Prenatal application of fluorescent in situ hybridization (FISH) for identification of a mosaic Y-chromosome marker,IDIC(Yp)

An amniocentesis was performed at 13.3 weeks' gestation for advanced maternal age. A mosaic sex chromosome pattern was found: of 50 cells examined, 34 had a 45,X karyotype. In 14 cells with a modal number of 46, a recognizable Y was substituted by a small non-fluorescent marker. C-banding identified the marker as an isodicentric in 12 cells. In two cells, the non-fluorescent marker appeared to be monocentric and looked like a non-fluorescent del (Yq), but could have been an isodicentric Y with inactivation of one of the centromeres. Two cells with a modal number of 47 showed two copies of the monocentric marker. Fluorescent in situ hybridization with an alpha satellite Y-specific centromeric probe confirmed the Y-chromosome origin of the markers and allowed for more accurate prenatal diagnostic information.     

Can we trust odor databases? Example of t- and n-butyl acetate

The US EPA has exempted t-butyl acetate from VOC regulations, which increases the likelihood that it may replace other solvents in some settings. This investigation probes its chemosensory properties. In Study 1, subjects (n = 29) sought to detect the odor of t-butyl acetate and of n-butyl acetate in forced-choice testing of stable concentrations, analytically confirmed. Subjects sniffed from cones with a high enough volumetric flow to insure against dilution by nonodorized air. A subject made hundreds of judgments, enough for a psychometric function for each material. The points of 50% detection above chance (“threshold”) occurred at 8 and 2 ppb for t-butyl acetate and n-butyl acetate, respectively. In study 2, subjects (n = 26) sought to detect vapor with the eye via chemesthesis (sensory irritation) in 10-s exposures. Detection at 50% occurred at 177 and 113 ppm for t-butyl acetate and n-butyl acetate, respectively, more than 10,000 times above that for odor detection. The protocols produced results of uncommon precision compared to those in often-misleading archival databases. The nose exhibits much higher sensitivity than the databases indicate. The collections rarely exhibit accuracy better than ±1000%. Collection of accurate data for a VOC can ironically bring on stricter regulation for just it, a situation that calls for a strategy to improve the database by collection of new data, importation of better data, and development of quantitative structure–activity modeling.     

Annual occurrence,abundance and diversity of fish in a South Carolina intertidal creek

An intertidal creek in North Inlet Estuary, South Carolina, USA, was sampled monthly for 1 year to determine the occurrence, abundance and diversity of fish species. Sampling was so conducted as to reduce sampling bias to a minimum and all individuals caught were weighed and measured. A total of 16,611 individuals weighing 202.45 kg and comprising 51 species and 25 families of fish was collected. Three diversity indices were calculated for species number. Analysis of variance revealed that season had a highly significant effect on all indices and the number of species, but had no effect on the number of individuals caught.This work was supported by the Belle W. Baruch Foundation and the South Carolina State Development Board, and is Contribution No. 71 of the Belle W. Baruch Institute for Marine Biology and Coastal Research.     

A New Method to Assess Mercury Emissions: A Study of Three Coal-Fired Electric-Generating Power Station Configurations

Abstract

U.S. Environmental Protection Agency (EPA) Method 7473 for the analysis of mercury (Hg) by thermal decomposition, amalgamation, and atomic absorption spectroscopy has proved successful for use in Hg assessment at coal-fired power stations. In an analysis time of ～5 min per sample, this instrumental methodology can directly analyze total Hg—with no discrete sample preparation—in the solid matrices associated with a coal-fired power plant, including coal, fly ash, bottom ash, and flue gas desulfurization (FGD) material. This analysis technique was used to investigate Hg capture by coal combustion byproducts (CCBs) in three different coal-fired power plant configurations. Hg capture and associated emissions were estimated by partial mass balance. The station equipped with an FGD system demonstrated 68% capture on FGD material and an emissions estimate of 18% (11 kg/yr) of total Hg input. The power plant equipped with low oxides of nitrogen burners and an electrostatic precipitator (ESP) retained 43% on the fly ash and emitted 57% (51 kg/yr). The station equipped with conventional burners and an ESP retained less than 1% on the fly ash, emitting an estimated 99% (88 kg/yr) of Hg. Estimated Hg emissions demonstrate good agreement with EPA data for the power stations investigated.     

Use of tracer tests to evaluate the impact of enhanced-solubilization flushing on in-situ biodegradation

Tracer tests were conducted to evaluate the effect of a complexing sugar flush (CSF) on in-situ biodegradation potential at a site contaminated by jet fuel, solvents, and other organic compounds. Technical-grade hydroxypropyl-beta-cyclodextrin was used during the CSF study, which was conducted in a hydraulically isolated cell emplaced in a surficial aquifer. In-situ biodegradation potential was assessed with the use of tracer tests, which were conducted prior to and immediately following the CSF study. Ethanol, hexanol, and benzoate were used as the biodegradable tracers, while bromide was used as a nonreactive tracer. The results indicate that the biodegradation of benzoate was similar for both tracer tests. Conversely, the biodegradation of ethanol (23% increase) and hexanol (41% increase) was greater for the post-CSF tracer test. In addition, analysis of core samples collected from within the test cell indicates that the population density of aerobic jet-fuel degraders increased in the vicinity of the injection wells during the CSF. These results indicate that the cyclodextrin flush did not deleteriously affect the indigenous microbial community. This study illustrates that tracer tests can be used to evaluate the impact of remediation activities on in-situ biodegradation potential.     

Carbon-14, tree rings,and urban air pollution

Differences in natural ¹⁴C content of rings from trees from urban and rural locations have been compared on a year by year basis. The differences as a fraction of the urban tree's radioactivity reflect the local excess ¹⁴C-free carbon dioxide from fossil fuel combustion in the urban environment. New York City, Boston, and Washington, D.C., show different degrees of excess carbon dioxide. New York City averages about 6% excess carbon dioxide between 1950 and 1970. From this is infered an average carbon monoxide concentration during this period of 5 ppm.