大连“7·16”溢油事故后5年间烃的降解与细菌丰度变化研究

摘要

With the aim to study the long term response of marine microbiology to oil contamination,the annual change of petroleum hydrocarbon (TPH) concentration and bacterial abundance in seawater and sediment of Dalian bay were analyzed after oil spill accident.The TPH concentration in surface seawater reduced from 0.22 ～0.67 mg/L in September 2010 to 0.0025～0.05 mg/L in May 2012 with the seawater quality changing from the third to the first seawater quality standards.The TPH concentration in surface sediments collected along the coastal sites BQ012 reduced from 7 133 μg/g in December 2011 to 926 μg/g in 2014,indicating the sediments quality recovered to the first quality standards in 2014.The abundance of heterotrophic bacteria and petroleum hydrocarbon degradation bacteria reached to 105 CFU/mL and 104 CFU/mL,respectively,within the two months of the accident.After 5 years,bacterial abundance decreased 1～2 magnitudes.The ratio of hydrocarbon degradation bacteria and heterotrophic bacteria (HDB/HB) in surface seawater is significantly correlated with petroleum hydrocarbon concentration (P＜0.01).There were no significant correlations between bacterial abundance and concentrations of nutrient salt and dissolved oxygen.Therefore,the value of HDB/HB is recommended to serve as an index of petroleum hydrocarbons pollution levels in the seawater environment.%为了解大连新港7.16溢油事故发生后5年间大连湾受污染海区生态恢复程度,同时探究大连湾表层海水和沉积物中微生物对石油污染的长期响应策略,对大连湾表层海水和沉积物中石油烃含量的分布、异养细菌和石油烃降解菌丰度的年度变化特征,以及细菌丰度与环境因子间相关性进行了研究.结果表明,溢油事故发生后2年间,大连湾表层海水中石油烃含量由溢油初期2010年9月的0.22-0.67 mg/L降到0.0025-0.05 mg/L (2012年5月),海水质量也由三类海水转变为一类海水;沿岸站位BQ012表层沉积物中石油烃含量也由201 1年12月的7 133 μg/g降低到2014年的926μg/g,其表层沉积物质量也由三类转变为一类沉积物质量标准.溢油后2个月内表层海水中异养细菌及石油烃降解菌丰度升高至105 CFU/mL和104 CFU/mL,随着时间推移各站位细菌丰度基本呈下降趋势,5年后细菌丰度回落了1～2个数量级并恢复到溢油前的历史水平.表层沉积物中石油烃降解菌丰度由溢油后2个月的105 CFU/g降低到2013年的102 CFU/g.石油烃降解菌与异养细菌的比值(HDB/HB)与石油烃含量呈极显著的正相关(P＜0.01),而与营养盐和溶解氧等主要环境因子相关性不大,因此认为其可作为海水中石油烃类污染评价的指标.