【作者】 蔡海洋；

【导师】 曾从盛；

【作者基本信息】 福建师范大学 ， 自然地理学， 2011， 博士

【摘要】 本文以闽江口主要湿地沉积物重金属为研究对象,分析和探讨了重金属在闽江口的空间分布、累积、赋存形态及其污染评价,研究了外源重金属进入湿地沉积物后的迁移转化规律,并试图建立重金属活力值对重金属的迁移转化能力进行评价。闽江口湿地Cu、Pb、Zn、Cd含量在全国主要河口中处于较高水平,与国外其他河口相比处于中等偏上水平。闽江口湿地重金属的含量沿河口区段总体上表现为两头低中间高的特点。不同植被下沉积物中重金属元素的含量为：咸草湿地>秋茄湿地>芦苇湿地>水稻湿地；不同土地利用方式的重金属污染程度为：鱼塘>草滩>光滩>水稻。不同沉积柱样各重金属元素含量分布模式大致如下：Mn>Zn>Cu>Pb>Cd。不同洲滩湿地重金属元素中,塔礁洲湿地的Cd含量远高于鳝鱼滩和蝙蝠洲湿地,蝙蝠洲湿地Cu和Mn含量则较其他湿地有明显的上升。闽江口湿地表层沉积物中的Pb主要是以铁锰氧化物结合态(F2)为主；Cu、Zn、Ni和Fe的各个形态以残渣态(F4)为主；Cd、Mn的各个形态中酸提取态(F1)所占比率最大,其次是F2。外源重金属的培育研究发现,Cu、Pb、Zn、Mn、Cd进入沉积物后,主要转化为F1、F2和F3；培养期间残渣态含量的变化不大。外源重金属进入沉积土柱后主要转化为F1和F2,但不同重金属不同。培养过程中重金属的垂直方向上的移动一直在持续的进行,并主要以F1和F2形态移动。国际上不同沉积物质量基准(SQC)的评价均认为Cu、Cd的污染的贡献较小香港、澳大利亚和新西兰的SQC评价中Zn的污染最重,其他SQC评价结果则认为Ni污染程度最大。海洋沉积物质量标准评价认为闽江口主要遭受Zn污染。地累积指数评价则认为闽江口Cd和Zn污染最重。潜在生态危害指数法评价认为闽江口面临中等生态危害,主要潜在生态危害重金属为Cd。以基于形态学的RSP法对闽江口湿地表层沉积物进行评价,其结果为闽江口湿地的重金属污染主要来自于Pb、Cd和Mn。首创提出F1、F2、F3与F4的比值即重金属活力值来说明并评价重金属元素的迁移和转化能力的强弱。闽江口沉积物中重金属活力值Vv>3的是Pb(31个)、Cd(68个)和Mn(83个)；各个重金属元素活力大小的顺序是Mn>Cd>Pb>Zn>Cu>Ni>Fe。更多还原

【Abstract】 The total concentration, chemical speciation of elements (Cu, Pb, Zn, Cd, Ni, Fe, Mn) were determined in surface sediment collected from different wetlands of Minjiang estuary. The concentration of core sediments came from different tidal wetlands were analyzed also. Based on which, the spatial distributions, accumulation, speciation, migration were investigated. Different ecological assessment methods, which based on total concentration and chemical speciation of elements, were applied to comprehensive assess the environment quality and ecological risk. Migration and transformation of exogenous heavy metals in wetland sediments were studied by soil incubation method and soil column experiment. Attempt to establish the vigor values of heavy metal to assess the ability of migration and transformation.Concentration of heavy metals in wetland sediments of the Minjiang estuary lie between the higher level for Chinese estuarine, and lie between the mid to higher range for abroad estuarine.The character of heavy metals concentrations in Minjiang estuary was the middle estuary higher than the both sides of the estuary. In other words, the contents of heavy metals of Tajiaozhou wetland and Shanyutan wetland were lower than the Yangzhong-village tidal wetland and Bianfuzhou wetland. It is quite different that the contents of heavy metals when the wetland sediments were treated with different vegetation or different land uses. Overall, the hierarchical order of heavy metal concentrations in different vegetation is as follow:Cmalaccensis Lam. Var. bervifolius Bocklr. wetland, Kandelia candel(L.) Druce wetland, phragmites australis (Cav.) Trin. ex Steud. wetland, and artificial wetland (paddy soil). The order of heavy metal pollution in different land uses is as follow:fishpond, growing grass beach, the barren wetland and paddy soil.The order of heavy metals concentrations of different core sediment is as follow: Mn>Zn>Cu>Pb>Cd, after analyzed the core sediments that collected from different wetland of Minjiang estuary. In different wetlands, the contents of Cd came from Tajiaozhou far higher than the other wetland, and Cu, Zn concentrations of Bianfuzhou was higher than the other wetland.The modified BCR-sequential extraction technique was used to analyzed the chemical speciation(acid-soluble, reducible, oxidisable and residual) of heavy metals (Cu, Pb, Zn, Cd, Mn, Ni, Fe) in surface sediments came from the Minjiang estuary wetland. Pb in surface sediments are mainly in reducible (Fe-Mn oxides) fraction, with the contents up to 39.23%. The major chemical speciation of Cu, Zn, Ni and Fe is residual, with the contents 56.23%,51.22%,76.88% and 81.97%, respectively. Cd and Mn are mainly in acid-soluble fraction, secondly is reducible fraction.Transform of chemical forms of exogenous heavy metals in the sediments were studied with soil incubation and core sediment incubation method. Results showed that exogenous heavy metals existed in the wetland sediments mainly in available and potentially available form, and the change of residual form concentration is little. It’s mainly transform into F1 and F2 when the exogenous heavy metals came into the sediments. In the whole incubation, the migration of heavy metal in vertical direction is moving continuously mainly with F1 and F2 forms.The assessment result of the heavy metals of Minjiang estuary wetland sediment by different Sediment Quality Criteria (SQC) method is not consistent. It is consensus that Cu, Cd contribution to the Minjiang estuary pollution assess by 6 kinds SQC is small, and there are large differences contribution to the Minjiang estuary pollution in different SQC about Ni, Zn and Pb. Hong Kong, Australia and New Zealand SQC evaluated that the heaviest pollution is Zn, but others SQC evaluation result argued that Ni pollution is the largest. According to the analysis of Marine sediment quality (GB 18668-2002), the heavy metal pollution of Minjiang estuary is mainly comprised by Zn. According to the geo-accumulation, the heavy metal pollution is mainly come from Cd and Zn. According to the potential ecological risk index, Minjiang estuary was suffered from medium ecological harm and its potential ecological risk was mainly come from Cd. According to RSP (Ratio of secondary phase and primary phase), which belong to based on chemical speciation of elements, showed that the pollution of Minjiang estuary wetland mainly from Pb, Cd and Mn.Exogenous heavy metals in wetland sediments mainly transformed into acid-soluble, reducible and oxidisable, the ratio of F1, F2, F3 and F4 can indicated the ability of heavy metals migration and transformation. It is named Vigor values of heavy metals. The Vv(Vigor values of heavy metals)>3 in the whole zone is Pb, Cd and Mn, showed 3 heavy metals belongs to strong migration and transformation. The Vigor values of heavy metals can be ordered as follow:Mn>Cd>Pb>Zn>Cu>Ni>Fe.更多还原