Composition of heavy metals in sediment, water, and fish of the Ganga and Yamuna Rivers in two major cities of India.

The rapid industrial development in the Indian capital region has led to significant waste generation, which, despite undergoing treatment prior to disposal, contributes substantially to water body contamination. Given the diverse nature of these wastes and their potential repercussions across the food chain, a study was conducted to evaluate heavy metal contamination levels in the Ganga and Yamuna Rivers of two major cities. Six heavy metals (Pb, Cd, Hg, Cu, Cr, and Zn) were analyzed in fish, water, and sediment samples by utilizing flame atomic absorption spectrophotometry (Avanta Σ) from March 2019 to February 2020. Results revealed distinct heavy metal distribution patterns, with Cr > Zn > Pb > Cu > Cd > Hg in the Ganga River and Zn > Cr > Pb > Cu > Cd > Hg in the Yamuna River for fish samples. Additionally, levels of Hg in Cyprinus carpio and Sperata oar from the Ganga River, and Pb, Cd, Hg, and Cr in Salmophasia bacaila and Mystus cavasius from the Yamuna River exceeded WHO/FAO permissible limits. In water samples, the predominant heavy metal sequences were Pb > Cu > Zn > Cr > Cd > Hg for the Ganga River and Cr > Zn > Pb > Cu > Cd > Hg for the Yamuna River, with Pb, Cr, Zn, and Cd surpassing WHO standards. Sediment analysis revealed varying heavy metal compositions, with Zn > Cr > Pb > Cu > Cd > Hg in the Ganga River and Cr > Zn > Pb > Cu > Cd > Hg in the Yamuna River. While drinking water and fish from the Ganga River were deemed safe for consumption, those from the Yamuna River were not. Given the toxic nature of heavy metals and their detrimental health impacts, regular monitoring and effective management strategies are imperative.

Effect of dietary Spirulina level on growth and chemical composition of carcass in rohu, Labeo rohita (Hamilton).

An experiment was conducted in three different tanks for 45 days (T1, T2 and T3) to investigate the effect of dietary Spirulina level on growth and chemical composition of carcass in rohu, Labeo rohita. A diet having de-oiled rice bran(30%), rice polish (15%), de-oiled mustard oil cake(25%), Soya bean oil cake(10%) and de-oiled groundnut cake(20%) was provided to the control (i.e. 100% formulated feed), whereas in T2 95% formulated feed with 5% Spirulina and in T3 90% formulated feed with 10% Spirulina. Data were analysed with ANOVA (P < 0.05) and found significant. There was significant difference in the average final weight of the fish among treatments with highest in the T3 (11.28g) followed by T2 (8.32g) and T1 (7.51g). The higher SGR was recorded in T3 (2.17) followed by T2 (1.52) and T1 (1.28). There was significant difference in the average carcass composition of the fish among treatments with highest level in T3 followed by T2 and T1.