The Physical-biological Processes Of Petroleum Hydrocarbons In Seawater/Sediments

With the rapid development of petroleum industry, marine oil pollution hasbecome a worldwide environmental problem. The oil is expanded to the coast inconsequence of tides and surge currents after oil spills, causing the pollution ofbeaches, coastal wetlands, etc. The physical-biological processes of petroleumhydrocarbons in the seawater/sediments were investigated. Besides, the toxic effectsof petroleum hydrocarbons on Brachydanio rerio were studied. The main results werelisted as follows:(1) The adsorption and desorption behaviors of dissolved petroleumhydrocarbons (DPHs) in sediments were described by the first-order kinetic model.The amount of equilibrium adsorption and desorption were0.395mg·g-1,0.201mg·g-1respectively. About49%DPHs were remained on sediments. The adsorption could bedescribed well by the linear isotherm model. ΔH was-39.0kJ·mol-1according to thethermodynamic analysis. The adsorption process was exothermic, and belonged tophysical adsorption.(2) The growth curves of petroleum-degrading bacteria S-1in the enrichmentmedium, the crude oil medium and the crude oil medium (30%dispersant) werestudied in this paper. The30%dispersant promoted the growth of bacteria. S-1hadthe highest degradation ratio when25%dispersant were added into the crude oilmedium. The maximum degradation ratio was46.8%with bacteria concentration of6.12×109cell mL-1.(3) The96h half lethal concentration (LC50) values of benzene, toluene,naphthalene, phenanthrene and crude oil on Brachydanio rerio were49.24,5.17,33.95,36.71and59.71mg L-1, respectively. The toxicity of the five chemicals shouldbe at the middle toxic level. The toxicity was in the sequence ofnaphthalene>phenanthrene>benzene>toluene>crude oil. The toxic mechanism wasrelated to the components and molecular structures of the five chemicals. (4) In process of indoor simulation experiment, the maximum concentration ofpetroleum hydrocarbons in the aqueous phase was4.875mg L-1, and dissolvedpetroleum hydrocarbons were sensitive to the effects of oil dispersant andbiodegradation. The amount of petroleum hydrocarbons in sediments basicallydecreased with increasing depth. The amplitude variations of petroleum hydrocarbonsconcentration in0~1.7cm sediments were greater than that in1.7~3.3cm and3.3~5.0cm sediments. The amount of petroleum hydrocarbons in intertidal sediments washigher than the amount of petroleum hydrocarbons on supratidal sediments. The C、Ncontents of the crude oil were lost in the various stages of the experiment. Then-alkanes were more sensitive to the effects of weathering and biodegradation. Thetotal loss ratios of the n-alkanes in the three stages of experiment were25.56%,16.56%and19.40%, respectively. The loss ratio caused by the emulsification ofdispersion was0.65%, biodegradation ratio was15.46%.The physical-biological processes of petroleum hydrocarbons in theseawater/sediments and the toxic effects of petroleum hydrocarbons on the aquaticorganisms were investigated. The results would provide the theoretical bases andtechnical supports for ecological assessment, pollution control and remediationtechnology of the petroleum hydrocarbon pollution.