首先，建立了基于切向超滤法（CFUF）和液液萃取法分离富集检测水体中胶体态（1 kDa ~ 0.22 μm）痕量金属的方法。该方法的检出限为：Cu 1.18 pmol L-1；Cd 0.68 pmol L-1；Pb 0.13 pmol L-1。方法对三种金属有较好的回收率，富集倍数为40，该方法已成功应用于北黄海实际样品中胶体态Cu、Cd和Pb的分离检测。其次，建立了一种结合离心超滤法（CUF）、酸萃取和ICP-MS分离测定水体中胶体态Cd、Cu和Pb的方法。通过调节离心时间和离心力，可以在70 min内有效分离水样中不同分子量的胶体态Cu、Cd和Pb。此外，方法检出限低，为0.005 ~ 0.131 nmol L-1，回收率为85.3% ~ 100.8%。此外还进行了膜校准实验。
（2）本研究选用1、3和10 kDa三种规格的再生纤维素膜CFUF装置对北黄海近岸海水样品进行尺寸分级后，然后结合液液萃取、ICP-MS对其中的痕量元素进行了富集并检测。结果表明，北黄海两近岸点海水中胶体态（1 kDa ~ 0.22 μm）Cd浓度分别为0.098和0.037 nmol L-1，胶体Cu浓度分别5.35和5.19 nmol L-1，胶体Pb浓度分别为2.75和8.20 nmol L-1，三种金属的胶体态约占总溶解态的30.9% ~ 50.8%。此外，1 ~ 10 kDa分子量区间的胶体部分可能是该地沿海生态系统中Cd、Cu和Pb迁移过程的关键部分，也可能是影响痕量金属在各个分子量区间中迁移的主要因素。另外，总溶解浓度的变化不一定影响<1 kDa真溶解态以及1 ~ 3 kDa、3 ~ 10 kDa和10 kDa ~ 0.22 μm三种胶体分级浓度的变化。
烟台市城市河流系统6个站位中，<1 kDa Cd、Cu和Pb占各自总溶解态的58.1% ~ 90.2%，胶体Cd浓度为0.02 ~ 0.05 nmol L-1，胶体Cu浓度为0.24 ~ 6.88 nmol L-1，胶体Pb浓度为0.23 ~ 1.11 nmol L-1。Cd和Pb更可能与10 kDa ~ 0.22 μm分级的胶体结合，而Cu更可能与1 ~ 3 kDa 低分子量胶体有关。溶解态Cd在低盐区的添加行为涉及Cl络合物的形成以及颗粒物的解吸或降解，并且这种添加行为在冬季更为明显，并且与1 ~ 10 kDa胶体的行为密切相关。逛荡河口1 ~ 10 kDa Cd的去除行为则可以归因于胶体的凝结/絮凝。Cu在逛荡河口的去除行为可能是强Cu配体的减少和胶体的凝结/絮凝，而辛安河口的添加行为可能与沉积物中强Cu配体的引入有关。Pb在两个河口的去除行为可能受到Fe氧化物的凝结/絮凝作用的显着控制。
（3）对牟平海洋牧场海域中痕量元素的生物地球化学行为进行表征，考察了人类活动影响区域各环境因素对痕量金属在水体中迁移的综合影响。采用建立的CUF法研究了该区域表层水中7种痕量元素，并对溶解相的五个分级，即<1 kDa真溶解态以及1 ~ 3 kDa、3 ~ 10 kDa、10 ~ 100 kDa和100 kDa ~ 0.7 μm四个胶体态分级与各个环境参数之间的相关性进行了研究。结果表明，7种胶体态目标元素在9月主要以100 kDa ~ 0.7 μm大分子为主，11月目标区域内胶体态Cu、Cd和Pb仍以100 kDa ~ 0.7 μm大分子为主，胶体Ca和Mn主要为10 ~ 100 kDa，Al和Fe则主要为1 ~ 3 kDa。从目标元素与各环境因子的相关性来看，Al、Ca、Mn、Fe、Cu、Cd、Pb在不同分级与不同种类的营养盐的相关性之间出现了显著性差异。9月水体温度较11月偏高，浮游植物的快速生长繁殖引起的营养盐浓度降低使其与Fe、Mn等生物易利用金属呈显著性相关。11月气温降低不利于浮游植物的生长及大量繁殖，以及由此引起的低生物量以及有机质对胶体配体的贡献程度减小，引起了胶体态金属比例的整体降低。此外，Cd、Pb等亲有机金属在研究区域与无机因素（如Si、P等）也显示出显著性相关，表明其来源并非单一的有机来源，风浪及洋流引起的沉积物再悬浮所释放的无机配体也可能影响其空间及尺寸分布。
（4）采用建立的CUF法研究了黄河口表层水中7种痕量元素，并对溶解相的四个分级，即<1 kDa真溶解态以及1 ~ 3 kDa、3 ~ 10 kDa和10 kDa ~ 0.7 μm三个胶体态分级与颗粒物、有机质等环境参数之间的相关性进行了研究。Al、Mn、Fe、Cu、Cd和Pb与10 kDa ~ 0.7 μm尺寸分级的胶体相关，而溶解态Ca在丰水期与3 ~ 10 kDa尺寸分级的胶体有关，在枯水期则与10 kDa ~ 0.7 μm的胶体相关。枯水期胶体Cu、Cd和Pb的来源主要可能为陆源输入；胶体Ca的浓度在两个季节中均与悬浮颗粒物（SPM）浓度呈显着负相关，表明胶体Ca的主要来源可能来自颗粒物表面的解析；胶体态Pb在四个溶解态分级中的迁移主要受水体溶解有机物的影响，而颗粒物对胶体态Ca的影响更大。
In this research, based on the study of the separation and enrichment of colloidal trace metals in natural waters, the concentration and distribution of various colloidal trace metals in the coastal of the Shandong Peninsula and the estuary were systematically analyzed. The general characteristics of the coastal waters of the North Yellow Sea, the urban riverine and estuarine waters of Yantai City, the Yellow River Estuary (YRE), and the waters of the Muping marine pasture were obtained. Combined with correlation studies of other environmental factors (such as organic matter, particulate matter, and salinity), the effects of particulate matter concentration, organic matter concentration and form, and salinity on the migration of trace elements in water were analyzed. As a result, a series of new results and understandings were obtained:
(1) Two methods for separating and detecting colloidal trace metals in natural water were established, and they were successfully applied to the sample detection.
First, a method based on cross-flow ultrafiltration (CFUF) and liquid-liquid extraction for the separation and determination of colloidal trace metals (1 kDa ~ 0.22 μm) in water was established. The detection limit of this method was: Cu 1.18 pmol L-1; Cd 0.68 pmol L-1; Pb 0.13 pmol L-1. The method had a good recovery for three metals with an enrichment factor of 40. This method has been successfully applied to the separation and detection of colloidal Cu, Cd and Pb in actual samples from the North Yellow Sea. Second, a method was developed for the separation and determination of colloidal Cd, Cu and Pb in water by a combination of centrifugal ultrafiltration (CUF), acid extraction and ICP-MS. By adjusting the centrifugation time and centrifugal force, colloidal Cu, Cd and Pb with different molecular weights in water samples could be effectively separated within 70 minutes. Besides, the method had a low detection limit of 0.005 ~ 0.131 nmol L-1 and recoveries of 85.3% ~ 100.8%. A membrane calibration experiment was also performed.
(2) In this study, CFUF units with regenerated cellulose membranes of 1, 3 and 10 kDa nominal pore size, respectively, were used for the size fractionation of the coastal water samples of the North Yellow Sea, and then combined with liquid-liquid extraction and ICP-MS to enrich and measure the trace elements. The results showed that the concentration of colloidal Cd (1 kDa ~ 0.22 μm) in the two coastal water sites of the North Yellow Sea were 0.098 and 0.037 nmol L-1, the concentration of colloidal Cu were 5.35 and 5.19 nmol L-1, and the concentration of colloidal Pb were 2.75 and 8.20 nmol L-1, which accounted for 30.9% ~ 50.8% of their respective total dissolved pools. In addition, the 1 ~ 10 kDa may be the key fraction of the migration process for Cd, Cu and Pb in the coastal ecosystem, and the main factor affecting the migration of trace metals among the fractions with different molecular weight range, e.g. <1 kDa, 1 ~ 3 kDa, 3 ~ 10 kDa, and 10 kDa ~ 0.22 μm, may not be simply the change of their total dissolved concentration.
<1 kDa Cd, Cu and Pb accounted for 58.1% to 90.2% of their total dissolved state, the colloidal Cd concentrations were 0.02 ~ 0.05 nmol L-1, the colloidal Cu concentrations were 0.24 ~ 6.88 nmol L-1 and colloidal Pb concentrations were 0.23 ~ 1.11 nmol L-1 among the 6 stations in the urban river system of Yantai City. Cd and Pb were more likely to bind with 10 kDa ~ 0.22 μm colloids, while Cu was more likely to be associated with 1 ~ 3 kDa low molecular weight colloids. The addition behavior of dissolved Cd in the lower salinity zone involved the formation of Cl-complexes and desorption or degradation of particulate matters, and this addition is more pronounced in winter and is strongly correlated with the 1 ~ 10 kDa colloids. The removal behaviors of 1 ~ 10 kDa Cd in the Guangdang estuary could be attributed to the coagulation/flocculation of the colloid. As for Cu, the removal behaviors in the Guangdang estuary may be the reduction of strong Cu-ligands and the coagulation/flocculation of colloids, and the intriguing additions in the Xinan estuary may be the reason for the strong Cu-ligands introduced into the water by sediments. As a metal with strong correlation with Fe-oxides, removal behaviors of Pb at the two estuaries are significantly controlled by the coagulation/flocculation of Fe-oxides.
(3) The biogeochemical behaviors of 7 trace elements in the waters of the Muping marine pasture were characterized, and the comprehensive influence of various environmental factors in the area affected by human activities on the migration of trace metals in water was examined. The established CUF method was used to study the 7 trace elements in the surface water of this area, and the correlation between the five dissolved fractions (namely <1 kDa truly dissolved phase and 1 ~ 3 kDa, 3 ~ 10 kDa, 10 ~ 100 kDa and 100 kDa ~ 0.7 μm colloidal phases) and various environmental parameters were studied. The results showed that the 7 colloidal target elements were mainly dominated by macromolecules of 100 kDa ~ 0.7 μm in September. In November, the colloidal Cu, Cd and Pb in the study area were still dominated by 100 kDa ~ 0.7 μm colloids, Ca and Mn were mainly related to 10 ~ 100 kDa, Al and Fe were mainly related to 1 ~ 3 kDa. From the correlation between target elements and environmental factors, significant differences were found in the correlation between different grades of Al, Ca, Mn, Fe, Cu, Cd, Pb and different types of nutrients. The water temperature in September was higher than that in November. The reduction in nutrient concentrations caused by the rapid growth and reproduction of phytoplankton makes it significantly related to the bioavailable metals such as Fe and Mn. The lower temperature in November was not conducive to the growth and mass reproduction of phytoplankton, and the resulting low biomass and the reduced contribution of organic matter to the colloidal ligands had caused overall decreases in the proportion of colloidal metals. In addition, organophilic metals such as Cd and Pb showed significant correlations with inorganic factors (such as Si and P) in the study area, indicating that their sources were not only a single organic source. Inorganic ligands released by the resuspension of sediments caused by wind waves and ocean currents may also affect the spatial and size distribution of the colloidal Cd and Pb.
(4) The established CUF method was used to study the seven trace elements in the surface water of the YRE, and the correlation between the four dissolved fractions (namely <1 kDa truly dissolved phase and 1 ~ 3 kDa, 3 ~ 10 kDa and 10 kDa ~ 0.7 μm colloidal phases), particulate matter and organic matter were studied. Al, Mn, Fe, Cu, Cd, and Pb were related to colloids with a size of 10 kDa ~ 0.7 μm, while dissolved Ca was related to colloids with 3 ~ 10 kDa colloids in the wet season and 10 kDa ~ 0.7 μm in the dry season. The sources of colloidal Cu, Cd and Pb in the dry season may be mainly terrestrial input; the concentration of colloidal Ca in both seasons had significant negative correlations with the concentration of suspended particulate matter, indicating that the main source of colloidal Ca ligands may come from the desorption of the particle surface; The migration of colloidal Pb in the four dissolved fractions was mainly affected by the dissolved organic matter in the water, while the particulate matter had a greater effect on the colloidal Ca.|