Since the introduction of the Environmental Protection Act in the UK, there are few reports of PAH emissions from clinical waste incinerators (CWIs) operating to improved performance standards. The main aim of this study is to determine PAH emissions from a state-of-the-art CWI focusing on the effects of reactive gases and operating variables on emissions. This was carried out by collection of stack samples over three phases of operation.
At stack conditions, most PAHs are predicted to be in the vapour phase. Reactive losses of PAHs were closely correlated by rank with expected reactivities from laboratory studies. Estimates of emissions incorporating sampling losses were derived, although no correlation was found between PAH losses and the modest levels of reactive stack gases. PAH concentrations were one to two orders of magnitude lower than earlier reports from incinerators without effective air pollution control equipment (APCE). The low levels of carbon monoxide recorded were not correlated with any PAHs.
This study demonstrates the impact of efficient combustion conditions and APCE on PAH emissions from a CWI. 相似文献
Background Monitoring biological responses that are mediated via the aryl-hydrocarbon receptor (AhR) in animals exposed to environmental
contaminants can indicate both the presence to chemicals that act through this biochemical pathway and whether these chemicals
are bioavailable.
Objectives The use of an ex-situ method that incorporated biological responsiveness monitoring in mice for determining the presence of
‘biologically active’ hydrocarbons in contaminated soils was investigated.
Methods The use of C57BL/6 as a test organism was validated by determining hepatic and immune responsiveness to two polyaromatic hydrocarbons
(PAHs): 3,4 benz[a]pyrene (B[a]P) and 1,2 benz (a)anthracene (BA) administered via intraperitoneal (i.p.) injection. The responsiveness
of mice exposed to soils spiked with hydrocarbons or ex situ exposures to soil removed from two contaminated sites was also
investigated.
Results and Discussion Mice that were exposed to B[a]P via i.p. injections showed a 14-fold increase in liver microsomal ethoxyresorufin O-deethylase
(EROD) activity compared to the control group. In contrast EROD activity following BA exposure at the same level was not significantly
enhanced. Mouse immune response was significantly inhibited in a dose-dependent manner by i.p. injections of B[a]P. No significant
inhibition occurred with the same doses of BA. Following i.p. exposure, the retention of B[a]P in mouse carcasses was greater
than BA. Mice exposed to clean soils spiked with environmentally relevant concentrations of B[a]P and BA failed to show any
significantly different hepatic or immune responses. Carcass residue data indicated a limited uptake of PAH from the soil.
In contrast, EROD activity in mice exposed (ex situ) to hydrocarbon-contaminated soils removed from a fuel-loading depot and
decommissioned gas works was significantly enhanced (4- and 2-fold respectively). However, this increase in EROD activity
did not appear to correlate with either soil or carcass PAH concentrations.
Conclusions and Outlook These results support the assumption that B[a]P has a higher affinity for the aryl hydrocarbon receptor (AhR) compared to
BA. Soil parameters such as organic carbon content, structure and particle size distribution can modulate the bioavailability
of contaminants to biological receptors. These factors are implicated in the lack of responsiveness demonstrated in the spiked
soil experiments. However the responsiveness of EROD activity in mice exposed (ex situ) to soil contaminated with complex
mixtures of hydrocarbon compounds confirms the potential usefulness of this model to determine the presence of ‘biologically
active’ compounds in aged soils removed from contaminated sites. 相似文献
Background, Aims and Scope Releasing agents, applied in the aluminium diecasting process, usually consist of water, oils, waxes, polysiloxanes, as well
as of a set of additives like emulsifiers, corrosion inhibitors, and biocides. During spray application and part release,
gases and aerosols are emitted into workplace air. The chemical compositions of these emissions are determined by the components
of the releasing agents and their reaction products formed during thermal stress of more than 700 °C. In the frame of the
joint project, the analytical tasks were to develop an appropriate sampling strategy for this production environment, to draw
conclusions about the occurrence of hazardous chemicals from production plant studies and from laboratory-scale thermolysis
experiments, and to determine the biodegradability of customary releasing agents.
Methods During realistic test production, active air sampling was performed in a production hall using different adsorption materials.
Cotton fabric sheets were positioned in the production area as passive samplers. Thermolysis experiments were performed at
600 °C with sealed quartz ampoules. The biodegradability of different releasing agents was determined according to German
industry standard DIN 51828 (2000). For analyses, GC/MS (headspace), FTIR, HPLC, IC, and ICP-OES techniques were applied.
Results and Discussion The substance spectrum, which was found in workplace air, was dominated by saturated and non-saturated aliphatic hydrocarbons.
Besides these, alcohols, alkyl phenols, xylenes and other benzene derivatives, aldehydes, glycols, carboxylic acid esters,
and amides were present. The German limiting value of 40 mg/m3 of complex hydrocarbon mixtures in a diecasting workplace atmosphere
was clearly under-run. Total hydrocarbon contents ranged between 2.7 and 6.3 mg/m3. Five different PAH were found in the air
close to the diecasting machine, with maximum concentrations between 0.05 and 3.06 μg/m3. Concentrations of nonylphenols ranged
from 10 to 200 μg/m3, and those of triethanolamine from 20 to 30 μg/m3. From 17 elements analyzed, only B, Fe, P, S, Si, and
Ti were emitted in small amounts. It was striking that the PAH patterns resulting from thermolysis experiments were quite
the same compared to those determined during the diecasting process. An influence of water and of Fe/Al on the composition
of the thermolysis products could mostly be shown. The degrees of biodegradation of three releasing agent extracts after 21
days were 21%, 29%, and 55%, respectively.
Conclusion A sampling strategy was developed, which allows an emission assessment for the industrial process of aluminium diecasting.
It enabled one to control limiting values, to characterise a wide variety of compounds emitted, and to identify and quantify
relevant pollutants. Only a few hazardous substances could be detected during the exemplary use of one releasing agent within
the compounds emitted into workplace air. Indications were found, that the prediction of the formation of harmful substances
from releasing agent components should be possible via thermolysis experiments. The biodegradability test can serve to assess
the expenditure of disposal of the usual leakage run-off of excess agent during production.
Recommendation and Outlook Investigations on further differently composed releasing agents, e.g. powders, would be desirable. A substitution of nonylphenol
ethoxylates by less harmful components would surely be an improvement of a releasing agent with regard to work safety and
health care, because of avoiding the emission of toxic and endocrine active nonylphenols. The surprisingly wide range of biodegradability
of the investigated releasing agents points to an optimization potential, that has obviously not yet been considered. 相似文献