Unburned coal as a source of hydrocarbons in surface sediments

The isolation and quantification of the various sources of trace levels of hydrocarbons in environmental samples is a difficult analytical task. Based on the hydrocarbon concentrations found in non-polluted surface sediment and an estimate of the amounts of coal particles found in similar areas we conclude that unburned coal can be a significant source of sediment hydrocarbons in the coastal marine environment.     

The 1974 spill of the Bouchard 65 oil barge: petroleum hydrocarbons persist in Winsor Cove salt marsh sediments

Petroleum hydrocarbons persist in salt marsh sediments in Winsor Cove (Buzzards Bay, Massachusetts) impacted from the 1974 spill of No. 2 fuel oil by the barge Bouchard 65. Intertidal sediment cores were collected from 2001 to 2005 and analyzed for total petroleum hydrocarbons (TPHs). TPHs content was greatest (as high as 8.7 mg g(-1) dry weight) in the surface sediments and decreased with distance landward. Select samples were analyzed for polycyclic aromatic hydrocarbons (PAHs) with values as high as 16.7 microg g(-1) for total naphthalenes and phenanthrenes/anthracenes. These remaining PAHs are mainly C(4)-naphthalenes and C(1)-, C(2)-, and C(3)-phenanthrenes/anthracenes revealing preferential loss of almost all of the naphthalenes and the parent compound phenanthrene. Inspection of the data indicates that biodegradation, water-washing and evaporation were major removal processes for many of the petroleum hydrocarbons in the marsh sediments. In addition, historical data and photographs combined with their recent counterparts indicate that erosion has physically removed these contaminants from this site.     

An Evaluation of Tertiary-Butyl Alcohol for the Development of a Drinking Water Action Level in Delaware

For regulators to develop risk-based screening levels (RBSLs) for a petroleum constituent, a maximum allowable concentration at an exposure point, such as a drinking water action level, must be established. Of particular interest to regulators of leaking underground storage tank (LUST) sites in Delaware is the development of RBSLs for the oxygenated compounds that are added to gasoline to increase octane rating and promote cleaner burning fuel. Whereas methyl-tertiary butyl ether (MTBE) became the first of the oxygenated compounds to gain regulatory attention in Delaware, tertiary-butyl alcohol (TBA) is not far behind. TBA has been detected at LUST sites throughout Delaware and in some cases has been detected in private water supplies. However, Delaware does not currently have a drinking water action level, or maximum allowable exposure concentration, on which to base regulatory decisions regarding TBA.
Toxicological data is inconclusive in classifying TBA as a carcinogen. However, carcinogenic responses are reported in rat and mice studies at extremely high doses. To address TBA in Delaware's Risk-Based Corrective Action Program, the Delaware Division of Public Health must calculate drinking water action levels based on the results of the toxicological data. However, the establishment of TBA action levels could have a tremendous impact on the costs associated with investigating and remediating a LUST site. TBA may add $2000 to $5000 per year in analytical costs alone for an average LUST site in Delaware.     

Intervening O vi Quasar Absorption Systems at Low Redshift: A Significant Baryon Reservoir

Far-UV echelle spectroscopy of the radio-quiet QSO H1821+643 (zem=0.297), obtained with the Space Telescope Imaging Spectrograph (STIS) at approximately 7 km s-1 resolution, reveals four definite O vi absorption-line systems and one probable O vi absorber at 0.15相似文献   

Tag loss and movement of stocked yearling rainbow trout (Oncorhynchus mykiss) in southwestern Australia

Rainbow trout, Oncorhynchus mykiss, have been stocked in southwestern Australia since the 1930s. Trials at a research station maintained 868 tagged yearling O. mykiss (age: 14 months; standard length: 208 mm) for up to 375 days. The mean tag loss rate was 0.12% ± 0.040% per day for both single- and double-tagged fish. The tag loss rate was used to interpret tag return data from 7030 single-tagged yearlings stocked into three river systems in southwestern Australia. Recaptures indicated that O. mykiss survived into their second season in all rivers, with the maximum time at liberty of 21 months (longevity of at least 35 months). Upstream and downstream movements of O. mykiss increased with time, although 29% of recaptures were reported from the stocking site. Significantly more O. mykiss were recaptured from the Warren River, and differences remained even when corrected for stocking levels; angler effort had a marginal effect on return rates. Higher return rates from the Warren River may be due to availability of suitable habitat (stream cover, cooler water) for O. mykiss. Results allow the stocking regime to be reviewed to improve fishery performance.