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Brazilian Journal of Development
Expedition on the Lower São Francisco: An X-ray of fisheries and agriculture,
pollution, silting and saline intrusion
Expedição no Baixo São Francisco: um raio-X da pesca e agricultura,
poluição, assoreamento e intrusão salina
DOI:10.34117/bjdv6n1-221
Recebimento dos originais: 30/11/2019
Aceitação para publicação: 21/01/2020

Emerson Carlos Soares
Pós-Doutor em Ciências Aquáticas, Professor Associado III Universidade Federal de Alagoas, BR
104, km 85, Centro de Ciências Agrárias, Rio Largo, AL, CEP: 57100-000, Brasil
e-mail: soaemerson@gmail.com
Carlos Alberto Silva
Pós-Doutor em Aquicultura, Pesquisador Embrapa Tabuleiros Costeiros, Avenida Beira Mar, 3.250,
Bairro Jardins, Aracaju, SE, CEP 49025-040, Brasil
e mail: cadaloceano@gmail.com
Marcus Aurelio Soares Cruz
Doutor em Recursos Hídricos, Pesquisador Embrapa Tabuleiros Costeiros, Avenida Beira Mar,
3.250, Bairro Jardins, Aracaju, SE, CEP 49025-040, Brasil
e-mail: marcus.cruz@embrapa.br
Elton Lima Santos
Doutor em Zootecnia, Professor Associado I Universidade Federal de Alagoas, BR 104, km 85,
Centro de Ciências Agrárias, Rio Largo, AL, CEP: 57100-000, Brasil
E-mail: elton@zootecnista.com.br
Ticiano Rodrigo Oliveira
Doutorando em Ecologia, Universidade Federal de Sergipe, Av. Marechal Rondon, s/n - Jardim
Rosa Elze, São Cristóvão - SE, 49100-000, Brasil
email: ticiano.rodrigo@gmail.com
Themis de Jesus Silva
Pós-Doutora em Genética, Professor Associado I Universidade Federal de Alagoas, BR 104, km 85,
Centro de Ciências Agrárias, Rio Largo, AL, CEP: 57100-000, Brasil
e-mail: themisjdasilva@gmail.com
Evaristo Perez Rial
Doutorando en Acuicultura Instituto Español de Oceanografía - Centro Oceanográfico de Vigo,
Subida a Radio Faro, 50-52, 36390 Vigo- PO, Espanha
e-mail: evaristoperezr@hotmail.com
Rafael Navas Silva
Doutor em Agronomia, Professor Adjunto Universidade Federal de Alagoas, BR 104, km 85,
Centro de Ciências Agrárias, Rio Largo, AL, CEP: 57100-000, Brasil
e-mail: navas_rj@yahoo.com.br

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José Vieira Silva
Doutor em Agronomia, Professor Associado III Universidade Federal de Alagoas, Campus
Arapiraca, Av. Manoel Severino Barbosa - Bom Sucesso, Arapiraca - AL, 57309-005, Brasil. email: jovisi@yahoo.com.br

ABSTRACT
The São Francisco River represents 2/3 of the Northeast Region freshwater availability. Its basin is
divided into Upper São Francisco, Middle São Francisco, Sub-Middle São Francisco, and Lower São
Francisco. The Lower São Francisco is one of the most impacted regions of the Northeast, considering
factors related to fishing, electric power generation and city sewage pollution. The first Scientific
Expedition of the Lower São Francisco aimed at evaluating the water quality, pollution, silting,
deforestation of the ciliary forest, socio-economic survey, environmental education, ictiofaunal
composition, analysis of metals in fish, fishing and catching and salt intrusion. The samples were
collected in seven coastal municipalities in the states of Alagoas and Sergipe. The results indicate
that all the municipalities studied have water pollution problems from household and diffuse sewages,
pesticides, and organic matter deposited in the sediment. Much of the crops are dependent on the use
of agrochemical in crops on the banks of the river, with a prevailing environmental degradation
scenario. There was a decrease in the number of native fish species and predominance of exotic and
invasive marine species. In addition, it was possible to detect the occurrence of catch methods with
high impact on the fishes. The saline wedge is already 16 km from the river mouth, replacing
agricultural activities by shrimp farming. Fish show metal content, but a large part of them are within
acceptable limits and a georeferenced database with the results of the expedition was made available
for consultation.
Keywords: Contamination, Ecotoxicology, São Francisco river, Fishing, Agriculture, Scientific
Expedition.
RESUMO
O São Francisco representa 2/3 da disponibilidade de água doce da Região Nordeste. Sua bacia é
dividida em Alto São Francisco, Médio São Francisco, Sub-Médio São Francisco e o Baixo São
Francisco (cidade de Paulo Afonso- Bahia até a foz). O Baixo São Francisco é uma das regiões mais
impactadas do Nordeste, quando tratamos dos fatores ligados a pesca, geração de energia elétrica e
poluição oriunda dos esgotos das cidades. A 1º Expedição Científica do Baixo São Francisco, teve
por objetivo avaliar estes impactos visando uma bioprospecção de aspectos como: qualidade da água,
poluição aquática, assoreamento, desmatamento da mata ciliar, levantamento socio-econômico,
educação ambiental, composição da ictiofauna, análise de metais nos peixes, pesca e captura e
intrusão salina. Foram coletadas amostras em sete municípios ribeirinhos dos Estados de Alagoas e
Sergipe. Os resultados indicam os municípios estudados, possuem problemas de poluição aquática
decorrentes de esgotos domésticos, agrotóxicos e matéria orgânica depositada no sedimento. Boa
parte das culturas é dependente da utilização de agroquímicos, em cultivos nas margens do rio,
prevalecendo o cenário de degradação ambiental. Constatou-se diminuição do número de espécies
nativas de peixes e predominância de espécies exóticas e marinhas invasoras, ademais foi possível
detectar a ocorrência de métodos de capturas com grande impacto sobre a ictiofauna. A cunha salina
encontra-se a 16 km da foz do São Francisco, substituindo atividades agrícolas pela carcinicultura. O
pescado apresenta teores de metais, com boa parte estão dentro dos limites aceitáveis. Um banco de
dados georeferenciados com resultados da expedição foi disponibilizado para consulta.
Palavras-chave: Poluentes, Ecotoxicologia, Rio São Francisco, Pesca, Agricultura, Expedição
científica.
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1 INTRODUCTION

The Lower São Francisco is one of the most impacted regions of the Northeast because it is
located in an arid environment, where water is the main driving force of rural communities,
contributing to the supply of riverside communities, animal drinking sources, irrigation, fishing,
aquaculture, and electricity generation. However, it receives a large amount of pollution from city
sewers, as well as problems related to silting, use of pesticides in crops along the river banks,
deforestation of marginal vegetation, advance of the saline wedge, flow alterations, which impact
directly the social, economic and environmental life of the communities of this region.
The flow regime in the Lower São Francisco is governed by reservoirs located upstream of
the basin, such as the dams of Sobradinho, Itaparica, Paulo Afonso, and Xingó, whose affluence have
been reduced in recent years due to the inadequate use of land, with reduction of water production in
the basin and increased soil erosion, as well as successive periods of drought (CHESF, 2017). As a
consequence, there is a gradual reduction of the minimum flows in the river, with significant impacts,
including the advance of the saline wedge in the river mouth.
Associated with this issue, the lower purifying capacity of the river resulting from lower flows
over longer periods contributes significantly to the maintenance of pollutants at concentrations
harmful to the biota, consumption, and irrigation of crops (MEDEIROS et al., 2016). The São
Francisco river flow was drastically reduced in recent years from 1,300 m³/s in 2012 to 550 m³/s in
2017 (resolution ANA no 1,291/2017), as an immediate effect the increase of salinity was detected
at the mouth of the São Francisco.
There are several consequences of this reduction to the Lower São Francisco, because the
advance of the saline wedge on the river has brought significant impacts on ecosystems and the local
population, with probable increase of the concentration of pollutants, harmful interference in
economic activities such as fishing and rice-growing, and may make it impossible to use the waters
for human supply purposes. Possibly, the effects of the salinization are promoting changes in the local
biota, with increased competition between species, dwindling fishing stocks and the disappearance
of some species of fish and crustaceans (SOARES et al., 2011; MEDEIROS et al., 2016; BARBOSA;
SOARES, 2017; BARBOSA et al., 2018).
This scenario has worsened in recent years, and may have accelerated the excessive
exploitation of natural resources, such as the removal of riparian forest in tributary rivers and the low
level of urban sewage treatment in the municipalities of the region (CUNHA, 2015). The historical
suppression of vegetation on the banks of the river contributes to the increase of silting and erosive
soil processes, influencing the decrease of organisms (APARECIDO et al., 2016).

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Data from the early 2010s indicated the currimatã-pacu Prochilodus argenteus and the piau
Leporinus obtusidens as the most abundant species (BARBOSA; SOARES, 2009, SOARES et al.,
2011), however reports from local fishermen suggest that, since 2015, these populations have
declined, and these individuals, who together represented about 55% of the catches in the microregion
of Penedo, may not be among the five main traded species (SOARES et al., 2011; BARBOSA et al.,
2017).
In the case of other agricultural activities, there is a decrease in the productive capacity of the
economic sectors that depend on the fluctuation of water levels, by shrimp farming, using the same
nurseries previously used in rice cultivation, with small construction works of adequacy,
reinforcement of the slopes and adequacy of the water supply floodgates (BARBOSA et al., 2018).
Because of all the changes that have happened on the Lower São Francisco, a major eight-day
expedition was organized in seven data stations, in order to collect, learn, quantify, analyze, and
investigate the economic, social, and environmental conditions, levels of pollutants and pesticides,
survey of the fish fauna, limnology (physicochemical quality and the microbial in the environment),
economic and social data, deforestation and silting up of the banks, marketing of the fish, and
saltwater intrusion.

2 MATERIAL AND METHODS
The collections were carried out in the municipalities of Traipu, Porto Real do Colégio, Igreja
Nova, Penedo and Piaçabuçu, in Alagoas, and the municipalities of Propriá and Neopólis, in Sergipe,
all located in the Lower São Francisco region, making a route by waterway of approximately 140 km,
during the month of October 2018 (Figure 1).

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Figure 1. Locations travelled and collection stations of the I Expedition of the Lower São Francisco. WAT Water Quality; CLI - Climatic Variables; SED - Sediment; FIS - Fish Collection; SOC - Social Data
Collection

2.1 APPLICATION OF QUESTIONNAIRES, INTERVIEWS, AND MEETINGS
Visits were made to the secretaries of Environment and Agriculture, farmers association and
fishermen colony of each targeted municipality of the study in conjunction with EMATER-Alagoas,
where the groups and contacts were defined seeking to report the experience with agriculture, as well
as the existing problems and potentials. Later, were applied a total of about 160 questionnaires,
following the proposal of Walliman (2015), and then conducted the surveys in loco, through
photographs and visits to the banks and riparian areas.
2.2 ENVIRONMENTAL EDUCATION ACTIONS IN COMMUNITIES
Visits were carried out in the schools of the riparian municipalities/towns where there were
stops for collections of materials, information and application of questionnaires in five schools, one
in each targeted municipality by the expedition, with objective of this activity was to know the local
reality, the level of knowledge and involvement of young people with environmental problems, and
to question the students and teachers of the schools about the current state of degradation of the São
Francisco River.
2.3 SEDIMENT COLLECTION AND SOIL SAMPLES
The sediment collections and soil samples were carried out at random, and in each station
(municipality) the collection of five samples was established. These samples were collected on both
banks (Alagoas and Sergipe) and three river bed samples (channel) and sediment bank or islands
resulting from the silting. The depth of sampling, at the margins and bank of sediments or islands,
was 20 cm on average, as recommended for physical and fertility analysis of soils (FILIZOLA;
GOMES; SOUZA, 2006).
Particle size analysis was carried through the screening process in a sieve stirrer, consisting
of six distinct retention meshes (>2000 meshes; >600 meshes; >500 meshes; >425 meshes; >250
meshes and >212 meshes) and one passage mesh (< 212 meshes), the latter referring to silt + clay
fractions, and part of the fine sand fraction with particle size smaller than 212 m.
2.4 CHARACTERIZATION OF METALS IN FISH
Immediately upon capture, muscle samples from the hake were obtained on board by
removing portions of the laterodorsal region muscle amounting to about 30 g to 150 g, depending on
the size of the fish for metal analysis, and were subsequently transported, refrigerated in thermal
boxes. The fish were identified according to Lessa and Nóbrega (2000).

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All biological material was packed in plastic containers previously immersed in an acid bath
of HNO3 10% v/v for 24 hours and rinsed with Mili-Q water (18 μΩ), properly identified and stored
at temperatures below -15°C in a freezer until the time of freeze-drying.
In the digestion process, about 0.40 g of heavy lyophilized muscle was used directly in the
digestion tubes and then added 10 mL of nitric acid (HNO3) at the concentration of 7 M and 2 mL of
hydrogen peroxide 30% v/v (H2O2, Merk, Emsure®) as adapted by Jarić et al. (2011). The
quantitative determination of metals was analyzed by an inductively coupled plasma mass
spectrometer (ICP-MS, Thermo, Germany). The validation of the analytical method used the certified
reference material NIST - 1566b USA (fish tissue) based on analyte recovery values.
2.5 COLLECTION OF PHYSICO-CHEMICAL AND METAL PARAMETERS IN WATER
Sixteen points were selected for random sampling of water samples, seeking to represent the
average behavior of the river measurement sections present in each municipality as far as possible.
The samples (about 45 water samples) were collected on the surface and bottom using a Van
Dorn bottle. The water has been transferred from the on-board to a 500-mL polyethylene bottles, precleaned with a mild detergent solution, and then bath acid in HNO3 10% (v/v) for 24 hours and rinsed
with water Milli-Q (18 μΩ), properly identified, transported, cooled in cooler boxes to the laboratory
and stored at temperatures below -15 °C in a freezer until time of analysis.
The analyses of sodium (Na), copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn) cations
in water were done with Atomic Absorption Spectrophotometry (AAS). The calibration curves have
been prepared with multi-elemental SpecSol® solutions. The physical/chemical parameters pH, water
temperature, turbidity, electrical conductivity, oxide-reduction potential, dissolved solid totals, and
salinity was measured in situ by using a multiparametric probe model Aquareead AP 2000.
The evaluation of the environmental condition and multiple uses of the sampled waters was
carried out by comparing the limits established by Conama Resolution no 357 of March 17, 2005; by
the Consolidation Ordinance No 5 of 28/09/2017 of the Health Ministry on potability standards.
2.6 COLLECTION OF ICTIOFAUNAL
The fish were caught using 100 m mesh and 6 m mesh nets, both of which with 30, 40, and
50 between opposite knots, during a 6-hour work period. The fish caught have been identified, when
possible at order level, family, genus, and species and then fixed with 10% formaldehyde, and after
48 hours fixed with 70%.
2.7 GEOPROCESSING AND GENERATION OF SHIPPING DATABASE
In each of the sixteen water collection sites, the geographical coordinates were obtained with
the use of GPS and maps. It was possible to generate location maps of geospatial water collection

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points along the expedition route on the Lower São Francisco using a free-version SIG, Quantum GIS
(QGIS), version 2.18.21.

3 RESULTS AND DISCUSSION
3.1 AGRICULTURE
In the region of Porto Real do Colégio, considered a municipality, with an economy dependent
exclusively on agricultural activities (IBGE, 2019), the expedition acted in the area comprising the
irrigated District of Itiúba (area of 894 hectares) with small family farmers. The main economic
activity detected was flood rice-production.
Rice-production uses water of the São Francisco River, through irrigation channels Intensive
production requires many agricultural inputs, both to replenish nutrients from the soil and to control
unwanted pests and plants. The use of pesticides is frequent, as there is a need for the use of
fungicides, insecticides, rat poisoning, herbicides, as well as chemical fertilizers and urea.
The increase in pests, rats and birds, has forced farmers to make frequent use of pesticides,
and with the predominance of monoculture, aggravated by the high level of deforestation on the banks
of the rivers of the region, causes these animals to seek extensive rice plantations as housing and food
source, causing damage to farmers.
Another major problem is the appearance of black rice, a grass with morphology similar to
the rice produced commercially and considered an invader that reduces the quality of the final
product.
The municipality of Igreja Nova has a diversified agriculture, especially the Boacica irrigation
district, with 2,762 ha, being a major rice producer (38% of the area planted), however, bananas (59%
of the area planted) is the main product, followed by sugarcane with 3% of the production
(CODEVASF, 2019). 113 residents and farmers associated with a cooperative produce fruits,
vegetables, and greenery in an agroecological system, as well as dairy cattle breeding. The existence
of agriculture and livestock together allow the exploitation of manure for the fertilization of crops,
with the commercialization of products through the National Program of School Feeding (PNAE), in
fairs and markets of neighboring cities.
At the same time, there are cases of farmers engaged in sugarcane cultivation, favored by the
incentive and contracts with sugar-alcohol mills. However, with the crisis of the sector in the last 10
years, payments have been occurring with delays and in a discontinued way, being always paid in
subsequent years or relative to the last harvest, which has caused financial and social damage. In
addition, the cultivation system adopted is highly dependent on the use of soluble fertilizers and

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agrochemicals, favoring cultivation on the banks of the river, increasing the environmental
degradation of the region.
In the Microregion of Penedo, the municipality of Piaçabuçu near the mouth of the São
Francisco River has its economy supported by tourism, fishing activities, and services. Agriculture
has low representativeness in the economy and has faced severe problems in recent years due to the
increase in water salinity. Even though agriculture does not show any economic importance, the
activity is essential for the family economy, especially in the production of self-consumption,
contributing to the food security of families, including non-commercial fishermen.
In the municipality, the salinity level of the São Francisco River has increased significantly in
the last 10 years, making agriculture in this region difficult. Even in this scenario, there are still rice
crops adapted to this problem of the advance of the sea and the saline wedge over the waters of the
river. These adaptations include the use of small ponds, with water captured from the levels of the
“dead” tides - the period when the sea remains with fewer variations in height is that it is possible to
capture the water of the São Francisco river, reducing the uptake in the environment with higher
levels of salinity.
3.2 ICTIOFAUNAL AND FISHING
About 100 fish were collected, highlight Perciformes order (Cichlidae family: Cichla
monoculus – 14 individuals, Oreochromis niloticus-11; Carangidae family: Caranx latus- 11 and
Centropomidae family), Characiformes order (Serrasalmidae family: Serralsalmus brandtii – 11
individuals, Myleus micans – 9, Pygocentrus piraya -5; Erythrinidae family: Hoplias malabaricus-8,
Anostomidae family; Leporinus obtusidens – 4, Schizodon knerii– 3; Prochilodontidae family;
Prochilodus argenteus – 1 individual), with the Gerreidae and Eletridae families.
According to the studies carried out by Barbosa and Soares (2009) and Barbosa et. al., (2018),
the fish fauna from the São Francisco river basin is made up of 32 families, 110 genres, and 241
species, belonging to seven orders: Clupeiformes, Characiformes, Siluriformes, Gymnotiformes,
Cypriniformes, Sinbranchiformes, and Perciformes. The distribution of families, genres, and species,
in this order, detach the orders of Characiformes, with 13 families, 44 genres, and 77 species, and the
order Siluriformes, with the 10 families, 47 genres and 85 species, by the greater diversity of these
taxa, demonstrating a high capacity for dispersal and speciation in these groups. The same authors
concluded that, among the native species of the basin, several species are important as human food,
and therefore heavily fished, specially: curimatans Prochilodus spp., dourado Salminus franciscanus,
mandi-amarelo Pimelodus maculatus, mandi-açu Duopalatinus emarginatus, piaus Leporinus spp.
and Schizodon knerii, traíras Hoplias spp.

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Data from the studies of Soares et al. (2011) in the Microregion of Penedo, reported a
prevalence of 22 species in 2007, and 18 species in 2008, and 17 species in 2009, of which close to
five represent an average of 80% of the biomass of the landed fish, with the curimatã-pacu
Prochilodus argenteus, a species that is endemic to the basin, with an average percent of 40.0%,
followed by the families Anostomidae, having the piaus Leporinus and Leporinus obtusidens, with
22,0%, alternating between a representative of the family Engraulidae, the pilombeta Anchoviella sp..
When we're faced with the actual data obtained on this expedition, the decline of the native species
composition of the catches is noticeable, with 17 species collected, highlighting the collapse of the
curimatãs-pacus, pilombetas, and a decrease of the piaus, with a prevalence of fish of the order
Perciformes, to the detriment of the Characiformes, which once was the most abundant, and the
increase of the species eurihalinas, sea and the exotic compared with the native species.

As for

fishing activity in the Lower São Francisco, it employs small vessels, constructed with wood, with a
length of between three and seven meters with propulsion engines of up to 5.0 hp or sail (SOARES
et al. 2011).
The data by Porto Real do Colégio indicated that fishing activity has been alternating between
fish and crab, which represented a large volume of capture in the last few years, due mainly to the
decline in fish stocks, and as a result, the catch of the curimatã-pacu Prochilodus argenteus, a species
once most plentiful on the Lower São Francisco, and pilombeta - Anchoviella sp. (SOARES et al.,
2011), with the last capture record in 2012. The interviewees reported strong evidence of fishing with
the use of dynamite and rice dumplings soaked in formaldehyde (methods prohibited by the
legislation), and this, possibly allied to other factors, has been contributing to the decline of the
activity, proven by the disappearance of species.
According to the associates of the Igreja Nova's fishermen colony, of the 1,100 active
members, 300 had not received the Seguro-Defeso (government program to compensate periods
where fishing is prohibited) in 2018, caused in part by the difficulties of access to the Prev Web
system, belonging to the INSS, possibly by inconsistencies in the documentation.
As in studies of Soares et al. (2011), there is a strong presence of the middleman in the
marketing of fish where the price can vary from R$ 10.00/kg in the direct sale to the consumer and
R$ 5.00/kg to the middleman, called "moneychanger" in the region.
The municipality of Piaçabuçu is considered the main fishing pole in the region, due to great
catch rates of Peneideos shrimp, with records of more than 242 tons of this resource caught in 2018.
It is notable for the pluriactivity of fishing, an activity carried out in the waters of the estuary and the
coast, due to alteration of salinity and diversity of environments (saline, estuarine, and freshwater).
The data collected in the region indicate a fall in the catches of pilombeta, one of the resources that
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represented about 18% of the catches in the mesoregion of Penedo equivalent to the third-largest
catch (SOARES et al., 2011), practically disappeared from the region, and as possible causes, the low
flow of the river, increased salinity, and high levels of contaminants from the sewers of the cities may
have contributed to this decrease. As noted in the other municipalities, fishermen reported a drop-in
catches of currimatã-pacu and piaus, as well as robalos, and an increase in catches of siris Calinectes
spp., and camuripim Megalops atlanticus.
In addition, the interviewees reported certain types of fisheries that contribute to the overfishing of the leading stocks such as: beat fishing, trawl, harpoon, purse seine, or lambuda (mesh
smaller than permitted by the environmental authorities), beyond the competition with fishermen
from other regions, difficulties with the discharge of the oil from the engines of larger boats, and
protective measures for species with an increase in monitoring.
As observed by Soares et al. (2011), the perception of small-scale fishing in Lower São
Francisco is related to low fishing productivity, to the capture (incidental or non-incidental) of species
whose fishing is prohibited or controlled, and to the difficulties of monitoring and regulating the
"Seguro defeso" for non-commercial fishermen.
The record of socio-environmental conflicts in Lower São Francisco comes from relationships
with cattlemen, in the privatization of the riverbanks and their marginal lagoons. Furtado (1993) states
that "the territoriality of fishing is an area built and disputed by several other categories". The disputes
go beyond the fishing stocks since water is the abundant resource passed over. The small-scale fishing
practiced in these waters is the activity that suffers the most damage due to a series of dams that the
São Francisco River has in its length, or a change in the normal flow, which in turn generates a shift
beyond the reproductive cycle of its species of fish, resulting in a reduction of the inventory levels.
It is worth mentioning the report of a new agrarian conflict arising from the appropriation of islands
formed by sandbanks, as a consequence of the silting and low flow of the river. These new territories
are quickly habited by the cattle of local producers, and fenced, being known from then on as "islands
of so-and-so". Of course, these islands become good attractions for fish stocks, increasing fishing
points. The dispute over the territory is settled since the extractivists are not allowed to dock on these
newly acquired Islands.
3.3 ENVIRONMENTAL EDUCATION, POLLUTION, SILTING, DEFORESTATION AND
SEDIMENT
The Lower São Francisco River receives a huge load of sewage from the cities bordering the
river. All samples collected in the cities of Traipu, Porto Real do Colégio, Igreja Nova, Penedo and
Piaçabuçu, showed high rates of fecal coliforms. There is also drainage water for irrigation projects
which, for the most part, are not treated before released into the river stream. In general, all the
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municipalities bordering the Lower São Francisco have enormous financial difficulties in establishing
a local sewage treatment policy, a fact that favors the high rates of fecal coliforms found in all the
municipalities studied.
All the teachers interviewed stated that planning and development of environmental
educational activities, focused on addressing the issues, are dealt with in a cursory way, both in the
school and in the community. Evidence of this is that the majority of the students interviewed were
not aware of the impacts caused by silting, deforestation, and pollution of the environment
(anthropogenic).
There are reports about the poor performance of the environmental monitoring bodies. The
perception is that, in most cases, surveillance activities are carried out only in specific locations and
at certain periods of the year. The riverside population itself points to the need to strengthen the FPI
(Integrated Preventive Inspections) and that, if they had a permanent character.
In the path between Traipu and Penedo, it is observed that the margins, on the side of the state
of Sergipe, are better preserved than the marginal areas of the state of Alagoas, where a few isolated
remnants of ciliar forests are recorded, however, the fragments of ciliar forests on Sergipe's side are
far from complying with environmental legislation.
There are no effective actions or implementation of solutions to recover or mitigate the current
degradation of the São Francisco River. It is noticeable that there are efforts by groups of activists
and defenders of the Velho Chico, but the extent of environmental and social problems supplant the
actions taken by them.
It is possible to verify the occurrence of the intense erosive action of the water on the banks
of the São Francisco River, even with low flow, provoking cliff and drag of the ciliar forests and
sediments to the river channel. The existence of different laminar layers of deposition and
composition points to significant variations in the water regime of the river, year by year, but without
a specific date.
The incidence of sandbanks and a load of mineral and organic sediments resulting from the
process of water erosion and silting are visible throughout the covered river area, from Traipu to
Piaçabuçu, and presents a dynamic of drag and formation very variable with the flow of the river.
Although navigable throughout, the main channel of the river has severe limitations on the traffic of
large vessels where, due to the silting and reduction of the flow of the river, in many stretches, the
average depth is less than 2 m.
The deposition of sediments of variable particle size, besides reducing the average depth of
the river, promotes the emergence of new sediment outcrops above the water mirror. In terms of
composition, the new sediment banks (with up to 3 years of formation) consist of fine and medium
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sand and silt, with material much reworked by the waters, while in the older banks there is a visible
and more massive presence of silt and clays.
The sediments found in the sample collection sites, between banks, sediment bank, and bed
of the main channel, are predominantly composed of sand (medium and thin), silt and clay, with a
particle size ranging from 0.001 to 0.60 mm, and also have some aggregates supported by mud and
lytic fragments. However, in the samples of the main channel of the river, a small fraction with a
particle size above 0.6 mm (characterized as medium and thick sands) was found.
In Piaçabuçu, it is possible to see a reduction in the size of the particles of the sediment, both
in the still waters and in the islands and banks. On the other hand, in the main channel, with running
water, there is the occurrence of sediments with predominant particle size composition of medium
sand, mixed with a fraction consisting of slime and organ-clay material (mud).
3.4 METALS IN FISH
The mean concentration of arsenic was 0.44 ± 0.09 mg/kg. The mean minimum content of
0.05 ± 0.00 mg/kg was detected in the piau caught in Traipu and the higher content of 2.42 ± 0.63
mg/kg in the baiacu from Piaçabuçu. Values above the LMT of 1.0 mg/kg for arsenic (ANVISA,
2013) were found for baiacu (2.42 ± 0.63 mg/kg) and bagre (1.96 ± 0.34 mg/kg), both caught in
Piaçabuçu.
Inorganic arsenic at chronic doses can cause irritation of the stomach, intestine, lung, and skin,
as well as decrease in red and white blood cell production (DESESSO, 2001), hyperpigmentation and
diabetes (TSENG et al., 2000) and the intake of significant amounts of this element can intensify the
development of cancer, in particular, lymph, skin, lung and liver cancer (ATSDR, 2007).
With the exception of one sample of the pirambebas, caught in Traipu/AL, which had a
cadmium content of 0.01± 0.00 mg/kg, all other samples of the fish species analysed showed levels
below the detection limit of 0.023 mg/kg (ANVISA, 2013).
Anthropic contributions of cadmium to the environment can come from industrial processes
and also from the use of chemical fertilizers. The health implications of cadmium exposure are
aggravated by the relative inability of humans to excrete cadmium (DURAL et al., 2007).
The mean zinc concentration was 7.74 ± 0.94 mg/kg, and the lowest mean value of 4.54 ±
0.37 mg/kg was observed in the robalo and the highest mean value of 16.61 ± 4.39 mg/kg in baiacu.
None of the species analyzed in this study had zinc levels above the LMT of 50 mg/kg provided in
the Brazilian legislation according to Decree n° 55,871 of 03/26/1965.
Fish with an average zinc content of about 3 to 5 mg/kg is a good source for this essential
element. (OEHLENSCHLAGER, 2002). Zinc deficiency causes disorders such as diarrhea, brain

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function disorders, retardation of growth, a decline in immune defense, damage to eyes and skin,
impaired healing of wounds and other skin diseases (ROTH; KIRCHGAESSNER, 1991).
Lead has been detected in only three species; pacu and piau with a content of 0.03 ± 0.01
mg/kg and pirambeba of 0.02 ± 0.01 mg/kg. None evaluated fish species had lead concentrations
above the LMT of 0.3 mg/kg (ANVISA, 2013). Lead accumulation in organisms can cause adverse
effects such as neurological damage, kidney disease, cardiovascular and reproductive effects. The
organic form is the most toxic and absorbed by organisms, but the inorganic form is the most frequent
(GARZA et al., 2006).
The mean chromium concentration in this study was 0.37 ± 0.05 mg/kg. The lowest and
highest average levels found in the muscle tissue of the fish were 0.11 ± 0.02 mg/kg in the sole
specimen of xaréu caught in Penedo/AL and 1.25 ± 0.09 in carapebas caught in Piaçabuçu/AL. All
evaluated species had average concentrations of chromium higher than the LMT of 0.1 mg/kg
prescribed in Decree No 55,871 of 03/26/1965 for any food. Several studies indicate that chromium
(VI) compounds may increase the risk of lung cancer (ISHIKAWA et al., 1994).
The average manganese content was 0.79 ± 0.14 mg/kg, with the lowest average value of 0.44
± 0.21 mg/kg detected in the single copy of sargo caught in Piaçabuçu/AL, and the highest in the
single copy of curimatã-pacu was 1.33 ± 0.07 mg/kg caught in the Igreja Nova/AL. There are no
maximum limits in Brazilian legislation in hake prescribed for this metal. Manganese is an essential
element for humans, and Mn deficiency causes skeletal and reproductive abnormalities
(SIVAPERUMAL et al., 2007). This metal occurs naturally and can be released into water bodies
through runoff or leaching facilitated by agricultural activities, while anthropogenic sources include
pesticides.
The mean level of copper found in fish was 0.45 ± 0.09 mg/kg, and the lowest and highest
mean values were 0.30 ± 0.05 mg/kg in tucunarés fished along the RSF, and 0.62 ± 0.03 mg/kg in the
single copy of xaréu caught at Penedo/AL, respectively. All fish evaluated in this study had copper
levels below to the LMT of 30 mg/kg, laid down in Decree No 55,871 of 03/26/1965. Copper is an
essential metal for the organism and is easily regulated by metabolism, which makes bioaccumulation
very difficult (PEREIRA et al, 2010).
3.5 SALINE INTRUSION
The waters collected, both on the surface and on the bottom, from point 0 in Traipu (140 km
to the mouth) to point 13, between Penedo and Neopólis, both 30 km from the mouth, were framed
as 'fresh waters' (waters with salinity of 0.5 ‰ or less), according to Conama resolution n o 357 of 17
March 2005. The mean salinity was 0.02 ± 0.004 ‰ and minimum values of 0.02‰ and maximum
values of 0.03‰.
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The sodium levels (Na+) of surface and background water from Traipu to Penedo had an
average concentration of 3.69 ± 0.49 mg/L, minimum values of 3.20 mg/L, and maximum values of
3.50 mg/L. These values of the sodium concentration in the water are below the potability limit of
200 mg/L defined for this parameter by the Consolidation Decree No. 5 of 09/28/2017 of the Ministry
of Health, being viable for human consumption.
The average concentrations of copper (0.01 ± 0.00 mg/L), iron (0.05 ± 0.02 mg/L), manganese
(0.01 ± 0.01 mg/L), and zinc (0.01 ± 0.01 mg/L) were observed in the water collected between Traipu
and Penedo, presenting values below the limits of 2.0 mg/L, 0.3 mg/L, 0.1 mg/L, and 5.0 mg/L,
respectively, which were established by the same decree as above. According to Bassoi and Guazelli
(2004), copper values below 0.02 mg/L are common in freshwater, as well as zinc in concentrations
of 0.001 to 0.10 mg/L and manganese in the range of 0.2 mg/L, rarely exceeding 1.0 mg/L. The values
described by the authors above are in the same order of magnitude or higher than those obtained in
the fresh waters of Lower São Francisco.
In points 14 and 15 (Piaçabuçu) (16 km away from the mouth) and point 16 (large breezes/SE),
water collected in surface and background water has been classified as 'brackish water' (waters with
salinity above 0.5 ‰ and below 30‰), according to Conama resolution. The surface salinity ranged
from 2.59‰ to 4.50 ‰ and from 5.48‰ to 16.98‰ in the background waters along the São Francisco
River in the Piaçabuçu/AL-Brejo Grande/SE locality. The water sampled at the bottom showed the
highest salinity because higher levels of dissolved salts in these waters confer higher water densities,
that are distributed below surface waters of lower salinity and densities.
For the sodium content of brackish water in the Piaçabuçu locality, the lower value of 334.0
mg/L was observed in surface water and the higher content of 4,400.0 mg/L in bottom water. These
values are above the potability limit of 200 mg/L defined for this parameter by the Consolidation
Decree No 5 of 09/28/2017 of the Ministry of Health, being impractical to use them for human
consumption. About the set boundaries for the rest of the cations contained in this decree, the average
levels in the surface water and the bottom to the copper was 0.02 ± 0.00 in mg/L and 0.03 ± 0.01
mg/L; iron, 0.04 ± 0.02 mg/L and 0.05 ± 0.02 mg/L; manganese, 0.01 ± 0.01 mg/L; and zinc 0.02 ±
0,00 mg/L and 0.02 ± 0.01 mg/L, respectively, which are below the limit for human consumption.
There is a trend of higher concentrations of these cations in groundwater relative to the surface of the
Piaçabuçu station, and the same behavior has been recorded for electrical conductivity with lower
average values of 6.47 ± 2.35 dS/cm on the surface, and greater than 19.23 ± 12.31 dS/cm in-depth,
values that frame these waters in water of severe risk for use for irrigation of crops according to FAO.

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The problem of salinization of the São Francisco River in the mouth region, like Piaçabuçu,
is linked to the decrease of maximum levels (released leaks), that is, the reduction of floods that
manage to push the saline wedge back to the sea.
The data on nitrite and ammonia were greater in the collections carried out in the
municipalities of Porto Real do Colegio, Penedo, and Piaçabuçu, with average values of 0.5 ± 0.1
mg/L and 2.5 ± 0.3 mg/L, respectively. For alkalinity and stiffness, these were statistically higher in
Piaçabuçu with mean values of 2.01 ± 0.2 mg/l, 48.00 ± 1.5 mg/L, and 196.5 ± 3.7 mg/L, respectively.
3.6 DATABASE OF INFORMATION COLLECTED ON THE EXPEDITION
To facilitate access to all the information collected, results analysis, graphics, photos and
routes, it was created with the Google Maps My Maps Platform, an interactive online map that,
through layers (layers), any user can view the information that makes up the database obtained by the
expedition in a specialized way, that is, with its location in point form on the surface, and the
information detail on each point. The collection of expedition data is available in
https://goo.gl/s2LxL2.

4 CONCLUSIONS
The agriculture present frequent use of pesticides, and with the predominance of monoculture,
aggravated by the high level of deforestation. The saline intrusion extension is of 16 kilometers of
estuary. All samples of water collected in the cities showed high rates of fecal coliforms and high
levels of nitrogen, phosphorus and sulfates. Occurred the decline of the native fish species in the
composition of the catches. The heavy metals were observed in every fishes, but with levels accepted
by literature.

AKNOWLEDGE
To the team of Scientific Expedition of Lower São Francisco river. To the Commite of
Hidrographic Basin of São Francisco River (CBHSF). The Fundation of Research and Inovation of
Alagoas State (FAPEAL) and the Emater/AL - Technical Assistance and Rural Extension Company
of Alagoas.

REFERENCES

ANVISA - AGÊNCIA NACIONAL DE VIGILÂNCIA SANITÁRIA. Resolução nº 42 de 29 de ago.
2013. Dispõe sobre o regulamento técnico Mercosul sobre limites máximos de contaminantes

Braz. J. of Develop., Curitiba, v. 6, n. 1, p.3047-3064 jan. 2020.

ISSN 2525-8761

3062

Brazilian Journal of Development
inorgânicos em alimentos. Diário Oficial da República Federativa do Brasil, Brasília, DF, 2013.
Seção 1, p. 33-35.
APARECIDO, C. F. F.; VANZELA, L. S.; VAZQUEZ, G. H.; LIMA, R. C. Manejo de bacias
hidrográficas e sua influência sobre os recursos hídricos. Irriga, v. 21, n. 2, p. 239-256, 2016.
ATSDR. Agency for Toxic Substances and Disease Registry. Toxicological profile for arsenic.
Atlanta, 2007. 500 p. Disponível em: <https://www.atsdr.cdc.gov/ toxprofiles/tp2.pdf>. Acesso em:
11/02/2019.
BARBOSA, J. M.; SOARES, E. C. Perfil da ictiofauna da Bacia do São Francisco: Estudo preliminar.
Rev. Bras. Eng. Pesca, 4 (1), 155-172, 2009.
BARBOSA, J. M.; SOARES, E. C.; CINTRA, I. H. A.; HERMANN, M.; ARAÚJO, A. R. R. Perfil da
ictiofauna da bacia do rio São Francisco. ActaFish, 5 (1), 70-90, 2017.
BARBOSA, J.M.; NUNES-FILHO, A.; FERREIRA, A.F.; SILVA, A.A.; SOARES, E.C. Evolução da
atividade agrossilvipastoril na região e Brejo Grande, Estado de Sergipe: Carcinicultura.
Agroflorestalis News, v. 3, n.1, 52-60, 2018.
BASSOI, L. J.; GUAZELLI, M. R. Controle Ambiental da Água. In: PHILIPPI, JR. A.; ROMÉRIO,
M. A.; BRUNA, G. C. Curso de Gestão Ambiental. Universidade de São Paulo. p. 53-99, 2004.
CHESF. Redução temporária da vazão mínima do Rio São Francisco para 550 m³/s, a partir da UHE
Sobradinho. 45o Relatório Mensal de Acompanhamento. Companhia Hidrelétrica do São
Francisco. Dezembro. 2017.
CODEVASF - Companhia de Desenvolvimento dos Vales do São Francisco e Parnaíba. Áreas de
Irrigação. Disponível em:<https://www.codevasf.gov.br/principal/perimetros-irrigados/elenco-deprojetos/boacica>. Acesso em: 04/02/2019.
CUNHA, C.J. Regularização da vazão e sustentabilidade de agroecossistemas no estuário do Rio São
Francisco. Tese de Doutorado. Programa de Pós-Graduação em Geografia do Centro de Ciências e
Tecnologia. Universidade Estadual do Ceará. 2015. 231 p.
DESESSO, J. M. Teratogen updade: inorganic arsenic. Teratology, v. 64, n. 3, p. 170-173, 2001.
DURAL, M.; GOKSU, M. Z. L.; ÖZAK, A. A. Investigation of heavy metal levels in economically
important fish species captured from the Tuzla lagoon. Food Chemistry, n. 102, p. 415-421, 2007.
FAO - Food and Agriculture Organization of the United Nations. The stat of world of fisheries and
aquaculture. Rome. 2016.
FILIZOLA, H.F.; GOMES, M.A.F.; SOUZA, M.D. Manual de procedimentos de coleta de
amostras em áreas agrícolas para análise da qualidade ambiental: solo, água e sedimentos.
Jaguariúna: Embrapa Meio Ambiente, 2006. 169p.

Braz. J. of Develop., Curitiba, v. 6, n. 1, p.3047-3064 jan. 2020.

ISSN 2525-8761

3063

Brazilian Journal of Development
FURTADO, L. G. Reservas pesqueiras: uma alternativa de subsistência e de preservação ambiental.
In: FURTADO, L.; MELLO, A. F.; LEITÃO, W. Povos das Águas realidade e perspectiva na
Amazônia. Belém, MPEG/UFPA. p. 243-276, 1993.
GARZA, A.; VEGA, R.; SOTO, E. Cellular mechanisms of lead neurotoxicity. Medical Science
Monitor, v. 12, n.3, p. 57-65, 2006.
GOOGLE, INC. Google Maps. Disponível em: <https://www.google.com.br/maps/>. Acesso em:
dezembro de 2018.
IBGE - Instituto Brasileiro de Geografia e Estatística. https://cidades.ibge.gov.br/. Acessado em
30/11/2018 e 04/02/2019.
ISHIKAWA, Y.; NAGAKAWA, K.; SATOH, Y.; KITAGAWA, T.; SUGANO, H.; HIRANO, T.;
TSUCHIYA, E. Characteristics of chromate workers’ cancers, chromium lung deposition and
precancerous bronchial lesions: an autopsy study. Br J. Cancer 70: 160-166, 1994.
LESSA, R.; NÓBREGA, M. F. Guia de identificação de peixes marinhos da Região Nordeste.
Recife:

Dimar,

2000.

Disponível

em:

<http://

http://www.mma.gov.br/estruturas/revizee/_arquivos/guiaiden.pdf>. Acesso em: 25 out. 2018.
MEDEIROS, P. R. P.; CAVALCANTE, G. H.; BRANDINI, N.; KNOPPERS, B.A. Inter-annual
variability on the water quality in the Lower São Francisco River (NE-Brazil). Acta Limnologica
Brasiliensia, vol. 28, ed.5, 2016.
OEHLENSCHLAGER, J. Identifying heavy metals in fish. In H. BREMMER, A. (Ed.). Safety and
quality issues in fish processing. Woodhead Publishing Limited and CRC Press LLC, 2002. p. 95113.
PEREIRA, P.; PABLO, H.; PACHECO, M. Vale The relevance of temporal and organ specific
factors on metals accumulation and biochemical effects in feral fish (Liza aurata) under a moderate
contamination scenario. Ecotoxicology and Environmental Safety, 73: 805-816, 2010.
QGIS Development Team. QGIS User Guide, Release 2.18: QGIS Project, 2016.
ROTH, H. & KIRCHGAESSNER, M. Z. Biochemie, physiologie, pathophysiology undklinik des
stoffwechsels des menschen. In: Roth, H.; Kirchgaessner H. J. M.; Holtmeier, J. Kruse-Jarres (Ed.).
Stuttgart: Wissenschaftliche Verlagsgesellschaft mbH, 1991. p. 67–101.
SIVAPERUMAL, P., SANKAR, T.V., NAIR P.G.V. Heavy metal concentrations in fish, shellfish
and fish products from internal markets of India vis-à-vis international standards. Food Chemistry,
102, 612-620, 2007.
SOARES, E. C. et al. Ictiofauna e pesca no entorno de Penedo, Alagoas. Biotemas, v. 24, p. 61-67,
2011.

Braz. J. of Develop., Curitiba, v. 6, n. 1, p.3047-3064 jan. 2020.

ISSN 2525-8761

3064

Brazilian Journal of Development
TSENG, C. H.; TAI, T. Y.; CHONG, C. K.; TSENG, C. P.; LAI, M. S.; LIN, B. J.; CHIOU, H. Y.;
HSUEH, Y. M.; HSU, K. H.; CHEN, C. J. Long-term arsenic exposure and incidence of non-insulin
dependent diabetes mellitus: a cohort study in arseniasis-hyperendemic villages Taiwan.
Environmental Health Perspectives, v. 108, n. 9, p. 847-51, 2000.
WALLIMAN, Nicholas. Métodos de Pesquisa. 1 ed. São Paulo: Saraiva, 2015. 192 p.

Braz. J. of Develop., Curitiba, v. 6, n. 1, p.3047-3064 jan. 2020.

ISSN 2525-8761