Seasonal changes of benthic megafauna in the Ría de Muros e Noia (Galicia,North-West Spain)

A community of decapod crustaceans (Brachyura) was sampled seasonally (October 1978–July 1979) from three habitats (raft, middle and beach) in the Ría de Muros e Noia (North-West Spain), with the purpose of studying spatial and temporal changes in the community and comparing with communities in the neighbouring Ría de Arousa, which supports an intense mussel (Mytilus edulis)-raft culture. The Portunidae family dominated the decapod community. Polybius henslowi, a species with pelagic stages, which enters the rías periodically in large numbers, was the dominant species at all the stations throughout the sampling period, attaining densities of 1.6 individuals m^-2 (18.7 g wet wt m^-2) in summer. Macropipus depurator and M. puber were the next most important species at the raft station, M. depurator at middle stations, and M. vernalis and Carcinus maenas at beach stations. The highest population densities were recorded in summer, due to the great abundance of Polybius henslowi at this time. When the data were reconsidered omitting p. henslowi, highest densities were in autumn and winter in the inner ría. In general, the nature of the substratum, the presence of mussel rafts, depth and salinity were the main factors determining the structure of the community. Density and biomass in the Ría de Muros e Noia (P. henslowi omitted) were lower than in the Ría de Arousa (up to six times lower in some areas). The Ría de Muros lacks the extensive number of mussel rafts present in the Ría de Arousa which constitute an important food resource for decapods.     

Effects of bleached kraft mill effluents on the swimming activity of Monoporeia affinis (crustacea, amphipoda) lindström

The crustacean Monoporeia affinis Lindström was exposed to two different concentrations of bleached kraft mill effluent (BKME) containing, originally, 8.3 mg/g organic chlorine determined as adsorbable organic halogen (AOX). The swimming activity of the animals was recorded by pairs of infra-red sensitive photocells attached to 5.6 1 aquaria having a seawater inflow rate of 12 ml/min. The test sequence included a control phase, an exposure phase and a recovery phase. During the exposure phase the total swimming activity decreased in three of the four test aquaria containing effluent, indicating that the animals had retreated into the sediment. Total activity increased during the recovery phase and, in the case of the lower organic chlorine concentration, activity almost achieved the original control-phase level. Statistical differences in swimming activity changes during experiment were evaluated using ANOVA. Experimental methods are explained in detail.     

Nitrogen mineralization and nitrate leaching of a sandy soil amended with different organic wastes.

Organic wastes can be recycled as a source of plant nutrients, enhancing crop production by improving soil quality. However, the study of the dynamic of soil nutrient, especially the N dynamic, after soil application of any organic material is vital for assessing a correct and effective use of the material, minimizing the losses of nitrate in leachates and avoiding the negative environmental effects that it may cause in groundwater. To estimate the effect of three organic materials, a municipal solid waste compost (MWC), a non-composted paper mill sludge (PS), and an agroforest compost (AC) on the N dynamic of a sandy soil two experiments were carried out: an incubation experiment and a column experiment. The incubation experiment was conducted to estimate the N mineralization rate of the different soil-amendment mixtures. The soil was mixed with the organic amendments at a rate equivalent to 50,000 kg ha(-1) and incubated during 40 weeks at constant moisture content (70% of its water-holding capacity) and temperature (28 degrees C) under aerobic conditions. Organic amendment-soil samples showed an immobilization of N during the first weeks, which was more noticeable and longer in the case of PS-treated soil compared to the other two amendments due to its high C/N ratio. After this immobilization stage, a positive mineralization was observed for all treatment, especially in MWC treated soil. Contemporaneously a 1-year column (19 cm diameter and 60 cm height) experiment was carried out to estimate the nitrate losses from the soil amended with the same organic materials. Amendments were mixed with the top soil (0-15 cm) at a rate equivalent to 50,000 kg ha(-1). The columns were periodically irrigated simulating rainfall in the area of study, receiving in total 415 mm of water, and the water draining was collected during the experimental period and analysed for NO3-N. At the end of the experimental period NO3-N content in soil columns at three depths (0-20, 20-35 and 35-50 cm) was determined. The nitrate concentration in drainage water confirmed the results obtained in the incubation experiment: nitrate leaching was higher in soil treated with MWC due to its higher N-mineralization rate. Nevertheless, the nitrate losses represented a low amount compared with the total nitrogen added to soil. No clear signs of water-draining contamination were observed during the first year after the application of AC and PS; however, the nitrate leaching in soil treated with MWC slightly exceeded the limit allowed for the Drinking Water Directive 98/83/CE.     

服务能力解放了当地居民:玻利维亚马迪迪国家公园的恰拉兰生态旅馆

作者们介绍了有关恰拉兰生态旅馆发展的最新信息 , 它是玻利维亚亚马孙地区马迪迪国家公 园综合管理自然区的一个社区项目 .能力建设的最初阶段 (1997- 98)对于巩固恰拉兰 (马迪迪 )生态旅馆的新旅游胜地地位和确保社区在可持续发展自行管理项目中独立自主地进行决策是 最根本的 .作者们把这个项目看作是玻利维亚和亚马孙地区生态旅游发展的模范 .     

Low level radioactivity measurements with phoswich detectors using coincident techniques and digital pulse processing analysis

A new system has been developed for the detection of low radioactivity levels of fission products and actinides using coincidence techniques. The device combines a phoswich detector for alpha/beta/gamma-ray recognition with a fast digital card for electronic pulse analysis. The phoswich can be used in a coincident mode by identifying the composed signal produced by the simultaneous detection of alpha/beta particles and X-rays/gamma particles. The technique of coincidences with phoswich detectors was proposed recently to verify the Nuclear Test Ban Treaty (NTBT) which established the necessity of monitoring low levels of gaseous fission products produced by underground nuclear explosions. With the device proposed here it is possible to identify the coincidence events and determine the energy and type of coincident particles. The sensitivity of the system has been improved by employing liquid scintillators and a high resolution low energy germanium detector. In this case it is possible to identify simultaneously by alpha/gamma coincidence transuranic nuclides present in environmental samples without necessity of performing radiochemical separation. The minimum detectable activity was estimated to be 0.01 Bq kg(-1) for 0.1 kg of soil and 1000 min counting.     

Present status of 222Rn in groundwater in Extremadura

Radon-222 was measured in groundwater sources of Extremadura (Spain), analyzing 350 samples from private and public springs, wells, and spas by liquid scintillation counting (LSC) and gamma spectrometry. The (222)Rn activity concentrations ranged from 0.24 to 1168BqL(-1). The statistical analysis showed a log-normal distribution with a mean of (111+/-7)BqL(-1) and a median of (36+/-3)BqL(-1). A hydrogeological study revealed correlations between the activity concentration and the aquifer material's characteristics. A map of (222)Rn in groundwater was elaborated and compared with the natural gamma radiation map for this region. About 35% of the samples showed (222)Rn activity concentrations above the Euratom recommended limit of 100BqL(-1). Three uranium series radionuclides ((238)U, (234)U, and (226)Ra) were also assayed by alpha-particle spectrometry, estimating the annual effective dose due to the presence of these natural radionuclides in drinking water.     

Characterization of radioactive particles from the Palomares accident

As a consequence of the nuclear accident that took place in Palomares (Almería, Spain) more than 40 years ago, actinides contamination is present in the area nowadays. Previous investigations performed with soil samples collected in different locations of Palomares indicate that the contamination in the area is highly inhomogeneous, suggesting the existence of radioactive particles, thus hindering the evaluation of the radiological situation. This work presents the methodology used for the location of the radioactive particles in the field and their isolation in the laboratory for further speciation and characterization studies. Colour pictures, electron microscopy images and EDX analyses show that most of the studied particles present a granular appearance with a variable grain size and a high fragmentation tendency, being plutonium and uranium the most abundant nuclear elements. Radiochemical determinations and activity isotopic ratios prove that the nuclear material is aged weapon grade plutonium arising from the Palomares accident.