Elsevier

Environmental Pollution

Volume 163, April 2012, Pages 256-260
Environmental Pollution

Sedimentary record of polycyclic aromatic hydrocarbons in a reservoir in Northeast China

https://doi.org/10.1016/j.envpol.2012.01.005Get rights and content

Abstract

A sediment core from the Dahuofang Reservoir in Northeast China was 210Pb and 137Cs dated and analyzed for polycyclic aromatic hydrocarbons (PAHs) to track the regional PAH pollution in the past 50 years. The 2–4 ring PAHs peaked in the early 1990s, reflecting the historical role of coal usage in the energy structure in this area. More recently, vehicle emissions caused the continuous increase of the 5 + 6 ring PAHs. However, the sixteen US EPA priority PAHs showed a significant decline since the early 1990s. This PAH temporal trend is different from the U.S., the European countries and Japan, and is also different from the other areas of China, which could be attributed to the switch from coal to oil or natural gas as the main energy, and the large-scale elimination of outdated combustion facilities and techniques in Northeast China.

Highlights

► The 50 year trend of PAHs in a reservoir in Northeast China was established. ► The decrease of the 16 PAHs since 1990s could be attributed to the energy structure change in the region. ► The increase of 5 + 6 ring PAHs in the reservoir could be partly due to the contribution from vehicle emissions. ► The PAH time trend in this study is different from that in the U.S. and European countries, and other areas of China.

Introduction

Polycyclic aromatic hydrocarbons (PAHs), compounds containing two to eight aromatic rings, have been of concern for several decades due to their carcinogenic properties, and the US EPA has designated sixteen priority PAHs (16 PAHs) that are characteristic of environmental pollution. In China, the major anthropogenic sources of these 16 PAHs include biomass burning, coal and petroleum combustion, coking as well as metal production (Xu et al., 2006). The increase in the consumption of energy in recent years in China suggests PAH emissions will also keep on increasing (Liu et al., 2005, Guo et al., 2006, Yan et al., 2009, Hu et al., 2011).

Because of the persistent nature of some PAHs, sediment cores can provide historical records of PAHs, and perhaps even other pollutants, on a regional basis for 50–100 years (Pereira et al., 1999, Hartmann et al., 2005, Itoh et al., 2010). These records, in turn, can be used to understand the energy structure and consumption, and thus building a picture of the economic development of a region (Lima et al., 2003, Liu et al., 2005, Guo et al., 2006).

Northeast China, including Liaoning, Jilin and Heilongjiang provinces is one of the most important heavy-industry bases in China because it has bountiful of natural resources including coal, wood, shale and minerals, and in the 1960s, petroleum was discovered. In 2009, the GDP of Liaoning ranked seventh in the nation. The industries include heavy machinery, electronics, metal refining, automobile, petroleum, chemicals, construction materials, etc. Due to the long and harsh winter there, space heating will also add to the pollution problem.

The Dahuofang Reservoir (DHF) is in the central part of Liaoning (Fig. 1) and is the largest man-made lake in Northeast China. Its sediments contain atmospheric deposition that can reveal regional pollution, in particular, PAHs and thus the energy structure in the past 50 years.

Section snippets

Sampling

The DHF is located in the Northeast China among 41°41′N-41°57′N° and 124°05′E–124°20′E° as shown in Fig. 1. The DHF started to be built in 1952 and was completed in December 1958. The DHF is the biggest lake of Liaoning Province with the area of 114 km2, the water volume of 21.87 × 108 m3, and the watershed of 5437 km2.

A sediment core, Z6, was collected using a gravity corer in January, 2010 (Fig. 1). The core Z6 was located at the center of the DHF and the water depth was 36 m. The length of core Z6

Occurrence level of PAHs

The 16 PAH concentration range is 590–638 ng/g in the surface and subsurface sediments (0–3 cm). Comparing to the other lakes in China, it is lower than Nansi Lake, North China (160–32,600 ng/g) (Li et al., 2009), Taihu Lake, East China (1207–4754 ng/g) (Qiao et al., 2006), and it is also lower than the Pearl River, South China (Luo et al., 2008), Haihe River, North China (Jiang et al., 2007), but comparable to Qiantang River, East China (Chen et al., 2007), Yangtze River (East China) and Yellow

Conclusions

The sediment core extracted from the DHF reservoir in Liaoning Province in Northeast China in January 2010 showed a significant decline in the 16 PAHs concentrations after the early 1990s despite the rapid economic development that started in 1978. This decrease is quite different from the studies from the other areas in China. The reasonable explanation is because of the availability of petroleum products in Liaoning and the surrounding provinces. Liaoning was able to switch from coal to

Acknowledgements

This work was supported by the major program of the national water pollution control and management in China (No. 2009ZX07528-002). We are deeply grateful to Prof. Ming Fang of the Hong Kong University of Science and Technology for his invaluable advice. We wish to thank Dr. Zhao Y.M., Mr. Liu X., Mr. Wang M.Y., and Miss Luo Y. for the sample collection. Anonymous reviewers should be sincerely appreciated for their constructive comments and suggestions that greatly improved this work.

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