Sheng Weikang, Hou Qingye, Yang Zhongfang, Yu Tao
School of Earth Science and Resources, China University of Geosciences, Beijing, 100083, PR China.
School of Earth Science and Resources, China University of Geosciences, Beijing, 100083, PR China.
Mar Environ Res. 2023 May;187:105968. doi: 10.1016/j.marenvres.2023.105968. Epub 2023 Mar 21.
The alluvial plain delta is vulnerable to complex land-sea interactions as a result of rising sea levels and increasing storm surges due to global environmental change. Topsoil samples (0-20 cm) from the Pearl River Delta (PRD) were subjected to periodic artificial saltwater inundation treatments with varying salinities (0, 35‰, 40‰, 50‰) for 50 days to explore the impacts of saltwater inundation on heavy metals (Cd, Pb, Zn) in soils. The inundation treatments reached dynamic equilibrium in approximately 20 days, and heavy metals were promoted to release into leachate. The extraction rate of heavy metals was highest with artificial saltwater at 40‰ salinity, which was generally attributed to pH variation, increasing ionic strength and reductive dissolution of Fe-Mn oxyhydroxides. However, once the salinity reached 50‰, a higher SO2- 4concentration could depress the release of heavy metals by providing more negative adsorption sites. Cd in soils was most likely to leach, followed by Zn, but Pb showed higher retention. After saltwater inundation, the bioavailability of heavy metals decreased in the order Cd > Zn > Pb. Redundancy analysis (RDA) results demonstrated that Cd and Zn are more susceptible to soluble salt ions in soils than Pb. The retention of Pb could be attributed to its larger ionic radius and reduced hydrated radius as well as the stable species under the pH conditions of the treatments. This study suggests that the migration of heavy metals could reduce the water quality and increase the ecological risk of the interaction zone between land and sea.
由于全球环境变化导致海平面上升和风暴潮增加，冲积平原三角洲易受复杂的陆海相互作用影响。采集珠江三角洲（PRD）的表层土壤样本（0 - 20厘米），用不同盐度（0、35‰、40‰、50‰）的人工盐水进行为期50天的周期性淹水试验，以探究盐水淹水对土壤中重金属（镉、铅、锌）的影响。淹水试验在大约20天内达到动态平衡，重金属被促进释放到渗滤液中。盐度为40‰的人工盐水对重金属的提取率最高，这通常归因于pH值变化、离子强度增加以及铁锰氢氧化物的还原溶解。然而，一旦盐度达到50‰，较高的硫酸根离子浓度可通过提供更多负吸附位点抑制重金属的释放。土壤中的镉最容易淋溶，其次是锌，但铅的保留率较高。盐水淹水后，重金属的生物有效性按镉>锌>铅的顺序降低。冗余分析（RDA）结果表明，镉和锌比铅更容易受到土壤中可溶性盐离子的影响。铅的保留可能归因于其较大的离子半径和减小的水合半径，以及处理pH条件下稳定的物种。本研究表明，重金属的迁移可能会降低水质，并增加陆海交互带的生态风险。
