Mid- to late-Holocene coastal environmental changes in southwest Florida, USA
Mid- to late-Holocene coastal environmental changes in southwest Florida, USA
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美国佛罗里达州西南部全新世中晚期沿海环境变化
DOI：
10.1177/0959683611434226
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
G. Reichart
中科院分区：
文献类型：
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作者：
EE van Soelen;G. Brooks;R. Larson;J. Sinninghe Damsté;G. Reichart
在全新世，佛罗里达经历了降水和径流的重大变化。为了更好地了解这些过程，从夏洛特港（西南佛罗里达）的浅海沉积物岩心进行了研究，涵盖了大约9000年。应用全柱样XRF扫描技术对一条河流-海洋断面上不同沉积物柱样进行了对比。生物标志物被用来确定增加径流和初级生产力的时期。中全新世沉积物的特点是相对较大的输入陆源有机质，最大的降水和径流约5万年BP。这一最大值可能与水文循环的大规模变化有关，涉及ITCZ、亚速尔群岛高压和极锋的变化。大约3.5 kyr BP，夏洛特港从径流为主的环境转变为更贫营养和海洋环境。尽管其他研究表明，在这段时间，佛罗里达的降水量增加了，但这并没有反映在夏洛特港的记录中。可能是佛罗里达由于海平面逐渐上升和降水量增加而导致的更潮湿的条件导致了陆地上有机物质的积累。在记录上部观察到的沉积速率、陆地输入和初级生产力的增加可能是上世纪人类影响的结果。在整个记录中，风暴活动的迹象可以被认为是由石英砂或贝壳碎片组成的粗粒层。这些地层在全新世中期是罕见的，但在3.2和2 kyr BP之间，它们的数量增加，这表明墨西哥湾的热带气旋活动增加。
During the Holocene, Florida experienced major changes in precipitation and runoff. To better understand these processes, shallow marine sediment cores from Charlotte Harbor (southwest Florida) were studied, covering approximately the past 9000 years. Whole core XRF scanning was applied to correlate different sediment cores on a river to sea transect. Biomarkers were used to identify periods with increased runoff and primary productivity. The mid-Holocene sediments are characterized by a relatively large input of terrestrially derived organic matter, with a maximum in precipitation and runoff around 5 kyr BP. This maximum can be linked to large-scale changes in the hydrological cycle involving shifts of the ITCZ, Bermuda-Azores High and Polar Front. Around 3.5 kyr BP, Charlotte Harbor changed from a runoff-dominated environment to a more oligotrophic and marine setting. Although other studies suggest that, around this time, precipitation in Florida increased, this is not reflected by the Charlotte Harbor records. Possibly, wetter conditions in Florida due to gradual, ongoing, sea level rise in combination with increased precipitation, resulted in accumulation of organic matter on land. Increased sedimentation rates, terrestrial input and primary productivity observed in the upper part of the record are likely a consequence of human impact during the past century. Throughout the record, indications for storm activity can be recognized as coarser grained layers consisting of quartz sands or shell debris. These layers are rare during the mid Holocene, but between 3.2 and 2 kyr BP, their numbers increase, suggesting an increase in tropical cyclone activity in the Gulf of Mexico.