Changes in the physical and geochemical properties of suspended sediment delivered to the headwaters of LOIS river basins over the last 100 years: a preliminary analysis of lake and reservoir bottom sediments
Changes in the physical and geochemical properties of suspended sediment delivered to the headwaters of LOIS river basins over the last 100 years: a preliminary analysis of lake and reservoir bottom sediments
复制标题
近100年来LOIS河流域源头悬浮沉积物物理和地球化学性质的变化：湖泊和水库底部沉积物的初步分析
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
J. Lees
中科院分区：
文献类型：
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作者：
I. Foster;J. Lees
对从九个湖泊和/或水库地点取回的单个岩心的底部沉积物进行了粒度、烧失量和 Ca、Mg、Na、K、Fe、Al、Mn 和 P 总浓度的分析。地点差异反映了本地和异地对沉积记录的贡献的相对重要性，并且与根据每个岩心确定的 210 Pb 和 137 Cs 年代学确定的沉积速率随时间的变化有关。虽然沉积速率的变化反映了来自贡献流域的沉积物流入和集中在湖盆内的情况，但这些模式通常揭示了上个世纪与流域扰动相关的变化。在鲕粒石灰岩下面的两个排水集水区的湖泊中发现了富含钙的沉积物。通过低温烧失量测定的有机物含量范围为 13% 至 25%。在流域具有广泛的覆盖泥炭积累的底部沉积物中，或者在沉积物积累率较低的湖泊中，有机质含量更可能受到湖泊生产力的控制，在底部沉积物中发现了高有机质水平。一般来说，有机质含量与沉降速率和产沙量成反比。在湖泊沉积物记录中发现了沉积物物理和地球化学特征的最大核心变化，其中流域的沉积物流入量显着增加。九个湖泊流域中每个流域的平均产沙量与沉积物的平均有机质和磷含量成反比，但产沙量的增加与更好的分选以及粗粒和中粒淤泥颗粒比例的减少有关。九个地点中的六个显示出其近地表沉积物中总磷负荷显着增加的证据，这要么是由于沉积物产量高于平均水平，要么是沉积物磷浓度显着增加的结果。
Bottom sediments from a single core retrieved from nine lakes and/or reservoir sites have been analysed for particle size, loss on ignition and the total concentration of Ca, Mg, Na, K, Fe, Al, Mn and P. Site differences reflect the relative significance of autochthonous and allochthonous contributions to the sedimentary record and are related to changes in sedimentation rate through time as determined from a 210 Pb and 137 Cs chronology determined for each core. Whilst changing sedimentation rates reflect both sediment influx from the contributing catchment and focusing within the lake basin, the patterns generally reveal changes associated with catchment disturbance over the last century. Calcium-rich sediments are found in two lakes draining catchments underlain by Oolitic limestones. Organic matter contents, as determined by low temperature loss on ignition, range from 13 to 25%. High organic matter levels are found in bottom sediments either where the contributing catchment has extensive blanket peat accumulations or in lakes with low sediment accumulation rates, where the organic matter content is more likely to be controlled by lake productivity. In general, organic matter content is inversely related to sedimentation rate and to sediment yield. Greatest down-core variations in sediment physical and geochemical signatures are found in lake sediment records where catchments have experienced significant increases in sediment influx from the catchment. The average sediment yield determined for each of the nine lake-catchments is inversely related to average organic matter and P content of the sediments, but an increase in sediment yield is associated with better sorting and a decrease in the proportion of coarse and medium silt sized particles. Six of the nine sites show evidence for significant increases in the total P load in their near-surface sediments, either resulting from higher than average sediment yields or as a result of significant increases in sediment-P concentrations.