Environ Monit Assess (2019) 191:77 https://doi.org/10.1007/s10661-019-7188-7 Influence of land use on trophic state indexes in northeast Brazilian river basins Olandia Ferreira Lopes & Felizardo Adenilson Rocha & Lucas Farias de Sousa & Daniela Mariano Lopes da Silva & Andrique Figueiredo Amorim & Ronaldo Lima Gomes & André Luiz Sampaio da Silva Junior & Raildo Mota de Jesus Received: 7 August 2018 /Accepted: 2 January 2019 # Springer Nature Switzerland AG 2019 Abstract Eutrophication is a natural process within the from 2008 to 2015, at thirteen (13) sampling sites, with ecological succession of aquatic ecosystems that results quarterly collections. The results showed that, among from nutrient inputs to water bodies, especially limiting three basins analyzed, Cachoeira River basin presented elements such as phosphorus and nitrogen. However, the worst values for trophic state index (TSI) due to the the anthropogenic activities in river basin influence high level of anthropization, while best results were areas accelerate the eutrophication process of water found in Una basin. It was verified that land use exerted bodies. Eutrophication is a global problem and consid- a significant influence on the water quality of bodies of ered one of the most relevant reasons of aquatic envi- water evaluated. ronments’ degradation. In this context, watercourses that make up the Eastern Water Planning and Manage- Keywords Eutrophication . Degradation . ment Region (RPGA) receive high pollutant contribu- Anthropogenic action . Effluents tions due to release of wastewater and agriculture diffuse sources from cities located in influence area. The present study aims to evaluate the land use effect in trophic state Introduction of the water bodies in Eastern RPGA basins. The Carlson Trophic State Index in 1977, adjusted by Eutrophication is a natural process of succession in Lamparelli 2004, was used to determine the eutrophica- bodies of water. This phenomenon occurs due to the tion degree of the three river basins (Almada, Cachoeira, entry of nutrients especially the most limiting ones such and Una) located in the Eastern RPGA. The nutrient and as phosphorus (P) and nitrogen (N) into aquatic envi- chlorophyll a data were obtained from the Monitoring ronments. However, anthropogenic actions in river ba- Program (Monitora) of Environment and Water Re- sins (agricultural practices, the launching of sanitary, sources Institute of Bahia (INEMA), covering the period agroindustrial, and industrial wastewater without O. F. Lopes : L. F. de Sousa : D. M. L. da Silva : Bahia 45201-570, Brazil R. L. Gomes : A. L. S. da Silva Junior : R. M. de Jesus (*) Universidade Estadual de Santa Cruz (UESC), Rodovia Jorge F. A. Rocha Amado, km 16, Bairro Salobrinho, Ilhéus, Bahia CEP: 45662-900, Instituto Federal de Educação, Ciência e Tecnologia da Bahia Brazil (IFBA), Av. Sérgio Vieira de Mello, 3150 - Zabelê, Vitória da e-mail: [email protected] Conquista, Bahia, Brazil O. F. Lopes : A. F. Amorim R. M. de Jesus Instituto Federal de Educação, Ciência e Tecnologia da Bahia INCT de Energia e Ambiente, Universidade Federal da Bahia, (IFBA), John Kennedy, s/n - Loteamento Cidade Nova, Jequié, Salvador, Bahia 40170-280, Brazil 77 Page 2 of 14 Environ Monit Assess (2019) 191:77 previous treatment) accelerate this process. These activ- determine TSI adapted by Lamparelli (2004) are total ities cause the introduction of excessive amounts of phosphorus and chlorophyll a, considering that the these nutrients to the watercourse (Lundberg 2013; values of transparency generally do not represent the Vieira et al. 2013). According to Meng et al. (2015), trophic degree of the river, because high concentrations phosphorus runoff causes the eutrophication phenome- of turbidity present in watercourses may interfere in its non, resulting in serious environmental problems in results (Maia et al. 2015). river basins. Increased availability of elements such as The study of water quality of the rivers in the Eastern P and N causes numerous changes in aquatic environ- Water Planning and Management Region (RPGA) is ment, such as reduction of water bodies’ biodiversity, important for the population in Southern Bahia, espe- high pH, fish mortality, anoxic conditions, and produc- cially in municipalities such as Uruçuca, Una, Itabuna, tion of toxins that can be harmful to aquatic organisms Almadina, Barro Preto, Coaraci, and Itajuípe. Conser- and human health (Whitehead et al. 2011; Ouyang vation of these watercourses is essential, as the region 2012; Privette and Smink 2017). depends on this water for drinking, agricultural irriga- Land use in the watershed area plays a relevant role tion, fishing, and supplying urban as well as rural com- in the entry of sediments and nutrients into the riverbeds munities. This RPGA presents a significant level of of water bodies (Halstead et al. 2014; Shi et al. 2017). degradation due to the predominance of industrial and According to Castilla et al. (2015), aquatic environ- sanitary effluents associated with agriculture and live- ments suffer anthropogenic pressures mainly due to stock activities dumped without pretreatment into its urban expansion and increases in agricultural crops tributaries. In some stretches of rivers, aquatic macro- productions. Deforestation, agricultural activities, and phytes, silting, and vegetation growth are present in the urbanization often modify the characteristics of the riverbed. These factors demonstrate the serious situation earth’s surface, triggering changes in the volume of of water resources’ degradation. surface runoff, changes in water temperature, increases The present study aimed to evaluate the degree of in algae production, and decreases in oxygen concentra- eutrophication of the river basins located in Eastern tion in watercourses (Ding et al. 2015; Pilgrim et al. RPGA (BA), by different methodologies, relating the 2014). In this sense, monitoring the water bodies’ qual- different scenarios of land use with possible changes in ity is required in order to understand the scenario in water quality. relation to anthropogenic influences, as well as to assist in water resources planning and management. Consid- ering that water quality monitoring encompasses many Materials and methods variables, the development of quality indexes has the objective of transforming data generated through mon- Study area itoring into information that is more accessible and more easily understandable way by people involved in the The present study was developed in the Eastern RPGA management of this resource and the populations that (Fig. 1), which consists of the basins of Bahian Rivers use these watercourses. There are numerous indexes that flow into the Atlantic Ocean, bounded from the applied to water monitoring that simplify the data sets north and northwest by the Contas River RPGA and obtained in a single or a few values. Among them, it is from the south to the southwest by the Pardo River possible to use the trophic state index (TSI), which aims RPGA (INEMA 2016). to frame water bodies in different degrees of trophy, Eastern RPGA covers an area of 9507 km2 (1.68% of pointing out strategies for recovery and conservation the state), with a population of around 682,652 inhabi- of water resources (CETESB 2015). tants. The basins of the Almada, Cachoeira, and Una The potential eutrophication of water body can be River stand out. The biome is the Atlantic Forest, with evaluated through some indexes; the most classic is Seasonal Decidual and Semidecidual Forest formations. Carlson’s(1977) TSI developed for lentic environments The soil classes identified in the Eastern RPGA are located in temperate climates, which was modified by argisols, quartzeneic neosols, chernosol, and spodosol Toledo Jr. et al. (1983) for tropical environments and (INEMA 2016; CPRM 2010). then adjusted by Lamparelli (2004) for lotic water bod- According to Koppen’s classification (1936), the ies located in tropical regions. The variables used to boundaries of the Eastern RPGA comprise two climatic Environ Monit Assess (2019) 191:77 Page 3 of 14 77 Fig. 1 Land use coverage and location of study sample points typologies. In the coastal zones of the study area, which sensors (spatial resolution of 30 m) dated February 2008 are the northeastern and southern pieces, the tropical and January 2017, orbit point 284, and they are available forest climate (Afi) predominates, characterized by rain- in the digital image catalogs of the Space Research Na- fall indexes of approximately 2200 mm. These values tional Institute (INPE) and the Geological Survey Earth are the result of maritime processes, as it is a region with Resources Observation and Science Center (USGS- significant rainfall history in all months of the year. On EROS) (Clark et al. 2017). From the total number of the other hand, the central and western zones of the spectral bands that make up the image metadata, bands RPGA under study exhibit a tropical climate with a 1, 2, 3, 4, and 5 were used to identify different vegetation defined dry season that is characterized by a decrease cover and anthropogenic systems, as observed by of precipitation in the winter months between June and Lourenço and Landim (2004). In addition, the data repre- August. The cities of this zone present annual average sented in SEI (2004) and GlobCover (2009) database rainfall values of around 850 mm, with summer as the were added to geoprocessing of information in order to season with highest intense rains (Alvares et al. 2013). superimpose