渤海龙口湾沉积物中烃类物质的分布特征、来源解析及风险评价

随着《山东半岛蓝色经济区发展规划》（国函2011]）的实施，龙口湾的海洋开发活动得到空前发展，人类活动不仅影响了其潮汐和沉积环境，也使石油类成为该海域主要污染物之一.采用网格布点法采集了龙口湾表层（0~5 cm）沉积物样品，使用GC-MS对烃类物质（正构烷烃和多环芳烃）进行研究，通过其特征参数和比值丰度识别沉积物中有机物来源及污染排放源，并对沉积物进行生态风险评价.结果表明:正构烷烃参数碳优势指数（CPI_25-35）最大值为1.5（< 4），陆海比（TAR）和海洋与水生输入比（P_mar-aq）的范围分别为0.15~1.08和0.28~0.74，指示沉积物中有机物的海源性浮游动植物贡献较大；nC₁₆指数〔w（∑C_11-36）/w（nC₁₆）〕最大值为20.76（< 30），且71%站位的天然正构烷烃比率（NAR）值小于0，说明海洋开发活动造成了石油类污染物注入.沉积物中2环、3环PAHs（多环芳烃）的占比均超过50%，16种PAHs的总浓度范围为460.03~2 448.29 ng/g，平均值为1 328.60 ng/g，且86%的站位达到PAHs的中度、重度污染；PAHs的特征比值分析指示，龙口湾沉积物中PAHs属于石油和燃烧源的混合来源.以沉积物中PAHs含量为基础，与加拿大土壤质量指南比较，结果显示低分子量PAHs（Acy、Ace、Flu、Phe和Ant）偶尔会产生生态危害；致癌性PAHs比重（∑Car-PAHs）和BaP毒性当量（TEQ_BaP）综合评价表明，在当前的经济开发活动下龙口湾沉积物中PAHs具有一定的潜在毒性，但处于安全水平内.研究显示，龙口湾沉积物中正构烷烃属于陆源、海源和石油烃混合来源；PAHs主要属于石油和燃烧源的混合来源，其生态风险处于安全水平. 

Distribution, Source and Risk Assessment of Hydrocarbons in Sediments of Longkou Bay, Bohai Sea

With the implementation of the Development Plan of Shandong Peninsula Blue Economic Zone, human activities in Longkou Bay have developed at an unprecedented rate. Economic development not only affected its tidal and sedimentary environment, but also made petroleum one of the major pollutants in the bay. The surface sediments (0-5 cm) were collected in Longkou Bay. All samples were analyzed for hydrocarbons using GC-MS. The distribution and characteristic parameters of n-alkanes and polycyclic aromatic hydrocarbons (PAHs) were investigated to determine the origins of organic matter and pollutant emission in sediments. Then an environmental risk assessment of sediments were carried out. The results showed that the maximum value of CPI_25-35 was 1.5 (< 4). The TAR ranged from 0.15 to 1.08, while the P_mar-aq ranged from 0.28 to 0.74. These indicated that biogenic origin n-alkanes were more input of marine plankton. The maximum value of the nC₁₆ index was 20.76 (< 30), and 71% of the stations' NAR value was less than 0. These showed that marine development activities caused a certain degree of oil pollution. The proportion of 2- and 3- ring PAHs reached up to 50%. The total concentration of 16 PAHs ranged from 460.03 to 2448.29 ng/g, with a mean value of 1328.60 ng/g, and 86% of the stations reached the moderate and severe pollution. The indices of PAHs indicated that PAHs were derived primarily from petroleum and combustion. PAHs toxicity level was evaluated using the Canada Soil Quality Guidelines (SQGs). Some low molecular weight PAHs (Acy, Ace, Flu, Phe, and Ant) occasionally had adverse ecological risk. The Carcinogenic PAHs (∑Car-PAHs) and BaP toxicity equivalent (TEQ_BaP) were used to estimate the potential health risk of PAHs. They indicated that Longkou Bay sediments had certain toxicity risk, but they were within safe levels. This study shows that n-alkanes in Longkou Bay sediments come from terrestrial, marine organic matter and hydrocarbons origin. And PAHs belong to a mixed source of petroleum and combustion, and their environmental risks are at safe levels.