黄河源区鄂陵湖中多环芳烃的百年沉积记录

为研究黄河源区多环芳烃（PAHs）的污染历史，于2016年7月在鄂陵湖中采集了沉积物柱芯，采用²¹⁰Pb定年，利用气相色谱串联三重四级杆质谱仪（GC-MS/MS）分析了16种PAHs，运用有序聚类分析对PAHs的垂向分布进行分带，并采取主成分分析及多元线性回归定量分析了PAHs的来源.结果表明，鄂陵湖沉积柱的沉积速率为0.176cm/a，慢于青藏高原多数湖泊.总PAHs的含量为11.3~54.7ng/g，平均值为29.2ng/g，与其他高原和偏远地区湖泊沉积物相比，处于较低水平，可被视为PAHs的全球沉积物背景值.PAHs的垂向变化分为1948年以前、1948~1976和1976~2016年3个时间段，5~6环PAHs在1948~2016年间呈上升趋势，与青海省人口及大型牲畜数量显著相关，反映了鄂陵湖地区近70a来的人类活动以农牧业为主.PAHs来源分为本地源（23%）以及长距离迁移与本地混合源（77%）.本地源的垂向变化与5~6环PAHs一致，代表了青藏高原地区以牛粪饼为主要燃料的生物质燃烧源.

Centennial sedimentary records of polycyclic aromatic hydrocarbons (PAHs) in Ngoring Lake at the source region of the Yellow River,Tibetan Plateau

The pollution history of polycyclic aromatic hydrocarbons (PAHs) in the source region of the Yellow River was investigated with a sediment core in Ngoring Lake collected in July 2016. The chronology was dated by ²¹⁰Pb and 16US-EPA priority PAHs were determined by the gas chromatography-tandem mass spectrometry (GC-MS/MS). The results showed that the average sedimentation rate was 0.176cm/a, which was slower than most lakes in Tibetan Plateau. The concentrations of Σ₁₆PAHs ranged from 11.3ng/g to 54.7ng/g with a mean value of 29.2ng/g, which stayed at a low level compared with other lake sediments in Tibetan Plateau and remote regions. The concentrations of PAHs in Ngoring Lake can be considered as the global background value of PAHs in lake sediments. The vertical distribution of PAHs was divided into three periods:before 1948, 1948~1976, and 1976~2016 by the sequential cluster analysis. Five-ring and six-ring PAHs increased from 1948 to 2016 and significantly correlated with population and amounts of big livestock in Qinghai Province, indicating that ranching was the dominant human activities around Ngoring Lake. The results of principle components analysis combined with multiple linear regression showed the sources of PAHs may be attributed to the local source and the mixed source of long-range atmospheric transport and local emission. These two sources contributed 23% and 77% to the total PAHs, respectively. The vertical trend of the local source coincided with five-and six-ring PAHs, which is correlated with that cow dung is the major fuel in Tibetan Plateau.