Compostos químicos de origem natural e artificial são incorporados aos seres humanos por diversas vias, sendo elas ingestão, inalação e contato dérmico. O presente estudo tem como objetivo quantificar o risco para a saúde humana pela exposição a pesticidas e metais detectados no Rio Pardo, Brasil. Foram realizadas campanhas de coleta de dados em 6 pontos ao longo do Rio Pardo durante períodos chuvosos e secos entre os anos de 2014 e 2015. Três espécimes de peixes do Rio Pardo foram adquiridos com pescadores e outros três espécimes foram adquiridos em mercado no município de Ribeirão Preto, SP. Foram analisados os inseticidas organoclorados pp\'-DDE, pp\'-TDE, pp\'-DDT, ?- BHC, ?-BHC, ?-BHC, heptacloro, heptacloro epóxido, aldrin, dieldrin, endrin, ?- endossulfan, ?-endossulfan e endossulfan sulfato. Os herbicidas nitrogenados quantificados na água foram ametrina, atrazina, desetilatrazina, diuron, hexazinona, metribuzim, simazina e tebutiuron. Os metais quantificados nas amostras de água, sedimento e peixes foram Al, As, Be, Cd, Cr, Cu, Pb, Mn, Hg, Ni, Tl, Sn, V e Zn. Realizou-se amostragem passiva pelo método DGT para quantificação da fração biodisponível dos metais na água. A avaliação de risco para saúde humana por meio da exposição aos metais e herbicidas foi realizada considerando o cenário residencial. Foram detectados metabólitos de DDT e DDD em níveis inferiores aos limites permitidos pela legislação internacional. Os herbicidas nitrogenados foram detectados em cinco dos seis pontos de coleta analisados no Rio Pardo, sendo que para atrazina as concentrações variaram de 0,16 a 0,32 µg/L, acima dos valores permitidos pela União Europeia (0,1 µg/L). As análises de metais na água indicaram que Al, Cd, Cu, Hg, Mn, Pb e Zn apresentaram concentrações acima dos limites recomendados pela legislação brasileira. O pH da água variou de 5,7 a 7,8. Os níveis de alguns metais nos sedimentos foram maiores no ponto 1, sugerindo fonte de poluição pontual provavelmente relacionada a afluente contaminado. A determinação de metais em peixes indicou que a espécie P. glauca apresentou concentração acima dos limites estabelecidos pela legislação brasileira para As (7,23 µg/g). A avaliação de risco não carcinogênico pela ingestão de água indicou que os níveis de herbicidas não representaram risco. Já para metais, todos os pontos de coleta tanto no período seco quanto chuvoso apresentaram HI>1, sendo que o metal que mais contribuiu com os resultados foi o Al. A avaliação de risco carcinogênico indicou que para As os seis pontos de coleta avaliados estavam acima dos valores considerados aceitáveis (<10-6 ) no período chuvoso. A avaliação de risco não carcinogênico associado à ingestão de peixes indicou que as espécies Salmo spp. e P. glauca apresentaram HIs acima dos níveis considerados seguros. Risco carcinogênico associado à exposição ao As para adultos pela ingestão de peixes destacou as espécies P. glauca, Salmo spp. e S. brasiliensis como potenciais causadoras de risco carcinogênico. A PCA mostrou que 94,31% da variação dos dados foram explicadas pelos cinco primeiros componentes principais. As contaminações determinadas no Rio Pardo indicam que medidas devem ser adotadas pelas autoridades competentes, visando minimizar os riscos às saúde humana / Chemical compounds of natural and artificial origin are incorporated to human body in different ways, they are ingestion, inhalation and dermal contact. This study aims to quantify the risk to human health from exposure to pesticides and metals detected in Pardo River, Brazil. Data collection campaigns were conducted in 6 points along the Pardo River during rainy and dry periods between 2014 and 2015. Three fish specimens from Pardo River were acquired with fishermen and three specimens were acquired on a Ribeirão Preto, SP, market. The organochlorine insecticides analyzed were pp\'-DDE, pp\'-TDE, pp\'-DDT, ?-BHC, ?-BHC, ?-BHC, heptachlor, heptachlor epoxide, aldrin, dieldrin, endrin, ?-endosulfan, ?-endosulfan and endosulfan sulfate. Herbicides quantified in the water were ametrin, atrazine, deethylatrazine, diuron, hexazinone, metribuzin, simazine and tebuthiuron. Metals quantified in water, sediment and fish were Al, As, Be, Cd, Cr, Cu, Pb, Mn, Hg, Ni, Tl, Sn, V and Zn. Passive sampling was performed with DGT method, for the bioavailable fraction quantification of metals in water. The risk assessment through the exposure to metals and herbicides were considering the residential scenario. DDT and DDD metabolites were detected at levels below to the limits permitted by international thresholds. Herbicides were detected in five of the six sampling points analyzed in the Pardo River, and for atrazine concentrations ranged from 0.16 to 0.32 µg/L, above the levels allowed by the European Union (0.1 µg/L). Metal analyses in water indicated that Al, Cd, Cu, Hg, Mn, Pb and Zn showed concentrations above the limits recommended by Brazilian legislation. The water pH ranged from 5.7 to 7.8. The levels of some metals in sediments were higher in sampling point #1, suggesting punctual source of pollution, probably related to contaminated tributary. The determination of metals in fish indicated that P. glauca showed concentrations above the limits established by Brazilian legislation (7.23 µg/L). Non-carcinogenic risk assessment for water intake indicated that the herbicide levels did not represent risk. For metals, all sampling points both rainy and dry season showed HI>1, and the metal that contributed to the results was Al. The evaluation of carcinogenic risk indicated that all of the six sampling points assessed were above the levels considered acceptable (<10-6 ) during the rainy season. The non-carcinogenic risk assessment associated with fish intake indicated that the species Salmo spp. and P. glauca showed HIs above to the levels considered safe. Carcinogenic risk associated to fish intake indicate that the species P. glauca, Salmo spp. and S. brasiliensis represented potential carcinogenic risk. The PCA showed that 94.3% of the data variation was explained by five main components. Contaminations determined in the Pardo River indicate that measures should be taken by the competent authorities in order to minimize the human health risks

This study assessed the usefulness of multivariate statistical tools to characterize watershed dynamics and prioritize streams for remediation. Three multiple regression models were developed using water quality data collected from Sinking Creek in the Watauga River watershed in Northeast Tennessee. Model 1 included all water quality parameters, model 2 included parameters identified by stepwise regression, and model 3 was developed using canonical discriminant analysis. Models were evaluated in seven creeks to determine if they correctly classified land use and level of fecal pollution. At the watershed level, the models were statistically significant (p < 0.001) but with low r2 values (Model 1 r2 = 0.02, Model 2 r2 = 0.01, Model 3 r2 = 0.35). Model 3 correctly classified land use in five of seven creeks. These results suggest this approach can be used to set priorities and identify pollution sources, but may be limited when applied across entire watersheds.

Hydrological models are powerful tools used to predict water systems behavior such as flow and water level characteristics for rivers and streams. In this research, a fully dynamic 1-D model was developed using the MIKE 11 model for a specific stream called A-014, this stream is in the Savannah River Site (SRS), SC. A field study was conducted in order to collect data needed as inputs for the model development. Data like water velocity and cross-section measurement played a major role in understanding the behavior of the A-014 and the validation of our model. Results showed a correlation capable to predict the water flow of the A-014 stream and how it can be affected by atmospheric events and hydrologic infrastructure. Rain fall events had a big effect in the stream flow by increasing it along many cross-sections. In addition, hydrological infrastructures effected the stream flow by slowing it down and by forming ponds around the culvert and weir which are located in the A-014 stream.

Groundwater-surface water interactions between streams and shallow alluvial aquifers can significantly affect their thermal and chemical regimes and thus are critical for effective management of water resources and riparian ecosystems. Of particular significance is the hyporheic zone, an area delineated by subsurface flow paths that begin and end in surface water bodies. Although detailed work has examined hyporheic flow in the vertical dimension, some studies have suggested that the drop in a stream’s elevation as it flows downstream can laterally extend the hyporheic zone. This study examines intra-meander hyporheic flow using extensive field measurements in a full-scale experimental stream-aquifer system. Synoptic head measurements from 2008 and 2009 and a lithium tracer test were conducted to determine the extent and nature of hyporheic flow within the meander. Permeability was measured and sediment cores were analyzed from 2008 to 2009 to assess aquifer properties. Finally, transient head and temperature measurements were collected during flooding events to assess the sensitivity of intra-meander hyporheic flow and temperature to stream discharge. Results verify that hyporheic flow through meanders occurs, but show that it is sensitive to whether a stream is gaining or losing water to the subsurface overall. In addition, permeability and core grain size results indicate moderate heterogeneity in permeability can occur in aquifers composed of relatively uniform sediment. Results also demonstrate that permeability in alluvial aquifers can evolve through time. Such evolution may be driven by groundwater flow, which transports fine particles from areas where porosity and permeability are relatively high and deposits them where they are relatively low, thus creating a positive feedback loop. Finally, measurements during flooding indicate that steady-state hyporheic flow and the thermal regime within the aquifer are largely insensitive to stream discharge. Together, these results expand upon previous field studies of intra-meander hyporheic flow and verify previous modeling work, although they demonstrate a level of complexity within these systems that should be considered in future work. / text

Magistro darbe tiriama antropogeninės veiklos įtaka Širvintos upės vandens kokybei. Darbo objektas – Širvintos upė (Vilkaviškio rajone) ir jos baseinas. Darbo tikslas – nustatyti ir įvertinti antropogeninės veiklos įtaką Širvintos upės vandens kokybei. Tyrimų metu, nustatyti taršos šaltinius, ir taršos pobūdį Širvintos upės baseine, - taip pat atlikti vandens kokybės stebėjimus. Darbo metodika – taršos šaltiniai ir jos pobūdis Širvintos upės baseine nustatyti analizuojant Vilkaviškio rajono savivaldybės administracijos darbuotojų pateiktą informaciją. Cheminė vandens pavyzdžių analizė atlikta keturis kartus per metus (kartą per sezoną) dešimtyje upės vagos vietų. Vandens kokybė vertinta lyginant gautus cheminės analizės duomenis su DLK vandens telkinyje – priimtuve ir su Paviršinių vandens telkinių, kuriuose gali gyventi ir veistis gėlavandenės žuvys apsaugos reikalavimais. Darbo rezultatai. Širvintos upės baseino pagrindinis taršos šaltinis – žemės ūkis. Baseine 53 % apima dirbama žemė, laikoma 1742 sąlyginių gyvulių, per metus susidaro apie 20287,2 m3 mėšlo, o visame susidariusiame mėšle vidutiniškai – apie 110,5 t azoto. Tyrimu nustatyta, kad Širvintos upė yra vidutiniškai užteršta. Vidutinė metinė skendinčių medžiagų koncentracija 2010 – aisiais 6,9 mg l-1, pagal šį rodiklį upės vanduo – labai geros kokybės. Vidutinis pH ir biocheminis deguonies sunaudojimas, tyrimų laikotarpiu, neviršijo nustatytų normatyvų. Didžiausia leistina amonio koncentracija – 0,78 mg l-1... [toliau žr. visą tekstą] / This Master‘s work researches the influence of anthropological activity to water quality of Sirvinta‘s river. The object of the work – Sirvinta‘s river (Vilkaviškis district) and it‘s reservoir. The aim of the work – ascertine and evaluate the influence of antropological activity to water quality of Sirvint‘s river; define pollution sources and it‘s attribution in the reservoir of Sirvinta‘s river; fullfil the observation of water quality. The method of the work – pollution sources and it‘s attribotion in the reservoir of Sirvinta‘s river are ascertined according to the proposed informatikon of municipality administration of Vilkaviškis district. The chemical water samples‘ analysis is accomplished four times a year (once a season) in ten channels‘ places of the river. The quality of the water is evaluated comparing attained facts of chemical anglysis with DLK in water mines and With surface of water mines, where the freshwater fish can live and pullulate. The results of the work. The main pollution source of Sirvinta‘s river is agriculture. 53 % involve farmland, 1742 – livestock. Muck pompose about 20287,2 m3 per year and about 110,5 t azote are composed from that muck. According to the research, Sirvinta‘s river is polluted on average. The annual material concentration was 6,9 mg l-1 on average in 2010. According to this index the water of the river is very good quality. Medium pH an biochemical oxygen consumption did not execeed the stints. The biggest permissible... [to full text]

Ceramic membrane processes are a rapidly emerging technology for water treatment, yet virtually no information on the performance and fouling mechanisms is available to the industry. Ceramic microfiltration of model feed solutions and a synthetic river water was examined, and a systematic comparison with polymeric counterpart was performed. The results suggested that the models which have been applied to polymeric membranes agreed well with the ceramic membrane filtration data. The fouling was characterized by the initial pore blocking mechanism and transition to the cake filtration mechanism at a later phase. Cake resistance was dominant and readily removable by physical cleaning. The effects of solution chemistry including ionic strength, divalent ion concentration and pH on the flux behavior were comparatively evaluated for ceramic and polymeric ultrafiltration of synthetic water containing model natural organic matter. Experimental evaluations further included resistance-in-series model analysis, organic matter fouling visualization using quantum dots, batch adsorption test, and contact angle measurement, and provided a quantitative a quantitative comparison of fouling characteristics between ceramic and polymeric membranes. The results collectively suggested that the effects of solution chemistry on the fouling behavior with ceramic membranes were mostly similar with polymeric membranes in terms of trends, while the extents varied depending on water quality parameters. Less fouling tendency and better cleaning efficiency were observed with the ceramic membranes, which was a promising finding for ceramic membrane application to surface water treatment. The study further examined a coagulation-ceramic membrane process as a robust option for surface water treatment. The performance of the hybrid system was evaluated using selected surface waters by varying coagulation conditions and types of coagulants. Results suggested that ceramic membranes experienced relatively less fouling and had better cleaning efficiency than polymeric counterpart. The results of this study provide critical information to guide the industry practitioners, consultants, and regulatory agents considering early adoption of this new technology as well as fundamental knowledge upon which further in-depth studies can be built.

Chromium is used in many processing applications, which has led to the formation of chromium(VI) waste. Cr(VI) is an unstable, mobile carcinogen, which is interchangeable with Cr(III) under certain environmental conditions. Management of this waste, however, is often not considered. Mine under investigation is an example of such historic mismanagement. During the second World War, Cr(VI) waste was transferred to the study site from areas where leather products were made for the war effort. This waste was not managed appropriately in the past and with time Cr(VI) leached into the groundwater and possibly surface water resources. As these water resources are used for domestic and agricultural water supply, this may have serious effects on the human and environmental health in the area. Some of the major Cr(VI) effects on human and animal health include malignant tumours, skin irritation, respiratory and reproductive system damage. Lung cancer is of concern when Cr(VI) is inhaled and stomach tumours occur when this chemical pollutant is ingested. The effects of Cr(VI) on plants include the disruption of shoot and root elongation, and if it accumulates enough within the plant can cause ingested health problems for humans and animals. Water quality guidelines state that the Target Water Quality Range for Cr(VI) in drinking water should not exceed 0.05 mg/L. Prolonged exposure of values higher than this target value has adverse health effects and may result in cancer. The study site has a scarcity in water sources and therefore requires good quality water resources. This study aims to identify and use biomarkers to assist in the hydrological characterization of the mine. Available mitigation options can be implemented once it is known how the water in the area moves and distributes Cr(VI) pollution. A biomarker is an indicator of a biological state, which in turn can be used to assist in characterizing the chemical conditions of the sub-surface. Bacteria can aid as environmental biomarkers as they are sensitive and specific to the environmental conditions in which they flourish. In this way they give a good indication of the environmental condition and any possible pollution. Due to the fact that ground- and surface water are integrated resources, it is likely that if one is impacted by pollution, it will indirectly impact the other one. Therefore, the biomarkers identified can be used to characterize water pollutants that are present in ground- and some surface water resources. A description of the study site is provided, wherein the climate, elevation, geology, land use, geohydrology, hydrochemistry and surface water are documented. These factors help to identify and clarify the sources and pathways that water and the pollution would follow. Ten water samples, from surface and groundwater, were obtained in two separate sampling opportunities. The first analysis of the water samples included the determination of the chemical constituents. Two of these constituents analyzed were the total Cr and individual Cr(VI) levels. Six water samples had excessively high Cr values (exceeding the Water Quality Target Range of drinking water and water agricultural use). These values ranged from 0.1 – 3.9 mg/L. The 6 samples with excessive Cr(VI) values were used for the microbial analyses. The microbial analyses consisted of DAPI (4’,6-diamidino-2-phenylindole ) staining, for cell enumeration, and molecular analyses. The molecular analyses included polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE) and sequencing applications concluded in the laboratory. Fifteen bands, representing different organisms, were removed from the DGGE polyacrylamide gel and processed for sequencing. The organisms that were present in the sample were uncultured Cyanobacterium, Sediminibacterium salmoneum, uncultured Bacteroidetes bacterium, uncultured betaproteobacterium, uncultured actinobacterium, uncultured Rhodocyclaceae, uncultured Chloroflexi bacterium and uncultured delta-proteobacterium. According to literature most of these organisms may adapt the ability to either reduce Cr(VI) or resist any effect of Cr(VI) in the environment. Two of the bands were highly unidentified organisms, which means that these organisms have not yet been cultured or identified in any sense. The reason for this is that most microorganisms have not yet been documented. This also makes it difficult to identify the exact bacterial strain present within the samples. The deoxyribonucleic acid (DNA) sequences of the different organisms were very different from each other, when compared by a dendrogram. This means that there was a diverse community present within the samples. Electrical conductivity profiles were conducted in the monitoring boreholes to identify possible fracture positions. The total chromium and chromium(VI) levels were documented and compared. Other chemical factors were analysed and those of high value, such as chloride, nitrate and chromium measurements, were used for statistical analyses and comparison with the biomarkers present in the sample. A positive correlation was found between the sample sites and the organisms present within each. It was noted that different communities have different metabolic activities related to susceptibility and will therefore differ under specific environmental conditions. The microorganisms that were present in the 6 water samples all have the ability to either resist or reduce Cr(VI). This means that in Cr(VI) polluted areas they are more likely to flourish than organisms that do not possess this ability. Such susceptible, non-resistant organisms would otherwise occur naturally in a non-polluted environment. From the obtained results it was noted that microorganisms could aid as biomarkers when determining the environmental condition (with respect to Cr(VI) pollution). The bacteria analysed in the samples all indicate a level of chromium pollution, and aided in the determination of pollution sources. These biomarkers can therefore be used to determine the location of other chromium deposits not yet located. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2013

Chromium is used in many processing applications, which has led to the formation of chromium(VI) waste. Cr(VI) is an unstable, mobile carcinogen, which is interchangeable with Cr(III) under certain environmental conditions. Management of this waste, however, is often not considered. Mine under investigation is an example of such historic mismanagement. During the second World War, Cr(VI) waste was transferred to the study site from areas where leather products were made for the war effort. This waste was not managed appropriately in the past and with time Cr(VI) leached into the groundwater and possibly surface water resources. As these water resources are used for domestic and agricultural water supply, this may have serious effects on the human and environmental health in the area. Some of the major Cr(VI) effects on human and animal health include malignant tumours, skin irritation, respiratory and reproductive system damage. Lung cancer is of concern when Cr(VI) is inhaled and stomach tumours occur when this chemical pollutant is ingested. The effects of Cr(VI) on plants include the disruption of shoot and root elongation, and if it accumulates enough within the plant can cause ingested health problems for humans and animals. Water quality guidelines state that the Target Water Quality Range for Cr(VI) in drinking water should not exceed 0.05 mg/L. Prolonged exposure of values higher than this target value has adverse health effects and may result in cancer. The study site has a scarcity in water sources and therefore requires good quality water resources. This study aims to identify and use biomarkers to assist in the hydrological characterization of the mine. Available mitigation options can be implemented once it is known how the water in the area moves and distributes Cr(VI) pollution. A biomarker is an indicator of a biological state, which in turn can be used to assist in characterizing the chemical conditions of the sub-surface. Bacteria can aid as environmental biomarkers as they are sensitive and specific to the environmental conditions in which they flourish. In this way they give a good indication of the environmental condition and any possible pollution. Due to the fact that ground- and surface water are integrated resources, it is likely that if one is impacted by pollution, it will indirectly impact the other one. Therefore, the biomarkers identified can be used to characterize water pollutants that are present in ground- and some surface water resources. A description of the study site is provided, wherein the climate, elevation, geology, land use, geohydrology, hydrochemistry and surface water are documented. These factors help to identify and clarify the sources and pathways that water and the pollution would follow. Ten water samples, from surface and groundwater, were obtained in two separate sampling opportunities. The first analysis of the water samples included the determination of the chemical constituents. Two of these constituents analyzed were the total Cr and individual Cr(VI) levels. Six water samples had excessively high Cr values (exceeding the Water Quality Target Range of drinking water and water agricultural use). These values ranged from 0.1 – 3.9 mg/L. The 6 samples with excessive Cr(VI) values were used for the microbial analyses. The microbial analyses consisted of DAPI (4’,6-diamidino-2-phenylindole ) staining, for cell enumeration, and molecular analyses. The molecular analyses included polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE) and sequencing applications concluded in the laboratory. Fifteen bands, representing different organisms, were removed from the DGGE polyacrylamide gel and processed for sequencing. The organisms that were present in the sample were uncultured Cyanobacterium, Sediminibacterium salmoneum, uncultured Bacteroidetes bacterium, uncultured betaproteobacterium, uncultured actinobacterium, uncultured Rhodocyclaceae, uncultured Chloroflexi bacterium and uncultured delta-proteobacterium. According to literature most of these organisms may adapt the ability to either reduce Cr(VI) or resist any effect of Cr(VI) in the environment. Two of the bands were highly unidentified organisms, which means that these organisms have not yet been cultured or identified in any sense. The reason for this is that most microorganisms have not yet been documented. This also makes it difficult to identify the exact bacterial strain present within the samples. The deoxyribonucleic acid (DNA) sequences of the different organisms were very different from each other, when compared by a dendrogram. This means that there was a diverse community present within the samples. Electrical conductivity profiles were conducted in the monitoring boreholes to identify possible fracture positions. The total chromium and chromium(VI) levels were documented and compared. Other chemical factors were analysed and those of high value, such as chloride, nitrate and chromium measurements, were used for statistical analyses and comparison with the biomarkers present in the sample. A positive correlation was found between the sample sites and the organisms present within each. It was noted that different communities have different metabolic activities related to susceptibility and will therefore differ under specific environmental conditions. The microorganisms that were present in the 6 water samples all have the ability to either resist or reduce Cr(VI). This means that in Cr(VI) polluted areas they are more likely to flourish than organisms that do not possess this ability. Such susceptible, non-resistant organisms would otherwise occur naturally in a non-polluted environment. From the obtained results it was noted that microorganisms could aid as biomarkers when determining the environmental condition (with respect to Cr(VI) pollution). The bacteria analysed in the samples all indicate a level of chromium pollution, and aided in the determination of pollution sources. These biomarkers can therefore be used to determine the location of other chromium deposits not yet located. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2013

A quantitative understanding of ground water flow characteristics in unconfined aquifers is important because of the prevalence of abstraction from, and pollution of these systems. The current understanding of ground water flow in unconfined aquifers is limited because of the dominance of horizontal flow modelling strategies used to represent unconfined flow processes. The application of horizontal flow principles leads to an ignorance of seepage-face formation and can not predict the complicated three-dimensional nature of the ground water flow that dominates at the ground water-surface water interface. This study aims to address some of these deficiencies by exploring the true three-dimensional nature of ground water flow including the formation of seepage faces at the ground water-surface water interface using numerical and laboratory techniques. A finite element model for simulating two-dimensional (vertical) variably saturated flow is developed and benchmarked against standard laboratory and field-scale solutions. The numerical features of the finite element model are explored and compared to a simple finite difference formulation. The comparison demonstrates how finite element formulations lead to a broader spatial averaging of material properties and a different method for the representation of specified flux boundaries. A detailed comparison analysis indicates that these differences in the finite element solution lead to an improved approximation to the partial differential equation governing two-dimensional (vertical) variably saturated flow. A laboratory analysis of unconfined ground water flow and associated solute transport characteristics was performed. The analysis focused upon unconfined flow towards a pumping well. The laboratory observations were reliably reproduced using a three-dimensional (axi-symmetric), variably saturated ground water flow model. The model was benchmarked against the ground water flow characteristics such as the seepage-face height and total flow rate. In addition, the model was shown to reliably reproduce the solute transport features such as travel times and streamline distributions. This is the first time that a numerical model has been used to reliably reproduce the solute transport characteristics near a seepage-face boundary where the three-dimensional flow effects are prevalent. The ability to reliably predict solute transport patterns in the seepage-face zone is important since this region is known to support vital microbially facilitated reactions that control nutrient cycling and contaminant attenuation. The three-dimensional travel time distribution near the seepage-face was compared to that predicted using a horizontal flow modelling approach derived from the basic Dupuit-Forchheimer equations. The Dupuit-Forchheimer based model indicated that horizontal flow modelling would under-estimate the total residence time near a seepage-face boundary, thereby introducing a considerable source of error in a solute transport analysis. For this analysis, a new analytical solution for the steady travel time distribution in an unconfined aquifer subject to a single pumping well was derived. The analytical model has identified, for the first time in the hydrogeology literature, the use of the imaginary error function. The imaginary error function is a standard transcendental function and an infinite series approach to evaluate the function was successfully proposed. The two-dimensional (vertical) ground water flow model was extended to handle the case where the flow is driven by density gradients near the ground water-surface water interface. The unsteady, two-dimensional, Galerkin finite element model of density-dependent ground water flow in variably saturated porous media is rigorously presented and partially benchmarked under fully saturated (confined) conditions. The partial benchmarking involved reproducing solutions to the standard Henry salt-water intrusion and the Elder salt-convection problems. The model was used in a standard density-coupled and a new density-uncoupled mode to elucidate the worthiness of the Henry and Elder problems as benchmark standards. A comparison of the coupled and uncoupled solutions indicates that the Henry salt-water intrusion problem has limited worthiness as a benchmark as the patterns of ground water flow are relatively insensitive to density-coupled effects. Alternatively, the Elder problem is completely dependent upon a correct representation of the density-coupled flow and solute transport processes. The coupled versus uncoupled comparison is proposed as a new test of the worthiness of benchmark standards. The Henry salt-water intrusion problem was further analysed in an attempt to alleviate some of the difficulties associated with this benchmark problem. The numerical model was tested against a re-evaluated version of Henry's semi-analytical solution for the coupled solute concentration distribution. The numerical model was used to propose a modified version of the Henry problem where the importance of density-coupled processes was increased. The modified problem was shown to have an improved worthiness as compared to the standard solution. The numerical model results were benchmarked against a new set of semi-analytical results for the modified problem. Certain advantages in using the modified problem as a test case for benchmarking the results of a numerical model of density-dependent ground water flow are identified. A numerical investigation of the patterns of density-driven ground water flow at the ground water-surface water interface was undertaken. The numerical model is shown to produce grid-independent results for a finely discretised domain. The pattern of discharge is controlled, in part, by two parameters. One describes the recharge applied to the aquifer, and the second describes the magnitude of the density differences between the fresh recharging fluid and the saline receiving fluid. The influence of dense intrusions upon the formation of seepage-face boundaries at the ground water-surface water interface under steady-state conditions was also investigated. Dense intrusions are shown to dominate the pattern of ground water flow only under mild recharge conditions, while seepage faces dominate the outflow pattern under strong recharge conditions. Therefore, the formation of seepage-face boundaries and dense intrusions are unlikely to coincide under the conditions examined in this study.

Sewage misconnections currently pose severe threats to water quality especially in urban areas in the UK. These misconnections lead to the discharge of untreated wastewater into receiving watercourses via surface water outfalls. Regular discharges from this source could lead to these watercourses failing to meet standards set by the Water Framework Directives. Despite the impacts resulting from this urban diffuse pollutant source, research into this area is limited. The study area is the River Lee, which is known to experience issues with water quality especially within the heavily urbanized lower Lee section. Misconnections are one of the major contributors to the poor water quality status of the River. In this study, the Lee was investigated using several parameters. The approach involved the monitoring of coliform bacteria to detect outfalls where misconnections were likely, then biofilm samples below selected outfalls were used for both clean and polluted sites to look for community types. Results showed severe pollution within some sections of the River particularly within the lower Lee. Pymmes Brook was used as a case study, both coliform bacteria and biofilm communities below outfalls were further investigated for clean and polluted sites. Results from the Pymmes Brook study also showed that this watercourse was experiencing severe issues with water quality, with elevated levels of coliform bacteria identified below polluted outfalls. Biofilm community data obtained during the pilot and experimental phases of study were analyzed using a range of multivariate techniques. Results of the analysis showed consistent x patterns in community structure within sites with similar water quality, with indicator species identified. Communities below polluted outfalls were composed mainly of species tolerant of organic pollution thus indicating a response of communities to misconnection discharges. Currently, the identification of misconnections are carried out through trackbacks, a process which is expensive and time consuming. During this study an inexpensive and rapid approach is proposed for assessing misconnections within a catchment. Using this method, misconnection hotspots are mapped out using coliform bacteria and biofilm communities. Using catchment data and predicted coliform bacteria from enumerated counts, misconnections within these hotspots are assessed. Having tested this approach on Pymmes Brook, a tributary of the River Lee, the results obtained were promising. Pending further verification, this system provides an economical and rapid tool for the assessment of misconnections within a catchment.