Persistence of PCDD/Fs in a Sludge-Amended Soil

McLachlan, Michael S.; Sewart, A. P.; Bacon, Jeffrey R.; Jones, Kevin C.

doi:10.1021/es950932g

Cited by 43 publications

(28 citation statements)

References 33 publications

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“…Many chlorinated synthetic organic chemicals, such as PCBs and dioxins, are persistent, slow to degrade, and they bioaccumulate. More than 50% of dioxins and furans were still present in soil 20 years after sludge application (McLachlan et al, 1996).…”

Section: Synthetic Organic Chemicalsmentioning

confidence: 99%

Land application of sewage sludges: an appraisal of the US regulations

Harrison

McBride²,

Bouldin³

1999

IJEP

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Current US federal regulations governing the land application of sewage sludges do not appear adequately protective of human health, agricultural productivity or ecological health. US standards are far less protective than those of many European countries and Canadian provinces. This is due to both policy choices such as a 'do no harm' philosophy applied in some northern European countries and also to many gaps and non-conservative assumptions in the risk assessment performed by US Environmental Protection Agency. The potential for widespread use of sludges on agricultural and residential land, the persistence of many of the pollutants, which may remain in soils for a very long time, and the difficulty of remediation support a cautious approach. Soil, water and crop characteristics in New York State and other areas of the northeastern US raise particular concerns. The authors do not suggest a prohibition of land application but, rather, significantly more restrictive use. Limiting cumulative additions of pollutants to prevent soils from exceeding recommended maximum contaminant levels can be achieved by application of clean sludges or by application of lesser amounts of less high quality sludges. Further investigation is needed to assess risks to ground and surface water and to establish standards for additional contaminants.

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Section: Synthetic Organic Chemicalsmentioning

confidence: 99%

Land application of sewage sludges: an appraisal of the US regulations

Harrison

McBride²,

Bouldin³

1999

IJEP

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“…However, naturally occurring microorganisms have evolved to degrade and mineralize many, but by no means all, of these compounds. For example, several PCDD/Fs are degraded very slowly or not at all (12). In addition to genera such as Terrabacter (6,14) and Pseudomonas (6), several strains belonging to the genus Sphingomonas were reported to use diaryl ethers such as dibenzofuran and dibenzo-p-dioxin as the sole source of carbon and energy (3).…”

mentioning

confidence: 99%

“…However, despite the fact that previous transformation experiments monitoring the disappearance of selected mono-to tetrachlorinated congeners of dibenzofurans and dibenzo-p-dioxins have indicated some depletion of tetrachlorodibenzo-p-dioxins is due to bacterial activity (7,15), there is still a lack of information concerning the aerobic bacterial catabolism of higher chlorinated dibenzo-pdioxins (i.e., Cl n , where n Ͼ 4) such as the ubiquitous pollutants 1,2,3,7,8-penta-or 1,2,3,4,7,8-hexachlorodibenzo-p-dioxin. In fact, these two congeners are known to exhibit very long half-lives compared to low chlorinated congeners (12) and were therefore selected.…”

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confidence: 99%

Biotransformation of 1,2,3-Tri- and 1,2,3,4,7,8-Hexachlorodibenzo-p- Dioxin bySphingomonas wittichiiStrain RW1

Nam

Kim

Schmidt

et al. 2006

Appl Environ Microbiol

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Appl. Environ. Microbiol. 68: [2584][2585][2586][2587][2588] 2002). Here we demonstrate the aerobic bacterial catabolism of the ubiquitous toxic diaryl ether pollutant 1,2,3,4,7,8-hexachlorodibenzo-p-dioxin by this strain. The products of this biotransformation were identified as tetrachlorocatechol and 2-methoxy-3,4,5,6-tetrachlorophenol by comparing mass spectra recorded before and after nbutylboronate and N,O-bis(trimethylsilyl)-trifluoroacetamide derivatization with those of authentic compounds. Additional experiments showed that the less-chlorinated 1,2,3,7,8-pentachlorodibenzo-p-dioxin was not transformed by the strain RW1. The importance of substitution patterns for the degradability of individual congeners was illustrated by the fact that the 1,2,3-trichlorodibenzo-p-dioxin was catabolized to yield 3,4,5-trichlorocatechol, whereas the 2,3,7-trichlorodibenzo-p-dioxin was not attacked.Polychlorinated aromatic compounds such as the polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) are among the most problematic environmental pollutants because of their chemical inertness and recalcitrance, lipid solubility, and toxicity (1,3,8,13). Consequently, numerous studies have been carried out to elucidate the aerobic (7, 9, 19) bacterial degradation of PCDD/Fs, compounds produced by incineration processes and as unwanted by-products of the synthesis of pesticides and herbicides (4, 17). However, naturally occurring microorganisms have evolved to degrade and mineralize many, but by no means all, of these compounds. For example, several PCDD/Fs are degraded very slowly or not at all (12). In addition to genera such as Terrabacter (6,14) and Pseudomonas (6), several strains belonging to the genus Sphingomonas were reported to use diaryl ethers such as dibenzofuran and dibenzo-p-dioxin as the sole source of carbon and energy (3). Some of these isolates are examples for effective biocatalysts that can even catabolize some di-, tri-, and tetrachlorinated dibenzo-p-dioxins and dibenzofurans (6,7,9,19). However, the aerobic catabolism of important environmental pollutants such as 1,2,3,7,8-penta-or 1,2,3,4,7,8-hexachlorodibenzo-p-dioxin, giving rise to the formation of corresponding metabolites, has not been demonstrated previously.The catabolism of dibenzofurans and dibenzo-p-dioxins is in Sphingomonas wittichii RW1 initiated by a ring-hydroxylating dioxygenase (2,18,20), introducing two hydroxyl groups in the accessible angular positions of the diaryl ether, thereby producing unstable hemiacetals. The labile intermediate spontaneously decays in the case of dibenzo-p-dioxins to yield the corresponding 2,2Ј,3-trihydroxydiphenyl ether, which is further processed, yielding a catechol and the corresponding 2-hydroxy-cis,cis-muconic acid (3, 21). However, despite the fact that previous transformation experiments monitoring the disappearance of selected mono-to tetrachlorinated congeners of dibenzofurans and dibenzo-p-dioxins have indicated some depletion of tetrachlorodibenzo-p-dioxins is due to bact...

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“…Since they are released into the atmosphere, they can disperse long distances and eventually reach water systems, soil and plants via dry and wet deposition, and can eventually bioaccumulate in the food chain, particularly in the case of fat (Wild et al, 1994;Welsch-Pausch et al, 1995;McLachlan et al, 1996;Halsall et al, 1997;Lohmann and Jones, 1998;Ren et al, 2007). There are two types of atmospheric deposition, dry and wet, that serve as the major removal mechanism for PCDD/Fs (Koester and Hites, 1992).…”

Section: Introductionmentioning

confidence: 99%