The present study evaluates the surface water quality in the canals of An Giang province in the period from 2009 to 2016. The results showed that surface water of the canals was contaminated by organic matter and microorganisms which makes it not suitable for water supply and conservation of aquatic life. The water quality parameters such as dissolved oxygen (DO), biological oxygen demand (BOD), total suspended solids (TSS), orthophosphate (P-PO43-) and coliforms levels in the wet season were found to be higher than those in the dry season. The problem of organic and microorganic pollution over a long period of time without solutions leads to declines in water quality and then quantity as well. Agriculture is the main activity contributing to pollution of surface water in interior canals along with the activities of daily life, industry and services. This causes pollution of the surface water on Hau River due to its exchange of water with the connected canals. Good agricultural practices should be implemented to limit the pollution of surface water resources of the Mekong Delta. / Nghiên cứu này nhằm đánh giá diễn biến chất lượng nước mặt trong các kênh rạch nội đồng của tỉnh An Giang trong giai đoạn 2009 – 2016. Kết quả cho thấy nước mặt tại các kênh rạch nội đồng đã ô nhiễm hữu cơ và vi sinh vật. Nguồn nước không phù hợp cho mục đích cấp nước sinh hoạt và bảo tồn thực vật thủy sinh. Các chỉ tiêu như hàm lượng oxy hòa tan (DO), nhu cầu oxy sinh hóa (BOD), tổng chất rắn lơ lửng (TSS), orthophosphate (P-PO43-) và coliforms trong mùa mưa cao hơn mùa khô. Vấn đề ô nhiễm hữu cơ và vi sinh vật diễn ra trong thời gian dài và chưa có giải pháp xử lý làm cho chất lượng nước suy giảm dẫn đến suy giảm về trữ lượng. Nông nghiệp là hoạt động chính góp phần làm ô nhiễm nguồn nước mặt trong các kênh rạch nội đồng bên cạnh các hoạt động sinh hoạt, công nghiệp và dịch vụ. Điều này dẫn đến nước mặt trên sông Hậu cũng có đặt tính ô nhiễm tương tự do trao đổi nước với các kênh rạch nội đồng. Thực hành sản xuất nông nghiệp thân thiện môi trường cần sớm được triển khai để hạn chế ô nhiễm nguồn nước mặt quan trọng của khu vực đồng bằng sông Cửu Long.

No description available.

No description available.

<p dir="ltr">Alpine glacier meltwater is an important source of recharge supporting groundwater flow processes in the high mountains. In the face of rapid ice loss, knowledge of response times of mountain aquifers to loss of glacial ice is critical in evaluating the sustainability of alpine water resources for human communities and alpine ecosystems. Glaciers are very sensitive to changes in climate, they advance during periods of global or regional cooling, and they retreat in response to global or regional warming conditions. When the glaciers grow, the equilibrium-line altitude separating the zone of accumulation and zone of ablation on the glacier moves downslope; it moves upslope when they retreat. The latter is not a sustainable condition for the glacier. Previous studies have shown that glacial meltwater is an important source of groundwater recharge. However, we lack fundamental information on the importance of glacial meltwater in mountain groundwater processes such as supporting baseflow generation to alpine streams, perennial flow to alpine springs, and the geochemical evolution of groundwater in mountain aquifers. Thus, continued glacial ice loss may have severe consequences for alpine hydrological and hydrogeological systems.</p><p dir="ltr">Glacier National Park (GNP) and Mount Hood National Forest (MH), both have alpine glaciers. These two study sites show different responses to climate change since their glaciers are in different states of retreat. GNP glaciers are in advanced stages of retreat compared to MH glaciers. Groundwater samples were collected from springs, seasonal snow, glacial ice, and glacial melt (subglacial flow) in GNP and MH. The samples were analyzed for a suite of environmental isotopes and geochemical tracers to address the following questions: 1) How are isotopic fingerprints of glacial meltwater preserved in mountain-block aquifers? What does the isotopic fingerprint of subglacial flow tell us about melting, meltwater processes, and mixing processes? 2) Is the preservation of the isotopic fingerprint of glacial meltwater affected by aspect controls on ice preservation? Aspect is defined as the compass direction of the slope where the glacier is found. 3) What controls groundwater flow and flowpath connectivity from high elevations (near glacier) to lower elevations? What geologic units support groundwater flow to local- and regional-scale springs and flowpath connectivity across spatial scales in each study site?</p><p dir="ltr">The flow of groundwater in mountainous terrain is heavily dependent on the hydraulic properties of the bedrock including presence/absence of dipping layers and structural features, primary and secondary porosity, and presence/absence of ongoing tectonic activity. Strontium isotopes (⁸⁷Sr/⁸⁶Sr) were used to identify the rock units that host groundwater flowpaths and to quantify flowpath connectivity across spatial scales in both study sites. The ⁸⁷Sr/⁸⁶Sr data show that flowpaths in GNP are primarily hosted in the Helena Formation and permeable facies in the Snowslip Formation. Groundwater also flows through alluvium and younger bedrock units, and there is some flow along or through the volcanic sill in the Helena Formation. Hydrostratigraphy also affects groundwater flow and the spatial distribution of alpine springs in GNP. At MH, the rock units hosting flowpaths are young reworked volcanic rock units that are Quaternary in age. Flowpaths in MH appear to be connected across spatial scales since warm springs emerging along the lower southern slopes of Mount Hood preserve stable isotopic signatures of glacial meltwater. In comparison, nearly all the sampled springs in GNP emerge on south-facing slopes. This is not an indication of ice preservation, instead it’s controlled by hydrostratigraphy. In fact, it’s unlikely that high-elevation groundwater is strongly connected to low-elevation sites due to hydrostratigraphy. There are more springs on south-facing slopes at MH as well; however, they do not preserve an isotopic signature of recharge from glacial meltwater except for the warm springs. Springs on north-facing slopes in MH, however, do preserve the signature.</p><p dir="ltr">Tritium (³H) and chlorine-36 (³⁶Cl/Cl) were measured to assess how the isotopic fingerprint of glacial meltwater is preserved in mountain aquifers. The ³H activities in spring water are elevated in GNP and it’s difficult to differentiate between modern precipitation and glacial meltwater. Tritium activities are lower in MH, but it’s also difficult to differentiate between potential endmembers. This discrepancy could imply that glacial meltwater doesn’t contribute to groundwater recharge, but this doesn’t support the Bayesian stable isotope mixing model results of an earlier study. Instead, I infer that englacial mixing processes are affecting the isotopic fingerprint of subglacial melt. An englacial mixing model (EMM) was developed to explain how the isotopic fingerprint of subglacial flow (glacial meltwater) changes in relation to the stage of retreat. The stage of retreat is important because it controls the proportion of glacial meltwater to runoff from snowmelt and rain that enters the englacial network from the surface of the glacier. Mixing occurs in the englacial network, and the mixed water is transported to the base of the glacier. Englacial mixing in conduits, fractures, and moulins affects the ³H and ³⁶Cl/Cl fingerprint of subglacial flow and will, in turn, affect the isotopic fingerprint of recharge from glacial meltwater. For this study, the ³H is not robust by itself; however, ³⁶Cl/Cl shows some additional benefits over ³H. The EMM suggests that the impact of englacial mixing and the influence of modern precipitation on the isotopic composition of subglacial flow increases as the glacier retreats in both GNP and MH. This model is novel to the best of our knowledge. Additional testing of the EMM should be prioritized in the near future.</p>

Water Quality Management is one of the critical challenges currently facing South Africa. The triad of water resource management, socio- economic development and environmental sustainability are key issues that require balance and compromise. The effects of anthropogenic activities on the Blesbokspruit catchment were examined. Water samples were collected from nine strategically selected sites along the stream for a period of ten months in six weekly intervals and analysed for physio-chemical, selected trace metals and microbial entities. Results revealed that variables of concern were Electrical Conductivity (EC), Total Suspended Solids (TSS), Nitrates, Phosphates, Sulphates and Chemical Oxygen Demand (COD). Mean levels of these parameters in this order ranged from 93.0-146.63mS/m; 11.25-39mg/L; 0.16-2.01mg/L; 0.5-0.96mg/L; 118.63-379.5mg/L and 15.0-34.0mg/L respectively. Levels of E. coli and F. coliforms also ranged from 19.13- 43999.125 cfu/100mL and 20.63-16878.5 cfu/100mL respectively which were of concern. Levels of analysed trace metals were tolerable except for Fe with a range of 0.04- 0.73mg/L. Generally, the results from this study indicate that the river is contaminated and therefore not suitable for direct human consumption as well as for irrigation purposes.

Aquifers in the arid alluvial basins of the southwestern U.S. are recharged predominantly by infiltration from streams within the basins and by water entering along the margins of the basins from surrounding mountains (mountain -front recharge). The Tucson Basin of Southeastern Arizona is such a basin. The Santa Catalina Mountains form the northern boundary of this basin and receive more than twice as much precipitation (about 70 cm/yr) as the basin does (about 30 cm/yr). In this study environmental isotopes were employed to investigate the migration of precipitation basinward through joints and fractures. Water samples were obtained from springs in the Santa Catalina Mountains. Stable isotopes and thermonuclear bomb-produced tritium enabled qualitative characterizations of flow paths and flow velocities. Stable isotopic measurements fail to display a direct altitude effect. Tritium values indicate that although a few springs discharge pre-bomb water, most springs discharge waters from the 1960's or later.

Les agents anti-infectieux sont utilisés pour traiter ou prévenir les infections chez les humains, les animaux, les insectes et les plantes. L’apparition de traces de ces substances dans les eaux usées, les eaux naturelles et même l’eau potable dans plusieurs pays du monde soulève l’inquiétude de la communauté scientifique surtout à cause de leur activité biologique. Le but de ces travaux de recherche a été d’étudier la présence d’anti-infectieux dans les eaux environnementales contaminées (c.-à-d. eaux usées, eaux naturelles et eau potable) ainsi que de développer de nouvelles méthodes analytiques capables de quantifier et confirmer leur présence dans ces matrices. Une méta-analyse sur l’occurrence des anti-infectieux dans les eaux environnementales contaminées a démontré qu’au moins 68 composés et 10 de leurs produits de transformation ont été quantifiés à ce jour. Les concentrations environnementales varient entre 0.1 ng/L et 1 mg/L, selon le composé, la matrice et la source de contamination. D’après cette étude, les effets nuisibles des anti-infectieux sur le biote aquatique sont possibles et ces substances peuvent aussi avoir un effet indirect sur la santé humaine à cause de sa possible contribution à la dissémination de la résistance aux anti-infecteiux chez les bactéries. Les premiers tests préliminaires de développement d’une méthode de détermination des anti-infectieux dans les eaux usées ont montré les difficultés à surmonter lors de l’extraction sur phase solide (SPE) ainsi que l’importance de la sélectivité du détecteur. On a décrit une nouvelle méthode de quantification des anti-infectieux utilisant la SPE en tandem dans le mode manuel et la chromatographie liquide couplée à la spectrométrie de masse en tandem (LC-MS/MS). Les six anti-infectieux ciblés (sulfaméthoxazole, triméthoprime, ciprofloxacin, levofloxacin, clarithromycin et azithromycin) ont été quantifiés à des concentrations entre 39 et 276 ng/L dans les échantillons d’affluent et d’effluent provenant d’une station d’épuration appliquant un traitement primaire et physico- chimique. Les concentrations retrouvées dans les effluents indiquent que la masse moyenne totale de ces substances, déversées hebdomadairement dans le fleuve St. Laurent, était de ~ 2 kg. En vue de réduire le temps total d’analyse et simplifier les manipulations, on a travaillé sur une nouvelle méthode de SPE couplée-LC-MS/MS. Cette méthode a utilisé une technique de permutation de colonnes pour préconcentrer 1.00 mL d’échantillon dans une colonne de SPE couplée. La performance analytique de la méthode a permis la quantification des six anti-infectieux dans les eaux usées municipales et les limites de détection étaient du même ordre de grandeur (13-60 ng/L) que les méthodes basées sur la SPE manuelle. Ensuite, l’application des colonnes de SPE couplée de chromatographie à débit turbulent pour la préconcentration de six anti-infectieux dans les eaux usées a été explorée pour diminuer les effets de matrice. Les résultats obtenus ont indiqué que ces colonnes sont une solution de réchange intéressante aux colonnes de SPE couplée traditionnelles. Finalement, en vue de permettre l’analyse des anti-infectieux dans les eaux de surface et l’eau potable, une méthode SPE couplée-LC-MS/MS utilisant des injections de grand volume (10 mL) a été développée. Le volume de fuite de plusieurs colonnes de SPE couplée a été estimé et la colonne ayant la meilleure rétention a été choisie. Les limites de détection et de confirmation de la méthode ont été entre 1 à 6 ng/L. L’analyse des échantillons réels a démontré que la concentration des trois anti-infectieux ciblés (sulfaméthoxazole, triméthoprime et clarithromycine) était au dessous de la limite de détection de la méthode. La mesure des masses exactes par spectrométrie de masse à temps d’envol et les spectres des ions produits utilisant une pente d’énergie de collision inverse dans un spectromètre de masse à triple quadripôle ont été explorés comme des méthodes de confirmation possibles. / Anti-infectives are used to treat or prevent infections in humans, animals, insects and plants. The occurrence of traces of these substances in wastewaters, natural waters and even drinking water has caused concern among the scientific community especially because of their biological activiy. The goal of this research was to study the occurrence of anti-infectives in contaminated environmental waters (wastewaters, natural waters, and drinking water) and to develop new analytical methods able to quantitate and confirm their presence in these matrices. A meta-analysis on the occurrence of anti-infectives in contaminated environmental waters demonstrated that at least 68 parent compounds and 10 transformation products have been quantified to date. Environmental concentrations vary between 0.1 ng/L and 1 mg/L depending on the compound, the matrix and the source of contamination. According to this study, detrimental effects of anti-infectives on aquatic biota are possible and these substances could also affect indirectly human health because of their possible contribution to the dissemination of antibiotic resistance in bacteria. Preliminary tests on the development of a method of determination of anti-infectives in wastewaters showed the main difficulties to overcome during solid-phase extraction (SPE) as well as the importance of the detector selectivity. A novel method of determination of anti-infectives was described using off-line tandem SPE and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Six target anti-infectives (sulfamethoxazole, trimethoprim, ciprofloxacin, levofloxacin, clarithromycin and azithromycine) were quantitated at concentrations between 39 and 276 ng/L in samples of influent and effluent collected from a primary and physico-chemical wastewater treatement plant. Reported effluent concentrations indicate that the mean mass of these substances discharged daily in the St. Lawrence River was ~ 2 kg. In order to reduce total analysis time and simplify sample preparation, a new on-line SPE-LC-MS/MS was presented. This method used a column-switching technique to preconcentrate 1.00 mL of sample in an on-line SPE column. Method analytical performance allowed the quantitation of six anti-infectives in municipal wastewaters and limits of detection were of the same magnitude (13-60 ng/L) than methods based in offline SPE. Next, the application of turbulent flow chromatography on-line SPE columns for the preconcentration of six anti-infectives in wastewaters was explored. Results showed that these columns are an interesting alternative to traditional on-line SPE columns. Finally, in order to allow analysis of anti-infectives in surface and drinking water, we developed an on-line SPE-LC-MS/MS method using large-volume injections (10 mL). Breakthrough volumes of several on-line SPE columns were estimated and the column having the best retention, Strata-X, was chosen. Method detection and confirmation limits were between 1 and 6 ng/L. Analysis of real samples indicated that the concentration of the three target anti-infectives (sulfamethoxazole, trimethoprim and clarithromycin) was lower that the method detection limits. Accurate mass measurement by time-of-flight mass spectrometry and product ion spectra obtained by a reversed-energy ramp in a triple quadrupole mass spectrometer were explored as alternative confirmation methods.

Water Quality Management is one of the critical challenges currently facing South Africa. The triad of water resource management, socio- economic development and environmental sustainability are key issues that require balance and compromise. The effects of anthropogenic activities on the Blesbokspruit catchment were examined. Water samples were collected from nine strategically selected sites along the stream for a period of ten months in six weekly intervals and analysed for physio-chemical, selected trace metals and microbial entities. Results revealed that variables of concern were Electrical Conductivity (EC), Total Suspended Solids (TSS), Nitrates, Phosphates, Sulphates and Chemical Oxygen Demand (COD). Mean levels of these parameters in this order ranged from 93.0-146.63mS/m; 11.25-39mg/L; 0.16-2.01mg/L; 0.5-0.96mg/L; 118.63-379.5mg/L and 15.0-34.0mg/L respectively. Levels of E. coli and F. coliforms also ranged from 19.13- 43999.125 cfu/100mL and 20.63-16878.5 cfu/100mL respectively which were of concern. Levels of analysed trace metals were tolerable except for Fe with a range of 0.04- 0.73mg/L. Generally, the results from this study indicate that the river is contaminated and therefore not suitable for direct human consumption as well as for irrigation purposes.

Compte tenu de l’évolution démographique et climatique planétaire, la gestion de la ressource en eau constitue un défi majeur auquel la communauté internationale devra faire face au cours du XXIème siècle. A cet effet, l'identification de la continuité hydrique entre les eaux de surface et les eaux souterraines permet l'introduction de la notion de gestion intégrée de la ressource. L'application de ce principe de gestion au bassin de la Seine, à travers l'estimation des échanges nappe-rivière, est rendue possible par la mise en pratique du concept d'interface nappe-rivière emboitées au sein de travaux de modélisation. Pour cela une procédure de modélisation multi-échelles peut être mise en place. Elle vise à intégrer des informations locales au sein de modélisation à une échelle supérieure. Dans ce mémoire, une procédure de modélisation multi-échelles est mise en œuvre. Ce protocole de modélisation est initié par une estimation des flux d'eau régionaux au sein de l'hydrosystème Seine. La cohérence globale de ces flux est garantie par le développement d'une méthodologie de calibration de modèles couplés en deux étapes. Ensuite les informations locales, que sont les hétérogénéités de la plaine alluviale de la Bassée et de la représentation des interfaces nappe-rivière du réseau secondaire, sont intégrées au modèle régional par une procédure de modélisation emboitée et de changement d'échelle des paramètres hydrauliques. La mise en place de cette procédure a finalement permis l'estimation fine des échanges nappe-rivière sur la quasi-totalité (83%) du réseau hydrographique naturel du bassin de la Seine et ainsi de répondre aux recommandations de gestion intégrée de la ressource faites par la directive cadre sur l'eau. / Given the current climate and anthropogenic evolutions, water management becomes one of the greatest challenges of the 21st Century. For that purpose, by identifying hydraulic continuity between surface and subsurface water, the concept of integrated water management can be introduced. In this work this management concept is applied on the Seine basin by quantizing hydrological processes occuring at the nested stream-aquifer interface. The implementatin of the nested interface concept can bedone through multi-scale modeling. This modelling procedure, aimed at embody the local characteristics of the interfaces (such as structural or hydrodynamic heterogeneities) in large scale models. A multi-scale modelling procedures is applied to the regional Seine basin model (70000 km²) in order, to study the hydrodynamic behaviour of the Bassée alluvial plain, and to quantify the stream-aquifer exchanged fluxes at the basin scale. The modelling protocol is initiated with regionals fluxes estimation over Seine hydrosystem. Regional fluxes consistency are assured by a two-step calibration procedure of fully coupled models. Then, the local characteristics of the Bassée alluvial plain, are implemented in the regional model by nested modelling methodology associated with upscaling procedure of hydraulics properties. Finally, the multi-scale modelling procedure lead to quantify distributed stream-aquifer exchanged water fluxes over 83% of the natural river network of the Seine basin, and thus, achieve to answer the integrated water resources management recommandations of the water framework directive.

Die Arbeit besteht aus mehreren Studien zur Quantifizierung des Grundwasserstroms in Seen (Exfiltration; engl.: lacustrine groundwater discharge, LGD) und damit verbundener Nährstoffeinträge. In zwei einleitenden Kapiteln dieser Arbeit werden eine Gründe für die Vernachlässigung der Grundwasserexfiltration (LGD) in Seen und der daran gekoppelten Nährstoffeinträge identifiziert. Diese Literaturstudien fassen den aktuellen Kenntnisstand zum Einfluss des Grundwassers auf die Hydrologie von Seen und ihre Nährstoffhaushalte zusammen. Den Kern der vorliegenden Arbeit bilden zwei empirische Studien, die sich mit der Quantifizierung der grundwasserbürtigen Phosphor (P)-Fracht in den Arendsee in Deutschland befassen. Das Gesamtvolumen des Grundwasserzustroms wird basierend auf der Grundwasserneubildung im Einzugsgebiet des Sees ermittelt. Lokale Muster der Grundwasserexfiltration werden anhand von Temperaturtiefenprofilen des Seesediments bestimmt. Eine Kombination der Ergebnisse ermöglicht es, die quantitativen Daten mit lokalen Informationen zu unterstützen. Die Untersuchung der Grundwasserqualität zeigt, dass die P-Konzentrationen im Grundwasser im besiedelten Bereich teilweise stark erhöht sind. Als Konsequenz daraus haben die grundwasserbürtigen P-Frachten einen Anteil von mehr als 50% an der gesamten externen P-Last des Arendsees. Das Grundwasser ist damit eine maßgebliche Ursache für die Eutrophierung des Gewässers. Drei weitere Studien widmen sich der Entwicklung und Optimierung von Ansätzen zur qualitativen und quantitativen Bestimmung der Grundwasserexfiltration in Seen. Die kritische Auseinandersetzung mit den Ergebnissen der Studien zeigt die Notwendigkeit weiterer Forschung zur Verbesserung und Standardisierung der Methoden zur Bestimmung von LGD und damit verbundenen Stofftransporten auf. Der Fall des Arendsees sollte alle, Wissenschaftler und Praktiker, dazu motivieren, das Grundwasser als relevante Eutrophierungsquelle in Betracht zu ziehen. / The present work is a collection of studies on lacustrine groundwater discharge (LGD) and groundwater-borne phosphorus (P) loads. For a number of reasons, groundwater exfiltration (i.e., LGD) is often not considered in water and nutrient budgets of lakes. This is also and especially true for P which was often regarded to be immobile in groundwater until recently. Two chapters review the scientific literature regarding the impacts of groundwater on hydrology and nutrient budgets of lakes, respectively. They present mechanisms and processes of LGD as well as techniques and methods to measure LGD and related nutrient transports. Moreover, numbers of LGD volumes and loads reported in literature are presented. The core of the present work is represented by two case studies dealing with the quantification of P loads from LGD to a lake in Germany. A combination of different methods is applied to overcome the problem of quantitative large scale LGD determination without losing local spatial information. P concentrations in groundwater and LGD are investigated by detailed spatial water sampling. The results reveal that P is actually present in concentrations far above natural background concentrations in the urban groundwater. LGD-derived P loads account for more than 50% of the overall external P loads to the lake and by that contribute significantly to lake eutrophication. Three further studies are devoted to the development and improvement of approaches to determine LGD. Critical reviews of the above mentioned studies reveal the need for further research in order to standardize and improve methods for LGD and mass load determination. It is found that the appropriate method for LGD determination depends on the spatial scale of interest. The identification of P introduced by LGD as a main driver of lake eutrophication is an important finding which should encourage scientists, policy makers, and lake managers to consider groundwater as a relevant P source for lakes.