Studies On The Interactions Between Oil And Suspended Particulate Matter In The Coastal Environment

The demand of oil is growing as the industrialization processes speed up.Oil spill is inevitable in the process of exploitation and transportation,which can cause the coastal zone being polluted more frequently.Oil and suspended particles in the marine environment can generate Oil-Suspended Particulate Matter Aggregates.At the same time,the particles,plankton,and the biological interacting with oil to form Marine Oil Snow.The formation of OMA/MOS can promote the spread of oil from the beach to the sea water,which is conducive to the natural removal of oil pollution.Dispersant is usually applied for emergency treatment after the oil spill.The existing researches mainly focus on the formation mechanism of OMA and its influencing factors,the systematic study of the effect of bacteria on the formation of MOS and dispersant on OMA/MOS is lacking.In this regard,a laboratory study was designed and conducted.OMA/MOS formed by beach surface sediment and quartz and kaoline under different conditions were studied.The effects of mixing energy,particle concentration,salinity and dispersant on OMA/MOS formation were analyzed.The main conclusions are as follows:(1)The dominate particle size of Qingdao Huiquan Bay beach surface sediments that affect the formation of aggregates begins at 75?m.After the screening,the smaller the particle is the more easily to form aggregates with oil droplets.(2)The types of mineral particles have a significant influence on the formation of aggregates,kaoline is more easily to interact with oil forming aggregates than quartz sand and Qingdao Huiquan bay beach surface sediments;Quartz needs high mixing energy to form OMA.(3)Mixing energy has a strong control function on the formation of aggregates.When below a certain mixing energy(with orbital shaker speed less than 120r/min),no aggregates formed in a short time even if there is enough mineral grains.The oil capture of sedimentary continues to grow with orbital shaker speed up until reach an equilibrium value.The increase of mixing energy can reduce the begin time of aggregate forming.(4)By studying the structural characteristics of OMA/MOS,OMA are mainly single droplet and short-rod type,while MOS are stringy or fluffy type with rough edge.The size of OMA is on micron level,the largest is 200?m.MOS is relatively large in size,and some can reach up to millimeter.(5)Salinity has little effect on the formation of aggregates.The optimal salinity of OMA is around 20‰,the optimal salinity of MOS is around 35‰.(6)Dispersant also has a certain influence on the formation of aggregates.Dispersant can affect the surface properties of oil droplets and then affect the formation of OMA/MOS.At low concentration(DOR<1:2),it will promote the formation process.And the addition of dispersant is not the more the better.(7)Bacteria play a crucial role in the removal of oil.Compared to oil capture in the sedimentation of OMA,it is much higher in the sedimentation of MOS.The oil capture rate of oil in the form of sedimentation OMA is less than 10%,however the oil capture rate of oil from the surface in the form of sedimentation MOS can reach up to 95.24%.