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921.
922.
This investigation represents the first environmental diagnosis of the distribution and sources of polycyclic aromatic hydrocarbons (PAHs) in sediments from a tropical mangrove in Fortaleza, northeastern Brazil. Sediment cores from six sampling stations in the Cocó and Ceará Rivers were retrieved in June-July 2006 to determine 17 priority PAHs. The total PAH concentrations (ΣPAHs) ranged from 3.04 to 2234.76 μg kg?1(Cocó River) and from 3.34 to 1859.21 μg kg?1 (Ceará River). These levels are higher than those of other cities with more industrial development. PAH concentrations did not reach probable effect levels (PELs). However, from 4.5 to 87.5% of individual PAH concentrations can occasionally cause adverse biological effects for aquatic organisms. The PAH molecular ratios indicate that the PAHs in the sediment core were derived mainly from petroleum, wood, and charcoal combustion (pyrogenic source), and that atmospheric deposition and urban runoff may serve as important pathways for PAH input to the sediment. Clearly, the ΣPAHs in sediments collected in the Cocó and Ceará Rivers indicate that ongoing pollution is more severe than past pollution.  相似文献   
923.
924.
Large (>90%) for gestational age (LGA) fetuses are usually identified incidentally. Detection of the LGA fetus should first prompt the provider to rule out incorrect dates and maternal diabetes. Once this is done, consideration should be given to certain overgrowth syndromes, especially if anomalies are present. The overgrowth syndromes have significant clinical and molecular overlap, and are associated with developmental delay, tumors, and other anomalies. Although genetic causes of overgrowth are considered postnatally, they are infrequently diagnosed prenatally. Here, we review prenatal sonographic findings in fetal overgrowth syndromes, including Pallister-Killian, Beckwith-Wiedemann, Sotos, Perlman, and Simpson-Golabi-Behmel. We also discuss prenatal diagnosis options and recurrence risks. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   
925.
The hypothesis of this research was that attitudes about the management of biodegradable municipal waste (BMW) are spatially variable, even within a city of modest (1.2 million) population. For a select number of representative electoral districts in the Dublin, Ireland region, residents were surveyed regarding attitudes towards waste management in general, and BMW management in particular. A total of 850 survey responses were collected. Door-to-door interviews produced 688 responses in the residential sector; these were supplemented by 162 responses to a web-based survey.The surveys revealed that the majority of households use local authority, rather than private, waste collection services (both are available). The majority of residents, regardless of the local authority in which they live, were satisfied with their waste management service. “Reducing the quantity of waste generated” was regarded the most important future issue for 28% of residential respondents. Statistical analyses of the survey responses showed that the local authority in which respondents resided significantly influenced most responses (including waste collection service used, waste service satisfaction and backyard composting activity). Many responses (including waste service satisfaction, waste management influences) were also significantly related to the respondents’ personal characteristics (e.g., education level, type of accommodation, age, etc.). These statistical results proved the hypothesis of the research and demonstrated that waste management initiatives designed for one area of the city (or, indeed, for uniform application to the city as a whole) could ignore the needs of other areas. The survey responses suggest that targeted intervention strategies would lead to improved diversion rates of BMW from landfill, a requirement of the Landfill Directive 1999/31/EC.  相似文献   
926.
This paper investigates the changes of mineralogical composition of bottom ash in the environment. The chemical and mineralogical bulk composition was determined by X-ray fluorescence (XRF) and X-ray powder diffraction (XRPD) Rietveld method. Single bottom ash particles were investigated by optical microscopy, scanning electron microscopy with quantitative energy-dispersive X-ray microanalysis (SEM/EDX) and electron probe micro analysis (EPMA). SEM/EDX and EPMA are valuable complement to bulk analysis and provide means for rapid and sensitive multi-elemental analysis of ash particles. The fresh bottom ash consists of amorphous (>30 wt.%) and major crystalline phases (>1 wt.%) such as silicates, oxides and carbonates. The mineral assemblage of the fresh bottom ash is clearly unstable and an aging process occurs by reaction towards an equilibrium mineral phase composition in the environmental conditions. The significant decrease of anhydrite and amorphous contents was observed in the aged bottom ash, leading to the formation of ettringite, hydrocalumite and rosenhahnite under atmospheric conditions. In the water-treated sample, the calcite contents increased significantly, but ettringite was altered by the dissolution and precipitation processes in part, to produce gypsum, while the remaining part reacted with chloride to form hydrocalumite. Gypsum and other Ca based minerals may take up substantial amounts of heavy metals and subsequently control leaching behaviour of bottom ash.  相似文献   
927.
The present study investigated the contribution of environmental factors to the accumulation of As, Cd, Cu, Pb and Zn in earthworms, beetles and woodlice, and framed within an exposure assessment of the European hedgehog. Soil and invertebrate samples were collected in three distinct habitat types. Results showed habitat-specific differences in soil and invertebrate metal concentrations and bioaccumulation factors when normalized to soil metal concentration. Further multiple regression analysis showed residual variability (habitat differences) in bioaccumulation that could not be fully explained by differences in soil metal contamination, pH or organic carbon (OC). Therefore, the study demonstrated that in bioaccumulation studies involving terrestrial invertebrates or in risk assessment of metals, it is not sufficient to differentiate habitat types on general soil characteristics such as pH and/or OC alone. Furthermore, simple generic soil risk assessments for Cd and Cu showed that risk characterization was more accurate when performed in a habitat-specific way.  相似文献   
928.
ABSTRACT: A methodology for ground water remediation design has been developed that interfaces ground water simulation models with an enhanced annealing optimizer. The ground water flow and transport simulators provide the ability to consider site‐specific contamination and geohydrologic conditions directly in the assessment of alternative remediation system designs. The optimizer facilitates analysis of tradeoffs between technical, environmental, regulatory, and financial risks for alternative design and operation scenarios. A ground water management model using an optimization method referred to as “enhanced annealing” (simulated annealing enhanced to include “directional search” and “memory” mechanisms) has been developed and successfully applied to an actual restoration problem. The demonstration site is the contaminated unconfined aquifer referred to as N‐Springs located at Han‐ford, Washington. Results of the demonstration show the potential for improving groundwater restoration system performance while reducing overall system cost.  相似文献   
929.
930.
Abstract

The October 1995 court decision allowing Ethyl Corporation to offer methylcyclopentadienyl manganese tricarbonyl (MMT) for sale to refiners for introduction into unleaded gasoline as an octane enhancer is likely to result in increased fine (PM2.5) manganese (Mn) concentrations in ambient air. Concern exists regarding possible health effects. In this paper, recent fine Mn concentrations in three monitoring networks and one U.S. Environmental Protection Agency (EPA) study of personal exposure are analyzed. One network consists mainly of rural sites in national parks in the United States, a second consists mainly of urban sites in California, and the third consists mainly of urban sites in Canada where MMT has been used for a number of years. During the late 1980s and early 1990s, mean ambient concentrations ranged from 1 ng/m3 in the mostly rural network to 3 ng/m3 in the mostly urban California network to 12 ng/m3 in the MMT-impacted Canadian network. Several lines of evidence suggested that some of the fine Mn observed in the United States during the 1986-1992 period was contributed by automobiles using leaded gasoline, for which MMT was a registered fuel additive. However, the near-disappearance of leaded gasoline has resulted in a very small portion of fine Mn being attributed to automobiles in the years since 1992.A source apportionment analysis suggested that crustal contributions to ambient fine Mn are on the order of 1-2 ng/m3 in both the United States and Canada.  相似文献   
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