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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
211

Integrating Livestock And Winter Annual Forages Into A No-Till Corn Silage System

Stefani Faé, Giovani 08 December 2008 (has links)
No description available.
212

Συνθήκες ιζηματογένεσης και παλαιογεωγραφική εξέλιξη των ιζημάτων της τομής Μακρυλιά στη λεκάνη της Ιεράπετρας στην Κρήτη

Μόφορης, Λεωνίδας 11 October 2013 (has links)
Η λεπτομερής ιζηματολογική ανάλυση των αποθέσεων της τομής Μακρυλιά, έδειξε την ύπαρξη τουλάχιστον 5 κύκλων ιζηματογένεσης με αυξανόμενο προς τα πάνω κοκκομετρικό μέγεθος που αναπτύχτηκαν σε ένα περιβάλλον υφαλοκρηπίδας. Η κύρια λιθολογία είναι αμμούχος πηλός και τα ιζήματα μεταφέρθηκαν ως ομογενές αιώρημα. Το ποσοστό του ανθρακικού ασβεστίου είναι χαμηλό και τείνει αυξανόμενο προς τα πιο αδρομερή κλάσματα. Το ποσοστό του οργανικού υλικού έδειξε την παρουσία αρκετών δειγμάτων με αυξημένο οργανικό υλικό προτείνοντας την ύπαρξη εν δυνάμει μητρικών πετρωμάτων για την γένεση υδρογονανθράκων. Η σχέση μεταξύ του ανθρακικού ασβεστίου και οργανικού υλικού είναι κύρια αρνητική προτείνοντας ανοξικές συνθήκες. Η βιοστρωματογραφική ανάλυση έδειξε Πλειοκαινική ηλικία των ιζημάτων που αποτέθηκαν σε εναλλασσόμενες οξικές – ανοξικές συνθήκες. Από τα παραπάνω αποτελέσματα και περνώντας υπόψη τα υπάρχοντα αποτελέσματα των ιζημάτων που περιβάλλουν την περιοχή μελέτης φαίνεται πως οι μελετηθείσες αποθέσεις συγκεντρώθηκαν σε μια ρηχή με ήσυχα νερά ενδο-ορεινή λεκάνη στα περιθώρια της κύριας λεκάνης της Ιεράπετρας. / Detailed sedimentological analysis, in Makrylia cross-section deposits, showed at least five coarsening-upward cycles developed in a shelf environment. The main lithology is sandy silt and sediments transported as homogenous suspension in a low energy environment that deposited in a shallow water basin. Calcium carbonate (CaCO3) is low and tends to increase to the coarse-grained clasts. Organic carbon (TOC) ratio showed the presence of many high content samples in TOC suggesting potential hydrocarbon source rocks. There is mostly a negative relation between CaCO3 and TOC introducing generally anoxic conditions. Biostratigraphy analysis showed a Pliocene age for the studied deposits in alternating conditions with oxic- anoxic events. According to the above results and taking into account previous results from the surrounding sediments it seems that studied deposits accumulated in a shallow, low energy, intra-mountain basin at the margins of the main Ierapetra basin.
213

Organinių mulčių liekamasis poveikis dirvožemio biologinėms savybėms ekologinėje žemdirbystės sistemoje / The Residual Effect of Organic Mulches on Soil Biological Properties in Organic Farming System

Bartkevičius, Gediminas 03 June 2011 (has links)
Dviejų veiksnių eksperimentas atliktas 2010 m. Lietuvos žemės ūkio universiteto Pomologiniame sode. Dirvožemis – karbonatingas giliau glėjiškas ištplaužemis – Calc(ar)i-Endohypgleyic Luvisol. Eksperimento variantai: Veiksnys A – mulčiai: 1) nemulčiuota; 2) smulkinti žieminių kviečių šiaudai; 3) žemapelkių durpės; 4) šviežios pjuvenos; 5) smulkinta vejų žolė. Veiksnys B – mulčio sluoksnio storis: 1) 5 cm; 2) 10 cm. Tyrimų tikslas – įvertinti įvairių organinių mulčių ir jų skirtingo storio sluoksnio liekamąjį poveikį dirvos biologinėms savybėms. Įvairių organinių mulčių naudojimas turėjo liekamąjį poveikį sliekų skaičiui ir masei. Laukeliuose, kurie buvo mulčiuoti žole, nustatytas esmingai didesnis sliekų skaičius ir masė, palyginus su nemulčiuotais. Sliekų masė buvo esmingai mažesnė 10 cm storio mulčio sluoksniu 2004–2009 m. mulčiuotuose laukeliuose palyginus su 5 cm storio sluoksniu mulčiuotais laukeliais. Nustatytas liekamasis organinių mulčių poveikis dirvožemio fermentų sacharazės ir ureazės aktyvumui. Didžiausią teigiamą ir esminį liekamąjį poveikį sacharazės aktyvumui turėjo žolės mulčias. Didžiausią teigiamą liekamąjį poveikį ureazės aktyvumui darė mulčiavimas pjuvenomis ir žole. Mulčio sluoksnio storinimas turėjo tendenciją didinti ureazės aktyvumą. Durpių ir pjuvenų mulčiai turėjo teigiamą esminį liekamąjį poveikį organinės anglies kiekiui dirvožemyje. Mulčio sluoksnio storio poveikis taip pat esminis. Didžiausią teigiamą esminį liekamąjį poveikį svogūnų derliui... [toliau žr. visą tekstą] / Experiment was carried out at the Pomological Garden of Lithuanian University of Agriculture. The soil type – Calc(ar)i–Endohypogleyic Luvisol. The residual effect of organic mulches on earthworm population was investigated in 2010. The influence of different organic mulches on agrocenosis was investigated in 2004–2009. Scheme of the experiment: Factor A – mulches: 1) no mulching; 2) winter wheat straw; 3) peat; 4) sawdust; 5) grass. Factor B – thickness of mulch layer: 1) 5 cm; 2) 10 cm. The aim of this investigation was to evaluate the residual effect of different organic mulches and different thickness of mulch layer on earthworm population. The residual effect of different organic mulches on amount and mass of earthworms was established. Amount and mass of earthworms in plots which were mulched with grass was significantly highercompared with plots without mulch. Significantly lower mass of earthworms was established in plots mulched with 10 cm layer of mulch in 2004–2009 compared with plots mulched with 5 cm layer of mulch. The residual effect of organic mulches on the activity of soil enzymes saccharase and urease was established. Grass mulch has the greatest positive and signifficant residual effect on saccharase activity. Mulching with sawdust and grass has the greatest residual effect on activity of urease. Tendency of stronger effect of the thicker mulch layer on urease activity was established. Peat and sawdust mulches significantly positively affected the amount... [to full text]
214

Biologically relevant characteristics of dissolved organic carbon (DOC) from soil

Bowen, Susan January 2006 (has links)
Of the organic matter in soils typically < 1% by weight is dissolved in the soil solution (dissolved organic matter; DOM). DOM is a continuum of molecules of various sizes and chemical structures which has largely been operationally defined as the fraction of total organic carbon in an aqueous solution that passes through a 0.45 µm filter. Although only representing a relatively small proportion, it represents the most mobile part of soil organic carbon and is probably enriched with highly labile compounds. DOM acts as a source of nutrients for both soil and aquatic micro-organisms, influences the fate and transport of organic and inorganic contaminants, presents a potential water treatment problem and may indicate the mobilisation rate of key terrestrial carbon stores. The objective of this research was to ascertain some of the biologically relevant characteristics of soil DOM and specifically to determine: (1) the influence of method and time of extraction of DOM from the soil on its biochemical composition and concentration; (2) the dynamics of DOM biodegradation; and, (3) the effects of repeated applications of trace amounts of DOM on the rate of soil carbon mineralization. To examine the influence of method and time of extraction on the composition and concentration of DOM, soil solution was collected from a raised peat bog in Central Scotland using water extraction, field suction lysimetry, and centrifugation techniques on a bimonthly basis over the period of a year (Aug 2003 – Jun 2004). Samples were analysed for dissolved organic carbon (DOC), dissolved organic nitrogen (DON), protein, carbohydrate and amino acid content. For all of the sampled months except June the biochemical composition of DOC varied with extraction method, suggesting the biological, chemical and/or physical influences on DOC production and loss are different within the differently sized soil pores. Water-extractable DOC generally contained the greatest proportion of carbohydrate, protein and/or amino acid of the three extraction methods. Time of extraction had a significant effect on the composition of water- and suction-extracted DOC: the total % carbohydrate + protein + amino acid C was significantly higher in Oct than Dec, Feb and Jun for water-extracted DOC and significantly greater in Dec than Aug, Apr and Jun for suction-extracted DOC. There was no significant change in the total % carbohydrate + protein + amino acid C of centrifuge-extracted DOC during the sampled year. Time of extraction also had a significant effect on the % protein + amino acid N in water- and centrifuge-extracted DON: Oct levels were significantly higher than Feb for water-extracted DON and significantly higher in Aug and Apr for centrifuge-extracted DON. Concentrations of total DOC and total DON were also found to be dependent on time of extraction. DOC concentrations showed a similar pattern of variation over the year for all methods of extraction, with concentrations relatively constant for most of the year, rising in April to reach a peak in Jun. DON concentrations in water- and centrifuge-extracted DON peaked later, in Aug. There were no significant seasonal changes in the concentration of suction-extracted DON. A lack of correlation between DOC and DON concentrations suggested that DOC and DON production and/or loss are under different controls. Laboratory-based incubation experiments were carried out to examine the dynamics of DOC biodegradation. Over a 70 day incubation period at 20oC, the DOM from two types of peat (raised and blanket) and four samples of a mineral soil (calcaric gleysol), each previously exposed to a different management strategy, were found to be comprised of a rapidly degradable pools (half-life: 3 – 8 days) and a more stable pool (half-life: 0.4 to 6 years). For all soil types/treatments, excepting raised peat, the total net loss of DOC from the culture medium was greater than could be accounted for by the process of mineralization alone. A comparison between net loss of DOC and loss of DOC to CO2 and microbial biomass determined by direct microscopy suggested that at least some of the differences between DOC mineralised and net DOC loss were due to microbial assimilation and release. Changes in the microbial biomass during the decomposition process showed proliferation followed by decline over 15 days. The protein and carbohydrate fractions showed a complex pattern of both degradation and production throughout the incubation. The effects of repeated applications of trace amounts of litter-derived DOC on the rate of carbon mineralization over a 35 day period were investigated in a laboratory based incubation experiment. The addition of trace amounts of litter-derived DOC every 7 and 10.5 days appeared to ‘trigger’ microbial activity causing an increase in CO2 mineralisation such that extra C mineralised exceeded DOC additions by more than 2 fold. Acceleration in the rate of extra C mineralised 7 days after the second addition suggested that either the microbial production of enzymes responsible for biodegradation and/or an increase in microbial biomass, are only initiated once a critical concentration of a specific substrate or substrates has been achieved. The addition of ‘DOC + nutrients’ every 3.5 days had no effect on the total rate of mineralization. To date DOC has tended to be operationally defined according to its chemical and physical properties. An understanding of the composition, production and loss of DOC from a biological perspective is essential if we are to be able to predict the effects of environmental change on the rate of mineralization of soil organic matter. This research has shown that the pools of DOC extracted, using three different methods commonly used in current research, are biochemically distinct and respond differently to the seasons. This suggests some degree of compartmentalisation of biological processes within the soil matrix. The observed similarities between the characteristics of the decomposition dynamics of both peatland and agricultural DOC suggests that either there is little difference in substrate quality between the two systems or that the microbial community have adapted in each case to maximise their utilisation of the available substrate. The dependency of the concentration and biochemical composition of DOC on the seasons requires further work to ascertain which biotic and/or abiotic factors are exerting control. Published research has focussed on factors such as temperature, wet/dry cycles, and freeze/thawing. The effect of the frequency of doses of trace amounts of DOC on increasing the rate of soil organic C mineralization, evident from this research, suggests that the interval between periods of rainfall may be relevant. It also emphasises how it can be useful to use knowledge of a biological process as the starting point in determining which factors may be exerting control on DOC production and loss.
215

Patterns and drivers of riverine particulate organic carbon transport in an Andean valley

Clark, Kathryn Elizabeth January 2014 (has links)
Physical erosion can mobilise particulate organic carbon (POC) from vegetation and soil, representing an export of primary productivity from ecosystems, and a lateral transfer of carbon recently-derived from the atmosphere. These carbon transfers are thought to be enhanced in mountain forests where erosion rates are high. However, the rates and controls on POC transfer remain poorly constrained, as does the impact of POC export on carbon cycling at regional and global scales. This thesis takes an interdisciplinary approach to address this issue, using remote sensing, river geochemistry, river hydrology, and geomorphic mapping in the Kosñipata Valley, in the Central Andes of Peru. Its main aims are to: 1) estimate stream discharge throughout the year and to evaluate the water balance and sources; 2) quantify the source of riverine POC, accounting for POC derived from sedimentary rocks (POC<sub>fossil</sub>) to examine the POC eroded from soils and vegetation (POC<sub>non-fossil</sub>); 3) quantify river POC yields; 4) assess the hillslope processes that erode POC; and 5) assess how POC export impacts the carbon balance of mountain forest, and how fluvial transfer impacts the wider carbon cycle. Stream flow was monitored from January 2010 to February 2011 at two newly installed river gauging stations in the Kosñipata Valley at 2250 m (Wayqecha, 48.5 km<sup>2</sup>) and 1360 m (San Pedro, 164.4 km<sup>2</sup>). Then annual water balance for the San Pedro catchment was quantified. Rainfall inputs of 3028 mm and cloud water inputs of 308 ± 97 mm were balanced by outputs via stream runoff (2721 mm) and actual evapotranspiration (907 mm), leaving a residual of -294 ± 97 mm (< ~10 % of water inputs). The source of POC in river suspended sediment samples was quantified using radiocarbon (Δ<sup>14</sup>C, ‰), stable carbon isotopes, and the nitrogen to carbon ratio. This revealed that river POC<sub>non-fossil</sub> was sourced from very young organic carbon in the valley (Δ<sup>14</sup>C ~50 ‰) and that POC<sub>fossil</sub> comprised 43 % of total POC. Combining the hydrometric measurements with river samples, annual particulate load fluxes were quantified. The vast majority (73 % to 77 %) of the annual suspended sediment transfer and POC (both POC<sub>fossil</sub> and POC<sub>non-fossil</sub>) occurred in the wet season over a period of 4 months. The suspended sediment yield for the valley (960 – 1200 t km<sup>-2</sup> yr<sup>-1</sup>) was consistent with those for the Andean portion of the Madre de Dios River into which the Kosñipata River drains. The river POC<sub>non-fossil</sub> yield was 5.2 – 6.9 tC km<sup>-2</sup> yr<sup>-1</sup>. Landslides are likely to have played an important role in the mobilisation of POC<sub>non-fossil</sub>. A detailed landslide mapping using 25 years of remote sensing data revealed that on average 0.09 % of the valley per year is impacted by this mass-wasting process. These landslides mobilise ~28 tC km<sup>-2</sup> yr<sup>-1</sup> of soil and vegetation valley-wide. The discrepancy between the landslide erosional flux and fluvial POCnon-fossil export suggests an important fraction of the POCnon-fossil harvested by landslides is either exported as coarse debris (not quantified in the fluvial POC<sub>non-fossil</sub> flux), remains buried onsite, or is degraded and respired onsite. Landslides also played an important ecosystem function, turning over some sections of the mountain forest within ~625 years, with a 1200 year valley-wide mean. On the basin scale, the Madre de Dios River drains ~ 6 % of the Amazonian Andes. This study enables estimation of the delivery of POC to the lowland Amazon Basin. Using the observation that POC<sub>non-fossil</sub> and POC<sub>fossil</sub> fluxes were closely linked with suspended sediment transfer, total yields of ~0.22 MtC yr<sup>-1</sup> and ~0.17 MtC yr<sup>-1</sup>, respectively, were estimated from this section of the Andes. The export of POC<sub>non-fossil</sub> from mountain forests by rivers represents 0.4 – 1.0 % yr<sup>-1</sup> of the net primary productivity of Andean forest and so even if only a small portion of this is buried in sedimentary deposits, it may promote the Andes as a carbon sink. These results demonstrate the long-term influence of erosional processes in the cycling of carbon in the Amazon Basin.
216

High-resolution mapping and spatial variability of soil organic carbon storage in permafrost environments

Siewert, Matthias Benjamin January 2016 (has links)
Large amounts of carbon are stored in soils of the northern circumpolar permafrost region. High-resolution mapping of this soil organic carbon (SOC) is important to better understand and predict local to global scale carbon dynamics. In this thesis, studies from five different areas across the permafrost region indicate a pattern of generally higher SOC storage in Arctic tundra soils compared to forested sub-Arctic or Boreal taiga soils. However, much of the SOC stored in the top meter of tundra soils is permanently frozen, while the annually thawing active layer is deeper in taiga soils and more SOC may be available for turnover to ecosystem processes. The results show that significantly more carbon is stored in soils compared to vegetation, even in fully forested taiga ecosystems. This indicates that over longer timescales, the SOC potentially released from thawing permafrost cannot be offset by a greening of the Arctic. For all study areas, the SOC distribution is strongly influenced by the geomorphology, i.e. periglacial landforms and processes, at different spatial scales. These span from the cryoturbation of soil horizons, to the formation of palsas, peat plateaus and different generations of ice-wedges, to thermokarst creating kilometer scale macro environments. In study areas that have not been affected by Pleistocene glaciation, SOC distribution is highly influenced by the occurrence of ice-rich and relief-forming Yedoma deposits. This thesis investigates the use of thematic maps from highly resolved satellite imagery (&lt;6.5 m resolution). These maps reveal important information on the local distribution and variability of SOC, but their creation requires advanced classification methods including an object-based approach, modern classifiers and data-fusion. The results of statistical analyses show a clear link of land cover and geomorphology with SOC storage. Peat-formation and cryoturbation are identified as two major mechanisms to accumulate SOC. As an alternative to thematic maps, this thesis demonstrates the advantages of digital soil mapping of SOC in permafrost areas using machine-learning methods, such as support vector machines, artificial neural networks and random forests. Overall, high-resolution satellite imagery and robust spatial prediction methods allow detailed maps of SOC. This thesis significantly increases the amount of soil pedons available for the individual study areas. Yet, this information is still the limiting factor to better understand the SOC distribution in permafrost environments at local and circumpolar scale. Soil pedon information for SOC quantification should at least distinguish the surface organic layer, the mineral subsoil in the active layer compared to the permafrost and further into organic rich cryoturbated and buried soil horizons. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.</p>
217

Upřesnění sekvestrace uhlíku v půdě v severní části Českého krasu / Soil carbon sequestration in northern part of Czech karst

Polická, Petra January 2014 (has links)
Due to climate change there is a growing concern for soil organic carbon reservoires. The soil is the largest terrestrial pool of organic carbon and its balance is being increasingly disturbed by conversion of natural to managed ecosystem (for agriculture, forestry and urbanization). There are still large uncertainities with estimating real amount of organic carbon sequestrated in soils. Therefore a number of regional and national soil inventories and monitoring networks are currently established or tested to verify soil carbon changes. Thesis is focused on estimation of soil organic carbon pools in the area of Czech basic map Beroun 12-41-08. It evaluates available soil data and restrictions of their use. Especially is focused on comprehensive soil survey undertaken between 1961 and 1970, on soil properties change in time and how to get missing bulk densities of the soil, particularly through pedotransfer functions. Powered by TCPDF (www.tcpdf.org)
218

Porovnání různých způsobů frakcionace půdní organické hmoty / Comparison of two methods of soil organic matter fractionantion

Fryčová, Kateřina January 2012 (has links)
Comparison of two different soil organic matter fractionation methods Soil organic matter (SOM) significantly affects physical, chemical and biological properties of soils and plays also a crucial role in the global carbon cycle. In order to simulate SOM dynamics a number of mathematical models have been developed. These models divide SOM into several theoretical pools according to their stability. Unfortunately, lacking experimental procedure which could measure these pools directly, although for this purpose a wide range of fractionation procedures were developed, that are trying identified empirical fractions with theoretical model pools. An objective of this experiment was to reproduce two fractionation procedures on a set of twenty-seven laboratory-prepared samples: according to Six and according to Zimmermann and to compare their results. Also the relationship between respiration and the amount of carbon in different pools was compared. The most significant differences were found in active pools, where Six's method found twice as much carbon than Zimmermann's one. Finally response of both method results to various environmental parameters (mineral composition, litter type and soil mixing) was compared. According to the results of Zimmermann's method the amount of carbon in different pools was mainly...
219

Comportamento de sistemas pós-filtros adsorvedores na remoção de compostos orgânicos precursores e subprodutos da desinfecção. / Behavior of post-filter adsorbers in the removal of organic precursors and disinfection byproducts.

Pereira, Claudia Mota Santos 14 August 2009 (has links)
O presente trabalho teve como objetivo avaliar a eficiência de pós-filtros adsorvedores constituídos de Carvão Ativado Granular (CAG) na remoção de compostos orgânicos precursores e na formação de subprodutos da desinfecção, em particular dos trialometanos (THM) na Estação de Tratamento de Água Alto da Boa Vista (ETA ABV), abastecida por reservatórios de água bruta com elevado grau de eutrofização. Os ensaios foram conduzidos em ETA Piloto composta por tanque de reservação de água filtrada, ozonizador, tanque de reservação de água ozonizada e 4 pós-filtros adsorvedores, sendo duas unidades dotadas de CAG de origem mineral e duas unidades dotadas de CAG de origem vegetal. Os filtros foram operados em paralelo, sendo que duas colunas foram alimentadas com água filtrada da ETA ABV (Filtro F3 CAG de origem mineral e Filtro F4 CAG de origem vegetal) e as outras duas alimentadas com água filtrada e ozonizada (Filtro F1 CAG de origem mineral e Filtro F2 CAG de origem vegetal). A avaliação da remoção de compostos orgânicos precursores e formação de subprodutos da desinfecção foi feita através de análises de carbono orgânico total (COT), UV-254 nm e formação de THM. A análise dos resultados gerados de julho de 2007 a dezembro de 2008 permitiu concluir que 93% do THM é formado nas primeiras 24 horas de contato da amostra com o cloro, simulando a pós cloração e pós alcalinização da ETA ABV. O processo de oxidação por ozônio não foi efetivo na remoção de THM instantâneo, visto que a média dos 38 valores de THM instantâneo para a água filtrada (17,8 ± 5,6 g/L) foi igual a média obtida para o THM instantâneo na água ozonizada. A remoção de THM pelos filtros de CAG foi mais significativa nos primeiros três meses de operação do sistema, apresentando remoção de 80% para os filtros com CAG de origem mineral e 70% para os filtros com CAG de origem vegetal, a partir do quarto mês de operação do sistema a remoção de THM caiu para um valor médio de 34%, o que mostra uma iminente saturação do leito adsorvedor. Os pós-filtros adsorvedores constituídos de CAG de origem mineral apresentaram melhor comportamento com respeito a remoção de THM e COT quando comparado com os pós-filtros dotados de CAG de origem vegetal. / The main purpose of this work was to evaluate the performance of a Granular Activated Carbon (GAC) post-filter adsorbers in the removal of organic precursors and in the formation of disinfection byproducts, especially trihalomethanes (THM) in Alto da Boa Vista Water Treatment Plant (ABV WTP), which takes raw water from a highly eutrophized reservoirs. The tests was conducted on a Pilot WTP composed of filtered water tank, ozonator, ozonized water tank, and four post-filter adsorbers: two units with mineral GAC media and two units with vegetal GAC media. The filters were operated in parallel, with two columns fed with filtered water from ABV WTP (F3 Filter mineral GAC and F4 Filter vegetal GAC) and the other fed with ozonized water (F1 Filter mineral GAC and F2 Filter vegetal GAC). The evaluation of the removal of organic precursors and the formation of disinfection byproducts was made through analysis of Total Organic Carbon (TOC), UV-254 nm and THM formation. The results generated from July 2007 to December 2008 showed that 93% of THM is formed in the first 24 hours of contact with the chlorine in the sample, simulating the post chlorination and post alkalinization of ABV WTP in samples of filtered water, ozonized water, and post-filter adsorbers effluent. Ozone oxidation process was not effective in removing THM. Was found the same instantaneous THM values in the filtered water (17.8 g/L± 5.6 g/L) and in the ozonized water. During the first three months of post-filter adsorber operation, THM removal efficiencies were around 80% for F1 and F3 (mineral GAC media) and around 70% for F2 and F4 (vegetal GAC media). After four months of operation, THM removal efficiencies decreased to 34% average value, thus indicative of GAC saturation. Regarding THM and TOC removal efficacy, the mineral GAC performed better than the vegetal GAC.
220

Sorção/dessorção e lixiviação do herbicida ametrina em solos canavieiros tratados com lodo de esgoto / Sorption/desorption and leaching of the herbicide ametryne in soils cultivated with sugar cane and amended with sewage sludge

Marchese, Luciana 31 July 2007 (has links)
Vários estudos têm mostrado os benefícios da aplicação agronômica de lodo de esgoto sobre as propriedades físicas e químicas do solo. No entanto, poucos são aqueles que avaliam o impacto desta prática sobre o comportamento de pesticidas em solos tropicais. O principal objetivo deste estudo foi avaliar o efeito da adição de diferentes fontes de lodo (Ribeirão Preto, Franca e Jundiaí) na sorção / dessorção e lixiviação do herbicida ametrina em solos canavieiros do estado de São Paulo (Neossolo Quartzarênico Órtico Típico (RQ), Latossolo Vermelho Distrófico Típico (LVd), Argissolo Vermelho Eutroférrico Chernossólico (PV) e Latossolo Vermelho Distroférrico (LVdf). Cinco concentrações (de 4,4 a 79,8 mg i.a. L-1) do herbicida foram utilizadas para obter os valores dos coeficientes de sorção de Freündlich (Kf) e dos coeficientes aparentes de sorção médio e para a menor concentração (Kd ap médio e Kd ap [menor]), a qual corresponde à dose de campo recomendada. Para o teste de lixiviação, o método utilizado foi o de lixiviação em colunas de solo (diâmetro = 5 cm e comprimento = 30 cm), utilizando-se três repetições para cada tratamento, sobre as quais foi simulada chuva de 200 mm uniformemente distribuídas durante 48 h, após a aplicação da solução de 14Cametrina na dose de 3,0 kg i.a. ha-1. De forma geral, a sorção da ametrina variou de moderada à alta em todos os tratamentos (2,68 < Kd ap [menor] < 85,71 L kg-1). Solos argilosos com maior teor de matéria orgânica e argilas do tipo 2:1, como é o caso do PV, apresentaram muito maior potencial de sorção da ametrina; enquanto que solos arenosos com baixos teores de matéria orgânica, como foram os casos do LVd e RQ, apresentaram moderado potencial de sorção. A aplicação de lodos menos estabilizados, com biomassa e material orgânico menos recalcitrante e, portanto, com maiores valores de carbono orgânico total, carbono orgânico dissolvido e pH, como é o caso do lodo de Ribeirão Preto, tendeu a diminuir o potencial de sorção da ametrina. Já a adição de lodos mais recalcitrantes, como o de Jundiaí, tendeu a aumentar o potencial de sorção da ametrina, principalmente em solos arenosos devido a sua menor capacidade tampão. Nestes cenários, poderá ocorrer redução da eficácia agronômica ametrina, uma vez que haverá menos produto disponível na solução do solo. A ametrina apresentou baixo potencial de lixiviação (< 1% da quantidade aplicada) em todos os tratamentos, os quais não apresentaram diferenças entre si, sendo que a grande maioria do pesticida (> 95% da quantidade aplicada) ficou retida na camada de 0-10 cm de profundidade da coluna de solo. Isto implica dizer que a ametrina apresenta baixo potencial de contamina águas subterrâneas, mesmo em solos arenosos, como RQ (90% de areia) / Several studies have shown the benefits of applying sewage sludge on the physical and chemical properties of the soils. However, just a few of them evaluates the impact of this practice on the behavior of pesticides in tropical soils. The main goal of this research was to evaluate the effects of applying different sources of sewage sludge (Ribeirão Preto, Franca e Jundiaí) on the sorption / desorption and leaching of ametryne in soils from São Paulo state (Brazil) cultivated with sugarcane (Neossolo Quartzarênico Órtico Típico (RQ), Latossolo Vermelho Distrófico Típico (LVd), Argissolo Vermelho Eutroférrico Chernossólico (PV) e Latossolo Vermelho Distroférrico (LVdf). Five concentrations (4.4 to 79.8 mg a.i. ha-1) of the herbicide were applied to the soil samples to attain the Freündlich sorption coefficients (Kf) and the apparent sorption coefficient for the lower concentration (Kd ap [menor]), which corresponded to the field application rate. For the leaching test the adopted method was the soil leaching columns (diameter = 5 cm and depth = 30 cm), in triplicates, over which a 200 mm rainfall evenly distributed during 48 h was simulated just after ametryne application at the rate of 3.0 kg a.i. ha-1. In general, ametryne sorption ranged from moderate to high in all treatments (2.68 < Kd ap [menor] < 85.71 L kg-1). Clay soils with higher organic matter and 2:1 clay contents, such as the PV, showed much higher sorption potential, whereas sand soils with low organic matter content, such as LVd and RQ, showed moderate sorption potential. The application of less stabilized sewage sludges, with less recalcitrant biomass and organic material and, therefore, with higher organic matter and dissolved organic carbon contents and pH values, such as the Ribeirão Preto, tends to decrease ametryne sorption potential. Otherwise, the addition of more recalcitrant sludges, such as the Jundiaí, tends to enhance its sorption potential, mainly in sand soils due to its lower buffer capacity. In those cases, the agronomic efficacy of ametryne may be reduced since there is lower concentration of the compound available in the soil solution. The ametryne presented low leaching potential in all treatments (< 1% of the applied amount), which were not different among themselves, and that its majority (> 95% of the applied amount) was found at 0 -10 cm soil depth in the column. It implies that ametryne has low potential to contaminate groundwater even in sandy soils, such as the RQ (90% sand)

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