Temperature and wetland plant species effects on wastewater treatment and root zone oxidation

Constructed wetlands are widely used for wastewater treatment, but there is little information on processes affecting their performance in cold climates, effects of plants on seasonal performance, or plant selection for cold regions. We evaluated the effects of three plant species on seasonal removal of dissolved organic matter (OM) (measured by chemical oxygen demand and dissolved organic carbon) and root zone oxidation status (measured by redox potential [Eh] and sulfate [SO4(2-)]) in subsurface-flow wetland (SSW) microcosms. A series of 20-d incubations of simulated wastewater was conducted during a 28-mo greenhouse study at temperatures from 4 to 24 degrees C. Presence and species of plants strongly affected seasonal differences in OM removal and root zone oxidation. All plants enhanced OM removal compared with unplanted controls, but plant effects and differences among species were much greater at 4 degrees C, during dormancy, than at 24 degrees C, during the growing season. Low temperatures were associated with decreased OM removal in unplanted controls and broadleaf cattail (Typha latifolia L.) microcosms and with increased removal in beaked sedge (Carex rostrata Stokes) and hardstem bulrush [Schoenoplectus acutus (Muhl. ex Bigelow) A. & D. L?ve var. acutus] microcosms. Differences in OM removal corresponded to species' apparent abilities to increase root zone oxygen supply. Sedge and bulrush significantly raised Eh values and SO4(2-) concentrations, particularly at 4 degrees C. These results add to evidence that SSWs can be effective in cold climates and suggest that plant species selection may be especially important to optimizing SSW performance in cold climates.     

Temperature, Salinity, and Fluorescence in Southern North Sea: High-Resolution Data Sampled from a Ferry

/ In 1991 and 1992, temperature, salinity, and fluorescence were measured by automatic continuous registration using instrumentation on a ferry crossing the southern North Sea daily along a transect between Zeebrugge, Belgium, and Hull, United Kingdom. The temperature ranged between 4 and 21 degrees C off the Belgian coast and between 6 and 17 degrees C in the middle of the transect. Salinity varied between 34 and 35.5 PSU in the offshore part of the transect, but showed much larger variation along the Belgian and UK estuarine coasts. Fluorescence, which was used as a measure of phytoplankton biomass, was highest at the continental coast and lowest near the English coast. Spring blooms of phytoplankton were found along the continental coast and in the channel-influenced water; in 1991 the blooms were denser than in 1992. Some summer blooms were also recorded. Water masses could be distinguished on the basis of salinity and fluorescence patterns. The general patterns in the data are compared with the literature and discussed in relation to river discharge, light penetration, and wind speed and direction. Finally, the value of automatic and frequent measurements of fluorescence for monitoring phytoplankton is compared with less frequent observations at selected stations. It is concluded that accurate information about phytoplankton biomass can only be established from the high-frequency data. KEY WORDS: Monitoring; Sampling; North Sea; Ferry; Fluorescence; Salinity; Temperature     

An interaction of extra- and intracellular osmoregulatory mechanisms in the bivalve mollusc Rangia cuneata

We have studied the interaction of extra- and intracellular osmoregulatory mechanisms which the estuarine bivalve Rangia cuneata utilize to tolerate salinities ranging from freshwater to 25 ppt. The normally occurring intracellular free amino acid (FAA) accumulation in hyperosmotically stressed R. cuneata isolated ventricles was significantly reduced in the presence of divalent cation concentrations lower than that normally found in the blood. The effect of the divalent cations was not on the intracellular biosynthetic pathways responsible for FAA synthesis but rather on the myocardial membrane permeability to FAA. These data indicate that the effectiveness of the intracellular FAA mediated volume regulatory response in R. cuneata is dependent on both intracellular FAA accumulation and on the extracellular regulation of blood divalent cation concentration. This dependency indicates one interaction of extra- and intracellular osmoregulation in R. cuneata.     

Female discharges are more electrifying: spontaneous preference in the electric fish,Eigenmannia (Gymnotiformes,Teleostei)

Summary The tropical South American teleost Eigenmannia lineata showed a spontaneous preference for the female type, compared with the male type, of its sexually dimorphic, weak-electric organ discharge (EOD). Female and male EODs differ in waveform and harmonic content. An isolated fish was simultaneously stimulated with digitally synthesized natural male and female EODs of equal peak-to-peak amplitudes, at ±35 Hz frequency difference centered on its stable resting discharge frequency. The stimulus dipoles were arranged symmetrically to the right and left of the fish's hiding place. All stimulus conditions were permuted at random sequence. Among 11 fish tested, 8 showed a statistically significant preference for one stimulus, the female type, as measured by the amount of time a fish spent close to a stimulus dipole (P<0.05 in each fish, two-tailed). Thus female EODs rather than male EODs were more attractive to adult and juvenile fish of both sexes. It was also concluded that E. lineata is capable of discriminating female from male EODs by a complex sensory capacity requiring neither amplitude nor frequency cues. The EOD waveform changed very little within the ecological range of water conductivities (approximately 10–100 S·cm^-1); the P/N-ratio (a waveform character based on zerocrossing intervals) depended only weakly, but significantly, on conductivity (negative correlation in all four fish). Also, the effect of temperature on EOD waveform was very weak: Q ₁₀-values of the P/N-ratio were below but close to 1 in all fish (27±5°C). Thus, it can be concluded that the EOD waveform is remarkably stable within widely changing conditions-even beyond the variation found in the field-and is therefore potentially useful as a social cue.     

Developing a theoretical foundation to change road user behavior and improve traffic safety: Driving under the influence of cannabis (DUIC)

Objectives: This study explored a theoretical model to assess the influence of culture on willingness and intention to drive under the influence of cannabis (DUIC). This model is expected to guide the design of strategies to change future DUIC behavior in road users.

Methods: This study used a survey methodology to obtain a nationally representative sample (n = 941) from the AmeriSpeak Panel. Survey items were designed to measure aspects of a proposed definition of traffic safety culture and a predictive model of its relationship to DUIC.

Results: Although the percentage of reported past DUIC behaviors was relatively low (8.5%), this behavior is still a significant public health issue—especially for younger drivers (18–29 years), who reported more DUIC than expected. Findings suggest that specific cultural components (attitudes, norms) reliably predict past DUIC behavior, general DUIC willingness, and future DUIC intention. Most DUIC behavior appears to be deliberate, related significantly to willingness and intention. Intention and willingness both appear to fully moderate the relationship between traffic safety culture and DUIC behavior.

Conclusions: This study explored a theoretical model to understand road user behavior involving drug (cannabis)-impaired driving as a significant risk factor for traffic safety. By understanding the cultural factors that increase DUIC behavior, we can create strategies to transform this culture and sustain safer road user behavior.     

Climate change impacts in the Middle East and Northern Africa (MENA) region and their implications for vulnerable population groups

Regional Environmental Change - The Middle East and North Africa (MENA) region emerges as one of the hot spots for worsening extreme heat, drought and aridity conditions under climate change. A...     

Some Air Pollution Problems Associated with Agriculture in Texas

A report of some experiences with air pollution problems associated with the cotton ginning industry and the application of agricultural insecticides and herbicides.