A bench-scale investigation of land treatment of soil contaminated with diesel fuel.

A bench-scale investigation (soil pan testing) was conducted with the objective of studying degradation rates of diesel contaminated soil (2500 and 10,000 ppm by weight of total petroleum hydrocarbons (TPH) to dry weight of soil) under different treatment conditions over a 17 week testing period. The greatest degradation of the diesel contaminated soil was obtained with the addition of nutrients (Co = 10,000 ppm of TPH; k = 0.19 week-1). 'k' for soil not amended with nutrients was 0.07 week-1. The control cell (C0 = 2500 ppm TPH), with sodium azide (to suppress degradation) was compared with an experimental cell of 2500 ppm initial concentration of TPH without nutrient amendment. The control cell exhibited a relatively low uniform degradation (k = 0.08 week-1) of TPH over the duration of the experiment with reasonable first-order kinetic regression statistics.     

Effects of nutrient limitation on toxin production and composition in the marine dinoflagellate Protogonyaulax tamarensis

Toxin production was measured by high pressure liquid chromatography (HPLC) when the marine dinoflagellate Protogonyaulax tamarensis (NEPCC 255) was grown under nitrogen or phosphorus limitation. The major toxins found in P. tamarensis (255) consisted of (N21-SO ₃ ^- )STX (11%), (N21-SO ₃ ^- )NeoSTX (44%), and [(N21-SO ₃ ^- )GTX₂ plus (N21-SO ₃ ^- )GTX₃] (20%). Total toxin content on a per cell basis was high for cultures in log phase (30 to 40 fmol cell^-1) and then decreased to ca 20 fmol cell^-1 as the cultures entered stationary phase. There was a gradual decrease in the toxin content per cell during nitrogen-limited stationary phase to ca 3 fmol cell^-1 or less. Phosphorus-limited cultures showed a markedly different response than nitrogen-limited cultures. Toxin content in P-limited cells dramatically increased at the start of stationary phase, reaching levels 3 to 4 times that observed in control and nitrogen-limited cultures. These results cannot be explained by changes in the average cell volume. Eventhough dramatic effects on the total toxin concentration were observed in response to nutrient limitation (N or P), the toxin composition (on a percent basis) remained constant. This suggests that the individual toxin composition of a given isolate is a fixed genetic trait and not a transient response to changing environmental factors.     

Ventilation efficiency

Research indicates that ventilating systems can be designed for higher ventilation efficiency in the zone of occupation than systems designed for complete mixing. Expressions for ventilation efficiency are derived using a two-box theoretic model. These definitions of ventilation efficiency can be used for practical measurements, and also seem to be valid for multibox schemes. Measurements reviewed show that diagonal schemes are the most efficient. Short-circuiting schemes, with warm air supply along the ceiling and high wall exhaust, produce very low efficiencies. The mathematical model predicts high efficiencies using diffuse air supply directly to the zone of occupation, if the air is not used heating.     

东非十足类螃蟹迈纳新胀蟹对红树林海底落叶的清理

本文通过在东非进行的一系列野外和实验室试验,研究了丰富的红树林十足类螃蟹迈纳新胀蟹(Neosarmatium meinerti)对落叶的清理.在地势高的海榄雌(Avicennia meinerti)潮间带,螃蟹掩埋了所有红树林林区海底的落叶,而且会在2小时内平均消耗其中的67%.     

Visual fields in Flamingos: chick-feeding versus filter-feeding

In birds, the position and extent of the region of binocular vision appears to be determined by feeding ecology. Of prime importance is the degree to which vision is used for the precise control of bill position when pecking or lunging at prey. In birds that do not require such precision (probe and filter-feeders), the bill falls outside the binocular field, which extends above and behind the head, thus providing comprehensive visual coverage. Flamingos Phoenicopteridae are highly specialised filter-feeders. They employ a unique technique that does not require accurate bill positioning in which the inverted head is placed between the feet. Feeding flamingos often walk forwards with the head pointing “backwards”. Here we show that in Lesser Flamingos Phoeniconaias minor visual fields are in fact the same as those of birds that feed by precision pecking and that feeding flamingos are blind in the direction of their walking. We suggest that this is due to the requirement for accurate bill placement when flamingos feed their chicks with “crop-milk”, and possibly when building their nest. We propose that chick-feeding may be the ultimate determinant of visual field topography in birds, not feeding ecology.