Release of Endogenous Nutrients Drives the Transformation of Nitrogen and Phosphorous in the Shallow Plateau of Lake Jian in Southwestern China

Abstract

Eutrophication remediation is an ongoing priority for protecting aquatic ecosystems, especially in plateau lakes with fragile ecologies and special tectonic environments. However, current strategies to control the phosphorus (P) and nitrogen (N) levels in eutrophication sites have been mainly guided by laboratory experiments or literature reviews without in-field analyses of the geochemical processes associated with the hydrological and eutrophic characteristics of lakes. This study analyzed the water quality parameters of 50 sites at Lake Jian in May 2019, a moderate eutrophication shallow plateau lake, based on dissolved/sedimentary nitrogen, phosphorous and organic matter, grain size, C/N ratios and stable isotope ratios of δ13C or δ15N in sediments. The results showed that the average total nitrogen (TN) and total phosphorus (TP) concentrations in the lake water were 0.57 mg/L and 0.071 mg/L, respectively. The TN and TP contents of surface sediment ranged from 2.15 to 9.55 g/kg and 0.76 to 1.74 g/kg, respectively. Stable isotope and grain source analysis indicated that N in sediments mainly existed in organic matter form and P mainly occurred as inorganic mineral adsorption. Endogenous pollution contributed to >20% of TN. Furthermore, our findings showed that phosphorus was the nutrient that limited eutrophication at Lake Jian, unlike other eutrophic shallow lakes. In contrast, the nutrient levels in the sediment and input streams belonged entirely to the N-limitation state. The distinctness in release intensity of N and P could modify the N/P limitation in the lake, which affects algae growth and nutrient control. These results demonstrated that reducing exogenous nutrients might not effectively mitigate lake eutrophication due to their endogenous recycling; thus, detailed nutrient monitoring is needed to preserve aquatic ecosystems.

Spatiotemporal Variations of Water Eutrophication and Non-Point Source Pollution Prevention and Control in the Main Stream of the Yellow River in Henan Province from 2012 to 2021

“…At the same time, water temperature and pH indirectly affect DO levels. And algal growth due to increased nutrients in the water is also a major factor in increased eutrophication [22]. Therefore, we selected eight indicators for analysis, encompassing physical indicators such as water temperature, DO and pH, as well as oxygen consumption indicators including COD Mn and BOD 5 , and nutrients including TP, NO 3 -N, and NH 3 -N. The selection of these three types of indicators can more effectively explore the influence of indicators other than Chlorophyll-a on water trophic status and the internal mechanism of eutrophication.…”

Effects of Dredging on Nitrogen and Phosphorus Storage Pat-Terns and Retention Mechanisms in Column Core Sediments in the Caohai Region of Dianchi Lake

“…Lakes in many countries around the world face the problem of eutrophication, caused by exogenous and endogenous pollutants [1][2][3]. When exogenous pollutants are effectively controlled, the sediments at the bottom of the lake act as a source and sink for pollutants, which are released through molecular diffusion, re-suspension, and convection, leading to water quality deterioration and algal blooms.…”

Assessing Climate and Human Activity Effects on Hypersaline Lake Ecosystem: Case Study of Saki Lake, Crimea

“…It affects the state of their biota, especially the microbial communities, phyto-and zooplankton. The microbial consortium is the key component of the nutrients recycling, and its modification disturbs the balance between different groups of microorganisms, including those involved in the transformation of organic and inorganic matters, in particular, nitrogen, phosphorus and carbon in biogeochemical cycles [8][9][10]. These processes together with climatic changes result in extremely negative consequences for salt lakes, which have been already observed worldwide, namely: their drying out, desalination and complete degradation [11].…”

“…At present, anthropogenic processes influence natural biogeochemical cycles, because often, nitrogen-phosphorus-and carbon-bearing chemicals are introduced into the environments. Sometimes, they contain the compounds disturbing the natural migration and transformation of these elements in water bodies [10,13]. Climate change and the modification of the key biogen elements cycles can adversely affect ecosystems and their biota, resulting in changes in the concentrations of these compounds in aquatic ecosystems, the physicochemical properties of the water and bottom sediments, and the structure and composition of the aquatic life [14].…”