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101.
Environmental Science and Pollution Research - A Correction to this paper has been published: https://doi.org/10.1007/s11356-021-12759-3  相似文献   
102.
Hexanitrohexaazaisowurtzitane (CL-20) is an emerging explosive that may replace the currently used explosives such as RDX and HMX, but little is known about its fate in soil. The present study was conducted to determine degradation products of CL-20 in two sandy soils under abiotic and biotic anaerobic conditions. Biotic degradation was prevalent in the slightly acidic VT soil, which contained a greater organic C content, while the slightly alkaline SAC soil favored hydrolysis. CL-20 degradation was accompanied by the formation of formate, glyoxal, nitrite, ammonium, and nitrous oxide. Biotic degradation of CL-20 occurred through the formation of its denitrohydrogenated derivative (m/z 393 Da) while hydrolysis occurred through the formation of a ring cleavage product (m/z 156 Da) that was tentatively identified as CH2N-C(N-NO2)-CHN-CHO or its isomer N(NO2)CH-CHN-CO-CHNH. Due to their chemical specificity, these two intermediates may be considered as markers of in situ attenuation of CL-20 in soil.  相似文献   
103.
Salt marsh vegetation change in response to tidal restriction   总被引:4,自引:0,他引:4  
Vegetation change in response to restriction of the normal tidal prism of six Connecticut salt marshes is documented. Tidal flow at the study sites was restricted with tide gates and associated causeways and dikes for purposes of flood protection, mosquito control, and/or salt hay farming. One study site has been under a regime of reduced tidal flow since colonial times, while the duration of restriction at the other sites ranges from less than ten years to several decades. The data indicate that with tidal restriction there is a substantial reduction in soil water salinity, lowering of the water table level, as well as a relative drop in the marsh surface elevation. These factors are considered to favor the establishment and spread ofPhragmites australis (common reed grass) and other less salt-tolerant species, with an attendant loss ofSpartina-dominated marsh. Based on detailed vegetation mapping of the study sites, a generalized scheme is presented to describe the sequence of vegetation change from typicalSpartina- toPhragmites-dominated marshes. The restoration of thesePhragmites systems is feasible following the reintroduction of tidal flow. At several sites dominated byPhragmites, tidal flow was reintroduced after two decades of continuous restriction, resulting in a marked reduction inPhragmites height and the reestablishment of typical salt marsh vegetation along creekbanks. It is suggested that large-scale restoration efforts be initiated in order that these degraded systems once again assume their roles within the salt marsh-estuarine ecosystem.  相似文献   
104.
The Jarcho–Levin syndrome is a specific form of spondylocostal/spondylothoracic dysostosis. There have been various classifications of this syndrome. We present the case of a severe prenatal Jarcho–Levin syndrome, diagnosed by ultrasound examination during the first trimester of pregnancy in a family with no previous medical history of an affected child. X-ray exploration, high-resolution spiral computed tomography and autopsy confirmed the diagnosis. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   
105.
In 2003, concentrations of altogether 17 PCDD/Fs congeners and 12 non-ortho and mono-ortho dioxin-like PCBs were measured in the blood of 60 randomly selected adults who lived in three settlements surrounding a chemical plant that had been producing chlorinated herbicides (mainly HCHs, HCB, pentachlorophenole, 2,4,5-T) in the 1960's; subjects consuming home-produced animal foods were chosen. Twenty blood donors with similar characteristics from the locality with about 80 km distance were used as control subjects. The factors that influenced the dioxin levels were investigated on the basis of a questionnaire. The aim of our study was to find out whether the residents living in the surroundings of the chemical plant are at a greater exposure risk than the controls. To calculate TEQ values, WHO-TEFs were used. The concentrations of four PCDD and six PCDF congeners were below the LOD in more than 50% of samples. Significantly higher WHO-TEQ levels (p<0.05) were found for PCDDs, PCDFs, or PCBs in all three followed up groups compared with controls. The geometric means of the total TEQ values for PCDD/F/PCBs were 43.8, 50.2, and 40.0 pg/g fat compared to 23.2 pg/g fat in the control. The percentages of TEQ due to the measured congeners in exposed groups were 9-10.3% for PCDDs, 20.5-26.9% for PCDFs, 19.2-23.1% for coplanar and 43.6-47.2% for mono-ortho PCBs. In control, the percentage of TEQ was 11.6, 26.7, 24.1, and 37.5%. PCBs, predominantly PCB156, followed by PCB126 contributed 60 to 70% of the total TEQ value. Positive correlation of the PCDD/PCDF/PCB blood levels with age and with consumption of locally produced eggs was found.  相似文献   
106.
The alligator snapping turtle (  Macroclemys temminckii ) is a long-lived, slow-growing chelydrid turtle found in Gulf of Mexico drainages from Florida to Texas (U.S.A.). Populations are thought to be depleted throughout the range due in part to an increased harvest in the 1960s through 1980s. To identify population and evolutionary units, 420 base pairs were sequenced within the mitochondrial DNA control region of 158 specimens from 12 drainages. Results indicate substantial phylogeographic structuring and strong population-level separations among river drainages. Eight of 11 haplotypes were observed to be river-specific, providing diagnostic markers for most drainages. Three partitions are resolved in the mtDNA genealogy, corresponding to the eastern, central, and western portion of the species' range. These separations coincide with recognized biogeographic provinces. The population structure by river system indicates that many drainages are distinct management units, with the Suwannee River lineage possibly deserving special attention, based on the criterion of genetic distinctiveness. The partitioning of M. temminckii into river-specific populations illustrates the management framework and conservation challenges that apply to a broad array of riverine species. Drainage-specific molecular markers may be used to identify the geographic origin of turtle products in the marketplace.  相似文献   
107.
108.
An Erratum has been published for this article in Prenatal Diagnosis 22(13) 2002, 1241. Fibrochondrogenesis is a rare and lethal osteochondrodysplasia with an autosomal recessive mode of inheritance. We report a male fetus in which the diagnosis of lethal osteochondrodysplasia was suspected on prenatal ultrasound and radiological examinations during the second trimester of pregnancy. After termination of pregnancy, fibrochondrogenesis was diagnosed by radiological examination and histological study of fetal bones. Interwoven fibrous septa and fibroblastic degeneration of chondrocytes are pathognomonic. The recurrence rate is 25% and accurate diagnosis is necessary to enable genetic counselling. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   
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