A series of laboratory incubation experiments were conducted to examine the decomposition of algal organic matter in clay-enriched marine sediment under oxic and anoxic conditions. During the 245-day incubation period...A series of laboratory incubation experiments were conducted to examine the decomposition of algal organic matter in clay-enriched marine sediment under oxic and anoxic conditions. During the 245-day incubation period, changes in the concentrations of TOC, major algal fatty acid components （14：0, 16：0, 16：1, 18：1 and 20：5）, and n-alkanes （C16-C23） were quantified in the samples. Our results indicate that the organic matters were degraded more rapidly in oxic than anoxic conditions. Adsorption of fatty acids onto clay minerals was a rapid and reversible process. Using a simple G model, we calculated the decomposition rate constants for TOC, n-alkanes and fatty acids which ranged from 0.017-0.024 d^-1, 0.049-0.103 d^-1 and 0.011 to 0.069 d-l, respectively. Algal organic matter degraded in two stages characterized by a fast and a slow degradation processes. The addition of clay minerals montmorillonite and kaolinite to the sediments showed significant influence affecting the decomposition processes of algal TOC and fatty acids by adsorption and incorporation of the compounds with clay particles. Adsorption/association of fatty acids by clay minerals was rapid but appeared to be a slow reversible process. In addition to the sediment redox and clay influence, the structure of the compounds also played important roles in affecting their degradation dynamic in sediments.展开更多
With the development of modern industry and the increase of human demand, it is increasingly important to prospect and exploit marine mineral resources. Based on the oceanic geological investigation references obtaine...With the development of modern industry and the increase of human demand, it is increasingly important to prospect and exploit marine mineral resources. Based on the oceanic geological investigation references obtained from the regional geological surveying and mapping of China Sea (“Shantoufu, F 50” 1∶1 000 000) and on the data (“Marine Engineering Geological Investigation Project in the Pearl River Mouth basin in the South China Sea” 1∶200 000), the authors elaborate the grain size composition, mineral composition, mineral features and distribution pattern of the surface sediments in the sea at 114°-120°E and 20°-24°N. Moreover, the analysis of the regional solid state mineral resources in the coast of Fujian, Guangdong and the west of Taiwan, shows that the main resources include littoral/neritic placers, littoral/neritic sandy gravel and ferromanganese nodule (crust). In addition, the future focus should be on the placers and sandy gravels in this littoral area.展开更多
Based on the analysis and mathematical statistics of quantitative data on both the heavy minerals and their REE (La, Ce, Nd, Sm, Eu, Tb, Yb, Lu), trace (Zr, Hf, Th, Ta, U, Rb, Sr, Zn, Co, Ni, Cr, As, Sc) and major (Fe...Based on the analysis and mathematical statistics of quantitative data on both the heavy minerals and their REE (La, Ce, Nd, Sm, Eu, Tb, Yb, Lu), trace (Zr, Hf, Th, Ta, U, Rb, Sr, Zn, Co, Ni, Cr, As, Sc) and major (Fe) elements in the surface sediments in the northwestern sea area of Antarctic Peninsula, the authors find that the heavy minerals as the carriers of REE and trace elements should not be overlooked.Q-mode factor analysis of the heavy minerals provides a 3-factor model of the heavy mineral assemblages in the study area, which is mainly controlled by the origin of materials and sea currents. The common factor P1, composed mainly of pyroxene and metal minerals, and common factor P2, composed of hornblende, epidote and accessory minerals, represent two heavy mineral assemblages which are different from each other in both lithological characters and origin of materials. And common factor P3 probably results from mixing of two end members of the above-mentioned assemblages. R-mode group analysis of the heavy minerals indicates that there are two heavy mineral groups in the sea area, which are different from each other in both genesis and origin of materials. With the help of R-mode analysis, 22 elements are divided into 3 groups and 9 subgroups. These element assemblages show that they are genetically related and that they are different in geochemical behaviors during diagenesis and mineral-forming process. In addition, the relationship between the heavy mineral assemblages and the element subgroups is also discussed.展开更多
通过分析测定南海北部湾中东部海底柱状沉积物的主量、微量元素和矿物组成,结合AMS^(14)C定年,研究了11.3 ka BP以来该海域全新世沉积地球化学特征及其对物源和海洋环境变化的指示意义。结果表明,剖面以86 cm为界限,大部分主量、微量元...通过分析测定南海北部湾中东部海底柱状沉积物的主量、微量元素和矿物组成,结合AMS^(14)C定年,研究了11.3 ka BP以来该海域全新世沉积地球化学特征及其对物源和海洋环境变化的指示意义。结果表明,剖面以86 cm为界限,大部分主量、微量元素含量呈现明显的上、下两阶段变化特征,分别为3.2~0.2 ka BP的上部沉积层段(86~4 cm)和11.3~3.2 ka BP的下部沉积层段(200~86 cm),其中Si、Ca、Zr等元素含量在上部层段沉积物中显著减少,而A1、Fe、Ti、V、Cr、Co等元素含量明显升高,稀土元素含量变化不明显。此外,剖面中的矿物组成主要为石英、伊利石、绿泥石和长石。相比于下部层段,上部层段中绿泥石含量更高、长石含量更低。综合来看,沉积物物源输入比较稳定,主要来自周边海岸侵蚀产物和琼州海峡的下切侵蚀产物,其次是红河和珠江携带的沉积物。剖面上、下层段沉积物中元素和矿物含量的差异主要与3.2 ka BP以来,高海平面下琼州海峡进一步扩张引起的海底下沉和海水深度增加有关,从而导致上部沉积时期水动力较弱,黏土矿物含量增加。展开更多
基金Supported by the National Natural Science Foundation of China (Nos. 40476038 and 40576039)
文摘A series of laboratory incubation experiments were conducted to examine the decomposition of algal organic matter in clay-enriched marine sediment under oxic and anoxic conditions. During the 245-day incubation period, changes in the concentrations of TOC, major algal fatty acid components （14：0, 16：0, 16：1, 18：1 and 20：5）, and n-alkanes （C16-C23） were quantified in the samples. Our results indicate that the organic matters were degraded more rapidly in oxic than anoxic conditions. Adsorption of fatty acids onto clay minerals was a rapid and reversible process. Using a simple G model, we calculated the decomposition rate constants for TOC, n-alkanes and fatty acids which ranged from 0.017-0.024 d^-1, 0.049-0.103 d^-1 and 0.011 to 0.069 d-l, respectively. Algal organic matter degraded in two stages characterized by a fast and a slow degradation processes. The addition of clay minerals montmorillonite and kaolinite to the sediments showed significant influence affecting the decomposition processes of algal TOC and fatty acids by adsorption and incorporation of the compounds with clay particles. Adsorption/association of fatty acids by clay minerals was rapid but appeared to be a slow reversible process. In addition to the sediment redox and clay influence, the structure of the compounds also played important roles in affecting their degradation dynamic in sediments.
文摘With the development of modern industry and the increase of human demand, it is increasingly important to prospect and exploit marine mineral resources. Based on the oceanic geological investigation references obtained from the regional geological surveying and mapping of China Sea (“Shantoufu, F 50” 1∶1 000 000) and on the data (“Marine Engineering Geological Investigation Project in the Pearl River Mouth basin in the South China Sea” 1∶200 000), the authors elaborate the grain size composition, mineral composition, mineral features and distribution pattern of the surface sediments in the sea at 114°-120°E and 20°-24°N. Moreover, the analysis of the regional solid state mineral resources in the coast of Fujian, Guangdong and the west of Taiwan, shows that the main resources include littoral/neritic placers, littoral/neritic sandy gravel and ferromanganese nodule (crust). In addition, the future focus should be on the placers and sandy gravels in this littoral area.
文摘Based on the analysis and mathematical statistics of quantitative data on both the heavy minerals and their REE (La, Ce, Nd, Sm, Eu, Tb, Yb, Lu), trace (Zr, Hf, Th, Ta, U, Rb, Sr, Zn, Co, Ni, Cr, As, Sc) and major (Fe) elements in the surface sediments in the northwestern sea area of Antarctic Peninsula, the authors find that the heavy minerals as the carriers of REE and trace elements should not be overlooked.Q-mode factor analysis of the heavy minerals provides a 3-factor model of the heavy mineral assemblages in the study area, which is mainly controlled by the origin of materials and sea currents. The common factor P1, composed mainly of pyroxene and metal minerals, and common factor P2, composed of hornblende, epidote and accessory minerals, represent two heavy mineral assemblages which are different from each other in both lithological characters and origin of materials. And common factor P3 probably results from mixing of two end members of the above-mentioned assemblages. R-mode group analysis of the heavy minerals indicates that there are two heavy mineral groups in the sea area, which are different from each other in both genesis and origin of materials. With the help of R-mode analysis, 22 elements are divided into 3 groups and 9 subgroups. These element assemblages show that they are genetically related and that they are different in geochemical behaviors during diagenesis and mineral-forming process. In addition, the relationship between the heavy mineral assemblages and the element subgroups is also discussed.
文摘通过分析测定南海北部湾中东部海底柱状沉积物的主量、微量元素和矿物组成,结合AMS^(14)C定年,研究了11.3 ka BP以来该海域全新世沉积地球化学特征及其对物源和海洋环境变化的指示意义。结果表明,剖面以86 cm为界限,大部分主量、微量元素含量呈现明显的上、下两阶段变化特征,分别为3.2~0.2 ka BP的上部沉积层段(86~4 cm)和11.3~3.2 ka BP的下部沉积层段(200~86 cm),其中Si、Ca、Zr等元素含量在上部层段沉积物中显著减少,而A1、Fe、Ti、V、Cr、Co等元素含量明显升高,稀土元素含量变化不明显。此外,剖面中的矿物组成主要为石英、伊利石、绿泥石和长石。相比于下部层段,上部层段中绿泥石含量更高、长石含量更低。综合来看,沉积物物源输入比较稳定,主要来自周边海岸侵蚀产物和琼州海峡的下切侵蚀产物,其次是红河和珠江携带的沉积物。剖面上、下层段沉积物中元素和矿物含量的差异主要与3.2 ka BP以来,高海平面下琼州海峡进一步扩张引起的海底下沉和海水深度增加有关,从而导致上部沉积时期水动力较弱,黏土矿物含量增加。
