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Previous issue date: 2015-02-20 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Os efeitos delet?rios das atividades humanas ao meio ambiente s?o temas de v?rios estudos e
consequentemente de mudan?as de paradigmas. Exemplo disso, ? que at? pouco tempo
acreditava-se em um infinito poder de dilui??o dos ecossistemas em rela??o aos agentes t?xicos,
e pouco se conhecia dos efeitos dos contaminantes aos organismos. Em ?reas de intenso
crescimento urbano ? comum o descarte indiscriminado de subst?ncias t?xicas e
consequentemente o desequil?brio das din?micas naturais dos ecossistemas. Dentre estes, os
lagos s?o complexos e importantes fontes de ?gua superficial, abrigam esp?cies e t?m influ?ncia
sobre o clima da regi?o ao seu redor. A Lagoa de Extremoz/RN, litoral Nordeste do Brasil, ?
um corpo h?drico localizado numa regi?o de r?pido crescimento urbano. Est? sob influ?ncia de
atividades rurais, urbanas e industriais, al?m do regime clim?tico prop?cio a per?odos
prolongados de estiagem. O abastecimento de cerca de 300.000 pessoas depende da estabilidade
h?drica dessa lagoa. O objetivo deste trabalho foi descrever as rela??es entre par?metros f?sicos,
componentes qu?micos e as respostas observadas nos ensaios ecotoxicol?gicos, buscando
informa??es sobre as varia??es sazonais. Para isso, foram realizadas, em dois anos, 2013 e
2014, an?lises f?sicas, qu?micas e ecotoxicol?gicas da ?gua e do sedimento superficial, em duas
esta??es de amostragem na Lagoa de Extremoz (T1 e T2) e uma no rio Guajiru (T3). Nas
amostras de ?gua foram aferidos o pH, turbidez, cloreto, OD, nitrato, nitrito, fosfato reativo
total, metais e dureza. Para avaliar a toxicidade das amostras foram usados Ceriodaphnia dubia
e C. silvestrii como organismos-teste. No sedimento foram aferidos os teores de carbonato,
mat?ria org?nica e metais, caracteriza??o granulom?trica e avaliado os efeitos t?xicos sobre a
sobreviv?ncia de Hyalella azteca. Verificou-se no per?odo de estiagem, ocorr?ncia de
toxicidade aguda aos Hyalella azteca e nesse mesmo per?odo as concentra??es de metais em
?gua e sedimento tamb?m foram maiores. Em uma an?lise espacial percebeu-se que a maioria
das amostras com efeito t?xico aos organismos-teste e com maiores concentra??es de metais
foram coletadas na esta??o T2. Portanto, existem evid?ncias de que a qualidade da ?gua da
Lagoa de Extremoz esteja diminuindo gradualmente e este processo se agrava pontualmente
nos per?odos de menor pluviometria e na esta??o de amostragem T2. / The deleterious effects of human activities on the environment, are subject of several studies
and therefore paradigm shifts. Until recently thought up in an infinite power dilution of
ecosystems in relation to toxic agents, and little was known of the effects of contaminants to
organisms. The intense urban growth contributes to the increase of toxic substances and the
instability of the environment dynamics. Among these, the lakes are complex ecosystems
important for sustaining life, by stock and provide water, to have influence on microclimates
and others. The Extremoz Lake/RN, northeastern Brazil, is a water body located in a fast urban
growth area. It is under the influence of rural, urban and industrial activities, further on the
climate regime conducive to prolonged periods of drought. The supply of approximately
300.000 people depended on the hydraulic stability of this lake The aim of this study was to
describe the relationship between physical, chemical components and the responses observed
in the ecotoxicological tests, seeking information on seasonal variations. Physical, chemical
and ecotoxicological analysis of water and surface sediment were held in two years, 2013 and
2014, in two sampling stations in Extremoz Lake (T1 and T2) and in Guajiru (T3) river. In all
the water samples were measured pH, turbidity, chloride, DO, nitrate, nitrite, the total reactive
phosphate, hardness and metals. Ceriodaphnia dubia and C. silvestrii as test organisms were
used to evaluate the toxicity of the water samples. In the sediment were measured the carbonate,
organic matter, metals, particle size, and evaluated the toxic effects on the survival of Hyalella
Azteca. In dry season occurred acute toxicity to Hyalella azteca and in the same period the
concentrations of metals in water and sediment were also higher. In a spatial analysis, it was
noticed that most of the samples with toxic effects on test organisms and with the highest metal
concentrations were collected at T2. So there is evidence that the Extremoz Lake quality is
gradually declining and this process is occasionally worsens during periods of lower rainfall
and sampling station T2.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/24593 |
| Date | 20 February 2015 |
| Creators | N?brega, Thiago Farias |
| Contributors | 24043427204, Silva, Fernando Moreira da, 20610700430, Rocha, Odete, 86476947834, Souza, Raquel Franco de |
| Publisher | PROGRAMA REGIONAL DE P?S-GRADUA??O EM DESENVOLVIMENTO E MEIO AMBIENTE - PRODEMA, UFRN, Brasil |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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