitrogen (N) and phosphorus (P) from stormwater in the constructed water detention systems before it is discharged into the St. Lucie Estuary, an important surface water system in Florida, using phytoremediation technologies.     

Job level risk assessment using task level ACGIH hand activity level TLV scores: a pilot study.

Existing upper extremity musculoskeletal disorder analytical tools are primarily intended for single or mono-task jobs. However, many jobs contain more than 1 task and some include job rotation. This case/control study investigates methods of modifying an existing tool, the American Conference of Governmental Industrial Hygienists (ACGIH) Hand Activity Level (HAL) Threshold Limit Value (TLV), to assess the upper extremity risk of multi-task jobs. Various methods of combining the task differences and ratios into a job level assessment were explored. Two methods returned significant odds ratios, (p < .05) of 18.0 (95% CI 1.8-172) and 12.0 (95% CI 1.2-120). These results indicate that a modified ACGIH HAL TLV may provide insight into the work-related risk of multi-task jobs. Further research is needed to optimize this process.     

Effects of parasites on foraging and defense behavior of a termitophagous ant,Pheidole titanis Wheeler (Hymenoptera: Formicidae)

Summary Pheidole titanis Wheeler, an ant that occurs in desert and deciduous thorn forest in the southwestern United States and western Mexico, is a predator on termites. In the dry season well-coordinated raids against termite foraging parties occur early in the morning or late in the afternoon, whereas in the wet season most raids occur at night. This seasonal shift in the timing of raids is due to the increased activity of a fly (Diptera: Phoridae) that is a specialist parasitoid on P. titanis workers and soldiers. When parasitic flies discover P. titanis nest entrances or raiding columns, workers stop foraging and defend themselves against oviposition attacks. Flies are only active during the day and never interfere with foraging at night. However, P. titanis does not increase the frequency of raids at night and, as a result, colonies collect less food in the wet season compared to the dry season. Presence of parasitic flies also interferes with normal defense behavior of P. titanis against conspecific and heterospecific enemy ants. Dissections of P. titanis workers and soldiers suggest that the parasitism rate by flies is less than 2% and observations indicate that parasitic flies are much rarer than their host workers and soldiers. Nonetheless, these parasites exert a strong ecological impact on their host.