IOCAS-IR  > 海洋生态与环境科学重点实验室
台湾东部黑潮海水元素地球化学及对黑潮入侵东海的指示
刘伟
学位类型博士
导师宋金明
2017-05
学位授予单位中国科学院大学
学位授予地点北京
学位专业环境科学
摘要探讨黑潮主流径海水中元素地球化学特征对于阐明黑潮对东海陆架的输入与影响,揭示黑潮对东中国海生态环境调控作用有重要科学价值。本学位论文基于2014年5~6月期间对台湾以东黑潮主流径及邻近东海海域的综合调查,在建立和完善海水中元素定量测定方法的基础上,系统地研究了海水中溶解态元素的地球化学分布特征、迁移机制、影响因素以及与海域生态环境的关系,构建了黑潮对东海陆架海水的输入与影响的化学元素指示指标体系,获得了一系列新的结果和认识:
1通过对海水中元素Mg(OH)2共沉淀和直接稀释两种预处理方式ICP-MS测定方法的比较研究,确定了两种预处理方法与不同元素定量分析的对应关系,完善建立了一种Mg(OH)2共沉淀-直接稀释预处理联用准确快速测定大洋和近海海水中28种常微量元素的方法。
Mg(OH)2共沉淀法能够实现对海水中V、Cr、Mn、Co、Cd及稀土元素(La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu)共19种微量元素的准确测定,10倍直接稀释法能够实现海水中B、Sr、Li、Rb、I、V、Cr、As、Cd、U、Mo、Cu、Mn共13种常量/微量元素的准确测定。通过两种方法联用,使用较少的样品量(约50mL海水),即可实现大洋和近海海水中Co、La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu(这15个元素采用Mg(OH)2共沉淀法)及B、Sr、Li、Rb、I、V、Cr、As、Cd、U、Mo、Cu、Mn(这13个元素采用10倍直接稀释法)等28种元素的准确测定,适用于大批量海水样品简便、快速分析。
2、揭示了台湾以东黑潮主流径及邻近东海海域海水中保守型元素钙(Ca)、镁(Mg)、锶(Sr)、钾(K)、溴(Br)、硫酸盐(SO42-)、锂(Li)、铷(Rb)、钼(Mo),营养盐型元素碘(I)、镉(Cd)、锰(Mn)、锑(Sb)的地球化学分布特征及控制因素,系统获取了黑潮输入东海的物质通量。
黑潮主流径海水中保守型元素Ca、Mg、Sr、K、Br、SO42-、Li、Rb、Mo的浓度分布范围分别为420~453 mg/L、1321~1369 mg/L、7.94~8.38 mg/L、391~412 mg/L、65.17~71.07 mg/L、2629~2834 mg/L、164~187 μg/L、110~131 μg/L、14.11~16.10 μg/L,其垂直分布与盐度的变化趋势基本一致,呈现出表层浓度低,向下次表层浓度逐渐增高,中层浓度下降,再向下至底层浓度逐渐升高的特点,其中Mg、SO42-、Li受黑潮水层变化影响最为明显。营养盐型元素I、Cd、Mn、Sb在黑潮主流径海水中的浓度分布范围分别为49.7~64.3 μg/L、0.02~0.20 μg/L、0.30~1.42 μg/L、0.24~0.44 μg/L,呈现出从表层至深层浓度逐渐增高的特点,其中Cd、Mn两种元素在表层与深层水中的垂向富集分馏最为明显。
水交换模型估算得出黑潮水在5~10月间(雨季)向东海陆架的元素净输入通量分别为Ca 8.09×1012 kg、Mg 25.1×1012 kg、Sr 0.152×1012 kg、K 7.53×1012 kg、Br 1.11×1012 kg、SO42- 51.0×1012 kg/半年、Li 3.33×109 kg、Rb 2.25×109 kg、Mo 2.8×108 kg、I 11.03×108 kg、Cd 1.59×106 kg、Mn 1.18×107 kg、Sb 5.60×106 kg。各元素中Ca、Mg、Sr、SO42-、Rb、Mo、I、Mn、Sb以黑潮次表层水的输送通量为最大,表层水次之,而中层水最小。黑潮次表层水和表层水向东海陆架输送的K和Br通量相当,但均高于中层水。Cd和Li的输送通量以黑潮表层水为最高,次表层水较小,中层水最小。
东海陆架区表层和30m层元素的分布结果显示,陆架外侧的站位表层至30m层主要受控于台湾海峡水,来自台湾海峡的低Ca、Mg、Sr、K、Br、SO42-、Li、Mo、I、Sb的水流从海峡北端出口东侧向北,可到达东海陆架的中南部,而来自东部的高Ca、Mg、Sr、K、Br、SO42-、Li、Mo、I、Sb浓度的黑潮表层水则受到了台湾海峡北向出水的抑制,被限定在陆架的东南部。在外侧东海陆架底层,元素Ca、Mg、Sr、K、SO42-、Li、I、Cd、Mn、Sb较陆架中部高,呈现出黑潮次表层水的特点,黑潮水的影响范围向西北扩大。从东海陆架各断面元素的垂直分布来看,Ca、Mg、Sr、K、SO42-、Li、I、Sb在DH5、DH7断面的分布能够体现出黑潮次表层水沿底层爬升、北向入侵陆架至钱塘江口,在DH9断面从陆架坡折处从底层向西入侵的现象。由于地球化学特性的差异,部分元素分别在平面分布、垂直分布及特定站位分布上不能完全体现出黑潮的影响。总起来看,元素Ca、Mg、Sr、K、SO42-、Li、I、Sb在调查海域平面分布、垂直分布及上升流中心的TW0-1站位分布中均能够较好的指示黑潮对东海的影响。
3、以海水中溶解Ba作为指示指标,构建了Ba-盐度(S)指示黑潮与东海海水混合的新指标体系;基于海水元素簇谱和向量相似法构建了指示黑潮水入侵的海水元素相似性分析方法。
以溶解钡(Ba)作为指示指标得出,调查期间黑潮表层水对东海陆架区域影响不大,黑潮次表层水沿陆架底层向上爬升,从台湾东北海域沿陆架中部向西北方向侵入,形成一支黑潮入侵流,至钱塘江口附近黑潮水占比仍可达到65%左右。东海陆架底层外侧大部被黑潮水所控制,100m等深线以深处黑潮水能够占95%以上的比例。在台湾东北部DH9断面,黑潮次表层水从陆架坡折处沿底部向西侵入,黑潮水占比95%的位置可达东经122°左右,垂直向上黑潮水所占比例越小。海水溶解Ba可以细致地刻画黑潮入侵东海的情景,其地球化学特性使其成为指示黑潮入侵东海的有效指标,为定量揭示黑潮与东海的相互作用提供了新的手段。
以海水中Ca、Mg、Sr、K、Br及SO42-共6种常量元素构建了黑潮次表层水元素簇谱,搭建了适用于海水元素相似性分析的向量相似计算方法,结果显示东海陆架区各站位底层海水与黑潮次表层水的相似度能够显示出黑潮次表层水入侵东海陆架的轨迹,说明基于海水元素簇谱和向量相似法构建的海水元素相似性分析方法能够指示黑潮入侵东海现象,有必要进一步开展海水元素相似性分析方法在海洋水团混合领域的研究。
其他摘要The studies on geochemical characteristics of elements in seawater are of important scientific significance in illuminating the input and influence from the Kuroshio to the East China Sea (ECS), and in revealing the regulation role of the Kuroshio on the ecological environment of the ECS. In this study, geochemical characteristics of multiple elements in sea water were studied by investigation of the Kuroshio mainstream east of Taiwan Island and the adjacent ECS from May to June 2014. Systemic studies on geochemical distributions, transport processes and influencing factors of dissolved elements, and the coupling relationships between elements and environmental parameters were presented on the basis of establishing and improving the simultaneous determination method for elements in sea water. The indicator system of dissolved elements for the Kuroshio incursion into the ECS was established. A series of new results and viewpoints were presented as follows:
1. Two preprocessing methods, including Mg(OH)2 co-precipitation and direct dilution, had been studied in the determination of multiple elements in sea water by inductively coupled plasma mass spectrometric (ICP-MS). Suitable method was defined for the quantitative analysis of corresponding elements. A method of accurately and rapidly determining 28 elements in offshore and open sea water was established by combining the two methods together.
Mg(OH)2 co-precipitation could achieve the separation, enrichment and accurate determination of 19 elements including V, Cr, Mn, Co, Cd, Pb and rare elements(La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu),while 10 fold direct dilution method could accurately and simultaneously determine 13 major/ trace elements including B, Sr, Li, Rb, I, V, Cr, As, Cd, U, Mo, Cu, Mn, but it was not suitable for Zn, Ni, Co, Pb and low concentration elements like rare earth elements. The two methods were simple and rapid for suitable elements with high accuracy and precision. Combining the two methods together, accurate determination of 28 elements, including Co, Pb, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu(15 elements, by Mg(OH)2 co-precipitation) and B, Sr, Li, Rb, I, V, Cr, As, Cd, U, Mo, Cu, Mn(13 elements, by 10 fold direct dilution) could be achieved with about 50 mL of offshore and open sea water.
2. Concentration, distribution and controlling factors of conservative elements including Ca, Mg, Sr, K, Br, SO42-, Li, Rb, Mo and nutrient-type elements including I, Cd, Mn, Sb, were revealed in water of the Kuroshio mainstream east of Taiwan Island and the adjacent ECS. The influx of elements from the Kuroshio into the ECS was systematically obtained.
The concentration of Ca, Mg, Sr, K, Br, SO42-, Li, Rb, Mo in the Kuroshio mainstream water was in the range 420~453 mg/L, 1321~1369 mg/L, 7.94~8.38 mg/L, 391~412 mg/L, 65.17~71.07 mg/L, 2629~2834 mg/L, 164~187 μg/L, 110~131 μg/L, 14.11~16.10 μg/L respectively. The vertical distribution of these elements was similar to salinity, showing the trend of lower concentration in surface water, increasing for subsurface water, decreasing in intermediate water, but rising again in deep water, in which Mg, SO42-, and Li was mostly affectd by the change of water layer. The concentration of I, Cd, Mn, Sb in the Kuroshio mainstream water was in the range 49.7~64.3 μg/L, 0.02~0.20 μg/L, 0.30~1.42 μg/L, 0.24~0.44 μg/L respectively, all showing the trend of increaseing gradually downward from the surface, in which the vertrical enrichment of Cd, Mn was most noteable.
The influx of elemens from the Kuroshio into the ECS during May to October (Rainy season) was calculated to be Ca 8.09×1012 kg, Mg 25.1×1012 kg, Sr 0.152×1012 kg, K 7.53×1012 kg, Br 1.11×1012 kg, SO42- 51.0×1012 kg, Li 3.33×109 kg, Rb 2.25×109 kg, Mo 2.8×108 kg, I 11.03×108 kg, Cd 1.59×106 kg, Mn 1.18×107 kg, Sb 5.60×106 kg by a water exchange model. For Ca, Mg, Sr, SO42-, Rb, Mo, I, Mn, Sb, the subsurface layer had the largest portion, followed by surface layer, and the intermediate water had the lowest portion. There were similar influx between subsurface and surface water for K and Br. But for Cd and Li, the surface water had the largest portion, followed by subsurface water, and the intermediate water had the lowest portion. 
As shown from the distribution of elements, water of surface and 30 m layer at the stations of the outer shelf was mainly controlled by Taiwan Strait water. Water of low Ca, Mg, Sr, K, Br, SO42-, Li, Mo, I, Sb concentration, flowing northward from the north exit of the Taiwan Strait, could reach the south-central ECS shelf. This restricted KSW, which contained higher Ca, Mg, Sr, K, Br, SO42-, Li, Mo, I content,to the southeast part of ECS shelf. In the bottom layer of the outer shelf, the concentration of Ca, Mg, Sr, K, SO42-, Li, I, Cd, Mn, Sb was higher than in the middle shelf water, which showed the characteristics of KSSW and that the Kuroshio had begun to expand its influence by intruding onto the shelf northwestward from station TW0-1. Vertically, the distribution of Ca, Mg, Sr, K, SO42-, Li, I, Sb in the section DH5 and DH7 could refelect the phenomenon of Kuroshio subsurface water climbing northward along shelf bottom to as far as the Qiantang River estuary, and plunging westward into shelf water along bottom from the shelf edge in section DH9. Because of the different gechemical characteristic, some elements could not fully refect the Kuroshio incursion in plane distribution, vertical distribution and the distribution at specific station. In general, Ca, Mg, Sr, K, SO42-, Li, I, Sb could well reflect the regular pattern of Kuroshio incursion into the ECS both in plane distribution, vertical distribution and the distribution at TW0-1 station.
3. The indicator system of Ba-Salinity(S) for indicating water mixing between the Kuroshio and the ECS was established by using Ba as a tracer. A similarity analysis method for sea water elements was proposed to explore the incursion of Kuroshio water based on element cluster map and vector similarity analysis method.
The indicating results of Ba as a parameter, showed that the Kuroshio surface water had little impact on the ECS, while the Kuroshio subsurface water formed an intrusion current by climbing northwest along the bottom of the middle shelf from the sea area northeast of Taiwan Island into the Qiantang Estuary, of which the volume of Kuroshio water was nearly 65%. Kuroshio water was the predominant part of the water on the outer shelf bottom and its proportion in areas deeper than the 100 m isobath could reach more than 95%. In the DH9 section (north of Taiwan Island), Kuroshio subsurface water intruded westward along the bottom from the shelf edge and then rose upward (in lower proportion). Kuroshio water accounted for 95% of the ocean volume could reach as far as 122° E. Ba was able to provide detailed tracing of the Kuroshio incursion into the ECS owing to its geochemical characteristics and became an effective tracer for revealing quantitative interactions between the Kuroshio and the ECS.
The element cluster map of Kuroshio subsurface water was established by 6 major elements including Ca, Mg, Sr, K, Br, and SO42-. Similarity analysis method for sea water elements was put forward based on the principle of vector similarity. Results showed, the similairty between bottom layer water of the ECS shelf and Kuroshio subsuface water could reflect the track of Kuroshio incursion into the ECS, which illustrated that the similarity analysis method for sea water elements based on element cluster map and vector similarity method could reveal the pattern of Kuroshio incursion, indicating a need for further study on the application of the similarity analysis method for sea water elements in marine water mixing research.
语种中文
文献类型学位论文
条目标识符http://ir.qdio.ac.cn/handle/337002/136687
专题海洋生态与环境科学重点实验室
作者单位中国科学院海洋研究所
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刘伟. 台湾东部黑潮海水元素地球化学及对黑潮入侵东海的指示[D]. 北京. 中国科学院大学,2017.
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