Surface Water Levels Research Articles

Using biodiversity response for prioritizing participants and service provisions in a payment-for-water-storage program in the Everglades basin

Hydrological changes can lead to biodiversity responses that are complex and challenging to quantify. We present a framework that uses biodiversity as a criterion to address “where to buy” and “how much to buy” in a payment-for-environmental-services (PES) program focused on water storage service in the Everglades basin, USA. The PES program was designed to pay for added water storage on private cattle ranchlands by raising the spillage level in drainage control structures to reduce surface flows. We predicted that increased hydration of previously drained wetlands would benefit biodiversity, a previously unquantified but desirable co-benefit of the original program, and that a PES program offering bundled services (e.g., storage and biodiversity) can better achieve restoration goals. We quantified desirable biodiversity services (abundance of native flora and fauna such as cover of wetland and forage plants, and abundance of fishes, amphibians, and macroinvertebrates), dis-services (e.g., abundance of invasive plants and mosquitos), and hydrologic signatures (e.g., wetland water depth, inundation area and duration) at four ranches to develop eco-hydrological relationships (models) between hydrological changes and biodiversity responses. Next, a hydrologic model (MIKE-SHE/MIKE-11) was used to predict surface and subsurface water levels and flows and resulting wetland hydrologic signatures for 13 water storage alternatives on the ranches, which were used as example PES proposals. A decision-support-system (DSS) was developed to integrate (i) storage predicted by the hydrologic model, (ii) biodiversity responses predicted by eco-hydrologic models, and (iii) a user-defined preference scheme to assign importance weights to storage, biodiversity, and implementation cost. The DSS calculated a cumulative score for ranking PES proposals. By considering desirable services and dis-services, stakeholders can decide on their preferred level of services, e.g., buyer(s) may settle for less storage if there is a gain in desirable biodiversity. The DSS can identify trade-offs among services, helping stakeholders negotiate.

Design Principles and Applications of Selective Lanthanide-Based Receptors for Inorganic Phosphate.

Phosphate is an anion of both environmental and medical significance. The increase in phosphate levels in surface waters due primarily to run-offs from fertilized agricultural fields causes widespread eutrophication and increasingly large dead-zones. Hyperphosphatemia, a condition in which blood phosphate levels are elevated, is a primary cause of increased mortality and morbidity in chronic or advanced kidney disease. Resolving both of these issues require, in part, new technology that could selectively sequester phosphate in water at neutral pH. The high hydration energy of phosphate, which prevents organic receptors from functioning in water with sufficient affinity, can be overcome via coordination to a hard metal ion. The hardness, oxophilicity and lability of lanthanide ions make them excellent candidates for the design of high affinity phosphate receptors. In this perspective, we discuss how the principles of lanthanide coordination chemistry can be exploited to design sensitive and selective receptors for phosphate. Unlike many supramolecular systems, these hosts do not recognize their anionic guests via directed electrostatic and hydrogen bonding interactions. Instead, the selectivity of our fluxional receptors is governed entirely by acid-base chemistry and electrostatic forces. Parameters that affect the affinity and selectivity of the receptors include the basicities of the coordinating ligand and of the targeted anion, the acidity of the lanthanide ion, and the geometry of the ligand. Uniquely, their affinity for phosphate can be readily tuned by orders of magnitude either by peripheral interactions or by the lanthanide ion itself without affecting their exquisite selectivity over competing anions such as bicarbonate and chloride.

Residues of Cardiovascular and Lipid-Lowering Drugs Pose a Risk to the Aquatic Ecosystem despite a High Wastewater Treatment Ratio in the Megacity Shanghai, China

The residues of pharmaceuticals in surface waters of megacities and ecotoxicological implications are of particular concern. In this study, we combined field investigations and model simulations to explore the contamination of cardiovascular and lipid-lowering drugs, one group of the most prescribed medications globally, in surface waters of a typical megacity, Shanghai, with a high wastewater treatment ratio (≈96%). Among 26 target substances, 19 drugs were detected with aqueous concentrations ranging from 0.2 (ketanserin) to 715 ng/L (telmisartan). Of them, angiotensin II receptor antagonists, telmisartan and irbesartan, were dominant besides β-blockers. Spatial distribution analysis demonstrated their much higher levels in tributaries compared to the mainstream. The results of model simulations and field investigation revealed relatively low concentrations of cardiovascular and lipid-lowering drugs in surface waters of Shanghai compared to other cities in highly developed countries, which is associated with low per capita usage in China. Ecotoxicological studies in zebrafish embryos further revealed developmental effects, including altered hatching success and heart rate, by irbesartan, telmisartan, lidocaine, and their mixtures at ng/L concentrations, which are typical levels in surface waters. Overall, the present results suggest that the high wastewater treatment ratio was not sufficient to protect fish species in the aquatic ecosystem of Shanghai. Exposure to cardiovascular and lipid-lowering drugs and associated risks will further increase in the future due to healthcare improvements and population aging.

Following the fate of microplastic in four abiotic and biotic matrices along the Ticino River (North Italy)

Microplastics (MPs) are emerging contaminants in freshwater systems that have already attracted much scientific interest, but little attention has been paid to a multi-matrix analysis of MP occurrences along the length of a river. The present research provides the first record of MP contamination of four abiotic and biotic matrices from a river ecosystem simultaneously analysed. MPs were isolated and identified by micro-Fourier Transform Infrared (μ-FTIR) spectroscopy from samples collected along the Ticino River in North Italy during spring 2019. Abiotic samples were surface water (n = 18, 33 MPs m−3) and sediment (n = 18, 11 MPs kg−1), while biological samples consisted of stomach and gut content of fish (n = 18, wels catfish, Silurus glanis, 0.032 MPs g−1) and macroinvertebrates (n = 90, caddisfly larvae, Hydropsychidae, 0.03 MPs mg−1). MPs were found in biota from all stations; 44% of fish and 61% of macroinvertebrate samples contained MPs. The calculated unit-consistent concentration ratios indicate that both S. glanis and Hydropsychidae larvae had a consistent higher amount of MPs than their respective medium (sediment and water), strongly suggesting an efficient uptake pathway into organisms. MP levels in surface water, sediment, fish and macroinvertebrates were not correlated and did not increase with the river's length. From our mass balance calculations, the Ticino River transports a consistent amount of MP (yearly load of 3.40 × 1011 ± 1.1 × 1011 MPs) to the Po River. This MP load was almost half than an estimated MP load from wastewater treatment plants (WWTPs). On that basis and supported by the finding that MP concentration in sediment was mostly opposed to that in surface water but was on average 750-fold higher compared to the water matrix, we surmise that the complex hydrological network of the Ticino River retains a consistent amount of MPs which might build up over time.

Experimental Study on Head Loss Due to Cluster of Randomly Distributed Non-Uniform Roughness Elements in Supercritical Flow

Accurate estimation of head loss introduced via randomly placed roughness elements found in natural or constructed streams (e.g., fish passages) is essential in order to estimate flow variables in mountain streams, understand formation of niches for aquatic life, and model flow structure. Owing to the complexity of the involved processes and the often missing detailed data regarding the roughness elements, the head loss in such streams is mostly approximated using empirical models. In our study, we utilize flume experiments to analyze the effects of the spatial distribution of roughness elements on water surface levels and head loss and, moreover, use the produced data to test three empirical models estimating head loss. The experiments were performed in a 15 m long, 0.9 m wide flume with a slope of 5% under large Froude numbers (2.5–2.8). Flow velocities and water levels were measured with different flow rates at 58 points within a 3.96 m test section of the flume. We could show that different randomly arranged patterns of roughness elements significantly affected head loss (differences up to 33.6%), whereas water jumps occurred when flow depths were in the same size range as the roughness elements. The roughness element position and its size influenced water surface profiles. None of the three tested empirical models were able to well reproduce the differences in head loss due to the different patterns of roughness elements, with overestimated head loss from 12 to 94.7%, R2 from 41 to 73%, NSE from −21.1 to 0.09, and RRMSE from 18.4 to 93%. This generally indicates that these empirical models are conditionally suitable to consider head loss effects of random patterns of roughness elements.

Influence of Atmospheric Pressure Surges on the Level of Suprapermafrost Waters and the Flow of Small Rivers (Anadyr Lowland, Chukotka)

It is known that atmospheric pressure surges affect the discharge of underground water sources in large artesian basins. In southern latitudes, the groundwater tables change insignificantly following the diurnal variations of atmospheric pressure. There is no information on the influence of rapid changes in atmospheric pressure on the position of the surface of the suprapermafrost waters and river flow in the Arctic region. The study of the diurnal course of the level of underground suprapermafrost and surface waters was carried out to identify the links of river flow with atmospheric phenomena and cryogenic processes. It was found that the daily atmospheric pressure drop with an amplitude of 1.2 kPa in the area of the small Ugolnaya-Dionisia river, located in the Anadyr lowland in Chukotka, led to a simultaneous decrease and then an increase in the level of suprapermafrost underground and surface river basin waters by 2.5-7.8 cm. This corresponds to a short-term decrease and then an increase in the river water discharge by more than 3.5 times. To clarify the factors that determine the mechanism of the influence of atmospheric pressure on the water level and river flow, a consideration of the hydrophysical properties of aquifer-containing peat soils was carried out. Compression tests revealed that the elasticity of the peat soils horizon remains within the range of 0-15 kPa, which contributes to a dynamic change in porosity even with a slight change in the external load. This means that the atmospheric pressure changes during weather development are sufficient to modify the water capacity of peat soils and deposit them, and then discharge a part of the suprapermafrost flow. The discovered pressure impact in the tundra soils of the permafrost zone is a unique mechanism for providing plants with moisture during droughts and reducing the risk of tundra fires. As part of the further study of the pressure impact, it is planned to conduct laboratory experiments to determine the quantitative parameters of the change in the peat soils moisture capacity under pressure drops in the atmosphere. Mathematical modeling of the capillary moisture capacity of peat soils will be performed under conditions of ambient load changes. The results of experiments and theoretical studies are assumed to be useful for predicting the flow of bogged-up river basins, design of reclamation, and irrigation of areas of peat soils distribution.

Seasonal Amplitude of Water Storage Variations of the Yangtze–Huai Plain Lake Group: Implicaion for Floodwater Storage Capacity

Lakes are of significant importance in regulating floods and providing water sources. The seasonal water storage variations for the plain lake group in the Yangtze–Huai River Basin (YHRB) are significant for alleviating flood pressure and regulating runoff. However, to date, the seasonal amplitude of lake water storage variations and its capacity of buffering floodwater in the YHRB is not quantified well and remains to be investigated comprehensively. To advance the understanding of such a critical scientific issue, the water level data of the plain lake group (area>100 km2, 29 lakes) in the YHRB is collected from multi-source data between 1990 and 2020. Using lake inundation area obtained from Global Surface Water and water level variations, water storage dynamics for the plain lake group are quantified. Furthermore, this study also uses the Gravity Recovery and Climate Experiment (GRACE) products to analyze the terrestrial water storage anomalies (TWSA) in the whole basin. The results indicate that the seasonal amplitude of water level change and water storage variation of the plain lake group are 2.80 ± 0.71 m and 37.38 ± 14.19 Gt, respectively. Poyang and Dongting Lakes, two lakes that maintain the natural connection with the Yangtze River, have the most substantial seasonal amplitude in the hydrological situation. The amplitude in water level and water storage in Poyang Lake is 9.53 ± 2.02 m and 14.13 ± 5.54 Gt respectively, and that in Dongting Lake is 7.39 ± 1.29 m and 7.31 ± 3.42 Gt respectively. The contribution of seasonal variation of water storage for large plain lakes to TWSA in the YHRB is approximately 33.25%, fully reflecting these lake’s imperative position in the YHRB. This study is expected to enhance the scientific understanding of the seasonal hydrologic regime for the large lakes in the YHRB and contribute to the management of flood risks and water resources in East China.

A Robust Multi-Residue Method for the Monitoring of 25 Endocrine Disruptors at Ultra-Trace Levels in Surface Waters by Spe-Lc-Ms/Ms

A Robust Multi-Residue Method for the Monitoring of 25 Endocrine Disruptors at Ultra-Trace Levels in Surface Waters by Spe-Lc-Ms/Ms

Investigating the relationship between interannual closeness of ice coating and ice thickness in the Chukchi sea and water level variations

The hypothesis is tested that there is a significant relationship between changes in water surface level in some areas of the Chukchi Sea and variations in average ice cover thickness and cohesion in them, which can be used to refine short- and long-term forecasts of ice conditions. The results of the GLORYS12v1 global reanalysis and standard methods of mathematical statistics were used for verification. Changes in average ice cohesion were found to be correlated with changes in sea level in some areas from November to June. The correlation between sea level and average ice thickness is traceable only in December. The areas where this correlation is found include numerous sections of the coastal routes of the Northern Sea Route. It is noted that making medium- and long-term forecasts of the development of ice conditions in these areas can be significantly improved by taking into account the current changes in sea level. The identified regularities are important for ensuring safe and sustainable navigation along the Northern Sea Route during the internavigation period for independent navigation of vessels with high ice class and during the winter period when escorted by nuclear-powered icebreakers.

Динамика площади зеркала горных озер бассейна реки Гунт (Памир, Таджикистан

The article discusses mountain lakes posing threat to downstream settlements and infrastructure based on the example of Lakes Rivakkul and Nimatskul in the Gunt River Basin. In recent decades, the number and area of lakes have been growing at an accelerated rate due to the shrinking of glaciers in the target basin home to over 600 such reservoirs. The elaboration of recommendations for the installation of early warning equipment to inform population about high-mountain lake outbursts is critical for the sustainable development of the Central Asian Region. The study aimed to investigate the surface area dynamics of 2 (two) mountain lakes in the Gunt River Basin during 2000-2019. Using remote sensing data, summary data were collected on their water supply, location and surface area. The paper presents the findings obtained based on Landsat 7-8 imagery (August and September 2000-2019). The harvested data showed that 2006 witnessed the maximum increase in the area of Lake Nimatskul, whereas the same was observed for Lake Rivakkul in 2010. During the study period (from 2000 to 2019), Lake Nimatskul demonstrated a gradual surface area decrease from 0.513 to 0.462 km2, while Lake Rivakkul remained more stable. It was established that the surface area dynamics of mountain lakes are closely related to meteorological parameters, and that surface and underground runoff stabilized lake surface area and water level.

Prediction of Vistula water surface level by applying the new group method of data handling

Prediction of Vistula water surface level by applying the new group method of data handling

Hydro‐Morphodynamics of an Open‐Channel Confluence With Bed Discordance at Dynamic Equilibrium

AbstractThis study examines the hydrodynamics and morphodynamics of open‐channel confluences characterized by subcritical flow, low flow discharge ratio, a 90° junction angle and dominant sediment supply coming from the tributary. The analysis is based on a novel data set comprised of the three‐dimensional time‐averaged velocity field, turbulence, bed morphology, and water surface levels acquired under controlled conditions in a laboratory setup. Confluence morphology at equilibrium stage was characterized by moderate bed discordance and pronounced bed erosion at the junction. This study suggests an updated conceptual model of flow hydrodynamics in realistic morphologically stable confluences. The near‐bed flow from the main channel proceeds underneath the tributary inflow into the tributary where it engages in the rotational motion of a strong secondary circulation observed within and downstream of the junction. The high‐speed near‐bed flow intensifies the stretching of the secondary cell past the downstream junction corner where it expands and aligns with slope of the bank‐attached bar. It is argued that the post‐confluence secondary cell is a result of flow separation at the tributary‐mouth bar and of the curvature of the shear layer, configuring a Prandtl’s first kind of helical flow.

Climate change and its effects on the water level of Lake Baikal region since the 1980s

气候变化对湖泊水位的影响是湖泊研究的关注热点.作为欧亚大陆最大淡水湖，贝加尔湖水位变化深受自然因素和人类活动的共同影响.在全球变暖背景下，贝加尔湖水位升降将对维系流域生态系统与社会发展至关重要.为此，基于湖区气象站、水文站和湖泊水位观测数据，采用突变检验、变异系数检验等方法，分析了过去40年贝加尔湖周边气候变化及其对水位的影响.主要结论如下：1980-2019年，贝加尔湖及其周边区域气温整体呈显著上升趋势（0.31℃/10 a），其空间分布主要受纬度和海拔影响；年际降水波动较大（变异系数达0.2左右），但变化趋势不显著，其空间分布主要影响因素为地形.过去40年，贝加尔湖平均水位为456.42 m，水位发生多次大幅波动.1980-2015年，色楞格河和安加拉河径流量总体呈先增加后减少的变化格局，是导致贝加尔湖水位先上升后下降的重要原因.而入湖、出湖径流的高低主要受控于降水的多寡.通径分析结果表明，降水是影响贝加尔湖水位变化的主要气象因素，降水通过直接补给和入湖径流补给共同影响贝加尔湖水位.本文将水位转折的原因大致划分为3类：第1类是气候变化驱动型，指1982-1983、1985-1987和2013-2015年这3个阶段的水位突变过程；第2类是气候变化与人类活动共同驱动型，以1995-1996年水位大幅下降过程为例，气候变化与流域内人类活动共同导致了水位突变；第3种类型是气候变化背景下的人为调控驱动型，这是贝加尔湖特有的水位变化驱动类型，即俄罗斯联邦政府立法通过下游水利枢纽工程人为调控湖泊水位.由于持续的暖干气候条件，贝加尔湖2015-2017年水位被严格控制在456.07 m左右的低水位.本研究将为贝加尔湖未来气候变化预估、后续水位调控以及流域灾害防控提供理论支撑.;The impact of climate change on lakes is one of the lake research foci. As the largest freshwater lake in Eurasia, Lake Baikal is impacted by both the natural environment and human activities. Hence, it is indispensable to discuss how Lake Baikal will change with global warming to guarantee the watershed ecological balance and regional sustainable development. We, therefore, analyzed the climate change in the Lake Baikal region and its impacts on the water surface level of Lake Baikal over the past 40 years, with the coefficient of variation test and multi-methods of abrupt change test using the observation data from meteorological stations, hydrological stations and water level of the lake surface. The main conclusions are summarized as follows. From 1980 to 2019, the annual average temperature around Lake Baikal shows a significant rising trend of 0.31℃/10 a, and its spatial distribution is mainly affected by latitude and altitude. The annual average precipitation fluctuates remarkably with a variation coefficient of about 0.2, and the overall variation trend is not significant. The main controlling factor of its spatial distribution is topography. In the past 40 years, Lake Baikal's average water level is 456.42 m, and the water level has undergone several sharp changes. The runoff in Selenga River and Angara River increases first and then decreases during 1980-2015, leading to the water level changes of Lake Baikal synchronously. The results of path analysis show that precipitation is the main meteorological factor affecting the water level of Lake Baikal. Precipitation affects the water level of Lake Baikal through both direct recharge and runoff recharge. We roughly divide the causes of water level transition into three categories. The first type is the climate change-driven type, which refers to the abrupt changes in water level during 1982-1983, 1985-1987, and 2013-2015. The second type is the combination of climate change and anthropogenic activities. Taking the dramatic decline of water level in 1995-1996 as an example, climate change and the increase of human water use in the basin led to the dramatic shift in water level. The third type is government regulation control with climate change, which is unique to Lake Baikal. That is, the government regulates the water level of the lake artificially through the downstream hydroelectric facilities. Due to the continuous warm and dry climate conditions, Lake Baikal's water level is strictly controlled at a low value of 456.07 m from 2015 to 2017. This study hopefully will provide theoretical support for the projection of climate change, water level control, and disaster prevention of Lake Baikal Basin.

Novel Time Series Bagging Based Hybrid Models for Predicting Historical Water Levels in the Mekong Delta Region, Vietnam

Water level predictions in the river, lake and delta play an important role in flood management. Every year Mekong River delta of Vietnam is experiencing flood due to heavy monsoon rains and high tides. Land subsidence may also aggravate flooding problems in this area. Therefore, accurate predictions of water levels in this region are very important to forewarn the people and authorities for taking timely adequate remedial measures to prevent losses of life and property. There are so many methods available to predict the water levels based on historical data but nowadays Machine Learning (ML) methods are considered the best tool for accurate prediction. In this study, we have used surface water level data of 18 water level measurement stations of the Mekong River delta from 2000 to 2018 to build novel time-series Bagging based hybrid ML models namely: Bagging (RF), Bagging (SOM) and Bagging (M5P) to predict historical water levels in the study area. Performances of the Bagging-based hybrid models were compared with Reduced Error Pruning Trees (REPT), which is a benchmark ML model. The data of 19 years period was divided into 70:30 ratio for the modeling. The data of the period 1/2000 to 5/2013 (which is about 70% of total data) was used for the training and for the period 5/2013 to 12/2018 (which is about 30% of total data) was used for testing (validating) the models. Performance of the models was evaluated using standard statistical measures: Coefficient of Determination (R2), Root Mean Square Error (RMSE) and Mean Absolute Error (MAE). Results show that the performance of all the developed models is good (R2 > 0.9) for the prediction of water levels in the study area. However, the Bagging-based hybrid models are slightly better than another model such as REPT. Thus, these Bagging-based hybrid time series models can be used for predicting water levels at Mekong data.

Runoff evolution and wetland ecological response in Lake Baiyangdian Basin in recent 60 years

白洋淀是雄安新区的核心生态功能区，近几十年来面临水源不足、湿地萎缩等生态环境问题.选取白洋淀流域上游王快、西大洋及拒马河3个子流域开展河川径流演变研究，结合1969年以来18期白洋淀湿地遥感影像，揭示白洋淀流域河川径流驱动湿地演变的过程机制.结果表明：近60年来白洋淀流域山区径流量呈持续衰减趋势，从P1阶段（1961—1979年）至P3阶段（1997—2019年），典型子流域年径流系数均值由0.29降至0.12，山区年径流总量由30.84×10⁸ m³/a降至11.37×10⁸ m³/a，降幅达63.1%，梯田修建、地下水开采等人类活动是导致径流衰减的主要原因；不同子流域产流和基流减少对径流衰减的贡献率存在差异，以变质岩为主的王快子流域径流衰减的主要原因是地表产流减少，碳酸盐岩分布较广的拒马河子流域径流衰减的主要原因是基流减少；白洋淀湿地面积变化受控于地表水位波动，近60年来白洋淀湿地退化的直接原因是入淀流量减少，根本原因是人类活动影响导致的山区径流衰减.;Baiyangdian Wetland is the main ecological functional area of Xiong'an New Area. In recent decades, Baiyangdian Wetland has been faced with ecological and environmental problems, such as water shortage and wetland degradation. Three typical sub-basins (Wangkuai, Xidayang and Juma River) in the upper reaches of Lake Baiyangdian Basin were selected to study the runoff evolution in the past 60 years. Based on 18 remote sensing images of Lake Baiyangdian Wetland since 1969, the evolution process of Lake Baiyangdian Wetland was analyzed. The results showed that the mountain runoff in Lake Baiyangdian Basin decreased continuously in the past 60 years. From P1 (1961-1979) to P3(1997-2019), the average annual runoff coefficient in typical basins decreased from 0.29 to 0.12, and the total annual runoff in mountainous areas decreased from 30.84×10⁸ m³/a to 11.37×10⁸ m³/a, decreasing by 63.1%. Human activities such as terrace construction and groundwater exploitation are the main causes of runoff attenuation. There are differences in runoff and baseflow reduction in different sub-basins. The lithology of Wangkuai sub-basins is mainly metamorphic rock. The main reason for runoff attenuation is the decrease in surface runoff. The karst strata in the Juma River basin are widely distributed, and the main reason for runoff attenuation is the decrease in base flow. The direct factor affecting the area of Lake Baiyangdian Wetland is the fluctuation of surface water level. The decrease of water inflow is the direct cause of the degradation of Lake Baiyangdian Wetland in recent 60 years, and the fundamental reason is the attenuation of mountain runoff caused by human activities.

Determination of β-N-Methylamino-L-Alanine (BMAA) Levels in Surface Water and Treated Water by Liquid Chromatography-Tandem Mass Spectrometry

β-Methylamino-L-alanine (BMAA) is an emerging algal toxin that has drawn attention because it can cause neurodegenerative diseases, including Parkinson's disease and Alzheimer's disease (AD). Therefore, it is necessary to develop a sensitive analytical method for BMAA, an emerging cyanobacterial toxin, to determine whether a trace amount is detected in the water resources and treated water. In this study, we developed a simple and sensitive analytical method for BMAA using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with direct injection. The method was validated for linearity of calibration, limit of detection, limit of quantitation, accuracy, and precision. The limits of detection and quantitation were in the range of 0.030 ?/L and 0.096 ?/L, respectively. The optimized method was used to measure the concentrations of BMAA in surface water from each weir point of the Geum River, Nakdong River. Sampling and analysis of drinking water treatment plants of the Geum River, Nakdong River were applied to samples for each process.

Variations and driving mechanism of dissolved arsenic in sediment porewater near wetland

The special hydrogeological conditions of wetland easily lead to the formation of high-arsenic (As) groundwater. However, it is unclear relative contribution of wetland water (surface water) dissolved organic matter (DOM) and sedimentary organic matter (SOM) to porewater DOM and its relations with dissolved As under the wetland. Porewater, groundwater and sediment samples were taken to monitor spatial-temporal variations in dissolved As affected by fluctuation of surface water levels near a typical wetland with high As groundwater in the arid-semiarid Hetao Basin, China. Hydrochemical data showed that As concentrations of sediment porewater (average: 17.1 μg/L) lay between As concentrations of surface water (average: 6.48 μg/L) and groundwater (average: 184 μg/L). A long-term observation showed concentrations of dissolved As, Fe, and dissolved organic carbon (DOC) of porewater obviously increased when levels of surface water rose during waterlogging period. There were positive correlations between dissolved As and Fe (r = 0.69, p < 0.01) and dissolved As and DOC (r = 0.38, p < 0.01). The sequential extraction showed that the main As form in sediment was amorphous Fe(III) oxide-coprecipitated form (averagely 45.0% of total As). It indicates that the dissolved As in porewater mainly originated from the Fe(III) oxide-bound forms in the sediment. Fluorescence indices and parallel factor analysis of the three-dimensional fluorescence spectra showed that porewater DOM mainly derived mainly from SOM during the drought period and from both surface water DOM and SOM during the waterlogging period. Higher proportions of As(III) in porewaters during waterlogging period were observed relative to those during drought period, indicating that surface water infiltration led to relatively reducing conditions. Surface water infiltration introduced DOM and stimulated the release of SOM into the porewater. DOM, acting as electron donor and electron shuttle, triggered the reductive dissolution of Fe(III) oxides, leading to the As mobilization under the wetland. This study suggests that drinking water supply near wetlands should be concerned, since high concentrations of dissolved As normally occurred in shallow aquifers near the wetland.

Effect of Ota Industrial Estate effluents on surface water quality of Oruku River, Ota, South Western Nigeria

The effect of industrial effluents on surface water quality of Oruku River was investigated in this study by analyzing selected water quality indicators such as pH, dissolved oxygen (DO) and total dissolved solids (TDS) were examined amongst other physicochemical parameters using standard methods. Results show that, average pH of the surface waters ranged from 5.53±0.31 to 6.23±0.45 with SR3 having the highest value. This indicates that all the water sources were alkaline. The effluents had an average pH range of 5.95 ± 1.12 to 6.40 ± 0.48. A comparison of these average pH values with effluent quality standards indicated that the effluents pH were below limit (6.5-9.5). The average BOD levels in surface water ranged from 1.94 ± 0.95 for SR-4 to 3.78 ± 1.61 for SR-1. DO average values in surface water was found to be higher at SR-1 with a mean value of 5.36 ± 1.55 and lower at SR-2 with a mean value of 3.05 ± 0.68. The mean COD value for surface water ranged from 108.66 ± 73.03mg/L to 232.81 ± 155.46mg/L. SR-3 had the highest COD average value of 232.81 ± 155.46mg/L while there was a reduction at SR-5 to an average value of 108.66 ± 73.03mg/L. The high COD value in the surface water indicates that gross-organic pollution of the water source may be from other sources such as agricultural and urban run-offs.

Groundwater Recharge Assessment Using Multi Component Analysis: Case Study at the NW Edge of the Varaždin Alluvial Aquifer, Croatia

Exploring the interaction between precipitation, surface water, and groundwater has been a key subject of many studies dealing with water quality management. The Varaždin aquifer is an example of an area where high nitrate content in groundwater raised public concern, so it is important to understand the aquifer recharge for proper management and preservation of groundwater quality. The NW part of the Varaždin aquifer has been selected for study area, as precipitation, Drava River, accumulation lake, and groundwater interact in this area. In this study, groundwater and surface water levels, water temperature, water isotopes (2H and 18O), and chloride (Cl−) were monitored in precipitation, surface water, and groundwater during the four-year period to estimate groundwater recharge. Head contour maps were constructed based on the groundwater and surface water levels. The results show that aquifer is recharged from both Drava River and accumulation lake for all hydrological conditions–low, mean, and high groundwater levels. The monitoring results of water temperature, chloride content, and stable water isotopes were used as tracers, i.e. as an input to the mixing model for estimation of the contribution ratio from each recharge source. The calculation of mixing proportions showed that surface water is a key mechanism of groundwater recharge in the study area, with a contribution ratio ranging from 55% to 100% depending on the proximity of the observation well to surface water.

Enhancement of a global lake and reservoir database to aid climate studies and resource monitoring utilizing satellite radar altimetry

Here, we describe the expansion and enhancement of a large (surface area ≥100 km2) lake and reservoir database (1.GREALD). These efforts have also resulted in the spin-off of two additional databases, one containing lakes and reservoirs (2.GREALD, area 10–99 km2), and the other containing ephemeral lakes (3.GELD, area ≥100 km2). These databases are unique sources for projects that utilize satellite radar altimeter data to monitor surface water levels. While 1.GREALD aims to be a complete catalog, 2.GREALD focuses on reservoirs in response to applied sciences programs that monitor water and energy resources. The creation of 3.GELD has climate change objectives as well as water resources and ecosystem conservation applications. The recording of information pertaining to the potential overpasses (waterbody crossings) of the current and archive satellite altimeters is a primary objective as is the need to highlight any form of controlled water level variation. The permanent water databases now contain 6282 entries, half experience some form of anthropogenic influence and ∼430 have been identified as potential climatically sensitive terminal lakes. The revised integral surface area distribution is a power law with exponent −1.016. Statistics reveal that with altimetric repeat visit times of 10-day to monthly, at least 80% of the permanent water bodies (≥10 km2) have been overflown at some period since the 1990s. Current information on water use and reservoir formation date show that the primary use of the reservoir class is hydroelectric power, and that China, Brazil, India, Turkey, and Vietnam dominate the dam building in recent decades.