Water framework directive mixing zone guidelines

The Water Framework Directive (WFD) aims to protect the aquatic environment and human health by reducing pollutants at the source. In order to achieve this, the concentration of priority substances should be lower than Environmental Quality Standards (EQS) values at the point sources. There are cases when the priority substance exceeds the EQS at the effluent discharge, however, they should be met at a distance close to the discharge point. The zones in the vicinity of discharge points where the priority substances exceed the relevant EQS values are called mixing zones. Article 4 of Directive 2008/105/EC allows member states to designate mixing zones when the pollutant concentrations exceed the EQS values at effluent discharges. But mixing zones should not affect the compliance of the rest of the water body with EQS standards. Therefore, mixing zone design should meet some defined criteria. Moreover for ensuring that design criteria are met and for facilitating the mixing zone application, member states are provided with a Mixing Zone Guideline. This project applies the Mixing Zone Guidelines at the Rönnskär Smelter located in the Northern Sweden with effluent discharges to the Baltic Sea. A second assessment of mixing zones is done in a mine area with discharge to Brubäcken stream. A “Tiered Approach” used in the guidelines is followed in assessment of mixing zones. The priority substances considered in the effluents are Hg, Cd, Ni and Pb. In the Rönnskär Smelter at Tier 2 determination of mixing zone length is done by the Discharge Test provided with Mixing Zone Guideline. CORMIX model is used for prediction of mixing in Tier 3. In the mine area the concentration of metals at the measured points showed no exceedence of EQSs, therefore there was no need for the mixing zone design. In Rönnskär, for effluents where more than one priority substance exceeded the EQS values, the mixing zones determination is done separately for each metal. Mixing zone AA-EQS criteria were met for each substance within a predefine distance of 500 m from each of the discharge points. However, much more investigation is needed related to the use of total and dissolved metals concentrations, consideration of background concentration and other input data which are site specific. Further research is also needed for mixing zone assessment where the effluent discharges contain multiple priority substances. We also concluded that climate effects, seasonal changes and other factors related to the receiving water characteristics need further investigation for a proper implementation of mixing zones for protection of aquatic and human life in Sweden

Visual Plumes mixing zone modeling software

The US Environmental Protection Agency has a history of developing plume models and providing technical assistance. The Visual Plumes model (VP) is a recent addition to the public-domain models available on the EPA Center for Exposure Assessment Modeling (CEAM) web page. The Windows-based VP adapts, modifies, and enhances the earlier DOS-based PLUMES with a new interface, models, and capabilities. VP is a public platform for mixing zone models designed to encourage the continued improvement of plume theory and models by facilitating verification and inter-model comparison. Some examples are presented to illustrate VP’s new capabilities. One demonstrates its ability, for reasonably one-dimensional estuaries, to estimate background concentrations due to tidal re-circulation of previously contaminated receiving water. This capability depends on the optional linkage to time-series input files that enables VP to simulate mixing zone and far-field parameters for long periods. Also described are the new bacterial decay models used to estimate depth changes in first-order decay rates based on environmental stressors, including solar insolation, salinity, and temperature. The nascent density phenomenon is briefly described as it is potentially important to Outer Continental Shelf (OCS) oil exploration discharges

Estudio en modelo físico de los procesos de mezcla producidos en vertidos hiperdensos y corrientes de gravedad

Programa Oficial de Doutoramento en Enxeñaría Civil . 5011V01[Resumen] Esta tesis doctoral analiza el comportamiento de las descargas de las salmueras de las plantas desaladoras en modelo físico bajo diferentes configuraciones de vertido y condicionantes ambientales como el calado, la velocidad de la corriente y el sentido de la descarga en el medio receptor. El análisis se ha realizado para las zonas más próximas al difusor (campo cercano), y para las zonas más alejadas (campo lejano). La caracterización de los procesos físicos se ha realizado con técnicas láser comunes en la hidráulica experimental: velocimetría de partículas láser (PIV) y fluorescencia inducida por láser (LIF). Además, se ha desarrollado un sistema basado en conductivímetros para estudiar la evolución en planta de los vertidos. Cabe destacar que esta última técnica de caracterización ha sido objeto de una patente de invención en la OEPM, otorgando un valor añadido al presente documento.[Resumo] Esta tese doutoral analiza o comportamento das descargas das salmoiras das plantas desaladoras en modelo físico baixo diferentes configuracións de vertido e condicións ambientais como a profundidade, a velocidade da corrente ou o sentido de descarga respecto o ambiente receptor. Estudáronse as zonas máis próximas ó difusor, campo próximo, e as zonas máis afastadas, campo distante. A caracterización dos procesos físicos realizouse con técnicas láser comúns na hidráulica experimental (velocimetría láser de partículas (PIV) e fluorescencia inducida por láser (LIF). Ademais, desenvolveuse un sistema baseado en conductivímetros para o estudo da evolución en planta dos vertidos. Cabe destacar que a última técnica de caracterización foi obxecto dunha patente de invención na OEPM, dándolle un valor engadido ó presente documento.[Abstract] This PhD Thesis analyses the brine spill behaviour from desalination plants in physical model with different spill configurations and ambient conditions such as water depth discharge, flow velocity and the jet orientation respect to the receiver ambient current. The closest area from the nozzle (near field) and the farther regions (far field) were analysed. In order to characterize the physical processes Particle Image Velocimetry (PIV) and Laser Induced Fluorescence (LIF) techniques has been applied. Furthermore, to study the brine evolution on top view a system based on conductivity probes was developed. It is noteworthy that this system was registered in Spanish Office Patent (OEPM)

Análise dos efeitos de factores climáticos e antropogénicos na Ria de Aveiro

Doutoramento em BiologiaA compreensão dos impactes das alterações climáticas é fundamental para a gestão a longo do prazo dos ecossistemas estuarinos. Esta compreensão só poderá ser efectiva considerando a variabilidade climática natural e o papel relativo das intervenções antropogénicas nestes ecossistemas. Assim, a presente dissertação analisa a influência das alterações climáticas e pressões antropogénicas na qualidade da água e dinâmica ecológica da Ria de Aveiro com base numa abordagem integrada, que combinou a análise de séries temporais dos últimos 25 anos e a modelação numérica de elevada resolução de cenários futuros de alterações climáticas e intervenções antropogénicas. A componente de modelação de qualidade da água e ecológica foi melhorada a vários níveis. A análise de sensibilidade do modelo 3D hidrodinâmicoecológico ECO-SELFE aplicado à Ria de Aveiro e a revisão das constantes de semi-saturação para absorção de nutrientes pelo fitoplâncton contribuíram para a precisão e robustez das aplicações. A concentração do fitoplâncton foi significativamente influenciada pelas taxas de crescimento do fitoplâncton e de mortalidade e excreção do zooplâncton, e apresentou uma sensibilidade reduzida à variação das constantes de semi-saturação na gama identificada para as diatomáceas. O acoplamento do ECO-SELFE a um modelo de campo próximo e a integração do ciclo do oxigénio aumentaram a sua capacidade de representação dos processos e das escalas espaciais relevantes. A validação do ECO-SELFE foi realizada com base num conjunto de campanhas específicas realizadas no canal de Mira. Os padrões espaciais e temporais observados para as várias variáveis (clorofila a, nutrientes, oxigénio dissolvido, salinidade, temperatura da água, correntes e níveis) foram simulados com erros menores ou semelhantes aos obtidos neste tipo de aplicações. A análise dos padrões de variabilidade espacial e temporal da qualidade da água e ecológica na Ria de Aveiro a diferentes escalas, efectuada com base nos dados históricos de 1985 a 2010 complementados pelas campanhas realizadas, sugeriu uma influência combinada da variabilidade climática e das acções antropogénicas. Os cenários futuros de alterações climáticas e intervenções antropogénicas simulados evidenciaram uma influência mais significativa das alterações climáticas quando comparadas com os efeitos das acções antropogénicas analisadas. As variações mais significativas são previstas para os cenários de subida do nível do mar, seguidos dos cenários de alterações dos regimes hidrológicos, evidenciando o papel da circulação (maré e caudal fluvial) no estabelecimento da qualidade da água e dinâmica ecológica na laguna. Para os cenários de subida do nível do mar são previstos decréscimos significativos da clorofila a e dos nutrientes a jusante e nas zonas intermédias do canal, e um aumento significativo da salinidade a montante. Estas alterações poderão favorecer modificações da composição e distribuição das comunidades, afectando a cadeia alimentar e causando uma progressão para montante de espécies marinhas. Os resultados sugerem ainda que os efeitos poderão ser mais significativos em estuários pouco profundos.Understanding the impacts of climate change is essential to ensure the longterm management of estuarine ecosystems. This understanding will only be reliable if the systems’ natural variability and the relative role of anthropogenic pressures are considered. Thus, this thesis evaluates the influence of climate change and anthropogenic pressures on the water quality and ecological dynamics of the Aveiro lagoon based on an integrated approach, combining the analysis of long time series from the past 25 years and high-resolution numerical modelling of future scenarios of climate change and anthropogenic interventions in the lagoon. The water quality and ecological modelling component was improved at several levels. The sensitivity analysis of the 3D hydrodynamic-ecological model ECOSELFE applied in the Aveiro lagoon and the review of the half-saturation constants for nutrients uptake by phytoplankton contributed to the precision and robustness of the applications. Phytoplankton concentration was significantly influenced by the phytoplankton growth and zooplankton mortality and excretion rates, and presented a low sensitivity to the half-saturation constants variation within the range reviewed for diatoms. ECO-SELFE’s coupling to a near field model and its extension to the oxygen cycle increased the model’s ability to represent the relevant processes and spatial scales. ECO-SELFE validation was achieved based on a set of specific field campaigns performed along the Mira channel. The spatial and temporal patterns observed for the measured variables (chlorophyll a, nutrients, dissolved oxygen, salinity, water temperature, currents and water levels) were reproduced by the model with errors smaller or similar to the ones achieved in this type of applications. The analysis of the spatial and temporal patterns of variability of the water and ecological quality in the Aveiro lagoon at different scales, based on historical data from 1985 to 2010 complemented by the campaigns performed, suggested a combined influence of the climatic variability and anthropogenic interventions. Future scenarios of climate change and anthropogenic interventions simulated revealed a larger influence of climate change when compared with the analysed anthropogenic actions. The most important variations from the reference scenario are predicted for the sea level rise scenarios, followed by the changes in the hydrological regimes scenarios, putting in evidence the main role of circulation (tide and river flow) in establishing the water quality and ecological dynamics in the lagoon. A significant decrease of chlorophyll a and nutrients is predicted in the downstream and middle areas of the channel due to sea level rise, while a significant salinity increase is predicted upstream. These changes may promote modifications in the communities’ distribution and composition, affecting the food web and promoting a progression further upstream of the marine species. Results also suggest that the identified effects may be more important in shallow estuaries

Estudio numérico-experimental de la dispersión de efluentes de emisarios submarinos en la costa valenciana

Actualmente, la problemática que enfrentan las zonas costeras del Mediterráneo en general y la Comunidad Valenciana en particular, es la generación de grandes cantidades de agua residual urbana, principalmente durante la época estival, que son vertidas a través de los emisarios submarinos al medio ambiente marino/costero. Esta carga de contaminantes es tan grande que, en ocasiones, el medio receptor es incapaz de asimilarla a corto plazo, provocando episodios de polución que afectan de forma negativa la calidad de las aguas de baño. En este trabajo, se analizaron los procesos físicos, químicos y biológicos involucrados en la dinámica de los ambientes costeros y la calidad del agua en tres zonas afectadas por el vertido de los emisarios submarinos de Pinedo, Cullera y Gandía, en la Costa Valenciana. De forma concreta, los datos registrados en diversas campañas de campo permitieron evidenciar que la introducción de agua residual en estas zonas someras, con hidrodinámica suave y diferentes condiciones de vertido, genera una serie de afecciones significativas a corto-medio plazo sobre éste ecosistema costero. Las altas concentraciones de bacterias y nutrientes en la superficie, encontradas en las estaciones cercanas al punto de vertido, demuestran que la presencia de los diferentes contaminantes, en el medio receptor, se debe a que fueron liberados a través del efluente vertido por el emisario submarino. Además, se constató que, en algunos casos, no se cumple con la normativa europea sobre calidad de las aguas de baño. En la parte numérica, se realizó la calibración y validación de los modelos ROMS, LIMMIX y VISUAL PLUMES, que fueron utilizados para simular los diferentes efluentes vertidos a través de los emisarios submarinos. A pesar de que los modelos ROMS y LIMMIX no pudieron reproducir satisfactoriamente la zona del campo cercano, debido a la complejidad de los procesos que se conjugan en la superficie y de sus interacciones, con el modelo VISUAL PLUMES fue posible establecer una alternativa de mejora para el diseño de los vertidos de los emisarios submarinos de Gandía y Cullera. De este modo, se pudo comprobar que es posible realizar un diseño del emisario que garantice una mayor dilución y, sobre todo, que cumpla con la Normativa Europea para la calidad de las aguas de baño, incluso en el caso de que la calidad de los efluentes sea muy pobre, como sucede en el caso de agua poco o nada tratadaActualment, la problemàtica que afronten les zones costaneres del Mediterrani en general i el País Valencià en particular, consisteix en la generació de grans quantitats d’aigua residual urbana, principalment durant l’època estival, que són abocades al medi ambient marí/costaner mitjançant els emissaris submarins. Aquesta càrrega de contaminants és tan gran que, a vegades, el medi receptor és incapaç d’assimilar-la a curt termini, provocant episodis de pol·lució que afecten de forma negativa la qualitat de las aigües de bany. En aquest treball, s´han analitzat els processos físics, químics i biològics involucrats en la dinàmica dels ambients costaners i la qualitat de l’aigua en tres zones afectades per l’abocament dels emissaris submarins de Pinedo, Cullera i Gandia, a la Costa Valenciana. De forma concreta, les dades enregistrades en diverses campanyes de camp van permetre evidenciar que la introducció d’aigua residual en aquestes zones somes, amb hidrodinàmica suau i diferents condicions d’abocament, genera una sèrie d’afeccions significatives a curt-mig termini sobre aquest ecosistema costaner. Les altes concentracions de bacteris i nutrients en la superfície, trobades en les estacions properes al punt d’abocament, demostren que la presència dels diferents contaminants, en el medi receptor, és deguda a que van ser alliberats a través de l’efluent abocat per l’emissari submarí. A més a més, es va constatar que, en alguns casos, no es compleix la normativa europea sobre qualitat de les aigües de bany. En la part numèrica, s’ha realitzat el calibrat i la validació dels models ROMS, LIMMIX i VISUAL PLUMES, que han estat utilitzats per simular els diferents efluents abocats a través dels emissaris submarins. Malgrat que els models ROMS i LIMMIX no han pogut reproduir satisfactòriament la zona del camp proper, degut a la complexitat dels processos que tenen lloc a la superfície i de les seves interaccions, amb el model VISUAL PLUMES ha estat possible establir una alternativa de millora per al disseny dels abocaments dels emissaris submarins de Gandia i Cullera. D’aquesta manera, s’ha pogut comprovar que és possible realitzar un disseny de l’emissari que garanteixi una major dilució i, sobre tot, que compleixi amb la Normativa Europea per a la qualitat de les aigües de bany, fins i tot en el cas que la qualitat dels efluents sigui molt pobre, como succeeix en el cas d’aigua poc o gens tractada.One of the most important problems that occur in the Mediterranean coastal areas and particularly in the Valencian Community is the generation of large quantity of urban wastewater especially during the summer season, that is discharged into the sea through marine outfalls. These effluents may carry important loads of contaminants that often the environment is unable to assimilate, causing episodes of pollution that negatively affect the quality of bathing water. This work analyzed the physical, chemical and biological processes involved in the dynamics of coastal environments and water quality on three areas affected by the marine outfalls of Pinedo, Cullera and Gandia in the Valencia coast. The data were acquired in several field campaigns showed that the introduction of wastewater into these shallow areas with weak hydrodynamic and different discharge conditions generates a number of significant conditions, short to medium term, in this coastal environment. High concentrations of bacteria and nutrients in the surface at stations close to the discharging point, demonstrate the presence of different pollutants in the receiving waters due to the effluent discharged by the outfall. In addition, it was found that in some cases, it does not fulfill with the European Water Framework Directive for bathing water. In the numerical work, the calibration and validation of models ROMS, LIMMIX y VISUAL PLUMES was carried out. These numerical models were used to simulate the different effluents discharged through the marine outfalls. While ROMS and LIMMIX models could not satisfactorily reproduce the near field zone due to the complexity of the physical processes and their interactions that take place in the surface, it was with VISUAL PLUME model which made it possible to establish an improved design for Gandia and Cullera marine outfalls. Thus, it was found that it is possible to make a design to ensure higher dilution and, especially that satisfies the bathing water regulations, even in the case that the effluent quality is poor, as in the case of poor or untreated water