Geochemical processes contributing to the contamination of soil and surface waters in the Rio Conchos basin, Mexico

Abstract

A geochemical characterization of the middle Rio Conchos basin is presented based on two contaminants, salts (Ca and Na) and toxic metalloids (As and Sb). Their content in surface water and sediment samples was determined, and their spatial distribution was mapped to show the relationship to each other, to the geology and hydrology, and to other potential factors affecting their distribution (i.e., prevailing winds). Correlation analyses between salts, toxic metalloids, and associated elements, and their spatial distribution aided in determining their sources, which included mines, rock outcrops, urban centers, irrigation waste water, and agricultural runoff. The salinity of the Rio Conchos reached a critical level after receiving waters of its contaminated tributary Rio Chuviscar and irrigation drain returns from the Irrigation District 005, but further downstream the water quality improved when it mixed with Ca-rich water, signifi cantly reducing its Na concentration. Based on its spatial distribution, the content of As in alluvial material was found to be associated with the presence of Ag-Pb mines and to a lesser degree to Oligocene ignimbrites. A correlation of As with Sb, Cu, and Bi suggests that natural sources are the dominant contribution of As within the area, although concentrations above permissible level for water were found in river water samples at a few places where sewage was also present, suggesting an additional (anthropogenic) important source of As. A characterization of natural sources affecting the chemistry of surface waters is a fi rst step toward understanding the natural processes taking place and for documenting natural background levels that are needed to predict the response of the environment to various human activities.

Limnological characteristics and rotifer community composition of Northern Mexico Chihuahuan Desert Springs

“…The few studies on ground and surface water quality in the CD focused primarily on the Río Bravo and Conchos (e.g., Gutiérrez et al, 2008; Ríos et al, 2004); indeed detailed surveys of arid land waters in Mexico are rare, particularly for CD aquatic systems (Carson & Masa-Benignos, 2014; CNA, 2011; Alcocer &Bernal-Brooks, 2010; Hendrickson et al, 2008; Walsh et al, 2008; INE, 2007). Water scarcity and multiple geographical features often result in high diversity and endemism of biota in arid land springs (Unmack & Minckley, 2008).…”

An Overall Water Quality Index (WQI) for a Man-Made Aquatic Reservoir in Mexico

“…The Luis L. Leon dam in Chihuahua, Mexico is the downstream water reservoir that captures the water from the Conchos River. Different studies have been conducted in the Conchos River with the purpose of identifying its water quality in terms of physical-chemical-biologic parameters [ 15 , 16 , 17 , 18 , 19 ]. Moreover, metal and metalloid levels have been reported in the water as well as sediments throughout this river [ 20 , 21 , 22 , 23 , 24 ].…”

Innovación y gobernanza para el desarrollo sustentable en México

“…Un estudio categorizó los contaminantes, incluyen metales pesados que causaron el síndrome de Itai-Itai y afectaron la salud del feto en mujeres embarazadas (McCulligh y Vega Fregoso, 2019). La concentración de los metales pesados en el río Conchos fue provocada por las precipitaciones erráticas y las altas temperaturas en el norte de México (Gutiérrez et al, 2008). Las altas temperaturas y las precipitaciones erráticas hacen que el río Conchos pierda mucha agua por evaporación.…”