No abstract

The silver nitrate/fluorescein mercuric acetate fluorimetric method for the measurement of atmospheric hydrogen sulfide has been adapted to passive sampling. Standard samplers have been tested and used in both indoor and outdoor environments. Sampler performance was not dependent on construction materials or sunlight intensity and gave similar results to active sampling. Two case studies were carried out, one in the Horniman Museum and its associated storage and study building, London, UK, and the other in the vicinity of a pulp and paper mill and geothermal area North Island, New Zealand. The detection limit of the samplers (50 ppt average for a one-week exposure) provides the opportunity to make measurements in a variety of locations provided exposure times are sufficiently long, i.e., up to one month in areas of low hydrogen sulfide concentration.

SumnaryIn a study of some aspects of the rate and type of decomposition of leaf litter of Abies grandis Lindley, Picea sitchensis (Bongard) Carribre, and Pinus sylvestris L., the external features of the needles at different stages of decay have been recorded, together with the micro-fungi appearing on the needles and cultured from them. A regular sequence of colour changes was demonstrated, from the original green to grey-green, brown, grey to black. Unless conditions were very favourable, the litter of Piceu sitchenris changed colour much more slowly than that of the other species. The proportion of collapsed leaves increased progressively with time, although in the earlier stages of decay reversion to the non-sunken condition could occur by water uptake. A definite succession of fungi was recorded as the litter decomposed. Needles remaining affixed to the tree were commonly colonized by Fusicoccum bacillare, accompanied on needles of Pinus by L o p h o h i u m pinastri. On freshly fallen needles, Haplographiurn penicilloides, AsperlgiUs fumigatus, and Penicillium frequentans occurred frequently, together with white hyphal 'cushions' in the stomata1 apertures, and a sterile net-forming surface mycelium.Older litter was colonized'by Trkhodnma t i d e , oidiodendron fuscum, and Verticiclodium trifidum. Mucor hiemalis and Aposphaeria sp. were present throughout the period of decay, together with a number of less common species.

SummaryThe numerical response of adult female T. pyri feeding on different levels of ERM larvae, and at a range of temperatures was examined. The duration of the pre‐oviposition period decreased as larval consumption increased, and the rate of oviposition was linearly related to the rate of consumption of larvae. Mathematical models were used to describe these relationships in terms of temperature and consumption of ERM larvae. The results were discussed in relation to the nature of the T. pyri/ERM interaction in New Zealand apple orchards.