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511.
Yu. N. Litvinov S. A. Abramov V. Yu. Kovaleva A. V. Krivopalov E. A. Novikov A. I. Chechulin 《Russian Journal of Ecology》2007,38(6):413-418
The structural-temporal organization of a murine rodent community in the taiga has been studied near Lake Teletskoe, Mountain Altai. The results show that the long-term dynamics of indices characterizing community diversity depend mainly on changes in the structure of dominance rather than on the population dynamics of species. The distribution of species in the factor space corresponds to their preference for certain biotopes, from dry to relatively moist. An analysis of relationships within the rodent community has revealed the synchronous dynamics of species abundance and antiphase pattern of changes in the structural indices of dominant species. 相似文献
512.
This study deals with the question of how winegrowing in Spain may be altered by anthropogenic climate change. The present state and expected future development of three bioclimatic indices relevant for winegrowing were assessed by observation, and four regional climate models from the EU-ENSEMBLES project were investigated. When comparing the 2061–2090 scenario period to the 1961–1990 reference period, the models unanimously indicate a significant increase in the mean of the two considered thermal indices over the entire study region. However, for the index based on temperature and precipitation, the models are heavily biased when verified against observations and generally disagree on the size of the projected future change. For this index, unanimous model agreement was only found for northwestern Spain where all models indicated a significant decrease in the mean. From these results, regional climate change is expected to negatively affect the quality of wine in the growing regions of central and southern Spain, and the Ebro valley, whereas positive effects should be expected in the northwest. No significant changes in the risk of mildew infestation are to be expected except for the northwest, where this risk is projected to decrease. 相似文献
513.
Effect of aluminum sulfate and cationic polyelectrolytes on the destabilization of emulsified wastes 总被引:9,自引:0,他引:9
Emulsified oil in wastewater constitutes a severe problem in the different treatment stages. Aluminum salts have been traditionally used as coagulants in wastewater treatments. Polyelectrolytes are used to coagulate and flocculate colloidal systems. The performance of aluminum sulfate in comparison to polyelectrolytes (chitosan and polyacrylamide) as conditioning chemicals for an emulsion waste was tested, and the predominant mechanisms acting in each case were analyzed. Turbidimetry, jar test, colloidal titration and microscopy were used to test emulsion destabilization. Both charge neutralization and bridge formation were identified and confirmed as mechanisms of interaction of polyelectrolytes with waste constitutents. Charge neutralization would be more important for chitosan than for polyacrylamide treatment. A coincidence between the doses necessary to reach zero colloidal charge and minimum turbidity was observed for polyelectrolytes. The time necessary to produce system clarification was larger for aluminum sulfate than for polyelectrolytes; this time was shortened for higher aluminum sulfate concentration. The pH showed a marked effect on aluminum sulfate performance with the optimum at pH 6; polyelectrolyte action was practically not affected by pH. Polyelectrolyte addition produced the minimum turbidity for the same doses that zero colloidal charge; at higher doses, emulsion was restabilized and became turbid again. However, aluminum sulfate treatment did not produce emulsion restabilization. 相似文献
514.
515.
Lead is a widespread element and one of the persistent and cumulative pollutants of the environment. The present study deals with the bioaccumulation of lead and the influence of chelating agents, meso 2,3-dimercaptosuccinic acid (DMSA), D-Penicillamine and CaNa2EDTA in reducing the concentration of lead on the selected organs of Catla catla fingerlings for both acute and chronic exposures by using ICP-AES. It is inferred from the present findings that there was a correlation between environmental conditions and the heavy metal contents of the fish. The highest concentration of lead is found in kidney tissues and the lowest in muscle tissues. The accumulation pattern of lead in the selected organs of Catla catla is: kidney > liver > gill > brain > muscle. Also, it has been found that the treatment of chelating agents, DMSA, D-Penicillamine and CaNa2EDTA reduces the concentration of lead significantly for both acute and chronic exposures. The results also show that DMSA is the most effective chelator of lead in reducing the body burden of C. catla fingerlings. The observed data further indicate that C. catla could be suitable for monitoring organisms to study the bioavailability of water-bound metals in freshwater habitats. 相似文献
516.
Surface swarms of the stomatopod Oratosquilla investigatoris (Lloyd, 1907) were observed in the Gulf of Aden and the equatorial western Indian Ocean during 1967. Collections from inshore and offshore swarms were made in both areas, and from demersal trawl catches in the equatorial area. O. investigatoris was also collected from the stomachs of several species of oceanic pelagic and inshore fish from 1965 to 1967, and was also reported in the stomach contents of the lesser frigate bird. Further collections were made from strandings on two oceanic islands in the equatorial area. Indirect observations on the occurrence of the species resulted from increased predation on pelagic longline baits during seasos of apparent abundance of O. investigatoris in the equatorial region. At the surface, predation by the species was observed on fast-swiming fish, and the swimming behaviour was noted. A size range of 6 to 37 mm carapace length (CL) was recorded for the 4000 specimens collected, and there was no size difference between the sexes. Length-frequency analysis of the samples indicated a major mode at 19 to 21 mm CL and an increase in length of 3 mm over 3 months. The sex ratio was weighted in favour of females in the majority of collections. It was concluded that the pelagic swarming of O. investigatoris is an important ecological phenomenon, but not regular in the area, and the factors affecting it could not be deduced from the available data. 相似文献
517.
518.
Fuga A Saiki M Marcelli MP Saldiva PH 《Environmental pollution (Barking, Essex : 1987)》2008,151(2):334-340
The Canoparmelia texana epiphytic lichenized fungi was used to monitor atmospheric pollution in the S?o Paulo metropolitan region, SP, Brazil. The cluster analysis applied to the element concentration values confirmed the site groups of different levels of pollution due to industrial and vehicular emissions. In the distribution maps of element concentrations, higher concentrations of Ba and Mn were observed in the vicinity of industries and of a petrochemical complex. The highest concentration of Co found in lichens from the S?o Miguel Paulista site is due to the emissions from a metallurgical processing plant that produces this element. For Br and Zn, the highest concentrations could be associated both to vehicular and industrial emissions. Exploratory analyses revealed that the accumulation of toxic elements in C. texana may be of use in evaluating the human risk of cardiopulmonary mortality due to prolonged exposure to ambient levels of air pollution. 相似文献
519.
S.K. Kashyap J.P. Jani H.N. Saiyed S‐K. Gupta 《Journal of environmental science and health. Part. B》2013,48(4-5):479-489
Abstract Phorate (Thimet), an aliphatic derivative of phospnorus is a hignly toxic insecticide. In order to implement the safety measures, the clinical manifestations and cholinesterase (ChE) activity were evaluated before and after 2 weeks of exposure to this insecticide in 40 male tormulators. The 2 week's exposure reveal signs and symptoms of toxicity in 60% of the formulators. Gastrointestinal symptoms and lowering of heart rate (bradycardia) were more prominent as compared to the neurological symptoms. A significant depression in plasma ChE activity was observed at the end of 1st week (55%) and 2nd week (71%) as compared to the respective pre‐exposure values. A recovery up to 79% of the pre‐exposure activity of this enzyme was noticed 10 days after cessation of the above exposure. 相似文献
520.
Urinary tract anomalies are common. Prenatal diagnosis is important and enables either special obstetric management or termination of pregnancy and probably in the future, intrauterine intervention. Transvaginal sonography (TVS) allows visualization of the normal and anomalous fetal urinary tract at an early stage. One thousand nine hundred and forty women were examined via TVS at an early stage of pregnancy between 10 and 16 weeks from the last menstrual period (LMP) and 35 anomalies (1·8 per cent) were clearly identified: 29 cases of low urinary tract obstruction, 2 cases of multicystic dysplastic kidney, 2 cases of polycystic kidney (infantile type), 1 case of double collecting system, and 1 case of horseshoe kidney. Potter syndrome could be ruled out in three patients who had delivered fetuses suffering from this anomaly in previous pregnancies. The concise and early identification of anomalies makes TVS an important aid in the hands of the obstetrician, ultrasonographer, and neonatologist. 相似文献