Sampling for the monitoring of heavy metals was carried out at 10 points, the first 8 in the river water of the upper Santa Rosa River basin, and samples 9 and 10 correspond to the treatment plant and household faucet. It is important to make this distinction because, according to the regulations used, the criteria for permissible limits are different for river water and water used for consumption.
Results of samples obtained in the upper Santa Rosa River basin:
The results of the monitoring of heavy metals in the river water samples obtained in the upper Santa Rosa River basin were compared with the respective regulations: EPA, WHO, INEN.
The values of the analyses obtained for heavy metals in river water in the upper Santa Rosa River basin, compared with the respective regulations, indicate that mercury exceeded the maximum permissible limits in samples 1 and 2, and cadmium in samples 2 to 5 exceeded the maximum permissible limits. This contamination could be due to the fact that at sampling points 1 and 2 there are mining concessions that spill leachate into the Santa Rosa River without any prior treatment.
Arsenic, according to the respective regulations, is above the permissible limit value in sample 2.
Results of the samples obtained at the Drinking Water Treatment Plant
The heavy metals of the samples taken at the drinking water plant and at the household faucet corresponding to samples 9 and 10 from the Santa Rosa canton respectively, sample 9 refers to the sample taken at the treatment plant, and sample 10 refers to the sample taken at the household faucet immediately after drinking water treatment, These values are compared with the results obtained from the respective monitoring of heavy metals Lead, Arsenic, Cadmium and Mercury, as shown in Table 3.
The results of the samples obtained at the drinking water plant for water entering without any prior treatment and for treated water were compared with the NTE INEN 1108 standard.
Sample 9, water from the drinking water treatment plant, showed that lead, arsenic, cadmium, and mercury comply with the maximum allowable limits established in the standard.
Sample 10, which corresponds to treated water obtained at the drinking water plant, whose values exceed the maximum limits of arsenic, cadmium and mercury allowed for drinking water, which can cause various health effects on the inhabitants of the city of Santa Rosa.
Comparison of the results of heavy metal analysis compared to previous years in the upper Santa Rosa River basin in the Quebrada El Panteón sector - El Guayabo sector.
the upper basin of the Santa Rosa River, analyses of heavy metals in the water have been conducted by the public drinking water company of the Santa Rosa canton (EMAPA SR). Table 4 shows the values of the analyses from 2012 to 2021 in a specific point such as the Quebrada El Panteón-Sector El Guayabo; in this place, mine wastewater is discharged without any prior treatment, which joins the Santa Rosa River.
Mercury in Quebrada El Panteón from 2012 to 2018 complied with the maximum permissible limits, but in 2019 it exceeded the permissible limits with a value of 0.0114 mg/l. According to our analysis, which is from 2021, mercury with a value of 0.00876 mg/l exceeded the limit stipulated in the standard.
Comparison of heavy metal results for samples 9 and 10:
Table 5 shows the results of heavy metals from 2012 to 2021, another important point of analysis, since the drinking water plant of the Santa Rosa canton supplies drinking water to 85% of its population, being essential to have water that meets the physical, chemical and microbiological parameters for the good of the public health of the population, in this case of the Santa Rosa community, one of the economic activities being mining.
According to our analysis of the year 2021, arsenic with a value of 0.015 mg/l exceeds the permissible range established in the standard and is harmful to human health.
Lead in the drinking water plant the years 2012,2014,2016,2017, 2018 and 2019 are within the maximum permissible limits; but the years 2013 and 2015 exceeded the permissible limits. According to our analysis in the year 2021 lead with a value of < 0.001 mg/l, complies with the maximum permissible limits.
According to our analysis that is the year 2021 cadmium with a value of 0.0106 mg/l, exceeds the maximum permissible limit established in the standard.
Mercury from the year 2012 to 2019 in the drinking water plant complied with the maximum permissible limits established in the standard. According to our analysis in 2021 mercury with a value of 0.0471 mg/l, exceeds the permissible ranges
Results of the surveys applied to the Santa Rosa community on water use:
A total of 349 surveys were conducted among the community living along the upper Santa Rosa River watershed, with the following results:
− 93% of the population living here uses river water and 7% does not use this water.
− 89% of the population has potable water in their homes and 11% does not have this service, so they use river water for their needs.
− 46% of the population uses river water for agriculture, 36% uses it for livestock and 18% for domestic activities.
− 89% of the population has potable water in their homes and 11% does not have this service, so they use river water for their needs.