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Economic activities such mineral extraction, generates high ecological impact. In the mining district "El Triunfo" located on the hydrological basin El Carrizal in Baja California Sur, the concentration of potential toxic elements (PTE: As, Cd, Pb) are above allowable limits, approximately 50 times the permissible levels. Nowadays, environmental pollution levels can be evaluated through the use of bioassays and stable isotopes of N. It’s well known that some organisms like Daphnia magna and Selenastrum capricornutum are high sensitive to low concentrations of PTE. In the case of the stable isotopes of N, are used to group several physiological processes compromised by high concentration of PTE. For this, isotopic analysis of nitrogen and concentrations of metals and metalloids were considered in the area where plants are exposed (Prosopis spp.). Polluted sediments were collected over 48 km of the Las Gallinas-El Hondo-El Carrizal arroyo. PTE concentrations, with a previous acidic digestion, were determined by ICP-MS. As and Sb were determined by NAA. D. magna and S. Capricornutum were exposed to pollute sediments and growth under these conditions: 22± 2 °C, photoperiod of 16h/8h light/darkness and usage of neonates under 24 h. For N isotopes, obtained samples were grounded to fine powder in an agate mortar with an acetone rinse between samples then analyzed by an EA-IRMS. Results showed that D. magna is more sensitive to PTE in comparison of S. capricornutum. In accordance to multivariate analysis D. magna presents a direct relationship in factors (1, 2, 3) with As, Cd and Fe. Plants growing on the tailings decreased their ?15N proportionally to the metal concentration in the área.

Palabras clave: Guadalupe fur seal; nitrogen; BIOASSAYS; potential toxic elements; Geochimistry

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