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41.
In the course of researches into radon occurrence in the groundwaters of the Polish part of the Sudety Mountains, conducted in various research centres in Poland, almost 1000 radon concentration determinations have been collected. These results have given the basis for an attempt to characterise the groundwaters of this region with respect to radon content. Radon concentrations oscillated within the range of 0.2-1645 Bq/dm3, with the arithmetic mean at 240.0 Bq/dm3 and the geometric mean at 106.7 Bq/dm3. The largest number of radon concentrations found in the Sudetic groundwaters ranged between ca. 3-6 and 1000 Bq/dm3. The values over 1000 Bq/dm3 can be considered anomalously high. They constitute 3.9% of all the results and occur around six localities within different geological units of the Sudety Mountains. These are shallow circulation, low mineralised groundwaters, which outflow from gneisses and granites. In the face of the fact that from 12.8% to 72.7% (depending on the adopted norm of maximum radon concentration for drinking waters) of the examined waters cannot be drunk directly without removing at least part of the radon, and in the face of the possibility of recognizing as many as 63.5% of the waters as potentially medicinal, extensive research of radon geochemistry in the Sudety Mountains area should be urgently undertaken.  相似文献   
42.
The aim of this work was to make a comparison of indoor radon concentrations in dwellings and in soil air in the area of two geological formations in the Suwa?ki region (Poland). The mean arithmetic airborne concentration was found to be the highest (301 Bq m (-3)) in the basements of buildings in the gravel and sand areas, whereas in the boulder clay areas it reached 587 Bq m (-3). Out of 54 measurements of radon concentrations performed at the ground floor, in eight cases concentrations were found to exceed 200 Bq m (-3) - permissible radon level in new-built houses in Poland and in three cases these values were even higher than 400 Bq m (-3). The highest radon levels were noted in houses with earthen basement floors and with direct entrance from the basement to rooms or kitchens. The mean arithmetic radon concentration in the soil air in the sandy and gravel formations was 39.7 kBq m (-3) and in clay formation it was 26.5 kBq m (-3). Higher radon levels were also found in the water obtained from household wells reaching 8367 Bq m (-3) as compared with tap water (2690 Bqm (-3)). The mean indoor concentration for the whole area under study was found to be 169.4 Bq m (-3), which is higher than the mean value for Poland (49.1 Bq m (-3)) by a factor of 3.5.  相似文献   
43.
Congenital heart defects (CHDs) are associated with neurodevelopmental (ND) delay. This study aims to assess evidence for impaired prenatal brain development, in fetuses with CHD. A systematical search was performed, and 34 studies evaluating the fetal brain [magnetic resonance imaging (MRI) or ultrasound] in isolated CHD were included (1990–2015). Data regarding cerebral abnormalities, head circumference growth and middle cerebral artery flow were extracted. Prenatal MRI was studied in ten articles (445 fetuses), resulting in a pooled prevalence of 18% (95%CI −6%; 42%) for combined structural and acquired cerebral abnormalities. Prenatal head circumference was studied in 13 articles (753 fetuses), resulting in a pooled z-score of −0.51 (95%CI −0.84; −0.18). Doppler was studied in 21 articles (1412 fetuses), resulting in a lower middle cerebral artery pulsatility index (z-score −0.70 95%CI −0.99; −0.41) in left-sided CHD only. We conclude that prenatal MRI and ultrasound demonstrate brain abnormalities, delay in head growth and brainsparing in subgroups of CHD. However, large MRI studies are scarce, and ultrasound data are biased towards severe and left-sided CHD. Long-term follow-up studies correlating prenatal findings with postnatal ND outcome are limited, and data are lacking to support counseling families regarding ND outcome based on prenatal findings suggestive of altered brain development. © 2016 John Wiley & Sons, Ltd.  相似文献   
44.
Hydrogen sulfide adsorption and oxidation by corroding concrete surfaces at different air-flows were quantified using a pilot-scale sewer reactor. The setup was installed in an underground sewer research station with direct access to wastewater. Hydrogen sulfide gas was injected into the headspace of the sewer reactor once per hour in peak concentrations of approximately 500 ppmv. The investigated range of sewer air-flows was representative for natural ventilated sewer systems, and covered both laminar and turbulent conditions. The experiments demonstrated a significant effect of sewer air-flow on the kinetics of hydrogen sulfide removal from the sewer headspace. From the lowest to the highest air-flow investigated, the rate of adsorption and oxidation increased more than threefold. At all air-flows, the reaction kinetics followed a simple n-th order rate equation with a reaction order of 0.8. The effect of air-flow on hydrogen sulfide adsorption and oxidation kinetics was quantified by a simple empirical equation.  相似文献   
45.
A widely accepted paradigm in mammalian behavioral biology is that exposure to unfamiliar males causes pregnancy disruption in female rodents (commonly known as the Bruce effect). This behavioral phenomenon has been demonstrated in the laboratory with at least 12 species of rodents, primarily within the genus Microtus, and is supposedly an adaptation that provides male perpetrators with reproductive access to females, and functions, for females, as a counterstrategy to infanticide. However, neither the Bruce effect nor its adaptive significance have been tested experimentally in the field. In a controlled field study, we exposed reproducing female gray-tailed voles (Microtus canicaudus) to treatments in which males were removed and replaced by either unfamiliar males or females, and found no significant differences in intervals between parturitions, number of pregnancies, and juvenile recruitment among the treatment and control animals. Thus, we conclude that neither the Bruce effect nor infanticide occurred differentially as a consequence of the treatments in gray-tailed voles. Multimale mating to confuse paternity, and postpartum estrus resulting in simultaneous pregnancy and lactation may deter infanticide and functionally negate any benefits of pregnancy disruption in gray-tailed voles and perhaps other murid rodents with similar mating systems. In light of our results, we recommend field verification for other species of murid rodents that exhibit the Bruce effect in the laboratory before the results are applied to evolutionary theory. Received: 12 May 1998 / Accepted after revision: 6 September 1998  相似文献   
46.
47.
The water disinfecting behavior of silver-modified clinoptilolite–heulandite rich tuff (ZSAg) as an antibacterial agent against coliform microorganisms from water in a continuous mode was investigated. Silver recovery from the disinfected effluents by the sodium-modified clinoptilolite–heulandite rich tuff (ZSNa) was also considered. Escherichia coli (ATCC 8739) and total coliform microorganisms, as indicators of microbiological contamination of water, were chosen to achieve the disinfection of synthetic wastewater or municipal wastewater. Ammonium (NH4+) and chloride (Cl) ions were added to the synthetic wastewater as an interfering chemical species on the disinfection processes. The antibacterial activity of the ZSAg as a bactericide was measured by the coliform concentration as evaluated by the APHA method. The amount of silver in the disinfected effluents was determined using atomic absorption spectroscopy. The inactivation of the ZSAg was calculated from the breakthrough curves based on the model reported by Gupta et al. It was found that when the silver concentration in the effluent is less than 0.6 μg/mL, the bacterial survival percentage increased and the volume of disinfected water diminished. The total silver amounts found in the effluent at the end of the disinfection processes varied depending on the water treated (synthetic or municipal wastewater). The presence of NH4+ ions in synthetic wastewater influent notably improved the disinfected water volume (zero NVC/100 mL), in comparison to the disinfection of the same influent without NH4+ ions. A contrary water disinfection behavior was observed in the presence of Cl ions. The silver recovery does not depend on the mass of the sodium zeolitic bed according with the wastewater to be treated (synthetic or municipal wastewater) and the presence of NH4+ or Cl ions in the influent also influenced the silver recovery from wastewater. The ZSNa did not have antibacterial activity. Therefore the amount of bactericide agent (silver-modified natural zeolite), coliform microorganisms from water (E. coli or consort of coliform microorganisms) as well as the water quality (synthetic wastewater or municipal wastewater) influenced both the disinfection process and the silver recovery in a column system.  相似文献   
48.
49.
The European Water Framework Directive (WFD) establishes a framework for the protection of estuarine and coastal waters, with the most important objective being to achieve 'good ecological status' for all waters, by 2015. Hence, Member States are establishing programmes for the monitoring of water quality status, through the assessment of ecological and chemical elements. These monitoring programmes can be of three types: surveillance monitoring; operational monitoring (both undertaken on a routine basis); and investigative monitoring (carried out where the reason of any exceedance for ecological and chemical status is unknown). Until now, nothing has been developed in relation to investigative monitoring and no clear guidance exists for this type of monitoring, as it must be tackled on a 'case-by-case' basis. Consequently, the present study uses slag disposal from a blast furnace, into a coastal area, as a case-study in the implementation of investigative monitoring, according to the WFD.In order to investigate the potential threat of such slags, this contribution includes: a geophysical study, to determine the extent of the disposal area; sediment analysis; a chemical metal analysis; and an ecotoxicological study (including a Microtox test and an amphipod bioassay). The results show that metal concentrations are several times above the background concentration. However, only one of the stations showed toxicity after acute toxicological tests, with the benthic communities being in a good status. The approaches used here show that contaminants are not bioavailable and that no management actions are required with the slags.  相似文献   
50.
Santiago, Chile has the distinction of having among the worst urban air pollution problems in Latin America. As part of an atmospheric pollution reduction plan, the Santiago Regional Metropolitan government defined an environmental policy goal of using urban forests to remove particulate matter less than 10 microm (PM(10)) in the Gran Santiago area. We used cost effectiveness, or the process of establishing costs and selecting least cost alternatives for obtaining a defined policy goal of PM(10) removal, to analyze this policy goal. For this study, we quantified PM(10) removal by Santiago's urban forests based on socioeconomic strata and using field and real-time pollution and climate data via a dry deposition urban forest effects model. Municipal urban forest management costs were estimated using management cost surveys and Chilean Ministry of Planning and Cooperation documents. Results indicate that managing municipal urban forests (trees, shrubs, and grass whose management is under the jurisdiction of Santiago's 36 municipalities) to remove PM(10) was a cost-effective policy for abating PM(10) based on criteria set by the World Bank. In addition, we compared the cost effectiveness of managing municipal urban forests and street trees to other control policies (e.g. alternative fuels) to abate PM(10) in Santiago and determined that municipal urban forest management efficiency was similar to these other air quality improvement measures.  相似文献   
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