湛江东海岛潮间带表层沉积物粒度的分布及与环境要素的相关性

Grain size distribution of surface sediments and its correlation with environmental factors in intertidal flat of Donghai Island,Zhanjiang

于2011年7月对湛江东海岛潮间带表层沉积物粒度及沉积环境要素进行了调查和分析.结果表明,东海岛潮间带表层沉积物可分为4种类型,即砂、粉砂质砂、砂质粉砂、粘土质粉砂,砂和粉砂质砂是东海岛潮间带沉积物主要类型.其中,湛江湾区（Ⅰ区）、龙海天区（Ⅱ区）、雷州湾区（Ⅲ区）等3区的主要沉积类型是砂,粉砂是通明海区（Ⅳ区）的主要沉积类型.东海岛各区潮间带表层沉积物平均粒径在0.023~0.342 mm（1.55~5.46φ）之间,平均值为0.092 mm（3.45φ）,各潮区颗粒大小总体表现为高潮区〉中潮区〉低潮区,且从西部东海大堤两侧的较小值沿东海岛南北两侧逐渐增大为东区的较大值.东海岛龙海天潮间带表层沉积物分选程度为中等至差之间,包含了从显著负偏态至正偏态的大多数类型,峰态多为宽平型和尖锐型.东海岛各区潮间带表层沉积物类型及其粒度分布特征是该岛沿岸潮流动力环境差异的直接体现,并直接影响沉积区的理化性质,表现为在沉积颗粒大的沉积区p H和CFe3＋/CFe2＋较高、有机物和硫化物含量较低,沉积颗粒较小的区域各环境因子变化规律相反.

In July,2011,the grain size and environmental factors of surface sediments were surveyed in intertidal flat of Donghai Island,Zhanjiang. It was showed in the results that the samples can be classified into four types in grain size： sand,silty sand,sandy silt and clayey silt. Sand and silty sand were two important types in the studied areas. The main sedimentary type was sand in three areas： Zhanjiang Bay（ areaⅠ）,Longhaitian area（ areaⅡ）and Leizhou Bay（ area Ⅲ）. The silty sand was the main type in Tongminghai area（ area Ⅳ）. The mean grain sizeof surface sediments was between 0. 023 mm and 0. 342mm（ 1. 55 - 5. 46φ） with an average of 0. 092mm（ 3. 45φ） at all sampling sites. As a whole,the grain size of intertidal sediments decreased gradually from high tidal region to low tidal region,and creased slowly from the west areas to the east along the south and north sides of Donghai Island. Most intertidal sediments were in a sorting state from the middle degree to the worse degree,and of skewed types from notable negative skewness to positive skewness. Most probability cumulative curves of grain size belonged to flat-type and sharp-type peaks. The sedimentary types and distribution characteristics of grain size embodied truly the dynamical differences of tidal current in different intertidal areas of Donghai Island,and impacted directly on the physical and chemical properties of sedimentary areas. Consequently in intertidal flats of Donghai Island,the bigger the grain size,the higher p H and CFe3 ＋/ CFe2 ＋,and the lower TOC and AVS contents. The environmental factors above-mentioned showed that the contrary changed the rules when the grain size was smaller.