Niveles de contaminación de mercurio, cadmio, arsénico y plomo en subsistemas de producción de la cuenca baja del río Bogotá
Alfaro Rodríguez, Ricardo | 2002-09
During 1996 the levels of Mercury (Hg), Cadmium (Cd), Arsenic (As) and Lead (Pb) in the lower basin of the Bogotá River were monitored. This alluvial plain has an altitude of 200 - 400 meters above sea level, an average anual precipitation of 1200mm; a temperature of 24°C, and belongs to a sub-humid province that makes necessary the use of supplementary irrigation in any agropecuarian exploitation. The municipalities that belong to this unity are: Girardot, Agua de Dios, Tocaima and Ricaurte. The measurements were done in orderto identify and quantify the toxic heavy metalic elements Hg, Cd, As and Pb in water, soil and in the production subsystems of rice, banana and grass. The measurements were done in twelve farms, bordering Bogotá river. The results show that the elements Cd an As are present in quantities that are beyond the normal or admissible limits established for soil and vegetable tissue (2 mg/Kg and 0,3 mg/Kg); the levels found in irrigation water are considerad within the admissible limits (< 0,01 mg/Kg Cd and < 0.05 mg/Kg As). Pb and Hg showed normal quantities for all the measurments taken (Soil, water and vegetable tissue): nevertheless animal tissue, particulary bovine muscles, showed high levels of Pb and Hg (3679.4pg/Kg and 241,8pg/Kg respectively), wich are over the máximum weekly ingestión admissible (1400 pg Pb and 300 pg Hg). These results confirm an active contamination process , with levels that exceed the máximum admissible limits established by the different international institutions, showing a high risk for animal and human health through food.