ENIVRONMENT ASIA

Volume 14, No. 01, Month JANUARY, Year 2021, Pages 63 - 68

Role of internal and external nutrients loading in regulating in-lake nutrient concentrations in a eutrophic shallow lake

Amy Rose Aeriyanie, Som Cit Sinang, Nasir Nayan, and Keong Bun Poh

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The information on changes in total phosphorus and total nitrogen concentrations of lake in response to variations of diff erent nutrients loading is critical for the selection of an appropriate lake management strategy. This study aimed to evaluate the infl uence of internal and external nutrients loading in controlling in-lake nutrient concentrations in a shallow lake system. This study was conducted in Slim River Lake for 12 months to quantify internal, external total phosphorus and total nitrogen loading, and in-lake total phosphorus and total nitrogen concentrations. Total phosphorus and total nitrogen in storm water and grab water samples were quantifi ed using ascorbic acid and hydrazine reduction method. Study results indicated that internal total phosphorus and total nitrogen loading fl uctuated from 150.17 kg to 7,538.33 kg and 2.72 kg to 42.23 kg, respectively, thus suggesting the signifi cant sediment phosphorus and nitrogen released into the water column. Mobilization of nutrients from the surrounding area was indicated by external total phosphorus and total nitrogen loading, which ranged from 19,800 kg to 401,500 kg and 67.81 kg to 4,611.67 kg, respectively. In-lake total phosphorus and total nitrogen concentrations ranged from 1.2 mg/L to 46.22 mg/L and from 0.14 mg/L to 0.65 mg/L, respectively. Pearson correlation analysis suggests that in-lake nutrient concentrations were only signifi cantly correlated to the internal total phosphorus (r = 0.82, p < 0.05) and internal total nitrogen (r = 0.60, p < 0.05) loading. These results indicated that the internal total phosphorus and total nitrogen loading could have more impact on the lake eutrophication as compared to external sources. Hence, future restoration strategies that include internal and external nutrients management should be considered to restore Slim River Lake.

Keywords

Nutrients; Eutrophication; Internal loading; External loading; Total phosphorus; Total nitrogen; Slim River Lake

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