Abstract: Chlorophyll a (Chl a) is an important environmental indicator for lake primary productivity assessment, eutrophication control, and water ecological restoration. This study presents an analysis of the temporal and spatial characteristics of 12 water environment factors of a large shallow Baiyang Lake, based on a field survey of 11 sampling sites in spring and summer. We construct a generalized additive model and discuss the correlation between Chl a and water environmental factors. The results show the environment factors in the lake under strong human disturbance featured obvious temporal and spatial heterogeneity. The Chl a concentration was significantly correlated with six environmental factors－total nitrogen, ammonia nitrogen, transparency, phosphate contents, nitrate nitrogen, and dissolved oxygen－and the first four are the most critical. The interpretation rate of this generalized model is 98.9% for the Chl a content, and verification against the measurements shows its reliability. The results help understand the algal growth in Baiyang Lake and improve its algal bloom prevention and water environmental protection.

Key words: Baiyang Lake, generalized additive model, Chlorophyll a, water environment, shallow lake