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121.
Metals and radionuclide levels in marine birds of the Aleutians are of interest because they are part of subsistence diets of the Aleut people, and can also serve as indicators of marine pollution. We examined geographic and species-specific variations in concentrations of radionuclides in birds and their eggs from Amchitka, the site of underground nuclear tests from 1965 to 1971, and Kiska Islands (a reference site) in the Aleutians, and the levels of lead, mercury and cadmium in eggs. In 2004 we collected common eiders (Somateria mollissima), tufted puffins (Fratercula cirrhata), pigeon guillemot (Cepphus columba) and glaucous-winged gulls (Larus glaucescens) from Amchitka and Kiska, and eggs from eiders and gulls from the two island. We also collected one runt bald eagle (Haliaeetus leucocephalus) chick from both Amchitka and Kiska Islands. For most species, the levels of radionuclide isotopes were below the minimum detectable activity levels (MDA). Out of 74 cesium-137 analyses, only one composite (gulls) was above the MDA, and out of 14 composites tested for plutonium (Pu-239, 240), only one exceeded the MDA (a guillemots). Three composites out of 14 tested had detectable uranium-238. In all cases, the levels were low and close to the MDAs, and were below those reported for other seabirds. There were significant interspecific differences in metal levels in eggs: gulls had significantly higher levels of cadmium and mercury than the eiders, and eiders had higher levels of lead than gulls. There were few significant differences as a function of island, but eiders had significantly higher levels of cadmium in eggs from Kiska, and gulls had significantly higher levels of mercury on Kiska. The levels of cadmium and mercury in eggs of eiders and gulls from this study were above the median for cadmium and mercury from studies in the literature. The levels of mercury in eggs are within the range known to affect avian predators, but seabirds seem less vulnerable to mercury than other birds. However, the levels of mercury are within the action levels for humans, suggesting some cause for concern if subsistence Aleuts eat a large quantity of eggs.  相似文献   
122.
Studies carried out in the NE coastal zone of the State of Pará (Brazil) have recorded, in the last 25 years, numerous evidence of natural impacts of the flood and erosion processes. As a consequence, diverse strategies and measures of population adaptation have been implemented but with limited success. Therefore, in order to subsidize the Coastal Zone Management Program of Pará, this paper aims to identify, assess and classify natural and socio-economic vulnerabilities of this coastal zone by means of a Geographical Information Systems (GIS)-based composite coastal vulnerability index (CVI). In spite of the data problems and shortcomings, using ESRI’s Arcview 3.2 program, the CVI score, to classify, weight and combine a number of 16 separate natural and socio-economic variables to create a single indicator provides a reliable measure of differences (5 classes) among regions and communities that are exposed to similar ranges of hazards. The results are presented in three maps referred to as Natural, Socioeconomic and Total Vulnerability. The confidence associated with the results obtained, the need to utilize another variables, and to frequently update the ones used already were analyzed and discussed.  相似文献   
123.
The chemical and size characterisation of aerosol in northern Italy was investigated by means of transport chemical aerosol model (TCAM) multiphase model long-term simulations performed within the frame of the CityDelta-CAFE exercise. The results show a high contribution of secondary inorganic compounds, in particular far from the Milan metropolitan area and in the large rural area of the Po valley where the major chemical fractions are ammonium and nitrates. The sulphate contribution is quite similar throughout this region, with the exception of areas close to SOx point emissions. Primary PM and organic compounds fractions, on the other hand, are greater close to major urban areas, in particular the Milan metropolitan zone. This work also presents a seasonal characterisation analysis of physical and chemical aerosol features. The results show that in winter, due to domestic heating emission of NOx and low temperatures, which favour the formation of secondary nitrate and organic aerosol, the PM10 and PM2.5 concentrations are higher than those in summer, in agreement with experimental data presented in several studies focussing on the same region.  相似文献   
124.
Atmospheric particulate matter is altering climate. For instance marine biogenic particles are cooling climate. Organic markers are major tools to elucidate the sources of atmospheric particulate matter. Formate is commonly used as a marker of continental aerosols, whereas methanesulphonate is used as tracer of biogenic marine aerosols. However, transformation processes during aerosol transport may modify their relative concentrations and, in turn, introduce a bias in the assessment of particle sources. Actually very little is known about the transformation of formate and methanesulphonate in aerosols. Therefore, we irradiated formate and methanesulphonate in the presence of nitrate and haematite. Nitrate and haematite are aerosol photosensitisers, producing reactive species that degrade organic compounds. The time evolution of formate and methanesulphonate was monitored by ion chromatography. Our results show that formate is transformed from 1.6 to 4.1 times faster than methanesulphonate. This trend is partly due to higher reactivity with the hydroxyl radical and partly due to additional reaction with other transients such as nitrogen dioxide. Such results strongly suggest faster formate transformation during particle transport. Therefore, when formate and methanesulphonate are used as particle tracers, an overestimation of marine biogenic versus continental particle sources is expected. This bias has major implications for climate prediction models, because marine biogenic particles have a cooling effect on climate.  相似文献   
125.
The mean of a balanced ranked set sample is more efficient than the mean of a simple random sample of equal size and the precision of ranked set sampling may be increased by using an unbalanced allocation when the population distribution is highly skewed. The aim of this paper is to show the practical benefits of the unequal allocation in estimating simultaneously the means of more skewed variables through real data. In particular, the allocation rule suggested in the literature for a single skewed distribution may be easily applied when more than one skewed variable are of interest and an auxiliary variable correlated with them is available. This method can lead to substantial gains in precision for all the study variables with respect to the simple random sampling, and to the balanced ranked set sampling too.  相似文献   
126.
Environmental Science and Pollution Research - Microplastics are contaminants of great concern all over the world. Microplastics constitute pollutants themselves; moreover, other contaminants such...  相似文献   
127.
Three blends formed by: agro-industrial waste, wastewater sewage sludge, and their mixture, blended with tree pruning as bulking agent, were composted over a 3-month period. During the composting process the blends were monitored for the main physical and chemical characteristics. Electrofocusing (EF) was carried out on the extracted organic matter. The EF profiles were analyzed by principal component analysis (PCA) in order to assess the suitability of EF to evaluate the stabilisation level during the composting process. Throughout the process, the blends showed a general shifting of focused bands, from low to high pH, even though the compost origin affected the EF profiles. If the EF profile is analyzed by dividing it into pH regions, the interpretation of the results can be affected by the origin of compost. A good clustering of compost samples depending on the process time was obtained by analyzing the whole profile by PCA. Analysis of EF results with PCA represents a useful analytical technique to study the evolution and the stabilisation of composted organic matter.  相似文献   
128.
Environmental Science and Pollution Research - This study aimed at investigating the photochemical behavior of sulfa drugs containing five and six-membered heterocyclic substituents...  相似文献   
129.
Fetal growth restriction (FGR) is a common complication of pregnancy, associated with higher risk of perinatal mortality and adverse health and developmental outcomes for surviving infants. True FGR relates to a pathological restriction of fetal growth resulting from complex interactions between maternal, placental, fetal, and environmental factors. Early-onset FGR (onset <32 weeks' gestation) is often first suspected at routine mid-trimester sonographic assessment of fetal morphology, or identified as part of the placental syndrome, commonly maternal pre-eclampsia. Prenatal investigations may identify the cause of FGR. Timing of delivery is guided by serial sonographic surveillance of fetal growth and well-being and maternal condition, balancing the risk of stillbirth with the benefits of advancing gestation. This is particularly pertinent to severe early-onset FGR, a leading iatrogenic cause of very preterm birth. Prognosis is largely determined by the severity of FGR and its causes, gestation at birth, and birthweight. Pregnancy termination may be considered. Antenatal care and delivery in a tertiary center, provided by a multi-disciplinary team with expertise in managing high-risk pregnancies, are imperative to optimizing outcomes.  相似文献   
130.
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