Geochemical Background and Baseline Values Determination and Spatial Distribution of Heavy Metal Pollution in Soils of the Andes Mountain Range (Cajamarca-Huancavelica, Peru).

Concentrations of seven heavy metals (Cd, Cr, Cu, Hg, Ni, Pb, and Zn) and one metalloid (As) as well as various parameters (pH, organic carbon, granulometric analysis and cation exchange capacity) were analyzed in 77 soil samples collected in the mining areas of La Zanja and Colquirrumi (Department of Cajamarca) and Julcani (Department of Huancavelica). Our study proposed geochemical baseline values for heavy metals in a natural region (La Zanja) from samples collected during the period of the environmental impact study (2006), that is, from an earlier period which occurred at the beginning of the exploitation of the current gold mine. The baseline values obtained were as follows: 8.26 mg kg-1 for Cr; 56.97 mg kg-1 for Ni; 22, 20 mg kg-1 for the Cu; 47.42 mg kg-1 for Zn; 27.50 mg kg-1 for As; 4.36 mg kg-1 for Cd; 4.89 mg kg-1 for Hg, and 44.87 mg kg-1 for Pb. Through the use of different indices of heavy metal contamination (geo-accumulation index (Igeo), improved Nemerow index (IIN) and potential ecological risk index (RI)), the degree of pollution caused by mining activities in two areas, Colquirrumi and Julcani, which have a high density of mining sites in operation, was determined. The values obtained from these indices indicated that the Colquirrumi region was the most contaminated, followed by Julcani. The area of La Zanja, despite being free of mining operations, presented slight diffuse pollution. Several positive correlations were obtained, with a high level of significance, between pH, organic carbon content, cation exchange capacity, and the Cr, Pb and Ni concentrations of the soils. The spatial distribution of the heavy metals was realized by means of the interpolation method of ordinary kriging. The results obtained and the experience gained in this work were necessary to facilitate the identification of soil contamination processes in high altitude areas of the Andes Western Cordillera (Peru) as a basis for taking appropriate measures when restoring soils, during mine closure processes, and to protect the quality of soil resources.

Una nueva especie de Acanthoscurria (Araneae: Theraphosidae: Theraphosinae) sin órgano estridulador, del sur de Perú / A new species of Acanthoscurria (Araneae: Theraphosidae: Theraphosinae) without stridulatory organ, from southern Peru

Se describe Acanthoscurria sacsayhuaman sp. nov. (Araneae: Theraphosidae) en base a un macho proveniente de Cusco, Perú. Esta especie se diferencia del resto de las especies del género por la ausencia de setas estriduladoras en la cara retrolateral del trocánter del pedipalpo. Además, puede separarse por la forma del bulbo del macho y la apófisis tibial del primer par de patas. Se registra por primera vez el género para Perú.

Acanthoscurria sacsayhuaman sp. nov. (Araneae: Theraphosidae) is described based on a male from Cusco, Peru. The new species is characterized by the absence of stridulatory bristles on retrolateral face of palpal trochanter. Moreover, it can be distinguished by morphology of the male palpal bulb and tibial apophysis of the first pair of legs. The genus is recorded for the first time for Peru.