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首页> 外文期刊>Physical Geography >Mid-late Holocene anthropogenic and natural variations in geochemistry and sedimentation in the Yazoo Basin: Clark Lake, Sharkey County, Mississippi
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Mid-late Holocene anthropogenic and natural variations in geochemistry and sedimentation in the Yazoo Basin: Clark Lake, Sharkey County, Mississippi

机译：yazoo盆地地球化学和地球化学和沉淀的中期全新世的全新世植物和自然变化：克拉克湖，斯卡基县，密西西比州

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摘要

A 4000-yr history at Clark Lake reveals natural variations in sediment geochemistry and nutrient levels and anthropogenic influence on twentieth century sedimentation rates. Sediment texture and ridge and swale topography indicate that the channel system creating Clark Lake is now occupied by the Yazoo River. Between 1.24 and 0.60 m (2522-865 cal yr BP), total carbon percentages and the C/N ratio average 42% and 17, respectively. The base of the 1650-yr interval and onset of high organic activity in the lake coincides with the abandonment of the Yazoo Meander Belt. The top of the interval is marked by a drop in C/N ratio to 11 and a geochemical transition zone. No change in the rate of sediment accumulation or clay mineralogy was observed despite increased cumulative percentages of Al, Fe, K, Mg, Mn, Ca, and Na. The decrease in organic activity at 865 cal yr BP is attributed to unfavorable growth conditions related to the entrenchment of the Yazoo River and changes in the hydroperiod of the area. Significant floodplain alteration was completed in 1978, but the only major effect was increased sedimentation in the late twentieth century due to the completion of the Whittington Auxiliary Channel.
机译：Clark Lake的4000年历史揭示了二十世纪沉降率的沉积物地球化学和营养水平和人为影响的自然变化。沉积物纹理和脊和沼泽地形表明，创建克拉克湖的渠道系统现在被yazoo河占用。在1.24和0.60米（2522-865只CAL YR BP）之间，总碳百分比和C / N比平均42％和17分别。湖泊中1650年间间隔和高有机活性的底座与yazoo蜿蜒带的放弃恰逢其有。间隔的顶部标有C / N比的下降到11和地球化学过渡区。尽管Al，Fe，K，Mg，Mn，Ca和Na增加，但仍未观察到沉积物积累或粘土矿物学率的变化。 865年CAL YR BP的有机活性降低归因于与yazoo河的壕沟有关的不利生长条件以及该地区的氢氢联系的变化。 1978年，重大洪泛平台改变，但由于完成了Whittington辅助渠道，二十世纪后期沉淀的唯一主要效果是增加的。

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