Abstract:In order to study the distribution characteristics, sources and ecological risks of polycyclic aromatic hydrocarbons (PAHs) in the sediments of lakes along the middle reaches of the Yangtze River, surface sediments were collected from 12 lakes in the region in July 2018. The contents of 16 PAHs were determined by gas chromatography-mass spectrometry (GC-MS). The results indicated that 16 kinds of priority PAHs were all detected in these lake sediments. The contents of total PAHs were between 572.7-1766.2 ng/g(dw)(with the mean value of 976.5±285.0 ng/g(dw)). The highest content of PAHs in the sediments of Wuhan Lake East was 1634.8±111.4 ng/g (dw). Compared with lake sediments in other domestic and oversea areas, the PAHs content in the middle reaches of the Yangtze River was higher than that of Lake Fuxian, Lake Qinghai and Lake Bosten in remote areas of China, but lower than that of Lake Chaohu and Lake Taihu in the lower reaches of the Yangtze River and the economically and industrially developed areas in the United States. According to the results of single PAH clustering analysis, 12 lakes can be divided into three types. Type 1 was mainly occupied by low ring of 64.04%±7.02%. Type 2 was mainly equivalent occupied by low ring and middle ring, which accounting for 50.76%±5.17% and 49.24%±5.17%, respectively. Type 3 was homogeneous occupied by different rings, which accounting for 35.35%±3.56%, 26.17%±0.45%, and 38.48%±3.84% from low ring to high ring. According to the distribution characteristics of PAHs in this area and the results of isomer ratio method and principal component analysis, the main source of PAHs in type 1 lake sediments is the mixed source of biomass combustion and petroleum, such as coal and wood. The main sources of PAHs in lake sediments of type 2 and type 3 are low-temperature combustion of biomass such as coal and wood, exhaust emissions from motor vehicles burning gasoline and diesel, and high-temperature combustion of fossil fuels such as industrial coking. The significant correlation between PAHs and total organic carbon (TOC) in the sediments indicates that, the content of TOC in the sediments is the key factor affecting the distribution of PAHs in the lake sediments in the middle reaches of the Yangtze River. The risk assessment results of the risk quotient method, that the RQNCs of PAHs in lake sediments in the middle reaches of the Yangtze River are all less than 800, and the RQMPCs are greater than 1, indicating that the PAHs in the lake sediments along the middle reaches of the Yangtze River presents a moderate risk level.