干旱区生态环境知识资源中心

The oasis irrigated by the Mendoza River (Province of Mendoza, Argentina) -like most cities at present- is facing problems such as urban encroachment into agricultural land, multiplicity of users, and reduced availability of water resources, both in quantity and quality. Efforts and investments have been made to secure water availability (improved efficiencies, water saving); however, this is not the case as regards preservation of water quality. The agricultural sector in Mendoza has become the victim of pollution caused by urban and industrial development due to effluent discharges (point and/or diffuse) in the irrigation network. Studies conducted in Mendoza’s Northern Oasis have shown high levels of phosphate pollution in the Mendoza River. The objective of this paper is to study the spatio-temporal evolution as well as the sources of this type of pollution. The study, which was based on a number of samplings carried out from 2003 to 2009, points to moderate levels of phosphate pollution in the Northern Oasis irrigated by the Mendoza River. Considerably high phosphate levels were also detected at three specific sites in the oasis: 1. the area irrigated by the Cacique Guaymallen and Jocoli canals (phosphate levels were six times the phosphate content in the water: from 0.2 mg L(-1) at site R I to 1-2 mg L(-1) at site C II); downstream of this latter site only a small area of 7300 ha is irrigated; 2. the area irrigated by the Pescara Canal downstream of site DVIII (1,250 ha), with mean content values seventeen times higher (8.5 mg L(-1)) than at site D I (0.49 mg L(-1)), where agricultural and stormwater runoff is discharged; 3. the Lower Mendoza River area, where phosphate content increased sixteen times in the middle and tail-end sections of the system, with mean values ranging from 0.2 mg L(-1) at site R II to 3.25 mg L(-1) at R III.