Characteristics of suspended flocs and the combined action of contributing factors in Yangtze Estuary: A case study on the significant differences between the inner estuary and the mouth area
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摘要: 絮凝对河口细颗粒悬沙运动起着极其重要的作用.为深入探讨长江口悬浮絮凝体的特征及其主要影响因子的综合作用,于2014年10月19-23日(长江口径流量、潮差、风浪均接近多年平均值)利用多种仪器在人类活动干扰较小的南支-北港-口外海滨水域进行了综合现场观测和取样,获得了四个潮流特征时刻(涨急、涨憩、落急、落憩)的悬浮絮凝体粒径、分散粒径(即分散悬沙的原始粒径)、悬沙浓度、体积浓度、流速流向、盐度等数据.利用灰色关联度分析方法分析五大影响因子(悬沙浓度、体积浓度、流速、盐度和分散粒径)对絮凝体粒径和有效密度影响程度.结果表明,在相同体积水体中,口门最大浑浊带测点的絮凝体相对口内河槽测点数量多、粒径小,絮凝体内粘土颗粒少、空隙大、自由水多.在口内河槽,絮凝体粒径主要受悬沙浓度、分散粒径和体积浓度控制,有效密度主要受到分散粒径、悬沙浓度和流速控制;在口门最大浑浊带,絮凝体粒径的主控因子是流速,有效密度主要受到盐度、悬沙浓度控制.Abstract: Flocculation plays a vital role in the transport of estuarine fine suspended sediments. To study the natural situation and the main influencing factors of fine suspended sediment flocculation, in-situ observations were carried out along the South Branch to the North Channel of the Yangtze Estuary from 19th to 23th October 2014 (During that time, river discharge, tidal range and wind waves have same value to annual mean value). Floc size, dispersed particle size, volume concentration (VC), suspended sediment concentration (SSC), salinity, temperature and flow velocities were measured at four characteristic moments at four sites. We study the relation between median floc size, as well as effective density, and the five influencing factors with the Grey relational analysis.The results shows that, in the same water volume, flocs in the Turbidity Maximum Zone has more floc numbers and smaller floc size; that floc inside has less clay particles, larger gap and more free water compare to the inner estuary. In the inner estuary, critical factors influencing floc sizes are SSC, dispersed particle size, VC, and critical factors influencing effective density were dispersed particle size, SSC, velocity. In the Turbidity Maximum Zone of the mouth area, the critical factor influencing floc sizes is velocity and the critical factors influencing effective density are salinity and SSC.
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Key words:
- suspended flocs /
- influencing factors /
- grey relational analysis /
- Yangtze Estuary
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图 3 长江口4个测点4个特征时刻时絮凝体中值粒径(a)、分散中值粒径(b)、悬沙浓度(c)、体积浓度(d)、有效密度(e)的剖面平均值
Fig. 3 The vertical average value of the floc median sizes (a), single particle median sizes (b), suspended sediment concentrations (SSC)(c), volume concentrations (VC)(d) and effective densities (e) in the four characteristic moment at the four observation sites in Yangtze Estuary
表 1 现场观测所用仪器及其观测项目
Tab. 1 Observation instruments and measured parameters
仪器名称 采样频率 观测项目 LISST-100现场激光粒度仪 1Hz 絮凝体粒级分布 OBS-3A光学后向散射浊度计 1Hz 浊度、盐度 Valeport-106自容点式流速仪 1Hz 表层流速 ADCP-300k多普勒流速剖面仪 0.1Hz 剖面流速、流向 -
[1] 钱宁, 万兆慧.泥沙运动力学[M].北京:科学出版社, 1983: 45-108. [2] STERNBERG R W, BERHANE I, OGSTON A S. Measurement of size and settling velocity of suspended aggregates on the northern California continental shelf[J]. Marine Geology, 1999, 154(1-4): 43-53. doi: 10.1016/S0025-3227(98)00102-9 [3] MIKKELSEN O, PEJRUP M. The use of a LISST-100 laser particle sizer for in-situ estimates of floc size, density and settling velocity[J]. Geo-Marine Letters, 2001, 20(4): 187-195. doi: 10.1007/s003670100064 [4] 程江, 何青, 王元叶.利用LISST观测絮凝体粒径、有效密度和沉速的垂线分布[J].泥沙研究, 2005(1): 33-39. http://www.cnki.com.cn/Article/CJFDTOTAL-NSYJ200501006.htm [5] DYER K R, MANNING A J. Observation of the size, settling velocity and effective density of flocs, and their fractal dimensions[J]. Journal of Sea Research, 1999, 41(1-2): 87-95. doi: 10.1016/S1385-1101(98)00036-7 [6] FUGATE D C, FRIEDRICHS C T. Determining concentration and fall velocity of estuarine particle populations using ADV, OBS and LISST[J]. Continental Shelf Research, 2002, 22(11/12/13): 1867-1886. https://www.researchgate.net/publication/223603344_Determining_concentration_and_fall_velocity_of_estuarine_particle_populations_using_ADV_OBS_and_LISST [7] WINTERWERP J C, BALE A J, CHRISTIE M C, et al. Flocculation and settling velocity of fine sediment[J]. Proceedings in Marine Science, 2002(5): 25-40. http://www.sciencedirect.com/science/article/pii/S1568269202800067 [8] 沈焕庭, 贺松林, 潘定安, 等.长江河口最大浑浊带研究[J].地理学报, 1992(5): 472-479. http://cdmd.cnki.com.cn/Article/CDMD-10269-1015348138.htm [9] CHEN S, EISMA D, KALF J. In situ distribution of suspendedmatter during the tidal cycle in the elbe estuary[J]. Netherlands Journal of Sea Research, 1994, 32(1): 37-48. doi: 10.1016/0077-7579(94)90026-4 [10] FENNESSY M J, DYER K R. Floc population characteristics measured with INSSEV during the Elbe estuary intercalibration experiment[J]. Journal of Sea Research, 1996, 36(1-2): 55-62. http://www.sciencedirect.com/science/article/pii/S1385110196907716 [11] MANNING A J, SCHOELLHAMER D H. Factors controlling floc settling velocity along a longitudinal estuarine transect[J]. Marine Geology, 2013, 345(6): 266-280. http://ca.water.usgs.gov/pubs/2013/ManningSchoellhamer2013.pdf [12] BALE A J, MORRIS A W. In situ, measurement of particle size in estuarine waters[J]. Estuarine Coastal & Shelf Science, 1987, 24(2): 253-263. http://linkinghub.elsevier.com/retrieve/pii/0272771487900680 [13] WANG Y P, VOULGARIS G, LI Y, et al. Sediment resuspension, flocculation, and settling in a macrotidal estuary[J]. Journal of Geophysical Research Oceans, 2013, 118(10): 5591-5608. doi: 10.1002/jgrc.20340 [14] VOULGARIS G, MEYERS S T. Temporal variability of hydrodynamics, sediment concentration and sediment settling velocity in a tidal creek[J]. Continental Shelf Research, 2004, 15(15): 1659-1683. https://www.researchgate.net/publication/222070043_Temporal_variability_of_hydrodynamics_sediment_concentration_and_sediment_settling_velocity_in_a_tidal_creek [15] 唐建华, 何青, 王元叶, 等.长江口浑浊带絮凝体特性[J].泥沙研究, 2008(2): 27-33. http://www.cnki.com.cn/Article/CJFDTOTAL-NSYJ200802004.htm [16] 李九发, 戴志军, 刘启贞, 等.长江河口絮凝泥沙颗粒粒径与浮泥形成现场观测[J].泥沙研究, 2008(3): 26-32. http://www.cnki.com.cn/Article/CJFDTOTAL-NSYJ200803003.htm [17] 邓聚龙.灰色系统基本方法[M].武汉:华中理工大学出版社, 1987: 17-42. [18] 谭学瑞, 邓聚龙.灰色关联分析:多因素统计分析新方法[J].统计研究, 1995(3):46-48. http://www.cnki.com.cn/Article/CJFDTOTAL-TJYJ503.010.htm [19] 蒋国俊, 姚炎明, 唐子文.长江口细颗粒泥沙絮凝沉降影响因素分析[J].海洋学报, 2002, 24(4): 51-57. http://www.cnki.com.cn/Article/CJFDTOTAL-SEAC200204005.htm [20] IPWC, HU B Q, WONG H, et al. Applications of grey relational method to river environment quality evaluation in China[J]. Journal of Hydrology, 2009, 379(3): 284-290. http://www.cabdirect.org/abstracts/20103008005.html?gitCommit=4.13.20-5-ga6ad01a [21] WANG Q, LIU J, ZHU X, et al. The experiment study of frost heave characteristics and gray correlation analysis of graded crushed rock[J]. Cold Regions Science & Technology, 2016, 126: 44-50. https://www.deepdyve.com/lp/elsevier/the-experiment-study-of-frost-heave-characteristics-and-gray-YMeEBdUYwo [22] YAN F, QIAO D, QIAN B, et al. Improvement of CCME WQI using grey relational method[J]. Journal of Hydrology, 2016, 543: 316-323. doi: 10.1016/j.jhydrol.2016.10.007 [23] 陈吉余.长江河口动力过程和地貌演变[M].上海:上海科学技术出版社, 1988: 1-5. [24] YANG S L, ZHAO Q Y, BELKIN I M.Temporal variation in the sediment load of the Yangtze River and the influences of the human activities [J].Journal of Hydrology, 2002, 263(1): 56-71 https://www.researchgate.net/publication/223480222_Temporal_variation_in_the_sediment_load_of_the_Yangtze_River_and_the_influences_of_human_activities [25] 王如生, 杨世伦, 罗向欣, 等.近30年长江北支口门附近的冲淤演变及其对人类活动的响应[J].华东师范大学学报(自然科学版), 2015(4): 34-41. http://xblk.ecnu.edu.cn/CN/abstract/abstract25207.shtml [26] 谢火艳, 王如生, 张国安, 等.长江口北槽沉积物的粒度特征和输运趋势探讨[J].上海国土资源, 2016, 37(2): 84-88. http://www.cnki.com.cn/Article/CJFDTOTAL-SHAD201602020.htm [27] 恽才兴.长江河口近期演变基本规律[M].北京:海洋出版社, 2004: 289-290. [28] LIU J H, YANG S L, ZHU Q, et al. Controls on suspended sediment concentration profiles in the shallow and turbid Yangtze Estuary[J]. Continental Shelf Research, 2014, 90: 96-108. doi: 10.1016/j.csr.2014.01.021 [29] 水利部长江水利委员会.长江泥沙公报[M].武汉:长江出版社, 2015: 3-4. [30] YANG S L, XU K H, MILLIMAN J D, et al. Decline of Yangtze River water and sediment discharge: Impact from natural and anthropogenic changes[J]. Scientific reports, 2015(5): 1-13. https://www.researchgate.net/profile/Shilun_Yang/publication/281819796_Decline_of_Yangtze_River_water_and_sediment_discharge_Impact_from_natural_and_anthropogenic_changes/links/55fc374308aeafc8ac43a914.pdf?inViewer=true&pdfJsDownload=true&disableCoverPage=true&origin=publication_detail [31] 武小勇, 茅志昌, 虞志英, 等.长江口北港河势演变分析[J].泥沙研究, 2006(2): 46-53. http://cdmd.cnki.com.cn/Article/CDMD-10269-1015351343.htm [32] 国家海洋局东海预报中心. 上海市沿海海洋预报[EB/OL]. (2014-10-19)[2014-10-23]. http://www.dhybzx.org/linebreakOceanPortal/pages/yubao/yanhaiyubao. html. [33] 方强飞, 赵书河, 周艳霞.近十年来长江口九段沙周边地貌演变GIS分析[J].测绘与空间地理信息, 2014(11): 90-93.. doi: 10.3969/j.issn.1672-5867.2014.11.026 [34] YANG S L, LI P, GAO A, et al. Cyclical variability of suspended sediment concentration over a low-energy tidal flat in Jiaozhou Bay, China: effect of shoaling on wave impact[J]. Geo-Marine Letters, 2007, 27(5): 345-353. doi: 10.1007/s00367-007-0058-2 [35] 张文祥, 杨世伦. OBS浊度标定与悬沙浓度误差分析[J].海洋技术, 2008, 27(4): 5-8. http://www.cnki.com.cn/Article/CJFDTOTAL-HYJS200804005.htm [36] 韩胜娟. SPSS聚类分析中数据无量纲化方法比较[J].科技广场, 2008(3): 229-231. http://www.cnki.com.cn/Article/CJFDTOTAL-KJIG200803089.htm [37] 阮文杰.细颗粒泥沙动水絮凝的机理分析[J].海洋科学, 1991, 15(5): 46-49. http://www.cnki.com.cn/Article/CJFDTOTAL-HYKX199105017.htm [38] 王保栋.河口细颗粒泥沙的絮凝作用[J].海洋科学进展, 1994(1): 71-76. http://www.cnki.com.cn/Article/CJFDTOTAL-HBHH401.008.htm [39] 严肃庄, 曹沛奎.长江口悬浮体的粒度特征[J].上海国土资源, 1994(3): 50-58. http://www.cnki.com.cn/Article/CJFDTOTAL-HYFZ200305004.htm [40] 金鹰, 王义刚, 李宇.长江口粘性细颗粒泥沙絮凝试验研究[J].河海大学学报, 2002, 30(3): 61-63. http://cdmd.cnki.com.cn/Article/CDMD-10269-2007081403.htm [41] 陈庆强, 孟翊, 周菊珍, 等.长江口细颗粒泥沙絮凝作用及其制约因素研究[J].海洋工程, 2005, 23(1): 74-82. http://www.cnki.com.cn/Article/CJFDTOTAL-HYGC200501012.htm