State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, 200062, China.
State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, 200062, China.
J Environ Radioact. 2019 Oct;207:15-26. doi: 10.1016/j.jenvrad.2019.05.017. Epub 2019 May 30.
The Southern Yellow Sea (SYS) is suffering from the increasing environment problems, such as the recurrent algal bloom. The Po/Pb disequilibrium is very useful for assessing particulate organic matter dynamics during phytoplankton blooming. In this study, 23 surface samples were collected from the SYS after the 2009 spring bloom, to investigate the disequilibrium between these two radionuclides. The dissolved Pb and particulate Pb activities (dpm 100 L) in the SYS surface waters varied within a wide range, with values of 2.28-17.82 (average 7.63 ± 4.25, n = 23) and 1.08-13.56 (average: 4.72 ± 2.84, n = 23). A deficiency of Po relative to Pb in the seawater was observed. The distribution coefficients (K) of the two radionuclides varied considerably (from 10 to 10 L kg), and higher K values of Po relative to Pb generally increased with POC/TSM (when above 10%). The negative correlation (R = 0.97, P = 0.012) between Po/Pb activity ratios and primary productivities in all four seasons implies that marine biological processes may enhance the disequilibrium between Po and Pb. The residence times of Po and Pb were estimated to be 7-206 days and 14-105 days, respectively. The longer Po residence times might be connected with several processes, e.g., Po uptake by marine particles or plankton, and recycling of fine-grained particles in the surface water. These short residence times of Po and Pb might indicate the existence of efficient scavenging processes, causing heavy metals and pollutants to deposit into the Yellow Sea (YS) bottom sediments.
南黄海（SYS）正面临日益严重的环境问题，如频繁发生的赤潮。Po/Pb 不平衡对于评估浮游植物大量繁殖期间的颗粒有机物质动态非常有用。本研究采集了 2009 年春季赤潮后南黄海表层海水 23 个样本，以调查这两种放射性核素之间的不平衡情况。南黄海表层水中溶解态 Pb 和颗粒态 Pb 活度（dpm 100L）变化范围较大，分别为 2.28-17.82（平均值 7.63±4.25，n=23）和 1.08-13.56（平均值：4.72±2.84，n=23）。观察到海水 Po 相对 Pb 不足。两种放射性核素的分配系数（K）差异较大（10 到 105Lkg），当 POC/TSM 高于 10%时，Po 相对于 Pb 的 K 值通常较高。四个季节的 Po/Pb 活度比与初级生产力之间的负相关关系（R=0.97，P=0.012）表明，海洋生物过程可能会增强 Po 和 Pb 之间的不平衡。Po 和 Pb 的居留时间估计分别为 7-206 天和 14-105 天。较长的 Po 居留时间可能与几种过程有关，例如，海洋颗粒或浮游生物对 Po 的吸收，以及表层水中细颗粒的再循环。Po 和 Pb 的较短居留时间可能表明存在有效的清除过程，导致重金属和污染物沉积到黄海（YS）海底沉积物中。
