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Query: UMLS:C1835664 (TOC)
 2,763 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The Mutatox test has been developed by Microbics Corp., U.S.A., in addition to the widely used acute toxicity test Microtox. The Mutatox test indicates the presence of any material in a test sample that causes genetic damage to dark variants of the luminescent bacteria Vibrio fischeri. As the Microtox test is less time-consuming and more cost-effective than the Mutatox test, the possibility of using the EC50 measured by Microtox for range-finding of genotoxic concentrations for the Mutatox test was examined. Both tests were applied on single compounds and several waste elutriates. The genotoxic potential of two PAH metabolites--1-hydroxypyrene and 9-fluorenone-1-carboxylic acid--was detected. According to the present results the highest concentration of a sample in the Mutatox test should in general exceed the EC50 by about 5-10 times. Elutriates were submitted to analyses of TOC, heavy metals, phenols, and PAH; additionally GC/MS screening analyses were carried out. In most cases correlations of ecotoxicological effects with single contaminants were not possible, but it can be assumed that these effects were produced by the interaction of inorganic and organic compounds present in the elutriates.
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PMID:Comparison of acute toxicity and genotoxic concentrations of single compounds and waste elutriates using the Microtox/Mutatox test system. 946 73

Various herbaceous biofuels (straw, whole plant cereals and set aside hay) and spruce wood were tested for their potential to form PCDD/F, PCPh, PCBz and PAH during combustion. The trials were conducted in an automatically charged multi-fuel furnace for domestic applications (50 kWth). Both, flue gas and the different ash fractions were analysed. CO-emission results show, that combustion conditions were relatively uniform (mean CO-level: 200 mg/m3 at 13% O2 in flue gas). Likewise, the TOC- and PAH-emissions in the fuel gas remained constantly on a relatively low level. However, for the PCDD/F, PCPh and PCBz increased emissions were detected when herbacious fuels were applied. This may be attributed to their higher chlorine concentration and the high ash content, which is responsible for increased dust emissions during combustion. Similar observations were also found for the PCDD/F-concentrations in the ashes. Combustion chamber ashes usually showed a drastically reduced contamination with highly toxical compounds, compared to the ash fraction from the heat exchanger ash or to chimney soot.
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PMID:Investigation on organic pollutants from a domestic heating system using various solid biofuels. 1073 57

Juvenile Nereis (Neanthes) arenaceodentata survival and growth were used to evaluate the effect of storage time on the toxicity of sediments with moderate PAH and metal contamination. Seven San Francisco Bay area sediments and a clean control sediment were stored (4 degrees C) and then periodically evaluated (up to two years after collection). During each test, juvenile worms (2-3 weeks post emergence) were exposed for 21 days. Test endpoints were survival and growth rate (mg dry weight/day). In general, survival was high (>75%) and long-term cold storage (740 days) did not significantly alter growth or survival. In half of the sediments a cyclical phenomenon was observed associated with the appearance of ammonia in the overlying water of bioassay beakers. The periodicity of this phenomenon was approximately one year. It was not associated with any geophysical characteristic of the test sediments (i.e. grain size, % TOC, % TKN). Significant mortality (0% survival on day 427) was associated with the largest of these peaks in overlying water ammonia concentration. Results of this study suggest that ammonia in stored sediments is an important, potentially confounding factor in sediment toxicity tests.
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PMID:Long-term storage of sediments: Implications for sediment toxicity testing. 1509 27

In this study the levels and distribution of some persistent toxic substances (PTS) were investigated in soils, superficial water, and snow along an altitudinal gradient in the Laja River Basin (South Central Chile). The principal objective was to establish the basin's contamination status. The working hypothesis was that PTS levels and distribution in the basin are dependent on the degree of anthropogenic intervention. Fifteen PAHs, seven PCBs congeners, and three organochlorine pesticides were studied in superficial soil and water samples obtained along the altitudinal gradient and from a coastal reference station (Lleu-Lleu River). Soil samples were extracted using accelerated solvent extraction with acetone/cyclohexane (1:1) for PAHs and organochlorine compounds. Contaminants were extracted from water and snow samples by liquid-liquid extraction (LLE). PAH and organochlorine compound quantification was carried out by HPLC with fluorescence detection and GC-MS, respectively. PCBs in soils presented four different profiles in the altitudinal gradient, mainly determined by their chlorination degree; these profiles were not observed for the chlorinated pesticides. In general, the detected levels for the analyzed compounds were low for soils when compared with soil data from other remote areas of the world. Higher summation operator PAHs levels in soils were found in the station located at 227 masl (4243 ng g-1 TOC), in a forestry area and near a timber industry, where detected levels were up to eight times higher than the other sampling sites. In general, PAH levels and distribution seems to be dependent on local conditions. No pesticides were detected in surface waters. However, congeners of PCBs were detected in almost all sampling stations with the highest levels being found in Laja Lake waters, where 1.1 ng/l were observed. This concentration is two times higher than values reported for polluted lakes in the Northern Hemisphere. The presence of organochlorine compound in snow sampled at the highest elevation point of the basin is indicative of the transport and atmospheric deposition phenomena of alpha-HCH, gamma-HCH and PCB 52, with values being similar to the levels reported in Canadian snow samples. We conclude that environmental PTS substance levels are in general relatively low, although PAHs may be of concern in some areas of the basin.
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PMID:Persistent toxic substances in soils and waters along an altitudinal gradient in the Laja River Basin, Central Southern Chile. 1563 62

During a contamination survey in NE-Germany sediment cores were sampled at 5 locations with freeze-coring devices and conventional box-coring systems. In total more than 40 samples were analysed for several organic compounds (136 PCDD/F, 33 PCB, 39 PAH, 10 DDX, 4 HCH, 4 CB), sedimentological parameters (TOC,TC,TIC,LOI), some total trace metals (Pb,Cd,Cr,Cu,Zn) and dated by measurement of the (210)Pb and (137)Cs activity. The deepest segment of the cores from the Arkona Basin and the freshwater lakes were dated back to the end of the 19th century. A comparison of marine versus freshwater data is presented. The contamination levels of Arkona Basin were often lower than anthropogenically influenced freshwater sediments and more similar to a freshwater sediment core only influenced by deposition, with an additional Oder River inflow. Differences in patterns and contamination levels are discussed.
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PMID:Organic pollutants in sediment cores of NE-Germany: comparison of the marine Arkona Basin with freshwater sediments. 1612 37

Twenty-one varieties of sewage sludge from municipal, municipal-industrial and industrial areas were analysed for their suitability for agricultural purposes. The samples were taken from an agricultural area of Poland characterised by a low level of industrialisation. The sewage sludges were characterised for total organic carbon and nitrogen, pH, available phosphorous and potassium, cation exchange capacity, total exchangeable bases, the degree of base saturation, the total trace metals (such as Cd, Co, Ni, Pb, Cu, Mn, Zn, Sr, V, Cr) and the content of polycyclic aromatic hydrocarbons (16 PAHs from EPA list). The results showed that the studied sludges can potentially enhance soil's agronomic properties. However in a few cases, the pH, ratio of total organic carbon to total nitrogen (TOC/Nt) and electrical conductivity were the exceptions. Trace metal contents in the sewage sludge studied varied widely (statistical significant) as a result of the size of the sewage producing unit, and especially, the content of industrial sludge. The results obtained for PAHs in sewage sludge showed a clear differentiation in the content of PAHs, which ranged from 2,039 to 36,439 microg/kg. The predominant contribution of 3- and 4-ring PAHs was observed. In the case of 6 sewage sludges the PAH content twice exceeded the allowable value.
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PMID:Characterization of Polish sewage sludges with respect to fertility and suitability for land application. 1685 95

The coal tar found in contaminated soils of former manufactured gas plants and coking plants acts as a long-term source of PAHs. Organic carbon and PAH transfer from coal tar particles to water was investigated with closed-looped laboratory column experiments run at various particle sizes and temperatures. Two models were derived. The first one represented the extraction process at equilibrium and was based on a linear partitioning of TOC and PAHs between coal tar and water. The partition coefficient was derived as well as the mass of extractable organic matter in the particles. The second model dealt with mass transfer. Particle diffusion was the limiting step; organic matter diffusivity in the coal tar was then computed in the different conditions. A good consistency was obtained between experimental and computed results. Hence, the modeling of PAH migration in contaminated soils at the field scale requires taking into account coal tar as the source-term for PAH release.
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PMID:PAHs and organic matter partitioning and mass transfer from coal tar particles to water. 1705 97

A PAH contaminated river floodplain soil was separated according to grain size and density. Coal and coal-derived particles from coal mining, coal industry and coal transportation activities were identified by organic petrographic analysis in our samples. Distinct concentrations of PAHs were found in different grain size and density fractions, however, similar distribution patterns of PAHs indicated similar sources. In addition, although light fractions had the mass fraction by weight of less than 5%, they contributed almost 75% of the total PAHs in the soil. PAH concentrations of all sub fractions showed positive correlation with their TOC contents. Altogether, coal and coal-derived particles that were abundant in light fractions could be the dominant geosorbents for PAHs in our samples.
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PMID:Occurrence of coal and coal-derived particle-bound polycyclic aromatic hydrocarbons (PAHs) in a river floodplain soil. 1749 20

Organic petrographic analysis was applied to provide direct information on carbonaceous geosorbents for PAHs in river floodplain soils. The anthropogenic OM group (primarily coal and coal-derived particles) displayed large volume amounts for all the soil samples. Distinct PAH concentrations with similar PAH distribution patterns were determined in grain size and density fractions for each sample. Two-ring PAHs had stronger correlation to organic carbon (OC) than black carbon (BC) contents, while heavier PAHs showed correlation to BC, rather than OC. In this study, we combined grain size and density separation, PAH determinations, TOC and BC measurements, and organic petrographic identification, and concluded that two-ring PAHs in soils were associated to coal particles. Other heavier PAHs could be more controlled by black carbon (BC), which were mostly coal-derived particles from former coal mining and coal industrial activity.
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PMID:Identification of carbonaceous geosorbents for PAHs by organic petrography in river floodplain soils. 1828 May 35

The distribution of polycyclic aromatic hydrocarbons was determined in surface sediments collected at 36 stations along the Spanish Northern continental shelf in March and September 2003, and February 2005. Concentrations of PAHs (Sigma13 parent components) were in the range of 22-47528 mug/kg dw, the highest values corresponding to coastal urban-industrial hotspots and decreasing offshore. Sediment quality guidelines (SQGs) showed that concentrations of total PAHs were below the threshold effect level (TEC) in 27 stations (81%) and above in 7, two of which (Gijon and Bilbao) were above the probable effect concentration (PEC). The detailed study of diagnostic ratios suggested a rather uniform mixture of petrogenic and pyrolytic PAH sources along the continental shelf, with a slight decrease of the latter moving westwards and offshore. In order to assess the incidence of sediment sampling on the variability of the results, selected stations were also monitored in February and September 2004 and September 2005. The average field variance of the values obtained for each station was 31% that decreased to 23% when the values were normalized to TOC.
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PMID:Sources and distribution of polycyclic aromatic hydrocarbons in sediments from the Spanish northern continental shelf. Assessment of spatial and temporal trends. 2008 Mar 25


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