Arsenic in waters, soils, sediments, and biota from Mexico: An environmental review.

We reviewed over 226 studies dealing with arsenic (As) in water bodies (124 sites or regions; 5,834 samples), soils (44; 2,700), sediments (56; 765), rocks (6; 85), mine waste (25; 582), continental plants (17 (77 species); 571), continental animals (10 (32 species); 3,525) and aquatic organisms (27 (100 species) 2,417) in Mexico. In general, higher As concentrations were associated with specific regions in the states of Hidalgo (21 sites), San Luis Potosi (SLP) (19), Baja California Sur (15), Zacatecas (5), and Morelos (4). High As levels have been detected in drinking water in certain locations of Coahuila (up to 435 μg L) and Sonora (up to 1004 μg L); in continental surficial water in Puebla (up to 780 μg L) and Matehuala, SLP (up to 8684 μg L); in groundwater in SLP (up to 16,000 μg L) and Morelia, Michoacán (up to 1506,000 μg L); in soils in Matehuala, SLP (up to 27,945 μg g) and the Xichú mining area, Guanajuato (up to 62,302 μg g); and in sediments in Zimapán, Hidalgo (up to 11,810 μg g) and Matehuala, SLP (up to 28,600 μg g). In contaminated arid and semi-arid areas, the plants P. laevigata and A. farnesiana exhibit the highest As levels. These findings emphasize the human and environmental risks associated with the presence of As in such regions. A synthesis of the available techniques for the removal of As in water and the remediation technologies for As contaminated soils and sediments is given. The As occurrence, origin (geogenic, thermal, mining and anthropogenic) and evolution in specific regions is summarized. Also, the mobilization and mechanisms to explain the As variability in continental environments are concisely given. For future research, a stratified regional sampling is proposed which prioritizes critical sites for waters, soils and sediments, and biota, considering the subpopulation of foods from agriculture, livestock, and seafood. It is concluded that more detailed and comprehensive studies concerning pollution levels, as well as As trends, transfer, speciation, and toxic effects are still required.