CHEN Jingan 1 , YIN Chao 1 , ZENG Yan 1 , YU Jia 2 , WANG Jingfu 1 , LIAO Peng 1
(1. State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences,Guiyang 550081, China;
2. Guizhou University, New Rural Development Research Institute of Guizhou University,
Guiyang 550025, China)
Abstract: Eutrophication is one of the most prominent ecological and environmental problems in the world. A large number of studies have shown that biogenic factors such as carbon (C) , nitrogen (N) and phosphorus ( P) are the key factors to control eutrophication. With the implementation of increasingly intensive watershed pollution control projects, the input flux of exogenous nitrogen and phosphorus decreased significantly, but the concentration of nitrogen and phosphorus in many lakes did not decrease significantly as expected, algae blooms were still frequent, and the high load of nutrients in lakes was considered to be the culprit. Organic matter is the main carrier of the biogeochemical cycles of biogenic elements such as carbon, nitrogen and phosphorus in the lake ecosystem. Algal growth is accompanied by the absorption of carbon, nitrogen and phosphorus and the formation of organic matter, while the mineralization and degradation of organic matter in the process of water sedimentation and early diagenesis of sediment are accompanied by the release of carbon, nitrogen and phosphorus. Although carbon, nitrogen and phosphorus are regenerated during the mineralization of particulate organic matter, they are not released in an equal proportion. Important progress has been made in the research on the regeneration behavior of biogenic elements during organic matter degradation, which is mainly reflected in the following aspects. (1) The C ∶N ratio and C ∶ P ratio of particulate matter in water gradually increase with the increase of water depth, indicating that granular nitrogen and granular phosphorus in water usually have a faster mineralization rate than granular carbon. (2) The preferential release intensity of phosphorus than carbon during organic matter degradation under anoxic conditions was much higher than that in oxygen enriched environments. (3) The polyphosphate cycle and enzymatic hydrolysis driven by microorganisms may be the important factors leading to the preferential regeneration of phosphorus in the degradation process of organic matter. After eutrophication, the preferential regeneration of phosphorus may accelerate the recycling of phosphorus, which is easy to form a positive feedback mechanism of " algae blooms→ water hypoxia intensification →preferential regeneration of phosphorus during organic matter degradation" . This positive feedback mechanism has increased the difficulty of lake eutrophication restoration. The future research should focus on the mechanism and ecological environmental effects of the differences in regeneration behavior of biogenic elements during organic matter degradation.
Key words:lake; biogenic elements; phosphorus; organic matter degradation; preferential regeneration
EARTH AND ENVIRONMENT: Vol. 51, No. 5, Tot No.355 2023