Universidade Federal de Santa Maria

Ci. e Nat., Santa Maria, v. 41, e15, 2019.

DOI: http://dx.doi.org/10.5902/2179460X36915

Received: 15/02/2019 Accepted: 13/04/2019

Section Environment

pH values and presence of Escherichia coli in human water supply in an area of intense swine activity

Eliana Aparecida Cadoná

Eduarda Carvalho Rampinelli

Alcenir Claudio Bueno

Andrei Lucas Bez Tieppo

Claudio Roberto Fonseca Sousa Soares

Eduardo Lorensi de Souza

Guilherme Wilbert Ferreira

Cledimar Rogério Lourenz

^I   Doutoranda em Manejo e Conservação do Solo e da Água na Universidade Federal de Pelotas. Universidade Federal de Santa Catarina, SC, Brasil - elianacadona@yahoo.com.br

^II  Universidade Federal de Santa Catarina, SC, Brasil – eduardarampinelli@gmail.com

^III  Universidade Federal de Santa Catarina, SC, Brasil – alcenircbueno@gmail.com

^IV  Graduando, Universidade Federal de Santa Catarina, SC, Brasil – andreitieppo@yahoo.com.br
^V   Doutor, Universidade Federal de Santa Catarina, SC, Brasil – crfsoares@gmail.com

^VI  Doutor, Universidade Estadual do Rio Grande do Sul, RS, Brasil – elorensi@yahoo.com.br

^VII Doutorando do Programa de Pós-Graduação em Agroecossistemas pela Universidade Federal de Santa Catarina, SC, Brasil – guilhermewfereira@hotmail.com

^VIIIDoutor, Universidade Federal de Santa Catarina, SC, Brasil – lourenzicr@gmail.com

Abstract

Intensive swine activity in Santa Catarina presents itself as an environmental problem related to the management of the manure generated by this activity. Thus, it is usual to apply the waste in agricultural areas near the units of production of pigs, however, this practice when carried out without technical recommendation can cause soil and water sources pollution and/or contamination. The aim of this study was to evaluate the pH values and E. coli presence in water sources in a region with intense swine activity in the State of Santa Catarina. Lentic and lotic water sources were evaluated in four rural properties and in the Coruja River, in the watershed of Coruja/Bonito River, in the municipality of Braço do Norte/SC, being that the pH values in water and the presence and quantification of thermotolerant coliforms, represented by the bacteria Escherichia coli, throught CONOMA resolution nº357/2005, were determinated. The pH values were below the minimum limit established by the legislation and, for the bacteriological evaluation, the study points were below the limit established by the legislation also. However, the presence of these microrganisms indicates the constant arrival of material of enteric origin.

Key-words: Environmental contamination. Swine Manure. Bacteriological evaluation.

1 Introduction

The swine industry is an agricultural activity based on a package of production of a large number of animals in an intensive confinement system, which is being developed in some countries through large productions chains. In this sense, the swine industry stands out as one of the main economic activities in many regions, especially the Southern Region of Brazil, with an emphasis to Rio Grande do Sul (RS) and Santa Catarina (SC) states, being that this activity has a greater development in the Western and Southern Regions of SC state (GATIBONI et al., 2015).

This swine production system has whipped up discussions about the great environmental pressure, since there is a high volume of waste that can be used in agricultural areas within production unit or in areas of third parties, in order to promote a nutrient cycling in the production system, as well as improvement in the physical, chemical and biological attributes of the soil. As an example, we can point to the increase of soils content of total organic carbon (COMIN et al., 2013); increase of aggregation rates and stability of aggregates in water (LOSS et al., 2017); changes in soil chemical attributes, such as the increase of pH values and decrease in Al saturation (LOURENZI et al., 2011; BRUNETTO et al., 2012); and increase of available nutrient contents such as P, K, Ca and Mg (GUARDINI et al., 2012; LOURENZI et al., 2013). In addition to increase of nutrient content in the soil, the application of swine manure promotes gains in the biological part, due to the presence of organic material, the activity of soil organisms increases, especially the microorganisms that are responsible for the nutrient cycling (MARTÍNEZ-GARCIA et al., 2017).

Despite the benefits of the use of swine manure as a source of nutrients, when applied above the soils support capacity, the processes of nutrient runoff and percolation can accelerate causing, in addition to soils contamination, the contamination of surface and subsurface water sources (CAPOANE et al., 2015). Nitrogen (N) and phosphorus (P) are among the nutrients found in pig slurry (PS) and the ones with the highest environmental damage potential, especially the contamination of water sources (LOURENZI et al., 2016). However, besides the nutrients with the highest environmental damage potential, the presence of microorganisms, especially with enteric origin, when in contact with soil and water can trigger pollution processes. In this sense, Cavalcante (2014), analyzing the presence of Escherichia coli in wells of a rural community in the Brazilian semi-arid region, observed that the presence of E. coli in the rural environment is linked to the absence of protection of human supply sources, effluent management and suggests the implementation of alternative ways of supplying these communities, which prioritize water supply with microbiological safety.

In the process of monitoring public water supply quality, Nascimento et al. (2016), in a study developed in the Piancó-Piranhas-Assú watershed in Rio Grande do Norte state, observed that in the Enterobacteriaceae family, gram-negative bacteria mainly occur and that in human wells these have an 80% predominance. Besides causing human health problems, such as gastroenteritis and cystitis, E. coli is an environmental indicator because it is restricted to warm-blooded animals (NASCIMENTO et al., 2014; CORDEIRO et al., 2016) and its presence in water sources is an indicator that fecal matter is being discharged or coming into contact with these water sources, directly or indirectly (DANTAS et al., 2010). Methodologically, E. coli is easy to determine and its use as an evaluation parameter is justified, because the use of several microorganisms as indicators is hard going and costly for water supply monitoring services (SILVA et al., 2015).

In this sense, it is necessary the environmental monitoring in the areas with intense swine activity, being able to observe possible scenarios of contamination caused by enteric microorganisms, as well as alteration of water characteristics that may makes them improper for human consumption (CUCIO & PORTO, 2015). Thereby, the aim of this study was to evaluate pH values and the presence of Escherichia coli in water sources in a region with intense swine activity in Santa Catarina state.

2 Material e methods

       This study was carried out in the Rio Coruja/Bonito watershed, which has about 52 km² and is located in the Tubarão River watershed, Southeastern region of Santa Catarina state. Geographically the watershed is located in the southeastern region of the municipality of Braço do Norte, mainly in the locality of Pinheiral, where the river is called Coruja, being called Bonito, when it crosses the urban portion of the municipality (COUTO, 2014). The region’s climate is classified as subtropical humid, Cfa type, according to Köeppen-Geiser classification. During the study period, the precipitation and temperature mean values were obtained from the meteorological data online from the Meteorological Station of the National Institute of Meteorology (INMET), located in the municipality of Urussanga, totalizing 1.512 mm of precipitation and 15,7ºC of mean temperature.

The study was carried out from July 2015 to June 2016, with the first sampling taking place on July 20^th 2015 (Jul/15), the second on October 20^th 2015 (Out/15), third on December 05^th 2015 (Dez/15), fourth on March 21^th 2016 (Mar/16) and the fifth sampling on May 20^th 2016 (Jun/16). In the watershed under study, four rural properties within Rio Coruja watershed were selected, being three with swine activity and intense use of manure in the production areas and one that uses swine and cattle manure in the areas of production. Also, three points of samplings were selected in the Coruja River. These point were identified according to its type (supply wells = SW, fountainhead = F, weir = W, river = R), property number (1, 2, 3, and 4) or river (1, 2 and 3), being identified as follows: property 1: F1.1, F1.2, SW1.1 e SW1.2; property 2: F2, SW2, W2; property 3: F3, W3 e SW3; property 4: W4 e SW; river: R1, R2 e R3. The geographical coordinates of the points are shown in table 1.

Water samples were collected in human wells, in the lentic and lotic waters. In each point, approximately 300 mL of water were collected and store in a pre-cleaned (HNO₃^- 10%) “snap cap” bottle. The samples were sent to the Laboratório de Análise de Solo, Água e Tecidos Vegetais of the Departamento de Engenharia Rural of the Universidade Federal de Santa Catarina. During sampling, samples pH values were determined using the conductivity meter YSI Model 85. In the laboratory, the Most Probable Number (MPN 100 mL^-1) of total and thermotolerant coliforms were evaluated according to Standard Methods (1995) methodology, being the thermotolerant represented by the bacterium Escherichia coli. For the data obtained, the CONAMA Resolution nº357/2005 was applied to evaluated the quality of water. For this, the pH values are presented from the field reading and the Escherichia coli values from the most probable number (MPN).

Table 1 - Geographical coordinates in the points of study of Coruja/Bonito River watershed

Points of study	Altitude	Geographical coordinates
SW1.1	381 m	28º13’977” S 49º06’254” O
SW1.2	383 m	28º13’992” S 49º06’201” O
SW2	405 m	28º11’786” S 49º04’770” O
SW3	399 m	28º11’818” S 49º05’492” O
SW4	388 m	28º12’483” S 49º05’204” O
F1.1	383 m	28º13’942” S 49º06’245” O
F1.2	382 m	28º14’011” S 49º06’246” O
F2	403 m	28º11’807” S 49º04’639” O
F3	399 m	28º11’818” S 49º05’498” O
F4	393 m	28º12’587” S 49º05’287” O
W2	410 m	28º11’888” S 49º04’612” O
W3	396 m	28º11’806” S 49º05’472” O
R1	389 m	28º12’461” S 49º05’170” O
R2	375 m	28º13’528” S 49º05’946” O
R3	277 m	28º15’372” S 49º05’562” O

According to CONAMA Resolution nº357/2005, pH values range from 6.00 to 9.00 for all water classes, all water bodies without classification, comprehended in Class 2 waters. For microbiological parameters thermotolerant coliforms, Class 1 waters accepts MPN not exceeding 200 coliforms in 100 mL per sample or absence in 80% of the samples, being at least six evaluations in the period of one year. For Class 2 waters, thermotolerant coliforms must not exceed 1000 coliforms in 100 mL or absence in 80% or more samples in an annual period, bimonthly sampling/evaluation frequency. In Class 3 waters, it is limited to 2500 thermotolerant coliforms or in 80% or more of at least 6 samples, sampling bimonthly, including watering operations of confined animals not exceeding the limit of 1000 coliforms in 100 mL per sample.

3 Results and discussion

The water sources points pH values ranged from 4,05 to 8,76 (Figure 1). To supply wells (SW), pH values ranged from 4,05 to 6,85; to the weirs (W) ranged from 5,64 to 8,76; to the fountainheads (F) ranged from 5,20 to 6,64; and to Coruja River sampling points (R), ranged from 5,32 to 6,68 (Figure 1). As established by CONAMA Resolution nº357/2005, pH values should range from 6,00 to 9,00 for all water classes.

Figure 1- pH values (a, c and e) and MPN of Escherichia coli (b, d and f) in the points of study of Coruja/Bonito River watershed, during a period of one year. SW= supply wells (a and b), F= fountainhead (c and d), W= weir and R= river (e and f)

For supply wells, in general, pH values were below the minimum limit established (Figure 1a). This can be justified by the shallow depth of the wells under study that may be receiving, by percolation processes, soil contaminant compounds or through communicating vessels processes within water table, that can increase H⁺ ions in water, affecting pH values and its characteristics. For the weirs under study, pH values from Jun/16 sampling were below the established standard, occurring variation between the points under study and the other samplings, being observed a decrease in the values from the Dez/15 sampling (Figure 1c). This behavior was also observed by Zucco et al. (2015), when evaluating physic-chemical parameters in floodwaters, observed that the rainfall indexes and the hydrographs increases were correlated to the pH values increase, due to the greater contribution of particulate material that occurred during this period. For the Coruja/Bonito River watershed study points (R), Jun/16 sampling showed the lowest pH values and rainfall indexes. To the other samplings occurred a greater pH values variation in the points under study, due to the more frequent rainfall indexes when compared to Jun/16 sampling.

Variations in the fountainheads and Coruja River sites are justified by anthropic pressure, through animal and human effluent discharge, as well as, by river bank erosion and silting up natural processes (Figure 1e). This process was also observed by Moura et al. (2010), on evaluating Córrego Gama watershed tributaries and its affluent Córrego do Cedro, in the municipality of Brasilia, in 2003-2005 period, observed that in the five of the sites under study, three sites had pH values below of the minimum limit, in which case there was greater anthropic pressure at the river banks through fresh human effluent discharges.

The presence of Escherichia coli (Figure 1b, 1d, 1f) was observed for all sites under study in the Coruja/Bonito watershed. CONAMA Resolution nº357/2005 limits to 1000 thermotolerant coliforms in 100 mL of water for Class 2 waters. It is observed that the values of thermotolerant coliforms were equal to the total ones, showing that the coliforms present in the water samples has an enteric origin.

In this sense, for the Coruja River sites, especially R3 site, the presented values were always above the allowed limit by CONOMA in all evaluations that were carried out, where these corroborates with the values founded by Terra et al. (2010). These authors when evaluating water supply quality from metropolitan region of the municipality of Vitoria/ES, observed that one of site under study stood out from the others, indicating that organic load at this site was high, seriously compromising water quality. For rivers that serves as public supply, it is of relevance the observation and monitoring of coliforms values, due to the presence of potential gastroenteritis originators, being able to cause endemic outbreaks in the population supplied.

For Coruja River sites under study, similar results were observed by Hadlich (2004). These authors observed that the farther from the rives fountainhead, the greater the degradation of the water course due to anthropic activity. Thus, Coruja River presents a high degradation due to the presence of pig slaughterhouses on the river banks, as well as the discharge of domestic effluent and swine and cattle manure surface runoff from the adjacent agricultural areas. The lowest values were observed in the supply wells sites, especially those used for human supply, indicating that the water intended for human consumption presents good microbiological quality. These values corroborate with those observed by Cavalcante (2014). These authors when evaluating supply wells microbiological quality in rural areas, observed that even the MPN of thermotolerant coliforms being within the established limits by a large number of legislations, especially for CONAMA Resolution No. 357/2005, the presence of E. coli in human supply wells indicates that it is necessary some actions to prevent effluents arrival, as well as basic sanitation actions or alternatives to supply, so that the population are not directly exposed to gastroenteritis.

For the weirs under study, it is observed a greater contamination in the F2 site, which can be explained by the position in the landscape lower portion within the studied property, where at this point the supply of drained water from the agricultural and animal management areas contributes to its pollution. In the other weirs, like the fountainheads under study, a greater presence of riparian forests can assist in the decrease of MPN coliforms, as a result as nutrient absorption through plants root system, besides that the coliforms need organic carbon for its survival outside the gastrointestinal system.

Currently the water bodies under study are classified as Class 2 waters by CONAMA Resolution nº357/2005. However, as pH values for all classes must be in the range between 6,0 and 9,0 all the sampling points under study must undergo some intervention to increase waters pH values, mainly those associated to the management of swine manure in adjacent areas. In relation to E. Coli parameter, the supply wells are generally within the established limit with the soil located above the wells, acting as a filtering membrane. In this way, the waters used for human and animal supply are suitable for consumption after conventional treatment. Fountainhead, weirs and Coruja River were classified as Class 3 waters, because it is allowed up to 2500 coliforms per sample, and the water can be used for human consumption after conventional treatment, or advanced treatment for irrigation, amateur fishing, the recreation of secondary contact and the watering of animals. It is important to emphasize that the constant application of animal manure in agricultural areas has caused, by processes of runoff and percolation, the decrease of pH values and the constant presence of coliforms in the water, being able to cause problems of public health to the population supplied by this water.

4 Conclusion

In general, pH values showed a change in the water quality and its organoleptic characteristics and for the presence of Escherichia coli, even though they are within the limits established by the legislation, indicates the danger of endemic processes that may occur through the ingestion of coliforms, and these two parameters indicates that pig slurry has caused environmental pollution.

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