Heavy metals content in several rivers in Costa Rica

Costa Rica has many water resources; however, several of the rivers are highly contaminated. An important pollutant type is the heavy metals (HM) that can have an adverse health effect in people, animals, and plants as well. Its non-biodegradability and its bioaccumulation cause longlasting toxic effects. There is little information on HM in the rivers of Costa Rica; Therefore, the purpose of this research was to evaluate the quality of several rivers located in different regions of the country. Twenty-six sampling sites were selected, and 7 HM content were evaluated between 2017 and 2018. The metals selected were lead, total chromium, cadmium, mercury, copper, arsenic and nickel. The different HM were found in several sites. In general, there were no differences between HM concentrations during the dry season and the rainy season. The presence of arsenic was only found in the Tempisque and Toro rivers; in the first case, there values usually exceeded national regulations. Other HM were found in some evaluated sites and usually with concentrations close to the maximum recommended limit. The case of mercury stands out among the data since it is found in 61,5% of the sampled sites and, for the most part, they exceed national regulations.