A survey of the digested sludge from 14 U.K. wastewater treatment plants was carried out to obtain contemporary U.K. data on the concentrations of certain classes of persistent organic compounds for which data are scarce and to assess whether U.K. sludge was likely to comply with the sludge limits for PCBs and PAHs proposed by the European Union. Total PAH (24 compounds) concentrations ranged from 67 to 370 mg/kg dw, in line with data from other countries; all the samples would exceed the proposed EU limit. Total PCB concentrations were 110-440 microg/kg dw, well below the proposed EU limit. Total PCN concentrations ranged from 50 to 190 microg/kg. Total synthetic musk concentrations ranged from 2.1 to 86 mg/kg dw; there were a few very high concentrations of HHCB and AHTN in the samples. Total concentrations of the short- and medium-chained polychlorinated alkanes ranged between 7 and 200 mg/kg and between 30 and 9700 mg/kg, respectively. These very high concentrations are indicative of chemicals with numerous and ongoing diffuse sources.

This study was carried out to assess the influence of physicochemical properties on PAH sequestration in sterile sewage sludge-amended arable soil. Radiolabeled phenanthrene (14C-9-Phe), pyrene (14C-4,5,9,10-Pyr), and benzo[a]pyrene (14C-7-B[a]P) were spiked and aged for up to 525 days in sterile soil microcosms. The degree of compound sequestration at various sampling times was determined by their extractability with organic solvents and release from soil residues by base saponification extraction. The amount of PAH extractable by butanol and dichloromethane decreased with compound aging in the soil. The decrease in PAH extractability with aging, and the formation of nonextractable bound residues, increased with compound molecular weight, KOW and KOC. The amount of total extractable PAH determined by sequential dichloromethane soxtec and methanolic saponification extraction decreased from 98%, 97%, and 94% at day 10 to 95%, 91%, and 77%, respectively for 14C-9-Phe, 14C-4,5,9,10-Pyr, and 14C-7-B[a]P after 525 days aging. During the same aging period there was an increase in the amount of PAH released from the soil by base saponification extraction, suggesting a progressive diffusion of PAHs into hydrolyzable and recalcitrant organic matter and mineral phases of soil. Calculated half-lives for the apparent loss of PAHs by sequestration in this experiment were dependent on the method used to extract them from soil. These half-lives ranged from 96 to 1,789 days depending on the compound, and are in agreement with values obtained from previous spiking experiments using nonsterile soils. These results suggest that a considerable fraction of PAHs assumed degraded in previous studies may have been sequestered within the organic carbon and, to a lesser extent, mineral phases of soil.

No abstract

Ambient air samples were taken concurrently at four sites in northwest England to assess the role of domestic burning of coal/wood on ambient levels of PCDD/Fs, PCBs (including co-PCBs), and PAHs. Fifty-six samples (ca. 800 m 3 each) were taken in January and February 1998 at an urban site, a rural reference site, and two village sites, which relied on domestic burning for space heating. Correlations with meteorological parameters found the urban site to be a source area of all POPs investigated, while the village sites had a local impact of PAHs and, to a lesser extent, PCDD/Fs. PCDD/F-levels changed simultaneously at all sites, pointing toward a combination of regional meteorological effects and increased domestic burning. Two sampling events, marked by low ambient temperatures and wind speeds, showed substantial increases in PCDD/F and PAH concentrations (by factors of 2-5). We estimate that local sources at the villages accounted for ∼25% of the ΣTEQ (with ∼75% stemming from advective transport) and ∼75% of the ΣPAHs in the ambient air at those sites (∼25% advective transport) during our winter sampling events. This study singled out PCDFs, notably the lower chlorinated ones, as good indicators of domestic burning, together with a range of PAHs. The co-PCBs #126 and 169 were found to behave like PCDD/Fs and PAHs rather than the more abundant "regular" PCBs, confirming that they have different sources to the environment.

A detailed comparison of two inherently different ambient air samplers has been conducted to fully characterize and compare their performance in sampling and measuring the partitioning of a suite of 29 semivolatile organic compounds (SVOCs). A high volume air sampler (hi-vol) utilizing polyurethane foam (PUF) adsorbent for vapor-phase trapping and an annular diffusion denuder sampler were operated concurrently. Sampling artifacts were observed and can be related to the physicochemical properties of the analytes and the designs of the samplers. The results suggest that high volume air samplers equipped with PUF are unsuitable for measuring those organochlorine compounds and 2-and 3-ring PAHs which have subcooled liquid vapor pressures (p°L) greater than ca. 0.2 Pa (log-[p°L] ) -0.7), owing to their breakthrough on PUF sampling media at relatively low sample volumes (170 m 3 ) and ambient temperatures typical of temperate regions (mean ) 11 °C, max ) 18 °C). Theoretical calculations of breakthrough volumes for SVOCs on PUF are presented and in most cases these successfully predict observed behavior. The denuder sampler is more efficient at measuring the relatively volatile SVOCs. For total SVOC measurements the hi-vol and denuder were in good agreement for those compounds which were efficiently sampled, and the denuder yielded total SVOC concentrations which differed by a mean factor of 1.2 relative to those obtained with the hi-vol sampler. The hi-vol sampler provides good agreement with the Junge-Pankow model for partitioning of the relatively less volatile PAHs (log[p°L] < -3), though the fraction of the PCBs in the particle-phase is underestimated. The results from the diffusion denuder indicate that for the more volatile SVOCs (log[p°L] > -3), particulate loadings are overestimated with respect to the Junge-Pankow model, and for less volatile SVOCs, particulate loadings tend to be underestimated. An important observation is that the results from the denuder indicate that PCBs may be adsorbed on atmospheric particulate matter to a similar degree as PAHs.