Understanding of automobile-derived pollution in tropical Asian waters

2003-2005年，在热带亚洲国家(即泰国、柬埔寨、老挝、马来西亚、菲律宾、越南、印度尼西亚和印度)的143个河流和沿海地点采集了表层沉积物样本。采用冷冻干燥沉积物加速溶剂萃取、两步硅胶柱层析、气相色谱-质谱仪(GC-MS)对沉积物样品中的多环芳烃(PAHs)、多环芳烃(PAHs)和苯并噻唑类化合物进行了分析。沉积物中多环芳烃的总浓度从6 ng/g干沉积物到265,000 ng/g。较低的浓度可归因于土壤的稀释，土壤主要由地表径流提供，与热带气候带固有的频繁和暴雨有关。除印度加尔各答外，热带亚洲城市地区沉积物中的多环芳烃剖面显示出强烈的成岩特征。…更多Re。已用于多环芳烃来源识别的甲基菲与菲的比值(MP/P比)在热带亚洲所有受检城市的许多地点都大于2，表明热带亚洲城市地区存在广泛的成岩多环芳烃输入。岩性多环芳烃的大量输入与发达国家热源输入的优势形成了鲜明对比，发达国家的MP/P值在许多情况下小于1。以十二烷基硫酸钠(十二烷基硫酸钠)水溶液为模拟消化液，采用体外提取法研究了沉积多环芳烃的生物可达性。对于MP/P比为~3~7的马来西亚沉积物，多环芳烃的生物可及性(用十二烷基硫酸钠提取的多环芳烃与用DCM超声提取的多环芳烃的比例)为~30%~~70%，而对于MP/P比小于2的日本沉积物，生物可及性为~5%~~40%。这表明，在亚洲热带水域中发现的岩生多环芳烃比热解多环芳烃具有更高的生物可获得性。这种较高的生物可及性与在马来西亚西海岸采集的贻贝中观察到的较高的多环芳烃浓度和较高的MP/P比值相一致。通过对多环芳烃和Hopane剖面的密集统计分析(聚类分析和多元回归分析)，对成岩多环芳烃的详细来源进行了估计。苯并噻唑的分析，轮胎磨损颗粒和街道灰尘的分子标记，以及重金属的分析也被应用于来源识别。分析表明，成岩的多环芳烃主要来源于汽车，街道扬尘是多环芳烃进入水环境的主要途径。此外，使用过的曲轴箱油、轮胎磨损颗粒、沥青和柴油废气被确定为街道灰尘和沉积物中多环芳烃的主要来源。街道粉尘的主要贡献是多环芳烃浓度与轮胎中丰富的几种金属(如Cd、Zn)之间的正相关。较少

Surface sediment samples were collected at 143 riverine and coastal locations in the tropical Asian countries (i.e., Thailand, Cambodia, Laos, Malaysia, Philippines, Vietnam, Indonesia, and India) in 2003-2005. Polycyclic aromatic hydrocarbons (PAHs) together with hopanes and benzothiazoles were analyzed for the sediment samples by gas-chromatograph equipped with mass spectrometer (GC-MS) following accelerated solvent extraction (ASE) of freeze-dried sediments, two-step silica gel column chromatography. Total PAH concentrations ranged from 6 ng/g-dry sediment to 265,000 ng/g. The concentrations of sedimentary PAHs were categorized as low to middle in comparison on global scale. The lower concentrations can be ascribed to dilution by soil which is intensively supplied by surface runoff associated with frequent and heavy rain inherent in the tropical climate zone.PAH profiles in sediments from urban areas in the tropical Asia except for Kolkata, India, exhibited strong petrogenic signatu … More re. A ratio of methylphenanthrenes to phenanthrene (MP/P ratio), which has been utilized for source-discrimination of PAHs, was more than 2 in many locations in all the cities examined in the tropical Asia, indicating that wide-spread inputs of petrogenic PAHs occur in urban areas in the tropical Asia. This extensive inputs of petrogenic PAHs provides striking contrast with dominance in pyrogenic inputs in developed countries where MP/P ratios are less than unity in many cases.Bioaccesibility of sedimentary PAHs were studied by in vitro extraction method using aqueous solution of sodium dodecylsulfate (SDS) as simulated digestive fluid. Bioaccessibility of PAHs (proportion of PAHs extracted with SDS to PAHs ultrasonically extracted with DCM) was〜30% to〜70% for Malaysian sediments whose MP/P ratios were〜3 to〜7, whereas those for Japanese sediments with MP/P ratio less than 2 were〜5% to〜40%. This suggests that petrogenic PAHs found in tropical Asian waters are more bioavailable than pyrogenic PAHs. The higher bioaccessibility is consistent with higher PAHs concentrations with higher MP/P ratios observed in mussels collected from Malaysian west coast than those from Tokyo Bay.Detailed sources of the petrogenic PAHs were estimated through intensive statistical analyses (cluster analysis and multi regression analysis) of PAHs and hopane profiles. Also analyses of benzothiazoles, molecular markers of tire-wear particles and street dusts, and heavy metals were applied to assist the source-identification. The analyses indicated that the petrogenic PAHs are derived from automobiles and the street dust was identified as the dominant pathway of PAHs to the aquatic environments. Furthermore, used crankcase oil, tire-wear particle, asphalt, and diesel exhaust were identified as primary sources of the PAHs to the street dust and sediments. Predominant contribution of street dust was supported by positive correlation between PAH concentrations and several metals abundant in tire (e.g., Cd, Zn). Less