Nanay River in the peruvian Amazonian rain forest supports 300 000 inhabitants in the city of Iquitos and surrounding villages with drinking water and fish for consumption. The river has been polluted with mercury, due to the use of the amalgamation method for gold extraction. This has resulted in that local people have got increased levels of mercury, up to 45 mg mercury per litre of blood. The aim of this study was to evaluate the concentrations of mercury in sediment and fish in the Nanay River, Peru, and to study eventual relation between fish mercury concentrations and mercury concentrations in sediment and water parameters such as dissolved organic matter, pH, dissolved oxygen and turbidity. In October 2005, eleven sample points for river water and sediment were established, from the gold mining activities close to Pucaurco westwards (18M 0605010, UTM 9579526) to Pampa Chica eastwards, drinking water source for Iquitos, (18M 0691053, UTM 9585255) in the region Loreto in Peru. Water temperature, conductivity,
total dissolved ions, turbidity, dissolved oxygen and pH was measured in the field. Five species of predatory fishes were collected within the study area, where Pintuyacu River
joins Nanay River. The samples are currently subject to analyses in Sweden and results will be obtained during the spring. Based on the results, information will be sent to the Regional Government in the region of Loreto about the current state and recommended actions to prevent further contamination.