The impact of point source pollution on shallow groundwater used for human consumption in a threshold country

Abstract

Many developing and threshold countries rely on shallow groundwater wells for their water supply whilst pit latrines are used for sanitation. We employed a unified strategy involving satellite images and environmental monitoring of 16 physico-chemical and microbiological water quality parameters to identify significant land uses that can lead to unacceptable deterioration of source water, in a region with a subtropical climate and seasonally restricted torrential rainfall in Northern Argentina. Agricultural and non-agricultural sources of nitrate were illustrated in satellite images and used to assess the organic load discharged. The estimated human organic load per year was 28.5 BOD(5) tons and the N load was 7.5 tons, while for poultry farms it was 9940-BOD(5) tons and 1037-N tons, respectively. Concentrations of nitrates and organics were significantly different between seasons in well water (p values of 0.026 and 0.039, respectively). The onset of the wet season had an extraordinarily negative impact on well water due in part to the high permeability of soils made up of fine gravels and coarse sand. Discriminant analysis showed that land uses had a pronounced seasonal influence on nitrates and introduced additional microbial contamination, causing nitrification and denitrification in shallow groundwater. P-well was highly impacted by a poultry farm while S-well was affected by anthropogenic pollution and background load, as revealed by Principal Component Analysis. The application of microbial source tracking techniques is recommended to corroborate local sources of human versus animal origin.

Strategies to optimize monitoring schemes of recreational waters from Salta, Argentina: a multivariate approach

“…The regime of the river is torrential with high flow rate and presence of suspended particles (mainly clays) during the wet season (Baudino 1997). Before entering the city, the river suffers the impact of agricultural activities (Cruz et al 2012) and while crossing the city, it is affected by different point and non-point discharges that decrease the ambient quality of the river water. The river also receives a high percentage of stormwater, partly treated sewage from the Waste Water Treatment Plant (WWTP) of the city of Salta, and effluents from small industries located on their margins (Poma et al 2012).…”

“…These anthropogenic activities and some natural events are the reasons by which surface waters are susceptible to changes in quality. The native flora and fauna of the area, seasonality, storm water runoff, illegal sewage discharges, industrialization, agriculture, and recreational human activities are some of the factors responsible for these changes, leading to a decrease in water quality (Cruz et al 2012; David et al 2013; Poma et al 2012; Wunderlin et al 2001). …”

“…Total and fecal coliforms are the most commonly used (Ashbolt et al 2001; Cruz et al, 2012; EC 1975; Hong et al 2010; Poma et al 2012). Two other microorganisms that have consistently performed well as indicators of illness in epidemiological studies in freshwater are Enterococci and E. coli (Marion et al 2010; Wiedenmann et al 2006).…”

“…Multivariate techniques are frequently used to evaluate water quality along rivers, reservoirs, groundwater and other AEs (Abgarie and Obi, 2009; Cruz et al 2012; Farmaki et al 2012; Hong et al 2010; Noori et al 2010; Noori et al 2012; Ouyang et al 2006; Poma et al 2012; Shrestha and Kazama, 2007; Shin et al 2012; Samsudin et al 2011; Wunderlin et al 2001). They have been applied to large amounts of data but in some cases, they were used to analyze the behavior of a unique AE and/or considering one or two microbiological parameters as indicators to evaluate microbial pollution.…”

“…They have been applied to large amounts of data but in some cases, they were used to analyze the behavior of a unique AE and/or considering one or two microbiological parameters as indicators to evaluate microbial pollution. Cruz et al (2012) studied water quality of shallow groundwater and surface water using 14 physicochemical and two microbiological parameters (total and fecal coliforms); Shrestha and Kazama (2007) analyzed the spatial and temporal variation of Fuji river basin, considering 12 parameters, with total coliform as microbial indicator; 19 parameters were measured by Shin et al (2012) in a urban estuary in New Jersey, in this case fecal coliform was the microbial indicator considered. Poma et al (2012) evaluated water quality of 11 monitoring points located along Arias-Arenales River.…”