珠江口沉积物210Pb分布特征及环境意义

根据珠江口及其邻近海域中的14个沉积柱样的210Pb随深度分布的测量数据以及210Pb过剩衰减法的原理，建立了基于傅立叶级数的变沉积速率模型，对珠江河口近50年来河口沉积物的沉积序列进行了分析。分别对各柱样的210Pb数据使用变沉积速率模型进行计算，获得了柱样更切实的沉积速率变化过程并分析沉积速率、年代计算结果与同时期内沉积环境之间的关系，结果表明:珠江口不同站位的沉积速率差异很大，几个站位的整体平均沉积速率分别是，7.25 cm/a，5.36 cm/a，3.26 cm/a，3.03 cm/a，1.58 cm/a；沉积速率的变化与同时期发生在区域内的洪水、风暴潮、人类活动、河口演变等一系列综合因素有较好的对应关系，这说明使用基于傅立叶级数的变沉积速率模型得到的210Pb沉积速率变化的垂直分布能够解释其对应时段内的沉积环境，此模型亦可为其它河口区域的210Pb沉积速率计算提供借鉴。

~(210)Pb Characteristic in the Sediment Cores from the Pearl River Mouth and Its Environmental Implication

Based on the principle of lead- 210 excess decaying and the characteristics of modern lead- 210 sediment profiles of 14 sediment cores from the Pearl River mouth and its adjacent areas, a Fourier series based model for counting variation sediment rates was built. Sediment series was analyzed at the Pearl River mouth within 50 sediment years. The lead- 210 of each sediment cores was calculated in the model for counting variation sedimentation rates and gained more specific data of the sedimentation process. Sedimentation rates, dating results and those relations between the sedimentary environmental at the same time were analyzed. The result shows that sedimentation rates are distinct from each other greatly at different stations. The average sediment rates of the stations were 7.25cm/a,5.36cm/a,3. 26cm/a,3.03cm/a,1.58cm/a, respectively. The sedimentation rates variation at different stations has good correla-tion with the flooding, storms, anthropological activities, geomorphologic evolvement and other environmental ele-ments at the estuary within the same periods. It verified that the characteristic of lead- 210 of the sediment profiles calculated from the Fourier series based model for counting variation sediment rates can explain the environmental stat-ues/changes at the same time. The model also made experiences for other estuaries which would analyses the sediment rates from the characteristic of lead- 210 of the sediment cores.