**5.1 Temperature**

*Lagoon Environments Around the World - A Scientific Perspective*

account and assessed.

**4. Methodology**

any drainage system that is available.

On the basis of the results for monitoring, an attempt was made to identify the cause(s) and origin of the failure to comply with standards detected in the quality of the water and grounded on the occurrence of parameters that were outside the fixed standards and above the limits recommended. In light of this, analyses of the contributing basins adjoining the nearest discharge points were also taken into

On the basis of its history and previous experiences, as well as the analysis of the points that were being monitored by TECMA, it can be inferred that the values found above the limits can be, without question, related to the illegal links to the sewage and drainage system that discharged waste into the LRF. These links can in turn be attributed to the existence of some remaining vestiges of the informal occupation with regard to the respective drainage basins (and sanitary sewage overflow) in question. In areas of this nonformal typology, the local community lacked suitable sanitation (i.e., an appropriate coordinated system for collecting and/or disposal of the sanitary drainage of the buildings). As infiltration in the soil is not a feasible alternative, what tends to occur is that the effluent waste is discharged in

The first stage of the methodology employed was to conduct a survey of the bibliographical references, including those regarding the selection of the parameters adopted for this analysis. Several more specific data were investigated that are related to the local drainage basin and the sanitary sewage system, together with an analysis of the locality. The plants and records available of the drainage and sewage

These were investigated together with the responsible bodies, including the municipal government of Rio de Janeiro and CEDAE (The State Water and Sewage Company) and the historical data obtained through the monitoring of the quality of

There was also an analysis of the field measurement data and the specific collections of the samples taken from the surface water of the Lagoon. This took place twice a week during the period from January 1 to December 31, 2018, in the six sampling points that were strategically placed around the water body (LRF1 to LRF6). These data were made available by the TECMA, and a third party was responsible

Despite the wide array of parameters that were analyzed in the course of the monitoring plan, in the particular case of this study, the physicochemical parameters that were examined were as follows: temperature, salinity, pH, turbidity, dissolved oxygen, ammonia nitrogen, total phosphorus, and orthophosphate. The biological parameters included *Escherichia coli*. The selection of these parameters was based on their degree of importance in representing the hydric quality for required use and grounded on the bibliographical support provided by this study. It should be noted that the parameters for monitoring were the same as those employed by Mello [17]. The temperature, salinity, pH, turbidity, and concentration of dissolved oxygen were determined in situ by means of the portable field recording equipment with electrodes. The samples of water for the analysis of the other parameters were obtained with the aid of collecting bottles and packaged in polyethylene flasks of appropriate volumes. These were duly labeled and preserved and then packed in thermal boxes with ice and sent to the TECMA laboratory for analysis in a timescale that ensured the tests were carried out within the deadline for preserving validity.

systems were investigated together with the respective basins concerned.

the water carried out by the TECMA in the last few years.

for analyzing the samples of water from the Lagoon.

**38**

Temperature is a factor of paramount importance for the aquatic ecosystem because it plays an essential role in the control of the environment by influencing physical, chemical, and biological processes including vital factors such as primary productivity and the decomposition of organic matter [25, 26]. The Central Institution of the Environmental System of São Paulo (CETESB) [27] stresses the importance of analyzing the temperature of the water, since aquatic organisms have differentiated limits of thermal tolerance and the best temperatures for growth. Thus as high solar radiation naturally results in an increase in the temperature of the water, the supply of water used in refrigeration systems results in a rise in the receptor body which can lead to a reduction in the concentration of dissolved oxygen and/or an acceleration of the metabolism of the phytoplankton which is favorable for the occurrence of blooming. Alterations in temperature can also sharpen the sensation of taste and smell in the water [28].

In the period being analyzed, it was noted that there was a horizontal uniformity in terms of water temperature on the surface layer of the Rodrigo de Freitas Lagoon. The averages, with regard to the six sampling points, ranged from 24.1 to 30.0°C, with lower temperatures in winter and higher in summer (**Figure 5**).

## *5.1.1 Temperature and phytoplanktonic blooming*

It was noted that together with other factors, the high temperatures of the water in the Lagoon in the spring of 2018 could have favored the phytoplanktonic blooming of the cyanobacteria *Synechocystis* spp., which occurred in the period December 10–17. It should be underlined that the fact that cyanobacteria have a preference for high temperatures has been demonstrated in a number of studies [29–31].

When compared with the springs of 2014, 2015, and 2016, the parameter in 2018 was 1–1.5°C above the others as can be observed in **Table 6**.

#### **Figure 5.**

*Temperature of the surface of the LRF in 2018.*

### **5.2 Salinity**


#### **Table 6.**

*Average water temperature at the LRF during the monitored spring seasons.*

Salinity is another factor that influences the biodiversity of hydric bodies, since different species have different ways of adapting to concentrations of mineral salts [28]. They are reduced to colonies of brackish environments by aquatic animals and superior vegetation, owing to the difficulties of osmoregulation which, according to Reid and Esteves [32], constitute one of the main factors responsible for the low phytoplanktonic diversity of the coastal lagoons of the State of Rio de Janeiro.

In the same way as temperature, salinity can have a great influence on the stratification of the water bodies, since the density of the water increases when there is a rise in the concentration of salts [28]. Esteves [33] underlines the fact that when there is a rise in temperature, an increase in salinity reduces the capacity of the water for the dissolution of oxygen.

The values for salinity that were observed for spring 2018 were relatively low, and this can probably be attributed to the pluvial and fluvial effects of the waters and to a less extent, to the sea and evaporation (**Figure 6**). It was found that the three greatest falls in salinity occurred in the periods November 8, 19, and 26 and coincided with the heavy rainfall recorded on those days. Attention should also be drawn to the fact that there was a lack of an entry for water from the sea owing to the low tide, a failure in the operation of the floodgates, and the constant silting of the Jardim de Alah Canal.

This silting was also recorded by Kaippert [16] and Lima [5] as a factor that involved a marine influence on the LRF. It is also worth noting that the values

**41**

**5.3 pH**

**Figure 6.**

**Table 7.**

**Salinity**

*Salinity of the surface of LRF in 2018.*

*Environmental Monitoring of Water Quality as a Planning and Management Tool: A Case…*

recorded on the days in question in November 2018 were the lowest since the monitoring by TECMA first started in 2011 and that the parameter that can influence the

Averages at sampling points 2014 2015 2016 2018

15.4 14.4 16.6 10.4

In the spring of 2018, there were records of phytoplanktic blooming of the cyanobacteria *Synechocystis* spp., in the period December 10–17. Domingos et al. [1] argue that a rise in salinity is a limiting factor for the presence of cyanobacteria of the *Synechocystis* genus. This means that the reduction of the values of the parameter may have provided conditions that were favorable to their growth in the Lagoon. When compared with the springs of 2014, 2015, and 2016, the parameter was

Another key parameter for the monitoring of hydric bodies is the pH, because not only it influences the solubilization and sedimentation of metals and other substances, but also it acts in different ways on the metabolism of aquatic communities by making a direct intervention in the distribution of the organisms [33, 34]. The pH must be situated in values of 6.0–9.0 for the maintenance of aquatic life, since values outside this range are usually harmful to most aquatic creatures [35, 36]. The values of pH are caused by natural phenomena such as the dissolution of rocks, the absorption of atmospheric gases, oxidation of organic matter and photosynthesis, as well as anthropic factors like the discharge of domestic effluent

establishment of organisms includes the phytoplankton community.

between 4 and 6 units below the others in 2018 as induced in **Table 7**.

*5.2.1 Salinity and phytoplanktonic blooming*

*Average water salinity at the LRF during the monitored spring seasons.*

*DOI: http://dx.doi.org/10.5772/intechopen.88687*

*Environmental Monitoring of Water Quality as a Planning and Management Tool: A Case… DOI: http://dx.doi.org/10.5772/intechopen.88687*

#### **Figure 6.**

*Lagoon Environments Around the World - A Scientific Perspective*

Salinity is another factor that influences the biodiversity of hydric bodies, since different species have different ways of adapting to concentrations of mineral salts [28]. They are reduced to colonies of brackish environments by aquatic animals and superior vegetation, owing to the difficulties of osmoregulation which, according to Reid and Esteves [32], constitute one of the main factors responsible for the low phytoplanktonic diversity of the coastal lagoons of the

*Average water temperature at the LRF during the monitored spring seasons.*

Averages at sampling points 2014 2015 2016 2018

27.6 27.7 26.6 28.2

In the same way as temperature, salinity can have a great influence on the stratification of the water bodies, since the density of the water increases when there is a rise in the concentration of salts [28]. Esteves [33] underlines the fact that when there is a rise in temperature, an increase in salinity reduces the capacity of

The values for salinity that were observed for spring 2018 were relatively low, and this can probably be attributed to the pluvial and fluvial effects of the waters and to a less extent, to the sea and evaporation (**Figure 6**). It was found that the three greatest falls in salinity occurred in the periods November 8, 19, and 26 and coincided with the heavy rainfall recorded on those days. Attention should also be drawn to the fact that there was a lack of an entry for water from the sea owing to the low tide, a failure in the operation of the floodgates, and the constant silting of

This silting was also recorded by Kaippert [16] and Lima [5] as a factor that involved a marine influence on the LRF. It is also worth noting that the values

**40**

**5.2 Salinity**

**Figure 5.**

**Table 6.**

**Water temperature (°C)**

*Temperature of the surface of the LRF in 2018.*

State of Rio de Janeiro.

the Jardim de Alah Canal.

the water for the dissolution of oxygen.

*Salinity of the surface of LRF in 2018.*


#### **Table 7.**

*Average water salinity at the LRF during the monitored spring seasons.*

recorded on the days in question in November 2018 were the lowest since the monitoring by TECMA first started in 2011 and that the parameter that can influence the establishment of organisms includes the phytoplankton community.
