Spelling suggestions: "subject:"water - contamination"" "subject:"water - decontamination""
31 |
AVALIAÇÃO DAS CONDIÇÕES HIGIÊNICO-SANITÁRIAS DA ÁGUA DAS PRAIAS DO MUNICÍPIO DE SÃO LUÍS-MA / EVALUATION OF TOILET-HEALTH CONDITIONS OF WATER FROM THE BEACHES OF São Luís -MA MUNICIPALITYSilva, Viviane Correa da 29 September 2006 (has links)
Made available in DSpace on 2016-08-19T17:47:08Z (GMT). No. of bitstreams: 1
Viviane Correia da Silva.pdf: 3103371 bytes, checksum: 346e99d0ade7b1dc870b9385ad0b002f (MD5)
Previous issue date: 2006-09-29 / The aim of this work was to evaluate the hygienic and sanitary conditions of the beaches of the São Luís municipality, using as an indicator the Enterococcus. Two distinct periods were studied: rainy and drought seasons. The samplings were performed fortnightly during
the rainy season and weekly at dry season. The pH was measured at the point of the water sampling area and the laboratorial microbiologic analyses were performed by using the method of multiple tubes, as preconized by the American Public Health Association APHA (1995). The pH was found at the normal standard level, between 7 and 8, for the all
examined beaches. High counts of Enterococcus, between 102 and 103 MPN/100 mL, were found to the drought season, and reaching 105 MPN/100 mL in the rainy season. It was
concluded that the beaches of the Ponta da Areia and Calhau were characterized as improper for swimming at the examined periods, while the Olho d Água and Araçagi beaches were suitable. / O objetivo deste estudo foi avaliar as condições higiênico-sanitárias das praias do município de São Luís, utilizando como indicador os Enterococcus. Avaliou-se dois períodos distintos, estação chuvosa e seca. A amostragem foi realizada quinzenalmente na estação chuvosa e semanalmente na estação seca. Aferiu-se o pH no local da coleta e no laboratório realizou-se análise microbiológica através do método dos tubos múltiplos,
conforme preconiza a American Public Health Association - APHA (1995). O pH mostrou-se dentro do padrão, com índices entre 7 e 8, em todas as praias. Constataram-se altos índices de Enterococcus, da ordem de 102 a 103 NMP/100 mL no período seco, chegando a 105 no período chuvoso. Conclui-se que as praias Ponta da Areia e do Calhau caracterizaram-se impróprias para banho no período avaliado, enquanto as praias Olho
d Água e Araçagi enquadraram-se como próprias.
|
32 |
Faecal source tracking and water quality in the Eastern Cape, South AfricaLuyt, Catherine Diane January 2013 (has links)
Water quality is concerning as many still lack access to safe drinking water. Alternate sources such as rivers (FC up to 1600 CFUs/100 mL) and rainwater are often polluted. Rainwater tanks require maintenance to improve water quality, but could be used for non-potable purposes or irrigation. Grahamstown infrastructural failures initiate deviations from DWAF 1996 domestic water guidelines for microorganisms within the distribution system. Frequent testing can decrease risks of waterborne diseases. Limitations to this are inaccessibility of rural areas, distances from testing centres and costs. The low cost H2S strip test able to be used onsite by communities, may aid in risk assessment. H2S strip test results are not affected by sulphate (14 to 4240 mg/L) or nitrite (up to 47 mg/L). Transportation of the H2S strip tests between 10 and 32°C does not modify results significantly. Similarly to other studies: Klebsiella spp.; Enterobacter spp. and Serratia spp. were isolated from H2S strip tests. The mH2S strip test corresponds best with HPC in treated water, while in untreated river water it has approximately 90% correspondence with FCs, while survival of FC causes discrepancies with the H2S test after 22 days. A faecal coliform inactivation rate of 0.1 CFUs/ day, may be longer than many pathogens. Faecal source tracking, not currently practised in South Africa, could aid health risk assessments for disaster management, which would improve the NMMP programme. Bacterial survival times could propose the time period for which water is unsafe. Bifidobacteria and Rhodococcus are proposed to help identify the faecal pollution source. But enumeration of Rhodococcus is too lengthy (21 days). The tracking ratio of bifidobacteria (between 0.1 to 6.25) is not source definitive. The bifidobacteria survival rate, could indicator the time since faecal pollution. The bifidobacteria average survival rate is 2.3 CFUs per day for both groups. The culturability and selectivity of agar is still poor, with total bifidobacteria less selectively culturable. Enterococci overgrowth of TB was decreased by Beerens media. SUB is still useful to identify potential human faecal inputs. A single tracking method is thus not suitable alone, but requires a combination of techniques.
|
33 |
FRAGILIDADES AMBIENTAIS APLICADAS À GESTÃO DA QUALIDADE DAS ÁGUAS: ESTUDO DE CASO DA BACIA DO RIO SANTA MARIA, RS. / ENVIRONMENTAL FRAGILITY APPLIED TO WATER QUALITY MANAGEMENT: CASE STUDY OF RIVER BASIN SANTA MARIA, RS.Tamiosso, Camila Ferreira 25 August 2011 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The rapid growth of urban centers and the increase in deforested areas and agricultural
activities, coupled with a lack of proper management of water resources has generated large
amounts of waste carried to water bodies, usually beyond their capacity of assimilation. So, to
assist the efforts of monitoring, control, supervision and development of territorial planning
for environmental management body, one of the main tools used is the map of environmental
fragility. However, it is necessary to assess how much uncertainty is implicit in applying this
type of method. In this context, the objective of this study is to analyze the consistency of the
methodological approach applied in the project FRAG-RIO, related for the contamination of
water for the basin under study. For this, was compared the hierarchy of river reaches in a
map of environmental fragilities of water contamination, with the hierarchy of river reaches
based on the sampling stations for water quality of FEPAM/RS. The study area is the river
basin Santa Maria, located on the southwestern border of Rio Grande do Sul, a predominantly
rural watershed, characterized by extensive livestock and rice fields. For the development of
methodology, in the stations of quality of FEPAM/RS were obtained observed data for
concentration of the following parameters: fecal coliform, BOD, COD, ortho phosphate, total
phosphorus, manganese, total Kjeldahl nitrogen and total solids. These data were transformed
into loads, and then ranked. To construct the map of fragilities were considered three
variables: the population organic load remaining, organic load of breeding and agriculture
index. The final map of fragilities varies from 0 to 255, where smaller values indicate low
fragility, while higher values represent the greatest fragility. The fragilities were analyzed in
relation to the quality stations of FEPAM/RS in two ways: considering all contributing
drainage area to the station, and considering only the incremental area of the station. The
results of these tests were ranked and compared with the ranking of each parameter of quality
stations. For this, the correlation between the hierarchies was analyzed using the Spearman
test. The main result, it was observed that the analysis of environmental fragility relating to
the aspect of water contamination is presented as a useful tool to support decision making in
basins with a lack of data, particularly when considering the quality parameters of BOD and
nitrogen. These parameters had the highest correlations with the hierarchy generated by the
sum of the fragilities of all contributing drainage area to the quality station , with a
determination coefficient of 59%. / O crescimento acelerado dos centros urbanos e o aumento de áreas desmatadas e
atividades agropecuárias, aliados a falta de um gerenciamento adequado dos recursos hídricos,
tem gerado quantidades elevadas de efluentes carreados para os corpos hídricos, normalmente
além de sua capacidade de assimilação. Assim, para auxílio às ações de monitoramento,
controle, fiscalização e elaboração do planejamento territorial ambiental pelo órgão gestor,
uma das principais ferramentas utilizadas é o mapa de fragilidade ambiental. No entanto, é
necessário avaliar qual a quantidade de incerteza está implícita ao se aplicar este tipo de
método. Neste contexto, o objetivo deste trabalho é analisar a consistência da abordagem
metodológica aplicada no projeto FRAG-RIO, referente ao aspecto contaminação das águas,
para a bacia em estudo. Para isso, foi comparada a hierarquização de trechos de rios de um
mapa de fragilidades ambientais quanto ao aspecto contaminação das águas, com a
hierarquização de trechos de rios baseada nas estações de amostragem de qualidade da água
da FEPAM/RS. A área de estudo corresponde à bacia hidrográfica do rio Santa Maria, situada
na fronteira sudoeste do Rio Grande do Sul, sendo uma bacia predominantemente rural,
caracterizada pela pecuária extensiva e lavouras de arroz. Para o desenvolvimento da
metodologia, nas estações de qualidade da FEPAM/RS foram obtidos dados observados de
concentração dos seguintes parâmetros: coliformes termotolerantes, DBO, DQO, fosfato orto,
fósforo total, manganês, nitrogênio total Kjeldahl e sólidos totais. Estes dados foram
transformados em cargas, e então hierarquizados. Para a construção do mapa de fragilidades
foram consideradas três variáveis: carga orgânica remanescente das populações, carga
orgânica das criações e índice agrícola. O mapa final de fragilidades varia de 0 a 255, sendo
que valores menores significam baixa fragilidade, enquanto valores maiores representam as
maiores fragilidades. As fragilidades foram analisadas em relação às estações de qualidade da
FEPAM/RS de duas formas: considerando toda área contribuinte à estação, e considerando
apenas a área incremental à estação. Os resultados obtidos destas análises foram
hierarquizados, e comparados com a hierarquização de cada parâmetro das estações de
qualidade. Para isso, foi analisada a correlação entre as hierarquizações por meio do teste de
Spearman. Como principal resultado, observou-se que a análise de fragilidades ambientais
referente ao aspecto contaminação das águas se apresentou como uma ferramenta útil para
subsidiar à tomada de decisões em bacias com carência de dados, em especial ao analisar os
parâmetros de qualidade DBO e nitrogênio. Estes parâmetros obtiveram as maiores
correlações com a hierarquia gerada pela soma das fragilidades de toda área contribuinte à
estação de qualidade, apresentando um coeficiente de determinação de 59%.
|
34 |
The occurrence of free-living Amoebae and Amoeba resistant bacteria in drinking water of Johannesburg City, South AfricaMalaka, Maropene Patrick 13 October 2014 (has links)
M.Tech. (Biomedical Technology) / Drinking water in the greater Johannesburg area is produced by Rand Water and is transported to local Johannesburg Water where it is stored in reservoirs for distribution. At any point during the production, distribution and storage of the water, contamination with free-living amoebae, potentially containing amoeba resistant bacteria, may occur. Free-living amoebae are often resistant to the biocides used by water treatment industries and may thus be transmitted to public facilities, consumers’ homes and informal settlements through water distribution systems and during storage in small containers. The aim of our study was to analyse the water quality around Johannesburg with regard to free-living amoebae and amoeba resistant bacteria. A total of 182 tap and 5 storage tank water samples, collected from Hillbrow, Bertrams, Riverlea, Braamfischerville and Hospital Hill, were analysed for amoebae, indicator organisms, Legionellae, environmental mycobacteria, Shigella, Salmonella and Vibrio species using amoebal enrichment method. Direct microscopy indicated the presence of amoebae in 96.1% of samples. Acanthamoeba cysts were present in 69.0% of the samples. In 55.0% of these samples visibly active intracellular bacteria were observed within the sample suspensions. In the 46 samples analysed by polymerase chain reaction, the presence of Acanthamoeba species was confirmed in 65.2%, and the intracellular bacteria such as Legionella pneumophila and Mycobacterium avium was confirmed in 23.9% and 73.9% respectively. All samples indicated the presence of Shigella species while one sample contained Salmonella species on xylose lysine desoxycholate agar after amoebal enrichment processing. Vibrio species was not confirmed in the samples. Our results indicated a high risk of transmission of amoeba resistant bacteria through drinking water to people living in these areas.
|
35 |
Preparation of photocatalytic TiO₂ nanoparticles immobilized on carbon nanofibres for water purificationNyamukamba, Pardon January 2011 (has links)
Titanium dioxide nanoparticles were prepared using the sol-gel process. The effect of temperature and precursor concentration on particle size was investigated. The optimum conditions were then used to prepare carbon and nitrogen doped titanium dioxide (TiO2) nanoparticles. Doping was done to reduce band gap of the nanoparticles in order to utilize visible light in the photocatalytic degradation of organic compounds. A significant shift of the absorption edge to a longer wavelength (lower energy) from 420 nm to 456 nm and 420 nm to 428 nm was observed for the carbon doped and nitrogen doped TiO2 respectively. In this study, the prepared TiO2 photocatalyst was immobilized on carbon nanofibres to allow isolation and reuse of catalyst. The photocatalytic activity of the catalyst was tested using methyl orange as a model pollutant and was based on the decolourization of the dye as it was degraded. The doped TiO2 exhibited higher photocatalytic activity than the undoped TiO2. The materials prepared were characterized by XRD, TEM, SEM, FT-IR, DSC and TGA while the doped TiO2 was characterized by XPS, ESR and Raman Spectroscopy.
|
36 |
Groundwater pollution threats of solid waste disposal in urban Kano, Nigeria : evaluation and protection strategiesAli, Ahmed January 2013 (has links)
The practices of solid waste management (SWM) and solid waste disposal (SWD) in Kano metropolis, Nigeria, were examined. The water quality of groundwater sources in the areas adjacent to the SWD sites was monitored in order to evaluate interactions and assess the possibility of groundwater contamination as a result of percolation of the leachates generated in the SWD sites. An integrated approach to the field investigation was employed in the study. This included an extensive desk study; a field survey of all existing SWD sites in the area; leachate and groundwater sampling; and laboratory-based experimental and instrumental analyses. The locations of the SWD sites relative to inhabited areas were examined, and eight sites and their environs were selected for leachate and groundwater sampling and quality assessments in May 2009 and May 2010. It was observed that SWM activities in Kano metropolis are unsystematic and pose a significant risk to both public health and environmental quality, especially in relation to local groundwater sources. It was also found that the leachates produced in the sampled sites contained significant concentrations of a wide range of contaminants; including nitrates, total alkalinity, total dissolved solids, chlorides and sulphates. The leachates were also observed to be in the methanogenic phase of biochemical degradation and were shown to have similar characteristics to other leachates from mature SWD sites in different parts of the world. Similarly, the physico-chemical characteristics of the groundwater samples around the selected SWD sites indicated high concentrations of nitrates, chlorides, total dissolved solids, total alkalinity, turbidity, iron and manganese, often above the WHO thresholds for acceptable drinking water quality. It is, therefore, concluded that the shallow groundwater sources analysed have been contaminated, due largely to improper SWM practice. This, in turn, affects not only the health and well-being of the local population, but also impedes developmental efforts and obstructs prosperity. Accordingly, some strategies for pollution prevention and control were developed for Kano metropolis, although they are also applicable to other urban areas with similar characteristics. These strategies, which are largely categorised as resource-focused, source-focused or remedial measures, can be achieved through: (1) identification and mapping of pollution sources; (2) establishment of databases and information management system; (3) vulnerability mapping; (4) establishment of functional monitoring and evaluation system; (5) promotion of public awareness and participation; (6) establishment of protection zones; and (7) the integration of pollution prevention and control strategy into urban planning, development and management of municipal services.
|
37 |
Critical role of organic matter in the natural attenuation of acid mine drainageJimenez Castaneda, Martha January 2014 (has links)
The study of acid rock and mine (ARD and AMD) environments mainly focused on the mineralogical and microbiological conditions and responses of such systems. Most of the research that involved some organic viewpoint was related to the amelioration of the environmental conditions, sometimes with contradictory results. How organic matter (OM) participates and which organic fractions are involved in ARD and AMD processes remain unclear. In this work we have applied organic geochemistry tools combined with mineralogical ad molecular microbiology techniques to study of ARD and AMD environments. The main objectives were to identify and characterise the natural sources of OM occurring both at ARD and AMD sites, and to determine whether the OM sources identified are involved in the generation or amelioration of AMD/ARD. This study shows that multiple OM sources occur naturally in acid drainage environments, included plant derived material and mature, petroleum-derived hydrocarbons, originating from the source rocks, apparently have not directly influence on the processes. This suggests that the generation of ARD and AMD is a completely chemoautotrophic process. Particle size of the iron phases present at ARD sites seems to be involved in the iron bioavailability. The presence of goethite in ARD/AMD systems may have a relationship with the presence of OM. Stimulation of ARD sediments using plant derived OM, abundantly present in and around ARD and AMD ponds systems does not result in the neutralisation of ARD or AMD. This suggests that plant material is not used by Fe(III)-reducing bacteria. However, it fuels fermentation processes and it is likely that fermentation products such as acetate, detected in microcosms and in situ, could limit Fe(III)-reduction. In contrast, the stimulation of ARD sediments using manure (particularly sheep manure) raises the pH up to near neutral conditions. Although it remains unclear which OM fraction from the manure is actively involved in the neutralisation of ARD; these results suggest that manure may make an interesting and non-expensive electron donor in AMD/ARD treatments.
|
38 |
Lixiviação de nitrato e amônio em colunas indeformadas de solos de uma pedossequência do estado do Paraná / Ammonium and nitrate leaching in undisturbed soil columns of a pedossequence of Paraná State (Brazil)Cristhiane Anete Neiverth 26 August 2013 (has links)
O uso intensivo do solo na agricultura associado ao consumo de fertilizantes nitrogenados tem causado a degradação acelerada dos recursos naturais e dos mananciais. A presente pesquisa teve como objetivo avaliar a lixiviação dos íons nitrato (NO3-) e amônio (NH4+) em colunas indeformadas de solo de uma pedossequência (cabeceira de drenagem), no município de Ponta Grossa, Paraná, analisando o comportamento dos solos em relação à susceptibilidade à contaminação da água pela lixiviação destes íons. Foram coletadas amostras de solo indeformadas de 0,5 m de comprimento, nas profundidades de 0 a 0,50 m e de 0,50 a 1,00 m. Nas amostras à granel foram efetuadas análises de macro e micronutrientes, da acidez atual e potencial, do teor de matéria orgânica e da granulometria nas camadas de 0-0,1 m, 0,1-0,2 m, 0,2-0,3 m, 0,3-0,5 m e 0,5-1,0 m de profundidade. Para determinação das porosidades (macro, micro e total) dos solos foram feitas coletas de amostras em anéis volumétricos nas mesmas profundidades das amostras à granel. Os solos descritos e amostrados foram os seguintes: Latossolo Bruno* Distrófico rubrico (não-hidromórfico), Cambissolo Húmico Distrófico gleissólico (semi-hidromórfico) e Gleissolo Melânico Tb Distrófico típico (hidromórfico). Nas colunas foram adicionadas quantidades de ureia e NPK equivalente a adubação recomendada para um ano e o volume de água adicionado foi equivalente a um ano de precipitação pluvial. Foram determinadas as concentrações de NO3- pelo método colorimétrico do salicilato e de NH4+ pelo sistema FIA (Análise de Injeção de Fluxo) nas amostras de água eluídas nos solos. Os resultados das análises foram submetidos à análise de variância e as médias comparadas pelo teste de Tukey ao nível de 5% de probabilidade, utilizando o programa SAS. A partir dos resultados obtidos concluiu-se que: o volume de eluição para os solos da coluna de superfície foi maior para o Gleissolo e Latossolo em relação ao Cambissolo, provavelmente devido a compactação desse último. Ao contrário do solo das colunas de superfície, a subsuperfície do Cambissolo apresentou o maior volume de eluição em relação ao Latossolo; as colunas de solo de superfície apresentaram maior lixiviação de N-NH4+ e N-NO3- no Latossolo em relação ao Cambissolo e Gleissolo. Na subsuperfície, tanto a lixiviação de N-NH4+ como a lixiviação de N-NO3- não diferenciou estatisticamente no Latossolo e Cambissolo. Para o N-NH4+ houve maior retenção no Latossolo em relação ao Cambissolo e o Gleissolo na camada 0,0-0,1 m e maior retenção no Cambissolo e o Gleissolo na camada de 0,1-0,2 m; nas demais camadas não houve diferença estatística. Com relação ao N-NO3- praticamente não houve retenção nos solos estudados; a lixiviação de nitrogênio nos três solos foi maior na forma N-NH4+ em relação a forma N-NO3- / The intensive use of soil in agriculture associated with the nitrogen fertilizers consumption has caused accelerated degradation of natural resources and water sources. This study aimed to evaluate leaching of nitrate (NO3-) and ammonium (NH4+) ions in undisturbed soils columns of a pedossequence in the county of Ponta Grossa, Paraná (Brazil) (25o09\' S, 50o16\' W) and to analyse the behavior of soils in relation to water contamination susceptibility by leaching of these ions. Undisturbed soil columns were colleted in these soils, in the depths from 0 to 0.5 m and from 0.5 to 1.0 m. In the disturbed soil samples were measured both macro and micronutriens, current and potential acidity, organic matter contend and particle size at depths of 0-0.1 m, 0.1-0.2 m, 0.2-0.3 m, 0.3-0.5 m and 0.5-1.0 m. To determine the porosity (macro, micro and total) of soil, undisturbed soil samples were colleted using Uhland extractor at the same depths of the disturbed ones. Soils described and sampled were the following: Latosol (non-hydromorphic), Cambisol (semi-hydromorphic) and Gleisol (hydromorphic). Urea and NPK equivalent to fertilization for one year and water equivalent to one year of rainfall were added into the soil columns. Concentrations of NO3- and NH4+ in eluate (water) samples and in the soils were determined by salicylate colorimetric method and FIA system (Flow Injection Analysis), respectively. The results were subjected to variance analysis and means compared by Tukey test at 5% probability, using the SAS program. From this experiment it a could be concluded that: (i) the elution water volume for surface soil columns (0.0-0.5 m) was higher for Gleisol and Latosol in relation to Cambisol, probably due to compaction of Cambisol and, in contrast, for subsurface soil columns (0.5-1.0 m), the elution water volume was higher in Cambisol than Latosol; (ii) in surface soil columns, N-NH4+ and N-N0-3 lixiviations were higher in Latosol in relation to Cambisol and Gleisol and, in subsurface soil columns, both N-NH4+ and N-N0-3 lixiviations were not significantly different in Latosol and Cambisol; (iii) there was higher N-NH4+ retention in Latosol in relation to Cambisol and Gleisol only in 0.0-0.1 m soil layer and a higher N-NH4+ retention in Cambisol and Gleisol in relation to Latosol only in 0.1-0.2 m soil layer, whereas with respect to N-N03-, there was no retention in any soil layers in studied soils; (iv) nitorogen lixiviation in the three soils was higher as N-NH4+ than N-N0-3.
|
39 |
Färdigbehandlade deponier : Ska miljöövervakningen fortlöpa? / Closed landfilling sites : Shall the environmental monitoring be proceeded?Persson, Hilda January 2021 (has links)
Waste management is an important key to protect the environment and human health. Landfilling is the oldest form of disposal of waste and due to that Sweden has about 2000 closed landfilling sites. Closed landfilling sites might have negative impact on the environment and must therefore be monitored to reduce the risk of pollution. A way to monitor a closed landfill site is to analyze the surrounding waters and ground waters to see if the leaches might affect them. This study aims to determinate when a closed landfilling site might be considered safe enough to stop monitoring. The landfilling site at Ersmarksberget has been used as an example. A screening has been performed in the ground water and analyses from 2007-2020 have been used to determinate how or if the landfilling site affects the surrounding waters. Metals, persistent organic pollutants, and nutrients have been analyzed. The result of this study tells us that the landfilling site do not have a great impact on surrounding waters. Some concentrations of metals are higher in waters in the landfilling catchment area compared to a reference sites, but most of the pollutions are not above the environmental quality standards set by Swedish authorities. If the negative effects of a closed landfilling site are a bare minimum it might be time to stop the monitoring. To protect the environment and human health it is better to monitor and to remediate sites that are affecting the environment in a severe way.
|
40 |
Bio assessment of water quality using macro-invertebrate communities in the Selati River, Lower Olifants River SystemRasifudi, Lwendo January 2019 (has links)
Thesis (M. Sc. (Zoology)) -- University of Limpopo, 2019 / Many South African rivers, including the Ga-Selati River have been deteriorating for the past few decades, due to an increase in mining, industrial, agricultural and domestic activities. Around mid-January 2014, the Ga-Selati River was contaminated by mine spills from a nearby phosphate mine, which polluted the river and killed many fish species. This river is a primary source of water for many activities (e.g. mining, industrial, agricultural and domestic activities), and as a result, large numbers of reservoirs, farm dams, and inter-basin transfer schemes have been constructed to increase the reliability of water supply along this river. Contamination of surface waters by agricultural pesticides and fertilizers, as well as by industrial metals, is a cause of increasing public concern.
The Ga-Selati River is a major tributary for the Olifants River, among other tributaries (Steelpoort River and Blyde River) and it plays a significant role in the Kruger National Park and other private game reserves in the catchment. This River is also known to supply water of very low quality into the main stem of the Olifants River. The Olifants River System has been described as degraded and is contaminated with metal and chemicals, and is considered to be one of the most threatened river systems in South Africa. The aim of the study was to investigate the ecological state of the Ga-Selati River and the impact of water and sediment quality on the aquatic invertebrate communities, and to propose measures to prevent further degradation of the river ecosystem by human disturbance. The main objectives were to: (i) establish the current physico-chemical composition of the river water and sediment along the entire length of the Ga-Selati River, (ii) to determine if poor water quality at the lower end of the river is due to pollution inputs in the lower reaches, or the result of cumulative pollution inputs along the entire length of the river, (iii) Assess the impact of water and sediment quality on the aquatic macro-invertebrate assemblages in the river.
The concentrations of pH, and DO were high at all sites. If there was any sort of pollution in the river, especially downstream by the mining sites, we expected these two variables to be lower. The water variables such as EC, TDS and salinity showed a gradual increase from upstream to downstream. There were also elevated levels of certain metals, such as Mg, Na, Ti, B, Sr, K and Ca showing a pollution gradient. The
v
high concentrations of metals in water samples indicate that the Ga-Selati River is heavily impacted downstream by anthropogenic activities such as illegal dumping/littering at site 6 and mining activities at site 7 to site 9. Some of the metal concentration (Na, Mg, K and Ca) in the river were found to be extremely high compared to other rivers in the region. Metal concentrations in sediment samples were very high compared to water samples River. The nutrient concentrations at the Ga-Selati River were high but did not show a pollution gradient.
The macro-invertebrate assemblages in the Ga-Selati River were rich in Ephemeroptera, Diptera and Trichoptera. Site 1 and site 2 accounted for most of the sensitive families, reflecting good water quality at these two sites, while site 9, a downstream site recorded the highest number of tolerant families.. The variations in the macro-invertebrate distribution were shown by the differences in the water quality at the various sites by the CCA plot. The effects of main pollution factors such as, EC, TDS, turbidity and nutrients were correlated with the distribution of tolerant taxa. / National Research Foundation (NRF) and
Vlir
|
Page generated in 0.1149 seconds