Analisis Bioakumulasi Logam Berat Timbal (Pb) pada Ikan Nila (Oreochromis niloticus) di Danau Siombak

Abstract

Lead (Pb) is a toxic heavy metal that is persistent and capable of accumulating in aquatic organisms through bioconcentration and biomagnification processes. This study aimed to analyze Pb concentrations in Nile tilapia (Oreochromis niloticus), determine the bioconcentration factor (BCF), and evaluate the influence of environmental factors on Pb accumulation in Lake Siombak, Medan City. Sampling was conducted at two observation sites, namely the Inlet and the Midlet, during the period of December 2024 to May 2025, representing the rainy season (DecemberFebruary) and the dry season (March–May). A total of 24 tilapia samples were collected, consisting of 12 fish from the Inlet and 12 fish from the Midlet, with two fish sampled at each station every month. In addition, 12 water samples were collected, comprising one sample per station per month during March–May 2025. Pb concentrations in water and fish muscle tissue were analyzed using Atomic Absorption Spectrophotometry (AAS), while water quality parameters including pH, temperature, dissolved oxygen (DO), and total suspended solids (TSS) were also measured. The results showed that Pb concentrations in Lake Siombak water ranged from approximately 0.10 to 0.15 mg/L, which were still below the water quality standards. However, Pb was detected in tilapia muscle tissue at concentrations ranging from approximately 0.07 to 18.1 mg/kg. This indicates that although Pb levels in water were relatively low, the metal could still accumulate in fish through uptake from water and the aquatic food web. The bioconcentration factor (BCF) of Pb in tilapia ranged from approximately 5 to 9, with an average value of about 0.05, indicating a low accumulation capacity of Pb in Oreochromis niloticus. Statistical analysis showed that seasonal variation (rainy and dry seasons) had no significant effect on Pb concentrations in fish. Variations in Pb levels in fish tissues were more strongly influenced by fluctuations in water quality and the tidal hydrological dynamics of Lake Siombak than by biological factors of the fish. Despite the low BCF values, the presence of Pb in tilapia indicates that this species remains a potential bioindicator of Pb contamination in the waters of Lake Siombak.