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Lake Martin, Louisiana sediments as a record of geomorphology, paleoenvironment, and human activities
Journal of Paleolimnology ( IF 2.1 ) Pub Date : 2020-05-12 , DOI: 10.1007/s10933-020-00125-1
Aubrey L. Hillman , Scott St. Romain

There are relatively few lake sediment records from the southeastern United States that span sufficient time to characterize the environment prior to substantial anthropogenic disturbance. This has made it difficult to characterize the magnitude and timing of the impact of industrial human activities within the context of natural variability. The objective of this study was therefore to use weight percent organic matter, carbon to nitrogen ratios, carbon and nitrogen isotopes, and weakly bound lead concentrations from Lake Martin, a small oxbow lake in southern Louisiana, to (1) characterize natural variability in lake carbon and nitrogen cycling within the last several millennia in a vastly understudied region of the US and (2) assess the impact of recent human activities such as agriculture, land-use change, and industrial activities on the water and sediment quality of the lake. The basal sediments from Lake Martin are distinctive in color and character and likely derive from a large paleo-lake that catastrophically drained in the late Holocene. The last 1100 years of the record demonstrates a gradual transition from a system with moderate amounts of terrestrial materials to one dominated by aquatic organic matter likely due to the transition from a lotic to lentic system. Coincident with when the Acadians settled in the Lafayette area around 200 years ago, further changes are apparent in the sediment record, but do not display the hallmark signs of either land-use change or cultural eutrophication. This may be because lake levels are low and led to the efficient oxidation and recycling of organic matter.

中文翻译:

路易斯安那州马丁湖沉积物作为地貌、古环境和人类活动的记录

来自美国东南部的湖泊沉积物记录相对较少,它们跨越足够的时间来表征大量人为干扰之前的环境。这使得很难在自然变化的背景下描述工业人类活动影响的程度和时间。因此,本研究的目的是使用来自路易斯安那州南部小牛轭湖马丁湖的有机质重量百分比、碳氮比、碳和氮同位素以及弱结合铅浓度,以 (1) 表征湖泊中的自然变化过去几千年来在美国一个未被充分研究的地区的碳和氮循环,以及 (2) 评估近期人类活动(如农业、土地利用变化)的影响,和工业活动对湖水和沉积物质量的影响。马丁湖的基底沉积物在颜色和特征上都很独特,很可能来自于全新世晚期灾难性地干涸的大型古湖泊。过去 1100 年的记录表明,从含有适量陆地物质的系统逐渐过渡到以水生有机物质为主的系统,这可能是由于从激流系统到静水系统的转变。与大约 200 年前阿卡迪亚人在拉斐特地区定居的同时,沉积物记录出现了进一步的变化,但没有显示出土地利用变化或文化富营养化的标志性迹象。这可能是因为湖泊水位低,导致有机物的有效氧化和循环利用。马丁湖的基底沉积物在颜色和特征上都很独特,很可能来自于全新世晚期灾难性地干涸的大型古湖泊。过去 1100 年的记录表明,从含有适量陆地物质的系统逐渐过渡到以水生有机物质为主的系统,这可能是由于从激流系统到静水系统的转变。与大约 200 年前阿卡迪亚人在拉斐特地区定居的同时,沉积物记录出现了进一步的变化,但没有显示出土地利用变化或文化富营养化的标志性迹象。这可能是因为湖泊水位低,导致有机物的有效氧化和循环利用。马丁湖的基底沉积物在颜色和特征上都很独特,很可能来自于全新世晚期灾难性地干涸的大型古湖泊。过去 1100 年的记录表明,从含有适量陆地物质的系统逐渐过渡到以水生有机物质为主的系统,这可能是由于从激流系统到静水系统的转变。与大约 200 年前阿卡迪亚人在拉斐特地区定居的同时,沉积物记录出现了进一步的变化,但没有显示出土地利用变化或文化富营养化的标志性迹象。这可能是因为湖泊水位低,导致有机物的有效氧化和循环利用。
更新日期:2020-05-12
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