Time trends in sources and dechlorination pathways of dioxins in agrochemically contaminated sediments.
Time trends in sources and dechlorination pathways of dioxins in agrochemically contaminated sediments.
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受农业化学品污染的沉积物中二恶英的来源和脱氯途径的时间趋势。
DOI：
10.1021/es0627444
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发表时间：
2007
影响因子：
11.4
通讯作者：
S. Masunaga
中科院分区：
文献类型：
--
作者：
Minori Uchimiya;S. Masunaga
虽然多氯二苯并对二恶英和二苯并呋喃被认为是生物和非生物降解过程中不可降解的物质，但实验室研究表明，在受污染沉积物普遍存在的高度还原条件下，侧向脱氯途径（去除2，3，7，8-取代氯）是可能的自然补救策略。以前对日本沉积物中的多氯二苯并对二恶英和多氯二苯并呋喃进行的主成分分析（PCA）未确定一个因子，其特征是五至八同系物在1，2，6，9-位完全氯化（1，2，6，9-模式）。在本研究中，我们重新研究了PCDD/Fs的沉积物芯从城市（东京湾）和偏远地区（湖真嗣）的日本使用正矩阵分解（PMF），并揭示了一个横向脱氯指纹表现出的1，2，6，9模式。相对摩尔浓度的假定的横向脱氯产物随沉积物深度线性增加，这表明几十年的反应导致在底部沉积物层中的七氯和六氯的横向脱氯产物的积累。原位形成脱氯产物所需的时间估计在信治湖至少为27.8 +/- 17.9年（摩尔%）（-1），在东京湾至少为4.7 +/- 0.5年（摩尔%）（-1）（均用于形成1，2，3，4，6，7，9-HpCDD）并且明显长于实验室中观察到的脱氯途径。
Although polychlorinated dibenzo-p-dioxins and dibezofurans (PCDD/Fs) are considered recalcitrant toward biotic and abiotic degradation processes, laboratory studies indicated lateral dechlorination pathways (removal of 2,3,7,8-substituted chlorines) as possible natural remediation strategies under highly reducing conditions prevailing in contaminated sediments. Previous principal component analysis (PCA) of PCDD/Fs in Japanese sediments left unidentified a factor characterized by penta- to octa- homologues fully chlorinated at 1,2,6,9-positions (1,2,6,9-pattern). In the present study, we reexamined PCDD/Fs in sediment cores from urban (Tokyo Bay) and remote (Lake Shinji) areas of Japan using positive matrix factorization (PMF) and revealed a lateral dechlorination fingerprint exhibiting the 1,2,6,9-pattern. Relative molar concentrations of putative lateral dechlorination products linearly increased with sediment depth, suggesting that decades of reaction resulted in the accumulation of hepta- and hexa- chlorinated lateral dechlorination products in the bottom sediment layers. Times required for in situ formation of dechlorination products were estimated to be at least 27.8 +/- 17.9 year(mole %)(-1) in Lake Shinji and 4.7 +/- 0.5 year(mole %)(-1) in Tokyo Bay (both for the formation of 1,2,3,4,6,7,9-HpCDD) and are significantly longer than the dechlorination pathways observed in the laboratory.