**5.3 pH**

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

**Figure 7.** *pH of the surface of LRF in 2018.*

(oxidation of organic matter) and industrial waste, which underlines the importance of this parameter in the assessment of human interference in the quality of water [35]. In the case of the lagoons which undergo influence from the sea, the salt water can bring about large quantities of carbonate and bicarbonate ion by causing a rise in pH, in the same way that an increase in rainfall can lead to a reduction of the values. In environments where there is a high phytoplanktonic density, the pH can naturally reach values above 9.0 during the period of maximum sunlight, owing to the photosynthetic activity of the algae which consume the CO2 [37].

The average surface values of the pH range from 7.42 to 8.35, with maximum values being recorded in the spring (**Figure 7**). It was noted that during the year of 2018, all the maximum surface values of pH surpassed the maximum limit of the 6.5–8.5 bands that was established by law for brackish waters of class 2.

#### *5.3.1 pH and the phytoplanktonic blooming*

When compared with the springs of 2014, 2015, and 2016, the parameter in 2018 was slightly above the others, which as pointed out by CETESB [27] might be linked to greater photosynthetic activity caused by a higher intake of CO2 as induced in **Table 8**.

It is noteworthy that in the spring of 2018, there was a blooming of the cyanobacteria *Synechocystis* spp.

## **5.4 Turbidity**

Alterations in the penetration of light are described as turbidity, and this can be caused by particles in suspension such as bacteria, phytoplankton clays, silting, organic and inorganic detritus, and dissolved compounds [25, 33]. Apart from a rise in the turbidity of the waters caused by a discharge of effluent, a natural phenomenon that also causes this rise is the erosion of the shores of the water bodies in periods of heavy rainfall. Since a high level of turbidity hinders the penetration of the solar rays in the water, this is able to reduce the photosynthesis of the plants and submerged algae and, as a result, influence the dynamics of the local biological community. In addition, it has an adverse effect on the domestic, industrial, and recreational use of the water in question [26].

**43**

**5.5** *Escherichia coli*

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

Averages at sampling points 2014 2015 2016 2018

7.9 8.1 8.3 8.4

The Lagoon showed low levels of turbidity for most of the year although some peaks were observed, particularly in the summer and spring which are the months with most rainfall. The averages in the seasons when the sampling was carried out

It was found that in the collection of November 26, there was a sharp rise in all the points of the parameter that is represented by the maximum values observed in spring. These results reflected the heavy rains recorded on that day, when the second highest accumulation of rainfall in the year was recorded in a period of 24 h (102.60 mm). Rosman [4] points out that since it is the lowest point of the hydrographic basin, the LRF has enormous inflows of dissolved substances carried along by the force of the downpours of rain. It should be noted that although the legislation (CONAMA 357/2005) does not determine the maximum value for the parameter, in the case of brackish waters, it recognizes that there are virtually no

However, when compared with the springs of 2014, 2015, and 2016 in **Table 9**, the spring of 2018 did not stand out with regard to the turbidity parameter. It is noteworthy that the spring of 2014 was the driest among all the monitored spring seasons.

The role of the microorganisms in the aquatic environment is essentially confined to transforming matter within the cycle of various elements with a view to obtaining energy for survival. The decomposition of organic matter into simpler substances, which is largely carried out by putrefactive bacteria, is one example of these changes. This is because it is vital for the aquatic environment, given the

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

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

**pH**

**Table 8.**

**Figure 8.**

range from 3.2 to 6.2 NTU (**Figure 8**).

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

signs of substances that produce turbidity.

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


#### **Table 8.**

*Lagoon Environments Around the World - A Scientific Perspective*

(oxidation of organic matter) and industrial waste, which underlines the importance of this parameter in the assessment of human interference in the quality of water [35]. In the case of the lagoons which undergo influence from the sea, the salt water can bring about large quantities of carbonate and bicarbonate ion by causing a rise in pH, in the same way that an increase in rainfall can lead to a reduction of the values. In environments where there is a high phytoplanktonic density, the pH can naturally reach values above 9.0 during the period of maximum sunlight, owing to the photosynthetic activity of the algae which consume

The average surface values of the pH range from 7.42 to 8.35, with maximum values being recorded in the spring (**Figure 7**). It was noted that during the year of 2018, all the maximum surface values of pH surpassed the maximum limit of the

When compared with the springs of 2014, 2015, and 2016, the parameter in 2018 was slightly above the others, which as pointed out by CETESB [27] might be linked to greater photosynthetic activity caused by a higher intake of CO2 as induced in **Table 8**. It is noteworthy that in the spring of 2018, there was a blooming of the cyano-

Alterations in the penetration of light are described as turbidity, and this can be caused by particles in suspension such as bacteria, phytoplankton clays, silting, organic and inorganic detritus, and dissolved compounds [25, 33]. Apart from a rise in the turbidity of the waters caused by a discharge of effluent, a natural phenomenon that also causes this rise is the erosion of the shores of the water bodies in periods of heavy rainfall. Since a high level of turbidity hinders the penetration of the solar rays in the water, this is able to reduce the photosynthesis of the plants and submerged algae and, as a result, influence the dynamics of the local biological community. In addition, it has an adverse effect on the domestic, industrial, and

6.5–8.5 bands that was established by law for brackish waters of class 2.

*5.3.1 pH and the phytoplanktonic blooming*

recreational use of the water in question [26].

bacteria *Synechocystis* spp.

**5.4 Turbidity**

**42**

**Figure 7.**

the CO2 [37].

*pH of the surface of LRF in 2018.*

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

**Figure 8.** *Turbidity of the surface of the LRF in 2018.*

The Lagoon showed low levels of turbidity for most of the year although some peaks were observed, particularly in the summer and spring which are the months with most rainfall. The averages in the seasons when the sampling was carried out range from 3.2 to 6.2 NTU (**Figure 8**).

It was found that in the collection of November 26, there was a sharp rise in all the points of the parameter that is represented by the maximum values observed in spring. These results reflected the heavy rains recorded on that day, when the second highest accumulation of rainfall in the year was recorded in a period of 24 h (102.60 mm). Rosman [4] points out that since it is the lowest point of the hydrographic basin, the LRF has enormous inflows of dissolved substances carried along by the force of the downpours of rain. It should be noted that although the legislation (CONAMA 357/2005) does not determine the maximum value for the parameter, in the case of brackish waters, it recognizes that there are virtually no signs of substances that produce turbidity.

However, when compared with the springs of 2014, 2015, and 2016 in **Table 9**, the spring of 2018 did not stand out with regard to the turbidity parameter. It is noteworthy that the spring of 2014 was the driest among all the monitored spring seasons.

#### **5.5** *Escherichia coli*

The role of the microorganisms in the aquatic environment is essentially confined to transforming matter within the cycle of various elements with a view to obtaining energy for survival. The decomposition of organic matter into simpler substances, which is largely carried out by putrefactive bacteria, is one example of these changes. This is because it is vital for the aquatic environment, given the


#### **Table 9.**

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

fact that the resulting nitrates, phosphates, and sulfates are reassimilated by other organisms in the environment [36]. Nonetheless, there are also microorganisms that are potentially an obstacle to the maintenance of the quality of the water body.

For this reason, a biological parameter of crucial importance in monitoring the quality of the water is the number of coliforms, in particular those that are thermotolerant and are present in the sample obtained. Since in most circumstances, the populations of thermotolerant coliforms predominantly consist of *Escherichia coli*, this group is regarded as a suitable indicator of the quality of the water since its presence is a sign of recent fecal contamination [36, 38]. The limit of *E. coli* used by SMAC for the Lagoon is based on the CONAMA Resolution 357/2005, which is 2000 NMP/100 mL.

In 2018, the densities of *Escherichia coli* showed a wide variation, although without any seasonal fluctuation being characterized (**Figure 9**). However, it should be noted that in winter, the average density was, in general terms, reduced, whereas in summer and spring, (the period with more rainfall), the maximum and average values were higher. It was found that that the results were a great deal higher at the points LRF1 and LRF2.

When compared with the springs of 2014, 2015, and 2016 in **Table 10**, the parameter for 2018 was between 5 and 30 times higher than the others.

Some of the factors that can influence the colimetrics results in the LRF are as follows: entries of organic matter through surface drainage, the opening of the floodgates, and the entry of the sewer system originating from an excessive number of leaks in the culverts during periods of rainfall [7, 8, 15]. In addition, there are often reports of the discharges of effluent in periods of drought at the rainwater

**45**

**Figure 10.**

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

outlets arranged around the Lagoon, as already mentioned [16, 17]. The presence of ammonia in the water can be detected through the reaction of the *Nessler* reagent to a qualitative test for the presence of ammonia, which is an indicator of recent drainage.

Averages at sampling points 2014 2015 2016 2018

163 1.179 168 4,745

Ammonia nitrogen is formed by ammonia species (NH3) and ion ammonia (NH4+), which is the most toxic species in the aquatic organisms [39]. The CONAMA Resolution 357/2005 stipulates 0.70 mg/L N as the limit of total ammonia nitrogen for the brackish waters of class 2, regardless of the pH [40]. Nitrogen is regarded as one of the most important elements in the metabolism of aquatic ecosystems for directly protecting aquatic life. This is also due to its role in the

The values of ammonia nitrogen showed a wide variation in 2018, although the seasonal fluctuations were not defined (**Figure 10**). However, it should be pointed out that, generally speaking, in summer the averages were reduced, while spring showed the highest maximum values, with the detection of a considerable increase in the parameter after heavy rainfall, mainly on October 15 and November 26. This rise in ammonia nitrogen can be attributed to the entry of organic matter and other

The inorganic forms of nitrogen, mainly ammonia nitrogen and nitrate, are ideally assimilated by phytoplankton [41–43]. During the period of phytoplanktonic blooming which took place between December 10 and 17, 2018, there was a reduction in the values of ammonia nitrogen, with a subsequent rise of the parameter at

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

*Average Escherichia coli at the LRF during the monitored spring seasons.*

*Escherichia coli* **(NMP/100ml)**

formation of proteins and chlorophyll [33].

**5.6 Ammonia nitrogen**

**Table 10.**

substances into the Lagoon.

the end of the blooming period.

*Ammonia nitrogen on the surface of the LRF in 2018.*

**Figure 9.** *Escherichia coli in the surface of the LRF in 2018.*

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


**Table 10.**

*Lagoon Environments Around the World - A Scientific Perspective*

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

fact that the resulting nitrates, phosphates, and sulfates are reassimilated by other organisms in the environment [36]. Nonetheless, there are also microorganisms that are potentially an obstacle to the maintenance of the quality of the water body. For this reason, a biological parameter of crucial importance in monitoring the quality of the water is the number of coliforms, in particular those that are thermotolerant and are present in the sample obtained. Since in most circumstances, the populations of thermotolerant coliforms predominantly consist of *Escherichia coli*, this group is regarded as a suitable indicator of the quality of the water since its presence is a sign of recent fecal contamination [36, 38]. The limit of *E. coli* used by SMAC for the Lagoon is based on the CONAMA Resolution 357/2005, which is 2000

Averages at sampling points 2014 2015 2016 2018

2.2 7.0 5.3 5.9

In 2018, the densities of *Escherichia coli* showed a wide variation, although without any seasonal fluctuation being characterized (**Figure 9**). However, it should be noted that in winter, the average density was, in general terms, reduced, whereas in summer and spring, (the period with more rainfall), the maximum and average values were higher. It was found that that the results were a great deal higher at the

When compared with the springs of 2014, 2015, and 2016 in **Table 10**, the

Some of the factors that can influence the colimetrics results in the LRF are as follows: entries of organic matter through surface drainage, the opening of the floodgates, and the entry of the sewer system originating from an excessive number of leaks in the culverts during periods of rainfall [7, 8, 15]. In addition, there are often reports of the discharges of effluent in periods of drought at the rainwater

parameter for 2018 was between 5 and 30 times higher than the others.

**44**

**Figure 9.**

*Escherichia coli in the surface of the LRF in 2018.*

NMP/100 mL.

**Turbidity (NTU)**

**Table 9.**

points LRF1 and LRF2.

*Average Escherichia coli at the LRF during the monitored spring seasons.*

outlets arranged around the Lagoon, as already mentioned [16, 17]. The presence of ammonia in the water can be detected through the reaction of the *Nessler* reagent to a qualitative test for the presence of ammonia, which is an indicator of recent drainage.
