2016 2nd International Conference on Sustainable Energy and Environmental Engineering (SEEE 2016) ISBN: 978-1-60595-408-0

Study on Oil Spill Risks and Emergency Response Strategy in Bay

Rong-chang CHEN*, Jing SHI and Chen LIU Waterborne Transport Research Institute, Beijing, 100088, P.R. China *Corresponding author

Keywords: Xiamen bay, Oil spill, Risk.

Abstract. This paper analyzes the current conditions and development pf oil spill risks existed in Xiamen Bay in aspects of environment-sensitive resources, port throughput and vessel traffic volume etc. and makes investigation into hazards and causes of oil spill incidents. The paper makes stochastic simulation on oil spill incidents that may possibly occur in Xiamen Bay, to predict and get the probability of sensitive resources being polluted surrounding the spill location, and the shortest travel time etc. The result indicates that, oil spill risks in Xiamen Bay varies significantly with season due to influencing factors such as the prevailing wind direction and tidal current, distribution of sensitive resources and seasonal change in tourist areas. On the basis of the predicted result and environmental conditions, strategies to prevent and emergency response to oil spill risks are presented, such as planning to build the emergency response capacity to regional oil spill incidents, establishing shoreline ESI atlas and measure set, making the contingency plan more regionally interactive and targeted, setting up special governmental fund for emergency response to ship pollution incidents.

Introduction Happening of serious marine pollution events such as oil spill in the Gulf of Mexico, 16/7 pollution incident in Dalian and the oil spill at Penglai 19-3 oilfield have brought severe damage to the marine environment and set off an alarm bell to human being. The whole society has been paying more attention to major marine pollution accidents, becoming more concerned about hazards arising possibly from such accidents and getting strongly aware of marine environmental protection, and therefore calling on government to impose higher requirement in better response to marine pollution. Analyzing the probability distribution of the impact of oil spill on surrounding sensitive resources and the shortest travel time can provide support to decision making in prevention and control of oil spill incidents, post-accident protection of sensitive resources and emergency response.

Analysis of Oil Spill Risk Factors

Analysis of Direct Causes to Ship Oil Spill Incidents Direct causes to ship oil spill incidents include grounding, allision/collision, hull failure, fire/explosion, loading/discharging, and other operational incidents. According to statistic of International Tanker Owners' Pollution Federation (ITOPF), during the period 1970 ~ 2014, there were in total 459 oil spills worldwide each of which spilled oil 700 tons and above [1], where the main direct causes were grounding (32.7 ％), allision/collision (29.6 ％) and hull failure (13.1 ％), as seen in Figure1.

Figure 1. Analysis of direct causes to oil spills 700 tons and above during 1970 ~ 2014 by ITOPF. During the period 1973 ~ 2006, there were in total 2635 tanker oil spills that happened in China’s coast, total oil spillage amounting to 37,000 tons [2]. Marine oil spill is one of major factors polluting marine environment and damaging ecosystem. Recent years have seen a steady growth in cargo throughput in . In 2015 its throughput reached 210 million tons. Though no heavy oil spill has ever happened in Xiamen Bay, with building of terminals and wharfs, expansion of navigational capacity and increased wharf tonnage at the Port of Xiamen, the vessel traffic flow will double or even higher in the Xiamen Bay, which will increase the possibility of vessel traffic accidents and thus aggravate the risk of vessel oil spill. Sensitivity of Marine Environment to Oil Spill Xiamen Bay is located in the southeast coastal area of Province. In the Bay the shorelines are meandering and of various types while outside it there are many islands such as Da Jinmen Island and Xiao Jinmen Island as barrier, forming an excellent bay with good protective conditions. In the Bay there are many ports and plenty of tourism resources. In and around Xiamen Bay there are numerous sensitive resources to spilled oil, including Xiamen Marine Rare-species Natural Reserve, Provincial Mangrove Natural Reserve, Gulangyu Island South Bathing Beach, Power-plant Water-Intake Zone, Haimen Island East Mariculture Zone etc. in addition to the urban shoreline and the port production shoreline. The Marine Rare-species Natural Reserve mainly involve the core reserves for Sousa chinensis, egret and lancelet. The distribution of major sensitive resources is presented in Figure 2.

Figure 2. Distribution of major sensitive resources. (1) Impact of Spilled oil on Sousa Chinensis Sousa chinensis is a Level-1 state-protection endangered wild animal and honored as “Marine National Treasure” and is highly valuable in scientific research in terms of military, medicine, bionics, species evolution, and biodiversity etc. Researches have shown that, pollution of spilled oil has major negative impact on Sousa chinensis with respect to physiology and ecologic activities, including echolocation, ingestion, respiration, reproduction, regional distribution and life safety. The most direct impact is its respiration. Because Sousa chinensis breathes with spiracle which is on the head and connected directly to its lung, if a Sousa chinensis swims encountering oil pollution, it will certainly contact spilled oil while floating-up and breathing, and may possibly breathe oil into its lung, which will necessarily jeopardize its health and survival[3]. (2) Impact of Spilled Oil on Seabirds such as Egret Of all marine organisms, seabirds are ones suffering the most significant impact of spilled oil pollution [4]. Whenever a seabird contacts the surface spilled oil, oil will adhere to its lipophilic feathers, permeate into its down feathers and damage feather’s original structure in such a way that feathers lose its thermal-insulation and water-proof functions and thus lose its buoyancy causing it to sink. Also, spilled oil adhered to the body of seabirds can make them lose balance in flight and even be deprived of the flight ability. A seabird that is contaminated by oil must increase its basic metabolism to keep its body temperature and thus have very high demand on energy. As a result it will die from hungry and cold because it will consume up very quickly its own fat reserve and it will be hard to find food in the oil-polluted area. There is also the possibility for seabirds to eat oil-contained food by mistake, and because of toxicity of petroleum hydrocarbons, seabirds will lay less eggs, give birth to less babies, suffer pathological change in tissues, develop abnormal physiology and behaviors, and even die. (3) Impact of Spilled Oil on Mangrove Mangrove grows over the shoal of inter-tidal zone at the intersection between land and sea, a special ecosystem transitional from land to sea. Mangrove functions wind breaking, wave dissipation, silting-up facilitation and beach protection, bank reinforcement and protection, cleaning of seawater and air. The mangrove Bahla Las Mmas situated across the coast of Caribbean, Panama, suffered two major pollutions of spilled oil in 30 years. The investigation by Duke et al [5] found that of all mangrove plants polluted by oil, 18 ％ died, and of all mangrove plants that were felled and survived, nearly 30% has very thin crown cover. The result from the experiment that was done by Suprayogi et al using two petroleum hydrocarbons at 5 different concentrations to process four mangrove plants: Rhizophora stylosa, Ceriops tagal, Rhizophora mucronata and Avicennia marina, [6] suggested that petroleum hydrocarbons could concentrate in leaves. Concentrated petroleum in mangrove deposit will drop pH, the content of dissolved oxygen, oxidation and reduction potential and salinity of interstitial water to create a strong-reducing environment short of oxygen damaging regional ecologic environment. Therefore, any oil spill that happen in Xiamen Bay and waters near it will lead to damage to sensitive resources hard to recover. Avoiding, reducing and effectively controlling oil spill accidents are very necessary to protect a variety of sensitive resources in and around Xiamen Bay and the baymouth, maintain and preserve the ecologic environment there, and drive the sustainable development in the marine waters there.

Oil Spill Risk Analysis Based on Stochastic Simulation Ever since 1984 when McCay Deborah French started using an oil spill model [7] to assess damage to natural resources, Oilmap has enjoyed many applications in assessment of oil spill risks[8]. The trajectory and fate model of the Oilmap model can forecast the drifting path of oil slick. Aiming at determined incident scenarios (the location of spill, the type of oil spilled, spillage and the simulating length), and winds and currents data being selected at random start time following a certain rules, the model calculates the trajectory and fate of spilled oil, and based on the threshold for thickness of oil slick, records pollution and travel time at every grid point through a single trajectory and fate simulation. After repeating the trajectory and fate simulation hundreds of times, conduct statistical analysis to all grid points with respect to the pollution probability and the travel time. The process for stochastic simulation and statistical analysis is presented in Figure 3.

Figure 3. Oilmap process for stochastic simulation and statistical analysis. (1) Oil Spill Trajectory and Fate Model The model generalizes spilled oil into oil particles having mass and each oil particle represents a proper fraction of total oil spillage. Joint action of wind force, wave, tidal current and gravity current on floating oil is considered in the oil slick drift algorithm applied in the model: the current-driving process is calculated with Lagrange particle tracking while the dissipation process is calculated with the random walk method. For the formula calculating particle’s drift speed (m/s), see Equation 1[9].    

Uoil= UUU w +++ t rα U e + β U p   (1) U w Ut where, is the speed component generated due to action of wind and wave, in m/s; is the speed U r component due to the action of tidal  current, in m/s; is the speed component due to residual

U e currents (e.g. gravity current), in m/s; is the speed component due to action of Ekman flow, in m/s; U p is the speed component due to action of squirt flow, in m/s; α is 0 for floating particles and 1 for underwater particles; β is 0 for non-squirt spill and 1 for squirt spill. (2) Stochastic Method With the oil spill trajectory and fate model will be done for dozens or hundreds of times. The method to calculate the pollution probability P (i, j) and the shortest travel time T (i, j) of each grid is presented in Equation 2 and 3[10].

M(i , j ) P() i, j = × 100% N (2) where, Mi , j ( )—The number of times of the grid (i, j)of which the quantity of pollutants exceed the set threshold, in N simulations; N—the total number of simulations;

Tij,= min N ( ) ( ) (3) min N where, ( )—the shortest travel time for pollutants to drift from the position of oil spill to the grid (i, j) of waters in N simulations under the simulated scenario where pollutants arrive at the grid (i, j) and exceed the preset threshold. Case Study

Design of Case Scenarios The scenario of oil spill incident: the turn point at the entry/exit channel of Xiamen Bay is selected as the location of oil spill simulated, the simulation forecasting with the trajectory and fate model run 300 times, and simulating start time is randomly selected in past decade. The winds data from Jan. 1 2001, 00:00 to Jan. 1 2011, 00:00, was obtained from National Centers for Environmental Prediction (NCEP), USA; seeing that the direction of prevailing winds is of great difference between summer and winter in Xiamen Bay, summer (June ~ August) and winter (December ~ the next February) are simulated and analyzed respectively. For the parameters used in model, see Table 1. Table 1. Table of parameters for stochastic simulation. Parameter Value Run times of trajectory and fate model 300 times Time length of winds 10 years (Jan. 1 2001 ~ Jan. 1 2011) accident location Turn point of the entry/exit channel at the baymouth Spillage 700 tons Single run time length for trajectory and fate model 72 hour Minimal statistical threshold Oil slick thickness: 1 µm Results from Stochastic Simulation and Analysis Based on the results from the stochastic simulation, the pollution probability distribution in Xiamen Bay is presented in Figure 4 and the distribution of statistical result of travel time for marine water being polluted is in Figure 5. From the simulating result of surface pollution probability, in summer, the sensitive resources the most liable to pollution is the Gulangyu tourist area (44%) on the north of the spill location, followed by Sousa chinensis core reserve (37%), the lancelet core reserve (35%), the power-plant water intake area (34%) and the egret natural reserve (21%), with the shortest travel time suffering pollution about 2 hours; in winter, the sensitive resources the most liable to pollution is the reclamation mariculture zone (23%) on the south of the spill location, followed by inter-tidal cultivation zone (14%) and the egret natural reserve (13%) on its north, with the shortest travel time suffering pollution about 3 ～4 hours; for details, see Table 2. It is known from the simulating result of different seasons that, oil spill in summer has more significant impact on the sensitive resources on the north of the spill location and since summer is just the peak season for tourism any oil spill will have much greater impact than in winter. Therefore, the oil spill risks in summer seems much more outstanding in Xiamen Bay.

Figure 4. Probability distribution (left: summer; right: winter).

Figure 5. Distribution of shortest travel time (left: summer; right: winter).

Table 2. Probability and shortest travel time distribution for main resources. Summer Winter No. sensitive resource Pollution Shortest travel Pollution Shortest Travel probability, % time, h probability, % time, h 1 Sousa chinensis Core reserve 37 2 3 4 2 Egret natural reserve 21 2 13 2 3 Mangrove natural reserve 4 6 2 9 4 Reclamation mariculture zone 7 4 23 3 5 Shellfish cultivating zone 7 4 6 4 6 Inter-tidal cultivation zone 4 5 14 4 7 Power-plant water intake zone 34 2 9 2 8 Lancelet core reserve 35 2 1 4 9 Gulangyu tourist area 44 2 4 4 Emergency Response Strategy for Oil Spill Risk It is known from the oil spill risk analysis and the result from stochastic simulation in Xiamen Bay, oil spill impacts to a large range and will seriously damage various sensitive resources in and around Xiamen Bay. Because oil spill risk in Xiamen Bay varies significantly with season due to influencing factors such as the direction of summer prevailing wind and tidal currents, distribution of sensitive resources and seasonal change in tourist areas, it is recommended to take following emergency response strategy for oil spill risk: (1) Make regional planning to build capacity for emergency response to oil spill. a) Develop a sound emergency response system and mechanism, and establish emergency response rules & regulations, contingency plan system and organizations; b) Provide multiple means and ways to monitor and detect oil spills, for instance, aviation and spaceflight remote sensing, onboard and shore-based radar, video and buoys, and develop such emergency information system as decision-making support and information sharing platform so as to detect any incident in early stage and treat any emergency in scientific ways. c) Reasonably deploy equipment warehouses for emergency use at proper places, and provide emergency vessels, equipment for containment, unloading, mechanical recovery, oil dispersant spraying and washing that fit for local hydrologic and weather conditions and necessary for emergency response, as well as necessary transferring and supporting facilities; d) Establish response teams: building on petrochemical enterprises (oil terminals) and specialized cleaning entities, establish emergency response expert group and specialized emergency response teams while bringing emergency response forces in society into full play and strengthen personnel training and emergency exercise or drill. (2) Seeing that Xiamen Bay has diverse shorelines, create the shoreline ESI index map, and establish localized emergency response measure sets specifically for different types of shorelines. Provide the shore seal boom, the quickly-deployable boom and contaminated bird cleaning facilities etc. specifically for peculiar sensitive resources. (3) The regional contingency plan system for vessel pollution accidents shall focus on regional interaction; emergency response measures fit for different seasons shall be developed and exercised or drilled intensively, giving that the different impact range and degree in summer and winter. (4) Set up special governmental emergency response fund to quickly start emergency actions and mobilize emergency response forces so as to control incidents and minimize damage; do more researches in vessel oil spill pollution control & prevention and emergency technologies, make more efforts to tackle hard-nut problems in science and technology, optimize the oil-spill emergency strategy and advance emergency response strategy to a higher level.

Conclusion and Recommendations Because there are rich resources sensitive to spilled oil in and around Xiamen Bay, any oil spill incident if happening in the bay or near the baymouth will engender short-term, long-term, or even regional environmental disaster to such sensitive resources as mangroves, Sousa chinensis, egret, cultivation zones and tourist areas. With fast development of the Port of Xiamen, increasing terminal tonnage and vessel traffic volume will aggravate the risk of oil spill. In the study, the stochastic simulation is applied in the oil spill risk analysis to analyze the oil spill risks in summer and winder in Xiamen Bay respectively, and put forth proper measures. Thus the study gives scientific recommendations for reasonable planning of resources for emergency response to oil spill. The stochastic correlates to factors such as the possible location of spill, spillage and simulating time length etc. and the result is comparatively significant within the range of the selected area. The pollution risk research over a large range shall be based on such possible locations of incidents as terminals &wharfs, navigational channels and anchorage within the whole range of the research, and make comprehensive analysis to multiple possible locations of incidents.

Acknowledgement This paper was funded by National science and technology support programs “the Study on Integration Technology of Major Marine Oil Spill Emergency Dispatch Command” (No. 2012BAC14B07).

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