Effect of Aquatic Organic Matter and Global Warming on Accumulation of PAHs in Lakes, East China

The sedimentary records of organic matter in lakes can reflect the response of lakes to global warming. Multiple organic proxies in the sediment core samples collected from Luoma Lake and Hongze Lake in Jiangsu were used to expound the effects of global warming and anthropogenic activities on lacustrine productivity and deposition of polycyclic aromatic hydrocarbons (PAHs). Total organic carbon, algal organic matter proxies (S2 and hydrogen index), and nutrients such as total phosphorus and total nitrogen were measured. The source apportionment modeling and the principal component analysis demonstrated that algal organic matter and bacteria organic matter showed an upcore increasing trend and an obvious enrichment effect on PAHs, which was also related to the increasing temperature and algal productivity in the lakes. Global warming enhanced the lacustrine productivity and the accumulation of PAHs in sediments. Therefore, the organic geochemical indicators in lake sediments can effectively reflect the impact of climate warming on the lacustrine productivity and the accumulation of PAHs, and provide data support for the management of lakes. Plain Language Summary The impact of global warming on the environment is increasing, and previous research was mainly on the polar region, and there are relatively few studies on the impact on inland lake environments. In this paper, a typical organic pollutant, polycyclic aromatic hydrocarbons (PAHs), is taken as the starting point, and two lakes in eastern China, Luoma Lake, and Hongze Lake, are taken as the research objects. The sedimentary records of diatoms and bacteria were also analyzed to explore the interaction between diatoms and bacteria in the lake and PAHs. The results showed that diatoms had bioaccumulation effects on PAHs, especially HMW‐PAHs, and bacteria were the main contributors to the secondary productivity of the lake. In addition, changes in atmospheric temperature of Xuzhou and Bengbu recorded by weather stations near the lake show that the average annual atmospheric temperature has risen by nearly 2°C over the past 70 years, indicating a warming phenomenon in the region. Next, we analyzed the three factors related to algal growth in lakes, temperature, total nitrogen, and total phosphorus, and correlated them with PAH content and algal and bacterial biomarker content. There were significant positive correlations, especially for HMW‐PAHs, indicating that the increase in plankton productivity cause