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(W/EH056) Effect of several species of cadmium on BAA proteasa in a soil amended with sewage sluge. Gomez, Ignacio 1, Marco, Begoņa2, Mataix, Jorge2, Navarro Pedreņo, Jose2, Mataix Solera, Jorge2Alicante, 1 2 ABSTRACT- A laboratory experiment was carried out with a calcareous agricultural soil of Alicante for three months. The soil was amended with sewage sludge from the wastewater treatment plant of Altea (Alicante) (40 g/kg d.w. soil). Several treatments with different doses of cadmium were applied to determine the effects of the heavy metal (soluble, exchangeable and complexed) on BAA protease (Argininamide Benzoil hidrolitic protease). The treatments established were: T0 (control soil), TL (soil+sewage sludge), T1 (soil+sewage sludge+Cd 40mg/kg d.w.), T2 (soil+sewage sludge+Cd 80 mg/kg d.w.), T3 (soil+sewage sludge+Cd 200 mg/kg d.w.). The cadmium was incorporated as cadmium chloride in desionized water solution used for irrigation along the experiment. Seventh sampling periods were established. The chemical speciation of the metal was done to obtain the soluble fraction (water extraction), exchangeable fraction (ammonium acetate 1 M extraction) and complexed fraction (NaOH 1 M extraction). Cadmium was measured by atomic absorption espectrometry. The BAA protease (enzymatic activity) was determined from the liberation of ammonium, using N-a-Benzoil Argininamide as substrate. The results showed that this enzyme was poorly affected by cadmium. A soft tendency to decrease the activity was appreciated, but not significant. The changes produced in the enzymatic activity were influenced by sewage sludge application, increasing the activity until 2.38 mmol NH4+/g h in the treatment TL opposite to the 0.50-1.33 mmol NH4+/g h obtained in the control treatment (T0). The fraction of soluble cadmium is small, and exchangeable and complexed cadmium have produced no important effect on protease. Key words: protease, cadmium, sewage sludge |
