5 research outputs found
Alternatives de fertilitzaci贸 per a la rehabilitaci贸 de s貌ls degradats : aplicaci贸 de fang fresc, compostat i d'assecatge t猫rmic /
Consultable des del TDXT铆tol obtingut de la portada digitalitzadaS'estima que a Europa l'any 2005 es generaran 9,4 milions de tones de fangs de depuradora (EEA, 2001), fet que suposa un problema important de cara a la seva eliminaci贸. A l'estat espanyol, al voltant del 46% de la producci贸 de fangs de depuradora de residus urbans es recicla mitjan莽ant aplicacions al s貌l. Aquest tipus de pr脿ctiques estan regulades segons la Directiva Europea 86/278/EEC que, 煤nicament considera com a components de risc el contingut total de metalls pesants i nitrats. L'actual normativa est脿 sent revisada (Working Document on Sludge, 3rd Draft, 2000, unpublished) i es preveu una major restricci贸 i control dels residus org脿nics, per a minimitzar el risc d'efectes negatius a la salut, el medi ambient i el deteriorament de la qualitat del s貌l. Els problemes de salubritat associats a l'煤s dels fangs frescs constitueixen un factor limitant per a la seva aplicaci贸 al s貌l, i fan necessari investigar les possibilitats d'煤s d'aquests residus un cop sotmesos a un proc茅s d'higienitzaci贸. A Catalunya, s'imposaran com a vies de post-tractament el compostatge i l'assecatge t猫rmic. En aquesta tesi es pret茅n avaluar els efectes derivats de l'aplicaci贸 dels tres tipus de fang esmentats, emprats com a esmenes org脿niques, per a la rehabilitaci贸 de s貌ls forestals degradats. S'ha avaluat les avantatges i inconvenients de la fertilitzaci贸 org脿nica amb fangs de depuradora en comparaci贸 a l'adobat mineral en una zona forestal. S'ha caracteritzat al laboratori la din脿mica i les transformacions que afecten la mat猫ria org脿nica de s貌ls tractats amb els tres tipus de fang i seguidament s'han estudiat els efectes d'aquests materials en condicions de camp, emprats com esmenes per a la rehabilitaci贸 de dos s貌ls forestals. Finalment, per tal de donar resposta a quina de les pr脿ctiques de fertilitzaci贸 resulta la m茅s adequada, i al mateix temps de quina manera podem ajudar en preses de decisions, relacionades amb aquesta problem脿tica, es proposa la utilitzaci贸 d'eines d'an脿lisi multicriteri. Dels resultats obtinguts es despr猫n que els fangs poden actuar com a catalitzadors del restabliment de la biofuncionalitat de s貌ls degradats ja que incrementa l'activitat respirat貌ria i la biomassa microbiana del s貌l. La millora de les propietats biol貌giques, f铆siques i nutritives del s貌l estimula el creixement dels arbres i proporciona major recobriment del s貌l, reduint d'aquesta manera el risc d'erosi贸 superficial. La mat猫ria org脿nica dels fangs es mineralitza a un ritme for莽a elevat, sent la del compostat la que presenta major estabilitat i uns efectes m茅s perdurables. Els desavantatges m茅s importants es relacionen amb problemes de p猫rdues de nitrogen per lixiviaci贸 i certa inhibici贸 observada en la germinaci贸 de les plantes en condicions controlades (especialment en el fang t猫rmic). Una major disponibilitat de nutrients a l'inici provoca un increment del quocient metab貌lic (qCO2). El descens dr脿stic del qCO2, major amb el fang t猫rmic, es d茅u a la reducci贸 de l'activitat microbiana causada probablement per l'esgotament del carboni org脿nic l脿bil, per貌 no podem descartar algun tipus d'estr猫s. A m茅s, l'aplicaci贸 superficial de fangs, provoca una certa ruderalitzaci贸 i reducci贸 de la riquesa flor铆stica de les 脿rees estudiades. Pel que fa a les difer猫ncies observades entre els diferents fangs, cal destacar que en el proc茅s de post-tractament dels fangs es produeixen canvis en les propietats qu铆miques que es revelen en modificacions de la mat猫ria org脿nica, l'efici猫ncia microbiana i la mineralitzaci贸 del nitrogen. La utilitzaci贸 de les an脿lisi multicriteri representen una valuosa aportaci贸 per a la presa de decisions en problemes que, com aquest, tenen un elevat grau d'incertesa i diferents objectius i en conflicte. Des del punt de vista aplicat, donats els indicis de toxicitat observats en l'aplicaci贸 de fang t猫rmic i l'esc脿s coneixement actual que ens permeti fer una avaluaci贸 real dels efectes directes i indirectes que provoca aquest fang, es recomana no aplicar-lo de manera generalitzada mentre no es garanteixi la seva innoqu茂tat.It is estimated that Europe will produce 9.4 million tons of sludge by 2005 (EEA 2001). The elimination of such sludge amounts poses important difficulties. In Spain, approximately 46% of the urban sewage sludge production is used in soil rehabilitation, as regulated by the UE Directive 86/278/EEC. Under this directive, only total heavy metal and nitrate contents are considered a risk. The present Directive is currently being revised (Working Document on Sludge, 3rd Draft, 2000, unpublished) and greater restrictions and control of organic wastes are expected, which will help to diminish the negative effects of sludge application on health, environment and soil quality. Environmental health problems associated with the use of digested sewage sludge hinder its application and make it necessary to investigate the possibility of using treated waste. Two types of sludge treatment, composting and thermal drying, are practiced in Catalonia. This PhD dissertation attempts to evaluate the effects of three types of sewage sludge (fresh, composted, thermal) used for forest soil rehabilitation. Advantages and disadvantages of sewage sludge amendment were compared to mineral fertilization in a project to transform a scrubland into a dehesa-system. Organic matter dynamics and transformation were characterized in the laboratory in soils treated with the different sludge types. Subsequently, the effects of sludge application were studied under field conditions. The study also proposes the use of multi-criteria analysis to identify the most suitable fertilization alternatives and to assist in the decision-making process of sludge recycling. The results show that sewage sludge use improves soil functionality, because it enhances respiration rates and microbial biomass. The improvement of soil physical, biological and fertilization properties stimulates tree growth and increases ground cover, thus reducing soil run-off. The organic matter of sewage sludge is quickly mineralized. In this study, composted sludge organic matter showed the greatest stability and longest-lasting effects. Experiments under controlled conditions showed that important disadvantages of sludge use were nitrate lixiviation and plant germination inhibition (especially with thermal sludge). Initial enhanced nutrient availability induced an increase of the metabolic quotient (qCO2). A subsequent fast reduction of qCO2, particularly in thermal sludge, was due to a decrease in microbial activity, probably caused by the depletion of labile organic carbon, although some type of stress could also be involved. Sewage sludge application above the soil surface caused the ruderalisation of the herbaceous community and the reduction of plant richness in the studied areas. In relation to the differences between different types of sewage sludge, it is possible to emphasize that in the composted and thermal processes changes in the chemical properties take place that are evidenced in the modification of the organic matter, microbial efficiency and nitrogen mineralization. Multi-criteria evaluation tools make a valuable contribution to decision-making processes concerning sewage sludge applications, because a high degree of uncertainty and conflictive objectives exist in these processes. Due to the observed signs of toxicity related to thermal sludge use and the scarce current knowledge to evaluate direct and indirect sewage sludge amendment effects, it is recommended to discontinue thermal sludge application in field conditions, until its innocuousness can be guaranteed
Proceso y m茅todos de evaluaci贸n integrada participativa de degradaci贸n en agroecosistemas semi谩ridos. Un caso de estudio en un 谩rea protegida en el tr贸pico seco nicarag眉ense
Los procesos de evaluaci贸n integrada y participativa son un buen marco metodol贸gico-operativo para la toma de decisiones frente a cuestiones ambientales complejas que conciernen a socio-agroecosistemas de alto dinamismo e impredecibilidad a cambios y con intereses conflictivos de los actores implicados en su gesti贸n. La finalidad del art铆culo es mostrar el potencial de la aplicaci贸n de un enfoque interdisciplinar e intercultural para desarrollar un proceso multiescala y multiobjetivo de evaluaci贸n comprehensiva y critica de la degradaci贸n ambiental de un sistema agrosilvopastoril semi谩rido en Nicaragua. Pese a que se trate de un proceso en curso, el art铆culo describe y reflexiona sobre los resultados metodol贸gicos de los primeros dos a帽os y discute como la combinaci贸n de m茅todos desde diferentes disciplinas y la integraci贸n de conocimientos han permitido explicitar las incertidumbres e ignorancias sobre la comprensi贸n del sistema y los procesos de cambios socio-ecol贸gicos locales, plantear y validar nuevas hip贸tesis de trabajo e obtener exactitud y relevancia de la evaluaci贸n de degradaci贸n. Asimismo el proceso participativo intenta incluir, en cada fase, la pluralidad de actores, con sus intereses y valoraciones y representaciones de futuro, para asegurar la calidad del proceso. Finalmente, el an谩lisis de escenarios se demuestra 煤til instrumento para aclarar las posibles interfases de conflicto y compromiso o negociaci贸n entre actores, investigadores y tomadores de decisiones sobre opciones alternativas de gesti贸n y desarrollo para el 谩rea.The integrated and participatory assessment processes are a good methodological and operational framework for decision making, facing to complexity on environmental issues when agro-ecosystems are highly dynamics and unpredictable to changes and there are plural and conflictive interests. This paper aims to investigate the potencial for such interdisciplinary and intercultural approach to develop a comprehensive and constructive multiscale and multiobjetive process of land degradation assessment in semiarid agro-ecosystems. Since the overall process is still on going, the research, applied to a case study in Nicaragua, describes and reflects on the experience through the first two years of work. The article argues that the integration between scientific and lay knowledge allows facing the uncertainties and ignorance in understanding complex systems and main processes of change, to propose and validate research hypothesis and to lead to both accurate and relevant assessment of land degradation. The participatory approach, using methods from a variety of disciplines, attempts to capture the plurality of relevant actors, with different objectives, values and representations of future, in order to assure quality of the process. Finally, the paper illustrates the usefulness of scenario analysis to explore the "arenas" of conflicts and negotiation between researchers, actors and decision makers on alternative management and development policies options
Alternatives de fertilitzaci贸 per a la rehabilitaci贸 de s貌ls degradats: aplicaci贸 de fang fresc, compostat i d'assecatge t猫rmic
S'estima que a Europa l'any 2005 es generaran 9,4 milions de tones de fangs de depuradora (EEA, 2001), fet que suposa un problema important de cara a la seva eliminaci贸. A l'estat espanyol, al voltant del 46% de la producci贸 de fangs de depuradora de residus urbans es recicla mitjan莽ant aplicacions al s貌l. Aquest tipus de pr脿ctiques estan regulades segons la Directiva Europea 86/278/EEC que, 煤nicament considera com a components de risc el contingut total de metalls pesants i nitrats. L'actual normativa est脿 sent revisada (Working Document on Sludge, 3rd Draft, 2000, unpublished) i es preveu una major restricci贸 i control dels residus org脿nics, per a minimitzar el risc d'efectes negatius a la salut, el medi ambient i el deteriorament de la qualitat del s貌l. Els problemes de salubritat associats a l'煤s dels fangs frescs constitueixen un factor limitant per a la seva aplicaci贸 al s貌l, i fan necessari investigar les possibilitats d'煤s d'aquests residus un cop sotmesos a un proc茅s d'higienitzaci贸. A Catalunya, s'imposaran com a vies de post-tractament el compostatge i l'assecatge t猫rmic. En aquesta tesi es pret茅n avaluar els efectes derivats de l'aplicaci贸 dels tres tipus de fang esmentats, emprats com a esmenes org脿niques, per a la rehabilitaci贸 de s貌ls forestals degradats. S'ha avaluat les avantatges i inconvenients de la fertilitzaci贸 org脿nica amb fangs de depuradora en comparaci贸 a l'adobat mineral en una zona forestal. S'ha caracteritzat al laboratori la din脿mica i les transformacions que afecten la mat猫ria org脿nica de s貌ls tractats amb els tres tipus de fang i seguidament s'han estudiat els efectes d'aquests materials en condicions de camp, emprats com esmenes per a la rehabilitaci贸 de dos s貌ls forestals. Finalment, per tal de donar resposta a quina de les pr脿ctiques de fertilitzaci贸 resulta la m茅s adequada, i al mateix temps de quina manera podem ajudar en preses de decisions, relacionades amb aquesta problem脿tica, es proposa la utilitzaci贸 d'eines d'an脿lisi multicriteri. Dels resultats obtinguts es despr猫n que els fangs poden actuar com a catalitzadors del restabliment de la biofuncionalitat de s貌ls degradats ja que incrementa l'activitat respirat貌ria i la biomassa microbiana del s貌l. La millora de les propietats biol貌giques, f铆siques i nutritives del s貌l estimula el creixement dels arbres i proporciona major recobriment del s貌l, reduint d'aquesta manera el risc d'erosi贸 superficial. La mat猫ria org脿nica dels fangs es mineralitza a un ritme for莽a elevat, sent la del compostat la que presenta major estabilitat i uns efectes m茅s perdurables. Els desavantatges m茅s importants es relacionen amb problemes de p猫rdues de nitrogen per lixiviaci贸 i certa inhibici贸 observada en la germinaci贸 de les plantes en condicions controlades (especialment en el fang t猫rmic). Una major disponibilitat de nutrients a l'inici provoca un increment del quocient metab貌lic (qCO2). El descens dr脿stic del qCO2, major amb el fang t猫rmic, es d茅u a la reducci贸 de l'activitat microbiana causada probablement per l'esgotament del carboni org脿nic l脿bil, per貌 no podem descartar algun tipus d'estr猫s. A m茅s, l'aplicaci贸 superficial de fangs, provoca una certa ruderalitzaci贸 i reducci贸 de la riquesa flor铆stica de les 脿rees estudiades. Pel que fa a les difer猫ncies observades entre els diferents fangs, cal destacar que en el proc茅s de post-tractament dels fangs es produeixen canvis en les propietats qu铆miques que es revelen en modificacions de la mat猫ria org脿nica, l'efici猫ncia microbiana i la mineralitzaci贸 del nitrogen.La utilitzaci贸 de les an脿lisi multicriteri representen una valuosa aportaci贸 per a la presa de decisions en problemes que, com aquest, tenen un elevat grau d'incertesa i diferents objectius i en conflicte. Des del punt de vista aplicat, donats els indicis de toxicitat observats en l'aplicaci贸 de fang t猫rmic i l'esc脿s coneixement actual que ens permeti fer una avaluaci贸 real dels efectes directes i indirectes que provoca aquest fang, es recomana no aplicar-lo de manera generalitzada mentre no es garanteixi la seva innoqu茂tat.It is estimated that Europe will produce 9.4 million tons of sludge by 2005 (EEA 2001). The elimination of such sludge amounts poses important difficulties. In Spain, approximately 46% of the urban sewage sludge production is used in soil rehabilitation, as regulated by the UE Directive 86/278/EEC. Under this directive, only total heavy metal and nitrate contents are considered a risk. The present Directive is currently being revised (Working Document on Sludge, 3rd Draft, 2000, unpublished) and greater restrictions and control of organic wastes are expected, which will help to diminish the negative effects of sludge application on health, environment and soil quality. Environmental health problems associated with the use of digested sewage sludge hinder its application and make it necessary to investigate the possibility of using treated waste. Two types of sludge treatment, composting and thermal drying, are practiced in Catalonia. This PhD dissertation attempts to evaluate the effects of three types of sewage sludge (fresh, composted, thermal) used for forest soil rehabilitation. Advantages and disadvantages of sewage sludge amendment were compared to mineral fertilization in a project to transform a scrubland into a dehesa-system. Organic matter dynamics and transformation were characterized in the laboratory in soils treated with the different sludge types. Subsequently, the effects of sludge application were studied under field conditions. The study also proposes the use of multi-criteria analysis to identify the most suitable fertilization alternatives and to assist in the decision-making process of sludge recycling.The results show that sewage sludge use improves soil functionality, because it enhances respiration rates and microbial biomass. The improvement of soil physical, biological and fertilization properties stimulates tree growth and increases ground cover, thus reducing soil run-off. The organic matter of sewage sludge is quickly mineralized. In this study, composted sludge organic matter showed the greatest stability and longest-lasting effects. Experiments under controlled conditions showed that important disadvantages of sludge use were nitrate lixiviation and plant germination inhibition (especially with thermal sludge). Initial enhanced nutrient availability induced an increase of the metabolic quotient (qCO2). A subsequent fast reduction of qCO2, particularly in thermal sludge, was due to a decrease in microbial activity, probably caused by the depletion of labile organic carbon, although some type of stress could also be involved. Sewage sludge application above the soil surface caused the ruderalisation of the herbaceous community and the reduction of plant richness in the studied areas. In relation to the differences between different types of sewage sludge, it is possible to emphasize that in the composted and thermal processes changes in the chemical properties take place that are evidenced in the modification of the organic matter, microbial efficiency and nitrogen mineralization. Multi-criteria evaluation tools make a valuable contribution to decision-making processes concerning sewage sludge applications, because a high degree of uncertainty and conflictive objectives exist in these processes.Due to the observed signs of toxicity related to thermal sludge use and the scarce current knowledge to evaluate direct and indirect sewage sludge amendment effects, it is recommended to discontinue thermal sludge application in field conditions, until its innocuousness can be guaranteed
Envisioning adaptive strategies to change : participatory scenarios for agropastoral semiarid systems in Nicaragua
Historically, the semiarid social-ecological systems of the dry Central American corridor have proven resilient to pressures. However, in the last century, these systems have experienced huge environmental and socioeconomic changes that have increased the vulnerability of local livelihoods to shocks. New approaches are needed to capture complex, uncertain, cross-scale and nonlinear relationships among drivers of change and vulnerability. Therefore, to tackle this challenge, we have applied a participatory and interdisciplinary methodological framework of vulnerability assessment to a case study in northern Nicaragua. We triangulated a range of information and data from participatory and scientific research to explore historical and current drivers of changes that affect the system's components and indicators of vulnerability, represented in a 3-dimensional space in terms of ecological resilience, the socioeconomic ability of individuals to adapt to change, and an institutional capacity to buffer and respond to crisis. A projection of climatic changes combined with a participatory scenario analysis helped, then, to heuristically analyze tendencies of vulnerability in the future and to explore what policy options might enhance the system's adaptive capacity to face new pressures. Our work primarily contributes to an empirical understanding of key factors that influence vulnerability and learning about local strategies to adapt to change in semiarid agropastoral systems in Central America. We also make a methodological contribution by testing the use of a multidimensional vulnerability framework as a way of stimulating discussion among researchers, local stakeholders, and policy makers
Proceso y m茅todos de evaluaci贸n integrada participativa de degradaci贸n en agroecosistemas semi谩ridos. Un caso de estudio en un 谩rea protegida en el tr贸pico seco nicarag眉ense
Los procesos de evaluaci贸n integrada y participativa son un buen marco metodol贸gico-operativo para la toma de decisiones frente a cuestiones ambientales complejas que conciernen a socio-agroecosistemas de alto dinamismo e impredecibilidad a cambios y con intereses conflictivos de los actores implicados en su gesti贸n. La finalidad del art铆culo es mostrar el potencial de la aplicaci贸n de un enfoque interdisciplinar e intercultural para desarrollar un proceso multiescala y multiobjetivo de evaluaci贸n comprehensiva y critica de la degradaci贸n ambiental de un sistema agrosilvopastoril semi谩rido en Nicaragua. Pese a que se trate de un proceso en curso, el art铆culo describe y reflexiona sobre los resultados metodol贸gicos de los primeros dos a帽os y discute como la combinaci贸n de m茅todos desde diferentes disciplinas y la integraci贸n de conocimientos han permitido explicitar las incertidumbres e ignorancias sobre la comprensi贸n del sistema y los procesos de cambios socio-ecol贸gicos locales, plantear y validar nuevas hip贸tesis de trabajo e obtener exactitud y relevancia de la evaluaci贸n de degradaci贸n. Asimismo el proceso participativo intenta incluir, en cada fase, la pluralidad de actores, con sus intereses y valoraciones y representaciones de futuro, para asegurar la calidad del proceso. Finalmente, el an谩lisis de escenarios se demuestra 煤til instrumento para aclarar las posibles interfases de conflicto y compromiso o negociaci贸n entre actores, investigadores y tomadores de decisiones sobre opciones alternativas de gesti贸n y desarrollo para el 谩rea.The integrated and participatory assessment processes are a good methodological and operational framework for decision making, facing to complexity on environmental issues when agro-ecosystems are highly dynamics and unpredictable to changes and there are plural and conflictive interests. This paper aims to investigate the potencial for such interdisciplinary and intercultural approach to develop a comprehensive and constructive multiscale and multiobjetive process of land degradation assessment in semiarid agro-ecosystems. Since the overall process is still on going, the research, applied to a case study in Nicaragua, describes and reflects on the experience through the first two years of work. The article argues that the integration between scientific and lay knowledge allows facing the uncertainties and ignorance in understanding complex systems and main processes of change, to propose and validate research hypothesis and to lead to both accurate and relevant assessment of land degradation. The participatory approach, using methods from a variety of disciplines, attempts to capture the plurality of relevant actors, with different objectives, values and representations of future, in order to assure quality of the process. Finally, the paper illustrates the usefulness of scenario analysis to explore the "arenas" of conflicts and negotiation between researchers, actors and decision makers on alternative management and development policies options