Irrigation effects on soil organic carbon under a ryegrass-white clover pasture on a Lismore stony silt loam soil : A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University

Long-term summer irrigation of temperate managed pastures has been reported to either increase or decrease soil organic carbon (SOC) stocks when compared with dryland systems. Understanding the short-term effects of irrigation on the assimilation, partitioning and storage of carbon (C) within the plant-soil system is important in order to identify key mechanisms that explain the observed differences in SOC responses to irrigation. Two continuous ¹³CO₂ pulse labelling experiments were performed to ¹³C-labelled mesocosms established with ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.) mixed pasture using a Lismore stony silt loam soil (Pallic Firm Brown soil). This PhD study has demonstrated that summer irrigation applied to increase above-ground pasture productivity in managed ryegrass-white clover pastures had no demonstrable effects on the storage and loss of new photosynthate C partitioned into the soil over an annual production cycle when compared with dryland conditions. Therefore, based on these results it can be concluded that under the conditions of this research, summer irrigation had a neutral effect on the formation and short-term (< 1 year) storage of newly formed SOC when compared with dryland conditions. However, the study of soil C components or pools (e.g. rhizosphere soil and soil particle size fractions) demonstrated that irrigation affected the spatial and temporal partitioning of root derived-C in the soil, when compared with a dryland pasture system, by reducing the accumulation of new photosynthate C in the rhizosphere soil while increasing the accumulation of this new C in the fine POM (53–250 µm) and clay (< 5 µm) size fractions of the non-rhizosphere soil. This re-distribution of root derived-C among the soil C components occurred relatively early in the irrigated pasture over the summer and autumn seasons, while in the dryland pasture the re-distribution occurred over the following autumn, winter and spring seasons. In addition, the results showed that with irrigation the root system became smaller and shallower, with the pasture biomass allocation to above-ground plant components being favoured. This effect persisted over an annual pasture growth cycle, especially during the autumn and spring seasons following the cessation of summer irrigation. These findings may have implications for the longer-term storage of SOC in dryland relative to irrigated pasture systems that were not tested in this study. Further research is needed to improve our understanding on the mechanisms driving the different responses of SOC to irrigation with a particular focus on: (i) determining the causes for the higher root turnover under irrigated pastures and, (ii) evaluating how irrigation interacts with other pasture management practices (e.g. fertiliser, grazing) to affect the formation, function and storage (> 1 year) of SOC, including that associated with POM and MAOM in soils

Análisis y propuestas al marco regulatorio de las descargas de aguas residuales no domésticas a las redes de alcantarillado

el objetivo del presente trabajo de investigación es analizar el marco normativo regulatorio para el control de las descargas de aguas residuales no domésticas a las redes de alcantarillado, con la finalidad de realizar propuestas que permitan su aplicación eficiente. Se considera que el tema se justifica por sí mismo, debido a la relevancia e importancia para el sector saneamiento. Asimismo, al ser un tema totalmente nuevo para el país, no existe experiencia previa, y la normatividad y regulación al respecto ha entrado en vigencia recién a partir del mes de setiembre del 2013. Para realizar dicho análisis y plantear algunas propuestas, el presente documento ha sido estructurado en cinco capítulos. Se inicia con una breve revisión de la organización del sector saneamiento, se describen los servicios de alcantarillado. Luego, en el siguiente capítulo, donde se desarrolla un análisis de la situación de las descargas de aguas residuales no domésticas, se explica las características físicas, químicas y bacteriológicas de las mismas, así como los impactos de la contaminación de dichas aguas en la infraestructura sanitaria. En el cuarto capítulo,se aborda de manera extensa la regulación de las descargas de aguas residuales no domésticas, desarrollando en primer lugar el marco normativo general y específico que circunscribe la aplicación de los VMA y, sobre la base de experiencias reales de EPS, se presenta un análisis del proceso de implementación del marco regulatorio que permite obtener conclusiones valiosas para el planteamiento de propuestas. En esta misma sección, se describen las principales limitaciones encontradas para la efectiva aplicación del marco regulatorio y se analiza brevemente la experiencia sobre el tema del presente trabajo de investigación en otros países como Chile, Colombia y México. En el último capítulo, se plantean algunas propuestas para modificar el marco normativo y se esbozan algunas estrategias y acciones específicas que podrían ser parte de un plan sectorial para facilitar la implementación de los VMA, considerándolo como un proceso que involucra diversos actores, más allá de las entidades del sector saneamiento. Finalmente, se presentan algunas conclusiones y recomendaciones

Avaluació de la capacitat de segrest de carboni d'un sòl restaurat amb fangs de depuradora : estabilitat de la matèria orgànica

L'avaluació de la capacitat de segrest de carboni d'un sòl denudat per l'extracció de calcàries i la seva posterior restauració amb fangs de depuradora s'ha realitzat mitjançant l'anàlisi de l'estabilitat de la matèria orgànica del sòl (MOS) en funció de la dosi de fangs aplicada. Els resultats d'aquest treball demostren dos fets fonamentals per a l'estudi de la capacitat de segrest de carboni, els qual són: la conservació del contingut total de MOS i l'augment de la seva estabilitat fins a nivells més alts que els de la MOS de les parcel·les de control. Aquests resultats són explicables per (i) la conservació i augment de la MOS recalcitrant, i (ii) la protecció d'una porció més o menys rellevant de la MO làbil continguda amb els fangs gràcies a l'acció simultània dels mecanismes d'estabilització de la MOS, com són: l'estabilització bioquímica (humificació), química, física, a més de la pròpia hidrofobicitat de la MOS, aquests dos últims potenciats per l'addicció del fangs de depuradora.La evaluación de la capacidad de secuestro de carbono de un suelo degradado por la extracción de caliza y su posterior restauración con lodos de depuradora se ha realizado mediante el análisis de la estabilidad de la materia orgánica del suelo (MOS) en función de la dosis de lodos aplicada. Los resultados de este trabajo demuestran dos hechos fundamentales para el estudio de la capacidad de secuestro de de carbono, estos hechos son: la conservación de la cantidad total de MOS y el aumento de su estabilidad hasta niveles superiores a los de la MOS de las parcelas control. Estos resultados son explicables por (i) la conservación y el aumento de la MOS recalcitrante, y (ii) la protección de una proporción más o menos relevante de la MOS lábil contenida en los lodos gracias a la acción simultánea de los mecanismos de estabilización, como son: la estabilización bioquímica (humificación), química, física y la propia hidrofobicidad de la MOS, estos dos últimos potenciados por la adición de los lodos de depuradora.The assessment of the C sequestration capacity of a degraded soil by the extraction of limestone and then restored with sewage sludge was conducted by analyzing the stability of the soil organic matter (SOM) based on the sludge dose. The results of this study highlight two fundamental facts for the study of carbon sequestration: the conservation of the total SOM amount and an increase in its stability to levels higher than the SOM of the control soil. These results can be explained by (i) the preservation or increase of the recalcitrant SOM, and (ii) the protection of a fraction more or less relevant of the labile SOM contained in the sludge thanks to the joint action of SOM stabilization processes such as: biochemical (humification), chemical, physical and also the hydrophobicity of the SOM, the two latter enhanced by the addiction of sewage sludge

Diplopia secondary to dural puncture: report of a case

Introducción: la anestesia raquídea, a pesar de sus múltiples ventajas, no está exenta de complicaciones; las neurológicas son las más temidas. La diplopía es una complicación que constituye motivo de preocupación para el Especialista en Anestesiología. Son pocos los casos de diplopía descritos en la bibliografía. Presentación del caso: se presenta el caso de una puérpera a la que se le practicó cesárea y consecutivamente presentó cefalea postpunción dural y diplopía. El cuadro de diplopía presentado por la paciente fue secundario a la hipotensión de líquido cefalorraquídeo subsiguiente a su pérdida excesiva. Conclusiones: la paciente, a pesar de haber presentado la diplopía como complicación de la punción dural asociada a la anestesia raquídea, tuvo una evolución favorable y no presentó complicaciones.Introduction: spinal anesthesia, despite its many advantages, is not without complications; the neurological ones are the most feared. Diplopia is a complication that represent  a concern for the Anesthesiology Specialist. There are few cases of diplopia described in the literature. Case report: the purpose of this job is to present the case of a puerpera who underwent cesarean section and consecutively presented dural post-puncture headache and diplopia. The diplopia presented by the patient was secondary to hypotension of cerebrospinal fluid subsequent to excessive loss. Conclusions: the patient, despite having presented diplopia as a complication of the dural puncture associated with spinal anesthesia, had a favorable evolution and did not present complications

Factors influencing the spread of pertussis in households: a prospective study, Catalonia and Navarre, Spain, 2012 to 2013

We aimed to investigate transmission rates of pertussis in household contacts of cases and factors associated with transmission. A prospective epidemiological study was conducted in 2012 and 2013 to determine the incidence of pertussis among household contacts of reported cases in Catalonia and Navarre, Spain. An epidemiological survey was completed for each case and contact, who were followed for 28 days to determine the source of infection (primary case) and detect the occurrence of secondary cases. Odds ratios (ORs) were used to estimate the effectiveness of vaccination and chemoprophylaxis in preventing new cases, using the formula (1 − OR) × 100. For the 688 primary cases, a total of 2,852 contacts were recorded. The household transmission rate was 16.1% (459/2,852) and rose according to the age (> 18 years) and lack of immunisation of the primary cases, and also the age (0–18 years), family relationship (siblings and children), lack of vaccination and chemoprophylaxis of contacts. Pertussis vaccine effectiveness in preventing new cases was 65.0% (95% confidence interval (CI): 11.6 to 86.2) for full vaccination (≥ 4 doses) and 59.7% (95% CI: −6.8 to 84.8) for incomplete vaccination (< 4 doses). The effectiveness of chemoprophylaxis was 62.1% (95% CI: 40.3 to 75.9). To reduce household transmission, contacts should be investigated to detect further cases and to administer chemoprophylaxis. The current vaccination status of cases and contacts can reduce household transmission.This study was supported by the Ministry of Science and Innovation, Institute of Health Carlos III (Project PI11/02557) and Fondo Europeo de Desarrollo Regional (FEDER-Una manera de hacer Europa)

Impacts of conversion of cropland to grassland on the C-N-P stoichiometric dynamics of soil, microorganisms, and enzymes across China: A synthesis

In response to escalating land degradation, the conversion of cropland to grassland has emerged as a crucial mitigation strategy. This conversion has a significant influence on the stoichiometry of soil, microorganisms, and enzymes, specifically in relation to carbon (C), nitrogen (N), and phosphorus (P). A meta-analysis was conducted with 371 observations from 122 articles investigating the impacts of cropland to grassland conversion on the C-N-P stoichiometric dynamics of soils, microorganisms, and enzymes across China. The findings revealed that conversion significantly increased soil C:P (9.0%), soil N:P (5.6%), microbial C:N (15.5%), and notably, microbial C:P by 57.9%. This substantial increase in microbial C:P indicates that microbial communities are highly responsive to land use conversion. Contrastingly, the enzyme C:P ratio decreased by 19.8%, suggesting microbial adaptation to changing nutrient availability. The duration of conversion was positively correlated with soil C:P and N:P ratios, implying that relative P availability may decrease as conversion progresses. However, duration was negatively correlated with microbial C:P. Environmental factors such as clay content, mean annual temperature, and mean annual precipitation were positively correlated with microbial C:N and negatively correlated with microbial N:P, while soil pH was inversely correlated with microbial C:N. These results suggest the substantial influence of cropland to grassland conversion on soil, microbial, and enzyme stoichiometry, with particularly pronounced effects on microbial communities. The observed shifts in stoichiometric ratios suggest changes in nutrient cycling and availability following conversion. While these changes are primarily attributed to the land use conversion, we acknowledge that alterations in management practices, such as reduced fertilization, likely contribute to the observed stoichiometric shifts. Our findings emphasize the importance of considering both environmental factors and management practices when implementing grassland conversion initiatives

Autobeca

Projecte presentat al 3r Premi a la Qualitat de la Gestió Universitària, convocat pel Consell Social de la UPCAward-winnin

Factors influencing the spread of pertussis in households: a prospective study, Catalonia and Navarre, Spain, 2012 to 2013

We aimed to investigate transmission rates of pertussis in household contacts of cases and factors associated with transmission. A prospective epidemiological study was conducted in 2012 and 2013 to determine the incidence of pertussis among household contacts of reported cases in Catalonia and Navarre, Spain. An epidemiological survey was completed for each case and contact, who were followed for 28 days to determine the source of infection (primary case) and detect the occurrence of secondary cases. Odds ratios (ORs) were used to estimate the effectiveness of vaccination and chemoprophylaxis in preventing new cases, using the formula (1 - OR) × 100. For the 688 primary cases, a total of 2,852 contacts were recorded. The household transmission rate was 16.1% (459/2,852) and rose according to the age (> 18 years) and lack of immunisation of the primary cases, and also the age (0-18 years), family relationship (siblings and children), lack of vaccination and chemoprophylaxis of contacts. Pertussis vaccine effectiveness in preventing new cases was 65.0% (95% confidence interval (CI): 11.6 to 86.2) for full vaccination (≥ 4 doses) and 59.7% (95% CI: -6.8 to 84.8) for incomplete vaccination (< 4 doses). The effectiveness of chemoprophylaxis was 62.1% (95% CI: 40.3 to 75.9). To reduce household transmission, contacts should be investigated to detect further cases and to administer chemoprophylaxis. The current vaccination status of cases and contacts can reduce household transmission