Anthropogenic Impact on the Quality of Water and Agricultural Soil in Guadiana Valley, Durango, Mexico

Abstract One of the most important effluents in Guadiana Valley, Durango is El Tunal River, mostly used for agricultural and livestock supply. This river has been polluted by agricultural activity and wastewater discharges. Thus, this study aimed to evaluate the current quality of water and agricultural soil near the river, to estimate the environmental situation of the agricultural sector and its main pollution sources. Hence, a total of 24 soil and five water samples were taken, analysing parameters of organic matter, pH, nutrients, and heavy metals(loid)s (As, Cd, Pb, Zn) in five agricultural areas. The randomised experimental design showed significant variations in soil ( p < 0.05) of organic matter, nitrogen, As, and Pb between sampling points, confirming suitable conditions for agriculture. Although contamination by heavy metal(loid)s exists, it is below permitted levels. In contrast, the physicochemical quality of the water indicated high levels of phosphates, total dissolved solids, and total coliforms, mainly in the nearest site of a wastewater treatment plant, thus the quality of the water is not suitable for consumption and irrigation for sensitive crops. Nevertheless, rainfall contributes to improve the quality of the river by diluting pollutants. Moreover, constant use of this water might represent a risk to human health and agriculture as it could transport elements to crops or soil, becoming a severe environmental problem.