This study is a preliminary examination of heavy metal pollution in sediments close to two mine sites in the upper part of the Jequetepeque River Basin, Peru. Sediment concentrations of Al, As, Cd, Cu, Cr, Fe, Hg, Ni, Pb, Sb, Sn, and Zn were analyzed. A comparative study of the trace metal content of sediments shows that the highest concentrations are found at the closest points to the mine sites in both cases. The sediment quality analysis was performed using the threshold effect level of the Canadian guidelines (TEL). The sediment samples analyzed show that potential ecological risk is caused frequently at both sites by As, Cd, Cu, Hg, Pb, and Zn. The long-term influence of sediment metals in the environment is also assessed by sequential extraction scheme analysis (SES). The availability of metals in sediments is assessed, and it is considered a significant threat to the environment for As, Cd, and Sb close to one mine site and Cr and Hg close to the other mine site. Statistical analysis of sediment samples provides a characterization of both subbasins, showing low concentrations of a specific set of metals and identifies the main characteristics of the different pollution sources. A tentative relationship between pollution sources and possible ecological risk is established.

The environmental implications of mining activities are of worldwide concern. An environmental evaluation at the basin level was conducted because of widespread mining in Cajamarca in Northern Peru. A sediment monitoring program was developed at the Jequetepeque basin, located in Cajamarca. A total of 16 sites were monitored at three different times between June 2009 and July 2010, and a total of 42 samples were collected. All samples were analyzed by microwave digestion and by a sequential extraction scheme following the three-stage European Community Bureau of Reference (three-stage BCR) protocol. Trace element mobilization from the sediments to the water column was assessed by the risk assessment code (RAC). Spatial and temporal distribution of trace elements was evaluated by principal component analysis and hierarchical cluster analysis. Cd, Zn, As, and Pb showed the highest concentrations independent of season. Notably, Cu concentration and mobility increased during the wet season for all samples. Additionally, Hg concentration and mobility increased during the wet season near the mine sites. According to the enrichment factor, the highest enrichments of Cd, Zn, Pb, and As were related to mine runoff. The effect of trace elements near the mine sites at the Jequetepeque basin was considered a significant threat to the environment due to Cd, Zn, Pb, and As, and the concentrations of Cu and Hg were also considered a concern. This work establishes a baseline for the environmental quality status of the Jequetepeque basin that may support water quality management in Peru.

Recent efforts have been made to determine the environmental impact of mining over the past 11 years in the Jequetepeque River basin, in northern Peru. We have now analyzed data from two studies to elucidate the spatial and temporal trace metal distributions and to assess the sources of contamination. These two studies were carried out from 2003 to 2008 by a Peruvian government administration and from 2008 to 2010 by us. We analyzed 249 samples by principal component analysis, measuring: pH, electrical conductivity, total dissolved solids, total suspended solids, chloride, weak-acid-dissociable cyanide, total cyanide, nitrite and nitrate, ammonium, sulfate, and trace metals and metalloids (Al, As, Ca, Cd, Cu, Cr, Fe, Mg, Mn, Ni, Pb, and Zn). Within the spatial distribution of the basin, the highest Al, As, Cu, Fe, Ni, and Pb concentrations were found at the closest point to the mine sites for both periods of time, with the higher peaks measured during the first years of the sampling data. Temporal trends showed higher concentrations of Cu and Fe in samples taken before 2005, at which point the two mines were closed. Risk assessment was quantified by the hazard quotient as related to water ingestion. The risk for human health posed by the concentrations of several trace metals and metalloids was found to be highly adverse (As and Cr), significant (Al, Cd, Cu, Fe, and Pb), or minimal (Ni and Zn).

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AGUA y TERRITORIO Rutgerd BoelensUniversity of Amsterdam and Wageningen University. Amsterdam-Wageningen, Países Bajos. rutgerd.boelens@wur.nlResumen -El presente artículo evalúa cómo la herramienta del monitoreo es utilizada políticamente en contextos de confl ictos por contaminación de empresas extractivas. Analizamos el caso de una cuenca afectada por minería de extracción de oro a cielo abierto en Cajamarca, Perú. En nuestro artículo diferenciamos las distintas etapas de un monitoreo para determinar cómo se convierte en herramienta legitimadora de los discursos difundidos por las mineras. El examen crítico de los procesos de monitoreo, en cambio, puede derivar en el apoyo a las acciones políticas de la sociedad civil que desafían el poder establecido por los actores extractivos. Abstract -The present article evaluates how mining enterprises rely on monitoring as a political tool in socio-

In the Jequetepeque basin (Peru), gold extraction activity has been performed in the last decades, leading to a release of metals and metalloids into the environment. Sediment samples were taken in the vicinity of two mines and analysed. Extraction of metals and metalloids from sediments was carried out using single extraction procedures, acidic (HNO 3 ), and complexation (EDTA) leaching, in order to determine the mobility of trace elements. Results indicated that acidic extraction at low pH values increased the leachability of trace elements. EDTA showed a higher bioavailability of metals in sediments that acidic extraction under similar pH conditions because of its greater leaching capacity. This is an important issue in view of risk assessment analysis. The highest extractability was observed for Cd in all sediments with up to 90% of extraction after 1 hour. The mobility index analysis indicated that faster kinetic leachability of some trace elements leads to a higher mobility in sediments, especially those near the active gold extraction mine. The ecological risk assessment suggested that the four river sediments were at high and very high risk levels, indicating that sediment contamination is an issue of environmental concern in the Jequetepeque basin of northern Peru.