Thermoluminescence of quartz and feldspar sand grains as a tracer of nearshore environmental processes in the Southeastern Mediterranean Sea
Thermoluminescence of quartz and feldspar sand grains as a tracer of nearshore environmental processes in the Southeastern Mediterranean Sea
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作者：
W. Rink
沉积物是在以色列海岸的18个地点收集的，水深约1米。淹没的沉积物被直接放入不透明的袋子中，以保护它们免受阳光的直接照射。为了确定在近岸运输的石英砂和长石砂颗粒中自然残余TL （NRTL）的大小，在低强度橙色光照下对其进行了分离，并用热释光（TL）发射检测系统进行了研究。在尼罗河三角洲，石英和长石砂的NRTL特征随其原生源向北距离的增加而减弱。与这一趋势不同的是，位于特拉维夫北部的Herzliyya的NRTL大幅增加，这似乎表明，在Jaffa和Herzliyya之间的沿岸层积中增加了具有高NRTL的沉积物，这表明NRTL有可能用于追踪携带较大NRTL的沉积物的运输和分布。这种砂的可能来源是疏浚的沉积物，这些沉积物是从较老的沉积物沉积物中取出的，这些沉积物没有暴露在长时间的太阳照射下，也没有自然侵蚀类似的较老沉积物到沿岸的河床上。相比之下，Herzliyya的NRTL大幅增加也可能是由于在特拉维夫近海建造海滩平行石桩而阻碍了尼罗河砂的北岸运输的结果。
Sediments were collected just offshore at approximately 1m water depth at eighteen locations along the coast of Israel. Submerged sediments were placed directly into opaque bags to protect them from direct sunlight exposure. Quartz and feldspar sand grains were separated in low-level orange lighting and studied with a thermoluminescence (TL) emission detection system in order to determine the size of the natural residual TL (NRTL) in grains which were in transport in the nearshore. Patterns of NRTL in both quartz and feldspar sand grains show a trend of decreasing intensity with increasing northerly distance from their primary source at the Nile Delta. A departure from this trend, characterized by a strong increase in the NRTL at Herzliyya located just north of Tel Aviv, seems to suggest the addition of sediment with high NRTL into the littoral bedload between Jaffa and Herzliyya, demonstrating the likelihood that NRTL can be used to trace the transport and distribution of sediments carrying larger NRTL. Possible sources for this sand are dredged sediments which are removed from older sediment deposits which have not been exposed to significantly long solar exposures or natural erosion of similar older deposits into the littoral bedload. In contrast the strong increase of NRTL at Herzliyya could also be the result of blockage of the northerly longshore transport of Nile sand due to the construction of the beach parallel stone piles just offshore at Tel Aviv.