In various natural sources of surface water in Ecuador, as well as in others worldwide, the concentration of arsenic exceeds the permissible limits (10 μg / L) established by the World Health Organization. The objective of these investigation was to determine the levels of arsenic in surface water and sediments in the Carrizal river basin (Manabí, Ecuador), an area that has an important agricultural activity. 21 stations in three areas were monitored, covering an area of 51 km. Arsenic concentrations in water and sediment were evaluated by means of atomic absorption spectrometry with the PerkinElmer® AAnalyst ™ 200 kit, in accordance with the guidelines of Standard Methods Edition 2015, by the APHA AWWA WEF 3114- B methodology. The experimental design of random blocks was applied, with a factorial arrangement of the three sampling areas. The indicated results are found for arsenic o...

ABSTRACT. The objective of this research is to identify the self-purification capacity of the organic matter of the Carrizal River, factors that influence its quality, starting from the point of discharge of wastewater from the oxidation pond in the city of Calceta to the water purification plant "La Estancilla. Several monitoring and analyses were performed, such as flow, pH, temperature, dissolved oxygen and organic matter, using the Protocol for Monitoring Water Resources of Peru, taking 4 points before, during and after the discharge of domestic wastewater, with a sample at a white point as a reference, taken during the low water season of 2019 (September, October and November). For the definition of these points, an information survey of the study area was carried out with ArcGis v10.4.1 software using a georeferenced map with the sampling locations. Organic matter (BOD5) was analyz...