不同功能型沉水植物对溶解氧影响及环境效应

DIFFERENT FUNCTIONAL TYPES OF SUBMERGED MACROPHYTES ON DISSOLVED OXYGEN AND ITS ENVIRONMENTAL EFFECTS

  • 摘要: 研究选用刺苦草(Vallisneria spinulosa)、黑藻(Hydrilla verticillata)和穗花狐尾藻(Myriophyllum spicatum)分别代表底层型、冠层少根型和冠层多根型沉水植物, 通过中宇宙实验, 探索不同功能型沉水植物在生长过程中水柱和沉积物中溶解氧(DO)浓度及其相关指标的差异。实验结果表明: 不同处理组水柱DO浓度存在显著差异, 空白组水柱DO浓度显著低于植物处理组, 且空白组水柱总氮(TN)和总磷(TP)浓度降低程度最少; 黑藻组比叶面积、叶面积指数、净增长生物量、相对生长速率和水柱DO浓度最大, 能够有效降低水柱TP和TN浓度; 穗花狐尾藻组株高最高, 提升水柱DO浓度显著高于刺苦草, 水柱TP降低程度最大; 刺苦草组比根长、单株总根长和根冠比最大, 提升沉积物深度6 cm以内的DO效果最好, 沉积物铁含量最高, 沉积物总氮(TN)、总碳(TC)含量和间隙水总溶解性磷(TDP)浓度最低。在修复富营养湖泊过程中, 可根据水和沉积物缺氧状况, 合理配置底层型和冠层型沉水植物, 构建释氧能力较强的群落, 从沉积物表层到水柱上层均为湖泊提供充足的氧气, 从而更加有利于清水态的形成。

     

    Abstract: The concentration of dissolved oxygen (DO) in lakes decreases due to eutrophication and climate warming. However, submerged macrophytes can release oxygen through photosynthesis, effectively increasing DO levels in lakes. The process can induce changes in the physicochemical properties of the water column and sediment, subsequently impacting the ecosystem. We conducted a mesocosm experiment to examine the differences in dissolved oxygen and related indexes in water column and sediment across different functional types of submerged macrophytes. Vallisneria spinulosa was assigned to bottom-dwelling species, Hydrilla verticillata was assigned to less rooted canopy-forming species, while Myriophyllum spicatum was assigned to more rooted canopy-forming species. The results showed that significant differences in water column DO among treatment groups. The blank group had significantly lower water column DO compared to the plant treatment group, and it exhibited the least reduction in total nitrogen (TN) and total phosphorus (TP) in the water column. The specific leaf area, leaf area index, net growth biomass, total biomass, relative growth rate and water column DO of H. verticillata were the largest, which can effectively reduce the concentration of TP and TN in the water column. The plant height of M. spicatum was the highest, and its ability to elevate water column DO was significantly higher than that of spiny bittercress, with the greatest reduction in water column TP. V. spinulosa had the largest specific root length, total root length per individual and root shoot ratio among the 3 species. It significantly increased DO concentration in the sediment up to a depth of 6 cm. Additionally, V. spinulosa had the highest sediment iron content and the lowest sediment total nitrogen (TN), total carbon (TC) content and total dissolved phosphorus (TDP) in interstitial water. Therefore, we suggest diverse functional submerged macrophyte types were constructed in the restoration of eutrophic lakes, such as combing bottom-dwelling and canopy-forming species, since it would be conducive to the formation of clear water state.

     

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