Stout Scott A, Uhler Allen D, Emsbo-Mattingly Stephen D
Battelle Memorial Institute, 397 Washington Street, Duxbury, Massachusetts, USA.
Environ Sci Technol. 2004 Jun 1;38(11):2987-94. doi: 10.1021/es040327q.
Anthropogenic hydrocarbons in surficial urban sediments derived from nonpoint sources (e.g., stormwater runoff, surface runoff, direct atmospheric deposition, and small but persistent discharges) are the principal characteristics of "urban background". Establishing the character and concentration of urban background helps determine the incremental impacts from point sources and develop successful remedial strategies. In this study, we compared the nature and amount of total extractable hydrocarbons (THC) and polycyclic aromatic hydrocarbons (PAHs), including alkylated PAHs, within 280 surficial (mostly 0-10 cm) sediments from nine, well-studied urban waterways on the East and West U.S. Coasts. These 280 sediments were predominantly impacted by urban background. All the sediments were analyzed by consistent preparation and analytical methods and met consistent data quality objectives, thereby minimizing variations attributable to methodology. The data demonstrate that the anthropogenic hydrocarbons comprising urban background from all locations exhibit a generally consistent nature, dominated by (1) a variably shaped unresolved complex mixture (UCM) within the residual (C20+) range and (2) a variable distribution of resolved 4- to 6-ring nonalkylated (parent) PAHs, mostly dominated by fluoranthene and pyrene (and exhibiting a FL/PY ratio of 0.9 +/- 0.2). The variable nature of both the THC and PAH distributions testifies that, while there is a general consistency to urban background, there are definite differences between (and even within) different urban settings. This indicates thatthere is no single "representative" urban background THC or PAH signature. The greatest mass of THC is reasonably attributable to heavy petroleum(s) comprising the UCM, whereas the greatest mass of PAHs is reasonably attributable to combustion-derived particulate matter. The mean concentration of THC attributable to urban background was 415 mg/kg (dry wt). The concentration of EPA 16-Priority Pollutant PAHs was less than 20 000 microg/kg (dry wt) in 96% of the sediments studied. Thus, sediments containing significantly more than 20000 microg/kg of the EPA 16 Priority Pollutant PAHs (or more the 30000 microg/kg of 43 parent and alkylated PAHs) should be suspected to contain PAHs not entirely attributable to urban background, unless site- or regional-specific survey data supports a different urban background concentration profile.
城市地表沉积物中源自非点源（如雨水径流、地表径流、直接大气沉降以及少量但持续的排放）的人为碳氢化合物是“城市背景”的主要特征。确定城市背景的特征和浓度有助于确定点源的增量影响，并制定成功的修复策略。在本研究中，我们比较了美国东、西海岸九条经过充分研究的城市水道中280份地表（大多为0 - 10厘米）沉积物中总可提取碳氢化合物（THC）和多环芳烃（PAHs）（包括烷基化多环芳烃）的性质和含量。这280份沉积物主要受城市背景影响。所有沉积物均采用一致的制备和分析方法进行分析，并满足一致的数据质量目标，从而将方法导致的变化降至最低。数据表明，所有地点构成城市背景的人为碳氢化合物具有总体一致的性质，主要表现为：（1）在残余（C20 +）范围内形状各异的未分辨复杂混合物（UCM），以及（2）已分辨的4至6环非烷基化（母体）多环芳烃的可变分布，大多以荧蒽和芘为主（且荧蒽/芘比值为0.9±0.2）。THC和PAH分布的可变性质表明，虽然城市背景总体上具有一致性，但不同城市环境之间（甚至在不同城市环境内部）存在明显差异。这表明不存在单一的“代表性”城市背景THC或PAH特征。THC的最大质量合理地归因于构成UCM的重质石油，而PAHs的最大质量合理地归因于燃烧产生的颗粒物。城市背景导致的THC平均浓度为415毫克/千克（干重）。在96%的研究沉积物中，美国环保署16种优先污染物多环芳烃的浓度低于20000微克/千克（干重）。因此，除非特定场地或区域的调查数据支持不同的城市背景浓度分布，否则含有显著超过20000微克/千克美国环保署16种优先污染物多环芳烃（或超过30000微克/千克的43种母体和烷基化多环芳烃）的沉积物应被怀疑含有并非完全归因于城市背景的多环芳烃。
