Polychlorinated Naphthalenes in U.K. Soils: Time Trends, Markers of Source, and Equilibrium Status
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- 作者：Sandra N. Meijer ; Tom Harner ; Paul A. Helm ; Crispin J. Halsall ; A. E. Johnston ; and Kevin C. Jones
- 刊名：Environmental Science & Technology
- 出版年：2001
- 出版时间：November 1, 2001
- 年：2001
- 卷：35
- 期：21
- 页码：4205 - 4213
- 全文大小：101K
- 年卷期：v.35,no.21(November 1, 2001)
- ISSN：1520-5851
文摘
Polychlorinated naphthalenes (PCNs) have been analyzedin archived soil from the U.K. to investigate historicaltrends. Samples were obtained from the Broadbalk experimentplots (1944-1986) and Luddington experiment station (1968-1990). Luddington samples also include a set of soilsthat received a one-time sludge treatment in 1968, andduplicate samples of this archived sludge were also analyzed.Peak residues of 
PCN (sum of all PCN congenersquantified) were ~9000 pg g-1 dry weight in 1956, decliningto ~300 pg g-1 in contemporary soils. The one-timesludge application resulted in elevated soil residues thatwere 1.5-6 times higher than the control plot over the timeseries. This increase is consistent with the knownapplication rate and the amount of PCN in the appliedsludge (~250 000 pg g-1 dry wt). Half-lives for the Luddingtoncontrol soil and the sludge-amended soil for the period 1972-1990 were 5.3 and 9.9 years, respectively. Investigationof time trends revealed differences between homologuegroups with the higher molecular weight congeners peakingearlier in the time series (pre-1950) and the lower molecularweight congeners peaking later, ca. 1970. Time trendsof individual congeners were investigated in terms of theirrelative mass percent contribution to the sum of theirhomologue group. Significant (p < 0.05) increasing trendswere observed for several congeners associated withcombustion sources (CN-29, -51, -52/60, -54, and -66/67)suggesting that combustion related sources are moreimportant now than they were in the past. However, nodecreasing trend was observed for congeners that werethought to be susceptible to degradation by photolysissuggesting that this may not be a key elimination pathwayof PCNs in the environment. A simple calculation of thefugacity status of PCNs in air and soil showed that the tri-CNs are exhibiting net outgassing, while the penta-CNsare still being deposited to soil. Interestingly, the penta-CNs associated with combustion show the largest gradientfor air-to-soil transfer, supporting the notion that combustionsources are important contributors to contemporary airburdens of these congeners.
PCN (sum of all PCN congenersquantified) were ~9000 pg g-1 dry weight in 1956, decliningto ~300 pg g-1 in contemporary soils. The one-timesludge application resulted in elevated soil residues thatwere 1.5-6 times higher than the control plot over the timeseries. This increase is consistent with the knownapplication rate and the amount of PCN in the appliedsludge (~250 000 pg g-1 dry wt). Half-lives for the Luddingtoncontrol soil and the sludge-amended soil for the period 1972-1990 were 5.3 and 9.9 years, respectively. Investigationof time trends revealed differences between homologuegroups with the higher molecular weight congeners peakingearlier in the time series (pre-1950) and the lower molecularweight congeners peaking later, ca. 1970. Time trendsof individual congeners were investigated in terms of theirrelative mass percent contribution to the sum of theirhomologue group. Significant (p < 0.05) increasing trendswere observed for several congeners associated withcombustion sources (CN-29, -51, -52/60, -54, and -66/67)suggesting that combustion related sources are moreimportant now than they were in the past. However, nodecreasing trend was observed for congeners that werethought to be susceptible to degradation by photolysissuggesting that this may not be a key elimination pathwayof PCNs in the environment. A simple calculation of thefugacity status of PCNs in air and soil showed that the tri-CNs are exhibiting net outgassing, while the penta-CNsare still being deposited to soil. Interestingly, the penta-CNs associated with combustion show the largest gradientfor air-to-soil transfer, supporting the notion that combustionsources are important contributors to contemporary airburdens of these congeners.