Institute of Geography, Fujian Normal University, Fuzhou 350117, China.
Fujian Provincial Key Laboratory for Subtropical Resources and Environment, Fuzhou 350117, China.
Ying Yong Sheng Tai Xue Bao. 2023 Aug;34(8):2205-2214. doi: 10.13287/j.1001-9332.202308.028.
Over the past decades, rivers have delivered imbalanced nutrient loads to coastal marine ecosystems due to human activities, which leads to serious regional or global eutrophication problems. The Minjiang River is heavily influenced by human activities. To understand the changing characteristics of nutrient transport ratios in the Minjiang River waters, we measured the seasonal variations of carbon, nitrogen, phosphorus and silicon nutrients in the lower surface waters of the Minjiang River between July 2019 and July 2020. The results showed that the annual average contents of dissolved silicon (DSi), lithogenic silicon (LSi) and biogenic silicon (BSi) in the surface waters of the lower Minjiang River were 5.30, 4.58 and 2.37 mg·L, respectively. There were large seasonal differences among these parameters, with higher content of DSi than LSi and BSi in summer, higher content of DSi than BSi and LSi in autumn and higher content of LSi than DSi and BSi in winter. The proportions of DSi in total silicon tended to decrease gradually from land to sea, while the proportion of BSi was on the contrary. In term of stoichiometric ratios, the Minjiang River mostly presented carbon or phosphorus limitation and was unlimited by silicon or nitrogen. About 1.03×10 mol DSi and 0.46 ×10 mol BSi were delivered via the Minjiang River to the ocean yearly, showing a decreasing trend year by year. Based on the data in recent years, the nutrient loads of carbon, nitrogen, and phosphorus transported by Minjiang River showed an increasing trend. The imbalanced nutrient loads may lead to changes in the structure and function of the river, estuary, and offshore ecosystems. The study of nutrient stoichiometric ratios can provide a theoretical basis for solving the problems in structural balance of nutrients and eutrophication in Minjiang River estuary and adjacent marine waters.
在过去的几十年中，由于人类活动的影响，河流向沿海海洋生态系统输送了不平衡的养分负荷，导致严重的区域或全球富营养化问题。岷江受人类活动的影响很大。为了了解岷江水中营养物质输送比例的变化特征，我们测量了 2019 年 7 月至 2020 年 7 月岷江下游表层水中碳、氮、磷和硅营养物质的季节性变化。结果表明，岷江下游表层水中溶解硅（DSi）、岩源硅（LSi）和生源硅（BSi）的年平均含量分别为 5.30、4.58 和 2.37mg·L。这些参数之间存在较大的季节性差异，夏季 DSi 的含量高于 LSi 和 BSi，秋季 DSi 的含量高于 BSi 和 LSi，冬季 LSi 的含量高于 DSi 和 BSi。DSi 在总硅中的比例从陆地到海洋逐渐降低，而 BSi 的比例则相反。就化学计量比而言，岷江主要表现为碳或磷限制，而不受硅或氮限制。每年通过岷江向海洋输送约 1.03×10mol DSi 和 0.46×10mol BSi，呈逐年减少的趋势。根据近年来的数据，岷江输送的碳、氮和磷养分负荷呈增加趋势。不平衡的养分负荷可能导致河流、河口和近海生态系统的结构和功能发生变化。营养物质化学计量比的研究可以为解决岷江河口及邻近海域营养物质结构平衡和富营养化问题提供理论依据。
