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Large inputs of groundwater and associated fluxes of alkalinity and nutrients into Jiaozhou Bay, China | Grands apports d’eau souterraine et de flux associés d’alcalinité et de nutriments dans la baie de Jiaozhou, Chine Aportes de agua subterránea y flujos asociados a la alcalinidad y nutrientes en la Bahía de Jiaozhou, China 中国胶州湾地下水和相关的碱度和营养盐的大量排入 Grandes entradas de águas subterrâneas e fluxos associados de alcalinidade e nutrientes na Baía de Jiaozhou, China Полный текст
2020
Zhang, Yan | Wang, Jerry H. C. | Li, Hailong | Song, Dehai
Submarine groundwater discharge (SGD) as a major source of alkalinity has rarely been studied in Jiaozhou Bay, China. The presented study used radon (²²²Rn) and radium isotopes to investigate SGD and its influence on alkalinity and nutrient inputs into the bay. Time-series observations of ²²²Rn were used to quantify groundwater dynamics over tidal time scales and the results showed that the SGD rates at point-scale were 0–67.2 (mean: 17.8) cm/day and 0–43.6 (mean: 12.3) cm/day in wet and dry seasons, respectively. Using radium mass balance models, the SGD in the whole bay was estimated to be (1.29–2.60) × 10⁷ m³/day in wet season and (5.81–6.83) × 10⁶ m³/day in dry season. Thus, both sets of results indicated higher SGD fluxes in wet season than in dry season. Such a seasonal variation pattern suggests a rapid response to local precipitation. The alkalinity fluxes associated with SGD were generally greater than those from the local rivers. Among the nutrient sources, SGD contributed about 63, 24 and 37% of total dissolved inorganic nitrogen, reactive phosphorus and silicate inputs, respectively. These results demonstrated that groundwater seepage is a major factor driving alkalinity and nutrients (especially dissolved inorganic nitrogen) into Jiaozhou Bay. SGD may have an important influence on the budgets of elements (C, N, P) and ecological environments in coastal waters.
Показать больше [+] Меньше [-]Assessment of groundwater recharge for a coarse-gravel porous aquifer in Slovenia | Evaluation de la recharge des eaux souterraines pour un aquifère poreux constitué de graviers grossiers en Slovénie Evaluación de la recarga de aguas subterráneas para un acuífero poroso de grava gruesa en Eslovenia 斯洛文尼亚粗砾孔隙含水层的地下水补给评价 Análise da recarga da água subterrânea para um aquífero poroso de cascalho grosso na Eslovênia Ocena napajanja podzemne vode za debelozrnati medzrnski vodonosnik v Sloveniji Полный текст
2020
Zupanc, Vesna | Bračič Železnik, Branka | Pintar, Marina | Čenčur Curk, Barbara
Research into the unsaturated zone and groundwater recharge can greatly improve understanding of hydrological processes and assist in sustainable groundwater management. Groundwater recharge of the Ljubljana Field aquifer, a coarse-gravel porous aquifer in Slovenia, was estimated with reference to soil characteristics, outflow data from a weighing lysimeter, and water-table fluctuation. The specific yield of the upper unsaturated zone determined from soil characteristics was 0.141 for the top soil layer (0–0.35 m), between 0.042 and 0.066 for the layer below the top soil (0.35–1.3 m), and between 0.239 and 0.219 for the underlying upper coarse layer. During long dry periods, especially in combination with times of high plant-water requirements, only substantial precipitation events directly contribute to considerable groundwater recharge, as ‘substantial precipitation’ is defined as those rainfall events that fill storage and exceed retention capacity of the upper soil layer. Lysimeter measurements show that 50% of the precipitation is lost by evapotranspiration and the other 50% contributes to groundwater recharge. Most infiltrated water was stored for a short time in the unsaturated zone and did not result in a significant discharge from the lysimeter. Average specific yield, calculated using the water-table fluctuation method, was 0.144. The nature of the gravely unsaturated zone is that once the retention buffer of the soil is exceeded, the water front travels through relatively quickly, which can be seen as an advantage for recharge or a disadvantage for prevention of groundwater pollution.
Показать больше [+] Меньше [-]Evolution and assessment of a nitrate vulnerable zone over 20 years: Gallocanta groundwater body (Spain) | Evolution et évaluation d’une zone vulnérable au nitrate sur 20 ans: masse d’eau souterraine de Gallocanta (Espagne) Evolución y evaluación de una zona vulnerable a nitratos a lo largo de 20 años: la masa de agua subterránea de Gallocanta (España) 西班牙Gallocanta地下水体硝酸盐脆弱区20年的演变和评估 Evolução e avaliação de uma a zona vulnerável ao nitrato ao longo de 20 anos: manancial de águas subterrâneas de Gallocanta (Espanha) Полный текст
2020
Orellana-Macías, J. M. | Merchán, D. | Causapé, J.
Evolution and assessment of a nitrate vulnerable zone over 20 years: Gallocanta groundwater body (Spain) | Evolution et évaluation d’une zone vulnérable au nitrate sur 20 ans: masse d’eau souterraine de Gallocanta (Espagne) Evolución y evaluación de una zona vulnerable a nitratos a lo largo de 20 años: la masa de agua subterránea de Gallocanta (España) 西班牙Gallocanta地下水体硝酸盐脆弱区20年的演变和评估 Evolução e avaliação de uma a zona vulnerável ao nitrato ao longo de 20 anos: manancial de águas subterrâneas de Gallocanta (Espanha) Полный текст
2020
Orellana-Macías, J. M. | Merchán, D. | Causapé, J.
Nitrate pollution from agricultural sources is one of the biggest issues facing groundwater management in the European Union (EU). During the last three decades, tens of nitrate vulnerable zones (NVZ) have been designated across the EU, aiming to make the problem more manageable. The Gallocanta Groundwater Body in NE Spain was declared as an NVZ in 1997, and after more than 20 years, significant improvements in water quality were expected to be observed. In the present study, the spatiotemporal trend of nitrate concentration within the Gallocanta NVZ in the last 38 years was assessed, and the effectiveness of the NVZ implementation was tested. Data from the official Ebro Basin Confederation monitoring network from 1980 to 2018 were used, and the results showed an increasing but fluctuating trend in nitrate concentration since 1980. Although a slight improvement was detected after the NVZ designation in 1997, the low rate of improvement would take decades to reach desirable levels in most of the area. The lack of update and control of action programmes, the inappropriate NVZ delimitation, and the influence of natural factors seem to be the reasons for the failure of the nitrate reduction measures. Currently, nitrate pollution and groundwater management are a matter of concern for the EU, so given the recurring problems in water supply in the area and the nonfulfillment of the goal of good quality status, more demanding measures are needed to be implemented in the short term.
Показать больше [+] Меньше [-]Evolution and assessment of a nitrate vulnerable zone over 20 years: Gallocanta groundwater body (Spain) Полный текст
2020
Orellana Macías, J. M. | Merchán Elena, Daniel | Causapé, Jesús | Ingeniaritza | Institute on Innovation and Sustainable Development in Food Chain - ISFOOD | Ingeniería
Nitrate pollution from agricultural sources is one of the biggest issues facing groundwater management in the European Union (EU). During the last three decades, tens of nitrate vulnerable zones (NVZ) have been designated across the EU, aiming to make the problem more manageable. The Gallocanta Groundwater Body in NE Spain was declared as an NVZ in 1997, and after more than 20 years, significant improvements in water quality were expected to be observed. In the present study, the spatiotemporal trend of nitrate concentration within the Gallocanta NVZ in the last 38 years was assessed, and the effectiveness of the NVZ implementation was tested. Data from the official Ebro Basin Confederation monitoring network from 1980 to 2018 were used, and the results showed an increasing but fluctuating trend in nitrate concentration since 1980. Although a slight improvement was detected after the NVZ designation in 1997, the low rate of improvement would take decades to reach desirable levels in most of the area. The lack of update and control of action programmes, the inappropriate NVZ delimitation, and the influence of natural factors seem to be the reasons for the failure of the nitrate reduction measures. Currently, nitrate pollution and groundwater management are a matter of concern for the EU, so given the recurring problems in water supply in the area and the nonfulfillment of the goal of good quality status, more demanding measures are needed to be implemented in the short term. | This work was undertaken thanks to a pre-doctoral grant awarded by the Government of Aragon to J. M. Orellana (BOA 20/07/2017). The work received funding from Ministerio de Economía y Competitividad via the Research Project AGRO-SOS (CGL2015–66016-R), and it was also supported by the Juan de la Cierva – Formación program, FJCI-2016-24,920; Research Project CGL2015–64284-C2–1-R awarded to D. Merchán.
Показать больше [+] Меньше [-]Fault zones in limestones: impact on karstogenesis and groundwater flow (Lez aquifer, southern France) | Zones de faille dans les calcaires: impact sur la karstogénèse et les écoulements d’eau souterraine (cas de l’aquifère du Lez, sud de la France) Zonas de falla en calizas: impacto en la karstogénesis y el flujo de aguas subterráneas (acuífero de Lez, sur de Francia) 石灰岩中断层带对岩溶作用和地下水流的影响(法国南部Lez含水层) Zonas de falha em calcários: impacto na carstogênese e no fluxo da água subterrânea (aquífero Lez, sul da França) Полный текст
2020
Clauzon, V. | Mayolle, S. | Leonardi, V. | Brunet, P. | Soliva, R. | Marchand, P. | Massonnat, G. | Rolando, J.-P. | Pistre, S.
The Lez aquifer in southern France comprises low-porosity karstified limestones and provides drinking water for ~400,000 inhabitants. Population growth and climate change have increased the stress on the water resources. In order to provide long-term protection and to optimize the water supply, the hydrogeology of the Lez aquifer must be better characterized. This study focused particularly on the St-Clément major fault zone (12 km long with a 500-m normal throw) which was structurally characterized using accurate geological mapping of the area, outcrops analysis and geophysics tools. The research highlights and explains the close relationship between the fault and the karstic occurrences. Moreover, tracer tests and piezometric head variations in boreholes have shown (1) strong interconnection between the observed karstic formations and (2) the major role of St-Clément fault on mass and pressure transfers in the aquifer. At the reservoir scale, the other major faults of the Lez aquifer, such as Corconne-Matelles or Gourg Noir faults, have shown some common morphologic and dynamic characteristics, and suggest a similar hydrogeological functioning. This study then extends this model to a larger scale. It proposes that, in aquifers of low-porosity carbonates, fault zones control the development of the main karstic network which, in turn, controls the main groundwater flows. Thus, faults should be reconsidered in order to improve the vulnerability studies and the quality of karstic aquifer modelling. Therefore, this report can contribute to protecting the groundwater resource, improving yields and optimizing groundwater supply exploitation in this type of aquifer.
Показать больше [+] Меньше [-]Hydrochemical variations of groundwater and spring discharge of the western Great Artesian Basin, Australia: implications for regional groundwater flow | Variations hydrochimiques des eaux souterraines et du débit des sources du Grand Bassin Artésien occidental en Australie: implications pour l’écoulement régional des eaux souterraines Variaciones hidroquímicas de las aguas subterráneas y de la descarga de manantiales de la Great Artesian Basin occidental, Australia: implicancias para el flujo regional de aguas subterráneas 澳大利亚大自流盆地西部地下水和泉流量的水化学变化:对区域地下水流动的影响 Variações hidroquímicas da água subterrânea e nascentes no oeste da Grande Bacia Artesiana, Austrália: implicações para o fluxo subterrâneo regional Полный текст
2020
Priestley, Stacey C. | Shand, P. (Paul) | Love, Andrew J. | Crossey, Laura J. | Karlstrom, Karl E. | Keppel, Mark N. | Wohling, Daniel L. | Rousseau-Gueutin, Pauline
The western Great Artesian Basin (GAB) is an important water source for pastoral and town water supplies, as well as for springs containing endemic flora and fauna, within arid Australia. This study focuses on the hydrochemical variations of groundwater and spring discharge in order to determine the major geochemical processes responsible for water quality and evolution across the western GAB. Regional hydrochemical trends within groundwater generally support the modern groundwater potentiometric surface and interpreted flow paths, highlighting that these approximately represent the long-term flow paths. Additionally, the regional chemical variations along the flow paths in the western GAB are complex, with their composition being a function of several controlling processes, including location of recharge, evapo-concentration, mixing and various water–rock interactions. These processes cause groundwater east of Lake Eyre to be predominantly of Na-HCO₃ type, whereas groundwater originating from the western margin is of Na-Cl-(-SO₄) type. The GAB springs appear to be discharging water predominantly from the main GAB aquifer, the J Aquifer; however, a component of the discharging water from several springs is from a source other than the J Aquifer. Current understanding of the hydrochemical variations of groundwater and spring discharge of the western GAB can help provide constraints on groundwater flow, as well as provide an understanding of the geochemical and hydrological processes responsible for water quality evolution.
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