Study on the changes of soil chemical characteristics as result of prescribed fire

Every year, particularly during the summer period, the Portuguese forests are devastated by forest fire that destroys their ecosystems. So in order to prevent these forest fires, public and private authorities frequently use methods for the reduction of combustible mass as the prescribed fire and the mechanical vegetation pruning. All of these methods of prevention of forest fires alter the vegetation layer and/or soil [1-2]. This work aimed the study of the variation of some chemical characteristics of soil that suffered prescribed fire. The studied an area was located in the Serra of Cabreira (Figure 1) with 54.6 ha. Twenty sampling points were randomly selected and samples were collected with a shovel before, just after the prescribed fire, and 125 and 196 days after that event. The parameters that were studied were: pH, soil moisture, organic matter and iron, magnesium and potassium total concentration. All the analysis followed International Standard Methodologies. This work allowed to conclude that: a) after the prescribed fire; i) the pH remained practically equal to the the initial value; ii) occurred a slight increase of the average of the organic matter contents and iron total contents; b) at the end of the sampling period compared to the initial values; i) the pH didn��t change significantly; ii) the average of the contents of organic matter decreased; and iii) the average of the total contents of Fe, Mg and K increased.

Impact of prescribed fire on the chemical properties of soil

Prescribed fire is a common forest management tool used in Portugal to reduce the fuel load availability and minimize the occurrence of wildfires. In addition, the use of this technique also causes an impact to ecosystems. In this presentation we propose to illustrate some results of our project in two forest sites, both located in Northwest Portugal, where the effect of prescribed fire on soil properties were recorded during a period of 6 months. Changes in soil moisture, organic matter, soil pH and iron, were examined by Principal Component Analysis multivariate statistics technique in order to determine impact of prescribed fire on these soil properties in these two different types of soils and determine the period of time that these forest soils need to recover to their pre-fire conditions, if they can indeed recover. Although the time allocated to this study does not allow for a widespread conclusion, the data analysis clearly indicates that the pH values are positively correlated with iron values at both sites. In addition, geomorphologic differences between both sampling sites, Gramelas and Anjos, are relevant as the soils��� properties considered have shown different performances in time. The use of prescribed fire produced a lower impact in soils originated from more amended bedrock and therefore with a ticker humus covering (Gramelas) than in more rocky soils with less litter covering (Anjos) after six months after the prescribed fire occurrence.

Nanoparticles for the remediation of agrogenic contaminated soil and groundwater ��� a review

The wide spread use and strong reliance on both fertilizers and pesticides made of agrigenic pollution one of the major contemporary threats to environment and human health. Impacts on the environment vary from local effects, such as eutrophycation1, 2, loss of biodiversity and diminished ecosystem health3, to global effects, such as the aggravation of global warming2, 4 and ozone layer depletion5. The novelty of nanoremediation and its early successes, reported for various contexts, present the prospect for the development of relevant applications for agrigenic contaminants.

Nanoparticles based Permeable Reactive Barriers as an Eco-efficient Technology for nitrate remediation in soil and groundwater

The need to increase agricultural yield led, among others, to an increase in the consumption of nitrogen based fertilizers. As a consequence, there are excessive concentrations of nitrates, the most abundant of the reactive nitrogen (Nr) species, in several areas of the world. The demographic changes and projected population growth for the next decades, and the economic shifts which are already shaping the near future are powerful drivers for a further intensification in the use of fertilizers, with a predicted increase of the nitrogen loads in soils. Nitrate easily diffuses in the subsurface environments, portraying high mobility in soils. Moreover, the presence of high nitrate loads in water has the potential to cause an array of health dysfunctions, such as methemoglobinemia and several cancers. Permeable Reactive Barriers (PRB) placed strategically relatively to the nitrate source constitute an effective technology to tackle nitrate pollution. Ergo, PRB avoid various adverse impacts resulting from the displacement of reactive nitrogen downstream along water bodies. A four stages literature review was carried out in 34 databases. Initially, a set of pertinent key words were identified to perform the initial databases searches. Then, the synonyms of those initial key words were used to carry out a second set of databases searches. The third stage comprised the identification of other additional relevant terms from the research papers identified in the previous two stages. Again, databases searches were performed with this third set of key words. The final step consisted of the identification of relevant papers from the bibliography of the relevant papers identified in the previous three stages of the literature review process. The set of papers identified as relevant for in-depth analysis were assessed considering a set of relevant characterization variables.

Influence of Soil Chemistry and Plant Physiology in the Phytoremediation of Cu, Mn, and Zn

Different anthropogenic sources of metals can result from agricultural, industrial, military, mining and urban activities that contribute to environmental pollution. Plants can be grown for phytoremediation to remove or stabilize contaminants in water and soil. Copper (Cu), manganese (Mn) and zinc (Zn) are trace essential metals for plants, although their role in homeostasis in plants must be strictly regulated to avoid toxicity. In this review, we summarize the processes involved in the bioavailability, uptake, transport and storage of Cu, Mn and Zn in plants. The efficiency of phytoremediation depends on several factors including metal bioavailability and plant uptake, translocation and tolerance mechanisms. Soil parameters, such as clay fraction, organic matter content, oxidation state, pH, redox potential, aeration, and the presence of specific organisms, play fundamental roles in the uptake of trace essential metals. Key processes in the metal homeostasis network in plants have been identified. Membrane transporters involved in the acquisition, transport and storage of trace essential metals are reviewed. Recent advances in understanding the biochemical and molecular mechanisms of Cu, Mn and Zn hyperaccumulation are described. The use of plant-bacteria associations, plant-fungi associations and genetic engineering has opened a new range of opportunities to improve the efficiency of phytoremediation. The main directions for future research are proposed from the investigation of published results.

PCR with Paracoccidioides brasiliensis specific primers: potential use in ecological studies

The precise microenvironment of Paracoccidioides brasiliensis has not yet been discovered perhaps because the methods used are not sensitive enough. We applied to this purpose the polymerase chain reaction (PCR) using three sets of specific primers corresponding to two P. brasiliensis genes. This fungus as well as several other fungi, were grown and their DNA obtained by mechanical disruption and a phenol chloroform isoamylalcohol-based purification method. The DNA served for a PCR reaction that employed specific primers from two P. brasiliensis genes that codify for antigenic proteins, namely, the 27 kDa and the 43 kDa. The lowest detection range for the 27 kDa gene was 3 pg. The amplification for both genes was positive only with DNA from P. brasiliensis; additionally, the mRNA for the 27 kDa gene was present only in P. brasiliensis, as indicated by the Northern analysis. The standardization of PCR technology permitted the amplification of P. brasiliensis DNA in artificially contaminated soils and in tissues of armadillos naturally infected with the fungus. These results indicate that PCR technology could play an important role in the search for P. brasiliensis�� habitat and could also be used in other ecological studies.

Effects of Soil Compaction and Organic Carbon Content on Preferential Flow in Loamy Field Soils

Abstract: Preferential flow and transport through macropores affect plant water use efficiency and enhance leaching of agrochemicals and the transport of colloids, thereby increasing the risk for contamination of groundwater resources. The effects of soil compaction, expressed in terms of bulk density (BD), and organic carbon (OC) content on preferential flow and transport were investigated using 150 undisturbed soil cores sampled from 15 �� 15���m grids on two field sites. Both fields had loamy textures, but one site had significantly higher OC content. Leaching experiments were conducted in each core by applying a constant irrigation rate of 10 mm h���1 with a pulse application of tritium tracer. Five percent tritium mass arrival times and apparent dispersivities were derived from each of the tracer breakthrough curves and correlated with texture, OC content, and BD to assess the spatial distribution of preferential flow and transport across the investigated fields. Soils from both fields showed strong positive correlations between BD and preferential flow. Interestingly, the relationships between BD and tracer transport characteristics were markedly different for the two fields, although the relationship between BD and macroporosity was nearly identical. The difference was likely caused by the higher contents of fines and OC at one of the fields leading to stronger aggregation, smaller matrix permeability, and a more pronounced pipe-like pore system with well-aligned macropores.

Assessing the impacts of land use and land cover change on hydrology of watershed: a case study on Gigel-Abbay Watershed, Lake Tana Basin, Ethiopia

Dissertation submitted in partial fulfillment of the requirements for the Degree of Master of Science in Geospatial Technologies.

Long-term behaviour of railway transitions under dynamic loading application to soft soil sites

Disserta����o para obten����o do Grau de Doutor em Engenharia Civil

Fertilization and cover crop effects on soil nitrogen and plant nutrition in a young guarana plantation

Fruit tree production is gaining an increasing importance in the central Amazon and elsewhere in the humid tropics, but very little is known about the nutrient dynamics in the soil-plant system. The present study quantified the effects of fertilization and cover cropping with a legume (Pueraria phaseoloides (Roxb.) Benth.) on soil nitrogen (N) dynamics and plant nutrition in a young guarana plantation (Paullinia cupana Kunth. (H.B. and K.) var. sorbilis (Mart.) Ducke) on a highly weathered Xanthic Ferralsol. Large subsoil nitrate (NO3-) accumulation at 0.3-3 m below the guarana plantation indicated N leaching from the topsoil. The NO3- contents to a depth of 2 m were 2.4 times greater between the trees than underneath unfertilized trees (P<0.05). The legume cover crop between the trees increased soil N availability as shown by elevated aerobic N mineralization and lower N immobilization in microbial biomass. The guarana N nutrition and yield did not benefit from the N input by biological fixation of atmospheric N2 by the legume cover (P&gt;0.05). Even without a legume intercrop, large amounts of NO3- were found in the subsoil between unfertilized trees. Subsoil NO3- between the trees could be utilized, however, by fertilized guarana. This can be explained by a more vigorous growth of fertilized trees which had a larger nutrient demand and exploited a larger soil volume. With a legume cover crop, however, more mineral N was available at the topsoil which was leached into the subsoil and consequently accumulated at 0.3-3 m depth. Fertilizer additions of P and K were needed to increase subsoil NO3- use between trees.

Spatial and temporal evolution of family-farming land use in the Tapaj��s region of the Brazilian Amazon

Pressures on the Brazilian Amazon forest have been accentuated by agricultural activities practiced by families encouraged to settle in this region in the 1970s by the colonization program of the government. The aims of this study were to analyze the temporal and spatial evolution of land cover and land use (LCLU) in the lower Tapaj&#243;s region, in the state of Par&#225;. We contrast 11 watersheds that are generally representative of the colonization dynamics in the region. For this purpose, Landsat satellite images from three different years, 1986, 2001, and 2009, were analyzed with Geographic Information Systems. Individual images were subject to an unsupervised classification using the Maximum Likelihood Classification algorithm available on GRASS. The classes retained for the representation of LCLU in this study were: (1) slightly altered old-growth forest, (2) succession forest, (3) crop land and pasture, and (4) bare soil. The analysis and observation of general trends in eleven watersheds shows that LCLU is changing very rapidly. The average deforestation of old-growth forest in all the watersheds was estimated at more than 30% for the period of 1986 to 2009. The local-scale analysis of watersheds reveals the complexity of LCLU, notably in relation to large changes in the temporal and spatial evolution of watersheds. Proximity to the sprawling city of Itaituba is related to the highest rate of deforestation in two watersheds. The opening of roads such as the Transamazonian highway is associated to the second highest rate of deforestation in three watersheds.

Natural fibers for soil reinforcement

The reinforcement of soil is defined as an effective and reliable technique to improve strength and stability. For this propose, the use of natural fibers has been commonly. Over the past years, a series of studies have been performed in order to investigate the influence of randomly oriented fibers, especially for compressible clayey soils. However, less attention has been given to the reinforcing of sandy materials, as well as the use of oriented fibers meshes in order to improve mechanical behaviour. The main aim of this study is to identify the influence that different percentages of fibers, as well as the use of meshes of oriented fibers, has on soil mechanical behaviour. For this purpose, unconfined compression tests with local strain measurements were performed on a silty sand reinforced with Sisal fibers and a comparative study between randomly oriented and 0�� and 90�� fibers is presented.

DINAMICA MICROBIANA Y CALIDAD DE LA MATERIA ORGANICA DEL SUELO COMO INDICADORES DE SUSTENTABILIDAD EN EL CHACO ARIDO DE LA PROVINCIA DE CORDOBA Microbial dynamic and organic matter quality as indicators of soil sustainability in Dry Chaco of C��rdoba Province

Se propone analizar el efecto del uso productivo en el Chaco ��rido de la provincia de C��rdoba, mediante la aplicaci��n de indicadores de sustentabilidad relacionados con la calidad de la materia org��nica y la liberaci��n de nutrientes en el suelo, con la finalidad de aportar a un tema de suma interes para la provincia de C��rdoba como es la formulaci��n de criterios y pautas de manejo para la implementaci��n de la Ley de Bosques (N�� 26331). Se trabajar�� en la localidad de San Miguel en el departamento Pocho, en un sitio de bosque no disturbado y en tres sistemas productivos: desmonte selectivo con implantaci��n de pasturas; desmonte total con agricultura bajo riego y desmonte total sobrepastoreado. En cada sitio se medir�� ���in situ��� la emisi��n de CO2 y se tomaran muestras de suelo a las que se les determinar��: a) contenido de materia org��nica total (MO), b) contenido de sustancias h��micas (SH), diferenciando ��cidos h��micos (AH) y f��lvicos (AF), c) abundancia y actividad de microorganismos nitrificadores y d) propiedades qu��micas de los AH y AF. Se calcular��n los siguientes ��ndices de sustentabilidad a) materia org��nica biodisponible (MOB=MO���SH); b) ��ndice de humificaci��n (IH=SH/MO); c) tipo de humus (TH=AF/AH; d) ��ndice de mineralizaci��n de C (IMC=CO2/MO); e) ��ndice de nitrificaci��n (IN=actividad/abundancia); y f) ��ndice de estabilidad de las fracciones humificadas: compuestos arom��ticos/ alif��ticos. Los datos ser��n analizados estad��sticamente mediante ANOVA y comparaci��n de medias por LSD (P<0.05) y tests multivariados. We proposed analyze the effect of land use in Arid Chaco of Cordoba province, using sustainability indicators related to organic matter quality and nutrient release in soil, with the aim to formulate management criteria for the implementation of the Ley de Bosques (N�� 26331) in C��rdoba province. The study will be conducted in San Miguel village in Pocho department, in one undisturbed forest site and three productive systems: selective clearing with grass sowing; total clearing with irrigation agriculture and total clearing with overgrazed. In each site "in situ" CO2 emission will be measured and soil samples will be taken, in which the following parameters will be determined: a) total organic matter content (MO), b) humic substances content (SH), in humic acids (AH) and fulvic acids (AF), c) abundance and activity of nitrifier microorganisms and d) chemical properties of AH and AF. The sustainability indexes will be calculated: biodisponible organic matter (MOB=MO���SH); b) humification index (IH=SH/MO); c) humus type (TH=AF/AH; d) C mineralization index (IMC=CO2/MO); e) nitrifying index (IN=activity/abundance); and f) humic fractions stability index: aromatic/aliphatic compounds. The data will be statistically analyzed by ANOVA and the means will be compared by LSD (P<0.05) and multivariate tests.

Evaluaci��n de la degradaci��n del suelo en agroecosistemas del centro-sur de C��rdoba mediante indicadores e ��ndices. Assessment of soil degradation in agroecosystems of central-southern C��rdoba by means of indicators and indices

Las actividades agropecuarias ejercen diferentes presiones sobre los recursos naturales. Esto ha llevado, en algunas ��reas, a un deterioro del suelo que provoca un impacto sobre la sustentabilidad en los sistemas agropecuarios. Para evaluar la degradaci��n del suelo se han propuesto listas de indicadores, sin embargo, se carece de una herramienta metodol��gica robusta, adaptada a las condiciones edafoclim��ticas regionales. Adem��s, existe una demanda de productores e instituciones interesados en orientar acciones para preservar el suelo. El objetivo de este proyecto es evaluar la degradaci��n f��sica, qu��mica y biol��gica de los suelos en agroecosistemas del centro-sur de C��rdoba. Por ello se propone desarrollar una herramienta metodol��gica que consiste en un set de indicadores f��sicos, qu��micos y biol��gicos, con valores umbrales, integrados en ��ndices de degradaci��n, que asistan a los agentes tomadores de decisiones y productores, en la toma de decisiones respecto de la degradaci��n del suelo. El ��rea de trabajo ser�� una regi��n agr��cola del centro-sur de C��rdoba con m��s de 100 a��os de agricultura. La metodolog��a comienza con la caracterizaci��n del uso del territorio y sistemas de manejo, su clasificaci��n y la obtenci��n de mapas base de usos y manejos, mediante sensores remotos y encuestas. Se seleccionar��n sitios de muestreo mediante una metodolog��a semi-dirigida usando un SIG, asegurando un m��nimo de un punto de muestreo por unidad de mapeo. Se elegir��n sitios de referencia lo m��s cercano a una condici��n natural. Los indicadores a evaluar surgen de listas propuestas en trabajos previos del grupo, seleccionados en base a criterios internacionales y a adecuados a suelos de la regi��n. Se usar��n indicadores n��cleo y complementarios. Para la obtenci��n de umbrales, se usar��n por un lado valores provenientes de la bibliograf��a y por otro, umbrales generados a partir de la distribuci��n estad��stica del indicador en suelos de referencia. Para estandarizar cada indicador se definir�� una funci��n de transformaci��n. Luego ser��n ponderar��n mediante an��lisis estad��sticos mulivariados e integrados en ��ndices de degradaci��n f��sica, qu��mica y biol��gica, y un ��ndice general de degradaci��n. El abordaje concluir�� con el desarrollo de dos instrumentos para la toma de decisiones: uno a escala regional, que consistir�� en mapas de degradaci��n en base a unidades cartogr��ficas ambientales, de uso del territorio y de sistemas de manejo y otro a escala predial que informar�� sobre la degradaci��n del suelo de un lote en particular, en comparaci��n con suelos de referencia. Los actores interesados contar��n con herramientas robustas para la toma de decisiones respecto de la degradaci��n del suelo tanto a escala regional como local. Agricultural activities exert different pressures on natural resources. In some areas this has led to soil degradation and has an impact on agricultural sustainability. To assess soil degradation a robust methodological tool, adapted to regional soil and climatic conditions, is lacking. In addition, there is a demand from farmers and institutions interested in direct actions to preserve the soil. The objective of this project is to assess physical, chemical and biological soil degradation in agroecosystems of C��rdoba. We propose to develop a tool that consists of a set of physical, chemical and biological indicators, with threshold values, integrated in soil degradation indices. The study area is a region with more than 100 years of agriculture. The methodology begins with the characterization of land use and management systems and the obtaining of base maps by means of remote sensing and survey. Sampling sites will be selected through a semi-directed methodology using GIS, ensuring at least one sampling point by mapping unit. Reference sites will be chosen as close to a natural condition. The proposed indicators emerge from previous works of the group, selected based on international standards and appropriate for the local soils. To obtain the thresholds, we will use, by one side, values from the literature, and by the other, values generated from the statistical distribution of the indicator in the reference soils. To standardize indicators transformation functions will be defined. Indicators will be weighted by mans of multivariate analysis and integrated in soil degradation indices. The approach concluded with the development of two instruments for decision making: a regional scale one, consisting in degradation maps based on environmental, land use and management systems mapping units; and an instrument at a plot level which will report on soil degradation of a particular plot compared to reference soils.

Aproximaci��n al dise��o de sistemas de bio-reactores para la delignificaci��n de materiales lignocelul��sicos y para la decontaminaci��n de suelos y efluentes. Approximation to the design of bio-reactors systems for the delignificaci��n of lignocellulosic materials and for the decontamination of soil and effluents

Los materiales lignocelul��sicos residuales de las actividades agroindustriales pueden ser aprovechados como fuente de lignina, hemicelulosa y celulosa. El tratamiento qu��mico del material lignocelul��sico se debe enfrentar al hecho de que dicho material es bastante recalcitrante a tal ataque, fundamentalmente debido a la presencia del pol��mero lignina. Esto se puede lograr tambi��n utilizando hongos de la podredumbre blanca de la madera. Estos producen enzimas lignol��ticas extracelulares fundamentalmente Lacasa, que oxida la lignina a CO2. Tambien oxida un amplio rango de sustratos ( fenoles, polifenoles, anilinas, aril-diaminas, fenoles metoxi-sustitu��dos, y otros), lo cual es una buena raz��n de su atracci��n para aplicaciones biotecnol��gicas. La enzima tiene potencial aplicaci��n en procesos tales como en la delignificaci��n de materiales lignocelul��sicos y en el bioblanqueado de pulpas para papel, en el tratamiento de aguas residuales de plantas industriales, en la modificaci��n de fibras y decoloraci��n en industrias textiles y de colorantes, en el mejoramiento de alimentos para animales, en la detoxificaci��n de polutantes y en bioremediaci��n de suelos contaminados. Tambi��n se la ha utilizado en Q.Org��nica para la oxidaci��n de grupos funcionales, en la formaci��n de enlaces carbono- nitr��geno y en la s��ntesis de productos naturales complejos. HIPOTESIS: Los hongos de podredumbre blanca, y en condiciones ��ptimas de cultivo producen distintos tipos de enzimas oxidasas, siendo las lacasas las m��s adecuadas para explorarlas como catalizadores en los siguientes procesos: ��� Delignificaci��n de residuos de la industria forestal con el fin de aprovechar tales desechos en la alimentaci��n animal. ��� Decontaminaci��n/remediaci��n de suelos y/o efluentes industriales. Se realizar��n los estudios para el dise��o de bio-reactores que permitan responder a las dos cuestiones planteadas en la hip��tesis. Para el proceso de delignificaci��n de material lignocelul��sico se proponen dos estrategias: 1- tratar el material con el micelio del hongo adecuando la provisi��n de nutrientes para un desarrollo sostenido y favorecer la liberaci��n de la enzima. 2- Utilizar la enzima lacasa parcialmente purificada acoplada a un sistema mediador para oxidar los compuestos polifen��licos. Para el proceso de decontaminaci��n/remediaci��n de suelos y/o efluentes industriales se trabajar�� tambi��n en dos frentes: 3) por un lado, se ha descripto que existe una correlaci��n positiva entre la actividad de algunas enzimas presentes en el suelo y la fertilidad. En este sentido se conoce que un sistema enzim��tico, tentativamente identificado como una lacasa de origen microbiano es responsable de la transformaci��n de compuestos org��nicos en el suelo. La enzima protege al suelo de la acumulaci��n de compuestos org��nicos peligrosos catalizando reacciones que involucran degradaci��n, polimerizaci��n e incorporaci��n a complejos del ��cido h��mico. Se utilizar��n suelos incorporados con distintos polutantes(por ej. policlorofenoles �� cloroanilinas.) 4) Se trabajar�� con efluentes industriales contaminantes (alpech��nes y/o el efluente l��quido del proceso de desamargado de las aceitunas). The lignocellulosic raw materials of the agroindustrial activities can be taken advantage as source of lignin, hemicellulose and cellulose. The chemical treatment of this material is not easy because the above mentioned material is recalcitrant enough to such an assault, due to the presence of the lignin. This can be achieved also using the white-rot fungi of the wood. It produces extracellular ligninolitic enzymes, fundamentally Laccase, which oxidizes the lignin to CO2. The enzyme has application in such processes as in the delignification of lignocellulosic materials and in the biobleaching of fibers for paper industry, in the treatment of waste water of industrial plants, in the discoloration in textile industries, in the improvement of food for ruminants, in the detoxification of polutants and in bioremediation of contaminated soils. HYPOTHESIS: The white-rot fungi produce different types of enzymes, being the laccases the most adapted to explore them as catalysts in the following processes: ��� Delignification of residues of the forest industry in order to take advantage of such waste in the animal feed. ��� Decontamination of soils and / or waste waters. The studies will be conducted for the design of bio reactors that allow to answer to both questions raised in the hypothesis. For the delignification process of lignocellulosic material they propose two strategies: 1- to treat the material with the fungi 2-to use the partially purified enzyme to oxidize the polyphenolic compounds. For the soil and/or waste water decontamination process, we have: 3- Is know that the enzyme protects to the soil of the accumulation of organic dangerous compounds catalyzing reactions that involve degradation, polymerization and incorporation to complexes of the humic acid. There will be use soils incorporated into different pollutants. 4- We will work with waste waters (alpechins or the green olive debittering effluents.