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典型重金属(Cd2+、 Pb2+)和有机污染物(BaP、 BDE-47)对长牡蛎的复合毒性效应研究
谢嘉1,2
学位类型博士
导师赵建民 ; 吴惠丰
2017-05-18
学位授予单位中国科学院大学
学位授予地点北京
关键词长牡蛎 重金属 有机污染物 复合污染 幼体 综合生物标志物 蛋白质组学
其他摘要       近年来,随着海上运输业的发展以及工业废水、生活污水的大量排放,我国近岸海域污染日益加重,严重威胁着海洋生态环境安全。其中,重金属污染具有持续时间长、不易分解的特点,且能够通过食物链转移并逐级放大,进而威胁人类健康。持久性有机污染物亦具有长期残留性、生物蓄积性和长距离迁移性等特点,对生物体具有致癌、致畸和致突变性等毒性作用。在海洋环境中,多种污染物通常同时共存并相互作用,因此其对海洋生物不仅具有单一毒性,而且还能产生联合毒性作用。然而,目前有关重金属和有机污染物对海洋生物联合毒性的研究较少,如何评估复合污染对海洋生物的毒性以及解析其致毒机理等问题亟待进一步研究。
长牡蛎(Crassostrea gigas)隶属于软体动物门双壳纲,广泛分布于我国北方近岸海域。由于其种群数量大,营固着和滤食性生活方式,对污染物具有较强的富集能力,被认为是一种较为理想的海洋环境监测生物。本研究以长牡蛎作为实验对象,探讨了典型重金属(镉、铅)和有机污染物(BaP、BDE-47)单一及复合污染对长牡蛎的急性(早期发育阶段)和亚慢性(成体)毒性效应,从而为环境监测和生态风险评价提供科学依据。同时,采集环渤海和北黄海潮间带的野生长牡蛎样品,测定其软体组织中重金属含量,检测消化腺和鳃组织中生物标志物的水平,并运用综合生物标志物响应指数法(IBR)评估了不同站位的污染状况。此外,利用iTRAQ技术,分析了环渤海和北黄海潮间带长牡蛎消化腺组织对环境压力的响应情况,研究结果可为海洋环境监测和生态风险评价提供科学依据。
本研究具体结果如下:
    (1)比较了Cd2+、Pb2+单一及复合污染对长牡蛎早期发育阶段的急性毒性效应。结果发现,Cd2+、Pb2+单一及Cd2+-Pb2+复合污染对长牡蛎胚胎的半效应浓度分别为272.2 µg/L、660.3 µg/L和373.1 µg/L;对长牡蛎幼虫96 h的半数致死浓度为353.3 µg/L、699.5 µg/L和205.5 µg/L;采用Marking相加指数(ATI)法评估了复合毒性作用,发现Cd2+和Pb2+复合污染对长牡蛎胚胎和幼虫的毒性效应分别为简单相加和协同作用。此外,与单一污染相比,复合暴露会导致长牡蛎胚胎细胞DNA损伤程度增大。以上结果表明,本研究中Cd2+、Pb2+复合污染比单一污染的毒性效应更加明显,从而可能对长牡蛎种群资源的补充过程产生潜在影响。
    (2)比较了BaP、BDE-47单一及复合污染对长牡蛎早期发育阶段的毒性效应。结果发现,BaP、BDE-47单一及BaP-BDE-47复合污染对长牡蛎胚胎的半效应浓度分别为18.4 µg/L、203.3 µg/L和72.0 µg/L;对长牡蛎幼虫96 h的半数致死浓度为26.8 µg/L、244.5 µg/L和108.9 µg/L;采用Marking相加指数(ATI)法评估了复合毒性作用,发现BaP和BDE-47复合污染对长牡蛎胚胎和幼虫的毒性效应均表现为拮抗作用,这可能是有机污染物的化学性质差异较大且易产生化学反应所导致。结果表明,BaP、BDE-47对长牡蛎的早期发育阶段具有较强毒性作用;在污染严重的河口区域,长牡蛎幼体发育等过程面临一定的风险。
     (3)探讨了Cd2+、Pb2+单一及复合污染对长牡蛎成体的亚慢性(7、14、28天)毒性效应。结果表明:长牡蛎鳃和消化腺组织对重金属均有较强的富集性(Cd2+ > Pb2+),且存在明显的剂量-依赖关系;此外,生物富集因子(BCF)随暴露浓度的增大而减小。在Cd2+和Pb2+暴露28天后,中、高浓度的单一及复合处理组的长牡蛎鳃组织出现了鳃丝肿胀、纤毛脱落以及血细胞浸润等病理现象,消化腺组织则出现了血细胞浸润、内壁间质组织与上皮细胞分离以及上皮细胞损伤坏死等病理现象,表明两种重金属暴露能够造成长牡蛎的组织结构损伤。运用综合生物标志物响应指数法(IBR),分析了长牡蛎抗氧化防御系统生物标志物的响应水平,发现Cd2+和Pb2+的联合毒性效应主要为表现为协同作用,且在高浓度处理组尤为明显。
    (4)探讨了BaP、BDE-47单一及复合污染对长牡蛎成体的亚慢性(7,14,28天)毒性效应。结果表明:长牡蛎鳃和消化腺组织对有机污染物均有很强的富集性(BDE-47 > BaP),且存在明显的剂量-依赖关系;此外,生物富集因子(BCF)随暴露浓度的增大而减小。在BaP和BDE-47暴露28天后,单一处理组的长牡蛎鳃组织出现了鳃丝肿胀和轻微的血细胞浸润等病理现象,消化腺组织则出现了血细胞浸润、内壁间质组织与上皮细胞分离并伴随上皮细胞坏死等病理现象;然而,复合处理组则无明显损伤。表明两种有机污染物复合暴露对长牡蛎组织结构的影响较小。运用综合生物标志物响应指数法(IBR),分析了长牡蛎抗氧化防御系统生物标志物的响应水平,发现BaP和BDE-47的联合毒性效应主要表现为拮抗作用。
     (5)运用综合生物标志物响应指数法(IBR),整合系列生物标志物,评价环渤海和北黄海潮间带的环境质量。结果表明,不同站位的长牡蛎组织中,重金属含量和生物标志物的响应值均存在较大的空间差异。其中,辛庄(XZ)和葫芦岛(HLD)站位的IBR/n值最高(大于2),即这两个区域的重金属污染状况最严重;其次是沧州(CZ)、曹妃甸(CFD)和盖州(GZ)站位,表明这三个站位存在较高的重金属污染压力;天津(TJ)、牟平(MP)、东营(DY)、芝罘岛(ZFD)、秦皇岛(QHD)和辛安(XA)站位重金属污染程度较轻;小石岛(XSD)、蓬莱(PL)、大连(DL)站位的IBR/n值最低(小于0.2),属于清洁海域。此外,采用iTRAQ技术,分析了环渤海和北黄海潮间带长牡蛎消化腺组织对无机环境压力的响应情况。结果发现,污染(MP、XZ、HLD站位)和清洁海域(XSD站位)之间的长牡蛎在信号传导、氧化应激、能量代谢以及免疫调节等多条途径发生了显著的变化。;
    With the rapid development of maritime transport industry and the huge emission of domestic and industrial wastewater, marine pollution has posed a serious threat to the marine environment and ecological safety. Heavy metals, well-known for their toxicity, persistence and bioaccumulation characteristics, are considered a major anthropogenic contaminant in coastal environment. Persistent organic pollutants are highly toxic and displayed a wide range of chronic effects, such as mutagenicity and carcinogenicity. In the marine environment, the heavy metals and organic pollutants not only have a single toxicity to marine organisms, but also interact with each other.
    The Pacific oysters Crassostrea gigas are widely distributed in offshore areas, and often used as bio-indicator in marine environmental assessment due to their sessile and filter-feeding lifestyle, wide geographical distribution and ability to accumulate contaminants from the surrounding water. In the present study, the individual and combined toxicities of typical heavy metals cadmium (Cd) and lead (Pb), and organic pollutants benzo[a]pyrene (BaP) and 2,2’,4,4’-Tetrabromodiphenyl ether (BDE-47) on the early development (acute) and adult period (chronic) of C. gigas were investigated, hopefully sheding light on the environmental monitoring and ecological risk assessment. Furthermore, an integrative biomarker approach was employed to evaluate the environmental quality of the coastal areas of Bohai Sea and Northern Yellow Sea using native oysters. Additonally, we applied iTRAQ-based proteomics to characterize the differential proteomic changes and elucidate the differential toxicological effects of oysters collected from different stations. The results were summarized as followed:
    (1) The individual and combined toxicities of dissolved Cd2+ and Pb2+ on early life stages of the oyster was investigated. For embryotoxicity, the median effective concentration (EC50) values for individual Cd2+, Pb2+ and their mixture were of 272.2µg/L, 660.3µg/L and 373.1 µg/L, respectively. The median lethal concentrations (LC50) for 96 h larval mortality were determined to be 353.3 µg/L, 699.5 µg/L and 205.5 µg/L for individual Cd2+, Pb2+ and their mixture, respectively; Moreover, the Marking-Dawson additive toxicity indices indicated an additive effect with a trend to synergism for the Cd2+ and Pb2+ combination. Furthermore, DNA strand breaks were observed in oyster embryos after individual Cd2+, Pb2+ and their mixture exposure, and a significant positive correlation was demonstrated between embryotoxicity and genotoxicty. These data will be helpful to predict the toxicity of metal mixtures, and provide biological criteria for the implementation of marine water quality standards.
    (2) The individual and combined toxicities of BaP and BDE-47 on early life stages of the C. gigas were investigated. The EC50 values of BaP, BDE-47 and their mixture on embryogenesis were 18.4 µg/L, 203.3 µg/L and 72.0 µg/L respectively, while the LC50 values for 96 h larval mortality were 26.8 µg/L, 244.5 µg/L and 108.9 µg/L respectively. The Marking-Dawson additive toxicity indices indicated an additive effect with a trend to antagonism. The results indicated that BaP and BDE-47 expoure may cause potential toxic effect to oyster embryos and larvae, especially at high-concentration areas.
    (3) The individual and combined chronic toxic effects (7, 14, 28 days) of dissolved Cd2+ and Pb2+ on the C. gigas were investigated. There was a strong accumulation of heavy metals in the gills and digestive glands of C.gigas, indicating a significant dose-dependent relationship. Bioconcentration factor (BCF) decreased generally with the increase of heavy metal concentrations in ambient seawater. Significant histopathological changes such as hemocyte infiltration, cilium eletion and filaments tumidness were observed in gills; while hemocyte infiltration, thinning and exfoliation of digestive gland tubule epithelium into lumen and tubule atrophy were found in digestive gland of C. gigas after Cd2+ and Pb2+ exposure. An integrated biomarker response (IBR) approach was employed to integrate the biomarkers of oxidative stress (superoxide dismutase, SOD, catalase catalase, CAT, lipid peroxidation, LPO and glutathione S-transferase, GST). The results showed that the combined toxicity effects of Cd2+ and Pb2+ were synergistic, especially in the high concentration treatment.
    (4) The individual and combined chronic toxic effects (7, 14, 28 days) of dissolved BaP and BDE-47 on the C. gigas were investigated. The gills and digestive glands of oysters showed a strong accumulation of organic pollutants, and presented a significant dose-dependent pattern. BCF decreased generally with the increase of POPs exposure concentration. After BaP and BDE-47 exposure, the gills and digestive glands of C. gigas displayed significant histopathological changes, such as hemocyte infiltration, cilium eletion and filaments tumidness were found in gills; hemocyte infiltration, thinning and exfoliation of digestive gland tubule epithelium into lumen and tubule atrophy were found in digestive glands indicating microstructure damage and dysfunetion in oysters. IBR method was employed to integrate the biomarkers of oxidative stress (SOD, CAT, LPO and GST). The results showed that the combined toxicity effects of BaP and BDE-47 were mainly antagonistic.
    (5) The integrated biomarker (IBR) approach was used to evaluate the environmental quality of the Bohai Sea and Northern Yellow Sea coastal area. There was a spatial difference of heavy metal concentration and biomarker responses in C. gigas collected from different sites. Among them, XZ and HLD sites were the most severely contaminated area with the highest IBR/n value (more than 2), and the XSD, PL and DL sites were the less-polluted area with the lowest IBR/n value (less than 0.2). Moreover, iTRAQ-based proteomics was applied to elucidate the perturbance of heavy metals in digestive glands of C. gigas from different coastal areas of Bohai Sea and Northern Yellow Sea. The alteration of proteins involved in signaling pathway, oxidative stress, energy metabolism and immune regulatory was observed in oyster digestive glands between the polluted areas (MP, XZ, HLD site) and less-polluted station (XSD site).
学科领域海洋生物学
语种中文
文献类型学位论文
条目标识符http://ir.yic.ac.cn/handle/133337/22444
专题中科院烟台海岸带研究所知识产出_学位论文
作者单位1.中国科学院烟台海岸带研究所
2.中国科学院大学
第一作者单位中国科学院烟台海岸带研究所
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谢嘉. 典型重金属(Cd2+、 Pb2+)和有机污染物(BaP、 BDE-47)对长牡蛎的复合毒性效应研究[D]. 北京. 中国科学院大学,2017.
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