Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / The understanding of processes such as the generation of surface runoff, sediment yield and their relations with the rainfall regime is the basis for the planning and effective management of soil and water resources in a watershed. In this context, the present study aims to identify the main processes that influence the generation of surface runoff and sediment yield in small watersheds, and determine parameters for empirical sedimentological models, as well as the Sediment Delivery Ratio (SDR) for the tropical, semi-arid region of Brazil. The study area is the Iguatu Experimental Basin (IEB), which comprises a watershed of 16.74 km2, three small nested watersheds (from 1 to 3 ha) and three erosion plots of 20 m2. One of the watersheds had been under regenerating Caatinga for 35 years, another subjected to a management, which involved thinning the Caatinga, and the last faced deforestation followed by burning and the cultivation of grass. The period of study was six years (2009 to 2014). Collections to quantify surface runoff and sediment yield were taken for each erosive rainfall event in an accumulated period of 24 hours. Surface runoff in the watersheds was quantified using Parshall flumes, and sediment yield was measured with towers and trenches to collect suspended sediment and bedload. On the watershed scale, runoff was measured by means of a spillway, and sediment yield by a turbidimeter. Cluster analysis was used to determine rainfall regimes and groups of similar rainfall-runoff events. With data from the erosion plots and watersheds, the C factors and coefficients of the Modified Universal Soil Loss Equation (MUSLE) were calibrated and validated. From data measured in the basin, sediment delivery ratios were determined. The occurrence of dry spells and the formation of cracks in the soil were important factors in controlling the generation of runoff and consequently sediment yield. The dry spells made it possible for the soil to dry out, with the formation of cracks, which acted as pathways for preferential flow, generating higher initial abstraction during the start of the rainy season. Changes in ground cover had little influence on accumulated flow, demonstrating that the soil characteristics and conditions as moisture and the presence of cracks, best explain the generation of runoff on expansive soils. The greatest runoff losses in all the watersheds under study were for Rainfall Regime II, characterized by higher depth, intensity and occurrence of the rainfall. For the ground covers under study, values for the C factors and the fit of the coefficients "a" and "b" of MUSLE, proved to be appropriate and recommended according to the statistical indices employed. Values for sediment delivery ratio for individual rainfall events ranged from 0.08 to 1.67%, with an average of 0.68%. In the basin, extreme events may cause high disaggregation of soil particles, but without sufficient transporting energy for dragging the sediment, generating low SDR. / O entendimento de processos como geraÃÃo do escoamento superficial, produÃÃo de sedimentos e suas relaÃÃes com o regime pluviomÃtrico à a base para o planejamento e a gestÃo eficaz dos recursos solo e Ãgua em uma bacia hidrogrÃfica. Nesse contexto, o presente estudo tem como objetivos identificar os principais processos que influenciam a geraÃÃo do escoamento superficial e a produÃÃo de sedimento em pequenas bacias hidrogrÃficas, e calibrar parÃmetros de modelos sedimentolÃgicos empÃricos, bem como a razÃo de aporte de sedimentos (SDR) para a regiÃo semiÃrida tropical do Brasil. A Ãrea de estudo à a Bacia Experimental de Iguatu (BEI), composta de uma bacia de 16,74 km2, trÃs pequenas microbacias aninhadas (de 1 a 3 ha) e trÃs parcelas de erosÃo de 20 m2. Uma das microbacias foi mantida com Caatinga em regeneraÃÃo hà 35 anos, outra submetida ao manejo de raleamento da Caatinga e na Ãltima foi realizado o desmatamento seguido de queimada e cultivo de capim. O perÃodo de estudo foi de seis anos (2009 a 2014). As coletas para quantificaÃÃo do escoamento superficial e da produÃÃo de sedimentos foram realizadas a cada evento de chuva erosiva, no acumulado de 24 horas. O escoamento superficial nas microbacias foi quantificado atravÃs de calhas Parshall e as produÃÃes de sedimentos foram mensuradas atravÃs de torres e fossos coletores de sedimentos em suspensÃo e arraste. Na bacia de 16,74 km2, o escoamento superficial foi mensurado por meio de um vertedor e a produÃÃo de sedimentos atravÃs de um turbidÃmetro. AnÃlises de agrupamento foram utilizadas para determinaÃÃo de regimes de chuvas e grupos de eventos similares de chuva-deflÃvio. Com dados das parcelas de erosÃo e das microbacias foram calibrados e validados os fatores C e os coeficientes da EquaÃÃo Universal de Perdas de Solo Modificada (MUSLE). A partir dos dados medidos na bacia foram determinadas as razÃes de aporte de sedimentos. A ocorrÃncia de veranicos e a formaÃÃo de fendas no solo foram determinantes no controle da geraÃÃo de escoamento e consequentemente da produÃÃo de sedimentos. A ocorrÃncia de veranicos possibilitou o secamento do solo com a formaÃÃo de fendas, que agem como caminhos preferenciais para o fluxo de Ãgua, gerando elevadas abstraÃÃes inicias durante o inÃcio da estaÃÃo chuvosa. As mudanÃas da cobertura vegetal apresentaram pouca influÃncia sobre o escoamento acumulado, indicando que as caracterÃsticas e condiÃÃes do solo, como umidade e presenÃa de fendas, explicam melhor a geraÃÃo de escoamento em solos expansivos. Maiores perdas por escoamento em todas as microbacias estudadas foram para chuvas do Regime II caracterizado por maiores alturas pluviomÃtricas, intensidades e ocorrÃncias. Quanto aos valores dos fatores C e dos coeficientes de ajuste âaâ e âbâ da MUSLE, para as coberturas estudadas, mostraram-se apropriados e recomendados de acordo com os Ãndices estatÃsticos empregados. Os valores da razÃo de aporte de sedimentos para eventos pluviomÃtricos individuais variaram de 0,08 a 1,67%, com mÃdia de 0,68%. Na bacia, eventos extremos podem causar elevada desagregaÃÃo de partÃculas de solo, mas podem nÃo dispor de energia de transporte suficiente para arrastÃ-las, gerando baixo SDR.

Per- and polyfluoroalkyl substances, PFASs, are highly fluorinated substances where the carbon chain is fully- or partly fluorinated. A functional group is coupled at the end of the carbon chain which gives PFASs their different properties. PFASs have been used in aqueous film forming foams (AFFFs) to decrease the surface tension of water and form a film on the fuel surfaces. AFFF is one of the main sources of PFASs pollution in the environment. A previous study has shown high PFASs concentrations in surface water in Lake Vänern. This study has analysed PFASs in sediment samples. The main detected PFASs was perfluorooctane sulfonate, PFOS, with concentrations below limit of detection to 51700 pg/g wet weight (ww). The compound detected in the highest concentration in Vissbäcken was PFOS at 7290 pg/g ww, this was followed by 6:2 fluorotelomersulfonate , 6:2FTS, at 516 pg/g ww. In outlet 4 (utlopp 4), PFOS had the highest concentration at 51800 pg/g ww, followed by perfluorohexane sulfonate, PFHxS, at 1790 pg/g ww. The only detected compound in the sediment cores was PFOS with approximately 100 pg/g ww. The high concentration of PFOS might be due to extensive use with subsequent release of firefighting foam in the area and degradation of other PFAS substances into PFOS. / Per-och polyfluoroalkylsubstanser, PFASs, är en grupp högfluorerade ämnen där kolkedjan är helt eller delvis fluorerad. En funktionell grupp kopplas i slutet av kolkedjan vilket ger PFASs dess olika egenskaper. PFAS har använts i vattenhaltiga filmbildande skum (AFFF) för att minska ytspänningen av vatten och bilda en film på bränsleytan. AFFF är en av huvudkällorna för PFAS-föroreningar i miljön. En tidigare studie har visat på höga koncentrationer av PFASs i ytvatten i Vänern. I denna studie har PFASs analyserats i sedimentprover. Den huvudsakliga detekterade PFAS var perfluoroktansulfonat, PFOS, med koncentrationer under detektionsgränsen och till 51700 pg /g våtvikt. Den högst detekterade föreningen i Vissbäcken var PFOS med 7290 pg/g våtvikt, detta följdes av 6:2 fluorotelomersulfonat, 6:2 FTS, med 516 pg/g våtvikt. Den högst detekterade föreningen i utlopp 4 var PFOS med 51800 pg/g våtvikt, följt av perfluorhexansulfonat, PFHxS, med 1790 pg /g våtvikt. Den enda detekterade föreningen i sedimentpropparna var PFOS med ungefär 100 pg/g våtvikt. Förekomsten av PFOS i sediment i sjön Vänern kan bero på omfattande användning med efterföljande utsläpp av brandbekämpningsskum i området och nedbrytning av andra PFAS-substanser till PFOS.

The Kennet and Avon Canal in southern England is experiencing severe water quality problems caused by inorganic sediment and algae. These water quality problems are affecting the angling sport of fishermen downstream of the confluence of the canal with the River Kennet. The Environment Agency has been called upon to remedy these issues, but before proceeding they desire a computer model capable of predicting the water quality impacts of various scenarios under consideration. No such model was available to them. This project identified the key solids generation and transport processes to be included in a water quality model for inland navigational canals. Where available, equations from the literature describing relevant processes were used or modified for inclusion in a canal modeling algorithm. Where literature was not available, water quality samples were taken to characterize needed relationships. The final algorithm was coded and tested using a simplified dataset that allowed clear evaluation of the simulated processes. After successful testing, the canal model was applied to the Kennet and Avon Canal. The time series predicted by the model were compared to observed hydrological, solids, and chlorophyll-a (representing algae) data at multiple points in the canal. The model adequately predicted all of these constituents at the monitored locations. The final task in the project required evaluation of six management scenarios proposed by the Environment Agency to address the water quality problem. The model suggests that filtration or other treatment of water in the canal near the confluence with the river is the best management option, as it will address both the elevated inorganic sediment and algae concentrations at the most critical point in the canal. Less desirable options include efforts that only target inorganic sediment, which could increase algal concentrations by increasing light availability; and diversion of surface flows from the canal, which could possibly damage the hydrologic balance of the canal while encouraging undesirable algal growth.

Usualmente la producción de sedimentos en suspensión (Qss) de un río es calculada utilizando datos de caudales medios diarios o mensuales. Considerando que la mayor Qss ocurre durante los eventos de lluvias y también que los caudales medios no son capaces de representar adecuadamente los máximos caudales, principalmente en zonas de alta variabilidad climática, la forma usual de cálculo de Qss puede subestimar esta producción. En este sentido, esta investigación buscó analizar la influencia de la variabilidad temporal de los datos de caudales en el cálculo de la producción de sedimentos. Adicionalmente fue analizada el uso de diferentes tipos de curvas de sedimentos: (i) para todo el periodo de estudio, (ii) por años hidrológicos y (iii) asociación por épocas características (húmedas, semi-húmedas y secas). El estudio fue realizado en la subcuenca del río Torata, ubicada en una zona semiárida al sur del Perú, entre 2100 y 5200 m de altitud con pendiente promedio de 21.0% y alta variabilidad climática, en especial la precipitación que se ve reflejado en los caudales, ya que en un lapso de horas puede variar de 4 a 34 m3/s. El error entre la descarga prevista y estimada para el periodo de estudio (2001-2012) utilizando los diferentes tipos de curvas fue (i) -65.85%, (ii) -15.36% y (iii) -8.74%, presentando mejora en el coeficiente de eficiencia de Nash-Sutcliffe de 0.248 para 0.500. Los resultados mostraron que la diferencia entre la descarga de sedimentos en suspensión total para el periodo calculado con caudales medias mensuales y diarias fue de -92% y -62%, ambos en comparación de producción para valores medios horarios. También fue constatado que el 99.7% de la producción de sedimentos ocurre en temporada de lluvias, inclusive, un único evento de lluvia llegó a producir 80% de la producción anual. Los resultados de esta investigación ponen en manifiesto la importancia de utilizar registros de caudales con escalas pequeñas de tiempo (minutos, horas), que puedan representar la alta variabilidad de los caudales característicos de zonas semiáridas. / The usual methods that calculate the suspended sediment flux (Qss) of rivers employ discharge mean values daily or monthly. As most of the sediments are transported during overflow events and a mean value smooths the flood peak discharge, mainly in high climatic variability areas, the usual method to evaluate the Qss might underestimate the production of river sediments. This paper reports on an analysis of the gauge influence of temporal variability on the sediment yield estimation. Additionally, the use of different types of sediment rate curves was analyzed for (i) the whole time-series data, (ii) per hydrological year, and (iii) per hydrological pattern characterization (flood, intermediary and drought). A study case was conducted in the Torata river sub-catchment, a Peruvian semi-arid area located between altitudes of 2100 and 5200 meters and whose average slope is 21%. The high climatic variability is expressed by the huge river flow amplitude, which ranges from 4 to 34 m3/s in a few hours. The errors for the sediment yield from 2001 to 2012 estimated by the different sediment rating curves were (i) -65,85%, (ii) -15,36% and (iii) -8,74%, with a 0,248 to 0,500 Nash-Sutcliffe efficiency coefficient improvement. The differences between the sediment yield in total suspension for the period calculated monthly and daily were -92% y and -62%, respectively, in comparison with the production for hourly average values. Results show that 99,7% of the sediment are produced during the flood season and a single overflow event could represent 80% of the annual sediment discharge flow. This research highlights the importance of collecting and using discharge data of a short time interval (minutes or hours) to compute and represent the overflow peaks typical of semiarid regions.

Os processos hidrossedimentológicos são complexos e dependem de diversos fatores. Entendê-los requer alto grau de especialização de mão de obra, além da utilização de equipamentos e técnicas ainda incipientes no país. O monitoramento hidrossedimentológico com dados confiáveis de concentração de sedimentos em suspensão pode ser problemático quando são empregados métodos convencionais, pois geralmente os mesmos apresentam medições com quantidade de postos e frequências inferiores aos desejáveis, limitando estudos e a gestão de recursos hídricos quando se trata de reservatórios. Nesse contexto, esta dissertação apresenta um estudo realizado no reservatório da Pequena Central Hidrelétrica Mogi-Guaçu (SP) na qual realizou-se a correlação dos dados de concentração de sedimentos em suspensão mensuradas com dispositivo automático (LISST-100X) e por amostragem convencional (Garrafa Van Dorn). Por meio de regressões lineares e testes estatísticos avaliou-se a eficiência da técnica de difração à laser, e se estimaram as concentrações de sedimentos em suspensão para as duas campanhas realizadas. Analisando os resultados obtidos, confirmou-se estatisticamente que dentre todos os cenários de regressões lineares adotados, o modelo que divide o reservatório em setores apresentou melhores estimativas de concentração, inferindo-se que a concentração do sedimento em suspensão possui um comportamento característico ao segmento do reservatório de Mogi-Guaçu. Notou-se também, a redução da concentração entre as duas campanhas realizadas, decorrente principalmente pela redução da velocidade do fluxo d\'água. Desse modo, a sonda LISST-100X, se mostrou viável para o estudo de caso. Ressalta-se que a utilização desta sonda possibilitou a obtenção de um número maior de dados do que os obtidos por meio do emprego de técnica convencional, possibilitando uma análise mais completa do reservatório e reduzindo significativamente o trabalho de campo, laboratório e escritório. / Hydrosedimentological processes are complex and depend on many factors and understanding them requires a high degree of labor specialization, as well as the use of equipment and techniques still incipient in Brazil. The hydrosedimentological monitoring with reliable sediment concentration data may be problematic when conventional methods are used. Its measurements are usually undertaken at a number of stations and frequencies below the desired ones, which limit studies and the management of water resources of reservoirs. This dissertation reports on a study on the Mogi-Guaçu (SP) Small Hydroelectric Plant reservoir and the correlation between the suspended sediment sample data measured by an automatic device (LISST-100X) and conventional sampling conducted by a Van Dorn sampler. The laser diffraction efficiency was evaluated by linear regression and statistical tests and the concentration of suspended sediment was estimated for the two campaigns. The results show the model that divides the reservoir into sectors provided better estimates of concentration and the concentration of suspended sediment exhibited a characteristic behavior for the segment of Mogi-Guaçu reservoir. A reduction in the concentration, caused mainly by a decrease in the water flow speed, was also observed between the two campaigns and laser diffraction proved feasible for the case study. This methodology enables the obtaining of a larger amount of data than that achieved by conventional techniques, a more complete analysis of the shell and significant reductions in the field, laboratory and office work.

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<p>U prvom delu rada ispitana je adsorpcija četiri grupe organskih&nbsp;jedinjenja: (1) nitroaromatičnih (nitrobenzen), (2) nepolarno alifatičnih&nbsp;(heksan), (3)&nbsp; monoaromatičnih (benzen, toluen, 1,2,3- i 1,2,4-trihlorbenzen) i (4) policikličnih aromatičnih ugljovodonika, PAH&nbsp;(naftalen, fenantren, piren i fluoranten) na vi&scaron;eslojnim ugljeničnim&nbsp;nanocevima (od eng. multiwalled carbon nanotubes, MWCNTs). Cilj&nbsp;ovog dela rada bio je pronaći korelaciju između parametara adsorpcije i&nbsp;fizičko-hemijskih karakteristika organskih molekula, kao i parametara&nbsp;<br />adsorpcije i karakteristika adsorbenata. Na osnovu dobijenih korelacija&nbsp;predložiti mehanizam adsorpcije ispitivanih organskih molekula na&nbsp;MWCNT-u.</p><p>U cilju ispitivanja uticaja kiseoničnih funkcionalnih grupa na povr&scaron;ini&nbsp;MWCNT-a odabrane su tri vrste MWCNT-a: originalni, nemodifikovani&nbsp;MWCNT (OMWCNT) i dve vrste funkcionalno modifikovanog&nbsp;MWCNT-a koji su dobijeni tretiranjem sa kiselinom tokom 3 h&nbsp;(FMWCNT3h) i 6 h (FMWCNT6h). Sve adsorpcione izoterme opisane&nbsp;<br />su Freundlich-ovim modelom. Nelinearnost izotermi bila je u opsegu od&nbsp;0,418 do 0,897. Rezultati pokazuju da dobijeni afiniteti adsorpcije (za ravnotežnu koncentraciju 50% rastvorljivosti jedinjenja u vodi, K_d0,5 S_W) za PAH-ove rastu sa povećanjem specifične povr&scaron;ine (SP) adsorbenta. Veći afiniteti adsorpcije dobijeni su za velike molekule kao &scaron;to su PAH-ovi u poređenju sa malim molekulima (benzen, toluen i heksan) &scaron;to može biti posledica veće kontaktne povr&scaron;ine između većih molekula i povr&scaron;ine adsorbenta. Pozitivna korelacija između afiniteta adsorpcije i hidrofobnosti molekula ukazuje da hidrofobne interakcije dominantno kontroli&scaron;u adsorpciju ispitivanih organskih jedinjenja, osim u slučaju nitobenzena. Da bi se ispitao uticaj &pi;-&pi; interakcija,&nbsp; K_d za odabranu ravnotežnu koncentraciju su normalizovane sa hidrofobno&scaron;ću molekula pri čemu su dobijeni odgovarajući&nbsp; K_d/K_OW&nbsp;odnosi. Za sva ispitivana jedinjenja K_d/K_OW<font size="1">&nbsp;</font>odnosi na svim ispitivanim MWCNT rastu u sledećem nizu: nepolarni alifatični &lt; monoaromatični &lt; PAH-ovi &lt; nitrobenzen, &scaron;to ukazuje da &pi;-&pi; interakcije značajno pobolj&scaron;avaju adsorpciju aromatičnih jedinjenja na MWCNT-u. Snažne interakcije između MWCNT-a i nitrobenzena posledica su formiranja &pi;-&pi; elektron donorsko-akceptorskih (EDA) interakcija izemđu nitroaromatičnih molekula (elektron akceptori)i visoko polarizovane ugljenične povr&scaron;ine nanocevi (elektron donori). Na osnovu dobijenih rezultata može se uočiti da se pri adsorpciji ispitivanihorganskih molekula na MWCNT-u istovreme odigrava vi&scaron;e mehanizama.</p><p>U drugom delu rada ispitan je uticaj ugljeničnog nanomaterijala (od eng.&nbsp;carbon based nanomaterial, CNM) natransport odabranih organskih&nbsp;jedinjenja (1,2,3- i 1,2,4-trihlorbenzena, naftalena, fenantrena, pirena i&nbsp;fluorantena) kroz sediment Dunava. Cilj ovog dela rada bio je ispitati&nbsp;mehanizam transporta odabranih organskih jedinjenja u prisustvu i&nbsp;odsustvu CNM. C/C_0&nbsp;vrednosti, dobijene za vreme trajanja eksperimenta&nbsp;<br />(t=96 h), ispitivanog jedinjenja u eluatu kolone napunjene samo&nbsp;sedimentom rastu u sledećem nizu: fluoranten &lt; piren &lt; fenantren &lt;&nbsp;1,2,4-trihlorbenzen &lt; 1,2,3-trihlorbenzen &lt; naftalen. U cilju ispitivanja&nbsp;uticaja hidrofobnosti ispitivanih molekula na sorpciju u neravnotežnim&nbsp;uslovima, dobijene vrednosti C/C₀ ispitivanih molekula su korelirane sa&nbsp;hidrofobno&scaron;ću molekula. Uočena je negativna korelacija &scaron;to ukazuje da&nbsp;hidrofobniji molekuli pokazuju duže vreme zadržavanja na koloni, a time&nbsp;i veću neravnotežnu sorpcijutokom transporta.&nbsp;</p><p>U prisustvu FMWCNT3h u koloni kojaje napunjena sedimentom može&nbsp;se uočiti da su koncentracije ispitivanih jedinjenja u eluatu manje za 2-3&nbsp;puta. Pri datim uslovima procenat detektovane koncentracije ispitivanog&nbsp;jedinjenja u eluatu raste u sledećem nizu: fluoranten &lt; fenantren &lt; piren &lt; naftalen &lt; 1,2,4-trihlorbenzena &lt; 1,2,3-trihlorbenzen. Predloženi mehanizam je sledeći: na eksperimentalnoj pH (pH=6,5) karboksilne grupe na FMWCNT3h su negativno naelekrisane, s druge strane tačka nultog naelektrisanja sedimenta Dunav je 4, &scaron;to ukazuje da je ukupna povr&scaron;ina pri pH=6,5 negativno naelektrisana. Međutim, metalni oksidi i hidroksidi gvožđa, aluminijuma i nikla na povr&scaron;ini sedimenta uzrokuju pozitivno naelektrisane centre &scaron;to dovodi do depozicije FMWCNT3h kao posledica elektrostatičkog privlačenja. Pri transportu organskih jedinjenja kroz sediment Dunava u prisustvu FMWCNT3h dolazi do simultane sorpcije organskih jedinjenja na organskom ugljeniku sedimenta i do adsorpcije na FMWCNT3h. Kada se pH vrednost poveća smanjuje se pozitivno naelekrisanje metalnih&nbsp; oksida i hidroksida na povr&scaron;ini sedimenta &scaron;to dovodi do povećane mobilnosti FMWCNT3h, a time i organskih jedinjenja adsorbovanih na njima. Svi rezultati ukazuju da pH vrednost ima veoma značajnu ulogu i može povećati &nbsp;transport funkcionalizovanog MWCNT-a, a time i transport organskih molekula adsorbovanih na njima.</p> / <p>The first part of the thesis investigates the adsorption of four&nbsp;groups of organic compounds (OCs): (1) nitroaromatics (nitrobenzene),&nbsp;(2) nonpolar aliphatics (hexane), (3) monoaromatics (benzene, toluene,&nbsp;1,2,3- and 1,2,4-trichlorobenzene) and (4) polycyclic aromatic&nbsp;hydrocarbons (PAHs, napthalene,&nbsp; phenanthrene, pyrene and&nbsp;fluoranthene) on multiwalled carbon nanotubes (MWCNTs). This part of&nbsp;the work aimed to find a correlationbetween the adsorption parameters&nbsp;and physical-chemical properties of the organic molecules, as well as the&nbsp;parameters of adsorption and the characteristics of the adsorbents. On the&nbsp;basis of the obtained correlations the adsorption mechanism was&nbsp;proposed. In order to investigate the influence which oxygen containing&nbsp;functional groups exert on the adsorption process, three MWCNTs were&nbsp;used: the pristine (original, as-received) MWCNTs (OMWCNT) and two&nbsp;<br />MWCNTs functionally modified by acid treatment of OMWCNT over 3&nbsp;h and 6 h (FMWCNT3h, FMWCNT6h). All adsorption isotherms well&nbsp;fitted with the Freundlich model. The nonlinearity of the isotherms&nbsp;ranged from 0.418 to 0.897. The results show that K_d&nbsp;values for PAHs&nbsp;increased with increasing specific surface areas (SSAs). The adsorption&nbsp;affinities of the larger molecular size OCs (PAHs) were higher &nbsp;than those of the smaller size OCs (benzene, toluene and hexane) which is probably due to their large contact area with the surface of the adsorbent. Adsorption of OCs on MWCNTs was mainly controlled by hydrophobic interactions, except for the nitroaromatic compound, as shown by the increasing adsorption affinities with the compound&rsquo;s hydrophobicity. K_OW-normalized adsorption coefficients (K_d/K_OW) for all the investigated compounds on all the MWCNTs followed the order: nonpolar aliphatic &lt; monoaromatics &lt; PAHs &lt; nitroaromatic, implying that &pi;-&pi; interactions enhanced the adsorption of aromatics on the MWCNTs. It can be concluded that the strong adsorptiveinteractions between the MWCNTs and nitroaromatics was due to the &pi;-&pi; electron-donor&ndash;acceptor (EDA) interaction between nitroaromatic molecules (electron acceptors) and the highly polarisable graphene sheets(electron donors) of the carbon nanotubes. Based on the obtained results, it can be concluded that multiple mechanisms control the adsorption of organic compounds on MWCNTs.</p><p>In the second part, the influence of carbon based nanomaterials CNM on&nbsp;transport of selected organic compounds (1,2,3 - and 1,2,4-trichlorobenzene, naphthalene, phenanthrene, pyrene and fluoranthene)&nbsp;through sediment Danube was investigated. &nbsp;The aim of this part of the&nbsp;work was to investigate the transport mechanism of selected organic&nbsp;compounds in the presence and absence of CNM. The C/C_0&nbsp;values for the&nbsp;tested compounds in the eluate of the column filled with sediment only&nbsp;increased in the following order: fluoranthene &lt;pyrene &lt;phenanthrene&nbsp;&lt;1,2,4-trichlorobenzene &lt;1,2,3-trichlorobenzene &lt;naphthalene. In order&nbsp;to investigate the influence of&nbsp; hydrophobicity of the investigated&nbsp;compounds on the nonequilibrium sorption, the obtained C/C_0&nbsp;values (for&nbsp;the duration of the experiment, t = 96 h) for these molecules were&nbsp;correlated with the hydrophobicity of the molecules. There was a&nbsp;negative correlation, indicating that more hydrophobic molecules show&nbsp;long residence times in the column, and thus had higher non-equilibrium&nbsp;sorption during transport. In the presence of FMWCNT3h in the column&nbsp;filled with sediment, it can be observed that the concentrations of&nbsp;compounds in the column eluate decreased by factors of 2-3. C/C_0&nbsp;values&nbsp;for the investigated compounds in the eluate increased in the following&nbsp;order: fluoranthene &lt;phenanthrene &lt;pyrene &lt;naphthalene &lt;1,2,4-trichlorobenzene &lt;1,2,3-trichlorobenzene. The proposed mechanism is as&nbsp;follows: under the experimental pH (pH = 6.5), carboxyl groups are&nbsp;negatively charged on the surface of FMWCNT3h and the point of zero&nbsp;charge of the Danube sediment is 4, which indicates thatthe total surface of the Danube sediment at pH 6.5 isnegatively charged. However, metal oxides and hydroxides of iron, aluminum and nickel on the surface of the sediment cause a positively charged centre that leads to the deposition of FMWCNT3h as a result of electrostatic attraction. Transport of organic compounds through the Danube sediment in the presence FMWCNT3h leads to the simultaneous &nbsp;sorption oforganic compounds on the sediment organic carbon and the adsorption of &nbsp;FMWCNT3h. When the pH increased, the positive charge of metal oxides and hydroxides on the sediment surface decreased, which leads to increased FMWCNT3h mobility and thus the organic compounds adsorbed on them. All results indicate that the pH value plays animportant role and can increase the transport of functionally modified MWCNT&#39;s, and thus the transport of organic molecules adsorbed on them.&nbsp;</p>

<p>Predmet izučavanja ove disertacije je ispitivanje mogućnosti imobilizacije&nbsp;toksičnih metala u sedimentu primenom imobilizacione tehnike&nbsp;solidifikacije/stabilizacije portland cementom, kalcijum-oksidom, prirodnim zeolitom,&nbsp;letećim pepelom, kaolinitom, montmorilonitom, i različitim sme&scaron;ama ovih agenasa&nbsp;kao i određivanje njihove efikasnosti u zavisnosti od brojnih faktora. Efikasnost&nbsp;imobilizacionih postupaka praćena je kori&scaron;ćenjem tzv. testova izluživanja, odnosno&nbsp;određivanjem koncentracije metala koji su u toku određenog vremena iz imobilisane&nbsp;faze pre&scaron;li u mobilnu fazu gde se smatraju potencijalno opasnim i biodostupnim.&nbsp;Krajnji cilj svakog testa izluživanja je mogućnost procene adekvatnosti primene&nbsp;određene imobilizacione, odnosno remedijacione tehnike. Efikasnost imobilizacionih&nbsp;postupaka zavisi i od određenih osobina: pH rastvora, dodatka imobilizacionog agensa&nbsp;&scaron;to je istraživanjem ispitano. Na osnovu ovog testa, odnosno &nbsp; odnosa kumulativne&nbsp;frakcije metala koja je oslobođena iz imobilizacione sme&scaron;e u mobilnu fazu i vremena&nbsp;određen je tip mehanizma koji omogućava transport metala &nbsp;(spiranje, difuzija,&nbsp;rastvaranje). Takođe su određeni i i parametri (koeficijenti difuzije, indeksi&nbsp;izlužljivosti) koji&nbsp; će poslužiti za ocenu efikasnosti prethodno primenjenih&nbsp;imobilizacionih tehnika. Primenjeni su i modifikovani testovi izluživanja sa ciljem &scaron;to&nbsp;bolje simulacije realnih uslova. U modifikovanim testovima izluživanja kori&scaron;ćen je&nbsp;rastvor sa pH 3,25 da bi se simulirali uslovi koji opona&scaron;aju kisele ki&scaron;e, odnosno uslovi&nbsp;u realnom sistemu. Takođe je kor&scaron;ćen i rastvor huminskih materija sa ciljem&nbsp;simulacije uslova velikog organskog opterećenja do kojeg bi moglo doći u slučaju&nbsp;akcidentnih situacija (na primer poplava) i generalno uslova koji se stvaraju u &nbsp;prirodi&nbsp;pri raspadanju organskog materijala (li&scaron;će, trava, itd.). Rezultati dobijeni simulacijom&nbsp;ovih uslova će dalje omogućiti modelovanje pona&scaron;anja metala u smislu dugoročnog&nbsp;&quot;izluživanja&quot; iz tretiranog sedimenta kao i procenu najefikasnijih agenasa &nbsp; za&nbsp;imobilizaciju različitih metala u sedimentu. Na osnovu dobijenih rezultata, zaključeno&nbsp;je da su optimalni agensi za imobilizaciju metala u sedimentu sme&scaron;a cementa i kreča&nbsp;(5% cementa i 10% kreča), sme&scaron;a montmorilonita i kreča (30% montmorilonita i 10%&nbsp;kreča), leteći pepeo (30%) i zeolit (30%). U ovim sme&scaron;ama dominantan mehanizam&nbsp;izluživanja je difuzija, a ove sme&scaron;e se mogu smatrati inertnim otpadom po svim&nbsp;ispitivanim kriterijumima. Ovi rezultati se mogu upotrebiti za projektovanje i&nbsp;izgradnju pilot postrojenja na kome bi se ispitala efikasnost ovih agenasa za&nbsp;remedijaciju sedimenta u realnim uslovima. Dobijeni podaci su neprocenjivi sa&nbsp;aspekta ekonomski i ekolo&scaron;ki prihvatljivog upravljanja sedimentom.</p> / <p>This work is concerned with exploring the possibilities of immobilization of toxic&nbsp;metals in sediments using solidification/stabilization as imobilization technique and&nbsp;using Portland cement, calcium oxide, natural zeolite, flying ash, kaolinite, montmorilonite, and various mixtures of these agents and determine their&nbsp;effectiveness depending on many factors. Performance of imobilization procedures&nbsp;was followed by the use of so-called leaching tests and determination of the metals&nbsp;concentration that are within a specified interval of time leached from the immobile phase and as such can be considered potentially hazardous and bioavailable. The ultimate goal of every leaching test is to assess the adequacy of the possibility of applying certain imobilization or remediation technique. Performance of imobilizaction procedures depends on certain characteristics: pH of solution, additon of imobilization agent, etc. Based on this test, ie relation between the cumulative fraction of metal leached from imobilization mixture and time, the type of leaching mechanism that allows the transport of metals (wash-off, diffusion, dissolution) was determined. Other parameters which will serve for evaluating the efficiency of the previously applied imobilization techniques (diffusion coefficients, leaching indices) were also determined. Modified leaching tests were applied with the aim of better simulation of real conditions on the field. In the modified leaching tests the solution with pH 3.25 was used to simulate conditions that mimic acid rain and conditions in the real system. The humic acid solution was also used with the aim to simulate high organic loads which could occur in the case accident situation (eg floods) and the general conditions that are created in naturewhen decaying organic material (leaves, grass, etc.). The results obtained by simulating these conditions will enable the modeling of behavior of metals in terms of long-term leaching period from the treated sediment and assess the most effective agents for the immobilization of various metals in the sediments. Based on these results, it was concluded that the optimal agents for immobilization of metals in the sediment mixture of cement and lime (5% cement and 10% lime), a mixture montmorilonite and&nbsp; lime (30% montmorilonite and 10% lime), fly ash (30%) and zeolite (30%). In these mixtures dominant leaching mechanism is diffusion, and these mixtures can be considered as inert waste by all tested criteria. These results can be used to design and builda pilot plant in which order to evaluate the effectiveness of these agents for remediation of sediment in real &nbsp;terms. The obtained data are invaluable from the aspect of economic and ecologically acceptable management of sediment.</p>

<p>Prirodna organska materija zemlji&scaron;ta/sedimenata predstavlja glavnu oblast<br />za sorpciju hidrofobnih organskih jedinjenja, a njene osobine utiču na stepen<br />retencije i konsekventnu (bio)dostupnost organskih jedinjenja. Da bi se procenio<br />ekotoksikolo&scaron;ki rizik zagađenih zemlji&scaron;ta/sedimenata po okolinu, dizajnirala<br />odgovarajuća strategija remedijacije ili predvidela sudbina i transport organskih<br />polutanata u zagađenim zonama, neophodno je razumevanje mehanizma sorpcije i<br />desorpcije na nivou mehanizma uspostavljenih veza. U radu je izvr&scaron;eno ispitivanje<br />sorpcije i desorpcije odabranih hidrofobnih organskih polutanata, pentahlorbenzena<br />i lindana, na sekvencijalno ekstrahovanim huminskim kiselinama i huminima iz<br />jednog uzorka sedimenta u cilju pronalaženja veze između strukturnih<br />karakteristika izolovanih huminskih kiselina i humina i sorpcionih i desorpcionih<br />parametara. Afinitet za sorpciju, nelinearnost izotermi i prividna sorpciono-desorpciona histereza korelirani su&nbsp; sa osobinama sorbenata dobijenim iz<br />elementarne i FTIR spektroskopske analize. Predloženo je da je mehanizam<br />sorpcije na huminskim kiselinama rezultat odigravanja raspodele i specifične<br />adsorpcije, pri čemu se pri nižim koncentracijama pentahlorbenzena i lindana prvo<br />popune sorpciona mesta u kondenzovanoj aromatičnoj oblasti, a tek potom pri<br />vi&scaron;im koncentracijama sorpciona mesta u amorfnim alifatičnim oblastima.<br />Sveukupno vi&scaron;i koeficijenti nelinearnosti dobijeni za sorpciju pentahlorbenzena na huminskim kiselinama u odnosu na nelinearnost sorpcionih izotermi lindana, ukazuju na to da u ukupnoj sorpciji pentahlorbenzena veći značaj ima mehanizam raspodele i sme&scaron;tanje molekula pentahlorbenzena u hidrofobne &scaron;upljine huminskih kiselina, u odnosu na specifičnu adsorpciju. Ovi zaključci su potvrđeni rezultatima spektroskopskih istraživanja interakcija&nbsp; odabranih organskih jedinjenja i N-metilformamida. Predloženi mehanizam sorpcije ne može objasniti sorpciju pentahlorbenzena i lindana na uzorcima humina, većje pretpostavljeno da nelinearna sorpcija za uzorke humina može biti rezultat ostvarivanja povr&scaron;inskih interakcija, a visoki afinitet za sorpciju rezultat je raspodele organskih jedinjenja u amorfnim alifatičnim oblastima koje pružaju odlično okruženje za sorpciju.</p><p>U cilju daljeg proučavanja mehanizma sorpcije, izvr&scaron;eno je ispitivanje kinetike<br />desorpcije tri odabrana hidrofobna organskajedinjenja, pentahlorbenzena, lindana i<br />pentahloranilina, posredstvom&nbsp; čvrstog adsorbenta, XAD-4 makroporozne<br />jonoizmenjivačke smole. Na osnovu rezultata dobijenih za uzorak sedimenta i<br />frakciju &lt; 125 &micro;m za dva ravnotežna vremena (15 i 90 dana) i za sva odabrana<br />organska jedinjenja može se zaključiti da se za procenu potencijalne (bio)dostupne<br />frakcije organskih jedinjenja može koristiti jednostavna desorpcija u prisustvu<br />XAD-4 makroporozne jonoizmenjivačke smole i to na dva načina: (1) ekstrakcijom<br />sedimenta tokom 24 časa, kada frakcija koja se desorbuje odgovara frakciji<br />jedinjenja koja se nalazi u brzo-desorbujućem domenu organske materije, ili (2)<br />ekstrakcijom tokom 6 časova, kada frakcija koja se desorbuje odgovara polovini<br />one frakcije jedinjenja koja se nalazi u brzo-desorbujućem domenu organske<br />materije.</p> / <p>Natural organic matter of soil/sediment make the main region for&nbsp;sorption of hydrophobic organic compounds, ant its properties influence the degree&nbsp;of retention and, consequently, (bio)availability of organic compounds. In order to&nbsp;assess the ecotoxicological risks of contaminated soils/sediments to the&nbsp;environment and design the appropriate remediation strategy or predict the fate and&nbsp;transport of organic pollutants in contaminated zones, it is necessary to understand&nbsp;the mechanisms of sorption/desorption at the level of the mechanism of established&nbsp;bonds. Study of the sorption and desorption of selected hydrophobic organic&nbsp;pollutants, pentachlorobenzene and lindane, on sequentially extracted humic acids&nbsp;and humins from a single sediment sample with the aim of finding the relationship&nbsp;between the structural characteristics of the isolated humic acids and humin and&nbsp;sorption and desorption parameters. Sorption affinity, nonlinearity of isotherms,&nbsp;and apparent sorption-desorption hysteresis were correlated to the sorbent&nbsp;characteristics obtained from elemental analysis and FTIR spectroscopic data. The&nbsp;proposed sorption mechanism on humic acids assumes that at low concentrations&nbsp;of pentachlorobenzene and lindane the sorption sites in the condensed aromatic&nbsp;region are occupied first, and then, at their higher concentrations, the sorption sites&nbsp;in the amorphous and aliphatic regions. Generally higher nonlinearity coefficient obtained for the sorption of pentachlorobenzene on &nbsp;umic acids compared with the nonlinearity of sorption isotherms for lindane, indicate that in the overall sorption of pentachlorobenzene of higher significance is the &nbsp;echanism of distribution and insertion of pentachlorobenzene molecule into hydrophobic dips of humic acids, compared to specific adsorption. These conclusions were confirmed with the results of spectroscopic investigation of &nbsp;intermolecular interaction of chosen organic compounds and N-methylformamide.Since suggested sorption mechanism could not explain sorption of &nbsp;pentachlorobenzene and lindane onto humin samples, it is supposed that the nonlinearity can be a result of surface interactions, while the high sorption affinity is result of distribution of organic compounds in the amorphous aliphatic regions that offer an excellent environment for sorption.</p><p>With the aim of further insight into the sorption mechanism, investigation of&nbsp;desorption kinetics of three chosen hydrophobic organic compounds,&nbsp;pentachlorobenzene, lindane and pentachloroaniline, in the presence of &nbsp;soild&nbsp;adsorbent XAD-4 macroporous ion-exchange resin was performed. On the basis of&nbsp;the results obtained for sediment sample and fraction &lt; 125 &micro;m at two equilibrium&nbsp;times (15 and 90 days) and for all selected organic compounds, it can be concluded&nbsp;that the assessment of the potential (bio)avialable fraction of organic compounds&nbsp;may be obtained by using simple method of desorption in the presence of XAD-4&nbsp;macroporous ion-exchange resin, performed in two ways: (1) by sediment&nbsp;<br />extraction during 24 hours, when the desorbing fraction corresponds to the fraction&nbsp;of &nbsp;he compound that is found in the fast-desorbing domain of organic matter, or&nbsp;(2) by 6-hour extraction, when the desorbing fraction corresponds to one half of the&nbsp;fraction appearing in the fast-desorbing domain of the organic matter.</p>