Mercury contamination in Lake Xolotlán (Managua)

Abstract

Total mercury was measured in different compartments of Lake Xolotlán's (Managua) ecosystemviz., sediments, water, fish and men. Sediments from 18 localities at 5 depths inside the sediment (5, 10, 15, 20 and 25 cm) contained an average concentration of 0.62 μg Hg.g⁻¹±0.46 at the surface, with extreme values of 0.16 and 1.8 μg.g⁻¹. The highest concentration was observed at 25 cm depth in front of the chlor-alkaly factory (ELPESA). This maximum is associated with the period of highest production of this factory. The highest mercury concentrations in water were also measured close to the discharge of ELPESA,viz. 787 μg.Hg⁻¹ in January and 506 μg.g⁻¹ in April. The mean mercury concentrations measured in the muscles of the most consumed fish were 0.63 μg.g⁻¹±0.22 (extreme values 0.22 and 1.45) inCichlasoma managuense, and 0.07 μg.g⁻¹±0.14 (extreme values 0.004 and 0.63) inC. citrinellum. The concentration in the liver was 0.79 μg.g⁻¹±1.29 inC. managuense and 0.62 μg.g⁻¹±0.44 inC. citrinellum. Human hairs (n=98) of fishermen and their families contained 5.03 μg.g⁻¹±6.2 (extreme values 0.02 and 38.22). The mean concentration measured in men was 6.22 μg.g⁻¹±6.34 (n=58), and in women 3.39 μg.g⁻¹±5.7 (n=40). The average mercury concentration of hairs of workers of ELPESA was 91.24 μg.g⁻¹±156.9 (extreme values 0.46 and 724.53; n=32). We conclude that total mercury levels in the various ecosystem compartments are very high and mercury contamination in the lake may be considered as dangerous for human health.