海南岛陵水新村港表层沉积物无机碳分布特征及其指示意义

DISTRIBUTION OF INORGANIC CARBON CHARACTERISTICS AND ITS SIGNIFICANCE IN THE SURFICIAL SEDIMENT OF XINCUN LAGOON, LINGSHUI, HAINAN ISLAND

新村港位于海南省陵水县东南部,面向南海,是海南岛不可多得的天然避风港,同时新村港是一个为潮汐所控制的近封闭状的天然潟湖.本文在海南陵水新村港采集33个表层沉积物,同时,在各站位使用多参数水质仪（YSI）测量了水层的水温、pH值数据,通过对海南陵水新村港的表层沉积物的粒度分析和无机碳数据分析,研究了该地区表层沉积物无机碳的特征及其指示意义.结果表明,新村港的平均粒径是在0.8～7.9φ之间波动,平均值为4.4φ,湾内粒径较细并向岸边逐渐变粗;分选系数是在1.1～2.5之间波动,平均值为1.8,分选较差.同时研究表明温度、pH值以及人类活动都对新村港的无机碳含量产生影响.新村港的无机碳含量具有北部高、西部低,湾内高、口门低的特点.其高值区出现在湾内以北的水域,最大值可达10.6％,并随着离口门距离的减小而逐渐降低;低值区出现在研究区的西部及其南部,梯度变化较小.其最大值十分接近于珊瑚礁的碳酸钙的无机碳含量（12％）,说明在湾内表层沉积物中珊瑚礁碎屑是主要成分,主要来自附近的珊瑚礁平台.

The Xincun lagoon is located in the southeast part of Lingshui County, Hainan Island, where it is tides controlled, nearly closed, open to the South China Sea. This study reveals the distribution characteristics of inorganic carbon and its significance based on 33 surfieial sediment samples collected in the lagoon with the analysis of inorganic carbon content and grain size, and the data of water temperature, pH measured by YSI in the same sites. The results show that the value of mean grain size is between 0.8φ and 7.9φ with the average of 4.4φ. The value of sorting coefficient is between 1.1 and 2.5 with the average of 1.8, indicating poorly sorted. From the middle part of the lagoon to the shoreline, it is coarser gradually. The inorganic carbon contents are relatively high in the northern part and low in the western part of the lagoon; they are relatively high inside the lagoon, low in the entrance channel. A maximum value is up to 10.6% occurred in the northern part of the lagoon which is very close to the inorganic carbon values of calcium carbonate （i.e., 12% ）. They decrease gradually toward to the mouth. This may indicate that the major surficial deposit is reef debris in the northern part of the lagoon so that the source of inorganic carbon is mainly from the adjacent coral reef platforms.