LINKING NUTRIENT ENRICHMENT AND OXYGEN DYNAMICS TO ECOLOGICAL WATER QUALITY IN FRESHWATER SYSTEMS
DOI:
https://doi.org/10.69980/dd2bgv46Keywords:
freshwater quality, nutrient enrichment, dissolved oxygen, chlorophyll-a, turbidityAbstract
The integrated assessment is important to detect emerging changes in the ecological condition of freshwaters, which is dependent on interacting nutrient, biological, physicochemical and oxygen-related processes. This study aimed to characterize freshwater water quality and examine temporal and statistical relationships among total phosphorus, chlorophyll-a, turbidity, dissolved oxygen, and supporting physicochemical indicators. The data from 23 monitoring observations between October 2022 and April 2023 were analyzed quantitatively to examine the changes over time. Total phosphorus was available for 12 observations. The following descriptive statistics, Shapiro–Wilk testing, Spearman rank correlations, temporal trend analysis and HC3-robust univariable regression models were used. Chlorophyll-a and turbidity increased significantly over time (ρ = 0.859 and 0.823; both p < 0.001), whereas dissolved oxygen declined (ρ = −0.622, p = 0.002). Chlorophyll-a was strongly associated with turbidity (ρ = 0.856, p < 0.001), while dissolved oxygen was inversely associated with chlorophyll-a (ρ = −0.490, p = 0.018) and turbidity (ρ = −0.532, p = 0.009). The turbidity accounted for 37.67% of the variation in DO, whereas chlorophyll-a accounted for 24.85%. There was no significant relationship found between total phosphorus and chlorophyll-a, dissolved oxygen, or BOD. The results suggest that ecological and oxygen indicators provided better temporal information than the available phosphorus measurements and should be routinely used in combination with phosphorus in freshwater water-quality assessments.
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