William Scott

Values of unsaturated water content determined with neutron moisture measurements (NMM) reveal different water profiles below different plantings. In the extremes, calibration requires a linear and logarithmic response (using the Lambert-W function) along with the normal submersion in a drum of water. Nevertheless a post-calibration with a hydraulic push sampler was used for confirmation. Data were collected at six pastures near the Western Australia coast near Geraldton, with four replicates through the profile. The sites have mostly sandy soils and receive 300–500 mm of rainfall annually. Findings generally showed that, if there was sufficient water, as in 2006, the perennials were able to use the water evenly throughout the vertical profile. Otherwise, with low rainfall, as in 2009, perennials struggle to survive and use less water than the annuals. Modelling of the soil water movement, plant growth and calibration/recalibration is and will be used to get a maximum likehood fit. Clearly, in desert conditions and little or no vegetation, rainfall tends to build up deep in the profile, increase salinity in groundwater, and create waterlogging. Any vegetation is helpful; perennials more so; provided they have sufficient water and are not significantly harvested.

Soil core samples were collected at Ashfield to determine the extent of Acid Sulfate Soils (ASS), and pin-point hot spots. ASS are major problems to environmental health, to people and infrastructures, from acidity and the movement of toxic heavy metals. Field and laboratory testing were used; (Field pH), Chloride to Sulfate ratios (Cl:SO4), as well as the Suspension Peroxide Oxidation Combined Acidity and Sulfate (SPOCAS) suite. Statistics show that Field pH measurements are sufficient in the detection of ASS; SPOCAS tends to confirm the results of the conservative Field pH measurements. Cl:SO4 ratios do not detect ASS in the same way as SPOCAS and cannot be considered as surrogates for Field pH or SPOCAS techniques. A decision tree presents a basis for analysing ASS, which might be used by an Environmental Health Officer.

Historic observations of sea-level on Macquarie Island recorded an ∼ 6 min oscillation with a perceived beat of ∼ 3 h, interpreted as two counter-rotating edge waves of slightly different frequencies. Alternative evidence is presented here that the oscillations are consistent with the fundamental shelf period of Buckles Bay; an envelope characteristic of local coast and shelf features. New data from a shore-mounted tide gauge, analyzed using fourier and wavelet techniques, show an ∼ 6.6 min phenomenon occurring in bursts every 1-4 h. A simple model shows that the fundamental resonant frequency may spread and comply with maximum and minimum coast and shelf features.

A method is developed to estimate the stress at the surface in a portable wind tunnel for wind erosion studies. The boundary layer height and the pressure gradient are used in a simple expression from the Kármán Integral Momentum Equation. Values of friction velocity u* are within 10% of experimental values obtained through correlation techniques, including measurements of differential pressures with the Murdoch Turbulence Probe MTP and the X-wire, hot-wire anemometer XWA. Wind velocity and stress profiles reveal logarithmic trends and a 'constant stress layer' near the surface in the DAWA portable wind tunnel. Realignment of the statistics with the mean wind is essential.

An early analysis of data for Acid Sulphate Soil ASS detection uses field based measurements of pH and laboratory based measurements of Cl/SO4 and SPOCAS at Ashfield, Western Australia. Statistically, no test is outstanding and the tests are not necessarily the same. Field pH testing is inexpensive and worth doing but statisti¬cally Field pH and Cl/SO4 are insignificantly related (P = 0.045) Fisherʼs Exact Test. Cl/SO4 testing rarely gives a negative result. When the Field pH gives a negative result, Cl/SO4 is unlikely to confirm it. Field pH and SPOCAS are significantly re¬lated (P = 0.022, Fisherʼs Exact Test); large numbers of positive and negative results lend power to this statement. It is particularly concerning that when the Field pH and Cl/SO4 agree, the SPOCAS only gives a positive result 68% of the time, a figure not statistically different to 50%. The follow-up suggests numerical readjustments of the cutoff for the tests and the protocol for ASS in Western Australia, in the shape of a decision tree.

Looks at the ways catalysis can occur through the action of bacteria. With billions of years of evolution, bacteria have taken every opportunity to direct and optimise the reaction coordinate. One model is a staircase with step sizes, shapes, and direction such that there is piecewise control over the whole reaction. Steps of a single size are appropriate; the effect of a series of reactions of smaller activation energies is explored; an optimal number of steps is found, with an individual step being RT. Specific data on Fe(II) oxidation and inoculation with ochre sludge were mined (from Stevenson, 1991); the data are for a controlled pH of 5.8, oxygen at 0.023atms and without nutrient limitations. It seems that 3 to 5 steps are involved in increasing the oxidation rate 3.3 to 7.6 times. A catalytic kinetic model involving protein as a surrogate for cells is used to fit the data. Two simultaneous differential equations evolve and are fitted to the initial and final concentrations of Fe(II) and protein. The observed trends are incompletely fit by the model but the parametric values give some insight into bacterial catalysis. The fractional mass increase in oxidation

I want to report to you the results of my calculations on the step-drawdown test that Andrew com¬pleted before they pulled the pump out. The pump you saw yesterday failed early this week. I believe it was an electrical fault. There was no problem with the hole. They put a new pump in the hole. The question is whether or not we can sense the presence of bacteria. I have done a number of standard tests on wells, through studentsʼ activities over the past 20 years or so, and some specially for this workshop. In addition, Murdoch has commissioned step-drawdown tests or simplest specific capac¬ity tests including outlet pressure and current to the well equipment on irregular occasions through many years with several different consultants. Andrew Ogden of Western Irrigation has completed a number of them, including a recent test on this particular bore hole, in November of last year, and now a step drawdown test with a new pump.

The force of wind on the ground created by turbulent eddies is commonly used to describe the horizontal flux of material during wind erosion. Here we present the Murdoch Turbulence Probe, an instrument for use in both clean and eroding flows which uses pressure differences to measure the three components of wind velocity. Correlation techniques calculate the forces near the ground and turbulence statistics in nearly real time, including turbulent velocity fluctuations from less than 0.1 Hz to 200 Hz, mean flow velocities, Reynolds stresses as well as the integral length and time scales. In the portable wind-tunnel used by Agriculture Western Australia, turbulence statistics were recorded over stable surfaces and in blowing sand from the initiation of erosion up to the time the sand supply was exhausted. Estimates of the friction velocity derived from the turbulence probe were compared with estimates obtained from the wind speed profile measured with a rake of pitot and static tubes. The Murdoch Turbulence Probe appears to work well in sandblasting conditions. Relative turbulence intensities ranged from 0.11 to 0.2 and are in close agreement with values in the literature. The ratio of the turbulence to the friction velocity (3 to 3.2) is at the high end of the reported range. The Reynolds stress measurements agree closely with predictions of the threshold friction velocities of the sand and estimates from the wind speed profile with a von Kármán constant of about 0.3, lower than the commonly accepted value of 0.4. We suggest that the wind-tunnel profile represents the 'outer layer' of the boundary-layer that may best be described by a 'Wake Law' or 'Defect Law'. At about 54 mm above the surface, the friction velocity decreases from 0.64 m/s to 0.39 m/s and the mean velocity increases from 9.6 m/s to 11.6 m/s as the supply of sand is depleted. In addition to the friction velocity, other scales may be necessary to characterise the overriding effect of the wind and in extending wind-tunnel results to the field.

Scripts are presented for slapstick scenes that can allow greater student anticipation, pleasant repetition and teaching enjoyment. This may seem a 'waste' of time but they allow objective, friendly and critical reflection. It is not for every personality and requires a 'tough hide'. This is to present a few teaching scenarios that receive good responses from students, add flavour and have impact on both students and staff. We found this 'happening' in 1995 and 1996, mostly in the first year course, Introduction to Environmental Sciences.