Sustratos de cobertura y suplementación del compost en cultivo de champiñón

El objetivo de este trabajo fue describir el comportamiento de la corteza de pino, de la fibra de coco y del sustrato postcultivo, como capas de cobertura, en el cultivo del champiñón (Agaricus bisporus). Tras la caracterización física, química y biológica de las capas de cobertura, se evaluaron los parámetros de producción cualitativos y cuantitativos, en un ciclo de cultivo de champiñón con cuatro floradas. La menor porosidad y capacidad de retención de agua del suelo mineral, sin aditivos, y la alta conductividad eléctrica del sustrato postcultivo del champiñón utilizado, asociado a la suplementación nutritiva, son los factores determinantes en el diferente comportamiento agronómico observado. Las mezclas de cobertura influenciaron el rendimiento y el número de champiñones, la eficiencia biológica, la tasa de producción y la precocidad. El mejor rendimiento total se obtuvo con la mezcla de suelo mineral y fibra de coco suplementado. Las capas de coberturas evaluadas pueden ser utilizadas comercialmente para la producción de champiñón

Natural radioactivity in private water supplies in Devon

Between 1986 and 1996 the Department of Environment (DOE) commissioned annual radiological assessments on various private water supplies to households in England and Wales. Each study examined samples from approximately 100 different households in a selected area for a range of natural and artificial radionuclides and, out of the samples studied, about 20% were also analysed for 222Rn. In each study, committed effective dose equivalents (CEDEs) were calculated for the observed radionuclides for hypothetical critical groups of householders based on the consumption of a year’s supply of drinking water. Three groups of consumers were studied - infants (< 1 year old), children (1-10 year old) and adults. The most recent dose conversion factors (ie. Dose per unit uptake factors) were used. Some of the results obtained for areas studied in 1990 (e.g. Kerrier and Restormel districts in Cornwall), exceed the World Health Organisation’s (WHO’s) guideline activity concentration value for radioactivity in drinking water. The WHO recommend a reference level of committed effective dose of 0.1mSv (for adults) for one year’s consumption of drinking water (based on the consumption of two litres of drinking water per day). Although the WHO guideline does not differentiate between natural and man-made radionuclides, the CEDEs calculated for the areas in Cornwall were predominantly due to the naturally occurring radionuclide 222Rn and, to a lesser extent, 210Po. The WHO recognise the difficulty in applying its guideline to 222Rn An area of West Devon around Tavistock was selected by the Department of the Environment, Transport and the Regions (DETR) for further, more focused, research. The aim of the research, as identified in the project specification, is to define: • the concentration of 222Rn in 100 private water supplies from West Devon; • temporal and spatial variations (within the household supply and distribution system) of 222Rn and 210Po content in the three water supplies selected from the detailed study; • the dose received by members of the household taking into account their actual drinking water consumption patterns rather than by assuming the 2 litres per day estimate given by WHO. The DETR awarded the British Geological Survey (BGS) a contract, reference number RW 5/2/299, EPG 1/4/51, to carry out this work. As the first phase of the project the BGS arranged for 128 private supplies in West Devon to be sampled and analysed for 222Rn, 226Ra, 238U and 232Th. Three supplies with very high radon concentrations have also been sampled for 210Po. Although the original work programme envisaged sampling only springs, wells and boreholes, discussions with West Devon Borough Council (WDBC) revealed a number of other private water supply types in the district. With the agreement of the DETR, a small number of these supplies, including river/stream extractions, mine drainage from adits and open, artificial waterways (known in the area as leats) were included in the sampling programme. Under subcontract to BGS WDBC staff liaised with local householders to obtain the samples