Nickel biosorption ability was evaluated in two bacterial strains: Acinetobacter baumannii UCR-2971 and Pseudomonas aeruginosa UCR-2957, resulting in greatest adsorption at pH 4.5 and a residence time of 100 minutes. Biosorption isotherms showed that the process follows the Langmuir model. The maximum adsorption rates (N max ) were 8.8 and 5.7 mg·g -1 for A. baumannii and P. aeruginosa, respectively; however, affinity constants suggest that P. aeruginosa (K=1.28) has higher affinity for nickel than A. baumannii (K=0.68). It is suggested that both strains could be used for wastewater treatment, as long as the concentration of Ni 2+ is within the range of mg·L Nickel is an important environmental inorganic pollutant, with allowed levels under 0.04 mg·L -1 in human consumption water. Higher concentrations affect normal flora in ecosystems and are toxic for human beings.Conventional chemical methods for heavy metal removal from wastewater (precipitation, filtration, ion-exchange, reduction-oxidation) are expensive and ineffective, particularly when metal concentration is low (4,12,13). Thus, biotechnological methods such as biosorption are emerging as an interesting alternative. Since cells are metabolically inactive in non-viable biomass systems, metal interactions occur at the superficial level (14). Bacteria express a wide range of complex molecules on their cell wall, which confer anionic net charge to the cell surface at acidic pH values (13). In Gram negative bacteria, the lipopolysaccharide, a highly anionic structure, has been identified as the main binding site for metals (9). When the cell wall is in direct contact with the environment, negatively charged groups are able to attract and bind metallic cations based on electrostatic forces, without cellular energy consumption, an effect that is favored by the high surfacevolume ratio in bacteria (3,5).In this work, nickel biosorption ability was investigated using bacteria isolated from wastewater contaminated with heavy metals (34.9 ± 9.0 mg Ni 2+ ·L -1 ; 31.5 ± 4.0 mg Pb 2+ ·L -1 ). The sample was aseptically filtered (0.45 µm membrane); the residues were resuspended in 100 mL Trypticase Soybean Broth (TSB, Difco) and incubated at 25ºC for four days. Then, 0.1 mL from the TSB were inoculated in Blood Agar, Cetrimide Agar (Difco), and Mac Conkey Agar (Oxoid) plates and incubated for 48 hours at 25ºC. Isolated strains were identified using the automatic VITEK system (BioMèrieux, Inc); Acinetobacter baumannii (UCR-2971) and Pseudomonas aeruginosa (UCR-2957) were the selected strains. For biomass production, these strains were inoculated in TSB and agitated (80 rpm) in a thermal bath (Orbit 3540, Labline), for 72 hours at 28ºC. The TSB was centrifuged at 5000 rpm for 10 minutes and biomass was washed three times with sterile distilled water and dried at 56ºC for 48 hours. The inocula of each adsorption

<p>The Aneto is the largest glacier of the Pyrenees, is located on the Maladeta Massif (Central Pyrenees), close to the highest point of the range, the Aneto peak (42° 37' 52 N, 0° 39' 24 E; 3,404 m a.s.l.). This glacier is 675 meters long, occupy an area of 48.64 ha and their maximum altitude is 3,269 meters. The glacier front ends at 3,029 m a.s.l. and its mean slope is 23.6°, reaching a maximum of 56° in some parts. The main aim of this research is to present a detailed volumetric reconstruction of the glacier since the LIA and analyze their retreat. Based on morphological features, the extent of the glacier has been reconstructed for different periods (LIA, 1957, 2000, 2006, 2015 and 2017) and their ice volume, maximum ice thickness and ELAs has been calculated. To delimitate the glacier extension during the LIA, the moraines have been mapped by using photo interpretation techniques. For the recent phases digital aerial photographs and satellite images have been used. To estimate the topography of the glacier we used a simple steady-state model that assumes a perfectly plastic ice rheology, reconstructing the theoretical ice profiles and obtaining the extent of the glaciers. Later, to reconstruct the ice surface we calculated longitudinal profiles, with these reconstructed profiles a digital elevation model was created and combined with the bedrock topography in order to obtain the ice thickness at each phase. This bedrock topography was obtained by combining the glacier topography with a 3D model of the glacier obtained with geo-radar (ERHIN program, Government of Aragon).</p><p>This study reveals a great retreat of the Aneto Glacier since the LIA. The length of the glacier has been reduced from 1,970 m during the LIA to 675 m in 2017, and its tongue has retreated from 2,385 to 3,029 m a.s.l. during the same period. Regarding the area, it has been reduced from 245 ha during the LIA to 48.64 ha in 2017. During this period, the ELA has increased from 2,925 to 3,140 m a.s.l. The glacier volume has been reduced from 82.57 x10<sup>6</sup> m<sup>3</sup> to 3.48 x10<sup>6</sup> m<sup>3</sup>, and the maximum ice thickness from 95 m to 27m. These data reveals a huge retreat of the glacier since the LIA, furthermore, this retreat has been more accelerated since the 50's.</p><p> </p><p>Research funded by PYRENEEND project (10.18258/11352)</p>