Abstract-Sediment studies around the diffuser of a relatively untreated major marine municipal sewage discharge indicated that 1,4-dichlorobenzene (1,4-DCB) and polycyclic aromatic hydrocarbons (PAHs) were among the contaminants of concern. Subsequent investigations revealed that elevated PAH concentrations were due to the shipwreck of a collier in the 1890s and were apparently not bioavailable. Coal is a common contaminant in marine and freshwater sediments and may be responsible, in some cases, for high PAH contaminant concentrations not resulting in pollution (i.e., biological effects) and can also affect total organic carbon measurements and normalizations. Little information exists regarding 1,4-DCB, whose main source to sewage appears to be toilet block deodorizers and which appears to be a useful marker of the extent of contamination for untreated sewage discharges. Correlative analyses suggest it is a pollutant, but this remains to be confirmed by experimental testing.
Assessments concerning the environmental impact of mining projects are highly dependent on reliable lowlevel analyses of samples collected from the receiving environment. The analytical program must be designed to maximize the reliability of the data and also provide infonnation concerning the reproducibility, accuracy, specificity, and sensitivity of test results. In Canada, the MEND (Mine Environment Neutral Drainage) Program has sponsored projects pertaining to comprehensive monitoring of subaqueous tailings disposal. Lake sediments, lake water, and interstitial water samples were collected and then analyzed for a host of parameters (metals, anions, physical tests, etc.). The analyses were carried out using state-of-the-art procedures and instruments. A comprehensive quality assurance-quality control (QA-QC) program was incorporated into the study with all QA-QC subsequently reported. The studies provide an ideal example of what is required, in tenns of analytical approach, for projects that require extremely low detection levels and are subject to rigorous scrutiny by regulatory agencies, the scientific community, and the public. This paper presents the QA-QC approach taken for the subaqueous tailings disposal work by discussing method selection, detennination of detection limits, use of reference materials, laboratory and field QC samples, and criteria for assessing QC results. Representative QC data are presented to demonstrate validation of methodology and to show that pre-detennined criteria were met. The results on all blanks were below limits of detection, the results on reference materials met suppliers 95% acceptance criteria and replicate results agreed to within± 15% of a calculated mean.
A number of comprehensive programs have been carried out to characterize oil refinery wastewaters with respect to specific organic and inorganic toxic chemicals. This paper provides some background on these studies which have shown that wastewater treatment systems at refinery sites are effective in reducing or removing toxic chemicals. Also presented is a discussion of analytical variability so readers can better appreciate the validity of results obtained from effluent monitoring programs. The variability associated with some chemical analyses, can be significant. Finally, a recommended approach towards routinely monitoring effluent quality and effectiveness of treatment, is presented. This approach involves the monitoring for total phenols, as a possible “surrogate” parameter, along with a “short list” of demonstration parameters.
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