藏北高原不同类型高寒湿地水环境特征及时空差异

Spatial and Temporal Distribution Patterns of Nutrient Elements in Different Alpine Wetlands in Northern Qinghai-Tibet Plateau

高寒湿地是高原元素生物地球化学循环的重要场所。高寒湿地的水环境特征是其元素生物地球化学的直接体现,不同类型高寒湿地的水环境特征时空差异会对其生态系统结构和功能造成直接影响。本研究于2020年9月和2021年4月分别调查了藏北高原不同沼泽、河口和河流三种类型天然湿地的水环境特征,并分析了造成其时空差异的主要原因。河口湿地的总氮、溶解性活性磷和总有机碳含量与河流湿地溶解性无机氮和总有机碳含量在4月均显著高于9月;沼泽湿地总氮含量在9月显著高于4月,其余各水环境指标在三类湿地均无显著性季节差异。沼泽湿地叶绿素a含量显著高于另外两种类型湿地,总有机碳显著高于河流湿地,沼泽和河流湿地的总氮含量显著高于河口湿地。溶解性活性磷则表现为河口湿地>沼泽湿地>河流湿地。不同湿地的水文特征、生命活动和物质来源的差异可能导致了湿地水环境特征的时空差异。

Alpine wetlands are important areas for elemental biogeochemical cycling,and the water characteristics of alpine wetlands can not only influence the biogeochemistry of different elements,but also the structure and function of the ecosystems.In this study,we investigated the water environment of three different types of natural alpine wetlands(estuarine wetlands,riverine wetlands,and peatlands)in the Northern Qinghai-Tibet Plateau during two field campaigns in September 2020 and April 2021,respectively.The spatial and temporal variation of the water environment indicators of the wetlands were compared and the possible reasons were discussed.The results showed that total nitrogen,dissolved reactive phosphorus,and total organic carbon contents in the water of estuarine wetlands and dissolved inorganic nitrogen and total organic carbon contents in the water of riverine wetlands were significantly higher in April than those in September.Total nitrogen contents in the water of peatlands were significantly higher in September than those in April,the rest of water environment indexes did not change significantly with seasons among the three types of wetlands.For peatlands,the chlorophyll a content was significantly higher than that of the other two types of wetlands,while total organic carbon was significantly higher than that of riverine wetlands.The total nitrogen contents of peatlands and riverine wetlands were significantly higher than those of estuarine wetlands.Soluble reactive phosphorus,on the other hand,showed a trend of estuarine wetlands>peatlands>riverine wetlands.The differences in hydrological characteristics,biotic activities,and sources of nutrients in different wetlands might lead to the spatial and temporal differences in the characteristics of the wetland water environment.