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No description available.

For a numerical or analytical model to be useful it should be ensured that the model outcome matches the observations or field measurements during calibration. This process has been typically done by manual perturbation of the model input parameters. This research investigates a methodology for using non linear parameter estimation technique (the Marquardt-Levenberg technique) with the multi component reactive solute transport model SEAM3D. The reactive multi-component solutes considered in this study are chlorinated ethenes. Previous studies have shown that this class of compounds can be degraded by four different biodegradation mechanisms, and the degradation path is a function of the prevailing oxidation reduction conditions. Tests were performed in three levels; the first level utilized synthetic model-generated data. The idea was to develop a methodology and perform preliminary testing where "observations" can be generated as needed. The second level of testing involved performing the testing on a single redox zone model. The methodology was refined and tested using data from a chlorinated ethenes-contaminated site. The third level involved performing the tests on a multiple redox zone model. The methodology was tested, and statistical validation of the recommended methodology was performed. The results of the tests showed that there is a statistical advantage for choosing a subgroup of the available parameters to optimize instead of the optimizing the whole available group. Therefore, it is recommended to perform a parameter sensitivity study prior to the optimization process to identify the suitable parameters to be chosen. The methodology suggests optimizing the oxidation-reduction species parameters first then calibrating the chlorinated ethenes model. The results of the tests also proved the advantage of the sequential optimization of the model parameters, therefore the parameters of the parent compound are optimized, updated in the daughter compound model, for which the parameters are then optimized so on. The test results suggested considering the concentrations of the daughter compounds when optimizing the parameters of the parent compounds. As for the observation weights, the tests suggest starting the applied observation weights during the optimization process at values of one and changing them if needed. Overall the proposed methodology proved to be very efficient. The optimization methodology yielded sets of model parameters capable of generating concentration profiles with great resemblance to the observed concentration profiles in the two chlorinated ethenes site models considered. / Ph. D.

In the research presented here, a new ground water model, FEMCoast, was developed to simulate ground water discharge to the intertidal zone of estuarine systems. This research may be the first attempt to model the ground water discharge process in a tidal estaurine system. The development of FEM Coast was undertaken as no existing ground model was capable of directly simulating the dynamic boundary conditions along the sediment water interface of the intertidal zone. Reproducing the dynamic tidal boundary conditions along the sediment water interface was determined to be essential to replicating the complex salinity gradients observed in the ground water within the intertidal zone. Field data and model results confirmed the presence of a region of ground water where an inverted salinity gradient existed. In this region the concentration of salinity decreased with depth from the ground surface. FEMCoast was also able to reproduce field data on the movement of the near shore water table and ground water discharge rates and patterns. However, the model was not able to replicate the short-term fluctuation in the concentration of salinity within the aquifer due to changes in the concentration of salinity within Cherrystone Inlet. It is believed that the inability to account for the wave action of the tides within the intertidal zone is responsible for this difficulty. The use of FEMCoast integrated with field studies provided a new method to investigate ground water discharge to tidal estuarine systems. / Ph. D.

An investigation was undertaken to better understand the hydrogeologic framework of the Rio Cobre and Rio Minho-Milk river basins, Jamaica, West Indies. A quasi three-dimensional finite-difference groundwater flow model was used to conceptualize flow conditions and establish a hydrogeologic budget of the region. The Rio Cobre and Rio Minho-Milk river basins lie on the Clarendon Block, an area with a complex geologic history. The geologic history includes: 1) the intrusion of calc-alkaline granites, 2) morphotectonic sedimentation, 3) three episodes of deformation by transpressional and transcurrent tectonics, 4) the deposition of a highly permeable, Tertiary carbonate platform, and 5) the development of near surface karst oriented with the major NNW-SSE fault trend in the basins. Since deposition, compression, faulting, and solution have modified the distribution and thickness of carbonate rocks impacting the ground-water flow of the region. The most notable features are the older NNW-SSE trend dip-slip faults and the younger E-W trend strike-slip faults, notably the South Coast Fault (SCF) formed during the Laramide Orogeny. The White Limestone aquifer is the principal aquifer of the Rio Cobre and Rio Minho-Milk river basins in the parishes of St. Catherine, Clarendon, and partly in Manchester. It is characterized by intercalated sequences of permeable rubbly and micritic carbonate rocks. The age of the rocks range from Late Cretaceous (Maastrichtian) to Recent. The permeability of the South Coast fault and the high hydraulic conductivity value associated with the Tertiary carbonate platform (480 m/d) in the Lower Rio Minho-Milk River basin control the gradient of the potentiometric surface and ground water flow in that region The agreement between the measured and the simulated hydraulic heads obtained for this steady-state model suggests that the values assigned to the hydraulic properties that characterize the ground-water flow of the White Limestone aquifer are reasonable. Recharge to the area occurs as net recharge in addition to upland subsurface inflow across the general head boundary in the northern part of the study area. Comparisons of calculated and observed values of head indicate that simulated groundwater flow field generally agree with field conditions. Several simplifying assumptions were made for the conceptualization and simulation of flow in the basins: 1) during the 1998 water year, ground-water in the basins was considered at steady-state, 2) pumping does not significantly affect the level of hydraulic heads; therefore pumping wells are not simulated, 3) Net recharge from precipitation varies spatially, 4) karstification and aquifer heterogeneity impact on the distribution of hydraulic conductivity, 5) Darcy's law is applicable to flow through the fractures and solutions openings in a karst region, 6) flow in the White Limestone aquifer occurs in the uppermost 650 m and vertical flow is assumed to be controlled by intervening units, 7) evaporation was not explicitly simulated in the model. Recharge rates were considered as "net recharge," and 8) submarine discharge occurs from the aquifer along the coast where aquifers are hydraulically connected to the sea. Ground-water flow in the basins was conceptualized as a quasi three-dimensional flow system in which two model layers were used. The model boundaries selected to represent natural hydrologic boundaries include (1) a no-flow along the western and eastern boundaries, (2) a constant head boundary along the freshwater/saltwater interface; (3) a general head boundary along the northern boundary; and (4) a horizontal-flow barrier boundary along the South Coast Fault; and (5) river leakage boundaries along major rivers draining the coastal basins. The simulated region is an area of 2,550 square kilometers, two-thirds of which is hilly and the remainder, irrigated plains with small swamps draining the area. The model consists of over 337,500 cells and employed a regular grid spacing of 200m x 160m. The model was designed and calibrated to steady-state conditions from data observed/estimated during water year 1998. The Water Resources Authority of Jamaica (WRAJ) will use the results of the modeling study as a predictive tool for long-term management and monitoring of water resources in the region. The model was calibrated using a manual trial-and-error adjustment of parameters. Hydraulic conductivity values in both model layers, hydraulic conductivity at the general-head boundary, and streambed conductance were adjusted during successive simulations until computed head values approximated field conditions. The computed potentiometric surface is an adequate or reasonable match on a regional scale, with the general horizontal hydraulic gradient oriented with the main fault trend NNW-SSE in both basins. Sensitivity tests of the calibrated model were conducted on net recharge, hydraulic conductivity, hydraulic conductivity assigned along the general-head boundary, and streambed vertical conductance to determine if differences between simulated and observed values were similar to the range of uncertainty in the values of input data and boundary conditions. Based on the results obtained from the sensitivity analysis, it is apparent that the model is extremely sensitive to changes in horizontal hydraulic conductivity and recharge in the form of precipitation. The model is least sensitive to streambed vertical hydraulic conductivity. / Master of Science

Arsenic has been discovered in the groundwater of Bangladesh and affects millions of people. Many parts of the country experiences elevated levels of As above the drinking water limit set by Bangladesh at 50 μg/L. Tube wells installed at a shallow depth is the main source of drinking water in Bangladesh for local communities. Previous investigation has identified elevated levels of As in these shallow tube wells. Color of sediments as well as depth below surface was also identified as important properties in determining As safe aquifers. Despite the knowledge surrounding the elevated As concentrations and mitigation efforts there has been a lack of large scale, successful mitigation methods. The problems have been identified as a lack of large scale knowledge transfer regarding the subsurface geology to local drillers and communities as well as a lack of coherent and country wide data capturing, management and storage. The aim of this study was to investigate how already captured data in Bangladesh from previous projects could be compiled, formatted, visualized and communicated to facilitate large scale knowledge transfer as well as increasing the understanding off what geological and hydrogeological data is necessary to accurately and with a high degree of confidence map the aquifers of Bangladesh. This study was conducted as a pilot study for aquifer mapping in the EPSC-DDM project together with the International Groundwater Research Group at KTH. To understand data necessity and how to effectively map aquifers in Bangladesh data from various sources needed to be compiled. The data was cleaned and investigated as 2D and 3D models. Hydrographs was created from water level data in GeoGIS. Water quality data was used together in modelling processes and alone to investigate the water quality of potential aquifer systems. The modelling was conducted in GeoGIS for 2D cross sections and Earth Volumetric Studios for 3D models. The results showed two distinct aquifer in the study area of Towakull union, at a depth of 50-150 m as well as around 200-250 meters. The shallow aquifer was deemed unsafe in terms of As concentrations while the deep was deemed safe. The results from the modelling indicated that data already gathered for previous projects could be used as a base for aquifer mapping. Lithological data with main grain size together with water quality data at depth was deemed as the minimum data needed for 3D model aquifer mapping and water level data as well as color of the sediments was deemed as important data to collect if possible. The results also indicated that automatic capturing and storage of data into one coherent format would greatly decrease the time of data cleaning before modelling as well as increasing the accuracy and limiting the need for interpretation of the modeler. In conclusion the usage of 2D or 3D models for aquifer mapping shows great promise and the usage of already captured data to create these models was possible. The models had the potential to be easily communicated and distributed in digital format or in print to facilitate large scale knowledge transfer and increase evidence-based decision making in Bangladesh. / Arsenik (As) har upptäckts i grundvattnet i Bangladesh och påverkar tillgången till vatten för miljontals människor. Stora delar av landet har områden med förhöjda halter av As, över 50 μg/L vilket är den nationella gränsen för dricksvatten. Tidigare forskning har visat att rörbrunnar är den till störst del accepterade åtgärdsmetoden för As-säkert dricksvatten bland lokala aktörer, detta på grund av att de är billiga att installera och enkla att använda. Färg på sediment på det djup där filtret till brunnarna installeras har visats ge indikation på om grundvattnet har låga eller höga halter av arsenik. Holocena sediment är ofta grå till mörkt gråa och innehåller höga halter löst arsenik medan de röda eller bruna sediment som blivit exponerade och oxiderade har visat sig ha låga halter av löst arsenik. Även om problematiken och åtgärdsmetoder kring arsenikförorening av grundvattnet i Bangladesh är väl dokumenterade är det fortfarande stora delar av befolkningen som inte har tillgång till rent dricksvatten. Bristen på resultat i åtgärder tros vara avsaknaden av kunskapsdelning och utbildning av lokalbefolkningen, vilka ofta är de som borrar och använder rörbrunnarna, samt att det saknas ett nationellt övergripande format för insamling, lagring och användning av geologisk och hydrogeologisk data. Den här studien skrevs tillsammans med EPSC-DDM som är ett projekt mellan KTH, SIDA, UNICEF och DPHE i Bangladesh. Målet med studien var att undersöka vilken typ av geologisk samt hydrogeologisk data som kunde användas för akvifärkartläggning på lokal nivå i Bangladesh. Vidare var det av intresse att förstå på vilket sätt denna data skulle användas och kommuniceras för att kunna förmedla kunskapen till lokala aktörer. Det var av intresse att använda redan insamlad data i Bangladesh. Tillgänglig geologisk och hydrogeologiska data samlades in och modellerades i 2D och i 3D för att kartlägga akvifärer på lokal skala i Bangladesh. Programvaran GeoGIS användes för 2D modelleringen och Earth Volumetric Studios användes vid 3D modelleringen. Grundvattennivådata användes för att skapa hydrografer som kunde användas tillsammans med de tillverkade modellerna. Studieområdet var Towakull union i Gowainghat upazilla, norra Bangladesh. Studieområdet valdes på grund av tillgång till olika dataformat och källor. Resultatet av studien visade att det troligen fanns två distinkta akvifärer, vilket är en ansamling av grundvatten som kan användas som en vattenresurs, i Towakull, Bangladesh, vilket var området för pilotstudien. De aktuella akvifärerna låg på ett djup av 50–150 meter samt 200–250 meter. Den grunda akvifären visade sig innehålla förhöjda halter av arsenik och ansågs vara osäker att använda som dricksvattentäkt. Den djupa akvifären verkade vara frånskild den ovanliggande grunda akvifären och innehöll lägre nivåer av arsenik. Modelleringsprocessen visade att tidigare insamlad data kan användas på ett effektivt sätt för att kartlägga akvifärer i Bangladesh, både i 2D och i 3D. För 3D modellering visade det sig att geologiska data och vattenkvalité var nödvändigt för att få ett resultat som kunde ge information med tillräcklig precision för att stödja lokala aktörer i deras beslutsfattande. Hydrografer samt färg på sediment gav mer säkerhet i kartläggningen men bedömdes inte vara nödvändig om de inte skulle vara tillgängligt. Automatisk insamling av data bedöms underlätta vid modelleringsprocessen då en stor del av problemet var att ”rengöra” och formatera data från olika källor till liknande format. Detta steg kan till stor del undvikas om data samlas in och lagras automatiskt på samma sätt i hela Bangladesh. Sammanfattningsvis visade pilotstudien att 2D- och 3D modellering är effektiva verktyg för att kartlägga akvifärer i Bangladesh med hjälp av redan insamlad data. Litologisk data och vattenkvalitéan sågs vara nödvändig för modelleringsprocessen, sedimentfärg och hydrografer var kraftfulla hjälpmedel. Resultaten av modelleringen bedöms ha hög potential för att kunna förmedlas till lokala aktörer, i till exempel en liten utskriven sammanfattningsrapport. Att gå över till automatisk insamling och lagring av data är avgörande för att göra data tillgängligt och kvalitetssäkrad och således för att säkra modelleringsprocessens kvalitet och potential för uppskalning.

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The knowledge of soil moisture is of pronounced importance in various applications e.g. flood control, agricultural production and effective water resources management. These applications require the knowledge of spatial and temporal variation of the soil moisture in the watershed. There are three approaches of estimating/measuring soil moisture namely,(i) in-situ measurements,(ii) remote sensing, and(iii) hydrological modelling. The in situ techniques of measurement provide relatively accurate information at point scale but are not feasible to gather in large numbers relevant for a watershed. The soil moisture can be simulated by hydrological models at the desired spatial and temporal resolution, but these simulations would often be affected by the uncertainties in the model physics, parameters, forcing, initial and boundary conditions. The remote sensing provides an alternative to retrieve the soil moisture of the surface (top few centimeters ) layer, but even this data is limited by the spatial or temporal resolution, which is satellite dependant. Hydrological models could be improved by assimilating remotely sensed soil moisture, which requires a retrieval algorithm. In order to develop a retrieval algorithm the satellite data need to be calibrated/validated with the in-situ ground measurements. The retrieval of surface soil moisture from microwave remote sensing is sensitive to surface conditions, and hence requires calibration/validation specific to a site/region. The improvement in the hydrological variables/fluxes is sensitive to the framework adopted during the assimilation of remotely sensed data. The main focus of the study was to assess the retrieval algorithm for the surface soil moisture from both active (ENVISAT,RADARSAT-2)and passive(AMSR-E) microwave satellites in a semi-arid tropical watershed of South India. Further, the usefulness of these retrieved remotely sensed products for the estimation of recharge was investigated by developing a coupled hydrological model and an assimilation framework. A brief introduction was made in Chapter 1 on the importance of surface soil moisture and evapotranspiration in hydrology, and the feasible options available for the retrieval from microwave remote sensing. A detailed review of the literature is presented in Chapter 2 to establish the state-of-the-art on the following:(i) retrieval algorithms for the surface soil moisture from active and passive microwave remote sensing,(ii) estimation of actual evapotranspiration from optical remote sensing(MODIS),(iii) coupled surface-ground water hydrological models,(iv) estimation of soil hydraulic properties with their uncertainties, and(v) assimilation framework specific to hydrological modelling. To calibrate/validate the retrieval algorithms and to test the coupled model and the assimilation framework developed, field measurements were carried out in the BerambadI experimental watershed located in the Kabini river basin. The surface soil moisture in 50 field plots, profile soil moisture up to 1m depth in 20 field plots, and ground water level in 200 bore wells were measured. Twelve images of ENVISAT, seven teen images of RADARSAT-2, along with AMSR-E and MODIS data were used. These data pertained to different durations during the period 2008 to 2011,the details of which are given in Chapter 3. The approach for the retrieval of surface soil moisture and the associated uncertainty from active and passive microwave remote sensing is given in Chapter 4. Surface soil moisture was retrieved for six vegetation classes using the linear regression model and copulas. Three types of copulas(Clayton, Frank and Gumbel) were investigated. It was found that the ensemble mean simulated using the linear regression model and three copulas was nearly same. The copulas were found to be superior than the linear regression model when comparing the distributions of the mean of the generated ensemble. Among the copulas it was observed that the Clayton copula performed better in the lower and middle ranges of backscatter coefficient, while the Gumbel and Frank copulas were found to be superior in the upper ranges of backscatter coefficients. The range of RMSE was approximatively 4cm3cm−3 indicating that the retrieval from ENVISAT/RADARSAT-2 was good. ACDF based approach was proposed to retrieve the surface soil moisture map for the watershed with a spatial resolution of 100m x 100m ( i.e one hectare). The map of the uncertainty in the retrieved surface soil moisture was also prepared using the Clayton copula. The AMSR-E surface soil moisture product was calibrated for the watershed during the period 2008 to 2011, using the map generated from the ENVISAT/RADARSAT data. They Clayton copula was used to generate the ensemble of the corrected AMSR-E surface soil moisture. The standard deviation of the generated ensemble varied from 0.01 to 0.03cm3cm−3 ,hence the derived surface soil moisture product for Berambadi was found to be good. In the Chapter 5, a one dimensional soil moisture model was developed based on the numerical solution of the Richards’ equation using finite difference method and inverse modeling was carried out using the Generalized Likelihood Uncertainty Estimation(GLUE) approach for estimating the soil hydraulic parameters of the van Genuchten(VG) model and their uncertainty. The parameters were estimated from the two field sites(Berambadi and Wailapally watershed in South India) and from laboratory evaporation experiment for the Wailapally site. It was found that the GLUE approach was able to provide good uncertainty bounds for the soil hydraulic parameters. The uncertainty in the estimates from the field experiment was found to be higher than from the laboratory evaporation experiment for both water retention and hydraulic conductivity curves. The saturated soil moisture(θs )and shape parameter (n) of VG model estimated from the laboratory evaporation and field experiment were found to be the same, and further more they showed a lower uncertainty from both the experiments. Moreover, the residual soil moisture (θr), inverse of capillary fringe thickness (α) and saturated hydraulic conductivity( KS) showed a relatively higher uncertainty. In the Berambadi watershed ,the inverse modeling was performed in three bare field plots, and it was found that field plots which had higher θs showed a relatively higher actual evapotranspiration (AET) and lower potential recharge. In Chapter 6, the retrieval of profile soil moisture up to 2m by assimilation of surface soil moisture was investigated by performing synthetic experiments on six soil types. The measured surface soil moisture over top 5cm depth was assimilated into the one dimensional soil moisture model to retrieve the profile soil moisture. Even though the assimilation of surface soil moisture helped in improving the profile soil moisture for the six soil types, the bias was observed. To reduce the bias, pseudo observations of profile soil moisture were generated and used in addition to the surface soil moisture in the assimilation altogether. These pseudo observations were generated using the linear relationship existing between the surface and profile soil moisture. A significant bias reduction was found to be feasible by using this method when pseudo observations beyond 75cm depth were used then there was no significant improvement. A coupled surface-ground water model was developed, which had 5 layers for the vadose zone and one layer for the ground water zone, in order to consider the major hydrological processes from ground surface to ground water table in a semi-arid watershed. The details of the coupled model were described in Chapter 7. The major aim of this model was to be able to use remotely sensed data of surface soil moisture and evapotranspiration to simulate recharge. The model was tested by applying in a lumped framework to the field data set in the Berambadi watershed for the year 2010 to 2011. The performance of the model was evaluated with the measured watershed average root zone soil moisture and ground water levels. The watershed average root zone soil moisture was obtained by averaging the field measurements from 20 plots and average ground water level was obtained by averaging the field measurement from 200 bore wells. In order to assimilate the AET into the coupled model, the daily AET at a spatial resolution of 1km was estimated from MODIS data. The AET was validated in one forested and four agricultural sites in the watershed. The validation was based on the comparison with AET simulated from water balance models. For agricultural plots the STICS (crop model) and for the forested site the COMFORT (hydrological) model were used. The AET from the MODIS showed a reasonably good match with both the forested and agricultural plots at the annual scale (for the crop model approximately 4-5 months). Model simulations were carried out with and without assimilating the remotely sensed data and the performance was evaluated. It was found that the assimilation helped in capturing the trends in deeper layer soil moisture and groundwater level. At the end, in Chapter 8 the major conclusions drawn from the various chapters are summarized.

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)