Wet and dry deposition of 129I in Seville (Spain) measured by accelerator mass spectrometry

Iodine-129 (Full-size image (<1 K)) concentrations have been determined by accelerator mass spectrometry in rainwater samples taken at Seville (southwestern Spain) in 1996 and 1997. This technique allows a reduction in the detection limits for this radionuclide in comparison to radiometric counting and other mass spectrometric methods such as ICP-MS. Typical 129I concentrations range from 4.7×107129I atoms/l (19.2%) to 4.97×109129I atoms/l (5.9%), while 129I depositions are normally in the order of 108–1010 atoms/m2 d. These values agree well with other results obtained for recent rainwater samples collected in Europe. Apart from these, the relationship between 129I deposition and some atmospheric factors has been analyzed, showing the importance of the precipitation rate and the concentration of suspended matter in it.

The ecoclimatology of Danum, Sabah, in the context of the world's rainforest regions, with particular reference to dry periods and their impact

Climatic records for Danum for 1985 to 1998, elsewhere in Sabah since 1879, and long monthly rainfall series from other rainforest locations are used to place the climate, and particularly the dry period climatology, of Danum into a world rainforest context. The magnitude frequency and seasonality of dry periods are shown to vary greatly within the world's rainforest zone. The climate of Danum, which is aseasonal but subject, as in 1997 to 1998, to occasional drought, is intermediate between less drought–prone north–western Borneo and the more drought–prone east coast. Changes through time in drought magnitude frequency in Sabah and rainforest locations elsewhere in South–East Asia and in the Neotropics are compared. The 1997 to 1998 ENSO–related drought event in Sabah is placed into a historical context. The effects of drought on tree growth and mortality in the tropics are assessed and a model relating intensity and frequency of drought disturbance to forest structure and composition is discussed.