Recebido em 15/12/08; aceito em 21/7/09; publicado na web em 25/11/09 NATURAL AND ANTHROPOGENIC EMISSIONS OF METALS AND NUTRIENTS TO THE LOWER CONTAS RIVER BASIN, BAHIA STATE, BRAZIL. Emission factors of anthropogenic activities and natural processes were used to estimate nutrients and metals loads to the Contas River lower basin, Southern Bahia, Brazil. Among natural sources, emission from soil leaching is larger for N, Cu and Pb. Atmospheric deposition is the major natural source of P, Zn, Cd and Hg. Among anthropogenic sources, agriculture is the major source of N, Cu and P. Urban sources are the major contributors to the other elements. Present anthropogenic land uses are already responsible for 78 and 99% of total N and P loads and about 50% of total Cu and Hg.Keywords: emission factors; pollutants; Rio de Contas estuary. INTRODUÇÃOOs principais nutrientes com elevado potencial de eutrofização (N e P) e metais de interesse ambiental (Zn, Cu, Cd, Pb e o Hg) são contaminantes com presença frequente e ubíqua em vários efluentes de atividades humanas incluindo industriais, urbanos e agropecuários. Além disto, são componentes naturais da deposição atmosférica, de solos, águas e biota. Dentre as fontes antrópicas, aquelas de origem urbana apresentam grande potencial de contaminação de águas superficiais por esses elementos oriundos da disposição inadequada de rejeitos sólidos urbanos (lixões), 1-3 de águas servidas (esgotamento sanitário) lançadas no meio ambiente sem tratamento prévio adequado 4 e runoff urbano, resultante da lixiviação por águas da chuva de superfícies urbanizadas.5-7 Em áreas rurais, atividades agrícolas também são importantes fontes de N, P e de alguns metais, particularmente Cd, Cu, Pb, Hg e Zn, presentes como resíduos em fertilizantes, como micronutrientes (Cu e Zn) e também como princípio ativo de biocidas (Cu). 8-12Da mesma forma a atividade pecuária também utiliza diversos insumos contendo metais, eventualmente liberados com as fezes e urina dos animais, juntamente com elevadas concentrações de P e N. [13][14][15] Portanto, mesmo em áreas de baixo desenvolvimento industrial e urbano nutrientes e alguns metais podem se constituir em ameaças potenciais à biodiversidade e à qualidade dos recursos hídricos e biológicos da região.Nutrientes e metais atingem os estuários principalmente associados ao material particulado em suspensão e/ou dissolvidos na coluna d'água dos sistemas fluviais e ainda por deposição atmosférica. As características hidrogeoquímicas das regiões estuarinas e costeiras favorecem a deposição e acumulação dessas substâncias que podem assim atingir concentrações elevadas, mesmo em áreas onde fontes pontuais significativas destes contaminantes estão ausentes.16

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Abstract:This work quantifies, using ADP and rating curve techniques, the instantaneous outflows at estuarine interfaces: higher to middle estuary and middle to lower estuary, in two medium-sized watersheds (72 000 and 66 000 km 2 of area, respectively), the Jaguaribe and Contas Rivers located in the northeastern (semi-arid) and eastern (tropical humid) Brazilian coasts, respectively. Results from ADP showed that the net water balances show the Contas River as a net water exporter, whereas the Jaguaribe River Estuary is a net water importer. At the Jaguaribe Estuary, water retention during flood tide contributes to 58% of the total volume transferred during the ebb tide from the middle to lower estuary. However, 42% of the total water volume (452 m 3 s 1 ) that entered during flood tide is retained in the middle estuary. In the Contas River, 90% of the total water is retained during the flood tide contributing to the volume transported in the ebb tide from the middle to the lower estuary. Outflows obtained with the rating curve method for the Contas and Jaguaribe Rivers were uniform through time due to river flow normalization by dams in both basins. Estimated outflows with this method are about 65% (Contas) and 95% (Jaguaribe) lower compared to outflows obtained with ADP. This suggests that the outflows obtained with the rating curve method underestimate the net water balance in both systems, particularly in the Jaguaribe River under a semi-arid climate. This underestimation is somewhat decreased due to wetter conditions in the Contas River basin.

This study aimed to point out the hydrogeochemistry groundwater in the municipality of Lençóis, State of Bahia, to classify them according to the content and types of dissolved salts. To this, twenty sampling points were listed in the groundwater in aquifers formed by metasediments, detritical covers and limestones, with the purpose of analyze the following parameters: electrical conductivity, temperature, pH, turbidity, total dissolved solids, HCO3, PO4, SO4, Cl-, NO3, Na+, K+, Ca2+, Mg2+, Fe3+, Mn4+, Sr2+ and Ba2+. The results showed that the groundwater in the municipality of Lençóis are distributed into two zones with different hydrogeochemistry, one of the largest controlled by geological clastic metasedimentary rocks typologies (sandstones, quartzites, conglomeratics, detritical covers) where the process of water-rock interaction allows occur little quantity salt water, slightly acidic, sweet, soft and predominantly sulfated sodic. The other zone is controlled by chemical metasedimentary rocks (limestones) as well as bicarbonates, where they occur hard water, slightly alkaline, sweets and sulfated calcic and mixed. The levels of metals and elements nitrate, phosphate and sulfate presented themselves generally at low concentrations, with some deviations detected in points of the urban area.

Resumo: Este trabalho teve como objetivo determinar os tipos e a qualidade das águas subterrâneas em aquíferos fissural (metassedimentar) e granular na área urbana do município de Lençóis (Bahia), região Nordeste do Brasil. Para tal, foram levantados quinze poços para amostragem de águas subterrâneas em aquíferos constituídos por rochas quatziticas do Grupo Chapada Diamantina, além de coberturas detríticas. . Os resultados apontaram que estas águas são de baixa salinidade, ácidas, doces e moles, apresentando uma boa qualidade ambiental para abastecimento e potabilidade. São águas do tipo cloretada sódica, e alguns pontos de uma zona da área urbana indicam traços de contaminação por nitrato, cloreto, sulfato e cálcio, de origem antrópica (águas residuárias). Com base nos diagramas de Gibbs, verificou-se que as águas subterrâneas na área urbana de Lençóis são do domínio da precipitação, evidenciando uma reduzida interação água-rocha. As fontes geogênicas (naturais) dos poucos íons dissolvidos nas águas podem ser atribuídas ao processo de hidrólise que ocorre entre a água e os minerais de quartzo constituintes das rochas da região.Palavras-chave: Hidrogeologia. Recursos hídricos. Chapada Diamantina. Abstract:The objective of this paper was to determine the types and quality of groundwater in fractured (metasedimentary) and granular aquifer in the urban area of the municipality of Lençóis, state of Bahia, Northeastern region of Brazil. For this, fifteen groundwater wells for sampling were analyzed in aquifers formed by quartzite rocks of the Chapada Diamantina Group, as well as, detrital cover. These parameters were analyzed: electrical conductivity, temperature, turbidity, total dissolved solids, pH, total hardness, HCO3 . The results indicated that these waters are of good environmental quality for supply and potability, furthermore, they are freshwater, acid, soft and with low salinity. They waters are NaCl, and some points in a zone of the urban area indicate traces of nitrate, chloride, sulfate and calcium contamination, of anthropic source (wastewater). Based on the Gibbs diagrams, found that the groundwater in the urban area of Lençóis is of the rainfall dominance, evidencing a reduced water-rock interaction. The geogenic sources (natural) of the few dissolved ions in the waters can be attributed to hydrolysis process that occurs between the water and the quartz minerals constituent of rocks of the region.

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