Certain concentration of metal may influence survival in embryonic stages, reducing the birthrate and hatching emergence. This study aimed to evaluate concentration of metal in eggs and hatchlings of Dermochelys coriacea and correlate metal concentrations in eggs with hatching and emergence success. The samples were collected at Biological Reserve Station, ES, Brazil. At the nests' opening, unhatched eggs and stillborn hatchlings were collected to survey the successful hatching and emergence of D. coriacea. The eggs shell, egg content, and dead hatchlings metal concentrations were compared to hatching and emergence success. A positive correlation was found between the concentration of copper (Cu) in the hatchlings and the success of the emergence (r2 = .28, p < .05), and a moderate positive correlation between the concentrations of iron (Fe) and barium (Ba; r2 = .44, p < .05) and success hatching. The concentrations of metals in eggs and hatchlings of D. coriacea in the Espírito Santo are below the levels that could be considered harmful to the species. In summary, there is a positive correlation between metals levels and hatching and emergence success. 相似文献
Evaporation and infiltration were compared for tropical rainforest and pasture, near to Manaus, Brazil from October 1990 to February 1992 using measurements of soil water storage over a depth of 2 m. The soil is a clayey oxisol of low water available capacity. In both of the dry seasons studied, the maximum change in soil water storage in the forest was 154 mm and in the pasture it was 131 and 112 mm. Similar behaviour of the soil water reservoir below forest and pasture in the wet season implied that differences in evaporation and drainage were small. In the dry season, soil water storage behaviour in the upper metre of the soil was similar but there were marked differences in the second metre. The pasture took up little water from below 1.5 m but the forest appeared to utilise all of the available water in the 2 m profile in both seasons.
The water balance of the 2 m profile showed that the pasture evaporation rate was equal to that of the forest until storage had decreased 80 mm from the maximum. There was then a decline in pasture evaporation rate to 1.2 mm day−1 as the storage decreased by a further 50 mm. In contrast, the forest uptake rate remained above 3.5 mm day−1 until storage had decreased 140 mm from the maximum (within 15 mm of the extraction limit), before declining abruptly to less than 1.5 mm day−1. There was strong evidence that the forest was able to abstract water from depths greater than 3.6 m.
Spatial variability of soil water storage was significantly greater beneath the pasture than beneath the forest, particularly following rainfall events in the dry season. This was largely the result of redistribution of rainfall as local surface runoff. There was no evidence of redistribution or runoff in the forest. 相似文献
Résumé Nous appliquons dans ce mémoire la théorie des perturbations, développée antérieuremet par l'un de nous, à la déduction des principales caractéristiques normales des perturbations compatibles avec un champ moyen donné de pression et de température. Cette deduction comprend la détermination: 1) de la configuration moyenne des perturbations dans les différentes régions étudiées; 2) des zones de creusement et de comblement et en particulier des foyers de formation et de disparition des perturbations; 3) des trajectoires, vitesses, fréquences et amplitudes moyennes des perturbations. C'est à l'ensemble de ces propriétés moyennes que nous donnons le nom de «climatologie dynamique» d'une période donnée.Après une première partie théorique, nous donnons des exemples d'application des résultats généraux à la climatologie dynamique des mois de Janvier et de Juillet pour l'Amérique du Nord, l'Atlantique Nord et l'Europe.
Summary In this paper we apply the theory of perturbations, previously developed by one of us, to the deduction of the main normal characteristics of the perturbations that are compatible with a given mean field of pressure and temperature. This deduction comprises the determination: 1) of the mean configuration of the perturbations for the different regions under examination; 2) of the normal deepening and filling regions of the perturbations, and particularly their formation and vanishing focuses; 3) of the mean paths, speeds, frequencies and amplitudes of the perturbations. The «dynamical climatology» we are contemplating here is concerned with all these mean properties of the perturbations for a given period.After a first theoretical part, we give some examples of the application of the general results to the dynamical climatology of January and July for North America, North Atlantic and Europe.
à ce mémoire a été assigné le Prix 1956 de la « Società Italiana di Geofisica e Meteorologia ». 相似文献
Water Resources - The Queima Pé Stream Basin (QPSB) and Ararão River Basin (ARB) in central Brazil have had recurrent problems with water scarcity. This may get worse under anthropogenic... 相似文献
Volcán Huaynaputina is a group of four vents located at 16°36'S, 70°51'W in southern Peru that produced one of the largest eruptions of historical times when ~11 km3 of magma was erupted during the period 19 February to 6 March 1600. The main eruptive vents are located at 4200 m within an erosion-modified amphitheater of a significantly older stratovolcano. The eruption proceeded in three stages. Stage I was an ~20-h sustained plinian eruption on 19-20 February that produced an extensive dacite pumice fall deposit (magma volume ~2.6 km3). Throughout medial-distal and distal parts of the dispersal area, a fine-grained plinian ashfall unit overlies the pumice fall deposit. This very widespread ash (magma volume ~6.2 km3) has been recognized in Antarctic ice cores. A short period of quiescence allowed local erosion of the uppermost stage-I deposits and was followed by renewed but intermittent explosive activity between 22 and 26 February (stage II). This activity resulted in intercalated pyroclastic flow and pumice fall deposits (~1 km3). The flow deposits are valley confined, whereas associated co-ignimbrite ash fall is found overlying the plinian ash deposit. Following another period of quiescence, vulcanian-type explosions of stage III commenced on 28 February and produced crudely bedded ash, lapilli, and bombs of dense dacite (~1 km3). Activity ceased on 6 March. Compositions erupted are predominantly high-K dacites with a phenocryst assemblage of plagioclase>hornblende>biotite>Fe-Ti oxides-apatite. Major elements are broadly similar in all three stages, but there are a few important differences. Stage-I pumice has less evolved glass compositions (~73% SiO2), lower crystal contents (17-20%), lower density (1.0-1.3 g/cm3), and phase equilibria suggest higher temperature and volatile contents. Stage-II and stage-III juvenile clasts have more evolved glass (~76% SiO2) compositions, higher crystal contents (25-35%), higher densities (up to 2.2 g/cm3), and lower temperature and volatile contents. All juvenile clasts show mineralogical evidence for thermal disequilibrium. Inflections on a plot of log thickness vs area1/2 for the fall deposits suggest that the pumice fall and the plinian ash fall were dispersed under different conditions and may have been derived from different parts of the eruption column system. The ash appears to have been dispersed mainly from the uppermost parts of the umbrella cloud by upper-level winds, whereas the pumice fall may have been derived from the lower parts of the umbrella cloud and vertical part of the eruption column and transported by a lower-altitude wind field. Thickness half distances and clast half distances for the pumice fall deposit suggests a column neutral buoyancy height of 24-32 km and a total column height of 34-46 km. The estimated mass discharge rate for the ~20-h-long stage-I eruption is 2.4᎒8 kg/s and the volumetric discharge rate is ~3.6᎒5 m3/s. The pumice fall deposit has a dispersal index (Hildreth and Drake 1992) of 4.4, and its index of fragmentation is at least 89%, reflecting the dominant volume of fines produced. Of the 11 km3 total volume of dacite magma erupted in 1600, approximately 85% was evacuated during stage 1. The three main vents range in size from ~70 to ~400 m. Alignment of these vents and a late-stage dyke parallel to the NNW-SSE trend defined by older volcanics suggest that the eruption initiated along a fissure that developed along pre-existing weaknesses. During stage I this fissure evolved into a large flared vent, vent 2, with a diameter of approximately 400 m. This vent was active throughout stage II, at the end of which a dome was emplaced within it. During stage III this dome was eviscerated forming the youngest vent in the group, vent 3. A minor extra-amphitheater vent was produced during the final event of the eruptive sequence. Recharge may have induced magma to rise away from a deep zone of magma generation and storage. Subsequently, vesiculation in the rising magma batch, possibly enhanced by interaction with an ancient hydrothermal system, triggered and fueled the sustained Plinian eruption of stage I. A lower volatile content in the stage-II and stage-III magma led to transitional column behavior and pyroclastic flow generation in stage II. Continued magma uprise led to emplacement of a dome which was subsequently destroyed during stage III. No caldera collapse occurred because no shallow magma chamber developed beneath this volcano. 相似文献