Particle dynamics play significant roles in sedimentological and geomorphological processes as well as biogeochemical cycles in estuaries. We collected a suite of water samples from the North Passage of the Changjiang (Yangtze) Estuary during different tidal conditions in summer 2009 to observe variations in the particulate ²³⁴Th, ⁷Be, ²¹⁰Pb, and ¹³⁷Cs activities as well as in particle transport, deposition, and resuspension. The mean activities of ⁷Be and ²¹⁰Pb_ex in surface water during low tide were lower than those during high tide. The residence times of ⁷Be (1.1–3.4 d), ²³⁴Th (4.7–28 d), and ²¹⁰Pb (7.9–34 d) in the North Passage increased with the increase of salinity and suspended particulate matter. The estimated results, based on a two‐dimensional model of ⁷Be, ²³⁴Th, and ²¹⁰Pb, showed that sedimentary particles in the North Passage experienced net deposition during neap tides whereas those in more seaward areas of the North Passage exhibited net resuspension during spring tides. The ⁷Be/²¹⁰Pb_ex activity ratio in seaward area of the North Passage was lower during spring tide than during neap tide but both were close to values in surface sediments beyond the estuary. Using ⁷Be/²¹⁰Pb_ex and ¹³⁷Cs/²¹⁰Pb_ex activity ratios as tracers, we deduced that most of particles in the North Passage were not derived from the direct deposition of Changjiang input particles but were transported from sediment deposited offshore. These results emphasized the important contributions of offshore inputs to sediments in this channel, which should be considered when conducting channel dredging of other estuarine systems.

中文翻译：

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使用多个放射性核示踪剂确定的不同潮汐条件下受控导航通道中的粒子动力学

粒子动力学在河口的沉积学和地貌过程以及生物地球化学循环中起着重要作用。我们在2009年夏季的不同潮汐条件下，从长江口北通道采集了一组水样，以观察²³⁴ Th，⁷ Be，²¹⁰ Pb和¹³⁷ Cs颗粒活动以及颗粒传输过程中的变化。 ，沉积和重悬。退潮时地表水中⁷ Be和²¹⁰ Pb _ex的平均活性低于涨潮时。停留时间为⁷ Be（1.1–3.4 d），²³⁴ Th（4.7–28 d）和随着盐度和悬浮颗粒物的增加，北通道的²¹⁰ Pb（7.9–34 d）有所增加。基于⁷ Be，²³⁴ Th和²¹⁰ Pb的二维模型的估计结果表明，北航道中的沉积颗粒在潮汐时经历了净沉积，而北航道中较靠海地区的沉积物在沉积过程中出现了净悬浮。春天的潮汐。的⁷铍/ ²¹⁰铅_离小潮期间在北槽的靠海面积活性比高于大潮在较低但均接近值超过河口沉积物。使用⁷ Be / ²¹⁰ Pb _ex和¹³⁷ CS / ²¹⁰的Pb_前活性的比率作为示踪剂，我们推断，在最北槽颗粒未从长江输入粒子的直接沉积衍生的但是从近海成沉积物被运送。这些结果强调了海上投入对该河道沉积物的重要贡献，在进行其他河口系统的河道疏ed时应考虑这些贡献。