Water pollution index of high Andean micro-basin of the Chumbao River, Andahuaylas, Peru

Abstract

During its journey, the river water suffers natural or anthropic contamination, deteriorating its quality. This impact can be qualified by determining the pollution Indexes (IPO). The work aimed to evaluate the spatial and temporal variation of the IPOs in the water of the high Andean micro-basin of the Chumbao River. The study included the section from 13°46'38.4” S, 73°15'32.3” W at 4079 m of altitude up to 13°35'26.4” S, 73°27'00.8” W at 2572 m of altitude. Physical, chemical, and microbiological parameters of the water were determined in 8 points along the river. These were grouped to calculate the IPO by mineralization (IPOMI), organic matter (IPOMO), suspended solids (IPOSUS), and trophic (IPOTRO) in the dry and rainy seasons. The indexes were categorized from 0.0 (not polluted) to 1.0 (highly polluted). The data were collected in triplicate and valuated through ANOVA and Tukey's test. It was found that IPOSUS, IPOMI, and IPOMO. The points near the head of the micro-basin reported no and low pollution; besides, they increased considerably in urban areas reaching highly polluted levels. In contrast, IPOTRO reported a eutrophic state, and that contamination levels were higher in the dry season. The waters of the Chumbao River above 2900 m of altitude and close to the head of the micro-basin do not show contamination, but in the urban area the index of pollution is high.

Proposal of a Water-Quality Index for High Andean Basins: Application to the Chumbao River, Andahuaylas, Peru

“…The scores assigned by the experts had a variability ranging from 0.0% to 25%, whereas the BOD 5 reported 0.0% variability. This is an important indicator in surface and river water quality [10,12,14,17,29,40,51].…”

“…The importance of the parameter's weight is related to water use and source [85][86][87][88][89]. In the case of WQI applicable to surface waters, it would seem that the greatest weight should be given to the parameters DO, BOD 5 , nitrates, suspended solids and total coliforms [5,12,17,25,43,64,68,88].…”

“…In order to formulate the WQI HA equation, the sum of SI PC , SI HM , and SI OM with weights 0.3, 0.3, and 0.4, respectively were considered, taking as weight criteria the importance and the major source of pollution for high Andean rivers which are agricultural, livestock, and domestic activities [5][6][7]12].…”

“…Concerning the nitrogen series, levels of 0.0 mg/L for nitrates, nitrites, and ammonium, as well as phosphates (Table 7) were observed, especially in the high places of the high Andean basin of Chumbao (Figure 5). However, there is anthropic activity [10,26,92], mainly livestock activity (open field rearing of alpacas, sheep, and cattle) [6,12].…”

“…The problem can be aggravated when rivers pass through urbanized areas where contamination with organic matter stormwater runoff contributes further [8][9][10][11]. Additionally, rivers in urban areas are affected by untreated wastewater discharges from clandestine landfills, sanitary landfills, and industrial waste [12][13][14][15][16]. The anthropic activities surrounding a high Andean river basin, such as livestock, agriculture, and mining extraction, generate negative impacts on water quality and on surrounding soils [17][18][19][20][21], whose pollutant components, in many cases, are not biodegradable, or the self-purification capacity is very low [7,13,22], especially if they contain traces of dissolved metals and inorganic material [23,24].…”