This study reports soil PAHs from a small city (Tezpur) of the mid-Brahmaputra Valley. The soil PAHs has been assessed from representative land use using detailed protocol of extracting, cleaning, and quantitative analysis by HPLC technique. The concentrations of PAHs showed minimum spatial variability and yet showed strong seasonal variability, which could be typical of small cities having weak local source strengths. On examining the air mass reaching the region, it appeared that there has been explicit effect of long-range transport. The HYSPLIT back trajectories reaching the study area during different seasons showed variations in terms of their origins and transport pathways. This might have led to differential long-range transport of PAHs, which is reflected in the seasonal variabilities of the concentrations of PAHs. The seasonal variations were much profound with the highest ΣPAHs concentration during post-monsoon (7961 ng g-1) followed by pre-monsoon (2414 ng g-1) and monsoon (773 ng g-1) season. The toxicity of the PAHs was examined as BaP equivalent (BaPeq) concentrations, which were found to be on the lower side as compared to the studies conducted elsewhere. The percentage contribution of 3- and 4-ring compounds was found to be greater. An attempt also was made to apportion the sources of the PAHs by application of diagnostic ratios, principal component analysis-multiple linear regression (PCA-MLR) and hierarchal cluster analysis (HCA), which revealed that coal and biomass burning and vehicular emissions are the major contributors to the PAHs load in Tezpur city.

中文翻译：

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针对Brahmaputra山谷中部一个小城市（Tezpur）的土地利用，土壤PAH的变化：季节，来源和远程运输。

这项研究报告了布拉马普特拉河谷中部一个小城市（特兹普尔）的土壤多环芳烃。通过使用HPLC技术提取，清洁和定量分析的详细协议，从代表性土地利用中评估了土壤PAHs。PAHs的浓度显示出最小的空间变异性，但仍表现出强烈的季节性变异性，这可能是当地来源强度较弱的小城市的典型特征。在检查到达该区域的空气质量时，似乎已经对远距离运输产生了明显的影响。在不同季节到达研究区的HYSPLIT背轨迹显示出其起源和运输途径的变化。这可能导致了PAHs的远距离迁移差异，这可以从PAHs浓度的季节变化中反映出来。季节变化非常明显，季风后（7961 ng g-1）期间最高的ΣPAHs浓度，其次是季风前（2414 ng g-1）和季风（773 ng g-1）季节。以BaP当量（BaPeq）浓度检查了PAHs的毒性，与其他地方进行的研究相比，该浓度低一些。发现3-和4-环化合物的百分比贡献更大。还尝试通过应用诊断比率，主成分分析-多元线性回归（PCA-MLR）和层次聚类分析（HCA）来分摊多环芳烃的来源，这表明煤炭和生物质燃烧以及车辆排放是最主要的原因。 Tezpur市PAHs负荷的主要贡献者。