Eutrophication factor analysis using Carlson trophic state index (CTSI) towards non-algal impact reservoirs in Taiwan

Abstract

Carlson trophic state index (CTSI) has been commonly adopted to assess the eutrophication potential of reservoirs or lakes in water quality management. This study aims to analyze the influential factors of CTSI-based eutrophication by using Pearson correlation analysis and principal component analysis with long-term data from 2008 to 2019 on 21 drinking water reservoirs in Taiwan. The trophic state index (TSI) deviation indicates that most drinking water reservoirs, around 45.5% of statistical data fall within non-algal turbidity with surplus phosphorus, especially in the spring and winter season. Besides, about 78% of total collected data show that TSI chlorophyll-a (Chl-a) is less than TSI Secchi depth (SD) due to the small particulate predominance. On the other hand, three TSI variables (SD, total phosphorus (TP) and Chl-a) of CTSI exhibits insignificant correlation to each other in most cases. Under such conditions, the probability of eutrophication (TSI > 50) based on TSI (SD) is 63%, while it is low as 20% based on TSI (TP) and TSI (Chl-a). The influencing factors of eutrophication variables by suspended solids (SS) composition and turbidity have shown that the SD is strongly influenced by non-algal SS. The deviations of three TSI have shown that the highest algae-induced eutrophication potential occurs in summer season. In addition, the TP is the most significant loading factor of algae-induced eutrophication for drinking water reservoirs. It is concluded that the CTSI has limited applicability to identify the trophic state of drinking water reservoirs in Taiwan in the presence of sustainable non-algal turbidity comparative Chl-a that specifically represents the potential of algal growth.

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

“…Lin et al found that TP is the main factor of eutrophication in drinking water reservoirs in Taiwan based on principal component analysis. This result is consistent with the conclusion of this paper [38]. In well-aerated water conditions, NH 3 -N readily oxidizes into NO 3 -N. Both TP and NO 3 -N serve as nutrients for plant growth, promoting the proliferation of phytoplankton, which in turn leads to a decline in DO levels and exacerbates water eutrophication.…”

Đánh giá mức độ phú dưỡng tại một số hồ nội thành tại quận Hai Bà Trưng, thành phố Hà Nội

“…Để đánh giá mức độ phú dưỡng, chỉ số phú dưỡng do Carlson phát triển [8] năm 1977 dựa trên 3 chỉ số phụ là chỉ số tổng phốt pho (TSITP), chỉ số về nồng độ diệp lục a (TSIChla) và chỉ số độ sâu đĩa Secchi (TSISD). Phương pháp tính chỉ số phú dưỡng Carlson đã được áp dụng rộng rãi trên thế giới để đánh giá mức độ phú dưỡng của nước hồ [6,7,[9][10][11].…”

Depth profile of reservoir water quality in the Southwest of Ethiopia

“…Terrestrial organic matter also plays a significant role in riverine runoff [ 10 ]. Intense rainfall has a substantial correlation with the potential for eutrophication [ 11 ]. Fertilizers and pesticides are washed into bodies of water by runoff from agriculture.…”