Changes in chlorophyll a and its response to nitrogen and phosphorus characteristics over the past three decades in Poyang Lake, China

Abstract

AbstractIn this study, we explore the relationship between changes in chlorophyll a (Chl a) content, total nitrogen (TN) and total phosphorus (TP) characteristics from 1989 to 2018 in Poyang Lake, China, by applying Landsat Thematic Mapper/Enhanced Thematic Mapper (TM/ETM) image data in combination with in situ monitoring data. Results showed that the average Chl a content in water over this 30‐year period was 5.77 μg/L. Although the water quality status of the lake was generally healthy, proportional Chl a content >10 μg/L (E10) has gradually increased, and the water quality in some areas of the lake has subsequently deteriorated over the past 30 years. Additionally, E10 was significantly positively correlated to the TN/TP. Changes in Chl a content were significantly positively correlated to the ratio of TN flux to TP flux from tributaries into the lake, but negatively correlated to TP flux. Results indicated that Lake can be categorized as phosphorus‐sufficient and nitrogen limited.