北部湾悬浮颗粒现场剖面测量与粒度分析

In-situ profiling of suspended particles in the Beibu Gulf and analysis of grain size

应用LISST-100现场激光粒度仪于2006年8月在北部湾首次进行了悬浮颗粒剖面测量,获得了整个垂直剖面的悬浮颗粒现场粒径分布、体积比和光衰减系数,并计算得到了垂直剖面的总浓度和各层的粒度参数及粒级组成。结果表明,悬浮颗粒自上而下均为双峰分布,只是表层的双峰位于5.57μm和34.4μm,中间层和底层的双峰位于34.4μm和129.4μm。悬浮颗粒体积比自上而下逐渐增大,到达底层时达到最大。光衰减系数的变化趋势与颗粒体积比非常相似,且二者存在很好的相关性,相关系数高达0.98。整个垂直剖面上,表层粒度较细,随着深度增加粒度逐渐变粗,到达底层时粒度最粗。悬浮体总体上正偏,峰态值较小,分选较差。粒度以砂为主,粉砂含量次之,不含黏土。

A laser in-situ scattering transmissiometry （Lisst-100） was first used to make a profiling of suspended sediment in the Beibu Gulf in August 2006, and the grain size distribution, volume concentration and light attenuation coefficient were obtained. Further, the total concentration, grain size parameters and grain composition were calculated. The results show that the size distribution from surface to bottom is bimodal, and the surface peaks appear at 5.57 μm and 34.4 μm; the peaks of the middle layer and bttcom at 34.4μm and 129.4μm. The concentration increases with the increase of the depth, and is the biggest at the bottom. The tendency of light attenuation coefficient is very similar to that of the concentration, and between them there is a good correlation with the correlation coefficient up to 0.98, from which it is concluded that the light attenuation is mainly caused by the scattering of suspended sediment of grain size 1-250μm. Grain size analysis shows that the size increases with the increase of the depth. The suspended sediment consists of sand and silt, relatively poorly sorted with positive skewness and small kurtosis values.