Temporal and spatial variations in signatures of sedimented organic matter in Lingding Bay (Pearl estuary), southern China
Temporal and spatial variations in signatures of sedimented organic matter in Lingding Bay (Pearl estuary), southern China
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DOI：
10.1016/s0304-4203(03)00050-1
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发表时间：
2003-06
期刊：
影响因子：
3
通讯作者：
G. Jia;P. Peng
中科院分区：
文献类型：
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作者：
G. Jia;P. Peng
对中国南方珠江大河口伶仃湾的三个210Pb测年沉积物岩心沉积有机碳的浓度、积累速率、总有机碳与总氮的比值以及δ13C值进行了研究。研究发现，陆地有机质对伶仃湾沉积物贡献显着，而水动力条件极大地影响了有机质的来源，从而影响了碳同位素的分布。其中，河流输送的陆地有机质是ZJ-6岩心有机质的主要类型，位于西北河口附近，主要被流动的河水覆盖。水生有机物是ZJ-7核心区的主要输入源，该核心区位于海湾东部，河流较弱。在海湾西南部的ZJ-8核心区，海水和河水相互作用，有机质具有陆地和水生混合的特征。 TOC/TN 行为随有机物来源的不同而变化。在ZJ-6岩心中，由于无机氮比例较高，TOC/TN比值下降，且TOC含量最低的样品下降最严重。在ZJ-7和ZJ-8岩心中，富氮有机物的优先降解可能会导致误导性的TOC/TN来源特征。大约在20世纪50年代之前，沉积有机质的积累速率较低，δ13C稳定，但自1950年代以来，沉积有机质积累速率较高，δ13C变化较大。 20世纪50年代以来，包括香港、澳门在内的珠江三角洲地区经济的快速发展可能会引发这种变化。
The concentration, accumulation rate, the ratio of total organic carbon to total nitrogen, and δ13C value of sedimented organic carbon from three210Pb-dated sediment cores were studied in Lingding Bay, a large estuary of the Pearl River in southern China. It was found that terrestrial organic matter contributed significantly to the Lingding Bay sediments, and that hydrodynamic conditions greatly influenced the sources of organic matter, and hence carbon isotope distributions. Specifically, river-transported terrestrial organic matter is the main type of organic matter in core ZJ-6, located near the northwestern river outlets and overlaid mainly by flowing river water. Aquatic organic matter is the main input for the core ZJ-7 in the east of the bay, where the river current is weak. In core ZJ-8 in the southwest of the bay, where seawater and river water interact, organic matter is characterized by mixture of terrestrial and aquatic origin. TOC/TN behaviors vary with organic matter sources. In core ZJ-6, TOC/TN ratios are depressed due to considerable proportion of inorganic nitrogen, and samples with lowest TOC contents are the most depressed. In core ZJ-7 and ZJ-8, the preferential degradation of nitrogen-rich organic matter may result in misleading TOC/TN source signature. Sedimented organic matter had a low accumulation rate and stable δ13C before about the 1950s, but a high accumulation rate and variable δ13C since the 1950s. Rapid economic development in the region of Pearl River delta, including Hong Kong and Macao, since the 1950s may give rise to the change.