Evaluation of the water quality of the Casacay
river in the province of El Oro
Evaluación de la calidad de agua del río Casacay
de la provincia de El Oro
Marcelo Álvarez Pico
Environmental Engineer and Master in Environmental
Management
Professor, Faculty of Natural Sciences, Universidad de
Guayaquil, Guayaquil, Ecuador.
marcelo.alvarezp@ug.edu.ec
ORCID:0000-0002-5935-2161
Williams Sánchez Arízaga
Biologist and Master of Science
Professor, Faculty of Natural Sciences, Universidad de
Guayaquil, Guayaquil, Ecuador.
williams.sancheza@ug.edu.ec
ORCID:0000-0002-2882-3039
Abstract
This research work will focus on analyzing the physical, chemical and
microbiological parameters of the water quality of the Casacay River in the
province of El Oro, since this water body is a source of water supply for several
cantons in this province. Using simple random methodology, several sampling
sites were established in the vicinity of the study area, where several
parameters were obtained by means of multiparametric equipment in situ and
later analyzed in the laboratory. It was evidenced that the first monitoring
complied with the maximum permissible limits, unlike the second monitoring,
where certain parameters: oils and fats, biological oxygen demand, and total
petroleum hydrocarbons, do not comply with the maximum permissible limits
of the quality criteria of water sources for human and domestic consumption
of the Ministerial Agreement 097-A. Therefore, the purpose of this study is
based on identifying the optimum values to establish water quality indicators
and guarantee a safe water source for drinking and final consumption.
Key words: Water quality, physical, chemical and microbiological
parameters, evaluation.
Resumen
En el presente trabajo de investigación se enfocará en analizar los parámetros
físicos, químicos y microbiológicos de la calidad de agua del río Casacay de
la provincia de El Oro, debido a que el cuerpo hídrico constituye una fuente
Pacific Oceanographic Record
DOI: https//doi.org/10.54140/raop.v3i2.63
Received July 19, 2022
Accepted December 11, 202
Vol 5. No. 1. 2023
ISSN: 1390-129X
ISSN: 2806-5522
Pg. 1-10
Evaluation of the water quality of the Casacay river in the province of El Oro.
2
de abastecimiento para diversos cantones de esta provincia. Mediante la
metodología aleatoria simple se establecieron diversos sitios de muestreo en
las cercanías del área de estudio, en donde se obtuvieron varios parámetros
mediante el equipo multiparamétrico de manera in situ y posteriormente
analizados en el laboratorio. Se evidenció que en el primer monitoreo se
cumplió con los límites máximos permisibles, a diferencia del segundo
monitoreo, en donde ciertos parámetros: aceites y grasas, demanda biológica
de oxígeno, e hidrocarburos totales de petróleo, no cumplen con los límites
máximos permisibles de los criterios de calidad de fuentes de agua para
consumo humano y doméstico del Acuerdo Ministerial 097-A. Por
consiguiente, la finalidad del presente estudio se basa en identificar los
valores óptimos para establecer los indicadores de calidad de agua y
garantizar una fuente de agua segura para su potabilización y consumo final.
Palabras clave: Calidad de agua, parámetros físicos, químicos y
microbiológicos, evaluación.
Introduction
Water is an invaluable and essential natural
resource for the continuity of life on the
planet, the same that represents the object
of study of the present study. The
composition of water supply sources varies
in time and space, and is directly affected
by chemical reactions and by the presence
and/or absence of biological organisms
(Raffo & Ruiz, 2014).
According to Guillén, et. al., (2012) the
interactions of chemical elements with the
properties of natural waters give rise to a
series of oxidation-reduction reactions,
which added to the demand for nutrients by
microorganisms establishes the dynamics
and kinetics of the water body. Chemical
and microbiological contaminants such as
phosphates, nitrates, chlorides,
hydrocarbons, coliforms, etc., present in
water can cause chronic and acute effects
on human health.
In the 2030 Agenda for Sustainable
Development, the quality of natural waters
is considered a standard, which is
associated with biogeochemical cycles,
since from its origin the hydrological cycle is
related to marine life, and also with
chemical compounds and emerging
contaminants, which can vary in their
organoleptic parameters such as turbidity,
mineralization, hardness, pH, odor, taste,
color, total coliforms, among others.
According to the World Health Organization,
2018, raised a Guideline for drinking water
quality, by which reference values are
established to assess water quality.
According to the NTE INEN 1108:2011
Standard, specific requirements and
maximum allowable limits are established to
evaluate the quality of drinking water for
their respective parameters.
The World Health Organization, 2021
mentions that the 2020 coronavirus crisis
highlighted that countries are facing more
frequent challenges related to water
scarcity and contamination of the
population. The United Nations, 2020
mentions that 2.2 billion people worldwide
do not have access to safe drinking water,
let alone good quality water.
As part of the objective of the water quality
assessment of the Casacay river in the
province of El Oro, the objective of the study
is to identify through analysis of physical,
Alvarez, M., Sanchez, W. Vol. 5. No. 1. 202 3
3
chemical and microbiological parameters, in
order to know the current state of the water
conditions for human consumption.
Literature review
This section will establish the relevant
concepts that are part of the conceptual
analysis of the physical, chemical and
microbiological parameters, among other
important aspects that will serve as a basis
and theoretical reference for this research.
Bioindicators
Biological indicators are living organisms
that are characterized by their high
sensitivity to environmental factors and the
changes that occur in them. This is related
to the presence or absence of species that
give rise to the characterization of the study
area through species identification.
Chemical characteristics of natural
waters
The composition of natural waters depends
on several factors, climatic, edaphological,
temporal, seasonal, among others. The
composition also depends on the presence
of elements and chemical compounds such
as gases, inorganic substances, sodium,
potassium, calcium, magnesium,
aluminum, iron, manganese, nitrogen,
phosphorus, silicon, chlorides, sulfates,
organic substances, trihalomethanes,
halogenated compounds and others.
Water pollution
Water pollution is defined as the presence
of substances in concentrations that imply a
risk to human health and the environment.
The excess of the values of physical,
chemical and biological parameters results
in the impairment of the use of the water
body. Water pollution represents the degree
of impurification that results in adverse
effects on human health of a population
during foreseeable periods.
Chemical contaminants
The main chemical contaminants in water
include petroleum products, nitrates,
insecticides, herbicides, persistent organic
compounds, sediments and excess organic
matter, phosphates, nitrates, mercury, lead,
cadmium, among others.
Microbiological contaminants
Microbiological contamination is related to
the unintentional and/or unintentional entry
of microorganisms into the water such as
bacteria, fungi, protozoa, viruses, and the
addition of toxins originated during the
growth and incubation stages in the host
organism.
Emerging contaminants
Emerging contaminants are those chemical
substances that have not been previously
detected by a conventional physical-
chemical analysis, which are usually
present in very small quantities in water.
Among the most frequent emerging
compounds present in water are
pharmaceutical and personal care products
and by-products, contraceptives, persistent
organic compounds, pesticides and
microplastics.
Water quality indexes
Water quality assessment is associated
with the evaluation of physical, chemical,
and biological characteristics in accordance
with natural quality, uses, and possible
effects on human health. That is, a water
quality index is associated with a single
value that reflects the quality of the water
body by interrelating measurements of
certain universal solvent parameters.
Evaluation of the water quality of the Casacay river in the province of El Oro.
4
Heavy metals
Heavy metals are arranged in the periodic
table as chemical elements of high density,
usually greater than 4 g/cm
3
. Another
important characteristic is that heavy metals
are toxic at low concentrations.
There are studies of cases of heavy metal
poisoning due to the consumption of water
contaminated with metals such as
cadmium, mercury, lead, among others,
whose concentrations affect the human
body depending on age, body mass and
sex.
Materials and methods
The present research was carried out on
February 11 and June 12, 2020 in different
points of the Casacay river, where random
sampling or simple sampling was applied to
obtain the results, all samples in the quantitative
approach as mentioned by Hernandez (2014)
must be significant; therefore, the use of
random processes only denotes a type of
mechanical procedure closely related to
probability and the choice of element.
The following coordinates were taken in the
study area with UTM WGS 84 zone 17 South
datum as shown in Table 1.
Table 1: Coordinates of sampling points.
POINTS
X (EAST)
Y (NORTH)
1
632773
9640499
632846
9640499
632846
9640418
632773
9640418
5
632773
9640499
Sampling method
Three points along the Casacay River were
considered, identifying the places that could be
accessed, since the sector is surrounded by
abundant shrub flora. The coordinates were
recorded in Table 1. For this, a simple point
sampling was used following INEN 2169: 2013
and INEN 2176-2013 Standards; six containers
equivalent in total to 4 liters of water per
sampling point were taken from each point and
stored in plastic and glass containers; in
addition, the measurement was performed in
situ using a 3630WTW multiparametric
equipment to determine values in the following
parameters: Dissolved Oxygen, pH, Total
Suspended Solids, Temperature, and Turbidity.
Simple sampling technique
It is known as a point sample when the sample
is manually collected only once and the
researcher needs to know a data of the process
immediately, this serves to determine
parameters such as dissolved oxygen, pH, and
temperature; representing the composition of
the water at the time the sampling was
performed (Calderón, 2017).
Sampling plan
In this research study, a field visit was made to
the Casacay River. Once the study area was
known (Figure 1), a field trip plan was prepared
to collect samples according to the established
schedule.
Alvarez, M., Sanchez, W. Vol. 5. No. 1. 202 3
5
Figure 1. Map of the study area
Sampling phase
The execution of the sampling phase was
carried out on February 11 and June 12, 2020
from 10 am to 16 pm, then proceeded to
perform the in situ analysis of the parameters
previously established with the multiparametric
equipment, the containers were homogenized
three times in the surface water in the center of
the stream, The sample was then collected in
the opposite direction to the water flow with the
respective containers. Six containers were used
for each sampling point and each one was
labeled to be placed in the thermal box for its
correct preservation and not to affect the
sample.
During the entire sampling procedure, along
with the respective chain of custody,
transportation and on-site analysis, the steps
stipulated in the technical standards INEN
2169:2013 - INEN 2176:2013 were followed.
Subsequently, the samples were sent to the
SAE accredited laboratory to analyze the
samples, and thus compare with the parameters
to be evaluated according to Ministerial
Agreement 097-A (Reform Unified Text of
Secondary Legislation) in Official Gazette No.
387 of November 04, 2015, from Table 2: Water
quality criteria for the preservation of aquatic
and wildlife life in fresh waters, and marine and
estuarine waters.
Evaluation of the water quality of the Casacay river in the province of El Oro.
6
Results
Population and sample
By means of simple random sampling, the
following results were obtained, as shown in
Table 2:
Table 2. Concentrations of the parameters evaluated in the study area.
Parameters
Results of
Monitoring 1
Results of
Monitoring
2
Units
National
environmental
quality criteria
International
reference
values **
International
reference
values **
International
reference
values **
International
reference
values **
International
reference
values **
International
reference
values **
International
reference
values
Oils and Fats
<0.3
0.49
mg/L
0.3
---
Arsenic
<0.005
<0.005
mg/L
0.1
0.01
Barium
<1.8
<0.008
mg/L
1
1.3
Cadmium
<0.01
<0.001
mg/L
0.02
0.003
Hexavalent
chromium
<0.1
<0.1
mg/L
0.05
---
Fecal coliforms
<1.1
<1.1
MPN/100
mL
1000
Not to be
detected in any
100 ml sample.
Total Coliforms
<1.1
<1.1
MPN/100
mL
----
Not to be
detected in any
100 ml sample.
Color
<20
<20
Platinum
and cobalt
units
Organochlorine
compounds
<0.005
<0.005
mg/L
----
----
Organophosphorus
compounds
<0.005
<0.005
mg/L
----
----
BOD
<2
mg/L
<2
---
COD
<5
<5
mg/L
<4
---
Phenols
<0.1
<0.1
mg/L
---
0.009
Total Petroleum
Hydrocarbons
<0.3
0.4
mg/L
0.2
Taste and odor
are detected in
concentrations
of
lower than those
of health
Alvarez, M., Sanchez, W. Vol. 5. No. 1. 202 3
7
concern,
especially for
short-term
exposure.
Nitrates
<8
<8
mg NO3- /L
Nitrites
<0.05
<0.05
mg NO2- /L
0.2
Dissolved Oxygen
5.6
4.8
mg/L
---
---
pH
8.3
pH units
6-9
6.5 - 8.0
Total Suspended
Solids (TSS)
<10
mg/L
---
Do not
represent a
health problem
Sulfates
mg SO
4
- /L
Temperature
30.4
30.2
°C
---
High water
temperature
enhances the
proliferation of
microorganisms
and can
increase taste,
odor, color and
corrosion
problems.
Surfactants
<0.1
<0.1
mg/L
---
It should not be
allowed to
The
concentration of
detergents in
water for human
use and
consumption
reaches levels
that cause
foaming or taste
problems.
Turbidity
1.98
1.13
NTU
* Ministerial Agreement No. 097-A, 2015.
Agreement. Special Edition No. 387 of the
Official Gazette. November 4, 2015.
**Guidelines for drinking water quality, WHO
2018.
Conclusions
The water quality obtained at the sampling
sites of the Casacay River in the province of El
Oro is considered to comply with the maximum
permissible limits as a source of water for
human consumption.
In the second monitoring, the parameters oils
and fats, biological oxygen demand, total
petroleum hydrocarbons and dissolved oxygen
did not comply with the maximum permissible
limits of the Quality Criteria for Water Sources
for Human and Domestic Consumption of
Ministerial Agreement 097-A.
It is true that at the national level there is a
technical standard NTE INEN 1108:2011,
regarding the quality criteria for drinking water
for human consumption, which is very limited.
In reference to the second monitoring, there
was an increase in the evaluation of the
parameters total petroleum hydrocarbons and
oils and greases due to the presence of vehicle
maintenance activities in the vicinity of the
sampling sites.
The water quality parameters in the present
study contribute to the monitoring of the quality
Evaluation of the water quality of the Casacay river in the province of El Oro.
8
index as part of a culture of disease prevention in the population of the province of El Oro.
References
Ministerial Agreement No. 097-A, 2015.
Agreement. Special Edition No. 387
of the Official Gazette. November 4,
2015.
Alcívar, J. 2016. Physical-chemical quality
of the salt marsh quarantine area in
2016. University of Guayaquil.
Álvarez, A., Pérez, M., & Macías, A. 2015,
October 5. Environmental zoning
criteria: case study estero salado de
Guayaquil - Ecuador. Revista
Científica ECOCIENCIA, Segundo.
http://ecociencia.ecotec.edu.ec/uplo
ad/php/files/numero1/01.pdf.
Alvear, G., & Omarza, F. 2014. Spatial and
intertidal variation of oils and fats in
the salty estuary in guayaquil,
ecuador [Universidad de
Especialidades Espiritu Santo].
http://repositorio.uees.edu.ec/handle
/123456789/2206
Baños, L. 2012. Distribution and
concentration of total coliforms, fecal
coliforms, Escherichia coli and
Enterococci in water and sediment in
the salty estuary (sections B, D, E
and G) [Universidad de Guayaquil].
http://repositorio.ug.edu.ec/handle/r
edug/810
Barros, D., Castro, D., & Pino, S. 2020.
Calidad De Agua Del Estero Salado
Y Su Incidencia En La Fauna
Acuática, Sector La Chala -
Guayaquil. IOSR Journal of Applied
Chemistry (IOSR-JAC, 13, 18-24.
https://doi.org/10.9790/5736-
1303021824
Bolaños-Alfaro, J. D., Cordero-Castro, G., &
Segura-Araya, G. 2017.
Determination of nitrites, nitrates,
sulfates and phosphates in drinking
water as indicators of man-made
contamination in two cantons of
Alajuela (Costa Rica). Revista
Tecnología En Marcha, 30(4), 15.
https://doi.org/10.18845/tm.v30i4.34
08.
https://doi.org/10.18845/tm.v30i4.34
08
Bravo, C., Osorno, C., & Salgado, E. 2016.
Propuesta de un tratamiento para
aceites y grasas de las aguas
residuales de las aguas residuales
de la microempresa "productos
verdes" laboratorio de biotecnologia,
UNAN - Managua, MARZO - JULIO
2016 [Universidad Nacional
Autónoma de Nicaragua, Managua].
https://repositorio.unan.edu.ni/3504/
1/61591.pdf
Caicedo, J. 2020. Spatial evaluation of the
macroinvertebrate community as a
tool for measuring water quality of
the San Enrique estuary, Duran
[Universidad Agraria del Ecuador].
https://cia.uagraria.edu.ec/cia_inv_vi
ew.php?id=30437&option=view
Calderon. 2017. Strategic Plan
Environmental Quality Laboratory
(Lca 2016- 2022).
http://www.ideam.gov.co/documents
/24189/359218/PLAN+ESTRATEGI
C+ Campbell, N., & Reece, J. (2007).
Campbell and Reece's Biology. In
Biologia Séptima Edición (Septima).
Editorial Medica Panamericana.
Carangui, G., & Pólit, P. 2017.
Determination of the water quality
index of the salty estuary between
the 5 de Junio bridge and the El
Velero bridge [Universidad de
Guayaquil].
http://repositorio.ug.edu.ec/bitstrea
m/redug/29111/1/401-1296 -
Alvarez, M., Sanchez, W. Vol. 5. No. 1. 202 3
9
Determinación agua del estero
salado.pdf.
Cheme, A. 2020. Evaluation of the water
quality of the salty estuary area
Puente Gómez Rendón in Guayaquil
during the years 2017 and 2020
[Universidad de Guayaquil].
www.fcq.edu.ec
EPA 2021, June 3. The Challenges
of the Estuaries|USEPA .
https://espanol.epa.gov/espanol/los-
retos-de-los-estuarios.
Escobar, J. 2002. River pollution and its
effects on coastal areas and the sea.
Natural Resources and
Infrastructure Series, 50(1680-
9017), 68.
Garnica, M. 2019. Comparison of
biopolymers and their efficiency in
the elimination of suspended organic
matter in waters of the San Camilo-
Cantón Durán estuary [Facultad de
Ciencias Naturales. Universidad de
Guayaquil].
http://repositorio.ug.edu.ec/handle/r
edug/44795
Gil, M., Soto, A., Usma, J., & Gutiérrez, O.
(2012). Emerging contaminants in
waters, effects and possible
treatments. Scielo, 7(2).
Guillén, V., Teck, H., Kohlmann, B., &
Yeomans, J. 2012. Microorganisms
as Bioindicators of water quality.
Tropical Earth, 8(1), 65-93.
Hernadez, R. 2014. Research
methodology. In Metodología de la
Investigacion (Sexta, Vol. 6, Issue
metodologia de la investigacion).
McGRAW- HILL /
INTERAMERICANA EDITORES,
S.A. DE C.V.
Isch L., E. 2011. Water Pollution and
Policies to Address It. In Foro de los
Recursos Hídricos (Vol. 1, Issue 1).
https://issuu.com/edgarisch/docs/co
ntaminacion_de_las_aguas_y_politi
Limongi, M. 2016. Analysis of the presence
of nitrogenous compounds in the
sediments of the San Camilo
estuary. University of Espiritu Santo
Specialties.
MAATE 2016.
EstrategiaNacionaldeCalidad
delAguaENCA.
https://www.controlsanitario.g
ob.ec/wp-
content/uploads/downloads/downloa
ds/2019/05/Estrategia-Nacional-de-
Calidad-del- Agua_2016-2030.pdf.
Mihelcic, J., & Zimmerman, J. 2012.
Environmental engineering :
fundamentals, sustainability and
design (First). Alfaomega Grupo
Editor, S.A.
Montoya, H. A., Contreras, C., & García, V.
1997. Integral Study of Water Quality
in the State of Jalisco. Com. Nal.
Agua, Geren., Reg. Lermasantiago,
Guadalajara, 106.
Olaya, P. 2016. Ecological status of the
estuarine system of the Guayas
River, Canton Durán, Ecuador:
Numerical simulation of its fluvial
dynamics and ecological principles
for the design of restoration and/or
recovery actions. University of
Alcalá.
WHO, O. (2018). Guidelines for drinking
water quality.
Orozco, A. 2014. Wastewater
bioengineering: Theory and design.
Second edition.
Pesantes, B. 2021. Water quality in micro-
watersheds of streams: Las Pavas-
Shushuhuayco - Turunuma and of
the cemetery in western
neighborhoods of the city of Loja,
Loja province [Facultad de Ciencias
Evaluation of the water quality of the Casacay river in the province of El Oro.
10
Naturales. Universidad de
Guayaquil].
http://repositorio.ug.edu.ec/handle/r
edug/53453
Pradana-Pérez, J. Á. and García, J. , 2019.
Quality criteria and drinking water
management. UNED - National
University of Distance Education.
Raffo, E., & Ruiz, E. 2014. Characterization
of wastewater and biochemical
oxygen demand.
https://www.redalyc.org/pdf/816/816
40855010.pdf Ramsar. (2010).
Wetlands in danger of disappearing
worldwide.
W. E. 2018. Assessment of
physicochemical and microbiological
contamination of Estero Salado
waters. Dominion of The Sciences,
3(4), 672-691.
https://doi.org/10.23857/DOM.CIEN.
POCAIP.2017.3.4.OCT.672-691
Rojas, W. 2017. Evaluation of the water
quality of the salty estuary for
recreational purposes by secondary
contact, between the Zigzag and 5
de Junio bridges [Faculty of Natural
Sciences. University of Guayaquil].
http://repositorio.ug.edu.ec/handle/r
edug/21033
Saavedra, C. 2009. The management,
protection and conservation of water
sources and natural resources (W.
Rivera (ed.)). Ministry of Water,
through the Vice-Ministry of Water
Resources and Irrigation Bolivia.
Severiche, C., Luna, J., & González, H.
2013. Analytical evaluation for the
determination of total phosphorus in
waters by the ascorbic acid method
(Issue 17).
Torres, P., Cruz, C. H., & Patiño, P. J. 2009.
Water quality indices in surface
sources used in the production of
water for human consumption: A
critical review. Revista Ingenierías
Universidad de Medellín, 8(15), 79-
94.
IUCN 2018. Participatory water quality
monitoring guide. International Union
for Conservation of Nature (IUCN).
UNEP 2016. A Snapshot of the World's
Water Quality: Towards a global
assessment. United Nations
Environment Programme.
https://uneplive.unep.org/media/doc
s/assessments/unep_wwqa_report_
web.p df
Vallejo, D. 2016. Determination of the level
of water pollution produced by the
fish farming activity in the flor del
valle estuary in the parish of puerto
libre, canton gonzalo pizarro
province of sucumbios [Universidad
Nacional de Loja].
https://dspace.unl.edu.ec/jspui/bitstr
eam/123456789/17876/1/Daniel
Benigno Vallejo Peñafiel.pdf
Zarzosa González, H. J. and Aragoneses
López, S. 2020. Fundamentals of
environmental and water
engineering. Dextra Editorial.
https://elibro.net/es/ereader/uguaya
quil/148270?page=54
