Understanding the importance of sediments to water ouality in coastal shallow lagoons

The undesirable enrichment of water by nutrients may be a problem, especially in areas with restricted exchange with the sea. The tidal regime flushes the system and contributes for the removal of phytoplankton, favouring phytobenthos as the target of enhanced nutrients. Water samples were collected during the years of 2006 and 2007-08 for nutrients, chlorophyll a and dissolved oxygen. Sediment sample s were also collected for pore water nutrients and benthic chlorophyll a. From comparison with previous work, a decrease in the nitrogen concentration in the water column can be pointed out, which may indicate an improvement of the water quality. Pore water DAIN represents approximately 75% of the total DAIN of the whole lagoon. Benthic chlorophyll a concentrations were much larger than in the water column, representing around 99% of the total chlorophyll existent in the lagoon. Benthic microalgae play a relevant role in this system and therefore standard monitoring programs of the WFD, which do not consider this component, may fail to track nutrient-driven changes in primary producers. Dissolved oxygen concentration could be near critical levels during the summer (early in the morning), especially in the inner channels.

Study of sewage sludge aimed at agricultural soil amendment by thermogravimetric analysis and fourier-transform infrared spectroscopy

Thermal degradation and gaseous products evolving from the pyrolysis of sewage sludge, aimed at agricultural soil amendment, were investigated using Thermogravimetric Analysis in conjunction with Fourier Transform Infrared Analysis (TG-FTIR). The materials were studied in temperatures ranging from 30 to 800 ºC. Furthermore infrared spectra of sewage sludge samples were performed as a complementary technique. In parallel the sewage sludge was spiked with ibuprofen in order to test whether the mentioned techniques are able to detect the drug. Thermal analysis showed the range of 200-400ºC as the most characteristic for weight loss, corresponding with the organic matter volatilization, while the range of 500-800ºC was also characteristic and due to the volatilization of carbonates. On the other hand, ibuprofen-spiking tests identified at temperature range (150-250ºC) where the compound totally volatilizes, therefore, in this work, the detection of ibuprofen by TGA was established for concentrations higher than 0.5 g/kg sludge, concentration 102 times higher than the concentrations measured by other authors in regular sewage sludge (Martín, et al., 2010). A correlation has been found between the ibuprofen concentrations in the sludge and the intensity of the absorption bands, both for FT-IR spectra at the maximum emission temperature for ibuprofen (232ºC) as for the FT-IR spectra of the non-pyrolyzed samples.

Combining sampling, profiling, remote sensing and modelling to efficiently monitoring estuarine and coastal water quality

Monitoring of coastal and estuarine water quality has been traditionally performed by sampling with subsequent laboratory analysis. This has the disadvantages of low spatial and temporal resolution and high cost. In the last decades two alternative techniques have emerged to overcome this drawback: profiling and remote sensing. Profiling using multi-parameter sensors is now in a commercial stage. It can be used, tied to a boat, to obtain a quick “picture” of the system. The spatial resolution thus increases from single points to a line coincident with the boat track. The temporal resolution however remains unchanged since campaigns and resources involved are basically the same. The need for laboratory analysis was reduced but not eliminated because parameters like nutrients, microbiology or metals are still difficult to obtain with sensors and validation measurements are still needed. In the last years the improvement in satellite resolution has enabled its use for coastal and estuarine water monitoring. Although spatial coverage and resolution of satellite images in the present is already suitable to coastal and estuarine monitoring, temporal resolution is naturally limited to satellite passages and cloud cover. With this panorama the best approach to water monitoring is to integrate and combine data from all these sources. The natural tools to perform this integration are numerical models. Models benefit from the different sources of data to obtain a better calibration. After calibration they can be used to extend spatially and temporally the methods resolution. In Algarve (South of Portugal) a monitoring effort using this approach is being undertaken. The monitoring effort comprises five different locations including coastal waters, estuaries and coastal lagoons. The objective is to establish the base line situation to evaluate the impact of Waste Water Treatment Plants design and retrofitting. The field campaigns include monthly synoptic profiling, using an YSI 6600 multi-parameter system, laboratory analysis and fixed stations. The remote sensing uses ENVISAT\MERIS Level 2 Full Resolution data. This data is combined and used with the MOHID modelling system to obtain an integrate description of the systems. The results show the limitations of each method and the ability of the modelling system to integrate the results and to produce a comprehensive picture of the system.

Spatial and temporal assessment of sediment contamination in Sado estuary: a methodological approach

For better management of estuarine ecosystems their contamination assessment should be easily communicated to local managers and decision makers. The problem is the lack of available data and the search of methodologies to enable that assessment using only few data. The Sado estuary in Portugal is as good example of a site where human pressures and ecological values collide with each other and where the degree of metal and organic contamination has not been subject to an overall assessment, either in terms of spatial or temporal variability, in a way that managers can understand.

EU water framework directive: will the nitrate load reduction from diffuse sources produce the same results in all estuaries?

The impact of urban waste-water and non-point nitrate discharges in estuarine and near-shore coastal waters are analyzed. The study is focused on the effects of applying the European directives 91/271/EEC and 91/676/EEC to these systems. 4 Portuguese estuaries and two coastal lagoons with different characteristics are studied. A modelling system is applied and calibrated in each system. Three nitrate load scenarios are examined. It is shown that the morphologic and hydrodynamic characteristics of the domain largely control the ecological processes in these systems. The primary production limitation factors are split into “biologic” and “hydrodynamic” components. The physical limitation due to hydrodynamic and residence time is the most important factor. The combined limitation of “biologic” factors (temperature, light and nutrients availability) control productivity only in the systems where physical limitation is not important.

Benthic biotope index for classifying estuarine habitats

An integration of sediment physical, chemical, biological, and toxicity data is necessary for a meaningful interpretation of the complex sediment conditions in the marine environment. Assessment of benthic community is a vital component for that interpretation, yet their evaluation is complex and requires a large expenditure of time and funds. Thus, there is a need for new tools that are less expensive and more understandable for managers. This paper presents a benthic biotope index to predict from physical and chemical variables the occurrence of macrobenthic habitats, applied to Sado Estuary, as a case of study.

Organic-walled dinoflagellate cysts in recent sediments from the Guadiana river estuary, South-East Portugal

Dissertação de Mestrado, Biologia Marinha, Faculdade de Ciências do Mar e do Ambiente, Universidade do Algarve, 2007

Application of LOICZ DPSIR framework to South asia Basins and developing typology for coastal vulnerability in South Asia

Dissertação de Mestrado, Gestão da Água e da Costa, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2007

Primary production in systems subject to natural and anthropogenic eutrophication

Tese dout., Química, Universidade do Algarve, 2005

Comparison of methods of eutrophication assessment in a coastal lagoon (Ria Formosa)

Dissertação de Mestrado, Gestão da Água e da Costa, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2010

Towards a hydrodynamic operational model of the Algarve coast and St. Vincent Cape

This study attempts to implement a hydrodynamic operational model which can ultimately be used for projecting oil spill dispersal patterns and also sewage, pollution and can also be used in wave forecasting. A two layer nested model was created using MOHID Water, which is powerful ocean modelling software. The first layer (father) is used to impose the boundary conditions for the second layer (son). This was repeated for two different wind dominant regimes, Easterly and Westerly winds respectively. A qualitative comparison was done between measured tidal data and the tidal output. Sea surface temperature was also qualitatively compared with the model’s results. The results from both simulations were analysed and compared to historical literature. The comparison was done at the surface layer, 100 metre depth and at 800m depth. In the surface layer the first simulation generated an upwelling event near Cape St. Vincent and within the Algarve. The second simulation generated a non-upwelling event within which the surface was flow reversed and the warm water mass was along the Algarve coastline and evening turning clockwise around Cape St. Vincent. At the 100 metre depth for both simulations, velocity vortexes were observed near Cape St. Vincent travelling northerly and southerly at various instances. At 800metre depth a strong oceanic flow was observed moving north westerly along the continental shelf.

Compostagem e caracterização de resíduos vegetais para utilização como substratos hortícolas

O objectivo deste trabalho foi estudar a utilização de 5 compostos de resíduos de origem vegetal, como componentes de substratos hortícolas. Estudaram-se os processos de compostagem de bagaço de azeitona, bagaço de uva, polpa de alfarroba, casca de eucalipto e casca de pinheiro, caracterizaram-se os compostos obtidos e testou-se a sua aptidão agronómica, como substratos para viveiro de tomate (Lycopersicum esculentum Mill.) em placas alveoladas e cultura de pelargónio (Pelargonium x hortorum) em vaso. Após uma preparação prévia, que em alguns dos resíduos vegetais constou de moenda, suplemento de azoto e aumento do teor de humidade, efectuou-se a sua compostagem em caixas com 1200 L de capacidade, isoladas termicamente, com arejamento por volteio manual. Depois foram analisadas as suas características físicas e químicas e testados na sua aptidão como constituintes únicos de substratos e em misturas com turfa de sphagnum. A maioria dos processos de compostagem apresentou uma evolução habitual da temperatura, com a máxima aproximando-se ou ultrapassando 60 oC. Como excepções, verificou-se um período de compostagem muito longo em bagaço de azeitona; o atraso da fase termofílica em polpa de alfarroba e, na 1ª compostagem de casca de pinheiro, a temperatura não alcançou a zona termofílica. A maioria dos resíduos manifestaram uma acentuada resistência à degradação durante a compostagem, à excepção da polpa de alfarroba e da casca de eucalipto. Contudo, a nível físico-químico e químico registaram-se evoluções acentuadas, sobretudo nas variáveis relacionadas com alterações da superfície das partículas, como por exemplo, a capacidade de troca catiónica. Outras variáveis apresentaram uma evolução interessante para o acompanhamento do processo e o conhecimento do grau de estabilidade do composto final. Foi apreciável o efeito proporcionado pela adição de lamas de estação de tratamento de águas residuais urbanas, como suplemento azotado, a nível das propriedades físicas dos compostos, do aumento da velocidade do processo de compostagem e do enriquecimento dos compostos em macro e micronutrientes. A compostagem não conduziu à melhoria significativa das propriedades físicas dos materiais, excepto em casca de eucalipto. Os compostos caracterizaram-se fundamentalmente por uma reduzida capacidade de retenção de água e uma elevada capacidade de arejamento. Os compostos obtidos com incorporação de lamas apresentaram os valores mais baixos de capacidade de arejamento, mesmo assim dentro dos limites satisfatórios e, os valores mais altos de capacidade de retenção de água. Na cultura em placas alveoladas, o comportamento de muitas das misturas com compostos não se diferenciou do da testemunha, observando-se uma flutuação sazonal do comportamento das misturas nos dois viveiros de cada ano, associada às condições ambientais mais exigentes do ponto de vista da disponibilidade de água. Observou-se um maior número de correlações significativas entre as características dos substratos e as variáveis relativas ao crescimento das plantas nos viveiros efectuados mais tarde, sob condições de maior evapotranspiração. As plantas obtidas no segundo viveiro de tomate foram instaladas em cultura. As características das plantas do viveiro, apresentaram elevada correlação com as respectivas produções obtidas no campo, evidenciando a importância da qualidade das plantas de viveiro, na produção. Nos ensaios de pelargónio em vaso, também se observaram comportamentos idênticos ao da testemunha em muitas das misturas com compostos. Observou-se no 2º ensaio, um maior número de tratamentos com resultados idênticos aos da testemunha, resultante das condições de menor exigência hídrica, as quais fizeram sobressair menos as diferenças de propriedades físicas das misturas. Contudo, a diferença de crescimento obtido em algumas misturas, atribuiu-se também à interferência da continuidade capilar entre o vaso de papel com a estaca enraizada e a mistura em estudo. O trabalho presente mostrou que é possível obter compostos a partir de resíduos orgânicos, com boas características e a preço competitivo para utilização como substratos hortícolas. O processo de compostagem sendo um elemento chave, é fácil de controlar se houver uma regulação eficaz do arejamento e do teor de humidade durante o processo. Apesar de alguns resíduos, como a polpa de alfarroba, serem caros, se tomarmos em consideração o custo da sua eliminação, poderão conduzir a substratos comercialmente viáveis. Em condições ambientais que favoreçam uma maior evapotranspiração ou, em culturas com maior exigência hídrica, pode ser aconselhável a mistura dos compostos estudados com turfa de sphagnum pouco decomposta para melhorar a capacidade de retenção de água.