低硫燃料油对斑马鱼早期发育阶段的毒性效应

Toxic effects of low sulphur fuel oil on early life stages of zebrafish(Danio rerio)

低硫燃料油(low sulphur fuel oil,LSFO)是指硫含量小于0.5%的燃料油.为控制航行过程中尾气硫化物的排放,减少大气污染,LSFO正逐步取代传统高硫燃料油在全球海域被广泛使用,但有关LSFO的环境风险和毒理学研究仍十分有限.本研究选取3种不同类型的LSFO:中质油WRG(wide range gas oil)、轻质油MGO(marine gas oil)和重质油VLSFO(very low sulphur fuel oil),通过制备其水溶性组分(water accommodated fractions,WAFs)溶液,综合分析LSFO及其WAFs的理化性质和组成成分;并以斑马鱼胚胎/仔鱼为受试生物,探究3类LSFO的WAFs的潜在生物毒性.结果表明,轻质油MGO及其WAFs中半挥发性有机物(semi-volatile organic compounds,SVOCs)、挥发性有机物(volatile organic compounds,VOCs)和总石油烃(total petroleum hydrocarbon,TPH)含量之和最高,中质油WRG次之,重质油VLSFO最低.WAFs的浓度由SVOCs和VOCs浓度之和表示,根据《水和废水监测分析方法(第四版)》分级标准,WRG的WAFs急性毒性特征为低毒,而MGO的WAFs和VLSFO的WAFs分别为高毒和极高毒,其半数致死浓度(LC50)分别为1.58 mg·L^(−1)和0.83 mg·L^(−1).MGO和VLSFO的WAFs对胚胎孵化抑制浓度(EC20)分别为0.85 mg·L^(−1)和0.65 mg·L^(−1).未稀释的MGO和VLSFO的WAFs会导致仔鱼出现鱼鳔发育不完全/未充气等畸形.3种LSFO的WAFs均会诱导胚胎/仔鱼体内活性氧物种含量显著升高.基于毒性单位模型的组分毒性差异分析表明,以萘类化合物为主的轻质多环芳烃是主要毒性贡献因子,LSFO的WAFs组分间可能存在拮抗作用从而减弱其生物毒性.

Low Sulphur Fuel Oil(LSFO)is an emerging category of fuel oil with a sulphur content of less than 0.5%.To control the emission of sulphur dioxide and to reduce atmospheric pollution,LSFO is steadily replacing the marine traditional high-sulphur fuel oil for wider utilizations.However,environmental risks and toxicological studies on LSFO are scarce.In this study,three different LSFOs:medium oil WRG(wide range gas oil),light oil MGO(marine gas oil),and heavy oil VLSFO(very low sulphur fuel oil)were investigated.These LSFOs and their wateraccommodated fractions(WAFs)were thoroughly characterized for chemical compositions and physicochemical properties.The zebrafish(Danio rerio)embryos/larvae were selected as test organism to investigate the toxic effects of LSFO WAFs.The results showed that the total amount of semi-volatile organic compounds(SVOCs),volatile organic compounds(VOCs),and total petroleum hydrocarbons(TPH)in the light oil MGO and its WAFs was the highest,followed by the medium oil WRG,and the heavy oil VLSFO being the lowest.The concentration of WAFs is expressed as the sum of the concentrations of SVOCs and VOCs,according to the classification standard of“Water and Wastewater Monitoring and Analysis Methods(fourth edition)”,the acute toxicity of WRG WAFs to zebrafish embryos was minimal,whereas MGO WAFs and VLSFO WAFs were highly and extremely toxic,with LC50 values of 1.58 mg·L^(−1)and 0.83 mg·L^(−1),respectively.MGO and VLSFO WAFs had inhibitory concentrations(EC20)on embryo hatching of 0.85 mg·L^(−1) and 0.65 mg·L^(−1),respectively;undiluted MGO and VLSFO WAFs could induce serious deformities in larvae,such as incomplete swim bladder development or inflation failure.All three LSFO WAFs induced significant increases in the content of reactive oxygen species in embryos/larvae.Based on the toxic unit model,the toxicity difference analysis of components revealed low molecular weight PAHs,mainly the naphthalenes,were the main toxicity contributors.And the possible antagonistic effect among the components of LSFO WAFs likely weakened their toxic effects on the organism.