Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Long-term Petroleum Pollution Status of the Coastal Waters and Sediments after Dalian “7.16” Oil Spill
Weijun Guo,Wenhui Qi, and Jibing Zou
College of Environmental Sciences and Engineering, Dalian Maritime University
Dalian, China

the PH of seawater, which is also recognized as a key indicator ofenvironmental pollution in China at the present time (Wu, 2018).
Phs is a homogeneous mixture of alkane, olefin, arene, heterocyclicbenzenoid, and other components with complex molecular structures,containing a variety of carcinogens that are difficult to reduce ordestroy in soil or water.
PHs is a homogeneous mixture of alkane, olefin, arene, heterocyclicbenzenoid, and other components with complex molecular structures,containing a variety of carcinogens that are difficult to reduce ordestroy in soil or water (Gilde et al., 2012; Li et al., 2019; ). Moreover,once PHs reach the shoreline, they will be strongly adsorbed bysediments. It is known that sediment adsorbed PHs are more resistant tovarious weathering processes, such as biodegradation andphotodegradation (Duan et al., 2018; Tansel et al., 2011; Yin et al.,2015). The slow rate of dissipation and weathering of sedimentadsorbed oil may pose long-term risk to marine ecosystems and humanhealth because sediment-retained oil may resuspend into the watercolumn under extreme conditions or ingested by benthos (Yin et al.,2015). Owing to concerns about the long-term effects of the spill, aseries of environmental impact assessments were conducted to monitor
the concentrations of PHs in seawater and sediment in vicinity of thespill site.

ABSTRACT
We use monitoring data of petroleum hydrocarbons (PHs) after ten
years as indicators to assess the long-term environmental impact of theDalian “7.16” Oil Spill on seawater and sediments. Compared with thevalues measured ten years ago, the monitoring PHs concentrations inwater and sediment have decreased 91.1% and 69.2%. Although oil has
been eliminated from the surface, the long-term environmental impacts
are confined to the sea beds where PHs levels in sediment exceeding
1000 mg/kg. High levels of PHs are primarily concentrated in industrial
area far away from spill site, indicating that the PHs in seawater ismainly from on-going sewage outfalls rather than the spill event.
Unless external loading levels of PHs are suppressed, the sedimentquality is expected to recover slowly.

KEY WORDS: oil spill; petroleum hydrocarbons; sediment; Dalian.
INTRODUCTION
Spilled oil has long been recognized as a problem for the oceans: itpollutes both beaches and sea surface; and is consumed by fish,seabirds, and other creatures. The Dalian “7.16” oil spill happened on
July 16, 2010, and released approximate 35,000 tonnes of crude oil into
the coastal water (Xu et al., 2012; Guo et al., 2014). Oil leakage
contaminated the surrounding area and the Yellow Sea in China,causing 100 square kilometers of sea surface covered by oil slicks (Liuet al., 2013). An area of approximately 10 square kilometers washeavily polluted (Liu, 2016). Oil spills were cleaned up using physicalmethods such as oil absorbent felt within a month. In addition, 30 tonsof oil abatement agents were also sprayed in the contaminated area inorder to break down and dissolve the crude oil (Hong et al., 2020). A
large extent of the shoreline in Dalian was also heavily polluted. The
spilled oil had brought dramatic ecological impacts to the Daliancoastal ecosystem (Liu et al., 2013). Recent oil spills have shown thatoil can persist in coastal sediment for several decades (Reddy et al.,
2002; Peterson et al., 2003). An important indicator of water quality isMETHODS AND MATERIAL
Study area and sample collection
The sampling points are distributed in the oil spill affected area, ofwhich 12 are located in the nearshore area and the other 20 are locatedin the offshore area (Fig. 1).

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