School of Environmental and Chemical Engineering, Shanghai University, 150#, 99 Shangda Road, Shanghai, 200444, China.
Environ Sci Pollut Res Int. 2024 Feb;31(10):14775-14790. doi: 10.1007/s11356-024-32118-2. Epub 2024 Jan 27.
Spartina alterniflora, an invasive plant widely distributed in China's coastal regions, has had a significant impact on the stability of wetland ecosystems and elemental biogeochemical cycles. The invasion of S. alterniflora has been found to lead to the accumulation of sulfides in the soil. The cycling of sulfur and iron in the soil is closely interconnected. Coastal estuarine wetlands are influenced by both freshwater in rivers and seawater tides, as well as the frequent variations in redox conditions caused by tidal fluctuations, which makes the cycling of sulfur and iron in the soil invaded by S. alterniflora more intricate. In this study, field surveys and laboratory experiments were conducted to explore the effects of S. alterniflora invasion and hydrological changes on the cycling of sulfur and iron as well as related functional microorganisms in the soil. The invasion of S. alterniflora showed an increase in soil reduced inorganic sulfur (RIS) components in both high and low marshes of Jiuduansha wetland, with higher content observed in summer and autumn. The tidal simulation experiments revealed abundant sulfate in seawater tidal conditions could promote the formation of acid volatile sulfides (AVS) in the soil of low marshes invaded by S. alterniflora and ensuring the continuous increase in AVS content. Diffusive gradients in-thin-films (DGT) technology indicated the existence of high-concentration soluble S enrichment zones in the soil of low marshes invaded by S. alterniflora, which may be related to S. alterniflora root exudates. Tidal action increased the relative abundance of sulfur-reducing bacteria (SRB) in the soil of low marshes, and under the influence of seawater tidal action, SRB exhibited higher relative abundance. However, S. alterniflora might inhibit the activity of iron-reducing bacteria (FeRB) in the soil of low marshes. In conclusion, S. alterniflora may enhance the sulfate reduction rate and promote the formation of free sulfides in tidal salt marsh ecosystems by releasing root exudates that stimulate the activity of SRB, while concurrently inhibiting the activity of FeRB and reducing their competition with SRB. This effect is particularly pronounced in low marshes under seawater tidal conditions. Thus, S. alterniflora is capable of rapidly invading tidal salt marshes by utilizing sulfides effectively.
互花米草是一种广泛分布于中国沿海地区的入侵植物，对湿地生态系统的稳定性和元素生物地球化学循环产生了重大影响。互花米草的入侵导致土壤中硫化物的积累。土壤中硫和铁的循环密切相关。沿海河口湿地受河流淡水和海潮的影响，以及潮汐波动引起的氧化还原条件频繁变化，使得互花米草入侵的土壤中硫和铁的循环更加复杂。本研究通过野外调查和室内实验，探讨了互花米草入侵和水文变化对土壤中硫铁循环及相关功能微生物的影响。互花米草的入侵增加了九段沙湿地高、低滩土壤中还原性无机硫（RIS）的含量，夏季和秋季含量较高。潮汐模拟实验表明，海水潮汐条件下丰富的硫酸盐可以促进低滩互花米草土壤中酸挥发性硫（AVS）的形成，并确保 AVS 含量的持续增加。薄膜扩散梯度（DGT）技术表明，互花米草入侵的低滩土壤中存在高浓度可溶性硫富集区，这可能与互花米草根系分泌物有关。潮汐作用增加了低滩土壤中硫还原菌（SRB）的相对丰度，在海水潮汐作用的影响下，SRB 的相对丰度较高。然而，互花米草可能会抑制低滩土壤中铁还原菌（FeRB）的活性。综上所述，互花米草可能通过释放刺激 SRB 活性的根系分泌物，增强硫酸盐还原速率，并促进潮汐盐沼生态系统中游离硫化物的形成，同时抑制 FeRB 的活性，减少其与 SRB 的竞争。在海水潮汐条件下的低滩，这种效应更为明显。因此，互花米草能够通过有效利用硫化物快速入侵潮汐盐沼。
