This paper reports the effects of nutrient magnesium (Mg) concentrations on the growth and photosynthetic physiology of clonal Pinus radiata from four female parents (families) known to differ in their tolerance to Mg deficiency and in their needle Mg concentrations. Plants were grown in flowing nutrient solutions with 2 mg l −" (control) and 0.8 mg l −" (low) Mg. Plant growth, needle Mg concentration, photosynthesis, chlorophyll fluorescence and carotenoid pigment content were measured. At low Mg, needle Mg concentration was about half that of control plants, height growth was reduced 15-25%, and the needles showed strong visual characteristics of Mg deficiency. Photosynthesis was also halved, and was associated with closure of the stomata under low Mg and with reductions in the residual conductance. In needles from plants grown at low Mg, photochemical yield was reduced both in the light and in the dark, and was strongly dependent on needle Mg concentrations below a threshold concentration of 0.02-0.025% (d. wt basis). The electron transport rate (ETR) at saturating photon flux density in low-Mg-grown needles was reduced to about half that of their Mg controls, but the photon efficiency of ETR was unaffected by the Mg concentration the plants were grown in. Photosynthetic quenching was markedly reduced and non-photosynthetic quenching was increased following growth in low Mg. Growth under low Mg also increased levels of zeaxanthin. Although family differences in growth and photosynthetic physiology were present, few familyiMg interactions were significant. We conclude that Mg deficiency probably affects growth through severe reductions in photosynthesis.

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Various methods have been proposed for assessing the cation exchange capacity (CEC) of soils. A pH 7 buffered ammonium acetate solution is the most widely used method but its use for forest soils has been questioned as it may result in an overestimation of CEC in soils with pH dependent charges. The objective of this study was to determine the most appropriate method for measuring the natural CEC of forest soils using variations of 3 common methods. These methods included: (1) pH 7 buffered ammonium acetate (2) unbuffered 1.0, 0.5, and 0.1 M ammonium chloride, and (3) the compulsive exchange method using the original method and with magnesium chloride. The CEC of three reference materials (kaolinite, vermiculite and humified organic matter) was predetermined and used for comparison. In addition, samples from the major genetic horizons of 8 soils from Washington State, USA, the North Island, New Zealand, and Indonesia were analyzed for CEC. Results showed that the 1751

Six test firings of large improvised explosive devices were carried out. The principal objectives of the firings were to measure the physical effects of the explosions upon representative objects placed nearby and to recover any chemical traces deposited on these objects. The results are intended for use as an aid in determining the approximate size and type of an explosive employed in terrorist attacks. Three 454 kg charges of a mixture of calcium ammonium nitrate (CAN) fertilizer and sugar, and three 2268 kg charges of a similar mixture, all confined in cylindrical steel containers were fired. Each charge was surrounded by 19 road signs mounted on posts and four vehicles, to act as witness materials. The analysis of aqueous swab extracts taken from the witness materials after firing showed the recovery of nitrate, ammonium and low levels of glucose. No sucrose was detected. Nitrate was usually recovered in greater quantities than ammonium and recovery generally decreased with increasing distance from the charges in any given direction. Quantities recovered from objects placed at the same distance in different directions varied considerably. Patterns of physical damage to the witness materials could be discerned according to their distance from the charge and the size of the charge. The velocities of detonation and air blast effects were measured.